WorldWideScience

Sample records for silica aerogel monoliths

  1. Monolithic Silica aerogel in superinsulating glazings

    DEFF Research Database (Denmark)

    Duer, Karsten; Svendsen, Sv Aa Højgaard

    1988-01-01

    technique were manufactured and characterized for their optical and thermal properties. As expected the same scattering of light was found in the aerogel glazings as in the aerogel samples, but excellent thermal performance was found, indicating a glazing type that from a thermal point of view is without......Silica aerogel is an open-pored porous transparent material with optical and thermal properties that makes the material very interesting as an insulation material in windows. A number of different aerogels have been investigated for their optical and thermal performance. High thermal resistance...... of aerogel was found for all the investigated samples and the samples showed very high solar as well as light transmittance. However all the investigated aerogel samples showed a tendency to scatter the transmitted light resulting in a reduced optical quality when the aerogels are integrated in glazings...

  2. Monolithic silica aerogel - material design on the nano-scale

    DEFF Research Database (Denmark)

    Jensen, Karsten Ingerslev; Schultz, Jørgen Munthe; Kristiansen, Finn Harken

    of piezoelectric transducers. - Other applications could be; waste encapsulation, spacers for vacuum insulation panels, membranes, etc. Department of Civil Engineering is co-ordinator of a current EU FP5 research project1, which deals with the application of aerogel as transparent insulation materials in windows......By means of a production process in two major steps - a sol/gel process and a supercritical drying – open-cell, monolithic silica aerogel can be made. This material can have a density in the range of 30- to 300 kg/m3, corresponding to porosities between 86 and 98 %. The solid structure has...... characteristic dimensions of 2 – 5 nm and the typical pore diameter is about 20 nm. A number of different applications of aerogel have been proposed: - Because of the large internal surface of aerogel (up to 1000 m²/g), the material is proposed to serve as substrate for catalytic materials. - The special pore...

  3. Synthesis of silica aerogel monoliths with controlled specific surface areas and pore sizes

    Science.gov (United States)

    Gao, Bingying; Lu, Shaoxiang; Kalulu, Mulenga; Oderinde, Olayinka; Ren, Lili

    2017-07-01

    To replace traditional preparation methods of silica aerogels, a small-molecule 1,2-epoxypropane (PO) has been introduced into the preparation process instead of using ammonia as the cross-linking agent, thus generating a lightweight, high porosity, and large surface area silica aerogel monolithic. We put forward a simple solution route for the chemical synthesis of silica aerogels, which was characterized by scanning electron microscopy (SEM), TEM, XRD, FTIR, thermogravimetric analysis (TGA) and the Brunauer-Emmett-Teller (BET) method In this paper, the effect of the amount of PO on the microstructure of silica aerogels is discussed. The BET surface areas and pore sizes of the resulting silica aerogels can be freely adjusted by changing the amount of PO, which will be helpful in promoting the development of silica aerogels to fabricate other porous materials with similar requirements. We also adopted a new organic solvent sublimation drying (OSSD) method to replace traditional expensive and dangerous drying methods such as critical point drying and freeze drying. This simple approach is easy to operate and has good repeatability, which will further facilitate actual applications of silica aerogels.

  4. On the improvement of mechanical properties of monolithic silica aerogels (for transparent insulating material); Silica aerogel (tomei dannetsu zairyo) kyodo no kaizen ni tsuite

    Energy Technology Data Exchange (ETDEWEB)

    Tajiri, K.; Igarashi, K.; Tanemura, S. [National Industrial Research Institute of Nagoya, Nagoya (Japan)

    1997-11-25

    Study was made on improvement of the strength of silica aerogel as transparent insulating material. Silica aerogel is a low-density porous material with high heat insulation and transparency. To develop a insulating material with high transparency, monolithic silica aerogel was studied. For direct use of it for windows, its strength improvement was attempted. The aerogel was prepared by supercritical drying (alcohol or CO2) of silica wet gel obtained by hydrolysis and condensation of silicon alkoxide solution. To prepare the aerogel bonded on plate glass for strength improvement, the aerogel was bonded to alkoxide by exposing active silanol radical through F-etching of plate glass surface. However, to obtain the practical large-area bonded aerogel, shrinkage control of the aerogel in supercritical drying was necessary. Addition of Laponite into a silica network for strength improvement by polymer increased the bending strength by 50%. Although some reduction of its transparency was observed because of clouding, its heat insulation was stable. Further strength improvement is necessary for its practical use. 5 figs., 1 tab.

  5. Epoxy Crosslinked Silica Aerogels (X-Aerogels)

    Science.gov (United States)

    fabrizio, Eve; Ilhan, Faysal; Meador, Mary Ann; Johnston, Chris; Leventis, Nicholas

    2004-01-01

    NASA is interested in the development of strong lightweight materials for the dual role of thermal insulator and structural component for space vehicles; freeing more weight for useful payloads. Aerogels are very-low density materials (0.010 to 0.5 g/cc) that, due to high porosity (meso- and microporosity), can be, depending on the chemical nature of the network, ideal thermal insulators (thermal conductivity approx. 15 mW/mK). However, aerogels are extremely fragile. For practical application of aerogels, one must increase strength without compromising the physical properties attributed to low density. This has been achieved by templated growth of an epoxy polymer layer that crosslinks the "pearl necklace" network of nanoparticles: the framework of a typical silica aerogel. The requirement for conformal accumulation of the epoxy crosslinker is reaction both with the surface of silica and with itself. After cross-linking, the strength of a typical aerogel monolith increases by a factor of 200, in the expense of only a 2-fold increase in density. Strength is increased further by coupling residual unreacted epoxides with diamine.

  6. Cellulose-silica aerogels.

    Science.gov (United States)

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

    2015-05-20

    Aerogels based on interpenetrated cellulose-silica networks were prepared and characterised. Wet coagulated cellulose was impregnated with silica phase, polyethoxydisiloxane, using two methods: (i) molecular diffusion and (ii) forced flow induced by pressure difference. The latter allowed an enormous decrease in the impregnation times, by almost three orders of magnitude, for a sample with the same geometry. In both cases, nanostructured silica gel was in situ formed inside cellulose matrix. Nitrogen adsorption analysis revealed an almost threefold increase in pores specific surface area, from cellulose aerogel alone to organic-inorganic composite. Morphology, thermal conductivity and mechanical properties under uniaxial compression were investigated. Thermal conductivity of composite aerogels was lower than that of cellulose aerogel due to the formation of superinsulating mesoporous silica inside cellulose pores. Furthermore, composite aerogels were stiffer than each of reference aerogels. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. 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)

  8. Prospect of Thermal Insulation by Silica Aerogel: A Brief Review

    Science.gov (United States)

    Hasan, Mohammed Adnan; Sangashetty, Rashmi; Esther, A. Carmel Mary; Patil, Sharanabasappa B.; Sherikar, Baburao N.; Dey, Arjun

    2017-10-01

    Silica aerogel is a unique ultra light weight nano porous material which offers superior thermal insulation property as compared to the conventional thermal insulating materials. It can be applied not only for ground and aerospace applications but also in low and high temperatures and pressure regimes. Aerogel granules and monolith are synthesized by the sol-gel route while aerogel based composites are fabricated by the reinforcement of fibers, particle and opacifiers. Due to the characteristic brittleness (i.e., poor mechanical properties) of monolith or bulk aerogel, it is restricted in several applications. To improve the mechanical integrity and flexibility, usually different fibers are reinforced with aerogel and hence it can be used as flexible thermal insulation blankets. Further, to achieve effective thermal insulation behaviour particularly at high temperature, often opacifiers are doped with silica aerogel. In the present brief review, the prospects of bulk aerogel and aerogel based composites are discussed for the application of thermal insulation and thermal stability.

  9. Transparent monolithic metal ion containing nanophase aerogels

    Energy Technology Data Exchange (ETDEWEB)

    Risen, W. M., Jr.; Hu, X.; Ji, S.; Littrell, K.

    1999-12-01

    The formation of monolithic and transparent transition metal containing aerogels has been achieved through cooperative interactions of high molecular weight functionalized carbohydrates and silica precursors, which strongly influence the kinetics of gelation. After initial gelation, subsequent modification of the ligating character of the system, coordination of the group VIII metal ions, and supercritical extraction afford the aerogels. The structures at the nanophase level have been probed by photon and electron transmission and neutron scattering techniques to help elucidate the basis for structural integrity together with the small entity sizes that permit transparency in the visible range. They also help with understanding the chemical reactivities of the metal-containing sites in these very high surface area materials. These results are discussed in connection with new reaction studies.

  10. Silica Aerogel: Synthesis and Applications

    Directory of Open Access Journals (Sweden)

    Jyoti L. Gurav

    2010-01-01

    Full Text Available Silica aerogels have drawn a lot of interest both in science and technology because of their low bulk density (up to 95% of their volume is air, hydrophobicity, low thermal conductivity, high surface area, and optical transparency. Aerogels are synthesized from molecular precursors by sol-gel processing. Special drying techniques must be applied to replace the pore liquid with air while maintaining the solid network. Supercritical drying is most common; however, recently developed methods allow removal of the liquid at atmospheric pressure after chemical modification of the inner surface of the gels, leaving only a porous silica network filled with air. Therefore, by considering the surprising properties of aerogels, the present review addresses synthesis of silica aerogels by the sol-gel method, as well as drying techniques and applications in current industrial development and scientific research.

  11. The monolithic carbon aerogels and aerogel composites for electronics and thermal protection applications

    Science.gov (United States)

    Lu, Sheng; Guo, Hui; Zhou, Yugui; Liu, Yuanyuan; Jin, Zhaoguo; Liu, Bin; Zhao, Yingmin

    2017-09-01

    Monolithic carbon aerogels have been prepared by condensation polymerization and high temperature pyrolysis. The morphology of carbon aerogels are characterized by SEM. The pore structure is characterized by N2 adsorption-desorption technique. Monolithic carbon aerogels are mesoporous nanomaterials. Carbon fiber reinforced carbon aerogel composites are prepared by in-situ sol-gel process. Fiber reinforced carbon aerogel composites are of high mechanical strength. The thermal response of the fiber reinforced aerogel composite samples are tested in an arc plasma wind tunnel. Carbon aerogel composites show good thermal insulation capability and high temperature resistance in inert atmosphere even at ultrahigh temperature up to 1800 °C. The results show that they are suitable for applications in electrodes for supercapacitors/ Lithium-ion batteries and aerospace thermal protection area.

  12. Evacuated aerogel glazings

    DEFF Research Database (Denmark)

    Schultz, Jørgen Munthe; Jensen, Karsten Ingerslev

    2008-01-01

    This paper describes the main characteristics of monolithic silica aerogel and its application in evacuated superinsulating aerogel glazing including the evacuation and assembling process. Furthermore, the energetic benefit of aerogel glazing is quantified. In evacuated aerogel glazing the space...... between the glass panes is filled with monolithic silica aerogel evacuated to a rough vacuum of approximately 1-10 hPa. The aerogel glazing does not depend on use of low emissive coatings that have the drawback of absorbing a relatively large part of the solar radiation that otherwise could reduce...

  13. X-ray radiographic technique for measuring density uniformity of silica aerogel

    International Nuclear Information System (INIS)

    Tabata, Makoto; Hatakeyama, Yoshikiyo; Adachi, Ichiro; Morita, Takeshi; Nishikawa, Keiko

    2013-01-01

    This paper proposes a new X-ray radiographic technique for measuring density uniformity of silica aerogels used as radiator in proximity-focusing ring-imaging Cherenkov detectors. To obtain high performance in a large-area detector, a key characteristic of radiator is the density (i.e. refractive index) uniformity of an individual aerogel monolith. At a refractive index of n=1.05, our requirement for the refractive index uniformity in the transverse plane direction of an aerogel tile is |δ(n−1)/(n−1)|<4% in a focusing dual layer radiator (with different refractive indices) scheme. We applied the radiographic technique to evaluate the density uniformity of our original aerogels from a trial production and that of Panasonic products (SP-50) as a reference, and to confirm they have sufficient density uniformity within ±1% along the transverse plane direction. The measurement results show that the proposed technique can quantitatively estimate the density uniformity of aerogels.

  14. Monolithic three-dimensional electrochemical energy storage system on aerogel or nanotube scaffold

    Science.gov (United States)

    Farmer, Joseph C; Stadermann, Michael

    2013-11-12

    A monolithic three-dimensional electrochemical energy storage system is provided on an aerogel or nanotube scaffold. An anode, separator, cathode, and cathodic current collector are deposited on the aerogel or nanotube scaffold.

  15. Novel bioactive materials: silica aerogel and hybrid silica aerogel/pseudowollastonite

    Directory of Open Access Journals (Sweden)

    Reséndiz-Hernández, P. J.

    2014-10-01

    Full Text Available Silica aerogel and hybrid silica aerogel/pseudowollastonite materials were synthesized by controlled hydrolysis of tetraethoxysilane (TEOS using also methanol (MeOH and pseudowollastonite particles. The gels obtained were dried using a novel process based on an ambient pressure drying. Hexane and hexamethyl-disilazane (HMDZ were the solvents used to chemically modify the surface. In order to assess bioactivity, aerogels, without and with pseudowollastonite particles, were immersed in simulated body fluid (SBF for 7 and 14 days. The hybrid silica aerogel/pseudowollastonite showed a higher bioactivity than that observed for the single silica aerogel. However, as in both cases a lower bioactivity was observed, a biomimetic method was also used to improve it. In this particular method, samples of both materials were immersed in SBF for 7 days followed by their immersion in a more concentrated solution (1.5 SBF for 14 days. A thick and homogeneous bonelike apatite layer was formed on the biomimetically treated materials. Thus, bioactivity was successfully improved even on the aerogel with no pseudowollastonite particles. As expected, the hybrid silica aerogel/pseudowollastonite particles showed a higher bioactivity.Se sintetizaron aerogel de sílice y aerogel híbrido de sílice/partículas de pseudowollastonita por hidrólisis controlada de tetraetoxisilano (TEOS usando metanol (MeOH y partículas de pseudowollastonita. Los geles obtenidos se secaron utilizando un novedoso proceso basado en una presión de secado ambiental. Hexano y hexametil-disilazano fueron los solventes usados para modificar químicamente la superficie. Para evaluar la bioactividad, los aerogeles con y sin partículas de pseudowollastonita se sumergieron en un fluido fisiológico simulado (SBF por 7 y 14 días. El aerogel híbrido de sílice/partículas de pseudowollastonita mostró más alta bioactividad que la observada por el aerogel solo. Sin embargo, en ambos casos, se

  16. Preparation of silica aerogel for Cerenkov counters

    International Nuclear Information System (INIS)

    Poelz, G.; Riethmueller, R.

    1981-09-01

    Aerogel of silica was produced with an index of refraction of n = 1.024 to equip the TASSO Cerenkov detector with 1700 litres of this radiator medium. In the production process, which is described in detail, different parameters were varied to determine their influence on the shape and the optical quality of the aerogel samples. With the present equipment samples with a size of 17 x 17 x 2.3 cm 3 were manufactured at a rate of 144 pieces per week. A production efficiency of about 90% was obtained. The index of refraction for all samples around n = 1.024 is distributed with sigmasub(n) = 1.3 x 10 -3 . They have an optical transmission length of Λ = 2.64 cm at a wavelength lambda = 438 nm with sigmasub(Λ) = 0.22 cm. For samples with n = 1.017, Λ is found to be about 30% higher. (orig.) [de

  17. Vanadia-silica aerogels from vanadylacetylacetonate

    Energy Technology Data Exchange (ETDEWEB)

    Klett, U.; Fricke, J. [Bavarian Center for Applied Energy Research (ZAE)/Physikalisches Institut der Universitaet Wuerzburg, Am Hubland, D-97074 Wuerzburg (Germany)

    1998-04-15

    For the preparation of vanadium pentoxide doped silica gels, vanadium(V) oxide trialkoxides are the precursors of choice as they possess already the desired oxidation number. In vanadylacetylacetonate, the oxidation number of vanadium is only +4 instead of +5. However, vanadylacetylacetonate is less reactive with water and thus easier to handle, less toxic and cheaper than vanadium(V) oxide triisopropoxide. Gels were prepared using vanadylacetylacetonate, tetramethoxysilane, methanol and water containing HCl or NH{sub 3} as catalyst. After supercritical drying with respect to CO{sub 2} and heat treatment in air, vanadia doped silica aerogels show the same colour change upon adsorption of water molecules as vanadium(V) oxide triisopropoxide doped silica xerogels. Structural properties were investigated by N{sub 2}-absorption and SAXS measurements

  18. From 1D to 3D - macroscopic nanowire aerogel monoliths

    Science.gov (United States)

    Cheng, Wei; Rechberger, Felix; Niederberger, Markus

    2016-07-01

    Here we present a strategy to assemble one-dimensional nanostructures into a three-dimensional architecture with macroscopic size. With the assistance of centrifugation, we successfully gel ultrathin W18O49 nanowires with diameters of 1 to 2 nm and aspect ratios larger than 100 into 3D networks, which are transformed into monolithic aerogels by supercritical drying.Here we present a strategy to assemble one-dimensional nanostructures into a three-dimensional architecture with macroscopic size. With the assistance of centrifugation, we successfully gel ultrathin W18O49 nanowires with diameters of 1 to 2 nm and aspect ratios larger than 100 into 3D networks, which are transformed into monolithic aerogels by supercritical drying. Electronic supplementary information (ESI) available: Experimental details, SEM and TEM images, and digital photographs. See DOI: 10.1039/c6nr04429h

  19. Aerogel

    Indian Academy of Sciences (India)

    dried in an autoclave at supercritical conditions of the respective alcohol. As a result, a highly porous, low density, large surface area silica aerogel is produced. What is so special about the aerogel? The microstructure of the aerogel resembles a bunch of pearl necklaces heaped on a table. --------~~------. 66. RESONANCE I ...

  20. Aerogel

    Indian Academy of Sciences (India)

    It certainly looks like a whiff of smoke frozen into immobility. If you happen to hold a tile of silica aerogel, commonly called silica air-glass, you would feel practically no weight in your hands. But your mind may well be loaded with a number of questions about its origin, its structure and its properties. Aerogel is a highly porous ...

  1. Quantitative analysis of silica aerogel-based thermal insulation coatings

    DEFF Research Database (Denmark)

    Kiil, Søren

    2015-01-01

    A mathematical heat transfer model for a silica aerogel-based thermal insulation coating was developed. The model can estimate the thermal conductivity of a two-component (binder-aerogel) coating with potential binder intrusion into the nano-porous aerogel structure. The latter is modelled using...... a so-called core–shell structure representation. Data from several previous experimental investigations with silica aerogels in various binder matrices were used for model validation. For some relevant cases with binder intrusion, it was possible to obtain a very good agreement between simulations...... containing intact hollow glass or polymer spheres showed that silica aerogel particles are more efficient in an insulation coating than hollow spheres. In a practical (non-ideal) comparison, the ranking most likely cannot be generalized. A parameter study demonstrates how the model can be used, qualitatively...

  2. In vivo ultrasonic detection of polyurea crosslinked silica aerogel implants.

    Directory of Open Access Journals (Sweden)

    Firouzeh Sabri

    Full Text Available BACKGROUND: Polyurea crosslinked silica aerogels are highly porous, lightweight, and mechanically strong materials with great potential for in vivo applications. Recent in vivo and in vitro studies have demonstrated the biocompatibility of this type of aerogel. The highly porous nature of aerogels allows for exceptional thermal, electric, and acoustic insulating capabilities that can be taken advantage of for non-invasive external imaging techniques. Sound-based detection of implants is a low cost, non-invasive, portable, and rapid technique that is routinely used and readily available in major clinics and hospitals. METHODOLOGY: In this study the first in vivo ultrasound response of polyurea crosslinked silica aerogel implants was investigated by means of a GE Medical Systems LogiQe diagnostic ultrasound machine with a linear array probe. Aerogel samples were inserted subcutaneously and sub-muscularly in a fresh animal model and b cadaveric human model for analysis. For comparison, samples of polydimethylsiloxane (PDMS were also imaged under similar conditions as the aerogel samples. CONCLUSION/SIGNIFICANCE: Polyurea crosslinked silica aerogel (X-Si aerogel implants were easily identified when inserted in either of the regions in both fresh animal model and cadaveric model. The implant dimensions inferred from the images matched the actual size of the implants and no apparent damage was sustained by the X-Si aerogel implants as a result of the ultrasonic imaging process. The aerogel implants demonstrated hyperechoic behavior and significant posterior shadowing. Results obtained were compared with images acquired from the PDMS implants inserted at the same location.

  3. Thermoresponsive Polyrotaxane Aerogels: Converting Molecular Necklaces into Tough Porous Monoliths.

    Science.gov (United States)

    Wang, Jin; Du, Ran; Zhang, Xuetong

    2018-01-17

    Polyrotaxanes (PRs) are supramolecular systems that combine with several cyclic molecules threaded on a linear molecule, and have been widely applied in molecular abacus, stimuli-responsive systems, self-healing materials, etc. The fabrication of macroscopic porous PR monoliths, which is expected to impart more functions, has not been realized yet. PR aerogels featuring with high specific surface area (232 m 2 /g), high strength (74.7 MPa), and temperature-responsiveness have been synthesized in this work by introducing poly(N-isopropylacrylamide) to the molecular necklaces followed by chemical cross-linking with a rigid cross-linker and supercritical fluid drying in sequence, which might open a new door toward smart macroscopic porous materials.

  4. Super insulating aerogel glazing

    DEFF Research Database (Denmark)

    Schultz, Jørgen Munthe; Jensen, Karsten Ingerslev; Kristiansen, Finn Harken

    2005-01-01

    This paper describes the application results of a previous and current EU-project on super insulating glazing based on monolithic silica aerogel. Prototypes measuring approx. 55´55 cm2 have been made with 15 mm evacuated aerogel between two layers of low-iron glass. Anti-reflective treatment...

  5. Modeling silica aerogel optical performance by determining its radiative properties

    Science.gov (United States)

    Zhao, Lin; Yang, Sungwoo; Bhatia, Bikram; Strobach, Elise; Wang, Evelyn N.

    2016-02-01

    Silica aerogel has been known as a promising candidate for high performance transparent insulation material (TIM). Optical transparency is a crucial metric for silica aerogels in many solar related applications. Both scattering and absorption can reduce the amount of light transmitted through an aerogel slab. Due to multiple scattering, the transmittance deviates from the Beer-Lambert law (exponential attenuation). To better understand its optical performance, we decoupled and quantified the extinction contributions of absorption and scattering separately by identifying two sets of radiative properties. The radiative properties are deduced from the measured total transmittance and reflectance spectra (from 250 nm to 2500 nm) of synthesized aerogel samples by solving the inverse problem of the 1-D Radiative Transfer Equation (RTE). The obtained radiative properties are found to be independent of the sample geometry and can be considered intrinsic material properties, which originate from the aerogel's microstructure. This finding allows for these properties to be directly compared between different samples. We also demonstrate that by using the obtained radiative properties, we can model the photon transport in aerogels of arbitrary shapes, where an analytical solution is difficult to obtain.

  6. Optically Transparent Thermally Insulating Silica Aerogels for Solar Thermal Insulation.

    Science.gov (United States)

    Günay, A Alperen; Kim, Hannah; Nagarajan, Naveen; Lopez, Mateusz; Kantharaj, Rajath; Alsaati, Albraa; Marconnet, Amy; Lenert, Andrej; Miljkovic, Nenad

    2018-04-18

    Rooftop solar thermal collectors have the potential to meet residential heating demands if deployed efficiently at low solar irradiance (i.e., 1 sun). The efficiency of solar thermal collectors depends on their ability to absorb incoming solar energy and minimize thermal losses. Most techniques utilize a vacuum gap between the solar absorber and the surroundings to eliminate conduction and convection losses, in combination with surface coatings to minimize reradiation losses. Here, we present an alternative approach that operates at atmospheric pressure with simple, black, absorbing surfaces. Silica based aerogels coated on black surfaces have the potential to act as simple and inexpensive solar thermal collectors because of their high transmission to solar radiation and low transmission to thermal radiation. To demonstrate their heat-trapping properties, we fabricated tetramethyl orthosilicate-based silica aerogels. A hydrophilic aerogel with a thickness of 1 cm exhibited a solar-averaged transmission of 76% and thermally averaged transmission of ≈1% (at 100 °C). To minimize unwanted solar absorption by O-H groups, we functionalized the aerogel to be hydrophobic, resulting in a solar-averaged transmission of 88%. To provide a deeper understanding of the link between aerogel properties and overall efficiency, we developed a coupled radiative-conductive heat transfer model and used it to predict solar thermal performance. Instantaneous solar thermal efficiencies approaching 55% at 1 sun and 80 °C were predicted. This study sheds light on the applicability of silica aerogels on black coatings for solar thermal collectors and offers design priorities for next-generation solar thermal aerogels.

  7. Evacuation and assembly of aerogel glazings

    DEFF Research Database (Denmark)

    Jensen, Karsten Ingerslev

    1999-01-01

    The application of monolithic silica aerogel as transparent insulation material for windows has been investigated for some years. It has been realised that a major problem of an industrial production of aerogel glazings will be the time for evacuation of the aerogel material. However, in a previous...

  8. Recent Advances in Research on the Synthetic Fiber Based Silica Aerogel Nanocomposites

    Directory of Open Access Journals (Sweden)

    Agnieszka Ślosarczyk

    2017-02-01

    Full Text Available The presented paper contains a brief review on the synthesis and characterization of silica aerogels and its nanocomposites with nanofibers and fibers based on a literature study over the past twenty years and my own research. Particular attention is focused on carbon fiber-based silica aerogel nanocomposites. Silica aerogel is brittle in nature, therefore, it is necessary to improve this drawback, e.g., by polymer modification or fiber additives. Nevertheless, there are very few articles in the literature devoted to the synthesis of silica aerogel/fiber nanocomposites, especially those focusing on carbon fibers and nanofibers. Carbon fibers are very interesting materials, namely due to their special properties: high conductivity, high mechanical properties in relation to very low bulk densities, high thermal stability, and chemical resistance in the silica aerogel matrix, which can help enhance silica aerogel applications in the future.

  9. Synthesis and Textural Characterization of Mesoporous and Meso-/Macroporous Silica Monoliths Obtained by Spinodal Decomposition

    Directory of Open Access Journals (Sweden)

    Anne Galarneau

    2016-04-01

    Full Text Available Silica monoliths featuring either mesopores or flow-through macropores and mesopores in their skeleton are prepared by combining spinodal phase separation and sol-gel condensation. The macroporous network is first generated by phase separation in acidic medium in the presence of polyethyleneoxides while mesoporosity is engineered in a second step in alkaline medium, possibly in the presence of alkylammonium cations as surfactants. The mesoporous monoliths, also referred as aerogels, are obtained in the presence of alkylpolyethylene oxides in acidic medium without the use of supercritical drying. The impact of the experimental conditions on pore architecture of the monoliths regarding the shape, the ordering, the size and the connectivity of the mesopores is comprehensively discussed based on a critical appraisal of the different models used for textural analysis.

  10. Elastic properties of silica aerogels from a new rapid supercritical extraction process

    Energy Technology Data Exchange (ETDEWEB)

    Gross, J.; Coronado, P.R.; Hair, L.M.; Hrubesh, L.W.

    1997-08-11

    Silica aerogels were produced by a new process from Tetramethoxysilane (TMOS) with ammonia as base catalyst. the process involves pouring the liquid sol in a stainless steel mold and immediately heating it to supercritical conditions. Gelation and aging occurs during heating and reaction rates are high die to high average temperatures. the gel fills the container completely, which enables relatively fast venting of the supercritical fluid by providing a constraint for swelling and failure of the gel monolith. The whole process can be completed in 6 h or less. Longitudinal and shear moduli were measured in the dried aerogels by ultrasonic velocity measurements both as a function of chemical composition of the original sol and of position in the aerogel. It was found that the sound velocity exhibits marked maxima on the surface of the cylindrical specimens and specifically close to the ends, where the fluid left during venting. Specimens with high catalyst concentration and high water:TMOS ratio exhibited higher average moduli.

  11. Applications of silica-based monolithic HPLC columns.

    Science.gov (United States)

    Cabrera, Karin

    2004-07-01

    The recent invention and successive commercial introduction of monolithic silica columns has motivated many scientists from both academia and industry to study their use in HPLC. The first paper on monolithic silica columns appeared in 1996. Currently about 200 papers have been published relating to applications and characterization of monolithic silica columns, including monolithic capillaries. This review attempts to give an overview covering various aspects of this new column type in the field of high throughput analysis of drugs and metabolites, chiral separations, analysis of pollutants and food-relevant compounds, as well as in bioanalytical separations such as in proteomics. Some of the applications are described in greater detail. The numerous publications dealing with the physicochemical and chromatographic characterization of monolithic silica columns are briefly summarized.

  12. Basic science of new aerogels. Final report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-08-01

    Feasibility of making monolithic composite aerogels containing silica and natural clay minerals, synthetic clay minerals or zeolites has been demonstrated, using two different processes; up to 30 wt% of the mineral phase has been successfully added. Addition of natural and synthetic clay minerals or zeolites to silica aerosols was shown to retard densification. Composite silica aerogels showed significant surface area still present after sintering at 800 or 1000 C. For most samples, 1 wt% of the second phase is equally effective in retarding densification as 10 wt%. Composite aerogels, in general, had lower hardness values than pure silica. Hardness values were inversely proportional to aerogel pore radius.

  13. Aerogels: transparent and super-insulating materials; Les aerogels: isolants transparent-super isolants

    Energy Technology Data Exchange (ETDEWEB)

    Melka, S.; Rigacci, A.; Achard, P.; Bezian, J.J. [Ecole des Mines de Paris, 06 - Sophia-Antipolis (France); Sallee, H.; Chevalier, B. [Centre des Sciences et Techniques du Batiment, 38 - Saint-Martin-d`Heres (France)

    1996-12-31

    Recent studies have demonstrated the super-insulating properties of silica aerogel in its monolithic or finely divided state. In its monolithic state, this material conciliates excellent thermal insulation performances, a good transmission of visible light and interesting acoustic properties. Also its amazing structural characteristics (lightness, high global porosity, small diameter of pores) are particularly interesting for its use in double glazing windows as transparent insulating spacer. The aim of the work carried out by the Energetic Centre of the Ecole des Mines of Paris is to understand the thermal transfer phenomena in all forms of silica aerogel. In this paper, the main steps of the synthesis process of monolithic silica aerogel is presented with the thermal conductivities obtained. Then, a model is built to describe the thermal transfer mechanisms in finely divided aerogel beds. Finally, the hot wire thermal characterization method is presented and the results obtained on silica aerogels are discussed. (J.S.) 16 refs.

  14. Improvements of reinforced silica aerogel nanocomposites thermal properties for architecture applications.

    Science.gov (United States)

    Saboktakin, Amin; Saboktakin, Mohammad Reza

    2015-01-01

    An 1,4-cis polybutadiene rubber/carboxymethyl starch (CMS)-based silica aerogel nanocomposites as a insulation material was developed that will provide superior thermal insulation properties, flexibility, toughness, durability of the parent polymer, yet with the low density and superior insulation properties associated with the aerogels. In this study, reinforced 1,4-cis polybutadiene-CMS-silica aerogel nanocomposites were prepared from a silica aerogel with a surface area 710 m(2) g(-1), a pore size of 25.3 nm and a pore volume of 4.7 cm(3) g(-1). The tensile properties and dynamic mechanical properties of 1,4-cis polybutadiene/CMS nanocomposites were systematically enhanced at low silica loading. Similar improvements in tensile modulus and strength have been observed for 1,4-cis polybutadiene/CMS mesoporous silica aerogel nanocomposites. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Simulation and Analysis of Mechanical Properties of Silica Aerogels: From Rationalization to Prediction.

    Science.gov (United States)

    Ma, Hao; Zheng, Xiaoyang; Luo, Xuan; Yi, Yong; Yang, Fan

    2018-01-30

    Silica aerogels are highly porous 3D nanostructures and have exhibited excellent physio-chemical properties. Although silica aerogels have broad potential in many fields, the poor mechanical properties greatly limit further applications. In this study, we have applied the finite volume method (FVM) method to calculate the mechanical properties of silica aerogels with different geometric properties such as particle size, pore size, ligament diameter, etc. The FVM simulation results show that a power law correlation existing between relative density and mechanical properties (elastic modulus and yield stress) of silica aerogels, which are consistent with experimental and literature studies. In addition, depending on the relative densities, different strategies are proposed in order to synthesize silica aerogels with better mechanical performance by adjusting the distribution of pore size and ligament diameter of aerogels. Finally, the results suggest that it is possible to synthesize silica aerogels with ultra-low density as well as high strength and stiffness as long as the textural features are well controlled. It is believed that the FVM simulation methodology could be a valuable tool to study mechanical performance of silica aerogel based materials in the future.

  16. 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.

  17. Applications of monolithic silica capillary columns in proteomics

    NARCIS (Netherlands)

    Barroso, B.; Lubda, D; Bischoff, Rainer

    2003-01-01

    The use and applicability of silica based capillary monolithic reversed-phase columns in proteomic analysis has been evaluated by liquid chromatography-mass spectrometry (LC-MS). Chromatographic performance of the monolithic capillaries was evaluated with a tryptic digest of cytochrome C showing

  18. Sol-Gel Synthesis of Non-Silica Monolithic Materials

    Science.gov (United States)

    Gaweł, Bartłomiej; Gaweł, Kamila; Øye, Gisle

    2010-01-01

    Monolithic materials have become very popular because of various applications, especially within chromatography and catalysis. Large surface areas and multimodal porosities are great advantages for these applications. New sol-gel preparation methods utilizing phase separation or nanocasting have opened the possibility for preparing materials of other oxides than silica. In this review, we present different synthesis methods for inorganic, non-silica monolithic materials. Some examples of application of the materials are also included.

  19. Sol-Gel Synthesis of Non-Silica Monolithic Materials

    Directory of Open Access Journals (Sweden)

    Bartłomiej Gaweł

    2010-04-01

    Full Text Available Monolithic materials have become very popular because of various applications, especially within chromatography and catalysis. Large surface areas and multimodal porosities are great advantages for these applications. New sol-gel preparation methods utilizing phase separation or nanocasting have opened the possibility for preparing materials of other oxides than silica. In this review, we present different synthesis methods for inorganic, non-silica monolithic materials. Some examples of application of the materials are also included.

  20. Sol-Gel Synthesis of Non-Silica Monolithic Materials

    OpenAIRE

    Gawe?, Bart?omiej; Gawe?, Kamila; ?ye, Gisle

    2010-01-01

    Monolithic materials have become very popular because of various applications, especially within chromatography and catalysis. Large surface areas and multimodal porosities are great advantages for these applications. New sol-gel preparation methods utilizing phase separation or nanocasting have opened the possibility for preparing materials of other oxides than silica. In this review, we present different synthesis methods for inorganic, non-silica monolithic materials. Some examples of appl...

  1. Faraday rotation measurements in maghemite-silica aerogels

    International Nuclear Information System (INIS)

    Taboada, E.; Real, R.P. del; Gich, M.; Roig, A.; Molins, E.

    2006-01-01

    Faraday rotation measurements have been performed on γ-Fe 2 O 3 /SiO 2 nanocomposite aerogels which are light, porous and transparent magnetic materials. The materials have been prepared by sol-gel polymerization of a silicon alkoxide, impregnation of the intermediate silica gel with a ferrous salt and supercritical drying of the gels. During supercritical evacuation of the solvent, spherical nanoparticles of iron oxide, with a mean particle diameter of 8.1±2.0 nm, are formed and are found to be homogenously distributed within the silica matrix. The specific Faraday rotation of the composite was measured at 0.6 T using polarized light of 810 nm, being 29.6 deg./cm. The changes in the plane of polarization of the transmitted light and the magnetization of the material present similar magnetic field dependencies and are characteristic of a superparamagnetic system

  2. The LHCb RICH silica aerogel performance with LHC data

    CERN Multimedia

    Perego, D L

    2010-01-01

    In the LHCb detector at the Large Hadron Collider, powerful charged particle identification is performed by Ring Imaging Cherenkov (RICH) technology. In order to cover the full geometric acceptance and the wide momentum range (1-100 GeV/c), two detectors with three Cherenkov radiators have been designed and installed. In the medium (10-40 GeV/c) and high (30-100 GeV/c) momentum range, gas radiators are used (C4F10 and CF4 respectively). In the low momentum range (1 to a few GeV/c) pion/kaon/proton separation will be done with photons produced in solid silica aerogel. A set of 16 tiles, with the large transverse dimensions ever (20x20 cm$^2$) and nominal refractive index 1.03 have been produced. The tiles have excellent optical properties and homogeneity of refractive index within the tile of ~1%. The first data collected at LHC are used to understand the behaviour of the RICH: preliminary results will be presented and discussed on the performance of silica aerogel and of the gas radiators C4F10 and CF4.

  3. Development and Investigation of Evacuated Windows Based on Monolithic Silica Xerogel Spacers

    DEFF Research Database (Denmark)

    Schultz, Jørgen Munthe; Svendsen, Sv Aa Højgaard

    with the low thermal conductivity offers good possibilities for production of energy efficient windows. For the xerogel window system it is necessary to have the xerogel sufficiently dried, if not hydrophobic xerogels are used, because residual water vapour adsorbed in the material will cause condensation...... to shortage of large xerogel samples. Within the xerogel project a thermally improved wooden frame has been developed which has been used for measurements on aerogel windows to evaluate the effect on total heat loss coefficients. The calculated centre U-value of a xerogel glazing (xerogel density = 250 kg/m3...... will be approximately 0.013 W/(m K) which is approximately 33% of the value for commonly used insulation materials, e.g. mineral wool. Monolithic silica xerogel is a highly porous material (pore volume up to 90%) with a solar transmittance of 50% (thickness = 20 mm). However, if the silica xerogel is not made...

  4. Selective oxidation of cyclohexene through gold functionalized silica monolith microreactors

    Science.gov (United States)

    Alotaibi, Mohammed T.; Taylor, Martin J.; Liu, Dan; Beaumont, Simon K.; Kyriakou, Georgios

    2016-04-01

    Two simple, reproducible methods of preparing evenly distributed Au nanoparticle containing mesoporous silica monoliths are investigated. These Au nanoparticle containing monoliths are subsequently investigated as flow reactors for the selective oxidation of cyclohexene. In the first strategy, the silica monolith was directly impregnated with Au nanoparticles during the formation of the monolith. The second approach was to pre-functionalize the monolith with thiol groups tethered within the silica mesostructure. These can act as evenly distributed anchors for the Au nanoparticles to be incorporated by flowing a Au nanoparticle solution through the thiol functionalized monolith. Both methods led to successfully achieving even distribution of Au nanoparticles along the length of the monolith as demonstrated by ICP-OES. However, the impregnation method led to strong agglomeration of the Au nanoparticles during subsequent heating steps while the thiol anchoring procedure maintained the nanoparticles in the range of 6.8 ± 1.4 nm. Both Au nanoparticle containing monoliths as well as samples with no Au incorporated were tested for the selective oxidation of cyclohexene under constant flow at 30 °C. The Au free materials were found to be catalytically inactive with Au being the minimum necessary requirement for the reaction to proceed. The impregnated Au-containing monolith was found to be less active than the thiol functionalized Au-containing material, attributable to the low metal surface area of the Au nanoparticles. The reaction on the thiol functionalized Au-containing monolith was found to depend strongly on the type of oxidant used: tert-butyl hydroperoxide (TBHP) was more active than H2O2, likely due to the thiol induced hydrophobicity in the monolith.

  5. Synthesis and physical properties of TEOS-based silica aerogels prepared by two step (acid-base) sol-gel process

    International Nuclear Information System (INIS)

    Venkateswara Rao, A.; Bhagat, S.D.

    2004-01-01

    The experimental results on the synthesis and physical properties of tetra-ethoxy-silane- (TEOS) based silica aerogels produced by two step (acid-base) sol-gel process, are reported. The oxalic acid (A) and NH 4 OH (B) concentrations were varied from 0 to 0.1 M and from 0.4 to 3 M, respectively. Monolithic and transparent aerogels have been obtained for the values of A=0.001 M and B=1 M. The effect of time interval (t) before the base catalyst (NH 4 OH) addition to the acidic sol was studied from 0 to 72 h. The time interval at t=24 h of NH 4 OH addition was found to be the best, in terms of low volume shrinkage, high optical transmission and monolithicity. The molar ratio of EtOH/TEOS (S) was varied from 3 to 7.5. Monolithic and transparent aerogels were obtained for an S value of 6.9. Also, the effects of molar ratio of acidic water, i.e., H 2 O/TEOS (W1) and basic water, i.e., H 2 O/TEOS (W2) on the physical properties of the aerogels have been studied. Highly transparent (about 90%) and monolithic aerogels with lower volume shrinkage ( 2 O):basic (H 2 O). The results are discussed by taking into consideration the hydrolysis and poly-condensation reactions. The aerogels were characterized by scanning electron microscopy (SEM), optical transmission, bulk density, volume shrinkage and porosity measurements. (authors)

  6. Properties of Silica-Based Aerogel Substrates and Application to C-Band Circular Patch Antenna

    Science.gov (United States)

    Abdel-Rahman, Mohamed; Haraz, Osama M.; Ashraf, Nadeem; Zia, Muhammad Fakhar; Khaled, Usama; Elsahfiey, Ibrahim; Alshebeili, Saleh; Sebak, Abdel Razik

    2018-03-01

    Silica aerogel is a lightweight and low-permittivity dielectric material that possesses attractive features for use as an antenna substrate. In this paper, we characterize the radio frequency and microwave dielectric permittivity properties of substrates composed of silica aerogel encapsulated in polymer aerogel in the frequency range from 10 MHz to 8.5 GHz. Characterized silica-based aerogel substrates show relative permittivity values varying between 1.055 and 1.25 and loss tangent values ranging from 5.08 × 10-4 to 0.0206. Silica-based aerogel substrates thus have the potential of use in designing antennas with high gain and large bandwidth. Validation is presented by characterizing the performance of a manufactured C-band circular patch antenna on silica-based aerogel substrate. The performance is also compared to a design that uses Rogers Duroid RT5880 substrate. The results reveal that the silica aerogel substrate antenna at 7.2 GHz provides 1.5 dB increase in gain, 88% enhancement in bandwidth and 68.5% reduction in mass, in comparison with the antenna on RT5880 substrate.

  7. Dynamic properties of silica aerogels as deduced from specific-heat and thermal-conductivity measurements

    DEFF Research Database (Denmark)

    Bernasconi, A.; Sleator, T.; Posselt, D.

    1992-01-01

    The specific heat C(p) and the thermal conductivity lambda of a series of base-catalyzed silica aerogels have been measured at temperatures between 0.05 and 20 K. The results confirm that the different length-scale regions observed in the aerogel structure are reflected in the dynamic behavior...

  8. Low-temperature specific-heat and thermal-conductivity of silica aerogels

    DEFF Research Database (Denmark)

    Bernasconi, A.; Sleator, T.; Posselt, D.

    1992-01-01

    Specific heat, C(p), and thermal conductivity, lambda, have been measured on a series of base-catalyzed silica aerogels at temperatures between 0.05 and 20 K. Results for both C(p)(T) and lambda(T) confirm that the different length-scale regions observed in the aerogel structure are reflected...

  9. Mechanical Properties and Brittle Behavior of Silica Aerogels

    Directory of Open Access Journals (Sweden)

    Thierry Woignier

    2015-12-01

    Full Text Available Sets of silica gels: aerogels, xerogels and sintered aerogels, have been studied in the objective to understand the mechanical behavior of these highly porous solids. The mechanical behaviour of gels is described in terms of elastic and brittle materials, like glasses or ceramics. The magnitude of the elastic and rupture modulus is several orders of magnitude lower compared to dense glass. The mechanical behaviours (elastic and brittle are related to the same kinds of gel characteristics: pore volume, silanol content and pore size. Elastic modulus depends strongly on the volume fraction of pores and on the condensation reaction between silanols. Concerning the brittleness features: rupture modulus and toughness, it is shown that pores size plays an important role. Pores can be considered as flaws in the terms of fracture mechanics and the flaw size is related to the pore size. Weibull’s theory is used to show the statistical nature of flaw. Moreover, stress corrosion behaviour is studied as a function of environmental conditions (water and alcoholic atmosphere and temperature.

  10. Transparent aerogel Windows

    DEFF Research Database (Denmark)

    Jensen, Karsten Ingerslev; Schultz, Jørgen Munthe

    In a recent EU FP5 project, monolithic silica aerogel was further developed with respect to the production process at pilot-scale, its properties and the application as transparent insulation material in highly insulating and transparent windows. The aerogel production process has been optimised......-value of 0.7 W/m²K for about 14 mm aerogel thickness, which for a 20 mm thickness corresponds to a U-value of approximately 0.5 W/m²K. No other known glazing exhibits such an excellent combination of solar transmittance and heat loss coefficient. At a Danish location and North facing, the energy balance...

  11. Noble Metal Immersion Spectroscopy of Silica Alcogels and Aerogels

    Science.gov (United States)

    Smith, David D.; Sibille, Laurent; Cronise, Raymond J.; Noever, David A.

    1998-01-01

    We have fabricated aerogels containing gold and silver nanoparticles for gas catalysis applications. By applying the concept of an average or effective dielectric constant to the heterogeneous interlayer surrounding each particle, we extend the technique of immersion spectroscopy to porous or heterogeneous media. Specifically, we apply the predominant effective medium theories for the determination of the average fractional composition of each component in this inhomogeneous layer. Hence, the surface area of metal available for catalytic gas reaction is determined. The technique is satisfactory for statistically random metal particle distributions but needs further modification for aggregated or surfactant modified systems. Additionally, the kinetics suggest that collective particle interactions in coagulated clusters are perturbed during silica gelation resulting in a change in the aggregate geometry.

  12. Silica aerogel Cherenkov counter for the KEK B-factory experiment

    CERN Document Server

    Sumiyoshi, T; Enomoto, R; Iijima, T; Suda, R; Leonidopoulos, C; Marlow, D R; Prebys, E; Kawabata, R; Kawai, H; Ooba, T; Nanao, M; Suzuki, K; Ogawa, S; Murakami, A; Khan, M H R

    1999-01-01

    Low-refractive-index silica aerogel is a convenient radiator for threshold-type Cherenkov counters, which are used for particle identification in high-energy physics experiments. For the BELLE detector at the KEK B-Factory we have produced about 2 m sup 3 of hydrophobic silica aerogels of n=1.01-1.03 using a new production method. The particle identification capability of the aerogel Cherenkov counters was tested and 3 sigma pion/proton separation has been achieved at 3.5 GeV/c. Radiation hardness of the aerogels was confirmed up to 9.8 Mrad. The Aerogel Cherenkov counter system (ACC) was successfully installed in the BELLE just before this conference.

  13. Behavior of macroporous vinyl silica and silica monolithic columns in high pressure gas chromatography.

    Science.gov (United States)

    Maniquet, Adrien; Bruyer, Nicolas; Raffin, Guy; Baco-Antionali, Franck; Demesmay, Claire; Dugas, Vincent; Randon, Jérôme

    2017-06-30

    80% vinyltrimethoxysilane-based hybrid silica monoliths (80-VTMS), which have been initially developed for separation in reversed-phase liquid chromatography, have been investigated in high pressure gas chromatography separations (carrier gas pressure up to 60bar) and compared to silica monolithic columns. The behavior of both silica and 80-VTMS monolithic columns was investigated using helium, nitrogen and carbon dioxide as carrier gas. The efficiency of 80-VTMS monolithic columns was shown to vary differently than silica monolithic columns according to the temperature and the carrier gas used. Carrier gas nature was a significant parameter on the retention for both silica and vinyl columns in relation to its adsorption onto the stationary phase in such high pressure conditions. The comparison of retention and selectivity between 80-VTMS monoliths and silica was performed under helium using the logarithm of the retention factor according to the number of carbon atoms combined to Kovats indexes. The very good performances of these columns were demonstrated, allowing the separation of 8 compounds in less than 1min. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Super insulating aerogel glazing

    DEFF Research Database (Denmark)

    Schultz, Jørgen Munthe; Jensen, Karsten Ingerslev; Kristiansen, Finn Harken

    2004-01-01

    form the weakest part of the thermal envelope with respect to heat loss coefficient, but on the other hand also play an important role for passive solar energy utilisation. For window orientations other than south, the net energy balance will be close to or below zero. However, the properties......Monolithic silica aerogel offers the possibility of combining super insulation and high solar energy transmittance, which has been the background for a previous and a current EU project on research and development of monolithic silica aerogel as transparent insulation in windows. Generally, windows...... of aerogel glazing will allow for a positive net energy gain even for north facing vertical windows in a Danish climate during the heating season. This means that high quality daylight can be obtained even with additional energy gain. On behalf of the partners of the two EU projects, results related...

  15. Enhancement Studies on Manufacturing and Properties of Novel Silica Aerogel Composites

    Directory of Open Access Journals (Sweden)

    Sunil Chandrakant Joshi

    2018-01-01

    Full Text Available Silica Aerogel composites are ultra-low density, highly porous foam-like materials that exhibit excellent thermal insulation and high strain recovery characteristics. In the present work, environment-friendly silica aerogel composites are fabricated using silica aerogel granules with bio based porcine-gelatin as the binding agent dissolved in water and by further drying the mix at sub-zero condition. This article focuses on improvement studies carried on the mold design and the manufacturing process to achieve better geometric compliance for the silica aerogel composites. It also presents contact angle measurements, compressive behavior under different cycles of loading, time dependent behavior and flexural response of the composites. The influence of additives, such as fumed silica and carbon nanotubes on mechanical properties of the composites is also deliberated. Water droplet contact angle experiments confirmed the ultra-hydrophobic nature of the composites. The mechanical properties were characterized under cyclic loading-unloading compression and three-point flexure tests. On successive compression in three consecutive load cycles, the strain and thickness recovery were found to decrease by around 30%. The flexural properties of the aerogel composites were investigated using it as the core covered by thin carbon composite face sheets. It was found that the flexural strength and the failure strain of this aerogel sandwich composites is approximately half of the conventional nomex honeycomb sandwich equivalent.

  16. Assessment of Methods to Consolidate Iodine-Loaded Silver-Functionalized Silica Aerogel

    Energy Technology Data Exchange (ETDEWEB)

    Matyas, Josef; Engler, Robert K.

    2013-09-01

    The U.S. Department of Energy is currently investigating alternative sorbents for the removal and immobilization of radioiodine from the gas streams in a nuclear fuel reprocessing plant. One of these new sorbents, Ag0-functionalized silica aerogels, shows great promise as a potential replacement for Ag-bearing mordenites because of its high selectivity and sorption capacity for iodine. Moreover, a feasible consolidation of iodine-loaded Ag0-functionalized silica aerogels to a durable SiO2-based waste form makes this aerogel an attractive choice for sequestering radioiodine. This report provides a preliminary assessment of the methods that can be used to consolidate iodine-loaded Ag0-functionalized silica aerogels into a final waste form. In particular, it focuses on experimental investigation of densification of as prepared Ag0-functionalized silica aerogels powders, with or without organic moiety and with or without sintering additive (colloidal silica), with three commercially available techniques: 1) hot uniaxial pressing (HUP), 2) hot isostatic pressing (HIP), and 3) spark plasma sintering (SPS). The densified products were evaluated with helium gas pycnometer for apparent density, with the Archimedes method for apparent density and open porosity, and with high-resolution scanning electron microscopy and energy dispersive spectroscopy (SEM-EDS) for the extent of densification and distribution of individual elements. The preliminary investigation of HUP, HIP, and SPS showed that these sintering methods can effectively consolidate powders of Ag0-functionalized silica aerogel into products of near-theoretical density. Also, removal of organic moiety and adding 5.6 mass% of colloidal silica to Ag0-functionalized silica aerogel powders before processing provided denser products. Furthermore, the ram travel data for SPS indicated that rapid consolidation of powders can be performed at temperatures below 950°C.

  17. Alumina/silica aerogel with zinc chloride as an alkylation catalyst

    Directory of Open Access Journals (Sweden)

    DEJAN U. SKALA

    2001-10-01

    Full Text Available The alumina/silica with zinc chloride aerogel alkylation catalyst was obtained using a one step sol-gel synthesis, and subsequent drying with supercritical carbon dioxide. The aerogel catalyst activity was found to be higher compared to the corresponding xerogel catalyst, as a result of the higher aerogel surface area, total pore volume and favourable pore size distribution. Mixed Al–O–Si bonds were present in both gel catalyst types. Activation by thermal treatment in air was needed prior to catalytic alkylation, due to the presence of residual organic groups on the aerogel surface. The optimal activation temperature was found to be in the range 185–225°C, while higher temperatures resulted in the removal of zinc chloride from the surface of the aerogel catalyst with a consequential decrease in the catalytic activity. On varying the zinc chloride content, the catalytic activity of the aerogel catalyst exhibited a maximum. High zinc chloride contents decreased the catalytic activity of the aerogel catalyst as the result of the pores of the catalyst being plugged with this compound, and the separation of the alumina/silica support into Al-rich and Si-rich phases. The surface area, total pore volume, pore size distribution and zinc chloride content had a similar influence on the activity of the aerogel catalyst as was the case of xerogel catalyst and supported zinc chloride catalysts.

  18. Monolithic cobalt-doped carbon aerogel for efficient catalytic activation of peroxymonosulfate in water.

    Science.gov (United States)

    Hu, Peidong; Long, Mingce; Bai, Xue; Wang, Cheng; Cai, Caiyun; Fu, Jiajun; Zhou, Baoxue; Zhou, Yongfeng

    2017-06-15

    As an emerging carbonaceous material, carbon aerogels (CAs) display a great potential in environmental cleanup. In this study, a macroscopic three-dimensional monolithic cobalt-doped carbon aerogel was developed by co-condensation of graphene oxide sheets and resorcinol-formaldehyde resin in the presence of cobalt ions, followed by lyophilization, carbonization and thermal treatment in air. Cobalt ions were introduced as a polymerization catalyst to bridge the organogel framework, and finally cobalt species were retained as both metallic cobalt and Co 3 O 4 , wrapped by graphitized carbon layers. The material obtained after a thermal treatment in air (CoCA-A) possesses larger BET specific surface area and pore volume, better hydrophilicity and lower leaching of cobalt ions than that without the post-treatment (CoCA). Despite of a lower loading of cobalt content and a larger mass transfer resistance than traditional powder catalysts, CoCA-A can efficiently eliminate organic contaminants by activation of peroxymonosulfate with a low activation energy. CoCA-A can float beneath the surface of aqueous solution and can be taken out completely without any changes in morphology. The monolith is promising to be developed into an alternative water purification technology due to the easily separable feature. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Ambient pressure dried tetrapropoxysilane-based silica aerogels with high specific surface area

    Science.gov (United States)

    Parale, Vinayak G.; Han, Wooje; Jung, Hae-Noo-Ree; Lee, Kyu-Yeon; Park, Hyung-Ho

    2018-01-01

    In the present paper, we report the synthesis of tetrapropoxysilane (TPOS)-based silica aerogels with high surface area and large pore volume. The silica aerogels were prepared by a two-step sol-gel process followed by surface modification via a simple ambient pressure drying approach. In order to minimize drying shrinkage and obtain hydrophobic aerogels, the surface of the alcogels was modified using trichloromethylsilane as a silylating agent. The effect of the sol-gel compositional parameters on the polymerization of aerogels prepared by TPOS, one of the precursors belonging to the Si(OR)4 family, was reported for the first time. The oxalic acid and NH4OH concentrations were adjusted to achieve good-quality aerogels with high surface area, low density, and high transparency. Controlling the hydrolysis and condensation reactions of the TPOS precursor turned out to be the most important factor to determine the pore characteristics of the aerogel. Highly transparent aerogels with high specific surface area (938 m2/g) and low density (0.047 g/cm3) could be obtained using an optimized TPOS/MeOH molar ratio with appropriate concentrations of oxalic acid and NH4OH.

  20. Mechanism of drug release from silica-gelatin aerogel-Relationship between matrix structure and release kinetics.

    Science.gov (United States)

    Veres, Péter; Kéri, Mónika; Bányai, István; Lázár, István; Fábián, István; Domingo, Concepción; Kalmár, József

    2017-04-01

    Specific features of a silica-gelatin aerogel (3 wt.% gelatin content) in relation to drug delivery has been studied. It was confirmed that the release of both ibuprofen (IBU) and ketoprofen (KET) is about tenfold faster from loaded silica-gelatin aerogel than from pure silica aerogel, although the two matrices are structurally very similar. The main goal of the study was to understand the mechanistic background of the striking difference between the delivery properties of these closely related porous materials. Hydrated and dispersed silica-gelatin aerogel has been characterized by NMR cryoporometry, diffusiometry and relaxometry. The pore structure of the silica aerogel remains intact when it disintegrates in water. In contrast, dispersed silica-gelatin aerogel develops a strong hydration sphere, which reshapes the pore walls and deforms the pore structure. The drug release kinetics was studied on a few minutes time scale with 1s time resolution. Simultaneous evaluation of all relevant kinetic and structural information confirmed that strong hydration of the silica-gelatin skeleton facilitates the rapid desorption and dissolution of the drugs from the loaded aerogel. Such a driving force is not operative in pure silica aerogels. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Synthesis and Characterization of Fibre Reinforced Silica Aerogel Blankets for Thermal Protection

    Directory of Open Access Journals (Sweden)

    S. Chakraborty

    2016-01-01

    Full Text Available Using tetraethoxysilane (TEOS as the source of silica, fibre reinforced silica aerogels were synthesized via fast ambient pressure drying using methanol (MeOH, trimethylchlorosilane (TMCS, ammonium fluoride (NH4F, and hexane. The molar ratio of TEOS/MeOH/(COOH2/NH4F was kept constant at 1 : 38 : 3.73 × 10−5 : 0.023 and the gel was allowed to form inside the highly porous meta-aramid fibrous batting. The wet gel surface was chemically modified (silylation process using various concentrations of TMCS in hexane in the range of 1 to 20% by volume. The fibre reinforced silica aerogel blanket was obtained subsequently through atmospheric pressure drying. The aerogel blanket samples were characterized by density, thermal conductivity, hydrophobicity (contact angle, and Scanning Electron Microscopy. The radiant heat resistance of the aerogel blankets was examined and compared with nonaerogel blankets. It has been observed that, compared to the ordinary nonaerogel blankets, the aerogel blankets showed a 58% increase in the estimated burn injury time and thus ensure a much better protection from heat and fire hazards. The effect of varying the concentration of TMCS on the estimated protection time has been examined. The improved thermal stability and the superior thermal insulation of the flexible aerogel blankets lead to applications being used for occupations that involve exposure to hazards of thermal radiation.

  2. Synthesis, Processing, and Characterization of Inorganic-Organic Hybrid Cross-Linked Silica, Organic Polyimide, and Inorganic Aluminosilicate Aerogels

    Science.gov (United States)

    Nguyen, Baochau N.; Guo, Haiquan N.; McCorkle, Linda S.

    2014-01-01

    As aerospace applications become ever more demanding, novel insulation materials with lower thermal conductivity, lighter weight and higher use temperature are required to fit the aerospace application needs. Having nanopores and high porosity, aerogels are superior thermal insulators, among other things. The use of silica aerogels in general is quite restricted due to their inherent fragility, hygroscopic nature, and poor mechanical properties, especially in extereme aerospace environments. Our research goal is to develop aerogels with better mechanical and environmental stability for a variety of aeronautic and space applications including space suit insulation for planetary surface missions, insulation for inflatable structures for habitats, inflatable aerodynamic decelerators for entry, descent and landing (EDL) operations, and cryotank insulation for advance space propulsion systems. Different type of aerogels including organic-inorganic polymer reinforced (hybrid) silica-based aerogels, polyimide aerogels and inorganic aluminosilicate aerogels have been developed and examined.

  3. Determination of dynamic mechanical properties of silica aerogel by resonance and non-resonance method

    Science.gov (United States)

    Qu, Z. P.; Sheng, M. P.

    2017-03-01

    Silica aerogel has great potential in aeronautics, building construction, and offshore oil transportation. The dynamic mechanical properties of silica aerogel were measured by the resonance and non-resonance method. The results of the two methods were compared. While the Young’s modulus coincided well, the loss factor had big difference. To explain this phenomenon, the sensitivity of the two methods was analyzed. It shows that the loss factor determination of low-loss materials by the non-resonance method is quite sensitive to the experiment uncertainties. This probably results in the loss factor difference between the two methods.

  4. Synthesis of aerogel tiles with high light scattering length

    CERN Document Server

    Danilyuk, A F; Okunev, A G; Onuchin, A P; Shaurman, S A

    1999-01-01

    The possibility of aerogel tiles production for RICH detectors is described. Monolithic blocks of silica aerogel were synthesized by two-step sol-gel processing of tetraethoxysilane Si(OEt) sub 4 followed by high temperature supercritical drying with organic solvent. The important characteristic of aerogel is the light scattering length. In the wide range of refraction indexes the light scattering length exceeds 4 cm at 400 nm.

  5. Preparation and Characterization of Highly Spherical Silica-titania Aerogel Beads with High Surface Area

    Directory of Open Access Journals (Sweden)

    YU Yu-xi

    2017-02-01

    Full Text Available The silica-titania aerogel beads were synthesized through sol-gel reaction followed by supercritical drying, in which TEOS and TBT as co-precursors, EtOH as solvents, HAC and NH3·H2O as catalysts. The as-prepared aerogel beads were characterized by SEM,TEM,XRD,FT-IR,TG-DTA and nitrogen adsorption-desorption. The results indicate that the diameter distribution of beads are between 1-8mm, the average diameter of beads is 3.5mm. The aerogel beads have nanoporous network structure with high specific surface area of 914.5m2/g, and the TiO2 particles are distributed in the aerogel uniformly, which keep the anatase crystal under high temperature.

  6. Sol-gel derived flexible silica aerogel as selective adsorbent for water decontamination from crude oil.

    Science.gov (United States)

    Abolghasemi Mahani, A; Motahari, S; Mohebbi, A

    2017-10-11

    Oil spills are the most important threat to the sea ecosystem. The present study is an attempt to investigate the effects of sol-gel parameters on seawater decontamination from crude oil by use of flexible silica aerogel. To this goal, methyltrimethoxysilane (MTMS) based silica aerogels were prepared by two-step acid-base catalyzed sol-gel process, involving ambient pressure drying (APD) method. To investigate the effects of sol-gel parameters, the aerogels were prepared under two different acidic and basic pH values (i.e. 4 and 8) and varied ethanol/MTMS molar ratios from 5 to 15. The adsorption capacity of the prepared aerogels was evaluated for two heavy and light commercial crude oils under multiple adsorption-desorption cycles. To reduce process time, desorption cycles were carried out by using roll milling for the first time. At optimum condition, silica aerogels are able to uptake heavy and light crude oils with the order of 16.7 and 13.7, respectively. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Preliminary study of silica aerogel as a gas-equivalent material in ionization chambers

    Science.gov (United States)

    Caresana, M.; Zorloni, G.

    2017-12-01

    Since about two decades, a renewed interest on aerogels has risen. These peculiar materials show fairly unique properties. Thus, they are under investigation for both scientific and commercial purposes and new optimized production processes are studied. In this work, the possibility of using aerogel in the field of radiation detection is explored. The idea is to substitute the gas filling in a ionization chamber with the aerogel. The material possesses a density about 100 times greater than ambient pressure air. Where as the open-pore structure should allow the charge carriers to move freely. Small hydrophobic silica aerogel samples were studied. A custom ionization chamber, capable of working both with aerogel or in the classic gas set up, was built. The response of the chamber in current mode was investigated using an X-ray tube. The results obtained showed, under proper conditions, an enhancement of about 60 times of the current signal in the aerogel configuration with respect to the classic gas one. Moreover, some unusual behaviours were observed, i.e. time inertia of the signal and super-/sub-linear current response with respect to the dose rate. While testing high electric fields, aerogel configuration seemed to enhance the Townsend's effects. In order to represent the observed trends, a trapping-detrapping model is proposed, which is capable to predict semi-empirically the steady state currents measured. The time evolution of the signal is semi-quantitatively represented by the same model. The coefficients estimated by the fits are in agreement with similar trapping problems in the literature. In particular, a direct comparison between the benchmark of the FET silica gates and aerogel case endorses the idea that the same type of phenomenon occurs in the studied case.

  8. Preparation and evaluation of zirconia-coated silica monolith for capillary electrochromatography.

    Science.gov (United States)

    Shi, Z-G; Feng, Y-Q; Xu, L; Zhang, M; Da, S-L

    2004-06-17

    Silica monoliths were fabricated inside fused-silica capillaries. Then the monolithic columns were coated with membrane-like zirconia. The zirconia-coated silica monoliths exhibited different EOF behavior comparing with that of bare silica monoliths. The magnitude and direction could be manipulated by changing the running buffers. Due to the amphoteric characteristic of zirconia, the silica monoliths with zirconia surface facilitate the separation of basic compounds. Aromatic amines and alkaloids were separated without obvious peak tailing. The zirconia surface was easily modified with octadecylphosphonic acid for the separation of neutral compounds. Column efficiency as high as 90,000 and 80,000m(-1) was obtained for beberine and naphthalene, respectively. Furthermore, the zirconia coating increased the stability of the monolithic columns. Even after being exposed to severe condition, there was no apparently efficiency decrease for the test samples.

  9. Low-temperature specific heat and thermal conductivity of silica aerogels

    DEFF Research Database (Denmark)

    Sleator, T.; Bernasconi, A.; Posselt, D.

    1991-01-01

    Specific-heat and thermal-conductivity measurements were made on a series of base-catalyzed silica aerogels at temperatures between 0.05 and 20 K. Evidence for a crossover between regimes of characteristically different excitations was observed. The data analysis indicates a "bump" in the density...

  10. Progress in development of silica aerogel for particle- and nuclear-physics experiments at J-PARC

    OpenAIRE

    Tabata, Makoto; Kawai, Hideyuki

    2014-01-01

    This study presents the advancement in hydrophobic silica aerogel development for use as Cherenkov radiators and muonium production targets. These devices are scheduled for use in several particle- and nuclear-physics experiments that are planned in the near future at the Japan Proton Accelerator Research Complex. Our conventional method to produce aerogel tiles with an intermediate index of refraction of approximately 1.05 is extended so that we can now produce aerogel tiles with lower indic...

  11. Effect of various structure directing agents on the physicochemical properties of the silica aerogels prepared at an ambient pressure

    KAUST Repository

    Sarawade, Pradip

    2013-12-01

    We studied the effects of various surfactants on the textural properties (BET surface area, pore size, and pore volume) of the silica aerogels prepared at an ambient pressure. A simple surface modification of silica gel prepared at an ambient pressure through hydrolysis and polycondensation of TEOS as asilica precursor was conducted using various structure directing agents. The treatment was found to induce a significant difference in the porosity of the silica aerogel. Highly porous silica aerogels with bimodal porous structures were prepared by modifying the surface of the silica wet-gel (alcogel) with trimethylchlorosilane (TMCS) in order to preserve its porosity. The samples were analyzed by small-angle X-ray scattering and nitrogen adsorption. In this work, a possible new type of highly porous hydrophobic silica aerogel with a bimodal porous structure is presented. A hydrophilic extremely porous (high surface area and large pore volume) silica aerogel was obtained by heating the as-synthesized hydrophobic silica aerogel at 400°C for 1 h. There was a significant effect of structure directing agent on the textural properties, such as specific surface area, pore size distribution and cumulative pore volume of the silicaaerogels. © 2013 Elsevier B.V. All rights reserved.

  12. A Novel Environmental Route to Ambient Pressure Dried Thermal Insulating Silica Aerogel via Recycled Coal Gangue

    Directory of Open Access Journals (Sweden)

    Pinghua Zhu

    2016-01-01

    Full Text Available Coal gangue, one of the main hazardous emissions of purifying coal from coalmine industry, is rich in silica and alumina. However, the recycling of the waste is normally restricted by less efficient techniques and low attractive output; the utilization of such waste is still staying lower than 15%. In this work, the silica aerogel materials were synthesized by using a precursor extracted from recycled silicon-rich coal gangue, followed by a single-step surface silylation and ambient pressure drying. A low density (~0.19 g/cm3 nanostructured aerogel with a 3D open porous microstructure and high surface area (~690 m2/g was synthesized, which presents a superior thermal insulation performance (~26.5 mW·m−1·K−1 of a plane packed of 4-5 mm granules which was confirmed by transient hot-wire method. This study offers a new facile route to the synthesis of insulating aerogel material by recycling solid waste coal gangue and presents a potential cost reduction of industrial production of silica aerogels.

