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Sample records for meso porous silica

  1. Control the Morphologies and the Pore Architectures of Meso porous Silicas through a Dual-Templating Approach

    International Nuclear Information System (INIS)

    Wang, H.; Chen, H.; Xu, Z.; Wang, S.; Li, B.; Li, Y.

    2012-01-01

    Meso porous silica nanospheres were prepared using a chiral cationic low-molecular-weight amphiphile and organic solvents such as toluene, cyclohexane, and tetrachlorocarbon through a dual-templating approach. X-ray diffraction, nitrogen sorption, field emission scanning electron microscopy, and transmission electron microscopy techniques have been used to characterize the meso porous silicas. The volume ratio of toluene to water plays an important role in controlling the morphologies and the pore architectures of the meso porous silicas. It was also found that meso porous silica nano flakes can be prepared by adding tetrahydrofuran to the reaction mixtures.

  2. Influence of the ammonium hydroxide concentration in morphological control of meso porous silica particles

    International Nuclear Information System (INIS)

    Yoon, Sukbon; Jung, Chonghun; Yoon, Inho; Kim, Changki; Choi, Wangkyu; Moon, Jeikwon

    2012-01-01

    The discovery of new M41S meso porous silica families in 1992 extended the applications into much wider pore ranges, bringing in a new prosperous era in porous material research. The synthesis of these meso porous silicas has been mainly accomplished through a self-assembly between surfactant molecules and inorganic species under various pH conditions. Meanwhile, many studies have been conducted on the application as catalysts, adsorbents, and packing materials for separation columns due to their unique properties such as high specific surface area, large pore volume, tuneable pore size, and narrow pore size distribution. The pore sizes of these materials can be easily controlled by changing the alkyl-chain length of the surfactant used. However, the control of the morphology and the pore structure is not so common. The morphological control of these materials in particular is one of the major challenges for their industrial application. Recently, the meso porous silica materials with various shapes such as fibers, films, polyhedral particles, and spheres have been reported. In our previous study, the core-shell nanoparticles with a silica core and a meso porous shell under basic conditions were synthesized using the silica nanoparticles as a core and tetraethyl orthosilicate (TEOS)-cetyltrimethylammonium bromide (CTABr)-NH 4 OH-H 2 O-C 2 H 5 OH system. In this work, we report the synthesis of the most well known hexagonal MCM-41 among three main mesophases in the M41S families using TEOS-CTABr-NH 4 OH-H 2 O system. Also, in the control of the morphology and pore structure of the meso porous silica materials, the influence of the NH 4 OH concentration was investigated

  3. Hydrothermal synthesis of meso porous silica MCM-41 using commercial sodium silicate

    Energy Technology Data Exchange (ETDEWEB)

    Melendez O, H. I.; Mercado S, A.; Garcia C, L. A.; Castruita, G.; Perera M, Y A., E-mail: ivan_melendez380@hotmail.com [Centro de Investigacion en Quimica Aplicada, Bldv. Enrique Reyna Hermosillo No. 140, Saltillo 25294, Coahuila (Mexico)

    2013-08-01

    In this work, ordered meso porous silica MCM-41 was prepared by hydrothermal synthesis using industrial-grade sodium silicate (Na{sub 2}SiO{sub 3}) as silica source, hexadecyltrimethyl-ammonium bromide (CTAB) as template agent and ethyl acetate as ph regulator. The influence of CTAB/SiO{sub 2} molar ratio, reaction time, aging temperature, and co-surfactant type on the structural and morphological properties of the obtained silica was studied. The products were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and nitrogen adsorption-desorption isotherms. Ordered meso porous MCM-41 silica was obtained at 80 C by using a range of CTAB/SiO{sub 2} molar ratio from 0.35 to 0.71 and reaction times up to 72 h and isopropanol (i-Pr OH) as co-surfactant. (Author)

  4. Hydrothermal synthesis of meso porous silica MCM-41 using commercial sodium silicate

    International Nuclear Information System (INIS)

    Melendez O, H. I.; Mercado S, A.; Garcia C, L. A.; Castruita, G.; Perera M, Y A.

    2013-01-01

    In this work, ordered meso porous silica MCM-41 was prepared by hydrothermal synthesis using industrial-grade sodium silicate (Na 2 SiO 3 ) as silica source, hexadecyltrimethyl-ammonium bromide (CTAB) as template agent and ethyl acetate as ph regulator. The influence of CTAB/SiO 2 molar ratio, reaction time, aging temperature, and co-surfactant type on the structural and morphological properties of the obtained silica was studied. The products were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and nitrogen adsorption-desorption isotherms. Ordered meso porous MCM-41 silica was obtained at 80 C by using a range of CTAB/SiO 2 molar ratio from 0.35 to 0.71 and reaction times up to 72 h and isopropanol (i-Pr OH) as co-surfactant. (Author)

  5. Effects of confinement in meso-porous silica and carbon nano-structures

    International Nuclear Information System (INIS)

    Leon, V.

    2006-07-01

    Physico-chemical properties of materials can be strongly modified by confinement because of the quantum effects that appear at such small length scales and also because of the effects of the confinement itself. The aim of this thesis is to show that both the nature of the confining material and the size of the pores and cavities have a strong impact on the confined material. We first show the effect of the pore size of the host meso-porous silica on the temperature of the solid-solid phase transition of silver selenide, a semiconducting material with enhanced magnetoresistive properties under non-stoichiometric conditions. Narrowing the pores from 20 nm to 2 nm raises the phase transition temperature from 139 C to 146 C. This result can be explained by considering the interaction between the confining and confined materials as a driving force. The effects of confinement are also studied in the case of hydrogen and deuterium inside cavities of organized carbon nano-structures. The effects that appear in the adsorption/desorption cycles are much stronger with carbon nano-horns as the host material than with C60 pea-pods and single-walled carbon nano-tubes. (author)

  6. Design and evaluation of hybrid meso-porous silicas to uranium extraction from sulfuric media

    International Nuclear Information System (INIS)

    Charlot, Alexandre

    2016-01-01

    Nuclear industries are perpetually looking for technical, economic and environmental progresses. Important volumes of acidic waste are generated by nuclear plants of the front end. The extraction of uranium from these solutions is required to decontaminate effluents (decrease of the radioactivity) and value uranium (re-incorporation in the cycle). Uranium leaching is mostly achieved using sulfuric acid leading to the production of aqueous effluents that contain a large grade of sulfate complexes. In such conditions, uranyl sulfate complexes constitute the predominant uranium species in solution and its extraction represents a real scientific and technological challenge. Commonly, precipitation, solvent extraction or solid phase extraction are used. The last one is particularly adapted for low grade solutions due to it weak environmental footprint (no solvent are handling) and the facility of the process involved (i.e. fixed bed column). among the available solid-phase extraction candidates, hybrid meso-porous silicas get a crucial part. They develop a very high specific surface areas and a driven porosity which give them a high potential of extraction capacities. In this manuscript the tailoring and the evaluation of hybrid meso-porous silicas have been investigated. Firstly, the work focus on the organic part grafted by post-synthetic pathway, the N,N-dialkyl-carbamoyl-phosphonate based molecules have been identified to get interesting extraction properties. This study emphasizes that acid groups are required and that alkyl substituents get a real importance in the extraction efficiency. On the second hand, the role of pore size has been investigated. The results obtained disclosed that pores size diameters directly impact the grafting ratio as well as the homogeneity of the material: (1) materials with a pore size below 3 nm are heterogeneously functionalized due to steric issues, (2) a homogeneous organic monolayer grafted onto the silica skeleton occurs when

  7. Effects of confinement in meso-porous silica and carbon nano-structures; Etude des effets de confinement dans la silice mesoporeuse et dans certaines nanostructures carbonees

    Energy Technology Data Exchange (ETDEWEB)

    Leon, V

    2006-07-15

    Physico-chemical properties of materials can be strongly modified by confinement because of the quantum effects that appear at such small length scales and also because of the effects of the confinement itself. The aim of this thesis is to show that both the nature of the confining material and the size of the pores and cavities have a strong impact on the confined material. We first show the effect of the pore size of the host meso-porous silica on the temperature of the solid-solid phase transition of silver selenide, a semiconducting material with enhanced magnetoresistive properties under non-stoichiometric conditions. Narrowing the pores from 20 nm to 2 nm raises the phase transition temperature from 139 C to 146 C. This result can be explained by considering the interaction between the confining and confined materials as a driving force. The effects of confinement are also studied in the case of hydrogen and deuterium inside cavities of organized carbon nano-structures. The effects that appear in the adsorption/desorption cycles are much stronger with carbon nano-horns as the host material than with C60 pea-pods and single-walled carbon nano-tubes. (author)

  8. A bio-inspired zinc finger analogue anchored in 2D hexagonal meso-porous silica for room temperature CO_2 activation via a hydrogeno-carbonate route

    International Nuclear Information System (INIS)

    Doghri, Hanene; Baranova, Elena A.; Albela, Belen; Bonneviot, Laurent; Mongia Said-Zina

    2017-01-01

    Bio-inspired diethylenetriamine-zinc(II) complexes were anchored into the nano-pores of hexagonal meso-porous MCM41-like silicas targeting a carbamate free and low temperature CO_2 recycling process. A step-by-step approach was adopted to perform an in situ synthesis in order to mimic the zinc finger of carbonic anhydrases, the fastest family of enzymes. In the presence of a surface-masking pattern of TMA"+ ions, some silanol groups were capped using grafted trimethylsilyl functions, TMSgr, (gr for grafted). After removing the masking ions, a tridentate diethylenetriamine ligand was anchored using diethylenetriamine propyl-trimethoxysilane. The so-called DETA_a_n ligands (an for anchored) were partially mono-protonated using either cyclohexane or isopropanol as a solvent. Nonetheless, up to two thirds of them were metallated by Zn(II) ions, leading to the targeted anchored zinc finger mimic [Zn(DETAan)L]+(L = Cl or OH). CO_2 is then adsorbed at room temperature and in humid ambient air by the formation of an intermediate hydrogeno-carbonate-zinc complex. Specific IR signatures at 1330 and 1400 cm"-"1 together with characteristic C 1s and Zn 2p3/2 XPS binding energies at 286.4 and 1024.6 eV advocate for a rather symmetrical bidentate [η"2-CO_3] structural unit in the anchored complex [Zn(DETA_a_n)(η"2-HCO_3"*)]"+, where the Zn(II) ion is most likely penta-coordinated. The internal pH value varied by less than 0.5 depending on the metal reacting with the DETA_a_n ligand and its ability to generate HCO_3"-, due to the buffering effect of surface silanol and amino groups according to the level of protonation of the DETA moieties measured from the N 1s XPS spectra. In contrast to nitrate ions, chloride ions were found to inhibit the formation of hydrogeno-carbonate. (authors)

  9. Controlled release of ibuprofen by meso-macroporous silica

    Science.gov (United States)

    Santamaría, E.; Maestro, A.; Porras, M.; Gutiérrez, J. M.; González, C.

    2014-02-01

    Structured meso-macroporous silica was successfully synthesized from an O/W emulsion using decane as a dispersed phase. Sodium silicate solution, which acts as a silica source and a poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (EO19PO39EO19) denoted as P84 was used in order to stabilize the emulsion and as a mesopore template. The materials obtained were characterized through transmission electron microscopy (TEM), scanning electron microscopy (SEM), small-angle X-ray diffraction scattering (SAXS) and nitrogen adsorption-desorption isotherms. Ibuprofen (IBU) was selected as the model drug and loaded into ordered meso-macroporous materials. The effect of the materials’ properties on IBU drug loading and release was studied. The results showed that the loading of IBU increases as the macropore presence in the material is increased. The IBU adsorption process followed the Langmuir adsorption isotherm. A two-step release process, consisting of an initial fast release and then a slower release was observed. Macropores enhanced the adsorption capacity of the material; this was probably due to the fact that they allowed the drug to access internal pores. When only mesopores were present, ibuprofen was probably adsorbed on the mesopores close to the surface. Moreover, the more macropore present in the material, the slower the release behaviour observed, as the ibuprofen adsorbed in the internal pores had to diffuse along the macropore channels up to the surface of the material. The material obtained from a highly concentrated emulsion was functionalized with amino groups using two methods, the post-grafting mechanism and the co-condensation mechanism. Both routes improve IBU adsorption in the material and show good behaviour as a controlled drug delivery system.

  10. Vapor phase versus liquid phase grafting of meso-porous alumina

    NARCIS (Netherlands)

    Sripathi, V.G.P.; Mojet, Barbara; Nijmeijer, Arian; Benes, Nieck Edwin

    2013-01-01

    Functionalization of meso-porous c-alumina has been performed by grafting of 3-Aminopropyltrimethoxysilane (3APTMS) simultaneously from either the liquid phase or from the vapor phase. In both cases, after grafting nitrogen physisorption indicates that the materials remain meso-porous with

  11. New strategy for surface functionalization of periodic mesoporous silica based on meso-HSiO1.5.

    Science.gov (United States)

    Xie, Zhuoying; Bai, Ling; Huang, Suwen; Zhu, Cun; Zhao, Yuanjin; Gu, Zhong-Ze

    2014-01-29

    Organic functionalization of periodic mesoporous silicas (PMSs) offers a way to improve their excellent properties and wide applications owing to their structural superiority. In this study, a new strategy for organic functionalization of PMSs is demonstrated by hydrosilylation of the recently discovered "impossible" periodic mesoporous hydridosilica, meso-HSiO1.5. This method overcomes the disadvantages of present pathways for organic functionalization of PMSs with organosilica. Moreover, compared to the traditional functionalization on the surface of porous silicon by hydrosilylation, the template-synthesized meso-HSiO1.5 is more flexible to access functional-groups-loaded PMSs with adjustable microstructures. The new method and materials will have wider applications based on both the structure and surface superiorities.

  12. Biodiesel production from transesterification of palm oil with methanol over CaO supported on bimodal meso-macroporous silica catalyst.

    Science.gov (United States)

    Witoon, Thongthai; Bumrungsalee, Sittisut; Vathavanichkul, Peerawut; Palitsakun, Supaphorn; Saisriyoot, Maythee; Faungnawakij, Kajornsak

    2014-03-01

    Calcium oxide-loaded porous materials have shown promise as catalysts in transesterification. However, the slow diffusion of bulky triglycerides through the pores limited the activity of calcium oxide (CaO). In this work, bimodal meso-macroporous silica was used as a support to enhance the accessibility of the CaO dispersed inside the pores. Unimodal porous silica having the identical mesopore diameter was employed for the purpose of comparison. Effects of CaO content and catalyst pellet size on the yield of fatty acid methyl esters (FAME) were investigated. The basic strength was found to increase with increasing the CaO content. The CaO-loaded bimodal porous silica catalyst with the pellet size of 325μm achieved a high %FAME of 94.15 in the first cycle, and retained an excellent %FAME of 88.87 after five consecutive cycles. Copyright © 2014 Elsevier Ltd. All rights reserved.

  13. Probing properties, stability, and performances of hierarchical meso-porous materials with nano-scale interfaces

    International Nuclear Information System (INIS)

    Baldinozzi, Gianguido; Gosset, Dominique; Simeone, David; Muller, Guillaume; Laberty-Robert, Christel; Sanchez, Clement

    2012-01-01

    Nano-crystals growth mechanism embedded into meso-porous thin films has been determined directly from grazing incidence X-ray diffraction data. We have shown, for the first time, that surface capillary forces control the growth mechanism of nano-crystals into these nano-architectures. Moreover, these data allow an estimation of the surface tension of the nano-crystals organized into a 3-D nano-architecture. The analysis of the variations in the strain field of these nano-crystals gives information on the evolution of the microstructure of these meso-porous films, that is, the contacts among nano-crystals. This work represents the first application of grazing incidence X-ray for understanding stability and performances of meso-porous thin films. This approach can be used to understand the structural stability of these nano-architectures at high temperature. (authors)

  14. Cooperation of micro- and meso-porous carbon electrode materials in electric double-layer capacitors

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Cheng [State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun 130022, Jilin Province (China); Graduate University of Chinese Academy of Sciences, Beijing 100039 (China); Qi, Li; Wang, Hongyu [State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun 130022, Jilin Province (China); Yoshio, Masaki [Advanced Research Center, Saga University, 1341 Yoga-machi, Saga 840-0047 (Japan)

    2010-07-01

    The capacitive characteristics of micro- and meso-porous carbon materials have been compared in cyclic voltammetric studies and galvanostatic charge-discharge tests. Meso-porous carbon can keep certain high capacitance values at high scan rates, whereas micro-porous carbon possesses very high capacitance values at low scan rates but fades quickly as the scan rate rises up. For better performance of electric double-layer capacitors (EDLCs), the cooperative application of both kinds of carbon materials has been proposed in the following two ways: mixing both kinds of carbons in the same electrode or using the asymmetric configuration of carbon electrodes in the same EDLC. The cooperative effect on the electrochemical performance has also been addressed. (author)

  15. Polyethyleneimine-loaded bimodal porous silica as low-cost and high-capacity sorbent for CO{sub 2} capture

    Energy Technology Data Exchange (ETDEWEB)

    Witoon, Thongthai, E-mail: fengttwi@ku.ac.th [National Center of Excellence for Petroleum, Petrochemicals and Advance Material, Department of Chemical Engineering, Faculty of Engineering, Kasetsart University, Bangkok 10900 (Thailand); Center for Advanced Studies in Nanotechnology and Its Applications in Chemical Food and Agricultural Industries, Kasetsart University, Bangkok 10900 (Thailand)

    2012-11-15

    In this work, bimodal (meso-macro) porous silicas with different mesopore diameters synthesized by using rice husk ash as a low-cost silica source and chitosan as a natural template were used as a polyethyleneimine (PEI) support for CO{sub 2} capture. Unimodal porous silica supports with equivalent mesopore diameters to bimodal porous silica supports have been prepared for purpose of comparison. Effects of different PEI contents (10, 20, 30, 40 and 50 wt%) on CO{sub 2} sorption capacity have been systematically investigated. The porous silica supports and the PEI-loaded porous silica supports were characterized by N{sub 2}-sorption analysis, scanning electron microscopy, Fourier transform infrared spectroscopy and thermal gravimetric analysis. CO{sub 2} sorption measurements of all PEI-loaded porous silica supports were performed at different adsorption temperatures (60, 75, 85, 90, 95 and 105 Degree-Sign C). At low PEI contents (10-20 wt%), the CO{sub 2} sorption of all adsorbents was found to decrease as a function of adsorption temperature, which was a characteristic of a thermodynamically-controlled regime. A transition from the thermodynamically-controlled regime to a kinetically-controlled regime was found when the PEI content was increased up to 30 wt% for PEI-loaded unimodal porous silicas and 40 wt% for PEI-loaded bimodal porous silicas. At high PEI contents (40-50 wt%), the CO{sub 2} capturing efficiency of the PEI-loaded bimodal porous silicas was found to be considerably greater than that of the PEI-loaded unimodal porous silicas, indicating that most of the amine groups of PEI molecules loaded on the unimodal porous silica supports was useless, and thus the appeared macroporosity of the bimodal porous silica supports could provide a higher effective amine density to adsorb CO{sub 2}. Highlights: Black-Right-Pointing-Pointer PEI-impregnated bimodal porous silica as low-cost sorbent for CO{sub 2} capture. Black-Right-Pointing-Pointer Macropores enhances

  16. Synthesis and Characterization of Meso porous Material Functionalized with Different Silylating Agent and Their Capability to Remove Cu2+

    International Nuclear Information System (INIS)

    Zaini Hamzah; Norhidayu Narawi; Hamizah Mohd Rasid; Amira Nazirah Mohd Yusoff

    2012-01-01

    Meso porous material MCM-41 with uniform hexagonally ordered pores in range of 2-10 nm was synthesized through hydrothermal method. The synthesis started from highly pure silica source known as Ludox which act as an active source of silica in the presence of organic surfactant (CTABr) as structure-directing agent. MCM-41 has been functionalized with the organic group known as 3-aminopropyltriethoxysilane (APTES), 3-mercaptopropyltrimethoxysilane (MPTMS), and chloropropyl triethoxysilane (CPTES) by co-condensation method in order to enhance the surface hydrophobicity of MCM-41. The increasing hydrophobicity will lead to efficient reaction specifically for organic reaction in organic solvent. The resulting materials were characterized with various techniques which are PXRD, FTIR, NMR, Elemental Analysis and AAS. The formation of uniform hexagonal framework of synthesized materials was shown in PXRD result. The functionalized groups of modified MCM-41 can be characterized via FTIR and 13 C-NMR results. The Elemental Analysis shows the percentage of nitrogen, carbon, hydrogen and sulphur in MCM-41 and functionalized MCM-41. From AAS, MCM-41 MPTMS has high capability for removal of Cu (II) in aqueous solution compared with others. (author)

  17. Potential of hybrid functionalized meso-porous materials for the separation and immobilization of radionuclides

    International Nuclear Information System (INIS)

    Luca, V.

    2013-01-01

    Functionalized meso-porous materials are a class of hybrid organic-inorganic material in which a meso-porous metal oxide framework is functionalized with multifunctional organic molecules. These molecules may contain one or more anchor groups that form strong bonds to the pore surfaces of the metal oxide framework and free functional groups that can impart and or modify the functionality of the material such as for binding metal ions in solution. Such materials have been extensively studied over the past decade and are of particular interest in absorption applications because of the tremendous versatility in choosing the composition and architecture of the metal oxide framework and the nature of the functional organic molecule as well as the efficient mass transfer that can occur through a well-designed hierarchically porous network. A sorbent for nuclear applications would have to be highly selective for particular radio nuclides, it would need to be hydrolytically and radiolytically stable, and it would have to possess reasonable capacity and fast kinetics. The sorbent would also have to be available in a form suitable for use in a column. Finally, it would also be desirable if once saturated with radio nuclides, the sorbent could be recycled or converted directly into a ceramic or glass waste form suitable for direct repository disposal or even converted directly into a material that could be used as a transmutation target. Such a cradle-to- grave strategy could have many benefits in so far as process efficiency and the generation of secondary wastes are concerned.This paper will provide an overview of work done on all of the above mentioned aspects of the development of functionalized meso-porous adsorbent materials for the selective separation of lanthanides and actinides and discuss the prospects for future implementation of a cradle-to-grave strategy with such materials. (author)

  18. The micro and meso-porous materials. Characterization; Les materiaux micro et mesoporeux. Caracterisation

    Energy Technology Data Exchange (ETDEWEB)

    Thibault-Starzyk, F.

    2004-10-01

    The micro and meso-porous materials, called zeolites, are very important in the modern chemical industry and in petrochemistry. This book deals in particular with the study and the characterization of zeolites. Its aim is to give to generalist chemists the tools for approaching experimentally these particular materials. The main methods of study and characterization are gathered in eight chapters, and the authors stress on the specificities due to the porous system: -structural analysis by the diffraction methods; -infrared spectroscopy; -NMR; -micro-calorimetry; -adsorption thermodynamics; -methods using the programed temperature; -modeling; -reactivity: kinetics and chemical engineering. This book appeals to students, engineers or searchers, without previous knowledge on these materials, but having a bachelor's degree or a master degree in general chemistry. (O.M.)

  19. A new apparatus for the determination of adsorption isotherms and adsorption enthalpies on microporous and meso-porous media

    International Nuclear Information System (INIS)

    Mouahid, A.

    2010-01-01

    A specific thermostated experimental device comprising a differential heat flow calorimeter coupled with a home built manometric system has been built for the simultaneous determination of adsorption isotherms and adsorption enthalpies. The differential heat flow calorimeter is a Tian Calvet Setaram C80 model which measures the heat flux of a gas and can be operated isothermally, the manometric system is a stainless steel homemade apparatus. This coupled apparatus allows measurements for pressure up to 2.5 MPa and temperature up to 423.15 K. On the one hand, the apparatus and the experimental procedures are described. On the second hand the reliability and reproducibility were established by measuring adsorption isotherms on a benchmark (Filtrasorb F400) at 318.15 K. The gravimetric method has been used at higher pressure at various temperatures. These devices allowed us to study the adsorption of supercritical fluid (nitrogen N 2 , methane CH 4 , carbon dioxide CO 2 ) in activated carbons and microporous or meso-porous silica. The adsorption of methane on a rock of type (TGR) was also studied. These experimental results are used for the study of the interactions fluid / solid that must be taken into account in molecular simulations or DFT theory. (author)

  20. The increase in pH during aging of porous sol-gel silica spheres

    NARCIS (Netherlands)

    Titulaer, M.K.; Kegel, W.K.; Jansen, J.B.H.; Geus, John W.

    1994-01-01

    The increase in pH in the hydrothermal fluid is studied after hydrothermal aging of porous silica gel spheres of 1–3 mm diameter. The porous silica spheres are formed by the sol-gel process from a supersaturated silica solution. The increase of the pH of the hydrothermal solution affects the silica

  1. Controlling porosity of porous carbon cathode for lithium oxygen batteries: Influence of micro and meso porosity

    Science.gov (United States)

    Kim, Minjae; Yoo, Eunjoo; Ahn, Wha-Seung; Shim, Sang Eun

    2018-06-01

    In rechargeable lithium-oxygen (Li-O2) batteries, the porosity of porous carbon materials plays a crucial role in the electrochemical performance serving as oxygen diffusion path and Li ion transfer passage. However, the influence of optimization of porous carbon as an air electrode on cell electrochemical performance remains unclear. To understand the role of carbon porosity in Li-O2 batteries, carbon materials featuring controlled pore sizes and porosity, including C-800 (nearly 96% microporous) and AC-950 (55:45 micro/meso porosity), are designed and synthesized by carbonization using a triazine-based covalent organic polymer (TCOP). We find that the microporous C-800 cathode allows 120 cycles with a limited capacity of 1000 mAh g-1, about 2 and 10 times higher than that of mixed-porosity AC-950 and mesoporous CMK-3, respectively. Meanwhile, the specific discharge capacity of the C-800 electrode at 200 mA g-1 is 6003 mAh g-1, which is lower than that of the 8433 and 9960 mAh g-1 when using AC-950 and CMK-3, respectively. This difference in the electrochemical performance of the porous carbon cathode with different porosity causes to the generation and decomposition of Li2O2 during the charge and discharge cycle, which affects oxygen diffusion and Li ion transfer.

  2. Sonochemical synthesis and photocatalytic activity of meso- and macro-porous TiO2 for oxidation of toluene

    International Nuclear Information System (INIS)

    Yang Liu; Yan Li; Wang Yuntao; Xie Lei; Zheng Jie; Li Xingguo

    2008-01-01

    Meso-and macro-porous TiO 2 were synthesized by ultrasonic induced solvothermal method. Octadecylamine as a soft template was used to direct the formation of porous structure. The as-prepared porous TiO 2 was characterized by low angle and wide angle X-ray diffraction, N 2 adsorption-desorption isotherms and BET surface area. The energy influence of ultrasound and heat and concentration of nitric acid for post extraction on formation of porous structure were investigated. The photocatalytic activities of TiO 2 were investigated by degrading toluene gas under UV light. The results revealed that proper energy facilitates the formation of porous structure and too low concentration of nitric acid cannot extract template from pores. The photocatalytic activities of TiO 2 with porous structure are higher than those of nonporous ones

  3. Selective porous gates made from colloidal silica nanoparticles

    Directory of Open Access Journals (Sweden)

    Roberto Nisticò

    2015-11-01

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

  4. Nanoparticles of Pt and Ag supported in meso porous SiO2: characterization and catalytic applications

    International Nuclear Information System (INIS)

    Espinosa, M.E.; Perez H, R.; Perez A, M.; Mondragon G, G.; Arenas A, J.

    2004-01-01

    The surface properties of catalysts of Pt and Ag supported in conventional SiO 2 hey have been studied through reduction reactions of N 2 O with H 2 which is a sensitive reaction to the structure. In our case it was used a meso porous ceramic support of SiO 2 of great surface area (1100 m 2 /gr), where it is caused a high dispersion of the metallic nanoparticles of Pt and Ag, the total charge of the active phase in the meso porous support was of 3% in weight. The catalysts show a variation in the percentages of conversion of N 2 O depending on the size and dispersion of the metallic phases. (Author)

  5. Synthesis of Various Silica Nanoparticles for Foam Stability

    International Nuclear Information System (INIS)

    Yoon, Suk Bon; Yoon, Inho; Jung, Chonghun; Kim, Chorong; Choi, Wangkyu; Moon, Jeikwon

    2013-01-01

    The synthesis of the non-porous silica nanoparticles with uniform sizes has been reported through the Sto ber method, the synthesis of meso porous silica nanoparticles with a specific morphology such as core-shell, rod-like, and hexagonal shapes is not so common. As a synthetic strategy for controlling the particle size, shape, and porosity, the synthesis of core-shell silicas with meso porous shells formed on silica particle cores through the self-assembly of silica precursor and organic templates or spherical meso porous silicas using modified Sto ber method was also reported. Recently, in an effort to reduce the amount of radioactive waste and enhance the decontamination efficiency during the decontamination process of nuclear facilities contaminated with radionuclides, a few research for the preparation of the decontamination foam containing solid nanoparticles has been reported. In this work, the silica nanoparticles with various sizes, shapes, and structures were synthesized based on the previous literatures. The resulting silica nanoparticles were used to investigate the effect of the nanoparticles on the foam stability. In a study on the foam stability using various silica nanoparticles, the results showed that the foam volume and liquid volume in foam was enhanced when using a smaller size and lower density of the silica nanoparticles. Silica nanoparticles with various sizes, shapes, and structures such as a non-porous, meso porous core-shell, and meso porous silica were synthesized to investigate the effect of the foam stability. The sizes and structural properties of the silica nanoparticles were easily controlled by varying the amount of silica precursor, surfactant, and ammonia solution as a basic catalyst. The foam prepared using various silica nanoparticles showed that foam the volume and liquid volume in the foam were enhanced when using a smaller size and lower density of the silica nanoparticles

  6. Porous silica from rice husk ash for tundish lining

    International Nuclear Information System (INIS)

    Ahmed, Y.M.Z; Ewais, E.M.

    2007-01-01

    Type of materials as well as its compressive strength and degree of porosity are the determinal parameters for deciding the suitability of its usage as lining for tundish in continuous casting of steel. Silica is one of the materials suitable for such application. High porosity degree with high compressive strength of its compacts is special demands for increasing its efficiency. The suitability of producing porous silica compacts from the combustion of rice husk ash (RHA) appropriate for this application is the objective of the present work. Experimental design technique was used to evaluate the effect of different parameters (i.e. firing temperature, time and compaction pressure) controlling both porosity degree and compressive strength of rice husk ash compacts. The results revealed that while the porosity degree of the compacts decreased with increasing the entire studied parameters, its compressive strength exhibits another trend especially at lower soaking time. At lower soaking time, increasing firing temperature leads to a slight decrease in the compressive strength and then increased thereafter. Porous silica compacts having 30% porosity and > 25 kg/cm/sup 2/ compressive strength suitable for tundish lining could obtain from the combustion of rice husk ash compacts. (author)

  7. Supercritical carbon dioxide behavior in porous silica aerogel

    International Nuclear Information System (INIS)

    Ciccariello, Salvino; Melnichenko, Yuri B.; He, Lilin

    2011-01-01

    Analysis of the tails of the small-angle neutron scattering (SANS) intensities relevant to samples formed by porous silica and carbon dioxide at pressures ranging from 0 to 20 MPa and at temperatures of 308 and 353 K confirms that the CO2 fluid must be treated as a two-phase system. The first of these phases is formed by the fluid closer to the silica wall than a suitable distance (delta) and the second by the fluid external to this shell. The sample scattering-length densities and shell thicknesses are determined by the Porod invariants and the oscillations observed in the Porod plots of the SANS intensities. The resulting matter densities of the shell regions (thickness 15-35 (angstrom)) are approximately equal, while those of the outer regions increase with pressure and become equal to the bulk CO2 at the higher pressures only in the low-temperature case.

  8. NMR of mercury in porous coal and silica gel

    International Nuclear Information System (INIS)

    Kasperovich, V.S.; Charnaya, E.V.; Tien, C.; Wur, C.S.

    2003-01-01

    Temperature dependences of the integral intensity and NMR signals Knight shift in 199 Hg nuclei are measured for liquid and solid mercury introduced into the porous coal and silica gel. The decrease in the crystallization completion temperature and small temperature hysteresis (from 4 up to 9 K) between melting and crystallization are identified. Mercury melting temperature in pores coincided with melting temperature of the bulk mercury. NMR signal from crystalline mercury under conditions of limited geometry was observed for the first time. It is ascertained that Knight shift for mercury in the pores both in liquid and crystalline phases is lesser than for the bulk mercury [ru

  9. CO2 capture on micro/meso-porous composites of (zeolite A)/(MCM-41) with Ca2+ located: Computer simulation and experimental studies

    International Nuclear Information System (INIS)

    Jianhai Zhou; Huiling Zhao; Jinxia Li; Yujun Zhu; Jun Hu; Honglai Liu; Ying Hu

    2013-01-01

    Composing of both zeolite and meso-porous structures, micro/meso-porous composites exhibit promising CO 2 capture capabilities. In this work, a full-atomic mimetic 5A-MCM-41 structure with bimodal pores has been constructed, in which the microporous structure of 5A zeolite is constructed and optimized based on zeolite A with Ca and Na cations introduced; whereas the meso-porous MCM-41 structure is produced by caving the cylindrical pores in the obtained 5A zeolite matrix. CO 2 adsorption on 5A-MCM- 41 has been simulated by the grand canonical Monte Carlo (GCMC). The simulation results demonstrated that CO 2 is preferentially adsorbed in micropores, and the CO 2 adsorption capacity and its isosteric heat on 5A-MCM-41 are much larger than those of N 2 . The CO 2 selectivity of 5A-MCM-41 results from the electrostatic interaction of the quadrupole CO 2 molecule with Ca 2+ cations of the zeolite. Furthermore, the hierarchical micro/meso-porous composites are synthesized to verify the simulated predictions. By the hydrothermal reaction using 5A zeolite 'seeds' as the silicon source and hexadecyl trimethylammonium bromide (CTAB) as the meso-porous template, 5A-MCM-41 composites are obtained, the characteristic results show that typical 5A microporous structure is remained and disordered meso-porous networks are produced in the composites.Moreover, the CO 2 adsorption capacity of the 5A-MCM- 41 composites can reach as high as 4.08 mmol/g at 100 kPa and 298 K. These observations have been strongly supported that micro/meso-porous composites with metal ions located would be promising adsorbents for CO 2 separation. (authors)

  10. Meso-scale modelling of the heat conductivity effect on the shock response of a porous material

    Science.gov (United States)

    Resnyansky, A. D.

    2017-06-01

    Understanding of deformation mechanisms of porous materials under shock compression is important for tailoring material properties at the shock manufacturing of advanced materials from substrate powders and for studying the response of porous materials under shock loading. Numerical set-up of the present work considers a set of solid particles separated by air representing a volume of porous material. Condensed material in the meso-scale set-up is simulated with a viscoelastic rate sensitive material model with heat conduction formulated from the principles of irreversible thermodynamics. The model is implemented in the CTH shock physics code. The meso-scale CTH simulation of the shock loading of the representative volume reveals the mechanism of pore collapse and shows in detail the transition from a high porosity case typical for abnormal Hugoniot response to a moderate porosity case typical for conventional Hugoniot response. Results of the analysis agree with previous analytical considerations and support hypotheses used in the two-phase approach.

  11. Rhodamine 6G impregnated porous silica: A photoluminescence study

    Energy Technology Data Exchange (ETDEWEB)

    Anedda, A. [Dipartimento di Fisica, Universita degli Studi di Cagliari and INMF UdR Cagliari, SP no8, Km 0700, 09042, Monserrato (Canada) (Italy); Carbonaro, C.M. [Dipartimento di Fisica, Universita degli Studi di Cagliari and INMF UdR Cagliari, SP no8, Km 0700, 09042, Monserrato (Canada) (Italy)]. E-mail: cm.carbonaro@dsf.unica.it; Clemente, F. [Dipartimento di Fisica, Universita degli Studi di Cagliari and INMF UdR Cagliari, SP no8, Km 0700, 09042, Monserrato (Ca) (Italy); Corpino, R. [Dipartimento di Fisica, Universita degli Studi di Cagliari and INMF UdR Cagliari, SP no8, Km 0700, 09042, Monserrato (Ca) (Italy); Ricci, P.C. [Dipartimento di Fisica, Universita degli Studi di Cagliari and INMF UdR Cagliari, SP no8, Km 0700, 09042, Monserrato (Ca) (Italy); Rossini, S. [Dipartimento di Fisica, Universita degli Studi di Cagliari and INMF UdR Cagliari, SP no8, Km 0700, 09042, Monserrato (Ca) (Italy)

    2005-12-15

    The optical properties of rhodamine 6G dye confined in porous silica are reported. Photoluminescence properties of embedded chromophores in mesoporous hosts can be affected by the surrounding matrices: shifts in emission spectra and variations of photoluminescence quantum yield are found as compared to dye solutions. Host-guest interactions are studied here by varying both SiO{sub 2} xerogels porosity and the dye concentration. Comparing samples obtained by impregnating matrices with 5.4 and 18.2 nm pores with solutions having concentrations in the rhodamine 6G high laser gain, matrices with 5.4 nm pores impregnated with a dye concentration of 5 x 10{sup -4} M are found to be the most stable and efficient in the examined range.

  12. Molecular dynamics study of shock compression in porous silica glass

    Science.gov (United States)

    Jones, Keith; Lane, J. Matthew D.; Vogler, Tracy J.

    2017-06-01

    The shock response of porous amorphous silica is investigated using classical molecular dynamics, over a range of porosity ranging from fully dense (2.21 g/cc) down to 0.14 g/cc. We observe an enhanced densification in the Hugoniot response at initial porosities above 50 %, and the effect increases with increasing porosity. In the lowest initial densities, after an initial compression response, the systems expand with increased pressure. These results show good agreement with experiments. Mechanisms leading to enhanced densification will be explored, which appear to differ from mechanisms observed in similar studies in silicon. Sandia National Laboratories is a multi mission laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  13. The effect of NaOH and KOH on the characterization of meso porous AlOOH nano structures in the hydrothermal route

    International Nuclear Information System (INIS)

    Haghnazari, N.; Abdollahifar, M.; Jahani, F.

    2014-01-01

    Meso porous AlOOH was synthesized by hydrothermal treatment from aluminium nitrate and NaOH or KOH. The effect of NaOH and KOH as precipitating agents on the characterization of samples were investigated. XRD, Ftir, FESEM and N 2 adsorption-desorption analytical techniques were used to characterize the products. Our results showed that using KOH as precipitating agent was favour-able for the formation of meso porous and crystalline AlOOH with high Bet-specific surface area of 98 m 2 /g. (Author)

  14. The effect of NaOH and KOH on the characterization of meso porous AlOOH nano structures in the hydrothermal route

    Energy Technology Data Exchange (ETDEWEB)

    Haghnazari, N.; Abdollahifar, M.; Jahani, F., E-mail: abdollahifar@gmail.com [Islamic Azad University, Kermanshah Branch, Department of Chemical Engineering, 67131 Kermanshah (Iran, Islamic Republic of)

    2014-10-01

    Meso porous AlOOH was synthesized by hydrothermal treatment from aluminium nitrate and NaOH or KOH. The effect of NaOH and KOH as precipitating agents on the characterization of samples were investigated. XRD, Ftir, FESEM and N{sub 2} adsorption-desorption analytical techniques were used to characterize the products. Our results showed that using KOH as precipitating agent was favour-able for the formation of meso porous and crystalline AlOOH with high Bet-specific surface area of 98 m{sup 2}/g. (Author)

  15. Granulation study of porous silica particles for MA recovery process

    International Nuclear Information System (INIS)

    Goto, Ichiro; Kofuji, Hirohide; Oriuchi, Akio; Watanabe, Sou; Takeuchi, Masayuki

    2017-01-01

    JAEA has been working on partition of MA from HLLW generated in the reprocessing by extraction chromatography technology. This technology utilizes 50 μm porous silica particles coated by styrene-divinylbenzene copolymer in which an extractant for MA recovery is impregnated as adsorbent. In this study, spray drying granulating experiments with various operating conditions and with different experimental apparatuses were carried out to find an appropriate condition to control the size of the particle and the pore. The target average sizes of the particle and pore are more than 50 μm and 600 nm respectively. Suspension containing fine silica particles were supplied to the spray drying devices, and small droplets generated through the spray nozzle were dried inside the drying chamber. In this study, viscosity of the feed solution and some granulation conditions were parametrically changed, and two different types of the spray nozzles were used. An air atomizing nozzle and a rotary disk nozzle were equipped at different chambers respectively. Then, performance of the product particle was evaluated by particle and pore size distributions and adsorption experiment after the polymer coating and an extractant impregnation. The particle size of the product depended on the atomizing pressure and viscosity of the feed solution, and the size increased with decrease in the pressure and in the viscosity. The maximum size obtained in this study was about 40 μm. Large viscosity of the feed solution lead poor recovery ratio and uniformity in the size distribution of the product powder. The pore size of the resultant particle was 550-800 nm as expected. As the type of the nozzle changed from the air atomizing nozzle to the rotary disk nozzle and size of the drying chamber became large, the average particle size and the particle size distribution became large and sharp, respectively. Rotation speed of the nozzle also influenced on the particle size, and targeted average size of the

  16. Effect of Nano Silica on the Physical Property of Porous Concrete Pavement

    Science.gov (United States)

    Yusak, Mohd Ibrahim Mohd; Ezree Abdullah, Mohd; Putra Jaya, Ramadhansyah; Rosli Hainin, Mohd; Ibrahim, Mohd Haziman Wan

    2017-08-01

    Rice husk can be categorized as an organic waste material from paddy industries. Silica is a major inorganic element of the rice husk. The aim of present study is to evaluate the effect of Nano silica on the physical properties of porous concrete pavement. Rice husk has been burned in the furnace (650°C for 6 hours) and ground for four different grinding times (33, 48, 63 and 81 hours). Five types of mixes were prepared to evaluate the different Nano silica grinding time. A Nano silica dosage of 10% by weight of binder was used throughout the experiments. The physical properties were examined through compressive strength, transmission electron microscopy and x-ray fluorescence. The experimental results indicate that the different Nano size gives a different effect to porous concrete strength. Based on the results obtained, Nano silica ground for 63 hours (65.84nm) gives the best result and performance to porous concrete pavement specimens.

  17. Vapor phase epitaxy of silicon on meso porous silicon for deposition on economical substrate and low cost photovoltaic application

    International Nuclear Information System (INIS)

    Quoizola, S.

    2003-01-01

    The silicon is more and more used in the industry. Meanwhile the production cost is a problem to solve to develop the photovoltaic cells production. This thesis presents a new technology based on the use of a meso-porous silicon upper layer,to grow the active silicon layer of 50 μm width. The photovoltaic cell is then realized, the device is removed and placed on a low cost substrate. The silicon substrate of beginning can be used again after cleaning. The first chapter presents the operating and the characteristics of the silicon photovoltaic cell. The second chapter is devoted to the growth technique, the vapor phase epitaxy, and the third chapter to the epitaxy layer. The chapter four deals with the porous silicon and the structure chosen in this study. The chapter five is devoted to the characterization of the epitaxy layer on porous silicon. The photovoltaic cells realized on these layers are presented in the last chapter. (A.L.B.)

  18. Investigation of porous concrete through macro and meso-scale testing

    NARCIS (Netherlands)

    Agar Ozbek, A.S.; Weerheijm, J.; Schlangen, H.E.J.G.

    2010-01-01

    In designing a porous concrete, containing a high volume of air pores, the effects of its mesoscale phases on its macro level properties have to be known. For this purpose, porous concretes having different aggregate gradings and cement paste compositions were investigated through macro-scale

  19. Sedimentation behaviour and colloidal properties of porous, chemically modified silicas in non-aqueous solvents

    NARCIS (Netherlands)

    Vissers, J.P.C.; Laven, J.; Claessens, H.A.; Cramers, C.A.M.G.; Agterof, W.G.M.

    1997-01-01

    The sedimentation behaviour and colloidal properties of porous, chemically modified silicas dispersed in non-aqueous solvents have been studied. The free settling behaviour of non-aggregated silica suspensions could effectively be described with a modified Stokes equation that takes into account the

  20. A polyacrylonitrile copolymer-silica template for three-dimensional hierarchical porous carbon as a Pt catalyst support for the oxygen reduction reaction.

    Science.gov (United States)

    Liu, Minmin; Li, Jian; Cai, Chao; Zhou, Ziwei; Ling, Yun; Liu, Rui

    2017-08-01

    Herein, we report a novel route to construct a hierarchical three-dimensional porous carbon (3DC) through a copolymer-silica assembly. In the synthesis, silica acts as a hard template and leads to the formation of an interconnected 3D macropore, whereas styrene-co-acrylonitrile polymer has been used as both a carbon source and a soft template for micro- and meso-pores. The obtained 3DC materials possess a large surface area (∼550.5 m 2 g -1 ), which facilitates high dispersion of Pt nanoparticles on the carbon support. The 3DC-supported Pt electrocatalyst shows excellent performance in the oxygen reduction reaction (ORR). The easy processing ability along with the characteristics of hierarchical porosity offers a new strategy for the preparation of carbon nanomaterials for energy application.

  1. 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.

  2. Silica decorated on porous activated carbon nanofiber composites for high-performance supercapacitors

    Science.gov (United States)

    Kim, So Yeun; Kim, Bo-Hye

    2016-10-01

    A hybrid of silica decorated on porous activated carbon nanofibers (ACNFs) is fabricated in the form of a web via electrospinning and an activation process as an electrode material for electrochemical capacitors in an organic electrolyte. The introduction of PhSiH3 (PS) into the polyacrylonitrile (PAN) solution induces a porous ACNF structure containing silica nanoparticles (NPs) via the spontaneous sol-gel process of PS by steam in the subsequent physical activation process. These inorganic-organic hybrid composites of porous ACNF containing silica NPs show superior specific capacitance and energy density in electrochemical tests, along with good rate capability and excellent cycle life in an organic electrolyte, which is attributed to the combination of ACNF's high surface area and silica's hydrophilicity. The electrochemical performance decreases with increasing PS concentration, and this trend is consistent with the specific surface area results, which reveal the rapid formation of a double layer.

  3. One-pot pseudomorphic crystallization of mesoporous porous silica to hierarchical porous zeolites

    Energy Technology Data Exchange (ETDEWEB)

    Xing, Jun-Ling; Jiang, Shu-Hua; Pang, Jun-Ling; Yuan, En-Hui; Ma, Xiao-Jing [Shanghai Key Laboratory of Green Chemistry and Chemical Processes, College of Chemistry and Molecular Engineering, East China Normal University, No. 3663 Zhongshan North Road, 200062 Shanghai (China); Lam, Koon-Fung [Department of Chemical Engineering, University College London, Torrington Place, London (United Kingdom); Xue, Qing-Song, E-mail: qsxue@chem.ecnu.edu.cn [Shanghai Key Laboratory of Green Chemistry and Chemical Processes, College of Chemistry and Molecular Engineering, East China Normal University, No. 3663 Zhongshan North Road, 200062 Shanghai (China); Zhang, Kun, E-mail: kzhang@chem.ecnu.edu.cn [Shanghai Key Laboratory of Green Chemistry and Chemical Processes, College of Chemistry and Molecular Engineering, East China Normal University, No. 3663 Zhongshan North Road, 200062 Shanghai (China)

    2015-09-15

    Hierarchically porous silica with mesopore and zeolitic micropore was synthesized via pseudomorphic crystallization under high-temperature hydrothermal treatment in the presence of cetyltrimethylammonium tosylate and tetrapropylammonium ions. A combined characterization using small-angle X-ray diffraction (XRD), nitrogen adsorption, high-resolution transmission electron microscopy (TEM), thermogravimetric analysis (TG), and elemental analysis showed that dual templates, CTA{sup +} and TPA{sup +} molecules, can work in a cooperative manner to synthesize mesoporous zeolite in a one-pot system by precisely tuning the reaction conditions, such as reaction time and temperature, and type and amount of heterometal atoms. It is found that the presence of Ti precursor is critical to the successful synthesis of such nanostructure. It not only retards the nucleation and growth of crystalline MFI domains, but also acts as nano-binder or nano-glue to favor the assembly of zeolite nanoblocks. - Graphical abstract: Display Omitted - Highlights: • A facile method to synthesize mesoporous zeolites with hierarchical porosity was presented. • It gives a new insight into keeping the balance between mesoscopic and molecular ordering in hierarchical porous materials. • A new understanding on the solid–solid transformation mechanism for the synthesis of titanosilicate zeolites was proposed.

  4. The retained templates as "helpers" for the spherical meso-silica in adsorption of heavy metals and impacts of solution chemistry.

    Science.gov (United States)

    Liang, Zhijie; Shi, Wenxin; Zhao, Zhiwei; Sun, Tianyi; Cui, Fuyi

    2017-06-15

    The spherical mesoporous silica (meso-silica) MCM-41 and those with different dosage of the retained templates were prepared and characterized. Particularly, effects of the retained template and its dosage on the adsorption of typical heavy metals (Cu 2+ and Cd 2+ ) in the synthesized materials were investigated. The results indicated that the retained templates acted as "helpers" for the adsorption of Cu 2+ and Cd 2+ in the spherical meso-silica MCM-41, and the maximum adsorption capacities (Q max ) increased with the increase of the retained template dosage. The interaction between the metal ions and the cationic heads of the templates contributed to the enhancement effect due to the anions (Cl - and OH - ) electronically adsorbed on the interface of the template micelles. Additionally, the presented results indicated that the adsorption of Cu 2+ and Cd 2+ depended on pH and high ion strength of the solution but not on the coexisted humic acid. Copyright © 2017 Elsevier Inc. All rights reserved.

  5. Synthesis of porous carbon/silica nanostructured microfiber with ultrahigh surface area

    Science.gov (United States)

    Zhou, Dan; Dong, Yan; Cui, Liru; Lin, Huiming; Qu, Fengyu

    2014-12-01

    Carbon/silica-nanostructured microfibers were synthesized via electrospinning method using phenol-formaldehyde resin and tetraethyl orthosilicate as carbon and silica precursor with triblock copolymer Pluronic P123 as soft template. The prepared samples show uniform microfiber structure with 1 μm in diameter and dozens of microns in length. Additionally, the mesopores in the material is about 2-6 nm. When the silica component was removed by HF, the porous carbon microfibers (PCMFs) were obtained. In addition, after the carbon/silica composites were calcined in air, the porous silica microfibers (PSiMFs) were obtained, revealing the converse porous nanostructure as PCMFs. It is a simple way to prepare PCMFs and PSiMFs with silica and carbon as the template to each other. Additionally, PCMFs possess an ultrahigh specific surface area (2,092 m2 g-1) and large pore volume. The electrochemical performance of the prepared PCMF material was investigated in 6.0 M KOH electrolyte. The PCMF electrode exhibits a high specific capacitance (252 F g-1 at 0.5 A g-1). Then, superior cycling stability (97 % retention after 4,000 cycles) mainly is due to its unique nanostructure.

  6. Synthesis of porous carbon/silica nanostructured microfiber with ultrahigh surface area

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Dan; Dong, Yan; Cui, Liru; Lin, Huiming, E-mail: hiuminglin@gmail.com; Qu, Fengyu, E-mail: qufengyu2012@yahoo.cn, E-mail: qufengyu@hrbnu.edu.cn [Harbin Normal University, College of Chemistry and Chemical Engineering (China)

    2014-12-15

    Carbon/silica-nanostructured microfibers were synthesized via electrospinning method using phenol-formaldehyde resin and tetraethyl orthosilicate as carbon and silica precursor with triblock copolymer Pluronic P123 as soft template. The prepared samples show uniform microfiber structure with ∼1 μm in diameter and dozens of microns in length. Additionally, the mesopores in the material is about 2–6 nm. When the silica component was removed by HF, the porous carbon microfibers (PCMFs) were obtained. In addition, after the carbon/silica composites were calcined in air, the porous silica microfibers (PSiMFs) were obtained, revealing the converse porous nanostructure as PCMFs. It is a simple way to prepare PCMFs and PSiMFs with silica and carbon as the template to each other. Additionally, PCMFs possess an ultrahigh specific surface area (2,092 m{sup 2} g{sup −1}) and large pore volume. The electrochemical performance of the prepared PCMF material was investigated in 6.0 M KOH electrolyte. The PCMF electrode exhibits a high specific capacitance (252 F g{sup −1} at 0.5 A g{sup −1}). Then, superior cycling stability (97 % retention after 4,000 cycles) mainly is due to its unique nanostructure.

  7. Porous silica nanoparticles as carrier for curcumin delivery

    Science.gov (United States)

    Hartono, Sandy Budi; Hadisoewignyo, Lannie; Irawaty, Wenny; Trisna, Luciana; Wijaya, Robby

    2018-04-01

    Mesoporous silica nanoparticles (MSN) with large surface areas and pore volumes show great potential as drug and gene carriers. However, there are still some challenging issues hinders their clinical application. Many types of research in the use of mesoporous silica material for drug and gene delivery involving complex and rigorous procedures. A facile and reproducible procedure to prepare combined drug carrier is required. We investigated the effect of physiochemical parameters of mesoporous silica, including structural symmetry (cubic and hexagonal), particles size (micro size: 1-2 µm and nano size: 100 -300 nm), on the solubility and release profile of curcumin. Transmission Electron Microscopy, X-Ray Powder Diffraction, and Nitrogen sorption were used to confirm the synthesis of the mesoporous silica materials. Mesoporous silica materials with different mesostructures and size have been synthesized successfully. Curcumin has anti-oxidant, anti-inflammation and anti-virus properties which are beneficial to fight various diseases such as diabetic, cancer, allergic, arthritis and Alzheimer. Curcumin has low solubility which minimizes its therapeutic effect. The use of nanoporous material to carry and release the loaded molecules is expected to enhance curcumin solubility. Mesoporous silica materials with a cubic mesostructure had a higher release profile and curcumin solubility, while mesoporous silica materials with a particle size in the range of nano meter (100-300) nm also show better release profile and solubility.

  8. NMR 1D-imaging of water infiltration into meso-porous matrices

    International Nuclear Information System (INIS)

    Le Feunteun, St.; Diat, O.; Podor, R.; Le Feunteun, St.; Poulesquen, A.; Poulesquen, A.

    2011-01-01

    It is shown that coupling nuclear magnetic resonance (NMR) 1D-imaging with the measure of NMR relaxation times and self-diffusion coefficients can be a very powerful approach to investigate fluid infiltration into porous media. Such an experimental design was used to study the very slow seeping of pure water into hydrophobic materials. We consider here three model samples of nuclear waste conditioning matrices which consist in a dispersion of NaNO 3 (highly soluble) and/or BaSO 4 (poorly soluble) salt grains embedded in a bitumen matrix. Beyond studying the moisture progression according to the sample depth, we analyze the water NMR relaxation times and self-diffusion coefficients along its 1D-concentration profile to obtain spatially resolved information on the solution properties and on the porous structure at different scales. It is also shown that, when the relaxation or self-diffusion properties are multimodal, the 1D-profile of each water population is recovered. Three main levels of information were disclosed along the depth-profiles. They concern (i) the water uptake kinetics, (ii) the salinity and the molecular dynamics of the infiltrated solutions and (iii) the microstructure of the water-filled porosities: open networks coexisting with closed pores. All these findings were fully validated and enriched by NMR cryo-poro-metry experiments and by performing environmental scanning electronic microscopy observations. Surprisingly, results clearly show that insoluble salts enhance the water progression and thereby increase the capability of the material to uptake water. (authors)

  9. Interphases, gelation, vitrification, porous glasses and the generalized Cauchy relation: epoxy/silica nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Philipp, M; Mueller, U; Jimenez Rioboo, R J; Baller, J; Sanctuary, R; Krueger, J K [Laboratoire de Physique des Materiaux, University of Luxembourg, 162A avenue de la Faiencerie, L-1511 Luxembourg (Luxembourg); Possart, W [Fachbereich Werkstoffwissenschaften, Universitaet des Saarlandes, D-66123 Saarbruecken (Germany)], E-mail: martine.philipp@uni.lu

    2009-02-15

    The generalized Cauchy relation (gCR) of epoxy/silica nano-composites does not show either the chemically induced sol-gel transition or the chemically induced glass transition in the course of polymerization. Astonishingly, by varying the silica nanoparticles' concentration between 0 and 25 vol% in the composites, the Cauchy parameter A of the gCR remains universal and can be determined from the pure epoxy's elastic moduli. Air-filled porous silica glasses are considered as models for percolated silica particles. A longitudinal modulus versus density representation evidences the aforementioned transition phenomena during polymerization of the epoxy/silica nanocomposites. The existence of optically and mechanically relevant interphases is discussed.

  10. Interphases, gelation, vitrification, porous glasses and the generalized Cauchy relation: epoxy/silica nanocomposites

    International Nuclear Information System (INIS)

    Philipp, M; Mueller, U; Jimenez Rioboo, R J; Baller, J; Sanctuary, R; Krueger, J K; Possart, W

    2009-01-01

    The generalized Cauchy relation (gCR) of epoxy/silica nano-composites does not show either the chemically induced sol-gel transition or the chemically induced glass transition in the course of polymerization. Astonishingly, by varying the silica nanoparticles' concentration between 0 and 25 vol% in the composites, the Cauchy parameter A of the gCR remains universal and can be determined from the pure epoxy's elastic moduli. Air-filled porous silica glasses are considered as models for percolated silica particles. A longitudinal modulus versus density representation evidences the aforementioned transition phenomena during polymerization of the epoxy/silica nanocomposites. The existence of optically and mechanically relevant interphases is discussed.

  11. Preparation and characterization of monodisperse large-porous silica microspheres as the matrix for protein separation.

    Science.gov (United States)

    Xia, Hongjun; Wan, Guangping; Zhao, Junlong; Liu, Jiawei; Bai, Quan

    2016-11-04

    High performance liquid chromatography (HPLC) is a kind of efficient separation technology and has been used widely in many fields. Micro-sized porous silica microspheres as the most popular matrix have been used for fast separation and analysis in HPLC. In this paper, the monodisperse large-porous silica microspheres with controllable size and structure were successfully synthesized with polymer microspheres as the templates and characterized. First, the poly(glycidyl methacrylate-co-ethyleneglycol dimethacrylate) microspheres (P GMA-EDMA ) were functionalized with tetraethylenepentamine (TEPA) to generate amino groups which act as a catalyst in hydrolysis of tetraethyl orthosilicate (TEOS) to form Si-containing low molecular weight species. Then the low molecular weight species diffused into the functionalized P GMA-EDMA microspheres by induction force of the amino groups to form polymer/silica hybrid microspheres. Finally, the organic polymer templates were removed by calcination, and the large-porous silica microspheres were obtained. The compositions, morphology, size distribution, specific surface area and pore size distribution of the porous silica microspheres were characterized by infrared analyzer, scanning-electron microscopy, dynamic laser scattering, the mercury intrusion method and thermal gravimetric analysis, respectively. The results show that the agglomeration of the hybrid microspheres can be overcome when the templates were functionalized with TEPA as amination reagent, and the yield of 95.7% of the monodisperse large-porous silica microspheres can be achieved with high concentration of polymer templates. The resulting large-porous silica microspheres were modified with octadecyltrichlorosilane (ODS) and the chromatographic evaluation was performed by separating the proteins and the digest of BSA. The baseline separation of seven kinds of protein standards was achieved, and the column delivered a better performance when separating BSA digests

  12. Targeting of porous hybrid silica nanoparticles to cancer cells

    NARCIS (Netherlands)

    Rosenholm, J.M.; Meinander, A.; Peuhu, E.; Niemi, R.; Eriksson, J.E.; Sahlgren, C.; Lindén, M.

    2009-01-01

    Mesoporous silica nanoparticles functionalized by surface hyperbranching polymerization of polyethylene imine), PEI, were further modified by introducing both fluorescent and targeting moieties, with the aim of specifically targeting cancer cells. Owing to the high abundance of folate receptors in

  13. Effect of Synthesis Time on Morphology of Hollow Porous Silica Microspheres

    Directory of Open Access Journals (Sweden)

    Qian CHEN

    2012-03-01

    Full Text Available Hollow porous silica microspheres may be applicable as containers for the controlled release in drug delivery systems (DDS, foods, cosmetics, agrochemical, textile industry, and in other technological encapsulation use. In order to control the surface morphological properties of the silica microspheres, the effect of synthesis time on their formation was studied by a method of water-in-oil (W/O emulsion mediated sol-gel techniques. An aqueous phase of water, ammonium hydroxide and a surfactant Tween 20 was emulsified in an oil phase of 1-octanol with a stabilizer, hydroxypropyl cellulose (HPC, and a surfactant, sorbitan monooleate (Span 80 with low hydrophile-lipophile balance (HLB value. Tetraethyl orthosilicate (TEOS as a silica precursor was added to the emulsion. The resulting silica particles at different synthesis time 24, 48, and 72 hours were air-dried at room temperature and calcinated at 773 K for 3 hours. The morphology of the particles was characterized by scanning electron microscopy and the particle size distribution was measured by laser diffraction. The specific surface areas were studied by 1-point BET method, and pore sizes were measured by Image Tool Software. Both dense and porous silica microspheres were observed after all three syntheses. Hollow porous silica microspheres were formed at 24 and 48 hours synthesis time. Under base catalyzed sol-gel solution, the size of silica particles was in the range of 5.4 μm to 8.2 μm, and the particles had surface area of 111 m2/g – 380 m2/g. The longer synthesis time produced denser silica spheres with decreased pore sizes.DOI: http://dx.doi.org/10.5755/j01.ms.18.1.1344

  14. Moisture sensor based on evanescent wave light scattering by porous sol-gel silica coating

    Science.gov (United States)

    Tao, Shiquan; Singh, Jagdish P.; Winstead, Christopher B.

    2006-05-02

    An optical fiber moisture sensor that can be used to sense moisture present in gas phase in a wide range of concentrations is provided, as well techniques for making the same. The present invention includes a method that utilizes the light scattering phenomenon which occurs in a porous sol-gel silica by coating an optical fiber core with such silica. Thus, a porous sol-gel silica polymer coated on an optical fiber core forms the transducer of an optical fiber moisture sensor according to an embodiment. The resulting optical fiber sensor of the present invention can be used in various applications, including to sense moisture content in indoor/outdoor air, soil, concrete, and low/high temperature gas streams.

  15. Thermally induced structural modifications and O2 trapping in highly porous silica nanoparticles

    International Nuclear Information System (INIS)

    Alessi, A.; Agnello, S.; Iovino, G.; Buscarino, G.; Melodia, E.G.; Cannas, M.; Gelardi, F.M.

    2014-01-01

    In this work we investigate by Raman spectroscopy the effect of isochronal (2 h) thermal treatments in air in the temperature range 200–1000 °C of amorphous silicon dioxide porous nanoparticles with diameters ranging from 5 up to 15 nm and specific surface 590–690 m 2 /g. Our results indicate that the amorphous structure changes similarly to other porous systems previously investigated, in fact superficial SiOH groups are removed, Si–O–Si linkages are created and the ring statistic is modified, furthermore these data evidence that the three membered rings do not contribute significantly to the Raman signal detected at about 495 cm −1 . In addition, after annealing at 900 and 1000 °C we noted the appearance of the O 2 emission at 1272 nm, absent in the not treated samples. The measure of the O 2 emission has been combined with electron paramagnetic resonance measurements of the γ irradiation induced HO · 2 radicals to investigate the O 2 content per mass unit of thin layers of silica. Our data reveal that the porous nanoparticles have a much lower ability to trap O 2 molecules per mass units than nonporous silica supporting a model by which O 2 trapping inside a surface layer of about 1 nm of silica is always limited. - Highlights: • O 2 emission and HO · 2 electron paramagnetic resonance signals are investigated. • Silica surface ability to trap O 2 molecules is explored by thermal treatments. • Raman study of thermally induced structural changes in porous silica nanoparticles. • Raman signal attributable to the three membered rings in silica

  16. Thermally induced structural modifications and O{sub 2} trapping in highly porous silica nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Alessi, A., E-mail: antonino.alessi@unipa.it; Agnello, S.; Iovino, G.; Buscarino, G.; Melodia, E.G.; Cannas, M.; Gelardi, F.M.

