Surface Modification, Characterization and Photocatalytic Performance of Nano-Sized Titania Modified with Silver and Bentonite Clay

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Neetu Divya

2009-12-01

Full Text Available In many textile industries dyes are used as coloring agents. Advanced oxidation processes are used for degrading or removing color from dye baths. Catalysts play a key role in these industries for the treatment of water. Solid catalysts are usually composed of metals that form supports onto the surface and create metal particles with high surface areas. TiO2 composites containing transition metal ions (silver and/or bentonite clay were prepared. Photocatalytic efficiencies have been investigated for the degradation of Orange G an azo dye. Various analytical techniques were used to characterize the surface properties of nano-sized titania modified using silver and/or bentonite clay. Scanning electron microscopy (SEM, Transmission electron microscopy (TEM, X-ray diffraction (XRD and FTIR analyses showed that TiO2 (10 ± 2 nm and Ag (2 to 3 nm particles were supported on the surface of the bentonite clay and the size was in the range of 100 ± 2 nm. The modified catalysts P-25 TiO2/Bentonite/Ag and P-25 TiO2/Ag were found to be very active for the photocatalytic decomposition of Orange G. The percent decolorization in 60 min was 98% with both P-25 TiO2/Ag and P-25 TiO2/Bentonite/Ag modified catalysts. Whereas mineralization achieved in 9 hr were 68% and 71% with P-25 TiO2/Bentonite/Ag and P-25 TiO2/Ag catalyst respectively. © 2009 BCREC UNDIP. All rights reserved[Received: 30 October 2009, Revised: 20 November 2009, Accepted: 21 November 2009][How to Cite: N. Divya, A. Bansal, A. K. Jana. (2009. Surface Modification, Characterization and Photocatalytic Performance of Nano-Sized Titania Modified with Silver and Bentonite Clay. Bulletin of Chemical Reaction Engineering and Catalysis, 4(2: 43-53.  doi:10.9767/bcrec.4.2.1249.43-53][How to Link/ DOI: http://dx.doi.org/10.9767/bcrec.4.2.1249.43-53 || or local: http://ejournal.undip.ac.id/index.php/bcrec/article/view/1249

Preparation of Al/Fe-Pillared Clays: Effect of the Starting Mineral.

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Muñoz, Helir-Joseph; Blanco, Carolina; Gil, Antonio; Vicente, Miguel-Ángel; Galeano, Luis-Alejandro

2017-11-28

Four natural clays were modified with mixed polyoxocations of Al/Fe for evaluating the effect of the physicochemical properties of the starting materials (chemical composition, abundance of expandable clay phases, cationic exchange capacity and textural properties) on final physicochemical and catalytic properties of Al/Fe-PILCs. The aluminosilicate denoted C2 exhibited the highest potential as starting material in the preparation of Al/Fe-PILC catalysts, mainly due to its starting cationic exchange capacity (192 meq/100 g) and the dioctahedral nature of the smectite phase. These characteristics favored the intercalation of the mixed (Al 13- x /Fe x ) 7+ Keggin-type polyoxocations, stabilizing a basal spacing of 17.4 Å and high increase of the BET surface (194 m²/g), mainly represented in microporous content. According to H₂-TPR analyses, catalytic performance of the incorporated Fe in the Catalytic Wet Peroxide Oxidation (CWPO) reaction strongly depends on the level of location in mixed Al/Fe pillars. Altogether, such physicochemical characteristics promoted high performance in CWPO catalytic degradation of methyl orange in aqueous medium at very mild reaction temperatures (25.0 ± 1.0 °C) and pressure (76 kPa), achieving TOC removal of 52% and 70% of azo-dye decolourization in only 75 min of reaction under very low concentration of clay catalyst (0.05 g/L).

Transition metal modified and partially calcined inorganic-organic pillared clays for the adsorption of salicylic acid, clofibric acid, carbamazepine, and caffeine from water.

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Cabrera-Lafaurie, Wilman A; Román, Félix R; Hernández-Maldonado, Arturo J

2012-11-15

Pharmaceutical and Personal Care Products (PPCPs) are considered emerging contaminants, and their efficient removal from water is going to be a challenging endeavor. Microporous adsorbent materials, including pillared clays, could offer a potential solution if tailored properly. Although pillared clays have been employed previously for the removal of organics, the effective removal of PPCPs will only be possible if their surface and textural properties are manipulated from the bottom-up. This work presents the use of modified inorganic-organic pillared clays (IOCs) for the adsorption of salicylic acid, clofibric acid, carbamazepine, and caffeine. The IOCs have been modified with Co(2+), Cu(2+), or Ni(2+) to induce complexation-like adsorbate-adsorbent interactions at ambient conditions, in an attempt to provide an efficient and yet reversible driving force in the sub-ppm concentration range. Furthermore, the IOCs were partially calcined to increase effective surface area by an order of magnitude while preserving some hydrophobicity. In general, the Ni(2+) IOCs exhibited the greatest interaction with salicylic and clofibric acids, respectively, while the Co(2+) adsorbents excelled at adsorbing caffeine at low concentrations. All of the metal-modified IOCs showed comparable adsorption capacities for the case of carbamazepine, probably due to the lack of availability of particular functional groups in this adsorbate. Copyright © 2012 Elsevier Inc. All rights reserved.

THE SYNTHESIS OF Cr2O3-PILLARED MONTMORILLONITE (CrPM AND ITS USAGE FOR HOST MATERIAL OF p-NITROANILINE

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Karna Wijaya

2010-06-01

Full Text Available The synthesis of Cr2O3-pillared montmorillonite (CrPM and its usage for host material of p-nitroaniline have been conducted. The Cr2O3-pillared montmorillonite clays was prepared by a direct ion exchange method. First, the polyhydroxychromium as a pillaring spesies was intercalated into the interlayer region of the montmorillonite clays (purified clay in the monocation form, result in a montmorillonite-polyoxychromium intercalation compound. The precursors/pillaring spesies was not stable, hence it must be stabilized by calcination in order to transform the polyoxychromium via dehydration and dehydroxylation processes into Cr2O3. This oxide constituts the so-called pillar that prop the clay layers apart to a relatively large distance. The Cr2O3-pillared clays as a host material was added into ethanol solution saturated with p-nitroaniline, and mixture was stirred for 24 h at room temperature. The Na-montmorillonite, Cr2O3-pillared clay and p-nitroaniline-Cr2O3-pillared clay (pNA-CrPM were characterized by X-Ray Diffraction (XRD, Gas Sorption Analysis, Infrared Spectroscopy (FTIR and Activated Neutron Analysis (ANA methods. The result of research showed that basal spacing (d001 of Cr2O3-pillared montmorillonite (CrPM was 18,55 Å, meanwhile the basal spacing of the hydrated Na-montmorillonite was 14,43 Å. The specific surface area of the Cr2O3-pillared montmorillonite was 174,308 m2/g, whereas p-nitroaniline-Cr2O3-pillared clay (pNA-CrPM was 133,331641 m2/g. This fact indicated that p-nitroaniline has been included into the pore of the Cr2O3-pillared clay.   Keyword: montmorillonite, pillared-clay, ion exchange, intercalate.

Study of colloidal properties of natural and Al-pillared smectite and removal of copper ions from an aqueous solution.

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Sartor, Lucas Resmini; de Azevedo, Antonio Carlos; Andrade, Gabriel Ramatis Pugliese

2015-01-01

In this study, an Al-pillared smectite was synthesized and changes in its colloidal properties were investigated. The pillaring solution was prepared by mixing 0.4 mol L(-1) NaOH and 0.2 mol L(-1) AlCl3.6H2O solutions. Intercalated clays were heated to obtain the pillared clay, and X-ray diffractometry (XRD), X-ray fluorescence (XRF), Fourier transform infrared (FTIR) spectroscopy and N2 sorption/desorption isotherms analysis were done to characterize the changes in clay properties. Moreover, adsorption experiments were carried out in order to evaluate the capacity of the pillared clays to remove Cu2+ from an aqueous solution and to characterize the interaction between adsorbent and adsorbate. The results indicate that the natural clay has a basal spacing of 1.26 nm, whereas the pillared clays reached 1.78 nm (500°C) and 1.80 nm (350°C) after calcination. XRF analysis revealed an increase in the Al3+ in the pillared clay as compared to the natural clay. The surface area and pore volume (micro and mesoporous) were higher for the pillared clays. Experimental data from the adsorption experiment were fit to Langmuir and Freundlich and Temkin adsorption models, and the former one was the best fit (highest r2 value) for all the clays and lower standard deviation (Δg%) for the natural clay. On the other hand, the Temkin model exhibited Δg% value lower for the pillared clays. Thermodynamics parameters demonstrate that the Cu2+ adsorption process is spontaneous for all the clays, but with higher values for the pillared materials. In addition, application of the Dubinin-Radushkevich model revealed that the bond between the metal and the clay are weak, characterizing a physisorption.

Preparation, characterization and application in deep catalytic ODS of the mesoporous silica pillared clay incorporated with phosphotungstic acid.

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Li, Baoshan; Liu, Zhenxing; Liu, Jianjun; Zhou, Zhiyuan; Gao, Xiaohui; Pang, Xinmei; Sheng, Huiting

2011-10-15

Mesoporous silica pillared clay (SPC) materials with different contents of H(3)PW(12)O(40) (HPW) heteropoly acid were synthesized by introducing HPW into clay interlayer template in an acidic suspension using sol-gel method. Samples with similar HPW loadings were also prepared by impregnation method using SPC as the support. The results of the characterizations showed that HPW was dispersed more homogeneously in the encapsulated samples than in the impregnated samples. The encapsulated materials exhibited better catalytic performance than the impregnated samples in oxidative desulfurization of dibenzothiophene-containing model oil. The sulfur removal reached up to 98.6% for the model oil under the experiential conditions. Copyright © 2011 Elsevier Inc. All rights reserved.

Modification of Colombian clays with pillars mixed Al-Fe and their evaluation in the catalytic oxidation of phenol in diluted watery solution

International Nuclear Information System (INIS)

Galeano, Luis A; Moreno G, Sonia

2002-01-01

The environmental legislation has become in the last time particularly restrictive with the bio-recalcitrant pollutants manage in the wastewaters. The pillared clays show great versatility to adjust at demands of the environmental reactions. Present study show that is achieve the modification of starting Colombian clays with precursor solutions of Al-Fe mixed pillars, and is found an excellent performance of them in the catalytic oxidation of aqueous solutions with middle contents of Total Organic Carbon TOC (36 mg C/L). The materials prepared in this way reached quantitative conversion of phenol, as model pollutant, in 2 hours of reaction at 20 Celsius degrade and atmospheric pressure; in 4 hours of reaction, the removal reached 62% of TOC in the solution yielding light carboxylic acids as main byproducts, although that CO 2 . The materials are stable under strongly oxidation media of reaction, and the iron leached in the effluent is close to 0,2 mg/L for the material of better catalytic performance

Pilarização de esmectita brasileira para fins catalíticos. Emprego de argila pilarizada na alquilação de benzeno com 1-dodeceno Pillarization of Brazilian smectite for the catalytic of purpose. Use of pillared clay in the alkylation of benzene with 1-dodecene

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Sidnei Quezada M. Leite

2000-04-01

Full Text Available Al-pillared clay was prepared with a Brazilian bentonite from the Campina Grande region (Paraíba, BRAZIL. It was intercalated at 298 K, during 48 hours, with a solution containing [Al3+] = 0.10 mol/L and molar ratio OH/Al = 2.0 prepared at 333 K, and was calcined at 773K. The catalytic activity was evaluated by alkylation of benzene with 1-dodecene. The characterization methods were: X-ray fluorescence and diffraction analysis; 27Al, 29Si and 23Na MAS NMR and textural analysis by N2 adsorption. The thermal stability of the natural clay was improved by the pillaring procedure, as well as the catalytic activity. The intercalated clay presented the highest initial rate of reaction among the systems tested.

Preliminary creep and pillar closure data for shales

International Nuclear Information System (INIS)

Lomenick, T.F.; Russell, J.E.

1987-10-01

The results of fourteen laboratory creep tests on model pillars of four different shales are reported. Initial pillar stresses range from 6.9 MPa (1000 psi) to 69 MPa (10,000 psi) and temperatures range from ambient to 100 0 C. Laboratory response data are used to evaluate the parameters in the transient power-law pillar closure equation similar to that previously used for model pillars of rock salt. The response of the model pillars of shale shows many of the same characteristics as for rock salt. Deformation is enhanced by higher stresses and temperatures, although the shale pillars are not as sensitive to either stress or temperature as are pillars of rock salt. These test results must be considered very preliminary since they represent the initial, or scoping, phase of a comprehensive model pillar test program that will lead to the development and validation of creep laws for clay-rich rocks. 11 refs., 9 figs., 7 tabs

Hybrids of ethylene vinyl acetate with Na-montmorillonite and titania: preparation and characterization

International Nuclear Information System (INIS)

Ashfaq, M.

2010-01-01

Hybrids of Ethylene vinyl acetate (EVA) with Na-montmorillonite and titania were formed. Montmorillonite was organically modified by two different modifiers: Pyridinium ions and 4. 4-oxydianilinium ions. X-ray diffraction results revealed that Pyridinium ions increased the .interlayer spacing by 0.33 nm and 4, 4-oxydianilinium by 0.55 nm approximately. These modified organo-clays were successfully exfoliated in EVA using melt blending. These hybrids showed improvement in mechanical and thermal properties. 4, 4-oxydianilinium ions were degraded at higher temperature due to which thermal degradation was enhanced in EVA. In addition to this, EVA/titania hybrids were also prepared using sot-gel technique and modified by triethoxy vinyl silane and (3-aminopropyI)- triethoxy silane to increase their compatibility with EVA. Some portion of unmodified titania was heat treated to 600 degree C to obtain particulate titania. The hybrid of particulate titania and modified titania improved the mechanical properties and thermal properties. Especially in case of modified titania toughness was almost doubled. (author)

Effect of ultrasound on the structural and textural properties of copper-impregnated cerium-modified zirconium-pillared bentonite

International Nuclear Information System (INIS)

Tomul, Fatma

2011-01-01

In this study, the synthesis of zirconium-pillared bentonite modified with cerium was performed via two different methods by the application of conventional and ultrasonic treatments during the intercalation stage. To synthesise copper-impregnated pillared clays by wet impregnation, cerium-modified zirconium-pillared clays were used as supportive materials after being calcined at 300 °C. Ultrasonic treatment significantly decreased the required processing time compared with the conventional treatment of the synthesised pillared bentonites. Chemical analysis confirmed the incorporation of Zr 4+ , Ce 4+ and Cu 2+ species into the pillared bentonites. X-ray diffraction (XRD) patterns of zirconium- and cerium/zirconium-pillared bentonites prepared by conventional treatment show that one large d-spacing above 3.5 nm corresponds to the mesoporous delaminated part, and another small d-spacing above 1.7 nm is indicative of the microporous pillared part. Zirconium- and cerium/zirconium-pillared bentonites prepared via ultrasonic treatment exhibited similar results, with the same high d-spacing but with a second low-intensity d-spacing above 1.9 nm. The delaminated structures of the pillared bentonites synthesised by both methods were conserved after copper impregnation. Nitrogen-adsorption isotherm analysis showed that the textural characteristics of products synthesised by ultrasonic treatment were comparable to those of products synthesised by conventional treatment. Fourier-transform infrared spectroscopy (FTIR) analyses showed the presence of Brønsted- and Lewis-acid sites, and zirconium-pillared clays synthesised by conventional treatment exhibited increased numbers of Brønsted- and Lewis-acid sites after cerium addition and copper impregnation. However, the products synthesised by ultrasonic treatment exhibited an increased number of Brønsted- and Lewis-acid sites after cerium addition, but a decreased number of acid sites after copper impregnation.

PREPARATION AND CATALYTIC ACTIVITY FOR ISOPROPYL BENZENE CRACKING OF Co, Mo AND Co/Mo-Al2O3-PILLARED MONTMORILLONITE CATALYSTS

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Hasanudin Hasanudin

2010-06-01

Full Text Available It has been prepared Co, Mo and Co/Mo-Al2O3-pillared montmorillonite catalysts using montmorillonite clay  as raw material. The structure and porosity of the catalysts were determined using N2 adsorption-desorption and FT-IR spectroscopy analysis methods. Isopropyl benzene cracking using these catalysts were used to test the catalytic activity and performance of Co, Mo and Co/Mo-Al2O3-pillared montmorillonites.  Characterization results showed that pillarization resulted in the increase of the total pore volume and specific surface area of the clay. Meanwhile, transition metals (Co, Mo and Co/Mo loaded on Al2O3-pillared monmorillonites could increase the catalytic activity of the catalysts for isopropyl benzene cracking significantly.   Keywords: pillared monmorillonite, isopropyl benzene  and cracking catalyst

Retention of contaminants Cd and Hg adsorbed and intercalated in aluminosilicate clays: A first principles study

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Crasto de Lima, F. D.; Miwa, R. H.; Miranda, Caetano R.