  13. Evaluations of Silica Aerogel-Based Flexible Blanket as Passive Thermal Control Element for Spacecraft Applications

    Science.gov (United States)

    Hasan, Mohammed Adnan; Rashmi, S.; Esther, A. Carmel Mary; Bhavanisankar, Prudhivi Yashwantkumar; Sherikar, Baburao N.; Sridhara, N.; Dey, Arjun

    2018-03-01

    The feasibility of utilizing commercially available silica aerogel-based flexible composite blankets as passive thermal control element in applications such as extraterrestrial environments is investigated. Differential scanning calorimetry showed that aerogel blanket was thermally stable over - 150 to 126 °C. The outgassing behavior, e.g., total mass loss, collected volatile condensable materials, water vapor regained and recovered mass loss, was within acceptable range recommended for the space applications. ASTM tension and tear tests confirmed the material's mechanical integrity. The thermo-optical properties remained nearly unaltered in simulated space environmental tests such as relative humidity, thermal cycling and thermo-vacuum tests and confirmed the space worthiness of the aerogel. Aluminized Kapton stitched or anchored to the blanket could be used to control the optical transparency of the aerogel. These outcomes highlight the potential of commercial aerogel composite blankets as passive thermal control element in spacecraft. Structural and chemical characterization of the material was also done using scanning electron microscopy, Fourier transform infrared spectroscopy and x-ray photoelectron spectroscopy.

  14. Electrochromatographic performance of conventional and polar-embedded C16 silica monolithic stationary phases.

    Science.gov (United States)

    Ye, Fanggui; Huang, Baojun; Wang, Shun; Zhao, Shulin

    2010-11-01

    A novel monolithic silica column that has a polar-embedded amide-secondary amine group linking with C16 functionality for RP-CEC is described. The amide-secondary aminealkyloxysilane was synthesized by the reaction of 3-(2-aminoethylamino) propyltrimethoxysilane with hexadecanoyl chloride. Then, the silylant agent was bonded to the silica monolith matrix to produce hexadecanamide-secondary amine bonded silica (HDAIS) monolithic column. The electrochromatographic performance of HDAIS monolithic column for the separation of neutral, basic and polar solutes was studied, which was compared to that using the hexadecyl bonded silica monolithic column. The HDAIS monolithic column displayed reduced hydrophobic retention characteristics in the separation of five hydrophobic n-alkylbenzenes and four polar phenols when compared to the hexadecyl bonded silica monolithic column. A very much reduced silanol activity of HDAIS monolithic column was observed in the separation of test basic mixture including four aromatic amines, atenolol and metoprolol with 10 mM borate buffer (pH 7.5) containing 30% v/v ACN as the mobile phase. The comparison results indicate good performance for both polar and basic mixtures on HDAIS monolithic column in RP-CEC, and also show promising results for further applications.

  15. Study of silica (Titania) aerogels using MYSANS at MINT 1 MW TRIGA reactor

    International Nuclear Information System (INIS)

    Abdul Aziz Mohamed; Faridah Mohd Idris; Razali Kassim

    2006-01-01

    Small angle neutron scattering (SANS) technique has been widely employed in probing the microstructure of amorphous materials in the nano structure range; 1-100 nm. In this study, SANS was used to study the structure of the silica aerogels with and without titania nanoparticles. In aerogel system, the size range of 1 to 100 nm is of particular interest since the structural units, such as the pores and particles often fall in this range. Data collected was consistent with present models for the structure of silica aerogels, and an increase in mass fractal dimension from 2.3 to 2.6 for titania containing aerogels was observed. Preliminary SANS data was collected using the MYSANS instrument on the MINT PUSPATI TRIGA reactor. The neutron beam has a wavelength of 0.5 nm. The sample in powder form had dimensions 18x37mm 2 and 2 mm path length. The complete data collection consists of three measurements: sample scattering, empty sample holder scattering, and detector dark current. The scattered neutrons were detected by a 128 x 128 array area sensitive detector, proportional counter (PSD). The resulting 2D patterns were reduced to 1D profiles for further analysis. Plots of intensity, I(Q) versus momentum transfer, Q, were derived. For comparison of this work, the samples had been analysed using BATAN SANS facility. This work has demonstrated that SANS facility at MINT, mySANS, is capable to provide information of fractal dimension. (Author)

  16. Synthesis of Silica Aerogel from Bagasse Ash by Ambient Pressure Drying

    Science.gov (United States)

    Setyawan, Nazriati Heru; Winardi, Sugeng

    2011-12-01

    Silica aerogels having very high surface area and pore volume have been succesfully synthesized from bagasse ash by ambient pressure drying (APD) method. Silica in bagasse ash was extracted by alkali extraction to produce sodium silicate solution. This is done by boiling bagasse ash in 2 N NaOH solution under continuous stirring for 1 h. To avoid the collapse of gel structure during drying at ambient pressure condition, the silica surface was modified with alkyl functional groups by a single step sol-gel process. Silicic acid produced by exchanging Na+ ions in dilute sodium silicate solution with H+ ions from cation resin was added with trimethylchlorosilane (TMCS) and let the reaction of TMCS with water pore proceeds for several minutes to produce hexamethyldisilazane (HMDS) and HCl. Then, HMDS was added to allow the modification of silica surface in which the silanol groups were exchanged with alkyl groups originating from HMDS. The solution pH was then adjusted to 8-9 by adding NH4OH solution to induce gel formation. The hydrogel was aged at 40 °C for 18 h and at 60 °C for 1 h. Then, it was dried at 80 °C at ambient pressure condition. The silica aerogels obtained have specific surface, as measured by BET method, ranging from 450.2 to 1360.4 m2/g depending on the synthesis condition. The pore volume was ranging from 0.7 to 1.9 cm3/g. It seems that silica aerogels with very high surface area and pore volume can be obtained if the silanols group in the silica surface was exchanged succesfully with alkyl groups from HMDS.

  17. Selective epoxidation of allylic alcohols with a titania-silica aerogel

    Energy Technology Data Exchange (ETDEWEB)

    Dusi, M.; Mallat, T.; Baiker, A. [Lab. of Technical Chemistry, Swiss Federal Inst. of Technology, ETH-Zentrum, Zuerich (Switzerland)

    1998-12-31

    An amorphous mesoporous titania-silica aerogel (20 wt%TiO{sub 2} - 80 wt% SiO{sub 2}) and tert.-butylhydroperoxide (TBHP) have been used for the epoxidation of various allylic alcohols. Allylic alcohols possessing an internal double bond were more reactive than those with a terminal C=C bond. Epoxide selectivities could be improved by addition of (basic) zeolite 4 A and NaHCO{sub 3} to the reaction mixture. (orig.)

  18. Histological evaluation of the biocompatibility of polyurea crosslinked silica aerogel implants in a rat model: a pilot study.

    Directory of Open Access Journals (Sweden)

    Firouzeh Sabri

    Full Text Available BACKGROUND: Aerogels are a versatile group of nanostructured/nanoporous materials with physical and chemical properties that can be adjusted to suit the application of interest. In terms of biomedical applications, aerogels are particularly suitable for implants such as membranes, tissue growth scaffolds, and nerve regeneration and guidance inserts. The mesoporous nature of aerogels can also be used for diffusion based release of drugs that are loaded during the drying stage of the material. From the variety of aerogels polyurea crosslinked silica aerogels have the most potential for future biomedical applications and are explored here. METHODOLOGY: This study assessed the short and long term biocompatibility of polyurea crosslinked silica aerogel implants in a Sprague-Dawley rat model. Implants were inserted at two different locations a subcutaneously (SC, at the dorsum and b intramuscularly (IM, between the gluteus maximus and biceps femoris of the left hind extremity. Nearby muscle and other internal organs were evaluated histologically for inflammation, tissue damage, fibrosis and movement (travel of implant. CONCLUSION/SIGNIFICANCE: In general polyurea crosslinked silica aerogel (PCSA was well tolerated as a subcutaneous and an intramuscular implant in the Sprague-Dawley rat with a maximum incubation time of twenty months. In some cases a thin fibrous capsule surrounded the aerogel implant and was interpreted as a normal response to foreign material. No noticeable toxicity was found in the tissues surrounding the implants nor in distant organs. Comparison was made with control rats without any implants inserted, and animals with suture material present. No obvious or noticeable changes were sustained by the implants at either location. Careful necropsy and tissue histology showed age-related changes only. An effective sterilization technique for PCSA implants as well as staining and sectioning protocol has been established. These studies

  19. Recent advances in preparation and application of hybrid organic-silica monolithic capillary columns.

    Science.gov (United States)

    Ou, Junjie; Lin, Hui; Zhang, Zhenbin; Huang, Guang; Dong, Jing; Zou, Hanfa

    2013-01-01

    Hybrid organic-silica monolithic columns, regarded as a second generation of silica-based monoliths, have received much interest due to their unique properties over the pure silica-based monoliths. This review mainly focuses on development in the fields of preparation of hybrid monolithic columns in a capillary and their application for CEC and capillary liquid chromatography separation, as well as for sample pretreatment of solid-phase microextraction and immobilized enzyme reactor since July 2010. The preparation approaches are comprehensively summarized with three routes: (i) general sol-gel process using trialkoxysilanes and tetraalkoxysilanes as coprecursors; (ii) "one-pot" process of alkoxysilanes and organic monomers concomitantly proceeding sol-gel chemistry and free radical polymerization; and (iii) other polymerization approaches of organic monomers containing silanes. The modification of hybrid monoliths containing reactive groups to acquire the desired surface functionality is also described. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Facile preparation of silver nanoparticles homogeneously immobilized in hierarchically monolithic silica using ethylene glycol as reductant.

    Science.gov (United States)

    Yu, Huan; Zhu, Yang; Yang, Hui; Nakanishi, Kazuki; Kanamori, Kazuyoshi; Guo, Xingzhong

    2014-09-07

    A facile and "green" method was proposed to introduce Ag nanoparticles (Ag NPs) into the hierarchically monolithic silica uniformly in the presence of (3-aminopropyl)-triethoxysilane (APTES) and ethylene glycol. APTES is used to modify the monolith by incorporating amino groups onto the surface of meso-macroporous skeletons, while ethylene glycol is employed as the productive reductant. Ag NPs are homogeneously immobilized in hierarchically monolithic silica after reduction and drying at 40 °C for different duration times, and the embedded amount of Ag NPs can reach 15.44 wt% when treated once. The embedment of Ag NPs increases with the repeat treatment and the APTES amount, without uncontrollable crystalline growth. The surface areas of Ag NPs embedded in silica monoliths after heat treatment at 300 and 400 °C are higher than those before heat treatment. The modification via APTES and the embedment of Ag NPs does not spoil the morphology of monolithic silica, while changing the pore structures of the monolith. A tentative formation process and a reduction mechanism are proposed for the modification, reduction and embedment. Ag NPs embedded in monolithic silica is promising for wide applications such as catalysis and separation.

  1. Formation of bimodal porous silica-titania monoliths by sol-gel route

    Energy Technology Data Exchange (ETDEWEB)

    Ruzimuradov, O N, E-mail: ruzimuradov@rambler.ru [Department of General Chemistry, Faculty of Chemistry, National University of Uzbekistan, 15, Vuzgorodok, Tashkent, 100174 (Uzbekistan)

    2011-10-29

    Silica-titania monoliths with micrometer-scale macroporous and nanometer-scale mesoporous structure and high titania contents are prepared by sol-gel process and phase separation. Titanium alkoxide precursor was not effective in the preparation of high titania content composites because of strong decrease in phase separation tendency. Bimodal porous gels with high titania content were obtained by using inorganic salt precursors such as titanium sulfate and titanium chloride. Various characterization techniques, including SEM, XRD, Hg porosimetry and N{sub 2} adsorption have been carried out to investigate the formation process and physical-chemical properties of silica-titania monoliths. The characterization results show that the silica-titania monoliths possess a bimodal porous structure with well-dispersed titania inside silica network. The addition of titania in silica improves the thermal stability of both macroporous and mesoporous structures.

  2. Effect of mixed Catalysts system on TEOS-based silica aerogels dried at ambient pressure

    Science.gov (United States)

    Gurav, Jyoti L.; Nadargi, Digambar Y.; Rao, A. Venkateswara

    2008-12-01

    In the present paper, the experimental results on the effect of mixed Catalysts system on the physical properties of the TEOS-based silica aerogels, are reported and discussed. The aerogels were produced by the single-step as well as two-step sol-gel process followed by atmospheric pressure drying. In the single-step process, only the NH 4F was used as a catalyst, whereas in the two-step process, NH 4F as well as a mixed catalysts, i.e., NH 4F and NH 4OH, were used after 12 h of acid (oxalic acid) addition. Effect of various exchanging solvents, viz., xylene, toluene, heptane or hexane and silylating agents, viz., MTMS, TMES, TMCS, HMDSO or HMDZ on the physical properties of the as prepared aerogels were studied. The volume of the NH 4OH, the molar ratios of MeOH/TEOS and HMDZ/TEOS were varied from 0.2 to 1 ml, and 5.5 to 27.5, 0.34 to 0.9, respectively, by keeping the volume of NH 4F and the concentrations of NH 4F and NH 4OH constant at 0.5 ml, 0.1 and 1 M, respectively. Remarkable results were obtained by using mixed catalyst system, hexane as exchanging solvent and surface chemical modification with 5% HMDZ in hexane. The aerogels were characterized by bulk density, optical transmission, thermal stability and contact angle measurements. The surface chemical modification was confirmed by Fourier Transform Infrared (FTIR) spectroscopy. The microstructural studies of the aerogels were done by Transmission Electron Microscopy (TEM), which revealed highly ramified self-similar polymeric structure in large length scale. The thermal stability of the aerogels were tested using TG-DT analyses. It was found that low bulk density (0.065 g/cm 3), superhydrophobic (153°), high thermal stability (380 °C) and high optical transmission (95%) of the as produced aerogels obtained at the molar ratio of TEOS:MeOH:oxalic acid:NH 4F:NH 4OH:HMDZ for 1:16.5:0.81:0.62:0.63:0.41, respectively.

  3. Effect of mixed Catalysts system on TEOS-based silica aerogels dried at ambient pressure

    Energy Technology Data Exchange (ETDEWEB)

    Gurav, Jyoti L.; Nadargi, Digambar Y. [Air Glass Laboratory, Shivaji University, Kolhapur 416004, Maharashtra (India); Rao, A. Venkateswara [Air Glass Laboratory, Shivaji University, Kolhapur 416004, Maharashtra (India)], E-mail: raouniv@yahoo.com

    2008-12-30

    In the present paper, the experimental results on the effect of mixed Catalysts system on the physical properties of the TEOS-based silica aerogels, are reported and discussed. The aerogels were produced by the single-step as well as two-step sol-gel process followed by atmospheric pressure drying. In the single-step process, only the NH{sub 4}F was used as a catalyst, whereas in the two-step process, NH{sub 4}F as well as a mixed catalysts, i.e., NH{sub 4}F and NH{sub 4}OH, were used after 12 h of acid (oxalic acid) addition. Effect of various exchanging solvents, viz., xylene, toluene, heptane or hexane and silylating agents, viz., MTMS, TMES, TMCS, HMDSO or HMDZ on the physical properties of the as prepared aerogels were studied. The volume of the NH{sub 4}OH, the molar ratios of MeOH/TEOS and HMDZ/TEOS were varied from 0.2 to 1 ml, and 5.5 to 27.5, 0.34 to 0.9, respectively, by keeping the volume of NH{sub 4}F and the concentrations of NH{sub 4}F and NH{sub 4}OH constant at 0.5 ml, 0.1 and 1 M, respectively. Remarkable results were obtained by using mixed catalyst system, hexane as exchanging solvent and surface chemical modification with 5% HMDZ in hexane. The aerogels were characterized by bulk density, optical transmission, thermal stability and contact angle measurements. The surface chemical modification was confirmed by Fourier Transform Infrared (FTIR) spectroscopy. The microstructural studies of the aerogels were done by Transmission Electron Microscopy (TEM), which revealed highly ramified self-similar polymeric structure in large length scale. The thermal stability of the aerogels were tested using TG-DT analyses. It was found that low bulk density (0.065 g/cm{sup 3}), superhydrophobic (153 deg.), high thermal stability (380 deg. C) and high optical transmission (95%) of the as produced aerogels obtained at the molar ratio of TEOS:MeOH:oxalic acid:NH{sub 4}F:NH{sub 4}OH:HMDZ for 1:16.5:0.81:0.62:0.63:0.41, respectively.

  4. Preparation and application of organic-silica hybrid monolithic capillary columns.

    Science.gov (United States)

    Wu, Minghuo; Wu, Ren'an; Zhang, Zhenbin; Zou, Hanfa

    2011-01-01

    Organic-silica hybrid monolithic columns have drawn more and more attention due to the ease of preparation and good mechanical stability in recent years. Many synthetic approaches have been developed and a variety of hybrid monolithic capillary columns have been prepared. The sol-gel process is well recognized in the fabrication of hybrid monolithic columns, which can be mainly classified as one-step, acid/base two-step procedures. The new approaches such as the "one-pot" and nano-scaled inorganic-organic hybrid reagent of polyhedral oligomeric silsesquioxane used as a cross-linker have also emerged for the preparation of hybrid monolithic columns. The applications of the organic-silica hybrid monolithic capillary columns for capillary electrochromatography, micro high-performance liquid chromatography, solid-phase micro-extraction and enzymatic reactor etc. are included in this review. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Investigation of polyurea-crosslinked silica aerogels as a neuronal scaffold: a pilot study.

    Directory of Open Access Journals (Sweden)

    Firouzeh Sabri

    Full Text Available BACKGROUND: Polymer crosslinked aerogels are an attractive class of materials for future implant applications particularly as a biomaterial for the support of nerve growth. The low density and nano-porous structure of this material combined with large surface area, high mechanical strength, and tunable surface properties, make aerogels materials with a high potential in aiding repair of injuries of the peripheral nervous system. however, the interaction of neurons with aerogels remains to be investigated. METHODOLOGY: In this work the attachment and growth of neurons on clear polyurea crosslinked silica aerogels (PCSA coated with: poly-L-lysine, basement membrane extract (BME, and laminin1 was investigated by means of optical and scanning electron microscopy. After comparing the attachment and growth capability of neurons on these different coatings, laminin1 and BME were chosen for nerve cell attachment and growth on PCSA surfaces. The behavior of neurons on treated petri dish surfaces was used as the control and behavior of neurons on treated PCSA discs was compared against it. CONCLUSIONS/SIGNIFICANCE: This study demonstrates that: 1 untreated PCSA surfaces do not support attachment and growth of nerve cells, 2 a thin application of laminin1 layer onto the PCSA discs adhered well to the PCSA surface while also supporting growth and differentiation of neurons as evidenced by the number of processes extended and b3-tubulin expression, 3 three dimensional porous structure of PCSA remains intact after fixing protocols necessary for preservation of biological samples and 4 laminin1 coating proved to be the most effective method for attaching neurons to the desired regions on PCSA discs. This work provides the basis for potential use of PCSA as a biomaterial scaffold for neural regeneration.

  6. Dimensional and Structural Control of Silica Aerogel Membranes for Miniaturized Motionless Gas Pumps.

    Science.gov (United States)

    Zhao, Shanyu; Jiang, Bo; Maeder, Thomas; Muralt, Paul; Kim, Nayoung; Matam, Santhosh Kumar; Jeong, Eunho; Han, Yen-Lin; Koebel, Matthias M

    2015-08-26

    With growing public interest in portable electronics such as micro fuel cells, micro gas total analysis systems, and portable medical devices, the need for miniaturized air pumps with minimal electrical power consumption is on the rise. Thus, the development and downsizing of next-generation thermal transpiration gas pumps has been investigated intensively during the last decades. Such a system relies on a mesoporous membrane that generates a thermomolecular pressure gradient under the action of an applied temperature bias. However, the development of highly miniaturized active membrane materials with tailored porosity and optimized pumping performance remains a major challenge. Here we report a systematic study on the manufacturing of aerogel membranes using an optimized, minimal-shrinkage sol-gel process, leading to low thermal conductivity and high air conductance. This combination of properties results in superior performance for miniaturized thermomolecular air pump applications. The engineering of such aerogel membranes, which implies pore structure control and chemical surface modification, requires both chemical processing know-how and a detailed understanding of the influence of the material properties on the spatial flow rate density. Optimal pumping performance was found for devices with integrated membranes with a density of 0.062 g cm(-3) and an average pore size of 142.0 nm. Benchmarking of such low-density hydrophobic active aerogel membranes gave an air flow rate density of 3.85 sccm·cm(-2) at an operating temperature of 400 °C. Such a silica aerogel membrane based system has shown more than 50% higher pumping performance when compared to conventional transpiration pump membrane materials as well as the ability to withstand higher operating temperatures (up to 440 °C). This study highlights new perspectives for the development of miniaturized thermal transpiration air pumps while offering insights into the fundamentals of molecular pumping in

  7. Fabrication and characterization of silica aerogel as synthetic tissues for medical imaging phantoms

    Science.gov (United States)

    In, Eunji; Naguib, Hani

    2015-05-01

    Medical imaging plays an important role in the field of healthcare industry both in clinical settings and in research and development. It is used in prevention, early detection of disease, in choosing the optimal treatment, during surgical interventions and monitoring of the treatment effects. Despite much advancement in the last few decades, rapid change on its technology development and variety of imaging parameters that differ with the manufacturer restrict its further development. Imaging phantom is a calibrating medium that is scanned or imaged in the field of medical imaging to evaluate, analyze and tune the performance of various imaging devices. A phantom used to evaluate an imaging device should respond in a similar manner to how human tissue and organs would act in that specific imaging modality. There has been many research on the phantom materials; however, there has been no attempt to study on the material that mimics the structure of lung or fibrous tissue. So with the need for development of gel with such structure, we tried to mimic this structure with aerogel. Silica aerogels have unique properties that include low density (0.003g/cm) and mesoporosity (pore size 2-50nm), with a high thermal insulation value (0.005W/mK) and high surface area (500-1200m-2/g).] In this study, we cross-linked with di-isocyanate, which is a group in polyurethane to covalently bond the polymer to the surface of silica aerogel to enhance the mechanical properties. By formation of covalent bonds, the structure can be reinforced by widening the interparticle necks while minimally reducing porosity.

  8. Development of windows based on highly insulating aerogel glazings

    DEFF Research Database (Denmark)

    Jensen, Karsten Ingerslev; Schultz, Jørgen Munthe; Kristiansen, Finn Harken

    2004-01-01

    Within a finished and a current EU project, research and development of monolithic silica aerogel as transparent insulation in windows are being carried out. On behalf of the partners of the two projects, results related to the window application will be presented here. At the thermal envelope...

  9. Solvothermal removal of the organic template from L 3 ("sponge") templated silica monoliths

    Science.gov (United States)

    Dabbs, Daniel M.; Mulders, Norbert; Aksay, Ilhan A.

    2006-10-01

    We compare the methods of continuous solvent (Soxhlet) and supercritical solvent extractions for the removal of the organic template from nanostructured silica monoliths. Our monoliths are formed by templating the L 3 liquid crystal phase of cetylpyridinium chloride in aqueous solutions with tetramethoxy silane. The monoliths that result from both Soxhlet and supercritical extraction methods are mechanically robust, optically clear, and free of cracks. The Soxhlet method compares favorably with supercritical solvent extraction in that equivalent L 3-templated silica can be synthesized without the use of specialized reactor hardware or higher temperatures and high pressures, while avoiding noxious byproducts. The comparative effectiveness of various solvents in the Soxhlet process is related to the Hildebrand solubility parameter, determined by the effective surface area of the extracted silica.

  10. On the correlation between the porous structure and the electrochemical response of powdered and monolithic carbon aerogels as electrodes for capacitive deionization

    Energy Technology Data Exchange (ETDEWEB)

    Macías, C., E-mail: carlosmacias@nanoquimia.com [Nanoquimia S.L., PCT Rabanales 21, Ed. Aldebarán M.4.3., 14014 Córdoba (Spain); Lavela, P. [Laboratorio de Química Inorgánica, Universidad de Córdoba, Marie Curie, Campus de Rabanales, 14071 Córdoba (Spain); Rasines, G. [Nanoquimia S.L., PCT Rabanales 21, Ed. Aldebarán M.4.3., 14014 Córdoba (Spain); Zafra, M.C.; Tirado, J.L. [Laboratorio de Química Inorgánica, Universidad de Córdoba, Marie Curie, Campus de Rabanales, 14071 Córdoba (Spain); Ania, C.O. [ADPOR Group, Instituto Nacional del Carbón (INCAR), CSIC, Apdo. 73, 33080 Oviedo (Spain)

    2016-10-15

    The combined effect of resorcinol/catalyst (100≤R/C≤800) and resorcinol/water (0.04≤R/W≤0.13) molar ratio on the textural and capacitive properties of carbon aerogels with potential application for capacitive deionization has been evaluated. Activated and pyrolyzed aerogels were synthesized by the sol-gel polymerization of resorcinol-formaldehyde mixtures and dried in supercritical conditions. Data show that high R/C and R/W molar ratios lead to materials with large pores in the mesopore range, whereas the surface area and micropore volumes remain somewhat the same. The activation of the aerogels increased the differences in the specific surface and micropore volumes due to the development of microporosity. This effect was more remarkable for the samples with low R/C whatever the R/W ratio, indicating that the carbon aerogel obtained using high amounts of catalyst are more prone to be activated. Regarding the electrochemical features of the aerogels, low capacitance values were measured in aerogels combining low R/W and high R/C and reciprocally low R/C and high R/W molar ratios, due to their higher resistance. Polarization resistances were found to be slightly higher for the pyrolyzed than for activated aerogels, and followed a decreasing trend with the mesoporosity, indicating the outstanding contribution of the mesoporous network to provide a good kinetic response. The desalting capacity of monolithic aerogels showed a simultaneous dependence with the surface area and the resistivity of the electrodes, pointing out the importance of performing electrochemical measurements in adequate cell configurations (i.e., desalting units) upon the intended application. - Graphical abstract: The textural properties of carbon aerogels are strongly influenced by the synthesis parameters precursor to catalyst (R/C) and water (R/C) ratios. The volumetric capacitance measured in a symmetric cell with monolithic electrodes of carbon aerogel strongly correlates with both

  11. [Preparation of C18-silica hybrid monolithic capillary column by "one-pot" process and its application].

    Science.gov (United States)

    Zhang, Zhenbin; Ou, Junjie; Dong, Jing; Wang, Fangjun; Wu, Minghuo; Lin, Hui; Zou, Hanfa

    2011-09-01

    A "one-pot" process for the preparation of organic-silica hybrid capillary monolithic column by concurrently using tetramethoxysilane (TMOS), vinyltrimethoxysilane (VTMS) and the organic monomer, N-(2-(methacryloyloxy) ethyl) dimethyl-octadecylammonium bromide (MDOAB), is described. The polycondensation of alkoxysilanes and the copolymerization of MDOAB and VTMS were subsequently carried out within the confines of a capillary under the proper reaction conditions. The performance of the C18-silica hybrid monolithic column was investigated by capillary electrochromatography and capillary liquid chromatography. In addition, the C18-silica hybrid capillary monolithic column was also applied in the analysis of tryptic digests of bovine serum albumin by capillary liquid chromatography/tandem mass spectrometry (CLC-MS/MS) for demonstrating its potential in proteome analysis. This in situ process of incorporating functional groups into silica monolith provides a new way for the preparation of the organic-silica hybrid monolithic column.

  12. Fabrication of a silica aerogel and examination of its hydrophobic properties via contact angle and 3M water repellency tests

    Science.gov (United States)

    Mazrouei-Sebdani, Z.; Javazmi, L.; Khoddami, A.; Shams-Ghahfarokhi, F.; Low, T.

    2017-05-01

    Aerogels are dry gels with a very high specific pore volume. Aerogels with increased hydrophobicity have significant potential to expand their use as lightweight materials. Considering its special nanostructure and exceptional properties, this paper focuses on the synthesis and hydrophobic evaluation of a silica aerogel. The structural properties were investigated by measuring density, SEM micrographs, and BET analyses. Also, the hydrophobic evaluation was carried out by measuring 3M water repellency and water/alcohol contact angle. The BET analysis showed successful synthesis of the nanoporous silica aerogel with a pore size of 24 nm and porosity of 89%. The synthesized aerogel showed 3M water repellency of 3 and water contact angle of 129.6°. Also, it is worth-mentioning that as the alcohol content of the drops in 3M water repellency test is increased, the drop contact angle is decreased due to its lower surface tension. Thus, the contact angle reaches the zero at 3M water repellency test number of 4 (water/alcohol 60/40).

  13. Silica aerogel radiator for use in the A-RICH system utilized in the Belle II experiment

    Science.gov (United States)

    Tabata, Makoto; Adachi, Ichiro; Hamada, Nao; Hara, Koji; Iijima, Toru; Iwata, Shuichi; Kakuno, Hidekazu; Kawai, Hideyuki; Korpar, Samo; Križan, Peter; Kumita, Tetsuro; Nishida, Shohei; Ogawa, Satoru; Pestotnik, Rok; Šantelj, Luka; Seljak, Andrej; Sumiyoshi, Takayuki; Tahirović, Elvedin; Yoshida, Keisuke; Yusa, Yosuke

    2014-12-01

    This paper presents recent progress in the development and mass production of large-area hydrophobic silica aerogels for use as radiators in the aerogel-based ring-imaging Cherenkov (A-RICH) counter, which will be installed in the forward end cap of the Belle II detector. The proximity-focusing A-RICH system is especially designed to identify charged kaons and pions. The refractive index of the installed aerogel Cherenkov radiators is approximately 1.05, and we aim for a separation capability exceeding 4σ at momenta up to 4 GeV/c. Large-area aerogel tiles (over 18×18×2 cm3) were first fabricated in test productions by pin drying in addition to conventional methods. We proposed to fill the large end-cap region (area 3.5 m2) with 124 water-jet-trimmed fan-shaped dual-layer-focusing aerogel combinations of different refractive indices (1.045 and 1.055). Guided by the test production results, we decided to manufacture aerogels by the conventional method and are currently proceeding with mass production. In an electron beam test undertaken at the DESY, we confirmed that the K/π separation capability of a prototype A-RICH counter exceeded 4σ at 4 GeV/c.

  14. Preparation of phenylboronic acid-silica hybrid monolithic column with one-pot approach for capillary liquid chromatography of biomolecules.

    Science.gov (United States)

    Lin, Zian; Huang, Hui; Li, Shihua; Wang, Juan; Tan, Xiaoqing; Zhang, Lan; Chen, Guonan

    2013-01-04

    A phenylboronic acid-silica hybrid monolithic column for capillary liquid chromatography (cLC) was prepared through one-pot process by using 4-vinylphenylboronic acid (VPBA) and alkoxysilanes simultaneously. The effects of the molar ratio of tetramethyloxysilane/γ-methacryloxypropyltrimethoxysilane (TMOS/γ-MAPS), amount of VPBA, and the volume of diethylene glycol (DEG) on the morphologies, permeabilities and pore properties of the prepared VPBA-silica hybrid monolithic columns were studied in detail. A relatively uniform monolithic structure with high porosity was obtained with optimized ingredients. A series of cis-diol-containing compounds, alkylbenzenes, amides, and anilines were utilized to evaluate the retention behaviors of the VPBA-silica hybrid monolithic column. The result demonstrated that the prepared VPBA-silica hybrid monolithic column exhibited multiple interactions including hydrophobicity, hydrophilicity, as well as cation exchange apart from the expected affinity interaction. The run-to-run, column-to-column and batch-to-batch reproducibility of the VPBA-silica hybrid monolith were satisfactory with the relative standard deviations (RSDs) less than 1.63% (n=5), 2.02% (n=3) and 2.90% (n=5), respectively, indicating the effectiveness and practicability of the proposed method. In addition, the VPBA-silica hybrid monolithic column was further applied to the separation of proteins and tryptic digest of bovine serum albumin (BSA), respectively. The successful applications suggested the potential of the VPBA-silica hybrid monolith in proteome analysis. Copyright © 2012 Elsevier B.V. All rights reserved.

  15. A new route for preparation of sodium-silicate-based hydrophobic silica aerogels via ambient-pressure drying

    Directory of Open Access Journals (Sweden)

    Uzma K H Bangi, A Venkateswara Rao and A Parvathy Rao

    2008-01-01

    Full Text Available An in-depth investigation into the synthesis of hydrophobic silica aerogels prepared by the surface derivatization of wet gels followed by subsequent drying at ambient pressure is reported. The following sol–gel parameters were examined for their effect on the physical properties of the derived aerogels: number of gel washings with water, percentage of hexane or methanol in silylating mixture, molar ratio of tartaric acid: Na2SiO3, gel aging period, weight% of silica, trimethylchlorosilane (TMCS percentage, and silylation period. These parameters were varied from 1 to 4, 0 to 100%, 0.27 to 1.2, 0 to 4 h, 1.5 to 8 wt.%, 20 to 40% and 6 to 24 h, respectively. The properties of hydrophobic silica aerogels synthesized by this new route were investigated in terms of bulk density, percentage volume shrinkage, percentage porosity, thermal conductivity and contact angle with water, and by Fourier transform infrared spectroscopy (FTIR. The as-prepared hydrophobic silica aerogels exhibited high temperature stability (up to approximately 435 °C as measured by thermogravimetric/differential thermal analysis (TGA-DTA. The optimal sol-gel parameters were found to be a molar ratio of Na2SiO3:H2O : tartaric acid : TMCS of 1 : 146.67 : 0.86 : 9.46, an aging period of 3 h, four washings with water in 24 h and the use of a 50% hexane- or methanol-based silylating mixture. Aerogels prepared with these optimal parameters were found to exhibit 50% optical transparency in the visible range, 84 kg m−3 density, 0.090 W mK−1 thermal conductivity, 95% porosity and a contact angle of 146° with water.

  16. Compressive properties of silica aerogel at 295, 76, and 20K

    International Nuclear Information System (INIS)

    Arvidson, J.M.; Scull, L.L.

    1986-01-01

    Specimens of silica aerogel were tested in compression at 295, 76, and 20 K in a helium gas environment. The properties reported include Young's modulus, the proportional limit, and yield strength. Compressive stress-versus-strain curves at these temperatures are also given. A test apparatus was developed specifically to determine the compressive properties of low strength materials. To measure specimen strain a concentric, overlapping-cylinder, capacitance extensometer was developed. This frictionless device has the capability to conduct variable temperature tests at any temperature from 1.8 to 295 K. Results from the compression tests indicate that at low temperatures the material is not only stronger, but tougher. During 295-K compression tests, the samples fractured and, in some cases, crumbled. After 76- or 20-K compression tests, the specimens remained intact

  17. Silica monolithic columns : Synthesis, characterisation and applications to the analysis of biological molecules

    NARCIS (Netherlands)

    Rieux, Laurent; Niederländer, Harm; Verpoorte, Elisabeth; Bischoff, Rainer

    In recent years, proteomics has been a subject of intense research. The complexity of proteomics samples has fostered technological developments. One of these addresses the need for more efficient and faster separations. Monolithic columns prepared from organic and silica monomers offer very

  18. Continuous-Flow Monolithic Silica Microreactors with Arenesulphonic Acid Groups: Structure–Catalytic Activity Relationships

    Directory of Open Access Journals (Sweden)

    Agnieszka Ciemięga

    2017-08-01

    Full Text Available The performance of monolithic silica microreactors activated with sulphonic acid groups and a packed bed reactor with Amberlyst 15 resin were compared in the esterification of acetic acid with n-butanol. The monolithic microreactors were made of single silica rods with complex pore architecture, differing in the size of mesopores, and in particular, flow-through macropores which significantly affected the flow characteristic of the continuous system. The highest ester productivity of 105.2 mol·molH+−1·h−1 was achieved in microreactor M1 with the largest porosity, characterized by a total pore volume of 4 cm3·g−1, mesopores with 20 nm diameter, and large flow-through macropores 30–50 μm in size. The strong impact of the permeability of the monoliths on a reaction kinetics was shown.

  19. Comparison of monolithic silica and polymethacrylate capillary columns for LC

    Czech Academy of Sciences Publication Activity Database

    Moravcová, D.; Jandera, P.; Urban, J.; Planeta, Josef

    2004-01-01

    Roč. 27, 10-11 (2004), s. 789-800 ISSN 1615-9306 R&D Projects: GA ČR(CZ) GA203/02/0023 Keywords : monolithic column s * capillary HPLC * column testing Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 1.927, year: 2004

  20. Enantioselective Transamination in Continuous Flow Mode with Transaminase Immobilized in a Macrocellular Silica Monolith

    Directory of Open Access Journals (Sweden)

    Ludivine van den Biggelaar

    2017-02-01

    Full Text Available ω-Transaminases have been immobilized on macrocellular silica monoliths and used as heterogeneous biocatalysts in a continuous flow mode enantioselective transamination reaction. The support was prepared by a sol-gel method based on emulsion templating. The enzyme was immobilized on the structured silica monoliths both by adsorption, and by covalent grafting using amino-functionalized silica monoliths and glutaraldehyde as a coupling agent. A simple reactor set-up based on the use of a heat-shrinkable Teflon tube is presented and successfully used for the continuous flow kinetic resolution of a chiral amine, 4-bromo-α-methylbenzylamine. The porous structure of the supports ensures effective mass transfer and the reactor works in the plug flow regime without preferential flow paths. When immobilized in the monolith and used in the flow reactor, transaminases retain their activity and their enantioselectivity. The solid biocatalyst is also shown to be stable both on stream and during storage. These essential features pave the way to the successful development of an environmentally friendly process for chiral amines production.

  1. Highly Insulating and Light Transmitting Aerogel glazing for Window (HILIT Aerogel Window)

    DEFF Research Database (Denmark)

    The HILIT AEROGEL WINDOW project with participants from Denmark (coordinator), France, Germany, Norway and Sweden, was formulated in order to develop a safe and clean production of monolithic silica aerogel based on supercritical CO2 drying of the gels, to study the process parameters and to tran...... the thermal bridge effect of the rim seal solution is measured to 0.74 W/m2K. The solar energy transmittance is measured to 76% thanks to the use of low-iron glass with an anti reflective coating....

  2. Characterization of stoichiometric nanocrystalline spinel ferrites dispersed on porous silica aerogel.

    Science.gov (United States)

    Casula, M F; Concas, G; Congiu, F; Corrias, A; Loche, D; Marras, C; Spano, G

    2011-11-01

    Stoichiometric magnetic nanosized ferrites MFe2O4 (M = Mn, Co, Ni) were prepared in form of nearly spherical nanocrystals supported on a highly porous silica aerogel matrix, by a sol-gel procedure. X-ray diffraction and transmission electron microscopy indicate that these materials are made out of non-agglomerated ferrite nanocrystals having size in the 5-10 nm range. Investigation by Mössbauer Spectroscopy was used to gain insights on the superparamagnetic relaxation and on the inversion degree. Magnetic ordering at room temperature varies from superparamagnetic in the NiFe2O4 sample, highly blocked (approximately 70%) in the MnFe2O4 sample and nearly fully blocked in the CoFe2O4 sample. A fitting procedure of the Mössbauer data has been used in order to resolve the spectrum into the tetrahedral and octahedral components; in this way, an inversion degree of 0.68 (very close to bulk values) was obtained for 6 nm silica-supported CoFe2O4 nanocrystals.

  3. Polypropylene/hydrophobic-silica-aerogel-composite separator induced enhanced safety and low polarization for lithium-ion batteries

    Science.gov (United States)

    Feng, Guanhua; Li, Zihe; Mi, Liwei; Zheng, Jinyun; Feng, Xiangming; Chen, Weihua

    2018-02-01

    Separator as an important part of lithium-ion batteries, allowing the ion to transfer and preventing the direct contact of anode with cathode, determines the safety of the batteries. In this work, a kind of polypropylene/hydrophobic silica-aerogel-composite (SAC) separator is fabricated through combining hydrophobic silica aerogel and polypropylene (PP) separator. The rationally designed SAC effectively increases the thermal stability of the separator with slightly growing weight (the area retention rate is 30% higher than that of the PP separator after being heated for 30 min at 160 °C). In addition, the hydrophobic silica aerogel layer in SAC significantly improves the wettability of PP separator to electrolyte owning to the introduced hydrophobic functional groups of -Si(CH3)3 and porous structure, and the contact angles of SAC separator to several common organic electrolytes (EC/DMC, DMC/DOL, Diglyme) are close to 0°. Electrochemical tests show that the prepared SAC separator can decrease the polarization of Li-ion batteries and leads to improved power performance and cycle stability. And the SAC separator is firm with neglectable abscission after folding 200 times. This work provides a new way to improve the safety and simultaneously reduce the polarization of the batteries, implying promising application potential in power batteries.

  4. [Reparation and application of perfluorodecyl modified silica monolithic capillary column in extraction and enrichment of perfluorooctane sulfonates].

    Science.gov (United States)

    Huang, Ke; Zhou, Naiyuan; Chen, Bo

    2011-10-01

    A perfluorodecyl modified silica monolithic capillary column has been prepared by using sol-gel method. The preparation steps included hydrolysis of alkoxy silane, fasculation of silanol, gelation, aging, meso-pore preparation, drying and surface modification. It could be used as a solid phase extraction (SPE) microcolumn for extraction and enrichment of perfluorooctane sulfonate (PFOS). The enrichment characteristics and efficiency of the perfluorodecyl modified monolithic silica capillary column has been investigated and compared with C18 silica monolithic capillary column. The results indicated that the perfluorodecyl modified silica monolithic capillary column ( 15 cm x 75 microm) had a higher adsorption capacity and a better enrichment selectivity for PFOS. The average adsorption capacity of the perfluorodecyl modified silica monolithic capillary column was 75 ng. And when the PFOS mass concentration in sample was 0. 25 mg/L, the enrichment factor was 29-fold in average. Owing to the good performance of the perfluorodecyl modified silica monolithic capillary column, it can be used for the extraction and enrichment of trace PFOS in water to meet the requirements of water quality monitoring and analysis.

  5. Optical characterization of /n=1.03 silica aerogel used as radiator in the RICH of HERMES

    Science.gov (United States)

    Aschenauer, E.; Bianchi, N.; Capitani, G. P.; Carter, P.; Casalino, C.; Cisbani, E.; Coluzza, C.; De Leo, R.; De Sanctis, E.; De Schepper, D.; Djordjadze, V.; Filippone, B.; Frullani, S.; Garibaldi, F.; Hansen, J. O.; Hommez, B.; Iodice, M.; Jackson, H. E.; Kaiser, R.; Kanesaka, J.; Lagamba, L.; Muccifora, V.; Nappi, E.; Nowak, W.-D.; O'Neill, T. G.; Potterveld, D.; Ryckbosch, D.; Sakemi, Y.; Sato, F.; Schwind, A.; Suetsugu, K.; Shibata, T.-A.; Thomas, E.; Tytgat, M.; Urciuoli, G. M.; van de Kerckhove, K.; van de Vyver, R.; Yoneyama, S.; Zhang, L. F.

    2000-02-01

    The optical properties of silica aerogel tiles with a refractive index of 1.03 and dimensions 11×11×1 cm3, produced by the Matsushita Electric Works (Japan), have been measured in the wavelength range from 200 to 900 nm. The tiles are used as one of the two radiators of the ring imaging Cherenkov counter of the HERMES experiment at DESY-HERA. The transmittance of light has been measured on 200 tiles by means of a double beam spectrophotometer. The light transflectance and reflectance have been measured on one tile by means of a single-beam spectrophotometer and an integrating reflecting sphere. Typical values of the measured transmittances at a wavelength λ=400 nm are around 0.67. The measured transflectance increases almost linearly from 0.4 to 0.96 in the interval 200-300 nm, and remains nearly constant at the value 0.95 in the complementary λ-range. The measured reflectance, mostly confined below 400 nm, is completely interpretable as backscattering from inside the aerogel, revealing an absence of light reflection at the aerogel surfaces. The transmittance data have been fitted with the Hunt formula, whose parameters have been used to evaluate the number of unscattered and scattered Cherenkov photons produced by aerogel. For stacks of 5 tiles and quantum efficiencies of phototubes with bialkali photocathodes, rings with up to 19 photoelectrons/event can be expected for β=1 particles.

  6. Zwitterionic silica-based monolithic capillary columns for isocratic and gradient hydrophilic interaction liquid chromatography

    Czech Academy of Sciences Publication Activity Database

    Moravcová, Dana; Planeta, Josef; Kahle, Vladislav; Roth, Michal

    2012-01-01

    Roč. 1270, DEC 28 (2012), s. 178-185 ISSN 0021-9673 R&D Projects: GA MV VG20112015021; GA ČR(CZ) GAP206/11/0138; GA ČR(CZ) GAP106/12/0522 Institutional support: RVO:68081715 Keywords : HILIC * Monolithic silica column * Nucleoside separation * Nucleic acid base Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 4.612, year: 2012

  7. Preparation of organic-silica hybrid monolithic columns via crosslinking of functionalized mesoporous carbon nanoparticles for capillary liquid chromatography.

    Science.gov (United States)

    Liu, Shengju; Peng, Jiaxi; Zhang, Hongyan; Li, Xin; Liu, Zheyi; Kang, Xiaohui; Wu, Minghuo; Wu, Ren'an

    2017-05-19

    An organic-silica hybrid monolithic capillary column was fabricated by crosslinking (3-aminopropyl)trimethoxysilane (APTMS) modified mesoporous carbon nanoparticles (AP-MCNs) with tetramethoxysilane (TMOS) and n-butyltrimethoxysilane (C4-TriMOS). Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy, mercury intrusion porosimetry and inverse size-exclusion chromatography characterization proved the successful immobilization of mesoporous carbon nanoparticles (MCNs). The crosslinking of AP-MCNs into the hybrid monolithic matrix has significantly increased the reversed-phase retention of alkylbenzenes and chromatographic performance for small molecules separations in comparison with the neat one without MCNs. The resulting column efficiency of the mesoporous carbon nanoparticle-based butyl-silica hybrid monolithic column (MCN-C4-monolith) was up to ca. 116,600N/m for the capillary liquid chromatography (cLC) separation of butylbenzene. Enhanced performance of proteins separation was achieved on the MCN-C4-monolith in comparison with the butyl-silica hybrid monolithic column without MCN (C4-monolith). The separation of peptides from bovine serum albumin (BSA) digest was carried out on the MCN-C4-monolith by capillary liquid chromatography-tandem mass spectrometry (cLC-MS/MS) with protein sequence coverage of 81.9%, suggesting its potential application in proteomics. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Thermal and Mechanical Properties of Novolac-Silica Hybrid Aerogels Prepared by Sol-Gel Polymerization in Solvent-Saturated Vapor Atmosphere

    Directory of Open Access Journals (Sweden)

    Mohamad Mehdi Seraji1, Seraji

    2015-05-01

    Full Text Available Nowadays organic–inorganic hybrid aerogel materials have attracted increasing interests due to improved thermal and mechanical properties. In the present research, initially, novolac type phenolic resin-silica hybrid gels with different solid concentrations were synthesized using sol-gel polymerization in solvent-saturatedvapor atmosphere. The hybrid gels were dried at air atmosphere through ambient drying process. This method removed the need for costly and risky supercritical drying process. The yields of the obtained hybrid aerogels increased with less shrinkage in comparison with conventional sol-gel process. The precursor of silica phase in this study was tetraethoxysilane and inexpensive novolac resin was used as a reinforcing phase. The results of FTIR analysis confirmed the simultaneous formation of silica and novolac gels in the hybrid systems. The resultant hybrid aerogels showed a nanostructure hybrid network with high porosity (above 80% and low density (below 0.25 g/cm3. Nonetheless, higher content of silica resulted in more shrinkage in the hybrid aerogel structure due to the tendency of the silica network to shrink more during gelation and drying process. The SEM images of samples exhibited a continuous network of interconnected colloidal particles formed during sol-gel polymerization with mean particle size of less than 100 nanometers. Si mapping analysis showed good distribution of silica phase throughout the hybrid structure. The results demonstrated improvements in insulation properties and thermal stability of novolac-silica aerogel with increasing the silica content. The results of compressive strength showed that the mechanical properties of samples declined with increasing the silica content.

  9. Synthesis of Flexible Aerogel Composites Reinforced with Electrospun Nanofibers and Microparticles for Thermal Insulation

    Directory of Open Access Journals (Sweden)

    Huijun Wu

    2013-01-01

    Full Text Available Flexible silica aerogel composites in intact monolith of 12 cm were successfully fabricated by reinforcing SiO2 aerogel with electrospun polyvinylidene fluoride (PVDF webs via electrospinning and sol-gel processing. Three electrospun PVDF webs with different microstructures (e.g., nanofibers, microparticles, and combined nanofibers and microparticles were fabricated by regulating electrospinning parameters. The as-electrospun PVDF webs with various microstructures were impregnated into the silica sol to synthesize the PVDF/SiO2 composites followed by solvent exchange, surface modification, and drying at ambient atmosphere. The morphologies of the PVDF/SiO2 aerogel composites were characterized and the thermal and mechanical properties were measured. The effects of electrospun PVDF on the thermal and mechanical properties of the aerogel composites were evaluated. The aerogel composites reinforced with electrospun PVDF nanofibers showed intact monolith, improved strength, and perfect flexibility and hydrophobicity. Moreover, the aerogel composites reinforced with the electrospun PVDF nanofibers had the lowest thermal conductivity (0.028 W·m−1·K−1. It indicates that the electrospun PVDF nanofibers could greatly improve the mechanical strength and flexibility of the SiO2 aerogels while maintaining a lower thermal conductivity, which provides increasing potential for thermal insulation applications.

  10. Zwitterionic silica-based monolithic capillary columns for isocratic and gradient hydrophilic interaction liquid chromatography.

    Science.gov (United States)

    Moravcová, Dana; Planeta, Josef; Kahle, Vladislav; Roth, Michal

    2012-12-28

    This study introduces zwitterionic monolithic capillary columns intended for isocratic and gradient HILIC separations. Silica-based monolithic capillary columns (100 μm × 150 mm) prepared by acidic hydrolysis of tetramethoxysilane in the presence of polyethylene glycol and urea were modified by a sulfoalkylbetaine zwitterion ([2-(methacryloyloxy)ethyl]-dimethyl-(3-sulfopropyl)-ammonium hydroxide) to HILIC stationary phase. The prepared columns were evaluated under the isocratic and gradient separation conditions using a standard mixture containing nucleic acid bases, nucleosides, and 2-deoxynucleosides. Mobile phases contained high concentration of acetonitrile (95-85%, v/v) and 5-50mM ammonium acetate or ammonium formate in the pH range of 3-6. The synthesized columns showed a long-term stability under the separation conditions while the high permeability and efficiency originating from dual structure of the silica monolith were preserved. The relative standard deviations (RSDs) for the retention times of tested solutes were lower than 2% under the isocratic conditions and lower than 3.5% under the gradient conditions. Copyright © 2012 Elsevier B.V. All rights reserved.

  11. Facile preparation of organic-silica hybrid monolith for capillary hydrophilic liquid chromatography based on "thiol-ene" click chemistry.

    Science.gov (United States)

    Chen, Ming-Luan; Zhang, Jun; Zhang, Zheng; Yuan, Bi-Feng; Yu, Qiong-Wei; Feng, Yu-Qi

    2013-04-05

    In this work, a one-step approach to facile preparation of organic-inorganic hybrid monoliths was successfully developed. After vinyl-end organic monomers and azobisisobutyronitrile (AIBN) were mixed with hydrolyzed tetramethoxysilane (TMOS) and 3-mercaptopropyltrimethoxysilane (MPTMS), the homogeneous mixture was introduced into a fused-silica capillary for simultaneous polycondensation and "thiol-ene" click reaction to form the organic-silica hybrid monoliths. By employing this strategy, two types of organic-silica hybrid monoliths with positively charged quaternary ammonium and amide groups were prepared, respectively. The functional groups were successfully introduced onto the monoliths during the sol-gel process with "thiol-ene" click reaction, which was demonstrated by ζ-potential assessment, energy dispersive X-ray spectroscopy (EDX), and Fourier transform infrared (FT-IR) spectroscopy. The porous structure of the prepared monolithic columns was examined by scanning electron microscopy (SEM), nitrogen adsorption-desorption measurement, and mercury intrusion porosimetry. These results indicate the prepared organic-silica hybrid monoliths possess homogeneous column bed, large specific surface area, good mechanical stability, and excellent permeability. The prepared monolithic columns were then applied for anion-exchange/hydrophilic interaction liquid chromatography. Different types of analytes, including benzoic acids, inorganic ions, nucleosides, and nucleotides, were well separated with high column efficiency around 80,000-130,000 plates/m. Taken together, we present a facile and universal strategy to prepare organic-silica hybrid monoliths with a variety of organic monomers using one-step approach. Copyright © 2013 Elsevier B.V. All rights reserved.

  12. Hydrophilic interaction chromatography using a meter-scale monolithic silica capillary column for proteomics LC-MS.

    Science.gov (United States)

    Horie, Kanta; Kamakura, Takeo; Ikegami, Tohru; Wakabayashi, Masaki; Kato, Takashi; Tanaka, Nobuo; Ishihama, Yasushi

    2014-04-15

    A meter-scale monolithic silica capillary column modified with urea-functional groups for hydrophilic interaction liquid chromatography (HILIC) was developed for highly efficient separation of biological compounds. We prepared a ureidopropylsilylated monolithic silica capillary column with a minimum plate height of 12 μm for nucleosides and a permeability of 2.1 × 10(-13) m(2), which is comparable with the parameters of monolithic silica-C18 capillary columns. Over 300,000 theoretical plates were experimentally obtained in HILIC with a 4 m long column at 8 MPa; this is the best result yet reported for HILIC. A 2 m long ureidopropylsilylated monolithic silica capillary column was utilized to develop a HILIC mode LC-MS system for proteomics applications. Using tryptic peptides from human HeLa cell lysate proteins, we identified the comparable numbers of peptides and proteins in HILIC with those in reversed-phase liquid chromatography (RPLC) using a C18-modified monolithic silica column when shallow gradients were applied. In addition, approximately 5-fold increase in the peak response on average was observed in HILIC for commonly identified tryptic peptides due to the high acetonitrile concentration in the HILIC mobile phase. Since HILIC mode LC-MS shows orthogonal selectivity to RPLC mode LC-MS, it is useful as a complementary tool to increase proteome coverage in proteomics studies.

  13. The preparation of microfluidic architecture with monolithic materials using a dual porous silica structure.

    Science.gov (United States)

    Birch, Christopher; Esfahani, Mohammad Mehdi Nasr; Shaw, Kirsty J; Kemp, Cordula; Haswell, Stephen James; Dyer, Charlotte

    2017-11-01

    A microfluidic device (MD) has been developed which features a porous silica (PS) monolithic disk synthesized from tetramethyl orthosilicate, incorporated into the device post-fabrication and sealed in place with a second PS monolithic layer, synthesized from potassium silicate. This dual porous silica (DPS) structure provides a pathway for sample introduction to the MD and offers an ideal platform for solid phase extraction (SPE) methodologies which can be rapidly and efficiently integrated into a chip-based format. All silica disk manufacture and functionalization was carried out in batch to provide a readily scalable method of production. Application of this design for processing samples was demonstrated using two alternative nucleic acid purification chemistries, yielding polymerase chain reaction amplifiable DNA extracted from 150 μL of human urine in less than 35 min. It is proposed that this DPS system could be further developed for a diverse range of chip-based SPE applications, providing an interface facilitating sample delivery and enabling SPE on-chip. Furthermore, to the author's knowledge it is the first reporting of two different types of PS amalgamated in a single MD. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Controlling the primary particle evolution process towards silica monoliths with tunable hierarchical structure.

    Science.gov (United States)

    Zhou, Yu; Lin, Wei Gang; Yang, Jing; Gao, Ling; Lin, Na; Yang, Jia Yuan; Hou, Qian; Wang, Ying; Zhu, Jian Hua

    2011-12-15

    In order to establish the hierarchical structure in multiple levels on mesoporous silica, this article reports a new strategy to prepare the monolith with the pore configuration in nanometer scale, micro-morphology in micrometer level and macroscopic shape in millimeter or larger grade. These hierarchical monoliths are synthesized in a weak acidic condition by using triblock copolymer P123, hydroxyl carboxylic acid and tetramethyl orthosilicate (TMOS), and the textural properties of the mesostructure can be facilely adjusted by simply controlling the synthesis condition without any additive. During the synthesis, the primary particles can be selectively synthesized as monodispersed sphere, noodle, prism, straight rods with different size or irregular bars, and their connection plus arrangement in 3D directions can be also regulated. Therefore, various textural properties of mesopore are able to be altered including pore size (5.5-10.6 nm), total pore volume (0.48-1.2 cm(3) g(-1)), micropore surface area (47-334 m(2) g(-1)), and pore shape (from 2D or 3D straight channel to plugged channel). Moreover, these monoliths exhibit a considerable mechanical strength; they are also applied in eliminating particulate matters and tobacco special nitrosamines (TSNA) in tobacco smoke, exhibiting various morphology-assisted functions. Copyright © 2011 Elsevier Inc. All rights reserved.

  15. On the underestimated impact of the gelation temperature on macro- and mesoporosity in monolithic silica.

    Science.gov (United States)

    Meinusch, Rafael; Ellinghaus, Rüdiger; Hormann, Kristof; Tallarek, Ulrich; Smarsly, Bernd M

    2017-06-07

    The preparation of monolithic SiO 2 with bimodal porosity using a special sol-gel procedure ("Nakanishi process") generally shows a pronounced sensitivity towards several physico-chemical parameters of the initial solution (concentrations, precursors, pH, temperature, etc.). Thus, temporal and spatial variations of these parameters during the sol-gel reactions can affect the final meso- and macropore space with respect to the pore size distributions and homogeneity. In this study we thoroughly examine the sol-gel reaction in terms of the impact of temperature accuracy and homogeneity during the gelation and their effect on meso- and macropore space. The in-depth characterization of the macroporosity in monolithic SiO 2 rods, prepared by utilizing a highly homogeneous and accurate temperature profile, shows that a decrease of only 1.5 °C during the reaction doubles the mean size of the macropores in the analyzed temperature ranges (22.0-28.0 °C and 33.5-36.5 °C). Rheological measurements of the gelation points and the viscosity of the starting solutions prove that a higher reaction rate is the main reason for this marked temperature-sensitivity. Furthermore, the mesoporosity is affected to a surprising extent by the applied small temperature differences during the gelation reaction. This phenomenon is shown to be mainly caused by the temperature-dependent differences in macropore and skeleton dimensions and an inhomogeneous distribution of mesopore sizes within the skeleton. In essence, our study reveals that the impact of temperature on the formation of meso- and macroscale dimensions during the sol-gel process has been underestimated so far. The impact of a poor temperature homogeneity during monolith synthesis is exemplarily demonstrated by the application of monolithic silica capillary columns in HPLC.

  16. Silica-based monolithic capillary columns modified by liposomes for characterization of analyte–liposome interactions by capillary liquid chromatography

    Czech Academy of Sciences Publication Activity Database

    Moravcová, Dana; Planeta, Josef; Wiedmer, S. K.

    2013-01-01

    Roč. 1317, SI (2013), s. 159-166 ISSN 0021-9673 R&D Projects: GA MV VG20112015021; GA ČR(CZ) GAP206/11/0138 Institutional support: RVO:68081715 Keywords : monolithic silica capillary column * immobilized liposomes * biomimicking stationary phase Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 4.258, year: 2013

  17. Optimization and application of octadecyl-modified monolithic silica for solid-phase extraction of drugs in whole blood samples.

    Science.gov (United States)

    Namera, Akira; Saito, Takeshi; Ota, Shigenori; Miyazaki, Shota; Oikawa, Hiroshi; Murata, Kazuhiro; Nagao, Masataka

    2017-09-29

    Monolithic silica in MonoSpin for solid-phase extraction of drugs from whole blood samples was developed to facilitate high-throughput analysis. Monolithic silica of various pore sizes and octadecyl contents were synthesized, and their effects on recovery rates were evaluated. The silica monolith M18-200 (20μm through-pore size, 10.4nm mesopore size, and 17.3% carbon content) achieved the best recovery of the target analytes in whole blood samples. The extraction proceeded with centrifugal force at 1000rpm for 2min, and the eluate was directly injected into the liquid chromatography-mass spectrometry system without any tedious steps such as evaporation of extraction solvents. Under the optimized condition, low detection limits of 0.5-2.0ngmL -1 and calibration ranges up to 1000ngmL -1 were obtained. The recoveries of the target drugs in the whole blood were 76-108% with relative standard deviation of less than 14.3%. These results indicate that the developed method based on monolithic silica is convenient, highly efficient, and applicable for detecting drugs in whole blood samples. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Monolithic silica-based capillary reversed-phase liquid chromatography/electrospray mass spectrometry for plant metabolomics

    NARCIS (Netherlands)

    Tolstikov, V.V.; Lommen, A.; Nakanishi, K.; Tanaka, N.; Fiehn, O.

    2003-01-01

    Application of C18 monolithic silica capillary columns in HPLC coupled to ion trap mass spectrometry detection was studied for probing the metabolome of the model plant Arabidopsis thaliana. It could be shown that the use of a long capillary column is an easy and effective approach to reduce

  19. Optical characterization of n=1.03 silica aerogel used as radiator in the RICH of HERMES

    CERN Document Server

    Aschenauer, E; Capitani, G P; Carter, P; Casalino, C; Cisbani, E; Coluzza, C; De Leo, R; De Sanctis, E; De Schepper, D; Dzhordzhadze, V; Filippone, B W; Frullani, S; Garibaldi, F; Hansen, J O; Hommez, B; Iodice, M; Jackson, H E; Kaiser, R; Kanesaka, J; Lagamba, L; Muccifora, V; Nappi, E; Nowak, Wolf-Dieter; O'Neill, T G; Potterveld, D; Ryckbosch, D; Sakemi, Y; Sato, F; Schwind, A; Suetsugu, K; Shibata, T A; Thomas, E; Tytgat, M; Urciuoli, G M; Kerckhove, K V D; Vyver, R V D; Yoneyama, S; Zhang, L F

    2000-01-01

    The optical properties of silica aerogel tiles with a refractive index of 1.03 and dimensions 11x11x1 cm sup 3 , produced by the Matsushita Electric Works (Japan), have been measured in the wavelength range from 200 to 900 nm. The tiles are used as one of the two radiators of the ring imaging Cherenkov counter of the HERMES experiment at DESY-HERA. The transmittance of light has been measured on 200 tiles by means of a double beam spectrophotometer. The light transflectance and reflectance have been measured on one tile by means of a single-beam spectrophotometer and an integrating reflecting sphere. Typical values of the measured transmittances at a wavelength lambda=400 nm are around 0.67. The measured transflectance increases almost linearly from 0.4 to 0.96 in the interval 200-300 nm, and remains nearly constant at the value 0.95 in the complementary lambda-range. The measured reflectance, mostly confined below 400 nm, is completely interpretable as backscattering from inside the aerogel, revealing an abs...

  20. Aerogels Handbook

    CERN Document Server

    Aegerter, Michel A; Koebel, Matthias M

    2011-01-01

    Aerogels are the lightest solids known. Up to 1000 times lighter than glass and with a density as low as only four times that of air, they show very high thermal, electrical and acoustic insulation values and hold many entries in Guinness World Records. Originally based on silica, R&D efforts have extended this class of materials to non-silicate inorganic oxides, natural and synthetic organic polymers, carbon, metal and ceramic materials, etc. Composite systems involving polymer-crosslinked aerogels and interpenetrating hybrid networks have been developed and exhibit remarkable mechanical strength and flexibility. Even more exotic aerogels based on clays, chalcogenides, phosphides, quantum dots, and biopolymers such as chitosan are opening new applications for the construction, transportation, energy, defense and healthcare industries. Applications in electronics, chemistry, mechanics, engineering, energy production and storage, sensors, medicine, nanotechnology, military and aerospace, oil and gas recove...

  1. Larnite powders and larnite/silica aerogel composites as effective agents for CO{sub 2} sequestration by carbonation

    Energy Technology Data Exchange (ETDEWEB)

    Santos, A., E-mail: alberto.santos@uca.es [Departamento de Ciencias de la Tierra, Universidad de Cadiz, Puerto Real, 11510 Cadiz (Spain); Ajbary, M.; Morales-Florez, V. [Departamento de Fisica de la Materia Condensada, Universidad de Cadiz, Puerto Real, 11510 Cadiz (Spain); Kherbeche, A. [Universite Sidi Mohamed Ben Abdellah, Ecole Superieure de Technologie, Fes (Morocco); Pinero, M. [Departamento de Fisica Aplicada, Universidad de Cadiz, Puerto Real, 11510 Cadiz (Spain); Esquivias, L. [Departamento de Fisica de la Materia Condensada, Facultad de Fisica, Instituto de Ciencias de Materiales de Sevilla (CSIC), Universidad de Sevilla, 41012 Sevilla (Spain)

    2009-09-15

    This paper presents the results of the carbonation reaction of two sample types: larnite (Ca{sub 2}SiO{sub 4}) powders and larnite/silica aerogel composites, the larnite acting as an active phase in a process of direct mineral carbonation. First, larnite powders were synthesized by the reaction of colloidal silica and calcium nitrate in the presence of ethylene glycol. Then, to synthesize the composites, the surface of the larnite powders was chemically modified with 3-aminopropyltriethoxysilane (APTES), and later this mixture was added to a silica sol previously prepared from tetraethylorthosilicate (TEOS). The resulting humid gel was dried in an autoclave under supercritical conditions for the ethanol. The textures and chemical compositions of the powders and composites were characterized.The carbonation reaction of both types of samples was evaluated by means of X-ray diffraction and thermogravimetric analysis. Both techniques confirm the high efficiency of the reaction at room temperature and atmospheric pressure. A complete transformation of the silicate into carbonate resulted after submitting the samples to a flow of pure CO{sub 2} for 15 min. This indicates that for this reaction time, 1 t of larnite could eliminate about 550 kg of CO{sub 2}. The grain size, porosity, and specific surface area are the factors controlling the reaction.

  2. Degradation of orange dyes and carbamazepine by soybean peroxidase immobilized on silica monoliths and titanium dioxide.

    Science.gov (United States)

    Calza, Paola; Zacchigna, Dario; Laurenti, Enzo

    2016-12-01

    In this paper, the removal of three common dyes (orange I, orange II, and methylorange) and of the anticonvulsant drug carbamazepine from aqueous solutions by means of enzymatic and photocatalytic treatment was studied. Soybean peroxidase (SBP) was used as biocatalyst, both free in solution and immobilized on silica monoliths, and titanium dioxide as photocatalyst. The combination of the two catalysts led to a faster (about two to four times) removal of all the orange dyes compared to the single systems. All the dyes were completely removed within 2 h, also in the presence of immobilized SBP. As for carbamazepine, photocatalytic treatment prevails on the enzymatic degradation, but the synergistic effect of two catalysts led to a more efficient degradation; carbamazepine's complete disappearance was achieved within 60 min with combined system, while up to 2 h is required with TiO 2 only.

  3. Damping and tuning of the fibre violin modes in monolithic silica suspensions

    International Nuclear Information System (INIS)

    Gossler, S; Cagnoli, G; Crooks, D R M; Lueck, H; Rowan, S; Smith, J R; Strain, K A; Hough, J; Danzmann, K

    2004-01-01

    High Q mirror suspensions are a key element of the advanced interferometric gravitational-wave detectors. In December 2002 the last of the final interferometer optics of GEO 600 were monolithically suspended, using fused silica fibres. The violin modes of the suspension fibres can have Q greater than 10 8 and can therefore interfere with the interferometer length control servo. Hence, the violin modes need to be damped, without degrading the pendulum Q itself. Furthermore, the frequency spread of the fibres used has to be small to allow for high Q notch filtering in the length control servo. The requirements for the violin modes of the two GEO 600 inboard suspensions are Q 6 for the fundamental and Q 6 for the first harmonic mode, respectively. The frequency spread should not exceed 10% within one mode. To accomplish that, two sections of the fibres were coated with amorphous Teflon. By applying the coating, the Q of the relevant modes can be degraded to the desired values and furthermore, the frequencies of these modes can be tuned almost independently with a good accuracy over a wide range. After welding the fibres in the monolithic suspension, a corrective coating was applied to some fibres, to compensate for the frequency spread due to the tension spread of the four fibres within a suspension. We present the method and the results achieved

  4. Damping and tuning of the fibre violin modes in monolithic silica suspensions

    Energy Technology Data Exchange (ETDEWEB)

    Gossler, S [Max-Planck-Institute for Gravitational Physics (Albert-Einstein-Institute) and University of Hannover, Callinstr 38, D-30167 Hannover (Germany); Cagnoli, G [Department of Physics and Astronomy, Institute for Gravitational Research, University of Glasgow, Glasgow G12 8QQ (United Kingdom); Crooks, D R M [Department of Physics and Astronomy, Institute for Gravitational Research, University of Glasgow, Glasgow G12 8QQ (United Kingdom); Lueck, H [Max-Planck-Institute for Gravitational Physics (Albert-Einstein-Institute) and University of Hannover, Callinstr 38, D-30167 Hannover (Germany); Rowan, S [Department of Physics and Astronomy, Institute for Gravitational Research, University of Glasgow, Glasgow G12 8QQ (United Kingdom); Smith, J R [Max-Planck-Institute for Gravitational Physics (Albert-Einstein-Institute) and University of Hannover, Callinstr 38, D-30167 Hannover (Germany); Strain, K A [Department of Physics and Astronomy, Institute for Gravitational Research, University of Glasgow, Glasgow G12 8QQ (United Kingdom); Hough, J [Department of Physics and Astronomy, Institute for Gravitational Research, University of Glasgow, Glasgow G12 8QQ (United Kingdom); Danzmann, K [Max-Planck-Institute for Gravitational Physics (Albert-Einstein-Institute) and University of Hannover, Callinstr 38, D-30167 Hannover (Germany)

    2004-03-07

    High Q mirror suspensions are a key element of the advanced interferometric gravitational-wave detectors. In December 2002 the last of the final interferometer optics of GEO 600 were monolithically suspended, using fused silica fibres. The violin modes of the suspension fibres can have Q greater than 10{sup 8} and can therefore interfere with the interferometer length control servo. Hence, the violin modes need to be damped, without degrading the pendulum Q itself. Furthermore, the frequency spread of the fibres used has to be small to allow for high Q notch filtering in the length control servo. The requirements for the violin modes of the two GEO 600 inboard suspensions are Q < 3 x 10{sup 6} for the fundamental and Q < 2 x 10{sup 6} for the first harmonic mode, respectively. The frequency spread should not exceed 10% within one mode. To accomplish that, two sections of the fibres were coated with amorphous Teflon. By applying the coating, the Q of the relevant modes can be degraded to the desired values and furthermore, the frequencies of these modes can be tuned almost independently with a good accuracy over a wide range. After welding the fibres in the monolithic suspension, a corrective coating was applied to some fibres, to compensate for the frequency spread due to the tension spread of the four fibres within a suspension. We present the method and the results achieved.