    2014-12-15

    In this work we investigate by Raman spectroscopy the effect of isochronal (2 h) thermal treatments in air in the temperature range 200–1000 °C of amorphous silicon dioxide porous nanoparticles with diameters ranging from 5 up to 15 nm and specific surface 590–690 m{sup 2}/g. Our results indicate that the amorphous structure changes similarly to other porous systems previously investigated, in fact superficial SiOH groups are removed, Si–O–Si linkages are created and the ring statistic is modified, furthermore these data evidence that the three membered rings do not contribute significantly to the Raman signal detected at about 495 cm{sup −1}. In addition, after annealing at 900 and 1000 °C we noted the appearance of the O{sub 2} emission at 1272 nm, absent in the not treated samples. The measure of the O{sub 2} emission has been combined with electron paramagnetic resonance measurements of the γ irradiation induced HO{sup ·}{sub 2} radicals to investigate the O{sub 2} content per mass unit of thin layers of silica. Our data reveal that the porous nanoparticles have a much lower ability to trap O{sub 2} molecules per mass units than nonporous silica supporting a model by which O{sub 2} trapping inside a surface layer of about 1 nm of silica is always limited. - Highlights: • O{sub 2} emission and HO{sup ·}{sub 2} electron paramagnetic resonance signals are investigated. • Silica surface ability to trap O{sub 2} molecules is explored by thermal treatments. • Raman study of thermally induced structural changes in porous silica nanoparticles. • Raman signal attributable to the three membered rings in silica.

  17. One-step synthesis of dye-incorporated porous silica particles

    Energy Technology Data Exchange (ETDEWEB)

    Liu Qing; DeShong, Philip; Zachariah, Michael R., E-mail: mrz@umd.edu [University of Maryland, Department of Chemistry and Biochemistry (United States)

    2012-07-15

    Fluorescent nanoparticles have a variety of biomedical applications as diagnostics and traceable drug delivery agents. Highly fluorescent porous silica nanoparticles were synthesized in a water/oil phase by a microemulsion method. What is unique about the resulting porous silica nanoparticles is the combination of a single-step, efficient synthesis and the high stability of its fluorescence emission in the resulting materials. The key of the success of this approach is the choice of a lipid dye that functions as a surrogate surfactant in the preparation. The surfactant dye was incorporated at the interface of the inorganic silica matrix and organic environment (pore template), and thus insures the stability of the dye-silica hybrid structure. The resulting fluorescent silica materials have a number of properties that make them attractive for biomedical applications: the availability of various color of the resulting nanoparticle from among a broad spectrum of commercially dyes, the controllablity of pore size (diameters of {approx}5 nm) and particle size (diameters of {approx}40 nm) by adjusting template monomer concentration and the water/oil ratio, and the stability and durability of particle fluorescence because of the deep insertion of surfactant's tail into the silica matrix.

  18. A silica sol-gel design strategy for nanostructured metallic materials

    NARCIS (Netherlands)

    Warren, S.C.; Perkins, M.R.; Adams, A.M.; Kamperman, M.M.G.

    2012-01-01

    Batteries, fuel cells and solar cells, among many other high-current-density devices, could benefit from the precise meso- to macroscopic structure control afforded by the silica sol–gel process. The porous materials made by silica sol–gel chemistry are typically insulators, however, which has

  19. Fullerenol-Capped Porous Silica Nanoparticles for pH-Responsive Drug Delivery

    Directory of Open Access Journals (Sweden)

    Nikola Ž. Knežević

    2015-01-01

    Full Text Available Novel nanocomposite containing fullerenol nanoparticles (FNP and porous silica nanoparticles (PSNs was constructed and characterized. The capability of FNP to serve as a pore-capping agent and for entrapping 9-aminoacridine (9-AA inside the pores of the PSN material was also demonstrated. Nitrogen sorption measurements evidence the successful capping of the silica pores while thermogravimetric analysis of FNP loaded PSN indicates the existence of pore-loaded fullerenol molecules. Higher amount of the drug release was noted by exposing the material to weakly acidic conditions in comparison to physiological pH, which may find application in targeted treatment of weakly acidic tumor tissues.

  20. Porous Silica Sol-Gel Glasses Containing Reactive V2O5 Groups

    Science.gov (United States)

    Stiegman, Albert E.

    1995-01-01

    Porous silica sol-gel glasses into which reactive vanadium oxide functional groups incorporated exhibit number of unique characteristics. Because they bind molecules of some species both reversibly and selectively, useful as chemical sensors or indicators or as scrubbers to remove toxic or hazardous contaminants. Materials also oxidize methane gas photochemically: suggests they're useful as catalysts for conversion of methane to alcohol and for oxidation of hydrocarbons in general. By incorporating various amounts of other metals into silica sol-gel glasses, possible to synthesize new materials with broad range of new characteristics.

  1. Nanoscale assembly of lanthanum silica with dense and porous interfacial structures.

    Science.gov (United States)

    Ballinger, Benjamin; Motuzas, Julius; Miller, Christopher R; Smart, Simon; Diniz da Costa, João C

    2015-02-03

    This work reports on the nanoscale assembly of hybrid lanthanum oxide and silica structures, which form patterns of interfacial dense and porous networks. It was found that increasing the molar ratio of lanthanum nitrate to tetraethyl orthosilicate (TEOS) in an acid catalysed sol-gel process alters the expected microporous metal oxide silica structure to a predominantly mesoporous structure above a critical lanthanum concentration. This change manifests itself by the formation of a lanthanum silicate phase, which results from the reaction of lanthanum oxide nanoparticles with the silica matrix. This process converts the microporous silica into the denser silicate phase. Above a lanthanum to silica ratio of 0.15, the combination of growth and microporous silica consumption results in the formation of nanoscale hybrid lanthanum oxides, with the inter-nano-domain spacing forming mesoporous volume. As the size of these nano-domains increases with concentration, so does the mesoporous volume. The absence of lanthanum hydroxide (La(OH)3) suggests the formation of La2O3 surrounded by lanthanum silicate.

  2. Fabrication of Meso-Porous Gamma-Alumina Films by Sol-Gel and Gel Casting Processes for Making Moisture Sensors

    Directory of Open Access Journals (Sweden)

    Kalyan Kumar Mistry

    2007-04-01

    Full Text Available Meso-porous g-Al2O3 film may be used as a highly sensitive trace moisture sensor. The crack-free alumina film was developed using a combination of sol-gel and tape casting processes, which produce high porosity, high surface area and small pore dimensions in the range of few nano-meter at uniform distribution. Sol-gel processes are well known in nano-technology and nano-material preparation, but it is difficult to make crack-free thick or thin films using this method. Tape cast methods are used for the fabrication of flexible crack-free thick ceramic sheets. Our objective was to develop nano-structured, crack-free, transparent Al2O3 film a few microns thick, has a highly porous and stable crystallographic nature. A metallic paste was printed by screen printing on both side of the film surface for electrodes to form a sensitive element. A silver wire (dia j=0.1mm lead was connected to a grid structure electrode using a silver paste spot for fine joining. Alumina is absorbs moisture molecules into its meso-porous layer and changes its electrical characteristics according to the moisture content, its dielectric constant increase as moisture increase. Moisture molecules can be conceived of as dipoles in random state before the application of an electric field. When the dipole orientation was changed from random to an equilibrium state under the application of external field, a large change in dielectric constant was observed. The number of water molecules absorbed determines the electrical impedance of the capacitor, which in turn is proportional to water vapor pressure.

  3. Control of Partial Coalescence of Self-Assembled Metal Nano-Particles across Lyotropic Liquid Crystals Templates towards Long Range Meso-Porous Metal Frameworks Design

    Directory of Open Access Journals (Sweden)

    Ludovic F. Dumée

    2015-10-01

    Full Text Available The formation of purely metallic meso-porous metal thin films by partial interface coalescence of self-assembled metal nano-particles across aqueous solutions of Pluronics triblock lyotropic liquid crystals is demonstrated for the first time. Small angle X-ray scattering was used to study the influence of the thin film composition and processing conditions on the ordered structures. The structural characteristics of the meso-structures formed demonstrated to primarily rely on the lyotropic liquid crystal properties while the nature of the metal nano-particles used as well as the their diameters were found to affect the ordered structure formation. The impact of the annealing temperature on the nano-particle coalescence and efficiency at removing the templating lyotropic liquid crystals was also analysed. It is demonstrated that the lyotropic liquid crystal is rendered slightly less thermally stable, upon mixing with metal nano-particles and that low annealing temperatures are sufficient to form purely metallic frameworks with average pore size distributions smaller than 500 nm and porosity around 45% with potential application in sensing, catalysis, nanoscale heat exchange, and molecular separation.

  4. Pretreatments of porous silica for improving the activity of a nickel-loaded catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Arai, M.; Ikushima, Y.; Nishiyama, Y.

    1986-02-01

    Nickel catalysts supported on porous silicas treated with water, ethanol, and 1-butanol were found to be more active than that supported on untreated silica for ethane hydrogenolysis and furan hydrogenation. To elucidate the reason for the activation, some surface properties of the treated silicas were examined. The treatments decreased the surface area and increased the volume of the macropores, the surface density of hydroxyl groups, and the heat of immersion in water per unit surface area. The state of nickel on the support was examined by temperature programed desorption (TPD) of hydrogen, X-ray diffraction (XRD), and scanning electron microscopy/X-ray microanalysis. The dispersion measured by XRD was not appreciably altered by the treatments, but the TPD showed more hydrogen desorbed above 150/sup 0/C from nickel on the treated supports. The activation of nickel by pretreatment of the support was ascribed to the increase of those nickel atoms which dispersed finely over the support by the increased number of surface hydroxyl groups. This was based on the number of hydroxyl groups per unit surface area. The nickel catalyst supported on the pretreated silicas showed greater thermal stability. 16 references, 5 figures, 1 table.

  5. Porous glass with high silica content for nuclear waste storage : preparation, characterization and leaching

    International Nuclear Information System (INIS)

    Aegerter, M.A.; Santos, D.I. dos; Ventura, P.C.S.

    1984-01-01

    Aqueous solutions simulating radioactive nuclear wastes (like Savanah River Laboratory) were incorporated in porous glass matrix with high silica content prepared by decomposition of borosilicate glass like Na 2 O - B 2 O 3 - SiO 2 . After sintering, the samples were submitted, during 28 days, to standard leaching tests MCC1, MCC5 (Soxhlet) and stagnating. The total weight loss, ph, as well as the integral and differential leaching rates and the accumulated concentrations in the leach of Si, Na, B, Ca, Mn, Al, Fe and Ni. The results are compared with the results from reference borosilicate glass, made by fusion, ceramic, synroc, concrets, etc... (E.G.) [pt

  6. Enhanced Thermal Properties of Novel Latent Heat Thermal Storage Material Through Confinement of Stearic Acid in Meso-Structured Onion-Like Silica

    Science.gov (United States)

    Gao, Junkai; Lv, Mengjiao; Lu, Jinshu; Chen, Yan; Zhang, Zijun; Zhang, Xiongjie; Zhu, Yingying

    2017-12-01

    Meso-structured onion-like silica (MOS), which had a highly ordered, onion-like multilayer; large surface area and pore volume; and highly curved mesopores, were synthesized as a support for stearic acid (SA) to develop a novel shape-stabilized phase change material (SA/MOS). The characterizations of SA/MOS were studied by the analysis technique of scanning electron microscope, infrared spectroscopy, x-ray diffraction, differential scanning calorimeter (DSC), and thermal gravimetry analysis (TGA). The results showed that the interaction between the SA and the MOS was physical adsorption and that the MOS had no effect on the crystal structure of the SA. The DSC results suggested that the melting and solidifying temperature of the SA/MOS were 72.7°C and 63.9°C with a melting latent heat of 108.0 J/g and a solidifying latent heat of 126.0 J/g, respectively, and the TGA results indicated that the SA/MOS had a good thermal stability. All of the results demonstrated that the SA/MOS was a promising thermal energy storage material candidate for practical applications.

  7. Construction and evaluation of controlled-release delivery system of Abamectin using porous silica nanoparticles as carriers.

    Science.gov (United States)

    Wang, Yan; Cui, Haixin; Sun, Changjiao; Zhao, Xiang; Cui, Bo

    2014-12-01

    Photolysis and poor solubility in water of Abamectin are key issues to be addressed, which causes low bioavailability and residual pollution. In this study, a novel hydrophilic delivery system through loading Abamectin with porous silica nanoparticles (Abam-PSNs) was developed in order to improve the chemical stability, dispersity, and the controlled release of Abamectin. These results suggest that Abam-PSNs can significantly improve the performance of controllable release, photostability, and water solubility of Abamectin by changing the porous structure of silica nanoparticles, which is favorable to improve the bioavailability and reduce the residues of pesticides.

  8. Two-Stage Crystallizer Design for High Loading of Poorly Water-Soluble Pharmaceuticals in Porous Silica Matrices

    Directory of Open Access Journals (Sweden)

    Leia Dwyer

    2017-05-01

    Full Text Available While porous silica supports have been previously studied as carriers for nanocrystalline forms of poorly water-soluble active pharmaceutical ingredients (APIs, increasing the loading of API in these matrices is of great importance if these carriers are to be used in drug formulations. A dual-stage mixed-suspension, mixed-product removal (MSMPR crystallizer was designed in which the poorly soluble API fenofibrate was loaded into the porous matrices of pore sizes 35 nm–300 nm in the first stage, and then fed to a second stage in which the crystals were further grown in the pores. This resulted in high loadings of over 50 wt % while still producing nanocrystals confined to the pores without the formation of bulk-sized crystals on the surface of the porous silica. The principle was extended to another highly insoluble API, griseofulvin, to improve its loading in porous silica in a benchtop procedure. This work demonstrates a multi-step crystallization principle API in porous silica matrices with loadings high enough to produce final dosage forms of these poorly water-soluble APIs.

  9. TiO2-Impregnated Porous Silica Tube and Its Application for Compact Air- and Water-Purification Units

    Directory of Open Access Journals (Sweden)

    Tsuyoshi Ochiai

    2015-09-01

    Full Text Available A simple, convenient, reusable, and inexpensive air- and water-purification unit including a one-end sealed porous amorphous-silica (a-silica tube coated with TiO2 photocatalyst layers has been developed. The porous a-silica layers were formed through outside vapor deposition (OVD. TiO2 photocatalyst layers were formed through impregnation and calcination onto a-silica layers. The resulting porous TiO2-impregnated a-silica tubes were evaluated for air-purification capacity using an acetaldehyde gas decomposition test. The tube (8.5 mm e.d. × 150 mm demonstrated a 93% removal rate for high concentrations (ca. 300 ppm of acetaldehyde gas at a single-pass condition with a 250 mL/min flow rate under UV irradiation. The tube also demonstrated a water purification capacity at a rate 2.0 times higher than a-silica tube without TiO2 impregnation. Therefore, the tubes have a great potential for developing compact and in-line VOC removal and water-purification units.

  10. One pot synthesized Li, Zr doped porous silica nanoparticle for low temperature CO2 adsorption

    Directory of Open Access Journals (Sweden)

    Mani Ganesh

    2017-05-01

    Full Text Available Li, Zr doped porous silica was synthesized in one pot and investigated for low temperature CO2 adsorption. The synthesized nanoparticle was characterized by X-ray diffraction (XRD, N2 adsorption–desorption measurement, thermogravimetric analysis (TGA and scanning electron microscopy (SEM. The specific surface area, average pore diameter and pore volume were determined to be 962 m2/g, 2.3 nm and 0.56 cm3/g respectively. ICP-AES analysis revealed a metal content of 4 wt.% (Zr and 3.42 wt.% (Li. Their CO2 adsorption capacity was tested at room temperature and atmospheric pressure. An uptake of about 5 wt.% was observed and regenerable at a low temperature of 200 °C. This adsorption and desorption temperature of the sorbent is lower than the reported lithium silicate. The CO2 adsorption–desorption cyclic performance studies illustrated that Li, Zr doped porous silica is a recyclable, selective and potential sorbent for CO2 adsorption.

  11. SiO2-TiO2-P2O5 meso porous coatings for proton exchange membranes fuel cells

    International Nuclear Information System (INIS)

    Castro, Y.; Mosa, J.; Duran, A.

    2014-01-01

    The article describes the preparation of meso porous SiO 2 -TiO 2 -P 2 O 5 coatings by Sol-Gel process combined to EISA method for using as proton exchange membranes fuel cells. Tetraethyl orthosilicate (TEOS), methyl triethoxysilane (MTES), titanium tetrachloride (TiCl 4 ) and phosphorus trichloride (PCl 3 ) have used as precursors and cetyl trimethylammonium bromide (CTAB) as porous generator agent. Films were deposited by immersion technique controlling the relative humidity at 40 and 20-70% and treated at 400 to 500 degree centigrade for 15, 30, 45 and 60 min. The variation of the refractive index and thickness have studied as a function of temperature and sintering time as well as the pore volume and density of the coatings by spectroscopic ellipsometry. Moreover, the hydrophobic/hydrophilic character of the coatings has been studied by Transform Infrared Spectroscopy (FTIR) and by contact angle measurements, following the loss of methyl groups with the temperature and sintering time. The results show that these parameters are crucial to obtain coatings with high porosity and low contact angle, important to obtain high proton conductivity conditions. The sintering conditions were fixed to 400 degree centigrade/60 min. Conductivity measurements at four points show high proton conductivity, 0,16 and 0,85 S/cm, up and down ramp, respectively, at 80 degree centigrade and 80 % of humidity. These coatings are good candidates for PEMFC membranes, if they are deposited onto electrodes. (Author)

  12. Two-Stage Crystallizer Design for High Loading of Poorly Water-Soluble Pharmaceuticals in Porous Silica Matrices

    OpenAIRE

    Leia Dwyer; Samir Kulkarni; Luzdary Ruelas; Allan Myerson

    2017-01-01

    While porous silica supports have been previously studied as carriers for nanocrystalline forms of poorly water-soluble active pharmaceutical ingredients (APIs), increasing the loading of API in these matrices is of great importance if these carriers are to be used in drug formulations. A dual-stage mixed-suspension, mixed-product removal (MSMPR) crystallizer was designed in which the poorly soluble API fenofibrate was loaded into the porous matrices of pore sizes 35 nm-300 nm in the first st...

  13. Phase equilibria and thermodynamic modeling of ethane and propane hydrates in porous silica gels.

    Science.gov (United States)

    Seo, Yongwon; Lee, Seungmin; Cha, Inuk; Lee, Ju Dong; Lee, Huen

    2009-04-23

    In the present study, we examined the active role of porous silica gels when used as natural gas storage and transportation media. We adopted the dispersed water in silica gel pores to substantially enhance active surface for contacting and encaging gas molecules. We measured the three-phase hydrate (H)-water-rich liquid (L(W))-vapor (V) equilibria of C(2)H(6) and C(3)H(8) hydrates in 6.0, 15.0, 30.0, and 100.0 nm silica gel pores to investigate the effect of geometrical constraints on gas hydrate phase equilibria. At specified temperatures, the hydrate stability region is shifted to a higher pressure region depending on pore size when compared with those of bulk hydrates. Through application of the Gibbs-Thomson relationship to the experimental data, we determined the values for the C(2)H(6) hydrate-water and C(3)H(8) hydrate-water interfacial tensions to be 39 +/- 2 and 45 +/- 1 mJ/m(2), respectively. By using these values, the calculation values were in good agreement with the experimental ones. The overall results given in this study could also be quite useful in various fields, such as exploitation of natural gas hydrate in marine sediments and sequestration of carbon dioxide into the deep ocean.

  14. Reactive silica transport in fractured porous media: Analytical solutions for a system of parallel fractures

    Science.gov (United States)

    Yang, Jianwen

    2012-04-01

    A general analytical solution is derived by using the Laplace transformation to describe transient reactive silica transport in a conceptualized 2-D system involving a set of parallel fractures embedded in an impermeable host rock matrix, taking into account of hydrodynamic dispersion and advection of silica transport along the fractures, molecular diffusion from each fracture to the intervening rock matrix, and dissolution of quartz. A special analytical solution is also developed by ignoring the longitudinal hydrodynamic dispersion term but remaining other conditions the same. The general and special solutions are in the form of a double infinite integral and a single infinite integral, respectively, and can be evaluated using Gauss-Legendre quadrature technique. A simple criterion is developed to determine under what conditions the general analytical solution can be approximated by the special analytical solution. It is proved analytically that the general solution always lags behind the special solution, unless a dimensionless parameter is less than a critical value. Several illustrative calculations are undertaken to demonstrate the effect of fracture spacing, fracture aperture and fluid flow rate on silica transport. The analytical solutions developed here can serve as a benchmark to validate numerical models that simulate reactive mass transport in fractured porous media.

  15. Transport of Silica Colloid through Saturated Porous Media under Different Hydrogeochemical and Hydrodynamic Conditions Considering Managed Aquifer Recharge

    Directory of Open Access Journals (Sweden)

    Zhuo Wang

    2016-11-01

    Full Text Available Colloids may have an important role in regulating the structure and function of groundwater ecosystems, and may influence the migration of low solubility contaminants in groundwater. There is, however, a degree of uncertainty about how colloids behave under the variable hydrogeochemical and hydrodynamic conditions that occur during managed aquifer recharge. We used an online monitoring system to monitor the transport of silica colloid in saturated porous media under different hydrogeochemical conditions, including a range of pH values (5, 7, and 9, ionic strengths (<0.0005, 0.02, and 0.05 M, cation valences (Na+, Ca2+, flow rates (0.1, 0.2, and 0.4 mL/min. The results showed that silica colloid was more likely to deposit on the surface of porous media in acidic conditions (pH = 5 than in alkaline conditions (pH = 9, indicating that the risks of pollution from colloidal interactions would be higher when the pH of the recharge water was higher. Colloid deposition occurred when the ionic strength of the colloidal suspension increased, and bivalent cations had a greater effect than monovalent cations. This suggests that bivalent cation-rich recharge water might affect the porosity of the porous medium because of colloid deposition during the managed aquifer recharge process. As the flow rate increased, the migration ability of silica colloid increased. We simulated the migration of silica colloid in porous media with the COMSOL Multiphysics model.

  16. Nanoparticles of Pt and Ag supported in meso porous SiO{sub 2}: characterization and catalytic applications; Nanoparticulas de Pt y Ag soportadas en SiO{sub 2} mesoporosa: caracterizacion y aplicaciones cataliticas

    Energy Technology Data Exchange (ETDEWEB)

    Espinosa, M.E.; Perez H, R.; Perez A, M.; Mondragon G, G. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico); Arenas A, J. [IFUNAM, A.P. 20-364, 01000 Mexico D.F. (Mexico)

    2004-07-01

    The surface properties of catalysts of Pt and Ag supported in conventional SiO{sub 2} hey have been studied through reduction reactions of N{sub 2}O with H{sub 2} which is a sensitive reaction to the structure. In our case it was used a meso porous ceramic support of SiO{sub 2} of great surface area (1100 m{sup 2}/gr), where it is caused a high dispersion of the metallic nanoparticles of Pt and Ag, the total charge of the active phase in the meso porous support was of 3% in weight. The catalysts show a variation in the percentages of conversion of N{sub 2}O depending on the size and dispersion of the metallic phases. (Author)

  17. Biogenic porous silica and silicon sourced from Mexican Giant Horsetail (Equisetum myriochaetum) and their application as supports for enzyme immobilization.

    Science.gov (United States)

    Sola-Rabada, Anna; Sahare, Padma; Hickman, Graham J; Vasquez, Marco; Canham, Leigh T; Perry, Carole C; Agarwal, Vivechana

    2018-06-01

    Porous silica-based materials are attractive for biomedical applications due to their biocompatibility and biodegradable character. In addition, inorganic supports such as porous silicon are being developed due to integrated circuit chip compatibility and tunable properties leading to a wide range of multidisciplinary applications. In this contribution, biosilica extracted from a rarely studied plant material (Equisetum Myriochaetum), its conversion to silicon and the potential for both materials to be used as supports for enzyme immobilization are investigated. E. myriochaetum was subject to conventional acid digestion to extract biogenic silica with a% yield remarkably higher (up to 3 times) than for other Equisetum sp. (i.e. E. Arvense). The surface area of the isolated silica was ∼400 m 2 /g, suitable for biotechnological applications. Biogenic silicon was obtained by magnesiothermic reduction. The materials were characterized by SEM-EDX, XRD, FT-IR, ICP-OES, TGA and BET analysis and did not contain significant levels of class 1 heavy elements (such as Pb, Cd, Hg and As). Two commercial peroxidases, horseradish peroxidase (HRP) and Coprinus cinereus peroxidase (CiP) were immobilized onto the biogenic materials using three different functionalization routes: (A) carbodiimide, (B) amine + glutaraldehyde and (C) amine + carbodiimide. Although both biogenic silica and porous silicon could be used as supports differences in behaviour were observed for the two enzymes. For HRP, loading onto biogenic silica via the glutaraldehyde immobilization technique (route B) was most effective. The loading of CiP showed a much higher peroxidase activity onto porous silicon than silica functionalized by the carbodiimide method (route A). From the properties of the extracted materials obtained from Equisetum Myriochaetum and the immobilization results observed, these materials appear to be promising for industrial and biomedical applications. Copyright © 2018 Elsevier

  18. Activity Tests of Macro-Meso Porous Catalysts over Metal Foam Plate for Steam Reforming of Bio-Ethanol.

    Science.gov (United States)

    Park, No-Kuk; Jeong, Yong Han; Kang, Misook; Lee, Tae Jin

    2018-09-01

    The catalytic activity of a macro-mesoporous catalyst coated on a metal foam plate in the reforming of bio-ethanol to synthesis gas was investigated. The catalysts were prepared by coating a support with a noble metal and transition metal. The catalytic activity for the production of synthetic gas by the reforming of bio-ethanol was compared according to the support material, reaction temperature, and steam/carbon ratio. The catalysts coated on the metal foams were prepared using a template method, in which macro-pores and meso-pores were formed by mixing polymer beads. In particular, the thermodynamic equilibrium composition of bio-ethanol reforming with the reaction temperature and steam/carbon ratio to produce synthetic gas was examined using the HSC (Enthalpy-Entropy-Heat capacity) chemistry program in this study. The composition of hydrogen and carbon monoxide in the reformate gas produced by steam reforming over the Rh/Ni-Ce-Zr/Al2O3-based pellet type catalysts and metal foam catalysts that had been coated with the Rh/Al-Ce-Zr-based catalysts was investigated by experimental activity tests. The activity of the metal foam catalyst was higher than that of the pellet type catalyst.

  19. Titanium dioxide encapsulation of supported Ag nanoparticles on the porous silica bead for increased photocatalytic activity

    Science.gov (United States)

    Liu, Hui; Deng, Lu; Sun, Chaochao; Li, Junqi; Zhu, Zhenfeng

    2015-01-01

    A new synthetic strategy has been developed to encapsulate Ag nanoparticles in heterogeneous catalysts to prevent their dropping and sintering. Ag nanoparticles with diameters about 5-10 nm were first supported on the porous silica bead. These were then covered with a fresh layer of titanium dioxide with the thickness about 5 nm. SEM and TEM images were used to confirm the success of each synthesis step, and the photocatalytic activity of the as-synthesized samples was evaluated by photocatalytic decolorization of Rhodamine B (Rh B) aqueous solution at ambient temperature under both UV and visible light irradiation. The resulting titanium dioxide encapsulated Ag nanoparticles exhibited an enhanced photocatalytic activity under both UV and visible light irradiation, this can be attributed to effective charge separation and light harvesting of the plasmonic silver nanoparticles decoration, even the reducing of the exciton recombination rate caused by the small grain size of anatase TiO2 nanocrystals.

  20. Poly(NIPAM-co-MPS-grafted multimodal porous silica nanoparticles as reverse thermoresponsive drug delivery system

    Directory of Open Access Journals (Sweden)

    Sushilkumar A. Jadhav

    2017-05-01

    Full Text Available Hybrid drug delivery systems (DDS have been prepared by grafting poly(NIPAM-co-MPS chains on multimodal porous silica nanoparticles having an inner mesoporous structure and an outer thin layer of micropores. The hybrid thermoresponsive DDS were fully characterized and loaded with a model drug. The in vitro drug release tests are carried out at below and above the lower critical solution temperature (LCST of the copolymer. The results have revealed that due to the presence of small diameter (~1.3 nm micropores at the periphery of the particles, the collapsed globules of the thermoresponsive copolymer above its LCST hinders the complete release of the drug which resulted in a reverse thermoresponsive drug release profile by the hybrid DDS.

  1. Impact of physicochemical properties of porous silica materials conjugated with dexamethasone via pH-responsive hydrazone bond on drug loading and release behavior

    Science.gov (United States)

    Numpilai, Thanapha; Witoon, Thongthai; Chareonpanich, Metta; Limtrakul, Jumras

    2017-02-01

    The conjugation of dexamethasone (DEX) onto modified-porous silica materials via a pH-responsive hydrazone bond has been reported to be highly efficient method to specifically deliver the DEX to diseased sites. However, the influence of physicochemical properties of porous silica materials has not yet been fully understood. In this paper, the impact of pore sizes, particle sizes and silanol contents on surface functionalization, drug loading and release behavior of porous silica materials conjugated with dexamethasone via pH-responsive hydrazone bond was investigated. The grafting density was found to relate to the number of silanol groups on the surface of porous silica materials. The particle size and macropores of the porous silica materials played an vital role on the drug loading and release behavior. Although the porous silica materials with larger particle sizes possessed a lower grafting density, a larger amount of drug loading could be achieved. Moreover, the porous silica materials with larger particle sizes showed a slower release rate of DEX due to a longer distance for cleaved DEX diffusion out of pores. DEX release rate exhibited pH-dependent, sustained release. At pH 4.5, the amount of DEX release within 10 days could be controlled in the range of 12.74-36.41%, depending on the host material. Meanwhile, less than 1.5% of DEX was released from each of type of the porous silica materials at pH 7.4. The results of silica dissolution suggested that the degradation of silica matrix did not significantly affect the release rate of DEX. In addition, the kinetic modeling studies revealed that the DEX releases followed Korsmeyer-Peppas model with a release exponent (n) ranged from 0.3 to 0.47, indicating a diffusion-controlled release mechanism.

  2. Effect of Pore Size on the Carbon Dioxide Adsorption Behavior of Porous Liquids Based on Hollow Silica.

    Science.gov (United States)

    Shi, Ting; Zheng, Yaping; Wang, Tianyu; Li, Peipei; Wang, Yudeng; Yao, Dongdong

    2018-01-05

    Porous liquids are an expanding class of material that has huge potential in gas separation and gas adsorption. Pore size has a dramatic influence on the gas adsorption of porous liquids. In this article, we chose hollow silica nanoparticles as cores, 3-(trihydroxysilyl)-1-propanesulfonic acid (SIT) as corona, and inexpensive industrial reagent polyether amine (M2070) as canopy to obtain a new type of porous liquids. Hollow silica nanospheres with different pore sizes were chosen to investigate the influence of porosity size on CO 2 adsorption capacity of porous liquids. Their chemical structure, morphology, thermal behavior and possible adsorption mechanism are discussed in detail. It was proved that with similar grafting density, porous liquid that has bigger pore size possesses a better CO 2 adsorption capacity (2.182 mmol g -1 under 2.5 MPa at 298 K). More than that, this article demonstrates a more facile and low-cost method to obtain porous liquids with good CO 2 adsorption capacity, recyclability, and huge variability. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Mannose-functionalized porous silica-coated magnetic nanoparticles for two-photon imaging or PDT of cancer cells

    International Nuclear Information System (INIS)

    Perrier, Marine; Gary-Bobo, Magali; Lartigue, Lenaïc; Brevet, David; Morère, Alain; Garcia, Marcel; Maillard, Philippe; Raehm, Laurence; Guari, Yannick; Larionova, Joulia; Durand, Jean-Olivier; Mongin, Olivier; Blanchard-Desce, Mireille

    2013-01-01

    An original fluorophore engineered for two-photon excitation or a porphyrin derivative were entrapped in the silica shell of magnetic porous silica nanoparticles during the synthesis of the silica moiety without damaging the structure of the organic part. The mild conditions involved allowed obtaining microporous or mesoporous silica magnetic nanoparticles, respectively. Mannose was grafted on the surface of the nanoparticles to target MCF-7 breast cancer cells. The studies of magnetic properties of these hybrid nanoparticles show that they present a blocking temperature at 190 K. The nano-objects designed with the two-photon fluorophore were efficient for two-photon imaging of MCF-7 cancer cells, whereas the nano-objects with the photosensitizer efficiently killed cancer cells. The presence of the mannose moiety was demonstrated to improve both imaging and therapy properties.

  4. Mannose-functionalized porous silica-coated magnetic nanoparticles for two-photon imaging or PDT of cancer cells

    Energy Technology Data Exchange (ETDEWEB)

    Perrier, Marine [UMR 5253 CNRS-UM2-ENSCM-UM1, Institut Charles Gerhardt Montpellier (France); Gary-Bobo, Magali [Faculte de Pharmacie, Universite Montpellier 1, Universite Montpellier 2, Institut des Biomolecules Max Mousseron UMR 5247 CNRS (France); Lartigue, Lenaiec; Brevet, David [UMR 5253 CNRS-UM2-ENSCM-UM1, Institut Charles Gerhardt Montpellier (France); Morere, Alain; Garcia, Marcel [Faculte de Pharmacie, Universite Montpellier 1, Universite Montpellier 2, Institut des Biomolecules Max Mousseron UMR 5247 CNRS (France); Maillard, Philippe [Universite Paris-Sud, UMR 176 CNRS, Institut Curie (France); Raehm, Laurence; Guari, Yannick, E-mail: yannick.guari@um2.fr; Larionova, Joulia; Durand, Jean-Olivier, E-mail: durand@univ-montp2.fr [UMR 5253 CNRS-UM2-ENSCM-UM1, Institut Charles Gerhardt Montpellier (France); Mongin, Olivier [Universite de Rennes 1, Institut des Sciences Chimiques de Rennes, CNRS UMR 6226 (France); Blanchard-Desce, Mireille [Universite Bordeaux, Institut des Sciences Moleculaires, UMR CNRS 5255 (France)

    2013-05-15

    An original fluorophore engineered for two-photon excitation or a porphyrin derivative were entrapped in the silica shell of magnetic porous silica nanoparticles during the synthesis of the silica moiety without damaging the structure of the organic part. The mild conditions involved allowed obtaining microporous or mesoporous silica magnetic nanoparticles, respectively. Mannose was grafted on the surface of the nanoparticles to target MCF-7 breast cancer cells. The studies of magnetic properties of these hybrid nanoparticles show that they present a blocking temperature at 190 K. The nano-objects designed with the two-photon fluorophore were efficient for two-photon imaging of MCF-7 cancer cells, whereas the nano-objects with the photosensitizer efficiently killed cancer cells. The presence of the mannose moiety was demonstrated to improve both imaging and therapy properties.

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

    International Nuclear Information System (INIS)

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

    2015-01-01

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

  6. Hierarchical meso/macro-porous carbon fabricated from dual MgO templates for direct electron transfer enzymatic electrodes

    Science.gov (United States)

    Funabashi, Hiroto; Takeuchi, Satoshi; Tsujimura, Seiya

    2017-03-01

    We designed a three-dimensional (3D) hierarchical pore structure to improve the current production efficiency and stability of direct electron transfer-type biocathodes. The 3D hierarchical electrode structure was fabricated using a MgO-templated porous carbon framework produced from two MgO templates with sizes of 40 and 150 nm. The results revealed that the optimal pore composition for a bilirubin oxidase-catalysed oxygen reduction cathode was a mixture of 33% macropores and 67% mesopores (MgOC33). The macropores improve mass transfer inside the carbon material, and the mesopores improve the electron transfer efficiency of the enzyme by surrounding the enzyme with carbon.

  7. Meso-porous α-Fe2O3 thin films synthesized via the sol-gel process for light-driven water oxidation

    International Nuclear Information System (INIS)

    Hamd, Wael; Laberty-Robert, Christel; Sanchez, Clement; Cobo, Saioa; Fize, Jennifer; Artero, Vincent; Baldinozzi, Gianguido; Schwartz, Wilfrid; Reymermier, Maryse; Pereira, Alexandre; Fontecave, Marc

    2012-01-01

    This work reports a facile and cost-effective method for synthesizing photoactive α-Fe 2 O 3 films as well as their performances when used as photoanodes for water oxidation. Transparent α-Fe 2 O 3 meso-porous films were fabricated by template-directed sol-gel chemistry coupled with the dip-coating approach, followed by annealing at various temperatures from 350 degrees C to 750 degrees C in air. α-Fe 2 O 3 films were characterized by X-ray diffraction, XPS, FE-SEM and electrochemical measurements. The photoelectrochemical performance of α-Fe 2 O 3 photoanodes was characterized and optimized through the deposition of Co-based co-catalysts via different methods (impregnation, electro-deposition and photo-electro-deposition). Interestingly, the resulting hematite films heat-treated at relatively low temperature (500 degrees C), and therefore devoid of any extrinsic dopant, achieve light-driven water oxidation under near-to-neutral (pH = 8) aqueous conditions after decoration with a Co catalyst. The onset potential is 0.75 V vs. the reversible hydrogen electrode (RHE), thus corresponding to 450 mV light-induced under potential, although modest photocurrent density values (40 μAcm -2 ) are obtained below 1.23 V vs. RHE. These new materials with a very large interfacial area in contact with the electrolyte and allowing for a high loading of water oxidation catalysts open new avenues for the optimization of photo-electrochemical water splitting. (authors)

  8. In situ growth of hollow gold-silver nanoshells within porous silica offers tunable plasmonic extinctions and enhanced colloidal stability.

    Science.gov (United States)

    Li, Chien-Hung; Jamison, Andrew C; Rittikulsittichai, Supparesk; Lee, Tai-Chou; Lee, T Randall

    2014-11-26

    Porous silica-coated hollow gold-silver nanoshells were successfully synthesized utilizing a procedure where the porous silica shell was produced prior to the transformation of the metallic core, providing enhanced control over the structure/composition of the bimetallic hollow core. By varying the reaction time and the precise amount of gold salt solution added to a porous silica-coated silver-core template solution, composite nanoparticles were tailored to reveal a readily tunable surface plasmon resonance that could be centered across the visible and near-IR spectral regions (∼445-800 nm). Characterization by X-ray photoelectron spectroscopy, energy-dispersive X-ray spectroscopy, scanning electron microscopy, and transmission electron microscopy revealed that the synthetic methodology afforded particles having uniform composition, size, and shape. The optical properties were evaluated by absorption/extinction spectroscopy. The stability of colloidal solutions of our composite nanoparticles as a function of pH was also investigated, revealing that the nanoshells remain intact over a wide range of conditions (i.e., pH 2-10). The facile tunability, enhanced stability, and relatively small diameter of these composite particles (∼110 nm) makes them promising candidates for use in tumor ablation or as photothermal drug-delivery agents.

  9. IR-spectroscopical investigations on the glass structure of porous and sintered compacts of colloidal silica gels

    Science.gov (United States)

    Clasen, Rolf; Hornfeck, M.; Theiss, Wolfgang

    1991-08-01

    The forming and sintering of fumed silica powders is an interesting route for the preparation of large, very pure or doped silica glasses with a precise geometry. The processing from the shaping of a porous compact to the sintering of transparent silica glass can be successfully investigated with optical spectroscopy. As only the dielectric function DF (a dielectric function is the square root of the complex refractive index) characterizes the material, the vibrational bands were calculated from reflectance measurements. In compacts of fine particles, the topology cannot be neglected. Therefore, the models describing topological effects are briefly reviewed. With these model calculations it could be proven that new bands in the compacts and the significant shifts in the reflectance spectra during sintering are mainly caused by topological effects and that changes in the glass structure play only a secondary role.

  10. TiO2 supported over porous silica photocatalysts for pesticide degradation using solar light: Part 2. Silica prepared using acrylic acid emulsion

    International Nuclear Information System (INIS)

    Phanikrishna Sharma, Mangalampalli V.; Durga Kumari, Valluri; Subrahmanyam, Machiraju

    2010-01-01

    An acrylic acid emulsion mixture is used for synthesis of novel porous silica (E-Si) material. The photocatalytic activity of TiO 2 under solar light irradiation for isoproturon (herbicide) degradation is drastically increased when dispersed over E-Si support using solid state dispersion (SSD) technique. The composite material is characterized by XRD, nitrogen adsorption-desorption isotherms, UV-vis DRS, SEM and TEM measurements. The photocatalytic activities of the composite catalysts are evaluated for different parameters. The 5 wt% TiO 2 /E-Si is found to be highly active for isoproturon degradation.

  11. TiO{sub 2} supported over porous silica photocatalysts for pesticide degradation using solar light: Part 2. Silica prepared using acrylic acid emulsion

    Energy Technology Data Exchange (ETDEWEB)

    Phanikrishna Sharma, Mangalampalli V.; Durga Kumari, Valluri [Inorganic and Physical Chemistry Division, Indian Institute of Chemical Technology, Tarnaka, Hyderabad 500607, Andhra Pradesh (India); Subrahmanyam, Machiraju, E-mail: subrahmanyam@iict.res.in [Inorganic and Physical Chemistry Division, Indian Institute of Chemical Technology, Tarnaka, Hyderabad 500607, Andhra Pradesh (India)

    2010-03-15

    An acrylic acid emulsion mixture is used for synthesis of novel porous silica (E-Si) material. The photocatalytic activity of TiO{sub 2} under solar light irradiation for isoproturon (herbicide) degradation is drastically increased when dispersed over E-Si support using solid state dispersion (SSD) technique. The composite material is characterized by XRD, nitrogen adsorption-desorption isotherms, UV-vis DRS, SEM and TEM measurements. The photocatalytic activities of the composite catalysts are evaluated for different parameters. The 5 wt% TiO{sub 2}/E-Si is found to be highly active for isoproturon degradation.

  12. Titanium dioxide encapsulation of supported Ag nanoparticles on the porous silica bead for increased photocatalytic activity

    International Nuclear Information System (INIS)

    Liu, Hui; Deng, Lu; Sun, Chaochao; Li, Junqi; Zhu, Zhenfeng

    2015-01-01

    Graphical abstract: - Highlights: • A novel Ag-loading and TiO 2 -coating technique was used to prepare samples. • The photocatalytic activity of the product was evaluated by removing of Rh B. • The as-synthesized samples showed an excellent photocatalytic activity. - Abstract: A new synthetic strategy has been developed to encapsulate Ag nanoparticles in heterogeneous catalysts to prevent their dropping and sintering. Ag nanoparticles with diameters about 5–10 nm were first supported on the porous silica bead. These were then covered with a fresh layer of titanium dioxide with the thickness about 5 nm. SEM and TEM images were used to confirm the success of each synthesis step, and the photocatalytic activity of the as-synthesized samples was evaluated by photocatalytic decolorization of Rhodamine B (Rh B) aqueous solution at ambient temperature under both UV and visible light irradiation. The resulting titanium dioxide encapsulated Ag nanoparticles exhibited an enhanced photocatalytic activity under both UV and visible light irradiation, this can be attributed to effective charge separation and light harvesting of the plasmonic silver nanoparticles decoration, even the reducing of the exciton recombination rate caused by the small grain size of anatase TiO 2 nanocrystals

  13. Organoclay hybrid materials as precursors of porous ZnO/silica-clay heterostructures for photocatalytic applications

    Directory of Open Access Journals (Sweden)

    Marwa Akkari

    2016-12-01

    Full Text Available In this study, ZnO/SiO2-clay heterostructures were successfully synthesized by a facile two-step process applied to two types of clays: montmorillonite layered silicate and sepiolite microfibrous clay mineral. In the first step, intermediate silica–organoclay hybrid heterostructures were prepared following a colloidal route based on the controlled hydrolysis of tetramethoxysilane in the presence of the starting organoclay. Later on, pre-formed ZnO nanoparticles (NP dispersed in 2-propanol were incorporated under ultrasound irradiation to the silica–organoclay hybrid heterostructures dispersed in 2-propanol, and finally, the resulting solids were calcinated to eliminate the organic matter and to produce ZnO nanoparticles (NP homogeneously assembled to the clay–SiO2 framework. In the case of montmorillonite the resulting materials were identified as delaminated clays of ZnO/SiO2-clay composition, whereas for sepiolite, the resulting heterostructure is constituted by the assembling of ZnO NP to the sepiolite–silica substrate only affecting the external surface of the clay. The structural and morphological features of the prepared heterostructures were characterized by diverse physico-chemical techniques (such as XRD, FTIR, TEM, FE-SEM. The efficiency of these new porous ZnO/SiO2-clay heterostructures as potential photocatalysts in the degradation of organic dyes and the removal of pharmaceutical drugs in water solution was tested using methylene blue and ibuprofen compounds, respectively, as model of pollutants.

  14. In Situ Loading of Basic Fibroblast Growth Factor Within Porous Silica Nanoparticles for a Prolonged Release

    Directory of Open Access Journals (Sweden)

    Postovit Lynne-Marie

    2009-01-01

    Full Text Available Abstract Basic fibroblast growth factor (bFGF, a protein, plays a key role in wound healing and blood vessel regeneration. However, bFGF is easily degraded in biologic systems. Mesoporous silica nanoparticles (MSNs with well-tailored porous structure have been used for hosting guest molecules for drug delivery. Here, we report an in situ route to load bFGF in MSNs for a prolonged release. The average diameter (d of bFGF-loaded MSNs is 57 ± 8 nm produced by a water-in-oil microemulsion method. The in vitro releasing profile of bFGF from MSNs in phosphate buffer saline has been monitored for 20 days through a colorimetric enzyme linked immunosorbent assay. The loading efficiency of bFGF in MSNs is estimated at 72.5 ± 3%. In addition, the cytotoxicity test indicates that the MSNs are not toxic, even at a concentration of 50 μg/mL. It is expected that the in situ loading method makes the MSNs a new delivery system to deliver protein drugs, e.g. growth factors, to help blood vessel regeneration and potentiate greater angiogenesis.

  15. Omega-3 PUFA concentration by a novel PVDF nano-composite membrane filled with nano-porous silica particles.

    Science.gov (United States)

    Ghasemian, Samaneh; Sahari, Mohammad Ali; Barzegar, Mohsen; Ahmadi Gavlighi, Hasan

    2017-09-01

    In this study, polyvinylidene fluoride (PVDF) and nano-porous silica particle were used to fabricate an asymmetric nano-composite membrane. Silica particles enhanced the thermal stability of PVDF/SiO 2 membranes; increasing the decomposition temperature from 371°C to 408°C. Cross sectional morphology showed that silica particles were dispersed in polymer matrix uniformly. However, particle agglomeration was found at higher loading of silica (i.e., 20 by weight%). The separation performance of nano-composite membranes was also evaluated using the omega-3 polyunsaturated fatty acids (PUFA) concentration at a temperature and pressure of 30°C and 4bar, respectively. Silica particle increased the omega-3PUFA concentration from 34.8 by weight% in neat PVDF to 53.9 by weight% in PVDF with 15 by weight% of silica. Moreover, PVDF/SiO 2 nano-composite membranes exhibited enhanced anti-fouling property compared to neat PVDF membrane. Fouling mechanism analysis revealed that complete pore blocking was the predominant mechanism occurring in oil filtration. The concentration of omega-3 polyunsaturated fatty acids (PUFA) is important in the oil industries. While the current methods demand high energy consumptions in concentrating the omega-3, membrane separation technology offers noticeable advantages in producing pure omega-3 PUFA. Moreover, concentrating omega-3 via membrane separation produces products in the triacylglycerol form which possess better oxidative stability. In this work, the detailed mechanisms of fouling which limits the performance of membrane separation were investigated. Incorporating silica particles to polymeric membrane resulted in the formation of mixed matrix membrane with improved anti-fouling behaviour compared to the neat polymeric membrane. Hence, the industrial potential of membrane processing to concentrate omega-3 fatty acids is enhanced. Copyright © 2017. Published by Elsevier Ltd.

  16. Core-shell designs of photoluminescent nanodiamonds with porous silica coatings for bioimaging and drug delivery II: application.

    Science.gov (United States)

    Prabhakar, Neeraj; Näreoja, Tuomas; von Haartman, Eva; Karaman, Didem Şen; Jiang, Hua; Koho, Sami; Dolenko, Tatiana A; Hänninen, Pekka E; Vlasov, Denis I; Ralchenko, Victor G; Hosomi, Satoru; Vlasov, Igor I; Sahlgren, Cecilia; Rosenholm, Jessica M

    2013-05-07

    Recent advances within materials science and its interdisciplinary applications in biomedicine have emphasized the potential of using a single multifunctional composite material for concurrent drug delivery and biomedical imaging. Here we present a novel composite material consisting of a photoluminescent nanodiamond (ND) core with a porous silica (SiO2) shell. This novel multifunctional probe serves as an alternative nanomaterial to address the existing problems with delivery and subsequent tracing of the particles. Whereas the unique optical properties of ND allows for long-term live cell imaging and tracking of cellular processes, mesoporous silica nanoparticles (MSNs) have proven to be efficient drug carriers. The advantages of both ND and MSNs were hereby integrated in the new composite material, ND@MSN. The optical properties provided by the ND core rendered the nanocomposite suitable for microscopy imaging in fluorescence and reflectance mode, as well as super-resolution microscopy as a STED label; whereas the porous silica coating provided efficient intracellular delivery capacity, especially in surface-functionalized form. This study serves as a demonstration how this novel nanomaterial can be exploited for both bioimaging and drug delivery for future theranostic applications.

  17. Study of water radiolysis in porous media

    International Nuclear Information System (INIS)

    Rotureau, Patricia

    2001-08-01

    The understanding of the production of H 2 in the radiolysis of water confined into pores of concrete is important for the disposal of radioactive waste. In order to describe the mechanisms of water radiolysis in such heterogeneous porous systems we have studied the behaviour under gamma radiation of water confined in porous silica glasses with pores going from 8 to 300 nm of diameter and meso-porous molecular sieves (MCM-41). The radiolytic yields of hydroxyl radicals, hydrated electron and dihydrogen, have been determined with respect to the pore size of materials. The increase of these radiolytic yields compared to those of free water allowed us to show a charge transfer from silica to confined water. On the other hand the kinetics of hydrated electron reactions measured by pulse radiolysis are not modified. (author) [fr

  18. Response to Extreme Temperatures of Mesoporous Silica MCM-41: Porous Structure Transformation Simulation and Modification of Gas Adsorption Properties.

    Science.gov (United States)

    Zhang, Shenli; Perez-Page, Maria; Guan, Kelly; Yu, Erick; Tringe, Joseph; Castro, Ricardo H R; Faller, Roland; Stroeve, Pieter

    2016-11-08

    Molecular dynamics (MD) and Monte Carlo (MC) simulations were applied together for the first time to reveal the porous structure transformation mechanisms of mesoporous silica MCM-41 subjected to temperatures up to 2885 K. Silica was experimentally characterized to inform the models and enable prediction of changes in gas adsorption/separation properties. MD simulations suggest that the pore closure process is activated by a collective diffusion of matrix atoms into the porous region, accompanied by bond reformation at the surface. Degradation is kinetically limited, such that complete pore closure is postponed at high heating rates. We experimentally observe decreased gas adsorption with increasing temperature in mesoporous silica heated at fixed rates, due to pore closure and structural degradation consistent with simulation predictions. Applying the Kissinger equation, we find a strong correlation between the simulated pore collapse temperatures and the experimental values which implies an activation energy of 416 ± 17 kJ/mol for pore closure. MC simulations give the adsorption and selectivity for thermally treated MCM-41, for N 2 , Ar, Kr, and Xe at room temperature within the 1-10 000 kPa pressure range. Relative to pristine MCM-41, we observe that increased surface roughness due to decreasing pore size amplifies the difference of the absolute adsorption amount differently for different adsorbate molecules. In particular, we find that adsorption of strongly interacting molecules can be enhanced in the low-pressure region while adsorption of weakly interacting molecules is inhibited. This then results in higher selectivity in binary mixture adsorption in mesoporous silica.

  19. Growth and physiological responses of maize (Zea mays L.) to porous silica nanoparticles in soil

    Energy Technology Data Exchange (ETDEWEB)

    Suriyaprabha, R.; Karunakaran, G.; Yuvakkumar, R.; Prabu, P.; Rajendran, V., E-mail: veerajendran@gmail.com [K. S. Rangasamy College of Technology, Centre for Nano Science and Technology (India); Kannan, N. [K. S. Rangasamy College of Arts and Science, Department of Biotechnology (India)

    2012-12-15

    The present study aims to explore the effect of high surface area (360.85 m{sup 2} g{sup -1}) silica nanoparticles (SNPs) (20-40 nm) extracted from rice husk on the physiological and anatomical changes during maize growth in sandy loam soil at four concentrations (5-20 kg ha{sup -1}) in comparison with bulk silica (15-20 kg ha{sup -1}). The plant responses to nano and bulk silica treatments were analyzed in terms of growth characteristics, phyto compounds such as total protein, chlorophyll, and other organic compounds (gas chromatography-mass spectroscopy), and silica accumulation (high-resolution scanning electron microscopy). Growth characteristics were much influenced with increasing concentration of SNPs up to 15 kg ha{sup -1} whereas at 20 kg ha{sup -1}, no significant increments were noticed. Silica accumulation in leaves was high at 10 and 15 kg ha{sup -1} (0.57 and 0.82 %) concentrations of SNPs. The observed physiological changes show that the expression of organic compounds such as proteins, chlorophyll, and phenols favored to maize treated with nanosilica especially at 15 kg ha{sup -1} compared with bulk silica and control. Nanoscale silica regimes at 15 kg ha{sup -1} has a positive response of maize than bulk silica which help to improve the sustainable farming of maize crop as an alternative source of silica fertilizer.

  20. Encapsulating Silica/Antimony into Porous Electrospun Carbon Nanofibers with Robust Structure Stability for High-Efficiency Lithium Storage.

    Science.gov (United States)

    Wang, Hongkang; Yang, Xuming; Wu, Qizhen; Zhang, Qiaobao; Chen, Huixin; Jing, Hongmei; Wang, Jinkai; Mi, Shao-Bo; Rogach, Andrey L; Niu, Chunming

    2018-04-24

    To address the volume-change-induced pulverization problems of electrode materials, we propose a "silica reinforcement" concept, following which silica-reinforced carbon nanofibers with encapsulated Sb nanoparticles (denoted as SiO 2 /Sb@CNFs) are fabricated via an electrospinning method. In this composite structure, insulating silica fillers not only reinforce the overall structure but also contribute to additional lithium storage capacity; encapsulation of Sb nanoparticles into the carbon-silica matrices efficiently buffers the volume changes during Li-Sb alloying-dealloying processes upon cycling and alleviates the mechanical stress; the porous carbon nanofiber framework allows for fast charge transfer and electrolyte diffusion. These advantageous characteristics synergistically contribute to the superior lithium storage performance of SiO 2 /Sb@CNF electrodes, which demonstrate excellent cycling stability and rate capability, delivering reversible discharge capacities of 700 mA h/g at 200 mA/g, 572 mA h/g at 500 mA/g, and 468 mA h/g at 1000 mA/g each after 400 cycles. Ex situ as well as in situ TEM measurements confirm that the structural integrity of silica-reinforced Sb@CNF electrodes can efficiently withstand the mechanical stress induced by the volume changes. Notably, the SiO 2 /Sb@CNF//LiCoO 2 full cell delivers high reversible capacities of ∼400 mA h/g after 800 cycles at 500 mA/g and ∼336 mA h/g after 500 cycles at 1000 mA/g.

  1. Electroless porous silicon formation applied to fabrication of boron-silica-glass cantilevers

    DEFF Research Database (Denmark)

    Teva, Jordi; Davis, Zachary James; Hansen, Ole

    2010-01-01

    This work describes the characterization and optimization of anisotropic formation of porous silicon in large volumes (0.5-1 mm3) of silicon by an electroless wet etching technique. The main goal is to use porous silicon as a sacrificial volume for bulk micromachining processes, especially in cases...... where etching of the full wafer thickness is needed. The porous silicon volume is formed by a metal-assisted etching in a wet chemical solution composed of hydrogen peroxide (30%), hydrofluoric acid (40%) and ethanol. This paper focuses on optimizing the etching conditions in terms of maximizing...... for bio-chemical sensors. The porous silicon volume is formed in an early step of the fabrication process, allowing easy handling of the wafer during all of the micromachining processes in the process flow. In the final process step, the porous silicon is quickly etched by immersing the wafer in a KOH...

  2. Impact of pore characteristics of silica materials on loading capacity and release behavior of ibuprofen

    Energy Technology Data Exchange (ETDEWEB)

    Numpilai, Thanapha [Department of Chemical Engineering, Faculty of Engineering, Kasetsart University, Bangkok 10900 (Thailand); Muenmee, Suthaporn [Department of Chemical Engineering, Faculty of Engineering, Kasetsart University, Bangkok 10900 (Thailand); Center for Advanced Studies in Nanotechnology and Its Applications in Chemical Food and Agricultural Industries, Kasetsart University, Bangkok 10900 (Thailand); Witoon, Thongthai, E-mail: fengttwi@ku.ac.th [Department of Chemical Engineering, Faculty of Engineering, Kasetsart University, Bangkok 10900 (Thailand); Center for Advanced Studies in Nanotechnology and Its Applications in Chemical Food and Agricultural Industries, Kasetsart University, Bangkok 10900 (Thailand); NANOTEC-KU-Center of Excellence on Nanoscale Materials Design for Green Nanotechnology, Kasetsart University, Bangkok 10900 (Thailand)

    2016-02-01

    Impact of pore characteristics of porous silica supports on loading capacity and release behavior of ibuprofen was investigated. The porous silica materials and ibuprofen-loaded porous silica materials were thoroughly characterized by N{sub 2}-sorption, thermal gravimetric and derivative weight analyses (TG-DTW), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), transmission electron microscope (TEM) to determine the physical properties of materials, amount of ibuprofen adsorbed and position of ibuprofen. The detailed characterization reveals that the ibuprofen molecules adsorbed inside the mesopores. Increasing the mesopore size from 5 nm to 10 nm increased the ibuprofen loading from 0.74 to 0.85 mmol/g, respectively. Incorporation of macropore into the structure of porous silica materials enhanced the ibuprofen loading capacity of 11.8–20.3%. The ibuprofen-loaded bimodal meso-macroporous silica materials exhibited the highest dissolution of 92 wt.% within an hour. The ibuprofen particles deposited on the external surface of the porous silica materials showed a lower dissolution rate than the ibuprofen adsorbed inside the mesopores due to the formation of ibuprofen crystalline. - Highlights: • Impacts of pore characteristics of supports on adsorption and release of ibuprofen • Increasing mesopore size increased the ibuprofen loading and dissolution rate. • Macropores reduced the diffusion pathway of ibuprofen and dissolution medium.

  3. Impact of pore characteristics of silica materials on loading capacity and release behavior of ibuprofen.

    Science.gov (United States)

    Numpilai, Thanapha; Muenmee, Suthaporn; Witoon, Thongthai

    2016-02-01

    Impact of pore characteristics of porous silica supports on loading capacity and release behavior of ibuprofen was investigated. The porous silica materials and ibuprofen-loaded porous silica materials were thoroughly characterized by N2-sorption, thermal gravimetric and derivative weight analyses (TG-DTW), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), transmission electron microscope (TEM) to determine the physical properties of materials, amount of ibuprofen adsorbed and position of ibuprofen. The detailed characterization reveals that the ibuprofen molecules adsorbed inside the mesopores. Increasing the mesopore size from 5nm to 10nm increased the ibuprofen loading from 0.74 to 0.85mmol/g, respectively. Incorporation of macropore into the structure of porous silica materials enhanced the ibuprofen loading capacity of 11.8-20.3%. The ibuprofen-loaded bimodal meso-macroporous silica materials exhibited the highest dissolution of 92wt.% within an hour. The ibuprofen particles deposited on the external surface of the porous silica materials showed a lower dissolution rate than the ibuprofen adsorbed inside the mesopores due to the formation of ibuprofen crystalline. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. Impact of pore characteristics of silica materials on loading capacity and release behavior of ibuprofen

    International Nuclear Information System (INIS)

    Numpilai, Thanapha; Muenmee, Suthaporn; Witoon, Thongthai

    2016-01-01

    Impact of pore characteristics of porous silica supports on loading capacity and release behavior of ibuprofen was investigated. The porous silica materials and ibuprofen-loaded porous silica materials were thoroughly characterized by N 2 -sorption, thermal gravimetric and derivative weight analyses (TG-DTW), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), transmission electron microscope (TEM) to determine the physical properties of materials, amount of ibuprofen adsorbed and position of ibuprofen. The detailed characterization reveals that the ibuprofen molecules adsorbed inside the mesopores. Increasing the mesopore size from 5 nm to 10 nm increased the ibuprofen loading from 0.74 to 0.85 mmol/g, respectively. Incorporation of macropore into the structure of porous silica materials enhanced the ibuprofen loading capacity of 11.8–20.3%. The ibuprofen-loaded bimodal meso-macroporous silica materials exhibited the highest dissolution of 92 wt.% within an hour. The ibuprofen particles deposited on the external surface of the porous silica materials showed a lower dissolution rate than the ibuprofen adsorbed inside the mesopores due to the formation of ibuprofen crystalline. - Highlights: • Impacts of pore characteristics of supports on adsorption and release of ibuprofen • Increasing mesopore size increased the ibuprofen loading and dissolution rate. • Macropores reduced the diffusion pathway of ibuprofen and dissolution medium.

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

    Science.gov (United States)

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

    2013-05-28

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

  6. Capillary pressure controlled methane hydrate and ice growth-melting patterns in porous media : synthetic silica versus natural sandstone

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, R.; Tohidi, B.; Webber, B. [Heriot-Watt Univ., Centre for Gas Research, Edinburgh (United Kingdom). Inst. of Petroleum Engineering

    2008-07-01

    Although naturally-occurring gas hydrates (or clathrate hydrates) in marine sediments can pose a hazard to deepwater hydrocarbon production operations, they represent a potential strategic energy reserve. Gas hydrates can also provide a means for deep ocean carbon dioxide disposal through sequestration/storage. They have long-term importance with respect to ocean margin stability, methane release, and global climate change. However, fundamental knowledge is still lacking regarding the mechanisms of hydrate growth, accumulation and distribution within the subsurface. Marine sediments which host gas hydrates are commonly fine-grained silts, muds, and clays with narrow mean pore diameters, leading to speculation that capillary phenomena could play a significant role in controlling hydrate distribution in the seafloor, and may be partly responsible for discrepancies between observed and predicted hydrate stability zone thicknesses. A close relationship between hydrate inhibition and pore size has been confirmed through previous laboratory studies. Clathrate stability has been significantly reduced in narrow pores. However, the focus of investigations has generally been hydrate dissociation conditions in porous media, with capillary controls on the equally important process of hydrate growth being largely overlooked. This paper presented the results of an experimental investigation into methane hydrate growth and dissociation equilibria in natural medium grained sandstone. The study also compared data with that previously measured for mesoporous silica glasses. The paper discussed solid-liquid phase behaviour in confined geometries including hysteresis in porous media. It also discussed the experimental equipment and method. It was concluded that, as for synthetic silicas, hydrate growth and dissociation in the sandstone were characterised by a measurable hysteresis between opposing transitions, notably hydrate (or ice) formation occurring at temperatures lower than

  7. Study of the radiolysis of water in porous media

    International Nuclear Information System (INIS)

    Rotureau, P.