2017-11-01

Layered clay materials have been used to incorporate transition metal (TM) contaminants. Based on first-principles calculations, we have examined the energetic stability and the electronic properties due to the incorporation of Cd and Hg in layered clay materials, kaolinite (KAO) and pyrophyllite (PYR). The TM can be (i) adsorbed on the clay surface as well as (ii) intercalated between the clay layers. For the intercalated case, the contaminant incorporation rate can be optimized by controlling the interlayer spacing of the clay, namely, pillared clays. Our total energy results reveal that the incorporation of the TMs can be maximized through a suitable tuning of vertical distance between the clay layers. Based on the calculated TM/clay binding energies and the Langmuir absorption model, we estimate the concentrations of the TMs. Further kinetic properties have been examined by calculating the activation energies, where we found energy barriers of ˜20 and ˜130 meV for adsorbed and intercalated cases, respectively. The adsorption and intercalation of ionized TM adatoms were also considered within the deprotonated KAO surface. This also leads to an optimal interlayer distance which maximizes the TM incorporation rate. By mapping the total charge transfers at the TM/clay interface, we identify a net electronic charge transfer from the TM adatoms to the topmost clay surface layer. The effect of such a charge transfer on the electronic structure of the clay (host) has been examined through a set of X-ray absorption near edge structure (XANES) simulations, characterizing the changes of the XANES spectra upon the presence of the contaminants. Finally, for the pillared clays, we quantify the Cd and Hg K-edge energy shifts of the TMs as a function of the interlayer distance between the clay layers and the Al K-edge spectra for the pristine and pillared clays.

Environmental Remediation and Sorption of Metal Cations Using Aluminum Pillared Nano-Bentonite

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Rifai, Rifai; Abou El Safa, Magda

2015-04-01

The release of heavy metal cations into the environment is a potential threat to water and soil quality. Some clay minerals play an important role, as physical and chemical barriers, for the isolation of metal-rich wastes and to adsorb heavy metals as well as to avoid their environmental dispersion. In the present study, the bentonitic clay (southeast El-Hammam City, Egypt) was subjected to pillaring using hydroxyl-aluminum solution. The XRD patterns of the Aluminum Pillared Nano-Bentonite (APNB) showed severe alteration of the crystal structure after pillaring. Poly metal solutions with different metal concentrations of Cu, Co, Ni, Zn, Cd and Pb (0.001, 0.005 and 0.01 moles), and pH (1, 2.5, 5 and 6) were subjected to treatment by the APNB. The removal process is very rapid and spontaneous and the contact time may be short (several minutes) for most adsorption to occur. The criterion for environmental remediation of APNB is less stringent and a short contact time is sufficient. The rate of Cu2+, Zn2+, Co2+, Cd2+, Ni2+ and Pb2+sorption remained higher or equal to the CEC. The sorption of metal ions by APNB are complex and probably involve several mechanisms. In general, APNB can be used to immobilize Cu2+, Zn2+, Co2+, Cd2+, Ni2+ and Pb2+ to any extent. For each metal ion, the most effective immobilization occurs over a particular pH around 5. According to the experimental data obtained, the uptake amount of the studied cations by APNB increased with increasing solution pH, sorbent dose and contact time. The preference of the APNB adsorption for heavy metal ions that are through the cation exchange processes decreases in the order: Cu2+>Zn2+>Co2+>Cd2+ >Ni2+ >Pb2+. Keywords: Bentonitic clay, Egypt, Aluminum Pillared Nano-Bentonite, heavy metal, environmental remediation

Low-temperature pyrolysis of oily sludge: roles of Fe/Al-pillared bentonites

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Jia Hanzhong

2017-09-01

Full Text Available Pyrolysis is potentially an effective treatment of oily sludge for oil recovery, and the addition of a catalyst is expected to affect its pyrolysis behavior. In the present study, Fe/Al-pillared bentonite with various Fe/Al ratios as pyrolysis catalyst is prepared and characterized by XRD, N2 adsorption, and NH3-TPD. The integration of Al and Fe in the bentonite interlayers to form pillared clay is evidenced by increase in the basal spacing. As a result, a critical ratio of Fe/Al exists in the Fe/Al-pillared bentonite catalytic pyrolysis for oil recovery from the sludge. The oil yield increases with respect to increase in Fe/Al ratio of catalysts, then decreases with further increasing of Fe/Al ratio. The optimum oil yield using 2.0 wt% of Fe/Al 0.5-pillared bentonite as catalyst attains to 52.46% compared to 29.23% without catalyst addition in the present study. In addition, the addition of Fe/Al-pillared bentonite catalyst also improves the quality of pyrolysis-produced oil and promotes the formation of CH4. Fe/Al-pillared bentonite provides acid center in the inner surface, which is beneficial to the cracking reaction of oil molecules in pyrolysis process. The present work implies that Fe/Al-pillared bentonite as addictive holds great potential in industrial pyrolysis of oily sludge.

CTAB as a soft template for modified clay as filler in active packaging

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Kajonpop Rittirong

2015-06-01

Full Text Available The role of modified clay has been employed in many areas of engineering research. Structure of clay was mainly focused on alumino-silicate layer and its form was presented as pillar layer. It composed of many ion exchanges inside. In industry, in order to use clay with higher efficiency, modification on surface and porosity has been developed. CTAB, one of the most effective cationic surfactant, was employed to modify the surface and porosity of clay.

Modification of Colombian clays with pillars mixed Al-Fe and their evaluation in the catalytic oxidation of phenol in diluted watery solution; Modificacion de arcillas colombianas con pilares mixtos Al-Fe y su evaluacion en la oxidacion catalitica de Fenol en solucion acuosa diluida

Energy Technology Data Exchange (ETDEWEB)

Galeano, Luis A; Moreno G, Sonia

2002-07-01

The environmental legislation has become in the last time particularly restrictive with the bio-recalcitrant pollutants manage in the wastewaters. The pillared clays show great versatility to adjust at demands of the environmental reactions. Present study show that is achieve the modification of starting Colombian clays with precursor solutions of Al-Fe mixed pillars, and is found an excellent performance of them in the catalytic oxidation of aqueous solutions with middle contents of Total Organic Carbon TOC (36 mg C/L). The materials prepared in this way reached quantitative conversion of phenol, as model pollutant, in 2 hours of reaction at 20 Celsius degrade and atmospheric pressure; in 4 hours of reaction, the removal reached 62% of TOC in the solution yielding light carboxylic acids as main byproducts, although that CO{sub 2}. The materials are stable under strongly oxidation media of reaction, and the iron leached in the effluent is close to 0,2 mg/L for the material of better catalytic performance.

Pilarization TiO2 onto De-oiled spent bleaching clay using Rarasaponin as surfactant

Science.gov (United States)

Hindryawati, N.; Daniel; Erwin; Fadillah, N. D.

2018-03-01

Synthesis and characterization TiO2 pillared deoiled spent bleaching clay (DSBC) with rarasaponin as surfactant had been done. Activation DSBC have been done with H2SO4 1N, followed by pillarization with TiO2 using rarasaponin as surfactant. Characterization has done with Fourier transform infrared spectroscopy showed the rarasaponin as surfactant was successfully carried out in DSBC with the presence of absorption peak C=O stretching group in a sharp 1720.50 cm-1 wavelength range. As well as the C-CH2 stretching uptake peak is represented on wave number 1462.04 cm-1 and 1033,85 cm-1 for aromatic functional group C=C stretching. After pillared by TiO2, the XRD pattern on DSBC showed new peak appears on 2θ = 27,4460° 36,0850° and 55,3216° and the mineral contain on DSBC is rectorite with dioctahedral mica layer and dioctahedral smectite with ratio 2:1. This molecule have formula Na.Al4(Si, Al)8.O20.(OH)4. H2O. Crystallinty of pillared clay showed 72,5014 % after calcination and there is some Ti suspected on the layer based on SEM.

Pillarization

NARCIS (Netherlands)

Maussen, M.; Stone, J.; Dennis, R.M.; Rizova, P.S.; Smith, A.D.; Hou, X.

2016-01-01

Pillarization describes a society as divided into a number of "pillars," being compartments standing for the networks of organizations belonging to religious and ideological subcultures. Typically the associations cover a broad range of societal domains (education, media, political parties). The

Long-Term Stability Evaluation and Pillar Design Criterion for Room-and-Pillar Mines

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Yang Yu

2017-10-01

Full Text Available The collapse of abandoned room-and-pillar mines is often violent and unpredictable. Safety concerns often resulted in mine closures with no post-mining stability evaluations. As a result, large amounts of land resources over room-and-pillar mines are wasted. This paper attempts to establish an understanding of the long-term stability issues of goafs (abandoned mines. Considering progressive pillar failures and the effect of single pillar failure on surrounding pillars, this paper proposes a pillar peeling model to evaluate the long-term stability of coal mines and the associated criteria for evaluating the long-term stability of room-and-pillar mines. The validity of the peeling model was verified by numerical simulation, and field data from 500 pillar cases from China, South Africa, and India. It is found that the damage level of pillar peeling is affected by the peel angle and pillar height and is controlled by the pillar width–height ratio.

Electrochemical biosensing based on polypyrrole/titania nanotube hybrid

Energy Technology Data Exchange (ETDEWEB)

Xie, Yibing, E-mail: ybxie@seu.edu.cn; Zhao, Ye

2013-12-01

The glucose oxidase (GOD) modified polypyrrole/titania nanotube enzyme electrode is fabricated for electrochemical biosensing application. The titania nanotube array is grown directly on a titanium substrate through an anodic oxidation process. A thin film of polypyrrole is coated onto titania nanotube array to form polypyrrole/titania nanotube hybrid through a normal pulse voltammetry process. GOD-polypyrrole/titania nanotube enzyme electrode is prepared by the covalent immobilization of GOD onto polypyrrole/titania nanotube hybrid via the cross-linker of glutaraldehyde. The morphology and microstructure of nanotube electrodes are characterized by field emission scanning electron microscopy and Fourier transform infrared analysis. The biosensing properties of this nanotube enzyme electrode have been investigated by means of cyclic voltammetry and chronoamperometry. The hydrophilic polypyrrole/titania nanotube hybrid provides highly accessible nanochannels for GOD encapsulation, presenting good enzymatic affinity. As-formed GOD-polypyrrole/titania nanotube enzyme electrode well conducts bioelectrocatalytic oxidation of glucose, exhibiting a good biosensing performance with a high sensitivity, low detection limit and wide linear detection range. - Graphical abstract: The schematic diagram presents the fabrication of glucose oxidase modified polypyrrole/titania (GOD-PPy/TiO{sub 2}) nanotube enzyme electrode for biosensing application. - Highlights: • Hydrophilic polypyrrole/titania nanotube hybrid is well used as biosensing substrate. • Polypyrrole promotes GOD immobilization on titania nanotubes via glutaraldehyde. • GOD-polypyrrole/titania enzyme electrode shows good bioelectrocatalytic reactivity.

Electrochemical biosensing based on polypyrrole/titania nanotube hybrid

International Nuclear Information System (INIS)

Xie, Yibing; Zhao, Ye

2013-01-01

The glucose oxidase (GOD) modified polypyrrole/titania nanotube enzyme electrode is fabricated for electrochemical biosensing application. The titania nanotube array is grown directly on a titanium substrate through an anodic oxidation process. A thin film of polypyrrole is coated onto titania nanotube array to form polypyrrole/titania nanotube hybrid through a normal pulse voltammetry process. GOD-polypyrrole/titania nanotube enzyme electrode is prepared by the covalent immobilization of GOD onto polypyrrole/titania nanotube hybrid via the cross-linker of glutaraldehyde. The morphology and microstructure of nanotube electrodes are characterized by field emission scanning electron microscopy and Fourier transform infrared analysis. The biosensing properties of this nanotube enzyme electrode have been investigated by means of cyclic voltammetry and chronoamperometry. The hydrophilic polypyrrole/titania nanotube hybrid provides highly accessible nanochannels for GOD encapsulation, presenting good enzymatic affinity. As-formed GOD-polypyrrole/titania nanotube enzyme electrode well conducts bioelectrocatalytic oxidation of glucose, exhibiting a good biosensing performance with a high sensitivity, low detection limit and wide linear detection range. - Graphical abstract: The schematic diagram presents the fabrication of glucose oxidase modified polypyrrole/titania (GOD-PPy/TiO 2 ) nanotube enzyme electrode for biosensing application. - Highlights: • Hydrophilic polypyrrole/titania nanotube hybrid is well used as biosensing substrate. • Polypyrrole promotes GOD immobilization on titania nanotubes via glutaraldehyde. • GOD-polypyrrole/titania enzyme electrode shows good bioelectrocatalytic reactivity

Fe/Ti co-pillared clay for enhanced arsenite removal and photo oxidation under UV irradiation

Energy Technology Data Exchange (ETDEWEB)

Li, Yuan [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Guang Dong Electric Power Design Institute, China Energy Engineering Group Co. Ltd., Guangzhou 510663 (China); Cai, Xiaojiao [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Guo, Jingwei [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); The 718th Research Institute of CSIC, Handan 056027 (China); Zhou, Shimin [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Na, Ping, E-mail: naping@tju.edu.cn [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China)

2015-01-01

Graphical abstract: - Highlights: • An iron and titanium co-pillared montmorillonite (Fe-Ti/MMT) was synthesized for arsenite removal. • Variety of characterization results indicated that Fe and Ti species were pillared in MMT. • A possible mechanism of arsenite adsorption/oxidation with UV light was established. • The participation of Fe component can promote the process of photocatalytic oxidation in Fe-Ti/MMT + As(III) system. • Fe-Ti/MMT can function as both photocatalyst and adsorbent for arsenite removal. - Abstract: A series of iron and titanium co-pillared montmorillonites (Fe-Ti/MMT) were prepared using hydrolysis of inserted titanium and different iron content in montmorillonite (MMT). The Fe-Ti/MMT were characterized by X-ray fluorescence, N{sub 2} adsorption and desorption, X-ray diffraction, scanning electron microscopy (SEM) and transmission electron microscopy (TEM), confirming the effective insertion of Fe species and TiO{sub 2} in the MMT. The Fe-Ti/MMT was used to remove arsenite (As(III)) from aqueous solutions under different conditions. The result of As(III) adsorption under UV irradiation showed that the photo activity can be enhanced by incorporating Fe and Ti in MMT. Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis indicated that the hydroxyl groups bonded to metal oxide (M–OH) played an important role in the adsorption of As(III)

Preparation and characterization of vanadia modified clay.catalytic application in cyclohexene epoxidation

OpenAIRE

REKKAB-Hammoumraoui I; Choukchou-Braham A; Belaidi N

2012-01-01

due to their molecular sieve properties,high surface area and physical/chemical absorption sites,pillared clays found many applications as absorbants,catalysts and catalyst supports… international symposium on"catalysis for clean energy and sustainable chemistry alcobendas,Madrid,27-29 june2012

Fabrication of homogeneous titania/MWNT composite materials

International Nuclear Information System (INIS)

Korbely, Barbara; Nemeth, Zoltan; Reti, Balazs; Seo, Jin Won; Magrez, Arnaud; Forro, Laszlo; Hernadi, Klara

2011-01-01

Highlights: → Homogenous titania coverage on MWNT surface in a controllable way. → Various titanium alkoxy precursors are suitable for layer formation. → Acetone and ethanol are the best to promote interaction between MWNT and titania. -- Abstract: MWNT/titania nanocomposites were prepared by an impregnation method and subsequent heat treatment at 400 o C. Precursor compounds such as titanium (IV) propoxide and titanium (IV) ethoxide were used to cover the surface of CNTs under solution conditions. Electron microscopy and X-ray diffraction techniques were carried out to characterize the as-prepared titania layers.