  5. Determination of phthalate esters in physiological saline solution by monolithic silica spin column extraction method

    Directory of Open Access Journals (Sweden)

    Lu Lu

    2011-05-01

    Full Text Available Monolithic silica spin column extraction (MonoSpin-SPE was developed as a simple, sensitive, and eco-friendly pretreatment method which combined with ultra-fast liquid chromatography-mass spectrometry (UFLC-MS to determine the levels of six phthalate esters, dimethyl-(DMP, diethyl-(DEP, dipropyl- [DPrP], butyl-benzyl-(BBP, dicyclohexyl(DcHP, and di- n-octyl-(DOP phthalate in physiological saline samples. Under optimized experimental conditions, the method was linear in the following ranges: 0.2- 50 μ/L for DMP, DEP, DPrP, DcHP and DOP; 5 – 100 μ/L for BBP. The correlation coefficients (R2 were in the range of O. 9951 – O. 9995 for all the analytes and the limits of detection (LODs and limits of quantification (LOQs were in the ranges of 0.02 – 0.9 μ/L and 0.08 – 2.7 μ/L, respectively. The pretreatment process showed good reproducibility with inter-day and intra-day relative standard deviations (RSDs below 8.5% and 11.2%, respectively. This method was used to determine the levels of six phthalate esters in physiological saline samples and the recoveries ranged from 71.2% to 107. 3%. DMP and DEP were found in actual physical saline samples (brand A and brand B. Keywords: Monolithic silica spin column, Phthalate esters, Physiological saline samples, Ultra fast liquid chromatographymass spectrometry (UFLC-MS

  6. The effect of high temperature sol-gel polymerization parameters on the microstructure and properties of hydrophobic phenol-formaldehyde/silica hybrid aerogels.

    Science.gov (United States)

    Seraji, Mohamad Mehdi; Sameri, Ghasem; Davarpanah, Jamal; Bahramian, Ahmad Reza

    2017-05-01

    Phenol-formaldehyde/silica hybrid aerogels with different degree of hydrophobicity were successfully synthesized via high temperature sol-gel polymerization. Tetraethoxysilane (TEOS) and methyltriethoxysilane (MTES) were used as precursor and co-precursor of the hydrophobic silica-based phase, respectively. The hydrolysis step of silica based sols were conducted by acid catalyzed reactions and HCl was used as hydrolysis catalyst. The chemical structure of prepared hybrid aerogels was characterized by Fourier Transform Infrared spectroscopy (FT-IR). The effect of MTES/TEOS proportion and catalyst content on the morphology and microstructure of samples were investigated by FE-SEM and C, Si mapping analysis. The acid catalyzed hydrolysis of TEOS and MTES sols leads to formation of a sol with primarily silica particles in the organic-inorganic hybrid sol and varying colloid growth mechanisms were occurred with change in MTES and HCl molar ratio. With the increasing of MTES content, the microstructure of samples changed from uniform colloidal network, core-shell structure to polymeric structure with a huge phase separation. The increasing of HCl mole fraction leads to smaller particle size. Moreover, the shrinkage of samples was decreased and water contact angles of the resulted aerogels were increased from 40 to 156.8° with the increases of MTES content. Copyright © 2017 Elsevier Inc. All rights reserved.

  7. Method for producing metal oxide aerogels having densities less than 0. 02 g/cc

    Science.gov (United States)

    Tillotson, T.M.; Poco, J.F.; Hrubesh, L.W.; Thomas, I.M.

    1994-01-04

    A two-step method is described for making transparent aerogels which have a density of less than 0.003 g/cm[sup 3] to those with a density of more than 0.8 g/cm[sup 3], by a sol/gel process and supercritical extraction. Condensed metal oxide intermediate made with purified reagents can be diluted to produce stable aerogels with a density of less than 0.02 g/cm[sup 3]. High temperature, direct supercritical extraction of the liquid phase of the gel produces hydrophobic aerogels which are stable at atmospheric moisture conditions. Monolithic, homogeneous silica aerogels with a density of less than 0.02 to higher than 0.8 g/cm[sup 3], with high thermal insulation capacity, improved mechanical strength and good optical transparency, are described. 7 figures.

  8. Energy down converting organic fluorophore functionalized mesoporous silica hybrids for monolith-coated light emitting diodes

    Directory of Open Access Journals (Sweden)

    Markus Börgardts

    2017-04-01

    Full Text Available The covalent attachment of organic fluorophores in mesoporous silica matrices for usage as energy down converting phosphors without employing inorganic transition or rare earth metals is reported in this article. Triethoxysilylpropyl-substituted derivatives of the blue emitting perylene, green emitting benzofurazane, and red emitting Nile red were synthesized and applied in the synthesis of mesoporous hybrid materials by postsynthetic grafting to commercially available MCM-41. These individually dye-functionalized hybrid materials are mixed in variable ratios to furnish a powder capable of emitting white light with CIE chromaticity coordinates of x = 0.33, y = 0.33 and an external quantum yield of 4.6% upon irradiation at 410 nm. Furthermore, as a proof of concept two different device setups of commercially available UV light emitting diodes, are coated with silica monoliths containing the three triethoxysilylpropyl-substituted fluorophore derivatives. These coatings are able to convert the emitted UV light into light with correlated color temperatures of very cold white (41100 K, 10700 K as well as a greenish white emission with correlated color temperatures of about 5500 K.

  9. Very large-scale structures in sintered silica aerogels as evidenced by atomic force microscopy and ultra-small angle X-ray scattering experiments

    CERN Document Server

    Marliere, C; Etienne, P; Woignier, T; Dieudonné, P; Phalippou, J

    2001-01-01

    During the last few years the bulk structure of silica aerogels has been extensively studied mainly by scattering techniques (neutrons, X-rays, light). It has been shown that small silica particles aggregate to constitute a fractal network. Its spatial extension and fractal dimension are strongly dependent on the synthesis conditions (e.g., pH of gelifying solutions). These typical lengths range from 1 to 10 nm. Ultra-small angle X-ray scattering (USAXS) and atomic force microscopy (AFM) experiments have been carried out on aerogels at different steps of densification. The results presented in this paper reveal the existence of a spatial arrangement of the solid part at a very large length scale. The evolution of this very large-scale structure during the densification process has been studied and reveals a contraction of this macro-structure made of aggregates of clusters. (16 refs).

  10. Immobilized enzyme reactor chromatography: Optimization of protein retention and enzyme activity in monolithic silica stationary phases

    International Nuclear Information System (INIS)

    Besanger, Travis R.; Hodgson, Richard J.; Green, James R.A.; Brennan, John D.

    2006-01-01

    Our group recently reported on the application of protein-doped monolithic silica columns for immobilized enzyme reactor chromatography, which allowed screening of enzyme inhibitors present in mixtures using mass spectrometry for detection. The enzyme was immobilized by entrapment within a bimodal meso/macroporous silica material prepared by a biocompatible sol-gel processing route. While such columns proved to be useful for applications such as screening of protein-ligand interactions, significant amounts of entrapped proteins leached from the columns owing to the high proportion of macropores within the materials. Herein, we describe a detailed study of factors affecting the morphology of protein-doped bioaffinity columns and demonstrate that specific pH values and concentrations of poly(ethylene glycol) can be used to prepare essentially mesoporous columns that retain over 80% of initially loaded enzyme in an active and accessible form and yet still retain sufficient porosity to allow pressure-driven flow in the low μL/min range. Using the enzyme γ-glutamyl transpeptidase (γ-GT), we further evaluated the catalytic constants of the enzyme entrapped in capillary columns with different silica morphologies as a function of flowrate and backpressure using the enzyme reactor assay mode. It was found that the apparent activity of the enzyme was highest in mesoporous columns that retained high levels of enzyme. In such columns, enzyme activity increased by ∼2-fold with increases in both flowrate (from 250 to 1000 nL/min) and backpressure generated (from 500 to 2100 psi) during the chromatographic activity assay owing to increases in k cat and decreases in K M , switching from diffusion controlled to reaction controlled conditions at ca. 2000 psi. These results suggest that columns with minimal macropore volumes (<5%) are advantageous for the entrapment of soluble proteins for bioaffinity and bioreactor chromatography

  11. Synthesis of Mesoporous Titania-Silica Monolith Composites — A Comprehensive Study on their Photocatalytic Degradation of Acid Blue 113 Dye Under UV Light

    Science.gov (United States)

    Thejaswini, Thurlapathi Vl; Prabhakaran, Deivasigamani

    2016-10-01

    The present work deals with the synthesis of bi-continuous macro and mesoporous crack-free titania-silica monoliths, with well-defined structural dimensions and high surface area. The work also highlights their potential photocatalytic environmental applications. The highly ordered titania-silica monoliths are synthesized through direct surface template method using organic precursors of silica and titania in the presence of surface directing agents such as pluronic P123 and PEG, under acetic acid medium. The monoliths are synthesized with different Ti/Si ratios to obtain monolithic designs that exhibit better photocatalytic activity for dye degradation. The titania-silica monoliths are characterized using XRD, SEM, EDAX, FT-IR, TG-DTA and BET analysis. The photocatalytic activity of the synthesized monoliths is tested on the photodegradation of a textile dye (acid blue 113). It is observed that the monolith with 7:3 ratio of Ti/Si showed significant photocatalysis behavior in the presence of UV light. The influence of various physico-chemical properties such as, solution pH, photocatalyst dosage, light intensity, dye concentration, effect of oxidants, etc. are analyzed and optimized using a customized photoreactor set-up. Under optimized conditions, the monoliths exhibited superior degradation kinetics, with the dye dissipation complete within 10min of photolysis. The mesoporous catalysts are recoverable and reusable up to four cycles of repeated usage.

  12. Random laser emission from a Rhodamine B-doped GPTS/TEOS-derived organic/silica monolithic xerogel

    Science.gov (United States)

    Abegão, Luis M. G.; Manoel, D. S.; Otuka, A. J. G.; Ferreira, P. H. D.; Vollet, D. R.; Donatti, D. A.; De Boni, L.; Mendonça, C. R.; De Vicente, F. S.; Rodrigues, J. J., Jr.; Alencar, M. A. R. C.

    2017-06-01

    A Rhodamine B-doped 3-glycidoxypropyltrimethoxysilane (GPTS)/tetraethyl orthosilicate (TEOS)-derived organic/silica monolithic xerogel with excellent optical properties was prepared and its potential as a random laser host investigated. This hybrid material has a non-porous organic/inorganic morphology with silica-rich nanoparticles of less than 10 nm in diameter homogeneously dispersed within the matrix. Random laser emission with incoherent feedback, centered at 618 nm, was observed from Rhodamine B incorporated into the monolithic xerogel when excited by a 532 nm pulsed laser. This hybrid system is shown to be very promising for the development of a new class of random laser-based integrated devices, with applications ranging from optical bio-imaging to sensing.

  13. SAXS and BET studies of aging and densification of silica aerogels

    OpenAIRE

    Lours, Thierry; Zarzycki, Jerzy; Craievich, Aldo F.; Dos Santos, Dayse Iara; Aegerter, Michel A.

    1987-01-01

    Aerogels prepared by hypercritical drying of gels obtained by hydrolysis of TMOS/methanol 50% solution in acid and basic conditions were studied combining SAXS and BET methods. Diffraction results do not seem to reveal a fractal character as the POROD's limit I(q) q4 → Cte was obtained in all cases without well characterised portions in log I(q) vs log q graphs. Aging produces a small increase in the density of the matrix. Densification studies indicate that for moderate temperatures 53...

  14. Properties of aerogels in glazings

    DEFF Research Database (Denmark)

    Schultz, Jørgen Munthe

    1998-01-01

    This report describes the final tests carried out on an advanced apparatus for measurement of thermal conductivity of materials at atmospheric pressure and different levels of evacuation. The apparatus was designed and constructed in the phase 1 of the project. Difficulties with the control system...... have been solved and measurements have been carried out on common polystyrene foam insulation at atmospheric pressure. The measurements have been compared with results from reference measurements and a difference of only 0.3% was found in measured thermal conductivity. Measurements on monolithic silica...... aerogel were performed at 5 different pressure levels in the range 0.2 - 1000 hPa. The measured equivalent thermal conductivity is in the range 8.9 - 16.4 mW/(m K) which corresponds very well with results obtained by institutes in Germany and France....

  15. Separation of nucleobases, nucleosides, and nucleotides using two zwitterionic silica-based monolithic capillary columns coupled with tandem mass spectrometry

    Czech Academy of Sciences Publication Activity Database

    Moravcová, Dana; Haapala, M.; Planeta, Josef; Hyötyläinen, T.; Kostiainen, R.; Wiedmer, S. K.

    2014-01-01

    Roč. 1373, Dec (2014), s. 90-96 ISSN 0021-9673 R&D Projects: GA MV VG20112015021; GA ČR(CZ) GAP106/12/0522 Institutional support: RVO:68081715 Keywords : HILIC separation * ESI–MS * Monolithic silica column Subject RIV: CB - Analytical Chemistry , Separation Impact factor: 4.169, year: 2014 http://hdl.handle.net/11104/0242051

  16. PREPARATION OF MESOPOROUS TITANIA-SILICA AEROGELS BY CO2 SUPERCRITICAL EXTRACTION

    Directory of Open Access Journals (Sweden)

    Silvester Tursiloadi

    2010-06-01

    Full Text Available Stable anatase is attractive because of its notable functions for photocatalysis and photon-electron transfer.  TiO2-nanoparticles dispersed SiO2 wet gels were prepared by hydrolysis of Ti(OC4H9n4 and Si(OC2H54 in a 2-propanol solution with acid catalyst.  The solvent in the wet gels was supercritically extracted using CO2 at 60 oC and 22 Mpa in one-step.  Thermal evolution of the microstructure of the extracted gels (aerogels was evaluated by XRD measurements, TEM and N2 adsorption measurements. The as-extracted aerogel with a large specific surface area, more than 365 m2g-1, contained anatase nanoparticles, about 5 nm in diameter.  The anatase phase was stable after calcinations at temperatures up to 1000 oC, and BET specific surface area, total pore volume and average pore diameter did not change significantly after calcinations at temperature up to 800 oC.   Keywords: Stable anatase, sol-gel, CO2 supercritical extraction.

  17. Aerogels in Aerospace: An Overview

    Directory of Open Access Journals (Sweden)

    Nadiir Bheekhun

    2013-01-01

    Full Text Available Aerogels are highly porous structures prepared via a sol-gel process and supercritical drying technology. Among the classes of aerogels, silica aerogel exhibits the most remarkable physical properties, possessing lower density, thermal conductivity, refractive index, and dielectric constant than any solids. Its acoustical property is such that it can absorb the sound waves reducing speed to 100 m/s compared to 332 m/s for air. However, when it comes to commercialization, the result is not as expected. It seems that mass production, particularly in the aerospace industry, has dawdled behind. This paper highlights the evolution of aerogels in general and discusses the functions and significances of silica aerogel in previous astronautical applications. Future outer-space applications have been proposed as per the current research trend. Finally, the implementation of conventional silica aerogel in aeronautics is argued with an alternative known as Maerogel.

  18. Effect of Granule Sizes on Acoustic Properties of Protein-Based Silica Aerogel Composites via Novel Inferential Transmission Loss Method

    Directory of Open Access Journals (Sweden)

    Mahesh Sachithanadam

    2016-03-01

    Full Text Available The acoustic properties of the silica aerogel (SA granules of various sizes from 0.50 to 3.35 mm, distributed into six groups of nominal sizes and measured via a two-microphone impedance tube, are presented. The absorption coefficients of the SA granules were evaluated at ultra- to super-low frequency range from 50–1600 Hz. It was observed that nominal SA granules with sizes of 1.2 mm (AG2 and 1.7 mm (AG3 displayed the best absorption coefficients. When tested with granules filled at 5 cm depth, AG2 and AG3 absorption coefficients peaked at 980 Hz with values of 0.86 and 0.81, respectively. A novel approach to measure transmission loss (TL by using “inferential” principle is presented. This novel method, named “Inferential Transmission Loss Method” (InTLM, revealed that the average TL, TLavg for both AG2 and AG3 SA granules was 14.83 dB and 15.35 dB, respectively. Gelatin silica aerogels doped with sodium dodecyl sulfate (GSA–SDS composites comprising of 1.2 mm (GSA–AG2 and 1.7 mm (GSA–AG3 granules of various configurations were fabricated and evaluated for absorption coefficients and TL with known traditional acoustic panels. The results showed that GSA–AG3 had a better absorption coefficient over other configurations for the same corresponding thickness reaching the peak of 0.6 from 1300 to 1450 Hz with TLavg between 10.7 and 20.3 decibels. The four-layered GSA–AG2 and GSA–AG3 composites showed exceptionally high absorption from 500 to 800 Hz suitable for narrow band applications. Lastly, the “InTLM” was matched with the sound meter measurements, with high accuracy between 0.3 and 3.2 dB for low-frequency testing (50–1600 Hz.

  19. Preparation of organic-silica hybrid boronate affinity monolithic column for the specific capture and separation of cis-diol containing compounds.

    Science.gov (United States)

    Li, Qianjin; Lü, Chenchen; Li, Hengye; Liu, Yunchun; Wang, Heye; Wang, Xin; Liu, Zhen

    2012-09-21

    A new boronate-silica hybrid monolithic column was prepared using a one-pot approach with 3-acrylamidophenylboronic acid (AAPBA) as the boronate affinity ligand. The AAPBA-silica monolith exhibited several attractive advantages. First, it is highly hydrophilic, providing excellent specificity and avoiding the presence of organic solvent in the mobile phase. Second, due to its large surface area, it exhibited a high binding capacity, 49.5 μmol/mL, the highest among the boronate affinity monolithic columns appeared in the literature. Third, the monolith can bind with cis-diol containing compounds at pH as low as 6.5, which not only avoids the use of basic pH conditions at which the silica monolith may hydrolysis but also facilitates the applications to wider sample range. Finally, the hybrid monolithic column exhibited apparent secondary separation capability, which allows for two-dimensional (2D) separation of cis-diol compounds in a single column. Due to these merits, the AAPBA-silica hybrid monolithic column can be a promising separation medium for the analysis of cis-diol containing compounds. Copyright © 2012 Elsevier B.V. All rights reserved.

  20. Optical study of the ultrasonic formation process of noble metal nanoparticles dispersed inside the pores of monolithic mesoporous silica

    CERN Document Server

    Fu Gan Hua; Kan Cai Xia; Li Cun Cheng; Fang Qi

    2003-01-01

    Gold nanoparticles dispersed inside the pores of monolithic mesoporous silica were prepared by soaking the silica in a gold (III) ion solution and subsequent ultrasound irradiation. The formation process of gold nanoparticles in the pores of mesoporous silica was investigated based on optical measurements of wrapped and naked soaked silica after ultrasonic irradiation, and the reduction rate effect in solution and pre-soaking effect. It has been shown that acoustic cavitation cannot occur in nano-sized pores. The gold nanoparticles in silica are not formed in situ within the pores but produced mainly by diffusion of the gold clusters formed in the solution during irradiation into the pores. The radicals formed in solution are exhausted before entering the pores of silica. There exists a critical reduction rate in solution, at which the yield of gold nanoparticles in silica reaches a maximum, and above which there is a decrease in the yield. This is attributed to too quick a growth or aggregation of gold clust...

  1. Rapid determination of amino acids in biological samples using a monolithic silica column.

    Science.gov (United States)

    Song, Yanting; Funatsu, Takashi; Tsunoda, Makoto

    2012-05-01

    A high-performance liquid chromatography method in which fluorescence detection is used for the simultaneous determination of 21 amino acids is proposed. Amino acids were derivatized with 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F) and then separated on a monolithic silica column (MonoClad C18-HS, 150 mm×3 mm i.d.). A mixture of 25 mM citrate buffer containing 25 mM sodium perchlorate (pH 5.5) and acetonitrile was used as the mobile phase. We found that the most significant factor in the separation was temperature, and a linear temperature gradient from 30 to 49°C was used to control the column temperature. The limits of detection and quantification for all amino acids ranged from 3.2 to 57.2 fmol and 10.8 to 191 fmol, respectively. The calibration curves for the NBD-amino acid had good linearity within the range of 40 fmol to 40 pmol when 6-aminocaproic acid was used as an internal standard. Using only conventional instruments, the 21 amino acids could be analyzed within 10 min. This method was found to be suitable for the quantification of the contents of amino acids in mouse plasma and adrenal gland samples.

  2. Behavior of short silica monolithic columns in high pressure gas chromatography.

    Science.gov (United States)

    Maniquet, Adrien; Bruyer, Nicolas; Raffin, Guy; Baco-Antoniali, Franck; Demesmay, Claire; Dugas, Vincent; Randon, Jérôme

    2016-08-19

    In order to analyze light hydrocarbons mixtures with silica monolithic columns, a conventional gas chromatograph was modified to work with carrier gas pressure as high as 60bar. To understand hydrodynamic flow and retention with short columns (less than 30cm), special attention was required due to the temperature difference between the oven area and the FID detector which contain a significant length of the column. Efficiency and selectivity using various carrier gases (helium, nitrogen and carbon dioxide) at different inlet pressure for different oven temperature were studied. Carrier gas nature was a very significant parameter: on one side, linked to adsorption mechanism for gases like nitrogen and carbon dioxide onto the stationary phase modifying retention and selectivity, on the other side in relation to the minimum theoretical plate height which was as low as 15μm (66 000 platem(-1)) using carbon dioxide as carrier gas. The chromatographic system was then used to separate methane, ethane, ethylene, acetylene, propane, cyclopropane, and butane in less than 30s. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. Mechanical performance and thermal stability of glass fiber reinforced silica aerogel composites based on co-precursor method by freeze drying

    Science.gov (United States)

    Zhou, Ting; Cheng, Xudong; Pan, Yuelei; Li, Congcong; Gong, Lunlun; Zhang, Heping

    2018-04-01

    In order to maintain the integrity, glass fiber (GF) reinforced silica aerogel composites were synthesized using methltrimethoxysilane (MTMS) and water glass co-precursor by freeze drying method. The composites were characterized by scanning electron microscopy, Brunauer-Emmett-Teller analysis, uniaxial compressive test, three-point bending test, thermal conductivity analysis, contact angle test, TG-DSC analysis. It was found that the molar ratio of MTMS/water glass could significantly affect the properties of composites. The bulk density and thermal conductivity first decreased and then increased with the increasing molar ratio. The composites showed remarkable mechanical strength and flexibility compared with pure silica aerogel. Moreover, when the molar ratio is 1.8, the composites showed high specific surface area (870.9 m2/g), high contact angle (150°), great thermal stability (560 °C) and low thermal conductivity (0.0248 W/m·K). These outstanding properties indicate that GF/aerogels have broad prospects in the field of thermal insulation.

  4. Development of a silica monolith microbioreactor entrapping highly activated lipase and an experiment toward integration with chromatographic separation of chiral esters.

    Science.gov (United States)

    Kawakami, Koei; Abe, Daisuke; Urakawa, Taiki; Kawashima, Ayako; Oda, Yasuhiro; Takahashi, Ryo; Sakai, Shinji

    2007-11-01

    Microbioreactors are effective for high-throughput production of expensive products from small amounts of substrates. Lipases are versatile enzymes for chiral syntheses, and are highly activated when immobilized in alkyl-substituted silicates by the sol-gel method. For practical application of sol-gel immobilized lipases to a flow system, a microbioreactor loaded with a macroporous silica monolith is well suited, because it can be easily integrated with a chromatographic separator for optical resolution. We attempted to develop a microbioreactor containing a silica monolith-immobilized lipase. A nonshrinkable silica monolith was first formed from a 4:1 mixture of methyltrimethoxysilane (MTMS) and tetramethoxysilane (TMOS). It was then coated with silica precipitates entrapping lipase, derived from a 4:1 mixture of n-butyltrimethoxysilane (BTMS) and TMOS. As a result, monolith treated with the BTMS-based silicate entrapping lipase exhibited approximately ten times higher activity than nontreated monolith-immobilized lipase derived from the MTMS-based silicate, in transesterification between glycidol and vinyl n-butyrate in isooctane. A commercially available chiral column was connected in series to the monolith microbioreactor, and a pulse of substrate solution was supplied at the inlet of the reactor. Successful resolution of the racemic ester produced was achieved in the chromatographic column.

  5. Chip electrochromatographic systems: Novel vertically aligned carbon nanotube and silica monoliths based separations

    Science.gov (United States)

    Goswami, Shubhodeep

    2009-12-01

    Miniaturized chemical analysis systems, also know as 'lab-on-a-chip' devices have been rapidly developing over the last decade. Capillary electrochromatography (CEC), a multidimensional separation technique combining capillary electrophoresis (CE) and liquid chromatography (LC) has been of great interest for chip based applications. Preliminary work has been undertaken to develop vertically aligned carbon nanotubes and photopolymerizable silica solgel as novel stationary phase materials for 'chip CEC' separations. Patterned growth of CNTs in a specific location of the channel has been carried out using a solid phase Fe-Al catalyst as well as a vapor deposited ferrocene catalyst. Characterization of the CNT "forests" was achieved using optical microscopy, secondary electron microscopy, high resolution tunneling electron microscopy and Raman spectroscopy. Proof-of-concept applications were demonstrated using reversed phase CEC separations as well as solid phase extraction of a glycosylated protein using concanavilin A immobilized onto the CNT bed. Photopolymerizable silica solgel materials were developed as stationary phase for microfluidic electrochromatographic separations in disposable polydimethylsiloxane (PDMS) chip devices. Effect on morphology and pore size of gels were studied as function of UV and solgel polymerization conditions, porogen, salt additives, geometry and hydrolyzable methoxy-ies. Structural morphologies were studied with Secondary Electron Microscopy (SEM). Pore size and pore volumes were characterized by thermal porometry, nitrogen BET adsorptions and differential scanning calorimetry. Computational fluid dynamics and confocal microscopy tools were employed to study the transport of fluids and model analytes. These investigations were directed towards evolving improved strategies for rinsing of uncrosslinked monomers to form porous monoliths as well as to effect a desired separation under a set of electrochromatograhic conditions

  6. Development of a simple technique for the coating of monolithic silica with pristine boron nitride nanotubes (BNNTs): HPLC chromatographic applications.

    Science.gov (United States)

    Guillaume, Yves Claude; André, Claire

    2017-03-01

    In this paper, a novel and very simple homogeneous coating of a monolithic silica HPLC support using pristine boron nitride nanotubes (BNNTs) was d0.escribed. The chromatographic support was coated with BNNTs in a non covalent way to preserve the nanotube structure. A solution of BNNTs dispersed in dimethylacetamide (DMAc) was pumped through the column at a flow-rate of 0.3mL/min for 24h at room temperature. Strong interaction between amino groups and the BNNT surfaces induces the adsorption of the BNNTs on the silica, while the stable solvation in DMAc hampers further adsorption of the tubes. The excellent stability of the non covalent BNNT-coating on the monolithic silica in view of application for HPLC was also demonstrated. It was shown that this novel stationary phase was efficient for the HPLC isocratic or gradient mode separation of molecules of different structure such as phenol derivatives, alkylbenzene or doping agents (steroids). As well, this simple technique of BNNT immobilization offers new perspectives for the BNNT-coating on the surfaces of a wide range of solid substrates. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Synthesis of New Flexible Aerogels from MTMS/DMDMS via Ambient Pressure Drying

    Energy Technology Data Exchange (ETDEWEB)

    Hayase, G; Kanamori, K; Kazuki, K; Hanada, T, E-mail: kanamori@kuchem.kyoto-u.ac.jp [Department of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa, Sakyo-ku, Kyoto, 606-8502 (Japan)

    2011-10-29

    Although silica aerogel is expected to be the material for energy savings, the lack of the strength prevents from commercial applications such as to low-density thermal insulators and acoustic absorbents. To improve mechanical properties, methyltrimethoxysilane (MTMS) and dimethyldimethoxysilane (DMDMS) are used as the co-precursor of aerogels in this study because the network becomes flexible due to the relatively low cross-linking density and to the unreacted methyl groups. Because of the strong hydrophobicity of MTMS/DMDMS-derived condensates, phase separation occurs, which must be suppressed in aqueous sol to obtain uniform and monolithic gel networks. We also employed surfactant n-hexadecyltrimethylammonium chloride (CTAC) in starting compositions to control phase separation during a 2-step acid/base sol-gel reaction. By changing the starting composition, various microstructures of pores are obtained. In the uniaxial compression test, the aerogel showed high flexibility and spring-back to the original shape after removing the stress.

  8. ZnFe2O4 nanoparticles dispersed in a highly porous silica aerogel matrix: a magnetic study.

    Science.gov (United States)

    Bullita, S; Casu, A; Casula, M F; Concas, G; Congiu, F; Corrias, A; Falqui, A; Loche, D; Marras, C

    2014-03-14

    We report the detailed structural characterization and magnetic investigation of nanocrystalline zinc ferrite nanoparticles supported on a silica aerogel porous matrix which differ in size (in the range 4-11 nm) and the inversion degree (from 0.4 to 0.2) as compared to bulk zinc ferrite which has a normal spinel structure. The samples were investigated by zero-field-cooling-field-cooling, thermo-remnant DC magnetization measurements, AC magnetization investigation and Mössbauer spectroscopy. The nanocomposites are superparamagnetic at room temperature; the temperature of the superparamagnetic transition in the samples decreases with the particle size and therefore it is mainly determined by the inversion degree rather than by the particle size, which would give an opposite effect on the blocking temperature. The contribution of particle interaction to the magnetic behavior of the nanocomposites decreases significantly in the sample with the largest particle size. The values of the anisotropy constant give evidence that the anisotropy constant decreases upon increasing the particle size of the samples. All these results clearly indicate that, even when dispersed with low concentration in a non-magnetic and highly porous and insulating matrix, the zinc ferrite nanoparticles show a magnetic behavior similar to that displayed when they are unsupported or dispersed in a similar but denser matrix, and with higher loading. The effective anisotropy measured for our samples appears to be systematically higher than that measured for supported zinc ferrite nanoparticles of similar size, indicating that this effect probably occurs as a consequence of the high inversion degree.

  9. Enhanced electrochemical capacitance and oil-absorbability of N-doped graphene aerogel by using amino-functionalized silica as template and doping agent

    Science.gov (United States)

    Du, Yongxu; Liu, Libin; Xiang, Yu; Zhang, Qiang

    2018-03-01

    The development of novel energy storage devices with high power density and energy density is highly desired. However, as a promising material, the strong π-π interaction of graphene inhibits its applications. Herein, we provide a new approach that amino-functionalized silica are used as both templates to prevent the restacking of the graphene sheets and doping agents simultaneously. The microstructures, porous properties and chemical composition of the resulted N-doped reduced graphene oxide (RGO) aerogels, characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Raman, X-ray photoelectron spectroscopy and Brunauer-Emmett-Teller measurement, indicate that the amount of SiO2-NH2 has profound effects on the surface area and carbon activity of the graphene sheets. Benefiting from the large specific surface area of 481.8 m2 g-1, low series resistances and high nitrogen doping content (4.4 atom%), the as-fabricated 3D hierarchical porous N-doped RGO aerogel electrode exhibits outstanding electrochemical performance in aqueous and organic electrolyte, such as ultrahigh specific capacitances of 350 F g-1 at a current density of 1 A g-1 and excellent reversibility with a cycling efficiency of 88% after 10000 cycles. In addition, the N-doped RGO aerogels possess high oil-absorbability with long recyclability.

  10. Application of a Fast Separation Method for Anti-diabetics in Pharmaceuticals Using Monolithic Column: Comparative Study With Silica Based C-18 Particle Packed Column.

    Science.gov (United States)

    Hemdan, A; Abdel-Aziz, Omar

    2018-04-01

    Run time is a predominant factor in HPLC for quality control laboratories especially if there is large number of samples have to be analyzed. Working at high flow rates cannot be attained with silica based particle packed column due to elevated backpressure issues. The use of monolithic column as an alternative to traditional C-18 column was tested for fast separation of pharmaceuticals, where the results were very competitive. The performance comparison of both columns was tested for separation of anti-diabetic combination containing Metformin, Pioglitazone and Glimepiride using Gliclazide as an internal standard. Working at high flow rates with less significant backpressure was obtained with the monolithic column where the run time was reduced from 6 min in traditional column to only 1 min in monolithic column with accepted resolution. The structure of the monolith contains many pores which can adapt the high flow rate of the mobile phase. Moreover, peak symmetry and equilibration time were more efficient with monolithic column.

  11. Development of windows based on highly insulating aerogel glazings

    DEFF Research Database (Denmark)

    Jensen, Karsten Ingerslev; Schultz, Jørgen Munthe; Kristiansen, Finn Harken

    2004-01-01

    Within a finished and a current EU project, research and development of monolithic silica aerogel as transparent insulation in windows are being carried out. On behalf of the partners of the two projects, results related to the window application will be presented here. At the thermal envelope...... of buildings, the window area is the weakest part with respect to the heat loss, but at the same time, it also provides e.g. solar energy gain. Glazing prototypes have been made of aerogel tiles of about 55 cm sq. (elaborated within the projects). Those tiles are quickly evacuated and easily sealed between two...... of approx. 15 mm, a centre heat loss coefficient of below 0.7 W/m² K and a solar transmittance of 76% have been obtained. The research is funded in part by the European Commission within the frameworks of the Non-Nuclear Energy Programme – JOULE III and the Energy, Environment and Sustainable Development...

  12. Effect of Aerogel Particle Concentration on Mechanical Behavior of Impregnated RTV 655 Compound Material for Aerospace Applications

    Directory of Open Access Journals (Sweden)

    Firouzeh Sabri

    2014-01-01

    Full Text Available Aerogels are a unique class of materials with superior thermal and mechanical properties particularly suitable for insulating and cryogenic storage applications. It is possible to overcome geometrical restrictions imposed by the rigidity of monolithic polyurea cross-linked silica aerogels by encapsulating micrometer-sized particles in a chemically resistant thermally insulating elastomeric “sleeve.” The ultimate limiting factor for the compound material’s performance is the effect of aerogel particles on the mechanical behavior of the compound material which needs to be fully characterized. The effect of size and concentration of aerogel microparticles on the tensile behavior of aerogel impregnated RTV655 samples was explored both at room temperature and at 77 K. Aerogel microparticles were created using a step-pulse pulverizing technique resulting in particle diameters between 425 μm and 90 μm and subsequently embedded in an RTV 655 elastomeric matrix. Aerogel particle concentrations of 25, 50, and 75 wt% were subjected to tensile tests and behavior of the compound material was investigated. Room temperature and cryogenic temperature studies revealed a compound material with rupture load values dependent on (1 microparticle size and (2 microparticle concentration. Results presented show how the stress elongation behavior depends on each parameter.

  13. Highly Insulating and Light Transmitting Aerogel Glazing for Super Insulating Windows (HILIT+)

    DEFF Research Database (Denmark)

    Jensen, Karsten Ingerslev; Kristiansen, Finn Harken; Schultz, Jørgen Munthe

    2005-01-01

    -free nano-structured aerogel materials through a reasonably fast and reproducible process. The applicative part of this project aimed at elaborating, studying and optimising “state-of-the-art” (0.5 W/m2 K) aerogel glazings for windows. An important issue was the risk of outside condensation and rime and its...... avoidance. The final aerogel window is optimised with regard to its production and performance in view of the technical, economical and life cycle aspects. The aerogel production process has been optimised and tuned so monolithic silica aerogel sheets are produced with more than 85% crack free sheets per...... insulation purposes. The edge seal solution shows only a very limited thermal bridge effect. The final glazing has a total solar energy transmittance above 85% and a U-value of 0.7 W/m2 K for about 14 mm aerogel thickness, which for a 20 mm thickness corresponds to a U-value of approximately 0.5 W/m2K...

  14. Highly luminescent and ultrastable CsPbBr{sub 3} perovskite quantum dots incorporated into a silica/alumina monolith

    Energy Technology Data Exchange (ETDEWEB)

    Li, Zhichun; Kong, Long; Huang, Shouqiang; Li, Liang [School of Environmental Science and Engineering, Shanghai Jiao Tong University (China)

    2017-07-03

    We successfully prepared QDs incorporated into a silica/alumina monolith (QDs-SAM) by a simple sol-gel reaction of an Al-Si single precursor with CsPbBr{sub 3} QDs blended in toluene solution, without adding water and catalyst. The resultant transparent monolith exhibits high photoluminescence quantum yields (PLQY) up to 90 %, and good photostability under strong illumination of blue light for 300 h. We show that the preliminary ligand exchange of didodecyl dimethyl ammonium bromide (DDAB) was very important to protect CsPbBr{sub 3} QDs from surface damages during the sol-gel reaction, which not only allowed us to maintain the original optical properties of CsPbBr{sub 3} QDs but also prevented the aggregation of QDs and made the monolith transparent. The CsPbBr{sub 3} QDs-SAM in powder form was easily mixed into the resins and applied as color-converting layer with curing on blue light-emitting diodes (LED). The material showed a high luminous efficacy of 80 lm W{sup -1} and a narrow emission with a full width at half maximum (FWHM) of 25 nm. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. Highly Luminescent and Ultrastable CsPbBr3 Perovskite Quantum Dots Incorporated into a Silica/Alumina Monolith.

    Science.gov (United States)

    Li, Zhichun; Kong, Long; Huang, Shouqiang; Li, Liang

    2017-07-03

    We successfully prepared QDs incorporated into a silica/alumina monolith (QDs-SAM) by a simple sol-gel reaction of an Al-Si single precursor with CsPbBr 3 QDs blended in toluene solution, without adding water and catalyst. The resultant transparent monolith exhibits high photoluminescence quantum yields (PLQY) up to 90 %, and good photostability under strong illumination of blue light for 300 h. We show that the preliminary ligand exchange of didodecyl dimethyl ammonium bromide (DDAB) was very important to protect CsPbBr 3 QDs from surface damages during the sol-gel reaction, which not only allowed us to maintain the original optical properties of CsPbBr 3 QDs but also prevented the aggregation of QDs and made the monolith transparent. The CsPbBr 3 QDs-SAM in powder form was easily mixed into the resins and applied as color-converting layer with curing on blue light-emitting diodes (LED). The material showed a high luminous efficacy of 80 lm W -1 and a narrow emission with a full width at half maximum (FWHM) of 25 nm. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Thermal conductivity studies of a polyurea cross-linked silica aerogel-RTV 655 compound for cryogenic propellant tank applications in space

    Science.gov (United States)

    Sabri, F.; Marchetta, J.; Smith, K. M.

    2013-10-01

    Silica-based aerogel is an ideal thermal insulator with a makeup of up to 99% air associated with the highly porous nature of this material. Polyurea cross-linked silica aerogel (PCSA) has superior mechanical properties compared to the native aerogels yet retains the highly porous open pore network and functions as an ideal thermal insulator with added load-bearing capability necessary for some applications. Room temperature vulcanizing rubber-RTV 655—is a space qualified elastomeric thermal insulator and encapsulant with high radiation and temperature tolerance as well as chemical resistance. Storage and transport of cryogenic propellant liquids is an integral part of the success of future space exploratory missions and is an area under constant development. Limitations and shortcomings of current cryogenic tank materials and insulation techniques such as non-uniform insulation layers, self-pressurization, weight and durability issues of the materials used, has motivated the quest for alternative materials. Both RTV 655 and PCSA are promising space qualified materials with unique and tunable microscopic and macroscopic properties making them attractive candidates for this study. In this work, the effect of PCSA geometry and volume concentration on the thermal behavior of RTV 655—PCSA compound material has been investigated at room temperature and at a cryogenic temperature. Macroscopic and microscopic PCSA material was encapsulated at increasing concentrations in an RTV 655 elastomeric matrix. The effect of pulverization on the nanopores of PCSA as a method for creating large quantities of homogeneous PCSA microparticles has also been investigated and is reported. The PCSA volume concentrations ranged between 22% and 75% for both geometries. Thermal conductivity measurements were performed based on the steady state transient plane source method.

  17. Histidine-modified organic-silica hybrid monolithic column for mixed-mode per aqueous and ion-exchange capillary electrochromatography.

    Science.gov (United States)

    Tang, Sheng; Liu, Shujuan; Liang, Xiaojing; Tang, Xiaofen; Wu, Xingcai; Guo, Yong; Liu, Xia; Jiang, Shengxiang

    2015-06-01

    A novel organic-silica hybrid monolith was prepared through the binding of histidine onto the surface of monolithic matrix for mixed-mode per aqueous and ion-exchange capillary electrochromatography. The imidazolium and amino groups on the surface of the monolithic stationary phase were used to generate an anodic electro-osmotic flow as well as to provide electrostatic interaction sites for the charged compounds at low pH. Typical per aqueous chromatographic behavior was observed in water-rich mobile phases. Various polar and hydrophilic analytes were selected to evaluate the characteristics and chromatographic performance of the obtained monolith. Under per aqueous conditions, the mixed-mode mechanism of hydrophobic and ion-exchange interactions was observed and the resultant monolithic column proved to be very versatile for the efficient separations of these polar and hydrophilic compounds (including amides, nucleosides and nucleotide bases, benzoic acid derivatives, and amino acids) in highly aqueous mobile phases. The successful applications suggested that the histidine-modified organic-silica hybrid monolithic column could offer a wide range of retention behaviors and flexible selectivities toward polar and hydrophilic compounds. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Mesoporous fluorocarbon-modified silica aerogel membranes enabling long-term continuous CO2 capture with large absorption flux enhancements.

    Science.gov (United States)

    Lin, Yi-Feng; Chen, Chien-Hua; Tung, Kuo-Lun; Wei, Te-Yu; Lu, Shih-Yuan; Chang, Kai-Shiun

    2013-03-01

    The use of a membrane contactor combined with a hydrophobic porous membrane and an amine absorbent has attracted considerable attention for the capture of CO2 because of its extensive use, low operational costs, and low energy consumption. The hydrophobic porous membrane interface prevents the passage of the amine absorbent but allows the penetration of CO2 molecules that are captured by the amine absorbent. Herein, highly porous SiO2 aerogels modified with hydrophobic fluorocarbon functional groups (CF3 ) were successfully coated onto a macroporous Al2 O3 membrane; their performance in a membrane contactor for CO2 absorption is discussed. The SiO2 aerogel membrane modified with CF3 functional groups exhibits the highest CO2 absorption flux and can be continuously operated for CO2 absorption for extended periods of time. This study suggests that a SiO2 aerogel membrane modified with CF3 functional groups could potentially be used in a membrane contactor for CO2 absorption. Also, the resulting hydrophobic SiO2 aerogel membrane contactor is a promising technology for large-scale CO2 absorption during the post-combustion process in power plants. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Comparison of commercial organic polymer-based and silica-based monolithic columns using mixtures of analytes differing in size and chemistry.

    Science.gov (United States)

    Vyviurska, Olga; Lv, Yongqin; Mann, Benjamin F; Svec, Frantisek

    2018-01-02

    Commercially available silica-based monolithic columns Chromolith RP-8e, Chromolith RP-18, and Chromolith HR RP-18, and polymer-based monolithic columns ProSwift RP-1S, ProSwift RP-2H, and ProSwift RP-3U varying in pore size and bonded phase have been tested for the fast separation of selected sets of analytes. These mixtures of analytes included small molecules (uracil, caffeine, 1-phenylethanol, butyl paraben, and anthracene), acylated insulins, and intact proteins (ribonuclease A, cytochrome C, transferrin, apomyoglobin, and thyroglobulin), and covered wide range of chemistries and sizes. Small molecules were well separated with a height equivalent to theoretical plate of 11-26 μm using silica-based monolithic columns, while organic polymer-based monoliths excelled in the fast sub 1 min baseline separations of large molecules. A peak capacity of 37 was found for separation of acylated insulins on Chromolith columns using a 3 min gradient at a flow rate of 3 ml/min. Poor recovery of proteins from Chromolith columns and significant peak tailing of small molecules using ProSwift columns were the major obstacles in using monolithic columns in those applications. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. B1 Aerogels

    DEFF Research Database (Denmark)

    Duer, Karsten; Svendsen, Sv Aa Højgaard

    1996-01-01

    , engineering and architectural basis which will support the appropriate use of aerogels in windows, solar collectors and passive solar applications, with the aim of saving or producing thermal energy for use in buildings".This objective is in very good agreement with the general scope of task 18 but where Task...... of aerogel as a material for window applications3. Construction of an aerogel DGU and measurement of key performance parameters. The goal for the aerogel DGU was to reach a Total Solar Energy Transmittance above 0.75 and a U-value below 0.5 W/m²K. These are values that can not be simultaneously reached......The report summarizes the work that has been carried out within the project "B1 AEROGELS" as a part of the IEA SH&CP Task 18 "Advanced Glazing and Associated Materials For Solar And Building Applications".By providing at the same time thermal insulation and transparency the silica aerogel is a very...

  1. Comments on "hydrodynamic and dispersion behavior in a non-porous silica monolith through fluid dynamic study of a computational mimic reconstructed from sub-micro-tomographic scans".

    Science.gov (United States)

    Hlushkou, Dzmitry; Höltzel, Alexandra; Tallarek, Ulrich

    2013-08-09

    We comment on a recently published paper by Loh and Vasudevan [J. Chromatogr. A 1274 (2013) 65], which reported the physical reconstruction of the bulk macropore space of an analytical silica monolith by X-ray computed microtomography and the subsequent computational fluid dynamics simulations of flow and mass transport in the reconstructed monolith model. Loh and Vasudevan claim that their combined reconstruction and simulation approach offers a significant reduction of computational expenses without significant loss in accuracy in characterizing the macropore space heterogeneity of the monolith and predicting its transport properties. We challenge their claim and question the validity and validation of their results by discussing the employed scanning resolution, the characterization of macropore space heterogeneities, the interpretation of the simulated dispersion data, as well as the comparison of computational expenses with previous work. Copyright © 2013 Elsevier B.V. All rights reserved.

  2. Sorption and diffusion of phenols onto well-defined ordered nanoporous monolithic silicas.

    Science.gov (United States)

    El-Safty, S A

    2003-04-01

    The sorption of phenol, and o-, m-, and p-aminophenol (o-, m-, and p-AP) onto highly ordered mesoporous silicas (HOM) with cubic Im3m (HOM-1), hexagonal H(I) (HOM-2), 3-D hexagonal p6(3)/mmc (HOM-3), cubic Ia3d (HOM-5), lamellar L( infinity ) (HOM-6), and solid phase S (HOM-8) materials has been investigated kinetically. Nanostructured silica molecular sieves have been prepared at 25 and 60 degrees C with lyotropic liquid-crystalline phases of the nonionic surfactant (Brij 76) that was used as a structure-directing agent. Such nanostructured silicas have been studied by 29Si nuclear magnetic resonance (29Si NMR), powder X-ray diffraction (XRD), the Brunauer-Emmett-Teller (BET) method for nitrogen adsorption and surface area measurements, and transmission electron microscopy (TEM) techniques after synthesis and sorption. It was found that all materials exhibit well-defined long-range porous architectures without significant loss of the ordered texture during phenol sorption. The kinetics of phenol sorption has been studied spectrophotometrically at different temperatures (25-40 degrees C; +/-0.1 range). The sorption rate is zero order in all phenols sorbed, and increases directly in the pattern P >m-AP > o-AP > p-AP, which reflects the mobility of the phenol compounds on the particle pores. The isothermal sorption and the kinetic parameters were discussed and it was established that a diffusion-controlled process characterizes phenol sorption. Furthermore, the mechanism of phenol sorption was deduced to be predominantly particle diffusion. The diffusion coefficients were determined using Fick's equation. The trend of diffusion of all phenols onto nanoporous silica was HOM-8 > HOM-2 > HOM-6 > HOM-5 > HOM-1 > HOM-3, reflecting the effect of the uniform pore size distribution and the internal surface area of the nanostructured silicas on the diffusion process.

  3. Application of a Burkholderia cepacia lipase-immobilized silica monolith to batch and continuous biodiesel production with a stoichiometric mixture of methanol and crude Jatropha oil

    Directory of Open Access Journals (Sweden)

    Takahashi Ryo

    2011-10-01

    Full Text Available Abstract Background The enzymatic production of biodiesel through alcoholysis of triglycerides has become more attractive because it shows potential in overcoming the drawbacks of chemical processes. In this study, we investigate the production of biodiesel from crude, non-edible Jatropha oil and methanol to characterize Burkholderia cepacia lipase immobilized in an n-butyl-substituted hydrophobic silica monolith. We also evaluate the performance of a lipase-immobilized silica monolith bioreactor in the continuous production of biodiesel. Results The Jatropha oil used contained 18% free fatty acids, which is problematic in a base-catalyzed process. In the lipase-catalyzed reaction, the presence of free fatty acids made the reaction mixture homogeneous and allowed bioconversion to proceed to 90% biodiesel yield after a 12 hour reaction time. The optimal molar ratio of methanol to oil was 3.3 to 3.5 parts methanol to one part oil, with water content of 0.6% (w/w. Further experiments revealed that B. cepacia lipase immobilized in hydrophobic silicates was sufficiently tolerant to methanol, and glycerol adsorbed on the support disturbed the reaction to some extent in the present reaction system. The continuous production of biodiesel was performed at steady state using a lipase-immobilized silica monolith bioreactor loaded with 1.67 g of lipase. The yield of 95% was reached at a flow rate of 0.6 mL/h, although the performance of the continuous bioreactor was somewhat below that predicted from the batch reactor. The bioreactor was operated successfully for almost 50 days with 80% retention of the initial yield. Conclusions The presence of free fatty acids originally contained in Jatropha oil improved the reaction efficiency of the biodiesel production. A combination of B. cepacia lipase and its immobilization support, n-butyl-substituted silica monolith, was effective in the production of biodiesel. This procedure is easily applicable to the design

  4. Rice Husk Ash as a Renewable Source for the Production of Value Added Silica Gel and its Application: An Overview

    Directory of Open Access Journals (Sweden)

    Ram Prasad

    2012-06-01

    Full Text Available In recent years, silica gels have developed a lot of interest due to their extraordinary properties and their existing and potential applications in science and technology. Silica gel has a wide range of applications such as a desiccant, as a preservation tool to control humidity, as an adsorbent, as a catalyst and as a cata-lyst support. Silica gel is a rigid three-dimensional network of colloidal silica, and is classified as: aqua-gel, alco-gel, xero-gel and aero-gel. Out of all known solid porous materials, aero-gels are particularly known for their high specific surface area, high porosity, low bulk density, high thermal insulation value, ultra low dielectric constant and low index of refraction. Because of these extraordinary properties silica aero-gel has many commercial applications such as thermal window insulation, acoustic barriers, super-capacitors and catalytic supports. However, monolithic silica aero-gel has been used extensively in high energy physics in Cherenkov radiation detectors and in shock wave studies at high pressures, inertial confinement fusion (ICF radio-luminescent and micrometeorites. Silica gel can be prepared by using various sol gel precursors but the rice husk (RH is considered as the cheapest source for silica gel production. Rice husk is a waste product abundantly available in rice producing countries during milling of rice. This review article aims at summarizing the developments carried out so far in synthesis, properties, characterization and method of determination of silica, silica gel, silica aero-gel and silica xero-gel. The effect of synthesis parameters such as pH, temperature of burning the rice husk, acid leaching prior to formation of rice husk ash (RHA on the properties of final product are also described. The attention is also paid on the application of RH, RHA, sil-ica, silica aero-gel and silica xero-gel. Development of economically viable processes for getting rice husk silica with specific

  5. Direct Cross-Linking of Au/Ag Alloy Nanoparticles into Monolithic Aerogels for Application in Surface-Enhanced Raman Scattering.

    Science.gov (United States)

    Gao, Xiaonan; Esteves, Richard J Alan; Nahar, Lamia; Nowaczyk, Jordan; Arachchige, Indika U

    2016-05-25

    The direct cross-linking of Au/Ag alloy nanoparticles (NPs) into high surface area, mesoporous Au/Ag aerogels via chemical oxidation of the surface ligands is reported. The precursor alloy NPs with composition-tunable morphologies were produced by galvanic replacement of the preformed Ag hollow NPs. The effect of Au:Ag molar ratio on the NP morphology and surface plasmon resonance has been thoroughly investigated and resulted in smaller Au/Ag alloy NPs (4-8 nm), larger Au/Ag alloy hollow NPs (40-45 nm), and Au/Ag alloy hollow particles decorated with smaller Au NPs (2-5 nm). The oxidative removal of surfactant ligands, followed by supercritical drying, is utilized to construct large (centimeter to millimeter) self-supported Au/Ag alloy aerogels. The resultant assemblies exhibit high surface areas (67-73 m(2)/g), extremely low densities (0.051-0.055 g/cm(3)), and interconnected mesoporous (2-50 nm) networks, making them of great interest for a number of new technologies. The influence of mesoporous gel morphology on surface-enhanced Raman scattering (SERS) has been studied using Rhodamine 101 (Rd 101) as the probe molecule. The alloy aerogels exhibit SERS signal intensities that are 10-42 times higher than those achieved from the precursor Au/Ag alloy NPs. The Au/Ag alloy aerogel III exhibits SERS sensing capability down to 1 nM level. The increased signal intensities attained for alloy aerogels are attributed to highly porous gel morphology and enhanced surface roughness that can potentially generate a large number of plasmonic hot spots, creating efficient SERS substrates for future applications.

  6. Violin mode amplitude glitch monitor for the presence of excess noise on the monolithic silica suspensions of GEO 600

    Energy Technology Data Exchange (ETDEWEB)

    Sorazu, B; Strain, K A; Heng, I S; Kumar, R, E-mail: b.sorazu@physics.gla.ac.u [Department of Physics and Astronomy, University of Glasgow, University Avenue, Glasgow G12 8QQ (United Kingdom)

    2010-08-07

    Non-Gaussian features of data from gravitational wave detectors are of interest as unpredictable 'glitches' limit the sensitivity of searches for many kinds of signal. We consider events due to non-random excitations of the test masses and their suspension fibres. These events could, for example, be related to acoustic emissions in the fibres due to the presence and propagation of cracks or another type of structural perturbation, and they would generate excess noise above the Gaussian background, which matches the level expected due to thermal noise. We look for excess noise in the fundamental violin modes of the monolithic silica suspension fibres of GEO 600. We describe the algorithm used to monitor the violin mode amplitude for glitches, present our results and consider how these may be applied to advanced detectors. The conclusion of our analysis is that no excess noise above what was considered to be thermal noise was observed for several days of h(t) data analysed at the frequency of the selected violin modes.

  7. Violin mode amplitude glitch monitor for the presence of excess noise on the monolithic silica suspensions of GEO 600

    International Nuclear Information System (INIS)

    Sorazu, B; Strain, K A; Heng, I S; Kumar, R

    2010-01-01

    Non-Gaussian features of data from gravitational wave detectors are of interest as unpredictable 'glitches' limit the sensitivity of searches for many kinds of signal. We consider events due to non-random excitations of the test masses and their suspension fibres. These events could, for example, be related to acoustic emissions in the fibres due to the presence and propagation of cracks or another type of structural perturbation, and they would generate excess noise above the Gaussian background, which matches the level expected due to thermal noise. We look for excess noise in the fundamental violin modes of the monolithic silica suspension fibres of GEO 600. We describe the algorithm used to monitor the violin mode amplitude for glitches, present our results and consider how these may be applied to advanced detectors. The conclusion of our analysis is that no excess noise above what was considered to be thermal noise was observed for several days of h(t) data analysed at the frequency of the selected violin modes.

  8. Violin mode amplitude glitch monitor for the presence of excess noise on the monolithic silica suspensions of GEO 600

    Science.gov (United States)

    Sorazu, B.; Strain, K. A.; Heng, I. S.; Kumar, R.

    2010-08-01

    Non-Gaussian features of data from gravitational wave detectors are of interest as unpredictable 'glitches' limit the sensitivity of searches for many kinds of signal. We consider events due to non-random excitations of the test masses and their suspension fibres. These events could, for example, be related to acoustic emissions in the fibres due to the presence and propagation of cracks or another type of structural perturbation, and they would generate excess noise above the Gaussian background, which matches the level expected due to thermal noise. We look for excess noise in the fundamental violin modes of the monolithic silica suspension fibres of GEO 600. We describe the algorithm used to monitor the violin mode amplitude for glitches, present our results and consider how these may be applied to advanced detectors. The conclusion of our analysis is that no excess noise above what was considered to be thermal noise was observed for several days of h(t) data analysed at the frequency of the selected violin modes.

  9. C₁₈-bound porous silica monolith particles as a low-cost high-performance liquid chromatography stationary phase with an excellent chromatographic performance.

    Science.gov (United States)

    Ali, Faiz; Cheong, Won Jo

    2014-12-01

    Ground porous silica monolith particles with an average particle size of 2.34 μm and large pores (363 Å) exhibiting excellent chromatographic performance have been synthesized on a relatively large scale by a sophisticated sol-gel procedure. The particle size distribution was rather broad, and the d(0.1)/d(0.9) ratio was 0.14. The resultant silica monolith particles were chemically modified with chlorodimethyloctadecylsilane and end-capped with a mixture of hexamethyldisilazane and chlorotrimethylsilane. Very good separation efficiency (185,000/m) and chromatographic resolution were achieved when the C18 -bound phase was evaluated for a test mixture of five benzene derivatives after packing in a stainless-steel column (1.0 mm × 150 mm). The optimized elution conditions were found to be 70:30 v/v acetonitrile/water with 0.1% trifluoroacetic acid at a flow rate of 25 μL/min. The column was also evaluated for fast analysis at a flow rate of 100 μL/min, and all the five analytes were eluted within 3.5 min with reasonable efficiency (ca. 60,000/m) and resolution. The strategy of using particles with reduced particle size and large pores (363 Å) combined with C18 modification in addition to partial-monolithic architecture has resulted in a useful stationary phase (C18 -bound silica monolith particles) of low production cost showing excellent chromatographic performance. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Carbon aerogels

    International Nuclear Information System (INIS)

    Berthon-Fabry, S.; Achard, P.

    2003-06-01

    The carbon aerogel is a nano-porous material at open porosity, electrical conductor. The aerogels morphology is variable in function of the different synthesis parameters. This characteristic offers to the aerogels a better adaptability to many applications: electrodes (super condensers, fuel cells). The author presents the materials elaboration and their applications. It provides also the research programs: fundamental research, realization of super-condenser electrodes, fuel cells electrodes, gas storage materials and opaque materials for thermal insulation. (A.L.B.)

  11. Graphene aerogels

    Science.gov (United States)

    Pauzauskie, Peter J; Worsley, Marcus A; Baumann, Theodore F; Satcher, Jr., Joe H; Biener, Juergen

    2015-03-31

    Graphene aerogels with high conductivity and surface areas including a method for making a graphene aerogel, including the following steps: (1) preparing a reaction mixture comprising a graphene oxide suspension and at least one catalyst; (2) curing the reaction mixture to produce a wet gel; (3) drying the wet gel to produce a dry gel; and (4) pyrolyzing the dry gel to produce a graphene aerogel. Applications include electrical energy storage including batteries and supercapacitors.

  12. Monolithic silica rod liquid chromatography with ultraviolet or fluorescence detection for metabolite analysis of cytochrome P450 marker reactions.

    Science.gov (United States)

    Lutz, E S M; Markling, M E; Masimirembwa, C M

    2002-11-25

    In vitro cytochrome P450 assays are used in metabolism studies in support of early phases of drug discovery to investigate, e.g., metabolic stability, enzyme inhibition and induction by new chemical entities. LC-UV and LC-fluorescence are traditional analytical tools in support of such studies. However, these tools typically comprise different methods of relatively low throughput for the various metabolites of probe reactions. In recent years, LC-MS methods have been developed to increase throughput. Increased throughput can also be achieved by means of modern chromatographic tools in combination with UV and fluorescence detection. This approach is especially suitable when cytochrome P450 isoforms are investigated by means of single probe incubations. Here, an LC-UV/fluorescence system based on a monolithic porous silica column is described for the analysis of metabolites of nine cytochrome P450 marker reactions [phenacetin to paracetamol (CYP1A2), coumarin to 7-hydroxycoumarin (CYP2A6), paclitaxel to 6alpha-hydroxypaclitaxel (CYP2C8), diclofenac to 4-hydroxydiclofenac (CYP2C9), mephenytoin to 4-hydroxymephenytoin (CYP2C19), bufuralol to 1-hydroxybufuralol (CYP2D6), chlorzoxazone to 6-hydroxychlorzoxazone (CYP2E1), midazolam to 1-hydroxymidazolam (CYP3A4), and testosteron to 6beta-hydroxytestosteron (CYP3A4)]. While offering sensitivities and linear ranges comparable to previously reported methods, the set-up described here provides ease of use and increased throughput with maximum cycle times of 4.5 min. Copyright 2002 Elsevier Science B.V.

  13. Automated dual two-dimensional liquid chromatography approach for fast acquisition of three-dimensional data using combinations of zwitterionic polymethacrylate and silica-based monolithic columns.

    Science.gov (United States)

    Hájek, Tomáš; Jandera, Pavel; Staňková, Magda; Česla, Petr

    2016-05-13

    A monolithic sulfobetaine polymethacrylate micro-column BIGDMA-MEDSA designed in our laboratory, shows dual retention mechanism: In acetonitrile-rich mobile phase, hydrophilic interactions control the retention (HILIC system), whereas in more aqueous mobile phases the column shows essentially reversed-phase behavior with major role of hydrophobic interactions. The zwitterionic polymethacrylate micro-column can be used in the first dimension of two-dimensional LC in alternating reversed-phase (RP) and HILIC modes, coupled with an alkyl-bonded core-shell or silica-based monolithic column in the second dimension, for HILIC×RP and RP×RP comprehensive two-dimensional separations. During the HILIC×RP period, a gradient of decreasing acetonitrile gradient is used for separation in the first dimension, so that at the end of the gradient the polymeric monolithic micro-column is equilibrated with a highly aqueous mobile phase and is ready for repeated sample injection, this time for separation under reversed-phase gradient conditions with increasing concentration of acetonitrile in the first dimension. The fast repeating reversed-phase gradients on a short silica-monolithic or core-shell column in the second dimension can be optimized independently of the actual running first-dimension gradient program. As the alternating HILIC and RP separations on the first-dimension zwitterionic methacrylate column are based on complementary retention mechanisms, the instrumental setup essentially represents two coupled two-dimensional systems. It is first time that such an automated dual LCxLC approach is reported. The novel system allows obtaining three-dimensional data in a relatively short time and can be applied not only to multidimensional gradient separations of flavones and related polyphenolic compounds. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. Durable polymer-aerogel based superhydrophobic coatings, a composite material

    Science.gov (United States)

    Kissel, David J; Brinker, Charles Jeffrey

    2014-03-04

    Provided are polymer-aerogel composite coatings, devices and articles including polymer-aerogel composite coatings, and methods for preparing the polymer-aerogel composite. The exemplary article can include a surface, wherein the surface includes at least one region and a polymer-aerogel composite coating disposed over the at least one region, wherein the polymer-aerogel composite coating has a water contact angle of at least about 140.degree. and a contact angle hysteresis of less than about 1.degree.. The polymer-aerogel composite coating can include a polymer and an ultra high water content catalyzed polysilicate aerogel, the polysilicate aerogel including a three dimensional network of silica particles having surface functional groups derivatized with a silylating agent and a plurality of pores.

  15. Durable polymer-aerogel based superhydrophobic coatings: a composite material

    Science.gov (United States)

    Kissel, David J.; Brinker, Charles Jeffrey

    2016-02-02

    Provided are polymer-aerogel composite coatings, devices and articles including polymer-aerogel composite coatings, and methods for preparing the polymer-aerogel composite. The exemplary article can include a surface, wherein the surface includes at least one region and a polymer-aerogel composite coating disposed over the at least one region, wherein the polymer-aerogel composite coating has a water contact angle of at least about 140.degree. and a contact angle hysteresis of less than about 1.degree.. The polymer-aerogel composite coating can include a polymer and an ultra high water content catalyzed polysilicate aerogel, the polysilicate aerogel including a three dimensional network of silica particles having surface functional groups derivatized with a silylating agent and a plurality of pores.

  16. 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).

  17. Thin-layer chromatographic plates with monolithic layer of silica: production, physical-chemical characteristics, separation capabilities.

    Science.gov (United States)

    Frolova, Anastasiya M; Konovalova, Olga Y; Loginova, Lidia P; Bulgakova, Alena V; Boichenko, Alexander P

    2011-08-01

    The technique for production of thin-layer chromatographic plates with fixed monolithic layer of sorbent was developed on the basis of investigation of factors affecting sorption capacity, sorption kinetics and mechanical stability of monoliths. The optimal reaction mixture for sol-gel synthesis of monoliths consisted of tetraethoxysilane, buffer solution with pH 7.4, N,N-dimethylformamide, ethanol, polyethyleneglycol with molecular weight 1000 and cetylpyridinium chloride in molar ratio 1.0:4.6:1.4:7.6:0.26:8×10(-3). On the basis of analysis of sorption kinetics of malachite green on the monoliths it was concluded that mechanism of sorption includes chemisorption. The optimized conditions for fixing the monolithic layer on the carrier and its drying allow obtaining undisturbed monolithic layer, which was used for test mixtures separation. The increase of monolithic layer thickness in comparison with ultrathin-layer chromatographic plates allows detecting visually at reasonable concentrations and loaded sample volumes the spots of food and synthetic dyes. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Influence of Aerogel Morphology and Reinforcement Architecture on Gas Convection in Aerogel Composites

    Science.gov (United States)

    Hurwitz, Frances I.; Meyer, Matthew; Guo, Haiquan; Rogers, Richard B.; DeMange, Jeffrey J.; Richardson, Hayley

    2016-01-01

    A variety of thermal protection applications require lightweight insulation capable of withstanding temperatures well above 900 C. Aerogels offer extremely low-density thermal insulation due to their mesoporous structure, which inhibits both gas convection and solid conduction. Silica aerogel systems are limited to use temperatures of 600-700 C, above which they sinter. Alumina aerogels maintain a porous structure to higher temperatures than silica, before transforming to -alumina and densifying. We have synthesized aluminosilicate aerogels capable of maintaining higher surface areas at temperatures above 1100 C than an all-alumina aerogel using -Boehmite as the aluminum source and tetraethoxysilane (TEOS) as the silicon source. The pore structure of these aerogels varies with thermal exposure temperature and time, as the aluminosilicate undergoes a variety of phase changes to form transition aluminas. Transformation to -alumina is inhibited by incorporation of silica into the alumina lattice. The aerogels are fragile, but can be reinforced using a large variety of ceramic papers, felts or fabrics. The objective of the current study is to characterize the influence of choice of reinforcement and architecture on gas permeability of the aerogel composites in both the as fabricated condition and following thermal exposure, as well as understand the effects of incorporating hydrophobic treatments in the composites.

  19. Silica Aerogel-supported Hydrozincite and Carbonate-intercalated Hydrotalcite for High-efficiency Removal of Pb(II) Ions by Precipitation Transformation Reactions

    Science.gov (United States)

    Wang, Lijun; Wang, Xiaoxia; Li, Jianfa; Feng, Xiaolan; Wang, Yusen

    2017-09-01

    In this work, hydrozincite and Zn/Al-CO3 2- hydrotalcite supported on silica aerogel were prepared via a simple and economical process and used as adsorbents for Pb(II) removal. The supported hydrozincite and Zn/Al-CO3 2- hydrotalcite possess ultra-thin thickness, high surface area, and weak crystallinity. In the batch Pb(II) adsorption experiments, the adsorbents with higher Zn(II) contents showed higher Pb(II) adsorption capacities, and the adsorption data fitted well with the Langmuir isotherm model and pseudo-second-order kinetic model, indicating a mechanism of surface chemisorption. The adsorption capacities calculated based Langmuir isotherm model are 684.9 mg/g and 555.6 mg/g for the supported hydrozincite and Zn/Al-CO3 2- hydrotalcite, respectively, higher than the adsorption capacities of other hydrotalcite-based adsorbents and most of other inorganic adsorbents reported previously. The XRD diffraction peaks of hydrozincite and Zn/Al-CO3 2- hydrotalcite disappeared after the adsorption, and the Pb(II) species were uniformly dispersed in the adsorbents in form of Pb3(CO3)2(OH)2 proven by TEM, EDS mapping and XRD analysis, demonstrating the nature of the adsorption is the precipitation conversion of hydrozincite or Zn/Al-CO3 2- hydrotalcite into Pb3(CO3)2(OH)2. These results demonstrate the synergic Pb(II) removal effect of the CO3 2- and OH- derived from hydrozincite and Zn/Al-CO3 2- hydrotalcite together with their ultra-thin thickness and high surface area contribute the excellent properties of the adsorbents.