    2004-01-01

    The understanding of the production of H 2 in the radiolysis of water confined into pores of concrete is important for the disposal of radioactive waste. In order to describe the mechanisms of water radiolysis in such heterogeneous porous systems we have studied the behaviour under gamma radiation of water confined in porous silica glasses with pores going from 8 to 300 nm of diameter and meso-porous molecular sieves (MCM-41). The radiolytic yields of hydroxyl radicals, hydrated electron and dihydrogen, have been determined with respect to the pore size of materials. The increase of these radiolytic yields compared to those of free water allowed us to show a charge transfer from silica to confined water. On the other hand the kinetics of hydrated electron reactions measured by pulse radiolysis are not modified. (author) [fr

  8. Monitoring Phase Behavior of Sub- and Supercritical CO2 Confined in Porous Fractal Silica with 85% Porosity

    International Nuclear Information System (INIS)

    Melnichenko, Yuri B.; Mayama, Hiroyuki; Cheng, Gang; Cheng, Gang; Blach, Tomasz P.

    2010-01-01

    Phase behavior of CO 2 confined in porous fractal silica with volume fraction of SiO 2 φ 5 = 0.15 was investigated using small-angle neutron scattering (SANS) and ultrasmall-angle neutron scattering (USANS) techniques. The range of fluid densities (0 CO2 ) bulk 3 ) and temperatures (T = 22 C, 35 and 60 C) corresponded to gaseous, liquid, near critical and supercritical conditions of the bulk fluid. The results revealed formation of a dense adsorbed phase in small pores with sizes D CO2 ) bulk 3 ) the average fluid density in pores may exceed the density of bulk fluid by a factor up to 6.5 at T = 22 C. This 'enrichment factor' gradually decreases with temperature, however significant fluid densification in small pores still exists at temperature T = 60 C, i.e., far above the liquid?gas critical temperature of bulk CO 2 (T c = 31.1 C). Larger pores are only partially filled with liquid-like adsorbed layer which coexists with unadsorbed fluid in the pore core. With increasing pressure, all pores become uniformly filled with the fluid, showing no measurable enrichment or depletion of the porous matrix with CO 2 .

  9. Meso Mechanical Analysis of AC Mixture Response

    NARCIS (Netherlands)

    Woldekidan, M.F.; Huurman, M.; Vaccari, E.; Poot, M.

    2012-01-01

    Ongoing research into performance modeling of Asphalt Concrete (AC) mixtures using meso mechanics approaches is being undertaken at Delft University of Technology (TUD). The approach has already been successfully employed for evaluating the long term performance of porous asphalt concrete. The work

  10. Investigating the mesostructure of ordered porous silica nanocomposites by transmission electron microscopy techniques

    Energy Technology Data Exchange (ETDEWEB)

    Bullita, S.; Casula, M. F., E-mail: casulaf@unica.it [INSTM and Department of Chemical and Geological Science, University of Cagliari, Monserrato (Canada) (Italy); Piludu, M. [Department of Biomedical Sciences, University of Cagliari, Monserrato (Canada) (Italy); Falqui, A. [INSTM and Department of Chemical and Geological Science, University of Cagliari, Monserrato (Canada) Italy and KAUST-King Abdullah University of Science and Technology, Jeddah (Saudi Arabia); Carta, D. [INSTM and Department of Chemical and Geological Science, University of Cagliari, Monserrato (Canada), Italy and Faculty of Physical Sciences and Engineering, University of Southampton, Southampton (United Kingdom); Corrias, A. [INSTM and Department of Chemical and Geological Science, University of Cagliari, Monserrato (Canada) Italy and School of Physical Sciences, Ingram Building, University of Kent, Canterbury (United Kingdom)

    2014-10-21

    Nanocomposites made out of FeCo alloy nanocrystals supported onto pre-formed mesoporous ordered silica which features a cubic arrangement of pores (SBA-16) were investigated. Information on the effect of the nanocrystals on the mesostructure (i.e. pore arrangement symmetry, pore size, and shape) were deduced by a multitechnique approach including N2 physisorption, low angle X-ray diffraction, and Transmission electron microscopy. It is shown that advanced transmission electron microscopy techniques are required, however, to gain direct evidence on key compositional and textural features of the nanocomposites. In particular, electron tomography and microtomy techniques make clear that the FeCo nanocrystals are located within the pores of the SBA-16 silica, and that the ordered mesostructure of the nanocomposite is retained throughout the observed specimen.

  11. Preparation of monodisperse porous silica particles using poly(glycidyl methacrylate) microspheres as a template

    Czech Academy of Sciences Publication Activity Database

    Grama, Silvia; Horák, Daniel

    2015-01-01

    Roč. 64, Suppl. 1 (2015), S11-S17 ISSN 0862-8408 R&D Projects: GA MŠk(CZ) EE2.3.30.0029; GA MŠk(CZ) ED1.1.00/02.0109 Institutional support: RVO:61389013 Keywords : microspheres * monodisperse * silica Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 1.643, year: 2015 http://www.biomed.cas.cz/physiolres/pdf/64%20Suppl%201/64_S11.pdf

  12. SiO{sub 2}-TiO{sub 2}-P{sub 2}O{sub 5} meso porous coatings for proton exchange membranes fuel cells; Recubrimientos meso-porosos de SiO{sub 2}-TiO{sub 2}-P{sub 2}O{sub 5} para aplicaciones en pilas de combustible de intercambio protonico

    Energy Technology Data Exchange (ETDEWEB)

    Castro, Y.; Mosa, J.; Duran, A.

    2014-07-01

    The article describes the preparation of meso porous SiO{sub 2}-TiO{sub 2}-P{sub 2}O{sub 5} coatings by Sol-Gel process combined to EISA method for using as proton exchange membranes fuel cells. Tetraethyl orthosilicate (TEOS), methyl triethoxysilane (MTES), titanium tetrachloride (TiCl{sub 4}) and phosphorus trichloride (PCl{sub 3}) have used as precursors and cetyl trimethylammonium bromide (CTAB) as porous generator agent. Films were deposited by immersion technique controlling the relative humidity at 40 and 20-70% and treated at 400 to 500 degree centigrade for 15, 30, 45 and 60 min. The variation of the refractive index and thickness have studied as a function of temperature and sintering time as well as the pore volume and density of the coatings by spectroscopic ellipsometry. Moreover, the hydrophobic/hydrophilic character of the coatings has been studied by Transform Infrared Spectroscopy (FTIR) and by contact angle measurements, following the loss of methyl groups with the temperature and sintering time. The results show that these parameters are crucial to obtain coatings with high porosity and low contact angle, important to obtain high proton conductivity conditions. The sintering conditions were fixed to 400 degree centigrade/60 min. Conductivity measurements at four points show high proton conductivity, 0,16 and 0,85 S/cm, up and down ramp, respectively, at 80 degree centigrade and 80 % of humidity. These coatings are good candidates for PEMFC membranes, if they are deposited onto electrodes. (Author)

  13. Inclusion of gold nanoparticles in meso-porous silicon for the SERS analysis of cell adhesion on nano-structured surfaces

    KAUST Repository

    Coluccio, M.L.; De Vitis, S.; Strumbo, G.; Candeloro, P.; Perozziello, G.; Di Fabrizio, Enzo M.; Gentile, F.

    2016-01-01

    MeP Si surfaces were realized by anodization of a Si wafer, creating the device for cell adhesion and growth. Gold nanoparticles were deposited on porous silicon by an electroless technique. We thus obtained devices with superior SERS capabilities, whereby cell activity may be controlled using Raman spectroscopy. MCF-7 breast cancer cells were cultured on the described substrates and SERS maps revealing the different expression and distribution of adhesion molecules were obtained by Raman spectroscopic analyses.

  14. Impact of the De-Alloying Kinetics and Alloy Microstructure on the Final Morphology of De-Alloyed Meso-Porous Metal Films

    Directory of Open Access Journals (Sweden)

    Bao Lin

    2014-10-01

    Full Text Available Nano-textured porous metal materials present unique surface properties due to their enhanced surface energy with potential applications in sensing, molecular separation and catalysis. In this paper, commercial alloy foils, including brass (Cu85Zn15 and Cu70Zn30 and white gold (Au50Ag50 foils have been chemically de-alloyed to form nano-porous thin films. The impact of the initial alloy micro-structure and number of phases, as well as chemical de-alloying (DA parameters, including etchant concentration, time and solution temperature on the final nano-porous thin film morphology and properties were investigated by electron microscopy (EM. Furthermore, the penetration depth of the pores across the alloys were evaluated through the preparation of cross sections by focus ion beam (FIB milling. It is demonstrated that ordered pores ranging between 100 nm and 600 nm in diameter and 2–5 μm in depth can be successfully formed for the range of materials tested. The microstructure of the foils were obtained by electron back-scattered diffraction (EBSD and linked to development of pits across the material thickness and surface during DA. The role of selective etching of both noble and sacrificial metal phases of the alloy were discussed in light of the competitive surface etching across the range of microstructures and materials tested.

  15. Meso and microscopic characterization of deformation bands in porous sandstones: an example on the Paleozoic, Pre- and Sin-rift sequences of the Araripe Basin, Northeast of Brazil; Caracterizacao meso e microscopica de bandas de deformacao em arenitos porosos: um exemplo nas tectonossequencias Paleozoica, Pre- e Sin-rifte da Bacia do Araripe, Nordeste do Brasil

    Energy Technology Data Exchange (ETDEWEB)

    Araujo Neto, Joao Marculino de; Silva, Fernando Cesar Alves da; Sa, Emanuel Ferraz Jardim de [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil). Programa de Pos-Graduacao em Geodinamica e Geofisica], e-mails: jota_ex2@hotmail.com, fernando@geologia.ufrn.br, emanuel@ccet.ufrn.br

    2012-04-15

    Deformation bands are narrow tabular volumes developed in porous sandstones. Although these structures are a product of brittle deformation, they may have internally a continuous displacement gradient. When granular cataclasis is the dominant deformation mechanism, the initial properties of their host rocks (i.e., porosity and permeability) can change significantly. The deformation bands in sandstones from the pre- and syn-rift of the Araripe Basin were studied in meso and microscale in order to classify them and to understand the deformation mechanisms involved during their nucleation and development. Their geometric-spatial, kinematic, and rheological criteria allowed establishing relations between the origin of deformation bands and lithification of their host rocks. Additionally, some inferences on their influence to the fluid flow in the reservoir-scale were outlined. Moreover, the study of deformation bands contributed to the understanding of the tectonic evolution of the studied basin. Accordingly, the study of deformation bands can support research on local and regional aspects of the tectonosedimentary evolution of sedimentary basins. (author)

  16. HPLC-CUPRAC post-column derivatization method for the determination of antioxidants: a performance comparison between porous silica and core-shell column packing.

    Science.gov (United States)

    Haque, Syed A; Cañete, Socrates Jose P

    2018-01-01

    An HPLC method employing a post-column derivatization strategy using the cupric reducing antioxidant capacity reagent (CUPRAC reagent) for the determining antioxidants in plant-based materials leverages the separation capability of regular HPLC approaches while allowing for detection specificity for antioxidants. Three different column types, namely core-shell and porous silica including two chemically different core-shell materials (namely phenyl-hexyl and C18), were evaluated to assess potential improvements that could be attained by changing from a porous silica matrix to a core-shell matrix. Tea extracts were used as sample matrices for the evaluation specifically looking at catechin and epigallocatechin gallate (EGCG). Both the C18 and phenyl-hexyl core-shell columns showed better performance compared to the C18 porous silica one in terms of separation, peak shape, and retention time. Among the two core-shell materials, the phenyl-hexyl column showed better resolving power compared to the C18 column. The CUPRAC post-column derivatization method can be improved using core-shell columns and suitable for quantifying antioxidants, exemplified by catechin and EGCG, in tea samples.

  17. Controlled Release from Core-Shell Nano porous Silica Particles for Corrosion Inhibition of Aluminum Alloys

    International Nuclear Information System (INIS)

    Jiang, X.; Rathod, Sh.; Shah, P.; Brinker, C.J.; Jiang, X.; Jiang, Y.; Liu, N.; Xu, H.; Brinker, C.J.

    2011-01-01

    Cerium (Ce) corrosion inhibitors were encapsulated into hexagonally ordered nanoporous silica particles via single-step aerosol-assisted self-assembly. The core/shell structured particles are effective for corrosion inhibition of aluminum alloy AA2024-T3. Numerical simulation proved that the core-shell nanostructure delays the release process. The effective diffusion coefficient elucidated from release data for monodisperse particles in water was 1.0x10-14 m 2 s for Ce 3+ compared to 2.5x10-13 m 2 s for NaCl. The pore size, pore surface chemistry, and the inhibitor solubility are crucial factors for the application. Microporous hydrophobic particles encapsulating a less soluble corrosion inhibitor are desirable for long-term corrosion inhibition.

  18. Fabrication of high-capacity polyelectrolyte brush-grafted porous AAO-silica composite membrane via RAFT polymerization.

    Science.gov (United States)

    Song, Cunfeng; Wang, Meijie; Liu, Xin; Wang, He; Chen, Xiaoling; Dai, Lizong

    2017-09-01

    Surface-initiated reversible addition-fragmentation chain transfer (RAFT) polymerization has been utilized to fabricate high-capacity strong anion-exchange (AEX) membrane for the separation of protein. By means of RAFT polymerization, quaternized poly(3-(methacrylamidomethyl)-pyridine) brushes formed 3-dimensional nanolayers on the surface of porous anodic aluminum oxide (AAO)-silica composite membrane. The surface properties of the membranes were analyzed by SEM, water contact angle, ATR-FTIR, XPS and TGA. To investigate the adsorption performance, the new AEX membranes were applied to recover a model protein, ovalbumin (OVA). High adsorption capacities of 95.8mg/g membranes (static) and 65.3mg/g membranes (dynamic) were obtained at ambient temperature. In the further studies, up to 90% of the adsorbed OVA was efficiently eluted by using phosphate buffer-1M NaCl as elution medium. The successful separation of OVA with high purity from a mixture protein solution was also achieved by using the AEX membranes. The present study demonstrated that under mild reaction condition, RAFT polymerization can be used to fabricate ion-exchange membrane which has many remarkable features, such as high capacity and selectivity, easy elution and so on. Copyright © 2017. Published by Elsevier B.V.

  19. Temperature dependence of positron lifetime in ordered porous silica (SBA-3)

    International Nuclear Information System (INIS)

    Kunishige, S.; Koshimizu, M.; Asai, K.

    2009-01-01

    The temperature dependence of positron lifetime in uniform mesopores was analyzed. We used SBA-3 as the sample material, which possesses an ordered porous structure with uniform cylindrical mesopores. The positron lifetime corresponding to the annihilation in the mesopores increased gradually with a decrease in temperature down to 100 K, and its relative intensity also increased concomitantly. This result was attributed to the lower probability of the escape of the ortho-positronium (o-Ps) from the mesopores into the intergrain space at lower temperatures. An anomalous and sudden increase in the lifetime was observed at around 100 K; this result was in agreement with an increase in the positron lifetime reported in a previous study. It was revealed that the increase in the lifetime is very steep in cases of uniform mesopores, suggesting that the temperature dependence is influenced by the pore size.

  20. Inclusion of gold nanoparticles in meso-porous silicon for the SERS analysis of cell adhesion on nano-structured surfaces

    KAUST Repository

    Coluccio, M.L.

    2016-03-25

    The study and the comprehension of the mechanism of cell adhesion and cell interaction with a substrate is a key point when biology and medicine meet engineering. This is the case of several biomedical applications, from regenerative medicine and tissue engineering to lab on chip and many others, in which the realization of the appropriate artificial surface allows the control of cell adhesion and proliferation. In this context, we aimed to design and develop a fabrication method of mesoporous (MeP) silicon substrates, doped with gold nanoparticles, in which we combine the capability of porous surfaces to support cell adhesion with the SERS capabilities of gold nanoparticles, to understand the chemical mechanisms of cell/surface interaction. MeP Si surfaces were realized by anodization of a Si wafer, creating the device for cell adhesion and growth. Gold nanoparticles were deposited on porous silicon by an electroless technique. We thus obtained devices with superior SERS capabilities, whereby cell activity may be controlled using Raman spectroscopy. MCF-7 breast cancer cells were cultured on the described substrates and SERS maps revealing the different expression and distribution of adhesion molecules were obtained by Raman spectroscopic analyses.

  1. Synthesis of silica nanoparticles for the manufacture of porous carbon membrane and particle size analysis by sedimentation field-flow fractionation

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Seung Ho; Eum, Chul; Hun; Choi, Seong Ho; Kim, Woon Jung [Dept. of Chemistry, Hannam University, Daejeon (Korea, Republic of)

    2016-11-15

    Silica nanoparticles were synthesized by emulsion polymerization by mixing ethanol, ammonium hydroxide, water, and tetraethyl orthosilicate. An apparatus was designed and assembled for a large-scale synthesis of silica nanospheres, which was aimed for uniform mixing of the reactants. Then sedimentation field-flow fractionation (SdFFF) was used to determine the size distribution of the silica nanoparticles. SdFFF provided mass-based separation where the retention time increased with the particle size, thus the size distribution of silica nanoparticles obtained from SdFFF appeared more accurate than that from dynamic light scattering, particularly for those having broad and multimodal size distributions. A disk-shaped porous carbon membrane (PCM) was manufactured for application as an adsorbent by pressurizing the silica particles, followed by calcination. Results showed that PCM manufactured in this study has relatively high surface area and temperature stability. The PCM surface was modified by attaching a carboxyl group (PCM-COOH) and then by incorporating silver (PCM-COOH-Ag). The amount of COOH group on PCM was measured electrochemically by cyclic voltammetry, and the surface area, pore size, pore volume of PCM-COOH-Ag by Brunauer–Emmet–Teller measurement. The surface area was 40.65 and reduced to 13.02 after loading a COOH group then increased up to 30.37 after incorporating Ag.

  2. Thermoresponsive copolymer-grafted SBA-15 porous silica particles for temperature-triggered topical delivery systems

    Directory of Open Access Journals (Sweden)

    S. A. Jadhav

    2017-02-01

    Full Text Available A series of poly(N-isopropylacrylamide-co-acrylamide thermoresponsive random copolymers with different molecular weights and composition were synthesized and characterized by attenuated total reflectance Fourier-transform infrared (ATR-FTIR, differential scanning calorimetry (DSC, size exclusion chromatography (SEC and proton nuclear magnetic resonance (NMR spectroscopy. The lower critical solution temperatures (LCST of the copolymers were tuned by changing the mole ratios of monomers. Copolymer with highest molecular weight and LCST (41.2 °C was grafted on SBA-15 type mesoporous silica particles by a two-step polymer grafting procedure. Bare SBA-15 and the thermoresponsive copolymergrafted (hybrid SBA-15 particles were fully characterized by scanning electron microscope (SEM, ATR-FTIR, thermogravimetric analysis (TGA and Brunauer-Emmett-Teller (BET analyses. The hybrid particles were tested for their efficiency as temperature-sensitive systems for dermal delivery of the antioxidant rutin (quercetin-3-O-rutinoside. Improved control over rutin release by hybrid particles was obtained which makes them attractive hybrid materials for drug delivery.

  3. A new porous hybrid material derived from silica fume and alginate for sustainable pollutants reduction

    Science.gov (United States)

    Zanoletti, Alessandra; Vassura, Ivano; Venturini, Elisa; Monai, Matteo; Montini, Tiziano; Federici, Stefania; Zacco, Annalisa; Treccani, Laura; Bontempi, Elza

    2018-03-01

    In this work a new mesoporous adsorbent material obtained from a natural, high abundant raw material and a high volume industrial by-product is presented. The material is consolidated by the gelling properties of alginate and by decomposition of sodium-bicarbonate controlled porosity at low temperatures (70-80°C) at different scale lengths. The structural, thermal, and morphological characterization shows that the material is a mesoporous organic-inorganic hybrid. The material is tested as adsorbent, showing high performances. Methylene blue, used as model pollutant, can be adsorbed and removed from aqueous solutions even at a high concentration with efficiency up to 94%. By coating the material with a 100 nm thin film of titania, good photodegradation performance (more than 20%) can be imparted. Based on embodied energy and carbon footprint of its primary production, the sustainability of the new obtained material is evaluated and quantified in respect to activated carbon as well. It is shown that the new proposed material has an embodied energy lower than one order of magnitude in respect to the one of activated carbon, which represents the gold standards. The versatility of the new material is also demonstrated in terms of its design and manufacturing possibilities. In addition, this material can be printed in 3D. Finally, preliminary results about its ability to capture diesel exhaust particulate matter are reported. The sample exposed to diesel contains a large amount of carbon in its surface. At the best of our knowledge this is the first time that hybrid porous materials are proposed as a new class of sustainable materials, produced to reduce pollutants in the wastewaters and in the atmosphere.

  4. Comparison of three labeled silica nanoparticles used as tracers in transport experiments in porous media. Part II: Transport experiments and modeling

    International Nuclear Information System (INIS)

    Vitorge, Elsa; Szenknect, Stéphanie; Martins, Jean M.-F.; Barthès, Véronique; Gaudet, Jean-Paul

    2014-01-01

    Three types of labeled silica nanoparticles were used in transport experiments in saturated sand. The goal of this study was to evaluate both the efficiency of labeling techniques (fluorescence (FITC), metal (Ag(0) core) and radioactivity ( 110m Ag(0) core)) in realistic transport conditions and the reactive transport of silica nanocolloids of variable size and concentration in porous media. Experimental results obtained under contrasted experimental conditions revealed that deposition in sand is controlled by nanoparticles size and ionic strength of the solution. A mathematical model is proposed to quantitatively describe colloid transport. Fluorescent labeling is widely used to study fate of colloids in soils but was the less sensitive one. Ag(0) labeling with ICP-MS detection was found to be very sensitive to measure deposition profiles. Radiolabeled ( 110m Ag(0)) nanoparticles permitted in situ detection. Results obtained with radiolabeled nanoparticles are wholly original and might be used for improving the modeling of deposition and release dynamics. -- Highlights: • Three kinds of labeled nanotracers were used in transport experiments in sand columns. • They were used as surrogates of silica nanoparticles or mineral colloid. • Deposition depending on colloid size and ionic strength was observed and modeled. • Fluorescence labeling had the worse detection limit but was the more convenient. • Radiolabeled nanotracers were detected in situ in a non destructive way. -- Follow the kinetics of transport, deposition and release of silica nanoparticles with suitably labeled nanoparticles

  5. Morphology-properties relationship of gas plasma treated hydrophobic meso-porous membranes and their improved performance for desalination by membrane distillation

    International Nuclear Information System (INIS)

    Dumée, Ludovic F.; Alglave, Hortense; Chaffraix, Thomas; Lin, Bao; Magniez, Kevin; Schütz, Jürg

    2016-01-01

    than 99.99%. This is the first time that an investigation demonstrates how the permeation characteristics of these membranes is directly related to data from spectral, morphological and surface charge analyses, which provide new insights on the impact of plasma treatments on both, the surface charge and roughness, of PTFE porous materials.

  6. Morphology-properties relationship of gas plasma treated hydrophobic meso-porous membranes and their improved performance for desalination by membrane distillation

    Energy Technology Data Exchange (ETDEWEB)

    Dumée, Ludovic F., E-mail: ludovic.dumee@deakin.edu.au [Deakin University, Geelong Victoria–Australia - Institute for Frontier Materials (Australia); Alglave, Hortense; Chaffraix, Thomas; Lin, Bao; Magniez, Kevin [Deakin University, Geelong Victoria–Australia - Institute for Frontier Materials (Australia); Schütz, Jürg [CSIRO, Manufacturing Flagship, 75 Pigdons Road, 3216 Waurn Ponds, Victoria (Australia)

    2016-02-15

    than 99.99%. This is the first time that an investigation demonstrates how the permeation characteristics of these membranes is directly related to data from spectral, morphological and surface charge analyses, which provide new insights on the impact of plasma treatments on both, the surface charge and roughness, of PTFE porous materials.

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

    International Nuclear Information System (INIS)

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

    2016-01-01

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

  8. Fabrication and Properties of Silica Gel/Calcium Sulfate/Strontium-doped β-tricalcium Phosphate Composite Porous Scaffolds for Bone Tissue Engineering

    Directory of Open Access Journals (Sweden)

    QIN Xiao-su

    2018-03-01

    Full Text Available The calcium sulfate/strontium-doped β-tricalcium phosphate composite spherical pellets was fabricated, using the calcium sulfate/strontium-doped β-TCP as raw material, and through the stirring spray drying method, and then composite spherical pellets were combined with silica gel, porous silica gel/calcium sulfate/strontium-doped β-tricalcium phosphate scaffold was obtained by stacking aggregation method in the mould. The XRD, SEM and FT-IR, etc are employed to examine the chemical composition, composite morphology and structure characteristics, and the degradability, porosity, mechanical properties and cytotoxicity of the scaffolds materials were studied. The results reveal that the composite porous scaffolds have irregular pore structure with pore size between 0.2-1.0mm, and they have a large number of micropores on each of the composite spherical pellets, with the aperture between 50-200μm. Moreover, the porosity of the composite scaffolds is about 62%, which can meet the requirements of scaffolds for bone tissue engineering in porosity; the cytotoxicity tests show the composite scaffolds have no cytotoxic effect and it has good degradation. Therefore, it has good application prospect in bone tissue engineering of the bone defect repair of non-bearing site.

  9. Synthesis and characterization of a new material based on porous silica-Chemically immobilized C,N-pyridylpyrazole for heavy metals adsorption

    Energy Technology Data Exchange (ETDEWEB)

    Radi, Smaail [Laboratoire de Chimie Organique, Macromoleculaire et Produits Naturels, Departement de Chimie, Faculte des Sciences, Universite Mohamed 1er, BP 524, 60 000 Oujda (Morocco)], E-mail: radi_smaail@yahoo.fr; Attayibat, Ahmed [Laboratoire de Chimie Organique, Macromoleculaire et Produits Naturels, Departement de Chimie, Faculte des Sciences, Universite Mohamed 1er, BP 524, 60 000 Oujda (Morocco); Lekchiri, Yahya [Laboratoire de Biochimie, Departement de Biologie, Faculte des Sciences, Universite Mohamed 1er, BP 524, 60 000 Oujda (Morocco); Ramdani, Abdelkrim [Laboratoire de Chimie Organique, Macromoleculaire et Produits Naturels, Departement de Chimie, Faculte des Sciences, Universite Mohamed 1er, BP 524, 60 000 Oujda (Morocco); Bacquet, Maryse [Laboratoire de Chimie Macromoleculaire, Universite des Sciences et Technologies de Lille, 59655 Villeneuve d' Ascq (France)

    2008-10-15

    The immobilization of C,N-pyridylpyrazole on the surface of epoxy group containing silica gel phase for the formation of a newly synthesized material based on porous silica-bound C,N-pyridylpyrazole (SGPP) is described. The surface modification was characterized by {sup 13}C NMR of solid sample, elemental analysis and infrared spectra and was studied and evaluated by determination of the surface area using the BET equation, the adsorption and desorption capability using the isotherm of nitrogen and BJH pore sizes, respectively. The new material exhibits good thermal stability determined by thermogravimetry curves. The synthesized material was utilised in column and batch methods for separation and trace extraction of (Hg{sup 2+}, Cd{sup 2+}, Pb{sup 2+}, Cu{sup 2+}, Zn{sup 2+}, K{sup +}, Na{sup +} and Li{sup +}) and compared to results of classical liquid-liquid extraction with the unbound C,N-pyridylpyrazole compound. The grafting at the surface of silica does not affect complexing properties of the ligand and the material exhibits a high selectivity toward Hg(II)

  10. Tunable thick porous silica coating fabricated by multilayer-by-multilayer bonding of silica nanoparticles for open-tubular capillary chromatographic separation.

    Science.gov (United States)

    Qu, Qishu; Liu, Yuanyuan; Shi, Wenjun; Yan, Chao; Tang, Xiaoqing

    2015-06-19

    A simple coating procedure employing a multilayer-by-multilayer process to modify the inner surface of bare fused-silica capillaries with silica nanoparticles was established. The silica nanoparticles were adsorbed onto the capillary wall via a strong electrostatic interaction between amino functional groups and silica particles. The thickness of the coating could be tuned from 130 to 600 nm by increasing the coating cycles from one to three. Both the retention factor and the resolution were greatly increased with increasing coating cycles. The loading capacity determined by naphthalene in the column with three coating cycles is 152.1 pmol. The effects of buffer concentration and pH value on the stability of the coating were evaluated. The retention reproducibility of the separation of toluene was 0.8, 1.2, 2.3, and 4.5%, respectively, for run-to-run, day-to-day, column-to-column, and batch-to-batch, respectively. The chromatographic performance of these columns was evaluated by both capillary liquid chromatography and open-tubular capillary electrochromatography (OT-CEC). Separation of aromatic hydrocarbons in the column with three coating cycles provided high theoretical plate numbers (up to 269,280 plates m(-1) for toluene) and short separation time (<15 min) by using OT-CEC mode. The method was also used to separate egg white proteins. Both acidic and basic proteins as well as four glycoisoforms were separated in a single run. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Highly porous flame-retardant and sustainable biofoams based on wheat gluten and in situ polymerized silica

    DEFF Research Database (Denmark)

    Wu, Qiong; Andersson, Richard L.; Holgate, Tim

    2014-01-01

    This article presents a novel type of flame-retardant biohybrid foam with good insulation properties based on wheat gluten and silica, the latter polymerized in situ from hydrolysed tetraethyl orthosilicate (TEOS). This led to the formation of intimately mixed wheat gluten and silica phases, wher...... with a vacuum treatment to remove the largest air bubbles. X-ray photoelectron and infrared spectroscopy showed that silicon was present mainly as SiO2....

  12. Meso-/Nanoporous Semiconducting Metal Oxides for Gas Sensor Applications

    Directory of Open Access Journals (Sweden)

    Nguyen Duc Hoa

    2015-01-01

    Full Text Available Development and/or design of new materials and/or structures for effective gas sensor applications with fast response and high sensitivity, selectivity, and stability are very important issues in the gas sensor technology. This critical review introduces our recent progress in the development of meso-/nanoporous semiconducting metal oxides and their applications to gas sensors. First, the basic concepts of resistive gas sensors and the recent synthesis of meso-/nanoporous metal oxides for gas sensor applications are introduced. The advantages of meso-/nanoporous metal oxides are also presented, taking into account the crystallinity and ordered/disordered porous structures. Second, the synthesis methods of meso-/nanoporous metal oxides including the soft-template, hard-template, and temple-free methods are introduced, in which the advantages and disadvantages of each synthetic method are figured out. Third, the applications of meso-/nanoporous metal oxides as gas sensors are presented. The gas nanosensors are designed based on meso-/nanoporous metal oxides for effective detection of toxic gases. The sensitivity, selectivity, and stability of the meso-/nanoporous gas nanosensors are also discussed. Finally, some conclusions and an outlook are presented.

  13. Microporous and meso porous molecular sieves

    International Nuclear Information System (INIS)

    Araujo, Antonio Souza de

    1999-01-01

    In this work, general aspects on the microporous and mesoporous molecular sieves using inorganic sources of aluminium, silicon, phosphorous, water and structural organic templates are reviewed. The nomenclature, synthesis, structure, acidity and chemical functionality of microporous zeolites and silico alumino phosphate, besides mesoporous MCM-41 material, will be emphasized. (author)

  14. Tailored Porous Materials

    Energy Technology Data Exchange (ETDEWEB)

    BARTON,THOMAS J.; BULL,LUCY M.; KLEMPERER,WALTER G.; LOY,DOUGLAS A.; MCENANEY,BRIAN; MISONO,MAKOTO; MONSON,PETER A.; PEZ,GUIDO; SCHERER,GEORGE W.; VARTULI,JAMES C.; YAGHI,OMAR M.

    1999-11-09

    Tailoring of porous materials involves not only chemical synthetic techniques for tailoring microscopic properties such as pore size, pore shape, pore connectivity, and pore surface reactivity, but also materials processing techniques for tailoring the meso- and the macroscopic properties of bulk materials in the form of fibers, thin films and monoliths. These issues are addressed in the context of five specific classes of porous materials: oxide molecular sieves, porous coordination solids, porous carbons, sol-gel derived oxides, and porous heteropolyanion salts. Reviews of these specific areas are preceded by a presentation of background material and review of current theoretical approaches to adsorption phenomena. A concluding section outlines current research needs and opportunities.

  15. Transport of oxidized multi-walled carbon nanotubes through silica based porous media: influences of aquatic chemistry, surface chemistry, and natural organic matter.

    Science.gov (United States)

    Yang, Jin; Bitter, Julie L; Smith, Billy A; Fairbrother, D Howard; Ball, William P

    2013-12-17

    This paper provides results from studies of the transport of oxidized multi-walled carbon nanotubes (O-MWCNTs) of varying surface oxygen concentrations under a range of aquatic conditions and through uniform silica glass bead media. In the presence of Na(+), the required ionic strength (IS) for maximum particle attachment efficiency (i.e., the critical deposition concentration, or CDC) increased as the surface oxygen concentration of the O-MWCNTs or pH increased, following qualitative tenets of theories based on electrostatic interactions. In the presence of Ca(2+), CDC values were lower than those with Na(+) present, but were no longer sensitive to surface oxygen content, suggesting that Ca(2+) impacts the interactions between O-MWCNTs and glass beads by mechanisms other than electrostatic alone. The presence of Suwannee River natural organic matter (SRNOM) decreased the attachment efficiency of O-MWCNTs in the presence of either Na(+) or Ca(2+), but with more pronounced effects when Na(+) was present. Nevertheless, low concentrations of SRNOM (organic carbon) were sufficient to mobilize all O-MWCNTs studied at CaCl2 concentrations as high as 10 mM. Overall, this study reveals that NOM content, pH, and cation type show more importance than surface chemistry in affecting O-MWCNTs deposition during transport through silica-based porous media.

  16. Osseointegration properties of titanium dental implants modified with a nanostructured coating based on ordered porous silica and bioactive glass nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Covarrubias, Cristian, E-mail: ccovarrubias@odontologia.uchile.cl [Laboratory of Nanobiomaterials, Institute for Research in Dental Sciences, Faculty of Dentistry, University of Chile, Santiago (Chile); Mattmann, Matías [Laboratory of Nanobiomaterials, Institute for Research in Dental Sciences, Faculty of Dentistry, University of Chile, Santiago (Chile); Von Marttens, Alfredo [Department of Prosthesis, Faculty of Dentistry, University of Chile, Santiago (Chile); Caviedes, Pablo; Arriagada, Cristián [Laboratory of Cell Therapy, ICBM, Faculty of Medicine, University of Chile (Chile); Valenzuela, Francisco [Laboratory of Nanobiomaterials, Institute for Research in Dental Sciences, Faculty of Dentistry, University of Chile, Santiago (Chile); Rodríguez, Juan Pablo [Laboratory of Cell Biology, INTA, University of Chile, Santiago (Chile); Corral, Camila [Department of Restorative Dentistry, Faculty of Dentistry, University of Chile, Santiago (Chile)

    2016-02-15

    Graphical abstract: - Highlights: • The fabrication of a coating for osseointegration of titanium implant is presented. • The coating consists of nanoporous silica loaded with bioactive glass nanoparticles. • Coating accelerates the in vitro formation of apatite in simulated body fluid. • Coating promotes the osteogenic differentiation of stem cells. • Coating accelerates the formation of bone tissue in the periphery of the implant. - Abstract: The fabrication of a nanoporous silica coating loaded with bioactive glass nanoparticles (nBG/NSC) on titanium dental implant surface and its in vitro and in vivo evaluation is presented. The coating was produced by a combined sol–gel and evaporation induced self-assembly process. In vitro bioactivity was assessed in simulated body fluid (SBF) and investigating the osteogenic differentiation of human bone marrow mesenchymal stem cells (hBMSCs). A rat tibial model was employed to analyze the bone response to nBG/NSC-modified titanium implant surface in vivo. The nBG/NSC coating was confirmed at nano level to be constituted by a highly ordered nanoporous silica structure. The coating nanotopography in conjunction with the bioactivity of the BG particles accelerate the in vitro apatite formation and promote the osteogenic differentiation of hBMSCs in absence of osteogenic supplements. These properties accelerate the formation of bone tissue in the periphery of the implant after 3 weeks of implantation. Backscattered scanning electron microscopy images revealed the presence of gaps and soft tissue in the unmodified implant after 6 weeks, whereas the nBG/NSC-modified implant showed mature bone in intimate contact with the implant surface. The nBG/NSC coating appears promising for accelerating the osseointegration of dental implants.

  17. Osseointegration properties of titanium dental implants modified with a nanostructured coating based on ordered porous silica and bioactive glass nanoparticles

    International Nuclear Information System (INIS)

    Covarrubias, Cristian; Mattmann, Matías; Von Marttens, Alfredo; Caviedes, Pablo; Arriagada, Cristián; Valenzuela, Francisco; Rodríguez, Juan Pablo; Corral, Camila

    2016-01-01

    Graphical abstract: - Highlights: • The fabrication of a coating for osseointegration of titanium implant is presented. • The coating consists of nanoporous silica loaded with bioactive glass nanoparticles. • Coating accelerates the in vitro formation of apatite in simulated body fluid. • Coating promotes the osteogenic differentiation of stem cells. • Coating accelerates the formation of bone tissue in the periphery of the implant. - Abstract: The fabrication of a nanoporous silica coating loaded with bioactive glass nanoparticles (nBG/NSC) on titanium dental implant surface and its in vitro and in vivo evaluation is presented. The coating was produced by a combined sol–gel and evaporation induced self-assembly process. In vitro bioactivity was assessed in simulated body fluid (SBF) and investigating the osteogenic differentiation of human bone marrow mesenchymal stem cells (hBMSCs). A rat tibial model was employed to analyze the bone response to nBG/NSC-modified titanium implant surface in vivo. The nBG/NSC coating was confirmed at nano level to be constituted by a highly ordered nanoporous silica structure. The coating nanotopography in conjunction with the bioactivity of the BG particles accelerate the in vitro apatite formation and promote the osteogenic differentiation of hBMSCs in absence of osteogenic supplements. These properties accelerate the formation of bone tissue in the periphery of the implant after 3 weeks of implantation. Backscattered scanning electron microscopy images revealed the presence of gaps and soft tissue in the unmodified implant after 6 weeks, whereas the nBG/NSC-modified implant showed mature bone in intimate contact with the implant surface. The nBG/NSC coating appears promising for accelerating the osseointegration of dental implants.

  18. Preparation and characterization of micro-cell membrane chromatographic column with N-hydroxysuccinimide group-modified silica-based porous layer open tubular capillary.

    Science.gov (United States)

    Xu, Liang; Xu, Bei; Zhao, Zhi-Yu; Yang, Hui-Ping; Tang, Cheng; Dong, Lin-Yi; Liu, Kun; Fu, Li; Wang, Xian-Hua

    2017-09-22

    Cell membrane chromatography (CMC) is an effective tool in screening active compounds from natural products and studying membrane protein interactions. Nevertheless, it always consumes a large amount of cells (e.g. 10 7 -10 8 ) for column preparation. To overcome this, micro-CMC (mCMC), that employs a silica capillary as membrane carrier, was developed. However, both CMC and mCMC suffer from short column life span (e.g. 3days), mainly due to the falling-off of cellular membranes (CMs). This has greatly limited further application of CMC and mCMC, especially when the cells are hard to obtain. To solve this, N-hydroxysuccinimide (NHS)-modified silica-based porous layer open tubular capillary was first prepared for mCMC. The NHS groups can easily react with amino groups on CMs to form a stable covalent bond under a mild condition. So, CMs immobilized on the NHS-modified capillary are less likely to fall off. To verify this, SKBR3/mCMC (Her2 positive) and BALL1/mCMC (CD20 positive) columns were prepared. Two monoclonal antibody drugs, trastuzumab (anti-Her2) and rituximab (anti-CD20), were selected as analytes to characterize the columns. As a result, NHS-modified column for mCMC can afford higher chromatographic retention than non-modified column. Besides, the column life span was significantly improved to more than 16days for SKBR3/mCMC and 14days for BALL1/mCMC, while the compared column showed a sharp decline in retention factor in first 3days. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. C,N-bipyrazole receptor grafted onto a porous silica surface as a novel adsorbent based polymer hybrid.

    Science.gov (United States)

    Radi, Smaail; Attayibat, Ahmed; El-Massaoudi, Mohamed; Bacquet, Maryse; Jodeh, Shehdeh; Warad, Ismail; Al-Showiman, Salim S; Mabkhot, Yahia N

    2015-10-01

    A simple heterogeneous synthesis of pure adsorbent based polymer hybrid made by condensing a functionalized C,N-bipyrazole with a 3-glycidoxypropyl-trimethoxysilane silylant agent, previously anchored on a silica surface was developed. The formed material (SG2P) was characterized through elemental analysis, FT-IR spectroscopy, (13)C NMR of solid state, scanning electron microscope (SEM), and was studied and evaluated by determination of the surface area using the BET equation, the adsorption and desorption capability using the isotherm of nitrogen and B.J.H. pore sizes. The new material exhibits good thermal stability determined by thermogravimetry curves and good chemical stability was examined in various acidic and buffer solutions (pH 1-7). The binding and adsorption abilities of SG2P were investigated for Hg(2+), Cd(2+), Pb(2+), Zn(2+), K(+), Na(+) and Li(+) cations and compared to the results of classical liquid-liquid extraction with the unbound C,N-bipyrazole compound. The grafting at the surface of silica does not affect complexing properties of the ligand and the SG2P exhibits a high selectivity toward Hg(2+) ion with no complexation being observed towards zinc and alkali metals. The extracted and the complexing cation percentages were determined by atomic absorption measurements. Copyright © 2015 Elsevier B.V. All rights reserved.

  20. Osseointegration properties of titanium dental implants modified with a nanostructured coating based on ordered porous silica and bioactive glass nanoparticles

    Science.gov (United States)

    Covarrubias, Cristian; Mattmann, Matías; Von Marttens, Alfredo; Caviedes, Pablo; Arriagada, Cristián; Valenzuela, Francisco; Rodríguez, Juan Pablo; Corral, Camila

    2016-02-01

    The fabrication of a nanoporous silica coating loaded with bioactive glass nanoparticles (nBG/NSC) on titanium dental implant surface and its in vitro and in vivo evaluation is presented. The coating was produced by a combined sol-gel and evaporation induced self-assembly process. In vitro bioactivity was assessed in simulated body fluid (SBF) and investigating the osteogenic differentiation of human bone marrow mesenchymal stem cells (hBMSCs). A rat tibial model was employed to analyze the bone response to nBG/NSC-modified titanium implant surface in vivo. The nBG/NSC coating was confirmed at nano level to be constituted by a highly ordered nanoporous silica structure. The coating nanotopography in conjunction with the bioactivity of the BG particles accelerate the in vitro apatite formation and promote the osteogenic differentiation of hBMSCs in absence of osteogenic supplements. These properties accelerate the formation of bone tissue in the periphery of the implant after 3 weeks of implantation. Backscattered scanning electron microscopy images revealed the presence of gaps and soft tissue in the unmodified implant after 6 weeks, whereas the nBG/NSC-modified implant showed mature bone in intimate contact with the implant surface. The nBG/NSC coating appears promising for accelerating the osseointegration of dental implants.

  1. Transport and abatement of fluorescent silica nanoparticle (SiO{sub 2} NP) in granular filtration: effect of porous media and ionic strength

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, Chao, E-mail: chaozeng@email.arizona.edu; Shadman, Farhang; Sierra-Alvarez, Reyes [University of Arizona, Department of Chemical and Environmental Engineering (United States)

    2017-03-15

    The extensive production and application of engineered silica nanoparticles (SiO{sub 2} NPs) will inevitably lead to their release into the environment. Granular media filtration, a widely used process in water and wastewater treatment plants, has the potential for NP abatement. In this work, laboratory-scale column experiments were performed to study the transport and retention of SiO{sub 2} NPs on three widely used porous materials, i.e., sand, anthracite, and granular activated carbon (GAC). Synthetic fluorescent core-shell SiO{sub 2} NPs (83 nm) were used to facilitate NP detection. Sand showed very low capacity for SiO{sub 2} filtration as this material had a surface with limited surface area and a high concentration of negative charge. Also, we found that the stability and transport of SiO{sub 2} NP were strongly dependent on the ionic strength of the solution. Increasing ionic strength led to NP agglomeration and facilitated SiO{sub 2} NP retention, while low ionic strength resulted in release of captured NPs from the sand bed. Compared to sand, anthracite and GAC showed higher affinity for SiO{sub 2} NP capture. The superior capacity of GAC was primarily due to its porous structure and high surface area. A process model was developed to simulate NP capture in the packed bed columns and determine fundamental filtration parameters. This model provided an excellent fit to the experimental data. Taken together, the results obtained indicate that GAC is an interesting material for SiO{sub 2} NP filtration.

  2. Transport and abatement of fluorescent silica nanoparticle (SiO_2 NP) in granular filtration: effect of porous media and ionic strength

    International Nuclear Information System (INIS)

    Zeng, Chao; Shadman, Farhang; Sierra-Alvarez, Reyes

    2017-01-01

    The extensive production and application of engineered silica nanoparticles (SiO_2 NPs) will inevitably lead to their release into the environment. Granular media filtration, a widely used process in water and wastewater treatment plants, has the potential for NP abatement. In this work, laboratory-scale column experiments were performed to study the transport and retention of SiO_2 NPs on three widely used porous materials, i.e., sand, anthracite, and granular activated carbon (GAC). Synthetic fluorescent core-shell SiO_2 NPs (83 nm) were used to facilitate NP detection. Sand showed very low capacity for SiO_2 filtration as this material had a surface with limited surface area and a high concentration of negative charge. Also, we found that the stability and transport of SiO_2 NP were strongly dependent on the ionic strength of the solution. Increasing ionic strength led to NP agglomeration and facilitated SiO_2 NP retention, while low ionic strength resulted in release of captured NPs from the sand bed. Compared to sand, anthracite and GAC showed higher affinity for SiO_2 NP capture. The superior capacity of GAC was primarily due to its porous structure and high surface area. A process model was developed to simulate NP capture in the packed bed columns and determine fundamental filtration parameters. This model provided an excellent fit to the experimental data. Taken together, the results obtained indicate that GAC is an interesting material for SiO_2 NP filtration.

  3. Structure and thermal performance of poly(ethylene glycol) alkyl ether (Brij)/porous silica (MCM-41) composites as shape-stabilized phase change materials

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Lingjian; Shi, Haifeng, E-mail: haifeng.shi@gmail.com; Li, Weiwei; Han, Xu; Zhang, Xingxiang, E-mail: zhangpolyu@gmail.com

    2013-10-20

    Graphical abstract: The maximum 50 wt% Brij58 is loaded into the porous MCM-41 networks, and a new peak at 18.8° in XRD patterns confirmed the changes of crystallization behavior of Brij58 against the bulk one. - Highlights: • Poly(ethylene glycol) hexadecyl ether and poly(ethylene glycol) octadecyl ether have the good thermal storage ability. • New peak at 18.8° proved the coexisted confined crystallization and nucleation-induced crystallization. • Poly(ethylene glycol) alkyl ether/MCM-41 PCMs exhibits the good thermal stability. - Abstract: A series of shape-stabilized phase change materials (PCMs), composed of poly(ethylene glycol) hexadecyl ether (Brij58) or poly(ethylene glycol) octadecyl ether (Brij76) and porous silica (MCM-41), were prepared by the physical mixing method. The structure, thermal stability, energy storage ability and crystallization behavior of these composites are deeply investigated and characterized by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), wide-angle X-ray diffraction (WAXD) and thermogravimetric analysis (TGA). Obvious phase transition behavior and energy storage capability are observed for these Brij/MCM-41 composites, and the heat storage efficiency increased with the weight of Brij component. New peak at 18.8° demonstrated that the pore size and the surface adsorption ability of MCM-41 affect the crystallization behavior of Brij molecule. The crystalline structure and energy storage ability of these Brij/MCM-41 composites are discussed based on the crystallization process.

  4. Hierarchical self-assembly of heparin-PEG end-capped porous silica as a redox sensitive nanocarrier for doxorubicin delivery

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen Thi, Thu Thao; Tran, Tuong Vi; Tran, Ngoc Quyen [Institute of Research and Development, Duy Tan University, Da Nang City 550000 (Viet Nam); Institute of Applied Materials Science, Vietnam Academy of Science and Technology, Ho Chi Minh City 70000 (Viet Nam); Nguyen, Cuu Khoa [Institute of Applied Materials Science, Vietnam Academy of Science and Technology, Ho Chi Minh City 70000 (Viet Nam); Nguyen, Dai Hai, E-mail: nguyendaihai0511@gmail.com [Institute of Applied Materials Science, Vietnam Academy of Science and Technology, Ho Chi Minh City 70000 (Viet Nam)

    2017-01-01

    Porous nanosilica (PNS) has been attracting a great attention in fabrication carriers for drug delivery system (DDS). However, unmodified PNS-based carriers exhibited the initial burst release of loaded bioactive molecules, which may limit their potential clinical application. In this study, the surface of PNS was conjugated with adamantylamine (A) via disulfide bonds (PNS-SS-A) which was functionalized with cyclodextrin-heparin-polyethylene glycol (CD-HPEG) for redox triggered doxorubicin (DOX) delivery. The modified PNS was successfully formed with spherical shape and diameter around 50 nm determined by transmission electron microscopy (TEM). DOX was efficiently trapped in the PNS-SS-A@CD-HPEG and slowly released in phosphate buffered saline (PBS) without any initial burst effect. Importantly, the release of DOX was triggered due to the cleavage of the disulfide bonds in the presence of dithiothreitol (DTT). In addition, the MTT assay data showed that PNS-SS-A@CD-HPEG was a biocompatible nanocarrier and reduced the toxicity of DOX. These results demonstrated that PNS-SS-A@CD-HPEG has great potential as a novel nanocarrier for anticancer drug in cancer therapy. - Graphic abstract: Hierarchical self-assembly of heparin-PEG end-capped mesoporous silica through host-guest interaction for trapping doxorubicin. The copolymer attached on PNS via disulfide bond which is rapidly cleaved in redox environment, and as a result a huge amount of doxorubicin will release. - Highlights: • Novel redox-responsive nanocarriers based on surface-modified porous nanosilica (PNS) were developed. • Spherical-shaped PNS nanoparticles with diameter around 50 nm were obtained. • Doxorubicin (DOX) was effectively loaded and released in a controlled manner without any initial burst release by surface modification of PNS. • The redox-responsive properties of the modified PNS were demonstrated due to reductive cleavage of disulfide bonds in dithiothreitol (DTT). • The

  5. Transport and abatement of fluorescent silica nanoparticle (SiO2 NP) in granular filtration: effect of porous media and ionic strength

    Science.gov (United States)

    Zeng, Chao; Shadman, Farhang; Sierra-Alvarez, Reyes

    2017-03-01

    The extensive production and application of engineered silica nanoparticles (SiO2 NPs) will inevitably lead to their release into the environment. Granular media filtration, a widely used process in water and wastewater treatment plants, has the potential for NP abatement. In this work, laboratory-scale column experiments were performed to study the transport and retention of SiO2 NPs on three widely used porous materials, i.e., sand, anthracite, and granular activated carbon (GAC). Synthetic fluorescent core-shell SiO2 NPs (83 nm) were used to facilitate NP detection. Sand showed very low capacity for SiO2 filtration as this material had a surface with limited surface area and a high concentration of negative charge. Also, we found that the stability and transport of SiO2 NP were strongly dependent on the ionic strength of the solution. Increasing ionic strength led to NP agglomeration and facilitated SiO2 NP retention, while low ionic strength resulted in release of captured NPs from the sand bed. Compared to sand, anthracite and GAC showed higher affinity for SiO2 NP capture. The superior capacity of GAC was primarily due to its porous structure and high surface area. A process model was developed to simulate NP capture in the packed bed columns and determine fundamental filtration parameters. This model provided an excellent fit to the experimental data. Taken together, the results obtained indicate that GAC is an interesting material for SiO2 NP filtration.

  6. Preparation of porous hollow silica spheres via a layer-by-layer process and the chromatographic performance

    Science.gov (United States)

    Wei, Xiaobing; Gong, Cairong; Chen, Xujuan; Fan, Guoliang; Xu, Xinhua

    2017-03-01

    Hollow silica spheres possessing excellent mechanical properties were successfully prepared through a layer-by-layer process using uniform polystyrene (PS) latex fabricated by dispersion polymerization as template. The formation of hollow SiO2 micro-spheres, structures and properties were observed in detail by zeta potential, SEM, TEM, FTIR, TGA and nitrogen sorption porosimetry. The results indicated that the hollow spheres were uniform with particle diameter of 1.6 μm and shell thickness of 150 nm. The surface area was 511 m2/g and the pore diameter was 8.36 nm. A new stationary phase for HPLC was obtained by using C18-derivatized hollow SiO2 micro-spheres as packing materials and the chromatographic properties were evaluated for the separation of some regular small molecules. The packed column showed low column pressure, high values of efficiency (up to about 43 000 plates/m) and appropriate asymmetry factors.

  7. Highly porous layers of silica nanospheres sintered by drying: scaling up of the elastic properties of the beads to the macroscopic mechanical properties.

    Science.gov (United States)

    Lesaine, Arnaud; Bonamy, Daniel; Gauthier, Georges; Rountree, Cindy L; Lazarus, Véronique

    2018-05-16

    Layers obtained by drying a colloidal dispersion of silica spheres are found to be a good benchmark to test the elastic behaviour of porous media, in the challenging case of high porosities and nano-sized microstructures. Classically used for these systems, Kendall's approach explicitly considers the effect of surface adhesive forces onto the contact area between the particles. This approach provides the Young's modulus using a single adjustable parameter (the adhesion energy) but provides no further information on the tensorial nature and possible anisotropy of elasticity. On the other hand, homogenization approaches (e.g. rule of mixtures, and Eshelby, Mori-Tanaka and self-consistent schemes), based on continuum mechanics and asymptotic analysis, provide the stiffness tensor from the knowledge of the porosity and the elastic constants of the beads. Herein, the self-consistent scheme accurately predicts both bulk and shear moduli, with no adjustable parameter, provided the porosity is less than 35%, for layers composed of particles as small as 15 nm in diameter. Conversely, Kendall's approach is found to predict the Young's modulus over the full porosity range. Moreover, the adhesion energy in Kendall's model has to be adjusted to a value of the order of the fracture energy of the particle material. This suggests that sintering during drying leads to the formation of covalent siloxane bonds between the particles.

  8. Development of new microporous silica membranes for gas separation

    International Nuclear Information System (INIS)

    Camelia Barboiu; Alejandro Mourgues; Beatrice Sala; Serge de Perthuis; Camelia Barboiu; Alejandro Mourgues; Beatrice Sala; Anne Julbe; Jose Sanchez

    2006-01-01

    This paper presents the synthesis and the application of molecular sieving ceramic membranes to purify hydrogen or helium from various gas mixtures. The membranes prepared in this work consist of an ultra-microporous silica-based separative layer produced via a sol-gel process. Ultra microporous silica containing boron is synthesized by the acid catalyzed hydrolysis and condensation of tetra-ethyl-ortho-silicate in ethanol. The layer is deposited inside a tubular asymmetric alumina support with a meso-porous y alumina inner layer. The thickness of the silica layers after treatment is about 200 nm, estimated from their cross-section SEM micrographs. Ultra-microporous membranes (with pore sizes less than 0.7 nm) are thus required to get high selectivity. Such membranes enable to carry out gas separation up to 500 deg C under a transmembrane pressure lower than 8 bars. He and H 2 permeance values close to 10 -7 mol.m -2 s -1 Pa -1 are obtained, associated with ideal selectivities α(He/CO 2 ) and α(H 2 /CO 2 ) between 10 and 20 at 300 deg C. (authors)

  9. Syntheses of carbon porous materials with varied pore sizes and their performances as catalyst supports during methanol oxidation reaction

    International Nuclear Information System (INIS)

    Lo, An-Ya; Hung, Chin-Te; Yu, Ningya; Kuo, Cheng-Tzu; Liu, Shang-Bin

    2012-01-01

    Highlights: ► CPMs with varied pore sizes (1–400 nm) were replicated from various porous silicas by CVI method. ► MOR activities of Pt/CPM electrocatalysts increase with increasing pore size of CPM support. ► Microporous CPMs are favorable supports for Pt in terms of catalytic performance and CO-tolerance. -- Abstract: Carbon porous materials (CPMs) with extended ranges of pore size and morphology were replicated using various porous silicas, such as zeolites, mesoporous silicas, and photonic crystals, as templates by means of chemical vapor infiltration (CVI) method. The micro-, meso-, and macro-porous carbons so fabricated were adopted as supports for the metal (Pt) catalyst for direct methanol fuel cells (DMFCs), and the supported Pt/CPM electrocatalysts were characterized by a variety of different spectroscopic/analytical techniques, viz. transmission electron microscopy (TEM), Raman, X-ray photoelectron spectroscopy (XPS), gas physisorption/chemisorption analyses, and cyclic voltammetry (CV). That these Pt/CPMs were found to exhibit superior electrocatalytic activities compared to the commercial Pt/XC-72 with a comparable Pt loading during methanol oxidation reaction (MOR) is attributed to the presence of Pt nanoparticles (NPs; typically 1–3 nm in size) that are highly dispersed in the CPMs, facilitating an improved tolerance for CO poisoning. While the MOR activity observed for various Pt/CPMs tend to increase with increasing pore size of the carbon supports, Pt catalyst supported on carbon substrates possessing microporosities was found to have superior stability in terms of tolerance for CO poisoning than those with greater pore size or having meso- and macroporosities.

  10. Methanol-Sensing Property Improvement of Meso structured Zinc Oxide Prepared by the Nano casting Strategy

    International Nuclear Information System (INIS)

    Gao, Q.; Zheng, W.T.; Wei, C.D.; Lin, H.M.

    2013-01-01

    The specific structure and morphology often play a critical role in governing the excellent intrinsic properties of the compound semiconductor. Herein, meso structured ZnO with excellent methanol-sensing properties was prepared by a structure replication procedure through the incipient wetness technique. The investigation on the crystal structure and morphology of the resultant material shows that the product consists of hexagonally arranged meso pores and crystalline walls, and its structure is an ideal replication of CMK-3 template. Consequently, meso structured ZnO was fabricated as a gas sensor for methanol. The excellent methanol-sensing performance was achieved at a relatively low operating temperature of 120°C. In comparison with the non porous ZnO prepared through conventional coprecipitation approach, meso structured ZnO material shows the higher sensitivity and stability. Furthermore, it shows the discrimination between methanol and ethanol sensitivity, which makes it a good candidate in fabricating selective methanol sensor in practice

  11. Sol–gel hybrid membranes loaded with meso/macroporous SiO{sub 2}, TiO{sub 2}–P{sub 2}O{sub 5} and SiO{sub 2}–TiO{sub 2}–P{sub 2}O{sub 5} materials with high proton conductivity

    Energy Technology Data Exchange (ETDEWEB)

    Castro, Yolanda, E-mail: castro@icv.csic.es [Instituto de Cerámica y Vidrio, Consejo Superior de Investigaciones Científicas (ICV-CSIC), Campus de Cantoblanco, 28049 Madrid (Spain); Mosa, Jadra, E-mail: jmosa@icv.csic.es [Instituto de Cerámica y Vidrio, Consejo Superior de Investigaciones Científicas (ICV-CSIC), Campus de Cantoblanco, 28049 Madrid (Spain); Aparicio, Mario [Instituto de Cerámica y Vidrio, Consejo Superior de Investigaciones Científicas (ICV-CSIC), Campus de Cantoblanco, 28049 Madrid (Spain); Pérez-Carrillo, Lourdes A.; Vílchez, Susana; Esquena, Jordi [Instituto de Química Avanzada de Cataluña, Consejo Superior de Investigaciones Científicas (IQAC-CSIC), CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Jordi Girona 18-26, 08034 Barcelona (Spain); Durán, Alicia [Instituto de Cerámica y Vidrio, Consejo Superior de Investigaciones Científicas (ICV-CSIC), Campus de Cantoblanco, 28049 Madrid (Spain)

    2015-01-15

    In this work, highly conductive hybrid organic–inorganic membranes loaded with SiO{sub 2}, TiO{sub 2}–P{sub 2}O{sub 5} and SiO{sub 2}–TiO{sub 2}–P{sub 2}O{sub 5} meso/macroporous particles were prepared via a sol–gel process. Meso/macroporous particles were incorporated to hybrid membranes, for improving water retention and enhancing electrochemical performance. These particles with a polymodal pore size distribution were prepared by templating in highly concentrated emulsions, the particles showed a specific surface area between 50 m{sup 2}/g (TiO{sub 2}–P{sub 2}O{sub 5}) and 300 m{sup 2}/g (SiO{sub 2}–TiO{sub 2}–P{sub 2}O{sub 5}). The particles were dispersed in a hybrid silica sol and further sprayed onto glass paper. The films were polymerized and sintered; those loaded with meso/macroporous particles had a homogenous distribution. High temperature proton conductivity measurements confirmed a high water retention. Conductivity of these materials is higher than that of Nafion{sup ®} at higher temperatures (120 °C) (2·10{sup −2} S/cm). This study provides processing guideline to achieve hybrid electrolytes for efficient conduction of protons due to their high surface area and porous structure. - Highlights: • Hybrid electrolyte with meso/macroporous particles were synthesized by sol–gel. • Depositions of hybrid solutions by spraying onto glass substrates were performed. • Proton conductivity was evaluated as a function of composition and porous structure.

  12. Sol–gel hybrid membranes loaded with meso/macroporous SiO2, TiO2–P2O5 and SiO2–TiO2–P2O5 materials with high proton conductivity

    International Nuclear Information System (INIS)

    Castro, Yolanda; Mosa, Jadra; Aparicio, Mario; Pérez-Carrillo, Lourdes A.; Vílchez, Susana; Esquena, Jordi; Durán, Alicia

    2015-01-01

    In this work, highly conductive hybrid organic–inorganic membranes loaded with SiO 2 , TiO 2 –P 2 O 5 and SiO 2 –TiO 2 –P 2 O 5 meso/macroporous particles were prepared via a sol–gel process. Meso/macroporous particles were incorporated to hybrid membranes, for improving water retention and enhancing electrochemical performance. These particles with a polymodal pore size distribution were prepared by templating in highly concentrated emulsions, the particles showed a specific surface area between 50 m 2 /g (TiO 2 –P 2 O 5 ) and 300 m 2 /g (SiO 2 –TiO 2 –P 2 O 5 ). The particles were dispersed in a hybrid silica sol and further sprayed onto glass paper. The films were polymerized and sintered; those loaded with meso/macroporous particles had a homogenous distribution. High temperature proton conductivity measurements confirmed a high water retention. Conductivity of these materials is higher than that of Nafion ® at higher temperatures (120 °C) (2·10 −2  S/cm). This study provides processing guideline to achieve hybrid electrolytes for efficient conduction of protons due to their high surface area and porous structure. - Highlights: • Hybrid electrolyte with meso/macroporous particles were synthesized by sol–gel. • Depositions of hybrid solutions by spraying onto glass substrates were performed. • Proton conductivity was evaluated as a function of composition and porous structure

  13. Anisotropic silica mesostructures for DNA encapsulation

    Indian Academy of Sciences (India)

    The encapsulation of biomolecules in inert meso or nanostructures is an important step towards controlling drug delivery agents. Mesoporous silica nanoparticles (MSN) are of immense importance owing to their high surface area, large pore size, uniform particle size and chemical inertness. Reverse micellar method with ...

  14. Constitutive relation of concrete containing meso-structural characteristics

    Directory of Open Access Journals (Sweden)

    Li Guo

    Full Text Available A constitutive model of concrete is proposed based on the mixture theory of porous media within thermodynamic framework. By treating concrete as a multi-phase multi-component mixture, we constructed the constitutive functions for elastic, interfacial, and plastic strain energy respectively. A constitutive law of concrete accommodating internal micro-cracks and interfacial boundaries was established. The peak stress predicted with the developed model depends primarily on the volume ratio of aggregate, and the results explain very well reported experimental phenomena. The strain-stress curve under uniaxial loading was found in a good agreement with experimental data for concrete with three different mixing proportions. Keywords: Constitutive model of concrete, Mixture theory of porous media, Meso-structure, Interfacial energy

  15. Thiol-functionalized silica colloids, grains, and membranes for irreversible adsorption of metal(oxide) nanoparticles

    NARCIS (Netherlands)

    Claesson, E.M.; Philipse, A.P.