Composite TiO{sub 2}/clays materials for photocatalytic NOx oxidation

Energy Technology Data Exchange (ETDEWEB)

Todorova, N.; Giannakopoulou, T.; Karapati, S.; Petridis, D. [Institute of Nanoscience and Nanotechnology, NCSR “Demokritos”, P.O. Box 60037, 153 10, Ag. Paraskevi, Attiki (Greece); Vaimakis, T. [Department of Chemistry, University of Ioannina, P.O. Box 1186, 451 10, Ioannina (Greece); Trapalis, C., E-mail: trapalis@ims.demokritos.gr [Institute of Nanoscience and Nanotechnology, NCSR “Demokritos”, P.O. Box 60037, 153 10, Ag. Paraskevi, Attiki (Greece)

2014-11-15

Graphical abstract: - Highlights: • Clays-supported TiO{sub 2} photocatalysts are prepared by simple, scalable method. • Visible light active TiO{sub 2} is incorporated in hydrotalcite, talk and kunipia clays. • The alkali substrates facilitate the NOx adsorption to the photocatalytic surface. • Low-content TiO{sub 2} photocatalysts demonstrated high NOx oxidation activity. • Titania/hydrotalcite photocatalyst exhibited remarkable NOx removal activity. - Abstract: TiO{sub 2} photocatalyst received much attention for air purification applications especially for removal of air pollutants like NOx, VOCs etc. It has been established that the activity of the photocatalyst can be significantly enhanced by its immobilization onto suitable substrates like inorganic minerals, porous silica, hydroxyapatite, adsorbent materials like activated carbon, various co-catalysts such as semiconductors, graphene, reduced graphite oxide, etc. In the present work, photocatalytic composite materials consisted of mineral substrate and TiO{sub 2} in weight ratio 1:1 were manufactured and examined for oxidation and removal of nitric oxides NOx (NO and NO{sub 2}). Commercial titania P25 (Evonik-Degussa) and urea-modified P25 were used as photocatalytically active components. Inorganic minerals, namely kunipia, talk and hydrotalcite were selected as supporting materials due to their layered structure and expected high NOx adsorption capability. Al{sup 3+} and Ca{sup 2+} intercalation was applied in order to improve the dispersion of TiO{sub 2} and its loading into the supporting matrix. The X-ray diffraction analysis and Scanning Electron Microscopy revealed the binary structure of the composites and homogeneous dispersion of the photocatalyst into the substrates. The photocatalytic behavior of the materials in NOx oxidation and removal was investigated under UV and visible light irradiation. The composite materials exhibited superior photocatalytic activity than the bare titania

Development of highly porous crystalline titania photocatalysts

Science.gov (United States)

Marszewski, Michal

The objectives of this dissertation are the design, synthesis, and characterization of titania materials with surface area, porosity, crystallinity and doping tailored toward photocatalytic applications. Ultimately, the research should result in a strategy allowing the synthesis of titania with all these important features. The synthetic methods investigated in this research will include: i) soft-templating, ii) hard-templating, and iii) modified precursor strategy. Soft-templating strategy uses organic templates--either block copolymers or surfactants--that under specific conditions assemble into micelles, and later, these micelles are used to template the desired material around them. The resulting organic-inorganic composite is then calcined in air to remove the organic template and recover the final material with high surface area and large pore volume. This work explores 1) synthesis of titania materials in the presence of polymer templates, and the effects of different synthetic conditions on the structure of the resulting materials. Hard-templating, in contrast to soft-templating, uses inorganic templates. The hard template is introduced during the synthesis to cast its shape onto the fabricated material and removed afterwards, when the material has formed. The final material is an inverse replica of the hard template used, typically with a well-developed mesostructure. This work explores 1) hard templating synthesis of titania materials using silica and alumina, and 2) the effects of the template amount and type. The modified precursor strategy is a novel synthetic method, developed in this research, and designed specifically to achieve titania material with high surface area, large pore volume, high crystallinity, and possibly doping. The modified precursors are prepared by reacting generic titania precursors, such as titanium isopropoxide (TIPO), with organic acids, which results in substitution of some or all alkoxide groups in TIPO structure. The goal

Hydrogen peroxide route to Sn-doped titania photocatalysts

Directory of Open Access Journals (Sweden)

Štengl Václav

2012-10-01

Full Text Available Abstract Background The work aims at improving photocatalytic activity of titania under Vis light irradiation using modification by Sn ions and an original, simple synthesis method. Tin-doped titania catalysts were prepared by thermal hydrolysis of aqueous solutions of titanium peroxo-complexes in the presence of SnCl4 or SnCl2 using an original, proprietary "one pot" synthesis not employing organic solvents, metallo-organic precursors, autoclave aging nor post-synthesis calcination. The products were characterized in details by powder diffraction, XPS, UV–vis, IR, and Raman spectroscopies, electron microscopy and surface area and porosity measurements Results The presence of tin in synthesis mixtures favors the formation of rutile and brookite at the expense of anatase, decreases the particle size of all formed titania polymorphs, and extends light absorption of titania to visible light region >400 nm by both red shift of the absorption edge and introduction of new chromophores. The photocatalytic activity of titania under UV irradiation and >400 nm light was tested by decomposition kinetics of Orange II dye in aqueous solution Conclusions Doping by Sn improves titania photoactivity under UV light and affords considerable photoactivity under >400 nm light due to increased specific surface area and a phase heterogeneity of the Sn-doped titania powders.

Preparation and characterization of titania based nanowires

International Nuclear Information System (INIS)

Stengl, Vaclav; Bakardjieva, Snejana; Murafa, Natalie; Vecernikova, Eva; Subrt, Jan; Balek, Vladimir

2007-01-01

A new method for preparation of titania nanowires with diameter around 10 nm and length up to 2-3 μm is described. The precursor was prepared from sodium titanate by adding ethylene glycole (EG) and heating at temperature of 198 deg. C for 6 h under reflux. The sodium titanate glycolate formed by this way aggregated into 1D nanostructures and was subsequently transformed into titania glycolate during a chemical treatment with 98% sulfuric acid. Titania nanowires with variable amount of anatase and rutile were prepared by heating to temperatures in the range 350-1000 deg. C. The precursor as well as titania based samples were characterized by X-ray diffraction, Infrared spectroscopy, Scanning electron microscopy, High resolution transmission microscopy, Thermogravimetry, Differential thermal analysis, Evolved gas analysis and Emanation thermal analysis. The nitrogen adsorption/desorption was used for surface area and porosity determination. The photoactivity of the prepared titania samples was assessed by the photocatalytic decomposition of 4-chlorophenol in an aqueous slurry under UV irradiation of 365 nm wavelength

Stress reduction for pillar filled structures

Science.gov (United States)

Nikolic, Rebecca J.; Conway, Adam; Shao, Qinghui; Voss, Lars; Cheung, Chin Li; Dar, Mushtaq A.

2015-09-01

According to one embodiment, an apparatus for detecting neutrons includes an array of pillars, wherein each of the pillars comprises a rounded cross sectional shape where the cross section is taken perpendicular to a longitudinal axis of the respective pillar, a cavity region between each of the pillars, and a neutron sensitive material located in each cavity region.

Improving the photovoltaic performance of dye-sensitized solar cell by graphene/titania photoanode

International Nuclear Information System (INIS)

Zhao, Junchang; Wu, Jihuai; Zheng, Ming; Huo, Jinghao; Tu, Yongguang

2015-01-01

Highlights: • A colloid of graphene/titania is prepared, and thus a graphene/titania film is made. • The film shows high porosity, large surface area and small transfer resistance. • The cell with graphene/titania photoanode obtains a conversion efficiency of 7.52%. • Which is increased by 18% compared to the cell with pristine titania electrode. - Abstract: A mixed colloid of graphene and titania is synthesized by a one-step hydrothermal reaction, thus a graphene/titania film photoanode is prepared. The graphene/titania film shows high porosity and large specific surface area, which favors a full adsorption of sensitized dye. On the other hand, the graphene/titania electrode has smaller charge transfer resistance than the pristine titania electrode, which replies that the graphene/titania electrode accelerates electronic transportation and suppresses the charge recombination. Under an optimal condition, the dye-sensitized solar cell based on graphene/titania photoanode achieve a power conversion efficiency of 7.52%, which is increased by 17.7% compared to the cell based on the pristine titania electrode under a simulated solar light irradiation of 100 mW·cm −2

Stress-state monitoring of coal pillars during room and pillar extraction

Czech Academy of Sciences Publication Activity Database

Waclawik, Petr; Ptáček, Jiří; Koníček, Petr; Kukutsch, Radovan; Němčík, J.

2016-01-01

Roč. 15, č. 2 (2016), s. 49-56 ISSN 2300-3960 R&D Projects: GA MŠk(CZ) LO1406; GA MŠk ED2.1.00/03.0082 Institutional support: RVO:68145535 Keywords : stress-state monitoring * room and pillar * coal pillar Subject RIV: DH - Mining , incl. Coal Mining http://www.sciencedirect.com/science/article/pii/S2300396016300180

Recent progress in mesoporous titania materials: adjusting morphology for innovative applications

Directory of Open Access Journals (Sweden)

Juan L Vivero-Escoto, Ya-Dong Chiang, Kevin C-W Wu and Yusuke Yamauchi

2012-01-01

Full Text Available This review article summarizes recent developments in mesoporous titania materials, particularly in the fields of morphology control and applications. We first briefly introduce the history of mesoporous titania materials and then review several synthesis approaches. Currently, mesoporous titania nanoparticles (MTNs have attracted much attention in various fields, such as medicine, catalysis, separation and optics. Compared with bulk mesoporous titania materials, which are above a micrometer in size, nanometer-sized MTNs have additional properties, such as fast mass transport, strong adhesion to substrates and good dispersion in solution. However, it has generally been known that the successful synthesis of MTNs is very difficult owing to the rapid hydrolysis of titanium-containing precursors and the crystallization of titania upon thermal treatment. Finally, we review four emerging fields including photocatalysis, photovoltaic devices, sensing and biomedical applications of mesoporous titania materials. Because of its high surface area, controlled porous structure, suitable morphology and semiconducting behavior, mesoporous titania is expected to be used in innovative applications.

Size and morphology effects of titania on dye-sensitized solar cells performance

International Nuclear Information System (INIS)

Chien, Wen-Chen; Lin, Chien-Chih; Jang, Shiue-Ming; Kao, Tien-Hsieh

2013-01-01

This study uses commercial titania (P25) to prepare titania nanowires (NWs) using alkali and hydrothermal treatments. Nanosized titania P25 and NWs were used to prepare spray-dried titania P25 (SP25) and spray-dried titania nanowires (SNWs), respectively, using the spray-drying process. These different titania sizes and morphologies were used to fabricate photoelectrodes for dye-sensitized solar cells (DSSCs) and to investigate their effect on cell performance. All prepared titania NWs and SNWs were in the anatase phase after heat treatment at 450 °C for 2 h. The specific areas for titania with different morphologies were 49.5 m 2 /g for P25, 48.3 m 2 /g for SP25, 42.6 m 2 /g for NWs, and 40.3 m 2 /g for SNWs. The results show that the surface areas decreased when the titania P25 or NWs were processed by spray drying. In optimal conditions, DSSCs prepared from P25 + 2.5 wt.% NWs with a light-to-electric energy conversion efficiency of 5.88% were produced using a simulated solar light irradiation of 100 mW/cm 2 (AM 1.5). - Highlights: • Titania with different size and morphology were prepared. • Hydrothermal and spray drying process were applied. • Solar cells with an efficiency of 5.88% were produced

Size and morphology effects of titania on dye-sensitized solar cells performance

Energy Technology Data Exchange (ETDEWEB)

Chien, Wen-Chen, E-mail: wcchien@mail.mcut.edu.tw [Department of Chemical Engineering, Ming Chi University of Technology, 84 Gunjuan Road, New Taipei City 243, Taiwan (China); Battery Research Center of Green Energy, Ming Chi University of Technology, 84 Gunjuan Road, New Taipei City 243, Taiwan (China); Lin, Chien-Chih [Department of Chemical Engineering, Ming Chi University of Technology, 84 Gunjuan Road, New Taipei City 243, Taiwan (China); Jang, Shiue-Ming [Industrial Technology Research Institute, Hsinchu 310, Taiwan (China); Kao, Tien-Hsieh [Department of Chemical Engineering, Ming Chi University of Technology, 84 Gunjuan Road, New Taipei City 243, Taiwan (China)

2013-10-01

This study uses commercial titania (P25) to prepare titania nanowires (NWs) using alkali and hydrothermal treatments. Nanosized titania P25 and NWs were used to prepare spray-dried titania P25 (SP25) and spray-dried titania nanowires (SNWs), respectively, using the spray-drying process. These different titania sizes and morphologies were used to fabricate photoelectrodes for dye-sensitized solar cells (DSSCs) and to investigate their effect on cell performance. All prepared titania NWs and SNWs were in the anatase phase after heat treatment at 450 °C for 2 h. The specific areas for titania with different morphologies were 49.5 m{sup 2}/g for P25, 48.3 m{sup 2}/g for SP25, 42.6 m{sup 2}/g for NWs, and 40.3 m{sup 2}/g for SNWs. The results show that the surface areas decreased when the titania P25 or NWs were processed by spray drying. In optimal conditions, DSSCs prepared from P25 + 2.5 wt.% NWs with a light-to-electric energy conversion efficiency of 5.88% were produced using a simulated solar light irradiation of 100 mW/cm{sup 2} (AM 1.5). - Highlights: • Titania with different size and morphology were prepared. • Hydrothermal and spray drying process were applied. • Solar cells with an efficiency of 5.88% were produced.

Pillar-type acoustic metasurface

DEFF Research Database (Denmark)

Jin, Yabin; Bonello, Bernard; Moiseyenko, Rayisa

2017-01-01

We theoretically investigate acoustic metasurfaces consisting of either a single pillar or a line of identical pillars on a thin plate, and we report on the dependence on the geometrical parameters of both the monopolar compressional and dipolar bending modes. We show that for specific dimensions...

Imaging of the cervical articular pillar

Energy Technology Data Exchange (ETDEWEB)

Yeomans, E. [Orange Base Hospital, Orange, NSW (Australia)

1998-12-01

The cervical articular pillar, due to the complex anatomical structure of the cervical spine, is not well demonstrated in routine plain radiographic views. Dedicated views have been devised to demonstrate the pillar, yet their performance has abated considerably since the inception of Computed Tomography (CT) in the 1970`s. It is the consideration that CT does not image the articular pillar with a 10 per cent accuracy that poses the question: Is there still a need for plain radiography of the cervical articular pillar? This paper studies the anatomy, plain radiography, and incidence of injury to the cervical articular pillar. It discusses (with reference to current and historic literature) the efficacy of current imaging protocols in depicting this injury. It deals with plain radiography, CT, complex tomography, and Magnetic Resonance Imaging (MRI) of the cervical spine to conclude there may still be a position in current imaging protocols for plain radiography of the cervical articular pillar. Copyright (1998) Australian Institute of Radiography 43 refs., 5 figs.

Synthesis and polymorphic control for visible light active titania nanoparticles

Science.gov (United States)

Kaewgun, Sujaree

Titania (TiO2) is useful for many applications in photocatalysis, antimicrobials, pigment, deodorization, and decomposition of harmful organics and undesirable compounds in the air and waste water under UV irradiation. Among the three phases of TiO2, Rutile, Anatase, and Brookite, studies have been more focused on the anatase and rutile phases. Pure brookite is the most difficult phase to prepare, even under hydrothermal conditions. Predominantly brookite phase TiO2 nanoparticles were prepared by the Water-based Ambient Condition Sol (WACS) process in our laboratory. The objectives of this research were to enhance visible light active (VLA) photocatalytic properties of polymorphic brookite TiO2 by minimizing the lattice defects and narrowing band gap of titania by nitrogen and/or carbon chromophone, and to investigate the deactivation, reusability, and regeneration of the VLA titania in order to design better titania catalysts for organic compound degradation applications. In order to study the influence of hydroxyl content on photocatalytic activities (PCAs) of polymorphic titania nanoparticles, the WACS samples were post-treated by a Solvent-based Ambient Condition Sol (SACS) process in sec-butanol (sec-BuOH). All samples were characterized for phase composition, surface area, hydroxyl contamination, and particle morphology by x-ray diffraction, N2 physisorption, FT-IR, solid state 1H NMR and scanning electron microscopy, and then compared to a commercial titania, Degussa P25. Evaluation of methyl orange (MO) degradation under UV irradiation results showed that the lower lattice hydroxyl content in SACS titania enhanced the PCA. As-prepared titania and SACS samples, which have similar surface areas and crystallinity, were compared in order to prove that the superior PCA came from the reduction in the lattice hydroxyl content. To enhance PCA and VLA properties of WACS, an alternative high boiling point polar solvent, N-methylpyrrolidone (NMP), was utilized in the

The immobilization of titania nanoparticles on hyaluronan films and their photocatalytic properties

International Nuclear Information System (INIS)

Pasqui, Daniela; Atrei, Andrea; Barbucci, Rolando

2009-01-01

We have developed a method to bind titania nanoparticles onto hyaluronic films (HA) photoimmobilized on silanized glass. Titania nanoparticles were deposited on the HA films from commercially available dispersions by casting and dip-coating methods at various pH values. XPS was used to monitor the deposition of titania and to estimate the surface coverage of the nanoparticles. The topography of the titania-modified HA films was investigated by means of AFM. XPS results indicate that the titania surface coverage depends on the preparation method and the pH of the dispersion. We found that the maximum titania nanoparticle surface coverage was obtained by the casting method with the formation of aggregates and multilayers of particles. The titania surface coverage for the surfaces prepared by the dip-coating method is pH-dependent. The surfaces prepared at pH 2 show a surface coverage of 65% and a rather uniform distribution of particles. We found that titania nanoparticles are anchored in a stable way to the HA substrate in a phosphate buffer solution (PBS) and that the interaction between the HA and the titania is through the carbonyl group of carboxylates and amidic groups of the polymer. AFM images clearly show that titania nanoparticles are uniformly distributed over the HA films. By measuring the average diameter and the average height of the nanoparticles deposited on HA films it appears that the particles are partially embedded in the polysaccharide films. The results of the study on the photobleaching of methylene blue indicate that the characteristic photocatalytic activity of titania is maintained when the nanoparticles are anchored to the HA substrate.

Titania based nanocomposites as a photocatalyst: A review

Directory of Open Access Journals (Sweden)

Farha Modi

2016-08-01

Full Text Available Titanium dioxide or Titania is a semiconductor compound having remarkable dielectric, electronic and physico-chemical surface properties. It has excellent photocatalytic efficiency in presence of UV light. The curious grey matter of scientists has forced them to focus their attention to make Titania capable of utilizing the whole visible spectrum of light also. The hurdle that they faced was larger band gap of 3 eV and more, for this, efforts were directed towards adding other materials to Titania. The present article reviews the recent advances in the synthesis of different Titanium-based nanocomposite materials and their photocatalytic efficiency so as to apply them for several applications such as removal of dyes, other water pollutants, microbes and metals. A brief explanation of the photocatalytic process and the structural properties of TiO2 are also touched upon. Various past and recent approaches made in these directions of utilizing Titania based nanocomposites for photocatalytic activities are reviewed. It is suggested that there is a need to establish the kinetics of photo-corrosion and thermodynamic part of the photo-corrosion of various composites developed by different group across the globe, so that Titania based nanocomposites could be commercially utilized.