  20. One-pot preparation of a mixed-mode organic-silica hybrid monolithic capillary column and its application in determination of endogenous gibberellins in plant tissues.

    Science.gov (United States)

    Zhang, Zheng; Hao, Yan-Hong; Ding, Jun; Xu, Sheng-Nan; Yuan, Bi-Feng; Feng, Yu-Qi

    2015-10-16

    A newly improved one-pot method, based on "thiol-ene" click chemistry and sol-gel approach in microemulsion system, was developed for the preparation of C8/PO(OH)2-silica hybrid monolithic capillary column. The prepared monolith possesses large specific surface area, narrow mesopore size distribution and high column efficiency. The monolithic column was demonstrated to have cation exchange/reversed-phase (CX/RP) mixed-mode retention for analytes on nano-liquid chromatography (nano-LC). On the basis of the developed nano-LC system with MS detector coupled to pipette tip solid phase extraction (PT-SPE) and derivatization process, we then realized simultaneous determination of 10 gibberellins (GAs) with low limits of detection (LODs, 0.003-0.025 ng/mL). Furthermore, 6 endogenous GAs in only 5mg rice leaves (fresh weight) were successfully detected and quantified. The developed PT-SPE-nano-LC-MS strategy may offer promising applications in the determination of low abundant bioactive molecules from complex matrix. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. Selective CO2 Sequestration with Monolithic Bimodal Micro/Macroporous Carbon Aerogels Derived from Stepwise Pyrolytic Decomposition of Polyamide-Polyimide-Polyurea Random Copolymers.

    Science.gov (United States)

    Saeed, Adnan M; Rewatkar, Parwani M; Majedi Far, Hojat; Taghvaee, Tahereh; Donthula, Suraj; Mandal, Chandana; Sotiriou-Leventis, Chariklia; Leventis, Nicholas

    2017-04-19

    Polymeric aerogels (PA-xx) were synthesized via room-temperature reaction of an aromatic triisocyanate (tris(4-isocyanatophenyl) methane) with pyromellitic acid. Using solid-state CPMAS 13 C and 15 N NMR, it was found that the skeletal framework of PA-xx was a statistical copolymer of polyamide, polyurea, polyimide, and of the primary condensation product of the two reactants, a carbamic-anhydride adduct. Stepwise pyrolytic decomposition of those components yielded carbon aerogels with both open and closed microporosity. The open micropore surface area increased from capacity for CO 2 (up to 4.9 mmol g -1 ), and selectivity toward other gases (via Henry's law). The selectivity for CO 2 versus H 2 (up to 928:1) is suitable for precombustion fuel purification. Relevant to postcombustion CO 2 capture and sequestration (CCS), the selectivity for CO 2 versus N 2 was in the 17:1 to 31:1 range. In addition to typical factors involved in gas sorption (kinetic diameters, quadrupole moments and polarizabilities of the adsorbates), it is also suggested that CO 2 is preferentially engaged by surface pyridinic and pyridonic N on carbon (identified with XPS) in an energy-neutral surface reaction. Relatively high uptake of CH 4 (2.16 mmol g -1 at 0 °C/1 bar) was attributed to its low polarizability, and that finding paves the way for further studies on adsorption of higher (i.e., more polarizable) hydrocarbons. Overall, high CO 2 selectivities, in combination with attractive CO 2 adsorption capacities, low monomer cost, and the innate physicochemical stability of carbon render the materials of this study reasonable candidates for further practical consideration.

  2. Sedimentation assisted preparation of ground particles of silica monolith and their C18 modification resulting in a chromatographic phase of improved separation efficiency.

    Science.gov (United States)

    Ali, Ashraf; Ali, Faiz; Cheong, Won Jo

    2017-11-24

    The sedimentation procedure has been adopted in production of ground silica monolith particles to improve chromatographic separation efficiency of the resultant phase. First, silica monolith particles have been successfully prepared in a large scale by a sol-gel process followed by grinding. The particles after calcination were separated by sedimentation into three zones using an Imhoff sedimentation cone. The particles of the bottom zone were derivatized with a C18 ligand and end-capped. The sedimentation process was found to not only eliminate troublesome minute particles but also narrow down the particle size distribution. The resultant phase was packed in glass lined stainless steel micro-columns. The average number of theoretical plates (N) of the columns for a test mixture was 47,000 and 29,300 for the 300 and 150mm columns (1mm internal diameter), corresponding to 157,000/m and 195,000/m, respectively. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Thermal properties of methyltrimethoxysilane aerogel thin films

    Directory of Open Access Journals (Sweden)

    Leandro N. Acquaroli

    2016-10-01

    Full Text Available Aerogels are light and porous solids whose properties, largely determined by their nanostructure, are useful in a wide range of applications, e.g., thermal insulation. In this work, as-deposited and thermally treated air-filled silica aerogel thin films synthesized using the sol-gel method were studied for their thermal properties using the 3-omega technique, at ambient conditions. The thermal conductivity and diffusivity were found to increase as the porosity of the aerogel decreased. Thermally treated films show a clear reduction in thermal conductivity compared with that of as-deposited films, likely due to an increase of porosity. The smallest thermal conductivity and diffusivity found for our aerogels were 0.019 W m−1 K−1 and 9.8 × 10-9 m2 s−1. A model was used to identify the components (solid, gaseous and radiative of the total thermal conductivity of the aerogel.

  4. Evaluation of supercritical CO2 dried cellulose aerogels as nano-biomaterials

    Science.gov (United States)

    Lee, Sinah; Kang, Kyu-Young; Jeong, Myung-Joon; Potthast, Antje; Liebner, Falk

    2017-10-01

    Cellulose is the renewable, biodegradable and abundant resource and is suggested as an alternative material to silica due to the high price and environmental load of silica. The first step for cellulose aerogel production is to dissolve cellulose, and hydrated calcium thiocyanate molten salt is one of the most effective solvents for preparing porous material. Cellulose aerogels were prepared from dissolved cellulose samples of different degree of polymerization (DP) and drying methods, and tested with shrinkage, density and mechanical strength. Supercritical CO2 dried cellulose aerogels shrank less compared to freeze-dried cellulose aerogels, whereas the densities were increased according to the DP increases in both cellulose aerogels. Furthermore, scanning electron microscope (SEM) images showed that the higher DP cellulose aerogels were more uniform with micro-porous structure. Regarding the mechanical strength of cellulose aerogels, supercritical CO2 dried cellulose aerogels with higher molecular weight were much more solid.

  5. Tuning preparation conditions towards optimized separation performance of thermally polymerized organo-silica monolithic columns in capillary liquid chromatography.

    Science.gov (United States)

    Gharbharan, Deepa; Britsch, Denae; Soto, Gabriela; Weed, Anna-Marie Karen; Svec, Frantisek; Zajickova, Zuzana

    2015-08-21

    Tuning of preparation conditions, such as variations in the amount of a porogen, concentration of an aqueous acid catalyst, and adjustment in polymerization temperature and time, towards optimized chromatographic performance of thermally polymerized monolithic capillaries prepared from 3-(methacryloyloxy)propyltrimethoxysilane has been carried out. Performance of capillary columns in reversed-phase liquid chromatography was assessed utilizing various sets of solutes. Results describing hydrophobicity, steric selectivity, and extent of hydrogen bonding enabled comparison of performance of hybrid monolithic columns prepared under thermal (TSG) and photopolymerized (PSG) conditions. Reduced amounts of porogen in the polymerization mixture, and prolonged reaction times were necessary for the preparation of monolithic columns with enhanced retention and column efficiency that reached to 111,000 plates/m for alkylbenzenes with shorter alkyl chains. Both increased concentration of catalyst and higher temperature resulted in faster polymerization but inevitably in insufficient time for pore formation. Thermally polymerized monoliths produced surfaces, which were slightly more hydrophobic (a methylene selectivity of 1.28±0.002 TSG vs 1.20±0.002 PSG), with reduced number of residual silanols (a caffeine/phenol selectivity of 0.13±0.001 TSG vs 0.17±0.003 PSG). However, steric selectivity of 1.70±0.01 was the same for both types of columns. The batch-to-batch repeatability was better using thermal initiation compared to monolithic columns prepared under photopolymerized conditions. RSD for retention factor of benzene was 3.7% for TSG capillaries (n=42) vs. 6.6% for PSG capillaries (n=18). A similar trend was observed for columns prepared within the same batch. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. Monolithic silica spin column extraction and simultaneous derivatization of amphetamines and 3,4-methylenedioxyamphetamines in human urine for gas chromatographic-mass spectrometric detection

    Energy Technology Data Exchange (ETDEWEB)

    Nakamoto, Akihiro [Scientific Investigation Laboratory, Hiroshima Prefectural Police Headquarters, Kohnan 2-26-3, Naka-ku, Hiroshima 730-0825 (Japan); Nishida, Manami [Hiroshima University Technical Center, Kasumi 1-2-3, Minami-ku, Hiroshima 734-8551 (Japan); Saito, Takeshi [Department of Emergency and Critical Care Medicine, Tokai University School of Medicine, Shimokasuya 143, Isehara, Kanagawa 259-1143 (Japan); Kishiyama, Izumi; Miyazaki, Shota [GL Sciences Inc., Sayamagahara 237-2, Iruma, Saitama 358-0032 (Japan); Murakami, Katsunori [Scientific Investigation Laboratory, Hiroshima Prefectural Police Headquarters, Kohnan 2-26-3, Naka-ku, Hiroshima 730-0825 (Japan); Nagao, Masataka [Department of Forensic Medicine, Graduate School of Biomedical Sciences, Hiroshima University, Kasumi 1-2-3, Minami-ku, Hiroshima 734-8551 (Japan); Namura, Akira, E-mail: namera@hiroshima-u.ac.jp [Department of Forensic Medicine, Graduate School of Biomedical Sciences, Hiroshima University, Kasumi 1-2-3, Minami-ku, Hiroshima 734-8551 (Japan)

    2010-02-19

    A simple, sensitive, and specific method with gas chromatography-mass spectrometry was developed for simultaneous extraction and derivatization of amphetamines (APs) and 3,4-methylenedioxyamphetamines (MDAs) in human urine by using a monolithic silica spin column. All the procedures, such as sample loading, washing, and elution were performed by centrifugation. APs and MDAs in urine were adsorbed on the monolithic silica and derivatized with propyl chloroformate in the column. Methamphetamine-d{sub 5} was used as an internal standard. The linear ranges were 0.01-5.0 {mu}g mL{sup -1} for methamphetamine (MA) and 3,4-methylenedioxymethamphetamine (MDMA) and 0.02-5.0 {mu}g mL{sup -1} for amphetamine (AP) and 3,4-methylenedioxyamphetamine (MDA) (coefficient of correlation {>=}0.995). The recovery of APs and MDAs in urine was 84-94%, and the relative standard deviation of the intra- and interday reproducibility for urine samples containing 0.1, 1.0, and 4.0 {mu}g mL{sup -1} of APs and MDAs ranged from 1.4% to 13.6%. The lowest detection limit (signal-to-noise ratio {>=} 3) in urine was 5 ng mL{sup -1} for MA and MDMA and 10 ng mL{sup -1} for AP and MDA. The proposed method can be used to perform simultaneous extraction and derivatization on spin columns that have been loaded with a small quantity of solvent by using centrifugation.

  7. Magnetic and Mössbauer spectroscopy studies of nanocrystalline iron oxide aerogels

    DEFF Research Database (Denmark)

    Carpenter, E.E.; Long, J.W.; Rolison, D.R.

    2006-01-01

    A sol-gel synthesis was used to produce iron oxide aerogels. These nanocrystalline aerogels have a pore-solid structure similar to silica aerogels but are composed entirely of iron oxides. Mössbauer experiments and x-ray diffraction showed that the as-prepared aerogel is an amorphous or poorly...... by magnetic interactions between the particles at lower temperatures. ©2006 American Institute of Physics...

  8. Flame Retardant Effect of Aerogel and Nanosilica on Engineered Polymers

    Science.gov (United States)

    Williams, Martha K.; Smith, Trent M.; Roberson, Luke B.; Yang, Feng; Nelson, Gordon L.

    2010-01-01

    Aerogels are typically manufactured vIa high temperature and pressure-critical-point drying of a colloidal metal oxide gel filled with solvents. Aerogel materials derived from silica materials represent a structural morphology (amorphous, open-celled nanofoams) rather than a particular chemical constituency. Aerogel is not like conventional foams in that it is a porous material with extreme microporosity and composed of individual features only a few nanometers in length with a highly porous dendriticlike structure. This unique substance has unusual properties such as low thermal conductivity, refractive index and sound suppression; in addition to its exceptional ability to capture fast moving dust. The highly porous nature of the aerogel's structure provides large amounts of surface area per unit weight. For instance, a silica aerogel material with a density of 100 kilograms per cubic meters can have surface areas of around 800 to 1500 square meters per gram depending on the precursors and process utilized to produce it. To take advantage of the unique properties of silica aerogels, especially the ultra light weight and low thermal conductivity, their composites with various engineering polymers were prepared and their flammability was investigated by Cone Calorimetry. The flammability of various polystyrene/silica aerogel nanocomposites were measured. The combination of these nanocomposites with a NASA patented flame retardant SINK were also studied. The results were compared with the base polymer to show the differences between composites with different forms of silica.

  9. Aerogel sorbents

    Energy Technology Data Exchange (ETDEWEB)

    Begag, Redouane; Rhine, Wendell E.; Dong, Wenting

    2018-04-03

    The current invention describes methods and compositions of various sorbents based on aerogels of various silanes and their use as sorbent for carbon dioxide. Methods further provide for optimizing the compositions to increase the stability of the sorbents for prolonged use as carbon dioxide capture matrices.

  10. Measurement of the eddy dispersion term in chromatographic columns. II. Application to new prototypes of 2.3 and 3.2 mm I.D. monolithic silica columns.

    Science.gov (United States)

    Gritti, Fabrice; Guiochon, Georges

    2012-03-02

    The mass transfer mechanisms in silica monolithic columns of the second generation were investigated, using four research samples (two 2.3 mm × 50 mm and two 3.2 mm × 50 mm silica rods) provided by their manufacturer. The heights equivalent to a theoretical plate (HETP) of these columns were measured in a range of mobile phase velocities, following a meticulous experimental protocol. The coefficients of the van Deemter equation (longitudinal diffusion term B/u(S), skeleton/eluent mass transfer resistance term Cu(S), and eddy diffusion term A) were determined. The protocol includes using the peak parking method (to determine the longitudinal diffusion term), an accurate model of effective diffusion in silica monolithic structures (to determine the skeleton/eluent mass transfer resistance term), and an accurate method to measure the column HETP and determine the eddy diffusion term. The results show that the minimum plate heights of these new monolithic columns ranges between 4 and 5 μm, three to four times lower than those observed for monolithic columns of the first generation. A detailed analysis of the eddy diffusion term demonstrates that this improvement in column efficiency is partly explained by the reduction of the domain size (the sum of the skeleton and throughpore sizes, -40%) but mostly by an increase of the radial homogeneity of the monolithic rods. The columns of this second generation exhibit residual trans-column relative velocity biases as low a 1.4% (instead of 3% for previous columns), a value which is comparable to those observed in 4.6mm I.D. columns packed with sub-3 μm core-shell particles, with which they might become competitive. Copyright © 2011 Elsevier B.V. All rights reserved.

  11. Aerogel Projects Ongoing in MSFC's Engineering Directorate

    Science.gov (United States)

    Shular, David A.; Smithers, Gweneth A.; Plawsky, Joel L.; Whitaker, Ann F. (Technical Monitor)

    2000-01-01

    When we speak of an aerogel material, we are referring more to process and structure am to a specific substance. Aerogel, considered the lightest solid material, has been made from silica for seventy years. Resorcinol-formaldehyde, organic aerogels have been developed more recently. However, aerogel can be made from almost any type of substance, even lead. Because an aerogel is mostly air (about 99 %), the solid substance used will affect the weight very little. The term "aerogel" connotes the sol-gel process used to manufacture the material. The aerogel begins as a liquid "sol," becomes a solid "alcogel," and is then dried to become an "aerogel." The final product has a unique structure, useful for exploitation. It is an "open pore" system with nano-sized particles and pores, has very high surface area, and is highly interconnected. Besides low weight, aerogels have ultimate (lowest) values in other properties: thermal conductivity, refractive index, sound speed, and dielectric constant. Aerogels were first prepared in 1931 by Steven Kistler, who used a supercritical drying step to replace the liquid in a gel with air, preserving the structure (1). Kistler's procedure involved a water-to-alcohol exchange step; in the 1970's, this step was eliminated when a French investigator introduced the use of tetramethylorthosilicate. Still, alcohol drying involved dangerously high temperatures and pressures. In the 1980's, the Microstructured Materials Group at Berkeley Laboratory found that the alcohol in the gel could be replaced with liquid carbon dioxide before supercritical drying, which greatly improved safety (2). 'Me most recent major contribution has been that of Deshpande, Smith and Brinker in New Mexico, who are working to eliminate the supercritical drying step (3). When aerogels were first being developed, they were evaporatively dried. However, the wet gel, when dried, underwent severe shrinkage and cracking; this product was termed "xerogel." When the

  12. Measurements of scattering, transmittance/reflectance, IR-transmittance and thermal conductivity of small aerogel samples

    DEFF Research Database (Denmark)

    Duer, Karsten; Svendsen, Sv Aa Højgaard

    1997-01-01

    By providing at the same time thermal insulation and transparency the silica aerogel is a very attractive material for the purpose of improving the thermal performance of windows. Nevertheless a lot of problems have to be solved on the way from concept to the developed product. The B1 Aerogels...... project deals with some of these problems.This report summarizes the work that has been carried out on the subject of characterizing the optical and thermal performance of different types of aerogels and aerogel-like materials for the purpose of using aerogel in clear glazings.All measurements presented...

  13. Rapid tea catechins and caffeine determination by HPLC using microwave-assisted extraction and silica monolithic column.

    Science.gov (United States)

    Rahim, A A; Nofrizal, S; Saad, Bahruddin

    2014-03-15

    A rapid reversed-phase high performance liquid chromatographic method using a monolithic column for the determination of eight catechin monomers and caffeine was developed. Using a mobile phase of water:acetonitrile:methanol (83:6:11) at a flow rate of 1.4 mL min(-1), the catechins and caffeine were isocratically separated in about 7 min. The limits of detection and quantification were in the range of 0.11-0.29 and 0.33-0.87 mg L(-1), respectively. Satisfactory recoveries were obtained (94.2-105.2 ± 1.8%) for all samples when spiked at three concentrations (5, 40 and 70 mg L(-1)). In combination with microwave-assisted extraction (MAE), the method was applied to the determination of the catechins and caffeine in eleven tea samples (6 green, 3 black and 2 oolong teas). Relatively high levels of caffeine were found in black tea, but higher levels of the catechins, especially epigallocatechin gallate (EGCG) were found in green teas. Copyright © 2013 Elsevier Ltd. All rights reserved.

  14. Crystalline boron nitride aerogels

    Energy Technology Data Exchange (ETDEWEB)

    Zettl, Alexander K.; Rousseas, Michael; Goldstein, Anna P.; Mickelson, William; Worsley, Marcus A.; Woo, Leta

    2017-12-12

    This disclosure provides methods and materials related to boron nitride aerogels. For example, one aspect relates to a method for making an aerogel comprising boron nitride, comprising: (a) providing boron oxide and an aerogel comprising carbon; (b) heating the boron oxide to melt the boron oxide and heating the aerogel; (c) mixing a nitrogen-containing gas with boron oxide vapor from molten boron oxide; and (d) converting at least a portion of the carbon to boron nitride to obtain the aerogel comprising boron nitride. Another aspect relates to a method for making an aerogel comprising boron nitride, comprising heating boron oxide and an aerogel comprising carbon under flow of a nitrogen-containing gas, wherein boron oxide vapor and the nitrogen-containing gas convert at least a portion of the carbon to boron nitride to obtain the aerogel comprising boron nitride.

  15. Synthesis and electronic structure of low-density monoliths of nanoporous nanocrystalline anatase TiO2

    Energy Technology Data Exchange (ETDEWEB)

    Kucheyev, S O; Baumann, T F; Wang, Y M; van Buuren, T; Satcher, J H

    2004-08-13

    Monolithic nanocrystalline anatase titania aerogels are synthesized by the epoxide sol-gel method followed by thermal annealing at 550 C. These aerogels are formed by {approx}10-20 nm size anatase nanoparticles which are randomly oriented and interconnected into an open-cell solid network. Aerogel monoliths have an apparent density of {approx}6% and a surface area of {approx} 100 m{sup 2} g{sup -1}. High-resolution transmission electron microscopy and soft x-ray absorption near-edge structure spectroscopy reveal good crystallinity of the anatase nanoparticles forming the aerogel skeleton.

  16. Evaluation of fused-core and monolithic versus porous silica-based C18 columns and porous graphitic carbon for ion-pairing liquid chromatography analysis of catecholamines and related compounds.

    Science.gov (United States)

    Chirita, Raluca-Ioana; Finaru, Adriana-Luminita; Elfakir, Claire

    2011-03-15

    This paper evaluates the performances of reversed-phase (RPLC) and ion-pairing chromatography (IPLC) coupled with UV detection for the analysis of a set of 12 catecholamines and related compounds. Different chromatographic columns (porous C18-silica, perfluorinated C18-silica, porous graphitic carbon, monolithic and fused-core silica-based C18 columns) were tested using semi-long perfluorinated carboxylic acids as volatile ion-pairing reagents. Much more promising results were obtained by IPLC than by RPLC and important improvements in analytes peak symmetry and separation resolution were observed when using the "fast chromatography" columns (monolithic and fused-core C18) under IPLC conditions. For UV detection, a satisfactory separation of the 12 selected analytes was achieved in less than 20 min by using a fused-core particles column (Halo C18) and a mobile phase composed of a 1.25 mM nonafluoropentanoic acid aqueous solution and methanol under gradient elution mode. The chromatographic method developed can be directly coupled with electrospray ionization tandem mass spectrometry (ESI-MS/MS) in positive ionization mode and 10 solutes among those selected can be observed. The presence of the acidic ion-pairing reagent in the mobile phase makes this system incompatible with negative ionization mode and thus unable to detect the two acidic compounds that only responded in negative mode. In terms of MS detection, Monolithic C18 column proved to be the best one to reach the lowest detection limits (LODs) (from 0.5 ngmL(-1) to 10 ngmL(-1) depending on the neurotransmitter). The applicability of the optimized LC-MS/MS method to a "real world" sample was finally evaluated. The presence of the matrix leads to signal suppression for several solutes and thus to higher LODs. Copyright © 2011 Elsevier B.V. All rights reserved.

  17. Monolithic bed structure for capillary liquid chromatography.

    Science.gov (United States)

    Aggarwal, Pankaj; Tolley, H Dennis; Lee, Milton L

    2012-01-06

    Monolithic stationary phases show promise for LC as a result of their good permeability, ease of preparation and broad selectivity. Inorganic silica monoliths have been extensively studied and applied for separation of small molecules. The presence of a large number of through pores and small skeletal structure allows the chromatographic efficiencies of silica monoliths to be comparable to columns packed with 5 μm silica particles, at much lower back pressure. In comparison, organic polymeric monoliths have been mostly used for separation of bio-molecules; however, recently, applications are expanding to small molecules as well. Organic monoliths with high surface areas and fused morphology rather than conventional globular morphology have shown good performance for small molecule separations. Factors such as domain size, through-pore size and mesopore size of the monolithic structures have been found to govern the efficiency of monolithic columns. The structure and performance of monolithic columns are reviewed in comparison to particle packed columns. Studying and characterizing the bed structures of organic monolithic columns can provide great insights into their performance, and aid in structure-directed synthesis of new and improved monoliths. Copyright © 2011 Elsevier B.V. All rights reserved.

  18. Optimization of an aerogel cerenkov detector having a mirror light collection system

    International Nuclear Information System (INIS)

    Johansson, K.E.; Aakesson, T.; Norrby, J.

    1979-01-01

    Cerenkov detectors with silica aerogel of refractive indec 1.03 as the radiator have been tested in a particle beam at the CERN Proton Synchrotron. With a detector surface of 22 x 50 cm 2 and 9 cm thickness of aerogel, the number of photoelectrons was found to be 6.5 for β = 1 particles. (author)

  19. Vanadium oxide/polypyrrole aerogel nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Dave, B.C.; Dunn, B.S.; Wong, H.P. [Univ. of California, Los Angeles, CA (United States). Dept. of Materials Science and Engineering; Leroux, F.; Nazar, L.F. [Univ. of Waterloo, Ontario (Canada). Dept. of Chemistry

    1996-12-31

    Vanadium pentoxide/polypyrrole aerogel (ARG) nanocomposites were prepared by hydrolysis of VO(OC{sub 3}H{sub 7}){sub 3} using pyrrole/water/acetone mixtures. Monolithic green-black gels with polypyrrole/V ratios ranging from 0.15 to 1.0 resulted from simultaneously polymerization of the pyrrole and vanadium alkoxide precursors. Supercritical drying yielded high surface (150--200 m{sup 2}/g) aerogels, of sufficient mechanical integrity to allow them to be cut without fracturing. TEM studies of the aerogels show that they are comprised of fibers similar to that of V{sub 2}O{sub 5} ARG`s, but with a much shorter chain length. Evidence from IR that the inorganic and organic components strongly interact leads them to propose that this impedes the vanadium condensation process. The result is ARG`s that exhibit decreased electronic conductivity with increasing polymer content. Despite the unexpected deleterious effect of the conductive polymer on the bulk conductivity, at low polymer content, the nanocomposite materials show enhanced electrochemical properties for Li insertion compared to the pristine aerogel.

  20. A novel dilute and shoot HPLC assay method for quantification of irbesartan and hydrochlorothiazide in combination tablets and urine using second generation C18-bonded monolithic silica column with double gradient elution.

    Science.gov (United States)

    Koyuturk, Sema; Can, Nafiz Oncu; Atkosar, Zeki; Arli, Goksel

    2014-08-01

    Irbesartan (IRB) and hydrochlorothiazide (HCT) are angiotensin-II receptor antagonist and thiazide-class diuretic compounds, respectively, which are in use in the treatment of hypertension. A novel dilute-and-shoot HPLC assay method for simultaneous quantification of IRB and HCT in fixed-dose combination tablets and urine samples was described. The separation of IRB, HCT and agomelatine (internal standard) was carried out using a second generation C18-bonded monolithic silica column (Chromolith(®) High Resolution RP-18e, 100×4.6mm, Merck KGaA), utilizing both mobile phase and flow rate gradient elution programs. The analytes were detected at 230 nm wavelength using photodiode array detector within 24 minutes with high resolution, observing about 50 percent more peak capacity when using second generation C18-bonded monolithic silica column. Urine samples were introduced into the system effortlessly, with only filtration and subsequent dilution. Validation studies were performed according to the official recommendations of USP and ICH, and the developed method was successfully applied to pharmaceutical tablets and urine samples. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. Optical and ageing studies of aerogel samples for RICH applications in space

    Science.gov (United States)

    Martínez-Dávalos, A.; Belmont-Moreno, E.; Menchaca-Rocha, A.

    2005-11-01

    Optical and ageing properties of hydrophobic silica aerogel have been measured. The optical observations include the determination of the index of refraction of individual aerogel samples, and transmittance measurements. Concerning ageing, we investigate possible explanations for an appreciable decrease on the light yield observed in the aerogel tiles used in the AMS-01 Cherenkov detector, flown on board of the NASA Discovery Shuttle. Measurements were carried out simulating the vacuum and thermal cycle to which the aerogel was subject. These tests indicate that this material is very sensitive to residual contaminants that might be present during the vacuum pumping and/or gas admission process.

  2. Technical applications of aerogels

    International Nuclear Information System (INIS)

    Hrubesh, L.W.

    1997-01-01

    Aerogel materials posses such a wide variety of exceptional properties that a striking number of applications have developed for them. Many of the commercial applications of aerogels such as catalysts, thermal insulation, windows, and particle detectors are still under development and new application as have been publicized since the ISA4 Conference in 1994: e.g.; supercapacitors, insulation for heat storage in automobiles, electrodes for capacitive deionization, etc. More applications are evolving as the scientific and engineering community becomes familiar with the unusual and exceptional physical properties of aerogels, there are also scientific and technical application, as well. This paper discusses a variety of applications under development at Lawrence Livermore National Laboratory for which several types of aerogels are formed in custom sizes and shapes. Particular discussions will focus on the uses of aerogels for physics experiments which rely on the exceptional, sometimes unique, properties of aerogels

  3. Flexible Carbon Aerogels

    Directory of Open Access Journals (Sweden)

    Marina Schwan

    2016-09-01

    Full Text Available Carbon aerogels are highly porous materials with a large inner surface area. Due to their high electrical conductivity they are excellent electrode materials in supercapacitors. Their brittleness, however, imposes certain limitations in terms of applicability. In that context, novel carbon aerogels with varying degree of flexibility have been developed. These highly porous, light aerogels are characterized by a high surface area and possess pore structures in the micrometer range, allowing for a reversible deformation of the aerogel network. A high ratio of pore size to particle size was found to be crucial for high flexibility. For dynamic microstructural analysis, compression tests were performed in-situ within a scanning electron microscope allowing us to directly visualize the microstructural flexibility of an aerogel. The flexible carbon aerogels were found to withstand between 15% and 30% of uniaxial compression in a reversible fashion. These findings might stimulate further research and new application fields directed towards flexible supercapacitors and batteries.

  4. Technical applications of aerogels

    Energy Technology Data Exchange (ETDEWEB)

    Hrubesh, L.W.

    1997-08-18

    Aerogel materials posses such a wide variety of exceptional properties that a striking number of applications have developed for them. Many of the commercial applications of aerogels such as catalysts, thermal insulation, windows, and particle detectors are still under development and new application as have been publicized since the ISA4 Conference in 1994: e.g.; supercapacitors, insulation for heat storage in automobiles, electrodes for capacitive deionization, etc. More applications are evolving as the scientific and engineering community becomes familiar with the unusual and exceptional physical properties of aerogels, there are also scientific and technical application, as well. This paper discusses a variety of applications under development at Lawrence Livermore National Laboratory for which several types of aerogels are formed in custom sizes and shapes. Particular discussions will focus on the uses of aerogels for physics experiments which rely on the exceptional, sometimes unique, properties of aerogels.

  5. [Preparation of monolithic materials and their applications in proteomic analysis].

    Science.gov (United States)

    Liang, Yu; Zhang, Lihua; Zhang, Yukui

    2011-09-01

    Proteomics is one of the core contents of life science in the post-genomic era, among which it is very important to develop the analytical techniques with high resolution, high sensitivity, high accuracy and high throughput. With the advantages of facile preparation, fast mass transfer, low backpressure and easy modification, monolithic materials have been widely used in proteomic analysis. This review summarizes the preparation methods of different kinds of monolithic materials (including organic polymer monoliths, silica-based monoliths, organic-inorganic hybrid silica monoliths) and their applications in proteomic study such as the digestion of proteins, the separation of proteins or peptides, high throughput analysis integrating online digestion, separation and identification.

  6. A hybrid concept (segmented plus monolithic fused silica shells) for a high-throughput and high-angular resolution x-ray mission (Lynx/X-Ray Surveyor like)

    Science.gov (United States)

    Basso, Stefano; Civitani, Marta; Pareschi, Giovanni; Parodi, Giancarlo

    2017-09-01

    Lynx is a large area and high angular resolution X-ray mission being studied by NASA to be presented to the next Decadal Survey for the implementation in the next decade. It aims to realize an X-ray telescope with the effective area similar to Athena (2 m2 at 1 keV) but with the same angular resolution of Chandra and a much larger Field Of View (up 20 arcmin x 20 arcmin). The science of X-ray Surveyor requires a large-throughput mirror assembly with sub-arcsec angular resolution. These future X-ray mirrors have a set of requirements which, collectively, represents very substantial advances over any currently in operation or planned for missions other than X-ray Surveyor. Of particular importance is achieving low mass per unit collecting area, while maintaining Chandra like angular resolution. Among the possible solutions under study, the direct polishing of both thin monolithic pseudo-cylindrical shells and segments made of fused silica are being considered as viable solutions for the implementation of the mirrors. Fused silica has very good thermomechanical parameters (including a very low CTE), making the material particularly well suited for for the production of the Lynx mirrors. It should be noted that the use of close shells is also very attractive, since the operations for the integration of the shells will be greatly simplified and the area lost due to the vignetting from the interfacing structures minimized even if the management of such big (diameter of 3 m) and thin shells have to be demonstrated. In this paper we will discuss a possible basic layout for a full shell mirror and a hybrid concept (segmented plus monolithic shells made of fused silica) as a second solution, for the Lynx/XRS telescope, discussing preliminary results in terms of optical and mechanical performance.

  7. Aerogel-clad optical fiber

    Science.gov (United States)

    Sprehn, Gregory A.; Hrubesh, Lawrence W.; Poco, John F.; Sandler, Pamela H.

    1997-01-01

    An optical fiber is surrounded by an aerogel cladding. For a low density aerogel, the index of refraction of the aerogel is close to that of air, which provides a high numerical aperture to the optical fiber. Due to the high numerical aperture, the aerogel clad optical fiber has improved light collection efficiency.

  8. Synthesis and characterization of hybrid composite aerogels from alginic acid and graphene oxide

    Science.gov (United States)

    Co, C. J. U.; Quitain, A. T.; Borja, J. Q.; Dugos, N. P.; Takafuji, M.; Kida, T.

    2017-06-01

    Aerogels are one class of solid adsorbents that are gaining considerable attention because of their very high porosity, high specific surface area, and extremely low density. However, most aerogels being studied and used recently are synthetic in nature, which are usually mesoporous silica and metal-organic frameworks (MOFs). As research focus is geared towards sustainable engineering, it is desired to utilize biomass to synthesize aerogels. This study thus aims to produce alginic acid-graphene oxide hybrid composite aerogels and compare them with its existing synthetic counterparts. Alginic acid (AA) is an abundant marine biopolymer that easily forms gels, while graphene oxide (GO) is a nanomaterial consisting of many functional groups. Aerogels made up of AA and GO were successfully synthesized using a sol-gel method. The hydrogel was converted into an aerogel by drying with supercritical carbon dioxide. The percentage of graphene oxide was varied from 0 to 20%. The aerogels were characterized by scanning electron microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and nitrogen adsorption-desorption measurements. The addition of GO increased the specific surface area of the aerogel up to a certain point, after which it decreased. The 10% GO-AA aerogel showed the most favourable porosity characteristics with a specific surface area of 177.26 m2/g and average pore diameter of 53.2 nm. There had been no observable difference in the thermal behaviour of the aerogels with a change in the concentration of graphene oxide.

  9. B1 Aerogels

    DEFF Research Database (Denmark)

    Duer, Karsten; Svendsen, Sv Aa Højgaard

    1996-01-01

    The report summarizes the work which has been carried out since the 7th Expert's Meeting in Toronto, June 1995 in the aerogel project of IEA SHCP Task 18......The report summarizes the work which has been carried out since the 7th Expert's Meeting in Toronto, June 1995 in the aerogel project of IEA SHCP Task 18...

  10. Development of aerogel Cherenkov counters for KEDR detector

    International Nuclear Information System (INIS)

    Onuchin, A.P.; Shamov, A.G.; Vorobiov, A.I.; Danilyuk, A.F.; Gorodetskaya, T.A.; Kunznetsov, V.L.

    1990-01-01

    A threshold Cherenkov counters were proposed for particle identification in KEDR detector for B-mesons study. The counters are based on silica aerogel and phototubes, which can work in high magnetic field. Counters have a compact design and nearly 4π acceptance. In this paper design of counters is described. Tests of phototubes and Cherenkov counter prototype are presented

  11. Synthesis and application of in-situ molecularly imprinted silica monolithic in pipette-tip solid-phase microextraction for the separation and determination of gallic acid in orange juice samples.

    Science.gov (United States)

    Arabi, Maryam; Ghaedi, Mehrorang; Ostovan, Abbas

    2017-03-24

    A novel strategy was presented for the synthesis and application of functionalized silica monolithic as artificial receptor of gallic acid at micro-pipette tip. A sol-gel process was used to prepare the sorbent. In this in-situ polymerization reaction, tetraethyl orthosilicate (TEOS), 3-aminopropyl trimethoxysilane (APTMS), gallic acid and thiourea were used, respectively, as cross-linker, functionalized monomer, template and precursor to make crack-free and non-fragile structure. Such durable and inexpensive in-situ monolithic was successfully employed as useful tool for highly efficient extraction of gallic acid from orange juice samples. The effective parameters in extraction recovery were investigated and optimum conditions were obtained using experimental design methodology. Applying HPLC-UV for separation quantification at optimal conditions, the gallic acid was efficiently extracted without significant matrix interference. Good linearity for gallic acid in the range of 0.02-5.0mgL -1 with correlation coefficients of R 2 >0.999 revealed well applicability of the method for trace analysis. Copyright © 2017. Published by Elsevier B.V.

  12. Monolithic spectrometer

    Science.gov (United States)

    Rajic, Slobodan; Egert, Charles M.; Kahl, William K.; Snyder, Jr., William B.; Evans, III, Boyd M.; Marlar, Troy A.; Cunningham, Joseph P.

    1998-01-01

    A monolithic spectrometer is disclosed for use in spectroscopy. The spectrometer is a single body of translucent material with positioned surfaces for the transmission, reflection and spectral analysis of light rays.

  13. Monolithic multinozzle emitters for nanoelectrospray mass spectrometry

    Science.gov (United States)

    Wang, Daojing [Daly City, CA; Yang, Peidong [Kensington, CA; Kim, Woong [Seoul, KR; Fan, Rong [Pasadena, CA

    2011-09-20

    Novel and significantly simplified procedures for fabrication of fully integrated nanoelectrospray emitters have been described. For nanofabricated monolithic multinozzle emitters (NM.sup.2 emitters), a bottom up approach using silicon nanowires on a silicon sliver is used. For microfabricated monolithic multinozzle emitters (M.sup.3 emitters), a top down approach using MEMS techniques on silicon wafers is used. The emitters have performance comparable to that of commercially-available silica capillary emitters for nanoelectrospray mass spectrometry.

  14. Development and evaluation of aerogel-filled BMI sandwich panels for thermal barrier applications

    OpenAIRE

    A. Dineshkumar; Abdullah A. Sheikh; Zhao Yong; Sunil C. Joshi

    2016-01-01

    This study details a fabrication methodology envisaged to manufacture Glass/BMI honeycomb core aerogel-filled sandwich panels. Silica aerogel granules are used as core fillers to provide thermal insulation properties with little weight increase. Experimental heat transfer studies are conducted on these panels to study the temperature distribution between their two surfaces. Numerical studies are also carried out to validate the results. Despite exhibiting good thermal shielding capabilities, ...

  15. Pore Structure and Mechanical Properties of Poly(methylsilsesquioxane) Aerogels

    Energy Technology Data Exchange (ETDEWEB)

    Kanamori, K; Hayase, G; Nakanishi, K; Hanada, T, E-mail: kanamori@kuchem.kyoto-u.ac.jp [Department of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa, Sakyo-ku, Kyoto 606-8502 (Japan)

    2011-10-29

    Organic-inorganic hybrid aerogels have been prepared by an acid/base two-step sol-gel reaction utilizing urea and surfactant. Polycondensation of methyltrimethoxysilane (MTMS) is promoted by the hydrolysis of urea, and the hydrophobicity of condensates is weakened by adequate cationic or nonionic surfactant. Aerogels with low bulk density ({approx} 0.13 g cm{sup -3}) and high visible light transmittance ({approx} 89 % at 550 nm through 10 mm-thick sample) are obtained. The resultant hybrid aerogels show high deformability and subsequent spring-back upon uniaxial compression owing to the lower cross-linking density and residual silanol density compared to silica, and to the presence of hydrophobic methyl groups in the network. Additional aging of as-prepared wet gels in water improved mechanical properties in the case of cationic surfactant system.

  16. Production of aerogel double glazed units and measurement of key performance parameters

    DEFF Research Database (Denmark)

    Duer, Karsten; Svendsen, Sv Aa Højgaard

    1997-01-01

    By providing at the same time thermal insulation and transparency the silica aerogel is a very attractive material for the purpose of improving the thermal performance of windows. Nevertheless a lot of problems have to be solved on the way from concept to the developed product. The B1 Aerogels...... project in IEA SHCP Task 18 deals with some of these problems.This report summarizes the work that has been carried out on the subject of characterizing the optical and thermal performance of prototypical evacuated aerogel glazings produced in Denmark by means of a new edge seal technique with very small...

  17. Hard macrocellular silica Si(HIPE) foams templating micro/macroporous carbonaceous monoliths: applications as lithium ion battery negative electrodes and electrochemical capacitors

    Energy Technology Data Exchange (ETDEWEB)

    Brun, Nicolas [Universite de Bordeaux, Centre de Recherche Paul Pascal, UPR 8641-CNRS, Pessac (France); Universite de Bordeaux, Institut des Sciences Moleculaires CNRS-UMR, Talence (France); Prabaharan, Savari R.S. [Laboratoire de Reactivite et Chimie des Solides, UMR CNRS 6007 Universite de Picardie Jules Verne, Amiens (France); Faculty of Engineering and Computer Science, University of Nottingham, Malaysia Campus Jalan Broga, Semenyih, Selangor (Malaysia); Morcrette, Mathieu [Laboratoire de Reactivite et Chimie des Solides, UMR CNRS 6007 Universite de Picardie Jules Verne, Amiens (France); Sanchez, Clement [Laboratoire de Chimie de la Matiere Condensee de Paris, Universite Paris 06, Paris (France); Pecastaings, Gilles; Soum, Alain [Laboratoire de Chimie des Polymeres Organiques UMR 5629 CNRS, Universite Bordeaux-1, Pessac (France); Derre, Alain; Backov, Renal [Universite de Bordeaux, Centre de Recherche Paul Pascal, UPR 8641-CNRS, Pessac (France); Deleuze, Herve; Birot, Marc [Universite de Bordeaux, Institut des Sciences Moleculaires CNRS-UMR, Talence (France)

    2009-10-09

    By using Si(HIPEs) as hard, exotemplating matrices, interconnected macro-/microporous carbon monolith-type materials with a surface area of around 600 m{sup 2} g{sup -1} are synthesized and shaped. The carbonaceous foams exhibit a conductivity of 20 S cm{sup -1}, addressed with excellent mechanical properties (Young's modulus of 0.2 GPa and toughness of 13 J g{sup -1}, when the carbon core is optimized). The above-mentioned specificities, combined with the fact that the external shape and size can be easily designed on demand, are of primary importance for applications. The functionality of these carbonaceous monoliths is tested as both an electrochemical capacitor and a lithium ion negative electrode. The electrochemical capacitors' voltage-current profiles exhibit a non-ideal rectangular response, confirming the double-layer behavior of the carbon studied, while the charge-discharge current profile of the electric double-layer capacitor is directly proportional to the scan where the current response during charge and discharge exhibits high reversibility. When acting as a lithium ion negative electrode, after initial irreversibility, a good cyclability is obtained, associated with a stable capacity of 200 mA h g{sup -1} during the first 50 cycles at a reasonable current density (C/10). (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  18. High-performance liquid chromatography analysis of polyacetylenes and polyenes in Echinacea pallida by using a monolithic reversed-phase silica column.

    Science.gov (United States)

    Pellati, Federica; Calò, Samuele; Benvenuti, Stefania

    2007-05-11

    In this study, a RP-HPLC method for the analysis of polyacetylenes and polyenes in Echinacea pallida roots and phytopharmaceuticals was developed. The reference compounds used for quantification were isolated from the plant material and their structures were determined on the basis of the analysis of UV, IR, NMR and MS data. The complete structure elucidation of three compounds, namely 8-hydroxy-tetradec-(9E)-ene-11,13-diyn-2-one (1), tetradec-(8Z)-ene-11,13-diyn-2-one (6) and pentadec-(8Z)-en-2-one (9) is described. In the analysis of the n-hexane extracts of E. pallida roots, the comparison between conventional and monolithic columns showed that the elution order in both cases is identical and the selectivity is equivalent. However, the retention times achieved by the monolithic column are shorter, resulting in a faster separation (20 min). Therefore, the analyses were carried out on a Chromolith Performance RP-18e (100 mm x 4.6 mm i.d.), with a gradient mobile phase composed by H(2)O and ACN at the flow rate of 2 mL/min. The column was thermostatted at 20 degrees C. The photodiode array detector monitored the eluent at 210 nm. The validation procedure confirmed that this technique affords reliable analysis of these components and is appropriate for the quality control of complex matrices, such as E. pallida roots and phytopharmaceuticals.

  19. Aerogels Insulate Against Extreme Temperatures

    Science.gov (United States)

    2010-01-01

    In 1992, NASA started to pursue the development of aerogel for cryogenic insulation. Kennedy Space Center awarded Small Business Innovation Research (SBIR) contracts to Aspen Systems Inc., of Marlborough, Massachusetts, that resulted in a new manufacturing process and a new flexible, durable, easy-to-use form of aerogel. Aspen Systems formed Aspen Aerogels Inc., in Northborough, Massachusetts, to market the product, and by 2009, the company had become the leading provider of aerogel in the United States, producing nearly 20 million square feet per year. With an array of commercial applications, the NASA-derived aerogel has most recently been applied to protect and insulate people s hands and feet.

  20. 21 CFR 182.1711 - Silica aerogel.

    Science.gov (United States)

    2010-04-01

    ... CONSUMPTION (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Multiple Purpose GRAS Food Substances § 182... explanation. This substance is generally recognized as safe when used as a component of an anti-foaming agent...

  1. Band broadening in fast gradient high-performance liquid chromatography: application to the second generation of 4.6 mm I.D. silica monolithic columns.

    Science.gov (United States)

    Gritti, Fabrice; Guiochon, Georges

    2012-05-18

    The sources of band broadening in fast gradient elution chromatography include the contributions of the tubings placed upstream the column, the isocratic migration of the sample that takes place in the column until the moment when the front of the gradient catches up with it, dispersion and mass transfer resistance during band migration under gradient elution to the column outlet, and dispersion in the tubings downstream the column to the detector. The measurements of all these contributions is meticulously described, analyzed, and applied to assess the kinetic performance of monolithic columns of the second generation (KGaA Merck) in gradient elution, at the highest possible speed at which they can be operated (t(0)=25s at P=200 bar). These results are compared to those provided by several 4.6mm × 100mm columns packed with sub-3 μm core-shell particles (Kinetex, Phenomenex and Halo, Advanced Material Technologies) and by a 2.1mm × 100mm column packed with fully porous 1.7 μm BEH particles (Waters). A RPLC checkout sample (Agilent) containing nine alkanophenones (molecular weights between 120 and 204 g/mol) was used for this purpose. The mobile phase was a mixture of acetonitrile and water and the instrument, an optimized version of the 1290 Infinity HPLC system (Agilent). The results show that the overall peak capacity provided by this second generation of monolithic columns is nearly 30% smaller than that provided by commercial columns packed with sub-3 μm core-shell particles and 20% smaller than that provided by a narrow-bore column packed with sub-2 μm fully porous particles. After isolating the sole band broadening contribution due to the gradient migration of the analytes along the columns, the BEH column proved to provide the highest resolution power (apparent average plate height, of 2 μm), followed by the 2.6 μm Kinetex particles (3.0 μm), the Halo particles (3.2 μm), and the second generation of 4.6mm I.D. monolithic columns (6.5 μm). This

  2. Mechanically Strong, Polymer Cross-linked Aerogels (X-Aerogels)

    Science.gov (United States)

    Leventis, Nicholas

    2006-01-01

    Aerogels comprise a class of low-density, high porous solid objects consisting of dimensionally quasi-stable self-supported three-dimensional assemblies of nanoparticles. Aerogels are pursued because of properties above and beyond those of the individual nanoparticles, including low thermal conductivity, low dielectric constant and high acoustic impedance. Possible applications include thermal and vibration insulation, dielectrics for fast electronics, and hosting of functional guests for a wide variety of optical, chemical and electronic applications. Aerogels, however, are extremely fragile materials, hence they have found only limited application in some very specialized environments, for example as Cerenkov radiation detectors in certain types of nuclear reactors, aboard spacecraft as collectors of hypervelocity particles (refer to NASA's Stardust program) and as thermal insulators on planetary vehicles on Mars (refer to Sojourner Rover in 1997 and Spirit and Opportunity in 2004). Along these lines, the X-Aerogel is a new NASA-developed strong lightweight material that has resolved the fragility problem of traditional (native) aerogels. X-Aerogels are made by applying a conformal polymer coating on the surfaces of the skeletal nanoparticles of native aerogels (see Scanning Electron Micrographs). Since the relative amounts of the polymeric crosslinker and the backbone are comparable, X-Aerogels can be viewed either as aerogels modified by the templated accumulation of polymer on the skeletal nanoparticles, or as nanoporous polymers made by remplated casting of polymer on a nanostructured framework. The most striking feature of X-Aerogels is that for a nominal 3-fold increase in density (still a ultralighweight material), the mechanical strength can be up to 300 times higher than the strength of the underlying native aerogel. Thus, X-Aerogels combine a multiple of the specific compressive strength of steel, with the the thermal conductivity of styrofoam. X-Aerogels

  3. X-Aerogels for Structural Components and High Temperature Applications

    Science.gov (United States)

    2005-01-01

    Future NASA missions and space explorations rely on the use of materials that are strong ultra lightweight and able to withstand extreme temperatures. Aerogels are low density (0.01-0.5 g/cu cm) high porosity materials that contain a glass like structure formed through standard sol-gel chemistry. As a result of these structural properties, aerogels are excellent thermal insulators and are able to withstand temperatures in excess of l,000 C. The open structure of aerogels, however, renders these materials extremely fragile (fracturing at stress forces less than 0.5 N/sq cm). The goal of NASA Glenn Research Center is to increase the strength of these materials by templating polymers and metals onto the surface of an aerogel network facilitating the use of this material for practical applications such as structural components of space vehicles used in exploration. The work this past year focused on two areas; (1) the research and development of new templated aerogels materials and (2) process development for future manufacturing of structural components. Research and development occurred on the production and characterization of new templating materials onto the standard silica aerogel. Materials examined included polymers such as polyimides, fluorinated isocyanates and epoxies, and, metals such as silver, gold and platinum. The final properties indicated that the density of the material formed using an isocyanate is around 0.50 g/cc with a strength greater than that of steel and has low thermal conductivity. The process used to construct these materials is extremely time consuming and labor intensive. One aspect of the project involved investigating the feasibility of shortening the process time by preparing the aerogels in the templating solvent. Traditionally the polymerization used THF as the solvent and after several washes to remove any residual monomers and water, the solvent around the aerogels was changed to acetonitrile for the templating step. This process

  4. SINTESIS SILIKA AEROGEL DENGAN BAHAN DASAR ABU BAGASSE

    Directory of Open Access Journals (Sweden)

    Nazriati Nazriati

    2012-05-01

    Full Text Available SYNTHESIS OF SILICA AEROGEL FROM BAGASSE ASH. Synthesis of silica aerogel from bagasse ash was done by alkaline extraction followed by sol-gel. Bagasse ash was extracted with NaOH at its boiling temperature for one hour with continue stirring, to produce sodium silicate. Subsequently, sodium silicate was pass through ionic exchanger resin, to produces silicic acid (SA. Silicic acid solution was then added with TMCS and HMDS as surface modifier agent. In order to form gel pH must be adjusted to final pH of 8-9 by addition of NH4OH solution. The resulting gel then was aged and dried at ambient pressure and at a certain time and temperature. Characterization of products was done by measuring its pore volume, surface area, and hydrophobisity (contact angle. TMCS serves as water expeller from the pores and subsequently surface was modified by HMDS and TMCS. HMDS content will linearly increase surface area, pore volume, and the contact angle of the resulting silica aerogel. Characteristics of silica aerogel was generated by varying the composition of the SA:TMCS:HMDS resulting has a surface area of 50-488 m2/g, pore volume from 0.2 to 0.9 m3 /g, the contact angle of 48-119 and pore diameter ranging from 5.7-22.56 nm. Based on the resulting pore diameter, the synthesized of silica aerogel categorized as mesoporous.      Abstrak   Sintesis silika aerogel dari bahan dasar abu bagasse dilakukan dengan ekstraksi basa dan diikuti dengan sol-gel. Abu bagasse diekstrak dengan NaOH pada suhu didihnya sambil diaduk selama satu jam, menghasilkan sodium silikat. Selanjutnya, sodium silikat dilewatkan resin penukar ion, menghasilkan asam silicic (SA. Larutan asam silicic kemudian ditambahkan trimethy­l­chlorosilane (TMCS dan hexamethyldisilazane (HMDS sebagai agen pemodifikasi permukaan. Untuk terjadinya gel pH diatur hingga mencapai 8-9 dengan penambahan larutan NH4OH. Gel yang dihasilkan kemudian di-aging dan dikeringkan pada tekanan ambien pada suhu dan

  5. Preparation and Characterization of a Calcium Carbonate Aerogel

    Directory of Open Access Journals (Sweden)

    Johann Plank

    2009-01-01

    Full Text Available We report on a facile method for the preparation of a calcium carbonate aerogel consisting of aggregated secondary vaterite particles with an approximate average diameter of 50 nm. It was synthesized via a sol-gel process by reacting calcium oxide with carbon dioxide in methanol and subsequent supercritical drying of the alcogel with carbon dioxide. The resulting monolith was opaque, brittle and had overall dimensions of 6×2×1 cm. It was characterized by X-ray powder diffraction, nitrogen adsorption method (BET, and scanning electron microscopy.

  6. Monolithic ceramics

    Science.gov (United States)

    Herbell, Thomas P.; Sanders, William A.

    1992-01-01

    A development history and current development status evaluation are presented for SiC and Si3N4 monolithic ceramics. In the absence of widely sought improvements in these materials' toughness, and associated reliability in structural applications, uses will remain restricted to components in noncritical, nonman-rated aerospace applications such as cruise missile and drone gas turbine engine components. In such high temperature engine-section components, projected costs lie below those associated with superalloy-based short-life/expendable engines. Advancements are required in processing technology for the sake of fewer and smaller microstructural flaws.

  7. Aerogel-Based Insulation for High-Temperature Industrial Processes

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Owen Evans

    2011-10-13

    Under this program, Aspen Aerogels has developed an industrial insulation called Pyrogel HT, which is 4-5 times more thermally efficient than current non-aerogel technology. Derived from nanoporous silica aerogels, Pyrogel HT was specifically developed to address a high temperature capability gap not currently met with Aspen Aerogels{trademark} flagship product, Pyrogel XT. Pyrogel XT, which was originally developed on a separate DOE contract (DE-FG36-06GO16056), was primarily optimized for use in industrial steam processing systems, where application temperatures typically do not exceed 400 C. At the time, further improvements in thermal performance above 400 C could not be reasonably achieved for Pyrogel XT without significantly affecting other key material properties using the current technology. Cumulative sales of Pyrogel HT into domestic power plants should reach $125MM through 2030, eventually reaching about 10% of the total insulation market share in that space. Global energy savings would be expected to scale similarly. Over the same period, these sales would reduce domestic energy consumption by more than 65 TBtu. Upon branching out into all industrial processes in the 400 C-650 C regime, Pyrogel HT would reach annual sales levels of $150MM, with two-thirds of that being exported.

  8. Hierarchically Porous Carbon Monoliths with High Surface Area from Bridged Poly(silsesquioxane) without Thermal Activation Process

    Energy Technology Data Exchange (ETDEWEB)

    Hasegawa, G; Kanamori, K; Nakanishi, K; Hanada, T, E-mail: h_george@kuchem.kyoto-u.ac.jp [Department of Chemistry, Graduate School of Science, Kyoto University Kitashirakawa, Sakyo-ku, Kyoto (Japan)

    2011-10-29

    Hierarchically porous carbon monoliths with high specific surface areas have been fabricated by removing nano-sized silica phase from carbon/silica composites pyrolyzed from bridged poly(silsesquioxane). This activation method improves the homogeneity between inner and outer parts of the monoliths compared to the conventional thermal activation methods.

  9. Hierarchical Nafion enhanced carbon aerogels for sensing applications.

    Science.gov (United States)

    Weng, Bo; Ding, Ailing; Liu, Yuqing; Diao, Jianglin; Razal, Joselito; Lau, King Tong; Shepherd, Roderick; Li, Changming; Chen, Jun

    2016-02-14

    This work describes the fabrication of hierarchical 3D Nafion enhanced carbon aerogels (NECAGs) for sensing applications via a fast freeze drying method. Graphene oxide, multiwalled carbon nanotubes and Nafion were mixed and extruded into liquid nitrogen followed by the removal of ice crystals by freeze drying. The addition of Nafion enhanced the mechanical strength of NECAGs and effective control of the cellular morphology and pore size was achieved. The resultant NECAGs demonstrated high strength, low density, and high specific surface area and can achieve a modulus of 20 kPa, an electrical conductivity of 140 S m(-1), and a specific capacity of 136.8 F g(-1) after reduction. Therefore, NECAG monoliths performed well as a gas sensor and as a biosensor with high sensitivity and selectivity. The remarkable sensitivity of 8.52 × 10(3)μA mM(-1) cm(-2) was obtained in dopamine (DA) detection, which is two orders of magnitude better than the literature reported values using graphene aerogel electrodes made from a porous Ni template. These outstanding properties make the NECAG a promising electrode candidate for a wide range of applications. Further in-depth investigations are being undertaken to probe the structure-property relationship of NECAG monoliths prepared under various conditions.

  10. Increased thermal conductivity monolithic zeolite structures

    Science.gov (United States)

    Klett, James; Klett, Lynn; Kaufman, Jonathan

    2008-11-25

    A monolith comprises a zeolite, a thermally conductive carbon, and a binder. The zeolite is included in the form of beads, pellets, powders and mixtures thereof. The thermally conductive carbon can be carbon nano-fibers, diamond or graphite which provide thermal conductivities in excess of about 100 W/mK to more than 1,000 W/mK. A method of preparing a zeolite monolith includes the steps of mixing a zeolite dispersion in an aqueous colloidal silica binder with a dispersion of carbon nano-fibers in water followed by dehydration and curing of the binder is given.

  11. Hybrid aerogels and bioactive aerogels under uniaxial compression: an in situ SAXS study

    Directory of Open Access Journals (Sweden)

    Esquivias, L.

    2010-12-01

    Full Text Available The complex structure of hybrid organic/inorganic aerogels is composed by an inorganic phase covalently bonded to an organic chain forming a copolymer. Conventional hybrid aerogels were studied as well as bioactive hybrid aerogels, that is, aerogels with a calcium active phase added. In this work, the relationship between mechanical response and nanostructure was studied, using a specifically designed sample-holder for in situ uniaxial compression obtaining at the same time the small-angle X-ray pattern from synchrotron radiation (SAXS. Structural elements can be described as a particulated silica core surrounded by the organic chains. These chains are compressed on the direction parallel to the load, and a relationship between macroscopic uniaxial compression and particle and pore deformations can be established.

    La compleja estructura de los aerogeles híbridos orgánico/inorgánicos está compuesta por una fase inorgánica de sílice, unida mediante enlaces covalentes a una red de cadenas orgánicas. Se han estudiado composites híbridos convencionales y bioactivos, esto es, con una fase activa de calcio añadida. En este trabajo se ha investigado la relación entre la respuesta mecánica y la nanoestructura, con ayuda de un portamuestras específicamente diseñado para el estudio in situ de muestras bajo compresión uniaxial, a la vez que se obtiene el espectro de rayos-X a bajo-ángulo de radiación sincrotrón (SAXS. Los elementos estructurales se pueden describir como núcleos particulados de sílice rodeados de las cadenas orgánicas. Estas, se comprimen en la dirección paralela a la carga pudiéndose establecer una relación entre la compresión uniaxial macroscópica y la deformación de las partículas y poros que forman la estructura.

  12. Aerogels: II. Applications in catalysis

    Directory of Open Access Journals (Sweden)

    Orlović Aleksandar M.

    2002-01-01

    Full Text Available Sol-gel synthesis, and the resulting materials (xerogels and aerogels are finding increasing application in the synthesis of catalysts, due to their unique characteristics. The most important features of the sol-gel process are: the ability to achieve homogeneity at the molecular level, the introduction of several species in only one step and the ability to stabilize metastable phases. The supercritical drying process produces aerogels with structural features quite different to conventional materials. Some of these characteristics of aerogels can make them very effective catalysts.

  13. Flexible Polyimide Aerogel Cross-linked by Poly(maleic Anhydride-alt-alkylene)

    Science.gov (United States)

    Guo, Haiquan; Meador, Mary Ann B.; Wilkewitz, Brittany Marie

    2014-01-01

    Aerogels are potential materials for aerospace applications due to their lower thermal conductivity, lighter weight, and low dielectric constant. However, silica aerogels are restricted due to their inherent fragility, hygroscopic nature, and poor mechanical properties, especially in extreme aerospace environments. In order to fit the needs of aerospace applications, developing new thermal insulation materials that are flexible, and moisture resistant is needed. To this end, we fabricated a series of polyimide aerogels crosslinked with different poly(maleic anhydride-alt-alkylene)s as seen in Scheme 1. The polyimide oligomers were made with 3,3,4,4-biphenyltetracarboxylic dianhydride (BPDA), and different diamines or diamine combinations. The resulting aerogels have low density (0.06 gcm3 to 0.16 gcm3) and high surface area (240-440 m2g). The effect of the different backbone structures on density, shrinkage, porosity, surface area, mechanical properties, moisture resistance and thermal properties will be discussed. These novel polyalkylene-imide aerogels may be potential candidates for applications such as space suit insulation for planetary surface missions, insulation for inflatable structures for habitats, inflatable aerodynamic decelerators for entry, descent and landing (EDL) operations, and cryotank insulation for advance space propulsion systems. Scheme 1. Network of polyimide aerogels crosslinked with deifferent poly(maleic anhydride).

  14. Thermal conductivity of aerogel blanket insulation under cryogenic-vacuum conditions in different gas environments

    Science.gov (United States)

    E Fesmire, J.; Ancipink, J. B.; Swanger, A. M.; White, S.; Yarbrough, D.

    2017-12-01

    Thermal conductivity of low-density materials in thermal insulation systems varies dramatically with the environment: cold vacuum pressure, residual gas composition, and boundary temperatures. Using a reference material of aerogel composite blanket (reinforcement fibers surrounded by silica aerogel), an experimental basis for the physical heat transmission model of aerogel composites and other low-density, porous materials is suggested. Cryogenic-vacuum testing between the boundary temperatures of 78 K and 293 K is performed using a one meter cylindrical, absolute heat flow calorimeter with an aerogel blanket specimen exposed to different gas environments of nitrogen, helium, argon, or CO2. Cold vacuum pressures include the full range from 1×10-5 torr to 760 torr. The soft vacuum region, from about 0.1 torr to 10 torr, is complex and difficult to model because all modes of heat transfer - solid conduction, radiation, gas conduction, and convection - are significant contributors to the total heat flow. Therefore, the soft vacuum tests are emphasized for both heat transfer analysis and practical thermal data. Results for the aerogel composite blanket are analyzed and compared to data for its component materials. With the new thermal conductivity data, future applications of aerogel-based insulation systems are also surveyed. These include Mars exploration and surface systems in the 5 torr CO2 environment, field joints for vacuum-jacketed cryogenic piping systems, common bulkhead panels for cryogenic tanks on space launch vehicles, and liquid hydrogen cryofuel systems with helium purged conduits or enclosures.

  15. Highly Insulating and Light Transmitting Aerogel Glazing for Super Insulating Windows (HILIT+)

    DEFF Research Database (Denmark)

    Jensen, Karsten Ingerslev

    2005-01-01

    The first main objective deals with “aerogel process optimisation”. The general goal was to demonstrate that the elaboration process, developed during the recent HILIT project, permitted to obtain a significant amount of light transmitting, insulating and transparent 15-20 mm monolithic and crack...... material. Due to the low density, the acoustic impedance of aerogel could help boost the efficiency of piezoelectric transducers. • Waste encapsulation, spacers for vacuum insulation panels, membranes, etc.......-free nano-structured aerogel materials through a reasonably fast and reproducible process. The applicative part of this project aimed at elaborating, studying and optimising “state-of-the-art” (0.5 W/m2 K) aerogel glazings for windows. An important issue was the risk of outside condensation and rime and its....... No other known glazing exhibits such an excellent combination of solar transmittance and heat loss coefficient. The annual energy savings compared to triple low energy glazing is in the range of 10 – 20% depending on type of building. Beside the application in glazing production the HILIT+ aerogel material...

  16. Super-hydrophobic fluorine containing aerogels

    Science.gov (United States)

    Coronado, Paul R [Livermore, CA; Poco, John F [Livermore, CA; Hrubesh, Lawrence W [Pleasanton, CA

    2007-05-01

    An aerogel material with surfaces containing fluorine atoms which exhibits exceptional hydrophobicity, or the ability to repel liquid water. Hydrophobic aerogels are efficient absorbers of solvents from water. Solvents miscible with water are separated from it because the solvents are more volatile than water and they enter the porous aerogel as a vapor across the liquid water/solid interface. Solvents that are immisicble with water are separated from it by selectively wetting the aerogel. The hydrophobic property is achieved by formulating the aerogel using fluorine containing molecules either directly by addition in the sol-gel process, or by treating a standard dried aerogel using the vapor of fluorine containing molecules.

  17. Development of Innovative Aerogel Based Plasters: Preliminary Thermal and Acoustic Performance Evaluation

    Directory of Open Access Journals (Sweden)

    Cinzia Buratti

    2014-09-01

    Full Text Available The thermal and acoustic properties of innovative insulating systems used as building coatings were investigated: Granular silica aerogel was mixed with natural plaster in different percentages. This coating solution is transpiring and insulating, thanks to the use of a natural lime coat and aerogel, a highly porous light material with very low thermal conductivity. The thermal conductivity of the proposed solution was evaluated by means of a Heat Flow meter apparatus (EN ISO 12667, considering different percentages of aerogel. The natural plaster without aerogel has a thermal conductivity of about 0.50 W/m K; considering a percentage of granular aerogel of about 90% in volume, the thermal conductivity of the insulating natural coating falls to 0.050 W/m K. Increasing the percentage of granular aerogel, a value of about 0.018–0.020 W/m K can be reached. The acoustic properties were also evaluated in terms of the acoustic absorption coefficient, measured by means of a Kundt’s Tube (ISO 10534-2. Two samples composed by a plasterboard support, an insulation plaster with aerogel (thicknesses 10 mm and 30 mm respectively and a final coat were assembled. The results showed that the absorption coefficient strongly depends on the final coat, so the aerogel-based plaster layer moderately influences the final value. The application of this innovative solution can be a useful tool for new buildings, but also for the refurbishment of existing ones. This material is in development: until now, the best value of the thermal conductivity obtained from manufacturers is about 0.015 W/m K.

  18. Influence of Chemical Conditions on the Nanoporous Structure of Silicate Aerogels

    Directory of Open Access Journals (Sweden)

    Katalin Sinkó

    2010-01-01

    Full Text Available Silica or various silicate aerogels can be characterized by highly porous, open cell, low density structures. The synthesis parameters influence the three-dimensional porous structures by modifying the kinetics and mechanism of hydrolysis and condensation processes. Numerous investigations have shown that the structure of porous materials can be tailored by variations in synthesis conditions (e.g., the type of precursors, catalyst, and surfactants; the ratio of water/precursor; the concentrations; the medium pH; and the solvent. The objectives of this review are to summarize and elucidate the effects of chemical conditions on the nanoporous structure of sol-gel derived silicate aerogels.

  19. Densification and Strengthening of Aerogels by Sintering Heat Treatments or Plastic Compression

    Directory of Open Access Journals (Sweden)

    Thierry Woignier

    2018-01-01

    Full Text Available Due to their broad range of porosity, aerogels are suited to various applications. The advantages of a broad range of porosity are used directly, for example, in thermal and acoustic insulation, as materials for space applications or in catalysers. However, an overly high pore volume can also be a drawback, for example, in a glass precursor and host matrix. Fortunately, aerogel porosity can be tailored using sintering or isostatic compression. Sets of silica aerogels—sintered and compressed aerogels—have been studied with the objective of comparing these different densification mechanisms. We focus on the mechanical changes during the two processes of densification.

  20. Testbeam results on particle identification with aerogel used as RICH radiator

    CERN Document Server

    Alemi, M; Braem, André; Calvi, M; Chesi, Enrico Guido; Joram, C; Liko, D; Matteuzzi, C; Negri, P; Neufeld, N; Paganoni, M; Séguinot, Jacques; Voillat, D; Weilhammer, Peter; Ypsilantis, Thomas

    2000-01-01

    We present the results obtained by exposing samples of silica aerogel of different thickness and optical properties to pion and proton beams with momenta between 6 and 10 GeV/c in the PS testbeam facility at CERN. Two large diameter pad-HPDs with 2048 channels, produced at CERN, have been used as photon detectors. Separate Cherenkov rings produced by the different particles were reconstructed obtaining pion /proton separation on the whole considered momentum range. The number of photoelectrons was measured as a function of aerogel thickness and was found in agreement with Monte Carlo expectations. 5 Refs.