    2007-01-01

    Thiol-functionalization is described for silica surfaces from diverging origin, including commercial silica nanoparticles and St¨ober silica as well as silica structures provided by porous glasses and novel polymer-templated silica membranes. The functionalization allows in all cases for the

  16. Innovative preparation of Au/C by replication of gold-containing mesoporous silica catalysts

    KAUST Repository

    Kerdi, Fatmé ; Caps, Valerie; Tuel, Alain

    2010-01-01

    A new strategy, based on the nanocasting concept, has been used to prepare gold nanoparticles (NPs) highly dispersed in meso-structured carbons. Gold is first introduced in various functionalized mesostructured silicas (MCM-48 and SBA-15

  17. A porous silica rock ("tripoli") in the footwall of the Jurassic Úrkút manganese deposit, Hungary: composition, and origin through carbonate dissolution

    Science.gov (United States)

    Polgari, Marta; Szabo, Zoltan; Szabo-Drubina, Magda; Hein, James R.; Yeh, Hsueh-Wen

    2005-01-01

    The mineralogical, chemical, and isotopic compositions were determined for a white tripoli from the footwall of the Jurassic Úrkút Mn-oxide ore deposit in the Bakony Mountains, Hungary. The tripoli consists of quartz and chalcedony, with SiO2 contents up to 100 wt.%; consequently, trace-element contents are very low. Oxygen isotopes and quartz crystallinity indicate a low-temperature diagenetic origin for this deposit. The tripoli was formed by dissolution of the carbonate portion of the siliceous (sponge spicules) Isztimér Limestone. Dissolution of the carbonate was promoted by inorganic and organic acids generated during diagensis and left a framework composed of diagenetic silica that preserved the original volume of the limestone layer. The relative enrichment of silica and high porosity is the result of that carbonate dissolution. The silty texture of this highly friable rock is due to the structurally weak silica framework.

  18. Fumed silica. Fumed silica

    Energy Technology Data Exchange (ETDEWEB)

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

    1991-10-18

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

  19. Ordered mesoporous silica materials with complicated structures

    KAUST Repository

    Han, Yu; Zhang, Daliang

    2012-01-01

    Periodically ordered mesoporous silicas constitute one of the most important branches of porous materials that are extensively employed in various chemical engineering applications including adsorption, separation and catalysis. This short review

  20. A Hierarchically Micro-Meso-Macroporous Zeolite CaA for Methanol Conversion to Dimethyl Ether

    Directory of Open Access Journals (Sweden)

    Yan Wang

    2016-11-01

    Full Text Available A hierarchical zeolite CaA with microporous, mesoporous and macroporous structure was hydrothermally synthesized by a ”Bond-Blocking” method using organo-functionalized mesoporous silica (MS as a silica source. The characterization by XRD, SEM/TEM and N2 adsorption/desorption techniques showed that the prepared material had well-crystalline zeolite Linde Type A (LTA topological structure, microspherical particle morphologies, and hierarchically intracrystalline micro-meso-macropores structure. With the Bond-Blocking principle, the external surface area and macro-mesoporosity of the hierarchical zeolite CaA can be adjusted by varying the organo-functionalized degree of the mesoporous silica surface. Similarly, the distribution of the micro-meso-macroporous structure in the zeolite CaA can be controlled purposely. Compared with the conventional microporous zeolite CaA, the hierarchical zeolite CaA as a catalyst in the conversion of methanol to dimethyl ether (DME, exhibited complete DME selectivity and stable catalytic activity with high methanol conversion. The catalytic performances of the hierarchical zeolite CaA results clearly from the micro-meso-macroporous structure, improving diffusion properties, favoring the access to the active surface and avoiding secondary reactions (no hydrocarbon products were detected after 3 h of reaction.

  1. Grid for Meso american Archaeology

    International Nuclear Information System (INIS)

    Lucet, G.

    2007-01-01

    Meso american archaeology works with large amounts of disperse and diverse information, thus the importance of including new methods that optimise the acquisition, conservation, retrieval, and analysis of data to generate knowledge more efficiently and create a better understanding of history. Further, this information --which includes texts, coordinates, raster graphs, and vector graphs-- comes from a considerable geographical area --parts of Mexico, Nicaragua, Honduras and Costa Rica as well as Guatemala, El Salvador and Belize-- is constantly expanding. This information includes elements like shards, buildings, mural paintings, high and low reliefs, topography, maps, and information about the fauna and soil. Grid computing offers a solution to handle all this information: it respects researchers' need for independence while supplying a platform to share, process and compare the data obtained. Additionally, the Grid can enhance space-time analyses with remote visualisation techniques that can, in turn, incorporate geographical information systems and virtual reality. (Author)

  2. Dynamic behavior of porous concretes under drop weight impact testing

    NARCIS (Netherlands)

    Agar Ozbek, A.S.; Weerheijm, J.; Schlangen, E.; Breugel, K. van

    2013-01-01

    Porous concrete is used as a construction material in various applications mainly as a permeable cementitious material. However, its response under impact loading is generally not considered. Due to the high percentage of its intentional meso-size air pores, porous concrete has a moderate static

  3. Investigating porous concrete with improved strength: Testing at different scales

    NARCIS (Netherlands)

    Agar-Ozbek, A.S.; Weerheijm, J.; Schlangen, E.; Breugel, K. van

    2013-01-01

    Porous concrete incorporates a high percentage of meso-size air voids that makes its mechanical characteristics remarkably different from normal concrete. A research project was undertaken to design a special type of porous concrete, that fractures into small fragments when exposed to impact loading

  4. Fenton detemplation of ordered (meso)porous materials

    NARCIS (Netherlands)

    Melian-Cabrera, I.; Osman, A. H.; van Eck, E. R. H.; Kentgens, Arno P.M.; Polushkin, E.; Kapteijn, F.; Moulijn, J. A.; Xu, R; Gao, Z; Chen, J; Yan, W

    2007-01-01

    This article describes a new methodology (Fenton detemplation), which consists of removing the template by chemical oxidation and develop the material's porosity. The oxidizing agents are OH radicals, which are generated from H(2)O(2) in the presence of catalytic amounts of Fe cations. This is known

  5. Meso-optics for science and industry

    International Nuclear Information System (INIS)

    Soroko, L.M.

    1996-01-01

    The paper represents a concise overview of the meso-optical devices which provide very high selectivity and productivity. The source of these advantages is governed by the absence of the traditional 3D scanning operations. The information compression is accomplished on-line via conical wavefronts without any computer data processing. The factor of merits is of the order of 100:1. Meso-optical Fourier transition microscope for nuclear emulsion sees only straight line particle tracks and does not require depth scanning. Confocal meso-optical microscope accomplishes selective observation of the vertical particle tracks. In the meso-optical profilometer we use the phenomenon of the longitudinal interference of the conical waves. Meso-optical undulator as inserted device in the photon factories transforms conical waves into spherical ones and then into a point. Self-focusing undulator focuses side-going synchrotron radiation. Meso-optical conicometer accomplishes precise control of the conical surfaces both internal and external. Meso-optical interferometer with multipass transmission of the conical waves is used for on-line observation of the deviation of the surface of the industrial parts from the conical etalon without any scanning operations. 23 refs., 23 figs

  6. Hierarchical silica particles by dynamic multicomponent assembly

    DEFF Research Database (Denmark)

    Wu, Z. W.; Hu, Q. Y.; Pang, J. B.

    2005-01-01

    Abstract: Aerosol-assisted assembly of mesoporous silica particles with hierarchically controllable pore structure has been prepared using cetyltrimethylammonium bromide (CTAB) and poly(propylene oxide) (PPO, H[OCH(CH3)CH2],OH) as co-templates. Addition of the hydrophobic PPO significantly...... influences the delicate hydrophilic-hydrophobic balance in the well-studied CTAB-silicate co-assembling system, resulting in various mesostructures (such as hexagonal, lamellar, and hierarchical structure). The co-assembly of CTAB, silicate clusters, and a low-molecular-weight PPO (average M-n 425) results...... in a uniform lamellar structure, while the use of a high-molecular-weight PPO (average M-n 2000), which is more hydrophobic, leads to the formation of hierarchical pore structure that contains meso-meso or meso-macro pore structure. The role of PPO additives on the mesostructure evolution in the CTAB...

  7. On the use of mesophase pitch for the preparation of hierarchical porous carbon monoliths by nanocasting

    Directory of Open Access Journals (Sweden)

    Philipp Adelhelm, Karin Cabrera and Bernd M Smarsly

    2012-01-01

    Full Text Available A detailed study is given on the synthesis of a hierarchical porous carbon, possessing both meso- and macropores, using a mesophase pitch (MP as the carbon precursor. This carbon material is prepared by the nanocasting approach involving the replication of a porous silica monolith (hard templating. While this carbon material has already been tested in energy storage applications, various detailed aspects of its formation and structure are addressed in this study. Scanning electron microscopy (SEM, Hg porosimetry and N2 physisorption are used to characterize the morphology and porosity of the carbon replica. A novel approach for the detailed analysis of wide-angle x-ray scattering (WAXS from non-graphitic carbons is applied to quantitatively compare the graphene microstructures of carbons prepared using MP and furfuryl alcohol (FA. This WAXS analysis underlines the importance of the carbon precursor in the synthesis of templated porous carbon materials via the nanocasting route. Our study demonstrates that a mesophase pitch is a superior precursor whenever a high-purity, low-micropore-content and well-developed graphene structure is desired.

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

    Science.gov (United States)

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

    2016-06-01

    Mesoporous silica, MCM-41, functionalized with 3-aminopropyltriethoxysilane (APTES) was investigated as a potential drug delivery system, using [(64)Cu]-5, 10, 15, 20-tetrakis penta fluorophenyl porphyrin complex. [(64)Cu]-TPPF20 complex was grafted on functionalized MCM-41. The product was characterized by paper chromatography, FTIR spectroscopy, low angle X-ray diffraction, CHN and TGA/DTA analyses and atomic force microscopy. The biological evaluations of the grafted complex, [(64)Cu]-TPPF20@NH2-MCM-41, were done in Fibrosarcoma tumor-bearing Sprague-Dawley rats using scarification studies and Sopha DST-XL Dual-Head SPECT system. The actual loading amount of aminopropyl groups was found about 1.6mmol per gram of final silica. The specific activity of the final compound was found to be 3Ci/g. Amine functionalized MCM-41 was found to be a good platform for theranostic radiopharmaceuticals such as copper-64 complexes. Considering the accumulation of the tracer in tumor cells, fast wash-out from normal tissues, the short half-life copper-64 and less imposed radiation doses to patients, [(64)Cu]-TPPF20@NH2-MCM-41 can potentially be a suitable candidate for tumor imaging applications and future PET studies. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Experimental study and thermodynamic modelling of methane clathrate hydrate dissociation conditions in silica gel porous media in the presence of methanol aqueous solution

    International Nuclear Information System (INIS)

    Hashemi, Hamed; Javanmardi, Jafar; Zarifi, Mojdeh; Eslamimanesh, Ali; Mohammadi, Amir H.

    2012-01-01

    Highlights: ► Phase equilibria of hydrates of methane in confined silica gel pores are reported. ► Dissociation data in the presences of methanol aqueous solution are also measured. ► A thermodynamic model is developed for prediction of the obtained data. ► Acceptable agreement is found between the obtained data and the predicted results. - Abstract: In this work, the phase equilibria of clathrate hydrates of methane in the presence of pure water and 0.035 mass fraction of methanol aqueous solution in confined silica gel pores with (10 and 15) nm mean diameters are measured and reported. A thermodynamic model is also developed for prediction of the obtained experimental hydrate dissociation data. The Valderrama–Patel–Teja (VPT-EoS) equation of state (EoS) accompanied with the non-density dependent (NDD) mixing rules coupled with a previously developed activity model are applied to evaluate the fugacity of the species present and the activity coefficient of water in methanol aqueous solution. Acceptable agreement between the reported data and the predicted results using the proposed model and an existing method reported in the literature demonstrates the reliability of the presented model.

  10. Analazing the impact behavior of porous concrete

    NARCIS (Netherlands)

    Agar Ozbek, A.S.; Weerheijm, J.

    2014-01-01

    Porous concrete is a special type of cementitious material incorporating a high amount of meso-size air pores that makes its characteristics markedly different from normal concrete. Therefore, it is being investigated for various applications, aiming to benefit from the presence of the air voids in

  11. Polymer-Silica Nanocomposites: A Versatile Platform for Multifunctional Materials

    Science.gov (United States)

    Chiu, Chi-Kai

    Solution sol-gel synthesis is a versatile approach to create polymer-silica nanocomposite materials. The solution-to-solid transformation results in a solid consisting of interconnected nanoporous structure in 3D space, making it the ideal material for filtration, encapsulation, optics, electronics, drug release, and biomaterials, etc. Although the pore between nano and meso size may be tunable using different reaction conditions, the intrinsic properties such as limited diffusion within pore structure, complicated interfacial interactions at the pore surfaces, shrinkage and stress-induced cracking and brittleness have limited the applications of this material. To overcome these problems, diffusion, pore size, shrinkage and stress-induced defects need further investigation. Thus, the presented thesis will address these important questions such as whether these limitations can be utilized as the novel method to create new materials and lead to new applications. First, the behaviors of polymers such as poly(ethylene glycol) inside the silica pores are examined by studying the nucleation and growth of AgCl at the surface of the porous matrix. The pore structure and the pressure induced by the shrinkage affect have been found to induce the growth of AgCl nanocrystals. When the same process is carried out at 160 °C, silver metallization is possible. Due to the shrinkage-induced stresses, the polymer tends to move into open crack spaces and exterior surfaces, forming interconnected silver structure. This interconnected silver structure is very unique because its density is not related to the size scale of nanopore structures. These findings suggest that it is possible to utilize defect surface of silica material as the template to create interconnected silver structure. When the scale is small, polymer may no longer be needed if the diffusion length of Ag is more than the size of silica particles. To validate our assumption, monoliths of sol-gel sample containing AgNO3

  12. Efficient Self-Assembly of mPEG End-Capped Porous Silica as a Redox-Sensitive Nanocarrier for Controlled Doxorubicin Delivery

    Directory of Open Access Journals (Sweden)

    Anh Khoa Nguyen

    2018-01-01

    Full Text Available Porous nanosilica (PNS has been regarded as a promising candidate for controlled delivery of anticancer drugs. Unmodified PNS-based nanocarriers, however, showed a burst release of encapsulated drugs, which may limit their clinical uses. In this report, PNS was surface conjugated with adamantylamine (ADA via disulfide bridges (-SS-, PNS-SS-ADA, which was further modified with cyclodextrin-poly(ethylene glycol methyl ether conjugate (CD-mPEG to form a core@shell structure PNS-SS-ADA@CD-mPEG for redox triggered delivery of doxorubicin (DOX, DOX/PNS-SS-ADA@CD-mPEG. The prepared PNS-SS-ADA@CD-mPEG nanoparticles were spherical in shape with an average diameter of 55.5 ± 3.05 nm, a little larger than their parentally PNS nanocarriers, at 49.6 ± 2.56 nm. In addition, these nanoparticles possessed high drug loading capacity, at 79.2 ± 3.2%, for controlled release. The release of DOX from DOX/PNS-SS-ADA@CD-mPEG nanoparticles was controlled and prolonged up to 120 h in PBS medium (pH 7.4, compared to less than 40 h under reducing condition of 5 mM DTT. Notably, the PNS-SS-ADA@CD-mPEG was a biocompatible nanocarrier, and the toxicity of DOX was dramatically reduced after loading drugs into the porous core. This redox-sensitive PNS-SS-ADA@CD-mPEG nanoparticle could be considered a potential candidate with high drug loading capacity and a lower risk of systemic toxicity.

  13. Acoustic properties of a porous glass (vycor) at hypersonic frequencies

    International Nuclear Information System (INIS)

    Levelut, C; Pelous, J

    2007-01-01

    Brillouin scattering experiments have been performed from 5 to 1600 K in vycor, a porous silica glass. The acoustic velocity and attenuation at hypersonic frequencies are compared to those of bulk silica and others porous silica samples. The experimental evidence for the influence of porosity on the scattering by acoustic waves is compared to calculations. The correlation between internal friction and thermal conductivity at low temperature is discussed

  14. Experiences with the ALICE Mesos infrastructure

    Science.gov (United States)

    Berzano, D.; Eulisse, G.; Grigoraş, C.; Napoli, K.

    2017-10-01

    Apache Mesos is a resource management system for large data centres, initially developed by UC Berkeley, and now maintained under the Apache Foundation umbrella. It is widely used in the industry by companies like Apple, Twitter, and Airbnb and it is known to scale to 10 000s of nodes. Together with other tools of its ecosystem, such as Mesosphere Marathon or Metronome, it provides an end-to-end solution for datacenter operations and a unified way to exploit large distributed systems. We present the experience of the ALICE Experiment Offline & Computing in deploying and using in production the Apache Mesos ecosystem for a variety of tasks on a small 500 cores cluster, using hybrid OpenStack and bare metal resources. We will initially introduce the architecture of our setup and its operation, we will then describe the tasks which are performed by it, including release building and QA, release validation, and simple Monte Carlo production. We will show how we developed Mesos enabled components (called “Mesos Frameworks”) to carry out ALICE specific needs. In particular, we will illustrate our effort to integrate Work Queue, a lightweight batch processing engine developed by University of Notre Dame, which ALICE uses to orchestrate release validation. Finally, we will give an outlook on how to use Mesos as resource manager for DDS, a software deployment system developed by GSI which will be the foundation of the system deployment for ALICE next generation Online-Offline (O2).

  15. Study of the influence of humic acids (in solution or bound to a silica gel) on the migration of europium in a porous medium. Comparison with inorganic colloids

    International Nuclear Information System (INIS)

    Fleury, Ch.

    1998-01-01

    After having been reprocessed, radioactive wastes are stored in conditions which depend on the toxicity of the radioelements. In particular, for the actinides, the packaging has to be sure for several thousands years. In the case of a defective storage, phenomena which favour or diminish the migration of radioelements in the environment have to be identified. In water, organic or inorganic colloids able to bind radioelements can migrate. Among these colloids, are found the humic acids (HA), macromolecules (poly-electrolytes and poly-dispersed) known for their affinity towards some radioelements. These HA are either present on a soluble state or bound to mineral supports. Humic acids have then been studied in these two states and their influence on the europium migration in dynamical system have been observed (ion exchange and affinity chromatography). When HA are bound by covalent bonds to silica gel, they strongly retain the radioelement, whatever be the conditions of pH, flow rate or ionic strength, and either if phosphate ions are present. The study of HA in solution has shown that, on the one hand the formation of a Eu-HA complex alters the adsorption of the radioelement on sand and that the influence of the humic acids on the europium retention is superior to those of the inorganic colloids (silicon oxide, bentonite). On the other hand, the study has revealed that a solution containing HA desorbs almost entirely the europium beforehand bound to the sand. This desorption depends on the pH and on the flow rate but not on the presence of competitive ions as for instance phosphate ions. (O.M.)

  16. Electric double layer capacitance on hierarchical porous carbons in an organic electrolyte

    OpenAIRE

    Yamada, Hirotoshi; Moriguchi, Isamu; Kudo, Tetsuichi

    2008-01-01

    Nanoporous carbons were prepared by using colloidal crystal as a template. Nitrogen adsorption/desorption isotherms and transmission electron microscope images revealed that the porous carbons exhibit hierarchical porous structures with meso/macropores and micropores. Electric double layer capacitor performance of the porous carbons was investigated in an organic electrolyte of 1 M LiClO4 in propylene carbonate and dimethoxy ethane. The hierarchical porous carbons exhibited large specific dou...

  17. Enhanced microcontact printing of proteins on nanoporous silica surface

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-10-15

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

  18. Fabrication of hierarchical porous N-doping carbon membrane by using ;confined nanospace deposition; method for supercapacitor

    Science.gov (United States)

    Wang, Guoxu; Liu, Meng; Du, Juan; Liu, Lei; Yu, Yifeng; Sha, Jitong; Chen, Aibing

    2018-03-01

    The membrane carbon materials with hierarchical porous architecture are attractive because they can provide more channels for ion transport and shorten the ions transport path. Herein, we develop a facile way based on "confined nanospace deposition" to fabricate N-dopi-ng three dimensional hierarchical porous membrane carbon material (N-THPMC) via coating the nickel nitrate, silicate oligomers and triblock copolymer P123 on the branches of commercial polyamide membrane (PAM). During high temperature treatment, the mesoporous silica layer and Ni species serve as a "confined nanospace" and catalyst respectively, which are indispensable elements for formation of carbon framework, and the gas-phase carbon precursors which derive from the decomposition of PAM are deposited into the "confined nanospace" forming carbon framework. The N-THPMC with hierarchical macro/meso/microporous structure, N-doping (2.9%) and large specific surface area (994m2 g-1) well inherits the membrane morphology and hierarchical porous structure of PAM. The N-THPMC as electrode without binder exhibits a specific capacitance of 252 F g-1 at the current density of 1 A g-1 in 6 M KOH electrolyte and excellent cycling stability of 92.7% even after 5000 cycles.

  19. Optimizing CMS build infrastructure via Apache Mesos

    CERN Document Server

    Abduracmanov, David; Degano, Alessandro; Elmer, Peter; Eulisse, Giulio; Mendez, David; Muzaffar, Shahzad

    2015-12-23

    The Offline Software of the CMS Experiment at the Large Hadron Collider (LHC) at CERN consists of 6M lines of in-house code, developed over a decade by nearly 1000 physicists, as well as a comparable amount of general use open-source code. A critical ingredient to the success of the construction and early operation of the WLCG was the convergence, around the year 2000, on the use of a homogeneous environment of commodity x86-64 processors and Linux. Apache Mesos is a cluster manager that provides efficient resource isolation and sharing across distributed applications, or frameworks. It can run Hadoop, Jenkins, Spark, Aurora, and other applications on a dynamically shared pool of nodes. We present how we migrated our continuos integration system to schedule jobs on a relatively small Apache Mesos enabled cluster and how this resulted in better resource usage, higher peak performance and lower latency thanks to the dynamic scheduling capabilities of Mesos.

  20. Meso-Decorated Switching-Knot Gels

    Science.gov (United States)

    Gong, Jin; Sawamura, Kensuke; Makino, Masato; Kabir, M. H.; Furukawa, Hidemitsu

    Gels are a new material having three-dimensional network structures of macromolecules. They possess excellent properties as swellability, high permeability and biocompatibility, and have been applied in various fields of daily life, food, medicine, architecture, and chemistry .In this study, we tried to prepare new multi-functional and high-strength gels by using Meso-Decoration (Meso-Deco), one new method of structure design at intermediate mesoscale. High-performance rigid-rod aromatic polymorphic crystals. The strengthening of gels can be realized by meso-decorating the gels' structure using high-performance polymorphic crystals. New gels with good mechanical properties, novel optical properties and thermal properties are expected to be developed.

  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. Silica- and silylated europium-based luminescent hybrids: new analysis tools for biological environments

    International Nuclear Information System (INIS)

    Pereira Duarte, Adriana

    2012-01-01

    The association of the very interesting luminescence properties of the lanthanide chelates with the physicochemical properties of inorganic matrix such as silica is a promising way to obtain new probes or luminescent markers for biology analyses. In this idea, this work focuses on the preparation of new hybrid materials based on the grafting of new europium(III) complexes on silica nanoparticles. These europium complexes were developed in our group using bifunctional ligands containing both complexing and grafting sites. Intrinsic characteristic of the ligands gives us the ability to make a covalent bond between the material surface and the complex. Two different methodologies were used; the first one is the direct grafting reaction involving the complex and silica nanoparticles (i.e. dense or meso-porous particles). The second one is the Stoeber reaction, where the SiO 2 nanoparticles were prepared in presence of the europium complex. The last methodology has an additional difficult, because of the presence of silylated europium complex, it needs a closer control of the physicochemical conditions. The new organic-inorganic hybrid materials, obtained in this work, present an interesting luminescence behavior and this one is depending on the localization of the europium complex, i.e. on the surface or within the nanoparticles. In addition, the obtained hybrids present the nano-metric dimension and the complex is not leachable. Analyses were realized to describe the luminescence properties, beyond surface and structural characteristics. Initial results show that the new hybrids are promising candidates for luminescent bio-markers, particularly for the time-resolved analysis. (author) [fr

  3. complexes based on meso-substituted dipyrrins

    Indian Academy of Sciences (India)

    Keywords. Coordination polymers; meso-substituted dipyrrins; heteroleptic; acetylacetonato; ... Room temperature magnetic susceptibility measurements were ... After cooling to ambient tem- perature it ... crystals of 1 were obtained from CH2Cl2/ hexane (1. : 1) solution. .... are air-stable, crystalline solids, soluble in common.

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

    Directory of Open Access Journals (Sweden)

    Masako Miki

    2013-12-01

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

  5. Mass transport in thin supported silica membranes

    NARCIS (Netherlands)

    Benes, Nieck Edwin

    2000-01-01

    In this thesis multi-component mass transport in thin supported amorphous silica membranes is discussed. These membranes are micro-porous, with pore diameters smaller than 4Å and show high fluxes for small molecules (such as hydrogen) combined with high selectivities for these molecules with respect

  6. Positronium chemistry in porous materials

    International Nuclear Information System (INIS)

    Kobayashi, Y.; Ito, K.; Oka, T.; Hirata, K.

    2007-01-01

    Porous materials have fascinated positron and positronium chemists for over decades. In the early 1970s it was already known that ortho-positronium (o-Ps) exhibits characteristic long lifetimes in silica gels, porous glass and zeolites. Since then, our understanding of Ps formation, diffusion and annihilation has been drastically deepened. Ps is now well recognized as a powerful porosimetric and chemical probe to study the average pore size, pore size distribution, pore connectivity and surface properties of various porous materials including thin films. In this paper, developments of Ps chemistry in porous materials undertaken in the past some 40 yr are surveyed and problems to be addressed in future are briefly discussed

  7. A facile approach for the synthesis of monolithic hierarchical porous carbons – high performance materials for amine based CO2 capture and supercapacitor electrode

    KAUST Repository

    Estevez, Luis; Dua, Rubal; Bhandari, Nidhi; Ramanujapuram, Anirudh; Wang, Peng; Giannelis, Emmanuel P.

    2013-01-01

    An ice templating coupled with hard templating and physical activation approach is reported for the synthesis of hierarchically porous carbon monoliths with tunable porosities across all three length scales (macro- meso- and micro), with ultrahigh

  8. Porous silicon technology for integrated microsystems

    Science.gov (United States)

    Wallner, Jin Zheng

    With the development of micro systems, there is an increasing demand for integrable porous materials. In addition to those conventional applications, such as filtration, wicking, and insulating, many new micro devices, including micro reactors, sensors, actuators, and optical components, can benefit from porous materials. Conventional porous materials, such as ceramics and polymers, however, cannot meet the challenges posed by micro systems, due to their incompatibility with standard micro-fabrication processes. In an effort to produce porous materials that can be used in micro systems, porous silicon (PS) generated by anodization of single crystalline silicon has been investigated. In this work, the PS formation process has been extensively studied and characterized as a function of substrate type, crystal orientation, doping concentration, current density and surfactant concentration and type. Anodization conditions have been optimized for producing very thick porous silicon layers with uniform pore size, and for obtaining ideal pore morphologies. Three different types of porous silicon materials: meso porous silicon, macro porous silicon with straight pores, and macro porous silicon with tortuous pores, have been successfully produced. Regular pore arrays with controllable pore size in the range of 2mum to 6mum have been demonstrated as well. Localized PS formation has been achieved by using oxide/nitride/polysilicon stack as masking materials, which can withstand anodization in hydrofluoric acid up to twenty hours. A special etching cell with electrolytic liquid backside contact along with two process flows has been developed to enable the fabrication of thick macro porous silicon membranes with though wafer pores. For device assembly, Si-Au and In-Au bonding technologies have been developed. Very low bonding temperature (˜200°C) and thick/soft bonding layers (˜6mum) have been achieved by In-Au bonding technology, which is able to compensate the potentially

  9. Porous Materials from Thermally Activated Kaolinite: Preparation, Characterization and Application

    Directory of Open Access Journals (Sweden)

    Jun Luo

    2017-06-01

    Full Text Available In the present study, porous alumina/silica materials were prepared by selective leaching of silicon/aluminum constituents from thermal-activated kaolinite in inorganic acid or alkali liquor. The correlations between the characteristics of the prepared porous materials and the dissolution properties of activated kaolinite were also investigated. The results show that the specific surface area (SSA of porous alumina/silica increases with silica/alumina dissolution, but without marked change of the BJH pore size. Furthermore, change in pore volume is more dependent on activation temperature. The porous alumina and silica obtained from alkali leaching of kaolinite activated at 1150 °C for 15 min and acid leaching of kaolinite activated at 850 °C for 15 min are mesoporous, with SSAs, BJH pore sizes and pore volumes of 55.8 m2/g and 280.3 m2/g, 6.06 nm and 3.06 nm, 0.1455 mL/g and 0.1945 mL/g, respectively. According to the adsorption tests, porous alumina has superior adsorption capacities for Cu2+, Pb2+ and Cd2+ compared with porous silica and activated carbon. The maximum capacities of porous alumina for Cu2+, Pb2+ and Cd2+ are 134 mg/g, 183 mg/g and 195 mg/g, respectively, at 30 °C.

  10. Las comunidades locales como estructuras meso.

    Directory of Open Access Journals (Sweden)

    Ferrand, Alexis

    2002-09-01

    Full Text Available Entre el nivel micro y el nivel macro: meso. Si el nivel macro está definido por la regulación nacional, estatal o del mercado y el nivel micro por la regulación interpersonal, una agencia de regulación intermediaria de mayor importancia ha sido definida como “comunidad local” (Wellman, Fischer. Aparte de las dimensiones organizacionales (organizaciones locales, clubes, tiendas... e institucionales (poder local, partidos... locales, es posible definir algunas propiedades estructurales pertinentes de los sistemas de relaciones interpersonales privadas: uno es el grado de “cerrado” (closure local (Barnes: redes locales vs. transversales, o la “dualidad” de estos sistemas. Apoyándose en la idea de que la eficiencia de los “puentes” reside en el tipo de cliques que conectan (Lin, es posible definir tipos variados de micro-estructuras, cuyas distribuciones en diferentes localidades son indicadores sucedáneos o aproximaciones de las diferentes meso estructuras de sistemas relacionales como combinaciones de redes “locales” y “no locales”.

  11. Mathematical model and calculation algorithm of micro and meso levels of separation process of gaseous mixtures in molecular sieves

    Energy Technology Data Exchange (ETDEWEB)

    Umarova, Zhanat; Botayeva, Saule; Yegenova, Aliya; Usenova, Aisaule [South Kazakhstan State University, 5, Tauke Khan Avenue, 160012 Shymkent (Kazakhstan)

    2015-05-15

    In the given article, the main thermodynamic aspects of the issue of modeling diffusion transfer in molecular sieves have been formulated. Dissipation function is used as a basic notion. The differential equation, connecting volume flow with the change of the concentration of catchable component has been derived. As a result, the expression for changing the concentration of the catchable component and the coefficient of membrane detecting has been received. As well, the system approach to describing the process of gases separation in ultra porous membranes has been realized and micro and meso-levels of mathematical modeling have been distinguished. The non-ideality of the shared system is primarily taken into consideration at the micro-level and the departure from the diffusion law of Fick has been taken into account. The calculation method of selectivity considering fractal structure of membranes has been developed at the meso level. The calculation algorithm and its software implementation have been suggested.

  12. Mathematical model and calculation algorithm of micro and meso levels of separation process of gaseous mixtures in molecular sieves

    International Nuclear Information System (INIS)

    Umarova, Zhanat; Botayeva, Saule; Yegenova, Aliya; Usenova, Aisaule

    2015-01-01

    In the given article, the main thermodynamic aspects of the issue of modeling diffusion transfer in molecular sieves have been formulated. Dissipation function is used as a basic notion. The differential equation, connecting volume flow with the change of the concentration of catchable component has been derived. As a result, the expression for changing the concentration of the catchable component and the coefficient of membrane detecting has been received. As well, the system approach to describing the process of gases separation in ultra porous membranes has been realized and micro and meso-levels of mathematical modeling have been distinguished. The non-ideality of the shared system is primarily taken into consideration at the micro-level and the departure from the diffusion law of Fick has been taken into account. The calculation method of selectivity considering fractal structure of membranes has been developed at the meso level. The calculation algorithm and its software implementation have been suggested

  13. Ordered mesoporous silica materials with complicated structures

    KAUST Repository

    Han, Yu

    2012-05-01

    Periodically ordered mesoporous silicas constitute one of the most important branches of porous materials that are extensively employed in various chemical engineering applications including adsorption, separation and catalysis. This short review gives an introduction to recently developed mesoporous silicas with emphasis on their complicated structures and synthesis mechanisms. In addition, two powerful techniques for solving complex mesoporous structures, electron crystallography and electron tomography, are compared to elucidate their respective strength and limitations. Some critical issues and challenges regarding the development of novel mesoporous structures as well as their applications are also discussed. © 2011 Elsevier Ltd.

  14. LHCbDIRAC as Apache Mesos microservices

    CERN Multimedia

    Couturier, Ben

    2016-01-01

    The LHCb experiment relies on LHCbDIRAC, an extension of DIRAC, to drive its offline computing. This middleware provides a development framework and a complete set of components for building distributed computing systems. These components are currently installed and ran on virtual machines (VM) or bare metal hardware. Due to the increased load of work, high availability is becoming more and more important for the LHCbDIRAC services, and the current installation model is showing its limitations. Apache Mesos is a cluster manager which aims at abstracting heterogeneous physical resources on which various tasks can be distributed thanks to so called "framework". The Marathon framework is suitable for long running tasks such as the DIRAC services, while the Chronos framework meets the needs of cron-like tasks like the DIRAC agents. A combination of the service discovery tool Consul together with HAProxy allows to expose the running containers to the outside world while hiding their dynamic placements. Such an arc...

  15. Meso-scale wind variability. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Larsen, S.; Larsen, X.; Vincent, C.; Soerensen, P.; Pinson, P.; Trombe, P.-J.; Madsen, H.; Cutululis, N.

    2011-11-15

    The project has aimed to characterize mesoscale meteorological phenomenon for the North Sea and the Inner Danish waters, and additionally aimed on improving the predictability and quality of the power production from offshore windfarms. The meso-scale meteorology has been characterized with respect to the physical processes, climatology, spectral characteristics and correlation properties based on measurements from wind farms, satellite data (SAR) and mesoscale numerical modeling (WRF). The abilities of the WRF model to characterize and predict relevant mesoscale phenomenon has been proven. Additionally application of statistical forecasting, using a Markov switching approach that can be related to the meteorological conditions, to analyze and short term predict the power production from an offshore wind farms have been documented. Two PhD studies have been conducted in connection with the project. The project has been a cooperative project between Risoe DTU, IMM DTU, DONG Energy, Vattenfall and VESTAS. It is registered as Energinet.dk, project no. 2007-1-7141. (Author)

  16. Probabilistic, meso-scale flood loss modelling

    Science.gov (United States)

    Kreibich, Heidi; Botto, Anna; Schröter, Kai; Merz, Bruno

    2016-04-01

    Flood risk analyses are an important basis for decisions on flood risk management and adaptation. However, such analyses are associated with significant uncertainty, even more if changes in risk due to global change are expected. Although uncertainty analysis and probabilistic approaches have received increased attention during the last years, they are still not standard practice for flood risk assessments and even more for flood loss modelling. State of the art in flood loss modelling is still the use of simple, deterministic approaches like stage-damage functions. Novel probabilistic, multi-variate flood loss models have been developed and validated on the micro-scale using a data-mining approach, namely bagging decision trees (Merz et al. 2013). In this presentation we demonstrate and evaluate the upscaling of the approach to the meso-scale, namely on the basis of land-use units. The model is applied in 19 municipalities which were affected during the 2002 flood by the River Mulde in Saxony, Germany (Botto et al. submitted). The application of bagging decision tree based loss models provide a probability distribution of estimated loss per municipality. Validation is undertaken on the one hand via a comparison with eight deterministic loss models including stage-damage functions as well as multi-variate models. On the other hand the results are compared with official loss data provided by the Saxon Relief Bank (SAB). The results show, that uncertainties of loss estimation remain high. Thus, the significant advantage of this probabilistic flood loss estimation approach is that it inherently provides quantitative information about the uncertainty of the prediction. References: Merz, B.; Kreibich, H.; Lall, U. (2013): Multi-variate flood damage assessment: a tree-based data-mining approach. NHESS, 13(1), 53-64. Botto A, Kreibich H, Merz B, Schröter K (submitted) Probabilistic, multi-variable flood loss modelling on the meso-scale with BT-FLEMO. Risk Analysis.

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

    International Nuclear Information System (INIS)

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

    2006-01-01

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

  18. Preparation of tailored carbons with meso- and micro- porosity via template synthesis route

    Directory of Open Access Journals (Sweden)

    Howard. M. Williams

    2009-02-01

    Full Text Available A low cost templating approach to making non-ordered carbons with a tailored meso/micropore structure is described. A series of mesoporous carbons was prepared from polyfurfuryl alcohol and phenolic resin precursors by a templating route, using a variety of commercially available silica gels as the template material. Carbons were produced with mesopore volumes up to 1 cm3 g-1, mesopore sizes in the range of 4 nm to 8 nm and surface areas in the range of 300 to 700 m2 g-1. These mesoporous carbons were subsequently activated in CO2 to add controlled amounts of microporosity to produce carbons with both a micro and mesoporous structure. Significantly, the activation process did not appreciably change the mesopore size distribution of the carbons. By altering the activation time, it was possible to tailor the micropore: mesopore volume ratios within wide limits.

  19. Porous carbons

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    Abstract. Carbon in dense as well as porous solid form is used in a variety of applications. Activated porous carbons are made through pyrolysis and activation of carbonaceous natural as well as synthetic precursors. Pyrolysed woods replicate the structure of original wood but as such possess very low surface areas and ...

  20. LHCbDIRAC as Apache Mesos microservices

    Science.gov (United States)

    Haen, Christophe; Couturier, Benjamin

    2017-10-01

    The LHCb experiment relies on LHCbDIRAC, an extension of DIRAC, to drive its offline computing. This middleware provides a development framework and a complete set of components for building distributed computing systems. These components are currently installed and run on virtual machines (VM) or bare metal hardware. Due to the increased workload, high availability is becoming more and more important for the LHCbDIRAC services, and the current installation model is showing its limitations. Apache Mesos is a cluster manager which aims at abstracting heterogeneous physical resources on which various tasks can be distributed thanks to so called “frameworks” The Marathon framework is suitable for long running tasks such as the DIRAC services, while the Chronos framework meets the needs of cron-like tasks like the DIRAC agents. A combination of the service discovery tool Consul together with HAProxy allows to expose the running containers to the outside world while hiding their dynamic placements. Such an architecture brings a greater flexibility in the deployment of LHCbDirac services, allowing for easier deployment maintenance and scaling of services on demand (e..g LHCbDirac relies on 138 services and 116 agents). Higher reliability is also easier, as clustering is part of the toolset, which allows constraints on the location of the services. This paper describes the investigations carried out to package the LHCbDIRAC and DIRAC components into Docker containers and orchestrate them using the previously described set of tools.

  1. Verification of Meso-Zeaxanthin in Fish

    Science.gov (United States)

    Nolan, John M; Beatty, Stephen; Meagher, Katie A; Howard, Alan N; Kelly, David; Thurnham, David I

    2015-01-01

    Background/Objectives The carotenoids lutein (L), zeaxanthin (Z), and meso-zeaxanthin (MZ) accumulate in the central retina (the macula), where they are collectively known as macular pigment (MP). MP has been shown to enhance visual function in both diseased and non-diseased retinae, and therefore an understanding and confirmation of, the origins of these carotenoids is needed. Studies have shown that L and Z are present in many foodstuffs found in a typical Western diet (e.g. spinach, kale, peppers, yellow corn and eggs). It has been shown that MZ is generated from L in the primate retina and earlier reports suggested that MZ was present in some fish species. Recently, however, one research group reported that MZ is not present in fish and suggested that the earlier reports showing MZ in these marine species were a methodological artefact. The current study was designed to investigate the reason for the contradiction, and test for the presence of MZ in fish and some other foods. Methods Raw fruits, vegetables and fish were extracted for carotenoid analysis by high performance liquid chromatography. Results MZ was not detected in any of the fruits or vegetables tested in our study. However, using retention time matching, absorption spectrum comparison, and sample spiking, we verified the presence of MZ in salmon skin, sardine skin, trout skin and trout flesh. Conclusion This study confirmed the presence MZ in nature, and in the human food chain. PMID:25717420

  2. Unifying Inference of Meso-Scale Structures in Networks.

    Science.gov (United States)

    Tunç, Birkan; Verma, Ragini

    2015-01-01

    Networks are among the most prevalent formal representations in scientific studies, employed to depict interactions between objects such as molecules, neuronal clusters, or social groups. Studies performed at meso-scale that involve grouping of objects based on their distinctive interaction patterns form one of the main lines of investigation in network science. In a social network, for instance, meso-scale structures can correspond to isolated social groupings or groups of individuals that serve as a communication core. Currently, the research on different meso-scale structures such as community and core-periphery structures has been conducted via independent approaches, which precludes the possibility of an algorithmic design that can handle multiple meso-scale structures and deciding which structure explains the observed data better. In this study, we propose a unified formulation for the algorithmic detection and analysis of different meso-scale structures. This facilitates the investigation of hybrid structures that capture the interplay between multiple meso-scale structures and statistical comparison of competing structures, all of which have been hitherto unavailable. We demonstrate the applicability of the methodology in analyzing the human brain network, by determining the dominant organizational structure (communities) of the brain, as well as its auxiliary characteristics (core-periphery).

  3. Unifying Inference of Meso-Scale Structures in Networks.

    Directory of Open Access Journals (Sweden)

    Birkan Tunç

    Full Text Available Networks are among the most prevalent formal representations in scientific studies, employed to depict interactions between objects such as molecules, neuronal clusters, or social groups. Studies performed at meso-scale that involve grouping of objects based on their distinctive interaction patterns form one of the main lines of investigation in network science. In a social network, for instance, meso-scale structures can correspond to isolated social groupings or groups of individuals that serve as a communication core. Currently, the research on different meso-scale structures such as community and core-periphery structures has been conducted via independent approaches, which precludes the possibility of an algorithmic design that can handle multiple meso-scale structures and deciding which structure explains the observed data better. In this study, we propose a unified formulation for the algorithmic detection and analysis of different meso-scale structures. This facilitates the investigation of hybrid structures that capture the interplay between multiple meso-scale structures and statistical comparison of competing structures, all of which have been hitherto unavailable. We demonstrate the applicability of the methodology in analyzing the human brain network, by determining the dominant organizational structure (communities of the brain, as well as its auxiliary characteristics (core-periphery.

  4. Synthesis of eccentric titania-silica core-shell and composite particles

    NARCIS (Netherlands)

    Demirors, A.F.; van Blaaderen, A.; Imhof, A.

    2009-01-01

    We describe a novel method to synthesize colloidal particles with an eccentric core-shell structure. Titania-silica core-shell particles were synthesized by silica coating of porous titania particles under Sto¨ber (Sto¨ber et al. J. Colloid Interface Sci. 1968, 26, 62) conditions. We can control

  5. Supramolecular structures on silica surfaces and their adsorptive properties.

    Science.gov (United States)

    Belyakov, Vladimir N; Belyakova, Lyudmila A; Varvarin, Anatoly M; Khora, Olexandra V; Vasilyuk, Sergei L; Kazdobin, Konstantin A; Maltseva, Tetyana V; Kotvitskyy, Alexey G; Danil de Namor, Angela F

    2005-05-01

    The study of adsorptive and chemical immobilization of beta-cyclodextrin on a surface of hydroxylated silicas with various porous structure is described. Using IR spectroscopy, thermal gravimetrical analysis with a programmed heating, and chemical analysis of the silica surface, it is shown that the process of adsorption-desorption of beta-cyclodextrin depends on the porous structure of the silica. The reaction of esterification was used for chemical grafting of beta-cyclodextrin on the surface of hydroxylated silicas. Hydrolytic stability of silicas chemically modified by beta-cyclodextrin apparently is explained by simultaneous formation of chemical and hydrogen bonds between surface silanol groups and hydroxyl groups of beta-cyclodextrin. The uptake of the cations Cu(II), Cd(II), and Pb(II) and the anions Cr(VI) and As(V) by silicas modified with beta-cyclodextrin is investigated as a function of equilibrium ion concentrations. The increase of ion uptake and selectivity of ion extraction in comparison with starting silicas is established. It is due to the formation of surface inclusion complexes of the "host-guest" type in which one molecule of beta-cyclodextrin interacts simultaneously with several ions.

  6. Fabrication of keratin-silica hydrogel for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-09-01

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

  7. Impact of Micro Silica Surface Hydroxyl Groups on the Properties of Calcium Silicate Products

    DEFF Research Database (Denmark)

    Haastrup, Sonja; Jørgensen, Bianca; Yu, Donghong

    2017-01-01

    Porous calcium silicates are widely used in insulating systems for high temperature applications. In the production of porous calcium silicates, quicklime and micro silica have been utilized as key raw materials. In the reaction between SiO2 and CaO, the dissolution of SiO2 has been proven...

  8. Development of porous structure simulator for multi-scale simulation of irregular porous catalysts

    International Nuclear Information System (INIS)

    Koyama, Michihisa; Suzuki, Ai; Sahnoun, Riadh; Tsuboi, Hideyuki; Hatakeyama, Nozomu; Endou, Akira; Takaba, Hiromitsu; Kubo, Momoji; Del Carpio, Carlos A.; Miyamoto, Akira

    2008-01-01

    Efficient development of highly functional porous materials, used as catalysts in the automobile industry, demands a meticulous knowledge of the nano-scale interface at the electronic and atomistic scale. However, it is often difficult to correlate the microscopic interfacial interactions with macroscopic characteristics of the materials; for instance, the interaction between a precious metal and its support oxide with long-term sintering properties of the catalyst. Multi-scale computational chemistry approaches can contribute to bridge the gap between micro- and macroscopic characteristics of these materials; however this type of multi-scale simulations has been difficult to apply especially to porous materials. To overcome this problem, we have developed a novel mesoscopic approach based on a porous structure simulator. This simulator can construct automatically irregular porous structures on a computer, enabling simulations with complex meso-scale structures. Moreover, in this work we have developed a new method to simulate long-term sintering properties of metal particles on porous catalysts. Finally, we have applied the method to the simulation of sintering properties of Pt on alumina support. This newly developed method has enabled us to propose a multi-scale simulation approach for porous catalysts

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

    KAUST Repository

    Sarawade, Pradip; Shao, Godlistennamwel; Quang, Dangviet; Kim, Heetaik

    2013-01-01

    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.

  10. 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.

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

    Science.gov (United States)

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

    2017-08-01

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

  12. Positronium chemistry in porous adsorbents

    International Nuclear Information System (INIS)

    Foti, G.; Nagy, L.G.; Moravcsik, G.; Schay, G.

    1981-01-01

    Kinetic studies on the annihilation of orthopositronium in porous adsorbents have been performed using lifetime spectroscopy. The positron source applied was 22 Na with 0.2 MBq activity. The adsorbents investigated were silica gels of different particle size and pore structure. The appearance of the long-lived component in the lifetime spectra can be explained by the diffusion of the orthopositronium into the pores affected by the particle size and the pore size of the adsorbent, the coverage on it and the chemical nature of the adsorbate. The long-term aim of the work is to determine and to explain these effects. (author)

  13. Synthesis of Novel Mesoporous Silica Materials with Hierarchical Pore Structures

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Suk Bon; Choi, Wang Kyu; Choi, Byung Seon; Moon, Jei Kwon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2012-05-15

    Porous materials with various pore sizes in the range of micropore (< 2 nm), mesopore (2-50 nm), and macropore (> 50 nm) are attractive due to their many emerging applications such as catalysts, separation systems, and low dielectric constant materials. The discovery of new M41S mesoporous silica families with pore sizes larger than 2 nm in diameter in 1992 extended the applications into much wider pore ranges, bringing in a new prosperous era in porous material research. The synthesis of these silica materials has been mainly accomplished through a self-assembly between surfactant molecules and inorganic species under various pH conditions. Recently, core-shell nanoparticles with a silica core and mesoporous shell under basic conditions were synthesized using the silica nanoparticles as a core, and a silica precursor (TEOS) and cationic surfactant (CTABr) as a material for the formation of the mesoporous shell. The resultant materials were very monodispersive in size and showed a narrow pore size distribution in the range of ca 2-3 nm in diameter, depending on the alkyl-chain length of the surfactants used. In this work, the mesoporous shell coated-fumed silicas (denoted as MS M-5s) were synthesized by using fumed silica instead of the silica nanoparticle as a core based on previous reports. Also, the structural properties of the MS M-5s such as the specific surface area and pore volume were easily controlled by varying the amount of the silica precursor and surfactant. The resultant materials exhibited a BET surface area of ca 279-446 m{sup 2}/g and total pore volume of ca 0.64-0.74 cm{sup 3}/g and showed a narrow pore size distribution (PSD) due to the removal of the organic surfactant molecules

  14. Ordered meso- and macroporous perovskite oxide catalysts for emerging applications

    DEFF Research Database (Denmark)

    Arandiyan, Hamidreza; Wang, Yuan; Sun, Hongyu

    2018-01-01

    This feature article summarizes the recent progress in porous perovskite oxides as advanced catalysts for both energy conversion applications and various heterogeneous reactions. Recently, research has been focused on specifically designing porous perovskite materials so that large surface areas ...

  15. Fractal dimensions of silica gels generated using reactive molecular dynamics simulations

    International Nuclear Information System (INIS)

    Bhattacharya, Sudin; Kieffer, John

    2005-01-01

    We have used molecular dynamics simulations based on a three-body potential with charge transfer to generate nanoporous silica aerogels. Care was taken to reproduce the sol-gel condensation reaction that forms the gel backbone as realistically as possible and to thereby produce credible gel structures. The self-similarity of aerogel structures was investigated by evaluating their fractal dimension from geometric correlations. For comparison, we have also generated porous silica glasses by rupturing dense silica and computed their fractal dimension. The fractal dimension of the porous silica structures was found to be process dependent. Finally, we have determined that the effect of supercritical drying on the fractal nature of condensed silica gels is not appreciable

  16. Innovative preparation of Au/C by replication of gold-containing mesoporous silica catalysts

    KAUST Repository

    Kerdi, Fatmé

    2010-01-01

    A new strategy, based on the nanocasting concept, has been used to prepare gold nanoparticles (NPs) highly dispersed in meso-structured carbons. Gold is first introduced in various functionalized mesostructured silicas (MCM-48 and SBA-15) and particles are formed inside the porosity upon reduction of Au 3+ cations. Silica pores are then impregnated with a carbon precursor and the composite material is heated at 900°C under vacuum. Silica is then removed by acid leaching, leading to partially encapsulated gold particles in mesoporous carbon. Carbon prevents aggregation of gold particles at high temperature, both the mean size and distribution being similar to those observed in silica. However, while Au@SiO2 exhibit significant catalytic activity in the aerobic oxidation of trans-stilbene in the liquid phase, its Au@C mesostructured replica is quite inactive. © 2010 Elsevier B.V. All rights reserved.

  17. Quantitative study on crack of meso-damage and fracture concrete ...

    Indian Academy of Sciences (India)

    lysis of the meso-fracture process of concrete materials is performed. ... the result of the accumulation and development of damage and cracks at the meso-level. ... characteristics of concrete under uniaxial compression used fractal theory, and ...

  18. Preparation of porous materials for radionuclides capture

    International Nuclear Information System (INIS)

    Bajzikova, Anna; Smrcek, Stanislav; Kozempel, Jan; Vlk, Martin; Barta, Jan

    2015-01-01

    Porous materials showing promise for radionuclide capture from water at contaminated sites were prepared. Nanoporous materials (size of pores 1-100 nm) and some polymers are well suited to this purpose owing their affinity for selected radionuclides. Nanoporous metal oxides and silica gel with styrene-divinylbenzene-TODGA-modified surface were prepared, characterized and tested for radionuclide ( 227 Ac, 227 Th, 223 Ra) capture efficiency. (orig.)

  19. Ordered silica particles made by nonionic surfactant for VOCs sorption

    Energy Technology Data Exchange (ETDEWEB)

    Difallah, Oumaima; Hamaizi, Hadj, E-mail: hamaizimizou@yahoo.fr [University of Oran, OranMenaouer (Algeria); Amate, Maria Dolores Urena; Socias-Viciana, Maria Del Mar [University of Almeria (Spain)

    2017-07-15

    Adsorption of light organic compounds such acetone, 1-propanol and carbon dioxide was tested by using mesoporous silica materials made from non ionic surfactant with long chain and silica sources as tetraethyl orthosilicate TEOS and modified Na-X and Li-A Zeolites. X-ray powder diffraction (XRD), nitrogen adsorption-desorption analysis and scanning electron microscopy (SEM) were applied to characterize the silica particles of a variety prepared samples. Acetone, 1-propanol and CO{sub 2} adsorption at 298K was evaluated by a volumetric method and indicate a high sorption capacity of organic compounds depending essentially on the porous texture of adsorbents. An adsorption kinetic model was proposed to describe the adsorption of VOCs over template-free mesoporous silica materials. A good agreement with experimental data was found. (author)

  20. Optogenetic stimulation of a meso-scale human cortical model

    Science.gov (United States)

    Selvaraj, Prashanth; Szeri, Andrew; Sleigh, Jamie; Kirsch, Heidi

    2015-03-01

    Neurological phenomena like sleep and seizures depend not only on the activity of individual neurons, but on the dynamics of neuron populations as well. Meso-scale models of cortical activity provide a means to study neural dynamics at the level of neuron populations. Additionally, they offer a safe and economical way to test the effects and efficacy of stimulation techniques on the dynamics of the cortex. Here, we use a physiologically relevant meso-scale model of the cortex to study the hypersynchronous activity of neuron populations during epileptic seizures. The model consists of a set of stochastic, highly non-linear partial differential equations. Next, we use optogenetic stimulation to control seizures in a hyperexcited cortex, and to induce seizures in a normally functioning cortex. The high spatial and temporal resolution this method offers makes a strong case for the use of optogenetics in treating meso scale cortical disorders such as epileptic seizures. We use bifurcation analysis to investigate the effect of optogenetic stimulation in the meso scale model, and its efficacy in suppressing the non-linear dynamics of seizures.

  1. Meso-level analysis, the missing link in energy strategies

    International Nuclear Information System (INIS)

    Schenk, Niels J.; Moll, Henri C.; Schoot Uiterkamp, Anton J.M.

    2007-01-01

    Energy is essential for human societies. Energy systems, though, are also associated with several adverse environmental effects. So far societies have been unable to successfully change their energy systems in a way that addresses environmental and health concerns. Lack of policy consensus often resulted in so-called 'stop-go' policies, which were identified as some of the most important barriers regarding successful energy transitions. The lack of policy consensus and coherent long-term strategies may result from a lack of knowledge of energy systems' meso-level dynamics. The meso-level involves the dynamic behaviour of the individual system elements and the coupling of individual technologies, resulting in interdependencies and regimes. Energy systems are at the meso-level characterised by two typical aspects, i.e. dynamics driven by interactions between actors, and heterogeneous characteristics of actors. These aspects give rise to the ineffectiveness of traditional energy policies, which is illustrated with examples from the transport sector and household electricity consumption. We found that analysis of energy systems at the meso-level helps to better understand energy systems. To resolve persistent policy issues, the traditional 'one size fits all' energy policies are not sufficient. In order to tackle the difficult issues, 'redesign of system organisation', 'target group approach', or 'target group induced system re-orientation' are needed

  2. Onset of meso-scale turbulence in active nematics

    NARCIS (Netherlands)

    Doostmohammadi, A.; Shendruk, T.N.; Thijssen, K.; Yeomans, J.M.

    2017-01-01

    Meso-scale turbulence is an innate phenomenon, distinct from inertial turbulence, that spontaneously occurs at low Reynolds number in fluidized biological systems. This spatiotemporal disordered flow radically changes nutrient and molecular transport in living fluids and can strongly affect the

  3. Guanidine-catalyzed enantioselective desymmetrization of meso-aziridines

    KAUST Repository

    Zhang, Yan

    2011-01-01

    An amino-indanol derived chiral guanidine was developed as an efficient Brønsted base catalyst for the desymmetrization of meso-aziridines with both thiols and carbamodithioic acids as nucleophiles, which provided 1,2-difunctionalized ring-opened products in high yields and enantioselectivities. © The Royal Society of Chemistry.

  4. LSP Studies As a Quest For Meso-Level Regularities

    DEFF Research Database (Denmark)

    Engberg, Jan

    2015-01-01

    the suggested type of analysis. I proceed to present Knowledge Communication as theoretical-methodological framework of such analyses, followed by a presentation of the differences between a micro, a macro and a meso level approach to studying specialized communication. In the last part of the paper, I...

  5. Synthesis and characterization of new meso-substituted ...

    Indian Academy of Sciences (India)

    WINTEC

    tems. 10. Their ability to carry out the reactions rather unusual in organic chemistry has been the object of intensive investigations aiming to utilize them as a model compounds for biological systems and as catalysts. 11. Therefore, the synthesis of well defined meso-substituted unsymmetrical porphyrin deriva- tives (A3B) is ...

  6. 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.

  7. 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....

  8. Sugarcane bagasse lignin, and silica gel and magneto-silica as drug vehicles for development of innocuous methotrexate drug against rheumatoid arthritis disease in albino rats

    Energy Technology Data Exchange (ETDEWEB)

    Wahba, Sanaa M.R. [Zoology department, Women College, Ain-Shams University,11566 Cairo (Egypt); Darwish, Atef S., E-mail: atef_mouharam@sci.asu.edu.eg [Chemistry department, Faculty of Science, Ain Shams University, Cairo (Egypt); Shehata, Iman H. [Microbiology and Immunology Department, Faculty of Medicine, Ain-Shams University, Cairo (Egypt); Abd Elhalem, Sahar S. [Zoology department, Women College, Ain-Shams University,11566 Cairo (Egypt)

    2015-03-01

    The present study clarifies co-therapy action of deliveries from their textural changes point of view. Methotrexate (MTX) was immobilized onto biodegradable lignin, silica gel and iron/silica nanocomposite. Loaded-MTX was i.p. injected into albino rats at doses of 0.25 and 0.5 mg/kg/week for 2.5 months, after which spleen, liver, testes and knee joint tissues were collected for tests. IFN-γ and IL-17A mRNA gene expressions in spleen in all biological samples were determined by RT-PCR. Physicochemical features of drug carriers were monitored by XRD, BET-PSD, SEM and TEM. Drug inflammatory-site targeting was found to be closely related to the physico-features of deliverers. The interlayered lignin of micro- and meso-pore channels directed MTX toward concealed infected cells in liver and testes tissues, while meso-structured silica flacks satisfied by gathering MTX around knee joints. The magneto-silica nanocomposite targeted MTX toward spleen tissue, which is considered as a lively factory for the production of electron rich compounds. - Highlights: • Opening the door to synthesize smart targeted drug deliveries against RA disease • Therapy action of MTX-laden lignin and Fe{sub 3}O{sub 4}/SiO{sub 2} composite toward RA disease • Procure selective targeted drug deliveries of near 100% curing against RA disease • Revolutionary clinical therapies for RA disease by inventive MTX-delivery models.

  9. Sugarcane bagasse lignin, and silica gel and magneto-silica as drug vehicles for development of innocuous methotrexate drug against rheumatoid arthritis disease in albino rats.

    Science.gov (United States)

    Wahba, Sanaa M R; Darwish, Atef S; Shehata, Iman H; Abd Elhalem, Sahar S

    2015-03-01

    The present study clarifies co-therapy action of deliveries from their textural changes point of view. Methotrexate (MTX) was immobilized onto biodegradable lignin, silica gel and iron/silica nanocomposite. Loaded-MTX was i.p. injected into albino rats at doses of 0.25 and 0.5mg/kg/week for 2.5months, after which spleen, liver, testes and knee joint tissues were collected for tests. IFN-γ and IL-17A mRNA gene expressions in spleen in all biological samples were determined by RT-PCR. Physicochemical features of drug carriers were monitored by XRD, BET-PSD, SEM and TEM. Drug inflammatory-site targeting was found to be closely related to the physico-features of deliverers. The interlayered lignin of micro- and meso-pore channels directed MTX toward concealed infected cells in liver and testes tissues, while meso-structured silica flacks satisfied by gathering MTX around knee joints. The magneto-silica nanocomposite targeted MTX toward spleen tissue, which is considered as a lively factory for the production of electron rich compounds. Copyright © 2014 Elsevier B.V. All rights reserved.

  10. Sugarcane bagasse lignin, and silica gel and magneto-silica as drug vehicles for development of innocuous methotrexate drug against rheumatoid arthritis disease in albino rats

    International Nuclear Information System (INIS)

    Wahba, Sanaa M.R.; Darwish, Atef S.; Shehata, Iman H.; Abd Elhalem, Sahar S.

    2015-01-01

    The present study clarifies co-therapy action of deliveries from their textural changes point of view. Methotrexate (MTX) was immobilized onto biodegradable lignin, silica gel and iron/silica nanocomposite. Loaded-MTX was i.p. injected into albino rats at doses of 0.25 and 0.5 mg/kg/week for 2.5 months, after which spleen, liver, testes and knee joint tissues were collected for tests. IFN-γ and IL-17A mRNA gene expressions in spleen in all biological samples were determined by RT-PCR. Physicochemical features of drug carriers were monitored by XRD, BET-PSD, SEM and TEM. Drug inflammatory-site targeting was found to be closely related to the physico-features of deliverers. The interlayered lignin of micro- and meso-pore channels directed MTX toward concealed infected cells in liver and testes tissues, while meso-structured silica flacks satisfied by gathering MTX around knee joints. The magneto-silica nanocomposite targeted MTX toward spleen tissue, which is considered as a lively factory for the production of electron rich compounds. - Highlights: • Opening the door to synthesize smart targeted drug deliveries against RA disease • Therapy action of MTX-laden lignin and Fe 3 O 4 /SiO 2 composite toward RA disease • Procure selective targeted drug deliveries of near 100% curing against RA disease • Revolutionary clinical therapies for RA disease by inventive MTX-delivery models

  11. Determination of respirable-sized crystalline silica in different ambient environments in the United Kingdom with a mobile high flow rate sampler utilising porous foams to achieve the required particle size selection

    Science.gov (United States)

    Stacey, Peter; Thorpe, Andrew; Roberts, Paul; Butler, Owen

    2018-06-01

    Inhalation of respirable crystalline silica (RCS) can cause diseases including silicosis and cancer. Levels of RCS close to an emission source are measured but little is known about the wider ambient exposure from industry emissions or natural sources. The aim of this work is to report the RCS concentrations obtained from a variety of ambient environments using a new mobile respirable (PM4) sampler. A mobile battery powered high flow rate (52 L min-1) sampler was developed and evaluated for particulate aerosol sampling employing foams to select the respirable particle size fraction. Sampling was conducted in the United Kingdom at site boundaries surrounding seven urban construction and demolition and five sand quarry sites. These are compared with data from twelve urban aerosol samples and from repeat measurements from a base line study at a single rural site. The 50% particle size penetration (d50) through the foam was 4.3 μm. Over 85% of predict bias values were with ±10% of the respirable convention, which is based on a log normal curve. Results for RCS from all construction and quarry activities are generally low with a 95 th percentile of 11 μg m-3. Eighty percent of results were less than the health benchmark value of 3 μg m-3 used in some states in America for ambient concentrations. The power cutting of brick and the largest demolition activities gave the highest construction levels. Measured urban background RCS levels were typically below 0.3 μg m-3 and the median RCS level, at a rural background location, was 0.02 μg m-3. These reported ambient RCS concentrations may provide useful baseline values to assess the wider impact of fugitive, RCS containing, dust emissions into the wider environment.