30 CFR 75.207 - Pillar recovery.

Science.gov (United States)

2010-07-01

... SAFETY STANDARDS-UNDERGROUND COAL MINES Roof Support § 75.207 Pillar recovery. Pillar recovery shall be... be left in place. (b) Before mining is started in a pillar split or lift— (1) At least two rows of breaker posts or equivalent support shall be installed— (i) As close to the initial intended breakline as...

Fabrication of Titania Nanotubes for Gas Sensing Applications

Science.gov (United States)

Dzilal, A. A.; Muti, M. N.; John, O. D.

2010-03-01

Detection of hydrogen is needed for industrial process control and medical applications where presence of hydrogen indicates different type of health problems. Titanium dioxide nanotube structure is chosen as an active component in the gas sensor because of its highly sensitive electrical resistance to hydrogen over a wide range of concentrations. The objective of the work is to fabricate good quality titania nanotubes suitable for hydrogen sensing applications. The fabrication method used is anodizing method. The anodizing parameters namely the voltage, time duration, concentration of hydrofluoric acid in water, separation between the electrodes and the ambient temperature are varied accordingly to find the optimum anodizing conditions for production of good quality titania nanotubes. The highly ordered porous titania nanotubes produced by this method are in tabular shape and have good uniformity and alignment over large areas. From the investigation done, certain set of anodizing parameters have been found to produce good quality titania nanotubes with diameter ranges from 47 nm to 94 nm.

Thermoelectric properties of silicon nano pillars

Energy Technology Data Exchange (ETDEWEB)

Stranz, Andrej; Soekmen, Uensal; Waag, Andreas; Peiner, Erwin [Institute of Semiconductor Technology, Braunschweig (Germany)

2010-07-01

In order to establish silicon as a efficient thermoelectric material, its high thermal conductivity has to be reduced which is feasible, e.g., by nano structuring. Therefore, in this study Si-based sub-micron pillars of various dimensions were investigated. Using anisotropic etching followed by thermal oxidation we could fabricate pillars of diameters <500 nm, about 25 {mu}m in height with aspect ratios of more than 50. The distance between the pillars was varied from 500 nm to 10 micron. Besides the fabrication and structural characterization of sub-micron silicon pillars, and adequate metrology for measuring their thermoelectric properties was implemented. Commercial tungsten probes and self-made gold probes, as well as Wollaston wire probes were used for electrical and thermal conductivity, as well as Seebeck voltage measurements on single pillars in a scanning electron microscope equipped with nano manipulators.

Pillar support for a wind power plant

Energy Technology Data Exchange (ETDEWEB)

Dietz, A

1978-08-24

The invention concerns a stationary pillar for a wind power plant with vertical rotors in the outside walls of individual parts of the structure, which are arranged above one antoher and which can turn together freely as a pillar facade. There are problems in such a stationary pillar because of storm forces on the one hand, which try to buckle the pillar, and, on the other hand, the pillar should be easy to mount without difficult fishplates or screwed connections. In order to solve this problem, the invention provides that tension elements run from the top ring of the pillar to the foundation through all the spars and through the connecting rings inside the spars, whose tension forces not only counteract buckling of the pillar, but also pull the intersections of the spars together in tension and independently of the screwed connections also provided. The connecting rings at the connections to the spars have half sleeves, which are pushed into a sleeve of the spar coming from below. The tension elements can consist of bundles of steel wires or a wire rope.

Water condensation on ultrahydrophobic flexible micro pillar surface

Science.gov (United States)

Narhe, Ramchandra

2016-05-01

We investigated the growth dynamics of water drops in controlled condensation on ultrahydrophobic geometrically patterned polydimethylsiloxane (PDMS) cylindrical micro pillars. At the beginning, the condensed drops size is comparable to the pattern dimensions. The interesting phenomenon we observe is that, as the condensation progresses, water drops between the pillars become unstable and enforced to grow in the upward direction along the pillars surface. The capillary force of these drops is of the order of μ\\text{N} and acts on neighboring pillars. That results into bending of the pillars. Pillars bending enhances the condensation and favors the most energetically stable Wenzel state.

Hydrolysis and ion exchange of titania nanoparticles towards large-scale titania and titanate nanobelts for gas sensing applications

International Nuclear Information System (INIS)

Bela, Somaiah; Ho, Ghim Wei; Wong, Andrew See Weng

2010-01-01

One-dimensional titanate and titania nanostructures are prepared by hydrothermal method from titania nanoparticles precursor via hydrolysis and ion exchange processes. The formation mechanism and the reaction process of the nanobelts are elucidated. The effects of the NaOH concentration, HCl leaching duration and the calcination temperature on the morphology and chemical composition of the produced nanobelts are investigated. Na + ions of the titanate nanobelts can be effectively removed by longer acid leaching and neutralization process and transformed into metastable hydrogen titanate compound. A hybrid hydrogen titanate and anatase titania nanobelts can be obtained under dehydration process of 500 0 C. The nanobelts are produced in gram quantities and easily made into nanostructure paper for the bulk study on their electrical and sensing properties. The sensing properties of the nanobelts sheet are tested and exhibited response to H 2 gas.

Sustainable steric stabilization of colloidal titania nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Elbasuney, Sherif, E-mail: sherif_basuney2000@yahoo.com

2017-07-01

Graphical abstract: Controlled surface properties of titania nanoparticles via surface modification, flocculation from aqueous phase (a), stabilization in aqueous phase (b), extraction to organic phase (c). - Highlights: • Complete change in surface properties of titania nanoparticles from hydrophilic to hydrophobic. • Harvesting the formulated nanoparticles from the aqueous phase to the organic phase. • Exclusive surface modification in the reactor during nanoparticle synthesis. • Sustainable stabilization of titania nanoparticles in aqueous media with polar polymeric dispersant. - Abstract: A route to produce a stable colloidal suspension is essential if mono-dispersed particles are to be successfully synthesized, isolated, and used in subsequent nanocomposite manufacture. Dispersing nanoparticles in fluids was found to be an important approach for avoiding poor dispersion characteristics. However, there is still a great tendency for colloidal nanoparticles to flocculate over time. Steric stabilization can prevent coagulation by introducing a thick adsorbed organic layer which constitutes a significant steric barrier that can prevent the particle surfaces from coming into direct contact. One of the main features of hydrothermal synthesis technique is that it offers novel approaches for sustainable nanoparticle surface modification. This manuscript reports on the sustainable steric stabilization of titanium dioxide nanoparticles. Nanoparticle surface modification was performed via two main approaches including post-synthesis and in situ surface modification. The tuneable hydrothermal conditions (i.e. temperature, pressure, flow rates, and surfactant addition) were optimized to enable controlled steric stabilization in a continuous fashion. Effective post synthesis surface modification with organic ligand (dodecenyl succinic anhydride (DDSA)) was achieved; the optimum surface coating temperature was reported to be 180–240 °C to ensure DDSA ring opening

Empirical pillar design methods review report: Final report

International Nuclear Information System (INIS)

1988-02-01

This report summarizes and evaluates empirical pillar design methods that may be of use during the conceptual design of a high-level nuclear waste repository in salt. The methods are discussed according to category (i.e, main, submain, and panel pillars; barrier pillars; and shaft pillars). Of the 21 identified for main, submain, and panel pillars, one method, the Confined Core Method, is evaluated as being most appropriate for conceptual design. Five methods are considered potentially applicable. Of six methods identified for barrier pillars, one method based on the Load Transfer Distance concept is considered most appropriate for design. Based on the evaluation of 25 methods identified for shaft pillars, an approximate sizing criterion is proposed for use in conceptual design. Aspects of pillar performance relating to creep, ground deformation, interaction with roof and floor rock, and response to high temperature environments are not adequately addressed by existing empirical design methods. 152 refs., 22 figs., 14 tabs

Sintering and mechanical properties of the alumina–tricalcium phosphate–titania composites

Energy Technology Data Exchange (ETDEWEB)

Sakka, Siwar, E-mail: sakka.siwar@yahoo.fr; Bouaziz, Jamel; Ben Ayed, Foued

2014-07-01

The objective of this study was to determine the effect of the content of titania and the sintering process on the transformation phase, the densification, the rupture strength and the microstructures of the alumina–10 wt.% tricalcium phosphate composites. After the sintering process, the samples were examined by using {sup 31}P and {sup 27}Al magic angle scanning nuclear magnetic resonance, X-ray powder diffraction and scanning electron microscopy analysis. The Brazilian test was used to measure the rupture strength of the samples. The present results provide new information about solid-state reactivity in the ternary system α-alumina-β-tricalcium phosphate–anatase–titania. The differential thermal analysis of the α-alumina-β-tricalcium phosphate–titania composites shows two endothermic peaks, at 1360 °C and at 1405 °C, which are caused by the reactions between titania/alumina and titania/tricalcium phosphate, respectively. Thus, the presence of titania in the alumina–10 wt.% tricalcium phosphate leads to the formation of β-Al{sub 2}TiO{sub 5} at 1360 °C. At 1600 °C, the alumina–10 wt.% tricalcium phosphate–5 wt.% titania composites displayed the highest rupture strength (74 MPa), compared to the alumina–10 wt.% tricalcium phosphate composites (13.5 MPa). Accordingly, the increase of the rupture strength is due to the formation of the new β-Al{sub 2}TiO{sub 5} phase. - Highlights: • We examine the mechanical properties of bioceramics. • We measure the rupture strength by the Brazilian test. • We characterize the alumina–10 wt.% tricalcium phosphate–titania composites.

Ultrahigh temperature-sensitive silicon MZI with titania cladding

Directory of Open Access Journals (Sweden)

Jong-Moo eLee

2015-05-01

Full Text Available We present a possibility of intensifying temperature sensitivity of a silicon Mach-Zehnder interferometer (MZI by using a highly negative thermo-optic property of titania (TiO2. Temperature sensitivity of an asymmetric silicon MZI with a titania cladding is experimentally measured from +18pm/C to -340 pm/C depending on design parameters of MZI.

Silver decorated titanate/titania nanostructures for efficient solar driven photocatalysis

International Nuclear Information System (INIS)

Gong, Dangguo; Ho, Weng Chye Jeffrey; Tang Yuxin; Tay Qiuling; Lai Yuekun; Highfield, James George; Chen Zhong

2012-01-01

Photocatalysis has attracted significant interest to solve both the energy crisis and effectively combat environmental contamination. However, as the most widely used photocatalyst, titania (TiO 2 ) suffers from inefficient utilization of solar energy due to its wide band gap. In the present paper, we describe a method to extend the absorption edge of photocatalyst to visible region by the surface plasmon effect of silver. Silver ions are photo-reduced onto the surface of titanate nanotubes, which are synthesized by a conventional hydrothermal method. The as-synthesized Ag/titanate composite is transformed into Ag/titania nanoparticles by annealing at different temperatures. It is found that the interaction of Ag nanoparticles with the supports (titanate/titania) plays a key role for the visible light activity. The samples annealed at low temperature (<350 °C) do not show significant activity under our conditions, while the one annealed at 450 °C shows fast-degradation of methyl orange (MO) under visible light irradiation. The detailed mechanisms are also discussed. - Graphical abstract: Silver nanoparticles decorated titanate/titania as visible light active photocatalysts: silver nanoparticles could be excited by visible light due to its surface plasmon effect and excited electrons could be transferred to the conduction band of the semiconductor, where the reduction process occurs. Highlights: ► Uniform Ag nanoparticles are photo-reduced onto titanate and titania nanostructures. ► Titania crystal is formed by annealing hydrogen titanate at different temperatures. ► Best visible-light activity is achieved by Ag-loaded titania annealed at 450 °C. ► The visible light activity is attributed to the surface plasmonic resonance effect.

Controlled growth of silica-titania hybrid functional nanoparticles through a multistep microfluidic approach.

Science.gov (United States)

Shiba, K; Sugiyama, T; Takei, T; Yoshikawa, G

2015-11-11

Silica/titania-based functional nanoparticles were prepared through controlled nucleation of titania and subsequent encapsulation by silica through a multistep microfluidic approach, which was successfully applied to obtaining aminopropyl-functionalized silica/titania nanoparticles for a highly sensitive humidity sensor.

Transparent sculptured titania films for enhanced light absorption in thin-film Si solar cells

Energy Technology Data Exchange (ETDEWEB)

Hung, Kai-Hsiang, E-mail: khhung@itri.org.tw [Green Energy and Environment Research Laboratories, Industrial Technology Research Institute, Hsinchu, Taiwan (China); Chiou, Guan-Di; Wong, Ming-Show [Department of Materials Science and Engineering, National Dong Hwa University, Hualien, Taiwan (China); Wang, Yu-Chih [Green Energy and Environment Research Laboratories, Industrial Technology Research Institute, Hsinchu, Taiwan (China); Chung, I-Shan [Electronics and Optoelectronics Research Laboratories, Industrial Technology Research Institute, Hsinchu, Taiwan (China)

2011-12-30

This study presents a description of the enhancement of light absorption in thin-film silicon (Si) solar cells by using sculptured titania (TiO{sub 2}) films. We used an electron-beam evaporation system with a glancing angle deposition (GLAD) method to deposit porous TiO{sub 2} films on fluorine-doped SnO{sub 2} (FTO) substrates. The GLAD TiO{sub 2}/FTO films were used as conductive electrodes in hydrogenated microcrystalline silicon ({mu}c-Si:H) solar cells. Transmission electron microscopy revealed that the GLAD TiO{sub 2} films are composed of sculptured nano-pillars on an FTO surface, and this nanostructure provides a synergistic route for light scattering enhancement. The GLAD TiO{sub 2}/FTO exhibited a 68% improvement of optical haze (at {lambda} = 600 nm). The {mu}c-Si:H solar cells consisting of the GLAD-nanostructured TiO{sub 2} resulted in a 5% improvement of short-circuit current (J{sub sc}) and yielded a cell efficiency of 6.6%.

Molecularly imprinted titania nanoparticles for selective recognition and assay of uric acid

Science.gov (United States)

Mujahid, Adnan; Khan, Aimen Idrees; Afzal, Adeel; Hussain, Tajamal; Raza, Muhammad Hamid; Shah, Asma Tufail; uz Zaman, Waheed

2015-06-01

Molecularly imprinted titania nanoparticles are su ccessfully synthesized by sol-gel method for the selective recognition of uric acid. Atomic force microscopy is used to study the morphology of uric acid imprinted titania nanoparticles with diameter in the range of 100-150 nm. Scanning electron microscopy images of thick titania layer indicate the formation of fine network of titania nanoparticles with uniform distribution. Molecular imprinting of uric acid as well as its subsequent washing is confirmed by Fourier transformation infrared spectroscopy measurements. Uric acid rebinding studies reveal the recognition capability of imprinted particles in the range of 0.01-0.095 mmol, which is applicable in monitoring normal to elevated levels of uric acid in human blood. The optical shift (signal) of imprinted particles is six times higher in comparison with non-imprinted particles for the same concentration of uric acid. Imprinted titania particles have shown substantially reduced binding affinity toward interfering and structurally related substances, e.g. ascorbic acid and guanine. These results suggest the possible application of titania nanoparticles in uric acid recognition and quantification in blood serum.

Seeded Growth of Titania Colloids with Refractive Index Tunability and Fluorophore-Free Luminescence

NARCIS (Netherlands)

Demirors, A.F.; Jannasch, A.; van Oostrum, P.D.J.; Schäffer, E.; Imhof, A.; van Blaaderen, A.

2011-01-01

Titania is an important material in modern materials science, chemistry, and physics because of its special catalytic, electric, and optical properties. Here, we describe a novel method to synthesize colloidal particles with a crystalline titania, anatase core and an amorphous titania-shell

Effects of pillar height and junction depth on the performance of radially doped silicon pillar arrays for solar energy applications

NARCIS (Netherlands)

Elbersen, R.; Vijselaar, Wouter Jan, Cornelis; Tiggelaar, Roald M.; Gardeniers, Johannes G.E.; Huskens, Jurriaan

2016-01-01

The effects of pillar height and junction depth on solar cell characteristics are investigated to provide design rules for arrays of such pillars in solar energy applications. Radially doped silicon pillar arrays are fabricated by deep reactive ion etching of silicon substrates followed by the

In situ iron-57 Moessbauer spectroscopic investigations of the effect of titania surface area on the reducibility of titania-supported iron oxide

International Nuclear Information System (INIS)

Berry, F.J.; Du Hongzhang

1990-01-01

Iron-57 Moessbauer spectroscopy has been used to monitor the reducibility in hydrogen of iron oxides supported on titania of differing surface areas. The results show that although Fe 3+ in the iron oxide supported on low surface area titania (11 m 2 g -1 ) is not amenable to facile reduction at low temperatures, complete reduction to metallic iron is achieved by treatment at 600deg C. The data also show that the extent of reduction at elevated temperatures exceeds that which is obtained on similar silica- and alumina-supported systems. Fe 3+ in iron oxide supported on higher surface area titania (50 m 2 g -1 and 240 m 2 g -1 ) is partially reduced in hydrogen at 235deg C to Fe 2+ but fails to attain complete reduction to the metallic state following treatment at 600deg C. The results are related to the different dispersions of iron oxide which can be attained on titania of differing surface area and the consequent interactions between the support and the supported phases. (orig.)