  1. Test-beam results on particle identification with aerogel used as RICH radiator

    CERN Document Server

    Alemi, M; Braem, André; Calvi, M; Chesi, Enrico Guido; Joram, C; Liko, D; Matteuzzi, C; Negri, P; Neufeld, N; Paganoni, M; Séguinot, Jacques; Voillat, D; Weilhammer, Peter; Ypsilantis, Thomas

    2001-01-01

    We present the results obtained by exposing samples of silica aerogel of different thickness and optical properties to pion and proton beams with momenta between 6 and 10 GeV/c in the PS testbeam facility at CERN. Two large diameter pad hybrid photodiodes with 2048 channels, produced at CERN, have been used as photon detectors. Separate Cherenkov rings produced by the different particles were reconstructed obtaining pion/proton separation over the whole momentum range. The number of photoelectrons was measured as a function of aerogel thickness and was found to be in agreement with Monte Carlo expectations. (5 refs).

  2. Aerogels of 1D Coordination Polymers: From a Non-Porous Metal-Organic Crystal Structure to a Highly Porous Material

    Directory of Open Access Journals (Sweden)

    Adrián Angulo-Ibáñez

    2016-01-01

    Full Text Available The processing of an originally non-porous 1D coordination polymer as monolithic gel, xerogel and aerogel is reported as an alternative method to obtain novel metal-organic porous materials, conceptually different to conventional crystalline porous coordination polymer (PCPs or metal-organic frameworks (MOFs. Although the work herein reported is focused upon a particular kind of coordination polymer ([M(μ-ox(4-apy2]n, M: Co(II, Ni(II, the results are of interest in the field of porous materials and of MOFs, as the employed synthetic approach implies that any coordination polymer could be processable as a mesoporous material. The polymerization conditions were fixed to obtain stiff gels at the synthesis stage. Gels were dried at ambient pressure and at supercritical conditions to render well shaped monolithic xerogels and aerogels, respectively. The monolithic shape of the synthesis product is another remarkable result, as it does not require a post-processing or the use of additives or binders. The aerogels of the 1D coordination polymers are featured by exhibiting high pore volumes and diameters ranging in the mesoporous/macroporous regions which endow to these materials the ability to deal with large-sized molecules. The aerogel monoliths present markedly low densities (0.082–0.311 g·cm−3, an aspect of interest for applications that persecute light materials.

  3. High-density aerogels with ultralow sound velocity: Microstructure is a key parameter determining the sound velocity

    Science.gov (United States)

    Du, Ai; Zhou, Bin; Shen, Yang; Yu, Qiujie; Shen, Jun

    2014-03-01

    Aerogels are more and more regarded as a new state of matter nowadays because of its diverse chemical compositions and unique properties which could fill the gap between condensed matter and gas-state matter. Among the properties, the ultralow sound velocity in the aerogels (lower than that in the air) is of great interests. J. Fricke's group studied many kinds of aerogels with different compositions and found that the sound velocity was mainly influenced by the density. Thus they obtained the lowest sound velocity result (~ 100 m/s) in a low-density silica aerogel medium (~ 0.05 g.cm-3) . Here we studied the acoustical properties of the aerogels with the similar high density (about 1.3 g.cm-3) but different skeleton structure (nano-, micro- or nano-/micro- structured) by adjusting the phase separation mode. The sound velocities of all the aerogels are below 300 m.s-1, among which micro-/nano- structured aerogel exhibits lowest longitudinal wave velocity (below 80 m.s-1) . Further structural studies indicated that the hierarchical arrangement of microstructure is the key parameter determining the sound velocity besides the density. This work was supported by the National Natural Science Foundation of China (51102184, 51172163), National High-tech R&D Program of China (863 Program, 2013AA031801) and National Science and Technology Support Program (2013BAJ01B01).

  4. Aerogel Track Morphology: Measurement, Three Dimensional Reconstruction and Particle Location using Confocal Laser Scanning Microscopy

    Science.gov (United States)

    Kearsley, A. T.; Ball, A. D.; Wozniakiewicz, P. A.; Graham, G. A.; Burchell, M. J.; Cole, M. J.; Horz, F.; See, T. H.

    2007-01-01

    The Stardust spacecraft returned the first undoubted samples of cometary dust, with many grains embedded in the silica aerogel collector . Although many tracks contain one or more large terminal particles of a wide range of mineral compositions , there is also abundant material along the track walls. To help interpret the full particle size, structure and mass, both experimental simulation of impact by shots and numerical modeling of the impact process have been attempted. However, all approaches require accurate and precise measurement of impact track size parameters such as length, width and volume of specific portions. To make such measurements is not easy, especially if extensive aerogel fracturing and discoloration has occurred. In this paper we describe the application and limitations of laser confocal imagery for determination of aerogel track parameters, and for the location of particle remains.

  5. Diffusion Raman et luminescence dans des aerogels de silice purs ou dopes Dy

    Science.gov (United States)

    Guerri, F.; Fabre, F.; Zwick, A.; Bournett, D.

    1994-02-01

    Light scattering studies of pure and Dy doped aerogels are presented. Careful examination of Stokes and anti-Stokes spectra allow the discrimination between Raman and luminescence processes. It is shown that in pure aerogels, scattered intensity is due to Raman processes only, and the density of vibrational states does not exhibit any singularity. The fractal properties of the structure imply modifications not only in the spectral distribution of the low frequency modes (usually labelled phonons and fractons) but alsoin the high frequency one, at least up to 600 cm-1. In Dy-doped dense silica, coupling between electronic and vibronic excitations is evidenced by the presence of anti-Stokes luminescence. In Dy-doped aerogels, the enlarged Dy3+ electronic levels, strongly coupled with vibrational states give rise to emission processes traducing the response of the sample as a whole, rather than resonant Raman scattering or luminescence processes.

  6. Propiedades mecánicas de aerogeles híbridos de sílice

    Directory of Open Access Journals (Sweden)

    Piñero, M.

    2005-10-01

    Full Text Available Hybrids silica aerogels have been obtained by means the high power ultrasounds application in the precursor liquid and the drying of the wet gel under the supercritical condition of ethanol. The organic chains don’t degrade thermally and accelerate the network shrinkage process by thermal activation. The ultrasounds induce an organic chain crosslinking bonding to the porous silica clusters and avoid its cyclidation. The failure tests by uniaxial compression show an increase of the rupture modulus, passing from 8 MPa for a pure silica aerogel to 24 MPa for an aerogel with a 50 weight % of polymer content. It is also noted a continuous decrease of the Young’s modulus with the polymer content (from 100 to 56 MPa. These hybrid aerogels behave as elastomers with up to a 50% strain, showing a decrease in the relaxation viscoelastic modulus.

    Se han obtenido aerogeles híbridos de sílice orgánico-inorgánico por aplicación de ultrasonidos de alta potencia en los precursores líquidos y posterior secado del gel húmedo en condiciones supercríticas en etanol. Las cadenas orgánicas no se degradan térmicamente y aceleran el proceso de contracción de la red por activación térmica. Los ultrasonidos inducen un entrecruzamiento de cadenas orgánicas que unen los cúmulos de sílice porosa y evitan su ciclidación. Los ensayos de ruptura en compresión uniaxial indicaron un aumento del módulo de ruptura, pasando de 8 MPa para el aerogel de sílice pura hasta 24 MPa para un aerogel de 50% en peso de contenido de polímero. Se observa asimismo una disminución continua en el módulo de Young con el contenido de polímero (de 100 a 56 MPa. Estos aerogeles híbridos se comportan como elastómeros con deformaciones de hasta el 50%, mostrando una disminución del módulo de relajación viscoelástica.

  7. Polyimide Cellulose Nanocrystal Composite Aerogels

    Science.gov (United States)

    Nguyen, Baochau N.; Meador, Mary Ann; Rowan, Stuart; Cudjoe, Elvis; Sandberg, Anna

    2014-01-01

    Polyimide (PI) aerogels are highly porous solids having low density, high porosity and low thermal conductivity with good mechanical properties. They are ideal for various applications including use in antenna and insulation such as inflatable decelerators used in entry, decent and landing operations. Recently, attention has been focused on stimuli responsive materials such as cellulose nano crystals (CNCs). CNCs are environmentally friendly, bio-renewable, commonly found in plants and the dermis of sea tunicates, and potentially low cost. This study is to examine the effects of CNC on the polyimide aerogels. The CNC used in this project are extracted from mantle of a sea creature called tunicates. A series of polyimide cellulose nanocrystal composite aerogels has been fabricated having 0-13 wt of CNC. Results will be discussed.

  8. Vanadium oxide/polypyrrole aerogel nanocomposites. Technical report, 1 June 1995-31 May 1996

    Energy Technology Data Exchange (ETDEWEB)

    Dave, B.C.; Bunn, B.; Leroux, F.; Nazar, L.F.; Wong, H.P.

    1996-06-18

    Vanadium pentoxide/polypyrrole aerogel (ARG) nanocomposites were prepared by hydrolysis of VO(OC3H7)3 using pyrrole/water/acetone mixtures. Monolithic green-black gels with polypyrrole/V ratios ranging from 0.15 to 1.0 resulted from simultaneous polymerization of the pyrrole and vanadium alkoxide precursors. Supercritical drying yielded high surface (150-200 sq meters/g) aerogels, of sufficient mechanical integrity to allow them to be cut without fracturing. TEM studies of the aerogels show that they are comprised of fibers similar to that of V2O5 ARG`s, but with a much shorter chain length. Evidence from IR that the inorganic and organic components strongly interact leads us to propose that this impedes the vanadium condensation process. The result is ARG`s that exhibit decreased electronic conductivity with increasing polymer content. Despite the unexpected deleterious effect of the conductive polymer on the bulk conductivity, at low polymer content, the nanocomposite materials show enhanced electrochemical properties for Li insertion compared to the pristine aerogel.

  9. Monolithic and Small Particle Column Materials for Application in Proteomics

    NARCIS (Netherlands)

    Rozenbrand, J.

    2012-01-01

    In this thesis the influence of the capillary liquid chromatography separation on the identification of protein digests is studied. In the first part the chromatographic parameters for silica monolithic columns are optimized to obtain a high throughput or a high separation performance. in the second

  10. Desalination with Carbon Aerogel Electrodes

    National Research Council Canada - National Science Library

    Farmer, Joseph

    1996-01-01

    ... of 1.3x10 to the 7th power ft2 per lb have been achieved with thermal activation. After polarization, anions and cations are removed from the electrolyte by the imposed electric field and electrosorbed onto the carbon aerogel...

  11. Fabrication and Atomic Force Microscopy Characterization of Molecular Composites of Fullerenes in Aerogel Matrix for Optical Limiting

    Science.gov (United States)

    Lu, W. J .; Sunkara, H. B.; Shi, D.; Morgan, S. H.; Penn, B.; Frazier, D.; Collins, W. E.

    1998-01-01

    An optical limiter is a device which exhibits a decrease in the transmittance in a material with an increase in intensity of light. Sol-gel techniques offer many advantages in the fabrication of materials. These materials possess many desirable properties for nonlinear optical (NLO) device applications which include transparency, high thermal and chemical stabilities, very low refractive index and dielectric constants. C60 shows a higher excited state absorption cross section than the ground state absorption cross section over the complete visible spectrum, and the spectrum of the excited state absorption of C60 has the same general shape as the ground state absorption. This fact suggests that fullerenes are ideal optical limiting materials. Aerogels are fabricated by sol-gel processing. One of the key issues is the dispersion of fullerenes into small and uniform pores of silica aerogel host matrices. The aerogel network was characterized by Raman spectroscopy. Atomic force microscopy is a technique with many advantages to characterize the aerogel materials. The morphology of the cleaved surface for a C60/aerogel sample shows that there are long paralleled shaped stripes with 20-30 nm in width and about 500 nm in length on the cleaved surface. The cleaved surface also was etched by 5% HF solution for one minutes, and it became smoother after HF etching. The main feature in on the surface is the spherical particles with the size of few nanometers, and no aggregated fullerenes appear. The fullerenes are well dispersed in the aerogel matrices.

  12. Monolithic exploding foil initiator

    Science.gov (United States)

    Welle, Eric J; Vianco, Paul T; Headley, Paul S; Jarrell, Jason A; Garrity, J. Emmett; Shelton, Keegan P; Marley, Stephen K

    2012-10-23

    A monolithic exploding foil initiator (EFI) or slapper detonator and the method for making the monolithic EFI wherein the exploding bridge and the dielectric from which the flyer will be generated are integrated directly onto the header. In some embodiments, the barrel is directly integrated directly onto the header.

  13. Iron-Doped Carbon Aerogels: Novel Porous Substrates for Direct Growth of Carbon Nanotubes

    Science.gov (United States)

    Steiner, S. A.; Baumann, T. F.; Kong, J.; Satcher, J. H.; Dresselhaus, M. S.

    2007-02-20

    We present the synthesis and characterization of Fe-doped carbon aerogels (CAs) and demonstrate the ability to grow carbon nanotubes directly on monoliths of these materials to afford novel carbon aerogel-carbon nanotube composites. Preparation of the Fe-doped CAs begins with the sol-gel polymerization of the potassium salt of 2,4-dihydroxybenzoic acid with formaldehyde, affording K{sup +}-doped gels that can then be converted to Fe{sup 2+}- or Fe{sup 3+}-doped gels through an ion exchange process, dried with supercritical CO{sub 2} and subsequently carbonized under an inert atmosphere. Analysis of the Fe-doped CAs by TEM, XRD and XPS revealed that the doped iron species are reduced during carbonization to form metallic iron and iron carbide nanoparticles. The sizes and chemical composition of the reduced Fe species were related to pyrolysis temperature as well as the type of iron salt used in the ion exchange process. Raman spectroscopy and XRD analysis further reveal that, despite the presence of the Fe species, the CA framework is not significantly graphitized during pyrolysis. The Fe-doped CAs were subsequently placed in a thermal CVD reactor and exposed to a mixture of CH{sub 4} (1000 sccm), H{sub 2} (500 sccm), and C{sub 2}H{sub 4} (20 sccm) at temperatures ranging from 600 to 800 C for 10 minutes, resulting in direct growth of carbon nanotubes on the aerogel monoliths. Carbon nanotubes grown by this method appear to be multiwalled ({approx}25 nm in diameter and up to 4 mm long) and grow through a tip-growth mechanism that pushes catalytic iron particles out of the aerogel framework. The highest yield of CNTs were grown on Fe-doped CAs pyrolyzed at 800 C treated at CVD temperatures of 700 C.

  14. Iron-Doped Carbon Aerogels: Novel Porous Substrates for Direct Growth of Carbon Nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Steiner, S A; Baumann, T F; Kong, J; Satcher, J H; Dresselhaus, M S

    2007-02-15

    We present the synthesis and characterization of Fe-doped carbon aerogels (CAs) and demonstrate the ability to grow carbon nanotubes directly on monoliths of these materials to afford novel carbon aerogel-carbon nanotube composites. Preparation of the Fe-doped CAs begins with the sol-gel polymerization of the potassium salt of 2,4-dihydroxybenzoic acid with formaldehyde, affording K{sup +}-doped gels that can then be converted to Fe{sup 2+}- or Fe{sup 3+}-doped gels through an ion exchange process, dried with supercritical CO{sub 2} and subsequently carbonized under an inert atmosphere. Analysis of the Fe-doped CAs by TEM, XRD and XPS revealed that the doped iron species are reduced during carbonization to form metallic iron and iron carbide nanoparticles. The sizes and chemical composition of the reduced Fe species were related to pyrolysis temperature as well as the type of iron salt used in the ion exchange process. Raman spectroscopy and XRD analysis further reveal that, despite the presence of the Fe species, the CA framework is not significantly graphitized during pyrolysis. The Fe-doped CAs were subsequently placed in a thermal CVD reactor and exposed to a mixture of CH{sub 4} (1000 sccm), H{sub 2} (500 sccm), and C{sub 2}H{sub 4} (20 sccm) at temperatures ranging from 600 to 800 C for 10 minutes, resulting in direct growth of carbon nanotubes on the aerogel monoliths. Carbon nanotubes grown by this method appear to be multiwalled ({approx}25 nm in diameter and up to 4 mm long) and grow through a tip-growth mechanism that pushes catalytic iron particles out of the aerogel framework. The highest yield of CNTs were grown on Fe-doped CAs pyrolyzed at 800 C treated at CVD temperatures of 700 C.

  15. Periodic mesoporous silica gels

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, M.T.; Martin, J.E.; Odinek, J.G. [and others

    1996-06-01

    We have synthesized monolithic particulate gels of periodic mesoporous silica by adding tetramethoxysilane to a homogeneous alkaline micellar precursor solution. The gels exhibit 5 characteristic length scales over 4 orders of magnitude: fractal domains larger than the particle size (>500 nm), particles that are {approximately}150 to 500 nm in diameter, interparticle pores that are on the order of the particle size, a feature in the gas adsorption measurements that indicates pores {approximately}10-50 nm, and periodic hexagonal arrays of {approximately}3 nm channels within each particle. The wet gel monoliths exhibit calculated densities as low as {approximately}0.02 g/cc; the dried and calcined gels have bulk densities that range from {approximately}0.3-0.5 g/cc. The materials possess large interparticle ({approximately}1.0-2.3 cc/g) and intraparticle ({approximately}0.6 cc/g) porosities.

  16. Impact Verification of Aerogel Insulation Paint on Historic Brick Facades

    Science.gov (United States)

    Ganobjak, Michal; Kralova, Eva

    2017-10-01

    Increasing the sustainability of existing buildings is being motivated by reduction of their energy demands. It is the above all the building envelope and its refurbishment by substitution or addition of new materials that makes the opportunity for reduction of energy consumption. A special type of refurbishment is conservation of historical buildings. Preservation of historic buildings permits also application of innovative methods and materials in addition to the original materials if their effects are known and the gained experience ensures their beneficial effect. On the market, there are new materials with addition of silica aerogel in various forms of products. They are also potentially useful in conservation of monuments. However, the effects of aerogel application in these cases are not known. For refurbishment is commercially available additional transparent insulation paint - Nansulate Clear Coat which is containing aerogel and can be used for structured surfaces such as bricks. A series of experiments examined the thermo-physical manifestation of an ultra-thin insulation coating of Nansulate Clear Coat containing silica aerogel on a brick facade. The experiments of active and passive thermography have observed effects of application on the small-scale samples of the brick façade of a protected historical building. Through a series of experiments were measured thermal insulation effect and influence on the aesthetic characteristics such as change in colour and gloss. The treated samples were compared to a reference. Results have shown no thermal-insulating manifestation of the recommended three layers of insulation paint. The three layers recommended by the manufacturer did not significantly affect the appearance of the brick facade. Color and gloss were not significantly changed. Experiments showed the absence of thermal insulation effect of Nansulate transparent triple coating. The thermal insulation effect could likely be reached by more layers of

  17. Synthesis and characterization of hierarchically porous metal, metal oxide, and carbon monoliths with highly ordered nanostructure

    Science.gov (United States)

    Grano, Amy Janine

    Hierarchically porous materials are of great interest in such applications as catalysis, separations, fuel cells, and advanced batteries. One such way of producing these materials is through the process of nanocasting, in which a sacrificial template is replicated and then removed to form a monolithic replica. This replica consists of mesopores, which can be ordered or disordered, and bicontinuous macropores, which allow flow throughout the length of the monolith. Hierarchically porous metal oxide and carbon monoliths with an ordered mesopores system are synthesized for the first time via nanocasting. These replicas were used as supports for the deposition of silver particles and the catalytic efficiency was evaluated. The ordered silica template used in producing these monoliths was also used for an in-situ TEM study involving metal nanocasting, and an observation of the destruction of the silica template during nanocasting made. Two new methods of removing the silica template were developed and applied to the synthesis of copper, nickel oxide, and zinc oxide monoliths. Finally, hollow fiber membrane monoliths were examined via x-ray tomography in an attempt to establish the presence of this structure throughout the monolith.

  18. Chemical Analyses of Silicon Aerogel Samples

    Energy Technology Data Exchange (ETDEWEB)

    van der Werf, I.; Palmisano, F.; De Leo, Raffaele; Marrone, Stefano

    2008-04-01

    After five years of operating, two Aerogel counters: A1 and A2, taking data in Hall A at Jefferson Lab, suffered a loss of performance. In this note possible causes of degradation have been studied. In particular, various chemical and physical analyses have been carried out on several Aerogel tiles and on adhesive tape in order to reveal the presence of contaminants.

  19. Electrospinning of polymer-aerogel composite fibres

    DEFF Research Database (Denmark)

    Christiansen, Lasse; Fojan, Peter

    En poster om produktion af polymer-aerogel kompositfibre ved hjælp af elektrospinning. Fiberne er produceret fra en opløsning af aerogel og polyethylene oxide i vand, som er elektrospundet gennem en enkeltnålsprocess....

  20. About aerogels based on carbon nanomaterials

    Directory of Open Access Journals (Sweden)

    Fail Sultanov

    2014-12-01

    Full Text Available In this review a current trends in development and application of carbon nanomaterials and derivatives based on them are presented. Aerogels based on graphene and other carbon nanomaterials present a class of novel ultralight materials in which a liquid phase is completely substituted by gaseous. In its turn graphene based aerogel was named as the lightest material, thus the record of aerographite, which has retained for a long time was beaten. Aerogels are characterized by low density, high surface area and high index of hydrophobicity. In addition, depending on its application, aerogels based on carbon nanomaterials can be electrically conductive and magnetic, while retaining the flexibility of its 3D structure. Impressive properties of novel material – aerogels causes a huge interest of scientists in order to find their application in various fields, ranging from environment problems to medicine and electronics.

  1. Nano-Doped Monolithic Materials for Molecular Separation

    Directory of Open Access Journals (Sweden)

    Caleb Acquah

    2017-01-01

    Full Text Available Monoliths are continuous adsorbents that can easily be synthesised to possess tuneable meso-/macropores, convective fluid transport, and a plethora of chemistries for ligand immobilisation. They are grouped into three main classes: organic, inorganic, and hybrid, based on their chemical composition. These classes may also be differentiated by their unique morphological and physicochemical properties which are significantly relevant to their specific separation applications. The potential applications of monoliths for molecular separation have created the need to enhance their characteristic properties including mechanical strength, electrical conductivity, and chemical and thermal stability. An effective approach towards monolith enhancement has been the doping and/or hybridization with miniaturized molecular species of desirable functionalities and characteristics. Nanoparticles are usually preferred as dopants due to their high solid phase dispersion features which are associated with improved intermolecular adsorptive interactions. Examples of such nanomaterials include, but are not limited to, carbon-based, silica-based, gold-based, and alumina nanoparticles. The incorporation of these nanoparticles into monoliths via in situ polymerisation and/or post-modification enhances surface adsorption for activation and ligand immobilisation. Herein, insights into the performance enhancement of monoliths as chromatographic supports by nanoparticles doping are presented. In addition, the potential and characteristics of less common nanoparticle materials such as hydroxyapatite, ceria, hafnia, and germania are discussed. The advantages and challenges of nanoparticle doping of monoliths are also discussed.

  2. Surface Plasmon Resonance Evaluation of Colloidal Metal Aerogel Filters

    Science.gov (United States)

    Smith, David D.; Sibille, Laurent; Cronise, Raymond J.; Noever, David A.

    1997-01-01

    We have fabricated aerogels containing gold, silver, and platinum nanoparticles for gas catalysis applications. By applying the concept of an average or effective dielectric constant to the heterogeneous interlayer surrounding each particle, we extend the technique of immersion spectroscopy to porous or heterogeneous media. Specifically, we apply the predominant effective medium theories for the determination of the average fractional composition of each component in this inhomogeneous layer. Hence, the surface area of metal available for catalytic gas reaction is determined. The technique is satisfactory for statistically random metal particle distributions but needs further modification for aggregated or surfactant modified systems. Additionally, the kinetics suggest that collective particle interactions in coagulated clusters are perturbed during silica gelation resulting in a change in the aggregate geometry.

  3. Aerogels from Chitosan Solutions in Ionic Liquids

    Directory of Open Access Journals (Sweden)

    Gonzalo Santos-López

    2017-12-01

    Full Text Available Chitosan aerogels conjugates the characteristics of nanostructured porous materials, i.e., extended specific surface area and nano scale porosity, with the remarkable functional properties of chitosan. Aerogels were obtained from solutions of chitosan in ionic liquids (ILs, 1-butyl-3-methylimidazolium acetate (BMIMAc, and 1-ethyl-3-methyl-imidazolium acetate (EMIMAc, in order to observe the effect of the solvent in the structural characteristics of this type of materials. The process of elaboration of aerogels comprised the formation of physical gels through anti-solvent vapor diffusion, liquid phase exchange, and supercritical CO2 drying. The aerogels maintained the chemical identity of chitosan according to Fourier transform infrared spectrophotometer (FT-IR spectroscopy, indicating the presence of their characteristic functional groups. The internal structure of the obtained aerogels appears as porous aggregated networks in microscopy images. The obtained materials have specific surface areas over 350 m2/g and can be considered mesoporous. According to swelling experiments, the chitosan aerogels could absorb between three and six times their weight of water. However, the swelling and diffusion coefficient decreased at higher temperatures. The structural characteristics of chitosan aerogels that are obtained from ionic liquids are distinctive and could be related to solvation dynamic at the initial state.

  4. Aerogel Blanket Insulation Materials for Cryogenic Applications

    Science.gov (United States)

    Coffman, B. E.; Fesmire, J. E.; White, S.; Gould, G.; Augustynowicz, S.

    2009-01-01

    Aerogel blanket materials for use in thermal insulation systems are now commercially available and implemented by industry. Prototype aerogel blanket materials were presented at the Cryogenic Engineering Conference in 1997 and by 2004 had progressed to full commercial production by Aspen Aerogels. Today, this new technology material is providing superior energy efficiencies and enabling new design approaches for more cost effective cryogenic systems. Aerogel processing technology and methods are continuing to improve, offering a tailor-able array of product formulations for many different thermal and environmental requirements. Many different varieties and combinations of aerogel blankets have been characterized using insulation test cryostats at the Cryogenics Test Laboratory of NASA Kennedy Space Center. Detailed thermal conductivity data for a select group of materials are presented for engineering use. Heat transfer evaluations for the entire vacuum pressure range, including ambient conditions, are given. Examples of current cryogenic applications of aerogel blanket insulation are also given. KEYWORDS: Cryogenic tanks, thermal insulation, composite materials, aerogel, thermal conductivity, liquid nitrogen boil-off

  5. Carbon Papers and Aerogels Based on Graphene Layers and Chitosan: Direct Preparation from High Surface Area Graphite.

    Science.gov (United States)

    Barbera, Vincenzina; Guerra, Silvia; Brambilla, Luigi; Maggio, Mario; Serafini, Andrea; Conzatti, Lucia; Vitale, Alessandra; Galimberti, Maurizio

    2017-12-11

    In this work, carbon papers and aerogels based on graphene layers and chitosan were prepared. They were obtained by mixing chitosan (CS) and a high surface area nanosized graphite (HSAG) in water in the presence of acetic acid. HSAG/CS water dispersions were stable for months. High resolution transmission electron microscopy revealed the presence of few graphene layers in water suspensions. Casting or lyophilization of such suspensions led to the preparation of carbon paper and aerogel, respectively. In X-ray spectra of both aerogels and carbon paper, peaks due to regular stacks of graphene layers were not detected: graphene with unaltered sp 2 structure was obtained directly from graphite without the use of any chemical reaction. The composites were demonstrated to be electrically conductive thanks to the graphene. Chitosan thus makes it possible to obtain monolithic carbon aerogels and flexible and free-standing graphene papers directly from a nanosized graphite by avoiding oxidation to graphite oxide and successive reduction. Strong interaction between polycationic chitosan and the aromatic substrate appears to be at the origin of the stability of HSAG/CS adducts. Cation-π interaction is hypothesized, also on the basis of X-ray photoelectron spectroscopy findings. This work paves the way for the easy large-scale preparation of carbon papers through a method that has a low environmental impact and is based on a biosourced polymer, graphene, and water.

  6. Low density, resorcinol-formaldehyde aerogels

    Science.gov (United States)

    Pekala, R.W.

    1988-05-26

    The polycondensation of resorcinol with formaldehyde under alkaline conditions results in the formation of surface functionalized polymer ''clusters''. The covalent crosslinking of these ''clusters'' produces gels which when processed under supercritical conditions, produce low density, organic aerogels (density less than or equal to100 mg/cc; cell size less than or equal to0.1 microns). The aerogels are transparent,dark red in color and consist of interconnected colloidal-like particles with diameters of about 100 A/degree/. These aerogels may be further carbonized to form low density carbon foams with cell size of about 0.1 micron. 1 fig., 1 tab.

  7. Carbon aerogel electrodes for direct energy conversion

    Science.gov (United States)

    Mayer, Steven T.; Kaschmitter, James L.; Pekala, Richard W.

    1997-01-01

    A direct energy conversion device, such as a fuel cell, using carbon aerogel electrodes, wherein the carbon aerogel is loaded with a noble catalyst, such as platinum or rhodium and soaked with phosphoric acid, for example. A separator is located between the electrodes, which are placed in a cylinder having plate current collectors positioned adjacent the electrodes and connected to a power supply, and a pair of gas manifolds, containing hydrogen and oxygen positioned adjacent the current collectors. Due to the high surface area and excellent electrical conductivity of carbon aerogels, the problems relative to high polarization resistance of carbon composite electrodes conventionally used in fuel cells are overcome.

  8. A monolithic white laser.

    Science.gov (United States)

    Fan, Fan; Turkdogan, Sunay; Liu, Zhicheng; Shelhammer, David; Ning, C Z

    2015-09-01

    Monolithic semiconductor lasers capable of emitting over the full visible-colour spectrum have a wide range of important applications, such as solid-state lighting, full-colour displays, visible colour communications and multi-colour fluorescence sensing. The ultimate form of such a light source would be a monolithic white laser. However, realizing such a device has been challenging because of intrinsic difficulties in achieving epitaxial growth of the mismatched materials required for different colour emission. Here, we demonstrate a monolithic multi-segment semiconductor nanosheet based on a quaternary alloy of ZnCdSSe that simultaneously lases in the red, green and blue. This is made possible by a novel nanomaterial growth strategy that enables separate control of the composition, morphology and therefore bandgaps of the segments. Our nanolaser can be dynamically tuned to emit over the full visible-colour range, covering 70% more perceptible colours than the most commonly used illuminants.

  9. Rapid recovery of DNA from agarose gel slices by coupling electroelution with monolithic SPE.

    Science.gov (United States)

    Yu, Shengbing; Yang, Shuixian; Zhou, Ping; Zhou, Ke; Wang, Jing; Chen, Xiangdong

    2009-06-01

    An amino silica monolithic column prepared by in situ polymerization of tetraethoxysilane and N-(beta-aminoethyl)-gamma-aminopropyltriethoxysilane was firstly applied to recover DNA from agarose gel slices by coupling electroelution with monolithic SPE. DNA was electroeluted from the agarose gel slices onto the amino silica monolithic column. The DNA adsorbed on this monolithic column was then recovered using sodium phosphate solution at pH 10. The whole recovery procedure could be completed within 10 min because the use of amino silica monolithic column accelerated the DNA capture and facilitated the DNA release. Electroelution conditions, such as buffer pH, buffer concentration and applied voltage, were online optimized. The average yield for herring sperm DNA, pBR 322 DNA and lambda DNA recovered from 1.0% w/v agarose gel slices were 55+/-4, 50+/-6 and 42+/-7% (n=3), respectively. The polymerase chain reaction performance of pGM plasmid recovered from agarose gel slices demonstrated that the method could provide high-quality DNA for downstream processes. The combination of electroelution with monolithic SPE allows a rapid, simple and efficient DNA recovery method. This technique is especially useful for applications that need to purify small starting amounts of DNA.

  10. Fabrication and characterization of nanotemplated carbon monolithic material

    OpenAIRE

    He, Xiaoyun; Nesterenko, Ekaterina; Nesterenko, Pavel; Brabazon, Dermot; Zhou, Lin; Glennon, Jeremy D.; Luong, John H.T.; Paull, Brett

    2013-01-01

    A novel hierarchical nanotemplated carbon monolithic rod (NTCM) was prepared using a novel facile nanotemplating approach. The NTCM was obtained using C60-fullerene modified silica gels as hard templates, which were embedded in a phenolic resin containing a metal catalyst for localized graphitization, followed by bulk carbonization, and template and catalyst removal. TEM, SEM, and BET measurements revealed that NTCM possessed an integrated open hierarchical porous structure, with a trimodal p...

  11. Embedded-monolith armor

    Science.gov (United States)

    McElfresh, Michael W.; Groves, Scott E; Moffet, Mitchell L.; Martin, Louis P.

    2016-07-19

    A lightweight armor system utilizing a face section having a multiplicity of monoliths embedded in a matrix supported on low density foam. The face section is supported with a strong stiff backing plate. The backing plate is mounted on a spall plate.

  12. Study of ageing effects in aerogel

    CERN Document Server

    Bellunato, T F; Coluzza, C; Longo, G; Matteuzzi, C; Musy, M; Negri, P; Perego, D L

    2004-01-01

    Ageing effects on aerogel due to irradiation and absorption of humidity have been investigated. Aerogel tiles have been exposed to gamma radiation from a 60-Co source and to proton and neutron high intensity beams. The transmittance has been monitored in the wavelength range between 200 nm and 800 nm, determining the clarity factor C as a function of the increasing dose of irradiation. The index of refraction n was also measured.

  13. Fibrous-Ceramic/Aerogel Composite Insulating Tiles

    Science.gov (United States)

    White, Susan M.; Rasky, Daniel J.

    2004-01-01

    Fibrous-ceramic/aerogel composite tiles have been invented to afford combinations of thermal-insulation and mechanical properties superior to those attainable by making tiles of fibrous ceramics alone or aerogels alone. These lightweight tiles can be tailored to a variety of applications that range from insulating cryogenic tanks to protecting spacecraft against re-entry heating. The advantages and disadvantages of fibrous ceramics and aerogels can be summarized as follows: Tiles made of ceramic fibers are known for mechanical strength, toughness, and machinability. Fibrous ceramic tiles are highly effective as thermal insulators in a vacuum. However, undesirably, the porosity of these materials makes them permeable by gases, so that in the presence of air or other gases, convection and gas-phase conduction contribute to the effective thermal conductivity of the tiles. Other disadvantages of the porosity and permeability of fibrous ceramic tiles arise because gases (e.g., water vapor or cryogenic gases) can condense in pores. This condensation contributes to weight, and in the case of cryogenic systems, the heat of condensation undesirably adds to the heat flowing to the objects that one seeks to keep cold. Moreover, there is a risk of explosion associated with vaporization of previously condensed gas upon reheating. Aerogels offer low permeability, low density, and low thermal conductivity, but are mechanically fragile. The basic idea of the present invention is to exploit the best features of fibrous ceramic tiles and aerogels. In a composite tile according to the invention, the fibrous ceramic serves as a matrix that mechanically supports the aerogel, while the aerogel serves as a low-conductivity, low-permeability filling that closes what would otherwise be the open pores of the fibrous ceramic. Because the aerogel eliminates or at least suppresses permeation by gas, gas-phase conduction, and convection, the thermal conductivity of such a composite even at

  14. In vivo X-Ray excited optical luminescence from phosphor-doped aerogel and Sylgard 184 composites

    Science.gov (United States)

    Allison, Stephen W.; Baker, Ethan S.; Lynch, Kyle J.; Sabri, Firouzeh

    2017-06-01

    X-Ray excited optical luminescence (XEOL) is a new and noninvasive diagnostic technique suitable for in situ biochemical imaging and disease detection. The X-Ray excited optical luminescence of phosphor doping in crosslinked silica aerogel and Sylgard 184 hosts was investigated in this study. Composite silica aerogels and Sylgard 184 samples of 5%, 15%, and 50% concentrations by weight of La2O2S:Eu phosphor were prepared and inserted subcutaneously in a Sprague-Dawley rat and excited by X-Ray emission at 70 and 100 kV. A fiber optic bundle positioned within 5 mm of the sample collected the luminescence signal and conveyed it to a photomultiplier detector. The signal intensity scaled with dopant concentration. The time dependence of the predominantly red luminescence consisted of 60 cycle bursts of approximately 8 ms duration. The amplitude was modulated at about 10 Hz with a 60% depth. This indicates the time dependence of the X-Ray source. A simulation showed how to observe phosphor decay between individual burst pulses. The emission from the two types of composite samples was easily detected from the outside of the skin layer. Both Sylgard 184 and crosslinked silica aerogels are biocompatible and bio stable materials that could serve a variety of potential XEOL applications. These very strong signals imply potential for creating new In-vivo sensing applications and diagnostic tools.

  15. Monolithic column in gas chromatography.

    Science.gov (United States)

    Kurganov, A

    2013-05-02

    Monolithic columns invented in chromatographic praxis almost 40 years ago gained nowadays a lot of popularity in separations by liquid chromatographic technique. At the same time, application of monolithic columns in gas chromatography is less common and only a single review published by Svec et al. covers this field of research. Since that time a lot of new findings on application and properties of monolithic columns in gas chromatography have been published in the literature deserving consideration and discussion. This review considers preparation of monolithic columns for GC, an impact of preparation conditions on column performance, optimization of separation conditions for GC analysis on monolithic columns and other important aspects of preparation and usage of monolithic capillary columns in GC. A final part of the review discusses the modern trends and possible applications in the future of capillary monolithic columns in GC. Copyright © 2013 Elsevier B.V. All rights reserved.

  16. Synthesis and characterization of a nanocrystalline diamond aerogel

    Energy Technology Data Exchange (ETDEWEB)

    Pauzauskie, Peter J.; Crowhurst, Jonathan C.; Worsley, Marcus A.; Laurence, Ted A.; Kilcoyne, A. L. David; Wang, Yinmin; Willey, Trevor M.; Visbeck, Kenneth S.; Fakra, Sirine C.; Evans, William J.; Zaug, Joseph M.; Satcher, Jr., Joe H.

    2011-07-06

    Aerogel materials have myriad scientific and technological applications due to their large intrinsic surface areas and ultralow densities. However, creating a nanodiamond aerogel matrix has remained an outstanding and intriguing challenge. Here we report the high-pressure, high-temperature synthesis of a diamond aerogel from an amorphous carbon aerogel precursor using a laser-heated diamond anvil cell. Neon is used as a chemically inert, near-hydrostatic pressure medium that prevents collapse of the aerogel under pressure by conformally filling the aerogel's void volume. Electron and X-ray spectromicroscopy confirm the aerogel morphology and composition of the nanodiamond matrix. Time-resolved photoluminescence measurements of recovered material reveal the formation of both nitrogen- and silicon- vacancy point-defects, suggesting a broad range of applications for this nanocrystalline diamond aerogel.

  17. Bluedec in product design : Isolatiemateriaal op basis van aerogel

    NARCIS (Netherlands)

    Beurden, van K.M.M. (Karin); Goselink, E.A. (Erik)

    2014-01-01

    Aerogel is een zeer kostbaar voor de ruimtevaart ontwikkeld basismateriaal. Bluedec is een isolatiemateriaal bestaande uit een non woven kunststof dat met deze aerogel geïmpregneerd is. Hierdoor ontstaat een zeer goed isolerend materiaal dat goedkoper is dan aerogel. De

  18. Co-Fe-Si Aerogel Catalytic Honeycombs for Low Temperature Ethanol Steam Reforming

    Directory of Open Access Journals (Sweden)

    Montserrat Domínguez

    2012-09-01

    Full Text Available Cobalt talc doped with iron (Fe/Co~0.1 and dispersed in SiO2 aerogel was prepared from silica alcogel impregnated with metal nitrates by supercritical drying. Catalytic honeycombs were prepared following the same procedure, with the alcogel synthesized directly over cordierite honeycomb pieces. The composite aerogel catalyst was characterized by X-ray diffraction, scanning electron microscopy, focus ion beam, specific surface area and X-ray photoelectron spectroscopy. The catalytic layer is about 8 µm thick and adheres well to the cordierite support. It is constituted of talc layers of about 1.5 µm × 300 nm × 50 nm which are well dispersed and anchored in a SiO2 aerogel matrix with excellent mass-transfer properties. The catalyst was tested in the ethanol steam reforming reaction, aimed at producing hydrogen for on-board, on-demand applications at moderate temperature (573–673 K and pressure (1–7 bar. Compared to non-promoted cobalt talc, the catalyst doped with iron produces less methane as byproduct, which can only be reformed at high temperature, thereby resulting in higher hydrogen yields. At 673 K and 2 bar, 1.04 NLH2·mLEtOH(l−1·min−1 are obtained at S/C = 3 and W/F = 390 g·min·molEtOH−1.

  19. Influence of Surface Treatments on the Bond Strength of Resin Cements to Monolithic Zirconia.

    Science.gov (United States)

    Elsaka, Shaymaa E

    To assess the influence of surface treatment on the microtensile bond strength (μTBS) of resin cements to monolithic zirconia materials. Two types of monolithic zirconia (Zenostar T [ZT] and Prettau Anterior [PA]) were evaluated. The specimens were assigned to three groups based on the surface treatment applied: group 1: control, assintered; group 2: sandblasted with 50-μm Al₂O₃; group 3: tribochemically silica sandblasted. Two types of resin cements (Multilink Speed [MS] and Multilink N [MN]) were applied to each group for evaluating the bond strength using the μTBS test. The fractured specimens were observed with a stereomicroscope and SEM. Surface roughness and topography of monolithic zirconia were examined after treatment. Data were analyzed using ANOVA and Tukey's test. A Weibull analysis was performed on the bond strength data. The bond strength was significantly affected by the surface treatment and the type of resin cement (p zirconia (p = 0.387). Surface treatment with tribochemical silica sandblasting revealed significantly higher bond strength (p zirconia was changed due to surface treatments. The surface treatment of monolithic zirconia with tribochemical silica sandblasting enhanced the bond strength between zirconia and resin cements. Resins cements containing adhesive phosphate monomer (APM, MS) provided higher bond strength to monolithic zirconia than non-APM (MN).

  20. Aerogel Beads as Cryogenic Thermal Insulation System

    Science.gov (United States)

    Fesmire, J. E.; Augustynowicz, S. D.; Rouanet, S.; Thompson, Karen (Technical Monitor)

    2001-01-01

    An investigation of the use of aerogel beads as thermal insulation for cryogenic applications was conducted at the Cryogenics Test Laboratory of NASA Kennedy Space Center. Steady-state liquid nitrogen boiloff methods were used to characterize the thermal performance of aerogel beads in comparison with conventional insulation products such as perlite powder and multilayer insulation (MLI). Aerogel beads produced by Cabot Corporation have a bulk density below 100 kilograms per cubic meter (kg/cubic m) and a mean particle diameter of 1 millimeter (mm). The apparent thermal conductivity values of the bulk material have been determined under steady-state conditions at boundary temperatures of approximately 293 and 77 kelvin (K) and at various cold vacuum pressures (CVP). Vacuum levels ranged from 10(exp -5) torr to 760 torr. All test articles were made in a cylindrical configuration with a typical insulation thickness of 25 mm. Temperature profiles through the thickness of the test specimens were also measured. The results showed the performance of the aerogel beads was significantly better than the conventional materials in both soft-vacuum (1 to 10 torr) and no-vacuum (760 torr) ranges. Opacified aerogel beads performed better than perlite powder under high-vacuum conditions. Further studies for material optimization and system application are in progress.

  1. Parametric Analysis to Study the Influence of Aerogel-Based Renders’ Components on Thermal and Mechanical Performance

    Directory of Open Access Journals (Sweden)

    Sofia Ximenes

    2016-05-01

    Full Text Available Statistical models using multiple linear regression are some of the most widely used methods to study the influence of independent variables in a given phenomenon. This study’s objective is to understand the influence of the various components of aerogel-based renders on their thermal and mechanical performance, namely cement (three types, fly ash, aerial lime, silica sand, expanded clay, type of aerogel, expanded cork granules, expanded perlite, air entrainers, resins (two types, and rheological agent. The statistical analysis was performed using SPSS (Statistical Package for Social Sciences, based on 85 mortar mixes produced in the laboratory and on their values of thermal conductivity and compressive strength obtained using tests in small-scale samples. The results showed that aerial lime assumes the main role in improving the thermal conductivity of the mortars. Aerogel type, fly ash, expanded perlite and air entrainers are also relevant components for a good thermal conductivity. Expanded clay can improve the mechanical behavior and aerogel has the opposite effect.

  2. Parametric Analysis to Study the Influence of Aerogel-Based Renders’ Components on Thermal and Mechanical Performance

    Science.gov (United States)

    Ximenes, Sofia; Silva, Ana; Soares, António; Flores-Colen, Inês; de Brito, Jorge

    2016-01-01

    Statistical models using multiple linear regression are some of the most widely used methods to study the influence of independent variables in a given phenomenon. This study’s objective is to understand the influence of the various components of aerogel-based renders on their thermal and mechanical performance, namely cement (three types), fly ash, aerial lime, silica sand, expanded clay, type of aerogel, expanded cork granules, expanded perlite, air entrainers, resins (two types), and rheological agent. The statistical analysis was performed using SPSS (Statistical Package for Social Sciences), based on 85 mortar mixes produced in the laboratory and on their values of thermal conductivity and compressive strength obtained using tests in small-scale samples. The results showed that aerial lime assumes the main role in improving the thermal conductivity of the mortars. Aerogel type, fly ash, expanded perlite and air entrainers are also relevant components for a good thermal conductivity. Expanded clay can improve the mechanical behavior and aerogel has the opposite effect. PMID:28773460

  3. Parametric Analysis to Study the Influence of Aerogel-Based Renders' Components on Thermal and Mechanical Performance.

    Science.gov (United States)

    Ximenes, Sofia; Silva, Ana; Soares, António; Flores-Colen, Inês; de Brito, Jorge

    2016-05-04

    Statistical models using multiple linear regression are some of the most widely used methods to study the influence of independent variables in a given phenomenon. This study's objective is to understand the influence of the various components of aerogel-based renders on their thermal and mechanical performance, namely cement (three types), fly ash, aerial lime, silica sand, expanded clay, type of aerogel, expanded cork granules, expanded perlite, air entrainers, resins (two types), and rheological agent. The statistical analysis was performed using SPSS (Statistical Package for Social Sciences), based on 85 mortar mixes produced in the laboratory and on their values of thermal conductivity and compressive strength obtained using tests in small-scale samples. The results showed that aerial lime assumes the main role in improving the thermal conductivity of the mortars. Aerogel type, fly ash, expanded perlite and air entrainers are also relevant components for a good thermal conductivity. Expanded clay can improve the mechanical behavior and aerogel has the opposite effect.

  4. Preparation and characterization of phloroglucinol-formaldehyde aerogel

    International Nuclear Information System (INIS)

    Huang Changgang; China Academy of Engineering Physics, Mianyang; Tang Yongjian; Wang Chaoyang; Yan Hongmei

    2006-01-01

    Phloroglucinol-formaldehyde (PF) aerogels and carbonized PF (CPF) aerogels were prepared from Phloroglucinol (P) and Formaldehyde (F) by sol-gel, solvent exchanging, supercritical drying and carbonization processes. The aerogel has a large specific surface area, continuous nano-network and porous structure. The density and mean porosity radius will enlarge after being carbonized, while the specific surface area will be influenced little. The micro-structure and density of aerogel are controlled by concentration of total reactants and catalyzer, respectively. Aerogels with different micro-structure and different density fit for ICF targets can be prepared by optimizing synthesis conditions. (authors)

  5. Preparation, characterisation and modification of carbon-based monolithic rods for chromatographic applications.

    Science.gov (United States)

    Eltmimi, Ali H; Barron, Leon; Rafferty, Aran; Hanrahan, John P; Fedyanina, Olga; Nesterenko, Ekaterina; Nesterenko, Pavel N; Paull, Brett

    2010-05-01

    A range of porous carbon-based monolithic (PCM) rods with flow-through pore sizes of 1, 2, 5 and 10 mum, were produced using a silica particle template method. The rods were characterised using SEM and energy-dispersive X-ray spectroscopy, BET surface area and porous structure analysis, dilatometry and thermal gravimetry. SEM evaluation of the carbon monolithic structures revealed an interconnected rigid bimodal porous structure and energy-dispersive X-ray spectroscopy analysis verified the quantitative removal of the embedded silica beads. The specific surface areas of the 1, 2, 5 and 10 mum rods were 178, 154, 84 and 125 m(2)/g after pyrolysis and silica removal, respectively. Shrinkage of the monolithic rods during pyrolysis is proportional to the particle size of the silica used and ranged from 9 to 12%. Mercury porosimetry showed a narrow distribution of pore sizes, with an average of approximately 700 nm for the 1 mum carbon monolith. The suitability of bare and surface oxidised PCM rods for the use as a stationary phase for reversed and normal phase LC was explored. The additional modification of PCM rods with gold micro-particles followed by 6-mercaptohexanoic acid was performed and ion-exchange properties were evaluated.

  6. Fluorine-Free Oil Absorbents Made from Cellulose Nanofibril Aerogels.

    Science.gov (United States)

    Mulyadi, Arie; Zhang, Zhe; Deng, Yulin

    2016-02-03

    Aerogels based on cellulose nanofibrils (CNFs) have been of great interest as absorbents due to their high absorption capacity, low density, biodegradability, and large surface area. Hydrophobic aerogels have been designed to give excellent oil absorption tendency from water. Herein, we present an in situ method for CNF surface modification and hydrophobic aerogel preparation. Neither solvent exchange nor fluorine chemical is used in aerogel preparations. The as-prepared hydrophobic aerogels exhibit low density (23.2 mg/cm(-3)), high porosity (98.5%), good flexibility, and solvent-induced shape recovery property. Successful surface modification was confirmed through field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and water contact angle measurements. The hydrophobic aerogels show high absorption capacities for various oils, depending on liquid density, up to 47× their original weight but with low water uptake (<0.5 g/g aerogel).

  7. Test of aerogel as Cherenkov radiator

    CERN Document Server

    Alemi, M; Calvi, M; Matteuzzi, C; Negri, P; Paganoni, M; Liko, D; Neufeld, N; Chesi, Enrico Guido; Joram, C; Séguinot, Jacques; Ypsilantis, Thomas

    2001-01-01

    Two different stacks of aerogel were tested in a pion/proton beam of momentum between 3 and 10 GeV/c. The optical characteristics of the aerogel samples were different: one sample was hygroscopic while the other was hydrophobic. Two HPD tubes were used as photodetectors, and different thicknesses of the stacks were used, in order to determine the photoelectron yield, the Cherenkov angle and its precision. Pion/proton separation has been demonstrated at momenta up to 10 GeV/c.

  8. Tailoring aerogel electrodes for electrochemical applications

    Science.gov (United States)

    Sakamoto, Jeffrey Steven

    2001-07-01

    The principal theme of the dissertation research was determining the relation between aerogel electrode morphology and electrochemical performance. Issues such as electrical wiring and mass transport in transition metal oxide, aerogel electrodes were addressed and designs were tailored for electrochemical applications. Single-wall carbon nanotubes were used to form the electronically conducting network in lithium intercalation electrodes that incorporated vanadium oxide aerogel as the active material. The similarities in morphology and dimensional scale for the nanotubes and V2O5 ribbons enabled excellent electrical contact to be made between the two phases without seriously affecting the aerogel nanostructure. The electrodes exhibited specific capacities in excess of 400 mAh/g at high discharge rates and retained this level of capacity on cycling. A second research goal was to improve mass transport within the aerogel electrode by minimizing tortuosity. In this research, hierarchically ordered vanadium oxide aerogel electrodes were designed and fabricated. The electrodes have two discrete and independent levels or porosity. At one level, ordered, interconnected macropores were fabricated using the templating process. At another level, interconnected mesopores were created using sol-gel synthesis and ambient drying. Electrochemical activity towards lithium was demonstrated using cyclic voltammetry and chronopotentiometry. These data are believed to be the first to demonstrate electrochemical activity for the class of materials based on the inverse opal structure. Several Group I cations and multivalent cations were reversibly, and electrochemically reacted with vanadium oxide aerogel. The molar capacities of the Group I elements (Na+ = 3.0 moles and K+ = 2.0) were high and comparable to Li+ (3.6 moles). Interestingly, the electron equivalent capacity for Mg2+ (4.0) was higher than Li+ and agrees well with the chemical titration capacity. Galvanostatic rate

  9. Recent developments and applications of molecularly imprinted monolithic column for HPLC and CEC.

    Science.gov (United States)

    Zheng, Chao; Huang, Yan-Ping; Liu, Zhao-Sheng

    2011-08-01

    As a new generation of stationary phases, monolithic supports have attracted significant interest in high-performance liquid chromatography (HPLC) and capillary electrochromatography (CEC) because of their ease of preparation, high reproducibility, versatile surface chemistry and rapid mass transport. Molecularly imprinted polymers (MIPs) are synthetic materials with high specific recognition ability to template molecule. The combination of monolithic column and MIPs integrates the high efficiency of modern chromatography and the high selectivity provided by MIPs. This review focuses on the recent developments and applications of all kinds of monolithic matrix, i.e. organic polymer-based and silica-based MIP monolith in HPLC and CEC mode. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Comparing monolithic and fused core HPLC columns for fast chromatographic analysis of fat-soluble vitamins.

    Science.gov (United States)

    Kurdi, Said El; Muaileq, Dina Abu; Alhazmi, Hassan A; Bratty, Mohammed Al; Deeb, Sami El

    2017-06-27

    HPLC stationary phases of monolithic and fused core type can be used to achieve fast chromatographic separation as an alternative to UPLC. In this study, monolithic and fused core stationary phases are compared for fast separation of four fat-soluble vitamins. Three new methods on the first and second generation monolithic silica RP-18e columns and a fused core pentafluoro-phenyl propyl column were developed. Application of three fused core columns offered comparable separations of retinyl palmitate, DL-α-tocopheryl acetate, cholecalciferol and menadione in terms of elution speed and separation efficiency. Separation was achieved in approx. 5 min with good resolution (Rs > 5) and precision (RSD ≤ 0.6 %). Monolithic columns showed, however, a higher number of theoretical plates, better precision and lower column backpressure than the fused core column. The three developed methods were successfully applied to separate and quantitate fat-soluble vitamins in commercial products.

  11. Comparing monolithic and fused core HPLC columns for fast chromatographic analysis of fat-soluble vitamins

    Directory of Open Access Journals (Sweden)

    Kurdi Said El

    2017-06-01

    Full Text Available HPLC stationary phases of monolithic and fused core type can be used to achieve fast chromatographic separation as an alternative to UPLC. In this study, monolithic and fused core stationary phases are compared for fast separation of four fat-soluble vitamins. Three new methods on the first and second generation monolithic silica RP-18e columns and a fused core pentafluoro-phenyl propyl column were developed. Application of three fused core columns offered comparable separations of retinyl palmitate, DL-α-tocopheryl acetate, cholecalciferol and menadione in terms of elution speed and separation efficiency. Separation was achieved in approx. 5 min with good resolution (Rs > 5 and precision (RSD ≤ 0.6 %. Monolithic columns showed, however, a higher number of theoretical plates, better precision and lower column backpressure than the fused core column. The three developed methods were successfully applied to separate and quantitate fat-soluble vitamins in commercial products.

  12. Bioaffinity chromatography on monolithic supports

    NARCIS (Netherlands)

    Tetala, K.K.R.; Beek, van T.A.

    2010-01-01

    Affinity chromatography on monolithic supports is a powerful analytical chemical platform because it allows for fast analyses, small sample volumes, strong enrichment of trace biomarkers and applications in microchips. In this review, the recent research using monolithic materials in the field of

  13. Spectroscopic studies of Cu 2 ions in sol–gel derived silica matrix

    Indian Academy of Sciences (India)

    The Cu2+ ion doped silica gel matrices in monolithic shape were prepared by hydrolysis and condensation of tetraethyl orthosilicate (TEOS). The absorption, transmittance and fluorescence spectra of the gel matrices heat treated at different temperatures were monitored. The loss of water and hydroxyl group from silica ...

  14. Environmentally Benign Production of Stretchable and Robust Superhydrophobic Silicone Monoliths.

    Science.gov (United States)

    Davis, Alexander; Surdo, Salvatore; Caputo, Gianvito; Bayer, Ilker S; Athanassiou, Athanassia

    2018-01-24

    Superhydrophobic materials hold an enormous potential in sectors as important as aerospace, food industries, or biomedicine. Despite this great promise, the lack of environmentally friendly production methods and limited robustness remain the two most pertinent barriers to the scalability, large-area production, and widespread use of superhydrophobic materials. In this work, highly robust superhydrophobic silicone monoliths are produced through a scalable and environmentally friendly emulsion technique. It is first found that stable and surfactantless water-in-polydimethylsiloxane (PDMS) emulsions can be formed through mechanical mixing. Increasing the internal phase fraction of the precursor emulsion is found to increase porosity and microtexture of the final monoliths, rendering them superhydrophobic. Silica nanoparticles can also be dispersed in the aqueous internal phase to create micro/nanotextured monoliths, giving further improvements in superhydrophobicity. Due to the elastomeric nature of PDMS, superhydrophobicity can be maintained even while the material is mechanically strained or compressed. In addition, because of their self-similarity, the monoliths show outstanding robustness to knife-scratch, tape-peel, and finger-wipe tests, as well as rigorous sandpaper abrasion. Superhydrophobicity was also unchanged when exposed to adverse environmental conditions including corrosive solutions, UV light, extreme temperatures, and high-energy droplet impact. Finally, important properties for eventual adoption in real-world applications including self-cleaning, stain-repellence, and blood-repellence are demonstrated.

  15. Enthalpy-entropy compensation effect on adsorption of light hydrocarbons on monolithic stationary phases.

    Science.gov (United States)

    Korolev, Alexander A; Shiryaeva, Valeria E; Popova, Tamara P; Kurganov, Alexander A

    2011-08-01

    Enthalpy and entropy of adsorption of light hydrocarbons C1-C4 have been measured for three monoliths of different polarity and for five different carrier gases: helium, hydrogen, nitrogen, carbon dioxide and dinitrogen oxide. Using carrier gas helium the highest values of enthalpy and entropy were observed for monolith based on ethylenedimethacrylate and the lowest values were observed for monolith based on silica, while monolith based on divinylbenzene demonstrated intermediate values. Entropy-enthalpy correlations were observed with carrier gas helium for all thee monoliths and possess similar slope indicating similar adsorption mechanism on all monoliths studied. Comparing different carrier gases entropy-enthalpy correlations within a homological series of solutes were observed for light carrier gases (He, H2 and N2) and were not observed for heavy carrier gases (CO2 and N2O). Instead, entropy-enthalpy correlations for heavy carrier gases were observed with pressure as variable and the higher the carrier gas pressure the lower the values of enthalpy and entropy observed. The observed changes in entropy-enthalpy correlations were explained by competitive adsorption of heavy carrier gas on monoliths. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Monolithic columns with immobilized monomeric avidin: preparation and application for affinity chromatography.

    Science.gov (United States)

    Spross, Jens; Sinz, Andrea

    2012-03-01

    A poly(glycidyl methacrylate-co-acrylamide-co-ethylene dimethacrylate) monolith and a poly(glycidyl methacrylate-co-ethylene dimethacrylate) monolith were prepared in fused silica capillaries (100 μm ID) and modified with monomeric avidin using the glutaraldehyde technique. The biotin binding capacity of monolithic affinity columns with immobilized monomeric avidin (MACMAs) was determined by fluorescence spectroscopy using biotin (5-fluorescein) conjugate, as well as biotin- and fluorescein-labeled bovine serum albumin (BSA). The affinity columns were able to bind 16.4 and 3.7 μmol biotin/mL, respectively. Columns prepared using the poly(glycidyl methacrylate-co-ethylene dimethacrylate) monolith retained 7.1 mg BSA/mL, almost six times more than commercially available monomeric avidin beads. Protocols based on MALDI-TOF mass spectrometry monitoring were optimized for the enrichment of biotinylated proteins and peptides. A comparison of enrichment efficiencies between MACMAs and commercially available monomeric avidin beads yielded superior results for our novel monolithic affinity columns. However, the affinity medium presented in this work suffers from a significant degree of nonspecific binding, which might hamper the analysis of more complex mixtures. Further modifications of the monolith's surface are envisaged for the future development of monoliths with improved enrichment characteristics.

  17. Biodiesel synthesis using K2CO3/Al–O–Si aerogel catalysts

    Directory of Open Access Journals (Sweden)

    IVANA LUKIĆ

    2010-06-01

    Full Text Available In this study, catalysts for fatty acid methyl esters (FAME or bio-diesel synthesis with K2CO3 as the active component on an alumina/silica support were synthesized using the sol–gel method, which was followed by drying the “dense” wet gels with supercritical carbon dioxide to obtain the aerogels. The prepared catalysts were characterized by XRD analysis, FTIR spectroscopy and N2 physisorption at 77 K, and tested in the methanolysis of sunflower oil. The effects of reaction variables, such as reaction time, temperature and methanol to oil molar ratio, on the yield of FAME were investigated. The aerogel catalysts with K2CO3 as the active component on an alumina/silica support exhibited good activity in the methanolysis of sunflower oil. The leaching of potassium when the catalyst was in contact with pure methanol under the working conditions of methanolysis was also tested in this study, indicating that it occurred only at higher temperatures, while at lower ones, it was negligible.

  18. Porous polymer monolithic col

    Directory of Open Access Journals (Sweden)

    Lydia Terborg

    2015-05-01

    Full Text Available A new approach has been developed for the preparation of mixed-mode stationary phases to separate proteins. The pore surface of monolithic poly(glycidyl methacrylate-co-ethylene dimethacrylate capillary columns was functionalized with thiols and coated with gold nanoparticles. The final mixed mode surface chemistry was formed by attaching, in a single step, alkanethiols, mercaptoalkanoic acids, and their mixtures on the free surface of attached gold nanoparticles. Use of these mixtures allowed fine tuning of the hydrophobic/hydrophilic balance. The amount of attached gold nanoparticles according to thermal gravimetric analysis was 44.8 wt.%. This value together with results of frontal elution enabled calculation of surface coverage with the alkanethiol and mercaptoalkanoic acid ligands. Interestingly, alkanethiols coverage in a range of 4.46–4.51 molecules/nm2 significantly exceeded that of mercaptoalkanoic acids with 2.39–2.45 molecules/nm2. The mixed mode character of these monolithic stationary phases was for the first time demonstrated in the separations of proteins that could be achieved in the same column using gradient elution conditions typical of reverse phase (using gradient of acetonitrile in water and ion exchange chromatographic modes (applying gradient of salt in water, respectively.

  19. Mechanically Robust Polymer-Graphene Aerogels

    Science.gov (United States)

    Ha, Heonjoo; Shanmuganathan, Kadhiravan; Ellison, Christopher

    2015-03-01

    Graphene has been intensely studied for the past several years due to its many attractive properties. Graphene oxide (GO) aerogels are particularly interesting due to their light weight and excellent performance in various applications, such as environmental remediation, super-hydrophobic and super-oleophilic materials, energy storage, etc. However, GO aerogels are generally weak and delicate which complicates their handling and potentially limits their application outside the research lab. The focus of this work is to synthesize mechanically stable aerogels that are robust and easy to handle without substantially sacrificing their low density. To overcome this challenge, we found that by intermixing a small amount of readily available and thermally crosslinkable polymer can enhance the mechanical properties without disrupting other characteristic intrinsic properties of the aerogel itself. This method is a simple straight-forward procedure that does not include any tedious chemical reactions or harsh chemicals. Furthermore, we will demonstrate the performance of these materials as a super-absorbent and pressure sensor.

  20. Confinement of helium tides by aerogel

    Science.gov (United States)

    Dolesi, R.; Bonaldi, M.; Vitale, S.

    1999-12-01

    In the context of scientific space missions that use liquid helium as a coolant, many methods have been proposed to solve the problem of helium confinement. This problem is particularly relevant for those missions which carry on board sensitive accelerometers, because the sub-millimetre motion of the liquid-vapour interface due to the varying gravitational field amplifies the gravitational disturbances beyond the affordable level. Within this framework it has been proposed to use the strong Van der Waals and capillary forces that rise in nanometer sized pores of aerogel to confine helium. Aerogel is a space qualified material and many of its properties have been already studied to a large extent. Its pores occupy a volume always larger than at least 90% of the total volume, with an overall density comparable to the density of the helium liquid itself. We report here on a preliminary experiment that has investigated, by means of the torsion pendulum method, the He II behaviour when only partially filling an aerogel sample. For pressure values below saturation, we observed in particular a high "tortuosity" of the liquid-vapour interface. This supports the idea that even a gravitational field of 1 g does not overcome capillary forces in shaping the superfluid configuration in aerogel.

  1. 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.

  2. Organic Aerogels with Improved Resilience and Flexibility for Multifunctional Protection in Spacesuits, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Aspen Aerogels Inc proposes to develop high resilience polymeric aerogel for use as a multifunctional spacesuit material which will significantly improve human...

  3. Insights into the Controllable Chemical Composition of Metal Oxide Nanowires and Graphene Aerogels

    Science.gov (United States)

    Goldstein, Anna Patrice

    briefly, then isolated pockets of MTiO3 are formed on the nanowire surface. This structure retains the conductive channel in the center of the nanowire, which can be useful for charge separation. Longer annealing times result in segmented nanowires; the segments formed from a Ni-coated nanowire are bounded by TiO2(01-1) twin planes and NiTiO 3{100}/TiO2{03-1} interfaces. An alternative strategy for storing solar energy takes advantage of the capacitance between a semiconductor surface and adsorbed ions in solution. This type of energy storage device is called an electric double layer capacitor (EDLC). Graphene-based aerogels, which are porous materials composed of few-layer graphitic sheets, have the potential for higher surface area and higher conductivity than standard carbon aerogels. These properties make graphene-based aerogels a good material candidate for EDLC electrodes. Graphene oxide (GO) is the precursor material for the synthesis of a graphene-based aerogel, and it has been widely studied. Yet its hydrothermal gelation is still not fully understood, due to the high pressure reaction conditions and the non-uniform nature of GO. We demonstrate a number of changes that occur to the GO sheets during gelation: wrinkling, formation of a densified monolith, deoxygenation, increasing thermal stability, and color change. Plotting the time evolution of all these properties shows that they are simultaneous and likely of common origin. Possible mechanisms for gelation are explored. Graphene aerogels are synthesized by vapor phase thermal reduction of GO aerogels at temperatures up to 1600 °C. Further deoxygenation is observed in the aerogel during thermal reduction, along with enhanced crystallinity and an associated change in the electronic structure. When graphene aerogels are exposed to high-temperature boron oxide vapor, they are converted to boron nitride (BN) aerogels. The structure of the BN aerogel is investigated and shown to be similar in nanoscale morphology

  4. Facile preparation of SiO2/TiO2 composite monolithic capillary column and its application in enrichment of phosphopeptides.

    Science.gov (United States)

    Wang, Shao-Ting; Wang, Meng-Ya; Su, Xin; Yuan, Bi-Feng; Feng, Yu-Qi

    2012-09-18

    A novel SiO(2)/TiO(2) composite monolithic capillary column was prepared by sol-gel technology and successfully applied to enrich phosphopeptides as a metal oxide affinity chromatography (MOAC) material. For the monolith preparation, tetramethoxysilane (TMOS) and tetrabutoxytitanium (TBOT) were used as silica and titania source, respectively, and glycerol was introduced to attenuate the activity of titanium precursor, which provided a mild synthetic condition. The prepared monolith was characterized by energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). The results revealed an approximate 1/2 molar ratio of titanium to silica as well as an atom-scale homogeneity in the framework. The scanning electron microscopy (SEM) results demonstrated an excellent anchorage between the column and the inner capillary wall, and nitrogen adsorption-desorption experiments showed a bimodal porosity with a narrow mesopore distribution around 3.6 nm. The prepared monolith was then applied for selective enrichment of phosphopeptides from the digestion mixture of phosphoproteins and bovine serum albumin (BSA) as well as human blood serum, nonfat milk, and egg white using an in-tube solid phase microextraction (SPME) system. Our results showed that SiO(2)/TiO(2) composite monolithic capillary column could efficiently enrich the phosphopeptides from complex matrixes. To the best of our knowledge, this is the first attempt for preparing the silica-metal composite monolithic capillary column, which offers the promising application of the monolith on phosphoproteomics study.

  5. Nitrogen-doped carbon aerogels for electrical energy storage

    Science.gov (United States)

    Campbell, Patrick; Montalvo, Elizabeth; Baumann, Theodore F.; Biener, Juergen; Merrill, Matthew; Reed, Eric W.; Worsley, Marcus A.

    2017-10-03

    Disclosed here is a method for making a nitrogen-doped carbon aerogel, comprising: preparing a reaction mixture comprising formaldehyde, at least one nitrogen-containing resorcinol analog, at least one catalyst, and at least one solvent; curing the reaction mixture to produce a wet gel; drying the wet gel to produce a dry gel; and thermally annealing the dry gel to produce the nitrogen-doped carbon aerogel. Also disclosed is a nitrogen-doped carbon aerogel obtained according to the method and a supercapacitor comprising the nitrogen-doped carbon aerogel.