  12. What Is Crystalline Silica?

    Science.gov (United States)

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

  13. Analysis of glyoxal, methylglyoxal and dimethylglyoxal in beverages and edible products by mekc using meso-stilbenediamine as derivatizing reagent

    International Nuclear Information System (INIS)

    Mirza, M.; Chaudhary, M.A.; Khuhawar, M.Y.; Arain, R.

    2013-01-01

    Summary: The reactive alpha-diketones; glyoxal (Go), methylglyoxal (MGo) and dimethyglyoxal (DMGo) were determined from wines, beers, whisky, coffee, tea, soy sauce, juices and yoghurt by micellar electrokinetic chromatography (MEKC) using meso-stilbenediamine (meso-SD) as derivatizing reagent. The separation was carried out from uncoated fused silica capillary with effective length 39 cm x 75 micro m internal diameter (id), applied voltage 20 kV and photodiode detection at 228 nm. SDS was used as micellar medium at pH 8, and sodium tetraborate (0.1M) as buffer. The amounts of Go, MGo, and DMGo in Pakistani wines and beers were found within 1.31-6.49 micro g /mL with RSD 1.2 -3.7 %. The amount of Go, MGo and DMGo in food products (Brewed Coffee, Instant Coffee, Instant Tea, Soy sauce, Orange juice , Apple juice and Yoghurt) found were within 0.043-3.42 micro g /mL or micro g /g with RSD 1.1-3.9 %. The analysis was repeatable and reproducible using MEKC. Samples of wine and apple juice were also analyzed by using standard addition method and recoveries were calculated within 96.3-98.5 % with RSD 1.8-2.6 %. (author)

  14. Fabrication of polystyrene porous films with gradient pore structures

    International Nuclear Information System (INIS)

    Yan Hongwei; Zhang Lin; Li Bo; Yin Qiang

    2010-01-01

    Silica opals and multilayer heterostructures were fabricated by vertical deposition technique. Polystyrene inverse opals and gradient porous structures were obtained by colloidal templating, in order to control the pore microstructure of polymer porous materials. As shown in the scanning electron microscopy images, the polystyrene porous structures are precise replicas of inverse structures of the original templates. After being infiltrated with the polystyrene, the photonic stop-band position of the opal composite is redshifted compared with the original template, and it is blueshifted after the opal template being removed. The filling ratio of polystyrene was calculated according to the Bragg formula. (authors)

  15. Drug delivery via porous silicon: a focused patent review.

    Science.gov (United States)

    Kulyavtsev, Paulina A; Spencer, Roxanne P

    2017-03-01

    Although silicon is more commonly associated with computer chips than with drug delivery, with the discovery that porous silicon is a viable biocompatible material, mesoporous silicon with pores between 2 and 50 nm has been loaded with small molecule and biomolecule therapeutics and safely implanted for controlled release. As porous silicon is readily oxidized, porous silica must also be considered for drug delivery applications. Since 2010, only a limited number of US patents have been granted, primarily for ophthalmologic and immunotherapy applications, in contrast to the growing body of technical literature in this area.

  16. Three-dimensional printing of transparent fused silica glass

    Science.gov (United States)

    Kotz, Frederik; Arnold, Karl; Bauer, Werner; Schild, Dieter; Keller, Nico; Sachsenheimer, Kai; Nargang, Tobias M.; Richter, Christiane; Helmer, Dorothea; Rapp, Bastian E.

    2017-04-01

    Glass is one of the most important high-performance materials used for scientific research, in industry and in society, mainly owing to its unmatched optical transparency, outstanding mechanical, chemical and thermal resistance as well as its thermal and electrical insulating properties. However, glasses and especially high-purity glasses such as fused silica glass are notoriously difficult to shape, requiring high-temperature melting and casting processes for macroscopic objects or hazardous chemicals for microscopic features. These drawbacks have made glasses inaccessible to modern manufacturing technologies such as three-dimensional printing (3D printing). Using a casting nanocomposite, here we create transparent fused silica glass components using stereolithography 3D printers at resolutions of a few tens of micrometres. The process uses a photocurable silica nanocomposite that is 3D printed and converted to high-quality fused silica glass via heat treatment. The printed fused silica glass is non-porous, with the optical transparency of commercial fused silica glass, and has a smooth surface with a roughness of a few nanometres. By doping with metal salts, coloured glasses can be created. This work widens the choice of materials for 3D printing, enabling the creation of arbitrary macro- and microstructures in fused silica glass for many applications in both industry and academia.

  17. Synthesis of Porous Carbon Monoliths Using Hard Templates.

    Science.gov (United States)

    Klepel, Olaf; Danneberg, Nina; Dräger, Matti; Erlitz, Marcel; Taubert, Michael

    2016-03-21

    The preparation of porous carbon monoliths with a defined shape via template-assisted routes is reported. Monoliths made from porous concrete and zeolite were each used as the template. The porous concrete-derived carbon monoliths exhibited high gravimetric specific surface areas up to 2000 m²·g -1 . The pore system comprised macro-, meso-, and micropores. These pores were hierarchically arranged. The pore system was created by the complex interplay of the actions of both the template and the activating agent as well. On the other hand, zeolite-made template shapes allowed for the preparation of microporous carbon monoliths with a high volumetric specific surface area. This feature could be beneficial if carbon monoliths must be integrated into technical systems under space-limited conditions.

  18. Decay dynamics of blue-green luminescence in meso-porous MCM-41 nanotubes

    International Nuclear Information System (INIS)

    Lee, Y.C.; Liu, Y.L.; Wang, C.K.; Shen, J.L.; Cheng, P.W.; Cheng, C.F.; Ko, C.-H.; Lin, T.Y.

    2005-01-01

    Time-resolved photoluminescence (PL) was performed to investigate the decay of blue-green luminescence in MCM-41 nanotubes. The PL decay exhibits a clear nonexponential profile, which can be fitted by a stretched exponential function. In the temperature range from 50 to 300 K the photogenerated carriers become thermally activated with a characteristic energy of 29 meV, which is an indication of the phonon-assisted nonradiative process. The temperature dependence of the lifetime of PL decay has been explained using a model based on the radiative recombination of localized carriers and the phonon-assisted nonradiative recombination

  19. Kinetics Study of Gas Pollutant Adsorption and Thermal Desorption on Silica Gel

    Directory of Open Access Journals (Sweden)

    Rong A

    2017-06-01

    Full Text Available Silica gel is a typical porous desiccant material. Its adsorption performance for gaseous air pollutants was investigated to determine its potential contribution to reducing such pollutants. Three gaseous air pollutants, toluene, carbon dioxide, and methane, were investigated in this paper. A thermogravimetric analyzer was used to obtain the equilibrium adsorption capacity of gases on single silica gel particles. The silica gel adsorption capacity for toluene is much higher than that for carbon dioxide and methane. To understand gas pollutant thermal desorption from silica gel, the thermogravimetric analysis of toluene desorption was conducted with 609 ppm toluene vapor at 313 K, 323 K, and 333 K. The overall regeneration rate of silica gel was strongly dependent on temperature and the enthalpy of desorption. The gas pollutant adsorption performance and thermal desorption on silica gel material may be used to estimate the operating and design parameters for gas pollutant adsorption by desiccant wheels.

  20. 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

  1. Micro- and meso-scale effects of forested terrain

    DEFF Research Database (Denmark)

    Dellwik, Ebba; Mann, Jakob; Sogachev, Andrey

    2011-01-01

    scales are the height of the planetary boundary layer and the Monin-Obukhov length, which both are related to the energy balance of the surface. Examples of important micro- and meso-scale effects of forested terrain are shown using data and model results from recent and ongoing experiments. For micro......The height and rotor diameter of modern wind turbines are so extensive, that the wind conditions they encounter often are well above the surface layer, where traditionally it is assumed that wind direction and turbulent fluxes are constant with respect to height, if the surface is homogenous....... Deviations from the requirement of homogeneity are often the focus of micro-scale studies in forested areas. Yet, to explain the wind climate in the relevant height range for turbines, it is necessary to also account for the length scales that are important parameters for the meso-scale flow. These length...

  2. Meso-optical Fourier transform microscope with double focusing

    International Nuclear Information System (INIS)

    Batusov, Yu.A.; Soroko, L.M.; Tereshchenko, V.V.

    1992-01-01

    The meso-optical Fourier transform microscope (MFTM) with double focusing for particle tracks of low ionization level in the nuclear emulsion is described. It is shown experimentally that this device enables one to get high concentration of information about the position of the particle track in the nuclear emulsion and thus to increase the signal-to-noise ratio. It is shown that spreading of the meso-optical image of the particle track in the sagittal section of the MFTM can be eliminated completely in the frame of the diffraction limit. The number of the additional degrees of freedom in this new MFTM system along depth coordinate is equal to 20 in comparison to single degree of freedom in the Fourier transform microscope of the direct observation. 10 refs.; 15 figs

  3. Positron annihilation lifetime spectroscopy (PALS) application in metal barrier layer integrity for porous low- k materials

    CERN Document Server

    Simon, Lin; Gidley, D W; Wetzel, J T; Monnig, K A; Ryan, E T; Simon, Jang; Douglas, Yu; Liang, M S; En, W G; Jones, E C; Sturm, J C; Chan, M J; Tiwari, S C; Hirose, M

    2002-01-01

    Positron Annihilation Lifetime Spectroscopy (PALS) is a useful tool to pre-screen metal barrier integrity for Si-based porous low-k dielectrics. Pore size of low-k, thickness of metal barrier Ta, positronium (Ps) leakage from PALS, trench sidewall morphology, electrical test from one level metal (1LM) pattern wafer and Cu diffusion analysis were all correlated. Macro-porous low-k (pore size >=200 AA) and large scale meso-porous low-k (>50~200 AA) encounter both Ps leakage and Cu diffusion into low-k dielectric in the 0.25 mu mL/0.3 mu mS structures when using SEMATECH in-house PVD Ta 250 AA as barrier layer. For small scale meso-porous (>20~50 AA) and micro- porous (<=20 AA) low-k, no Ps leakage and no Cu diffusion into low-k were observed even with PVD Ta 50 AA, which is proved also owing to sidewall densification to seal all sidewall pores due to plasma etch and ash. For future technology, smaller pore size of porous Si-based low-k (=<50 AA) will be preferential for dense low-k like trench sidewall to...

  4. Oxygen configurations in silica

    International Nuclear Information System (INIS)

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

    2000-01-01

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

  5. Silica coatings on clarithromycin.

    Science.gov (United States)

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

    2005-03-03

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

  6. A review on chemical methodologies for preparation of mesoporous silica and alumina based materials.

    Science.gov (United States)

    Naik, Bhanudas; Ghosh, Narendra Nath

    2009-01-01

    The discovery of novel family of molecular sieves called M41S aroused a worldwide resurgence in the field of porous materials. According to IUPAC definition inorganic solids that contain pores with diameter in the size range of 20-500 A are considered mesoporous materials. Mesoporous silica and alumina based materials find applications in catalysis, adsorption, host- guest encapsulation etc. This article reviews the current state of art and outline the recent patents in mesoporous materials research in three general areas: Synthesis, various mechanisms involved for porous structure formation and applications of silica and alumina based mesoporous materials.

  7. Advanced three dimensional characterization of silica-based ultraporous materials

    OpenAIRE

    Foray , Genevieve; Roiban , L.; Rong , Q.; Perret , A.; Ihiawakrim , D.; Masenelli-Varlot , K.; Maire , E.; Yrieix , B.

    2016-01-01

    International audience; Whatever the field of application (building, transportation, packaging, etc.) energy losses must be reduced to meet the government target of a 40% cut in CO 2 emissions. This leads to a challenge for materials scientists: designing materials with thermal conductivities lower than 0.015 W m À1 K À1 under ambient conditions. Such a low value requires reducing air molecule mobility in highly porous materials, and silica-based superinsulation materials (SIM) made of packed...

  8. Innovative Route to Prepare of Au/C Catalysts by Replication of Gold-containing Mesoporous Silicas

    KAUST Repository

    Kerdi, Fatmé

    2011-12-23

    Gold-catalyzed aerobic epoxidations in the liquid phase are generally performed in low-polarity solvents, in which conventional oxide-supported catalysts are poorly dispersed. To improve the wettability of the catalytic powder and, thus, the efficiency of the catalyst, gold nanoparticles (NPs) have been dispersed on meso-structured carbons. Gold is first introduced in functionalized mesostructured silica and particles are formed inside the porosity. Silica pores are then impregnated with a carbon precursor and the composite material is heated at 900 °C under vacuum or nitrogen. Silica is then removed by acid leaching, leading to partially encapsulated gold particles in mesoporous carbon. Carbon prevents aggregation of gold particles at high temperature, both the mean size and distribution being similar to those observed in silica. However, while Au@SiO2 exhibit significant catalytic activity in the aerobic oxidation of trans-stilbene in the liquid phase, its Au@C mesostructured replica is quite inactive.

  9. An efficient sodium citrate-promoted synthetic method for the preparation of AuNPs@mesoSiO2 for surface enhanced Raman spectroscopy in the detection of diluted blood

    Directory of Open Access Journals (Sweden)

    Yun Zou

    2017-12-01

    Full Text Available We report on a novel, green, and efficient organically synthetic method for the preparation of gold nanoparticles embedded in mesoporous silica (AuNPs@mesoSiO2. AuNPs@mesoSiO2 prepared by one-pot synthesis method using sodium citrate as the key reactant was applied for surface enhanced Raman spectroscopy (SERS application in the analysis of diluted blood traces. The synthesized nanoparticles are of high quality, as characterized by use of X-ray diffraction, scanning electron microscopy and transmission electron microscopy. They exhibit high surface areas (170.18–883 m2/g and significant SERS enhancement. Detection of diluted blood (v/v, 1:50 traces through AuNPs@mesoSiO2 enhanced SERS is demonstrated, which has not been studied in previous literature. The combination of the SERS and AuNPs@mesoSiO2 would be a valuable tool for forensic investigation. Keywords: Gold nanoparticles, Mesoporous materials, Synthesis, SERS, Blood trace

  10. 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)

  11. Altering the concentration of silica tunes the functional properties of collagen-silica composite scaffolds to suit various clinical requirements.

    Science.gov (United States)

    Perumal, Sathiamurthi; Ramadass, Satiesh Kumar; Gopinath, Arun; Madhan, Balaraman; Shanmugam, Ganesh; Rajadas, Jayakumar; Mandal, Asit Baran

    2015-12-01

    The success of a tissue engineering scaffold depends on a fine balance being achieved between the physicochemical and biological properties. This study attempts to understand the influence of silica concentration on the functional properties of collagen-silica (CS) composite scaffolds for soft tissue engineering applications. Increasing the ratio of silica to collagen (0.25, 0.5, 0.75, 1.0, 1.25, 1.5 and 2.0 w/w) gave a marked advantage in terms of improving the water uptake and compressive modulus of the CS scaffolds, while also enhancing the biological stability and the turnover time. With increase in silica concentration the water uptake and compressive modulus increased concurrently, whereas it was not so for surface porous architecture and biocompatibility which are crucial for cell adhesion and infiltration. Silica:collagen ratio of ≤1 exhibits favourable surface biocompatibility, and any further increase in silica concentration has a detrimental effect. Copyright © 2015 Elsevier Ltd. All rights reserved.

  12. Hexadecane trapped in nano-pores of silica-aerogel

    International Nuclear Information System (INIS)

    Slavikova, B.; Jesenak, K.; Iskrova, M.; Majernik, V.; Sausa, O.; Kristiak, J.

    2009-01-01

    Ways of filling of the high-porous silica-aerogel with hydrocarbon C 16 H 34 and its efficient removal from the pores by physical method of the Positron Annihilation Spectroscopy were studied. As the most effective way to fill the SiO 2 aerogel appears through the implementation of a liquid phase, while the most appropriate way of removing of hexadecane is firing at an elevated temperature. Molecular system of hexadecane closed in nano-pores of silica-aerogel behaves otherwise than volume system of the same molecules. In the case of pure hexadecane phase transition was observed at 291 K, while solidification process is gradual with decrease of temperature in cetane trapped in pores of silica-aerogel. The results of the periods of life of o-Ps indicate greater turbidity in the pores of the molecular system compared to the volume sample of hexadecane.

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

    DEFF Research Database (Denmark)

    Kiil, Søren

    2015-01-01

    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......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...

  14. Isolation of two tissue-specific Drosophila paired box genes, Pox meso and Pox neuro.

    OpenAIRE

    Bopp, D; Jamet, E; Baumgartner, S; Burri, M; Noll, M

    1989-01-01

    Two new paired domain genes of Drosophila, Pox meso and Pox neuro, are described. In contrast to the previously isolated paired domain genes, paired and gooseberry, which contain both a paired and a homeo-domain (PHox genes), Pox meso and Pox neuro possess no homeodomain. Evidence suggesting that the new genes encode tissue-specific transcriptional factors and belong to the same regulatory cascade as the other paired domain genes includes (i) tissue-specific expression of Pox meso in the soma...

  15. A facile approach for the synthesis of monolithic hierarchical porous carbons – high performance materials for amine based CO2 capture and supercapacitor electrode

    KAUST Repository

    Estevez, Luis

    2013-05-03

    An ice templating coupled with hard templating and physical activation approach is reported for the synthesis of hierarchically porous carbon monoliths with tunable porosities across all three length scales (macro- meso- and micro), with ultrahigh specific pore volumes [similar]11.4 cm3 g−1. The materials function well as amine impregnated supports for CO2 capture and as supercapacitor electrodes.

  16. Experimental Study on Meso-Scale Milling Process Using Nanofluid Minimum Quantity Lubrication

    International Nuclear Information System (INIS)

    Lee, P. H.; Nam, T. S.; Li, Cheng Jun; Lee, S. W.

    2010-01-01

    This paper present the characteristics of micro- and meso-scale milling processes in which compressed cold air, minimum quantity lubrication (MQL) and MoS 2 nanofluid MQL are used. For process characterization, the micro and meso-scale milling experiments are conducted using desktop meso-scale machine tool system and the surface roughness is measured. The experimental results show that the use of compressed chilly air and nanofluid MQL in the micro- and meso-scale milling processes is effective in improving the surface finish

  17. A novel approach for osteocalcin detection by competitive ELISA using porous silicon as a substrate.

    Science.gov (United States)

    Rahimi, Fereshteh; Mohammadnejad Arough, Javad; Yaghoobi, Mona; Davoodi, Hadi; Sepehri, Fatemeh; Amirabadizadeh, Masood

    2017-11-01

    In this study, porous silicon (PSi) was utilized instead of prevalent polystyrene platforms, and its capability in biomolecule screening was examined. Here, two types of porous structure, macroporous silicon (Macro-PSi) and mesoporous silicon (Meso-PSi), were produced on silicon wafers by electrochemical etching using different electrolytes. Moreover, both kinds of fresh and oxidized PSi samples were investigated. Next, osteocalcin as a biomarker of the bone formation process was used as a model biomarker, and the colorimetric detection was performed by competitive enzyme-linked immunosorbent assay (ELISA). Both Macro-PSi and Meso-PSi substrates in the oxidized state, specifically the Meso-porous structure, were reported to have higher surface area to volume ratio, more capacitance of surface-antigen interaction, and more ability to capture antigen in comparison with the prevalent platforms. Moreover, the optical density signal of osteocalcin detected by the ELISA technique was notably higher than the common platforms. Based on the findings of this study, PSi can potentially be used in the ELISA to achieve better results and consequently more sensitivity. A further asset of incorporating such a nanometer structure in the ELISA technique is that the system response to analyte concentration could be maintained by consuming lower monoclonal antibody (or antigen) and consequently reduces the cost of the experiment. © 2016 International Union of Biochemistry and Molecular Biology, Inc.

  18. LBM estimation of thermal conductivity in meso-scale modelling

    International Nuclear Information System (INIS)

    Grucelski, A

    2016-01-01

    Recently, there is a growing engineering interest in more rigorous prediction of effective transport coefficients for multicomponent, geometrically complex materials. We present main assumptions and constituents of the meso-scale model for the simulation of the coal or biomass devolatilisation with the Lattice Boltzmann method. For the results, the estimated values of the thermal conductivity coefficient of coal (solids), pyrolytic gases and air matrix are presented for a non-steady state with account for chemical reactions in fluid flow and heat transfer. (paper)

  19. Toughening Mechanisms in Silica-Filled Epoxy Nanocomposites

    Science.gov (United States)

    Patel, Binay S.

    and modeled fracture energy results. Furthermore, the contribution of microcracking was most prevalent at lower filler contents which suggests that the presence of microcracking may account for the previously unexplained improvements in fracture behavior attained in silica-filled epoxy nanocomposites at low filler contents. Secondly, surface modification through the application of three different propriety surface treatments ("A", "B" and "C") was found to greatly influence the processibility and fracture behavior of silica-filled epoxy nanocomposites. B-treated silica nanoparticles were found to readily form micron-scale agglomerates, settled during nanocomposite curing and showed no improvement in fracture toughness with increasing filler content. In contrast, the nanocomposites consisting of A-treated and C-treated silica nanoparticles yielded morphologies primarily containing well-dispersed nanoparticles. Therefore, fracture toughness improved with increasing filler content. Finally, particle porosity was found to have no significant effect on fracture behavior for the range of silica-filled epoxy nanocomposites investigated. Lower density porous silica nanoparticles were just as effective toughening agents as higher density non-porous silica nanoparticles. Consequently, the potential exists for the use of toughened-epoxies in lightweight structural applications.

  20. Effect of hydrofluoric acid concentration on the evolution of photoluminescence characteristics in porous silicon nanowires prepared by Ag-assisted electroless etching method

    KAUST Repository

    Najar, Adel; Anjum, Dalaver H.; Hedhili, Mohamed N.; Ng, Tien Khee; Ooi, Boon S.; Ben Slimane, Ahmed; Sougrat, Rachid

    2012-01-01

    We report on the structural and optical properties of porous silicon nanowires (PSiNWs) fabricated using silver (Ag) ions assisted electroless etching method. Silicon nanocrystallites with sizes <5 nm embedded in amorphous silica have been

  1. Amine Functionalized Porous Network

    KAUST Repository

    Eddaoudi, Mohamed; Guillerm, Vincent; Weselinski, Lukasz Jan; Alkordi, Mohamed H.; Mohideen, Mohamed Infas Haja; Belmabkhout, Youssef

    2015-01-01

    Amine groups can be introduced in porous materials by a direct (one pot) or post-synthetic modification (PSM) process on aldehyde groups, and the resulting porous materials have increased gas affinity.

  2. Amine Functionalized Porous Network

    KAUST Repository

    Eddaoudi, Mohamed

    2015-05-28

    Amine groups can be introduced in porous materials by a direct (one pot) or post-synthetic modification (PSM) process on aldehyde groups, and the resulting porous materials have increased gas affinity.

  3. CH of masonry materials via meshless meso-modeling

    Directory of Open Access Journals (Sweden)

    Giuseppe Giambanco

    2014-07-01

    Full Text Available In the present study a multi-scale computational strategy for the analysis of masonry structures is presented. The structural macroscopic behaviour is obtained making use of the Computational Homogenization (CH technique based on the solution of the boundary value problem (BVP of a detailed Unit Cell (UC chosen at the meso-scale and representative of the heterogeneous material. The smallest UC is composed by a brick and half of its surrounding joints, the former assumed to behave elastically while the latter considered with an elastoplastic softening response. The governing equations at the macroscopic level are formulated in the framework of finite element method while the Meshless Method (MM is adopted to solve the BVP at the mesoscopic level. The work focuses on the BVP solution. The consistent tangent stiffness matrix at a macroscopic quadrature point is evaluated on the base of BVP results for the UC together with a localisation procedure. Validation of the MM procedure at the meso-scale level is demonstrated by numerical examples that show the results of the BVP for the simple cases of normal and shear loading of the UC.

  4. On Selective Derivatization of meso-Tetraarylporphyrins (A Microreview)

    International Nuclear Information System (INIS)

    Ostrowski, S.

    2003-01-01

    The studies on selective derivatization in one or two aromatic rings of meso-tetraarylporphyrin systems (and their zinc and copper complexes) using (a) selective nitration, (b) Vicarious Nucleophilic Substitution of Hydrogen(VNS), and (c) alkylation of the above intermediates with alkyl halides, are reported. The stepwise selective nitration of meso-aryl substituted porphyrins with fuming yellow nitric acid (d= 1.53) at the tempreture 0 deg to 20 deg results in the formation of 5-(4-nitroaryl)- 10, 15, 20-triarylporphyrins, 5,10-bis(4-nitroaryl)-15,20-diarylporphrins or trinitro- and tetranitro-derivatives, respectively, in good or reasonable yield. The above intermediates, after simple transformation to their copper or zinc complexes react with carbanions bearing leaving groups at the carbanionic center, according to VNS scheme. This reaction can be also realized at low temperature (-30 deg- 40 deg) without complexation of the parent nitroporphyrins. Alkylation of the products obtained with alkyl halides or alkyl halides bearing multiple bonds in the carbon chain led to useful compounds for further functionalization . (Author) 53 refs., 7sches., 4 figs

  5. Electrohydrodynamic Liquid Disintegration in Micro-, Meso- and Nanoscopic Dimensions

    Science.gov (United States)

    Vertes, Akos

    2008-11-01

    The electrohydrodynamic dispersion of liquids spans length scales from 1 mm to 1 nm and involves temporal variations from 1 s to 10 ps. The disintegration mechanisms are diverse and, due to the differences in the dominating forces, vary on the micro-, meso- and nanoscale extending to lower boundaries of 1 μm, 10 nm and 1 nm, respectively. Using fast imaging, spray current measurements, phase Doppler anemometry and molecular dynamics calculations, we followed the behavior of electrified liquids in the three most common geometries, spherical, pendant drop and slender jet, with dimensions ranging from 100 μm to 1 nm. Microscale disintegration involves jet ejection from conical surface deformations, jet breakup due to varicose, kink and ramified jet instabilities, and asymmetric droplet fission resulting in side jets. As the liquid dimensions shift from the microscopic dimensions where the processes are governed by the surface tension and the Maxwell stress, to the meso- and nanoscale, thermal fluctuations become increasingly important. The presence of charges in nanodroplets leads to enhanced surface fluctuations, the formation of extreme protrusions and eventually solvated ion evaporation. Charging of slender nanojets results in longer shape relaxation times along with the fission of systems charged below the Rayleigh limit. In collaboration with Jelena Lusic and Peter Nemes, George Washington University.

  6. Dielectric relaxations of confined water in porous silica ceramics

    Indian Academy of Sciences (India)

    2017-12-06

    Dec 6, 2017 ... Bull. Mater. Sci., Vol. 40, No. 7, December 2017, pp. 1489–1495 ... to prove the effect of the lateral surface state of the sample on water–inner surfaces of the .... of fractal description allows relating the fractal dimension of.

  7. Molecular imprinting at walls of silica nanotubes for TNT recognition.

    Science.gov (United States)

    Xie, Chenggen; Liu, Bianhua; Wang, Zhenyang; Gao, Daming; Guan, Guijian; Zhang, Zhongping

    2008-01-15

    This paper reports the molecular imprinting at the walls of highly uniform silica nanotubes for the recognition of 2,4,6-trinitrotoluene (TNT). It has been demonstrated that TNT templates were efficiently imprinted into the matrix of silica through the strong acid-base pairing interaction between TNT and 3-aminopropyltriethoxysilane (APTS). TNT-imprinted silica nanotubes were synthesized by the gelation reaction between APTS and tetraethylorthosilicate (TEOS), selectively occurring at the porous walls of APTS-modified alumina membranes. The removal of the original TNT templates leaves the imprinted cavities with covalently anchored amine groups at the cavity walls. A high density of recognition sites with molecular selectivity to the TNT analyte was created at the wall of silica nanotubes. Furthermore, most of these recognition sites are situated at the inside and outside surfaces of tubular walls and in the proximity of the two surfaces due to the ultrathin wall thickness of only 15 nm, providing a better site accessibility and lower mass-transfer resistance. Therefore, greater capacity and faster kinetics of uptaking target species were achieved. The silica nanotube reported herein is an ideal form of material for imprinting various organic or biological molecules toward applications in chemical/biological sensors and bioassay.

  8. Developmentally Regulated Production of meso-Zeaxanthin in Chicken Retinal Pigment Epithelium/Choroid and Retina.

    Science.gov (United States)

    Gorusupudi, Aruna; Shyam, Rajalekshmy; Li, Binxing; Vachali, Preejith; Subhani, Yumna K; Nelson, Kelly; Bernstein, Paul S

    2016-04-01

    meso-Zeaxanthin is a carotenoid that is rarely encountered in nature outside of the vertebrate eye. It is not a constituent of a normal human diet, yet this carotenoid comprises one-third of the primate macular pigment. In the current study, we undertook a systematic approach to biochemically characterize the production of meso-zeaxanthin in the vertebrate eye. Fertilized White Leghorn chicken eggs were analyzed for the presence of carotenoids during development. Yolk, liver, brain, serum, retina, and RPE/choroid were isolated, and carotenoids were extracted. The samples were analyzed on C-30 or chiral HPLC columns to determine the carotenoid composition. Lutein and zeaxanthin were found in all studied nonocular tissues, but no meso-zeaxanthin was ever detected. Among the ocular tissues, the presence of meso-zeaxanthin was consistently observed starting at embryonic day 17 (E17) in the RPE/choroid, several days before its consistent detection in the retina. If RPE/choroid of an embryo was devoid of meso-zeaxanthin, the corresponding retina was always negative as well. This is the first report of developmentally regulated synthesis of meso-zeaxanthin in a vertebrate system. Our observations suggest that the RPE/choroid is the primary site of meso-zeaxanthin synthesis. Identification of meso-zeaxanthin isomerase enzyme in the developing chicken embryo will facilitate our ability to determine the biochemical mechanisms responsible for production of this unique carotenoid in other higher vertebrates, such as humans.

  9. Silica-Immobilized Enzyme Reactors

    Science.gov (United States)

    2007-08-01

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

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

    NARCIS (Netherlands)

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

    2017-01-01

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

  11. Synthesis and separation properties of an α-alumina-supported high-silica MEL membrane

    NARCIS (Netherlands)

    Kosinov, N.; Hensen, E.J.M.

    2013-01-01

    A thin high-silica MEL membrane was synthesized on a porous a-alumina hollow fiber support by a secondary growth approach. The membrane quality was evaluated by permporometry, single-gas permeation and butane isomer separation. Comparison of the pervaporation performance of MEL membranes with a MFI

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

    NARCIS (Netherlands)

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

    2017-01-01

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

  13. Atomic dynamics of tin nanoparticles embedded into porous glass

    Energy Technology Data Exchange (ETDEWEB)

    Parshin, P. P.; Zemlyanov, M. G., E-mail: zeml@isssph.kiae.ru; Panova, G. Kh.; Shikov, A. A. [Russian Research Centre Kurchatov Institute (Russian Federation); Kumzerov, Yu. A.; Naberezhnov, A. A. [Russian Academy of Sciences, Ioffe Physicotechnical Institute (Russian Federation); Sergueev, I.; Crichton, W. [European Synchrotron Radiation Facility (France); Chumakov, A. I. [Russian Research Centre Kurchatov Institute (Russian Federation); Rueffer, R. [European Synchrotron Radiation Facility (France)

    2012-03-15

    The method of resonant nuclear inelastic absorption of synchrotron radiation has been used to study the phonon spectrum for tin nanoparticles (with a natural isotope mixture) embedded into a porous glassy (silica) matrix with an average pore diameter of 7 nm in comparison to the analogous spectrum of bulk tin enriched with {sup 119}Sn isotope. Differences between the spectra have been observed, which are related to both the dimensional effects and specific structural features of the porous glass-tin nanocomposite. Peculiarities in the dynamics of tin atoms embedded into nanopores of glass are interpreted in terms of a qualitative model of the nanocomposite structure.

  14. Atomic dynamics of tin nanoparticles embedded into porous glass

    International Nuclear Information System (INIS)

    Parshin, P. P.; Zemlyanov, M. G.; Panova, G. Kh.; Shikov, A. A.; Kumzerov, Yu. A.; Naberezhnov, A. A.; Sergueev, I.; Crichton, W.; Chumakov, A. I.; Rüffer, R.

    2012-01-01

    The method of resonant nuclear inelastic absorption of synchrotron radiation has been used to study the phonon spectrum for tin nanoparticles (with a natural isotope mixture) embedded into a porous glassy (silica) matrix with an average pore diameter of 7 nm in comparison to the analogous spectrum of bulk tin enriched with 119 Sn isotope. Differences between the spectra have been observed, which are related to both the dimensional effects and specific structural features of the porous glass-tin nanocomposite. Peculiarities in the dynamics of tin atoms embedded into nanopores of glass are interpreted in terms of a qualitative model of the nanocomposite structure.

  15. Meso- and macroporous sulfonated starch solid acid catalyst for esterification of palm fatty acid

    Directory of Open Access Journals (Sweden)

    Ibrahim M. Lokman

    2016-03-01

    Full Text Available In the present work, a heterogeneous solid acid catalyst was successfully developed from starch. The catalyst was prepared by a significant two-step process; the initial step was incomplete carbonization of starch (ICS at 400 °C for 12 h and consequently followed by sulfonation process using concentrated H2SO4 to produce sulfonated-incomplete carbonized starch (ICS-SO3H. The characterization of the ICS-SO3H catalyst was done for chemical and physical properties such as X-ray diffraction (XRD, ammonia-temperature programmed desorption (NH3-TPD, surface area analysis, thermal gravimetric analysis (TGA, elemental analysis and morphology analysis by scanning electron microscope (SEM. BET results showed the structure of ICS-SO3H consists of meso- and macro-porous properties, which allowed high density of the SO3H group attached on its carbon networks. The catalytic activity of ICS-SO3H catalyst was determined by analyzing the catalyst performance to esterify palm fatty acid distillate (PFAD and sequentially produced methyl ester. The maximum free fatty acid (FFA conversion and FAME yield were as high as 94.6% and 90.4%, respectively, at 75 °C using 10:1 methanol-to-PFAD molar ratio and 2 wt.% of catalyst within 3 h. The catalyst has sufficient potential to recycle up to 6 reactions without reactivation step and any remarkable loss of catalytic activity. It revealed that the heterogeneous ICS-SO3H catalyst exhibits high stability, reusability and catalytic activity.

  16. 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...

  17. Investigations on the homogeneity of silica glass and on the order of X-amorphous silica by luminescence measurements

    International Nuclear Information System (INIS)

    Boden, G.

    1982-08-01

    Silica glasses melted from crystalline SiO 2 were exposed to ionizing radiation. At room temperature the spatial intensity distribution of the emitted luminescent radiation has been recorded by means of photographic or autoradiographic materials. Thereby schlieren and inhomogeneities are made visible and information is obtained on the melting process of the crystalline SiO 2 . Synthetic fused silica made from SiCl 4 shows no luminescent radiation. Depending on the penetration depth of the ionizing radiation the bulk or the surface of the sample can be studied. The decay curves of the integral luminescence intensity yield data on inhomogeneities in the silica glass leading to conclusions on order state and structure. The luminescence intensity and its half-life are a measure for the inhomogeneity of the silica glass and the existence of so-called 'preordered states'. This connection between luminescence intensity and the order state is found also with other X-amorphous SiO 2 modifications: silica gel, precipitated silicic acids, porous SiO 2 glasses, aerosil, thin SiO 2 layers, mechanically activated quartz: whereas no luminescence phenomena occur in disordered nearly ideally amorphous SiO 2 species, the luminescence increases with increasing order degree of the SiO 2 network and attains a high intensity in the case of the crystalline SiO 2 modifications quartz and cristobalite

  18. Porous organic cages

    Science.gov (United States)

    Tozawa, Tomokazu; Jones, James T. A.; Swamy, Shashikala I.; Jiang, Shan; Adams, Dave J.; Shakespeare, Stephen; Clowes, Rob; Bradshaw, Darren; Hasell, Tom; Chong, Samantha Y.; Tang, Chiu; Thompson, Stephen; Parker, Julia; Trewin, Abbie; Bacsa, John; Slawin, Alexandra M. Z.; Steiner, Alexander; Cooper, Andrew I.

    2009-12-01

    Porous materials are important in a wide range of applications including molecular separations and catalysis. We demonstrate that covalently bonded organic cages can assemble into crystalline microporous materials. The porosity is prefabricated and intrinsic to the molecular cage structure, as opposed to being formed by non-covalent self-assembly of non-porous sub-units. The three-dimensional connectivity between the cage windows is controlled by varying the chemical functionality such that either non-porous or permanently porous assemblies can be produced. Surface areas and gas uptakes for the latter exceed comparable molecular solids. One of the cages can be converted by recrystallization to produce either porous or non-porous polymorphs with apparent Brunauer-Emmett-Teller surface areas of 550 and 23m2g-1, respectively. These results suggest design principles for responsive porous organic solids and for the modular construction of extended materials from prefabricated molecular pores.

  19. Preparation, characterization of electrospun meso-hydroxylapatite nanofibers and their sorptions on Co(II)

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hualin, E-mail: hlwang@hfut.edu.cn [School of Chemical Technology, Hefei University of Technology, Hefei, Anhui 230009 (China); Zhang, Peng; Ma, Xingkong; Jiang, Suwei; Huang, Yan; Zhai, Linfeng [School of Chemical Technology, Hefei University of Technology, Hefei, Anhui 230009 (China); Jiang, Shaotong [School of Biotechnology and Food Engineering, Hefei University of Technology, Hefei, Anhui 230009 (China)

    2014-01-30

    Highlights: • PVA/HA nanofibers could change into meso-HA nanofibers by calcination process. • Sorption of Co(II) on meso-HA was strongly dependent on pH and ionic strength. • Sorption kinetic data were well fitted by the pseudo-second-order rate equation. • Sorption isotherms could be well described by the Langmuir model. • Sorption process of Co(II) on meso-HA nanofibers was spontaneous and endothermic. -- Abstract: In this work, mesoporous hydroxylapatite (meso-HA) nanofibers were prepared via calcination process with polyvinyl alcohol/HA (PVA/HA) hybrid nanofibers fabricated by electrospinning technique as precursors, and the removal efficiency of meso-HA nanofibers toward Co(II) was evaluated via sorption kinetics and sorption isotherms. Furthermore, the sorption behaviors of Co(II) on meso-HA nanofibers were explored as a function of pH, ionic strength, and thermodynamic parameters. There existed hydrogen bonds between HA and PVA matrix in precursor nanofibers which could change into meso-HA nanofibers with main pore diameter at 27 nm and specific surface area at 114.26 m{sup 2}/g by calcination process. The sorption of Co(II) on meso-HA was strongly dependent on pH and ionic strength. Outer-sphere surface complexation or ion exchange was the main mechanisms of Co(II) adsorption on meso-HA at low pH, whereas inner-sphere surface complexation was the main adsorption mechanism at high pH. The sorption kinetic data were well fitted by the pseudo-second-order rate equation. The sorption isotherms could be well described by the Langmuir model. The thermodynamic parameters (ΔH°, ΔS° and ΔG°) calculated from the temperature-dependent sorption isotherms suggested that the sorption process of Co(II) on meso-HA nanofibers was spontaneous and endothermic.

  20. Positron annihilation in vitreous silica glasses

    International Nuclear Information System (INIS)

    Uedono, Akira; Tanigawa, Shoichiro

    1993-01-01

    The annihilation characteristics of positrons in vitreous silica glasses (v-SiO 2 ) were studied by measurements of two-dimensional angular correlation of positron annihilation radiations and positron lifetime spectra. From the measurements, it was found that positrons and positronium (Ps) atoms mainly annihilate from trapped states by vacancy-type defects in v-SiO 2 . For v-SiO 2 specimens with cylindrical porous structures, annihilations of Ps with anisotropic momentum distributions were observed. This fact was attributed to the momentum uncertainty due to localization of Ps in a finite dimension of pores. This investigation showed possibilities for the detection of microstructures in v-SiO 2 by the positron annihilation technique. (author)

  1. Silica from Ash

    Indian Academy of Sciences (India)

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

  2. 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

  3. Green's Kernels and meso-scale approximations in perforated domains

    CERN Document Server

    Maz'ya, Vladimir; Nieves, Michael

    2013-01-01

    There are a wide range of applications in physics and structural mechanics involving domains with singular perturbations of the boundary. Examples include perforated domains and bodies with defects of different types. The accurate direct numerical treatment of such problems remains a challenge. Asymptotic approximations offer an alternative, efficient solution. Green’s function is considered here as the main object of study rather than a tool for generating solutions of specific boundary value problems. The uniformity of the asymptotic approximations is the principal point of attention. We also show substantial links between Green’s functions and solutions of boundary value problems for meso-scale structures. Such systems involve a large number of small inclusions, so that a small parameter, the relative size of an inclusion, may compete with a large parameter, represented as an overall number of inclusions. The main focus of the present text is on two topics: (a) asymptotics of Green’s kernels in domai...

  4. Meso and micro level workforce challenges in psychiatric rehabilitation.

    Science.gov (United States)

    Reifels, Lennart; Pirkis, Jane

    2012-01-01

    Results of an exploratory study are presented which examined workforce challenges in Australia's most established psychiatric rehabilitation sector. The study had the two-fold aim of investigating workforce challenges at an organizational ("meso") level and at the level of direct-service workers' daily practice ("micro"). Data from 23 key informant interviews conducted with service managers and long-serving staff were analyzed through basic descriptive and thematic analyses. Organizations faced significant annual staff turnover (25.6%), specific staff supply shortages, and challenges in recruiting staff with adequate experience and longevity to match the complexity of client issues. Workers equally encountered challenges in this increasingly complex and rapidly changing field of work. CONCLUSIONS & IMPLICATIONS FOR PRACTICE: Workforce strategies designed to attract/retain experienced staff can improve workforce cohesiveness and sustainability, as can training and support activities aimed at equipping staff to reflect on and operate in dynamic and changing work environments.

  5. Safety analysis of urban arterials at the meso level.

    Science.gov (United States)

    Li, Jia; Wang, Xuesong

    2017-11-01

    Urban arterials form the main structure of street networks. They typically have multiple lanes, high traffic volume, and high crash frequency. Classical crash prediction models investigate the relationship between arterial characteristics and traffic safety by treating road segments and intersections as isolated units. This micro-level analysis does not work when examining urban arterial crashes because signal spacing is typically short for urban arterials, and there are interactions between intersections and road segments that classical models do not accommodate. Signal spacing also has safety effects on both intersections and road segments that classical models cannot fully account for because they allocate crashes separately to intersections and road segments. In addition, classical models do not consider the impact on arterial safety of the immediately surrounding street network pattern. This study proposes a new modeling methodology that will offer an integrated treatment of intersections and road segments by combining signalized intersections and their adjacent road segments into a single unit based on road geometric design characteristics and operational conditions. These are called meso-level units because they offer an analytical approach between micro and macro. The safety effects of signal spacing and street network pattern were estimated for this study based on 118 meso-level units obtained from 21 urban arterials in Shanghai, and were examined using CAR (conditional auto regressive) models that corrected for spatial correlation among the units within individual arterials. Results showed shorter arterial signal spacing was associated with higher total and PDO (property damage only) crashes, while arterials with a greater number of parallel roads were associated with lower total, PDO, and injury crashes. The findings from this study can be used in the traffic safety planning, design, and management of urban arterials. Copyright © 2017 Elsevier Ltd. All

  6. Fluid Flow Programming in Paper-Derived Silica-Polymer Hybrids.

    Science.gov (United States)

    Dubois, Christelle; Herzog, Nicole; Rüttiger, Christian; Geißler, Andreas; Grange, Eléonor; Kunz, Ulrike; Kleebe, Hans-Joachim; Biesalski, Markus; Meckel, Tobias; Gutmann, Torsten; Gallei, Markus; Andrieu-Brunsen, Annette

    2017-01-10

    In paper-based devices, capillary fluid flow is based on length-scale selective functional control within a hierarchical porous system. The fluid flow can be tuned by altering the paper preparation process, which controls parameters such as the paper grammage. Interestingly, the fiber morphology and nanoporosity are often neglected. In this work, porous voids are incorporated into paper by the combination of dense or mesoporous ceramic silica coatings with hierarchically porous cotton linter paper. Varying the silica coating leads to significant changes in the fluid flow characteristics, up to the complete water exclusion without any further fiber surface hydrophobization, providing new approaches to control fluid flow. Additionally, functionalization with redox-responsive polymers leads to reversible, dynamic gating of fluid flow in these hybrid paper materials, demonstrating the potential of length scale specific, dynamic, and external transport control.

  7. Synthesis of Macroporous Silica Particles by Continuous Generation of Droplets for Insulating Materials.

    Science.gov (United States)

    Cho, Young-Sang; Lee, Dokyoung

    2018-09-01

    We report on the synthesis of porous silica particles by self-assembly routes in a continuous manner for application to thermal insulators. A continuous process was employed to produce tiny droplets containing precursor materials such as silica and organic templates for self-organization to fabricate particles with well defined pores. A rotating cylinder system or a spray drying process was adopted to form emulsions or aerosol droplets as micro-reactors for self-assembly, and the physical properties including the thermal conductivity of the resulting porous particles were compared between the two methods. The porous particles could be coated as a thick film by solution dripping, and the fluorination treatment using a silane coupling agent was performed to produce superhydrophobic surfaces of insulating layers by a lotus effect.

  8. Self-diffusion of charged colloidal tracer spheres in transparent porous glass media: Effect of ionic strength and pore size

    Science.gov (United States)

    Kluijtmans, Sebastiaan G. J. M.; de Hoog, Els H. A.; Philipse, Albert P.

    1998-05-01

    The influence of charge on diffusion in porous media was studied for fluorescent colloidal silica spheres diffusing in a porous glass medium. The bicontinuous porous silica glasses were optically matched with an organic solvent mixture in which both glass and tracers are negatively charged. Using fluorescence recovery after photobleaching, the long-time self-diffusion coefficient DSL of the confined silica particles was monitored in situ as a function of the ionic strength and particle to pore size ratio. At high salt concentration DSL reaches a relatively high plateau value, which depends on the particle to pore size ratio. This plateau value is unexpectedly higher than the value found for uncharged silica spheres in these porous glasses, but still significantly smaller than the free particle bulk diffusion coefficient of the silica spheres. At low salt concentration DSL reduces markedly, up to the point where colloids are nearly immobilized. This peculiar retardation probably originates from potential traps and barriers at pore intersections due to deviations from cylinder symmetry in the double layer interactions between tracers and pore walls. This indicates that diffusion of charged particles in tortuous porous media may be very different from transport in long capillaries without such intersections.

  9. Effect of Steam Activation on Development of Light Weight Biomorphic Porous SiC from Pine Wood Precursor

    Science.gov (United States)

    Manocha, Satish M.; Patel, Hemang; Manocha, L. M.

    2013-02-01

    Biomorphic SiC materials with tailor-made microstructure and properties similar to ceramic materials manufactured by conventional method are a new class of materials derived from natural biopolymeric cellulose templates (wood). Porous silicon carbide (SiC) ceramics with wood-like microstructure have been prepared by carbothermal reduction of charcoal/silica composites at 1300-1600 °C in inert Ar atmosphere. The C/SiO2 composites were fabricated by infiltrating silica sol into porous activated biocarbon template. Silica in the charcoal/silica composite, preferentially in the cellular pores, was found to get transformed in forms of fibers and rods due to shrinkage during drying. The changes in the morphology of resulting porous SiC ceramics after heat treatment to 1600 °C, as well as the conversion mechanism of wood to activated carbon and then to porous SiC ceramic have been investigated using scanning electron microscope, x-ray diffraction, thermogravimetric analysis, and differential scanning calorimetry. Activation of carbon prior to silica infiltration has been found to enhance conversion of charcoal to SiC. The pore structure is found to be uniform in these materials than in those made from as-such charcoal/silica composites. This provides a low-cost and eco-friendly route to advanced ceramic materials, with near-net shape potential.

  10. Exploring encapsulation mechanism of DNA and mononucleotides in sol-gel derived silica.

    Science.gov (United States)

    Kapusuz, Derya; Durucan, Caner

    2017-07-01

    The encapsulation mechanism of DNA in sol-gel derived silica has been explored in order to elucidate the effect of DNA conformation on encapsulation and to identify the nature of chemical/physical interaction of DNA with silica during and after sol-gel transition. In this respect, double stranded DNA and dAMP (2'-deoxyadenosine 5'-monophosphate) were encapsulated in silica using an alkoxide-based sol-gel route. Biomolecule-encapsulating gels have been characterized using UV-Vis, 29 Si NMR, FTIR spectroscopy and gas adsorption (BET) to investigate chemical interactions of biomolecules with the porous silica network and to examine the extent of sol-gel reactions upon encapsulation. Ethidium bromide intercalation and leach out tests showed that helix conformation of DNA was preserved after encapsulation. For both biomolecules, high water-to-alkoxide ratio promoted water-producing condensation and prevented alcoholic denaturation. NMR and FTIR analyses confirmed high hydraulic reactivity (water adsorption) for more silanol groups-containing DNA and dAMP encapsulated gels than plain silica gel. No chemical binding/interaction occurred between biomolecules and silica network. DNA and dAMP encapsulated silica gelled faster than plain silica due to basic nature of DNA or dAMP containing buffer solutions. DNA was not released from silica gels to aqueous environment up to 9 days. The chemical association between DNA/dAMP and silica host was through phosphate groups and molecular water attached to silanols, acting as a barrier around biomolecules. The helix morphology was found not to be essential for such interaction. BET analyses showed that interconnected, inkbottle-shaped mesoporous silica network was condensed around DNA and dAMP molecules.

  11. Ion-Exchange-Induced Selective Etching for the Synthesis of Amino-Functionalized Hollow Mesoporous Silica for Elevated-High-Temperature Fuel Cells.

    Science.gov (United States)

    Zhang, Jin; Liu, Jian; Lu, Shanfu; Zhu, Haijin; Aili, David; De Marco, Roland; Xiang, Yan; Forsyth, Maria; Li, Qingfeng; Jiang, San Ping

    2017-09-20

    As differentiated from conventional synthetic processes, amino-functionalized hollow mesoporous silica (NH 2 -HMS) has been synthesized using a new and facile strategy of ion-exchange-induced selective etching of amino-functionalized mesoporous silica (NH 2 -meso-silica) by an alkaline solution. Nuclear magnetic resonance (NMR) spectroscopy and in situ time-resolved small-angle X-ray scattering (SAXS) reveal that ion-exchange-induced selective etching arises from the gradient distribution of OH - in the NH 2 -meso-silica nanospheres. Moreover, the ion-exchange-induced selective etching mechanism is verified through a successful synthesis of hollow mesoporous silica. After infiltration with phosphotungstic acid (PWA), PWA-NH 2 -HMS nanoparticles are dispersed in the poly(ether sulfone)-polyvinylpyrrolidone (PES-PVP) matrix, forming a hybrid PWA-NH 2 -HMS/PES-PVP nanocomposite membrane. The resultant nanocomposite membrane with an optimum loading of 10 wt % of PWA-NH 2 -HMS showed an enhanced proton conductivity of 0.175 S cm -1 and peak power density of 420 mW cm -2 at 180 °C under anhydrous conditions. Excellent durability of the hybrid composite membrane fuel cell has been demonstrated at 200 °C. The results of this study demonstrated the potential of the facile synthetic strategy in the fabrication of NH 2 -HMS with controlled mesoporous structure for application in nanocomposite membranes as a technology platform for elevated-temperature proton exchange membrane fuel cells.

  12. Preparation of porous bio-char and activated carbon from rice husk by leaching ash and chemical activation.

    Science.gov (United States)

    Ahiduzzaman, Md; Sadrul Islam, A K M

    2016-01-01

    Preparation porous bio-char and activated carbon from rice husk char study has been conducted in this study. Rice husk char contains high amount silica that retards the porousness of bio-char. Porousness of rice husk char could be enhanced by removing the silica from char and applying heat at high temperature. Furthermore, the char is activated by using chemical activation under high temperature. In this study no inert media is used. The study is conducted at low oxygen environment by applying biomass for consuming oxygen inside reactor and double crucible method (one crucible inside another) is applied to prevent intrusion of oxygen into the char. The study results shows that porous carbon is prepared successfully without using any inert media. The adsorption capacity of material increased due to removal of silica and due to the activation with zinc chloride compared to using raw rice husk char. The surface area of porous carbon and activated carbon are found to be 28, 331 and 645 m(2) g(-1) for raw rice husk char, silica removed rice husk char and zinc chloride activated rice husk char, respectively. It is concluded from this study that porous bio-char and activated carbon could be prepared in normal environmental conditions instead of inert media. This study shows a method and possibility of activated carbon from agro-waste, and it could be scaled up for commercial production.

  13. Caustic meso-optical confocal microscope for vertical particle tracks. Proposal

    International Nuclear Information System (INIS)

    Soroko, L.M.

    1995-01-01

    The principal of the proposed caustic meso-optical microscope for vertical particle tracks in the nuclear photoemulsion is explained. The results of the experiments performed to illustrate the main features of this new meso-optical microscope are given. The proposed caustic meso-optical microscope for vertical particle tracks in the nuclear photoemulsion can be effectively used in the experimental investigation of such rare processes as ν μ - ν τ oscillations and of the Pb-Pb interactions. 2 refs., 7 figs

  14. Pore fabrication in various silica-based nanoparticles by controlled etching

    KAUST Repository

    Zhao, Lan

    2010-07-20

    A novel method based on controlled etching was developed to fabricate nanopores on preformed silica nanoparticles (<100 nm in diameter). The obtained monodisperse nanoporous particles could form highly stable homogeneous colloidal solution. Fluorescent silica nanoparticles and magnetic silica-coated γ-Fe 2O 3 nanoparticles were investigated as examples to illustrate that this strategy could be generally applied to various silica-based functional nanoparticles. The results indicated that this method was effective for generating pores on these nanoparticles without altering their original functionalities. The obtained multifunctional nanoparticles would be useful for many biological and biomedical applications. These porous nanoparticles could also serve as building blocks to fabricate three-dimensionally periodic structures that have the potential to be used as photonic crystals. © 2010 American Chemical Society.

  15. Synthesis of hierarchically meso-macroporous TiO2/CdS heterojunction photocatalysts with excellent visible-light photocatalytic activity.

    Science.gov (United States)

    Zhao, Haixin; Cui, Shu; Yang, Lan; Li, Guodong; Li, Nan; Li, Xiaotian

    2018-02-15

    Photocatalysts with a hierarchically porous structure have attracted considerable attention owing to their wide pore size distribution and high surface area, which enhance the efficiency of transporting species to active sites. In this study, hierarchically meso-macroporous TiO 2 photocatalysts decorated with highly dispersed CdS nanoparticles were synthesized via hydrolysis, followed by a hydrothermal treatment. The textural mesopores and interconnected pore framework provided more accessible active sites and efficient mass transport for the photocatalytic process. The light collection efficiency was enhanced because of multiple scattering of incident light in the macropores. Moreover, the formation of a heterojunction between the CdS and TiO 2 nanoparticles extended the photoresponse of TiO 2 to the visible-light range and enhanced the charge separation efficiency. Therefore, the hierarchically meso-macroporous TiO 2 /CdS photocatalysts exhibited excellent photocatalytic activity for the degradation of rhodaming B under visible-light irradiation. Trapping experiments demonstrated that superoxide radicals (O 2 - ) and hydroxyl radicals (OH) were the main active species in photocatalysis. A reasonable photocatalytic mechanism of TiO 2 /CdS heterojunction photocatalysts was also presented. Copyright © 2017 Elsevier Inc. All rights reserved.

  16. Impact of water mobility in some porous media on migration of radio isotopes to the geosphere

    International Nuclear Information System (INIS)

    AL-Hajji, E.

    2011-07-01

    The aim of this work is to study the behavior of the water state (bound /free water) in porous materials such as illite and bentonite. These materials are widely used in the storage of radioactive waste. The study was carried out using proton nuclear magnetic resonance technique (NMR). That permits to understand the mechanism of leakage of radioactive elements from these porous materials to the surrounding environment. Such a leakage may have very serious consequences like the contamination of groundwater. In addition, other porous materials like silica and alumina, the two main composite of bentonite, have been studied as well.(author)

  17. Silica particles and method of preparation thereof

    NARCIS (Netherlands)

    2015-01-01

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

  18. Citrus pectin derived porous carbons as a superior adsorbent toward removal of methylene blue

    International Nuclear Information System (INIS)

    Zhang, Wenlin; Zhang, Lian Ying; Zhao, Xi Juan; Zhou, Zhiqin

    2016-01-01

    An adsorbent, citrus pectin derived porous carbons with ultra-high adsorption capacity, rapid adsorption rate and good reusability toward removal of methylene blue, was synthesized by a facile zinc chloride activation approach in this study. The materials hold a great potential for treatment of dye wastewater. - Graphical abstract: Citrus pectin derived porous carbons with ultra-high adsorption capacity, rapid adsorption rate and good reusability toward methylene blue removal. - Highlights: • Citrus pectin derived porous carbons (CPPCs) were synthesized a facile zinc chloride activation approach. • CPPCs had abundant macro/meso/micropores for trapping MB molecules. • CPPCs exhibited ultrahigh adsorption capacity, rapid adsorption rate and good reusability toward removal of MB.

  19. Citrus pectin derived porous carbons as a superior adsorbent toward removal of methylene blue

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Wenlin [College of Horticulture and landscape Architecture, Southwest University, Chongqing 400716 (China); Zhang, Lian Ying [Institute for Clean Energy & Advanced Materials, Southwest University, Chongqing 400715 (China); Zhao, Xi Juan [College of Horticulture and landscape Architecture, Southwest University, Chongqing 400716 (China); Key Laboratory of Horticulture Science for Southern Mountainous Regions, Ministry of Education, Chongqing 400715 (China); Zhou, Zhiqin, E-mail: zhouzhiqin@swu.edu.cn [College of Horticulture and landscape Architecture, Southwest University, Chongqing 400716 (China); Key Laboratory of Horticulture Science for Southern Mountainous Regions, Ministry of Education, Chongqing 400715 (China)

    2016-11-15

    An adsorbent, citrus pectin derived porous carbons with ultra-high adsorption capacity, rapid adsorption rate and good reusability toward removal of methylene blue, was synthesized by a facile zinc chloride activation approach in this study. The materials hold a great potential for treatment of dye wastewater. - Graphical abstract: Citrus pectin derived porous carbons with ultra-high adsorption capacity, rapid adsorption rate and good reusability toward methylene blue removal. - Highlights: • Citrus pectin derived porous carbons (CPPCs) were synthesized a facile zinc chloride activation approach. • CPPCs had abundant macro/meso/micropores for trapping MB molecules. • CPPCs exhibited ultrahigh adsorption capacity, rapid adsorption rate and good reusability toward removal of MB.

  20. A novel gel combustion procedure for the preparation of foam and porous pellets of UO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Sanjay Kumar, D. [Fuel Chemistry Division, Materials Chemistry and Metal Fuel Cycle Group, Homi Bhabha National Institute, Indira Gandhi Centre for Atomic Research, Kalpakkam, 603102, Tamil Nadu (India); Ananthasivan, K., E-mail: asivan@igcar.gov.in [Fuel Chemistry Division, Materials Chemistry and Metal Fuel Cycle Group, Homi Bhabha National Institute, Indira Gandhi Centre for Atomic Research, Kalpakkam, 603102, Tamil Nadu (India); Venkata Krishnan, R.; Maji, Dasarath [Fuel Chemistry Division, Materials Chemistry and Metal Fuel Cycle Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, 603102, Tamil Nadu (India); Dasgupta, Arup [Microscopy and Thermo-Physical Property Division, Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Homi Bhabha National Institute, Kalpakkam, 603102, Tamil Nadu (India)

    2017-01-15

    In this study, it has been demonstrated for the first time how sucrose gel-combustion could be used for the preparation of UO{sub 2} foam. Further the citrate gel-combustion was gainfully used for preparing porous pellets of UO{sub 2}. The utility of two-step sintering (1073 K for 30 min and 1473 K for 4 h) for obtaining these porous bodies was demonstrated for the first time. The foams and pellets possessed meso and macro pores. A starting mixture with sucrose to nitrate ratio of 2.4 was found to yield urania foam with adequate crush strength. The porous pellets were found to possess better handling strength, lesser carbon residue and higher overall density than the foam. A citric acid to nitrate ratio 0.25 in the starting mixture, 180 MPa compaction pressure were optimal for obtaining a pellet with 40% porosity. - Highlights: • Urania foam was successfully prepared for the first time by using sucrose-gel precursor method. • Porous urania pellets were successfully prepared for the first time by using citrate gel-combustion method. • The foam comprised both meso and macro pores, possessed good crush strength and porosity. • Citric acid to nitrate ratio of 0.25 and a compaction pressure of 180 MPa were best suited for the preparation of porous pellets.

  1. Research on the Ordered Mesoporous Silica for Tobacco Harm Reduction

    Science.gov (United States)

    Wang, Y.; Y Li, Z.; Ding, J. X.; Hu, Z. J.; Liu, Z.; Zhou, G.; Huang, T. H.

    2017-12-01

    For reducting tobacco harm, this paper prepared an ordered mesoporous silica by using triblock copolymer Pluronic P123 as template. The property of this material was characterized by the X-ray scattering spectrum(XRD), Transmission electron microscopy(TEM), Scanning electron microscopy (SEM) and Nitrogen adsorption/desorption. Then this ordered mesoporous silica was added into the cigarette filter in order to researching its effect of cigarette harm index. The result shows that the feature of SBA-15 was grain morphology, ordered arrangement, tubular porous 2-D hexagonal structure. The application of SBA-15 in cigarette filter can selectively reduce harmful components in cigarette smoke such as crotonaldehyde, hydrogen cyanide, benzo pyrene and tar. The synthesized SBA-15 could properly reduce cigarette harm index.

  2. 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

  3. Supercritical carbon dioxide versus toluene as reaction media in silica functionalisation: Synthesis and characterisation of bonded aminopropyl silica intermediate.

    Science.gov (United States)

    Ashu-Arrah, Benjamin A; Glennon, Jeremy D

    2017-06-09

    This research reports supercritical carbon dioxide versus toluene as reaction media in silica functionalisation for use in liquid chromatography. Bonded aminopropyl silica (APS) intermediates were prepared when porous silica particles (Exsil-pure, 3μm) were reacted with 3-aminopropyltriethoxysilane (3-APTES) or N,N-dimethylaminopropyltrimethoxysilane (DMAPTMS) using supercritical carbon dioxide (sc-CO 2 ) and toluene as reaction media. Covalent bonding to silica was confirmed using elemental microanalysis (CHN), thermogravimetric analysis (TGA), zeta potential (ξ), diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, scanning electron microscopy (SEM) and solid-state nuclear magnetic resonance (CP/MAS NMR) spectroscopy. The results demonstrate that under sc-CO 2 conditions of 100°C/414bar in a substantial reduced time of 3h, the surface coverage of APS (evaluated from%C obtained from elemental analysis) prepared with APTES (%C: 8.03, 5.26μmol/m -2 ) or DMAPTES (%C: 5.12, 4.58μmol/m 2 ) is somewhat higher when compared to organic based reactions under reflux in toluene at a temperature of 110°C in 24h with APTES (%C: 7.33, 4.71μmol/m 2 ) and DMAPTMS (%C: 4.93, 4.38μmol/m 2 ). Zeta potential measurements revealed a change in electrostatic surface charge from negative values for bare Exsil-pure silica to positive for functionalised APS materials indicating successful immobilization of the aminosilane onto the surface of silica. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Serpentinization processes: Influence of silica

    Science.gov (United States)

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

    2016-12-01

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

  5. High-density oxidized porous silicon

    International Nuclear Information System (INIS)

    Gharbi, Ahmed; Souifi, Abdelkader; Remaki, Boudjemaa; Halimaoui, Aomar; Bensahel, Daniel

    2012-01-01

    We have studied oxidized porous silicon (OPS) properties using Fourier transform infraRed (FTIR) spectroscopy and capacitance–voltage C–V measurements. We report the first experimental determination of the optimum porosity allowing the elaboration of high-density OPS insulators. This is an important contribution to the research of thick integrated electrical insulators on porous silicon based on an optimized process ensuring dielectric quality (complete oxidation) and mechanical and chemical reliability (no residual pores or silicon crystallites). Through the measurement of the refractive indexes of the porous silicon (PS) layer before and after oxidation, one can determine the structural composition of the OPS material in silicon, air and silica. We have experimentally demonstrated that a porosity approaching 56% of the as-prepared PS layer is required to ensure a complete oxidation of PS without residual silicon crystallites and with minimum porosity. The effective dielectric constant values of OPS materials determined from capacitance–voltage C–V measurements are discussed and compared to FTIR results predictions. (paper)

  6. Asymmetric Horner-Wadsworth-Emmons Reactions with meso-Dialdehydes: Scope, Mechanism, and Synthetic Applications

    DEFF Research Database (Denmark)

    Rein, Tobias; Vares, Lauri; Kawasaki, Ikuo

    1999-01-01

    Asymmetric Homer-Wadsworth-Emmons reactions between chiral phosphonate reagents and various meso-dialdehydes have been investigated. A mechanistic model useful for rationalizing the experimentally observed stereoselectivities is presented. Furthermore; strategies for applying these reactions...