Design of Merensky Reef crush pillars

CSIR Research Space (South Africa)

Watson, BP

2010-10-01

Full Text Available appear stiff enough. However, evidence from the pillar bursts suggests that unfailed pillars located at 10 m or more from the face are in a dangerous, soft-loading situation and may burst if failure takes place. From the evidence of the few collapses... reached a deformation of 32 mm during the initial failure and all failed in a reasonably stable manner. The unacceptable stiffness of the surrounding strata is about 5.0 mm/GN. Most of the measured pillars failed under loading conditions where...

Adsorption of vitamin E on mesoporous titania nanocrystals

International Nuclear Information System (INIS)

Shih, C.J.; Lin, C.T.; Wu, S.M.

2010-01-01

Tri-block nonionic surfactant and titanium chloride were used as starting materials for the synthesis of mesoporous titania nanocrystallite powders. The main objective of the present study was to examine the synthesis of mesoporous titania nanocrystals and the adsorption of vitamin E on those nanocrystals using X-ray diffraction (XRD), transmission electron microscopy, and nitrogen adsorption and desorption isotherms. When the calcination temperature was increased to 300 o C, the reflection peaks in the XRD pattern indicated the presence of an anatase phase. The crystallinity of the nanocrystallites increased from 80% to 98.6% with increasing calcination temperature from 465 o C to 500 o C. The N 2 adsorption data and XRD data taken after vitamin E adsorption revealed that the vitamin E molecules were adsorbed in the mesopores of the titania nanocrystals.

M-Polynomials and Topological Indices of Titania Nanotubes

Directory of Open Access Journals (Sweden)

Mobeen Munir

2016-10-01

Full Text Available Titania is one of the most comprehensively studied nanostructures due to their widespread applications in the production of catalytic, gas sensing, and corrosion-resistant materials. M-polynomial of nanotubes has been vastly investigated, as it produces many degree-based topological indices, which are numerical parameters capturing structural and chemical properties. These indices are used in the development of quantitative structure-activity relationships (QSARs in which the biological activity and other properties of molecules, such as boiling point, stability, strain energy, etc., are correlated with their structure. In this report, we provide M-polynomials of single-walled titania (SW TiO2 nanotubes and recover important topological degree-based indices to theoretically judge these nanotubes. We also plot surfaces associated to single-walled titania (SW TiO2 nanotubes.

Increased fibroblast functionality on CNN2-loaded titania nanotubes

Directory of Open Access Journals (Sweden)

Wei HB

2012-02-01

Full Text Available Hongbo Wei*, Shuyi Wu*, Zhihong Feng, Wei Zhou, Yan Dong, Guofeng Wu, Shizhu Bai, Yimin Zhao Department of Prosthodontics, School of Stomatology, Fourth Military Medical University, Xi'an, People's Republic of China *These authors contributed equally to this workAbstract: Infection and epithelial downgrowth are major problems associated with maxillofacial percutaneous implants. These complications are mainly due to the improper closure of the implant–skin interface. Therefore, designing a percutaneous implant that better promotes the formation of a stable soft tissue biologic seal around percutaneous sites is highly desirable. Additionally, the fibroblast has been proven to play an important role in the formation of biologic seals. In this study, titania nanotubes were filled with 11.2 kDa C-terminal CCN2 (connective tissue growth factor fragment, which could exert full CCN2 activity to increase the biological functionality of fibroblasts. This drug delivery system was fabricated on a titanium implant surface. CCN2 was loaded into anodized titania nanotubes using a simplified lyophilization method and the loading efficiency was approximately 80%. Then, the release kinetics of CCN2 from these nanotubes was investigated. Furthermore, the influence of CCN2-loaded titania nanotubes on fibroblast functionality was examined. The results revealed increased fibroblast adhesion at 0.25, 0.5, 1, 2, 4, and 24 hours, increased fibroblast viability over the course of 5 days, as well as enhanced actin cytoskeleton organization on CCN2-loaded titania nanotubes surfaces compared to uncoated, unmodified counterparts. Therefore, the results from this in vitro study demonstrate that CCN2-loaded titania nanotubes have the ability to increase fibroblast functionality and should be further studied as a method of promoting the formation of a stable soft tissue biologic seal around percutaneous sites.Keywords: anodization, titania nanotubes, adhesion, connective

Reassessment of coal pillar design procedure

CSIR Research Space (South Africa)

Madden, BJ

1995-12-01

Full Text Available The SIMRAC project COL 021A entitled “a reassessment of coal pillar design procedures” set out to achieve a coal pillar design procedure that takes cognisance of different geological and structural factors as well as the influence...

The Effect of Transition Metal Doping on the Photooxidation Process of Titania-Clay Composites

Directory of Open Access Journals (Sweden)

Judit Ménesi

2008-01-01

Full Text Available Montmorillonite-TiO2 composites containing various transition metal ions (silver, copper, or nickel were prepared, and their photocatalytic efficiencies were tested in the degradation of ethanol vapor at 70% relative humidity. Two light sources, UV-rich ( = 254 nm and visible ( = 435 nm, were used. The kinetics of degradation was monitored by gas chromatography. It was established that, in the case of each catalyst, ethanol degradation was more efficient in UV-C ( = 254 nm than in visible light, furthermore, these samples containing silver or copper ions were in each case about twice more efficient than P25 TiO2 (Degussa AG. used as a reference. In photooxidation by visible light, TiO2/clay samples doped with silver or copper were also more efficient than the reference sample, P25 TiO2. We show that doping metal ions can also be delivered to the surface of the support by ion exchange and significantly alters the optical characteristics of the TiO2/clay composite.

Evaluation of the Morphology and Osteogenic Potential of Titania-Based Electrospun Nanofibers

Directory of Open Access Journals (Sweden)

Xiaokun Wang

2012-01-01

Full Text Available Submicron-scale titania-based ceramic fibers with various compositions have been prepared by electrospinning. The as-prepared nanofibers were heat-treated at 700°C for 3 h to obtain pure inorganic fiber meshes. The results show that the diameter and morphology of the nanofibers are affected by starting polymer concentration and sol-gel composition. The titania and titania-silica nanofibers had the average diameter about 100–300 nm. The crystal phase varied from high-crystallized rutile-anatase mixed crystal to low-crystallized anatase with adding the silica addition. The morphology and crystal phase were evaluated by SEM and XRD. Bone-marrow-derived mesenchymal stem cells were seeded on titania-silica 50/50 fiber meshes. Cell number and early differentiation marker expressions were analyzed, and the results indicated osteogenic potential of the titania-silica 50/50 fiber meshes.

Barrier pillar between production panels in coal mine

Energy Technology Data Exchange (ETDEWEB)

Zingano, Andre Cezar; Koppe, Jair Carlos; Costa, Joao Felipe C.L. [Universidade Federal do Rio Grande do Sul, Porto Alegre (Brazil)

2007-07-01

The function of the barrier pillar is to protect the mining panel in activity from the abutment load of adjacent mining panels that were mined. In the case of underground mines in Santa Catarina State, the barrier pillar has functioned to protect the main entries of the mine against pillar failure from old mining panels. The objective of this paper is to verify the application of the empirical method to design barrier pillars as proposed by Peng (1986), using numerical simulation following the mining geometry of the coal mines in Santa Catarina State. Two-dimensional numerical models were built taking into account the geometry of the main entries and mining panels for different overburden thickness, and considering the geomechanical properties for the rock mass that forms the roof-pillar-floor system for the Bonito coal vein. The results of the simulations showed that the empirical method to determine the barrier pillar width is valid for the studied coal vein and considered mine geometry. Neither did the pillar at the main entry become overstressed due to adjacent mine panels, nor did the roof present any failure due to stress redistribution. 9 refs., 6 figs., 5 tabs.

Periodically structured Si pillars for high-performing heterojunction photodetectors

Science.gov (United States)

Melvin David Kumar, M.; Yun, Ju-Hyung; Kim, Joondong

2015-03-01

A periodical array of silicon (Si) micro pillar structures was fabricated on Si substrates using PR etching process. Indium tin oxide (ITO) layer of 80 nm thickness was deposited over patterned Si substrates so as to make ITO/n-Si heterojunction devices. The influences of width and period of pillars on the optical and electrical properties of prepared devices were investigated. The surface morphology of the Si substrates revealed the uniform array of pillar structures. The 5/10 (width/period) Si pillar pattern reduced the optical reflectance to 6.5% from 17% which is of 5/7 pillar pattern. The current rectifying ratio was found higher for the device in which the pillars are situated in optimum periods. At both visible (600 nm) and near infrared (900 nm) range of wavelengths, the 5/7 and 5/10 pillar patterned device exhibited the better photoresponses which are suitable for making advanced photodetectors. This highly transmittance and photoresponsive pillar patterned Si substrates with an ITO layer would be a promising device for various photoelectric applications.

Preparation and bioactivity evaluation of hydroxyapatite-titania/chitosan-gelatin polymeric biocomposites

International Nuclear Information System (INIS)

Mohamed, Khaled R.; Mostafa, Amani A.

2008-01-01

Biocomposites consisting of hydroxyapatite (HA) and natural polymers such as collagen, chitosan, chitin,and gelatin have been extensively investigated. However, studies on the combination of HA and titania with chitosan and gelatin have not been conducted yet. Novel biodegradable hydroxyapatite-titania/chitosan-gelatin polymeric composites were fabricated. In this work, our results are concerning with the preparation and characterization of HA powder and HA filler containing titania powder (10 and 30%) with a chitosan and gelatin copolymer matrix. The present research focuses on characterizing the structure of this novel class of biocomposites. Thermogravimetric analysis (TGA), X-ray diffraction (XRD), and Fourier Transformed Infrared Spectroscopy (FT-IR), Scanning electron microscopy (SEM-EDAX) were employed to assess the produced composites. The mechanical properties in terms of compressive strength and hardness test were also investigated. The in vitro study in simulated body fluid (SBF) was performed to assess the bioactivity of composites. The results proved that apatite resembling natural bone are formed faster and greater in the case the composite of HA containing 10% titania into chitosan-gelatin polymeric matrix when they are soaked in a simulated body fluid (SBF) than the composite containing 30% titania. The biocomposites containing HA with 10% titania are expected to be attractive for bioapplications as bone substitutes and scaffolds for tissue engineering in future

Coal pillar design procedures

CSIR Research Space (South Africa)

York, G

2000-03-01

Full Text Available Final Project Report Coal pillar design procedures G. York, I. Canbulat, B.W. Jack Research agency: CSIR Mining Technology Project number: COL 337 Date: March 2000 2 Executive Summary Examination of collapsed pillar cases outside of the empirical... in strength occurs with increasing specimen size. 45 40 35 30 25 20 15 10 5 0 20 40 60 80 100 120 140 160 UNIAX IA L COMPR EHEN SIV E S TR ENG TH (M Pa ) CUBE SIZE (cm) Figure 1...

Three Philosophical Pillars That Support Collaborative Learning.

Science.gov (United States)

Maltese, Ralph

1991-01-01

Discusses three philosophical pillars that support collaborative learning: "spaces of appearance," active engagement, and ownership. Describes classroom experiences with collaborative learning supported by these pillars. (PRA)

Hydroxyapatite nucleated and grown on nano titania particles enhances recruitment of Escherichia coli for subsequent photocatalytic elimination

International Nuclear Information System (INIS)

Huang, Jing; Liu, Yi; Liu, Yuxin; Li, Hua

2015-01-01

Titania-hydroxyapatite (HA) nanocomposites were fabricated by wet chemical synthesis approach. HA exhibited crystallographic orientation of nucleation on nano titania particle, forming the composite particles with titania being partially enwrapped with HA. Microstructural characterization by high resolution transmission electron microscopy revealed coherent interfacial bond of (110) and (222) planes of HA crystal with (101) plane of anatase. The HA layer promoted significantly recruitment of Escherichia coli bacteria onto the titania-based particles for subsequent photocatalytic killing. Less extent of enwrapping of HA on titania particle, as accomplished by increasing the aging time of HA suspension, gave rise to better capability of photocatalytic degradation of methylene blue and sterilization of the bacteria. The novel HA-enwrapped titania powder shows great potential for environmental applications. - Highlights: • Titania-hydroxyapatite nanocomposite powder was fabricated with cladding structure. • Hydroxyapatite nucleated and grew on titania particle with preferred orientation. • Hydroxyapatite layer promotes recruitment of Escherichia coli onto titania-based particles. • The titania-hydroxyapatite particles show excellent antibacterial performances. • The nanocomposite powder exhibits excellent photocatalytic performances

Hydroxyapatite nucleated and grown on nano titania particles enhances recruitment of Escherichia coli for subsequent photocatalytic elimination

Energy Technology Data Exchange (ETDEWEB)

Huang, Jing; Liu, Yi; Liu, Yuxin; Li, Hua, E-mail: lihua@nimte.ac.cn

2015-02-01

Titania-hydroxyapatite (HA) nanocomposites were fabricated by wet chemical synthesis approach. HA exhibited crystallographic orientation of nucleation on nano titania particle, forming the composite particles with titania being partially enwrapped with HA. Microstructural characterization by high resolution transmission electron microscopy revealed coherent interfacial bond of (110) and (222) planes of HA crystal with (101) plane of anatase. The HA layer promoted significantly recruitment of Escherichia coli bacteria onto the titania-based particles for subsequent photocatalytic killing. Less extent of enwrapping of HA on titania particle, as accomplished by increasing the aging time of HA suspension, gave rise to better capability of photocatalytic degradation of methylene blue and sterilization of the bacteria. The novel HA-enwrapped titania powder shows great potential for environmental applications. - Highlights: • Titania-hydroxyapatite nanocomposite powder was fabricated with cladding structure. • Hydroxyapatite nucleated and grew on titania particle with preferred orientation. • Hydroxyapatite layer promotes recruitment of Escherichia coli onto titania-based particles. • The titania-hydroxyapatite particles show excellent antibacterial performances. • The nanocomposite powder exhibits excellent photocatalytic performances.

Adsorption of vitamin E on mesoporous titania nanocrystals

Energy Technology Data Exchange (ETDEWEB)

Shih, C.J., E-mail: cjshih@kmu.edu.tw [Department of Fragrance and Cosmetic Science, Kaohsiung Medical University, Kaohsiung 807, Taiwan (China); Lin, C.T.; Wu, S.M. [School of Pharmacy, College of Pharmacy, Kaohsiung Medical University, Kaohsiung 807, Taiwan (China)

2010-07-15

Tri-block nonionic surfactant and titanium chloride were used as starting materials for the synthesis of mesoporous titania nanocrystallite powders. The main objective of the present study was to examine the synthesis of mesoporous titania nanocrystals and the adsorption of vitamin E on those nanocrystals using X-ray diffraction (XRD), transmission electron microscopy, and nitrogen adsorption and desorption isotherms. When the calcination temperature was increased to 300 {sup o}C, the reflection peaks in the XRD pattern indicated the presence of an anatase phase. The crystallinity of the nanocrystallites increased from 80% to 98.6% with increasing calcination temperature from 465 {sup o}C to 500 {sup o}C. The N{sub 2} adsorption data and XRD data taken after vitamin E adsorption revealed that the vitamin E molecules were adsorbed in the mesopores of the titania nanocrystals.