  6. Lightweight Rubbery Aerogel Composites for High Performance Protection, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Aspen Aerogels Inc. (AAI) and the Man Vehicle Laboratory (MVL) at the Massachusetts Institute of Technology propose to develop nanostructured, lightweight, rubbery...

  7. Mechanically Strong Lightweight Materials for Aerospace Applications (x-aerogels)

    Science.gov (United States)

    Leventis, Nicholas

    2005-01-01

    The X-Aerogel is a new NASA-developed strong lightweight material made by reacting the mesoporous surfaces of 3-D networks of inorganic nanoparticles with polymeric crosslinkers. Since the relative amount of the crosslinker and the backbone are comparable, X-Aerogels can be viewed either as aerogels modified by templated accumulation of polymer on the skeletal nanoparticles, or as nanoporous polymers made by templated casting of polymeric precursors on a nanostructured framework. The most striking feature of X-Aerogels is that for a nominal 3-fold increase in density (still a ultralightweight material), the mechanical strength can be up to 300 times higher than the strength of the underlying native aerogel. Thus, X-Aerogels combine a multiple of the specific compressive strength of steel, with the thermal conductivity of styrofoam. XAerogels have been demonstrated with several polymers such as polyurethanes/polyureas, epoxies and polyolefins, while crosslinking of approximately 35 different oxide aerogels yields a wide variety of dimensionally stable, porous lightweight materials with interesting structural, magnetic and optical properties. X-Aerogels are evaluated for cryogenic rocket fuel storage tanks and for Advanced EVA suits, where they will play the dual role of the thermal insulator/structural material. Along the same lines, major impact is also expected by the use of X-Aerogels in structural components/thermal protection for small satellites, spacecrafts, planetary vehicles and habitats.

  8. Synthesis, characterization and catalytic activity of highly ordered hexagonal and cubic composite monoliths.

    Science.gov (United States)

    El-Safty, Sherif A

    2008-03-15

    Design of nanocatalysts for efficient heterogeneous catalytic systems is needed to high ingredients for environmental cleanup of organic pollutant species. Here, well-defined order NiO-silica monolithic catalysts with hexagonal P6mm and cubic Pm3n mesostructures were successfully fabricated by using an instant direct-templating method of lyotropic and microemulsion phases of Brij 76 (C18H37(OCH2CH2)10 OH, C18EO 10). Ordered hexagonal P6mm NiO/HOM-2 monoliths could be fabricated in lyotropic system of Brij 76 at phase composition domains of TMOS/Brij 76 (50 wt%). However, periodically ordered cubic Pm3n NiO-supported monoliths were synthesized in microemulsion system formed by addition of C12-alkane to the hexagonal phase domains. This synthetic strategy also revealed that the NiO particles were well-dispersed into the silicate pore surface matrices of mesostructures. Monolithic NiO-silica composites with 2D hexagonal and 3D cubic geometries and with large particle morphologies show promise to act as catalysts. The current study revealed evidence of the advantages of nanoscale pore geometry and shape, and particle morphology of the supported silica monoliths in the design of nanocatalysts that can efficiently enhance the catalytic functionality in terms of stability, reversibility and reactivity. Furthermore, a key finding in our study was that 2D hexagonal and 3D cubic mesostructured NiO-silica catalysts retained the specific activity towards the oxidation reaction even after several regeneration/reuse cycles. Significant study of the mechanistic cyclization of the organic reactant using the density functional (DFT) calculations provided evidence of the key components of conformations of the functional model during the formation of the oxidation product.

  9. Preparation and characterization of alkyl methacrylate-based monolithic columns for capillary gas chromatography applications.

    Science.gov (United States)

    Yusuf, Kareem; Aqel, Ahmad; A L Othman, Zeid; Badjah-Hadj-Ahmed, Ahmed Yacine

    2013-08-02

    Gas chromatography (GC) is considered the least common application of both polymer and silica-based monolithic columns. This study describes the fabrication of alkyl methacrylate monolithic materials for use as stationary phases in capillary gas chromatography. Following the deactivation of the capillary surface with 3-(trimethoxysilyl)propyl methacrylate (TMSM), the monoliths were formed by the co-polymerization of either hexyl methacrylate (HMA) or lauryl methacrylate (LMA) with different percentage of ethylene glycol dimethacrylate (EDMA) in presence of an initiator (azobisisobutyronitrile, AIBN) and a mixture of porogens include 1-propanol, 1,4-butanediol and water. The monoliths were prepared in 500mm length capillaries possessing inner diameters of 250μm. The efficiencies of the monolithic columns for low molecular weight compounds significantly improved as the percentage of crosslinker was increased, because of the greater proportion of pores less than 50nm. The columns containing lower percentages of crosslinker were able to rapidly separate a series of 8 alkane members in 0.7min, but the separation was less efficient for the light alkanes. Columns prepared with the lauryl methacrylate monomer yielded a different morphology for the monolith-interconnected channels. The channels were more branched, which increased the separation time, and unlike the other columns, allowed for temperature programming. Copyright © 2013 Elsevier B.V. All rights reserved.

  10. Particle identification system based on dense aerogel

    Energy Technology Data Exchange (ETDEWEB)

    Barnyakov, A.Yu. [Budker Institute of Nuclear Physics, 11, akademika Lavrentieva prospect, Novosibirsk 630090 (Russian Federation); Barnyakov, M.Yu. [Budker Institute of Nuclear Physics, 11, akademika Lavrentieva prospect, Novosibirsk 630090 (Russian Federation); Novosibirsk State Technical University, 20, Karl Marx prospect, Novosibirsk, 630092 (Russian Federation); Beloborodov, K.I., E-mail: K.I.Beloborodov@inp.nsk.su [Budker Institute of Nuclear Physics, 11, akademika Lavrentieva prospect, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, 2, Pirogova Street, Novosibirsk 630090 (Russian Federation); Bobrovnikov, V.S.; Buzykaev, A.R. [Budker Institute of Nuclear Physics, 11, akademika Lavrentieva prospect, Novosibirsk 630090 (Russian Federation); Danilyuk, A.F. [Boreskov Institute of Catalysis, 5, akademika Lavrentieva prospect, Novosibirsk 630090 (Russian Federation); Golubev, V.B. [Budker Institute of Nuclear Physics, 11, akademika Lavrentieva prospect, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, 2, Pirogova Street, Novosibirsk 630090 (Russian Federation); Gulevich, V.V. [Budker Institute of Nuclear Physics, 11, akademika Lavrentieva prospect, Novosibirsk 630090 (Russian Federation); Kononov, S.A.; Kravchenko, E.A. [Budker Institute of Nuclear Physics, 11, akademika Lavrentieva prospect, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, 2, Pirogova Street, Novosibirsk 630090 (Russian Federation); Onuchin, A.P.; Martin, K.A. [Budker Institute of Nuclear Physics, 11, akademika Lavrentieva prospect, Novosibirsk 630090 (Russian Federation); Novosibirsk State Technical University, 20, Karl Marx prospect, Novosibirsk, 630092 (Russian Federation); Serednyakov, S.I. [Budker Institute of Nuclear Physics, 11, akademika Lavrentieva prospect, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, 2, Pirogova Street, Novosibirsk 630090 (Russian Federation); and others

    2013-12-21

    A threshold Cherenkov counter based on dense aerogel with refraction index n=1.13 is described. This counter is used for kaon identification at momenta below 1 GeV/c in the SND detector, which takes data at the VEPP-2000 e{sup +}e{sup −} collider. The results of measurements of the counter efficiency using electrons, muons, pions, and kaons produced in e{sup +}e{sup −} annihilation are presented.

  11. Monolithic metal oxide transistors.

    Science.gov (United States)

    Choi, Yongsuk; Park, Won-Yeong; Kang, Moon Sung; Yi, Gi-Ra; Lee, Jun-Young; Kim, Yong-Hoon; Cho, Jeong Ho

    2015-04-28

    We devised a simple transparent metal oxide thin film transistor architecture composed of only two component materials, an amorphous metal oxide and ion gel gate dielectric, which could be entirely assembled using room-temperature processes on a plastic substrate. The geometry cleverly takes advantage of the unique characteristics of the two components. An oxide layer is metallized upon exposure to plasma, leading to the formation of a monolithic source-channel-drain oxide layer, and the ion gel gate dielectric is used to gate the transistor channel effectively at low voltages through a coplanar gate. We confirmed that the method is generally applicable to a variety of sol-gel-processed amorphous metal oxides, including indium oxide, indium zinc oxide, and indium gallium zinc oxide. An inverter NOT logic device was assembled using the resulting devices as a proof of concept demonstration of the applicability of the devices to logic circuits. The favorable characteristics of these devices, including (i) the simplicity of the device structure with only two components, (ii) the benign fabrication processes at room temperature, (iii) the low-voltage operation under 2 V, and (iv) the excellent and stable electrical performances, together support the application of these devices to low-cost portable gadgets, i.e., cheap electronics.

  12. Chemical modification of graphene aerogels for electrochemical capacitor applications.

    Science.gov (United States)

    Hong, Jin-Yong; Wie, Jeong Jae; Xu, Yu; Park, Ho Seok

    2015-12-14

    Graphene aerogel is a relatively new type of aerogel that is ideal for energy storage applications because of its large surface area, high electrical conductivity and good chemical stability. Also, three dimensional interconnected macropores offer many advantages such as low density, fast ion and mass transfer, and easy access to storage sites. Such features allow graphene aerogels to be intensively applied for electrochemical capacitor applications. Despite the growing interest in graphene aerogel-based electrochemical capacitors, however, the graphene aerogels still suffer from their low capacitive performances and high fragility. Both relatively low capacitance and brittleness of physically crosslinked graphene aerogels remain a critical challenge. Until now, a number of alternative attempts have been devoted to overcome these shortcomings. In this perspective, we summarize the recent research progress towards the development of advanced graphene aerogel-based electrochemical capacitors according to the different approaches (e.g. porosity, composition and structure controls). Then, the recently proposed chemical strategies to improve the capacitive performances and mechanical durability of graphene aerogels for practical applications are highlighted. Finally, the current challenges and perspectives in this emerging material are also discussed.

  13. Tailoring of morphology and surface properties of syndiotactic polystyrene aerogels.

    Science.gov (United States)

    Wang, Xiao; Jana, Sadhan C

    2013-05-07

    This study evaluates a method for rendering syndiotactic polystyrene (sPS) aerogels hydrophilic using polyethylene oxide (PEO) of different molecular weights. The highly porous sPS aerogels are inherently hydrophobic although applications involving absorption of moisture and removal of particulate solids may benefit from the high surface area of sPS aerogels provided some degree of hydrophilicity is induced in these materials. In this work, sPS gels are prepared by thermo-reversible gelation in tetrahydrofuran in the presence of PEO. The gels are dried under supercritical conditions to obtain aerogels. The aerogels are characterized by scanning electron microscopy, nitrogen-adsorption porosimetry, helium pycnometry, and contact angle measurements. The data reveal that the pore structures and surface energy can be controlled by varying the concentration and molecular weight of PEO and using different cooling rates during thermo-reversible gelation. In the first case, sPS aerogels, aerogels containing PEO of a low molecular weight or low concentration show superhydrophobic surface presenting the "lotus effect". In the second case, PEO at a higher concentration or with higher molecular weight forms phase-separated domains yielding new hydrophilic macropores (>10 μm) in the aerogel structures. These macropores contribute to the superhydrophobic surface with the "petal effect". The cooling rate during gelation shows a strong influence on these two cases.

  14. Carbon aerogels by pyrolysis of TEMPO-oxidized cellulose

    Science.gov (United States)

    Zhang, Sizhao; Feng, Jian; Feng, Junzong; Jiang, Yonggang; Ding, Feng

    2018-05-01

    Although carbon aerogels derived from naturally occurring materials have been developed extensively, a reasonable synthetic approach using cellulose-resource remains unclear. Here, we report a strategy to prepare carbon aerogels originated from cellulose position-selectively oxidized by TEMPO-oxidized process. Contrary to non-TEMPO-oxidized cellulose-derived carbon aerogels (NCCA) with relative loose structure, TEMPO-oxidized cellulose-derived carbon aerogels (TCCA) with tight fibrillar-continuous network are monitored, suggesting the importance of TEMPO-oxidized modification towards creating the architecture of subsequently produced carbon aerogels. TCCA endows a higher BET area despite owning slightly dense bulk density comparing with that of NCCA. The structural texture of TCCA could be maintained in a way in comparison to TEMPO-oxidized cellulose-derived aerogel, due to the integration and aggregation effect by losing the electric double layer repulsion via ionization of the surface carboxyl groups. FTIR and XPS analyses signify the evidence of non-functionalized carbon-skeleton network formation in terms of TCCA. Further, the mechanism concerning the creation of carbon aerogels is also established. These findings not only provide new insights into the production of carbon aerogels but also open up a new opportunity in the field of functional carbon materials.

  15. Characterization of polymer-based monolithic capillary columns by inverse size-exclusion chromatography and mercury-intrusion porosimetry

    NARCIS (Netherlands)

    Urban, J.; Eeltink, S.; Jandera, P.; Schoenmakers, P.J.

    2008-01-01

    Organic-polymer monolithic capillary columns were prepared in fused-silica capillaries by a radical copolymerization reaction of butyl methacrylate and ethylene dimethacrylate monomers in the presence of 1,4-butanediol and 1-propanol as porogen solvents and azobisisobutyronitrile as the initiator.

  16. Silver-Loaded Aluminosilicate Aerogels As Iodine Sorbents

    Energy Technology Data Exchange (ETDEWEB)

    Riley, Brian J. [Pacific Northwest National Laboratory, Richland, Washington 99354, United States; Kroll, Jared O. [Pacific Northwest National Laboratory, Richland, Washington 99354, United States; Peterson, Jacob A. [Pacific Northwest National Laboratory, Richland, Washington 99354, United States; Matyáš, Josef [Pacific Northwest National Laboratory, Richland, Washington 99354, United States; Olszta, Matthew J. [Pacific Northwest National Laboratory, Richland, Washington 99354, United States; Li, Xiaohong [Pacific Northwest National Laboratory, Richland, Washington 99354, United States; Vienna, John D. [Pacific Northwest National Laboratory, Richland, Washington 99354, United States

    2017-09-14

    This paper discusses the development of aluminosilicates aerogels as scaffolds for Ag0 nanoparticles used for chemisorption of I2(g). The starting materials for these scaffolds included both Na-Al-Si-O and Al-Si-O aerogels, both synthesized from metal alkoxides. The Ag0 particles are added by soaking the aerogels in AgNO3 followed by drying and flowing under H2/Ar to reduce Ag+ → Ag0. In some cases, samples were soaked in 3-(mercaptopropyl)trimethoxysilane under supercritical CO2 to add –SH tethers to the aerogel surfaces for more effective binding of Ag+. During the Ag+-impregnation steps, for the Na-Al-Si-O aerogels, Na was replaced with Ag, and for the Al-Si-O aerogel, Si was replaced with Ag. The Ag-loading of thiolated versus non-thiolated Na-Al-Si-O aerogels was comparable at ~35 at% whereas the Ag-loading in unthiolated Al-Si-O aerogels was significantly lower at ~ 7 at% after identical treatment. Iodine loadings in both thiolated and unthiolated Ag0-functionalized Na-Al-Si-O aerogels were > 0.5 g g-1 showing almost complete utilization of the Ag through chemisorption to form AgI. Iodine loading in the thiolated Al-Si-O aerogel was 0.31 g g-1. The control of Ag uptake over solution residence time and [AgNO3] demonstrates the ability to customize the Ag-loading in the base sorbent to regulate the capacity of iodine chemisorption. Consolidation experimental results are also presented.

  17. Development and evaluation of aerogel-filled BMI sandwich panels for thermal barrier applications

    Directory of Open Access Journals (Sweden)

    A. Dineshkumar

    2016-07-01

    Full Text Available This study details a fabrication methodology envisaged to manufacture Glass/BMI honeycomb core aerogel-filled sandwich panels. Silica aerogel granules are used as core fillers to provide thermal insulation properties with little weight increase. Experimental heat transfer studies are conducted on these panels to study the temperature distribution between their two surfaces. Numerical studies are also carried out to validate the results. Despite exhibiting good thermal shielding capabilities, the Glass/BMI sandwich panels are found to oxidise at 180 ºC if exposed directly to heat. In order to increase the temperature bearing capacity and the operating temperature range for these panels, a way of coating them from outside with high temperature spray paint was tried. With a silicone-based coating, the temperature sustainability of these sandwich panels is found to increase to 350 ºC. This proved the effectiveness of the formed manufacturing process, selected high temperature coating, the coating method as well as the envisaged sandwich panel concept.

  18. Structure and properties of hybrid poly(2-hydroxyethyl methacrylate)/SiO2 monoliths

    DEFF Research Database (Denmark)

    Ji, Xiangling; Jiang, Shichun; Qiu, Xuepeng

    2003-01-01

    Abstract: Hybrid poly(2-hydroxyethyl methacrylate) (PHEMA)/SiO2 monoliths were synthesized via a sol-gel process of the precursor tetraethyl orthosilicate (TEOS) and the in situ free-radical polymerization of 2-hydroxyethyl methacrylate (HEMA). The weight ratio of the starting chemicals, TEOS to ...... related to some degree of chemical crosslinking between the polymer and the silica moiety, which would greatly improve the thermal stability of such hybrid monoliths compared with a pure PHEMA....... region, that is, good transparency. Mechanical properties were studied with an Instron tester, and the monoliths exhibited better compressive strength and modulus than did bulk PHEMA. Surprisingly, thermogravimetric analysis (TGA) data showed greater than 50 wt % solid residue up to 700degreesC, possibly...

  19. Highly Insulating and Light Transmitting Aerogel glazing for Window (HILIT Aerogel Window)

    DEFF Research Database (Denmark)

    and to transfer the results from lab- to mid- and finally to large-scale making of 60 by 60 cm2 in a pre-industrial plant. The large samples forms the basis for assembly of evacuated aerogel glazings optimised with respect to thermal and optical properties. The production process development and transfer to pre...... invention of several technical solutions related to moulding and handling of the large gels. Despite the efforts only aerogels with a thickness up to 15 mm have been produced with a good reproducibility. The thermal conductivity is approximately 0.015 W/mK at atmospheric pressure and 0.010 W/mK at 10 h......Pa. The optical properties have been improved compared to previous aerogels thanks to the process and the smooth surfaces obtained and a heat treatment of the dried aerogel. A rim seal solution that offers the required air and moisture tightness without leading to severe thermal bridge effects has been developed...

  20. Acoustic of monolithic dome structures

    Directory of Open Access Journals (Sweden)

    Mostafa Refat Ismail

    2018-03-01

    The interior of monolithic domes have perfect, concave shapes to ensure that sound travels through the dome and perfectly collected at different vocal points. These dome structures are utilized for domestic use because the scale allows the focal points to be positioned across daily life activities, thereby affecting the sonic comfort of the internal space. This study examines the various acoustic treatments and parametric configurations of monolithic dome sizes. A geometric relationship of acoustic treatment and dome radius is established to provide architects guidelines on the correct selection of absorption needed to maintain the acoustic comfort of these special spaces.

  1. Review on recent and advanced applications of monoliths and related porous polymer gels in micro-fluidic devices.

    Science.gov (United States)

    Vázquez, Mercedes; Paull, Brett

    2010-06-04

    This review critically summarises recent novel and advanced achievements in the application of monolithic materials and related porous polymer gels in micro-fluidic devices appearing within the literature over the period of the last 5 years (2005-2010). The range of monolithic materials has developed rapidly over the past decade, with a diverse and highly versatile class of materials now available, with each exhibiting distinct porosities, pore sizes, and a wide variety of surface functionalities. A major advantage of these materials is their ease of preparation in micro-fluidic channels by in situ polymerisation, leading to monolithic materials being increasingly utilised for a larger variety of purposes in micro-fluidic platforms. Applications of porous polymer monoliths, silica-based monoliths and related homogeneous porous polymer gels in the preparation of separation columns, ion-permeable membranes, preconcentrators, extractors, electrospray emitters, micro-valves, electrokinetic pumps, micro-reactors and micro-mixers in micro-fluidic devices are discussed herein. Procedures used in the preparation of monolithic materials in micro-channels, as well as some practical aspects of the micro-fluidic chip fabrication are addressed. Recent analytical/bioanalytical and catalytic applications of the final micro-fluidic devices incorporating monolithic materials are also reviewed. Copyright 2010 Elsevier B.V. All rights reserved.

  2. Iminodiacetic acid functionalised organopolymer monoliths: application to the separation of metal cations by capillary high-performance chelation ion chromatography.

    Science.gov (United States)

    Moyna, Áine; Connolly, Damian; Nesterenko, Ekaterina; Nesterenko, Pavel N; Paull, Brett

    2013-03-01

    Lauryl methacrylate-co-ethylene dimethacrylate monoliths were polymerised within fused silica capillaries and subsequently photo-grafted with varying amounts of glycidyl methacrylate (GMA). The grafted monoliths were then further modified with iminodiacetic acid (IDA), resulting in a range of chelating ion-exchange monoliths of increasing capacity. The IDA functional groups were attached via ring opening of the epoxy group on the poly(GMA) structure. Increasing the amount of attached poly(GMA), via photo-grafting with increasing concentrations of GMA, from 15 to 35%, resulted in a proportional and controlled increase in the complexation capacity of the chelating monoliths. Scanning capacitively coupled contactless conductivity detection (sC(4)D) was used to characterise and verify homogenous distribution of the chelating ligand along the length of the capillaries non-invasively. Chelation ion chromatographic separations of selected transition and heavy metals were carried out, with retention factor data proportional to the concentration of grafted poly(GMA). Average peak efficiencies of close to 5,000 N/m were achieved, with the isocratic separation of Na, Mg(II), Mn(II), Co(II), Cd(II) and Zn(II) possible on a 250-mm-long monolith. Multiple monolithic columns produced to the same recipes gave RSD data for retention factors of ions). The monolithic chelating ion-exchanger was applied to the separation of alkaline earth and transition metal ions spiked in natural and potable waters.

  3. Monolithic and core-shell columns in comprehensive two-dimensional HPLC: a review.

    Science.gov (United States)

    Jandera, Pavel; Hájek, Tomáš; Staňková, Magda

    2015-01-01

    The crucial point affecting the separation time in comprehensive two-dimensional liquid chromatography is the performance of the column used in the second dimension, which should allow highly efficient fast chromatographic separations in the short time available for the analysis of fractions transferred from the first to the second dimension (often 1 min or less). This can be accomplished on short columns packed with sub-2-μm particles, at the cost of very high operation pressure. Core-shell or silica monolithic columns have better permeability, and their use in the second dimension of comprehensive two-dimensional liquid chromatography with conventional liquid chromatography instrumentation is continuously increasing. Monolithic columns based on organic polymer matrices offer a wide selection of stationary phase chemistries, including new hydrophilic interaction liquid chromatography materials, which can be used in the design of novel two-dimensional separations. Some organic polymer monolithic materials offer a dual retention mechanism (reversed-phase hydrophilic interaction liquid chromatography), so a single column can be used in alternating runs for highly orthogonal off-line two-dimensional and even three-dimensional separations. In the present work, the properties of core-shell and silica gel monolithic columns are briefly summarized and their applications in two-dimensional separations of peptides, proteins, oligomer surfactants, fats and oils, carotenoids, phenolic and flavone compounds in plant extracts, food, and beverages are reviewed.

  4. Bridged polysilsesquioxane-based wide-bore monolithic capillary columns for hydrophilic interaction chromatography

    Czech Academy of Sciences Publication Activity Database

    Šesták, Jozef; Moravcová, Dana; Křenková, Jana; Planeta, Josef; Roth, Michal; Foret, František

    2017-01-01

    Roč. 1479, JAN (2017), s. 204-209 ISSN 0021-9673 R&D Projects: GA ČR(CZ) GA14-06319S; GA ČR(CZ) GA16-03749S Institutional support: RVO:68081715 Keywords : silica monolithic column * HILIC * oligosaccharides * nucleosides Subject RIV: CB - Analytical Chemistry, Separation OBOR OECD: Analytical chemistry Impact factor: 3.981, year: 2016

  5. Stardust Interstellar Preliminary Examination IX: High-Speed Interstellar Dust Analog Capture in Stardust Flight-Spare Aerogel

    Science.gov (United States)

    Postberg, F.; Sterken, V.; Achilles, C.; Allen, C.; Bastien, R. K.; Frank, D.; Sandford, S. A.; Zolensky, M. E.; Butterworth, A.; Gainesforth, Z.

    2014-01-01

    The NASA Stardust mission used silica aerogel slabs to slowly decelerate and capture impinging cosmic dust particles for return to Earth. During this process, impact tracks are generated along the trajectory of the particle into the aerogel. It is believed that the morphology and dimensions of these tracks, together with the state of captured grains at track termini, may be linked to the size, velocity, and density of the impacting cosmic dust grain. Here, we present the results of laboratory hypervelocity impact experiments, during which cosmic dust analog particles (diameters of between 0.2 and 0.4 lm), composed of olivine, orthopyroxene, or an organic polymer, were accelerated onto Stardust flight spare low-density (approximately 0.01 g/cu cm) silica aerogel. The impact velocities (3-21 km/s) were chosen to simulate the range of velocities expected during Stardust's interstellar dust (ISD) collection phases. Track lengths and widths, together with the success of particle capture, are analyzed as functions of impact velocity and particle composition, density, and size. Captured terminal particles from low-density organic projectiles become undetectable at lower velocities than those from similarly sized, denser mineral particles, which are still detectable (although substantially altered by the impact process) at 15 km/s. The survival of these terminal particles, together with the track dimensions obtained during low impact speed capture of small grains in the laboratory, indicates that two of the three best Stardust candidate extraterrestrial grains were actually captured at speeds much lower than predicted. Track length and diameters are, in general, more sensitive to impact velocities than previously expected, which makes tracks of particles with diameters of 0.4 lm and below hard to identify at low capture speeds (<10 km/s). Therefore, although captured intact, the majority of the interstellar dust grains returned to Earth by Stardust remain to be found.

  6. Stardust Interstellar Preliminary Examination IX: High-Speed Interstellar Dust Analog Capture in Stardust Flight-Spare Aerogel

    Science.gov (United States)

    Postberg, F.; Sterken, V.; Achilles, C.; Allen, C.; Bastien, R. K.; Frank, D.; Sandford, S. A.; Zolensky, M. E.; Butterworth, A.; Gainesforth, Z.

    2014-01-01

    The NASA Stardust mission used silica aerogel slabs to slowly decelerate and capture impinging cosmic dust particles for return to Earth. During this process, impact tracks are generated along the trajectory of the particle into the aerogel. It is believed that the morphology and dimensions of these tracks, together with the state of captured grains at track termini, may be linked to the size, velocity, and density of the impacting cosmic dust grain. Here, we present the results of laboratory hypervelocity impact experiments, during which cosmic dust analog particles (diameters of between 0.2 and 0.4 lm), composed of olivine, orthopyroxene, or an organic polymer, were accelerated onto Stardust flight spare low-density (approximately 0.01 g/cu cm) silica aerogel. The impact velocities (3-21 km/s) were chosen to simulate the range of velocities expected during Stardust's interstellar dust (ISD) collection phases. Track lengths and widths, together with the success of particle capture, are analyzed as functions of impact velocity and particle composition, density, and size. Captured terminal particles from low-density organic projectiles become undetectable at lower velocities than those from similarly sized, denser mineral particles, which are still detectable (although substantially altered by the impact process) at 15 km/s. The survival of these terminal particles, together with the track dimensions obtained during low impact speed capture of small grains in the laboratory, indicates that two of the three best Stardust candidate extraterrestrial grains were actually captured at speeds much lower than predicted. Track length and diameters are, in general, more sensitive to impact velocities than previously expected, which makes tracks of particles with diameters of 0.4 lm and below hard to identify at low capture speeds (interstellar dust grains returned to Earth by Stardust remain to be found.

  7. High-internal-phase emulsions stabilized by metal-organic frameworks and derivation of ultralight metal-organic aerogels

    Science.gov (United States)

    Zhang, Bingxing; Zhang, Jianling; Liu, Chengcheng; Peng, Li; Sang, Xinxin; Han, Buxing; Ma, Xue; Luo, Tian; Tan, Xiuniang; Yang, Guanying

    2016-02-01

    To design high-internal-phase emulsion (HIPE) systems is of great interest from the viewpoints of both fundamental researches and practical applications. Here we demonstrate for the first time the utilization of metal-organic framework (MOF) for HIPE formation. By stirring the mixture of water, oil and MOF at room temperature, the HIPE stabilized by the assembly of MOF nanocrystals at oil-water interface could be formed. The MOF-stabilized HIPE provides a novel route to produce highly porous metal-organic aerogel (MOA) monolith. After removing the liquids from the MOF-stabilized HIPE, the ultralight MOA with density as low as 0.01 g·cm-3 was obtained. The HIPE approach for MOA formation has unique advantages and is versatile in producing different kinds of ultralight MOAs with tunable porosities and structures.

  8. Monolithic fiber optic sensor assembly

    Science.gov (United States)

    Sanders, Scott

    2015-02-10

    A remote sensor element for spectrographic measurements employs a monolithic assembly of one or two fiber optics to two optical elements separated by a supporting structure to allow the flow of gases or particulates therebetween. In a preferred embodiment, the sensor element components are fused ceramic to resist high temperatures and failure from large temperature changes.

  9. UV-LED photopolymerised monoliths

    Czech Academy of Sciences Publication Activity Database

    Abele, S.; Nie, F.; Foret, František; Paull, B.; Macka, M.

    2008-01-01

    Roč. 133, č. 7 (2008), s. 864-866 ISSN 0003-2654 R&D Projects: GA AV ČR KAN400310651 Institutional research plan: CEZ:AV0Z40310501 Keywords : photopolymerisation * UV-LED * polymethacrylate monolith Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 3.761, year: 2008

  10. Aerogel Insulation Applications for Liquid Hydrogen Launch Vehicle Tanks

    Science.gov (United States)

    Fesmire, J. E.; Sass, J.

    2007-01-01

    Aerogel based insulation systems for ambient pressure environments were developed for liquid hydrogen (LH2) tank applications. Solutions to thermal insulation problems were demonstrated for the Space Shuttle External Tank (ET) through extensive testing at the Cryogenics Test Laboratory. Demonstration testing was performed using a 1/10th scale ET LH2 intertank unit and liquid helium as the coolant to provide the 20 K cold boundary temperature. Cryopumping tests in the range of 20K were performed using both constant mass and constant pressure methods. Long-duration tests (up to 10 hours) showed that the nitrogen mass taken up inside the intertank is reduced by a factor of nearly three for the aerogel insulated case as compared to the un-insulated (bare metal flight configuration) case. Test results including thermal stabilization, heat transfer effectiveness, and cryopumping confirm that the aerogel system eliminates free liquid nitrogen within the intertank. Physisorption (or adsorption) of liquid nitrogen within the fine pore structure of aerogel materials was also investigated. Results of a mass uptake method show that the sorption ratio (liquid nitrogen to aerogel beads) is about 62 percent by volume. A novel liquid nitrogen production method of testing the liquid nitrogen physical adsorption capacity of aerogel beads was also performed to more closely approximate the actual launch vehicle cooldown and thermal stabilization effects within the aerogel material. The extraordinary insulating effectiveness of the aerogel material shows that cryopumping is not an open-cell mass transport issue but is strictly driven by thermal communication between warm and cold surfaces. The new aerogel insulation technology is useful to solve heat transfer problem areas and to augment existing thermal protection systems on launch vehicles. Examples are given and potential benefits for producing launch systems that are more reliable, robust, reusable, and efficient are outlined.

  11. Organic acid catalyzed carbon aerogels with freeze-drying

    Science.gov (United States)

    Xu, Yuelong; Yan, Meifang; Liu, Zhenfa

    2017-09-01

    Carbon aerogels (CAs) were synthesized via a sol-gel process by condensation-polymerization of phloroglucinol, resorcinol and formaldehyde using 2,4-dihydroxybenzoic acid as catalyst with freeze-drying. The effects of the freeze-drying method on the texture and pore structure were studied. Meanwhile the structure of carbon aerogels was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and a surface-area analyzer. The results show that the freeze-drying method and acid catalyst were good for the specific surface area of carbon aerogel, up to 765m2 g-1, and pore size distribution.

  12. Synthesis and Characterization Carbon Nanotubes Doped Carbon Aerogels

    Science.gov (United States)

    Xu, Yuelong; Yan, Meifang; Liu, Zhenfa

    2017-12-01

    Polycondensation of phloroglucinol, resorcinol and formaldehyde with carbon nanotube (CNT) as the additives, using sodium carbonate as the catalyst, leads to the formation of CNT - doped carbon aerogels. The structure of carbon aerogels (CAs) with carbon nanotubes (CNTs) were characterized by X-ray diffraction and scanning electron microscopy. The specific surface area, pore size distribution and pore volume were measured by surface area analyzer. The results show that when the optimum doping dosage is 5%, the specific surface area of CNT - doped carbon aerogel is up to 665 m2 g-1 and exhibit plentiful mesoporous.

  13. Mesoporous aluminosilica monoliths for the adsorptive removal of small organic pollutants.

    Science.gov (United States)

    El-Safty, Sherif A; Shahat, Ahmed; Ismael, Mohamed

    2012-01-30

    Water treatment for the removal of organic or inorganic pollutants has become a serious global issue because of the increasing demand for public health awareness and environmental quality. The current paper, reports the applicability of mesoporous aluminosilica monoliths with three-dimensional structures and aluminum contents with 19≤Si/Al≥1 as effective adsorbents of organic molecules from an aqueous solution. Mesocage cubic Pm3n aluminosilica monoliths were successfully fabricated using a simple, reproducible, and direct synthesis. The acidity of the monoliths significantly increased with increasing amounts of aluminum species in the silica pore framework walls. The batch adsorption of the organic pollutants onto (10 g/L) aluminosilica monoliths was performed in an aqueous solution at various temperatures. These adsorbents exhibit efficient removal of organic pollutants (e.g., aniline, p-chloroaniline, o-aminophenol, and p-nitroaniline) of up to 90% within a short period (in the order of minutes). In terms of proximity adsorption, the functional acid sites and the condensed and rigid monoliths with tunable periodic scaffolds of the cubic mesocages are useful in providing easy-to-use removal assays for organic compounds and reusable adsorbents without any mesostructural damage, even under chemical treatment for a number of repeated cycles. Copyright © 2011 Elsevier B.V. All rights reserved.

  14. Trimethyl-β-cyclodextrin-encapsulated monolithic capillary columns: Preparation, characterization and chiral nano-LC application.

    Science.gov (United States)

    Ghanem, Ashraf; Adly, Frady G; Sokerik, Yasser; Antwi, Nana Yaa; Shenashen, Mohamed A; El-Safty, Sherif A

    2017-07-01

    Trimethylated-β-cyclodextrin (TM-β-CD) was encapsulated within several polymer monolithic capillary columns for reversed-phase chiral nano-liquid chromatography (nano-LC). The monolithic phases were prepared using the one-pot in situ copolymerization of ethylene glycol dimethacrylate (EDMA), glycidyl methacrylate (GMA) monomers and 1-propanol, 1,4-butanediol as progenic solvents in presence of TM-β-CD solution within fused silica capillaries (150µm I.D.). The obtained chiral monolithic stationery phases were characterized by scanning electron microscopy (SEM), N 2 adsorption/desorption isotherms, wide angle x-ray diffraction (WAXRD), thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The materials characterization demonstrated that monolithic phases with higher concentration of TM-β-CD have relatively larger surface area, smaller pore size and larger total pore volume compared to those with lower concentration TM-β-CD. The prepared columns were tested for their enantioseparation efficiency of a range of racemic pharmaceuticals. The screening results demonstrated the potential of functionalizing polymer monolithic stationary phases with TM-β-CD using the in situ encapsulation approach. Crown Copyright © 2016. Published by Elsevier B.V. All rights reserved.

  15. Iodine Adsorption by Ag-Aerogel under Prototypical Vessel Off-Gas Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Bruffey, Stephanie H. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Jubin, Robert Thomas [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-08-01

    U.S. regulations will require the removal of 129I from the off-gas streams of any used nuclear fuel (UNF) reprocessing plant prior to discharge of the off-gas to the environment. The required plant decontamination factor for iodine will vary based on fuel burnup, cooling time, and other factors but is very likely to be >1000 and could be as high as 8000. Multiple off-gas streams within a UNF reprocessing plant combine prior to environmental release, and each of these streams contains some amount of iodine. To achieve the decontamination factors (DFs) that are likely to be required by regulations, iodine removal from the vessel off-gas will be necessary. The vessel off-gas contains iodine at very dilute concentrations (ppb levels), and will also contain water vapor. Iodine species present are likely to include both elemental and organic iodides. There will also be solvent vapors and volatile radiolysis products. The United States has considered the use of silver-based sorbents for removal of iodine from UNF off-gas streams, but little is known about the behavior of those sorbents at very dilute iodine concentrations. The purpose of this study was to expose silver-functionalized silica aerogel (AgAerogel) to a prototypical vessel off-gas stream containing 40 ppb methyl iodide to obtain information about organic iodine capture by silver-sorbents at very low iodine concentrations. The design of this extended duration testing was such that information about the rate of adsorption, the penetration of the iodine species, and the overall system DF could be obtained. Results show that CH3I penetrates into a AgAerogel sorbent bed to a depth of 3.9 cm under prototypical vessel off-gas conditions. An iodine loading of 22 mg I/g AgAerogel was observed in the first 0.3 cm of the bed. Of the iodine delivered to the system, 48% could not be accounted for, and future efforts will investigate this concern. Direct calculation of the decontamination factor is not

  16. Flexible and monolithic zinc oxide bionanocomposite foams by a bacterial cellulose mediated approach for antibacterial applications.

    Science.gov (United States)

    Wang, Peipei; Zhao, Jun; Xuan, Ruifei; Wang, Yun; Zou, Chen; Zhang, Zhiquan; Wan, Yizao; Xu, Yan

    2014-05-14

    The use of self-assembled biomacromolecules in the development of functional bionanocomposite foams is one of the best lessons learned from nature. Here, we show that monolithic, flexible and porous zinc oxide bionanocomposite foams with a hierarchical architecture can be assembled through the mediation of bacterial cellulose. The assembly is achieved by controlled hydrolysis and solvothermal crystallization using a bacterial cellulose aerogel as a template in a non-aqueous polar medium. The bionanocomposite foam with a maximum zinc oxide loading of 70 wt% is constructed of intimately packed spheres of aggregated zinc oxide nanocrystals exhibiting a BET surface area of 92 m(2) g(-1). The zinc oxide bionanocomposite foams show excellent antibacterial activity, which give them potential value as self-supporting wound dressing and water sterilization materials.

  17. Polymer monolith microextraction using poly(butyl methacrylate-co-1,6-hexanediol ethoxylate diacrylate) monolithic sorbent for determination of phenylurea herbicides in water samples.

    Science.gov (United States)

    Lin, Shu-Ling; Wu, Yu-Ru; Fuh, Ming-Ren

    2016-01-15

    In this study, recently developed 1,6-hexanediol ethoxylate diacrylate (HEDA)-based polymeric monoliths were utilized as sorbents for efficient extraction of phenylurea herbicides (PUHs) from water samples. The HEDA-based monolithic sorbents were prepared in a fused silica capillary (0.7mm i.d., 4.5-cm long) for polymer monolith microextraction (PMME). The experimental parameters of PMME microextraction including sample loading speed, pH of sample solution, composition of elution solvent, and addition of salt were optimized to efficiently extract PUHs from environmental water samples. The extracted PUHs were determined using ultra-high performance liquid chromatography (UHPLC) with UV-photodiode array detection. The extraction recoveries for PUHs-spiked water samples were 91.1-108.1% with relative standard deviations lower than 5%. The linearity range was 0.025-25ngmL(-1) for each PUH and the detection limits of PUHs were estimated at 0.006-0.019ng mL(-1). In addition, good intra-day/inter-day precision (0.1-8.7%/0.2-8.9%) and accuracy (92.0-108.0%/96.5-105.2%) of the proposed method were obtained. The extraction capacity of the monolith-filled capillary was also determined to be approximately 1μg. Moreover, each monolith-filled capillary could be reused up to 8 times without carry-over. According to the European Union regulations, the allowed permissible limit of any single herbicide in drinking water is 0.1ng mL(-1). This permissible level fell in the linear range examined in this study. In addition, the proposed method provided detection limits lower than the allowed permissible level, which demonstrated the feasibility of utilizing the HEDA-based monolithic sorbent to perform PMME for determining contaminants, such as PUHs, in environmental application. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. Advances in the development of organic polymer monolithic columns and their applications in food analysis--a review.

    Science.gov (United States)

    Jandera, Pavel

    2013-10-25

    Monolithic continuous separation media are gradually finding their way to sample pre-treatment, isolation, enrichment and final analytical separations of a plethora of compounds, occurring as food components, additives or contaminants, including pharmaceuticals, pesticides and toxins, which have traditionally been the domain of particulate chromatographic materials. In the present review, recent advances in the technology of monolithic columns and the applications in food analysis are addressed. Silica-based monoliths are excellent substitutes to conventional particle-packed columns, improving the speed of analysis for low-molecular weight compounds, due to their excellent efficiency and high permeability. These properties have been recently appreciated in two-dimensional HPLC, where the performance in the second dimension is of crucial importance. Organic-polymer monoliths in various formats provide excellent separations of biopolymers. Thin monolithic disks or rod columns are widely employed in isolation, purification and pre-treatment of sample containing proteins, peptides or nucleic acid fragments. Monolithic capillaries were originally intended for use in electrochromatography, but are becoming more frequently used for capillary and micro-HPLC. Monoliths are ideal highly porous support media for immobilization or imprinting template molecules, to provide sorbents for shape-selective isolation of target molecules from various matrices occurring in food analysis. The separation efficiency of organic polymer monoliths for small molecules can be significantly improved by optimization of polymerization approach, or by post-polymerization modification. This will enable full utilization of a large variety of available monomers to prepare monoliths with chemistry matching the needs of selectivity of separations of various food samples containing even very polar or ionized compounds. Copyright © 2013 Elsevier B.V. All rights reserved.

  19. Multifunctional Aerogel Thermal Protection Systems for Hypersonic Vehicles, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — The overall objective of the Phase II project is to develop lightweight reinforced aerogel materials for use as the core structural insulation material in...

  20. Aerogel Antennas Communications Study Using Error Vector Magnitude Measurements

    Science.gov (United States)

    Miranda, Felix A.; Mueller, Carl H.; Meador, Mary Ann B.

    2014-01-01

    This presentation discusses an aerogel antennas communication study using error vector magnitude (EVM) measurements. The study was performed using 2x4 element polyimide (PI) aerogel-based phased arrays designed for operation at 5 GHz as transmit (Tx) and receive (Rx) antennas separated by a line of sight (LOS) distance of 8.5 meters. The results of the EVM measurements demonstrate that polyimide aerogel antennas work appropriately to support digital communication links with typically used modulation schemes such as QPSK and 4 DQPSK. As such, PI aerogel antennas with higher gain, larger bandwidth and lower mass than typically used microwave laminates could be suitable to enable aerospace-to- ground communication links with enough channel capacity to support voice, data and video links from CubeSats, unmanned air vehicles (UAV), and commercial aircraft.

  1. Acoustic properties of 97% porous aerogel at low temperatures

    International Nuclear Information System (INIS)

    Putselyk, S.; Eska, G.; Abe, S.; Matsumoto, K.

    2003-01-01

    Sound transmission techniques were used to investigate sound velocities and attenuation in an aerogel sample of 3 mm length and 3 mm diameter. This sample was squeezed between a 10 MHz transmitter and receiver quartz. Pulsed measurements were performed during several cool down cycles (300-0.7 K) in vacuum as well as while filling the aerogel with gaseous and liquid 3 He up to 29 bar. The striking features of all experiments were that a profound change of the sound mode in the 3 He-filled aerogel occurs around 5, 8 and 12 bar, and that neither sound velocity nor absorption in the aerogel has been found very reproducible from cool-down to cool-down

  2. Aerogel Scattering Filters for Millimeter and Sub-mm Astrophysics

    Data.gov (United States)

    National Aeronautics and Space Administration — We are developing infrared-blocking filters for millimeter and sub-millimeter astronomy composed of small scattering particles embedded in an aerogel substrate. The...

  3. Preparation and evaluation of poly(alkyl methacrylate-co-methacrylic acid-co-ethylene dimethacrylate) monolithic columns for separating polar small molecules by capillary liquid chromatography.

    Science.gov (United States)

    Lin, Shu-Ling; Wu, Yu-Ru; Lin, Tzuen-Yeuan; Fuh, Ming-Ren

    2015-04-29

    In this study, methacrylic acid (MAA) was incorporated with alkyl methacrylates to increase the hydrophilicity of the synthesized ethylene dimethacrylate-based (EDMA-based) monoliths for separating polar small molecules by capillary LC analysis. Different alkyl methacrylate-MAA ratios were investigated to prepare a series of 30% alkyl methacrylate-MAA-EDMA monoliths in fused-silica capillaries (250-μm i.d.). The porosity, permeability, and column efficiency of the synthesized MAA-incorporated monolithic columns were characterized. A mixture of phenol derivatives is employed to evaluate the applicability of using the prepared monolithic columns for separating small molecules. Fast separation of six phenol derivatives was achieved in 5 min with gradient elution using the selected poly(lauryl methacrylate-co-MAA-co-EDMA) monolithic column. In addition, the effect of acetonitrile content in mobile phase on retention factor and plate height as well as the plate height-flow velocity curves were also investigated to further examine the performance of the selected poly(lauryl methacrylate-co-MAA-co-EDMA) monolithic column. Moreover, the applicability of prepared polymer-based monolithic column for potential food safety applications was also demonstrated by analyzing five aflatoxins and three phenicol antibiotics using the selected poly(lauryl methacrylate-co-MAA-co-EDMA) monolithic column. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. Inverted opal luminescent Ce-doped silica glasses

    Directory of Open Access Journals (Sweden)

    R. Scotti

    2006-01-01

    Full Text Available Inverted opal Ce-doped silica glasses (Ce : Si molar ratio 1 ⋅ 10−3 were prepared by a sol-gel method using opals of latex microspheres as templates. The rare earth is homogeneously dispersed in silica host matrix, as evidenced by the absence of segregated CeO2, instead present in monolithic Ce-doped SG with the same cerium content. This suggests that the nanometric dimensions of bridges and junctions of the host matrix in the inverted opal structures favor the RE distribution avoiding the possible segregation of CeO2.

  5. Effects of Microgravity on the Formation of Aerogels

    Science.gov (United States)

    Hunt, A. J.; Ayers, M. R.; Sibille, L.; Cronise, R. J.; Noever, D. A.

    1999-01-01

    This paper describes research to investigate fundamental aspects of the effects of microgravity on the formation of the microstructure of metal oxide alcogels and aerogels. We are studying the role of gravity on pore structure and gel uniformity in collaboration with Marshall Space Flight Center (MSFC) on gelling systems under microgravity conditions. While this project was just initiated in May 1998, related research performed earlier is described along with the plans and rationale for the current microgravity investigation to provide background and describe newly developing techniques that should be useful for the current gellation studies. The role of gravity in materials processing must be investigated through the study of well-mastered systems. Sol-gel processed materials are near-perfect candidates to determine the effect of gravity on the formation and growth of random clusters from hierarchies of aggregated units. The processes of hydrolysis, condensation, aggregation and gellation in the formation of alcogels are affected by gravity and therefore provide a rich system to study under microgravity conditions. Supercritical drying of the otherwise unstable wet alcogel preserves the alcogel structure produced during sol-gel processing as aerogel. Supercritically dried aerogel provides for the study of material microstructures without interference from the effects of surface tension, evaporation, and solvent flow. Aerogels are microstructured, low density open-pore solids. They have many unusual properties including: transparency, excellent thermal resistance, high surface area, very low refractive index, a dielectric constant approaching that of air, and extremely low sound velocity. Aerogels are synthesized using sol-gel processing followed by supercritical solvent extraction that leaves the original gel structure virtually intact. These studies will elucidate the effects of microgravity on the homogeneity of the microstructure and porosity of aerogel. The

  6. Polyimide-Foam/Aerogel Composites for Thermal Insulation

    Science.gov (United States)

    Williams, Martha; Fesmire, James; Sass, Jared; Smith, Trent; Weoser. Erol

    2009-01-01

    Composites of specific types of polymer foams and aerogel particles or blankets have been proposed to obtain thermal insulation performance superior to those of the neat polyimide foams. These composites have potential to also provide enhanced properties for vibration dampening or acoustic attenuation. The specific type of polymer foam is denoted "TEEK-H", signifying a series, denoted H, within a family of polyimide foams that were developed at NASA s Langley Research Center and are collectively denoted TEEK (an acronym of the inventors names). The specific types of aerogels include Nanogel aerogel particles from Cabot Corporation in Billerica, MA. and of Spaceloft aerogel blanket from Aspen Aerogels in Northborough, MA. The composites are inherently flame-retardant and exceptionally thermally stable. There are numerous potential uses for these composites, at temperatures from cryogenic to high temperatures, in diverse applications that include aerospace vehicles, aircraft, ocean vessels, buildings, and industrial process equipment. Some low-temperature applications, for example, include cryogenic storage and transfer or the transport of foods, medicines, and chemicals. Because of thermal cycling, aging, and weathering most polymer foams do not perform well at cryogenic temperatures and will undergo further cracking over time. The TEEK polyimides are among the few exceptions to this pattern, and the proposed composites are intended to have all the desirable properties of TEEK-H foams, plus improved thermal performance along with enhanced vibration or acoustic-attenuation performance. A composite panel as proposed would be fabricated by adding an appropriate amount of TEEK friable balloons into a mold to form a bottom layer. A piece of flexible aerogel blanket material, cut to the desired size and shape, would then be placed on the bottom TEEK layer and sandwiched between another top layer of polyimide friable balloons so that the aerogel blanket would become

  7. Monolithic pattern-sensitive detector

    Science.gov (United States)

    Berger, Kurt W.

    2000-01-01

    Extreme ultraviolet light (EUV) is detected using a precisely defined reference pattern formed over a shallow junction photodiode. The reference pattern is formed in an EUV absorber preferably comprising nickel or other material having EUV- and other spectral region attenuating characteristics. An EUV-transmissive energy filter is disposed between a passivation oxide layer of the photodiode and the EUV transmissive energy filter. The device is monolithically formed to provide robustness and compactness.

  8. Full scale investigation on aerogel windows exposed to real climatic conditions

    DEFF Research Database (Denmark)

    Schultz, Jørgen Munthe; Nielsen, Lars Thomsen

    The aim of the project “Full scale experiments with aerogel windows exposed to natural conditions” is to test the durability of aerogel windows exposed to real climatic conditions and to investigate the influence of aerogel windows compared to common low-energy windows with respect to heat balance...... and indoor thermal comfort.The influence of temperature and wind load on the durability of sealed glazing units including aerogel windows has been investigated theoretically. The analyses show that evacuated aerogel glazings are significantly more robust to temperature changes and wind load than common...... sealed glazing units, due to the rough vacuum. A non-evacuated aerogel glazing has been mounted in a experimental house for 3 years without any sign of degeneration of the aerogel material.An energy saving of 30% has been found if aerogel windows are used instead of low-energy windows with argon...

  9. Reinforced plastics and aerogels by nanocrystalline cellulose

    Energy Technology Data Exchange (ETDEWEB)

    Leung, Alfred C. W.; Lam, Edmond; Chong, Jonathan; Hrapovic, Sabahudin; Luong, John H. T., E-mail: john.luong@cnrc-nrc.gc.ca [National Research Council Canada (Canada)

    2013-05-15

    Nanocrystalline cellulose (NCC), a rigid rod-like nanoscale material, can be produced from cellulosic biomass in powder, liquid, or gel forms by acid and chemical hydrolysis. Owing to its unique and exceptional physicochemical properties, the incorporation of a small amount of NCC into plastic enhances the mechanical strength of the latter by several orders of magnitudes. Carbohydrate-based NCC poses no serious environmental concerns, providing further impetus for the development and applications of this green and renewable biomaterial to fabricate lightweight and biodegradable composites and aerogels. Surface functionalization of NCC remains the main focus of NCC research to tailor its properties for dispersion in hydrophilic or hydrophobic media. It is of uttermost importance to develop tools and protocols for imaging of NCC in a complex matrix and quantify its reinforcement effect.

  10. Aerogel Cherenkov Counters of the KEDR Detector

    CERN Document Server

    Ovtin, I V; Barnyakov, M Y; Bobrovnikov, V S; Buzykaev, A R; Danilyuk, A F; Katcin, A A; Kononov, S A; Kravchenko, E A; Kuyanov, I A; Onuchin, A P; Rodiakin, V A

    2017-01-01

    The particle identification system of the KEDR detector is based on aerogel threshold Cherenkov counters called ASHIPH counters. The system consists of 160 counters arranged in two layers. An event reconstruction program for the ASHIPH system was developed. The position of each counter relative to the tracking system was determined using cosmic muons and Bhabha events. The geometric efficiency of the ASHIPH system was verified with Bhabha events. The efficiency of relativistic particle detection was measured with cosmic muons. A π/K separation of 4δ in the momentum range 0.95 −1.45 GeV/c was confirmed. A simulation program for the ASHIPH counters has been developed.

  11. Mechanically Strong Aerogels Formed by Templated Growth of Polymer Cross- Linkers on Inorganic Nanoparticles

    Science.gov (United States)

    Leventis, Nicholas; Fabrizio, Eve F.; Johnston, Chris; Meador, Maryann

    2004-01-01

    In the search for materials with better mechanical, thermal, and electrical properties, it is becoming evident that oftentimes dispersing ceramic nanoparticles in plastics improves performance. Along these lines, chemical bonding (both covalent and noncovalent) between a filler and a polymer improves their compatibility, and thus enhances certain properties of the polymeric matrix above and beyond what is accomplished by simple doping with the filler. When a similarly sized dopant and matrix are used, elementary building blocks may also have certain distinct advantages (e.g., in catalysis). In this context, researchers at the NASA Glenn Research Center reasoned that in the extreme case, where the dopant and the matrix (e.g., a filler and a polymer) are not only sized similarly, but their relative amounts are comparable, the relative roles of the dopant and matrix can be reversed. Then, if the "filler," or a certain form thereof, possesses desirable properties of its own, such properties could be magnified by cross-linking with a polymer. We at Glenn have identified silica as such a filler in its lowest-density form, namely the silica aerogel.

  12. Direct Ink Write (DIW) 3D Printed Cellulose Nanocrystal Aerogel Structures

    OpenAIRE

    Li, Vincent Chi-Fung; Dunn, Conner K.; Zhang, Zhe; Deng, Yulin; Qi, H. Jerry

    2017-01-01

    Pure cellulose nanocrystal (CNC) aerogels with controlled 3D structures and inner pore architecture are printed using the direct ink write (DIW) technique. While traditional cellulosic aerogel processing approaches lack the ability to easily fabricate complete aerogel structures, DIW 3D printing followed by freeze drying can overcome this shortcoming and can produce CNC aerogels with minimal structural shrinkage or damage. The resultant products have great potential in applications such as ti...

  13. From Green Aerogels to Porous Graphite by Emulsion Gelation of Acrylonitrile

    Science.gov (United States)

    2012-01-01

    resorcinol with formaldehyde (RF) still remains the prevalent route to C-aerogels,11 despite the long (up to a week) process.12 The resulting C-aerogels... carbonyl carbon at 176.03 ppm). The structure of emulsions as well as of the fundamental building blocks of the resulting aerogel microstructures were...spectra of both E- and H-aerogels show not only resonances assigned (by simulation) to fused pyridines but also to additional carbonyls (Figure 7).52

  14. Affinity monolith chromatography: A review of general principles and applications.

    Science.gov (United States)

    Li, Zhao; Rodriguez, Elliott; Azaria, Shiden; Pekarek, Allegra; Hage, David S

    2017-11-01

    Affinity monolith chromatography, or AMC, is a liquid chromatographic method in which the support is a monolith and the stationary phase is a biological-binding agent or related mimic. AMC has become popular for the isolation of biochemicals, for the measurement of various analytes, and for studying biological interactions. This review will examine the principles and applications of AMC. The materials that have been used to prepare AMC columns will be discussed, which have included various organic polymers, silica, agarose, and cryogels. Immobilization schemes that have been used in AMC will also be considered. Various binding agents and applications that have been reported for AMC will then be described. These applications will include the use of AMC for bioaffinity chromatography, immunoaffinity chromatography, dye-ligand affinity chromatography, and immobilized metal-ion affinity chromatography. The use of AMC with chiral stationary phases and as a tool to characterize biological interactions will also be examined. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Nanoporous Cu-C composites based on carbon-nanotube aerogels

    Energy Technology Data Exchange (ETDEWEB)

    Charnvanichborikarn, S.; Shin, S. J.; Worsley, M. A.; Tran, I. C.; Willey, T. M.; van Buuren, T.; Felter, T. E.; Colvin, J. D.; Kucheyev, S. O. [LLNL; (Sandia)

    2013-11-22

    Current synthesis methods of nanoporous Cu–C composites offer limited control of the material composition, structure, and properties, particularly for large Cu loadings of ≳20 wt%. Here, we describe two related approaches to realize novel nanoporous Cu–C composites based on the templating of recently developed carbon-nanotube aerogels (CNT-CAs). Our first approach involves the trapping of Cu nanoparticles while CNT-CAs undergo gelation. This method yields nanofoams with relatively high densities of ≳65 mg cm-3 for Cu loadings of ≳10 wt%. Our second approach overcomes this limitation by filling the pores of undoped CNT-CA monoliths with an aqueous solution of CuSO4 followed by (i) freeze-drying to remove water and (ii) thermal decomposition of CuSO4. With this approach, we demonstrate Cu–C composites with a C matrix density of -25 mg cm-3 and Cu loadings of up to 70 wt%. These versatile methods could be extended to fabricate other nanoporous metal–carbon composite materials geared for specific applications.

  16. High efficiency polyethylene glycol diacrylate monoliths for reversed-phase capillary liquid chromatography of small molecules.

    Science.gov (United States)

    Aggarwal, Pankaj; Lawson, John S; Tolley, H Dennis; Lee, Milton L

    2014-10-17

    Highly cross-linked monolithic networks (i.e., polyethylene glycol diacrylate, PEGDA) synthesized from monomers containing varying ethylene oxide chain lengths were fabricated inside fused silica capillary columns for use in liquid chromatography (LC) of small molecules. Tergitol was used as a surfactant porogen in combination with other typical organic liquid porogens. Column performance was correlated with quantitative descriptors of the physical/chemical properties of the monomers and porogens using a statistical model. Solubility and viscosity values of the components were identified as important predictors of monolith morphology and efficiency. The chromatographic retention mechanism was determined to be principally reversed-phase (RP) with additional hydrogen bonding between the polar groups of the analytes and the ethylene oxide groups embedded in the monolith structure. The fabricated monolithic columns were evaluated under RPLC conditions using phenols, hydroxy benzoic acids, and alkyl parabens as test compounds. Isocratic elution of hydroxy benzoic acids at a linear velocity of 0.04 cm/s using a PEGDA-700 monolith gave chromatographic peaks with little tailing (i.e., tailing factorcolumn was 186,000 plates/m when corrected for injector dead volume. High resolution gradient separations of selected pharmaceutical compounds and phenylurea herbicides were achieved in less than 18 min. Optimized monoliths synthesized from all four crosslinking monomers exhibited high permeability and demonstrated little swelling or shrinking in different polarity solvents. Column preparation was highly reproducible, with relative standard deviation (RSD) values less than 2.1%, based on retention times of the phenol standards (3 different columns). Copyright © 2014 Elsevier B.V. All rights reserved.

  17. A monolithic silicon detector telescope

    International Nuclear Information System (INIS)

    Cardella, G.; Amorini, F.; Cabibbo, M.; Di Pietro, A.; Fallica, G.; Franzo, G.; Figuera, P.; Papa, M.; Pappalardo, G.; Percolla, G.; Priolo, F.; Privitera, V.; Rizzo, F.; Tudisco, S.

    1996-01-01

    An ultrathin silicon detector (1 μm) thick implanted on a standard 400 μm Si-detector has been built to realize a monolithic telescope detector for simultaneous charge and energy determination of charged particles. The performances of the telescope have been tested using standard alpha sources and fragments emitted in nuclear reactions with different projectile-target colliding systems. An excellent charge resolution has been obtained for low energy (less than 5 MeV) light nuclei. A multi-array lay-out of such detectors is under construction to charge identify the particles emitted in reactions induced by low energy radioactive beams. (orig.)

  18. Imaging monolithic silicon detector telescopes

    International Nuclear Information System (INIS)

    Amorini, F.; Sipala, V.; Cardella, G.; Boiano, C.; Carbone, B.; Cosentino, L.; Costa, E.; Di Pietro, A.; Emanuele, U.; Fallica, G.; Figuera, P.; Finocchiaro, P.; La Guidara, E.; Marchetta, C.; Pappalardo, A.; Piazza, A.; Randazzo, N.; Rizzo, F.; Russo, G.V.; Russotto, P.

    2008-01-01

    We show the results of some test beams performed on a new monolithic strip silicon detector telescope developed in collaboration with the INFN and ST-microelectronics. Using an appropriate design, the induction on the ΔE stages, generated by the charge released in the E stage, was used to obtain the position of the detected particle. The position measurement, together with the low threshold for particle charge identification, allows the new detector to be used for a large variety of applications due to its sensitivity of only a few microns measured in both directions

  19. Monolithic media for applications in affinity chromatography.

    Science.gov (United States)

    Sproß, Jens; Sinz, Andrea

    2011-08-01

    Affinity chromatography presents a highly versatile analytical tool, which relies on exploiting highly specific interactions between molecules and their ligands. This review covers the most recent literature on the application of monoliths as stationary phases for various affinity-based chromatographic applications. Different affinity approaches as well as separations using molecularly imprinted monoliths are discussed. Hybrid stationary phases created by embedding of particles or nanoparticles into a monolithic stationary phase are also considered in this review article. The ease of preparation of monoliths and the multitude of functionalization techniques, which have matured during the past years, make monoliths interesting for an increasing number of biochemical and medical applications. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Applications of monolithic materials for sample preparation.

    Science.gov (United States)

    Nema, Tarang; Chan, Eric C Y; Ho, Paul C

    2014-01-01

    Recent advances in monolithic columns have made them an alternative to traditional packed columns used in liquid chromatography as well as capillary electrochromatography (CEC). The monolithic columns have been extensively studied and shown to possess several advantages that make them a promising and potential substitute for the particle packed columns. A large number of papers relating to monolithic columns have been published every year, focusing on different preparation techniques, characteristic evaluations as well as applications. This review highlighted the latest development of monoliths for other modes of analytical chemistry. In particular, this review will highlight the application of monoliths for sample preparation which is an important step of the entire analysis. Copyright © 2013 Elsevier B.V. All rights reserved.

  1. Fabrication of Graphene Aerogels with Heavily Loaded Metallic Nanoparticles

    Directory of Open Access Journals (Sweden)

    Chen Shen

    2017-02-01

    Full Text Available Natural biomaterials with hierarchical structures that enable extraordinary capability of detecting chemicals have inspired the interest in producing materials that can mimic these natural structures. This study reports the fabrication of hierarchically-structured, reduced graphene oxide (rGO aerogels with heavily loaded palladium (Pd, platinum (Pt, nickel (Ni, and tin (Sn metallic nanoparticles. Metal salts chelated with ethylenediaminetetraacetic acid (EDTA were mixed with graphene oxide (GO and then freeze-dried. The subsequent reduction produces rGO/metal nanoparticle aerogels. SEM and EDS results indicated that a loading of 59, 67, 39, and 46 wt % of Pd, Pt, Ni, and Sn nanoparticles was achieved. Pd/rGO aerogels of different Pd nanoparticle concentrations were exposed to H2 gas to monitor the resistance change of the composites. The results suggest that rGO aerogels can achieve a higher nanoparticle loading by using chelation to minimize electrostatic interactions between metal ions and GO. Higher loading of Pd nanoparticles in graphene aerogels lead to improved hydrogen gas sensing performance.

  2. Low-Density, Aerogel-Filled Thermal-Insulation Tiles

    Science.gov (United States)

    Santos, Maryann; Heng, Vann; Barney, Andrea; Oka, Kris; Droege, Michael

    2005-01-01

    Aerogel fillings have been investigated in a continuing effort to develop low-density thermal-insulation tiles that, relative to prior such tiles, have greater dimensional stability (especially less shrinkage), equal or lower thermal conductivity, and greater strength and durability. In preparation for laboratory tests of dimensional and thermal stability, prototypes of aerogel-filled versions of recently developed low-density tiles have been fabricated by impregnating such tiles to various depths with aerogel formations ranging in density from 1.5 to 5.6 lb/ft3 (about 53 to 200 kg/cu m). Results available at the time of reporting the information for this article showed that the thermal-insulation properties of the partially or fully aerogel- impregnated tiles were equivalent or superior to those of the corresponding non-impregnated tiles and that the partially impregnated tiles exhibited minimal (tiles containing aerogels at the higher end of the density range are stable after multiple exposures at the said temperature.

  3. Van der Waal Interactions in Ultrafine Nanocellulose Aerogels

    Science.gov (United States)

    Fritch, Byron; Bradley, Derek; Kidd, Tim

    Nanocellulose aerogels have shown an ability to be used in many different applications ranging from oil sponges to conductive materials to possibly a low calorie food substitute. Not much is known about the structural and physical property changes that occur when the composition of the aerogel changes. We studied what properties change when the aerogel amounts change, as well as how sticky the aerogels are and how strong they are. The higher concentrations appeared to have more plate-like structures while the lower concentrations had a more fibrous material. These fibers in the low concentrations had a smaller diameter than a human hair. Only the low concentration aerogels were able to stick to a glass surface in the adhesion test, but were able to support a mass much larger than their own. These low concentrations also would stick to your finger when lightly touched. Preliminary tests show that a concentration that is not too low, but not too high, is best for tensile strength. All concentrations were able to hold many times their own mass. Cellulose should be studied more because it is a renewable material and is easily accessed. Nanocellulose is also not environmentally dangerous allowing it to be used in applications involving humans and the environment like noted above. National Science Foundation Grant DMR-1410496.

  4. Extraction of amino acids from aerogel for analysis by capillary electrophoresis. Implications for a mission concept to Enceladus' Plume.

    Science.gov (United States)

    Mora, Maria F; Jones, Steve M; Creamer, Jessica; Willis, Peter A

    2018-02-01

    Ocean worlds like Europa and Enceladus in the outer solar system are prime targets in the search for life beyond Earth. Enceladus is particularly interesting due to the presence of a water plume ejecting from the south polar region. The recent discovery of H 2 in the plume, in addition to the presence of previously observed organic compounds, highlights the possibility of life in this moon. The plume provides materials from the underlying ocean that could be collected simply by flying through it. The presence of the plume means that material from the ocean is available for collection during a flyby, without the need for landing or complex sample handling operations such as scooping or drilling. An attractive approach to preserve the organics in particles collected during flyby encounters would be to utilize silica aerogel, the material used to collect particles at hypervelocity during the Stardust mission. Here we demonstrate amino acids can be extracted from aerogel simply by adding water. This simple liquid extraction method could be implemented during a mission prior to analysis with a liquid-based technique like capillary electrophoresis. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Aerogel Hybrid Composite Materials: Designs and Testing for Multifunctional Applications

    Science.gov (United States)

    Williams, Martha K.; Fesmire, James E.

    2016-01-01

    This webinar will introduce the broad spectrum of aerogel composites and their diverse performance properties such as reduced heat transfer to energy storage, and expands specifically on the aerogel/fiber laminate systems and testing methodologies. The multi-functional laminate composite system, AeroFiber, and its construction is designed by varying the type of fiber (e.g. polyester, carbon, Kevlar®, Spectra® or Innegral(TradeMark) and combinations thereof), the aerogel panel type and thickness, and overall layup configuration. The combination and design of materials may be customized and tailored to achieve a range of desired properties in the resulting laminate system. Multi-functional properties include structural strength, impact resistance, reduction in heat transfer, increased fire resistance, mechanical energy absorption, and acoustic energy dampening. Applications include aerospace, aircraft, automotive, boating, building and construction, lightweight portable structures, liquefied natural gas, cryogenics, transportation and energy, sporting equipment, and military protective gear industries.

  6. Aerogel-Based Insulation for Industrial Steam Distribution Systems

    Energy Technology Data Exchange (ETDEWEB)

    John Williams

    2011-03-30

    Thermal losses in industrial steam distribution systems account for 977 trillion Btu/year in the US, more than 1% of total domestic energy consumption. Aspen Aerogels worked with Department of Energy’s Industrial Technologies Program to specify, develop, scale-up, demonstrate, and deliver Pyrogel XT®, an aerogel-based pipe insulation, to market to reduce energy losses in industrial steam systems. The product developed has become Aspen’s best selling flexible aerogel blanket insulation and has led to over 60 new jobs. Additionally, this product has delivered more than ~0.7 TBTU of domestic energy savings to date, and could produce annual energy savings of 149 TBTU by 2030. Pyrogel XT’s commercial success has been driven by it’s 2-4X better thermal performance, improved durability, greater resistance to corrosion under insulation (CUI), and faster installation times than incumbent insulation materials.