  7. Validation of Micro-Meso Electrical Relations for Laminates with Varying Anisotropy

    KAUST Repository

    Selvakumaran, Lakshmi; Lubineau, Gilles

    2015-01-01

    For electrical impedance tomography (EIT) to be useful in monitoring transverse cracks in composites, it is imperative to establish the relation between conductivity and cracking density. Micro to meso scale homogenization has been developed

  8. Controlled in meso phase crystallization--a method for the structural investigation of membrane proteins.

    Directory of Open Access Journals (Sweden)

    Jan Kubicek

    Full Text Available We investigated in meso crystallization of membrane proteins to develop a fast screening technology which combines features of the well established classical vapor diffusion experiment with the batch meso phase crystallization, but without premixing of protein and monoolein. It inherits the advantages of both methods, namely (i the stabilization of membrane proteins in the meso phase, (ii the control of hydration level and additive concentration by vapor diffusion. The new technology (iii significantly simplifies in meso crystallization experiments and allows the use of standard liquid handling robots suitable for 96 well formats. CIMP crystallization furthermore allows (iv direct monitoring of phase transformation and crystallization events. Bacteriorhodopsin (BR crystals of high quality and diffraction up to 1.3 Å resolution have been obtained in this approach. CIMP and the developed consumables and protocols have been successfully applied to obtain crystals of sensory rhodopsin II (SRII from Halobacterium salinarum for the first time.

  9. Multi-template synthesis of hierarchically porous carbon spheres with potential application in supercapacitors

    NARCIS (Netherlands)

    Zhou, Weizheng; Lin, Zhixing; Tong, Gangsheng; Stoyanov, Simeon D.; Yan, Deyue; Mai, Yiyong; Zhu, Xinyuan

    2016-01-01

    A new and simple multi-template approach towards hierarchical porous carbon (HPC) materials was reported. HPC spheres were prepared by using hierarchical silica capsules (HSCs) as the hard template and triblock copolymer Pluronic P123 as the soft template. Three types of pores were tunably

  10. Immobilization of plutonium from solutions on porous matrices by the method of high temperature sorption

    Energy Technology Data Exchange (ETDEWEB)

    Nardova, A.K.; Filippov, E.A. [All Research Institute of Chemical Technologies, Moscow (Russian Federation); Glagolenko, Y.B. [and others

    1996-05-01

    This report presents the results of investigations of plutonium immobilization from solutions on inorganic matrices with the purpose of producing a solid waste form. High-temperature sorption is described which entails the adsorption of radionuclides from solutions on porous, inorganic matrices, as for example silica gel. The solution is brought to a boil with additional thermal process (calcination) of the saturated granules.

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

    Science.gov (United States)

    Lei, Qiong

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

  12. Pulse electrochemical meso/micro/nano ultraprecision machining technology.

    Science.gov (United States)

    Lee, Jeong Min; Kim, Young Bin; Park, Jeong Woo

    2013-11-01

    This study demonstrated meso/micro/nano-ultraprecision machining through electrochemical reactions using intermittent DC pulses. The experiment focused on two machining methods: (1) pulse electrochemical polishing (PECP) of stainless steel, and (2) pulse electrochemical nano-patterning (PECNP) on a silicon (Si) surface, using atomic force microscopy (AFM) for fabrication. The dissolution reaction at the stainless steel surface following PECP produced a very clean, smooth workpiece. The advantages of the PECP process included improvements in corrosion resistance, deburring of the sample surface, and removal of hydrogen from the stainless steel surface as verified by time-of-flight secondary-ion mass spectrometry (TOF-SIMS). In PECNP, the electrochemical reaction generated within water molecules produced nanoscale oxide textures on a Si surface. Scanning probe microscopy (SPM) was used to evaluate nanoscale-pattern processing on a Si wafer surface produced by AFM-PECNP For both processes using pulse electrochemical reactions, three-dimensional (3-D) measurements and AFM were used to investigate the changes on the machined surfaces. Preliminary results indicated the potential for advancing surface polishing techniques and localized micro/nano-texturing technology using PECP and PECNP processes.

  13. Implementation of meso-scale radioactive dispersion model for GPU

    Energy Technology Data Exchange (ETDEWEB)

    Sunarko [National Nuclear Energy Agency of Indonesia (BATAN), Jakarta (Indonesia). Nuclear Energy Assessment Center; Suud, Zaki [Bandung Institute of Technology (ITB), Bandung (Indonesia). Physics Dept.

    2017-05-15

    Lagrangian Particle Dispersion Method (LPDM) is applied to model atmospheric dispersion of radioactive material in a meso-scale of a few tens of kilometers for site study purpose. Empirical relationships are used to determine the dispersion coefficient for various atmospheric stabilities. Diagnostic 3-D wind-field is solved based on data from one meteorological station using mass-conservation principle. Particles representing radioactive pollutant are dispersed in the wind-field as a point source. Time-integrated air concentration is calculated using kernel density estimator (KDE) in the lowest layer of the atmosphere. Parallel code is developed for GTX-660Ti GPU with a total of 1 344 scalar processors using CUDA. A test of 1-hour release discovers that linear speedup is achieved starting at 28 800 particles-per-hour (pph) up to about 20 x at 14 4000 pph. Another test simulating 6-hour release with 36 000 pph resulted in a speedup of about 60 x. Statistical analysis reveals that resulting grid doses are nearly identical in both CPU and GPU versions of the code.

  14. Dynamics of meso and thermo citrate synthases with implicit solvation

    Science.gov (United States)

    Cordeiro, J. M. M.

    The dynamics of hydration of meso and thermo citrate synthases has been investigated using the EEF1 methodology implemented with the CHARMM program. The native enzymes are composed of two identical subunits, each divided into a small and large domain. The dynamics behavior of both enzymes at 30°C and 60°C has been compared. The results of simulations show that during the hydration process, each subunit follows a different pathway of hydration, in spite of the identical sequence. The hydrated structures were compared with the crystalline structure, and the root mean square deviation (RMSD) of each residue along the trajectory was calculated. The regions with larger and smaller mobility were identified. In particular, helices belonging to the small domain are more mobile than those of the large domain. In contrast, the residues that constitute the active site show a much lower displacement compared with the crystalline structure. Hydration free energy calculations point out that Thermoplasma acidophilum citrate synthase (TCS) is more stable than chicken citrate synthase (CCS), at high temperatures. Such result has been ascribed to the higher number of superficial charges in the thermophilic homologue, which stabilizes the enzyme, while the mesophilic homologue denatures. These results are in accord with the experimental found that TCS keeps activity at temperatures farther apart from the catalysis regular temperature than the CCS.

  15. MICRO-SEISMOMETERS VIA ADVANCED MESO-SCALE FABRICATION

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, Caesar A; Onaran, Guclu; Avenson, Brad; Hall, Neal

    2014-11-07

    The Department of Energy (DOE) and the National Nuclear Security Administration (NNSA) seek revolutionary sensing innovations for the monitoring of nuclear detonations. Performance specifications are to be consistent with those obtainable by only an elite few products available today, but with orders of magnitude reduction in size, weight, power, and cost. The proposed commercial innovation calls upon several technologies including the combination of meso-scale fabrication and assembly, photonics-based displacement / motion detection methods, and the use of digital control electronics . Early Phase II development has demonstrated verified and repeatable sub 2ng noise floor from 3Hz to 100Hz, compact integration of 3-axis prototypes, and robust deployment exercises. Ongoing developments are focusing on low frequency challenges, low power consumption, ultra-miniature size, and low cross axis sensitivity. We are also addressing the rigorous set of specifications required for repeatable and reliable long-term explosion monitoring, including thermal stability, reduced recovery time from mass re-centering and large mechanical shocks, sensitivity stability, and transportability. Successful implementation will result in small, hand-held demonstration units with the ability to address national security needs of the DOE/NNSA. Additional applications envisioned include military/defense, scientific instrumentation, oil and gas exploration, inertial navigation, and civil infrastructure monitoring.

  16. Flame dynamics of a meso-scale heat recirculating combustor

    Energy Technology Data Exchange (ETDEWEB)

    Vijayan, V.; Gupta, A.K. [Department of Mechanical Engineering, University of Maryland, College Park, MD 20742 (United States)

    2010-12-15

    The dynamics of premixed propane-air flame in a meso-scale ceramic combustor has been examined here. The flame characteristics in the combustor were examined by measuring the acoustic emissions and preheat temperatures together with high-speed cinematography. For the small-scale combustor, the volume to surface area ratio is small and hence the walls have significant effect on the global flame structure, flame location and flame dynamics. In addition to the flame-wall thermal coupling there is a coupling between flame and acoustics in the case of confined flames. Flame-wall thermal interactions lead to low frequency flame fluctuations ({proportional_to}100 Hz) depending upon the thermal response of the wall. However, the flame-acoustic interactions can result in a wide range of flame fluctuations ranging from few hundred Hz to few kHz. Wall temperature distribution is one of the factors that control the amount of reactant preheating which in turn effects the location of flame stabilization. Acoustic emission signals and high-speed flame imaging confirmed that for the present case flame-acoustic interactions have more significant effect on flame dynamics. Based on the acoustic emissions, five different flame regimes have been identified; whistling/harmonic mode, rich instability mode, lean instability mode, silent mode and pulsating flame mode. (author)

  17. Hierarchical Porous Structures

    Energy Technology Data Exchange (ETDEWEB)

    Grote, Christopher John [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-06-07

    Materials Design is often at the forefront of technological innovation. While there has always been a push to generate increasingly low density materials, such as aero or hydrogels, more recently the idea of bicontinuous structures has gone more into play. This review will cover some of the methods and applications for generating both porous, and hierarchically porous structures.

  18. Dual Tuning of Biomass-Derived Hierarchical Carbon Nanostructures for Supercapacitors: the Role of Balanced Meso/Microporosity and Graphene

    Science.gov (United States)

    Zhu, Zhengju; Jiang, Hao; Guo, Shaojun; Cheng, Qilin; Hu, Yanjie; Li, Chunzhong

    2015-10-01

    Rational design of advanced carbon nanomaterials with a balanced mesoporosity to microporosity is highly desirable for achieving high energy/power density for supercapacitors because the mesopore can allow better transport pathways for the solvated ions of larger than 1 nm. Inspired by the inherent meso/macroporous architecture and huge absorption ability to aqueous solution of auricularia biomass, we demonstrate a new biomass-derived synthesis process for the three-dimensional (3D) few-layered graphene nanosheets incorporated hierarchical porous carbon (GHPC) nanohybrids. The as-prepared GHPC nanohybrids possess a balanced mesoporosity to microporosity with much improved conductivity, which is highly desirable for achieving high energy/power density for supercapacitors. As we predicted, they delivered a high specific capacitance of 256 F g-1 at 1 A g-1 with excellent rate capability (120 F g-1 at 50 A g-1) and long cycle life (92% capacity retention after 10000 cycles) for symmetric supercapacitors in 1 M H2SO4. Based on the as-obtained carbon materials, a flexible and all-solid-state supercapacitor was also assembled, which can be fully recharged within 10 s and able to light an LED even under bended state. Such excellent performance is at least comparable to the best reports in the literature for two-electrode configuration under aqueous systems.

  19. Biochar-based carbons with hierarchical micro-meso-macro porosity for high rate and long cycle life supercapacitors

    Science.gov (United States)

    Qiu, Zhipeng; Wang, Yesheng; Bi, Xu; Zhou, Tong; Zhou, Jin; Zhao, Jinping; Miao, Zhichao; Yi, Weiming; Fu, Peng; Zhuo, Shuping

    2018-02-01

    The development of supercapacitors with high energy density and power density is an important research topic despite many challenging issues exist. In this work, porous carbon material was prepared from corn straw biochar and used as the active electrode material for electric double-layer capacitors (EDLCs). During the KOH activation process, the ratio of KOH/biochar significantly affects the microstructure of the resultant carbon, which further influences the capacitive performance. The optimized carbon material possesses typical hierarchical porosity composed of multi-leveled pores with high surface area and pore volume up to 2790.4 m2 g-1 and 2.04 cm3 g-1, respectively. Such hierarchical micro-meso-macro porosity significantly improved the rate performance of the biochar-based carbons. The achieved maximum specific capacitance was 327 F g-1 and maintained a high value of 205 F g-1 at a ultrahigh current density of 100 A g-1. Meanwhile, the prepared EDLCs present excellent cycle stability in alkaline electrolytes for 120 000 cycles at 5 A g-1. Moreover, the biochar-based carbon could work at a high voltage of 1.6 V in neutral Na2SO4, and exhibit a high specific capacitance of 227 F g-1, thus giving an outstanding energy density of 20.2 Wh kg-1.

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

    Directory of Open Access Journals (Sweden)

    Hao Ma

    2018-01-01

    Full Text Available 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.

  1. 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.

  2. Boiling in porous media

    International Nuclear Information System (INIS)

    1998-01-01

    This conference day of the French society of thermal engineers was devoted to the analysis of heat transfers and fluid flows during boiling phenomena in porous media. This book of proceedings comprises 8 communications entitled: 'boiling in porous medium: effect of natural convection in the liquid zone'; 'numerical modeling of boiling in porous media using a 'dual-fluid' approach: asymmetrical characteristic of the phenomenon'; 'boiling during fluid flow in an induction heated porous column'; 'cooling of corium fragment beds during a severe accident. State of the art and the SILFIDE experimental project'; 'state of knowledge about the cooling of a particulates bed during a reactor accident'; 'mass transfer analysis inside a concrete slab during fire resistance tests'; 'heat transfers and boiling in porous media. Experimental analysis and modeling'; 'concrete in accidental situation - influence of boundary conditions (thermal, hydric) - case studies'. (J.S.)

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

    African Journals Online (AJOL)

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

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

    NARCIS (Netherlands)

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

    2008-01-01

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

  5. Pecan drying with silica gel

    Energy Technology Data Exchange (ETDEWEB)

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

    1983-07-01

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

  6. Impact of surface impurity on phase transitions in amorphous micro silica

    DEFF Research Database (Denmark)

    Haastrup, Sonja; Yu, Donghong; Yue, Yuanzheng

    2016-01-01

    In this work we study three types of spherically shaped micron and submicron sized amorphous micro silica (MS) as common raw material for production of porous calcium silicate products used for insulation, which are selected on basis of chemical composition and production method. Two of them have...... silica content of 96% (from silicon production) and one has that of 92% (from ferro-silicon production). In order to achieve high quality calcium silicate products, which strongly depends on the characteristics of the raw MS, it is crucial to study the chemical and physical properties of the raw MS...

  7. Thermal insulator made of ultra fine particles of silica. Chobiryushi silica kei dannetsuzai

    Energy Technology Data Exchange (ETDEWEB)

    Eguchi, T.

    1991-05-30

    An overview was presented of properties and applications of thermal insulator made of ultra fine powder of silica, MICROTHERM. The thermal conductivity of MICROTHERM is as low as (1/3) - (1/4) of that of conventional thermal insulator, because it is mainly composed of fumed silica or aero gel and formed into porous structure. In addition, metal oxide of special particle size is added to it in order to reject the radiative heat. The thermal insulation property and the mechanical strength of MICROTHERM is not affected by a sudden change in temperature and moisture. The standard type of MICROTHERM can be used at a temperature up to 950 {degree}C, while the high temperature type MICROTHERM can stand a high temperature up to 1025 {degree}C for long period of time. The thickness of insulator can be reduced markedly by using MICROTHERM as compared with the use of conventional insulating materials. Many new products in which MICROTHERM is used came into market. New type kilt, Semi-cylindrical block, Super high temperature MICROTHERM are just a few examples. Variety of application and energy saving effect are attracting public attention. 11 figs.

  8. Probabilistic flood damage modelling at the meso-scale

    Science.gov (United States)

    Kreibich, Heidi; Botto, Anna; Schröter, Kai; Merz, Bruno

    2014-05-01

    Decisions on flood risk management and adaptation are usually based on risk analyses. Such analyses are associated with significant uncertainty, even more if changes in risk due to global change are expected. Although uncertainty analysis and probabilistic approaches have received increased attention during the last years, they are still not standard practice for flood risk assessments. Most damage models have in common that complex damaging processes are described by simple, deterministic approaches like stage-damage functions. Novel probabilistic, multi-variate flood damage models have been developed and validated on the micro-scale using a data-mining approach, namely bagging decision trees (Merz et al. 2013). In this presentation we show how the model BT-FLEMO (Bagging decision Tree based Flood Loss Estimation MOdel) can be applied on the meso-scale, namely on the basis of ATKIS land-use units. The model is applied in 19 municipalities which were affected during the 2002 flood by the River Mulde in Saxony, Germany. The application of BT-FLEMO provides a probability distribution of estimated damage to residential buildings per municipality. Validation is undertaken on the one hand via a comparison with eight other damage models including stage-damage functions as well as multi-variate models. On the other hand the results are compared with official damage data provided by the Saxon Relief Bank (SAB). The results show, that uncertainties of damage estimation remain high. Thus, the significant advantage of this probabilistic flood loss estimation model BT-FLEMO is that it inherently provides quantitative information about the uncertainty of the prediction. Reference: Merz, B.; Kreibich, H.; Lall, U. (2013): Multi-variate flood damage assessment: a tree-based data-mining approach. NHESS, 13(1), 53-64.

  9. Meso-scale modeling of irradiated concrete in test reactor

    International Nuclear Information System (INIS)

    Giorla, A.; Vaitová, M.; Le Pape, Y.; Štemberk, P.

    2015-01-01

    Highlights: • A meso-scale finite element model for irradiated concrete is developed. • Neutron radiation-induced volumetric expansion is a predominant degradation mode. • Confrontation with expansion and damage obtained from experiments is successful. • Effects of paste shrinkage, creep and ductility are discussed. - Abstract: A numerical model accounting for the effects of neutron irradiation on concrete at the mesoscale is detailed in this paper. Irradiation experiments in test reactor (Elleuch et al., 1972), i.e., in accelerated conditions, are simulated. Concrete is considered as a two-phase material made of elastic inclusions (aggregate) subjected to thermal and irradiation-induced swelling and embedded in a cementitious matrix subjected to shrinkage and thermal expansion. The role of the hardened cement paste in the post-peak regime (brittle-ductile transition with decreasing loading rate), and creep effects are investigated. Radiation-induced volumetric expansion (RIVE) of the aggregate cause the development and propagation of damage around the aggregate which further develops in bridging cracks across the hardened cement paste between the individual aggregate particles. The development of damage is aggravated when shrinkage occurs simultaneously with RIVE during the irradiation experiment. The post-irradiation expansion derived from the simulation is well correlated with the experimental data and, the obtained damage levels are fully consistent with previous estimations based on a micromechanical interpretation of the experimental post-irradiation elastic properties (Le Pape et al., 2015). The proposed modeling opens new perspectives for the interpretation of test reactor experiments in regards to the actual operation of light water reactors.

  10. Meso-scale modeling of irradiated concrete in test reactor

    Energy Technology Data Exchange (ETDEWEB)

    Giorla, A. [Oak Ridge National Laboratory, One Bethel Valley Road, Oak Ridge, TN 37831 (United States); Vaitová, M. [Czech Technical University, Thakurova 7, 166 29 Praha 6 (Czech Republic); Le Pape, Y., E-mail: lepapeym@ornl.gov [Oak Ridge National Laboratory, One Bethel Valley Road, Oak Ridge, TN 37831 (United States); Štemberk, P. [Czech Technical University, Thakurova 7, 166 29 Praha 6 (Czech Republic)

    2015-12-15

    Highlights: • A meso-scale finite element model for irradiated concrete is developed. • Neutron radiation-induced volumetric expansion is a predominant degradation mode. • Confrontation with expansion and damage obtained from experiments is successful. • Effects of paste shrinkage, creep and ductility are discussed. - Abstract: A numerical model accounting for the effects of neutron irradiation on concrete at the mesoscale is detailed in this paper. Irradiation experiments in test reactor (Elleuch et al., 1972), i.e., in accelerated conditions, are simulated. Concrete is considered as a two-phase material made of elastic inclusions (aggregate) subjected to thermal and irradiation-induced swelling and embedded in a cementitious matrix subjected to shrinkage and thermal expansion. The role of the hardened cement paste in the post-peak regime (brittle-ductile transition with decreasing loading rate), and creep effects are investigated. Radiation-induced volumetric expansion (RIVE) of the aggregate cause the development and propagation of damage around the aggregate which further develops in bridging cracks across the hardened cement paste between the individual aggregate particles. The development of damage is aggravated when shrinkage occurs simultaneously with RIVE during the irradiation experiment. The post-irradiation expansion derived from the simulation is well correlated with the experimental data and, the obtained damage levels are fully consistent with previous estimations based on a micromechanical interpretation of the experimental post-irradiation elastic properties (Le Pape et al., 2015). The proposed modeling opens new perspectives for the interpretation of test reactor experiments in regards to the actual operation of light water reactors.

  11. Fabricating porous silicon carbide

    Science.gov (United States)

    Shor, Joseph S. (Inventor); Kurtz, Anthony D. (Inventor)

    1994-01-01

    The formation of porous SiC occurs under electrochemical anodization. A sample of SiC is contacted electrically with nickel and placed into an electrochemical cell which cell includes a counter electrode and a reference electrode. The sample is encapsulated so that only a bare semiconductor surface is exposed. The electrochemical cell is filled with an HF electrolyte which dissolves the SiC electrochemically. A potential is applied to the semiconductor and UV light illuminates the surface of the semiconductor. By controlling the light intensity, the potential and the doping level, a porous layer is formed in the semiconductor and thus one produces porous SiC.

  12. An oral delivery system for indomethicin engineered from cationic lipid emulsions and silica nanoparticles

    DEFF Research Database (Denmark)

    Simovic, Spomenka; Hui, He; Song, Yunmei

    2010-01-01

    We report on a porous silica-lipid hybrid microcapsule (SLH) oral delivery system for indomethacin fabricated from Pickering emulsion templates, where the drug forms an electrostatic complex with cationic lipid present in the oil phase. Dry SLH microcapsules prepared either by spray drying...... (approximately 1-5 microm) or phase coacervation (20-50 microm) exhibit a specific internal porous matrix structure with pore diameters in the range of 20 to 100 nm. Dissolution studies under sink conditions and in the presence of electrolytes revealed a decreased extent of dissolution; this confirms...

  13. 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

  14. Adsorption of uranyl in SiO2 porous glass

    International Nuclear Information System (INIS)

    Benedetto, F. E.; Prado, M. O.

    2013-01-01

    Vitreous SiO 2 porous matrices can be used in many applications involving the uptake of chemical species on its solid surface. In this work, vitreous silica sponges were prepared from a sodium borosilicate glass manufactured in our laboratory. The product obtained was then separated into phases with subsequent leaching of the soluble phase rich in B and Na. The resulting porous matrices have a specific surface of 35 m2/gr. Adsorption of uranyl ions onto the SiO 2 porous surface was studied to evaluate the use of this material as a filter for treatment of uranium containing water. The effects of contact time, adsorbent mass and equilibrium concentration of solution were studied. The porous adsorbent exhibits a pseudo-second-order kinetic behavior. The sponges with adsorbed uranium were thermally sealed as a way of U immobilization. Retention of uranium was confirmed during the matrix sealing by TGA. Uranium concentration before and after adsorption tests were made by means of ICP-OES. For uranium concentration of 800 ppm, 72 hours contact time and pH of 3.5, the amount of uranium adsorbed was 21.06 ± 0.02 mg U per gram of vitreous porous SiO 2 . (author)

  15. Innovative synthesis of meso-structured YSZ using V2O5 complex fluids as a template

    International Nuclear Information System (INIS)

    Guiot, Camille; Grandjean, Stephane; Batail, Patrick

    2008-01-01

    Full text of publication follows: Within the framework of generation IV nuclear reactors, the prospect of a closed fuel cycle generate a need for new advanced materials integrating the actinides jointly. Researches are conducted on fuel material precursors synthesized by soft chemistry processes, which allow a fine control of the homogeneity and ordering at a nano-scale[1]. In a view to meso-structure an inorganic matrix, recent studies[2,3] have highlighted the potential of mineral liquid crystals as templates in new soft chemistry synthesis routes. The studies presently exposed relate to an original synthesis of an inorganic-inorganic hybrid material consisting in a main zirconia matrix tem plated by ribbon-like vanadium pentoxide. After eliminating the V 2 O 5 template, the obtained solid is to be a meso-porous material with ordered pores, and becomes a prime choice material, for example to immobilize actinides. The zirconia matrix has been chosen for its ability to host actinides, which are surrogated by neodymium. It is also a preliminary material for the study of the synthesis of uranium oxide based materials, thus preventing from the drawbacks of working with radioactive materials. The vanadium pentoxide is used as a template since it structure itself as ribbon-like mineral liquid crystals that can be aligned in weak magnetic field; consequently, the final material may be structured at a nano-scale over a macroscopic range. Since the shape of vanadium oxide in solution is very sensitive to the ionic strength of the medium and the pH, the real challenge is to establish a synthesis protocol which is compatible with the presence of vanadium pentoxide, remaining in its ribbon-like liquid crystal form. References: [1] Masson, M.; Grandjean, S.; Lacquement, J.; Bourg, S.; Delauzun, J. M.; Lacombe, J.; Nuclear Engineering and Design, 236 (5-6),516 (2006). [2] Camerel, F.; Gabriel, J.-C.P.; Batail, P.; Adv. Funct. Mater., 13 (5), 377 (2003). [3] Gabriel, J

  16. A study of the isobutane dehydrogenation in a porous membrane catalytic reactor: design, use and modelling

    Energy Technology Data Exchange (ETDEWEB)

    Casanave, D

    1996-01-26

    The aim of this study was to set up and model a catalytic fixed-bed membrane reactor for the isobutane dehydrogenation. The catalyst, developed at Catalysis Research Institute (IRC), was a silicalite-supported Pt-based catalyst. Their catalytic performances (activity, selectivity, stability) where found better adapted to the membrane reactor, when compared with commercial Pt or Cr based catalysts. The kinetic study of the reaction has been performed in a differential reactor and led to the determination of a kinetic law, suitable when the catalyst is used near thermodynamic equilibrium. The mass transfer mechanisms were determined in meso-porous and microporous membranes through both permeability and gas mixtures (iC{sub 4}/H{sub 2}/N{sub 2}) separation measurements. For the meso-porous {gamma}-alumina, the mass transfer is ensured by a Knudsen diffusion mechanism which can compete with surface diffusion for condensable gas like isobutane. The resulting permselectivity H{sub 2}/iC4 of this membrane is low ({approx} 4). For the microporous zeolite membrane, molecular sieving occurs due to steric hindrance, leading to higher permselectivity {approx}14. Catalyst/membrane associations were compared in terms of isobutane dehydrogenation performances, for both types of membranes (meso-porous and microporous) and for two different reactor configurations (co-current and counter-current sweep gas flow). The best experimental results were obtained with the zeolite membrane, when sweeping the outer compartment in a co-current flow. The equilibrium displacement observed with the {gamma}-alumina membrane was lower and mainly due to a dilution effect of the reaction mixture by the sweep gas. A mathematical model was developed, which correctly describes all the experimental results obtained with the zeolite membrane, when the co-current mode is used. (Abstract Truncated)

  17. Stochastic porous media equations

    CERN Document Server

    Barbu, Viorel; Röckner, Michael

    2016-01-01

    Focusing on stochastic porous media equations, this book places an emphasis on existence theorems, asymptotic behavior and ergodic properties of the associated transition semigroup. Stochastic perturbations of the porous media equation have reviously been considered by physicists, but rigorous mathematical existence results have only recently been found. The porous media equation models a number of different physical phenomena, including the flow of an ideal gas and the diffusion of a compressible fluid through porous media, and also thermal propagation in plasma and plasma radiation. Another important application is to a model of the standard self-organized criticality process, called the "sand-pile model" or the "Bak-Tang-Wiesenfeld model". The book will be of interest to PhD students and researchers in mathematics, physics and biology.

  18. AuRu/meso-Mn2O3: A Highly Active and Stable Catalyst for Methane Combustion

    Science.gov (United States)

    Han, Z.; Fang, J. Y.; Xie, S. H.; Deng, J. G.; Liu, Y. X.; Dai, H. X.

    2018-05-01

    Three-dimensionally ordered mesoporous Mn2O3 (meso-Mn2O3) and its supported Au, Ru, and AuRu alloy (0.49 wt% Au/meso-Mn2O3, 0.48 wt% Ru/meso-Mn2O3, and 0.97 wt% AuRu/meso-Mn2O3 (Au/Ru molar ratio = 0.98)) nanocatalysts were prepared using the KIT-6-templating and polyvinyl alcohol-protected reduction methods, respectively. Physicochemical properties of the samples were characterized by means of numerous techniques, and their catalytic activities were evaluated for the combustion of methane. It is found that among all of the samples, 0.48 wt% Ru/meso-Mn 2O3 and 0.97 wt% AuRu/meso-Mn2O3 performed the best (the reaction temperature (T90% ) at 90% methane conversion was 530-540°C), but the latter showed a better thermal stability than the former. The partial deactivation of 0.97 wt% AuRu/meso-Mn2O3 due to H2O or CO2 introduction was reversible. It is concluded that the good catalytic activity and thermal stability of 0.97 wt% AuRu/meso-Mn2O3 was associated with the high dispersion of AuRu alloy NPs (2-5 nm) on the surface of meso-Mn2O3 and good low-temperature reducibility.

  19. Silica research in Glasgow

    International Nuclear Information System (INIS)

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

    2002-01-01

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

  20. Strong visible-light emission of ZnS nanocrystals embedded in sol-gel silica xerogel

    International Nuclear Information System (INIS)

    Yang Ping; Lue, M.-K.; Song, C.-F.; Zhou, G.-J.; Ai, Z.-P.; Xu Dong; Yuan, D.-R.; Cheng, X.-F.

    2003-01-01

    ZnS nanoparticles embedded in novel porous phosphor silica xerogel have been synthesized by sol-gel processing. Their fluorescence properties have been evaluated and compared with those of the Na + -doped and un-doped silica xerogels. Stable and strong visible-light emission of the doped samples has been observed. The relative fluorescence intensities of the samples doped with ZnS nanoparticles (S 2- ions have been obtained by the water solution of NaS) are the highest among all of the doped samples. Its relative fluorescence intensity is about 7.5 times of that of the un-doped silica xerogel and about 300 times of that of pure ZnS nanoparticles. The emission wavelength of the ZnS-doped and Na + -doped samples is the same as that of the un-doped silica xerogel and ZnS nanoparticles (λ em =440-450 nm). This high efficiency luminescence of the doped silica xerogels has been assigned to the luminescence centers of ZnS nanoparticles and Na + in the porous phosphorescence silica xerogel

  1. Characteristics, distribution, origin, and significance of opaline silica observed by the Spirit rover in Gusev crater, Mars

    Science.gov (United States)

    Ruff, S.W.; Farmer, J.D.; Calvin, W.M.; Herkenhoff, K. E.; Johnson, J. R.; Morris, R.V.; Rice, M.S.; Arvidson, R. E.; Bell, J.F.; Christensen, P.R.; Squyres, S. W.

    2011-01-01

    The presence of outcrops and soil (regolith) rich in opaline silica (???65-92 wt % SiO2) in association with volcanic materials adjacent to the "Home Plate" feature in Gusev crater is evidence for hydrothermal conditions. The Spirit rover has supplied a diverse set of observations that are used here to better understand the formation of silica and the activity, abundance, and fate of water in the first hydrothermal system to be explored in situ on Mars. We apply spectral, chemical, morphological, textural, and stratigraphic observations to assess whether the silica was produced by acid sulfate leaching of precursor rocks, by precipitation from silica-rich solutions, or by some combination. The apparent lack of S enrichment and the relatively low oxidation state of the Home Plate silica-rich materials appear inconsistent with the originally proposed Hawaiian analog for fumarolic acid sulfate leaching. The stratiform distribution of the silica-rich outcrops and their porous and brecciated microtextures are consistent with sinter produced by silica precipitation. There is no evidence for crystalline quartz phases among the silica occurrences, an indication of the lack of diagenetic maturation following the production of the amorphous opaline phase. Copyright ?? 2011 by the American Geophysical Union.

  2. Mesoscopic analyses of porous concrete under static compression and drop weight impact tests

    DEFF Research Database (Denmark)

    Agar Ozbek, A.S.; Pedersen, R.R.; Weerheijm, J.

    2008-01-01

    was considered as a four-phase material incorporating aggregates, bulk cement paste, interfacial transition zones and meso-size air pores. The stress-displacement relations obtained from static compression tests, the stress values, and the corresponding damage levels provided by the drop weight impact tests were......The failure process in highly porous concrete was analyzed experimentally and numerically. A triaxial visco-plastic damage model and a mesoscale representation of the material composition were considered to reproduce static compression and drop weight impact tests. In the mesoscopic model, concrete...

  3. Synthesis of nano grade hollow silica sphere via a soft template method.

    Science.gov (United States)

    Tsai, Ming-Shyong; Li, Miao Ju; Yen, Fu-Hsu

    2008-06-01

    The nano grade hollow silica sphere (HSS) was synthesized by a novel soft template method. We found that the precipitate of aluminate had a porous structure that could be the soft template for HSS. After mixing the colloidal silica with the aluminate precipitate, the bubble trapped in this porous structure could form the nano grade HSS. The aluminate precipitate was removed by adjusting the pH of the slurry to approximately 1. The outside diameter, the specific surface, and the mean pore size diameter of the forming HSS were 60-90 nm, 571 m2/g, and 3 nm, respectively. The formed HSS was collected by modifying the surface with Si(OCH3)3CHCH2 (VTMO) and then filtrating the precipitated gel in the n-butanol and ethanol solvent system.

  4. Genotoxicity of meso-2,3-dimercapto succinic acid-coated silver sulfide quantum dot

    Directory of Open Access Journals (Sweden)

    Deniz Özkan Vardar

    2015-06-01

    Full Text Available Nanotecnology products have been used in wide applications in chemistry, electronics, energy generation, and medicine. Despite significant interest in developing quantum dots (QDs for biomedical applications, many researchers are convinced that QDs will never be used for the treatment of patients because of their potential toxicity. In various in vitro cell culture studies, the cytotoxic properties of some QD have been demonstrated and they have been suggested to be toxic in humans. In this study, the cytotoxic properties of Ag2S-(Meso-2,3-Dimercapto Succinic acid nanomaterials in V79 cells (Chinese lung fibroblast cell line were determined by MTT assay. The genotoxic effects of Ag2S-(Meso-2,3-Dimercapto Succinic acid were evaluated by the alkaline single cell gel electrophoresis. The cells were treated with Ag2S-(Meso-2,3-Dimercapto Succinic acid at the concentrations of 5- 2000 µg/ml. No cytotoxic effect of Ag2S-(Meso-2,3-Dimercapto Succinic acid at all concentrations studied was observed. No significant increases in DNA damage were found at the studied concentrations when compared to negative control in V79 cells. In conclusion, further in vitro and in vivo studies are required to determine the safety doses of Ag2S-(Meso-2,3-Dimercapto Succinic acid.

  5. STUDY OF SUBCELLULAR DISTRIBUTION OF CRYSTALLINE MESO-TETRA(3-PYRIDYLBACTERIOCHLORIN NANOPARTICLES

    Directory of Open Access Journals (Sweden)

    Yu. S. Maklygina

    2016-01-01

    Full Text Available The results of the study of subcellular distribution of molecular meso-tetra(3-pyridylbacteriochlorin nanocrystals proposed as therapeutic agents for photodynamic therapy are represented in the article. Investigations and measurement of spectroscopic properties of molecular crystals of near-infrared photosensitizer were conducted using special device complex based on fiber-optic spectrometer. Investigation and analysis of the pattern of subcellular accumulation of meso-tetra(3-pyridylbacteriochlorin in molecular (dimethyl sulfoxide (DMSO as solvent and nanocrystalline forms on different cell lines: human monocytes (THP-1, human cervical cancer cells (HeLa and mouse malignant brain tumor cells (glioma C6. The dynamics of subcellylar accumulation of the agent at concentration of 5 and 10 mg/l was assessed with laser microscope-spectrum analyzer and by confocal microscopy. The study showed that in the course of interaction with cell lines molecular nanocrystals of the agent developed ability to fluorescence. Hence, in the cellular environment meso-tetra(3-pyridyl bacteriochlorin nanoparticles became phototoxic giving opportunities for their use for fluorescence diagnosis and photodynamic therapy. Specific role of meso-tetra(3-pyridylbacteriochlorin in the range of photosensitizers is determined by its spectral characteristics, i.e. absorption and fluorescence in near-infrared band, which allows measuring and affecting on deeper layers of biotissue. Thus, the use of meso-tetra(3-pyridylbacteriochlorin nanoparticles as nanophotosensitizers may improve the efficacy of diagnosis and treatment of deep-seated tumors.

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

    International Nuclear Information System (INIS)

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

    2016-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-12-01

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

  8. Super-Hydrophobic/Icephobic Coatings Based on Silica Nanoparticles Modified by Self-Assembled Monolayers

    Directory of Open Access Journals (Sweden)

    Junpeng Liu

    2016-12-01

    Full Text Available A super-hydrophobic surface has been obtained from nanocomposite materials based on silica nanoparticles and self-assembled monolayers of 1H,1H,2H,2H-perfluorooctyltriethoxysilane (POTS using spin coating and chemical vapor deposition methods. Scanning electron microscope images reveal the porous structure of the silica nanoparticles, which can trap small-scale air pockets. An average water contact angle of 163° and bouncing off of incoming water droplets suggest that a super-hydrophobic surface has been obtained based on the silica nanoparticles and POTS coating. The monitored water droplet icing test results show that icing is significantly delayed by silica-based nano-coatings compared with bare substrates and commercial icephobic products. Ice adhesion test results show that the ice adhesion strength is reduced remarkably by silica-based nano-coatings. The bouncing phenomenon of water droplets, the icing delay performance and the lower ice adhesion strength suggest that the super-hydrophobic coatings based on a combination of silica and POTS also show icephobicity. An erosion test rig based on pressurized pneumatic water impinging impact was used to evaluate the durability of the super-hydrophobic/icephobic coatings. The results show that durable coatings have been obtained, although improvement will be needed in future work aiming for applications in aerospace.

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

    Science.gov (United States)

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

    2018-04-06

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

  10. Radionuclide separations in the nuclear fuel cycle development and application of micro and meso porous inorganic ion-exchangers

    International Nuclear Information System (INIS)

    Griffith, C.S.; Luca, V.

    2006-01-01

    Full text: Full text: From the mining of uranium-containing ores to the reprocessing of spent nuclear fuel, separations technologies play a crucial role in determining the efficiency and viability of the nuclear fuel cycle. With respect to proposed Advanced Nuclear Fuel Cycles (ANFC), the integral role of separations is no different with solvent extraction and pyroelectrometalurgical processing dominating efforts to develop a sustainable and publicly acceptable roadmap for nuclear power in the next 100 years. An often forgotten or overlooked separation technology is ion-exchange, more specifically, inorganic ion-exchangers. This is despite the fact that these materials offer the potential advantages of process simplicity; exceptional selectivity against high background concentrations of competing ions; and the possibility of a simple immobilization route for the separated radionculides. ANSTO's principal interest in inorganic ion-exchange materials in recent years has been the development of an inorganic ion-exchanger for the pretreatment of acidic legacy 9 Mo production waste to simultaneously remove radiogenic cesium and strontium. Radiogenic cesium and strontium comprise the majority of activity in such waste and may offer increased ease in the downstream processing to immobilise this waste in a Synroc wasteform. With the reliance on separations technologies in all current ANFC concepts, and the recent admission of ANSTO to the European Commissions EUROPART project, the development of new inorganic ion-exchangers has also expanded within our group. This presentation will provide a background of the fundamentals of inorganic and composite inorganic-organic ion-exchange materials followed by specific discussion of some selected inorganic and composite ion-exchange materials being developed and studied at ANSTO. The detailed structural and ion-exchange chemistry of these materials will be discussed and note made of how such materials could benefit any of the current ANFC concepts. Additionally, strategies for the immobilization of the 'spent' ion-exchange materials will be highlighted

  11. Silica nanoparticles as vehicles for therapy delivery in neurological injury

    Science.gov (United States)

    Schenk, Desiree

    Acrolein, a very reactive aldehyde, is a culprit in the biochemical cascade after primary, mechanical spinal cord injury (SCI), which leads to the destruction of tissue initially unharmed, referred to as "secondary injury". Additionally, in models of multiple sclerosis (MS) and some clinical research, acrolein levels are significantly increased. This aldehyde overwhelms the natural anti-oxidant system, reacts freely with proteins, and releases during lipid peroxidation (LPO), effectively regenerating its self. Due to its ability to make more copies of itself in the presence of tissue via lipid peroxidation, researchers believe that acrolein plays a role in the increased destruction of the central nervous system in both SCI and MS. Hydralazine, an FDA-approved hypertension drug, has been shown to scavenge acrolein, but its side effects and short half life at the appropriate dose for acrolein scavenging must be improved for beneficial clinical translation. Due to the inefficient delivery of therapeutic drugs, nanoparticles have become a major field of exploration for medical applications. Based on their material properties, they can help treat disease by delivering drugs to specific tissues, enhancing detection methods, or a mixture of both. Nanoparticles made from silica provide distinct advantages. They form porous networks that can carry therapeutic molecules throughout the body. Therefore, a nanomedical approach has been designed using silica nanoparticles as a porous delivery vehicle hydralazine. The silica nanoparticles are formed in a one-step method that incorporates poly(ethylene) glycol (PEG), a stealth molecule, directly onto the nanoparticles. As an additional avenue for study, a natural product in green tea, epigallocatechin gallate (EGCG), has been explored for its ability to react with acrolein, disabling its reactive capabilities. Upon demonstration of attenuating acrolein, EGCG's delivery may also be improved using the nanomedical approach. The

  12. Colloidal silica films for high-capacity DNA arrays

    Science.gov (United States)

    Glazer, Marc Irving

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

  13. The role of curvature in silica mesoporous crystals

    KAUST Repository

    Miyasaka, Keiichi; Bennett, Alfonso Garcia; Han, Lu; Han, Yu; Xiao, Changhong; Fujita, Nobuhisa; Castle, Toen; Sakamoto, Yasuhiro; Che, Shunai; Terasaki, Osamu

    2012-01-01

    Silica mesoporous crystals (SMCs) offer a unique opportunity to study micellar mesophases. Replication of non-equilibrium mesophases into porous silica structures allows the characterization of surfactant phases under a variety of chemical and physical perturbations, through methods not typically accessible to liquid crystal chemists. A poignant example is the use of electron microscopy and crystallography, as discussed herein, for the purpose of determining the fundamental role of amphiphile curvature, namely mean curvature and Gaussian curvature, which have been extensively studied in various fields such as polymer, liquid crystal, biological membrane, etc. The present work aims to highlight some current studies devoted to the interface curvature on SMCs, in which electron microscopy and electron crystallography (EC) are used to understand the geometry of silica wall surface in bicontinuous and cage-type mesostructures through the investigation of electrostatic potential maps. Additionally, we show that by altering the synthesis conditions during the preparation of SMCs, it is possible to isolate particles during micellar mesophase transformations in the cubic bicontinuous system, allowing us to view and study epitaxial relations under the specific synthesis conditions. By studying the relationship between mesoporous structure, interface curvature and micellar mesophases using electron microscopy and EC, we hope to bring new insights into the formation mechanism of these unique materials but also contribute a new way of understanding periodic liquid crystal systems. © 2012 The Royal Society.

  14. The role of curvature in silica mesoporous crystals

    KAUST Repository

    Miyasaka, Keiichi

    2012-02-08

    Silica mesoporous crystals (SMCs) offer a unique opportunity to study micellar mesophases. Replication of non-equilibrium mesophases into porous silica structures allows the characterization of surfactant phases under a variety of chemical and physical perturbations, through methods not typically accessible to liquid crystal chemists. A poignant example is the use of electron microscopy and crystallography, as discussed herein, for the purpose of determining the fundamental role of amphiphile curvature, namely mean curvature and Gaussian curvature, which have been extensively studied in various fields such as polymer, liquid crystal, biological membrane, etc. The present work aims to highlight some current studies devoted to the interface curvature on SMCs, in which electron microscopy and electron crystallography (EC) are used to understand the geometry of silica wall surface in bicontinuous and cage-type mesostructures through the investigation of electrostatic potential maps. Additionally, we show that by altering the synthesis conditions during the preparation of SMCs, it is possible to isolate particles during micellar mesophase transformations in the cubic bicontinuous system, allowing us to view and study epitaxial relations under the specific synthesis conditions. By studying the relationship between mesoporous structure, interface curvature and micellar mesophases using electron microscopy and EC, we hope to bring new insights into the formation mechanism of these unique materials but also contribute a new way of understanding periodic liquid crystal systems. © 2012 The Royal Society.

  15. Silica Sol-Gel Entrapment of the Enzyme Chloro peroxidase

    International Nuclear Information System (INIS)

    Le, T.; Chan, S.; Ebaid, B.; Sommerhalter, M.

    2015-01-01

    The enzyme chloro peroxidase (CPO) was immobilized in silica sol-gel beads prepared from tetramethoxysilane. The average pore diameter of the silica host structure (∼3 nm) was smaller than the globular CPO diameter (∼6 nm) and the enzyme remained entrapped after sol-gel maturation. The catalytic performance of the entrapped enzyme was assessed via the pyrogallol peroxidation reaction. Sol-gel beads loaded with 4 μg CPO per mL sol solution reached 9-12% relative activity compared to free CPO in solution. Enzyme kinetic analysis revealed a decrease in K_cat but no changes in K_M or K_I . Product release or enzyme damage might thus limit catalytic performance. Yet circular dichroism and visible absorption spectra of transparent CPO sol-gel sheets did not indicate enzyme damage. Activity decline due to methanol exposure was shown to be reversible in solution. To improve catalytic performance the sol-gel protocol was modified. The incorporation of 5, 20, or 40% methyltrimethoxysilane resulted in more brittle sol-gel beads but the catalytic performance increased to 14% relative to free CPO in solution. The use of more acidic casting buffers (ph 4.5 or 5.5 instead of 6.5) resulted in a more porous silica host reaching up to 18% relative activity

  16. On micro-meso relations homogenizing electrical properties of transversely cracked laminated composites

    KAUST Repository

    Lubineau, Gilles

    2013-11-01

    A practical way to track the development of transverse cracking in a laminated composite is to monitor the change of its electrical resistance. Yet, the relations between transverse cracking and the global modification of resistivity is still unclear that makes difficult to interpret these non-destructive-testing results. Here, we introduce the homogenization process that defines at the meso scale an equivalent homogeneous ply that is energetically equivalent to the cracked one. It is shown that this equivalent ply mainly depends on the cracking level while it can be considered independent on the rest of the laminated structure. The direct consequence is that the meso scale is a pertinent one to perform the homogenization. Then, non-destructive electrical measurements can be considered as a reliable technique to access meso scale damage indicators. © 2013 Elsevier Ltd.

  17. Meso-Helical Ag(I) Coordination Polymer Based on a Pyridylimidazole Ligand

    International Nuclear Information System (INIS)

    Kang, Youngjin; Kim, Jinho; Lee, Eunji; Park, Ki-Min; Moon, Suk-Hee

    2016-01-01

    In the fields of material science and metallosupramolecular chemistry, coordination polymers with various helical types have been extensively explored because of their charming structures, and their potential applications in material chemistry. Among them, meso-helical coordination polymers consisting of achiral 1D strands, which are generally constructed by a crystallographic inversion symmetry, are relatively rare. The coordination polymer 1 exhibits a rare one-dimensional meso-helical chain topology constructed by its internal inversion symmetry. The skeleton of this meso-helical chain is preserved up to 300°C. The complexation of silver(I) ion to the free pyim ligand give rise to the enhanced photoluminescence intensity and slightly blue-shifted emission maximum, originated from intraligand (IL) π[BOND]π* transition and rigidochromic effect. Further exploration of complexation of this ligand with other transition metal ions is currently in progress

  18. Spatio-temporal distributions of meso convective systems in NE China and its vicinity

    Science.gov (United States)

    Yuan, Meiying; Li, Zechun; Zhang, Xiaoling; Li, Xun

    2008-08-01

    Based on the IR cloud imagery from the Chinese FY-2C satellite for June ~ August, 2005 - 2007, statistics is undertaken of meso convective systems (MCS) over NE China and its neighborhood, obtaining the space - time distributions of MCS. MCS include elliptical type( MCC's) , persistent elongated type (PECS's), in shape. Dividing the total MCS into MαMCS, MβMCS and MCC (PECS) . Results show that the number of meso-α MCS (dominantly PECS's) is considerably more than that of meso-β MCS (largely MCCss), which are observed mainly in the NE China plain and Daxing'an Mountains, especially in the entrance to the plain as well as its central ~ northern portion; the MCS occur mainly in June ~ August, particularly in June; the extratropical MCS show two peak phases, one being in 1500-2200 BST the other being 0000-0700 BST as the secondary peaking interval.

  19. Meso-decorated self-healing gels: network structure and properties

    Science.gov (United States)

    Gong, Jin; Sawamura, Kensuke; Igarashi, Susumu; Furukawa, Hidemitsu

    2013-04-01

    Gels are a new material having three-dimensional network structures of macromolecules. They possess excellent properties as swellability, high permeability and biocompatibility, and have been applied in various fields of daily life, food, medicine, architecture, and chemistry. In this study, we tried to prepare new multi-functional and high-strength gels by using Meso-Decoration (Meso-Deco), one new method of structure design at intermediate mesoscale. High-performance rigid-rod aromatic polymorphic crystals, and the functional groups of thermoreversible Diels-Alder reaction were introduced into soft gels as crosslinkable pendent chains. The functionalization and strengthening of gels can be realized by meso-decorating the gels' structure using high-performance polymorphic crystals and thermoreversible pendent chains. New gels with good mechanical properties, novel optical properties and thermal properties are expected to be developed.

  20. Controlled release of ibuprofen by meso–macroporous silica

    Energy Technology Data Exchange (ETDEWEB)

    Santamaría, E., E-mail: esthersantamaria@ub.edu; Maestro, A.; Porras, M.; Gutiérrez, J.M.; González, C.

    2014-02-15

    Structured meso–macroporous silica was successfully synthesized from an O/W emulsion using decane as a dispersed phase. Sodium silicate solution, which acts as a silica source and a poly(ethylene oxide)–poly(propylene oxide)–poly(ethylene oxide) (EO{sub 19}PO{sub 39}EO{sub 19}) denoted as P84 was used in order to stabilize the emulsion and as a mesopore template. The materials obtained were characterized through transmission electron microscopy (TEM), scanning electron microscopy (SEM), small-angle X-ray diffraction scattering (SAXS) and nitrogen adsorption–desorption isotherms. Ibuprofen (IBU) was selected as the model drug and loaded into ordered meso–macroporous materials. The effect of the materials’ properties on IBU drug loading and release was studied. The results showed that the loading of IBU increases as the macropore presence in the material is increased. The IBU adsorption process followed the Langmuir adsorption isotherm. A two-step release process, consisting of an initial fast release and then a slower release was observed. Macropores enhanced the adsorption capacity of the material; this was probably due to the fact that they allowed the drug to access internal pores. When only mesopores were present, ibuprofen was probably adsorbed on the mesopores close to the surface. Moreover, the more macropore present in the material, the slower the release behaviour observed, as the ibuprofen adsorbed in the internal pores had to diffuse along the macropore channels up to the surface of the material. The material obtained from a highly concentrated emulsion was functionalized with amino groups using two methods, the post-grafting mechanism and the co-condensation mechanism. Both routes improve IBU adsorption in the material and show good behaviour as a controlled drug delivery system. - Graphical abstract: Ibuprofen release profiles for the materials obtained from samples P84{sub m}eso (black diamonds), P84{sub 2}0% (white squares), P84{sub 5

  1. 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.

  2. Storage and sustained release of volatile substances from a hollow silica matrix

    Energy Technology Data Exchange (ETDEWEB)

    Wang Jiexin [Key Lab for Nanomaterials, Ministry of Education, Beijing 100029 (China); Ding Haomin [Research Center of the Ministry of Education for High Gravity Engineering and Technology, Beijing University of Chemical Technology, Beijing 100029 (China); Tao Xia [Key Lab for Nanomaterials, Ministry of Education, Beijing 100029 (China); Chen Jianfeng [Key Lab for Nanomaterials, Ministry of Education, Beijing 100029 (China)

    2007-06-20

    Porous hollow silica nanospheres (PHSNSs) prepared by adopting a nanosized CaCO{sub 3} template were utilized for the first time as a novel carrier for the storage and sustained release of volatile substances. Two types of volatile substances, Indian pipal from perfumes and peroxyacetic acid from disinfectants, were selected and then tested by one simple adsorption process with two separate comparative carriers, i.e. activated carbon and solid porous silica. It was demonstrated that a high storage capacity (9.6 ml{sub perfume}/mg{sub carrier}) of perfume could be achieved in a PHSNS matrix, which was almost 14 times as much as that of activated carbon. The perfume release profiles showed that PHSNSs exhibited sustained multi-stage release behaviour, while the constant release of activated carbon at a low level was discerned. Further, a Higuchi model study proved that the release process of perfume in both carriers followed a Fickian diffusion mechanism. For peroxyacetic acid as a disinfectant model, PHSNSs also displayed a much better delayed-delivery process than a solid porous silica system owing to the existence of unique hollow frameworks. Therefore, the aforementioned excellent sustained-release behaviours would make PHSNSs a promising carrier for storage and sustained delivery applications of volatile substances.

  3. [Distribution pattern of meso-micro soil fauna in Eucalyptus grandis plantation].

    Science.gov (United States)

    Huang, Yumei; Zhang, Jian; Yang, Wanqin

    2006-12-01

    In this paper, meso-micro soil fauna were extracted and collected by Baermann's and Tullgren' s method, and their distribution pattern in the Eucalyptus grandis plantation of Hongya County, Sichuan Province was studied. A total of 13 550 specimens were collected, belonging to 6 phyla, 13 classes, and 26 orders. Acarina, Nematoda, Collembola were the dominant groups, and Enchytraeidae was the frequent one. The group and individual numbers of meso-micro soil fauna varied with seasons, being the maximum in autumn or winter, fewer in summer, and the minimum in spring. The density of meso-micro soil fauna in soil profile decreased rapidly with increasing soil depth, but a converse distribution was observed from time to time in 5 - 10 cm and 10 - 15 cm soil layers. The meso-micro soil fauna collected by Baermann's and Tullgren's method had a density of 3. 333 x 10(3) - 2. 533 x 10(5) ind x m(-2) and 1.670 x 10(2) - 2.393 x 10(5) ind x m(-2), respectively, and the decreasing rate of the density with the increase of soil depth was higher for those collected by Tullgren's method. The density-group index of meso-micro soil fauna in the E. grandis plantation was the lowest in spring, but the highest in autumn or summer. There were no significant differences in the density of meso-micro soil fauna and in the density-group index between E. grandis plantation and Quercus acutissima secondary forest.

  4. STUDY ON SILICA INFUSED RECYCLED AGGREGATE CONCRETE USING DESIGN OF EXPERIMENTS

    Directory of Open Access Journals (Sweden)

    P. M. MRUDUL

    2017-04-01

    Full Text Available Recycled Aggregate (RA generated from the construction industry is used as a material for sustainable construction. The old mortar attached to these aggregates makes it porous and are generally used for low-grade applications. However, by infusing with silica fumes, the properties of recycled aggregate concrete (RAC can be improved, as the silica fumes get infused into the pores of old mortar attached to it. In this study, the optimum percentage of recycled aggregate that can be used in fresh concrete for higher grade applications was found out. Design of experiments (DoE was used to optimize percentage of silica fumes and recycled aggregate to achieve optimum properties of concrete. Equations to predict the properties of concrete were also modelled using regression analysis.

  5. Methane Hydrate Formation and Dissociation in the Presence of Silica Sand and Bentonite Clay

    Directory of Open Access Journals (Sweden)

    Kumar Saw V.

    2015-11-01

    Full Text Available The formation and dissociation of methane hydrates in a porous media containing silica sand of different sizes and bentonite clay were studied in the presence of synthetic seawater with 3.55 wt% salinity. The phase equilibrium of methane hydrate under different experimental conditions was investigated. The effects of the particle size of silica sand as well as a mixture of bentonite clay and silica sand on methane hydrate formation and its dissociation were studied. The kinetics of hydrate formation was studied under different subcooling conditions to observe its effects on the induction time of hydrate formation. The amount of methane gas encapsulated in hydrate was computed using a real gas equation. The Clausius-Clapeyron equation is used to estimate the enthalpy of hydrate dissociation with measured phase equilibrium data.

  6. An interview with James Wilbur, Ph.D. General Manager, Life Sciences, Meso Scale Discovery.

    Science.gov (United States)

    Wilbur, James

    2004-06-01

    James L. Wilbur, Ph.D. received a Bachelor's degree from the University of California, San Diego and a Ph.D. in Chemistry from Stanford University. After completing an NIH Postdoctoral Fellowship with Professor George M. Whitesides in the Department of Chemistry at Harvard University, he joined IGEN International, Inc., where he held a variety of positions in Research and Development. During that time, he was part of the team that developed the core technology and products for Meso Scale Discovery. He assumed his current position in 2001 when Meso Scale Discovery launched the products discussed here.

  7. A three-dimensional meso-scale modeling for helium bubble growth in metals

    International Nuclear Information System (INIS)

    Suzudo, T.; Kaburaki, H.; Wakai, E.

    2007-01-01

    A three-dimensional meso-scale computer model using a Monte-Carlo simulation method has been proposed to simulate the helium bubble growth in metals. The primary merit of this model is that it enables the visual comparison between the microstructure observed by the TEM imaging and those by calculations. The modeling is so simple that one can control easily the calculation by tuning parameters. The simulation results are confirmed by the ideal gas law and the capillary relation. helium bubble growth, meso-scale modeling, Monte-Carlo simulation, the ideal gas law and the capillary relation. (authors)

  8. Comparative efficiency of racemic- and meso-2,3-dimercaptosuccinic acid to mobilize mercury in rats

    International Nuclear Information System (INIS)

    Prester, Lj.; Restek Samarzija, N.; Blanusa, M.; Piasek, M.; Kostial, K.; Jones, M.M.; Singh, P.K.

    1996-01-01

    Two stereoisomeric forms of chelating agent 2,3-dimercaptosuccinic acid (DMSA), meso- and racemic (rac-) DMSA, were compared for mercury mobilization in rats (Experiment 1). Acute oral toxicity of both chelators (LD 50 ) was also tested (Experiment 2). Experiments were carried out on 6-7 weeks old albino Wistar female rats. In Experiment 1 three groups of 9-10 animals were given intraperitoneally 0.5 mg HgCl 2 /kg b.w. and 2.5 mCi (92.5 kBq) of radioactive mercury in the form of 203 Hg(NO 3 ) 2 .Five days after mercury, therapy with 1.0 mmol/kg/day of either meso- or rac-DMSA was started and continued for four days. Whole body radioactivity was measured during the four-day therapy, i.e. 24 hours after each chelator application. In Experiment 2, chelators were given by gastric tube. They were dissolved in 8% NaHCOP 3 with addition of NaOH in equivalent quantities to obtain soluble sodium salts. Meso-DMSA was given at doses of 6, 8 or 12 mmol/kg and rac-DMSA at doses of 12 or 18.7 mmol/kg (3 rats at each dose level). Rat mortality was recorded during 8 days. Results of Experiment 1 showed that the efficiency of rac-DMSA in reducing body retention of mercury-203 was significantly higher than of meso-DMSA. At the end of experiment, reduction of mercury -203 whole body retention was 62% of control in meso-DMSA compared to 29% of control in rac D MSA group. In Experiment 2, the approximate oral LD 50 value were estimated to be >18.7 mmol/kg for meso-DMSA and between 8 and 12 mmol/kg for rac-DMSA. In conclusion, rac-DMSA reduces more efficiently mercury body load than its meso-form. However, more studies are needed to evaluate advantage of rac-DMSA application in spite of its higher toxicity compared to meso-DMSA. (author)

  9. Structure and dynamics of spin-labeled insulin entrapped in a silica matrix by the sol-gel method.

    Science.gov (United States)

    Vanea, E; Gruian, C; Rickert, C; Steinhoff, H-J; Simon, V

    2013-08-12

    The structure and conformational dynamics of insulin entrapped into a silica matrix was monitored during the sol to maturated-gel transition by electron paramagnetic resonance (EPR) spectroscopy. Insulin was successfully spin-labeled with iodoacetamide and the bifunctional nitroxide reagent HO-1944. Room temperature continuous wave (cw) EPR spectra of insulin were recorded to assess the mobility of the attached spin labels. Insulin conformation and its distribution within the silica matrix were studied using double electron-electron resonance (DEER) and low-temperature cw-EPR. A porous oxide matrix seems to form around insulin molecules with pore diameters in the order of a few nanometers. Secondary structure of the encapsulated insulin investigated by Fourier transform infrared spectroscopy proved a high structural integrity of insulin even in the dried silica matrix. The results show that silica encapsulation can be used as a powerful tool to effectively isolate and functionally preserve biomolecules during preparation, storage, and release.

  10. Synthesis and crystallographic analysis of meso-2,3-difluoro-1,4-butanediol and meso-1,4-dibenzyloxy-2,3-difluorobutane

    Directory of Open Access Journals (Sweden)

    Bruno Linclau

    2010-06-01

    Full Text Available A large-scale synthesis of meso-2,3-difluoro-1,4-butanediol in 5 steps from (Z-but-2-enediol is described. Crystallographic analysis of the diol and the corresponding benzyl ether reveals an anti conformation of the vicinal difluoride moiety. Monosilylation of the diol is high-yielding but all attempts to achieve chain extension through addition of alkyl Grignard and acetylide nucleophiles failed.