Preparation of nitrogen-doped titania using sol-gel technique and its photocatalytic activity

International Nuclear Information System (INIS)

Qin Haoli; Gu Guobang; Liu Song

2008-01-01

Yellowish nitrogen-doped titania was produced through sol-gel method at room temperature, with the elemental nitrogen derived from aqua ammonia. The titania catalysts were characterized using TG-DSC, XRD, BET, TEM, and UV-vis diffuse reflectance spectrophotometer. Methyl orange (MO) and 2-mercaptobenzothiazole (MBT) were used in this study as model chemicals and both the adsorption isotherm and photocatalytic activity of the nitrogen-doped titania catalysts were evaluated based on the MO and MBT photodegradation in aqueous solution under UV and visible light, respectively. The results showed that all titania catalysts were anatase. The crystallite size of nitrogen-doped ones increased with the increase of N/Ti proportion, both the adsorption capacity and adsorption equilibrium constants of the nitrogen-doped titania catalysts were improved by the doping of nitrogen. The doping of nitrogen could extend the absorption shoulder into the visible-light region, thus nitrogen-doped titania possessed visible-light activity illustrated by that higher capability of degradation of MO and MBT under the irradiation of visible light, whereas the pure ones showed little such kind of visible-light activity. The kinetics of the MO and MBT photodegradation using different nitrogen-doped titania were also studied, the experiments demonstrated that there was an optimum N/Ti proportion of 4 mol% to exhibit the highest visible-light activity. The UV activity of nitrogen-doped titania catalysts were worse than that of the pure one and Degussa P-25. In addition, nitrogen-doped titania had weakened appreciably activity in the visible-light region as the N/Ti proportion increased, while a reverse relationship exists for the UV light. It was concluded that the enhancement of MO and MBT photodegradation using the nitrogen-doped titania catalysts mainly involved in both the improvement of the organic substrate adsorption in catalysts suspension and the enhancement of the separation of electron

Biological performance of titania containing phosphate-based glasses for bone tissue engineering applications

International Nuclear Information System (INIS)

Abou Neel, Ensanya Ali; Chrzanowski, Wojciech; Knowles, Jonathan Campbell

2014-01-01

The interplay between glass chemistry, structure, degradation kinetics, and biological activity provides flexibility for the development of scaffolds with highly specific cellular response. The aim of this study was therefore to investigate the role of titania inclusion into the phosphate-based glass on its ability to stimulate osteoblast-like human osteosarcoma (HOS) cells to adhere, proliferate and differentiate. In depth morphological and biochemical characterisation was performed on HOS cells cultured on the surface of glass discs. Cell proliferation was also studied in the presence of the glass extract. Cell differentiation, through osteoblast phenotype genes, alkaline phosphatase (ALP) activity and osteocalcin production, was carried out using normal or osteogenic media. Both Thermanox® and titania free glass were used as controls. The data demonstrated that titania inclusion provides desired cytocompatible surface that supported initial cell attachment, sustained viability, and increased cell proliferation similar or significantly higher than Thermanox®. The modified glasses regulated osteoblastic cell differentiation as detected by osteoblast phenotype gene transcription and upregulated ALP and osteocalcin expression. Using osteogenic media had no significant effect on ALP activity and osteocalcin expression. Therefore, titania modified phosphate glasses may have future use as bone tissue engineering scaffolds. - Highlights: • This study investigated the role of titania on the biological response of phosphate glasses. • Incorporation of titania improved HOS cell attachment, viability and proliferation. • Titania modified glasses regulated osteoblastic cell differentiation. • Using osteogenic media had no significant effect on cell differentiation. • Titania modified glasses may have future use as bone tissue engineering scaffolds

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

Hydrogen gas sensing feature of polyaniline/titania (rutile) nanocomposite at environmental conditions

Energy Technology Data Exchange (ETDEWEB)

Milani Moghaddam, Hossain, E-mail: hossainmilani@yahoo.com [Solid State Physics Department, University of Mazandaran, Babolsar (Iran, Islamic Republic of); Nasirian, Shahruz [Solid State Physics Department, University of Mazandaran, Babolsar (Iran, Islamic Republic of); Basic Sciences Department, Mazandaran University of Science and Technology, Babol (Iran, Islamic Republic of)

2014-10-30

Graphical abstract: - Highlights: • Polyaniline/titania (rutile) nanocomposite (TPNC) was synthesized by a chemical oxidative polymerization method. • Surface morphology and titania (rutile) wt% in TPNC sensors were significant factors for H{sub 2} gas sensing. • TPNC sensors could be used for H{sub 2} gas sensing at different R.H. humidity. • TPNC Sensors exhibited considerable sensitive, reversible and repeatable response to H{sub 2} gas at environmental conditions. - Abstract: The resistance-based sensors of polyaniline/titania (rutile) nanocomposite (TPNC) were prepared by spin coating technique onto an epoxy glass substrate with Cu-interdigited electrodes to study their hydrogen (H{sub 2}) gas sensing features. Our findings are that the change of the surface morphology, porosity and wt% of titania in TPNCs have a significant effect on H{sub 2} gas sensing of sensors. All of the sensors had a reproducibility response toward 0.8 vol% H{sub 2} gas at room temperature, air pressure and 50% relative humidity. A sensor with 40 wt% of titania nanoparticles had better response/recovery time and the response than other sensors. Moreover, H{sub 2} gas sensing mechanism of TPNC sensors based contact areas and the correlation of energy levels between PANI chains and the titania grains were studied.

Performance engineering of dye sensitized solar cells (DSSC) using Ag modified titania as photoanode

Science.gov (United States)

Nair, Ranjith G.; Mathan Kumar, P.; Samdarshi, S. K.

2018-01-01

Present work reports the fabrication of silver (Ag) modified titania photoanode as an efficient photoanode for Dye Sensitized Solar Cell (DSSC). Pristine and Ag modified Titania nanomaterials were prepared using sol gel method. The structural analyses confirm the high crystallinity of the samples with crystallite size distribution in nanorange. TEM micrograph confirms that the synthesized nanomaterials are in uniform size. A red shift is observed in the UV DRS spectra compared to pristine Titania and which confirm the incorporation of Ag inside titania. A prototype DSSC was fabricated using the pristine and modified Titania as photoanode, Ruthenium dye as sensitizer, I-/I-3 as redox electrolyte and platinum counter electrode. The cell with Ag modified titania photoanode showed 15 times enhanced photoconversion efficiency (PCE) than the pristine one. This improved performance of the Ag modified DSSC can be ascribed to reduced recombination and improved charge carrier transport of electrons/holes at the interfaces.

Deformation-driven diffusion and plastic flow in amorphous granular pillars.

Science.gov (United States)

Li, Wenbin; Rieser, Jennifer M; Liu, Andrea J; Durian, Douglas J; Li, Ju

2015-06-01

We report a combined experimental and simulation study of deformation-induced diffusion in compacted quasi-two-dimensional amorphous granular pillars, in which thermal fluctuations play a negligible role. The pillars, consisting of bidisperse cylindrical acetal plastic particles standing upright on a substrate, are deformed uniaxially and quasistatically by a rigid bar moving at a constant speed. The plastic flow and particle rearrangements in the pillars are characterized by computing the best-fit affine transformation strain and nonaffine displacement associated with each particle between two stages of deformation. The nonaffine displacement exhibits exponential crossover from ballistic to diffusive behavior with respect to the cumulative deviatoric strain, indicating that in athermal granular packings, the cumulative deviatoric strain plays the role of time in thermal systems and drives effective particle diffusion. We further study the size-dependent deformation of the granular pillars by simulation, and find that different-sized pillars follow self-similar shape evolution during deformation. In addition, the yield stress of the pillars increases linearly with pillar size. Formation of transient shear lines in the pillars during deformation becomes more evident as pillar size increases. The width of these elementary shear bands is about twice the diameter of a particle, and does not vary with pillar size.

Mechanical properties of pillared-graphene nanostructures using molecular dynamics simulations

International Nuclear Information System (INIS)

Wang, Chih-Hao; Fang, Te-Hua; Sun, Wei-Li

2014-01-01

The deformation behaviour and mechanical properties of three-dimensional (3D) pillared graphene are investigated using molecular dynamics simulations. The Tersoff–Brenner many-body potential model is employed to evaluate the interactions between 3D pillared-graphene carbon atoms and nanotube carbons. The Lennard-Jones potential model is used to compute the interactions between a conical indenter and 3D pillared-graphene carbon atoms. The effects of the size and geometric structure of 3D pillared-graphene are evaluated in terms of the indentation force and contact stiffness. The simulation results for an armchair nanotube of 3D pillared graphene show that the contact stiffness increases with increasing chiral vector of the 3D-pillared graphene. However, the adhesive force sharply decreases with increasing chiral vector of the 3D-pillared graphene. A zigzag nanotube of 3D-pillared graphene exhibits better mechanical properties compared with those of the armchair nanotube. (paper)

Iron on mixed zirconia-titania substrate F-T catalyst

International Nuclear Information System (INIS)

Dyer, P.N.; Nordquist, A.F.; Pierantozzi, R.

1988-01-01

This patent deals with a Fischer-Tropsch catalyst comprising iron co-deposited with or deposited on particles comprising a mixture of zirconia and titania, preferably formed by co-precipitation of compounds convertible to zirconia and titania, such as zirconium and titanium alkoxide. The invention also comprises the method of making this catalyst and an improved Fischer-Tropsch reaction process in which the catalyst is utilized

PEDOT pillar fabrication using DOD inkjet system

Science.gov (United States)

Cui, Wei; Chang, Cheng-Ling; Wang, Wei-Chih

2012-04-01

In this paper, we present our preliminary results of high aspect ratio 3D PEDOT pillar study by drop-on demand (DOD) direct printing system. Design of the experimental setup and the fabrication of the DOD PEDOT pillar are introduced. Currently, the system can achieve a PEDOT pillar with a height of 300 μm and 80 μm in diameter. The proposed PEDOT 3D printing process has a wide range of potential applications in the eletronics and display industry.

Macrostructure-dependent photocatalytic property of high-surface-area porous titania films

Energy Technology Data Exchange (ETDEWEB)

Kimura, T., E-mail: t-kimura@aist.go.jp [Advanced Manufacturing Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Shimoshidami, Moriyama-ku, Nagoya 463-8560 (Japan)

2014-11-01

Porous titania films with different macrostructures were prepared with precise control of condensation degree and density of the oxide frameworks in the presence of spherical aggregates of polystyrene-block-poly(oxyethylene) (PS-b-PEO) diblock copolymer. Following detailed explanation of the formation mechanisms of three (reticular, spherical, and large spherical) macrostructures by the colloidal PS-b-PEO templating, structural variation of the titania frameworks during calcination were investigated by X-ray diffraction and X-ray photoelectron spectroscopy. Then, photocatalytic performance of the macroporous titania films was evaluated through simple degradation experiments of methylene blue under an UV irradiation. Consequently, absolute surface area of the film and crystallinity of the titania frameworks were important for understanding the photocatalytic performance, but the catalytic performance can be improved further by the macrostructural design that controls diffusivity of the targeted molecules inside the film and their accessibility to active sites.

Macrostructure-dependent photocatalytic property of high-surface-area porous titania films

Directory of Open Access Journals (Sweden)

T. Kimura

2014-11-01

Full Text Available Porous titania films with different macrostructures were prepared with precise control of condensation degree and density of the oxide frameworks in the presence of spherical aggregates of polystyrene-block-poly(oxyethylene (PS-b-PEO diblock copolymer. Following detailed explanation of the formation mechanisms of three (reticular, spherical, and large spherical macrostructures by the colloidal PS-b-PEO templating, structural variation of the titania frameworks during calcination were investigated by X-ray diffraction and X-ray photoelectron spectroscopy. Then, photocatalytic performance of the macroporous titania films was evaluated through simple degradation experiments of methylene blue under an UV irradiation. Consequently, absolute surface area of the film and crystallinity of the titania frameworks were important for understanding the photocatalytic performance, but the catalytic performance can be improved further by the macrostructural design that controls diffusivity of the targeted molecules inside the film and their accessibility to active sites.

Single and multi-component adsorption of salicylic acid, clofibric acid, carbamazepine and caffeine from water onto transition metal modified and partially calcined inorganic-organic pillared clay fixed beds.

Science.gov (United States)

Cabrera-Lafaurie, Wilman A; Román, Félix R; Hernández-Maldonado, Arturo J

2015-01-23

Fixed-beds of transition metal (Co(2+), Ni(2+) or Cu(2+)) inorganic-organic pillared clays (IOCs) were prepared to study single- and multi-component non-equilibrium adsorption of a set of pharmaceutical and personal care products (PPCPs: salicylic acid, clofibric acid, carbamazepine and caffeine) from water. Adsorption capacities for single components revealed that the copper(II) IOCs have better affinity toward salicylic and clofibric acid. However, multi-component adsorption tests showed a considerable decrease in adsorption capacity for the acids and an unusual selectivity toward carbamazepine depending on the transition metal. This was attributed to a combination of competition between PPCPs for adsorption sites, adsorbate-adsorbate interactions, and plausible pore blocking caused by carbamazepine. The cobalt(II) IOC bed that was partially calcined to fractionate the surfactant moiety showcased the best selectivity toward caffeine, even during multi-component adsorption. This was due to a combination of a mildly hydrophobic surface and interaction between the PPCP and cobalt(II). In general, the tests suggest that these IOCs may be a potential solution for the removal of PPCPs if employed in a layered-bed configuration, to take care of families of adsorbates in a sequence that would produce sharpened concentration wavefronts. Copyright © 2014 Elsevier B.V. All rights reserved.

Hydrogen gas sensing feature of polyaniline/titania (rutile) nanocomposite at environmental conditions

Science.gov (United States)

Milani Moghaddam, Hossain; Nasirian, Shahruz

2014-10-01

The resistance-based sensors of polyaniline/titania (rutile) nanocomposite (TPNC) were prepared by spin coating technique onto an epoxy glass substrate with Cu-interdigited electrodes to study their hydrogen (H2) gas sensing features. Our findings are that the change of the surface morphology, porosity and wt% of titania in TPNCs have a significant effect on H2 gas sensing of sensors. All of the sensors had a reproducibility response toward 0.8 vol% H2 gas at room temperature, air pressure and 50% relative humidity. A sensor with 40 wt% of titania nanoparticles had better response/recovery time and the response than other sensors. Moreover, H2 gas sensing mechanism of TPNC sensors based contact areas and the correlation of energy levels between PANI chains and the titania grains were studied.

Further validation of bracket pillar design methodology

CSIR Research Space (South Africa)

Vieira, F

1998-07-01

Full Text Available Design charts for bracket pillar design were developed under a previous SIMRAC project GAP 223 to provide rock mechanics engineers with an initial estimate of bracket pillar sizes for clearly identified geological discontinuities, based on mining...

Capabilities: Science Pillars

Science.gov (United States)

Alamos National Laboratory Delivering science and technology to protect our nation and promote world stability Science & Innovation Collaboration Careers Community Environment Science & Innovation Facilities Science Pillars Research Library Science Briefs Science News Science Highlights Lab Organizations

Chirality of Single-Handed Twisted Titania Tubular Nanoribbons Prepared Through Sol-gel Transcription.

Science.gov (United States)

Wang, Sibing; Zhang, Chuanyong; Li, Yi; Li, Baozong; Yang, Yonggang

2015-08-01

Single-handed twisted titania tubular nanoribbons were prepared through sol-gel transcription using a pair of enantiomers. Handedness was controlled by that of the template. The obtained samples were characterized using field-emission electron microscopy, transmission electron microscopy, diffuse reflectance circular dichroism (DRCD), and X-ray diffraction. The DRCD spectra indicated that the titania nanotubes exhibit optical activity. Although the tubular structure was destroyed after being calcined at 700 °C for 2.0 h, DRCD signals were still identified. However, the DRCD signals disappeared after being calcined at 1000 °C for 2.0 h. The optical activity of titania was proposed to be due to chiral defects. Previous results showed that straight titania tubes could be used as asymmetric autocatalysts, indicating that titania exhibit chirality at the angstrom level. Herein, it was found that they also exhibit DRCD signals, indicating that there are no obvious relationships between morphology at the nano level and chirality at the angstrom level. The nanotube chirality should originate from the chiral defects on the nanotube inner surface. The Fourier transform infrared spectra indicated that the chirality of the titania was transferred from the gelators through the hydrogen bonding between N-H and Ti-OH. © 2015 Wiley Periodicals, Inc.

The Effect of Titanium Tetrahedral Coordination of Silica-Titania Catalyst on the Physical Properties of Biodiesel

Science.gov (United States)

Nizar, U. K.; Hidayatul, J.; Sundari, R.; Bahrizal, B.; Amran, A.; Putra, A.; Latisma DJ, L.; Dewata, I.

2018-04-01

This study investigates the correlation of the number of titanium tetrahedral coordination and biodiesel production. The solid-state method has been used to synthesis of silica-titania catalyst for biodiesel production, which the precursors, i.e. silica and titania commercials were heated in the temperature range of 450 - 550°C. The characterization of the prepared silica-titania has been studied by FTIR and DR UV-Vis in order to identify and calculate the presence of titanium tetrahedral coordination in silica-titania catalyst. A very small peak at around 950 cm-1 indicated the presence of titanium tetrahedral coordination through Si–O–Ti bonds. Deconvolution of DR UV-Vis spectra showed the coordination of titanium in silica-titania is more octahedral. However, the number of titanium tetrahedral coordination of the prepared silica-titania is found higher than that of TiO2 commercial. The increasing of titanium tetrahedral fraction in silica-titania affects the physical properties of biodiesel in terms of boiling point, viscosity and density, which is produced by the reaction of methanol and palm oil.

Band Gap Engineering of Titania Systems Purposed for Photocatalytic Activity

Science.gov (United States)

Thurston, Cameron

Ab initio computer aided design drastically increases candidate population for highly specified material discovery and selection. These simulations, carried out through a first-principles computational approach, accurately extrapolate material properties and behavior. Titanium Dioxide (TiO2 ) is one such material that stands to gain a great deal from the use of these simulations. In its anatase form, titania (TiO2 ) has been found to exhibit a band gap nearing 3.2 eV. If titania is to become a viable alternative to other contemporary photoactive materials exhibiting band gaps better suited for the solar spectrum, then the band gap must be subsequently reduced. To lower the energy needed for electronic excitation, both transition metals and non-metals have been extensively researched and are currently viable candidates for the continued reduction of titania's band gap. The introduction of multicomponent atomic doping introduces new energy bands which tend to both reduce the band gap and recombination loss. Ta-N, Nb-N, V-N, Cr-N, Mo-N, and W-N substitutions were studied in titania and subsequent energy and band gap calculations show a favorable band gap reduction in the case of passivated systems.

Discussing three pillars of corporate governance

OpenAIRE

Andrei STĂNCULESCU; Eugen MITRICĂ

2015-01-01

This paper is a meaningful attempt to critically analyze the cohesion and relationship between three fundamental pillars of the corporate governance system: the shareholders, the board of directors and the employees. We present the characteristics of each pillar and discuss its relevance in corporate governance. A couple of world-renowned corporate governance models are considered. A synthetic conclusion is drawn based on information presented.