  7. Ultrasound propagation in dense aerogels filled with liquid 4He

    International Nuclear Information System (INIS)

    Matsumoto, K; Ohmori, K; Abe, S; Kanamori, K; Nakanishi, K

    2012-01-01

    Longitudinal ultrasound propagation was studied in dense aerogels filled with liquid 4 He. Sound velocity and attenuation were measured at the frequency of 6 MHz in both normal and superfluid phases. Pressure dependence of velocity and attenuation were also studied. Studied aerogels had porosities about 85%. They had two different types of structure, tangled strand structure and aggregated particles structure. The pore size distributions were narrow. Reduction of superfluid transition temperature mainly depended on not porosity but mean pore size. The structure of gel played an important role in sound velocity and attenuation.

  8. System and method for 3D printing of aerogels

    Science.gov (United States)

    Worsley, Marcus A.; Duoss, Eric; Kuntz, Joshua; Spadaccini, Christopher; Zhu, Cheng

    2016-03-08

    A method of forming an aerogel. The method may involve providing a graphene oxide powder and mixing the graphene oxide powder with a solution to form an ink. A 3D printing technique may be used to write the ink into a catalytic solution that is contained in a fluid containment member to form a wet part. The wet part may then be cured in a sealed container for a predetermined period of time at a predetermined temperature. The cured wet part may then be dried to form a finished aerogel part.

  9. Formation and pore structure of boron nitride aerogels

    International Nuclear Information System (INIS)

    Lindquist, D.H.; Borek, T.T.; Kramer, S.J.; Kramer, S.J.; Naruta, C.K.; Johnson, G.; Schaeffer, R.; Smith, D.M.; Paine, R.T.

    1990-01-01

    This paper reports gels containing a poly(borazinyl amine) and tetrahydrofuran processed by CO 2 supercritical drying techniques followed by pyrolysis. The resulting BN ceramic aerogels are highly porous, and the microstructure, porosity, and surface area characteristics have been examined. The aerogels show excellent thermal stability exhibiting surface areas in excess of 350 m 2 /g and porosities greater than 0.8 even when heated in argon at 1500 degrees C for 8 h. By removing solvent via evaporation before supercritical drying, the mean pore radius can be varied between 3.6 and 10 nm

  10. Preparation and application of hydrophilic monolithic columns.

    Science.gov (United States)

    Jiang, Zhengjin; Smith, Norman William; Liu, Zhenghua

    2011-04-29

    Hydrophilic interaction chromatography (HILIC) has experienced increasing attention in recent years. Much research has been carried out in the area of HILIC separation mechanisms, column techniques and applications. Because of their good permeability, low resistance to mass transfer and easy preparation within capillaries, hydrophilic monolithic columns represent a trend among novel HILIC column techniques. This review attempts to present an overview of the preparation and applications of HILIC monolithic columns carried out in the past decade. The separation mechanism of various hydrophilic monolithic stationary phases is also reviewed. Copyright © 2011 Elsevier B.V. All rights reserved.

  11. Ring-opening metathesis polymerization for the preparation of norbornene-based weak cation-exchange monolithic capillary columns.

    Science.gov (United States)

    Gatschelhofer, Christina; Mautner, Agnes; Reiter, Franz; Pieber, Thomas R; Buchmeiser, Michael R; Sinner, Frank M

    2009-03-27

    Functionalized monolithic columns were prepared via ring-opening metathesis polymerization (ROMP) within silanized fused silica capillaries with an internal diameter of 200 microm by in situ grafting. This procedure is conducted in two steps, the first of which is the formation of the basic monolithic structure by polymerization of norborn-2-ene (NBE) and 1,4,4a,5,8,8a-hexahydro-1,4,5,8-exo,endo-dimethanonaphthalene (DMN-H6) in a porogenic system (toluene and 2-propanol) using RuCl(2)(PCy(3))(2)(CHPh) as ROMP initiator. In the second step the still active initiator sites located on the surface of the structure-forming microglobules were used as receptor groups for the attachment ("grafting") of functional groups onto the monolithic backbone by flushing the monolith with 7-oxanorborn-2-ene-5,6-carboxylic anhydride (ONDCA). Functionalization conditions were first defined that did not damage the backbone of low polymer content (20%) monoliths allowing high-throughput chromatographic separations. Variation of the functionalization conditions was then shown to provide a means of controlling the degree of functionalization and resulting ion-exchange capacity. The maximum level of in situ ONDCA grafting was obtained by a 3h polymerization in toluene at 40 degrees C. The weak cation-exchange monoliths obtained provided good separation of a standard peptide mixture comprising four synthetic peptides designed specifically for the evaluation of cation-exchange columns. An equivalent separation was also achieved using the lowest capacity column studied, indicative of a high degree of robustness of the functionalization procedure. As well as demonstrably bearing ionic functional groups enabling analyte separation in the cation-exchange mode, the columns exhibited additional hydrophobic characteristics which influenced the separation process. The functionalized monoliths thus represent useful tools for mixed-mode separations.

  12. Monolithically Integrated Fiber Optic Coupler

    Science.gov (United States)

    2013-01-14

    single fused fiber 52 and drawn into ferrule 54 in order to provide an output as a photonic crystal fiber (PCF) or photonic bandgap ( PBG ) fiber 56...the reduced diameter air-silica photonic crystal fiber 56 (PCF) or photonic band gap ( PBG ), which is connected by a continuous transition of the... PBG 56 with a negative index of refraction includes metamaterials of superlattices formed by metal nanoparticles. The binary superlattices are

  13. Monolithic cells for solar fuels.

    Science.gov (United States)

    Rongé, Jan; Bosserez, Tom; Martel, David; Nervi, Carlo; Boarino, Luca; Taulelle, Francis; Decher, Gero; Bordiga, Silvia; Martens, Johan A

    2014-12-07

    Hybrid energy generation models based on a variety of alternative energy supply technologies are considered the best way to cope with the depletion of fossil energy resources and to limit global warming. One of the currently missing technologies is the mimic of natural photosynthesis to convert carbon dioxide and water into chemical fuel using sunlight. This idea has been around for decades, but artificial photosynthesis of organic molecules is still far away from providing real-world solutions. The scientific challenge is to perform in an efficient way the multi-electron transfer reactions of water oxidation and carbon dioxide reduction using holes and single electrons generated in an illuminated semiconductor. In this tutorial review the design of photoelectrochemical (PEC) cells that combine solar water oxidation and CO2 reduction is discussed. In such PEC cells simultaneous transport and efficient use of light, electrons, protons and molecules has to be managed. It is explained how efficiency can be gained by compartmentalisation of the water oxidation and CO2 reduction processes by proton exchange membranes, and monolithic concepts of artificial leaves and solar membranes are presented. Besides transferring protons from the anode to the cathode compartment the membrane serves as a molecular barrier material to prevent cross-over of oxygen and fuel molecules. Innovative nano-organized multimaterials will be needed to realise practical artificial photosynthesis devices. This review provides an overview of synthesis techniques which could be used to realise monolithic multifunctional membrane-electrode assemblies, such as Layer-by-Layer (LbL) deposition, Atomic Layer Deposition (ALD), and porous silicon (porSi) engineering. Advances in modelling approaches, electrochemical techniques and in situ spectroscopies to characterise overall PEC cell performance are discussed.

  14. Chromatographic selectivity of poly(alkyl methacrylate-co-divinylbenzene) monolithic columns for polar aromatic compounds by pressure-driven capillary liquid chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Shu-Ling; Wang, Chih-Chieh; Fuh, Ming-Ren, E-mail: msfuh@scu.edu.tw

    2016-10-05

    In this study, divinylbenzene (DVB) was used as the cross-linker to prepare alkyl methacrylate (AlMA) monoliths for incorporating π-π interactions between the aromatic analytes and AlMA-DVB monolithic stationary phases in capillary LC analysis. Various AlMA/DVB ratios were investigated to prepare a series of 30% AlMA-DVB monolithic stationary phases in fused-silica capillaries (250-μm i.d.). The physical properties (such as porosity, permeability, and column efficiency) of the synthesized AlMA-DVB monolithic columns were investigated for characterization. Isocratic elution of phenol derivatives was first employed to evaluate the suitability of the prepared AlMA-DVB columns for small molecule separation. The run-to-run (0.16–1.20%, RSD; n = 3) and column-to-column (0.26–2.95%, RSD; n = 3) repeatabilities on retention times were also examined using the selected AlMA-DVB monolithic columns. The π-π interactions between the aromatic ring and the DVB-based stationary phase offered better recognition on polar analytes with aromatic moieties, which resulted in better separation resolution of aromatic analytes on the AlMA-DVB monolithic columns. In order to demonstrate the capability of potential environmental and/or food safety applications, eight phenylurea herbicides with single benzene ring and seven sulfonamide antibiotics with polyaromatic moieties were analyzed using the selected AlMA-DVB monolithic columns. - Highlights: • First investigation on chromatographic selectivity of AlMA-DVB monolithic columns. • Good run-to-run/column-to-column repeatability (<3%) on AlMA-DVB monolithic columns. • Efficient separation of phenylurea herbicides and sulfonamides on AlMA-DVB columns.

  15. Preparation and evaluation of poly(alkyl methacrylate-co-methacrylic acid-co-ethylene dimethacrylate) monolithic columns for separating polar small molecules by capillary liquid chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Shu-Ling; Wu, Yu-Ru; Lin, Tzuen-Yeuan; Fuh, Ming-Ren, E-mail: msfuh@scu.edu.tw

    2015-04-29

    Highlights: • Methacrylic acid (MAA) was used to increase hydrophilicity of polymeric monoliths. • Fast separation of phenol derivatives was achieved in 5 min using MAA-incorporated column. • Separations of aflatoxins and phenicol antibiotics were achieved using MAA-incorporated column. - Abstract: In this study, methacrylic acid (MAA) was incorporated with alkyl methacrylates to increase the hydrophilicity of the synthesized ethylene dimethacrylate-based (EDMA-based) monoliths for separating polar small molecules by capillary LC analysis. Different alkyl methacrylate–MAA ratios were investigated to prepare a series of 30% alkyl methacrylate–MAA–EDMA monoliths in fused-silica capillaries (250-μm i.d.). The porosity, permeability, and column efficiency of the synthesized MAA-incorporated monolithic columns were characterized. A mixture of phenol derivatives is employed to evaluate the applicability of using the prepared monolithic columns for separating small molecules. Fast separation of six phenol derivatives was achieved in 5 min with gradient elution using the selected poly(lauryl methacrylate-co-MAA-co-EDMA) monolithic column. In addition, the effect of acetonitrile content in mobile phase on retention factor and plate height as well as the plate height-flow velocity curves were also investigated to further examine the performance of the selected poly(lauryl methacrylate-co-MAA-co-EDMA) monolithic column. Moreover, the applicability of prepared polymer-based monolithic column for potential food safety applications was also demonstrated by analyzing five aflatoxins and three phenicol antibiotics using the selected poly(lauryl methacrylate-co-MAA-co-EDMA) monolithic column.

  16. Green synthesis of hybrid graphene oxide/microcrystalline cellulose aerogels and their use as superabsorbents

    International Nuclear Information System (INIS)

    Wei, Xiao; Huang, Ting; Yang, Jing-hui; Zhang, Nan; Wang, Yong; Zhou, Zuo-wan

    2017-01-01

    Highlights: • Hybrid GO/MCC aerogels were prepared using LiBr aqueous solution as the solvent. • GO was exfoliated by MCC through the strong interaction between them. • The adsorption ability of GO per unit mass in the hybrid aerogels was greatly enhanced. - Abstract: In this work, we developed a green synthesis method to prepare the hybrid aerogels containing graphene oxide (GO) and microcrystalline cellulose (MCC) using lithium bromide (LiBr) aqueous solution as the solvent, which insured the complete dissolution of MCC. The interaction between GO and MCC was investigated through different methods The results demonstrate that there is a strong interaction between GO and MCC molecules, which promotes the exfoliation of GO in the hybrid aerogels. The hybrid GO/MCC aerogels exhibit typical three dimensional porous structure and the pore morphology can be well adjusted by changing the content of GO. The adsorption ability of the hybrid aerogels was measured using methylene blue (MB) as an adsorbate. The results show that the adsorption ability of GO per unit mass is greatly enhanced compared with the pure GO aerogel, especially at relatively low GO content the adsorption amount of GO per unit mass is enhanced up to 2630 mg/g. Further results demonstrate that the hybrid GO/MCC aerogels still obey the pseudo-second-order adsorption model, which is similar to that of the pure GO aerogel. The mechanism for the amplified adsorption ability of GO in the hybrid GO/MCC aerogels is then analyzed.

  17. Synthesis of ZnO-CuO Nanocomposite Aerogels by the Sol-Gel Route

    Directory of Open Access Journals (Sweden)

    Rula M. Allaf

    2014-01-01

    Full Text Available The epoxide addition sol-gel method has been utilized to synthesize porous zinc-copper composite aerogels in the zinc-to-copper molar ratios of 50 : 50 to 90 : 10. A two-step mixing approach has been employed to produce aerogels composed of nano- to micrometer sized particles. The aerogels were characterized by ultrahigh resolution scanning electron microscopy, transmission electron microscopy, and powder X-ray diffraction. The as-synthesized aerogels had a thin flake- or petal-like microstructure comprised of clustered flakes on two size scales; they were identified as being crystalline with the crystalline species identified as copper nitrate hydroxide, zinc hydroxide chloride hydrate, and zinc hydroxide nitrate hydrate. Annealing of the aerogel materials at a relatively low temperature (400°C resulted in a complete phase transition of the material to give highly crystalline ZnO-CuO aerogels; the aerogels consisted of networked nanoparticles in the ~25–550 nm size range with an average crystallite size of ~3 nm and average crystallinity of 98%. ZnO-CuO aerogels are of particular interest due to their particular catalytic and sensing properties. This work emphasizes the versatility of this sol-gel route in synthesizing aerogels; this method offers a possible route for the fabrication of aerogels of different metal oxides and their composites.

  18. Green synthesis of hybrid graphene oxide/microcrystalline cellulose aerogels and their use as superabsorbents

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Xiao; Huang, Ting; Yang, Jing-hui; Zhang, Nan; Wang, Yong, E-mail: yongwang1976@163.com; Zhou, Zuo-wan

    2017-08-05

    Highlights: • Hybrid GO/MCC aerogels were prepared using LiBr aqueous solution as the solvent. • GO was exfoliated by MCC through the strong interaction between them. • The adsorption ability of GO per unit mass in the hybrid aerogels was greatly enhanced. - Abstract: In this work, we developed a green synthesis method to prepare the hybrid aerogels containing graphene oxide (GO) and microcrystalline cellulose (MCC) using lithium bromide (LiBr) aqueous solution as the solvent, which insured the complete dissolution of MCC. The interaction between GO and MCC was investigated through different methods The results demonstrate that there is a strong interaction between GO and MCC molecules, which promotes the exfoliation of GO in the hybrid aerogels. The hybrid GO/MCC aerogels exhibit typical three dimensional porous structure and the pore morphology can be well adjusted by changing the content of GO. The adsorption ability of the hybrid aerogels was measured using methylene blue (MB) as an adsorbate. The results show that the adsorption ability of GO per unit mass is greatly enhanced compared with the pure GO aerogel, especially at relatively low GO content the adsorption amount of GO per unit mass is enhanced up to 2630 mg/g. Further results demonstrate that the hybrid GO/MCC aerogels still obey the pseudo-second-order adsorption model, which is similar to that of the pure GO aerogel. The mechanism for the amplified adsorption ability of GO in the hybrid GO/MCC aerogels is then analyzed.

  19. Optimization of monolithic columns for microfluidic devices

    Science.gov (United States)

    Pagaduan, Jayson V.; Yang, Weichun; Woolley, Adam T.

    2011-06-01

    Monolithic columns offer advantages as solid-phase extractors because they offer high surface area that can be tailored to a specific function, fast mass transport, and ease of fabrication. Porous glycidyl methacrylate-ethylene glycol dimethacrylate monoliths were polymerized in-situ in microfluidic devices, without pre-treatment of the poly(methyl methacrylate) channel surface. Cyclohexanol, 1-dodecanol and Tween 20 were used to control the pore size of the monoliths. The epoxy groups on the monolith surface can be utilized to immobilize target-specific probes such as antibodies, aptamers, or DNA for biomarker detection. Microfluidic devices integrated with solid-phase extractors should be useful for point-of-care diagnostics in detecting specific biomarkers from complex biological fluids.

  20. MONOLITHIC DISK FOR THE FAST CHROMATOGRAPHIC SEPARATION

    Directory of Open Access Journals (Sweden)

    Nurul Hidayat Aprilita

    2010-06-01

    Full Text Available Poly(styrene/divinylbenzene (PS/DVB monolithic disk was prepared by in situ free-radical copolymerization of styrene and divinylbenzene in the presence of decanol and tetrahydrofuran as porogens. PS/DVB monolithic disks were produced in two different lengths 1.5 mm and 3 mm. The disks were used in reversed phase chromatography of proteins with 0.2 % trifuoroacetic acid (TFA and 0.2 % TFA in acetonitrile as mobile phase A and B, respectively. The effect of gradient rate, flow rate, temperature and disk length on the separation of proteins were also studied. PS/DVB monolithic disks allow the rapid separation of proteins in reversed phase chromatography. Keywords: monolithic disk, poly(styrene/divinylbenzene, proteins

  1. Monolithic Time Delay Integrated APD Arrays Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The overall goal of the proposed program by Epitaxial Technologies is to develop monolithic time delay integrated avalanche photodiode (APD) arrays with sensitivity...

  2. Silicateins--a novel paradigm in bioinorganic chemistry: enzymatic synthesis of inorganic polymeric silica.

    Science.gov (United States)

    Müller, Werner E G; Schröder, Heinz C; Burghard, Zaklina; Pisignano, Dario; Wang, Xiaohong

    2013-05-03

    The inorganic matrix of the siliceous skeletal elements of sponges, that is, spicules, is formed of amorphous biosilica. Until a decade ago, it remained unclear how the hard biosilica monoliths of the spicules are formed in sponges that live in a silica-poor (inorganic polymer from an inorganic monomeric substrate. In the present review the successive steps, following the synthesis of the silicatein product, biosilica, and resulting in the formation of the hard monolithic spicules is given. The new insight is assumed to open new horizons in the field of biotechnology and also in biomedicine. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Wideband Monolithic Tile for Reconfigurable Phased Arrays

    Science.gov (United States)

    2017-03-01

    Wideband Monolithic Tile for Reconfigurable Phased Arrays James J. Komiak1, Ryan S. Westafer2, Nancy V. Saldanha2, Randall Lapierre1, R. Todd...Lee2 BAE Systems Electronic Systems1, Georgia Tech Research Institute2 Abstract: A Wideband Monolithic 6 x 6 Tile of interconnected Quad Switches...circuits. The Tile incorporates 36 such Quad Switches, having 288 PHEMT devices controlled by 144 control lines and 300 bias resistors. To the

  4. Decomposition of monolithic web application to microservices

    OpenAIRE

    Zaymus, Mikulas

    2017-01-01

    Solteq Oyj has an internal Wellbeing project for massage reservations. The task of this thesis was to transform the monolithic architecture of this application to microservices. The thesis starts with a detailed comparison between microservices and monolithic application. It points out the benefits and disadvantages microservice architecture can bring to the project. Next, it describes the theory and possible strategies that can be used in the process of decomposition of an existing monoli...

  5. Monolithic ceramic capacitors for high reliability applications

    Science.gov (United States)

    Thornley, E. B.

    1981-01-01

    Monolithic multi-layer ceramic dielectric capacitors are widely used in high reliability applications in spacecraft, launch vehicles, and military equipment. Their relatively low cost, wide range of values, and package styles are attractive features that result in high usage in electronic circuitry in these applications. Design and construction of monolithic ceramic dielectric capacitors, defects that can lead to failure, and methods for defect detection that are being incorporated in military specifications are discussed.

  6. A monolithically integrated magneto-optoelectronic circuit

    Science.gov (United States)

    Saha, D.; Basu, D.; Bhattacharya, P.

    2008-11-01

    The monolithic integration of a spin valve, an amplifier, and a light emitting diode to form a magneto-optoelectronic integrated circuit on GaAs is demonstrated. The circuit converts the spin polarization information in the channel of the spin valve to an amplified change in light intensity with a gain of 20. The monolithic circuit therefore operates as a magnetoelectronic switch which modulates the light intensity of the light emitting diode.

  7. Study on Thermal Conductivities of Aromatic Polyimide Aerogels.

    Science.gov (United States)

    Feng, Junzong; Wang, Xin; Jiang, Yonggang; Du, Dongxuan; Feng, Jian

    2016-05-25

    Polyimide aerogels for low density thermal insulation materials were produced by 4,4'-diaminodiphenyl ether and 3,3',4,4'-biphenyltetracarboxylic dianhydride, cross-linked with 1,3,5-triaminophenoxybenzene. The densities of obtained polyimide aerogels are between 0.081 and 0.141 g cm(-3), and the specific surface areas are between 288 and 322 m(2) g(-1). The thermal conductivities were measured by a Hot Disk thermal constant analyzer. The value of the measured thermal conductivity under carbon dioxide atmosphere is lower than that under nitrogen atmosphere. Under pressure of 5 Pa at -130 °C, the thermal conductivity is the lowest, which is 8.42 mW (m K)(-1). The polyimide aerogels have lower conductivity [30.80 mW (m K)(-1)], compared to the value for other organic foams (polyurethane foam, phenolic foam, and polystyrene foam) with similar apparent densities under ambient pressure at 25 °C. The results indicate that polyimide aerogel is an ideal insulation material for aerospace and other applications.

  8. Titania aerogel prepared by low temperature supercritical drying

    Czech Academy of Sciences Publication Activity Database

    Štengl, Václav; Bakardjieva, Snejana; Šubrt, Jan; Szatmáry, Lórant

    2006-01-01

    Roč. 91, 1-3 (2006), s. 1-6 ISSN 1387-1811 R&D Projects: GA MŠk(CZ) 1M0577 Institutional research plan: CEZ:AV0Z40320502 Keywords : aerogels * titanium oxide * supercritical drying Subject RIV: CA - Inorganic Chemistry Impact factor: 2.796, year: 2006

  9. Thin Aerogel as a Spacer in Multilayer Insulation

    Science.gov (United States)

    Moroz, Nancy

    2015-01-01

    Cryogenic fluid management is a critical technical area that is needed for future space exploration. A key challenge is the storability of liquid hydrogen (LH2), liquid methane (LCH4), and liquid oxygen (LOX) propellants for long-duration missions. The storage tanks must be well-insulated to prevent over-pressurization and venting, which can lead to unacceptable propellant losses for long-duration missions to Mars and beyond. Aspen Aerogels had validated the key process step to enable the fabrication of thin, low-density aerogel materials. The multilayer aerogel insulation (MLAI) system prototypes were prepared using sheets of aerogel materials with superior thermal performance exceeding current state-of-the-art insulation for space applications. The exceptional properties of this system include a new breakthrough in high-vacuum cryogenic thermal insulation, providing a durable material with excellent thermal performance at a reduced cost when compared to longstanding state-of-the-art multilayer insulation systems. During the Phase II project, further refinement and qualification/system-level testing of the MLAI system will be performed for use in cryogenic storage applications. Aspen has been in discussions with United Launch Alliance, LLC; NASA's Kennedy Space Center; and Yetispace, Inc., to test the MLAI system on rea-lworld tanks such as Vibro-Acoustic Test Article (VATA) or the Cryogenic Orbital Testbed (CRYOTE).

  10. Aerogel-Based Antennas for Aerospace and Terrestrial Applications

    Science.gov (United States)

    Meador, Mary Ann (Inventor); Miranda, Felix (Inventor); Van Keuls, Frederick (Inventor)

    2016-01-01

    Systems and methods for lightweight, customizable antenna with improved performance and mechanical properties are disclosed. In some aspects, aerogels can be used, for example, as a substrate for antenna fabrication. The reduced weight and expense, as well as the increased ability to adapt antenna designs, permits a systems to mitigate a variety of burdens associated with antennas while providing added benefits.

  11. Methacrylate Polymer Monoliths for Separation Applications

    Directory of Open Access Journals (Sweden)

    Robert J. Groarke

    2016-06-01

    Full Text Available This review summarizes the development of methacrylate-based polymer monoliths for separation science applications. An introduction to monoliths is presented, followed by the preparation methods and characteristics specific to methacrylate monoliths. Both traditional chemical based syntheses and emerging additive manufacturing methods are presented along with an analysis of the different types of functional groups, which have been utilized with methacrylate monoliths. The role of methacrylate based porous materials in separation science in industrially important chemical and biological separations are discussed, with particular attention given to the most recent developments and challenges associated with these materials. While these monoliths have been shown to be useful for a wide variety of applications, there is still scope for exerting better control over the porous architectures and chemistries obtained from the different fabrication routes. Conclusions regarding this previous work are drawn and an outlook towards future challenges and potential developments in this vibrant research area are presented. Discussed in particular are the potential of additive manufacturing for the preparation of monolithic structures with pre-defined multi-scale porous morphologies and for the optimization of surface reactive chemistries.

  12. Methacrylate Polymer Monoliths for Separation Applications

    Science.gov (United States)

    Groarke, Robert J.; Brabazon, Dermot

    2016-01-01

    This review summarizes the development of methacrylate-based polymer monoliths for separation science applications. An introduction to monoliths is presented, followed by the preparation methods and characteristics specific to methacrylate monoliths. Both traditional chemical based syntheses and emerging additive manufacturing methods are presented along with an analysis of the different types of functional groups, which have been utilized with methacrylate monoliths. The role of methacrylate based porous materials in separation science in industrially important chemical and biological separations are discussed, with particular attention given to the most recent developments and challenges associated with these materials. While these monoliths have been shown to be useful for a wide variety of applications, there is still scope for exerting better control over the porous architectures and chemistries obtained from the different fabrication routes. Conclusions regarding this previous work are drawn and an outlook towards future challenges and potential developments in this vibrant research area are presented. Discussed in particular are the potential of additive manufacturing for the preparation of monolithic structures with pre-defined multi-scale porous morphologies and for the optimization of surface reactive chemistries. PMID:28773570

  13. Preparation of monolithic polymer columns with homogeneous structure via photoinitiated thiol-yne click polymerization and their application in separation of small molecules.

    Science.gov (United States)

    Liu, Zhongshan; Ou, Junjie; Lin, Hui; Wang, Hongwei; Liu, Zheyi; Dong, Jing; Zou, Hanfa

    2014-12-16

    Two monolithic polymer columns were directly prepared in the UV-transparent fused-silica capillaries via photoinitiated thiol-yne click polymerization of 1,7-octadiyne (ODY) with a dithiol (1,6-hexanedithiol, 2SH) or a tetrathiol (pentaerythriol tetrakis(3-mercaptopropionate), 4SH) within 15 min. The rapid polymerization provided a time-saving approach to optimize preparation conditions. Then, two porogenic systems of diethylene glycol diethyl ether (DEGDE)/tetrahydrofuran (THF) and DEGDE/poly(ethylene glycol) (PEG, Mn = 200) were found to effectively control the porous structure of two kinds of polymeric monoliths (O2SH and O4SH), respectively. The almost disappearance of thiol and alkynyl vibrations (2560 and 2115 cm(-1), respectively) in infrared spectra and Raman spectra indicated a high conversion of the thiol-yne polymerization reaction. The thiol-yne polymerization was further proved by analyzing the energy-dispersive X-ray spectrum (EDS), MALDI-TOF mass spectrum, and elemental data. Scanning electron microscopy (SEM) images showed the monolithic polymer columns with homogeneous porous structure and macropore size of 0.5-1.0 μm, which facilitated the minimum plate heights of 10.0-12.0 μm for alkylbenzenes in reversed-phase liquid chromatography (RPLC). The low values of the A and C terms (monolithic silica columns. The BSA tryptic digest was also separated on the monolithic polymer column by cLC-MS/MS. The result with 85% protein coverage was better than those given by some hybrid monolithic columns. The monolithic polymer columns were further applied for separation of phenols, natural products, and standard proteins and demonstrated satisfactory separation ability.

  14. The synthesis of weak acidic type hybrid monolith via thiol-ene click chemistry and its application in hydrophilic interaction chromatography.

    Science.gov (United States)

    Zeng, Jiao; Liu, Shengquan; Wang, Menglin; Yao, Shouzhuo; Chen, Yingzhuang

    2017-05-01

    In this work, a porous structure and good permeability monolithic column was polymerized in UV transparent fused-silica capillaries via photo-initiated thiol-ene click polymerization of 2,4,6,8-tetravinyl-2,4,6,8-tetramethylcyclotetrasiloxane (TMTVS), pentaerythritol tetra(3-mercaptopropionate)(PETMP), itaconic acid, respectively, in the presence of porogenic solvents (tetrahydrofuranand methanol) and an initiator (2,2-dimethoxy-2-phenylacetophenone) (DMPA) within 30 min. The physical properties of this monolith were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy and nitrogen adsorption/desorption measurements. For an overall evaluation of the monolith in chromatographic application, separations of polycyclic aromatic hydrocarbons (PAHs), phenols, amides and bases were carried out. The column efficiency of this monolith could be as high as 112 560 N/m. It also possesses a potential application in fabrication of monoliths with high efficiency for c-LC. In addition, the resulting monolithic column demonstrated the potential use in analysis of environment waters. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Structure and Thermodynamics of Carbon Dioxide Sorption in Silica Pores from Experiments and Computer Models

    Science.gov (United States)

    Vlcek, L.; Rother, G.; Chialvo, A.; Cole, D. R.

    2011-12-01

    Injection of CO2 into geologic formations has been proposed as a key element to reduce the impact of greenhouse gases emissions. Quantitative understanding of CO2 adsorption in porous mineral environments at thermodynamic conditions relevant to proposed sequestration sites is thus a prerequisite for the assessment of their viability. In this study we use a combination of neutron scattering, adsorption experiments, and computer modeling to investigate the thermodynamics of near-critical carbon dioxide in the pores of SiO2 aerogel, which serves as a model of a high-porosity reservoir rock. Small angle neutron scattering (SANS) experiments provide input for the optimization of the computer model of the aerogel matrix, and also serve as a sensitive probe of local density changes of confined CO2 as a function of external pressure. Additional details of the aerogel basic building blocks and SiO2 surface are derived from TEM images. An independent source of global adsorption data is obtained from gravimetric experiments. The structural and thermodynamic aspects of CO2 sorption are linked using computer simulations, which include the application of the optimized diffusion limited cluster-cluster aggregation algorithm (DLCA), classical density functional theory (DFT) modeling of large-scale CO2 density profiles, and molecular dynamics simulations of the details of interactions between CO2 molecules and the amorphous silica surfaces. This integrated approach allows us to span scales ranging from 1Å to 1μm, as well as to infer the detailed structure of silica threads forming the framework of the silica matrix.

  16. Aerogel Poly(butylene succinate) Biomaterial Substrate for RF and Microwave Applications.

    Science.gov (United States)

    Habib Ullah, M; Mahadi, W N L; Latef, T A

    2015-08-04

    Polybutylene succinate (PBS) has become a potential candidate, similar to polypropylene (PP) and acrylonitrile butadiene styrene (ABS), for use as an organic plastic material due to its outstanding mechanical properties as well as high thermal deformation characteristics. A new composition of silica aerogel nanoparticles extracted from rice waste with PBS is proposed for use as a dielectric (εr = 4.5) substrate for microwave applications. A microstrip patch antenna was fabricated on the proposed dielectric substrate for multi-resonant ultra-wideband (UWB) applications. The performance characteristics of the proposed biomaterial-based antenna were investigated in a far-field measurement environment. The results indicate that the proposed biocompatible material-based antenna covered a bandwidth of 9.4 (2.3-11.7) GHz with stop bands from 5.5 GHz to 5.8 GHz and 7.0 GHz to 8.3 GHz. Peak gains of 9.82 dBi, 7.59 dBi, 8.0 dBi and 7.68 dBi were measured at resonant frequencies of 2.7 GHz, 4.6 GHz, 6.3 GHz and 9.5 GHz, respectively.

  17. Aerogel Poly(butylene succinate) Biomaterial Substrate for RF and Microwave Applications

    Science.gov (United States)

    Habib Ullah, M.; Mahadi, W. N. L.; Latef, T. A.

    2015-08-01

    Polybutylene succinate (PBS) has become a potential candidate, similar to polypropylene (PP) and acrylonitrile butadiene styrene (ABS), for use as an organic plastic material due to its outstanding mechanical properties as well as high thermal deformation characteristics. A new composition of silica aerogel nanoparticles extracted from rice waste with PBS is proposed for use as a dielectric (ɛr = 4.5) substrate for microwave applications. A microstrip patch antenna was fabricated on the proposed dielectric substrate for multi-resonant ultra-wideband (UWB) applications. The performance characteristics of the proposed biomaterial-based antenna were investigated in a far-field measurement environment. The results indicate that the proposed biocompatible material-based antenna covered a bandwidth of 9.4 (2.3-11.7) GHz with stop bands from 5.5 GHz to 5.8 GHz and 7.0 GHz to 8.3 GHz. Peak gains of 9.82 dBi, 7.59 dBi, 8.0 dBi and 7.68 dBi were measured at resonant frequencies of 2.7 GHz, 4.6 GHz, 6.3 GHz and 9.5 GHz, respectively.

  18. Methods for controlling pore morphology in aerogels using electric fields and products thereof

    Energy Technology Data Exchange (ETDEWEB)

    Worsley, Marcus A.; Baumann, Theodore F.; Satcher, Jr., Joe H.; Olson, Tammy Y.; Kuntz, Joshua D.; Rose, Klint A.

    2017-12-16

    In one embodiment, an aerogel or xerogel includes column structures of a material having minor pores therein and major pores devoid of the material positioned between the column structures, where longitudinal axes of the major pores are substantially parallel to one another. In another embodiment, a method includes heating a sol including aerogel or xerogel precursor materials to cause gelation thereof to form an aerogel or xerogel and exposing the heated sol to an electric field, wherein the electric field causes orientation of a microstructure of the sol during gelation, which is retained by the aerogel or xerogel. In one approach, an aerogel has elongated pores extending between a material arranged in column structures having structural characteristics of being formed from a sol exposed to an electric field that causes orientation of a microstructure of the sol during gelation which is retained by the elongated pores of the aerogel.

  19. Characterization of pure and composite resorcinol formaldehyde aerogels doped with silver

    Science.gov (United States)

    Attia, S. M.; Abdelfatah, M. S.; Mossad, M. M.

    2017-07-01

    A series of Resorcinol Formaldehyde (RF) aerogels composites with nanoparticles of sliver were prepared by the sol-gel method at different concentrations doped silver. FTIR spectra of pure and composite RF aerogels show six absorption bands attributed to -OH groups bonded to the benzene ring, stretching of -CH2- bonds and aromatic ring stretching. FTIR results ensured that sliver particles do not interact with aerogel network. UV-visible spectrum of pure silver show an absorbance peak at 420 nm attributed to the surface plasmon excitation of sliver Nano spheres. UV-visible spectral of pure and composite RF aerogels shows a steep decrease of absorption with wavelength after 500 nm, making sample’s color reddish brown. TEM and SEM images of pure and composite RF aerogels revealed that the textural arrangement of RF aerogels can be described as densely packed small nodules.

  20. Spray freeze-dried nanofibrillated cellulose aerogels with thermal superinsulating properties.

    Science.gov (United States)

    Jiménez-Saelices, Clara; Seantier, Bastien; Cathala, Bernard; Grohens, Yves

    2017-02-10

    Nanofibrillated cellulose (NFC) aerogels were prepared by spray freeze-drying (SFD). Their structural, mechanical and thermal insulation properties were compared to those of NFC aerogels prepared by conventional freeze-drying (CFD). The purpose of this investigation is to develop superinsulating bioaerogels by reducing their pore size. Severe reduction of the aerogel pore size and skeleton architecture were observed by SEM, aerogels prepared by SFD method show a fibril skeleton morphology, which defines a mesoporous structure. BET analyses confirm the appearance of a new organization structure with pores of nanometric sizes. As a consequence, the thermal insulation properties were significantly improved for SFD materials compared to CFD aerogel, reaching values of thermal conductivity as low as 0.018W/(mK). Moreover, NFC aerogels have a thermal conductivity below that of air in ambient conditions, making them one of the best cellulose based thermal superinsulating material. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Polysaccharide-based aerogels as water absorbent and oxygen scavenger in meat packaging

    OpenAIRE

    Gracanac, Bojana

    2015-01-01

    Polysaccharide-based aerogels are a novel concept with potential application in the food sector due to their material properties, renewability and sustainability. High absorption capacity of polysaccharide aerogels makes them a potential moisture absorbent material in meat packaging. The aim of this work was to study the tamarind seed galactoxyloglucan (XG) aerogels as potential meat packaging material by testing their absorption capacity and mechanical properties. Another objective of th...

  2. SAXS study of silica sols, gels and glasses obtained by the sol gel process

    International Nuclear Information System (INIS)

    Santos, D.I. dos; Aegerter, M.A.

    1988-01-01

    Systematic SAXS studies have been performed at the LURE Synchrotron, Orsay, using an intense beam of point like cross-section to obtain information about the sol -> humid gel -> dried gel -> silica glass transformation. The intensity curves have been analysed in term of power law in log-log plots, whose exponent is related to mass and surface fractal dimensions of the structure. It was found that almost all phases present fractal structures and for the case of basic gels, is of hierarchical nature. The aerogels are formed by a dense matrix, with a smooth surface and exhibit a very narrow auto-similarity range that gives a mass fractal dimension. (author) [pt

  3. Slow dynamics of nanocomposite polymer aerogels as revealed by X-ray photocorrelation spectroscopy (XPCS)

    Energy Technology Data Exchange (ETDEWEB)

    Hernández, Rebeca, E-mail: rhernandez@ictp.csic.es, E-mail: aurora.nogales@csic.es; Mijangos, Carmen [Instituto de Ciencia y Tecnología de Polímeros, ICTP-CSIC, Juan de la Cierva, 3, 28006 Madrid (Spain); Nogales, Aurora, E-mail: rhernandez@ictp.csic.es, E-mail: aurora.nogales@csic.es; Ezquerra, Tiberio A. [Instituto de Estructura de la Materia, IEM-CSIC, Serrano 121, 28006 Madrid (Spain); Sprung, Michael [Petra III at DESY, Notkestr. 85, 22607 Hamburg (Germany)

    2014-01-14

    We report on a novel slow dynamics of polymer xerogels, aerogels, and nanocomposite aerogels with iron oxide nanoparticles, as revealed by X-ray photon correlation spectroscopy. The polymer aerogel and its nanocomposite aerogels, which are porous in nature, exhibit hyper-diffusive dynamics at room temperature. In contrast, non-porous polymer xerogels exhibit an absence of this peculiar dynamics. This slow dynamical process has been assigned to a relaxation of the characteristic porous structure of these materials and not to the presence of nanoparticles.

  4. Structural properties and adsorption capacity of holocellulose aerogels synthesized from an alkali hydroxide-urea solution

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Gu-Joong; Kim, Dae-Young; Hwang, Jae-Hyun; Kang, Joo-Hyon [Dongguk University, Seoul (Korea, Republic of)

    2014-05-15

    A tulip tree was used to synthesize a holocellulose aerogel from an aqueous alkali hydroxide-urea solution with the substitution of an organic solvent followed by freeze-drying. For comparison, the synthesized holocellulose aerogels were divided into two groups according to the source of the hydrogel, an upper suspended layer and a bottom concentrated layer of the centrifuged solution of cellulose and NaOH/urea solvents. We investigated the effects of the temperature of the pre-cooled NaOH/urea solution (i.e., dissolution temperature) on the pore structure and the adsorption capacity of the holocellulose aerogel. A nano-fibrillar network structure of the holocellulose aerogel was observed, with little morphological difference in pore structure for different dissolution temperatures. Both micropores and mesopores were observed in the holocellulose aerogel. The specific surface area of the holocellulose aerogel was generally greater at lower dissolution temperatures. In a series of adsorption tests using methylene blue, the holocellulose aerogel showed the greatest adsorption capacity at the lowest dissolution temperature tested ( -2 .deg. C). However, the dissolution temperature generally had little effect on the adsorption capacity. The holocellulose aerogel produced from the upper suspended layer of the centrifuged hydrogel solution showed a greater porosity and adsorption capacity than the one produced from the bottom concentrated layer. Overall, the aerogel made by utilizing a delignified tulip tree display a high surface area and a high adsorption property, indicating its possible application in eco-friendly adsorption materials.

  5. Structural properties and adsorption capacity of holocellulose aerogels synthesized from an alkali hydroxide-urea solution

    International Nuclear Information System (INIS)

    Kwon, Gu-Joong; Kim, Dae-Young; Hwang, Jae-Hyun; Kang, Joo-Hyon

    2014-01-01

    A tulip tree was used to synthesize a holocellulose aerogel from an aqueous alkali hydroxide-urea solution with the substitution of an organic solvent followed by freeze-drying. For comparison, the synthesized holocellulose aerogels were divided into two groups according to the source of the hydrogel, an upper suspended layer and a bottom concentrated layer of the centrifuged solution of cellulose and NaOH/urea solvents. We investigated the effects of the temperature of the pre-cooled NaOH/urea solution (i.e., dissolution temperature) on the pore structure and the adsorption capacity of the holocellulose aerogel. A nano-fibrillar network structure of the holocellulose aerogel was observed, with little morphological difference in pore structure for different dissolution temperatures. Both micropores and mesopores were observed in the holocellulose aerogel. The specific surface area of the holocellulose aerogel was generally greater at lower dissolution temperatures. In a series of adsorption tests using methylene blue, the holocellulose aerogel showed the greatest adsorption capacity at the lowest dissolution temperature tested ( -2 .deg. C). However, the dissolution temperature generally had little effect on the adsorption capacity. The holocellulose aerogel produced from the upper suspended layer of the centrifuged hydrogel solution showed a greater porosity and adsorption capacity than the one produced from the bottom concentrated layer. Overall, the aerogel made by utilizing a delignified tulip tree display a high surface area and a high adsorption property, indicating its possible application in eco-friendly adsorption materials.

  6. 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....

  7. Surfactant-bound monolithic columns for CEC.

    Science.gov (United States)

    Gu, Congying; He, Jun; Jia, Jinping; Fang, Nenghu; Shamsi, Shahab A

    2009-11-01

    A novel anionic surfactant bound monolithic stationary phase based on 11-acrylaminoundecanoic acid is designed for CEC. The monolith possessing bonded undecanoyl groups (hydrophobic sites) and carboxyl groups (weak cationic ion-exchange sites) were evaluated as a mixed-mode stationary phase in CEC for the separation of neutral and polar solutes. Using a multivariate D-optimal design the composition of the polymerization mixture was modeled and optimized with five alkylbenzenes and seven alkyl phenyl ketones as test solutes. The D-optimal design indicates a strong dependence of electrochromatographic parameters on the concentration of 11-acrylaminoundecanoic acid monomer and porogen (water) in the polymerization mixture. A difference of 6, 8 and 13% RSD between the predicted and the experimental values in terms of efficiency, resolution and retention time, respectively, indeed confirmed that the proposed approach is practical. The physical (i.e. morphology, porosity and permeability) and chromatographic properties of the monolithic columns were thoroughly investigated. With the optimized monolithic column, high efficiency separation of N-methylcarbamates pesticides and positional isomers was successfully achieved. It appears that this type of mixed-mode monolith (containing both chargeable and hydrophobic sites) may have a great potential as a new generation of CEC stationary phase.

  8. Controlled generation of silver nanocolloid in amorphous silica materials

    International Nuclear Information System (INIS)

    Gil, C.; Garcia-Heras, M.; Carmona, N.; Villages, M. A.

    2004-01-01

    Amorphous silica-based materials bulk and superficially doped with silver nano colloids were prepared. Bulk doped glasses were obtained by conventional melting and doped monolithic slabs by sol-gel. Superficially doped glasses were obtained by ion-exchange and doped coatings by sol-gel. The samples were characterised by TEM and UV-VIS spectrometry. Depending on the composition, the silver incorporation process, and the thermal treatments, several colourings were obtained. By controlling these parameters, metallic silver nano colloids can be generated in the matrices studied. Colloids aggregation and growing up depends on the matrix nature and on the experimental process carried out. (Author) 10 refs

  9. Luminescence of TiO{sub 2}:Pr nanoparticles incorporated in silica aerogel

    Energy Technology Data Exchange (ETDEWEB)

    Amlouk, A. [Laboratoire de Physique des Materiaux et des Nanomateriaux Appliquee a l' Environnement, Faculte des Sciences de Gabes, cite Erriadh Manara Zrig, 6072 Gabes (Tunisia); El Mir, L. [Laboratoire de Physique des Materiaux et des Nanomateriaux Appliquee a l' Environnement, Faculte des Sciences de Gabes, cite Erriadh Manara Zrig, 6072 Gabes (Tunisia)], E-mail: Lassaad.ElMir@fsg.rnu.tn; Kraiem, S. [Laboratoire de Physique des Materiaux et des Nanomateriaux Appliquee a l' Environnement, Faculte des Sciences de Gabes, cite Erriadh Manara Zrig, 6072 Gabes (Tunisia); Saadoun, M. [Centre de Recherche et des Technologies de l' Energie (CRTE), Laboratoire de Photovoltaique et des Semiconducteurs, BP 95, 2050 Hammam-Lif (Tunisia); Alaya, S. [Laboratoire de Physique des Materiaux et des Nanomateriaux Appliquee a l' Environnement, Faculte des Sciences de Gabes, cite Erriadh Manara Zrig, 6072 Gabes (Tunisia); Pierre, A.C. [Institut de Recherches sur la Catalyse et l' Environnement de Lyon (Ircelyon), CNRS-UMR5256, Universite de Lyon, 2 Avenue Albert Einstein 69622, Villeurbanne Cedex (France)

    2008-01-15

    The photoluminescence of praseodymium ions in SiO{sub 2}/TiO{sub 2} glasses elaborated by the sol-gel method was reported. It is shown that Pr ions were embedded in TiO{sub 2} nanocrystals (tetragonal, rutile) surrounded by a SiO{sub 2} glass matrix. Photoluminescence (PL) and photoluminescence excitation (PLE) spectra revealed the presence of energy transfer between the host matrix states and Pr{sup 3+} ions. X-ray diffraction (XRD) spectra, specific surface area by the Brunauer, Emmett and Teller method (BET), transmission electron microscopy (TEM) and infrared (IR) absorption spectra of the samples have also been investigated. It is shown that the Pr{sup 3+} ions are not homogeneously distributed inside the glass matrix and that the lanthanide ion-doped TiO{sub 2} nanoparticules have higher surface area than the pure TiO{sub 2}.

  10. Taking a Large Monolith to Use for Teaching Soil Morphology.

    Science.gov (United States)

    Smith, B. R.; And Others

    1989-01-01

    Described is a technique for taking a large monolith for the purpose of teaching soil structure. Materials and procedures are detailed. A survey of 93 students indicated that the larger monolith was preferred over the commonly used narrow ones. (CW)

  11. Fabrication and characterization of nanotemplated carbon monolithic material.

    Science.gov (United States)

    He, Xiaoyun; Nesterenko, Ekaterina P; Nesterenko, Pavel N; Brabazon, Dermot; Zhou, Lin; Glennon, Jeremy D; Luong, John H T; Paull, Brett

    2013-09-11

    A novel hierarchical nanotemplated carbon monolithic rod (NTCM) was prepared using a novel facile nanotemplating approach. The NTCM was obtained using C60-fullerene modified silica gels as hard templates, which were embedded in a phenolic resin containing a metal catalyst for localized graphitization, followed by bulk carbonization, and template and catalyst removal. TEM, SEM, and BET measurements revealed that NTCM possessed an integrated open hierarchical porous structure, with a trimodal pore distribution. This porous material also possessed a high mesopore volume and narrow mesopore size distribution. During the course of carbonization, the C60 conjugated to aminated silica was partly decomposed, leading to the formation of micropores. The Raman signature of NTCM was very similar to that of multiwalled carbon nanotubes as exemplified by three major peaks as commonly observed for other carbon materials, i.e., the sp3 and sp2 carbon phases coexisted in the sample. Surface area measurements were obtained using both nitrogen adsorption/desorption isotherms (BET) and with a methylene blue binding assay, with BET results showing the NTCM material possessed an average specific surface area of 435 m2 g(-1), compared to an area of 372 m2 g(-1) obtained using the methylene blue assay. Electrochemical studies using NTCM modified glassy carbon or boron doped diamond (BDD) electrodes displayed quasi-reversible oxidation/reduction with ferricyanide. In addition, the BDD electrode modified with NTCM was able to detect hydrogen peroxide with a detection limit of below 300 nM, whereas the pristine BDD electrode was not responsive to this target compound.

  12. A little cloud of smoke full of night-rate electricity. Aerogel as electricity storage. The end of batteries?; Een wolkje rook vol nachtstroom. Aerogel als elektriciteitsopslag. Het einde van de accu?

    Energy Technology Data Exchange (ETDEWEB)

    Dijkgraaf, A. [ed.

    2000-06-22

    PowerStor in Dublin, California, USA, patented aerogel capacitors in which energy is stored in the form of electrostatic energy in between an electrolyte and the pores of a carbon-aerogel. A brief overview is given of the principle and the prospects of aerogel as a medium to store energy. 3 refs.

  13. Fracture resistance of monolithic zirconia molar crowns with reduced thickness

    OpenAIRE

    Nakamura, Keisuke; Harada, A.; Inagaki, R.; Kanno, Taro; Niwano, Y.; Milleding, Percy; Ørtengren, Ulf Thore

    2015-01-01

    This is the accepted manuscript version. Published version is available at Acta Odontologica Scandinavica Objectives. The purpose of the present study was to analyze the relationship between fracture load of monolithic zirconia crowns and axial/occlusal thickness, and to evaluate the fracture resistance of monolithic zirconia crowns with reduced thickness in comparison with that of monolithic lithium disilicate crowns with regular thickness. Materials and methods. Monolithic zi...

  14. Ag/SiO2- and Ag/Co3O4-Based Monolithic Flow Microreactors for Hydrogenation of Dyes: Their Activity and Stability

    Directory of Open Access Journals (Sweden)

    Yasemin Hakat

    2015-02-01

    Full Text Available Silver nanoparticles supported on hierarchically porous silica and cobalt oxide monoliths have previously been shown to be catalytically active for the hydrogenation of common organic dyes in batch studies. This work presents a detailed investigation of the activity and stability of these monoliths during the hydrogenation of eosin-Y in a continuous flow microreactor. The silver-containing monoliths showed excellent catalytic activity that reached a plateau after a period of approximately 6 h. From SEM particle size distribution studies of the catalysts before and after water and hexane were flowed through them, it was determined that under reaction conditions, silver was removed both by washing off of particles and by dissolution of silver.

  15. Eigenpolarization theory of monolithic nonplanar ring oscillators

    Science.gov (United States)

    Nilsson, Alan C.; Gustafson, Eric K.; Byer, Robert L.

    1989-01-01

    Diode-laser-pumped monolithic nonplanar ring oscillators (NPROs) in an applied magnetic field can operate as unidirectional traveling-wave lasers. The diode laser pumping, monolithic construction, and unidirectional oscillation lead to narrow linewidth radiation. Here, a comprehensive theory of the eigenpolarizations of a monolithic NPRO is presented. It is shown how the properties of the integral optical diode that forces unidirectional operation depend on the choice of the gain medium, the applied magnetic field, the output coupler, and the geometry of the nonplanar ring light path. Using optical equivalence theorems to gain insight into the polarization characteristics of the NPRO, a strategy for designing NPROs with low thresholds and large loss nonreciprocities is given. An analysis of the eigenpolarizations for one such NPRO is presented, alternative optimization approaches are considered, and the prospects for further reducing the linewidths of these lasers are briefly discussed.

  16. Low dielectric constant and moisture-resistant polyimide aerogels containing trifluoromethyl pendent groups

    Science.gov (United States)

    Wu, Tingting; Dong, Jie; Gan, Feng; Fang, Yuting; Zhao, Xin; Zhang, Qinghua

    2018-05-01

    Conventional polyimide aerogels made from biphenyl-3,3‧,4,4‧-tetracarboxylic dianydride (BPDA) and 4,4‧-oxidianiline (ODA) exhibit poor resistance to moisture and mechanical properties. In this work, a versatile diamine, 2,2‧-bis-(trifluoromethyl)-4,4‧-diaminobiphenyl (TFMB), is introduced to BPDA/ODA backbone to modify the comprehensive performance of this aerogel. Among all formulations, the resulted polyimide aerogels exhibit the lowest shrinkage and density as well as highest porosity, at the ODA/TFMB molar ratio of 5/5. Dielectric constants and loss tangents of the aerogels fall in the range of 1.29-1.33 and 0.001-0.004, respectively, and more TFMB fractions results in a slightly decrease of dielectric constant and loss tangent. In addition, moisture-resistance of the aerogels are dramatically enhanced as the water absorption decreasing from 415% for BPDA/ODA to 13% for the polyimide aerogel at the ODA/TFMB molar ratio of 7/3, and even to 4% for the homo-BPDA/TFMB polyimide aerogel, showing a superhydrophobic characteristic, which is a great advantage for polyimide aerogels used as low dielectric materials. Meanwhile, all of formulations of aerogels exhibit high absorption capacities for oils and common organic solvents, indicating that these fluorinated polyimide aerogels are good candidates for the separation of oils/organic solvents and water. Mechanical properties and thermal stability of the polyimide aerogels are also raised to varying degrees due to the rigid-rod biphenyl structure introduced by TFMB.

  17. Investigation into Cherenkov light scattering and refraction on aerogel surface

    Science.gov (United States)

    Barnyakov, A. Yu.; Barnyakov, M. Yu.; Bobrovnikov, V. S.; Buzykaev, A. R.; Danilyuk, A. F.; Katcin, A. A.; Kirilenko, P. S.; Kononov, S. A.; Korda, D. V.; Kravchenko, E. A.; Kudryavtsev, V. N.; Kuyanov, I. A.; Onuchin, A. P.; Ovtin, I. V.; Podgornov, N. A.; Predein, A. Yu.; Prisekin, V. G.; Protsenko, R. S.; Shekhtman, L. I.

    2017-12-01

    The work concerns the development of aerogel radiators for RICH detectors. Aerogel tiles with a refractive index of 1.05 were tested with a RICH prototype on the electron beam on the VEPP-4M collider. It has been shown that polishing with silk tissue yields good surface quality, the amount of light loss at this surface being about 5-7%. The Cherenkov angle resolution was measured for a tile in two conditions: with a clean exit face and with a polished exit face. The number of photons detected was 13.3 and 12.7 for the clean and polished surfaces, respectively. The Cherenkov angle resolution for the polished surface is 55% worse, which can be explained with the forward scattering on the polished surface. A tile with a crack inside was also tested. The experimental data show that the Cherenkov angle resolution is the same for tracks crossing the crack area and in a crack-free area.

  18. UPDATE ON MONOLITHIC FUEL FABRICATION METHODS

    Energy Technology Data Exchange (ETDEWEB)

    C. R. Clark; J. F. Jue; G. A. Moore; N. P. Hallinan; B. H. Park; D. E. Burkes

    2006-10-01

    Efforts to develop a viable monolithic research reactor fuel plate have continued at Idaho National Laboratory. These efforts have concentrated on both fabrication process refinement and scale-up to produce full sized fuel plates. Progress at INL has led to fabrication of hot isostatic pressed uranium-molybdenum bearing monolithic fuel plates. These miniplates are part of the RERTR-8 miniplate irradiation test. Further progress has also been made on friction stir weld processing which has been used to fabricate full size fuel plates which will be irradiated in the ATR and OSIRIS reactors.

  19. Macroporous Monolithic Polymers: Preparation and Applications

    Science.gov (United States)

    Arrua, Ruben Dario; Strumia, Miriam Cristina; Alvarez Igarzabal, Cecilia Inés

    2009-01-01

    In the last years, macroporous monolithic materials have been introduced as a new and useful generation of polymers used in different fields. These polymers may be prepared in a simple way from a homogenous mixture into a mold and contain large interconnected pores or channels allowing for high flow rates at moderate pressures. Due to their porous characteristics, they could be used in different processes, such as stationary phases for different types of chromatography, high-throughput bioreactors and in microfluidic chip applications. This review reports the contributions of several groups working in the preparation of different macroporous monoliths and their modification by immobilization of specific ligands on the products for specific purposes.

  20. Technology development for SOI monolithic pixel detectors

    International Nuclear Information System (INIS)

    Marczewski, J.; Domanski, K.; Grabiec, P.; Grodner, M.; Jaroszewicz, B.; Kociubinski, A.; Kucharski, K.; Tomaszewski, D.; Caccia, M.; Kucewicz, W.; Niemiec, H.

    2006-01-01

    A monolithic detector of ionizing radiation has been manufactured using silicon on insulator (SOI) wafers with a high-resistivity substrate. In our paper the integration of a standard 3 μm CMOS technology, originally designed for bulk devices, with fabrication of pixels in the bottom wafer of a SOI substrate is described. Both technological sequences have been merged minimizing thermal budget and providing suitable properties of all the technological layers. The achieved performance proves that fully depleted monolithic active pixel matrix might be a viable option for a wide spectrum of future applications

  1. Monolithic JFET preamplifier for ionization chamber calorimeter

    International Nuclear Information System (INIS)

    Radeka, V.; Rescia, S.; Manfredi, P.F.; Speziali, V.

    1990-10-01

    A monolithic charge sensitive preamplifier using exclusively n-channel diffused JFETs has been designed and is now being fabricated by INTERFET Corp. by means of a dielectrically isolated process which allows preserving as much as possible the technology upon which discrete JFETs are based. A first prototype built by means of junction isolated process has been delivered. The characteristics of monolithically integrated JFETs compare favorably with discrete devices. First results of tests of a preamplifier which uses these devices are reported. 4 refs

  2. 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

  3. Silica from Ash

    Indian Academy of Sciences (India)

    Silica (SiOz) is one of the valuable inorganic multipurpose chemical compounds. It can exist in gel, crystalline and amorphous forms. It is the most abundant material on the earth's crust. However, manufacture of pure silica is energy intensive. A variety of industrial processes, involving conven- tional raw materials require ...

  4. Aerogels and opened-cell structures: two examples of carbon foams; Les aerogels et les structures alveolaires. Deux exemples de mousses de carbone

    Energy Technology Data Exchange (ETDEWEB)

    Kocon, L.; Piquero, Th. [CEA Centre d' Etudes du Ripault, Dept. des Materiaux, Service Recherche Ceramiques et Composites, 37 - Tours (France)

    2006-03-15

    Two examples of carbon foams are exposed herein. They are very lightweight materials with an exceptionally open porosity high volume. Cells size varies from nanometer to micrometer for aerogels, and from micrometer to millimeter for opened cell carbon foams. Elaboration process conditions allow to adjust pore sizes as well as micro-textural characteristics and macroscopical mechanical properties. Carbon aerogels are synthesized by organic aerogels pyrolysis leading to a large variety of micro-textures. Opened cell carbon foams present an original mechanical behavior, brittle type, which can be enhanced by CVD or calefaction pyrocarbon reinforcement. (authors)

  5. Biodiesel production by using lipase immobilized onto novel silica-based hybrid foams

    Energy Technology Data Exchange (ETDEWEB)

    Brun, Nicolas [Centre de Recherche Paul Pascal, Pessac (France); Institut des Sciences Moleculaires, Talence (France); Garcia, Annick Babeau; Oestreicher, Victor; Durand, Fabien; Backov, Renal [Centre de Recherche Paul Pascal, Pessac (France); Deleuze, Herve [Institut des Sciences Moleculaires, Talence (France); Laurent, Guillaume; Sanchez, Clement [Laboratoire de Chimie de la Matiere Condensee, Paris (France)

    2010-07-01

    The covalent immobilization of crude lipases within silica-based macroporous frameworks have been performed by combining sol-gel process, concentrated direct emulsion, lyotropic mesophase and post-synthesis functionalizations. The assynthesized open cell hybrid monoliths exhibit high macroscopic porosity, around 90%, providing interconnected scaffold while reducing the diffusion low kinetic issue. The entrapment of enzymes in such foams deals with a high stability over esterification of fatty acids, hydrolysis of triglycerides (not shown herein) and biodiesel production by transesterification. (orig.)

  6. Starch-based aerogels: airy materials from amylose-sodium palmitate inclusion complexes

    Science.gov (United States)

    Aerogels are a class of interesting low density porous materials prepared by replacing the water phase contained within a hydrogel with a gas phase while maintaining the three dimensional network structure of the gel. The investigation of starch and hydrocolloid-based aerogels has received attentio...

  7. Quartz/fused silica chip carriers

    Science.gov (United States)

    1992-01-01

    The primary objective of this research and development effort was to develop monolithic microwave integrated circuit (MMIC) packaging which will operate efficiently at millimeter-wave frequencies. The packages incorporated fused silica as the substrate material which was selected due to its favorable electrical properties and potential performance improvement over more conventional materials for Ka-band operation. The first step towards meeting this objective is to develop a package that meets standard mechanical and thermal requirements using fused silica and to be compatible with semiconductor devices operating up to at least 44 GHz. The second step is to modify the package design and add multilayer and multicavity capacity to allow for application specific integrated circuits (ASIC's) to control multiple phase shifters. The final step is to adapt the package design to a phased array module with integral radiating elements. The first task was a continuation of the SBIR Phase 1 work. Phase 1 identified fused silica as a viable substrate material by demonstrating various plating, machining, and adhesion properties. In Phase 2 Task 1, a package was designed and fabricated to validate these findings. Task 2 was to take the next step in packaging and fabricate a multilayer, multichip module (MCM). This package is the predecessor to the phased array module and demonstrates the ability to via fill, circuit print, laminate, and to form vertical interconnects. The final task was to build a phased array module. The radiating elements were to be incorporated into the package instead of connecting to it with wire or ribbon bonds.

  8. Carbon aerogel composites prepared by ambient drying and using oxidized polyacrylonitrile fibers as reinforcements.

    Science.gov (United States)

    Feng, Junzong; Zhang, Changrui; Feng, Jian; Jiang, Yonggang; Zhao, Nan

    2011-12-01

    Carbon fiber-reinforced carbon aerogel composites (C/CAs) for thermal insulators were prepared by copyrolysis of resorcinol-formaldehyde (RF) aerogels reinforced by oxidized polyacrylonitrile (PAN) fiber felts. The RF aerogel composites were obtained by impregnating PAN fiber felts with RF sols, then aging, ethanol exchanging, and drying at ambient pressure. Upon carbonization, the PAN fibers shrink with the RF aerogels, thus reducing the difference of shrinkage rates between the fiber reinforcements and the aerogel matrices, and resulting in C/CAs without any obvious cracks. The three point bend strength of the C/CAs is 7.1 ± 1.7 MPa, and the thermal conductivity is 0.328 W m(-1) K(-1) at 300 °C in air. These composites can be used as high-temperature thermal insulators (in inert atmospheres or vacuum) or supports for phase change materials in thermal protection system. © 2011 American Chemical Society

  9. Direct Ink Write (DIW) 3D Printed Cellulose Nanocrystal Aerogel Structures.

    Science.gov (United States)

    Li, Vincent Chi-Fung; Dunn, Conner K; Zhang, Zhe; Deng, Yulin; Qi, H Jerry

    2017-08-14

    Pure cellulose nanocrystal (CNC) aerogels with controlled 3D structures and inner pore architecture are printed using the direct ink write (DIW) technique. While traditional cellulosic aerogel processing approaches lack the ability to easily fabricate complete aerogel structures, DIW 3D printing followed by freeze drying can overcome this shortcoming and can produce CNC aerogels with minimal structural shrinkage or damage. The resultant products have great potential in applications such as tissue scaffold templates, drug delivery, packaging, etc., due to their inherent sustainability, biocompatibility, and biodegradability. Various 3D structures are successfully printed without support material, and the print quality can be improved with increasing CNC concentration and printing resolution. Dual pore CNC aerogel scaffolds are also successfully printed, where the customizable 3D structure and inner pore architecture can potentially enable advance CNC scaffold designs suited for specific cell integration requirements.

  10. Multifunctional Carbon Aerogels Derived by Sol–Gel Process of Natural Polysaccharides of Different Botanical Origin

    Directory of Open Access Journals (Sweden)

    Monika Bakierska

    2017-11-01

    Full Text Available In this manuscript, we describe the results of our recent studies on carbon aerogels derived from natural starches. A facile method for the fabrication of carbon aerogels is presented. Moreover, the complete analysis of the carbonization process of different starch aerogels (potato, maize, and rice was performed using thermogravimetric studies combined with a detailed analysis of evolved decomposition products. The prepared carbon aerogels were studied in terms of their morphology and electrical properties to relate the origin of starch precursor with final properties of carbon materials. The obtained results confirmed the differences in carbon aerogels’ morphology, especially in materials’ specific surface areas, depending on the botanical origin of precursors. The electrical conductivity measurements suggest that carbon aerogels with the best electrical properties can be obtained from potato starch.

  11. Monolithic graphene oxide sheets with controllable composition.

    Science.gov (United States)

    Chu, Jae Hwan; Kwak, Jinsung; Kim, Sung-Dae; Lee, Mi Jin; Kim, Jong Jin; Park, Soon-Dong; Choi, Jae-Kyung; Ryu, Gyeong Hee; Park, Kibog; Kim, Sung Youb; Kim, Ji Hyun; Lee, Zonghoon; Kim, Young-Woon; Kwon, Soon-Yong

    2014-02-28

    Graphene oxide potentially has multiple applications and is typically prepared by solution-based chemical means. To date, the synthesis of a monolithic form of graphene oxide that is crucial to the precision assembly of graphene-based devices has not been achieved. Here we report the physical approach to produce monolithic graphene oxide sheets on copper foil using solid carbon, with tunable oxygen-to-carbon composition. Experimental and theoretical studies show that the copper foil provides an effective pathway for carbon diffusion, trapping the oxygen species dissolved in copper and enabling the formation of monolithic graphene oxide sheets. Unlike chemically derived graphene oxide, the as-synthesized graphene oxide sheets are electrically active, and the oxygen-to-carbon composition can be tuned during the synthesis process. As a result, the resulting graphene oxide sheets exhibit tunable bandgap energy and electronic properties. Our solution-free, physical approach may provide a path to a new class of monolithic, two-dimensional chemically modified carbon sheets.

  12. Methacrylate monolithic columns functionalized with epinephrine for capillary electrochromatography applications.

    Science.gov (United States)

    Carrasco-Correa, Enrique Javier; Ramis-Ramos, Guillermo; Herrero-Martínez, José Manuel

    2013-07-12

    Epinephrine-bonded polymeric monoliths for capillary electrochromatography (CEC) were developed by nucleophilic substitution reaction of epoxide groups of poly(glycidyl-methacrylate-co-ethylenedimethacrylate) (poly(GMA-co-EDMA)) monoliths using epinephrine as nucleophilic reagent. The ring opening reaction under dynamic conditions was optimized. Successful chemical modification of the monolith surface was ascertained by in situ Raman spectroscopy characterization. In addition, the amount of epinephrine groups that was bound to the monolith surface was evaluated by oxidation of the catechol groups with Ce(IV), followed by spectrophotometric measurement of unreacted Ce(IV). About 9% of all theoretical epoxide groups of the parent monolith were bonded to epinephrine. The chromatographic behavior of the epinephrine-bonded monolith in CEC conditions was assessed with test mixtures of alkyl benzenes, aniline derivatives and substituted phenols. In comparison to the poly(GMA-co-EDMA) monoliths, the epinephrine-bonded monoliths exhibited a much higher retention and slight differences in selectivity. The epinephrine-bonded monolith was further modified by oxidation with a Ce(IV) solution and compared with the epinephrine-bonded monoliths. The resulting monolithic stationary phases were evaluated in terms of reproducibility, giving RSD values below 9% in the parameters investigated. Copyright © 2013 Elsevier B.V. All rights reserved.

  13. Fabrication of molecularly imprinted hybrid monoliths via a room temperature ionic liquid-mediated nonhydrolytic sol-gel route for chiral separation of zolmitriptan by capillary electrochromatography.

    Science.gov (United States)

    Wang, He-Fang; Zhu, Yi-Zhou; Lin, Jian-Ping; Yan, Xiu-Ping

    2008-02-01

    A room temperature ionic liquid (RTIL)-mediated nonhydrolytic sol-gel (NHSG) protocol was explored for the fabrication of new molecularly imprinted silica-based hybrid monoliths for chiral separation of a basic template zolmitriptan by CEC. The RTIL-mediated NHSG protocol involved free-radical copolymerization and NHSG process. Three carboxylic acids (trifluoromethyl acrylic acid, cinnamic acid, and methacrylic acid (MAA)) were examined as both the functional monomers and the catalysts for the NHSG condensation of methacryloxypropyltrimethoxysilane (MPTMS) to form silica-based framework. RTIL was incorporated to reduce gel shrinkage and also to act as the pore template. The effects of carboxylic acids and RTIL on the performance of the silica-based hybrid molecularly imprinted polymer (MIP) monoliths were investigated in detail to realize excellent chiral recognition and to give new insights into the mechanism of the RTIL-mediated NHSG strategy. Excellent chiral separation of (R)/(S)-zolmitriptan was achieved when the molar ratio of MAA to MPTMS was 1:4 and 1:2 with RTIL involved. The synergism of the free-radical copolymerization of the C=C bond of carboxylic acids and MPTMS with the NHSG condensation of MPTMS catalyzed by the carboxylic acids was demonstrated. The incorporation of RTIL increased porosity, and hence improved selectivity of the prepared hybrid monoliths.