  11. Hyperpolarized Porous Silicon Nanoparticles: Potential Theragnostic Material for ²⁹Si Magnetic Resonance Imaging.

    Science.gov (United States)

    Seo, Hyeonglim; Choi, Ikjang; Whiting, Nicholas; Hu, Jingzhe; Luu, Quy Son; Pudakalakatti, Shivanand; McCowan, Caitlin; Kim, Yaewon; Zacharias, Niki; Lee, Seunghyun; Bhattacharya, Pratip; Lee, Youngbok

    2018-05-20

    Porous silicon nanoparticles have recently garnered attention as potentially-promising biomedical platforms for drug delivery and medical diagnostics. Here, we demonstrate porous silicon nanoparticles as contrast agents for ²⁹Si magnetic resonance imaging. Size-controlled porous silicon nanoparticles were synthesized by magnesiothermic reduction of silica nanoparticles and were surface activated for further functionalization. Particles were hyperpolarized via dynamic nuclear polarization to enhance their ²⁹Si MR signals; the particles demonstrated long ²⁹Si spin-lattice relaxation (T₁) times (~ 25 mins), which suggests potential applicability for medical imaging. Furthermore, ²⁹Si hyperpolarization levels were sufficient to allow ²⁹Si MRI in phantoms. These results underscore the potential of porous silicon nanoparticles that, when combined with hyperpolarized magnetic resonance imaging, can be a powerful theragnostic deep tissue imaging platform to interrogate various biomolecular processes in vivo. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Nanoporous Silica Templated HeteroEpitaxy: Final LDRD Report.

    Energy Technology Data Exchange (ETDEWEB)

    Burckel, David Bruce; Koleske, Daniel; Rowen, Adam M.; Williams, John Dalton; Fan, Hongyou; Arrington, Christian Lew

    2006-11-01

    This one-year out-of-the-box LDRD was focused on exploring the use of porous growth masks as a method for defect reduction during heteroepitaxial crystal growth. Initially our goal was to investigate porous silica as a growth mask, however, we expanded the scope of the research to include several other porous growth masks on various size scales, including mesoporous carbon, and the UV curable epoxy, SU-8. Use of SU-8 as a growth mask represents a new direction, unique in the extensive literature of patterned epitaxial growth, and presents the possibility of providing a single step growth mask. Additional research included investigation of pore viability via electrochemical deposition into high aspect ratio photoresist patterns and pilot work on using SU-8 as a DUV negative resist, another significant potential result. While the late start nature of this project pushed some of the initial research goals out of the time table, significant progress was made. 3 Acknowledgements This work was performed in part at the Nanoscience @ UNM facility, a member of the National Nanotechnology Infrastructure Network, which is supported by the National Science Foundation (Grant ECS 03-35765). Sandia is multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United Stated Department of Energy's National Nuclear Security Administration under Contract DE-AC04-94AL85000. This work was supported under the Sandia LDRD program (Project 99405). 4

  13. Silica research in Glasgow

    CERN Document Server

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

    2002-01-01

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

  14. Meso-ester and carboxylic acid substituted BODIPYs with far-red and near-infrared emission for bioimaging applications

    KAUST Repository

    Ni, Yong; Zeng, Lintao; Kang, Namyoung; Huang, Kuo-Wei; Wang, Liang; Zeng, Zebing; Chang, Young-Tae; Wu, Jishan

    2014-01-01

    -6) become partially soluble in water, and their absorptions and emissions are located in the far-red or near-infrared region. Three synthetic approaches are attempted to access the meso-carboxylic acid (COOH)-substituted BODIPYs 7 and 8 from the meso

  15. Meso-ester and carboxylic acid substituted BODIPYs with far-red and near-infrared emission for bioimaging applications

    KAUST Repository

    Ni, Yong

    2014-01-21

    A series of meso-ester-substituted BODIPY derivatives 1-6 are synthesized and characterized. In particular, dyes functionalized with oligo(ethylene glycol) ether styryl or naphthalene vinylene groups at the α positions of the BODIPY core (3-6) become partially soluble in water, and their absorptions and emissions are located in the far-red or near-infrared region. Three synthetic approaches are attempted to access the meso-carboxylic acid (COOH)-substituted BODIPYs 7 and 8 from the meso-ester-substituted BODIPYs. Two feasible synthetic routes are developed successfully, including one short route with only three steps. The meso-COOH-substituted BODIPY 7 is completely soluble in pure water, and its fluorescence maximum reaches around 650 nm with a fluorescence quantum yield of up to 15 %. Time-dependent density functional theory calculations are conducted to understand the structure-optical properties relationship, and it is revealed that the Stokes shift is dependent mainly on the geometric change from the ground state to the first excited singlet state. Furthermore, cell staining tests demonstrate that the meso-ester-substituted BODIPYs (1 and 3-6) and one of the meso-COOH-substituted BODIPYs (8) are very membrane-permeable. These features make these meso-ester- and meso-COOH-substituted BODIPY dyes attractive for bioimaging and biolabeling applications in living cells. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. A Review of the Appropriateness of Existing Micro- and Meso-level Models of Athlete Development within Equestrian Sport

    NARCIS (Netherlands)

    de Haan, D.M.

    2017-01-01

    The aim of this paper was to use a case study approach to review the appropriateness of existing micro- and meso-level models of athlete development within the sport specific context of equestrianism. At a micro-level the Long Term Athlete Development (LTAD) model was chosen. At a meso-level, the

  17. Foams in porous media

    Energy Technology Data Exchange (ETDEWEB)

    Marsden, S.S.

    1986-07-01

    In 1978 a literature search on selective blocking of fluid flow in porous media was done by Professor S.S. Marsden and two of his graduate students, Tom Elson and Kern Huppy. This was presented as SUPRI Report No. TR-3 entitled ''Literature Preview of the Selected Blockage of Fluids in Thermal Recovery Projects.'' Since then a lot of research on foam in porous media has been done on the SUPRI project and a great deal of new information has appeared in the literature. Therefore we believed that a new, up-to-date search should be done on foam alone, one which would be helpful to our students and perhaps of interest to others. This is a chronological survey showing the development of foam flow, blockage and use in porous media, starting with laboratory studies and eventually getting into field tests and demonstrations. It is arbitrarily divided into five-year time periods. 81 refs.

  18. Porous material neutron detector

    Science.gov (United States)

    Diawara, Yacouba [Oak Ridge, TN; Kocsis, Menyhert [Venon, FR

    2012-04-10

    A neutron detector employs a porous material layer including pores between nanoparticles. The composition of the nanoparticles is selected to cause emission of electrons upon detection of a neutron. The nanoparticles have a maximum dimension that is in the range from 0.1 micron to 1 millimeter, and can be sintered with pores thereamongst. A passing radiation generates electrons at one or more nanoparticles, some of which are scattered into a pore and directed toward a direction opposite to the applied electrical field. These electrons travel through the pore and collide with additional nanoparticles, which generate more electrons. The electrons are amplified in a cascade reaction that occurs along the pores behind the initial detection point. An electron amplification device may be placed behind the porous material layer to further amplify the electrons exiting the porous material layer.

  19. Porous Silicon Nanowires

    Science.gov (United States)

    Qu, Yongquan; Zhou, Hailong; Duan, Xiangfeng

    2011-01-01

    In this minreview, we summarize recent progress in the synthesis, properties and applications of a new type of one-dimensional nanostructures — single crystalline porous silicon nanowires. The growth of porous silicon nanowires starting from both p- and n-type Si wafers with a variety of dopant concentrations can be achieved through either one-step or two-step reactions. The mechanistic studies indicate the dopant concentration of Si wafers, oxidizer concentration, etching time and temperature can affect the morphology of the as-etched silicon nanowires. The porous silicon nanowires are both optically and electronically active and have been explored for potential applications in diverse areas including photocatalysis, lithium ion battery, gas sensor and drug delivery. PMID:21869999

  20. A Holistic Approach with Special Reference to Heat Transfer in Multi-Component Porous Media Systems

    Directory of Open Access Journals (Sweden)

    A. K. Borah

    2010-06-01

    Full Text Available Problems involving multiphase flow, heat transfer and multi-component mass transport in porous media arise in a number of scientific engineering disciplines. Important technological applications include thermally enhanced oil recovery, subsurface contamination and remediation, capillary assisted thermal technologies, drying process, thermal insulation materials, multiphase trickle bed reactors, nuclear reactor safety analysis, high level radioactive waste repositories and geothermal energy exploitation. In this paper we demonstrate multiphase flows in porous media are driven by gravitational, capillary and viscous forces. But gravity causes phase migration in the direction of the gravitational field. Microscopic modelling efforts were made to accurately incorporate microscopic interfacial phenomena. Multi-scale modelling approaches were attempted in order to transmit information over various lengths scales, ranging from micro-scale, meso-scale, macro-scale and finally to the field scale.

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

    Science.gov (United States)

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

    2017-12-13

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

  2. Porous silicon gettering

    Energy Technology Data Exchange (ETDEWEB)

    Tsuo, Y.S.; Menna, P.; Pitts, J.R. [National Renewable Energy Lab., Golden, CO (United States)] [and others

    1996-05-01

    The authors have studied a novel extrinsic gettering method that uses the large surface areas produced by a porous-silicon etch as gettering sites. The annealing step of the gettering used a high-flux solar furnace. They found that a high density of photons during annealing enhanced the impurity diffusion to the gettering sites. The authors used metallurgical-grade Si (MG-Si) prepared by directional solidification casing as the starting material. They propose to use porous-silicon-gettered MG-Si as a low-cost epitaxial substrate for polycrystalline silicon thin-film growth.

  3. Porous metal for orthopedics implants

    OpenAIRE

    Matassi, Fabrizio; Botti, Alessandra; Sirleo, Luigi; Carulli, Christian; Innocenti, Massimo

    2013-01-01

    Porous metal has been introduced to obtain biological fixation and improve longevity of orthopedic implants. The new generation of porous metal has intriguing characteristics that allows bone healing and high osteointegration of the metallic implants. This article gives an overview about biomaterials properties of the contemporary class of highly porous metals and about the clinical use in orthopaedic surgery.

  4. Preparation of reduced graphene oxide/meso-TiO_2/AuNPs ternary composites and their visible-light-induced photocatalytic degradation n of methylene blue

    International Nuclear Information System (INIS)

    Yang, Yongfang; Ma, Zheng; Xu, Lidong; Wang, Hefang; Fu, Nian

    2016-01-01

    Graphical abstract: Reduced graphene oxide/meso-TiO_2/AuNPs (RGO/meso-TiO_2/AuNPs) ternary composites were prepared via the addition of graphene oxide to the dispersion of meso-TiO_2/AuNPs under a hydrothermal condition. The RGO/meso-TiO_2/AuNPs ternary composites show high photocatalytic activity toward MB. - Highlights: • RGO/meso-TiO_2/AuNPs were obtained by addition of graphene oxide to meso-TiO_2/AuNPs. • Au NPs in the mesopores of meso-TiO_2 reduce the recombination of charge carriers. • RGO covered with the surface of the meso-TiO_2 enhance the adsorption of MB. • RGO/meso-TiO_2/AuNPs composites show high photocatalytic performance toward MB. - Abstract: Reduced graphene oxide/meso-TiO_2/AuNPs (RGO/meso-TiO_2/AuNPs) ternary composites were prepared via the addition of graphene oxide to the dispersion of meso-TiO_2/AuNPs under hydrothermal conditions. The structure and the morphology of the RGO/meso-TiO_2/AuNPs materials were characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The photocatalytic activity of RGO/meso-TiO_2/AuNPs was evaluated by degradation of methyl blue (MB) under visible-light illumination. The ternary composites present an extended light absorption range, efficient charge separation properties, high adsorption ability for MB and high photocatalytic degradation activity of MB compared to the meso-TiO_2 and meso-TiO_2/AuNPs.

  5. Preparation of reduced graphene oxide/meso-TiO{sub 2}/AuNPs ternary composites and their visible-light-induced photocatalytic degradation n of methylene blue

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Yongfang; Ma, Zheng; Xu, Lidong [School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin 300130 (China); Wang, Hefang, E-mail: whf0618@163.com [School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin 300130 (China); Fu, Nian, E-mail: funian3678@163.com [School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin 300130 (China); College of Physics Science and Technology of Hebei University, Baoding 071002 (China)

    2016-04-30

    Graphical abstract: Reduced graphene oxide/meso-TiO{sub 2}/AuNPs (RGO/meso-TiO{sub 2}/AuNPs) ternary composites were prepared via the addition of graphene oxide to the dispersion of meso-TiO{sub 2}/AuNPs under a hydrothermal condition. The RGO/meso-TiO{sub 2}/AuNPs ternary composites show high photocatalytic activity toward MB. - Highlights: • RGO/meso-TiO{sub 2}/AuNPs were obtained by addition of graphene oxide to meso-TiO{sub 2}/AuNPs. • Au NPs in the mesopores of meso-TiO{sub 2} reduce the recombination of charge carriers. • RGO covered with the surface of the meso-TiO{sub 2} enhance the adsorption of MB. • RGO/meso-TiO{sub 2}/AuNPs composites show high photocatalytic performance toward MB. - Abstract: Reduced graphene oxide/meso-TiO{sub 2}/AuNPs (RGO/meso-TiO{sub 2}/AuNPs) ternary composites were prepared via the addition of graphene oxide to the dispersion of meso-TiO{sub 2}/AuNPs under hydrothermal conditions. The structure and the morphology of the RGO/meso-TiO{sub 2}/AuNPs materials were characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The photocatalytic activity of RGO/meso-TiO{sub 2}/AuNPs was evaluated by degradation of methyl blue (MB) under visible-light illumination. The ternary composites present an extended light absorption range, efficient charge separation properties, high adsorption ability for MB and high photocatalytic degradation activity of MB compared to the meso-TiO{sub 2} and meso-TiO{sub 2}/AuNPs.

  6. Preparation and surface properties of mesoporous silica particles modified with poly(N-vinyl-2-pyrrolidone) as a potential adsorbent for bilirubin removal

    Energy Technology Data Exchange (ETDEWEB)

    Timin, Alexander, E-mail: a_timin@mail.ru [Inorganic Chemistry Department, Ivanovo State University of Chemistry and Technology (ISUCT), 7, Sheremetevsky prosp., 153000 Ivanovo (Russian Federation); Rumyantsev, Evgeniy, E-mail: evr@isuct.ru [Inorganic Chemistry Department, Ivanovo State University of Chemistry and Technology (ISUCT), 7, Sheremetevsky prosp., 153000 Ivanovo (Russian Federation); Lanin, Sergey N., E-mail: SNLanin@phys.chem.msu.ru [Chemistry Department, Physical Chemistry Division, Lomonosov Moscow State University, 1-3 Leninskie Gory, 119991 Moscow (Russian Federation); Rychkova, Sveta A. [Chemistry Department, Physical Chemistry Division, Lomonosov Moscow State University, 1-3 Leninskie Gory, 119991 Moscow (Russian Federation); Guseynov, Sabir S. [Krestov Institute of Solution Chemistry of Russian Academy of Sciences, 153000 Ivanovo (Russian Federation); Solomonov, Alexey V. [Inorganic Chemistry Department, Ivanovo State University of Chemistry and Technology (ISUCT), 7, Sheremetevsky prosp., 153000 Ivanovo (Russian Federation); Antina, Elena V. [Krestov Institute of Solution Chemistry of Russian Academy of Sciences, 153000 Ivanovo (Russian Federation)

    2014-10-15

    The surface of silica particles was modified with polyvinyl pyrrolidone (PVP) through sol–gel process. The different experimental techniques, i.e., thermogravimetric analysis (TGA and DTG), nitrogen adsorption, scanning electron microscopy (SEM), laser diffraction analysis (LDA), fourier transform spectroscopy (FTIR) are used to characterize the pure non-functionalized and functionalized silicas containing different amount of PVP. It was shown that PVP-modified silica samples have well developed porous structure; the values of specific surface area for PVP-modified silicas are in the range of 140–264 m{sup 2} g{sup −1}. While the non-functionalized silica shows the low surface area (S{sub BET} = 40 m{sup 2} g{sup −1}). The BJH analysis showed that PVP can be used as an effective agent to increase an average pore size and total pore volume. The results indicate that PVP functionalized silicas show a potential as effective adsorbents for bilirubin removal compared to other available adsorbents. - Highlights: • PVP functionalized silicas were synthesized via sol–gel method. • Modification of silica by PVP leads to the formation of mesoporous structure. • PVP functionalized mesoporous silicas demonstrate good adsorption properties for bilirubin removal.

  7. Power Generation from Concentration Gradient by Reverse Electrodialysis in Dense Silica Membranes for Microfluidic and Nanofluidic Systems

    Directory of Open Access Journals (Sweden)

    Sang Woo Lee

    2016-01-01

    Full Text Available In this study, we investigate power generation by reverse electrodialysis in a dense silica membrane that is between two NaCl solutions with various combinations of concentrations. Each silica membrane is fabricated by depositing a silica layer on a porous alumina substrate via chemical vapor deposition. The measured potential-current (V-I characteristics of the silica membrane are used to obtain the transference number, diffusion potential, and electrical resistance. We develop empirical correlations for the transference number and the area-specific resistance, and present the results of power generation by reverse electrodialysis using the fabricated silica membranes. The highest measured power density is 0.98 mW/m2. In addition, we develop a contour map of the power density as a function of NaCl concentrations on the basis of the empirical correlations. The contour map shows that a power output density of 1.2 mW/m2 is achievable with the use of silica membranes and is sufficient to drive nanofluidic and microfluidic systems. The dense silica membrane has the potential for use in micro power generators in nanofluidic and microfluidic systems.

  8. The plastic rotation effect in an isotropic gradient plasticity model for applications at the meso scale

    NARCIS (Netherlands)

    Poh, Leong Hien; Peerlings, R.H.J.

    2016-01-01

    Although formulated to represent a large system of polycrystals at the macroscopic level, isotropic gradient plasticity models have routinely been adopted at the meso scale. For such purposes, it is crucial to incorporate the plastic rotation effect in order to obtain a reasonable approximation of

  9. Preparation of gluten-free bread using a meso-structured whey protein particle system

    NARCIS (Netherlands)

    Riemsdijk, van L.E.; Goot, van der A.J.; Hamer, R.J.; Boom, R.M.

    2011-01-01

    This article presents a novel method for making gluten-free bread using mesoscopically structured whey protein. The use of the meso-structured protein is based on the hypothesis that the gluten structure present in a developed wheat dough features a particle structure on a mesoscopic length scale

  10. Symmetry-breaking intramolecular charge transfer in the excited state of meso-linked BODIPY dyads

    KAUST Repository

    Whited, Matthew T.; Patel, Niral M.; Roberts, Sean T.; Allen, Kathryn; Djurovich, Peter I.; Bradforth, Stephen E.; Thompson, Mark E.

    2012-01-01

    We report the synthesis and characterization of symmetric BODIPY dyads where the chromophores are attached at the meso position, using either a phenylene bridge or direct linkage. Both molecules undergo symmetry-breaking intramolecular charge transfer in the excited state, and the directly linked dyad serves as a visible-light-absorbing analogue of 9,9′-bianthryl.

  11. Quantitative study on crack of meso-damage and fracture concrete ...

    Indian Academy of Sciences (India)

    1School of Civil Engineering, Chang'an University, Xi'an 710061, China. 2Institute of Geotechnical ... lysis of the meso-fracture process of concrete materials is performed. The results demonstrate that the ... realize the quantitative analysis of micro cracks of concrete material (Ammouche et al 2000). The whole CT images of ...

  12. Shoreline resilience to individual storms and storm clusters on a meso-macrotidal barred beach

    NARCIS (Netherlands)

    Angnuureng, Donatus Bapentire; Almar, Rafael; Senechal, Nadia; Castelle, Bruno; Addo, Kwasi Appeaning; Marieu, Vincent; Ranasinghe, Roshanka

    2017-01-01

    This study investigates the impact of individual storms and storm clusters on shoreline recovery for the meso-to macrotidal, barred Biscarrosse beach in SW France, using 6 years of daily video observations. While the study area experienced 60 storms during the 6-year study period, only 36 storms

  13. Meso-meteorological effect of thermal releases from nuclear power plants in the GW range

    International Nuclear Information System (INIS)

    Bahloul, C.; Le Berre, P.

    1975-01-01

    A comparison is made between the energy released by nuclear power plants into the environment and the energy brought into action by meso-meteorological phenomena. Observations on the occasion of important heat release (forest fires) are made and compared with the thermal effluents generated by nuclear power plants [fr

  14. Pumping Iron and Silica Bodybuilding

    Science.gov (United States)

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

    2016-02-01

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

  15. Electrokinetics in porous media

    NARCIS (Netherlands)

    Luong, D.T.

    2014-01-01

    This thesis presents the PhD research on electrokinetics in porous media. Electrokinetic phenomena are induced by the relative motion between a fluid and a solid surface and are directly related to the existence of an electric double layer between the fluid and the solid grain surface.

  16. A novel and facile synthesis approach for a porous carbon/graphene composite for high-performance supercapacitors.

    Science.gov (United States)

    Liu, Ting; Zhang, Xuesha; Liu, Kang; Liu, Yanyan; Liu, Mengjie; Wu, Wenyu; Gu, Yu; Zhang, Ruijun

    2018-03-02

    We propose a novel and facile synthesis approach to a porous carbon/graphene composite. Graphene is obtained from room-temperature expanded graphite (RTEG), not involving the use of graphite oxide (GO). Porous carbon is acquired by carbonization and KOH-activation of polyvinylpyrrolidone (PVP), which is used to exfoliate RTEG into graphene and inhibit the restacking of the resultant graphene in the present work. The prepared porous carbon/graphene composite has a high specific surface area (SSA) (3008 m 2 g -1 ) and a hierarchical micro- and meso- pore structure (dominant pores in the range of 1-5 nm). Electrochemical measurement demonstrates that the as-prepared porous carbon/graphene composite can deliver an outstanding specific capacitance of up to 340 F g -1 at 5 mV s -1 in 6 M KOH electrolyte. This specific capacitance is among the highest reported so far for porous carbon/graphene materials. Moreover, the prepared composite as an electrode material also exhibits excellent cycling stability (94.4% capacitance retention over 10 000 cycles). The as-fabricated symmetrical supercapacitor exhibits a high energy density of 10.9 W h kg -1 (based on total mass of electrode materials) and an outstanding energy density retention, even at high power density. Compared with conventional preparation routes for porous carbon/graphene composites, the present approach is significantly simple, convenient and cost-effective, which will make it more competent in the development of electrode materials for high-performance supercapacitors.

  17. Evaluating healthcare priority setting at the meso level: A thematic review of empirical literature

    Science.gov (United States)

    Waithaka, Dennis; Tsofa, Benjamin; Barasa, Edwine

    2018-01-01

    Background: Decentralization of health systems has made sub-national/regional healthcare systems the backbone of healthcare delivery. These regions are tasked with the difficult responsibility of determining healthcare priorities and resource allocation amidst scarce resources. We aimed to review empirical literature that evaluated priority setting practice at the meso (sub-national) level of health systems. Methods: We systematically searched PubMed, ScienceDirect and Google scholar databases and supplemented these with manual searching for relevant studies, based on the reference list of selected papers. We only included empirical studies that described and evaluated, or those that only evaluated priority setting practice at the meso-level. A total of 16 papers were identified from LMICs and HICs. We analyzed data from the selected papers by thematic review. Results: Few studies used systematic priority setting processes, and all but one were from HICs. Both formal and informal criteria are used in priority-setting, however, informal criteria appear to be more perverse in LMICs compared to HICs. The priority setting process at the meso-level is a top-down approach with minimal involvement of the community. Accountability for reasonableness was the most common evaluative framework as it was used in 12 of the 16 studies. Efficiency, reallocation of resources and options for service delivery redesign were the most common outcome measures used to evaluate priority setting. Limitations: Our study was limited by the fact that there are very few empirical studies that have evaluated priority setting at the meso-level and there is likelihood that we did not capture all the studies. Conclusions: Improving priority setting practices at the meso level is crucial to strengthening health systems. This can be achieved through incorporating and adapting systematic priority setting processes and frameworks to the context where used, and making considerations of both process

  18. Silica nanoparticle stability in biological media revisited.

    Science.gov (United States)

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

    2018-01-09

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

  19. Light and Strong Hierarchical Porous SiC Foam for Efficient Electromagnetic Interference Shielding and Thermal Insulation at Elevated Temperatures.

    Science.gov (United States)

    Liang, Caiyun; Wang, Zhenfeng; Wu, Lina; Zhang, Xiaochen; Wang, Huan; Wang, Zhijiang

    2017-09-06

    A novel light but strong SiC foam with hierarchical porous architecture was fabricated by using dough as raw material via carbonization followed by carbothermal reduction with silicon source. A significant synergistic effect is achieved by embedding meso- and nanopores in a microsized porous skeleton, which endows the SiC foam with high-performance electromagnetic interference (EMI) shielding, thermal insulation, and mechanical properties. The microsized skeleton withstands high stress. The meso- and nanosized pores enhance multiple reflection of the incident electromagnetic waves and elongate the path of heat transfer. For the hierarchical porous SiC foam with 72.8% porosity, EMI shielding can be higher than 20 dB, and specific EMI effectiveness exceeds 24.8 dB·cm 3 ·g -1 at a frequency of 11 GHz at 25-600 °C, which is 3 times higher than that of dense SiC ceramic. The thermal conductivity reaches as low as 0.02 W·m -1 ·K -1 , which is comparable to that of aerogel. The compressive strength is as high as 9.8 MPa. Given the chemical and high-temperature stability of SiC, the fabricated SiC foam is a promising candidate for modern aircraft and automobile applications.

  20. Rod-shaped silica particles derivatized with elongated silver nanoparticles immobilized within mesopores

    Energy Technology Data Exchange (ETDEWEB)

    Mnasri, Najib [Institut Charles Gerhardt de Montpellier, CNRS UMR 5253, Université Montpellier, Place Eugène Bataillon, 34095 Montpellier Cedex 5 (France); Materials, Environment and Energy Laboratory (UR14ES26), Faculty of Science, University of Gafsa, 2112 Gafsa (Tunisia); Charnay, Clarence; Ménorval, Louis-Charles de [Institut Charles Gerhardt de Montpellier, CNRS UMR 5253, Université Montpellier, Place Eugène Bataillon, 34095 Montpellier Cedex 5 (France); Elaloui, Elimame [Materials, Environment and Energy Laboratory (UR14ES26), Faculty of Science, University of Gafsa, 2112 Gafsa (Tunisia); Zajac, Jerzy, E-mail: jerzy.zajac@umontpellier.fr [Institut Charles Gerhardt de Montpellier, CNRS UMR 5253, Université Montpellier, Place Eugène Bataillon, 34095 Montpellier Cedex 5 (France)

    2016-11-15

    Silver-derivatized silica particles possessing a non-spherical morphology and surface plasmon resonance properties have been achieved. Nanometer-sized silica rods with uniformly sized mesopore channels were prepared first making use of alkyltrimethyl ammonium surfactants as porogens and the 1:0.10 tetraethyl orthosilicate (TEOS) : 3-aminopropyltriethoxysilane (APTES) mixture as a silicon source. Silica rods were subsequently functionalized by introducing elongated silver nanoparticles within the intra-particle mesopores thanks to the AgNO{sub 3} reduction procedure based on the action of hemiaminal groups previously located on the mesopore walls. The textural and structural features of the samples were inferred from the combined characterization studies including SEM and TEM microscopy, nitrogen adsorption-desorption at 77 K, powder XRD in the small- and wide-angle region, as well as UV–visible spectroscopy. {sup 129}Xe NMR spectroscopy appeared particularly useful to obtain a correct information about the porous structure of rod-shaped silica particles and the silver incorporation within their intra-particle mesopores. - Highlights: • Mesoporous monodisperse submicron-sized silica rods were achieved. • Silver nanoparticles were located lengthwise within the intra-particle mesopores. • Textural and plasmonic properties of particles studied by {sup 129}Xe NMR and UV–Vis.

  1. Development of silica RO membranes

    International Nuclear Information System (INIS)

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

    2012-01-01

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

  2. Synthesis and structural evaluation of freeze-cast porous alumina

    Energy Technology Data Exchange (ETDEWEB)

    Souza, Douglas F., E-mail: souzadf@outlook.com [Department of Metallurgical and Materials Engineering, Federal University of Minas Gerais — UFMG, Avenida Presidente Antônio Carlos, 6627, Campus UFMG, Belo Horizonte, MG CEP: 31270-901, Escola de Engenharia, bloco 2, sala 2230 (Brazil); Nunes, Eduardo H.M., E-mail: eduardohmn@gmail.com [Department of Metallurgical and Materials Engineering, Federal University of Minas Gerais — UFMG, Avenida Presidente Antônio Carlos, 6627, Campus UFMG, Belo Horizonte, MG CEP: 31270-901, Escola de Engenharia, bloco 2, sala 2230 (Brazil); Pimenta, Daiana S.; Vasconcelos, Daniela C.L. [Department of Metallurgical and Materials Engineering, Federal University of Minas Gerais — UFMG, Avenida Presidente Antônio Carlos, 6627, Campus UFMG, Belo Horizonte, MG CEP: 31270-901, Escola de Engenharia, bloco 2, sala 2230 (Brazil); Nascimento, Jailton F.; Grava, Wilson [Petrobras/CENPES, Avenida Horácio Macedo 950, Cidade Universitária, Ilha do Fundão, Rio de Janeiro, RJ CEP:21941-915 (Brazil); Houmard, Manuel [Department of Materials Engineering and Civil Construction, Federal University of Minas Gerais — UFMG, Avenida Presidente Antônio Carlos, 6627, Campus UFMG, Belo Horizonte, MG CEP: 31270-901, Escola de Engenharia, bloco 1, sala 3304 (Brazil); Vasconcelos, Wander L., E-mail: wlv@demet.ufmg.br [Department of Metallurgical and Materials Engineering, Federal University of Minas Gerais — UFMG, Avenida Presidente Antônio Carlos, 6627, Campus UFMG, Belo Horizonte, MG CEP: 31270-901, Escola de Engenharia, bloco 2, sala 2230 (Brazil)

    2014-10-15

    In this work we fabricated alumina samples by the freeze-casting technique using tert-butanol as the solvent. The prepared materials were examined by scanning electron microscopy and X-ray microtomography. Next, they were coated with sol–gel silica films by dip-coating. Permeability tests were carried out in order to assess the permeation behavior of the materials processed in this study. We observed that the sintering time and alumina loading showed a remarkable effect on both the structural properties and flexural strength of the freeze-cast samples. Nitrogen adsorption tests revealed that the silica prepared in this study exhibited a microporous structure. It was observed that the presence of silica coatings on the alumina surface decreased the CO{sub 2} permeance by about one order of magnitude. Because of the similar kinetic diameters of nitrogen and carbon dioxide, the CO{sub 2}/N{sub 2} system showed a separation efficiency that was lower than that observed for the He/CO{sub 2} and He/N{sub 2} systems. We noticed that increasing the feed pressure improved the separation capacity of the obtained materials. - Highlights: • Porous alumina samples obtained by the freeze-casting technique • Microporous silica coating prepared by a simple sol–gel dip-coating methodology • Samples examined by SEM, μ-CT, and nitrogen sorption tests • Mechanical tests were carried out in the freeze-cast samples. • The presence of silica coatings on the alumina surface decreased the CO{sub 2} permeance.

  3. Modeling Time-Dependent Behavior of Concrete Affected by Alkali Silica Reaction in Variable Environmental Conditions.

    Science.gov (United States)

    Alnaggar, Mohammed; Di Luzio, Giovanni; Cusatis, Gianluca

    2017-04-28

    Alkali Silica Reaction (ASR) is known to be a serious problem for concrete worldwide, especially in high humidity and high temperature regions. ASR is a slow process that develops over years to decades and it is influenced by changes in environmental and loading conditions of the structure. The problem becomes even more complicated if one recognizes that other phenomena like creep and shrinkage are coupled with ASR. This results in synergistic mechanisms that can not be easily understood without a comprehensive computational model. In this paper, coupling between creep, shrinkage and ASR is modeled within the Lattice Discrete Particle Model (LDPM) framework. In order to achieve this, a multi-physics formulation is used to compute the evolution of temperature, humidity, cement hydration, and ASR in both space and time, which is then used within physics-based formulations of cracking, creep and shrinkage. The overall model is calibrated and validated on the basis of experimental data available in the literature. Results show that even during free expansions (zero macroscopic stress), a significant degree of coupling exists because ASR induced expansions are relaxed by meso-scale creep driven by self-equilibriated stresses at the meso-scale. This explains and highlights the importance of considering ASR and other time dependent aging and deterioration phenomena at an appropriate length scale in coupled modeling approaches.

  4. Niobia-silica and silica membranes for gas separation

    NARCIS (Netherlands)

    Boffa, V.

    2008-01-01

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

  5. Scaling of water vapor in the meso-gamma (2-20km) and lower meso-beta (20-50km) scales from tall tower time series

    Science.gov (United States)

    Pressel, K. G.; Collins, W.; Desai, A. R.

    2011-12-01

    Deficiencies in the parameterization of boundary layer clouds in global climate models (GCMs) remains one of the greatest sources of uncertainty in climate change predictions. Many GCM cloud parameterizations, which seek to include some representation of subgrid-scale cloud variability, do so by making assumptions regarding the subgrid-scale spatial probability density function (PDF) of total water content. Properly specifying the form and parameters of the total water PDF is an essential step in the formulation of PDF based cloud parameterizations. In the cloud free boundary layer, the PDF of total water mixing ratio is equivalent to the PDF of water vapor mixing ratio. Understanding the PDF of water vapor mixing ratio in the cloud free atmosphere is a necessary step towards understanding the PDF of water vapor in the cloudy atmosphere. A primary challenge in empirically constraining the PDF of water vapor mixing ratio is a distinct lack of a spatially distributed observational dataset at or near cloud scale. However, at meso-beta (20-50km) and larger scales, there is a wealth of information on the spatial distribution of water vapor contained in the physically retrieved water vapor profiles from the Atmospheric Infrared Sounder onboard NASA`s Aqua satellite. The scaling (scale-invariance) of the observed water vapor field has been suggested as means of using observations at satellite observed (meso-beta) scales to derive information about cloud scale PDFs. However, doing so requires the derivation of a robust climatology of water vapor scaling from in-situ observations across the meso- gamma (2-20km) and meso-beta scales. In this work, we present the results of the scaling of high frequency (10Hz) time series of water vapor mixing ratio as observed from the 447m WLEF tower located near Park Falls, Wisconsin. Observations from a tall tower offer an ideal set of observations with which to investigate scaling at meso-gamma and meso-beta scales requiring only the

  6. Sonochemical coating of magnetite nanoparticles with silica.

    Science.gov (United States)

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

    2010-01-01

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

  7. 21 CFR 584.700 - Hydrophobic silicas.

    Science.gov (United States)

    2010-04-01

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

  8. Graded/Gradient Porous Biomaterials

    Directory of Open Access Journals (Sweden)

    Xigeng Miao

    2009-12-01

    Full Text Available Biomaterials include bioceramics, biometals, biopolymers and biocomposites and they play important roles in the replacement and regeneration of human tissues. However, dense bioceramics and dense biometals pose the problem of stress shielding due to their high Young’s moduli compared to those of bones. On the other hand, porous biomaterials exhibit the potential of bone ingrowth, which will depend on porous parameters such as pore size, pore interconnectivity, and porosity. Unfortunately, a highly porous biomaterial results in poor mechanical properties. To optimise the mechanical and the biological properties, porous biomaterials with graded/gradient porosity, pores size, and/or composition have been developed. Graded/gradient porous biomaterials have many advantages over graded/gradient dense biomaterials and uniform or homogenous porous biomaterials. The internal pore surfaces of graded/gradient porous biomaterials can be modified with organic, inorganic, or biological coatings and the internal pores themselves can also be filled with biocompatible and biodegradable materials or living cells. However, graded/gradient porous biomaterials are generally more difficult to fabricate than uniform or homogenous porous biomaterials. With the development of cost-effective processing techniques, graded/gradient porous biomaterials can find wide applications in bone defect filling, implant fixation, bone replacement, drug delivery, and tissue engineering.

  9. Bacterial-cellulose-derived interconnected meso-microporous carbon nanofiber networks as binder-free electrodes for high-performance supercapacitors

    Science.gov (United States)

    Hao, Xiaodong; Wang, Jie; Ding, Bing; Wang, Ya; Chang, Zhi; Dou, Hui; Zhang, Xiaogang

    2017-06-01

    Bacterial cellulose (BC), a typical biomass prepared from the microbial fermentation process, has been proved that it can be an ideal platform for design of three-dimensional (3D) multifunctional nanomaterials in energy storage and conversion field. Here we developed a simple and general silica-assisted strategy for fabrication of interconnected 3D meso-microporous carbon nanofiber networks by confine nanospace pyrolysis of sustainable BC, which can be used as binder-free electrodes for high-performance supercapacitors. The synthesized carbon nanofibers exhibited the features of interconnected 3D networks architecture, large surface area (624 m2 g-1), mesopores-dominated hierarchical porosity, and high graphitization degree. The as-prepared electrode (CN-BC) displayed a maximum specific capacitance of 302 F g-1 at a current density of 0.5 A g-1, high-rate capability and good cyclicity in 6 M KOH electrolyte. This work, together with cost-effective preparation strategy to make high-value utilization of cheap biomass, should have significant implications in the green and mass-producible energy storage.

  10. 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.

  11. Modified silica-based heterogeneous catalysts for etherification of glycerol

    Energy Technology Data Exchange (ETDEWEB)

    Gholami, Zahra, E-mail: zahra.gholami@petronas.com.my [Centralized Analytical Laboratory, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 31750 Tronoh, Perak (Malaysia); Abdullah, Ahmad Zuhairi, E-mail: chzuhairi@usm.my; Gholami, Fatemeh, E-mail: fgholami59@gmail.com [School of Chemical Engineering, Universiti Sains Malaysia, Engineering Campus,14300 Nibong Tebal, Penang (Malaysia); Vakili, Mohammadtaghi, E-mail: farshid3601@gmail.com [School of Industrial Technology, Universiti Sains Malaysia, 11800 Penang (Malaysia)

    2015-07-22

    The advent of mesoporous silicas such as MCM-41 has provided new opportunities for research into supported metal catalysis. The loading of metals into framework structures and particularly into the pores of porous molecular sieves, has long been of interest because of their potential catalytic activity. Stable heterogeneous mesoporous basic catalysts were synthesized by wet impregnation of MCM-41 with calcium nitrate and lanthanum nitrate. The surface and structural properties of the prepared catalysts were characterized using BET surface analysis, SEM and TEM. MCM-41 and modified MCM-41 were used in the solventless etherification of glycerol to produce diglycerol as the desired product. The reaction was performed at 250 °C for 8 h, and catalyst activity was evaluated. Catalytic etherification over the 20%Ca{sub 1.6}La{sub 0.6}/MCM-41 catalyst resulted in the highest glycerol conversion of 91% and diglycerol yield of 43%.

  12. Acid leaching of natural chrysotile asbestos to mesoporous silica fibers

    Science.gov (United States)

    Maletaškić, Jelena; Stanković, Nadežda; Daneu, Nina; Babić, Biljana; Stoiljković, Milovan; Yoshida, Katsumi; Matović, Branko

    2018-04-01

    Nanofibrous silica with a high surface area was produced from chrysotile by the acid-leaching method. Natural mineral chrysotile asbestos from Stragari, Korlace in Serbia was used as the starting material. The fibers were modified by chemical treatment with 1 M HCl and the mineral dissolution was monitored by transmission electron microscopy, X-ray powder diffraction, inductively coupled plasma spectrometry and low-temperature nitrogen adsorption techniques to highlight the effects of the leaching process. The results showed that the applied concentration of acid solution and processing time of 4 h were sufficient to effectively remove the magnesium hydroxide layer and transform the crystal structure of the hazardous starting chrysotile to porous SiO2 nanofibers. With prolonged acid leaching, the specific surface area, S BET, calculated by BET equation, was increased from 147 up to 435 m2 g- 1, with micropores representing a significant part of the specific surface.

  13. Modified silica-based heterogeneous catalysts for etherification of glycerol

    International Nuclear Information System (INIS)

    Gholami, Zahra; Abdullah, Ahmad Zuhairi; Gholami, Fatemeh; Vakili, Mohammadtaghi

    2015-01-01

    The advent of mesoporous silicas such as MCM-41 has provided new opportunities for research into supported metal catalysis. The loading of metals into framework structures and particularly into the pores of porous molecular sieves, has long been of interest because of their potential catalytic activity. Stable heterogeneous mesoporous basic catalysts were synthesized by wet impregnation of MCM-41 with calcium nitrate and lanthanum nitrate. The surface and structural properties of the prepared catalysts were characterized using BET surface analysis, SEM and TEM. MCM-41 and modified MCM-41 were used in the solventless etherification of glycerol to produce diglycerol as the desired product. The reaction was performed at 250 °C for 8 h, and catalyst activity was evaluated. Catalytic etherification over the 20%Ca 1.6 La 0.6 /MCM-41 catalyst resulted in the highest glycerol conversion of 91% and diglycerol yield of 43%

  14. Convection in Porous Media

    CERN Document Server

    Nield, Donald A

    2013-01-01

    Convection in Porous Media, 4th Edition, provides a user-friendly introduction to the subject, covering a wide range of topics, such as fibrous insulation, geological strata, and catalytic reactors. The presentation is self-contained, requiring only routine mathematics and the basic elements of fluid mechanics and heat transfer. The book will be of use not only to researchers and practicing engineers as a review and reference, but also to graduate students and others entering the field. The new edition features approximately 1,750 new references and covers current research in nanofluids, cellular porous materials, strong heterogeneity, pulsating flow, and more. Recognized as the standard reference in the field Includes a comprehensive, 250-page reference list Cited over 2300 times to date in its various editions Serves as an introduction for those entering the field and as a comprehensive reference for experienced researchers Features new sections on nanofluids, carbon dioxide sequestration, and applications...

  15. Porous electrode preparation method

    Science.gov (United States)

    Arons, R.M.; Dusek, J.T.

    1983-10-18

    A porous sintered plaque is provided with a bimodal porosity that is especially well suited for use as an electrode within a molten carbonate fuel cell. The coarse porosity is sufficient for admitting gases into contact with the reaction surfaces while the fine porosity is wetted with and retains molten electrolyte on the reaction sites. The electrode structure is prepared by providing a very fine powder of such as nickel oxide and blending the powder with a suitable decomposable binder to form a solid mass. The mass is comminuted into agglomerate size particles substantially larger than the fine oxide particles and formed into a cohesive compact for subsequent sintering. Sintering is carried out at sufficient conditions to bind the agglomerates together into a porous structure having both coarse and fine porosity. Where lithiated nickel oxide cathodes are prepared, the sintering conditions can be moderate enough to retain substantial quantities of lithium within the electrode for adequate conductivity. 2 figs.

  16. Poling of Planar Silica Waveguides

    DEFF Research Database (Denmark)

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

    1999-01-01

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

  17. Functionalized silica materials for electrocatalysis

    Indian Academy of Sciences (India)

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

  18. Monomer functionalized silica coated with Ag nanoparticles for enhanced SERS hotspots

    Science.gov (United States)

    Newmai, M. Boazbou; Verma, Manoj; Kumar, P. Senthil

    2018-05-01

    Mesoporous silica (SiO2) spheres are well-known for their excellent chromatographic properties such as the relatively high specific surface, large pore volume, uniform particle size, narrow pore size distribution with favorable pore connectivity; whereas the noble metal Ag nanoparticles have unique size/shape dependant surface plasmon resonance with wide ranging applications. Thus, the desire to synchronize both their properties for specific applications has naturally prompted research in the design and synthesis of core-shell type novel nanoAg@mesoSiO2 nanocomposites, which display potential utility in applications such as photothermal therapy, photocatalysis, molecular sensing, and photovoltaics. In the present work, SiO2 spheres were carefully functionalized with the monomer, N-vinyl pyrrolidone (NVP), which cohesively controls the uniform mass transfer of Ag+ metal ions, thereby enabling its sequential reduction to zerovalent Ag (in the presence of slightly excess NaOH) by electron transfer from nucleophilic attack of the NVP vinyl group by the water molecules even under ambient conditions. Complete metal nanoshell coverage of the silica surface was obtained after multiple Ag deposition cycles, as systematically confirmed from the BET, TEM, optical and FTIR characterization. Our present Ag-coated silica spheres were directly utilized as viable SERS substrates with high sensitivity in contrast with other long chain polymer/surfactant coated silica spheres, owing to the presence of significant number of nanogaps enhanced SERS 'hotspots', which were methodically analyzed utilizing two example analytes, such as crystal violet (CV) and calendula officinalis (CaF).

  19. Silica nanoparticles containing 159-Gadolinium as potential system for cancer treatment

    International Nuclear Information System (INIS)

    Oliveira, Andre Felipe de; Ferreira, Tiago Hilario; Sousa, Edesia Martins Barros de; Lacerda, Marco Aurelio

    2013-01-01

    Ordered silica nanoparticles are compounds highly organized which have very interesting textural characteristics, such as high thermal stability, well defined pore size, narrow size distribution and high area surface. Among the various types of nano materials ordered, the SBA-16 have a meso structure that can be considered very interesting due to the fact of the arrangement of mesoporous (tri dimensional as a cage) and spherical morphology, which make it in a promising material for a range of bioapplications such as incorporation of drugs and radioisotopes. In this study Gadodiamide® (Omniscan-General Electric Healthcare Company), a frequently non-ionic gadolinium complex contrasting used in MRI's was incorporated in the silica matrix SBA-16 as a carrier. From this gadolinium it is possible to obtain the isotope 159 Gd by neutron irradiation, wherein the isotope 158 Gd captures a neutron and becomes 159 Gd [ 15 '8Gd(n,c) 1 '5 9 Gd]. The 159 Gd is a beta (endpoint energy of 970.6 keV) and gamma (main energy: 363.54 keV) emitter with a half-life of 18.59 hours. These characteristics are similar to that of other isotopes already used in nuclear medicine such as 90 Y. In this work, the 158 Gd incorporated in the Gd-silica was activated by the neutron flux generated by the cyclotron located in the Centro de Desenvolvimento da Tecnologia Nuclear (CDTN) during the production of the 18 FDG. Atomic emission spectroscopy (ICP-AES) and infrared spectroscopy (FTIR) were used to confirm the presence of the gadolinium complex in the silica matrix. The antitumor activity of the complex after the irradiation was evaluated through cytotoxicity assay with T98 cell lines derived from a human glioblastoma multiform tumor. (author)

  20. Porous germanium multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Garralaga Rojas, Enrique; Hensen, Jan; Brendel, Rolf [Institut fuer Solarenergieforschung Hameln (ISFH), Emmerthal (Germany); Carstensen, Juergen; Foell, Helmut [Chair for General Materials Science, Faculty of Engineering, Christian-Albrechts-University of Kiel (Germany)

    2011-06-15

    We present the reproducible fabrication of porous germanium (PGe) single- and multilayers. Mesoporous layers form on heavily doped 4'' p-type Ge wafers by electrochemical etching in highly concentrated HF-based electrolytes with concentrations in a range of 30-50 wt.%. Direct PGe formation is accompanied by a constant dissolution of the already-formed porous layer at the electrolyte/PGe interface, hence yielding a thinner substrate after etching. This effect inhibits multilayer formation as the starting layer is etched while forming the second layer. We avoid dissolution of the porous layer by alternating the etching bias from anodic to cathodic. PGe formation occurs during anodic etching whereas the cathodic step passivates pore walls with H-atoms and avoids electropolishing. The passivation lasts a limited time depending on the etching current density and electrolyte concentration, necessitating a repetition of the cathodic step at suitable intervals. With optimized alternating bias mesoporous multilayer production is possible. We control the porosity of each single layer by varying the etching current density and the electrolyte (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  1. Silica-Coated Liposomes for Insulin Delivery

    Directory of Open Access Journals (Sweden)

    Neelam Dwivedi

    2010-01-01

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

  2. Ultrahigh surface area meso/microporous carbon formed with self-template for high-voltage aqueous supercapacitors

    Science.gov (United States)

    Yang, Jie; Hu, Jiangtao; Zhu, Min; Zhao, Yan; Chen, Haibiao; Pan, Feng

    2017-10-01

    A new hierarchically porous carbon has been synthesized with self-template of silica phase from a commercial silicone resin by pyrolysis and subsequent NaOH activation. The obtained carbon materials achieve an ultrahigh specific surface area (2896 m2 g-1) with abundant mesopores. The C800 sample demonstrates excellent performance in supercapacitors, with a high capacitance of 322 F g-1 at 0.5 A g-1 and outstanding rate capability (182 F g-1 at 100 A g-1) in a three-electrode system using 6.0 mol L-1 KOH electrolyte. The energy density is improved by widening the voltage window using 1.0 mol L-1 alkali metal nitrate solutions (LiNO3, NaNO3, KNO3) in which the strong solvation of alkali metal cations and nitrate anions effectively reduce the activity of water. In a symmetric supercapacitor, the maximum operating voltage is essentially restricted by the potential of positive electrode and the total capacitance is dominated by the capacitance of the anion at the positive electrode. The symmetric supercapacitors based on C800 deliver a high energy density of 22.4 Wh kg-1 at a power density of 0.23 kW kg-1 in 1.0 mol L-1 LiNO3 with a voltage of 1.8 V and long-term stability with a retention of 89.87% after 10000 cycles.

  3. Synthesis and characterization of novel mesocomposites Co3O4 and CuO@OMS (ordered mesoporous silica) as active catalysts for hydrocarbon oxidation

    Science.gov (United States)

    Comănescu, Cezar

    2014-03-01

    Novel metal nanoporous transition metal oxides M x O y (Co3O4, CuO) have been synthesized by thermal decomposition of inorganic salts precursors (acetates, nitrates) impregnated into hexagonal mesoporous silica (OMS, ordered mesoporous silica) of SBA-15 type (prepared in-house) at different precursor loadings, the mesocomposites thus obtained being monitored after each impregnation-calcination step by small and wide angle powder XRD. The pore size for the ordered silica host range from 5.08 to 7.06 nm. Retention of the hexagonal silica framework has been observed in spite of the temperatures up to 500 °C. Mesoporous Co3O4 has been obtained by leaching the silica through overnight HF dissolution, which partially preserved the small-range ordering found in the parent Co3O4@OMS composite prior to leaching. Both Co3O4 ( meso) and Co3O4@SBA-15 have been tested in methane oxidation and were found to be superior to the bulk Co3O4 performance, with mesoporous Co3O4 being able to fully oxidize methane to CO2 and H2O at 350 °C, while Co3O4@OMS exhibits a lower activity with 20 % conversion at 350 °C. CuO@OMS shows the lowest activity, with only 13 % conversion at 500 °C.

  4. Morphology and properties of silica/novolac hybrid xerogels synthesized using sol–gel polymerization at solvent vapor-saturated atmosphere

    International Nuclear Information System (INIS)

    Seraji, Mohamad Mehdi; Seifi, Azadeh; Bahramian, Ahmad Reza

    2015-01-01

    Highlights: • Sol–gel polymerization in vapor of solvent saturated atmosphere is developed. • Highly porous novolac–silica hybrid xerogels are successfully synthesized. • Novolac–silica hybrid gel was dried in ambient condition with low shrinkage. • Required time for preparation of gel reduced from 5 days to about 5 h. • By incorporation of silica into the novolac xerogel structure, the pore size decreases. - Abstract: Highly porous novolac–silica hybrid xerogels were successfully synthesized via the novel method of sol–gel polymerization in solvent vapor-saturated atmosphere. This method removes the need for supercritical drying and yields the hybrid xerogels with reduced shrinkage in comparison with conventional sol–gel process. Tetraethoxysilane (TEOS) was used as the precursor of silica-based inorganic phase. The chemical and structural characterization of the prepared hybrid xerogels were performed by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) analysis, respectively. Thermal and mechanical properties of the hybrid samples were investigated by differential scanning calorimetry (DSC), and compressive strength analysis. The resultant hybrid xerogels show a nanostructured colloidal hybrid network with high porosity (above 80%) and low density (below 0.25 g cm −3 ). Si mapping images shows the good distribution of silica phase throughout the hybrid structure

  5. Synthesis, Characterization and Application of Multiscale Porous Materials

    Energy Technology Data Exchange (ETDEWEB)

    Hussami, Linda

    2010-07-01

    This thesis work brings fresh insights and improved understanding of nano scale materials through introducing new hybrid composites, 2D hexagonal in MCM-41 and 3D random interconnected structures of different materials, and application relevance for developing fields of science, such as fuel cells and solar cells. New types of porous materials and organometallic crystals have been prepared and characterized in detail. The porous materials have been used in several studies: as hosts to encapsulate metal-organic complexes; as catalyst supports and electrode materials in devices for alternative energy production. The utility of the new porous materials arises from their unique structural and surface chemical characteristics as demonstrated here using various experimental and theoretical approaches. New single crystal structures and arene-ligand exchange properties of f-block elements coordinated to ligand arene and halogallates are described in Paper I. These compounds have been incorporated into ordered 2D-hexagonal MCM-41 and polyhedral silica nano foam (PNF-SiO{sub 2}) matrices without significant change to the original porous architectures as described in Paper II and III. The resulting inorganic/organic hybrids exhibited enhanced luminescence activity relative to the pure crystalline complexes. A series of novel polyhedral carbon nano foams (PNF-C's) and inverse foams were prepared by nano casting from PNF-SiO{sub 2}'s. These are discussed in Paper IV. The synthesis conditions of PNF-C's were systematically varied as a function of the filling ratio of carbon precursor and their structures compared using various characterization methods. The carbonaceous porous materials were further tested in Paper V and VI as possible catalysts and catalyst supports in counter- and working electrodes for solar- and fuel cell applications

  6. Study on coal mine macro, meso and micro safety management system

    Directory of Open Access Journals (Sweden)

    Longkang Wang

    2016-03-01

    Full Text Available In recent years, the coal mine safety production situation in our country improved year by year, but severe accidents still occurred; the accidents caused great economic loss to the national economy. According to statistical analysis, almost all of the coal mine accidents will expose the hidden danger in before, most of the accidents caused due to safety management not reaching the designated position and the hidden danger management does not take any decision in time. Based on the coal mine safety management holes in our country, the coal mine macro, meso and micro safety management system was established in this paper, which includes meaning and conception of the theories of the macro, meso and micro safety management, and also includes the matching hardware equipment, in order to achieve the hidden danger's closed-loop control and dynamic early warning in the process of coal mine production.

  7. Acid-base and coordination properties of Meso-substituted porphyrins in nonaqueous solutions

    Science.gov (United States)

    Pukhovskaya, S. G.; Nam, Dao Tkhe; Fien, Chan Ding; Domanina, E. N.; Ivanova, Yu. B.; Semeikin, A. S.

    2017-09-01

    Acid-base and coordination properties of alkyl and aryl meso-substituted porphyrins are studied spectrophotometrically in nonaqueous solutions. It is found that the nature of the substituent greatly affects the basicity of ligands for porphyrins characterized by a flat structure of macrocycle. The electronic effects of substituents have a much weaker influence on the kinetics of complexing. These effects could be due to the opposite orientation of some factors: an increase in the basicity and stability of the N-H bonds of porphyrin reaction centers. Dissociation constants p K b of the cationic forms of meso-substituted derivatives of porphyrin are measured. The values of p K b are in good agreement with classic concepts of the nature of substituents, particularly those indirectly included in the macrocycle through phenyl buffer rings.

  8. The Meso-level Structure of F/OSS Collaboration Network

    DEFF Research Database (Denmark)

    Conald, Guido; Rullani, Francesco

    2010-01-01

    Social networks in Free/Open Source Software (F/OSS) have been usually analyzed at the level of the single project e.g., [6], or at the level of a whole ecology of projects, e.g., [33]. In this paper, we also investigate the social network generated by developers who collaborate to one or multiple...... F/OSS projects, but we focus on the less-studied meso-level structure emerging when applying to this network a community-detection technique. The network of ‘communities’ emerging from this analysis links sub-groups of densely connected developers, sub-groups that are smaller than the components...... of the network but larger than the teams working on single projects. Our results reveal the complexity of this meso-level structure, where several dense sub-groups of developers are connected by sparse collaboration among different sub-groups. We discuss the theoretical implications of our findings...

  9. A CFD Analysis of The Performance of Pin-Fin Laminar Flow Micro/Meso Scale Heat Exchangers

    National Research Council Canada - National Science Library

    Dimas, Sotirios

    2005-01-01

    A full three dimensional computational study was carried out using a finite-volume based solver for analyzing the performance of pin-fin based micro/meso scale heat exchangers with air as the working fluid...

  10. Densification of zirconia films by coevaporation with silica

    International Nuclear Information System (INIS)

    Feldman, A.; Farabaugh, E.N.

    1985-04-01

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

  11. Coastal Foredune Evolution, Part 2: Modeling Approaches for Meso-Scale Morphologic Evolution

    Science.gov (United States)

    2017-03-01

    for Meso-Scale Morphologic Evolution by Margaret L. Palmsten1, Katherine L. Brodie2, and Nicholas J. Spore2 PURPOSE: This Coastal and Hydraulics ...managers because foredunes provide ecosystem services and can reduce storm damages to coastal infrastructure, both of which increase the resiliency...MS 2 U.S. Army Engineer Research and Development Center, Coastal and Hydraulics Laboratory, Duck, NC ERDC/CHL CHETN-II-57 March 2017 2 models of

  12. Meso-scale effects of tropical deforestation in Amazonia: preparatory LBA modelling studies

    Directory of Open Access Journals (Sweden)

    A. J. Dolman

    1999-08-01

    Full Text Available As part of the preparation for the Large-Scale Biosphere Atmosphere Experiment in Amazonia, a meso-scale modelling study was executed to highlight deficiencies in the current understanding of land surface atmosphere interaction at local to sub-continental scales in the dry season. Meso-scale models were run in 1-D and 3-D mode for the area of Rondonia State, Brazil. The important conclusions are that without calibration it is difficult to model the energy partitioning of pasture; modelling that of forest is easier due to the absence of a strong moisture deficit signal. The simulation of the boundary layer above forest is good, above deforested areas (pasture poor. The models' underestimate of the temperature of the boundary layer is likely to be caused by the neglect of the radiative effects of aerosols caused by biomass burning, but other factors such as lack of sufficient entrainment in the model at the mixed layer top may also contribute. The Andes generate patterns of subsidence and gravity waves, the effects of which are felt far into the Rondonian area The results show that the picture presented by GCM modelling studies may need to be balanced by an increased understanding of what happens at the meso-scale. The results are used to identify key measurements for the LBA atmospheric meso-scale campaign needed to improve the model simulations. Similar modelling studies are proposed for the wet season in Rondonia, when convection plays a major role.Key words. Atmospheric composition and structure (aerosols and particles; biosphere-atmosphere interactions · Meterology and atmospheric dynamics (mesoscale meterology

  13. Genetic determination of the meso-diaminopimelate biosynthetic pathway of mycobacteria.

    OpenAIRE

    Cirillo, J. D.; Weisbrod, T. R.; Banerjee, A.; Bloom, B. R.; Jacobs, W. R.

    1994-01-01

    The increasing incidence of multiple-drug-resistant mycobacterial infections indicates that the development of new methods for treatment of mycobacterial diseases should be a high priority. meso-Diaminopimelic acid (DAP), a key component of a highly immunogenic subunit of the mycobacterial peptidoglycan layer, has been implicated as a potential virulence factor. The mycobacterial DAP biosynthetic pathway could serve as a target for design of new antimycobacterial agents as well as the constru...

  14. [Soil meso- and micro-fauna community structures in different urban forest types in Shanghai, China.

    Science.gov (United States)

    Jin, Shi Ke; Wang, Juan Juan; Zhu, Sha; Zhang, Qi; Li, Xiang; Zheng, Wen Jing; You, Wen Hui

    2016-07-01

    Soil meso- and micro-fauna of four urban forest types in Shanghai were investigated in four months which include April 2014, July 2014, October 2014 and January 2015. A total of 2190 soil fauna individuals which belong to 6 phyla, 15 classes and 22 groups were collected. The dominant groups were Nematoda and Arcari, accounting for 56.0% and 21.8% of the total in terms of individual numbers respectively. The common groups were Enchytraeidae, Rotatoria, Collembola and Hymenoptera and they accounted for 18.7% of the total in terms of individual numbers. There was a significant difference (PMetasequoia glyptostroboides forest, the smallest in Cinnamomum camphora forest. The largest groupe number was found in near-nature forest, the smallest was found in M. glyptostroboides forest. There was obvious seasonal dynamics in each urban forest type and green space which had larger density in autumn and larger groupe number in summer and autumn. In soil profiles, the degree of surface accumulation of soil meso- and micro-fauna in C. camphora forest was higher than in other forests and the vertical distribution of soil meso- and micro-fauna in near-nature forest was relatively homogeneous in four layers. Density-group index was ranked as: near-nature forest (6.953)> C. camphora forest (6.351)> Platanus forest (6.313)>M. glyptostroboides forest (5.910). The community diversity of soil fauna in each vegetation type could be displayed preferably by this index. It could be inferred through redundancy analysis (RDA) that the soil bulk density, organic matter and total nitrogen were the main environmental factors influencing soil meso- and micro-fauna community structure in urban forest. The positive correlations occurred between the individual number of Arcari, Enchytraeidae and soil organic matter and total nitrogen, as well as between the individual number of Diptera larvae, Rotatoria and soil water content.

  15. Meso-scale effects of tropical deforestation in Amazonia: preparatory LBA modelling studies

    Directory of Open Access Journals (Sweden)

    A. J. Dolman

    Full Text Available As part of the preparation for the Large-Scale Biosphere Atmosphere Experiment in Amazonia, a meso-scale modelling study was executed to highlight deficiencies in the current understanding of land surface atmosphere interaction at local to sub-continental scales in the dry season. Meso-scale models were run in 1-D and 3-D mode for the area of Rondonia State, Brazil. The important conclusions are that without calibration it is difficult to model the energy partitioning of pasture; modelling that of forest is easier due to the absence of a strong moisture deficit signal. The simulation of the boundary layer above forest is good, above deforested areas (pasture poor. The models' underestimate of the temperature of the boundary layer is likely to be caused by the neglect of the radiative effects of aerosols caused by biomass burning, but other factors such as lack of sufficient entrainment in the model at the mixed layer top may also contribute. The Andes generate patterns of subsidence and gravity waves, the effects of which are felt far into the Rondonian area The results show that the picture presented by GCM modelling studies may need to be balanced by an increased understanding of what happens at the meso-scale. The results are used to identify key measurements for the LBA atmospheric meso-scale campaign needed to improve the model simulations. Similar modelling studies are proposed for the wet season in Rondonia, when convection plays a major role.

    Key words. Atmospheric composition and structure (aerosols and particles; biosphere-atmosphere interactions · Meterology and atmospheric dynamics (mesoscale meterology

  16. Tadalafil inclusion in microporous silica as effective dissolution enhancer: optimization of loading procedure and molecular state characterization.

    Science.gov (United States)

    Mehanna, Mohammed M; Motawaa, Adel M; Samaha, Magda W

    2011-05-01

    Tadalafil is an efficient drug used to treat erectile dysfunction characterized by poor water solubility, which has a negative influence on its bioavailability. Utilization of microporous silica represents an effective and facile technology to increase the dissolution rate of poorly soluble drugs. Our strategy involved directly introducing tadalafil as guest molecule into microporous silica as host material by incipient wetness impregnation method. To optimize tadalafil inclusion, response surface methodology (RSM) using 3(3) factorial design was utilized. Furthermore, to investigate the molecular state of tadalafil, Fourier-transform infrared spectroscopy, differential scanning calorimetery, thermal gravimetrical analysis, nitrogen adsorption, and powder X-ray diffraction (PXRD) were carried out. The results obtained pointed out that the quantity of microporous silica was the predominant factor that increased the loading efficiency. For the optimized formula, the loading efficiency was 42.50 wt %. Adsorption-desorption experiments indicated that tadalafil has been introduced into the micropores. Powder XRD and differential scanning calorimetry analyses revealed that tadalafil is arranged in amorphous form. In addition, the dissolution rate of tadalafil from the microporous silica was faster than that of free drug. Amorphous tadalafil occluded in microporous silica did not crystallize over 3 months. These findings contributed in opening a new strategy concerning the utilization of porous silica for the dissolution rate enhancement. Copyright © 2010 Wiley-Liss, Inc.

  17. Porous ceramics out of oxides

    International Nuclear Information System (INIS)

    Bakunov, V.S.; Balkevich, V.L.; Vlasov, A.S.; Guzman, I.Ya.; Lukin, E.S.; Poluboyarinov, D.N.; Poliskij, R.Ya.