Vapor phase modification of sol-gel derived titania (TiO{sub 2}) surfaces

Energy Technology Data Exchange (ETDEWEB)

Piwonski, Ireneusz [University of Lodz, Department of Chemical Technology and Environmental Protection, Pomorska 163, 90-236 Lodz (Poland)]. E-mail: irek@uni.lodz.pl; Ilik, Aneta [University of Lodz, Department of Chemical Technology and Environmental Protection, Pomorska 163, 90-236 Lodz (Poland)

2006-12-30

Chemical vapor deposition (CVD) method was used in titania surface modification. Titania layers were obtained in sol-gel process and prepared as thin films on silicon wafers in dip-coating method. In order to define the influence of modification on titania surface properties (e.g., friction), various types of fluoroalkylsilanes were used. The effectiveness of the modification was monitored by FT-IR spectroscopy. The topography and frictional measurements were investigated with the use of atomic force microscopy (AFM)

Suspension of Water Droplets on Individual Pillars

DEFF Research Database (Denmark)

Tóth, T.; Ferraro, D.; Chiarello, E.

2011-01-01

We report results of extensive experimental and numerical studies on the suspension of water drops deposited on cylindrical pillars having circular and square cross sections and different wettabilities. In the case of circular pillars, the drop contact line is pinned to the whole edge contour unt...

Merensky pillar strength formulae based on back-analysis of pillar failures at Impala Platinum

CSIR Research Space (South Africa)

Watson, BP

2008-08-01

Full Text Available , with and without a large flanking area of mining. Such factors were generally less than 1.2 (20% correction), and were, where feasible, checked using Equation [1]4. This equation may be used if there is a large sea of mining with roughly uniform convergence... for pillars that are allowed to punch, as well as for pillars that are surrounded by an infinitely strong rock mass; high density mesh and varying brittleness Table IV Material and model properties �3 Co �0 �res �pr �0 �res (MPa) (MPa) (m�) A 2 15 55 50...

Sustainable steric stabilization of colloidal titania nanoparticles

Science.gov (United States)

Elbasuney, Sherif

2017-07-01

A route to produce a stable colloidal suspension is essential if mono-dispersed particles are to be successfully synthesized, isolated, and used in subsequent nanocomposite manufacture. Dispersing nanoparticles in fluids was found to be an important approach for avoiding poor dispersion characteristics. However, there is still a great tendency for colloidal nanoparticles to flocculate over time. Steric stabilization can prevent coagulation by introducing a thick adsorbed organic layer which constitutes a significant steric barrier that can prevent the particle surfaces from coming into direct contact. One of the main features of hydrothermal synthesis technique is that it offers novel approaches for sustainable nanoparticle surface modification. This manuscript reports on the sustainable steric stabilization of titanium dioxide nanoparticles. Nanoparticle surface modification was performed via two main approaches including post-synthesis and in situ surface modification. The tuneable hydrothermal conditions (i.e. temperature, pressure, flow rates, and surfactant addition) were optimized to enable controlled steric stabilization in a continuous fashion. Effective post synthesis surface modification with organic ligand (dodecenyl succinic anhydride (DDSA)) was achieved; the optimum surface coating temperature was reported to be 180-240 °C to ensure DDSA ring opening and binding to titania nanoparticles. Organic-modified titania demonstrated complete change in surface properties from hydrophilic to hydrophobic and exhibited phase transfer from the aqueous phase to the organic phase. Exclusive surface modification in the reactor was found to be an effective approach; it demonstrated surfactant loading level 2.2 times that of post synthesis surface modification. Titania was also stabilized in aqueous media using poly acrylic acid (PAA) as polar polymeric dispersant. PAA-titania nanoparticles demonstrated a durable amorphous polymeric layer of 2 nm thickness. This

The Three Pillars of Machine Programming

OpenAIRE

Gottschlich, Justin; Solar-Lezama, Armando; Tatbul, Nesime; Carbin, Michael; Rinard, Martin; Barzilay, Regina; Amarasinghe, Saman; Tenenbaum, Joshua B; Mattson, Tim

2018-01-01

In this position paper, we describe our vision of the future of machine programming through a categorical examination of three pillars of research. Those pillars are: (i) intention, (ii) invention, and(iii) adaptation. Intention emphasizes advancements in the human-to-computer and computer-to-machine-learning interfaces. Invention emphasizes the creation or refinement of algorithms or core hardware and software building blocks through machine learning (ML). Adaptation emphasizes advances in t...

Facile synthesis of hierarchical nanostructured rutile titania for lithium-ion battery

International Nuclear Information System (INIS)

Fei Hailong; Wei Mingdeng

2011-01-01

Highlights: → Rutile TiO 2 sub-microflowers and sub-microspheres with different building blocks as anode materials of lithium-ion battery. → Controllable morphologies with oxalic acid by the hydrothermal technique. → Sub-microflower and sub-microspheres constructed by well organized nanorods exhibited high capacity and good cycle stability. → Small size building blocks nanorods enhance the transfer rate of Li-ion. - Abstract: A facile hydrothermal method is developed to prepare rutile titania sub-microflowers consisting of nanorods with oxalic acid and TiOSO 4 as reagents. The diameter of sub-microflowers and nanorods is found to be ca. 800 and 40 nm, respectively. Also, the shape and size of building blocks in rutile titania sub-microflowers can be considerably controlled via adjusting the reaction time and reactant amounts. Rutile titania sub-microflowers composed of nanorods display higher discharge capacity and better rate cycle stability than other rutile titania nanostructures as lithium-ion battery anode material due to enhancing the Li-ion transfer rate for small size building blocks.

Solventless acid-free synthesis of mesostructured titania: Nanovessels for metal complexes and metal nanoclusters

Energy Technology Data Exchange (ETDEWEB)

Dag, Oe.; Celik, Oe.; Ozin, G.A. [Department of Chemistry, Bilkent University, 06533 Ankara (Turkey); Soten, I.; Polarz, S.; Coombs, N. [Materials Chemistry Research Group, Chemistry Department, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6 (Canada)

2003-01-01

A new and highly reproducible method to obtain mesostructured titania materials is introduced in this contribution. The mesostructured titania is obtained by employing self-assembled structures of non-ionic alkyl-poly(ethylene oxide) surfactants as templates. The materials are produced without additional solvents such as alcohols, or even water. Only the titanium(IV) ethoxide and the surfactant (C{sub 12}EO{sub 10}) are needed. Water, in the form of that attached to the surfactant and from the atmosphere, induces growth of titania nanoclusters in the synthesis sol. It is indicated that these nanoclusters interact with the surfactant EO-head groups to form a new titanotropic amphiphile. The new amphiphiles self-assemble into titanium nanocluster-surfactant hybrid lyotropic phases, which are transformed to the final mesostructured materials by further condensation of the titania network. The titania materials can be obtained also with noble-metal particles immobilized in the mesostructured framework. It is seen that when different metal salts are used as the metal precursors, different interactions with the titania walls are found. The materials are characterized by X-ray diffraction (XRD), polarization optical microscopy (POM), transmission electron microscopy (TEM), UV-vis spectroscopy, and micro-Raman analysis. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

POROUS MEMBRANE TEMPLATED SYNTHESIS OF POLYMER PILLARED LAYER

Institute of Scientific and Technical Information of China (English)

Zhong-wei Niu; Dan Li; Zhen-zhong Yang

2003-01-01

The anodic porous alumina membranes with a definite pore diameter and aspect ratio were used as templates to synthesize polymer pillared layer structures. The pillared polymer was produced in the template membrane pores, and the layer on the template surfaces. Rigid cured epoxy resin, polystyrene and soft hydrogel were chosen to confirm the methodology. The pillars were in the form of either tubes or fibers, which were controlled by the alumina membrane pore surface wettability. The structural features were confirmed by scanning electron microscopy results.

Mixed conductivity, structural and microstructural characterization of titania-doped yttria tetragonal zirconia polycrystalline/titania-doped yttria stabilized zirconia composite anode matrices

International Nuclear Information System (INIS)

Colomer, M.T.; Maczka, M.

2011-01-01

Taking advantage of the fact that TiO 2 additions to 8YSZ cause not only the formation of a titania-doped YSZ solid solution but also a titania-doped YTZP solid solution, composite materials based on both solutions were prepared by solid state reaction. In particular, additions of 15 mol% of TiO 2 give rise to composite materials constituted by 0.51 mol fraction titania-doped yttria tetragonal zirconia polycrystalline and 0.49 mol fraction titania-doped yttria stabilized zirconia (0.51TiYTZP/0.49TiYSZ). Furthermore, Y 2 (Ti 1-y Zr y ) 2 O 7 pyrochlore is present as an impurity phase with y close to 1, according to FT-Raman results. Lower and higher additions of titania than that of 15 mol%, i.e., x=0, 5, 10, 20, 25 and 30 mol% were considered to study the evolution of 8YSZ phase as a function of the TiO 2 content. Furthermore, zirconium titanate phase (ZrTiO 4 ) is detected when the titania content is equal or higher than 20 mol% and this phase admits Y 2 O 3 in solid solution according to FE-SEM-EDX. The 0.51TiYTZP/0.49TiYSZ duplex material was selected in this study to establish the mechanism of its electronic conduction under low oxygen partial pressures. In the pO 2 range from 0.21 to 10 -7.5 atm. the conductivity is predominantly ionic and constant over the range and its value is 0.01 S/cm. The ionic plus electronic conductivity is 0.02 S/cm at 1000 o C and 10 -12.3 atm. Furthermore, the onset of electronic conductivity under reducing conditions exhibits a -1/4 pO 2 dependence. Therefore, it is concluded that the n-type electronic conduction in the duplex material can be due to a small polaron-hopping between Ti 3+ and Ti 4+ . -- Graphical abstract: FE-SEM micrograph of a polished and thermal etched surface of a Ti-doped YTZP/Ti-doped YSZ composite material. Display Omitted Research highlights: → Ti-doped YTZP/Ti-doped YSZ composite materials are mixed conductors under low partial pressures. → From 5 mol% of TiO 2 , Y 2 (Ti 1-y ,Zr y ) 2 O 7 pyrochlore is

Photocatalytic composites based on titania nanoparticles and carbon nanomaterials

International Nuclear Information System (INIS)

Nguyen, Bich Ha; Nguyen, Van Hieu; Vu, Dinh Lam

2015-01-01

In this article we present a review on recent experimental works toward the formation of visible light responsive composite photocatalysts on the basis of titania nanoparticles and carbon nanomaterials of different types. The research results achieved in last years has shown that the nanocomposite photocatalysts comprising titania nanoparticles and graphene or graphene oxide sheets, and also nanoparticles of noble metals and metallic oxides, exhibited the evident priority compared to the others. Therefore our review emphasizes the research on these promising visible light responsive nanophotocatalysts. (review)

Removal of nitrate by zero-valent iron and pillared bentonite

International Nuclear Information System (INIS)

Li Jianfa; Li Yimin; Meng Qingling

2010-01-01

The pillared bentonite prepared by intercalating poly(hydroxo Al(III)) cations into bentonite interlayers was used together with Fe(0) for removing nitrate in column experiments. The obvious synergetic effect on nitrate removal was exhibited through uniformly mixing the pillared bentonite with Fe(0). In such a mixing manner, the nitrate was 100% removed, and the removal efficiency was much higher than the simple summation of adsorption by the pillared bentonite and reduction by Fe(0). The influencing factors such as bentonite type, amount of the pillared bentonite and initial pH of nitrate solutions were investigated. In this uniform mixture, the pillared bentonite could adsorb nitrate ions, and facilitated the mass transfer of nitrate onto Fe(0) surface, then accelerated the nitrate reduction. The pillared bentonite could also act as the proton-donor, and helped to keep the complete nitrate removal for at least 10 h even when the nitrate solution was fed at nearly neutral pH.

The improved stability of enzyme encapsulated in biomimetic titania particles

International Nuclear Information System (INIS)

Jiang Yanjun; Sun Qianyun; Jiang Zhongyi; Zhang Lei; Li Jian; Li Lin; Sun Xiaohui

2009-01-01

This study demonstrates a novel biomimetic approach for the entrapment of yeast alcohol dehydrogenase (YADH) within titania nanoparticles to improve its stability. Protamine was as the template and catalyst for the condensation of titanium (IV) bis(ammonium lactato) dihydroxide (Ti-BALDH) into titania nanoparticles in which YADH was trapped. The as-prepared titania/protamine/YADH composites were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), dynamic light scattering (DLS), X-ray powder diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The mechanism of YADH encapsulation was tentatively proposed from a series of experimental results. The preliminary investigation showed that encapsulated YADH could retain most of its initial activity. Compared to free YADH, encapsulated YADH exhibited significantly improved thermal, pH and recycling stability. After 5 weeks storage, no substantial loss of catalytic activity for encapsulated YADH was observed

Novel structuring routines of titania films for application in photovoltaics

OpenAIRE

Niedermeier, Martin A.

2014-01-01

Novel routines to structure titania thin films on various length scales are investigated regarding photovoltaic applications. The main focus of the investigations lies on the custom-tailoring of the morphologies of the titania films using sol-gel chemistry in combination with block copolymer templating. Additionally, a low-temperature routine for functional hybrid films as well as the growth of gold as electrode material on top of an organic hole-conductor are investigated. Im Hinblick auf...

Rapid synthesis of nitrogen doped titania with mixed crystal lattice via microwave-assisted hydrothermal method

International Nuclear Information System (INIS)

Zhang Peilin; Liu Bin; Yin Shu; Wang Yuhua; Petrykin, Valery; Kakihana, Masato; Sato, Tsugio

2009-01-01

A microwave-assisted hydrothermal method was employed to synthesize nitrogen doped titania nanoparticles. Due to the high heating efficiency of microwave, rapid synthesis could be achieved in comparison with the conventional oven. Mixed crystal lattice was found existing in the obtained product, and the phase transformation behaviour under calcination was studied by XRD measurement together with Raman spectroscopy in details. The obtained nitrogen doped titania showed high specific surface area, about 300 m 2 g -1 . Photocatalytic activity in destructing NO x gas by the prepared sample exceeded that of commercial titania (P 25) or nitrogen doped titania synthesized by conventional hydrothermal method, under both visible-light and ultraviolet-light irradiation.

The potential health risk of titania nanoparticles

International Nuclear Information System (INIS)

Zhang, Ruinan; Bai, Yuhong; Zhang, Bin; Chen, Lingxin; Yan, Bing

2012-01-01

Highlights: ► Nanotechnology has been widely used in environmental treatments. ► The safety of nanomaterials to human is under-studied. ► Taking titania nanoparticle as an example to address nanotoxicity and remedy. ► The much needed future investigations are suggested. - Abstract: Widespread use of titania nanoparticles (TNPs) has caused a significant release of TNPs into the environment, increasing human exposure to TNPs. The potential toxicity of TNPs has become an urgent concern. Various models have been used to evaluate the toxic effects of TNPs, but the relationship between TNPs’ toxicity and physicochemical properties is largely unknown. This review summarizes relevant reports to support the development of better predictive toxicological models and the safe future application of TNPs.

Lithium ion batteries with titania/graphene anodes

Science.gov (United States)

Liu, Jun; Choi, Daiwon; Yang, Zhenguo; Wang, Donghai; Graff, Gordon L; Nie, Zimin; Viswanathan, Vilayanur V; Zhang, Jason; Xu, Wu; Kim, Jin Yong

2013-05-28

Lithium ion batteries having an anode comprising at least one graphene layer in electrical communication with titania to form a nanocomposite material, a cathode comprising a lithium olivine structure, and an electrolyte. The graphene layer has a carbon to oxygen ratio of between 15 to 1 and 500 to 1 and a surface area of between 400 and 2630 m.sup.2/g. The nanocomposite material has a specific capacity at least twice that of a titania material without graphene material at a charge/discharge rate greater than about 10 C. The olivine structure of the cathode of the lithium ion battery of the present invention is LiMPO.sub.4 where M is selected from the group consisting of Fe, Mn, Co, Ni and combinations thereof.

Development of a dielectric ceramic based on diatomite-titania part two: dielectric properties characterization

Directory of Open Access Journals (Sweden)

Medeiros Jamilson Pinto

1998-01-01

Full Text Available Dielectric properties of sintered diatomite-titania ceramics are presented. Specific capacitance, dissipation factor, quality factor and dielectric constant were determined as a function of sintering temperature, titania content and frequency; the temperature coefficient of capacitance was measured as a function of frequency. Besides leakage current, the dependence of the insulation resistance and the dielectric strength on the applied dc voltage were studied. The results show that diatomite-titania compositions can be used as an alternative dielectric.