  14. Three-dimensional opal-like silica foams.

    Science.gov (United States)

    Carn, Florent; Saadaoui, Hassan; Massé, Pascal; Ravaine, Serge; Julian-Lopez, Beatriz; Sanchez, Clément; Deleuze, Hervé; Talham, Daniel R; Backov, Rénal

    2006-06-06

    The synthesis of novel meso-/macroporous SiO2 monoliths by combining a nano-building-blocks-based approach with the confined geometry of a tailored air-liquid foam structure is described. The resulting macrostructure in which ordered close-packed colloidal silica nanoparticles constitute the monolith's scaffolds very closely resembles the tailored periodic air-liquid foam template. The void spaces between adjacent particles create textural mesoporosity; therefore, the as-prepared silica networks are characterized by hierarchical porosity at the macroscopic and mesoscopic length scales. The fine-tuning of both the liquid foam's fraction and the bubble size allows a rational design over the macroscopic cell morphologies (shape, Plateau border's length, and width). Striking results of this approach are the weak shrinkage of the as-synthesized opal-like scaffolds during the thermally induced sintering process and, in contrast with previous studies, the formation of closed-cell structures. Particle organization and the foam film surface roughness are investigated by atomic force microscopy (AFM), showing the influence of the liquid flow, within the foams' Plateau borders and films, on the final assemblies.

  15. Aerogels with 3D ordered nanofiber skeletons of liquid-crystalline nanocellulose derivatives as tough and transparent insulators.

    Science.gov (United States)

    Kobayashi, Yuri; Saito, Tsuguyuki; Isogai, Akira

    2014-09-22

    Aerogels of high porosity and with a large internal surface area exhibit outstanding performances as thermal, acoustic, or electrical insulators. However, most aerogels are mechanically brittle and optically opaque, and the structural and physical properties of aerogels strongly depend on their densities. The unfavorable characteristics of aerogels are intrinsic to their skeletal structures consisting of randomly interconnected spherical nanoparticles. A structurally new type of aerogel with a three-dimensionally ordered nanofiber skeleton of liquid-crystalline nanocellulose (LC-NCell) is now reported. This LC-NCell material is composed of mechanically strong, surface-carboxylated cellulose nanofibers dispersed in a nematic LC order. The LC-NCell aerogels are transparent and combine mechanical toughness and good insulation properties. These properties of the LC-NCell aerogels could also be readily controlled. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Electrochemical Sensors: Functionalized Silica

    Energy Technology Data Exchange (ETDEWEB)

    Fryxell, Glen E.; Lin, Yuehe; Yantasee, Wassana

    2009-03-24

    This chapter summarizes recent devellopment of electrochemical sensors based on functionlized mesoporous silica materials. The nanomatrials based sensors have been developed for sensitive and selective enrironmental detection of toxic heavy metal and uranium ions.

  17. Effects of pressure and frictional heating on protein separation using monolithic columns in reversed-phase chromatography.

    Science.gov (United States)

    Mann, Benjamin F; Makarov, Alexey A; Wang, Heather; Welch, Christopher J

    2017-03-17

    Pressure is not typically controlled or adjusted independently of flow rate during method development in reversed-phase LC (RPLC). However, it has been shown that pressure has an effect on analyte molecular molar volume, and the magnitude of this effect is greater for proteins and ionizable compounds than neutral small molecules. This phenomenon has received attention recently in the context of porous sub-2-micron particle packed columns. The present study surveys the effect of pressure and frictional heating on RPLC separations using commercially-available monolithic columns at constant flow rate and with controlled external temperature. Because the current monoliths cannot be operated at high pressures, all experiments were conducted with pressures at or below 200bar. Nonetheless, substantial changes in retention were still observed; for example, an increase in pressure of 75bar shifted the retention factor for bovine insulin from 1.27 to 1.78, a 40% increase, while a similar experiment with the neutral small molecule, toluene, showed no change in retention. Results are presented from investigations of model peptides and proteins ranging in size from 1kDa to 30kDa, as well as experiments performed with a silica-based C18 monolith and a polystyrene divinylbenzene monolith functionalized with a phenyl stationary phase. This work indicates that protein separations in monoliths are highly pressure sensitive, and pressure should therefore be considered as an additional parameter in method development for optimizing retention and selectivity. Given these findings, and the ever-increasing importance of chromatographic separations of proteins in both industrial and academic laboratories, improved instrumentation and mechanisms for directly controlling system backpressure could be of great practical value. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. The dynamics of monolithic suspensions for advanced detectors: A 3-segment model

    Energy Technology Data Exchange (ETDEWEB)

    Piergiovanni, F; Campagna, E; Cesarini, E; Martelli, F; Vetrano, F; Vicere, A [Universita di Urbino, Via S.Chiara 27, 61029 Urbino (Italy); Lorenzini, M; Cagnoli, G; Losurdo, G, E-mail: piergiovanni@fi.infn.i [INFN, Istituto Nazionale di Fisica Nucleare, Sez. di Firenze, via G. Sansone 1, 50019 Sesto Fiorentino (Italy)

    2010-05-01

    In order to reduce the suspension thermal noise, the second generation GW interferometric detectors will employ monolithic suspensions in fused silica to hold the mirrors. The fibres are produced by melting and pulling apart a fused silica rod, obtaining a long thin wire with two thicker heads. The dynamics of such a fibre is in principle different from that of a cylindrical, regular fibre, because most of the deformation energy is stored in the neck region where the diameter is variable. This is an advantage, since adjusting the neck tapering, a thermoelastic noise cancellation effect can be obtained. Therefore, a careful study of the suspensions behavior is necessary to estimate the overall noise and to optimize the control strategy. To simplify the control design, a simple three segment model for the silica fibres has been developed, fully equivalent to the beam equation at low frequencies. The model, analytically proved for a regular cylindrical fibre, can be extended to a fibre with tapered necks, provided that the equivalent bending length is suitably measured. We developed a tool to measure the position of the bending point for each fibre, thus allowing to experimentally check the validity of the model. A numerical code has been written to solve the beam equation for wires with varying diameter. This code confirms the validity of the three segment model. Moreover, it is possible to extend the solution to higher frequencies thus computing the transfer function and the energy distribution of the suspension system and estimating the thermal noise contribution.

  19. Preparation and evaluation of 400μm I.D. polymer-based hydrophilic interaction chromatography monolithic columns with high column efficiency.

    Science.gov (United States)

    Liu, Chusheng; Li, Haibin; Wang, Qiqin; Crommen, Jacques; Zhou, Haibo; Jiang, Zhengjin

    2017-08-04

    The quest for higher column efficiency is one of the major research areas in polymer-based monolithic column fabrication. In this research, two novel polymer-based HILIC monolithic columns with 400μm I.D.×800μm O.D. were prepared based on the thermally initiated co-polymerization of N,N-dimethyl-N-(3-methacrylamidopropyl)-N-(3-sulfopropyl) ammonium betaine (SPP) and ethylene glycol dimethacrylate (EDMA) or N,N'-methylenebisacrylamide (MBA). In order to obtain a satisfactory performance in terms of column permeability, mechanical stability, efficiency and selectivity, the polymerization parameters were systematically optimized. Column efficiencies as high as 142, 000 plates/m and 120, 000 plates/m were observed for the analysis of neutral compounds at 0.6mm/s on the poly(SPP-co-MBA) and poly(SPP-co-EDMA) monoliths, respectively. Furthermore, the Van Deemter plots for thiourea on the two monoliths were compared with that on a commercial silica based ZIC-HILIC column (3.5μm, 200Å, 150mm×300μm I.D.) using ACN/H 2 O (90/10, v/v) as the mobile phase at room temperature. It was noticeable that the Van Deemter curves for both monoliths, particularly the poly(SPP-co-MBA) monolith, are significantly flatter than that obtained for the ZIC-HILIC column, which indicates that in spite of their larger internal diameters, they yield better overall efficiency, with less peak dispersion, across a much wider range of usable linear velocities. A clearly better separation performance was also observed for nucleobases, nucleosides, nucleotides and small peptides on the poly(SPP-co-MBA) monolith compared to the ZIC-HILIC column. It is particularly worth mentioning that these 400μm I.D. polymer-based HILIC monolithic columns exhibit enhanced mechanical strength owing to the thicker capillary wall of the fused-silica capillaries. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Inorganic hollow nanotube aerogels by atomic layer deposition onto native nanocellulose templates.

    Science.gov (United States)

    Korhonen, Juuso T; Hiekkataipale, Panu; Malm, Jari; Karppinen, Maarit; Ikkala, Olli; Ras, Robin H A

    2011-03-22

    Hollow nano-objects have raised interest in applications such as sensing, encapsulation, and drug-release. Here we report on a new class of porous materials, namely inorganic nanotube aerogels that, unlike other aerogels, have a framework consisting of inorganic hollow nanotubes. First we show a preparation method for titanium dioxide, zinc oxide, and aluminum oxide nanotube aerogels based on atomic layer deposition (ALD) on biological nanofibrillar aerogel templates, that is, nanofibrillated cellulose (NFC), also called microfibrillated cellulose (MFC) or nanocellulose. The aerogel templates are prepared from nanocellulose hydrogels either by freeze-drying in liquid nitrogen or liquid propane or by supercritical drying, and they consist of a highly porous percolating network of cellulose nanofibrils. They can be prepared as films on substrates or as freestanding objects. We show that, in contrast to freeze-drying, supercritical drying produces nanocellulose aerogels without major interfibrillar aggregation even in thick films. Uniform oxide layers are readily deposited by ALD onto the fibrils leading to organic-inorganic core-shell nanofibers. We further demonstrate that calcination at 450 °C removes the organic core leading to purely inorganic self-supporting aerogels consisting of hollow nanotubular networks. They can also be dispersed by grinding, for example, in ethanol to create a slurry of inorganic hollow nanotubes, which in turn can be deposited to form a porous film. Finally we demonstrate the use of a titanium dioxide nanotube network as a resistive humidity sensor with a fast response.

  1. Preparation of hydrophobic polyvinyl alcohol aerogel via the surface modification of boron nitride for environmental remediation

    Science.gov (United States)

    Zhang, Ruiyang; Wan, Wenchao; Qiu, Lijuan; Wang, Yonghua; Zhou, Ying

    2017-10-01

    Macroscopic polyvinyl alcohol (PVA) aerogel is of great interest in environmental remediation due to its low cost and easy fabrication. However, the hydrophily of PVA aerogel limited its application in oil-water separation. In this work, boron nitride (BN)-modified PVA aerogel has been successfully prepared by a cost-effective frozen-drying method. PVA plays a role as a scaffold of aerogel to support BN nanosheets which can modify the surface properties of PVA aerogel, resulting in a dramatic change of wettability from hydrophily (0°) to hydrophobicity (94.9°-100.8°). Moreover, the obtained BN-modified PVA aerogel possesses a favorable porous structure, low density (41.8-60.0 mg/cm3) and good adsorption capacity (12-38 g/g), which make it a promising wastewater treatment material. Importantly, PVA aerogel with other functions can be easily fabricated through coupling with other inorganic materials by this strategy, which can provide various promising applications for environmental remediation.

  2. Copper Nanowire-Based Aerogel with Tunable Pore Structure and Its Application as Flexible Pressure Sensor.

    Science.gov (United States)

    Xu, Xiaojuan; Wang, Ranran; Nie, Pu; Cheng, Yin; Lu, Xiaoyu; Shi, Liangjing; Sun, Jing

    2017-04-26

    Aerogel is a kind of material with high porosity and low density. However, the research on metal-based aerogel with good conductivity is quite limited, which hinders its usage in electronic devices, such as flexible pressure sensors. In this work, we successfully fabricate copper nanowire (CuNW) based aerogel through a one-pot method, and the dynamics for the assembly of CuNWs into hydrogel is intensively investigated. The "bubble controlled assembly" mechanism is put forward for the first time, according to which tunable pore structures and densities (4.3-7.5 mg cm -3 ) of the nanowire aerogel is achieved. Subsequently, ultralight flexible pressure sensors with tunable sensitivities (0.02 kPa -1 to 0.7 kPa -1 ) are fabricated from the Cu NWs aerogels, and the negative correlation behavior of the sensitivity to the density of the aerogel sensors is disclosed systematically. This work provides a versatile strategy for the fabrication of nanowire-based aerogels, which greatly broadens their application potential.

  3. Tert-butyl alcohol used to fabricate nano-cellulose aerogels via freeze-drying technology

    Science.gov (United States)

    Wang, Xiaoyu; Zhang, Yang; Jiang, Hua; Song, Yuxuan; Zhou, Zhaobing; Zhao, Hua

    2017-06-01

    Aerogel, a highly porous material, is attracting increasing attention owing to low thermal conductivity and high specific surface area. Freeze-drying technology has been employed to produce nano-cellulose aerogels; however, the resultant product has low specific surface areas. Here, a modified approach to prepare nano-cellulose aerogels was reported, which involves tert-butyl alcohol as a solvent. Nano-cellulose aerogels were prepared via a spontaneous gelation fashion using calcium chloride solution, followed by tert-butyl alcohol solvent displacement and freeze drying. Addition of calcium chloride (0.25%) accelerated the physical gelation process. The application of tert-butyl alcohol as a solvent contributed to preservation of gel network. The obtained spherical nano-cellulose aerogels had a shrinkage rate of 5.89%. The specific surface area and average pore size was 164. 9666 m2 g-1 and 10.01 nm, respectively. Additionally, nano-cellulose aerogels had a comparable thermal degradation property when compared to microcrystalline cellulose. These biophysical properties make nano-cellulose aerogels as a promising absorption material.

  4. Critical behavior of superfluid {sup 4}He in aerogel

    Energy Technology Data Exchange (ETDEWEB)

    Moon, K. [Department of Physics, University of California, Davis, California 95616 (United States); Girvin, S.M. [Department of Physics, Indiana University, Bloomington, Indiana 47405 (United States)

    1995-08-14

    We report Monte Carlo studies of the critical behavior of superfluid {sup 4}He in the presence of quenched disorder with long-range fractal correlations. Modeling aerogel as an incipient percolating cluster in 3D and weakening the bonds at the fractal sites, {ital XY}-model simulations demonstrate an increase in the superfluid density exponent {zeta} from 0.67{plus_minus}0.005 for the pure case to an apparent value of 0.722{plus_minus}0.005 in the presence of the fractal disorder, provided that the helium correlation length does not exceed the fractal correlation length.

  5. Electrochemical properties of carbon aerogels with freeze - drying

    Science.gov (United States)

    Xu, Yuelong; Yan, Meifang; Liua, Zhenfa

    2017-09-01

    Carbon aerogels (CAs) were prepared via a sol-gel process by polymerization of phloroglucinol, resorcinol and formaldehyde using 2,4-dihydroxybenzoic acid as catalyst with freeze-drying. The electrochemical properties were characterized using cyclic voltammetry, galvanostatic charge-discharge measurements and electrochemical impedance spectroscopy (EIS). The specific capacitance of corresponding CAs was up to 131 F g-1 and 105 F g-1 at the density of 0.5 A g-1 and 1.0 A g-1, respectively.

  6. Test of the TRAPPISTe monolithic detector system

    Science.gov (United States)

    Soung Yee, L.; Álvarez, P.; Martin, E.; Cortina, E.; Ferrer, C.

    2013-12-01

    A monolithic pixel detector named TRAPPISTe-2 has been developed in Silicon-on-Insulator (SOI) technology. A p-n junction is implanted in the bottom handle wafer and connected to readout electronics integrated in the top active layer. The two parts are insulated from each other by a buried oxide layer resulting in a monolithic detector. Two small pixel matrices have been fabricated: one containing a 3-transistor readout and a second containing a charge sensitive amplifier readout. These two readout structures have been characterized and the pixel matrices were tested with an infrared laser source. The readout circuits are adversely affected by the backgate effect, which limits the voltage that can be applied to the metal back plane to deplete the sensor, thus narrowing the depletion width of the sensor. Despite the low depletion voltages, the integrated pixel matrices were able to respond to and track a laser source.

  7. Monolithic pixel detectors for high energy physics

    CERN Document Server

    Snoeys, W

    2013-01-01

    Monolithic pixel detectors integrating sensor matrix and readout in one piece of silicon have revolutionized imaging for consumer applications, but despite years of research they have not yet been widely adopted for high energy physics. Two major requirements for this application, radiation tolerance and low power consumption, require charge collection by drift for the most extreme radiation levels and an optimization of the collected signal charge over input capacitance ratio ( Q / C ). It is shown that monolithic detectors can achieve Q / C for low analog power consumption and even carryout the promise to practically eliminate analog power consumption, but combining suf fi cient Q / C , collection by drift, and integration of readout circuitry within the pixel remains a challenge. An overview is given of different approaches to address this challenge, with possible advantages and disadvantages.

  8. Update On Monolithic Fuel Fabrication Development

    Energy Technology Data Exchange (ETDEWEB)

    C. R Clark; J. M. Wight; G. C. Knighton; G. A. Moore; J. F. Jue

    2005-11-01

    Efforts to develop a viable monolithic research reactor fuel plate have continued at Idaho National Laboratory. These efforts have concentrated on both fabrication process refinement and scale-up to produce full sized fuel plates. Advancements have been made in the production of U-Mo foil including full sized foils. Progress has also been made in the friction stir welding and transient liquid phase bonding fabrication processes resulting in better bonding, more stable processes and the ability to fabricate larger fuel plates.

  9. FLUIDIZED BED STEAM REFORMER MONOLITH FORMATION

    Energy Technology Data Exchange (ETDEWEB)

    Jantzen, C

    2006-12-22

    Fluidized Bed Steam Reforming (FBSR) is being considered as an alternative technology for the immobilization of a wide variety of aqueous high sodium containing radioactive wastes at various DOE facilities in the United States. The addition of clay, charcoal, and a catalyst as co-reactants converts aqueous Low Activity Wastes (LAW) to a granular or ''mineralized'' waste form while converting organic components to CO{sub 2} and steam, and nitrate/nitrite components, if any, to N{sub 2}. The waste form produced is a multiphase mineral assemblage of Na-Al-Si (NAS) feldspathoid minerals with cage-like structures that atomically bond radionuclides like Tc-99 and anions such as SO{sub 4}, I, F, and Cl. The granular product has been shown to be as durable as LAW glass. Shallow land burial requires that the mineralized waste form be able to sustain the weight of soil overburden and potential intrusion by future generations. The strength requirement necessitates binding the granular product into a monolith. FBSR mineral products were formulated into a variety of monoliths including various cements, Ceramicrete, and hydroceramics. All but one of the nine monoliths tested met the <2g/m{sup 2} durability specification for Na and Re (simulant for Tc-99) when tested using the Product Consistency Test (PCT; ASTM C1285). Of the nine monoliths tested the cements produced with 80-87 wt% FBSR product, the Ceramicrete, and the hydroceramic produced with 83.3 wt% FBSR product, met the compressive strength and durability requirements for an LAW waste form.

  10. FRACTURE-RESISTANT MONOLITHIC DENTAL CROWNS

    Science.gov (United States)

    Zhang, Yu; Mai, Zhisong; Barani, Amir; Bush, Mark; Lawn, Brian

    2016-01-01

    Objective To quantify the splitting resistance of monolithic zirconia, lithium disilicate and nanoparticle-composite dental crowns. Methods Fracture experiments were conducted on anatomically-correct monolithic crown structures cemented to standard dental composite dies, by axial loading of a hard sphere placed between the cusps. The structures were observed in situ during fracture testing, and critical loads to split the structures were measured. Extended finite element modeling (XFEM), with provision for step-by-step extension of embedded cracks, was employed to simulate full failure evolution. Results Experimental measurements and XFEM predictions were self consistent within data scatter. In conjunction with a fracture mechanics equation for critical splitting load, the data were used to predict load-sustaining capacity for crowns on actual dentin substrates and for loading with a sphere of different size. Stages of crack propagation within the crown and support substrate were quantified. Zirconia crowns showed the highest fracture loads, lithium disilicate intermediate, and dental nanocomposite lowest. Dental nanocomposite crowns have comparable fracture resistance to natural enamel. Significance The results confirm that monolithic crowns are able to sustain high bite forces. The analysis indicates what material and geometrical properties are important in optimizing crown performance and longevity. PMID:26792623

  11. Characterization of SOI monolithic detector system

    Science.gov (United States)

    Álvarez-Rengifo, P. L.; Soung Yee, L.; Martin, E.; Cortina, E.; Ferrer, C.

    2013-12-01

    A monolithic active pixel sensor for charged particle tracking was developed. This research is performed within the framework of an R&D project called TRAPPISTe (Tracking Particles for Physics Instrumentation in SOI Technology) whose aim is to evaluate the feasibility of developing a Monolithic Active Pixel Sensor (MAPS) with Silicon-on-Insulator (SOI) technology. Two chips were fabricated: TRAPPISTe-1 and TRAPPISTe-2. TRAPPISTe-1 was produced at the WINFAB facility at the Université catholique de Louvain (UCL), Belgium, in a 2 μm fully depleted (FD-SOI) CMOS process. TRAPPISTe-2 was fabricated with the LAPIS 0.2 μm FD-SOI CMOS process. The electrical characterization on single transistor test structures and of the electronic readout for the TRAPPISTe series of monolithic pixel detectors was carried out. The behavior of the prototypes’ electronics as a function of the back voltage was studied. Results showed that both readout circuits exhibited sensitivity to the back voltage. Despite this unwanted secondary effect, the responses of TRAPPISTe-2 amplifiers can be improved by a variation in the circuit parameters.

  12. Fracture-resistant monolithic dental crowns.

    Science.gov (United States)

    Zhang, Yu; Mai, Zhisong; Barani, Amir; Bush, Mark; Lawn, Brian

    2016-03-01

    To quantify the splitting resistance of monolithic zirconia, lithium disilicate and nanoparticle-composite dental crowns. Fracture experiments were conducted on anatomically-correct monolithic crown structures cemented to standard dental composite dies, by axial loading of a hard sphere placed between the cusps. The structures were observed in situ during fracture testing, and critical loads to split the structures were measured. Extended finite element modeling (XFEM), with provision for step-by-step extension of embedded cracks, was employed to simulate full failure evolution. Experimental measurements and XFEM predictions were self-consistent within data scatter. In conjunction with a fracture mechanics equation for critical splitting load, the data were used to predict load-sustaining capacity for crowns on actual dentin substrates and for loading with a sphere of different size. Stages of crack propagation within the crown and support substrate were quantified. Zirconia crowns showed the highest fracture loads, lithium disilicate intermediate, and dental nanocomposite lowest. Dental nanocomposite crowns have comparable fracture resistance to natural enamel. The results confirm that monolithic crowns are able to sustain high bite forces. The analysis indicates what material and geometrical properties are important in optimizing crown performance and longevity. Copyright © 2015 Academy of Dental Materials. All rights reserved.

  13. Metal oxide nanorod arrays on monolithic substrates

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Pu-Xian; Guo, Yanbing; Ren, Zheng

    2018-01-02

    A metal oxide nanorod array structure according to embodiments disclosed herein includes a monolithic substrate having a surface and multiple channels, an interface layer bonded to the surface of the substrate, and a metal oxide nanorod array coupled to the substrate surface via the interface layer. The metal oxide can include ceria, zinc oxide, tin oxide, alumina, zirconia, cobalt oxide, and gallium oxide. The substrate can include a glass substrate, a plastic substrate, a silicon substrate, a ceramic monolith, and a stainless steel monolith. The ceramic can include cordierite, alumina, tin oxide, and titania. The nanorod array structure can include a perovskite shell, such as a lanthanum-based transition metal oxide, or a metal oxide shell, such as ceria, zinc oxide, tin oxide, alumina, zirconia, cobalt oxide, and gallium oxide, or a coating of metal particles, such as platinum, gold, palladium, rhodium, and ruthenium, over each metal oxide nanorod. Structures can be bonded to the surface of a substrate and resist erosion if exposed to high velocity flow rates.

  14. Electrically driven monolithic subwavelength plasmonic interconnect circuits.

    Science.gov (United States)

    Liu, Yang; Zhang, Jiasen; Liu, Huaping; Wang, Sheng; Peng, Lian-Mao

    2017-10-01

    In the post-Moore era, an electrically driven monolithic optoelectronic integrated circuit (OEIC) fabricated from a single material is pursued globally to enable the construction of wafer-scale compact computing systems with powerful processing capabilities and low-power consumption. We report a monolithic plasmonic interconnect circuit (PIC) consisting of a photovoltaic (PV) cascading detector, Au-strip waveguides, and electrically driven surface plasmon polariton (SPP) sources. These components are fabricated from carbon nanotubes (CNTs) via a CMOS (complementary metal-oxide semiconductor)-compatible doping-free technique in the same feature size, which can be reduced to deep-subwavelength scale (~λ/7 to λ/95, λ = 1340 nm) compared with the 14-nm technique node. An OEIC could potentially be configured as a repeater for data transport because of its "photovoltaic" operation mode to transform SPP energy directly into electricity to drive subsequent electronic circuits. Moreover, chip-scale throughput capability has also been demonstrated by fabricating a 20 × 20 PIC array on a 10 mm × 10 mm wafer. Tailoring photonics for monolithic integration with electronics beyond the diffraction limit opens a new era of chip-level nanoscale electronic-photonic systems, introducing a new path to innovate toward much faster, smaller, and cheaper computing frameworks.

  15. An overview of monolithic zirconia in dentistry

    Directory of Open Access Journals (Sweden)

    Özlem Malkondu

    2016-07-01

    Full Text Available Zirconia restorations have been used successfully for years in dentistry owing to their biocompatibility and good mechanical properties. Because of their lack of translucency, zirconia cores are generally veneered with porcelain, which makes restorations weaker due to failure of the adhesion between the two materials. In recent years, all-ceramic zirconia restorations have been introduced in the dental sector with the intent to solve this problem. Besides the elimination of chipping, the reduced occlusal space requirement seems to be a clear advantage of monolithic zirconia restorations. However, scientific evidence is needed to recommend this relatively new application for clinical use. This mini-review discusses the current scientific literature on monolithic zirconia restorations. The results of in vitro studies suggested that monolithic zirconia may be the best choice for posterior fixed partial dentures in the presence of high occlusal loads and minimal occlusal restoration space. The results should be supported with much more in vitro and particularly in vivo studies to obtain a final conclusion.

  16. Measurement of the eddy dispersion term in chromatographic columns: III. Application to new prototypes of 4.6 mm I.D. monolithic columns.

    Science.gov (United States)

    Gritti, Fabrice; Guiochon, Georges

    2012-02-17

    We investigated the mass transfer mechanism in four research prototypes of silica monolithic columns of the second generation provided by their manufacturer (Merck KGaA, Darmstadt, Germany). The heights equivalent to a theoretical plate (HETP) of these columns were measured. The different contributions to the total HETP (longitudinal diffusion term B/u(S), skeleton/eluent mass transfer resistance term Cu(S), and eddy diffusion term A) were determined experimentally for a non-retained (uracil) and for a retained (naphthalene) compound. We used the peak parking method to determine the longitudinal diffusion term, a recently developed accurate model of effective diffusion in silica monolithic structures to determine the skeleton/eluent mass transfer resistance term, and an accurate method of measurement of the total column HETP to determine the eddy diffusion term. The results show that the minimum plate heights of these monolithic column prototypes range between 6 and 7 μm for retained analytes, three times lower than those observed for monolithic columns of the first generation. A detailed analysis of the eddy diffusion term demonstrates that the improvement observed in the column efficiency is explained in part by the 40% reduction of the domain size (which provides thinner half-height peak width) but mostly by a two-fold decrease of the radial velocity bias across the silica rods (which provides more symmetrical peaks). Yet, the rods in these columns exhibit a residual radial heterogeneity leading to a minimum HETP of only 10 μm for non-retained compounds. Copyright © 2011 Elsevier B.V. All rights reserved.

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

    Science.gov (United States)

    Lei, Qiong

    in disrupting R6G/silica attraction. Similar post-grafting method was applied to highly hydrated silica hydrogel monoliths. Rhodamine 6G (R6G) and fluorescein (Fl) molecules were used as probes to monitor the surface modification inside silica hydrogel by measuring anisotropy values of doped dyes. Due to the larger pore sizes, pore surface modification inside hydrogel was more effective than in alcogel. Surface modification by chemical reactions of 3-Aminopropyltrimethoxysilane (APTS) and methyltriethoxysilane (MTES) showed dramatic effect on guest molecule mobility, whereas surface modification by physical method, that is to increase ionic strength by using 1.0 M sodium chloride or to neutralize pore surfaces by adding pH 2.0 hydrochloric acid, barely showed any effect. Charge-reversal by APTS is a more effective way to modify pore surfaces in hydrogel than hydrophobic capping from MTES. The ease of tracking surface modification inside hydrogel by simply locating R6G dye band, and the negligible pore fluid effect on R6G in modified hydrogel makes R6G a better probe than Fl to monitor the pore surface modification process in silica hydrogel monoliths. During the study of post-grafting on silica alcogel thin film, a new approach to produce stable silica hydrogel-like thin films was discovered. Homogeneous thin film hydrogel-like samples with thickness between 100 nm and 300 nm were produced, and they showed a very hydrophilic surface, high dye loading capacity, and the support of molecular diffusion. The reactive stage of starting silica gel matrix was elongated by increasing environmental humidity, the reproducibility of sample preparation was greatly improved by controlling environmental humidity, and the dye loading capacity of samples was improved more than ten times by using phosphate buffer solutions (PBS). The concentration of R6G trapped inside hydrogel-like thin film could reach as high as 900 times of its saturated aqueous solution. Dye encapsulation can

  18. Kinetics of silica polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Weres, O.; Yee, A.; Tsao, L.

    1980-05-01

    The polymerization of silicic acid in geothermal brine-like aqueous solutions to produce amorphous silica in colloidal form has been studied experimentally and theoretically. A large amount of high quality experimental data has been generated over the temperature rang 23 to 100{sup 0}C. Wide ranges of dissolved silica concentration, pH, and sodium chloride concentration were covered. The catalytic effects of fluoride and the reaction inhibiting effects of aluminum and boron were studied also. Two basic processes have been separately studied: the formation of new colloidal particles by the homogeneous nucleation process and the deposition of dissolved silica on pre-existing colloidal particles. A rigorous theory of the formation of colloidal particles of amorphous silica by homogeneous nucleation was developed. This theory employs the Lothe-Pound formalism, and is embodied in the computer code SILNUC which quantitatively models the homogeneous nucleation and growth of colloidal silica particles in more than enough detail for practical application. The theory and code were extensively used in planning the experimental work and analyzing the data produced. The code is now complete and running in its final form. It is capable of reproducing most of the experimental results to within experimental error. It is also capable of extrapolation to experimentally inaccessible conditions, i.e., high temperatures, rapidly varying temperature and pH, etc.

  19. Immobilized monolithic enzyme reactors for application in proteomics and pharmaceutics.

    Science.gov (United States)

    Spross, Jens; Sinz, Andrea

    2009-11-01

    The use of monolithic supports for a wide variety of applications has rapidly expanded during the past few years. The examples for applications of monoliths presented herein show that the chromatographic performance of bioreactors and affinity media prepared from monolithic media is superior to that of conventional particle-based systems. The ease of fabrication and modification combined with the long lifetime of the monolithic columns and their potential to be used in fully automated analytical systems make them attractive tools for an increasing number of applications.

  20. The Effect of Radiation on Phaseolus vulgaris growth and Aerogel

    Science.gov (United States)

    Boylan, Derek; Durham, Stephanie

    2013-10-01

    Radiation affects human life in disparately subtle and dramatic ways. For instance, nuclear reactions in the Sun produce light and heat that are essential for human existence, while recent research implies that the flux of cosmic ray particles may also have an impact on humans' daily lives. According to the EPA the average American receives 310 mrems of radiation per year, well under a total dose of 50,000 mrems and higher doses that cause symptoms ranging from nausea to death. However, scientists hypothesize that exposure to low doses of ionizing radiation (Phaseolus vulgaris was tested. The same radiation was also tested on the performance of aerogel, a material used in particle detectors. Aerogel will be used in experiments at the 12 GeV Jefferson Laboratory and has been previously observed to change its optical characteristics after being used in experiments. To determine the level of cosmic ray flux and possible contribution to our experiments a detector was created using scintillator material and 2-inch phototubes. Results from our experiments will be presented. Supported in part by NSF grant 1019521 and 1039446.

  1. The Effect of Radiation on Phaseolus vulgaris and Aerogel

    Science.gov (United States)

    Durham, Stephanie; Boylan, Derek

    2013-10-01

    Radiation affects human life in disparately subtle and dramatic ways. For instance, nuclear reactions in the Sun produce light and heat that are essential for human existence, while recent research implies that the flux of cosmic ray particles may also have an impact on humans' daily lives. According to the EPA the average American receives 310 mrems of radiation per year, well under a total dose of 50,000 mrems and higher doses that cause symptoms ranging from nausea to death. However, scientists hypothesize that exposure to low doses of ionizing radiation (Phaseolus vulgaris was tested. The same radiation was also tested on the performance of aerogel, a material used in particle detectors. Aerogel will be used in experiments at the 12 GeV Jefferson Laboratory and has been previously observed to change its optical characteristics after being used in experiments. To determine the level of cosmic ray flux and possible contribution to our experiments a detector was created using scintillator material and 2-inch phototubes. Results from our experiments will be presented. Supported in part by NSF grant 1019521 and 1039446.

  2. Scintillator based on SiO2-aerogel

    International Nuclear Information System (INIS)

    Boyko, I.R.; Ignatenko, M.A.; Esenak, K.; Kuhta, L.; Ruzicka, J.; Fainor, V.

    1995-01-01

    For increasing the light output of SiO 2 -aerogel two aerogel samples were doped with the wavelength shifter POPOP. As a result a scintillator with intermediate density between the gas and the solid state has been produced. The light pulse shapes of the both samples are well approximated by a sum of two exponents with the decay times 1.4±0.1 ns (58% of total light output) and 5.2±0.4 ns (42%). Under irradiation of 5.5 MeV α-particles the light output of the sample with smaller wavelength shifter concentration was 30% and that of the sample with larger concentration was 8% of the light output of a plastic scintillator (polysterene, 2% paraterphenil, 0.2% POPOP). The obtained data indicate that the α/β ratio for both samples is close to 1. This material can be used in experiments where the amount of substance in the way of particles to be detected is a critical factor. (orig.)

  3. Impact Features and Projectile Residues in Aerogel Exposed on Mir

    Science.gov (United States)

    Hörz, F.; Zolensky, M. E.; Bernhard, R. P.; See, T. H.; Warren, J. L.

    2000-10-01

    Approximately 0.63 m 2 of SiO 2-based aerogel (0.02 g cm -3) was exposed for 18 months on the Mir Station to capture hypervelocity particles from both man-made and natural sources. Optical inspection revealed two major classes of hypervelocity impact features in the aerogel: (1) long, carrot-shaped tracks, well known from laboratory impact experiments, that exhibit a depth- ( t) to-diameter ( D) relationship of t/ D>10, typically 20-30, and (2) shallow pits ( t/ DCompositional analyses by SEM-EDS identified a variety of man-made and natural particles. A few natural particles were embedded in epoxy, microtomed, and analyzed by TEM. All were polymineralic aggregates that contained olivine exhibiting sharp electron-diffraction spots, and suggesting that the materials had experienced only minimal shock-deformation, if any. One natural particle contained olivine, augite, diopside, troilite, chromite/magnetite, and hercynite, the latter existing as pristine, undeformed octahedral crystals. The olivine in two of the particles were Fo 60-70 and Fo 39-53, and thus, more equilibrated than olivines in most stratospheric particles (Fo 80-100). These results illustrate that particle collections in Earth orbit are highly complementary to ground-based collections of cosmic dust.

  4. Systematic studies of tannin–formaldehyde aerogels: preparation and properties

    International Nuclear Information System (INIS)

    Amaral-Labat, Gisele; Szczurek, Andrzej; Fierro, Vanessa; Pizzi, Antonio; Celzard, Alain

    2013-01-01

    Gelation of tannin–formaldehyde (TF) solutions was systematically investigated by changing pH and concentration of TF resin in water. In this way we constructed the TF phase diagram, from which chemical hydrogels could be described, and also synthesized thermoreversible tannin-based hydrogels. Conditions of non-gelation were also determined. Hydrogels were dried in supercritical CO 2 , leading to a broad range of TF aerogels. The latter were investigated for volume shrinkage, total porosity, micro-, meso- and macropore volumes, Brunauer–Emmett–Teller (BET) surface area, microscopic texture, mechanical and thermal properties. All these properties are discussed in relation to each other, leading to an accurate and self-consistent description of these bioresource-based highly porous materials. The conditions for obtaining the highest BET surface area or mesopore volume were determined and explained in relation to the preparation conditions. The highest BET surface area, 880 m 2 g −1 , is remarkably high for organic aerogels derived from a natural resource. (paper)

  5. Systematic studies of tannin-formaldehyde aerogels: preparation and properties

    Science.gov (United States)

    Amaral-Labat, Gisele; Szczurek, Andrzej; Fierro, Vanessa; Pizzi, Antonio; Celzard, Alain

    2013-02-01

    Gelation of tannin-formaldehyde (TF) solutions was systematically investigated by changing pH and concentration of TF resin in water. In this way we constructed the TF phase diagram, from which chemical hydrogels could be described, and also synthesized thermoreversible tannin-based hydrogels. Conditions of non-gelation were also determined. Hydrogels were dried in supercritical CO2, leading to a broad range of TF aerogels. The latter were investigated for volume shrinkage, total porosity, micro-, meso- and macropore volumes, Brunauer-Emmett-Teller (BET) surface area, microscopic texture, mechanical and thermal properties. All these properties are discussed in relation to each other, leading to an accurate and self-consistent description of these bioresource-based highly porous materials. The conditions for obtaining the highest BET surface area or mesopore volume were determined and explained in relation to the preparation conditions. The highest BET surface area, 880 m2 g-1, is remarkably high for organic aerogels derived from a natural resource.

  6. Robust naphthyl methacrylate monolithic column for high performance liquid chromatography of a wide range of solutes.

    Science.gov (United States)

    Jonnada, Murthy; El Rassi, Ziad

    2015-08-28

    An organic monolithic column based on the co-polymerization of 2-naphthyl methacrylate (NAPM) as the functional monomer and trimethylolpropane trimethacrylate (TRIM) as the crosslinker was introduced for high performance reversed-phase liquid chromatography (RPC). The co-polymerization was performed in situ in a stainless steel column of 4.6mm i.d. in the presence of a ternary porogen consisting of 1-dodecanol and cyclohexanol. This monolithic column (referred to as naphthyl methacrylate monolithic column or NMM column) showed high mechanical stability at relatively high mobile phase flow velocity indicating that the column has excellent hydrodynamic characteristics. To characterize the NMM column, different probe molecules including alkyl benzenes, and aniline, benzene, toluene and phenol derivatives were chromatographed on the column and the results in terms of k, selectivity and plate counts were compared to those obtained on an octadecyl silica (ODS) column in order to assess the presence of π-π and hydrophobic interactions on the NMM column under otherwise the same elution conditions. The NMM column offered additional π-π interactions with aromatic molecules in addition to hydrophobic interactions under RPC elution conditions. Run-to-run and column-to-column reproducibility of solute k values were evaluated, and percent relative standard deviation of column using shallow (30min at 1.0mL/min), steep (10min at 1.0mL/min) and ultra steep (1min at 3.0mL/min) linear gradient elution at increasing ACN concentration in the mobile phase using a 10cm×4.6mm i.d. column in case of shallow and steep linear gradients and a 3cm×4.6mm i.d. column for ultra steep linear gradient. Copyright © 2015 Elsevier B.V. All rights reserved.

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

    African Journals Online (AJOL)

    Silica coated ionic liquid templated mesoporous silica nanoparticles. E.D.M. Isa, M. B. A. Rahman, H. Ahmad. Abstract. 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 ...

  8. Kinetically controlled synthesis of AuPt bi-metallic aerogels and their enhanced electrocatalytic performances

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Qiurong [School of Mechanical and Materials Engineering; Washington State University; Pullman; USA; Zhu, Chengzhou [School of Mechanical and Materials Engineering; Washington State University; Pullman; USA; Du, Dan [School of Mechanical and Materials Engineering; Washington State University; Pullman; USA; Key Laboratory of Pesticides and Chemical Biology; Bi, Cuixia [Institute of Crystal Materials; Shandong University; Jinan 250100; P. R. China; Xia, Haibing [Institute of Crystal Materials; Shandong University; Jinan 250100; P. R. China; Feng, Shuo [School of Mechanical and Materials Engineering; Washington State University; Pullman; USA; Engelhard, Mark H. [Environmental Molecular Sciences Laboratory; Pacific Northwest National Laboratory; Richland; USA; Lin, Yuehe [School of Mechanical and Materials Engineering; Washington State University; Pullman; USA

    2017-01-01

    Kinetically controlled synthesis of AuPtxbi-metallic hydrogels/aerogels was efficiently achieved for the first timeviatuning the reaction temperature or adding a surfactant.

  9. Structural Modifications of Continuous Aerogel Films for Low-power, High Performance Sensing Capabilities

    Data.gov (United States)

    National Aeronautics and Space Administration — Recent work has found that TiO2 nanorods and nanowires can be grown from a high-surface area, highly porous TiO2 ambiently-dried aerogel structure through varying...

  10. Ignition capsules with aerogel-supported liquid DT fuel for the National Ignition Facility

    Directory of Open Access Journals (Sweden)

    Ho D.D.-M.

    2013-11-01

    Full Text Available For high repetition-rate fusion power plant applications, capsules with aerogel-supported liquid DT fuel can have much reduced fill time compared to β-layering a solid DT fuel layer. The melting point of liquid DT can be lowered once liquid DT is embedded in an aerogel matrix, and the DT vapor density is consequently closer to the desired density for optimal capsule design requirement. We present design for NIF-scale aerogel-filled capsules based on 1-D and 2-D simulations. An optimal configuration is obtained when the outer radius is increased until the clean fuel fraction is within 65 – 75% at peak velocity. A scan (in ablator and fuel thickness parameter space is used to optimize the capsule configurations. The optimized aerogel-filled capsule has good low-mode robustness and acceptable high-mode mix.

  11. Cobalt sulfide aerogel prepared by anion exchange method with enhanced pseudocapacitive and water oxidation performances

    Science.gov (United States)

    Gao, Qiuyue; Shi, Zhenyu; Xue, Kaiming; Ye, Ziran; Hong, Zhanglian; Yu, Xinyao; Zhi, Mingjia

    2018-05-01

    This work introduces the anion exchange method into the sol-gel process for the first time to prepare a metal sulfide aerogel. A porous Co9S8 aerogel with a high surface area (274.2 m2 g‑1) and large pore volume (0.87 cm3 g‑1) has been successfully prepared by exchanging cobalt citrate wet gel in thioacetamide and subsequently drying in supercritical ethanol. Such a Co9S8 aerogel shows enhanced supercapacitive performance and catalytic activity toward oxygen evolution reaction (OER) compared to its oxide aerogel counterpart. High specific capacitance (950 F g‑1 at 1 A g‑1), good rate capability (74.3% capacitance retention from 1 to 20 A g‑1) and low onset overpotential for OER (220 mV) were observed. The results demonstrated here have implications in preparing various sulfide chalcogels.

  12. Flexible transparent aerogels as window retrofitting films and optical elements with tunable birefringence

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Qingkun; Frazier, Allister W.; Zhao, Xinpeng; De La Cruz, Joshua A.; Hess, Andrew J.; Yang, Ronggui; Smalyukh, Ivan I.

    2018-06-01

    Experimental realization of optically transparent, mechanically robust and flexible aerogels has been a longstanding challenge, which limits their practical applications in energy-saving devices, such as thermally insulating films for enhancing energy efficiency of windows. The poor transparency precluded even hypothetical consideration of the possibility of birefringent aerogels. We develop birefringent and optically isotropic aerogels that combine properties of thermal super-insulation, mechanical robustness and flexibility, and transparency to visible-spectrum light. This unusual combination of physical properties is achieved by combining liquid crystalline self-organization of cellulose nanofibers with polysiloxane cross-linking and control of the nanoscale porosity to form hybrid organic-inorganic mesostructured aerogels. Potential applications of these inexpensive materials range from single pane window retrofitting to smart fabrics.

  13. SYNTHESIS AND CHARACTERIZATION OF CELLULOSE BASED BIO-POLYMER AEROGEL ISOLATED FROM WASTE OF BLUEBERRY TREE (VACCINIUM MYRTILLUS

    Directory of Open Access Journals (Sweden)

    Mehmet KAYA

    2016-09-01

    Full Text Available Cellulose aerogel (CA has highly porous structure, environmentally friendly, thermally stable and flame retardant properties. These properties in material worlds have attracted large interest as a potentially industrial material. In this paper, cellulose aerogel with flame retardant was produced from pruned branches and bushes of blueberries wastes (PBBW. Firstly, cellulose raw material these wastes was obtained and then, cellulose aerogel via freeze-drying, followed by cellulose hydrogel production. Our reports showed that three dimensionally network aerogel structure prepared from NaOH/Urea as scaffold solution. The present cellulose aerogel has excellent flame retardancy, which can extinguish within 140 s. By the way, it was inferred thermal stability performance of cellulose aerogel could be efficient potential thermal insulating material. Besides, this process are sustainable, easily available at low cost and suitable for industrial applications.

  14. Measurement of the eddy diffusion term in chromatographic columns. I. Application to the first generation of 4.6mm I.D. monolithic columns.

    Science.gov (United States)

    Gritti, Fabrice; Guiochon, Georges

    2011-08-05

    The corrected heights equivalent to a theoretical plate (HETP) of three 4.6mm I.D. monolithic Onyx-C(18) columns (Onyx, Phenomenex, Torrance, CA) of different lengths (2.5, 5, and 10 cm) are reported for retained (toluene, naphthalene) and non-retained (uracil, caffeine) small molecules. The moments of the peak profiles were measured according to the accurate numerical integration method. Correction for the extra-column contributions was systematically applied. The peak parking method was used in order to measure the bulk diffusion coefficients of the sample molecules, their longitudinal diffusion terms, and the eddy diffusion term of the three monolithic columns. The experimental results demonstrate that the maximum efficiency was 60,000 plates/m for retained compounds. The column length has a large impact on the plate height of non-retained species. These observations were unambiguously explained by a large trans-column eddy diffusion term in the van Deemter HETP equation. This large trans-rod eddy diffusion term is due to the combination of a large trans-rod velocity bias (≃3%), a small radial dispersion coefficient in silica monolithic columns, and a poorly designed distribution and collection of the sample streamlets at the inlet and outlet of the monolithic rod. Improving the performance of large I.D. monolithic columns will require (1) a detailed knowledge of the actual flow distribution across and along these monolithic rod and (2) the design of appropriate inlet and outlet distributors designed to minimize the nefarious impact of the radial flow heterogeneity on band broadening. Copyright © 2011 Elsevier B.V. All rights reserved.

  15. 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...

  16. Oxidation-mediated chitosan as additives for creation of chitosan aerogels with diverse three-dimensional interconnected skeletons

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Sizhao, E-mail: bule-soul@hotmail.com; Feng, Jian, E-mail: fengj@nudt.edu.cn; Feng, Junzong; Jiang, Yonggang

    2017-02-28

    Highlights: • A new synthetic method for controlling morphology of chitosan aerogels is proposed. • Chitosan aerogels with nanoflake-like and nanofiber-like were prepared. • Textures of chitosan aerogels are strongly dependent upon the oxidation pattern. - Abstract: Naturally occurring polymer-based aerogels have myriad practical utilizations due to environmentally benign and fruitful resources. However, engineering morphology-controllable biomass aerogels still represents a great challenge. Here we present a facile solution to synthesize chitosan aerogels having distinguished textures by reacting oxidized chitosan with formaldehyde and chitosan sol. In more detail, chitosan was chemically oxidized using two types of oxidation agents such as ammonium persulphate (SPD) and sodium periodate (APS) to obtain corresponding oxidized chitosan, subsequently cross-linked with chitosan solution containing formaldehyde to harvest SPD-oxidized chitosan aerogels (SCAs) and APS-SPD-oxidized ones (ASCAs) after aging, solvent exchange and supercritical drying processes. We found that the morphologies of as-prepared chitosan aerogels are strongly dependent upon the oxidation pattern towards chitosan. The structural textures of SCAs and ASCAs appear nanoflake-like and nanofiber-like structures, which may be related to spatial freedom of active groups located in chitosan. Selected area electron diffraction analysis reveals that the crystalline properties of chitosan aerogels generally appear the serious deterioration comparing to raw chitosan owing to their interconnected skeletal structure formation. The occurrence of characteristic groups displays cross-linked chain construction by using chemical state measurements such as FT-IR and XPS. Further, a plausible mechanism for controlling morphology of chitosan aerogels is also established. This new family of method for creation of chitosan aerogels may open up a perspective for biomass aerogels with controllable textures.

  17. Oxidation-mediated chitosan as additives for creation of chitosan aerogels with diverse three-dimensional interconnected skeletons

    International Nuclear Information System (INIS)

    Zhang, Sizhao; Feng, Jian; Feng, Junzong; Jiang, Yonggang

    2017-01-01

    Highlights: • A new synthetic method for controlling morphology of chitosan aerogels is proposed. • Chitosan aerogels with nanoflake-like and nanofiber-like were prepared. • Textures of chitosan aerogels are strongly dependent upon the oxidation pattern. - Abstract: Naturally occurring polymer-based aerogels have myriad practical utilizations due to environmentally benign and fruitful resources. However, engineering morphology-controllable biomass aerogels still represents a great challenge. Here we present a facile solution to synthesize chitosan aerogels having distinguished textures by reacting oxidized chitosan with formaldehyde and chitosan sol. In more detail, chitosan was chemically oxidized using two types of oxidation agents such as ammonium persulphate (SPD) and sodium periodate (APS) to obtain corresponding oxidized chitosan, subsequently cross-linked with chitosan solution containing formaldehyde to harvest SPD-oxidized chitosan aerogels (SCAs) and APS-SPD-oxidized ones (ASCAs) after aging, solvent exchange and supercritical drying processes. We found that the morphologies of as-prepared chitosan aerogels are strongly dependent upon the oxidation pattern towards chitosan. The structural textures of SCAs and ASCAs appear nanoflake-like and nanofiber-like structures, which may be related to spatial freedom of active groups located in chitosan. Selected area electron diffraction analysis reveals that the crystalline properties of chitosan aerogels generally appear the serious deterioration comparing to raw chitosan owing to their interconnected skeletal structure formation. The occurrence of characteristic groups displays cross-linked chain construction by using chemical state measurements such as FT-IR and XPS. Further, a plausible mechanism for controlling morphology of chitosan aerogels is also established. This new family of method for creation of chitosan aerogels may open up a perspective for biomass aerogels with controllable textures.

  18. Transparent, Superflexible Doubly Cross-Linked Polyvinylpolymethylsiloxane Aerogel Superinsulators via Ambient Pressure Drying.

    Science.gov (United States)

    Zu, Guoqing; Shimizu, Taiyo; Kanamori, Kazuyoshi; Zhu, Yang; Maeno, Ayaka; Kaji, Hironori; Shen, Jun; Nakanishi, Kazuki

    2018-01-23

    Aerogels have many attractive properties but are usually costly and mechanically brittle, which always limit their practical applications. While many efforts have been made to reinforce the aerogels, most of the reinforcement efforts sacrifice the transparency or superinsulating properties. Here we report superflexible polyvinylpolymethylsiloxane, (CH 2 CH(Si(CH 3 )O 2/2 )) n , aerogels that are facilely prepared from a single precursor vinylmethyldimethoxysilane or vinylmethyldiethoxysilane without organic cross-linkers. The method is based on consecutive processes involving radical polymerization and hydrolytic polycondensation, followed by ultralow-cost, highly scalable, ambient-pressure drying directly from alcohol as a drying medium without any modification or additional solvent exchange. The resulting aerogels and xerogels show a homogeneous, tunable, highly porous, doubly cross-linked nanostructure with the elastic polymethylsiloxane network cross-linked with flexible hydrocarbon chains. An outstanding combination of ultralow cost, high scalability, uniform pore size, high surface area, high transparency, high hydrophobicity, excellent machinability, superflexibility in compression, superflexibility in bending, and superinsulating properties has been achieved in a single aerogel or xerogel. This study represents a significant progress of porous materials and makes the practical applications of transparent flexible aerogel-based superinsulators realistic.

  19. Room-temperature embedment of anatase titania nanoparticles into porous cellulose aerogels

    Science.gov (United States)

    Jiao, Yue; Wan, Caichao; Li, Jian

    2015-07-01

    In this paper, a facile easy method for room-temperature embedment of anatase titania (TiO2) nanoparticles into porous cellulose aerogels was reported. The obtained anatase TiO2/cellulose (ATC) aerogels were characterized by scanning electron microscopy, energy-dispersive X-ray spectrometer, transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, nitrogen adsorption measurements, and thermogravimetric analysis. The results showed that high-purity anatase TiO2 nanoparticles with sizes of 3.69 ± 0.77 nm were evenly dispersed in the cellulose aerogels, which leaded to the significant improvement in specific surface area and pore volume of ATC aerogels. Meanwhile, the hybrid ATC aerogels also had a high loading content of TiO2 (ca. 17.7 %). Furthermore, through a simple photocatalytic degradation test of indigo carmine dye under UV light, ATC aerogels exhibited superior photocatalytic activity and shape stability, which might be useful in some fields like governance of water pollution, and chemical leaks.

  20. Preparation of lignin-based carbon aerogels as biomaterials for nano-supercapacitor

    Science.gov (United States)

    Yang, Bong Suk; Kang, Kyu-Young; Jeong, Myung-Joon

    2017-10-01

    Kraft and organosolv lignins, generally produced in chemical pulping and bio-refinery processes of lignocellulosic biomass, were used to prepare lignin-based carbon aerogels for supercapacitors as raw materials. The difference between lignins and lignin-based aerogels were compared by analyzing physical and chemical properties, including molecular weight, polydispersity, and reactivity with formaldehyde. Also, density, shrinkage, Brunauer-Emmett-Teller (BET) surface area and scanning electron microscope (SEM) images of the lignin-based aerogel were investigated. Kraft lignin consisting of coniferyl alcohol (G) and p-coumaryl alcohol (H) increased the reactivity of formaldehyde, formed a hydrogel well (porosity > 0.45), and specific surface area higher than organosolv lignin. In the case of kraft lignin, there were irregular changes such as oxidation and condensation in the pulping process. However, reaction sites with aromatic rings in lignin impacted the production of aerogel and required a long gelation period. The molecular weight of lignin influences the gelation time in producing lignin-based aerogel, and lignin composition affects the BET surface area and pore structures of the lignin-based carbon aerogels.

  1. Silica from Ash

    Indian Academy of Sciences (India)

    and may change the product characteristics (colour, etc.). This method of quality assessment is more suitable to workers at the processing site as it does not involve lab-scale analysis. Process. The initial step is extraction of silica from ash as sodium silicate using caustic soda. This reaction is carried out at a temperature.

  2. Aniline incorporated silica nanobubbles

    Indian Academy of Sciences (India)

    Unknown

    2006-09-14

    Sep 14, 2006 ... persed in diverse media. 2. Experimental. 2.1 Materials. Chloroauric acid, trisodium citrate, ... molecules such as ciprofloxacin, we could see the same kind of carbon onion structures inside the silica .... molecule. The supernatant, after precipitation of ani- line@SiO2 by centrifugation, did not show aniline.

  3. The removal of uranium(VI) from aqueous solution by graphene oxide-carbon nanotubes hybrid aerogels

    International Nuclear Information System (INIS)

    Zexing Gu; Jun Tang; Jijun Yang; Jiali Liao; Yuanyou Yang; Ning Liu; Yun Wang; East China Institute of Technology, Nanchang, Jiangxi

    2015-01-01

    Novel graphene oxide-carbon nanotubes (GO-CNTs) hybrid aerogels were fabricated via a freeze-drying method using aqueous solutions of GO and CNTs. The resulting aerogels were characterized by scanning electron microscopy, X-ray diffraction, Fourier transformed infrared spectroscopy and thermal gravity analysis. The three-dimensional GO-CNTs aerogels were used to remove uranium(VI) from aqueous solutions. The results showed that GO-CNTs aerogels had high removal ability to uranium(VI) and could be a promising sorbent for many environment applications. (author)

  4. Super high-rate fabrication of high-purity carbon nanotube aerogels from floating catalyst method for oil spill cleaning

    Science.gov (United States)

    Khoshnevis, Hamed; Mint, Sandar Myo; Yedinak, Emily; Tran, Thang Q.; Zadhoush, Ali; Youssefi, Mostafa; Pasquali, Matteo; Duong, Hai M.

    2018-02-01

    In this study, we apply an advanced floating catalyst method to fabricate carbon nanotube (CNT) aerogels at super high deposition rate for oil spill cleaning. The aerogels consist of 3D porous network of stacking double-walled CNT bundles with low catalyst impurity (9%) and high thermal stability (650 °C). With high porosity, surface areas, and water contact angles, the CNT aerogels exhibit a high oil adsorption of up to 107 g/g and good reusability of up to four adsorption-burning cycles. This work suggests that the lightweight, porous, and super hydrophobic CNT aerogels can be promising sorbent materials for environmental applications.

  5. Fine-grain concrete from mining waste for monolithic construction

    Science.gov (United States)

    Lesovik, R. V.; Ageeva, M. S.; Lesovik, G. A.; Sopin, D. M.; Kazlitina, O. V.; Mitrokhin, A. A.

    2018-03-01

    The technology of a monolithic construction is a well-established practice among most Russian real estate developers. The strong points of the technology are low cost of materials and lower demand for qualified workers. The monolithic construction uses various types of reinforced slabs and foamed concrete, since they are easy to use and highly durable; they also need practically no additional treatment.

  6. Time-based position estimation in monolithic scintillator detectors

    NARCIS (Netherlands)

    Tabacchini, V.; Borghi, G.; Schaart, D.R.

    2015-01-01

    Gamma-ray detectors based on bright monolithic scintillation crystals coupled to pixelated photodetectors are currently being considered for several applications in the medical imaging field. In a typical monolithic detector, both the light intensity and the time of arrival of the earliest

  7. A novel photocatalytic monolith reactor for multiphase heterogeneous photocatalysis

    NARCIS (Netherlands)

    Du, P.; Carneiro, J.T.; Moulijn, J.A.; Mul, Guido

    2008-01-01

    A novel reactor for multi-phase photocatalysis is presented, the so-called internally illuminated monolith reactor (IIMR). In the concept of the IIMR, side light emitting fibers are placed inside the channels of a ceramic monolith, equipped with a TiO2 photocatalyst coated on the wall of each

  8. Hydrogel coated monoliths for enzymatic hydrolysis of penicillin G

    NARCIS (Netherlands)

    De Lathouder, K.M.; Smeltink, M.W.; Straathof, A.J.J.; Paasman, M.A.; Van de Sandt, E.J.A.X.; Kapteijn, F.; Moulijn, J.A.

    2008-01-01

    The objective of this work was to develop a hydrogel-coated monolith for the entrapment of penicillin G acylase (E. coli, PGA). After screening of different hydrogels, chitosan was chosen as the carrier material for the preparation of monolithic biocatalysts. This protocol leads to active

  9. Energy Absorption of Monolithic and Fibre Reinforced Aluminium Cylinders

    NARCIS (Netherlands)

    De Kanter, J.L.C.G.

    2006-01-01

    Summary accompanying the thesis: Energy Absorption of Monolithic and Fibre Reinforced Aluminium Cylinders by Jens de Kanter This thesis presents the investigation of the crush behaviour of both monolithic aluminium cylinders and externally fibre reinforced aluminium cylinders. The research is based

  10. Monolithic LTCC seal frame and lid

    Energy Technology Data Exchange (ETDEWEB)

    Krueger, Daniel S.; Peterson, Kenneth A.; Stockdale, Dave; Duncan, James Brent; Riggs, Bristen

    2016-06-21

    A method for forming a monolithic seal frame and lid for use with a substrate and electronic circuitry comprises the steps of forming a mandrel from a ceramic and glass based material, forming a seal frame and lid block from a ceramic and glass based material, creating a seal frame and lid by forming a compartment and a plurality of sidewalls in the seal frame and lid block, placing the seal frame and lid on the mandrel such that the mandrel fits within the compartment, and cofiring the seal frame and lid block.

  11. Safety characteristics of the monolithic CFC divertor

    International Nuclear Information System (INIS)

    Zucchetti, M.; Merola, M.; Matera, R.

    1994-01-01

    The main distinguishing feature of the monolithic CFC divertor is the use of a single material, a carbon fibre reinforced carbon, for the protective armour, the heat sink and the cooling channels. This removes joint interface problems which are one of the most important concerns related to the reference solutions of the ITER CDA divertor. An activation analysis of the different coolant options for this concept is presented. It turns out that neither short-term nor long-term activation are a concern for any coolants investigated. Therefore the proposed concept proves to be attractive from a safety stand-point also. ((orig.))

  12. Safety characteristics of the monolithic CFC divertor

    Science.gov (United States)

    Zucchetti, M.; Merola, M.; Matera, R.

    1994-09-01

    The main distinguishing feature of the monolithic CFC divertor is the use of a single material, a carbon fibre reinforced carbon, for the protective armour, the heat sink and the cooling channels. This removes joint interface problems which are one of the most important concerns related to the reference solutions of the ITER CDA divertor. An activation analysis of the different coolant options for this concept is presented. It turns out that neither short-term nor long-term activation are a concern for any coolants investigated. Therefore the proposed concept proves to be attractive from a safety stand-point also.

  13. 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

  14. Preparation of a long-alkyl-chain-based hybrid monolithic column with mixed-mode interactions using a "one-pot" process for pressurized capillary electrochromatography.

    Science.gov (United States)

    Lyu, Haixia; Zhao, Heqing; Qin, Wenfei; Xie, Zenghong

    2017-12-01

    A simple "one-pot" approach for the preparation of a new vinyl-functionalized organic-inorganic hybrid monolithic column is described. In this improved method, the hydrolyzed alkoxysilanes of tetramethoxysilane and triethoxyvinylsilane were used as precursors for the synthesis of a silica-based monolith, while 1-hexadecene and sodium ethylenesulfonate were used as vinyl functional monomers along with azobisisobutyronitrile as an initiator. The effects of reaction temperature, urea content, and composition of organic monomers on the column properties (e.g. morphology, mechanical stability, and chromatographic performance) were investigated. The monolithic column was used for the separation of neutral solutes by reversed-phase pressurized capillary. Furthermore, the monolith can separate various aromatic amines, which indicated its excellent cation-exchange capability and hydrophobic interactions. The baseline separation of the aromatic amines was obtained with a column efficiency of up to 78 000 plates/m. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Less common applications of monoliths: V. Monolithic scaffolds modified with nanostructures for chromatographic separations and tissue engineering.

    Science.gov (United States)

    Krenkova, Jana; Foret, Frantisek; Svec, Frantisek

    2012-06-01

    Scaffolds modified with nanostructures are recently finding use in a broad range of applications spanning from chromatographic separations to tissue engineering. This continuation of the review series on design and applications of monolithic materials covers some of the less common monoliths including use of nanostructures in preparation, modifications, and applications. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Growth techniques for monolithic YBCO solenoidal magnets

    International Nuclear Information System (INIS)

    Scruggs, S.J.; Putman, P.T.; Fang, H.; Alessandrini, M.; Salama, K.

    2006-01-01

    The possibility of growing large single domain YBCO solenoids by the use of a large seed has been investigated. There are two known methods for producing a similar solenoid. This first is a conventional top seeded melt growth process followed by a post processing machining step to create the bore. The second involves using multiple seeds spaced around the magnet bore. The appeal of the new technique lies in decreasing processing time compared to the single seed technique, while avoiding alignment problems found in the multiple seeding technique. By avoiding these problems, larger diameter monoliths can be produced. Large diameter monoliths are beneficial because the maximum magnetic field produced by a trapped field magnet is proportional to the radius of the sample. Furthermore, the availability of trapped field magnets with large diameter could enable their use in applications that traditionally have been considered to require wound electromagnets, such as beam bending magnets for particle accelerators or electric propulsion. A comparison of YBCO solenoids grown by the use of a large seed and grown by the use of two small seeds simulating multiple seeding is made. Trapped field measurements as well as microstructure evaluation were used in characterization of each solenoid. Results indicate that high quality growth occurs only in the vicinity of the seeds for the multiple seeded sample, while the sample with the large seeded exhibited high quality growth throughout the entire sample

  17. Catastrophic failure of a monolithic zirconia prosthesis.

    Science.gov (United States)

    Chang, Jae-Seung; Ji, Woon; Choi, Chang-Hoon; Kim, Sunjai

    2015-02-01

    Recently, monolithic zirconia restorations have received attention as an alternative to zirconia veneered with feldspathic porcelain to eliminate chipping failures of veneer ceramics. In this clinical report, a patient with mandibular edentulism received 4 dental implants in the interforaminal area, and a screw-retained monolithic zirconia prosthesis was fabricated. The patient also received a maxillary complete removable dental prosthesis over 4 anterior roots. At the 18-month follow-up, all of the zirconia cylinders were seen to be fractured, and the contacting abutment surfaces had lost structural integrity. The damaged abutments were replaced with new abutments, and a new prosthesis was delivered with a computer-assisted design and computer-assisted manufacturing fabricated titanium framework with denture teeth and denture base resins. At the 6-month recall, the patient did not have any problems. Dental zirconia has excellent physical properties; however, care should be taken to prevent excessive stresses on the zirconia cylinders when a screw-retained zirconia restoration is planned as a definitive prosthesis. Copyright © 2015 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  18. Multi-scale cellulose based new bio-aerogel composites with thermal super-insulating and tunable mechanical properties.

    Science.gov (United States)

    Seantier, Bastien; Bendahou, Dounia; Bendahou, Abdelkader; Grohens, Yves; Kaddami, Hamid

    2016-03-15

    Bio-composite aerogels based on bleached cellulose fibers (BCF) and cellulose nanoparticles having various morphological and physico-chemical characteristics are prepared by a freeze-drying technique and characterized. The various composite aerogels obtained were compared to a BCF aerogel used as the reference. Severe changes in the material morphology were observed by SEM and AFM due to a variation of the cellulose nanoparticle properties such as the aspect ratio, the crystalline index and the surface charge density. BCF fibers form a 3D network and they are surrounded by the cellulose nanoparticle thin films inducing a significant reduction of the size of the pores in comparison with a neat BCF based aerogel. BET analyses confirm the appearance of a new organization structure with pores of nanometric sizes. As a consequence, a decrease of the thermal conductivities is observed from 28mWm(-1)K(-1) (BCF aerogel) to 23mWm(-1)K(-1) (bio-composite aerogel), which is below the air conductivity (25mWm(-1)K(-1)). This improvement of the insulation properties for composite materials is more pronounced for aerogels based on cellulose nanoparticles having a low crystalline index and high surface charge (NFC-2h). The significant improvement of their insulation properties allows the bio-composite aerogels to enter the super-insulating materials family. The characteristics of cellulose nanoparticles also influence the mechanical properties of the bio-composite aerogels. A significant improvement of the mechanical properties under compression is obtained by self-organization, yielding a multi-scale architecture of the cellulose nanoparticles in the bio-composite aerogels. In this case, the mechanical property is more dependent on the morphology of the composite aerogel rather than the intrinsic characteristics of the cellulose nanoparticles. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Morphological and textural characterization of functionalized particulate silica xerogels

    Science.gov (United States)

    de Miranda, Lazaro A.; Mohallem, Nelcy D. S.; de Magalhães, Welington F.

    2006-03-01

    The functionalization of xerogels for use in chromatography and catalysis was carried out by solubilization of amorphous silica using a soxhlet extractor. Xerogels were prepared by sol-gel method using tetraethoxysilane, TEOS, ethanol, and water in a 1/3/10 molar ratio with HCl and HF as catalysts. The samples were prepared in monolithic form and dried at 70 °C and 550 °C for 1 h each. After functionalization, changes in textural and morphological characteristics of xerogels were investigated by means of nitrogen gas adsorption, positron annihilation lifetime spectroscopy (PALS), and scanning electron microscopy (SEM). As the analysis methods are based on different physical principles, the results are complementary, leading to a good knowledge of the texture of the samples studied.

  20. Monolithic integration of microfluidic channels and optical waveguides in silica on silicon

    DEFF Research Database (Denmark)

    Friis, Peter; Hoppe, Karsten; Leistiko, Otto

    2001-01-01

    -back technique are possible, but troublesome. We present a simple but efficient alternative: By means of changing the waveguide layout, bonding pads are formed along the microfluidic channels. With the same height as the waveguide, they effectively prevent leakage and hermetically seal the channels during...