    1977-01-01

    A review is made of manufacturing procedures and properties of oxide ceramics intended for high-temperature thermal insulation and thermal protection applications. Presented are structural characteristics of porous oxide refractories and their properties. Strength and thermal conductivity was shown to depend upon porosity. Described is a procedure for manufacturing porous ceramic materials from aluminium oxide, zirconium dioxide, magnesium oxide, beryllium oxide. The thermal resistance of porous ceramics from BeO is considerably greater than that of other high-refractoriness oxides. Listed are areas of application for porous materials based on oxides

  18. Selective formation of porous silicon

    Science.gov (United States)

    Fathauer, Robert W. (Inventor); Jones, Eric W. (Inventor)

    1993-01-01

    A pattern of porous silicon is produced in the surface of a silicon substrate by forming a pattern of crystal defects in said surface, preferably by applying an ion milling beam through openings in a photoresist layer to the surface, and then exposing said surface to a stain etchant, such as HF:HNO3:H2O. The defected crystal will preferentially etch to form a pattern of porous silicon. When the amorphous content of the porous silicon exceeds 70 percent, the porous silicon pattern emits visible light at room temperature.

  19. Mesoporous silica nanoparticles for treating spinal cord injury

    Science.gov (United States)

    White-Schenk, Désirée.; Shi, Riyi; Leary, James F.

    2013-02-01

    An estimated 12,000 new cases of spinal cord injury (SCI) occur every year in the United States. A small oxidative molecule responsible for secondary injury, acrolein, is an important target in SCI. Acrolein attacks essential proteins and lipids, creating a feed-forward loop of oxidative stress in both the primary injury area and the surrounding areas. A small molecule used and FDA-approved for hypertension, hydralazine, has been found to "scavenge" acrolein after injury, but its delivery and short half-life, as well as its hypertension effects, hinder its application for SCI. Nanomedical systems broaden the range of therapeutic availability and efficacy over conventional medicine. They allow for targeted delivery of therapeutic molecules to tissues of interest, reducing side effects of untargeted therapies in unwanted areas. Nanoparticles made from silica form porous networks that can carry therapeutic molecules throughout the body. To attenuate the acrolein cascade and improve therapeutic availability, we have used a one-step, modified Stober method to synthesize two types of silica nanoparticles. Both particles are "stealth-coated" with poly(ethylene) glycol (PEG) (to minimize interactions with the immune system and to increase circulation time), which is also a therapeutic agent for SCI by facilitating membrane repair. One nanoparticle type contains an amine-terminal PEG (SiNP-mPEG-Am) and the other possesses a terminal hydrazide group (SiNP-mPEG-Hz). The former allows for exploration of hydralazine delivery, loading, and controlled release. The latter group has the ability to react with acrolein, allowing the nanoparticle to scavenge directly. The nanoparticles have been characterized and are being explored using neuronal PC-12 cells in vitro, demonstrating the potential of novel silica nanoparticles for use in attenuating secondary injury after SCI.

  20. Microstructure investigation on micropore formation in microporous silica materials prepared via a catalytic sol-gel process by small angle X-ray scattering.

    Science.gov (United States)

    Shimizu, Wataru; Hokka, Junsuke; Sato, Takaaki; Usami, Hisanao; Murakami, Yasushi

    2011-08-04

    The so-called sol-gel technique has been shown to be a template-free, efficient way to create functional porous silica materials having uniform micropores. This appears to be closely linked with a postulation that the formation of weakly branched polymer-like aggregates in a precursor solution is a key to the uniform micropore generation. However, how such a polymer-like structure can precisely be controlled, and further, how the generated low-fractal dimension solution structure is imprinted on the solid silica materials still remain elusive. Here we present fabrication of microporous silica from tetramethyl orthosilicate (TMOS) using a recently developed catalytic sol-gel process based on a nonionic hydroxyacetone (HA) catalyst. Small angle X-ray scattering (SAXS), nitrogen adsorption porosimetry, and transmission electron microscope (TEM) allowed us to observe the whole structural evolution, ranging from polymer-like aggregates in the precursor solution to agglomeration with heat treatment and microporous morphology of silica powders after drying and hydrolysis. Using the HA catalyst with short chain monohydric alcohols (methanol or ethanol) in the precursor solution, polymer-like aggregates having microscopic correlation length (or mesh-size) micropores with diameters 2 nm) in the solid product due to apertures between the particle-like aggregates. The data demonstrate that the extremely fine porous silica architecture comes essentially from a gaussian polymer-like nature of the silica aggregates in the precursor having the microscopic mesh-size and their successful imprint on the solid product. The result offers a general but significantly efficient route to creating precisely designed fine porous silica materials under mild condition that serve as low refractive index and efficient thermal insulation materials in their practical applications.

  1. Energy intensities in Mato Grosso state and in meso-regions; Intensidades energeticas nas mesorregioes de Mato Grosso

    Energy Technology Data Exchange (ETDEWEB)

    Canavarros, Otacilio Borges; Melo, Moises Candido de; Dorileo, Ivo Leandro [Universidade Federal de Mato Grosso (UFMT), Cuiaba, MT (Brazil). Nucleo Interdisciplinar de Estudos em Planejamento Energetico (NIEPE)

    2004-07-01

    This work presents some energetic intensities in Mato Grosso state and in each of its five meso-regions that are in the document produced in 2002 by the NIPE/UFMT (Nucleo Interdisciplinar de Estudos em Planejamento Energetico of the Universidade Federal do Mato Grosso) entitled: 'Energetic Balance of the Mato Grosso and meso-regions: period 1995-2001'. (author)

  2. Discrete meso-element simulation of the failure behavior of short-fiber composites under dynamic loading

    International Nuclear Information System (INIS)

    Liu Wenyan; Tang, Z.P.; Liu Yunxin

    2000-01-01

    In recent years, more attention has been paid to a better understanding of the failure behavior and mechanism of heterogeneous materials at the meso-scale level. In this paper, the crack initiation and development in epoxy composites reinforced with short steel fibers under dynamic loading were simulated and analyzed with the 2D Discrete Meso-Element Dynamic Method. Results show that the damage process depends greatly on the binding property between matrix and fibers

  3. [Community structure of soil meso- and micro-fauna in different habitats of urbanized region].

    Science.gov (United States)

    Qin, Zhong; Zhang, Jia-en; Li, Qing-fang

    2009-12-01

    Investigations were made in May, June, and November 2007 and January 2008 to study the structural characteristics and their seasonal variations of soil meso- and micro-fauna communities in six habitats of three land use types (forest land, constructed grassland and farmland) in Tianhe District of Guangzhou City. The horizontal spatial distribution of soil fauna differed with habitat. During the investigation periods, the Botanical Garden of South China Agricultural University had the highest individual number (1286) of soil mesa- and micro-fauna, while the farmland, especially in the Fenghuang Street area, had the lowest number of individuals and groups. The seasonal variation of the individual number was in order of autumn (1815) > spring (1623) > winter (1365) > summer (1276). Hierarchical clustering and detrended correspondence analysis also showed that the community composition of soil meso- and micro-fauna in different habitats exhibited distinct seasonal variation. In the same seasons, the community structure and composition of soil meso- and micro-fauna in different habitats were correlated to the degrees of human interferences and the properties of soil environment.

  4. Overview of the Meso-NH model version 5.4 and its applications

    Directory of Open Access Journals (Sweden)

    C. Lac

    2018-05-01

    Full Text Available This paper presents the Meso-NH model version 5.4. Meso-NH is an atmospheric non hydrostatic research model that is applied to a broad range of resolutions, from synoptic to turbulent scales, and is designed for studies of physics and chemistry. It is a limited-area model employing advanced numerical techniques, including monotonic advection schemes for scalar transport and fourth-order centered or odd-order WENO advection schemes for momentum. The model includes state-of-the-art physics parameterization schemes that are important to represent convective-scale phenomena and turbulent eddies, as well as flows at larger scales. In addition, Meso-NH has been expanded to provide capabilities for a range of Earth system prediction applications such as chemistry and aerosols, electricity and lightning, hydrology, wildland fires, volcanic eruptions, and cyclones with ocean coupling. Here, we present the main innovations to the dynamics and physics of the code since the pioneer paper of Lafore et al. (1998 and provide an overview of recent applications and couplings.

  5. A functional interaction approach to the definition of meso regions: The case of the Czech Republic

    Directory of Open Access Journals (Sweden)

    Erlebach Martin

    2016-06-01

    Full Text Available The definition of functional meso regions for the territory of the Czech Republic is articulated in this article. Functional regions reflect horizontal interactions in space and are presented as a useful tool for various types of geographical analyses, and also for spatial planning, economic policy designs, etc. This paper attempts to add to the discussion on the need to delineate areal units at different hierarchical levels, and to understand the functional flows and spatial behaviours of the population in a given space. Three agglomerative methods are applied in the paper (the CURDS regionalisation algorithm, Intramax, and cluster analysis, and they have not been used previously in Czech geography for the delineation of functional meso regions. Existing functional regions at the micro-level, based on daily travel-to-work flows from the 2001 census, have served as the building blocks. The analyses have produced five regional systems at the meso level, based on daily labour commuting movements of the population. Basic statistics and a characterisation of these systems are provided in this paper.

  6. Luminescence of Tb.sup.3+./sup.-doped high silica glass under UV and X-ray excitation

    Czech Academy of Sciences Publication Activity Database

    Chewpraditkul, W.; Shen, Y.; Chen, D.; Beitlerová, Alena; Nikl, Martin

    2013-01-01

    Roč. 35, č. 3 (2013), s. 426-430 ISSN 0925-3467 R&D Projects: GA MŠk LH12185 Institutional support: RVO:68378271 Keywords : Tb 3+ * luminescence * luminescence decays * porous silica glass * scintillation Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.075, year: 2013 http://dx.doi.org/10.1016/j.optmat.2012.09.012

  7. Influence of structure of carrier (silica gel) on texture and catalytic properties of vanadium catalysts for sulfur dioxide oxidation

    International Nuclear Information System (INIS)

    Simonova, L.G.; Fenelonov, V.B.; Dzis'ko, V.A.; Noskova, S.P.; Kryukova, G.N.; Litvak, G.S.

    1982-01-01

    The influence of initial porous structure of a carrier-silica gel on texture and catalytic properties of vanadium catalysts is considered. It is shown that low thermal stability of the carrier results not only in considerable decrease of the catalyst surface during heat treatment but also in blocking part of active component in locked pores which accounts for the activity decrease in kinetic region and formation of active component forms that can not be extracted by acid

  8. Creating 3D Hierarchical Carbon Architectures with Micro-, Meso-, and Macropores via a Simple Self-Blowing Strategy for a Flow-through Deionization Capacitor.

    Science.gov (United States)

    Zhao, Shanshan; Yan, Tingting; Wang, Hui; Zhang, Jianping; Shi, Liyi; Zhang, Dengsong

    2016-07-20

    In this work, 3D hierarchical carbon architectures (3DHCAs) with micro-, meso-, and macropores were prepared via a simple self-blowing strategy as highly efficient electrodes for a flow-through deionization capacitor (FTDC). The obtained 3DHCAs have a hierarchically porous structure, large accessible specific surface area (2061 m(2) g(-1)), and good wettability. The electrochemical tests show that the 3DHCA electrode has a high specific capacitance and good electric conductivity. The deionization experiments demonstrate that the 3DHCA electrodes possess a high deionization capacity of 17.83 mg g(-1) in a 500 mg L(-1) NaCl solution at 1.2 V. Moreover, the 3DHCA electrodes present a fast deionization rate in 100-500 mg L(-1) NaCl solutions at 0.8-1.4 V. The 3DHCA electrodes also present a good regeneration behavior in the reiterative regeneration test. These above factors render the 3DHCAs a promising FTDC electrode material.

  9. Core-shell microspheres with porous nanostructured shells for liquid chromatography.

    Science.gov (United States)

    Ahmed, Adham; Skinley, Kevin; Herodotou, Stephanie; Zhang, Haifei

    2018-01-01

    The development of new stationary phases has been the key aspect for fast and efficient high-performance liquid chromatography separation with relatively low backpressure. Core-shell particles, with a solid core and porous shell, have been extensively investigated and commercially manufactured in the last decade. The excellent performance of core-shell particles columns has been recorded for a wide range of analytes, covering small and large molecules, neutral and ionic (acidic and basic), biomolecules and metabolites. In this review, we first introduce the advance and advantages of core-shell particles (or more widely known as superficially porous particles) against non-porous particles and fully porous particles. This is followed by the detailed description of various methods used to fabricate core-shell particles. We then discuss the applications of common silica core-shell particles (mostly commercially manufactured), spheres-on-sphere particles and core-shell particles with a non-silica shell. This review concludes with a summary and perspective on the development of stationary phase materials for high-performance liquid chromatography applications. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    Directory of Open Access Journals (Sweden)

    Seo Young Yoon

    2013-01-01

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

  11. Silica aerogel and space astrophysics

    International Nuclear Information System (INIS)

    Koch-Miramond, L.

    1985-09-01

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

  12. Silica Nanofiber Combat Hemostat (SINCH)

    Science.gov (United States)

    2008-10-13

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

  13. Optical performance of hybrid porous silicon-porous alumina multilayers

    Science.gov (United States)

    Cencha, L. G.; Antonio Hernández, C.; Forzani, L.; Urteaga, R.; Koropecki, R. R.

    2018-05-01

    In this work, we study the optical response of structures involving porous silicon and porous alumina in a multi-layered hybrid structure. We performed a rational design of the optimal sequence necessary to produce a high transmission and selective filter, with potential applications in chemical and biosensors. The combination of these porous materials can be used to exploit its distinguishing features, i.e., high transparency of alumina and high refractive index of porous silicon. We assembled hybrid microcavities with a central porous alumina layer between two porous silicon Bragg reflectors. In this way, we constructed a Fabry-Perot resonator with high reflectivity and low absorption that improves the quality of the filter compared to a microcavity built only with porous silicon or porous alumina. We explored a simpler design in which one of the Bragg reflectors is replaced by the aluminium that remains bound to the alumina after its fabrication. We theoretically explored the potential of the proposal and its limitations when considering the roughness of the layers. We found that the quality of a microcavity made entirely with porous silicon shows a limit in the visible range due to light absorption. This limitation is overcome in the hybrid scheme, with the roughness of the layers determining the ultimate quality. Q-factors of 220 are experimentally obtained for microcavities supported on aluminium, while Q-factors around 600 are reached for microcavities with double Bragg reflectors, centred at 560 nm. This represents a four-fold increase with respect to the optimal porous silicon microcavity at this wavelength.

  14. Morphology and orientational behavior of silica-coated spindle-type hematite particles in a magnetic field probed by small-angle X-ray scattering.

    Science.gov (United States)

    Reufer, Mathias; Dietsch, Hervé; Gasser, Urs; Hirt, Ann; Menzel, Andreas; Schurtenberger, Peter

    2010-04-15

    Form factor and magnetic properties of silica-coated spindle-type hematite nanoparticles are determined from SAXS measurements with applied magnetic field and magnetometry measurements. The particle size, polydispersity and porosity are determined using a core-shell model for the form factor. The particles are found to align with their long axis perpendicular to the applied field. The orientational order is determined from the SAXS data and compared to the orientational order obtained from magnetometry. The direct access to both, the orientational order of the particles, and the magnetic moments allow one to determine the magnetic properties of the individual spindle-type hematite particles. We study the influence of the silica coating on the magnetic properties and find a fundamentally different behavior of silica-coated particles. The silica coating reduces the effective magnetic moment of the particles. This effect is enhanced with field strength and can be explained by superparamagnetic relaxation in the highly porous particles.

  15. Synthesis, characterization, and evaluation of a superficially porous particle with unique, elongated pore channels normal to the surface.

    Science.gov (United States)

    Wei, Ta-Chen; Mack, Anne; Chen, Wu; Liu, Jia; Dittmann, Monika; Wang, Xiaoli; Barber, William E

    2016-04-01

    In recent years, superficially porous particles (SPPs) have drawn great interest because of their special particle characteristics and improvement in separation efficiency. Superficially porous particles are currently manufactured by adding silica nanoparticles onto solid cores using either a multistep multilayer process or one-step coacervation process. The pore size is mainly controlled by the size of the silica nanoparticles and the tortuous pore channel geometry is determined by how those nanoparticles randomly aggregate. Such tortuous pore structure is also similar to that of all totally porous particles used in HPLC today. In this article, we report on the development of a next generation superficially porous particle with a unique pore structure that includes a thinner shell thickness and ordered pore channels oriented normal to the particle surface. The method of making the new superficially porous particles is a process called pseudomorphic transformation (PMT), which is a form of micelle templating. Porosity is no longer controlled by randomly aggregated nanoparticles but rather by micelles that have an ordered liquid crystal structure. The new particle possesses many advantages such as a narrower particle size distribution, thinner porous layer with high surface area and, most importantly, highly ordered, non-tortuous pore channels oriented normal to the particle surface. This PMT process has been applied to make 1.8-5.1μm SPPs with pore size controlled around 75Å and surface area around 100m(2)/g. All particles with different sizes show the same unique pore structure with tunable pore size and shell thickness. The impact of the novel pore structure on the performance of these particles is characterized by measuring van Deemter curves and constructing kinetic plots. Reduced plate heights as low as 1.0 have been achieved on conventional LC instruments. This indicates higher efficiency of such particles compared to conventional totally porous and

  16. Hydrothermal assisted synthesis of iron oxide-based magnetic silica spheres and their performance in magnetophoretic water purification

    Energy Technology Data Exchange (ETDEWEB)

    Caparros, C., E-mail: ccaparros@fisica.uminho.pt [Centro de Fisica, Universidade do Minho, Campus de Gualtar, 4710-057 Braga (Portugal); Benelmekki, M.; Martins, P.M. [Centro de Fisica, Universidade do Minho, Campus de Gualtar, 4710-057 Braga (Portugal); Xuriguera, E. [Facultat de Quimica, Universitat de Barcelona, 08028 Barcelona (Spain); Silva, C.J.R. [Departamento de Quimica, Universidade do Minho, Campus de Gualtar, 4710-057 Braga (Portugal); Martinez, Ll.M. [Sepmag Technologies, Parc Tecnologic del Valles, 08290 Barcelona (Spain); Lanceros-Mendez, S. [Centro de Fisica, Universidade do Minho, Campus de Gualtar, 4710-057 Braga (Portugal)

    2012-08-15

    Porous Magnetic Silica (PMS) spheres of about 400 nm diameter were synthesised by one-pot process using the classical Stber method combined with hydrothermal treatment. Maghemite nanoparticles ({gamma}-Fe{sub 2}O{sub 3}) were used as fillers and cetyltrimethylammonium bromide (CTAB) was used as templating agent. The application of the hydrothermal process (120 Degree-Sign C during 48 h) before the calcination leads to the formation of homogeneous and narrow size distribution PMS spheres. X-ray diffraction patterns (XRD), Infrared measurements (FTIR) and Transmission Electron microscopy (TEM) methods were used to determine the composition and morphology of the obtained PMS spheres. The results show a homogeneous distribution of the {gamma}-Fe{sub 2}O{sub 3} nanoparticles in the silica matrix with a 'hollow-like' morphology. Magnetophoresis measurements at 60 T m{sup -1} show a total separation time of the PMS spheres suspension of about 16 min. By using this synthesis method, the limitation of the formation of silica spheres without incorporation of magnetic nanoparticles is overcome. These achievements make this procedure interesting for industrial up scaling. The obtained PMS spheres were evaluated as adsorbents for Ni{sup 2+} in aqueous solution. Their adsorption capacity was compared with the adsorption capacity of magnetic silica spheres obtained without hydrothermal treatment before calcination process. PMS spheres show an increase of the adsorption capacity of about 15% of the initial dissolution of Ni{sup 2+} without the need to functionalize the silica surface. Highlights: Black-Right-Pointing-Pointer Homogeneous and controlled size porous magnetic silica spheres were obtained. Black-Right-Pointing-Pointer Magnetophoretic removing of Ni{sup 2+} processes was successfully preformed at HLGMF. Black-Right-Pointing-Pointer PMS show higher Ni{sup 2+} removing capacity than spheres without hydrothermal treatment. Black-Right-Pointing-Pointer PMS can be

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

    Directory of Open Access Journals (Sweden)

    Celil Atik,

    2012-06-01

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

  18. High-silica glass matrix process for high-level waste solidification

    International Nuclear Information System (INIS)

    Simmons, J.H.; Macedo, P.B.

    1981-01-01

    In the search for an optimum glass matrix composition, we have determined that chemical durability and thermal stability are maximized, and that stress development is minimized for glass compositions containing large concentrations of glass-forming oxides, of which silica is the major component (80 mol%). These properties and characteristics were recently demonstrated to belong to very old geological glasses known as tektites (ages of 750,000 to 34 million years.) The barrier to simulating tektite compositions for the waste glasses was the high melting temperature (1600 to 1800 0 C) needed for these glasses. Such temperatures greatly complicate furnace design and maintenance and lead to an intolerable vaporization of many of the radioisotopes into the off-gas system. Research conducted at our laboratory led to the development of a porous high-silica waste glass material with approximately 80% SiO 2 by mole and 30% waste loading by weight. The process can handle a wide variety of compositions, and yields long, elliptical, monolithic samples, which consist of a loaded high-silica core completely enveloped in a high-silica glass tube, which has collapsed upon the core and sealed it from the outside. The outer glass layer is totally free of waste isotopes and provides an integral multibarrier protection system

  19. Modellierung of meso- and macroscale river basins - a workshop held at Lauenburg; Modellierung in meso- bis makroskaligen Flusseinzugsgebieten - Tagungsband zum gleichnamigen Workshop

    Energy Technology Data Exchange (ETDEWEB)

    Sutmoeller, J.; Raschke, E. (eds.) [GKSS-Forschungszentrum Geesthacht GmbH (Germany). Inst. fuer Atmosphaerenphysik

    2001-07-01

    During the past decade measuring and modelling of global and regional processes that exchange energy and water in the climate system of the Earth became a focus in hydrological and meteorological research. Besides climate research many more applications will gain from this effort, e.g. as weather forecasting, water management and agriculture. As large scale weather and climate applications diversify to water related issues such as water resources, reservoir management, and flood and drought forecasting hydrologists and meteorologists are challenged to work interdisciplinary. The workshop 'Modelling of meso- and macroscale river basins' brought together various current aspects of this issue, ranging from coupled atmosphere-hydrology models to integrated river basin management to land use change. Recent results are introduced and summarised in this report. (orig.)

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

    Science.gov (United States)

    Vassilakopoulou, Anastasia; Papadatos, Dionysios; Koutselas, Ioannis

    2017-04-01

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

  1. A study of luminescence from silicon-rich silica fabricated by plasma enhanced chemical vapour deposition

    International Nuclear Information System (INIS)

    Trwoga, P.F.

    1998-01-01

    Silicon is the most studied electronic material known to man and dominates the electronics industry in its use as a semiconductors for nearly all integrated electronics. However, optoelectronics is almost entirely based on III-V materials. This technology is used because silicon is a very inefficient light source, whereas the III-V band structure can lend itself to efficient light emission by electron injection. However, due to the overwhelming dominance of silicon based electronics it is still a highly desirable goal to generate light efficiently from silicon based materials. Recently, studies have demonstrated that efficient visible luminescence can be obtained from certain novel forms of silicon. These materials include porous silicon, hydrogenated amorphous silicon, and silicon-rich silica (SiO x x x is studied in detail; in addition, electroluminescence and rare-earth doping of silicon-rich silica is also addressed. (author)

  2. A tri-continuous mesoporous material with a silica pore wall following a hexagonal minimal surface

    KAUST Repository

    Han, Yu

    2009-04-06

    Ordered porous materials with unique pore structures and pore sizes in the mesoporous range (2-50nm) have many applications in catalysis, separation and drug delivery. Extensive research has resulted in mesoporous materials with one-dimensional, cage-like and bi-continuous pore structures. Three families of bi-continuous mesoporous materials have been made, with two interwoven but unconnected channels, corresponding to the liquid crystal phases used as templates. Here we report a three-dimensional hexagonal mesoporous silica, IBN-9, with a tri-continuous pore structure that is synthesized using a specially designed cationic surfactant template. IBN-9 consists of three identical continuous interpenetrating channels, which are separated by a silica wall that follows a hexagonal minimal surface. Such a tri-continuous mesostructure was predicted mathematically, but until now has not been observed in real materials. © 2009 Macmillan Publishers Limited. All rights reserved.

  3. A tri-continuous mesoporous material with a silica pore wall following a hexagonal minimal surface

    KAUST Repository

    Han, Yu; Zhang, Daliang; Chng, Leng Leng; Sun, Junliang; Zhao, L. J.; Zou, Xiaodong; Ying, Jackie

    2009-01-01

    Ordered porous materials with unique pore structures and pore sizes in the mesoporous range (2-50nm) have many applications in catalysis, separation and drug delivery. Extensive research has resulted in mesoporous materials with one-dimensional, cage-like and bi-continuous pore structures. Three families of bi-continuous mesoporous materials have been made, with two interwoven but unconnected channels, corresponding to the liquid crystal phases used as templates. Here we report a three-dimensional hexagonal mesoporous silica, IBN-9, with a tri-continuous pore structure that is synthesized using a specially designed cationic surfactant template. IBN-9 consists of three identical continuous interpenetrating channels, which are separated by a silica wall that follows a hexagonal minimal surface. Such a tri-continuous mesostructure was predicted mathematically, but until now has not been observed in real materials. © 2009 Macmillan Publishers Limited. All rights reserved.

  4. Silica-Coated Liposomes for Insulin Delivery

    OpenAIRE

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

    2010-01-01

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

  5. Mesoporous Silica: A Suitable Adsorbent for Amines

    Directory of Open Access Journals (Sweden)

    Abdollahzadeh-Ghom Sara

    2009-01-01

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

  6. COOH-functionalisation of silica particles

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-09-01

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

  7. Cellular membrane trafficking of mesoporous silica nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-01-01

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

  8. Practical Hydrogen Loading of Air Silica Fibres

    DEFF Research Database (Denmark)

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

    2005-01-01

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

  9. Synthesis And Characterization Of Pure-Silica- Zeolite-Beta Membrane

    Directory of Open Access Journals (Sweden)

    Yeong Yin Fong

    2017-11-01

    Full Text Available The semiconductor industry needs low dielectric constant (low k-value materials to more advance microprocessor and chips by reducing the size of the device features. In fabricate this context, a new material with lower k value than conventional silica ( k = 3.9 - 4.2 is needed in order to improve the circuit performance. As per the recent International Semiconductor Technology plan, a low-k material with a k = 1.6 will be needed by 2010. The choice of the inorganic zeolite membrane is an attractive option for low k material and suitable for microprocess application.  In the present study, a pure silica zeolite beta membrane coated on the non-porous stainless steel support was synthesized using in situ crystallization of a gel with the composition of  SiO2 : 0.6 TEAOH : 0.6 HF : 10.1 H2O. The crystallization was carried in the presence of tetraethylammonium hydroxide TEA(OH as structure directing agent, fumed silica, HF and deionized water at pH value of 9. The crystallization under hydrothermal conditions at 130oC was carried out for the time period of 14 days. The membrane was characterized by X-Ray Diffraction ( XRD ,  Thermogravimetric Analysis ( TGA , Nitrogen Adsorption and Scanning Electron Microscope ( SEM .   SEM micrographs show highly crystalline, truncated square bipyramidal morphology of pure silica zeolite beta was coated on the non-porous stainless steel support. The membrane dielectric constant, k-value was measured as 2.64 which makes it suitable for the microprocessor applications.

  10. Fabrication and excellent conductive performance of antimony-doped tin oxide-coated diatomite with porous structure

    International Nuclear Information System (INIS)

    Du Yucheng; Yan Jing; Meng Qi; Wang Jinshu; Dai Hongxing

    2012-01-01

    Graphical abstract: Antimony-doped tin oxide (ATO)-coated diatomite with porous structures are fabricated using the co-precipitation method. The porous ATO-coated diatomite material shows excellent conductive performance. Highlights: ► Sb-doped SnO 2 (ATO)-coated diatomite materials with porous structures are prepared. ► Sn/Sb ratio, ATO coating amount, pH value, and temperature influence resistivity. ► Porous ATO-coated diatomite materials show excellent conductive performance. ► The lowest resistivity of the porous ATO-coated diatomite sample is 10 Ω cm. - Abstract: Diatomite materials coated with antimony-doped tin oxide (ATO) were prepared by the co-precipitation method, and characterized by means of the techniques, such as X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, selected-area electron diffraction, X-ray fluorescence spectroscopy, and N 2 adsorption–desorption measurement. It was shown that the coated ATO possessed a tetragonal rutile crystal structure, and the ATO-coated diatomite materials had a multi-pore (micro- meso-, and macropores) architecture. The porous ATO-coated diatomite materials exhibited excellent electrical conductive behaviors. The best conductive performance (volume resistivity = 10 Ω cm) was achieved for the sample that was prepared under the conditions of Sn/Sb molar ratio = 5.2, Sn/Sb coating amount = 45 wt%, pH = 1.0, and reaction temperature = 50 °C. Such a conductive porous material is useful for the applications in physical and chemical fields.

  11. Fabrication and excellent conductive performance of antimony-doped tin oxide-coated diatomite with porous structure

    Energy Technology Data Exchange (ETDEWEB)

    Du Yucheng, E-mail: ychengdu@bjut.edu.cn [Key Lab of Advanced Functional Materials, Ministry of Education, College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124 (China); Yan Jing; Meng Qi; Wang Jinshu [Key Lab of Advanced Functional Materials, Ministry of Education, College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124 (China); Dai Hongxing, E-mail: hxdai@bjut.edu.cn [Laboratory of Catalysis Chemistry and Nanoscience, Department of Chemistry and Chemical Engineering, College of Environmental and Energy Engineering, Beijing University of Technology, Beijing 100124 (China)

    2012-04-16

    Graphical abstract: Antimony-doped tin oxide (ATO)-coated diatomite with porous structures are fabricated using the co-precipitation method. The porous ATO-coated diatomite material shows excellent conductive performance. Highlights: Black-Right-Pointing-Pointer Sb-doped SnO{sub 2} (ATO)-coated diatomite materials with porous structures are prepared. Black-Right-Pointing-Pointer Sn/Sb ratio, ATO coating amount, pH value, and temperature influence resistivity. Black-Right-Pointing-Pointer Porous ATO-coated diatomite materials show excellent conductive performance. Black-Right-Pointing-Pointer The lowest resistivity of the porous ATO-coated diatomite sample is 10 {Omega} cm. - Abstract: Diatomite materials coated with antimony-doped tin oxide (ATO) were prepared by the co-precipitation method, and characterized by means of the techniques, such as X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, selected-area electron diffraction, X-ray fluorescence spectroscopy, and N{sub 2} adsorption-desorption measurement. It was shown that the coated ATO possessed a tetragonal rutile crystal structure, and the ATO-coated diatomite materials had a multi-pore (micro- meso-, and macropores) architecture. The porous ATO-coated diatomite materials exhibited excellent electrical conductive behaviors. The best conductive performance (volume resistivity = 10 {Omega} cm) was achieved for the sample that was prepared under the conditions of Sn/Sb molar ratio = 5.2, Sn/Sb coating amount = 45 wt%, pH = 1.0, and reaction temperature = 50 Degree-Sign C. Such a conductive porous material is useful for the applications in physical and chemical fields.

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

    International Nuclear Information System (INIS)

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

    2003-01-01

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

  13. Structure study of the tri-continuous mesoporous silica IBN-9 by electron crystallography

    KAUST Repository

    Zhang, Daliang

    2011-12-01

    High resolution electron microscopy (HRTEM) has unique advantages for structural determination of nano-sized porous materials compared to X-ray diffraction, because it provides the important structure factor phase information which is lost in diffraction. Here we demonstrate the structure determination of the first tri-continuous mesoporous silica IBN-9 by electron crystallography. IBN-9 has a hexagonal unit cell with the space group P6 3/mcm and a = 88.4 , c = 84.3 . HRTEM images taken along three main directions, [0 0 1], [11̄0] and [1 0 0] were combined to reconstruct the 3D electrostatic potential map, from which the tri-continuous pore structure of IBN-9 was discovered. The different steps of structure determination of unknown mesoporous structures by electron crystallography are described in details. Similar procedures can also be applied for structure determination of other porous and nonporous crystalline materials. © 2011 Elsevier Inc. All rights reserved.

  14. Influence of alkali-silica reaction on the physical, mechanical, and structural behaviour of reinforced concrete

    DEFF Research Database (Denmark)

    Barbosa, Ricardo Antonio

    Alkali-silica reaction (ASR) is one of the major concrete deterioration mechanisms in the world. Cracking in concrete structures due to ASR has been observed worldwide. In Denmark numerous concrete structures have been built with a critical amount of ASR-reactive aggregate, mostly as porous opaline...... and porous calcareous opaline flint in the fine aggregate fraction. During the last few decades, an increasing number of bridges in Denmark have been severely damaged due to ASR. In the most severe cases, the ASR-damaged bridges have been demolished and reconstructed due to uncertainty about their residual...... following features in common: (a) significant amount of ASR cracks were observed on and inside the slabs, (b) the ASR cracks were oriented parallel to the plane of the slabs, and (c) ASR occurred in the fine aggregate fraction. In this PhD study, both the compressive strength and tensile strength of drilled...

  15. Application of diazene-directed fragment assembly to the total synthesis and stereochemical assignment of (+)-desmethyl-meso-chimonanthine and related heterodimeric alkaloids

    OpenAIRE

    Lathrop, Stephen; Movassaghi, Mohammad

    2013-01-01

    We describe the first application of our methodology for heterodimerization via diazene fragmentation towards the total synthesis of (−)-calycanthidine, meso-chimonanthine, and (+)-desmethyl-meso-chimonanthine. Our syntheses of these alkaloids feature an improved route to C3a-aminocyclotryptamines, an enhanced method for sulfamide synthesis and oxidation, in addition to a late-stage diversification leading to the first enantioselective total synthesis of (+)-desmethyl-meso-chimonanthine and i...

  16. Convection in porous media

    CERN Document Server

    Nield, Donald A

    1992-01-01

    This book provides a user-friendly introduction to the topic of convection in porous media The authors as- sume that the reader is familiar with the basic elements of fluid mechanics and heat transfer, but otherwise the book is self-contained The book will be useful both as a review (for reference) and as a tutorial work, suitable as a textbook in a graduate course or seminar The book brings into perspective the voluminous research that has been performed during the last two decades The field has recently exploded because of worldwide concern with issues such as energy self-sufficiency and pollution of the environment Areas of application include the insulation of buildings and equipment, energy storage and recovery, geothermal reservoirs, nuclear waste disposal, chemical reactor engineering, and the storage of heat-generating materials such as grain and coal Geophysical applications range from the flow of groundwater around hot intrusions to the stability of snow against avalanches

  17. Optimized manufacturable porous materials

    DEFF Research Database (Denmark)

    Andreassen, Erik; Andreasen, Casper Schousboe; Jensen, Jakob Søndergaard

    Topology optimization has been used to design two-dimensional material structures with specific elastic properties, but optimized designs of three-dimensional material structures are more scarsely seen. Partly because it requires more computational power, and partly because it is a major challenge...... to include manufacturing constraints in the optimization. This work focuses on incorporating the manufacturability into the optimization procedure, allowing the resulting material structure to be manufactured directly using rapid manufacturing techniques, such as selective laser melting/sintering (SLM....../S). The available manufacturing methods are best suited for porous materials (one constituent and void), but the optimization procedure can easily include more constituents. The elasticity tensor is found from one unit cell using the homogenization method together with a standard finite element (FE) discretization...

  18. Filtration in Porous Media

    DEFF Research Database (Denmark)

    Yuan, Hao; Shapiro, Alexander

    There is a considerable and ongoing effort aimed at understanding the transport and the deposition of suspended particles in porous media, especially non-Fickian transport and non-exponential deposition of particles. In this work, the influential parameters in filtration models are studied...... to understand their effects on the non-Fickian transport and the non-exponential deposition. The filtration models are validated by the comparisons between the modelling results and the experimental data.The elliptic equation with distributed filtration coefficients may be applied to model non-Fickian transport...... and hyperexponential deposition. The filtration model accounting for the migration of surface associated particles may be applied for non-monotonic deposition....

  19. Biogenic Cracks in Porous Rock

    Science.gov (United States)

    Hemmerle, A.; Hartung, J.; Hallatschek, O.; Goehring, L.; Herminghaus, S.

    2014-12-01

    Microorganisms growing on and inside porous rock may fracture it by various processes. Some of the mechanisms of biofouling and bioweathering are today identified and partially understood but most emphasis is on chemical weathering, while mechanical contributions have been neglected. However, as demonstrated by the perseverance of a seed germinating and cracking up a concrete block, the turgor pressure of living organisms can be very significant. Here, we present results of a systematic study of the effects of the mechanical forces of growing microbial populations on the weathering of porous media. We designed a model porous medium made of glass beads held together by polydimethylsiloxane (PDMS), a curable polymer. The rheological properties of the porous medium, whose shape and size are tunable, can be controlled by the ratio of crosslinker to base used in the PDMS (see Fig. 1). Glass and PDMS being inert to most chemicals, we are able to focus on the mechanical processes of biodeterioration, excluding any chemical weathering. Inspired by recent measurements of the high pressure (~0.5 Mpa) exerted by a growing population of yeasts trapped in a microfluidic device, we show that yeast cells can be cultured homogeneously within porous medium until saturation of the porous space. We investigate then the effects of such an inner pressure on the mechanical properties of the sample. Using the same model system, we study also the complex interplay between biofilms and porous media. We focus in particular on the effects of pore size on the penetration of the biofilm within the porous sample, and on the resulting deformations of the matrix, opening new perspectives into the understanding of life in complex geometry. Figure 1. Left : cell culture growing in a model porous medium. The white spheres represent the grains, bonds are displayed in grey, and microbes in green. Right: microscopy picture of glass beads linked by PDMS bridges, scale bar: 100 μm.

  20. Scalable 2D Hierarchical Porous Carbon Nanosheets for Flexible Supercapacitors with Ultrahigh Energy Density.

    Science.gov (United States)

    Yao, Lei; Wu, Qin; Zhang, Peixin; Zhang, Junmin; Wang, Dongrui; Li, Yongliang; Ren, Xiangzhong; Mi, Hongwei; Deng, Libo; Zheng, Zijian

    2018-03-01

    2D carbon nanomaterials such as graphene and its derivatives, have gained tremendous research interests in energy storage because of their high capacitance and chemical stability. However, scalable synthesis of ultrathin carbon nanosheets with well-defined pore architectures remains a great challenge. Herein, the first synthesis of 2D hierarchical porous carbon nanosheets (2D-HPCs) with rich nitrogen dopants is reported, which is prepared with high scalability through a rapid polymerization of a nitrogen-containing thermoset and a subsequent one-step pyrolysis and activation into 2D porous nanosheets. 2D-HPCs, which are typically 1.5 nm thick and 1-3 µm wide, show a high surface area (2406 m 2 g -1 ) and with hierarchical micro-, meso-, and macropores. This 2D and hierarchical porous structure leads to robust flexibility and good energy-storage capability, being 139 Wh kg -1 for a symmetric supercapacitor. Flexible supercapacitor devices fabricated by these 2D-HPCs also present an ultrahigh volumetric energy density of 8.4 mWh cm -3 at a power density of 24.9 mW cm -3 , which is retained at 80% even when the power density is increased by 20-fold. The devices show very high electrochemical life (96% retention after 10000 charge/discharge cycles) and excellent mechanical flexibility. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Potassium vapor assisted preparation of highly graphitized hierarchical porous carbon for high rate performance supercapacitors

    Science.gov (United States)

    Liu, Zheng; Zeng, Ying; Tang, Qunli; Hu, Aiping; Xiao, Kuikui; Zhang, Shiying; Deng, Weina; Fan, Binbin; Zhu, Yanfei; Chen, Xiaohua

    2017-09-01

    Ultrahigh graphitized carbon microspheres with rich hierarchical pores (AGHPCM-1) have been successfully synthesized through the one-step activation-carbonization strategy (OACS) with porous sulfonated poly-divinylbenzene as the carbon precursor, iron as the hard template and catalyst, and potassium hydroxide (KOH) as activation agent. Through the XRD, TEM, Raman and BET analysis, AGHPCM-1 shows very high graphitization degree and rich micro-, meso- and macro-pores. More importantly, the mechanism for KOH to improve the graphitization degree of carbon materials in OACS has been illustrated by the thermodynamical theory. The tremendous heat releasing from the reaction between the catalyst precursor of Fe2O3 and potassium vapor plays a key role in the formation of graphitized carbon. It may provide a general direction to prepare highly graphitized porous carbon at a moderate temperature. Integrating the advantages of high graphitization degree and rich hierarchical porous structure, the AGHPCM-1 exhibits an excellent rate performance with a response to up to the high current density of 150 A g-1 and high scan rate of 2000 mV s-1. No obvious capacitance decay can be observed after 10000 charge/discharge cycles even at the high current density of 20 A g-1.

  2. Preparation and characterization of nanostructured ZrO2 coatings on dense and porous substrates

    International Nuclear Information System (INIS)

    Shi Jingyu; Verweij, Henk

    2008-01-01

    Nanostructured ZrO 2 coatings are prepared on both dense and porous substrates by wet-chemical deposition of non-agglomerated 5 nm precursor particle dispersions, followed by thermal processing. The precursor particle dispersions are made by modified emulsion precipitation and a purification treatment to remove reaction products and additives. The coatings are formed by depositing the precursor nanoparticle dispersion directly onto the substrate, followed by drying and heating at 600 deg. C. Scanning electron microscopy and cross-sectional transmission electron microscopy observations of the heat-treated coatings indicate that the ZrO 2 coating on dense Si wafer substrate has a homogeneous, dense particle packing structure with shallow meniscus-shaped depressions in the surface, and microcracks below the meniscus surface. On the other hand, coatings formed on a meso-porous γ-alumina membrane substrate are free of defects, but with a lower packing density. The mechanism of the substrate effect on the particle packing behavior and defect formation during coating deposition is discussed. It is expected that by using a thin porous substrate with reduced capillary force, a defect-free, homogenously dense-packed coating structure can be achieved

  3. Luminescence of porous silicon doped by erbium

    International Nuclear Information System (INIS)

    Bondarenko, V.P.; Vorozov, N.N.; Dolgij, L.N.; Dorofeev, A.M.; Kazyuchits, N.M.; Leshok, A.A.; Troyanova, G.N.

    1996-01-01

    The possibility of the 1.54 μm intensive luminescence in the silicon dense porous layers, doped by erbium, with various structures is shown. Low-porous materials of both porous type on the p-type silicon and porous silicon with wood-like structure on the n + type silicon may be used for formation of light-emitting structures

  4. Setting Healthcare Priorities at the Macro and Meso Levels: A Framework for Evaluation.

    Science.gov (United States)

    Barasa, Edwine W; Molyneux, Sassy; English, Mike; Cleary, Susan

    2015-09-16

    Priority setting in healthcare is a key determinant of health system performance. However, there is no widely accepted priority setting evaluation framework. We reviewed literature with the aim of developing and proposing a framework for the evaluation of macro and meso level healthcare priority setting practices. We systematically searched Econlit, PubMed, CINAHL, and EBSCOhost databases and supplemented this with searches in Google Scholar, relevant websites and reference lists of relevant papers. A total of 31 papers on evaluation of priority setting were identified. These were supplemented by broader theoretical literature related to evaluation of priority setting. A conceptual review of selected papers was undertaken. Based on a synthesis of the selected literature, we propose an evaluative framework that requires that priority setting practices at the macro and meso levels of the health system meet the following conditions: (1) Priority setting decisions should incorporate both efficiency and equity considerations as well as the following outcomes; (a) Stakeholder satisfaction, (b) Stakeholder understanding, (c) Shifted priorities (reallocation of resources), and (d) Implementation of decisions. (2) Priority setting processes should also meet the procedural conditions of (a) Stakeholder engagement, (b) Stakeholder empowerment, (c) Transparency, (d) Use of evidence, (e) Revisions, (f) Enforcement, and (g) Being grounded on community values. Available frameworks for the evaluation of priority setting are mostly grounded on procedural requirements, while few have included outcome requirements. There is, however, increasing recognition of the need to incorporate both consequential and procedural considerations in priority setting practices. In this review, we adapt an integrative approach to develop and propose a framework for the evaluation of priority setting practices at the macro and meso levels that draws from these complementary schools of thought. © 2015

  5. Characterizing the Meso-scale Plasma Flows in Earth's Coupled Magnetosphere-Ionosphere-Thermosphere System

    Science.gov (United States)

    Gabrielse, C.; Nishimura, T.; Lyons, L. R.; Gallardo-Lacourt, B.; Deng, Y.; McWilliams, K. A.; Ruohoniemi, J. M.

    2017-12-01

    NASA's Heliophysics Decadal Survey put forth several imperative, Key Science Goals. The second goal communicates the urgent need to "Determine the dynamics and coupling of Earth's magnetosphere, ionosphere, and atmosphere and their response to solar and terrestrial inputs...over a range of spatial and temporal scales." Sun-Earth connections (called Space Weather) have strong societal impacts because extreme events can disturb radio communications and satellite operations. The field's current modeling capabilities of such Space Weather phenomena include large-scale, global responses of the Earth's upper atmosphere to various inputs from the Sun, but the meso-scale ( 50-500 km) structures that are much more dynamic and powerful in the coupled system remain uncharacterized. Their influences are thus far poorly understood. We aim to quantify such structures, particularly auroral flows and streamers, in order to create an empirical model of their size, location, speed, and orientation based on activity level (AL index), season, solar cycle (F10.7), interplanetary magnetic field (IMF) inputs, etc. We present a statistical study of meso-scale flow channels in the nightside auroral oval and polar cap using SuperDARN. These results are used to inform global models such as the Global Ionosphere Thermosphere Model (GITM) in order to evaluate the role of meso-scale disturbances on the fully coupled magnetosphere-ionosphere-thermosphere system. Measuring the ionospheric footpoint of magnetospheric fast flows, our analysis technique from the ground also provides a 2D picture of flows and their characteristics during different activity levels that spacecraft alone cannot.

  6. Setting Healthcare Priorities at the Macro and Meso Levels: A Framework for Evaluation

    Science.gov (United States)

    Barasa, Edwine W.; Molyneux, Sassy; English, Mike; Cleary, Susan

    2015-01-01

    Background: Priority setting in healthcare is a key determinant of health system performance. However, there is no widely accepted priority setting evaluation framework. We reviewed literature with the aim of developing and proposing a framework for the evaluation of macro and meso level healthcare priority setting practices. Methods: We systematically searched Econlit, PubMed, CINAHL, and EBSCOhost databases and supplemented this with searches in Google Scholar, relevant websites and reference lists of relevant papers. A total of 31 papers on evaluation of priority setting were identified. These were supplemented by broader theoretical literature related to evaluation of priority setting. A conceptual review of selected papers was undertaken. Results: Based on a synthesis of the selected literature, we propose an evaluative framework that requires that priority setting practices at the macro and meso levels of the health system meet the following conditions: (1) Priority setting decisions should incorporate both efficiency and equity considerations as well as the following outcomes; (a) Stakeholder satisfaction, (b) Stakeholder understanding, (c) Shifted priorities (reallocation of resources), and (d) Implementation of decisions. (2) Priority setting processes should also meet the procedural conditions of (a) Stakeholder engagement, (b) Stakeholder empowerment, (c) Transparency, (d) Use of evidence, (e) Revisions, (f) Enforcement, and (g) Being grounded on community values. Conclusion: Available frameworks for the evaluation of priority setting are mostly grounded on procedural requirements, while few have included outcome requirements. There is, however, increasing recognition of the need to incorporate both consequential and procedural considerations in priority setting practices. In this review, we adapt an integrative approach to develop and propose a framework for the evaluation of priority setting practices at the macro and meso levels that draws from these

  7. Setting Healthcare Priorities at the Macro and Meso Levels: A Framework for Evaluation

    Directory of Open Access Journals (Sweden)

    Edwine W. Barasa

    2015-11-01

    Full Text Available Background Priority setting in healthcare is a key determinant of health system performance. However, there is no widely accepted priority setting evaluation framework. We reviewed literature with the aim of developing and proposing a framework for the evaluation of macro and meso level healthcare priority setting practices. Methods We systematically searched Econlit, PubMed, CINAHL, and EBSCOhost databases and supplemented this with searches in Google Scholar, relevant websites and reference lists of relevant papers. A total of 31 papers on evaluation of priority setting were identified. These were supplemented by broader theoretical literature related to evaluation of priority setting. A conceptual review of selected papers was undertaken. Results Based on a synthesis of the selected literature, we propose an evaluative framework that requires that priority setting practices at the macro and meso levels of the health system meet the following conditions: (1 Priority setting decisions should incorporate both efficiency and equity considerations as well as the following outcomes; (a Stakeholder satisfaction, (b Stakeholder understanding, (c Shifted priorities (reallocation of resources, and (d Implementation of decisions. (2 Priority setting processes should also meet the procedural conditions of (a Stakeholder engagement, (b Stakeholder empowerment, (c Transparency, (d Use of evidence, (e Revisions, (f Enforcement, and (g Being grounded on community values. Conclusion Available frameworks for the evaluation of priority setting are mostly grounded on procedural requirements, while few have included outcome requirements. There is, however, increasing recognition of the need to incorporate both consequential and procedural considerations in priority setting practices. In this review, we adapt an integrative approach to develop and propose a framework for the evaluation of priority setting practices at the macro and meso levels that draws from

  8. Copepod faecal pellet transfer through the meso- and bathypelagic layers in the Southern Ocean in spring

    Science.gov (United States)

    Belcher, Anna; Manno, Clara; Ward, Peter; Henson, Stephanie A.; Sanders, Richard; Tarling, Geraint A.

    2017-03-01

    The faecal pellets (FPs) of zooplankton can be important vehicles for the transfer of particulate organic carbon (POC) to the deep ocean, often making large contributions to carbon sequestration. However, the routes by which these FPs reach the deep ocean have yet to be fully resolved. We address this by comparing estimates of copepod FP production to measurements of copepod FP size, shape, and number in the upper mesopelagic (175-205 m) using Marine Snow Catchers, and in the bathypelagic using sediment traps (1500-2000 m). The study is focussed on the Scotia Sea, which contains some of the most productive regions in the Southern Ocean, where epipelagic FP production is likely to be high. We found that, although the size distribution of the copepod community suggests that high numbers of small FPs are produced in the epipelagic, small FPs are rare in the deeper layers, implying that they are not transferred efficiently to depth. Consequently, small FPs make only a minor contribution to FP fluxes in the meso- and bathypelagic, particularly in terms of carbon. The dominant FPs in the upper mesopelagic were cylindrical and elliptical, while ovoid FPs were dominant in the bathypelagic. The change in FP morphology, as well as size distribution, points to the repacking of surface FPs in the mesopelagic and in situ production in the lower meso- and bathypelagic, which may be augmented by inputs of FPs via zooplankton vertical migrations. The flux of carbon to the deeper layers within the Southern Ocean is therefore strongly modulated by meso- and bathypelagic zooplankton, meaning that the community structure in these zones has a major impact on the efficiency of FP transfer to depth.

  9. 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

  10. Porous media geometry and transports

    CERN Document Server

    Adler, Pierre

    1992-01-01

    The goal of ""Porous Media: Geometry and Transports"" is to provide the basis of a rational and modern approach to porous media. This book emphasizes several geometrical structures (spatially periodic, fractal, and random to reconstructed) and the three major single-phase transports (diffusion, convection, and Taylor dispersion).""Porous Media"" serves various purposes. For students it introduces basic information on structure and transports. Engineers will find this book useful as a readily accessible assemblage of al the major experimental results pertaining to single-phase tr

  11. The synthesis, characterization, crystal structure and theoretical calculations of a new meso-BOBIPY substituted phthalonitrile

    International Nuclear Information System (INIS)

    Sen, Pinar; Yildiz, S. Zeki; Atalay, Yusuf; Dege, Necmi; Demirtas, Günes

    2014-01-01

    A novel 4-(2-meso-BOBIPY-phenoxy)phthalonitrile (6) derivative has been synthesized starting from BF 3 –OEt 2 complex and 4-(2-meso-dipyrromethene-phenoxy)phthalonitrile (5) which was prepared by the oxidation of 4-(2-meso-dipyrromethane-phenoxy)phthalonitrile (4). The final product exhibit noticeable spectroscopic properties which were examined by its absorption and fluorescence emission spectra. The original compounds prepared in the reaction pathway were characterized by the combination of FT-IR, 1 H and 13 C NMR, UV–vis, MS and HRMS spectral data. The final product (6) was obtained as single crystal which crystallized in the triclinic space group P-1 with a=7.9411 (6) Å, b=9.0150 (6) Å, c=14.419 (1) Å, α=74.917 (5)°, β=86.824 (6)°, γ=84.109 (5)° and Z=2. The crystal structure has intermolecular C–H···F–B and C–H···N interactions. These interactions construct bifurcated hydrogen bonds in the crystal structure. In this study, It has been calculated; molecular structure, vibrational frequencies, 1 H and 13 C NMR chemical shifts and HOMO and LUMO energies of the title compound by using B3LYP method with 6–311++G(dp) basis set, and the electronic spectral characterization was investigated for the target product, as well. - Highlights: • A novel 4-(2-meso-BOBIPY-phenoxy)phthalonitrile derivative has been synthesized. • The title product exhibit noticeable spectroscopic properties which were examined by its absorption and fluorescence emission spectra. • The final product (6) was obtained as single crystal which crystallized in the triclinic space group. • Molecular structure, vibrational frequencies, 1 H and 13 C NMR chemical shifts and HOMO and LUMO energies of the title compound were calculated theoretically. • The electronic spectral characterization was investigated, as well. • The title compound is also open to prepare further BODIPY substituted oligomeric molecules via on it

  12. Synthesis of a Phlorin from a Meso-Fused Anthriporphyrin by a Diels-Alder Strategy.

    Science.gov (United States)

    Aslam, Adil S; Hong, Jung-Ho; Shin, June-Ho; Cho, Dong-Gyu

    2017-12-18

    An anthracene-containing meso-fused carbaporphyrin, which has extended π-conjugation pathways as compared to the corresponding naphthalene-containing carbaporphyrin, has been synthesized. The weak global aromaticity of the anthriporphyrin also allowed its use as the diene for a Diels-Alder reaction with dimethyl acetylenedicarboxylate (DMAD). The resulting phlorin contains an interesting bicyclic structure. Moreover, to the best of our knowledge, this phlorin is the first Diels-Alder adduct of a diene forming part of the global π-conjugation pathway of an aromatic porphyrinoid. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Towards meso -Ester BODIPYs with Aggregation-Induced Emission Properties: The Effect of Substitution Positions

    KAUST Repository

    Chua, Ming Hui; Ni, Yong; Garai, Monalisa; Zheng, Bin; Huang, Kuo-Wei; Xu, Qing Hua; Xu, Jianwei; Wu, Jishan

    2015-01-01

    Three meso-ester boron dipyrromethene (BODIPY) dyes have been synthesized and functionalized with aggregation-induced emission (AIE)-active tetraphenylethene or triphenylethene moieties. It was found that functionalizing at the different positions of the BODIPY core resulted in the final dye having different emission properties in response to aggregation: from aggregation-induced quenching (ACQ) to being AIE active. X-ray crystallographic analysis was thus performed to provide an explanation for these differences. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. In meso in situ serial X-ray crystallography of soluble and membrane proteins

    International Nuclear Information System (INIS)

    Huang, Chia-Ying; Olieric, Vincent; Ma, Pikyee; Panepucci, Ezequiel; Diederichs, Kay; Wang, Meitian; Caffrey, Martin

    2015-01-01

    A method for performing high-throughput in situ serial X-ray crystallography with soluble and membrane proteins in the lipid cubic phase is described. It works with microgram quantities of protein and lipid (and ligand when present) and is compatible with the most demanding sulfur SAD phasing. The lipid cubic phase (LCP) continues to grow in popularity as a medium in which to generate crystals of membrane (and soluble) proteins for high-resolution X-ray crystallographic structure determination. To date, the PDB includes 227 records attributed to the LCP or in meso method. Among the listings are some of the highest profile membrane proteins, including the β 2 -adrenoreceptor–G s protein complex that figured in the award of the 2012 Nobel Prize in Chemistry to Lefkowitz and Kobilka. The most successful in meso protocol to date uses glass sandwich crystallization plates. Despite their many advantages, glass plates are challenging to harvest crystals from. However, performing in situ X-ray diffraction measurements with these plates is not practical. Here, an alternative approach is described that provides many of the advantages of glass plates and is compatible with high-throughput in situ measurements. The novel in meso in situ serial crystallography (IMISX) method introduced here has been demonstrated with AlgE and PepT (alginate and peptide transporters, respectively) as model integral membrane proteins and with lysozyme as a test soluble protein. Structures were solved by molecular replacement and by experimental phasing using bromine SAD and native sulfur SAD methods to resolutions ranging from 1.8 to 2.8 Å using single-digit microgram quantities of protein. That sulfur SAD phasing worked is testament to the exceptional quality of the IMISX diffraction data. The IMISX method is compatible with readily available, inexpensive materials and equipment, is simple to implement and is compatible with high-throughput in situ serial data collection at macromolecular

  15. Development of a Meso-Scale Fiberoptic Rotation Sensor for a Torsion Actuator.

    Science.gov (United States)

    Sheng, Jun; Desai, Jaydev P

    2018-01-01

    This paper presents the development of a meso-scale fiberoptic rotation sensor for a shape memory alloy (SMA) torsion actuator for neurosurgical applications. Within the sensor, a rotary head with a reflecting surface is capable of modulating the light intensity collected by optical fibers when the rotary head is coupled to the torsion actuator. The mechanism of light intensity modulation is modeled, followed by experimental model verification. Meanwhile, working performances for different rotary head designs, optical fibers, and fabrication materials are compared. After the calibration of the fiberoptic rotation sensor, the sensor is capable of precisely measuring rotary motion and controlling the SMA torsion actuator with feedback control.

  16. Towards meso -Ester BODIPYs with Aggregation-Induced Emission Properties: The Effect of Substitution Positions

    KAUST Repository

    Chua, Ming Hui

    2015-06-17

    Three meso-ester boron dipyrromethene (BODIPY) dyes have been synthesized and functionalized with aggregation-induced emission (AIE)-active tetraphenylethene or triphenylethene moieties. It was found that functionalizing at the different positions of the BODIPY core resulted in the final dye having different emission properties in response to aggregation: from aggregation-induced quenching (ACQ) to being AIE active. X-ray crystallographic analysis was thus performed to provide an explanation for these differences. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. meso-Substituted bisanthenes as soluble and stable near-infrared dyes

    KAUST Repository

    Li, Jinling

    2010-02-05

    (Chemical Equation Presented) Three meso-substituted bisanthenes, 4-6, were prepared in a short synthetic route from the bisanthenequinone. They exhibit largely improved stability and solubility in comparison to the parent bisanthene. All of these compounds also show near-infrared (NIR) absorption and emission with high to moderate fluorescence quantum yields. Amphoteric redox behavior was observed for 4-6 by cyclic voltammetry, and these compounds can be reversibly oxidized and reduced into respective cationic and anionic species by both electrochemical and chemical processes. In addition, compound 5 adopts a herringbone π-stacking motif in the single crystal. © 2010 American Chemical Society.

  18. Meso-structures of dynamical chaos and E-infinity theory

    International Nuclear Information System (INIS)

    Mukhamedov, A.M.

    2009-01-01

    A novel proposal is made to develop a unified theory of dynamical chaos using an idea of extra-coordinates. It is supposed that chaos is capable to translate influences from quantum level of description to the classical macroscopic one and vise versa. The notion of macroscopically prepared microstates is proposed to determine a special case of extra-coordinates induced by cooperative effects at quantum resolution of dynamical events. Meso-structures mediating quantum and classical appearances of chaotic motion are studied in the light of E-infinity theory.

  19. Isoporphyrin intermediate in heme oxygenase catalysis. Oxidation of alpha-meso-phenylheme.

    Science.gov (United States)

    Evans, John P; Niemevz, Fernando; Buldain, Graciela; de Montellano, Paul Ortiz

    2008-07-11

    Human heme oxygenase-1 (hHO-1) catalyzes the O2- and NADPH-dependent oxidation of heme to biliverdin, CO, and free iron. The first step involves regiospecific insertion of an oxygen atom at the alpha-meso carbon by a ferric hydroperoxide and is predicted to proceed via an isoporphyrin pi-cation intermediate. Here we report spectroscopic detection of a transient intermediate during oxidation by hHO-1 of alpha-meso-phenylheme-IX, alpha-meso-(p-methylphenyl)-mesoheme-III, and alpha-meso-(p-trifluoromethylphenyl)-mesoheme-III. In agreement with previous experiments (Wang, J., Niemevz, F., Lad, L., Huang, L., Alvarez, D. E., Buldain, G., Poulos, T. L., and Ortiz de Montellano, P. R. (2004) J. Biol. Chem. 279, 42593-42604), only the alpha-biliverdin isomer is produced with concomitant formation of the corresponding benzoic acid. The transient intermediate observed in the NADPH-P450 reductase-catalyzed reaction accumulated when the reaction was supported by H2O2 and exhibited the absorption maxima at 435 and 930 nm characteristic of an isoporphyrin. Product analysis by reversed phase high performance liquid chromatography and liquid chromatography electrospray ionization mass spectrometry of the product generated with H2O2 identified it as an isoporphyrin that, on quenching, decayed to benzoylbiliverdin. In the presence of H218O2, one labeled oxygen atom was incorporated into these products. The hHO-1-isoporphyrin complexes were found to have half-lives of 1.7 and 2.4 h for the p-trifluoromethyl- and p-methyl-substituted phenylhemes, respectively. The addition of NADPH-P450 reductase to the H2O2-generated hHO-1-isoporphyrin complex produced alpha-biliverdin, confirming its role as a reaction intermediate. Identification of an isoporphyrin intermediate in the catalytic sequence of hHO-1, the first such intermediate observed in hemoprotein catalysis, completes our understanding of the critical first step of heme oxidation.

  20. Pore-Confined Carriers and Biomolecules in Mesoporous Silica for Biomimetic Separation and Targeting

    Science.gov (United States)

    Zhou, Shanshan

    Selectively permeable biological membranes composed of lipophilic barriers inspire the design of biomimetic carrier-mediated membranes for aqueous solute separation. This work imparts selective permeability to lipid-filled pores of silica thin film composite membranes using carrier molecules that reside in the lipophilic self-assemblies. The lipids confined inside the pores of silica are proven to be a more effective barrier than bilayers formed on the porous surface through vesicle fusion, which is critical for quantifying the function of an immobilized carrier. The ability of a lipophilic carrier embedded in the lipid bilayer to reversibly bind the target solute and transport it through the membrane is demonstrated. Through the functionalization of the silica surface with enzymes, enzymatic catalysis and biomimetic separations can be combined on this nanostructured composite platform. The successful development of biomimetic nanocomposite membrane can provide for efficient dilute aqueous solute upgrading or separations using engineered carrier/catalyst/support systems. While the carrier-mediated biomimetic membranes hold great potential, fully understanding of the transport processes in composite synthetic membranes is essential for improve the membrane performance. Electrochemical impedance spectroscopy (EIS) technique is demonstrated to be a useful tool for characterizing the thin film pore accessibility. Furthermore, the effect of lipid bilayer preparation methods on the silica thin film (in the form of pore enveloping, pore filling) on ion transport is explored, as a lipid bilayer with high electrically insulation is essential for detecting activity of proteins or biomimetic carriers in the bilayer. This study provides insights for making better barriers on mesoporous support for carrier-mediated membrane separation process. Porous silica nanoparticles (pSNPs) with pore sizes appropriate for biomolecule loading are potential for encapsulating dsRNA within the