Reduced Titania Films with Ordered Nanopores and Their Application to Visible Light Water Splitting

International Nuclear Information System (INIS)

Shahid, Muhammad; Choi, Seoyeong; Liu, Jingling; Kwon, Younguk

2013-01-01

We report on the photoelectrochemical properties of partially reduced mesoporous titania thin films. The fabrication is achieved by synthesizing mesoporous titania thin films through the self-assembly of a titania precursor and a block copolymer, followed by aging and calcination, and heat-treatment under a H 2 (1 torr) environment. Depending on the temperature used for the reaction with H2, the degree of the reduction (generation of oxygen vacancies) of the titania is controlled. The oxygen vacancies induce visible light absorption, and decrease of resistance while the mesoporosity is practically unaltered. The photoelectrochemical activity data on these films, by measuring their photocurrent-potential behavior in 1 M NaOH electrolyte under AM 1.5G 100 mW cm -2 illumination, show that the three effects of the oxygen vacancies contribute to the enhancement of the photoelectrochemical properties of the mesoporous titania thin films. The results show that these oxygen deficient TiO 2 mesoporous thin films hold great promise for a solar hydrogen generation. Suggestions for the materials design for improved photoelectrochemical properties are made

Tin-Platinum catalysts interactions on titania and silica

International Nuclear Information System (INIS)

Nava, N.; Del Angel, P.; Salmones, J.; Baggio-Saitovitch, E.; Santiago, P.

2007-01-01

Pt-Sn was supported on titania and silica, and the resulting interactions between the components in prepared samples and the resulting interactions between the components before and after treatment with hydrogen were characterized by Moessbauer spectroscopy, X-ray diffraction, Rietveld refinement, high-resolution transmission electron microscopy (HRTEM) and catalytic tests data. Results show the presence of Pt and SnO 2 after calcinations, and Pt 3 Sn, PtSn and PtSn 3 after reduction. Rietveld analysis shows that some Ti 4+ are replaced by Sn 4+ atoms in the titania structure. Finally, HRTEM and the practically absence of activity observed confirms that metallic platinum is encapsulated

Bactericidal performance of visible-light responsive titania photocatalyst with silver nanostructures.

Directory of Open Access Journals (Sweden)

Ming-Show Wong

Full Text Available BACKGROUND: Titania dioxide (TiO(2 photocatalyst is primarily induced by ultraviolet light irradiation. Visible-light responsive anion-doped TiO(2 photocatalysts contain higher quantum efficiency under sunlight and can be used safely in indoor settings without exposing to biohazardous ultraviolet light. The antibacterial efficiency, however, remains to be further improved. METHODOLOGY/PRINCIPAL FINDINGS: Using thermal reduction method, here we synthesized silver-nanostructures coated TiO(2 thin films that contain a high visible-light responsive antibacterial property. Among our tested titania substrates including TiO(2, carbon-doped TiO(2 [TiO(2 (C] and nitrogen-doped TiO(2 [TiO(2 (N], TiO(2 (N showed the best performance after silver coating. The synergistic antibacterial effect results approximately 5 log reductions of surviving bacteria of Escherichia coli, Streptococcus pyogenes, Staphylococcus aureus and Acinetobacter baumannii. Scanning electron microscope analysis indicated that crystalline silver formed unique wire-like nanostructures on TiO(2 (N substrates, while formed relatively straight and thicker rod-shaped precipitates on the other two titania materials. CONCLUSION/SIGNIFICANCE: Our results suggested that proper forms of silver on various titania materials could further influence the bactericidal property.

Current practice and guidelines for the safe design of water barrier pillars

CSIR Research Space (South Africa)

Rangasamy, T

2001-08-01

Full Text Available adjacent to barrier pillars was conducted to ascertain the relationship between compartment water head, barrier pillar width and flow rates for combinations of roof bound, coal bound and floor bound flow. The results obtained from the instrumentation... pillars. A survey of South African Collieries revealed that water leakage associated with barrier pillars can be classed into seven predominant geotechnical flow categories. Through extensive numerical modelling and case history matching, barrier pillar...

Rib-pillar mining at Sigma Colliery

Energy Technology Data Exchange (ETDEWEB)

De Beer, J J.S.; Hunter, F; Neethling, A F [Sigma Colliery, Sasolburg (South Africa)

1991-06-01

The paper describes the rib-pillar extraction method now used at Sigma Colliery in the Orange Free State. In this method, access roadways (with a high safety factor) are developed into a block of coal suitable for total extraction; pillars that have a low safety factor are then formed and extracted immediately. The method, together with the current practices of labour management, has resulted in better utilization of the coal resources and capital, increased production and labour productivity, and improved safety. 11 figs.

Pessimistic Determination of Mechanical Conditions and Micro/macroeconomic Evaluation of Mine Pillar Replacement

Science.gov (United States)

Chen, Qingfa; Zhao, Fuyu

2017-12-01

Numerous pillars are left after mining of underground mineral resources using the open stope method or after the first step of the partial filling method. The mineral recovery rate can, however, be improved by replacement recovery of pillars. In the present study, the relationships among the pillar type, minimum pillar width, and micro/macroeconomic factors were investigated from two perspectives, namely mechanical stability and micro/macroeconomic benefit. Based on the mechanical stability formulas for ore and artificial pillars, the minimum width for a specific pillar type was determined using a pessimistic criterion. The microeconomic benefit c of setting an ore pillar, the microeconomic benefit w of artificial pillar replacement, and the economic net present value (ENPV) of the replacement process were calculated. The values of c and w were compared with respect to ENPV, based on which the appropriate pillar type and economical benefit were determined.

Performance enhancement of direct ethanol fuel cell using Nafion composites with high volume fraction of titania

Science.gov (United States)

Matos, B. R.; Isidoro, R. A.; Santiago, E. I.; Fonseca, F. C.

2014-12-01

The present study reports on the performance enhancement of direct ethanol fuel cell (DEFC) at 130 °C with Nafion-titania composite electrolytes prepared by sol-gel technique and containing high volume fractions of the ceramic phase. It is found that for high volume fractions of titania (>10 vol%) the ethanol uptake of composites is largely reduced while the proton conductivity at high-temperatures is weakly dependent on the titania content. Such tradeoff between alcohol uptake and conductivity resulted in a boost of DEFC performance at high temperatures using Nafion-titania composites with high fraction of the inorganic phase.

Titania-coated manganite nanoparticles: Synthesis of the shell, characterization and MRI properties

Energy Technology Data Exchange (ETDEWEB)

Jirák, Zdeněk; Kuličková, Jarmila [Institute of Physics, AS CR, Cukrovarnická 10, 162 00 Praha 6 (Czech Republic); Herynek, Vít [Institute for Clinical and Experimental Medicine, Vídeňská 1958/9, 140 21 Praha 4 (Czech Republic); Maryško, Miroslav [Institute of Physics, AS CR, Cukrovarnická 10, 162 00 Praha 6 (Czech Republic); Koktan, Jakub [Institute of Physics, AS CR, Cukrovarnická 10, 162 00 Praha 6 (Czech Republic); University of Chemistry and Technology, Prague, Technická 5, 166 28 Praha 6 (Czech Republic); Kaman, Ondřej, E-mail: kamano@seznam.cz [Institute of Physics, AS CR, Cukrovarnická 10, 162 00 Praha 6 (Czech Republic)

2017-04-01

Novel procedure for coating of oxide nanoparticles with titania, employing hydrolysis and polycondensation of titanium alkoxides under high-dilution conditions and cationic surfactants, is developed and applied to magnetic cores of perovskite manganite. Bare particles of the ferromagnetic La{sub 0.65}Sr{sub 0.35}MnO{sub 3} phase, possessing high magnetization, M{sub 10} {sub kOe}(4.5 K) = 63.5 emu g{sup −1}, and Curie temperature, T{sub C} = 355 K, are synthesized by sol-gel procedure and subsequently coated with titania. Further, a comparative silica-coated product is prepared. In order to analyse the morphology, colloidal stability, and surface properties of these two types of coated particles, a detailed study by means of transmission electron microscopy, dynamic light scattering, zeta-potential measurements, and IR spectroscopy is carried out. The experiments on the titania-coated sample reveal a continuous though porous character of the TiO{sub 2} shell, the nature of which is amorphous but can be transformed to anatase at higher temperatures. Finally, the relaxometric study at the magnetic field of 0.5 T, performed to quantity the transverse relaxivity and its temperature dependence, reveals important differences between the titania-coated and silica-coated nanoparticles. - Highlights: • Magnetic nanoparticles of perovskite La{sub 0.65}Sr{sub 0.35}MnO{sub 3} phase are coated with TiO{sub 2}. • The titania forms a continuous and amorphous shell and provides colloidal stability. • Morphology and surface properties are compared to a silica-coated product. • MRI properties of both the titania- and silica-coated particles are studied at 0.5 T. • The temperature dependence of r{sub 2} is strongly affected by the type of coating.

In vivo demonstration of enhanced radiotherapy using rare earth doped titania nanoparticles.

Science.gov (United States)

Townley, Helen E; Kim, Jeewon; Dobson, Peter J

2012-08-21

Radiation therapy is often limited by damage to healthy tissue and associated side-effects; restricting radiation to ineffective doses. Preferential incorporation of materials into tumour tissue can enhance the effect of radiation. Titania has precedent for use in photodynamic therapy (PDT), generating reactive oxygen species (ROS) upon photoexcitation, but is limited by the penetration depth of UV light. Optimization of a nanomaterial for interaction with X-rays could be used for deep tumour treatment. As such, titania nanoparticles were doped with gadolinium to optimize the localized energy absorption from a conventional medical X-ray, and further optimized by the addition of other rare earth (RE) elements. These elements were selected due to their large X-ray photon interaction cross-section, and potential for integration into the titania crystal structure. Specific activation of the nanoparticles by X-ray can result in generation of ROS leading to cell death in a tumour-localized manner. We show here that intratumoural injection of RE doped titania nanoparticles can enhance the efficacy of radiotherapy in vivo.

Effect of structural discontinuities on coal pillar strength as a basis for improving safety in the design of coal pillar systems.

CSIR Research Space (South Africa)

Esterhuizen, GS

1998-12-01

Full Text Available The stability of underground coal mines depends on the integrity of the pillars which are required to support the overlying strata. Should the pillars collapse, the safety of the persons in the workings will be threatened. The strength of a coal...

The potential health risk of titania nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Zhang, Ruinan, E-mail: ruinanzhang87@gmail.com [School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China); Bai, Yuhong, E-mail: yuhong.bai1983@gmail.com [School of Pharmaceutical Sciences, Shandong University, Jinan 250100 (China); Zhang, Bin, E-mail: binzhang1968@hotmail.com [School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China); Chen, Lingxin, E-mail: lxchen@yic.ac.cn [Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, Shandong 264003 (China); Yan, Bing, E-mail: dr.bingyan@gmail.com [School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China); Department of Chemical Biology and Therapeutics, St. Jude Children' s Research Hospital, Memphis, TN 38105 (United States)

2012-04-15

Highlights: Black-Right-Pointing-Pointer Nanotechnology has been widely used in environmental treatments. Black-Right-Pointing-Pointer The safety of nanomaterials to human is under-studied. Black-Right-Pointing-Pointer Taking titania nanoparticle as an example to address nanotoxicity and remedy. Black-Right-Pointing-Pointer The much needed future investigations are suggested. - Abstract: Widespread use of titania nanoparticles (TNPs) has caused a significant release of TNPs into the environment, increasing human exposure to TNPs. The potential toxicity of TNPs has become an urgent concern. Various models have been used to evaluate the toxic effects of TNPs, but the relationship between TNPs' toxicity and physicochemical properties is largely unknown. This review summarizes relevant reports to support the development of better predictive toxicological models and the safe future application of TNPs.

Fold catastrophe model of dynamic pillar failure in asymmetric mining

Energy Technology Data Exchange (ETDEWEB)

Yue Pan; Ai-wu Li; Yun-song Qi [Qingdao Technological University, Qingdao (China). College of Civil Engineering

2009-01-15

A rock burst disaster not only destroys the pit facilities and results in economic loss but it also threatens the life of the miners. Pillar rock burst has a higher frequency of occurrence in the pit compared to other kinds of rock burst. Understanding the cause, magnitude and prevention of pillar rock burst is a significant undertaking. Equations describing the bending moment and displacement of the rock beam in asymmetric mining have been deduced for simplified asymmetric beam-pillar systems. Using the symbolic operation software MAPLE 9.5 a catastrophe model of the dynamic failure of an asymmetric rock-beam pillar system has been established. The differential form of the total potential function deduced from the law of conservation of energy was used for this deduction. The critical conditions and the initial and final positions of the pillar during failure have been given in analytical form. The amount of elastic energy released by the rock beam at the instant of failure is determined as well. A diagrammatic form showing the pillar failure was plotted using MATLAB software. This graph contains a wealth of information and is important for understanding the behavior during each deformation phase of the rock-beam pillar system. The graphic also aids in distinguishing the equivalent stiffness of the rock beam in different directions. 11 refs., 8 figs.

Synthesis of Titania-supported Copper Nanoparticles via Refined Alkoxide Sol-gel Process

International Nuclear Information System (INIS)

Wu, Jeffrey C.S.; Tseng, I.-Hsiang; Chang, W.-C.

2001-01-01

Nanoparticles of titania and copper-loaded titania were synthesized by a refined sol-gel method using titanium butoxide. Unlike the conventional sol-gel procedure of adding water directly, the esterification of anhydrous butanol and glacial acetic acid provided the hydrolyzing water. In addition, acetic acid also served as a chelating ligand to stabilize the hydrolysis-condensation process and minimize the agglomeration of titania. Following the hydrolysis, Cu/TiO 2 was prepared by adding copper chloride to titania sol. The sol was dried, then calcined at 500 deg. C to remove organics and transformed to anatase titania which was verified by XRD. Cu/TiO 2 was further hydrogen-reduced at 300 deg. C. The recovery of Ti was exceeded by an average of 95% from titanium butoxide. TEM micrographs show that the Cu/TiO 2 particles are near uniform. The average crystallite sizes are 17-20 nm estimated from the peak broadening of XRD spectra. The bandgaps of TiO 2 and reduced Cu/TiO 2 range from 2.70 to 3.15 eV estimated from the diffusive reflective UV-Vis spectra. XPS analysis shows that Cu 2p 3/2 is 933.4 eV indicating primary Cu 2 O form on the TiO 2 supports. The binding energy of Ti does not exhibit chemical shift suggesting negligible interaction of Cu cluster and TiO 2 support

Synthesis of Titania-supported Copper Nanoparticles via Refined Alkoxide Sol-gel Process

Science.gov (United States)

Wu, Jeffrey C. S.; Tseng, I.-Hsiang; Chang, Wan-Chen

2001-06-01

Nanoparticles of titania and copper-loaded titania were synthesized by a refined sol-gel method using titanium butoxide. Unlike the conventional sol-gel procedure of adding water directly, the esterification of anhydrous butanol and glacial acetic acid provided the hydrolyzing water. In addition, acetic acid also served as a chelating ligand to stabilize the hydrolysis-condensation process and minimize the agglomeration of titania. Following the hydrolysis, Cu/TiO2 was prepared by adding copper chloride to titania sol. The sol was dried, then calcined at 500°C to remove organics and transformed to anatase titania which was verified by XRD. Cu/TiO2 was further hydrogen-reduced at 300°C. The recovery of Ti was exceeded by an average of 95% from titanium butoxide. TEM micrographs show that the Cu/TiO2 particles are near uniform. The average crystallite sizes are 17-20 nm estimated from the peak broadening of XRD spectra. The bandgaps of TiO2 and reduced Cu/TiO2 range from 2.70 to 3.15 eV estimated from the diffusive reflective UV-Vis spectra. XPS analysis shows that Cu 2p3/2 is 933.4 eV indicating primary Cu2O form on the TiO2 supports. The binding energy of Ti does not exhibit chemical shift suggesting negligible interaction of Cu cluster and TiO2 support.

Synthesis of Titania-supported Copper Nanoparticles via Refined Alkoxide Sol-gel Process

Energy Technology Data Exchange (ETDEWEB)

Wu, Jeffrey C.S., E-mail: Cswu@ccms.ntu.edu.tw; Tseng, I.-Hsiang; Chang, W.-C. [National Taiwan University, Department of Chemical Engineering (China)

2001-06-15

Nanoparticles of titania and copper-loaded titania were synthesized by a refined sol-gel method using titanium butoxide. Unlike the conventional sol-gel procedure of adding water directly, the esterification of anhydrous butanol and glacial acetic acid provided the hydrolyzing water. In addition, acetic acid also served as a chelating ligand to stabilize the hydrolysis-condensation process and minimize the agglomeration of titania. Following the hydrolysis, Cu/TiO{sub 2} was prepared by adding copper chloride to titania sol. The sol was dried, then calcined at 500 deg. C to remove organics and transformed to anatase titania which was verified by XRD. Cu/TiO{sub 2} was further hydrogen-reduced at 300 deg. C. The recovery of Ti was exceeded by an average of 95% from titanium butoxide. TEM micrographs show that the Cu/TiO{sub 2} particles are near uniform. The average crystallite sizes are 17-20 nm estimated from the peak broadening of XRD spectra. The bandgaps of TiO{sub 2} and reduced Cu/TiO{sub 2} range from 2.70 to 3.15 eV estimated from the diffusive reflective UV-Vis spectra. XPS analysis shows that Cu 2p{sub 3/2} is 933.4 eV indicating primary Cu{sub 2}O form on the TiO{sub 2} supports. The binding energy of Ti does not exhibit chemical shift suggesting negligible interaction of Cu cluster and TiO{sub 2} support.

Tin-Platinum catalysts interactions on titania and silica

Energy Technology Data Exchange (ETDEWEB)

Nava, N. [Instituto Mexicano del Petroleo Lazaro Cardenas 152, 07730 Mexico, D.F. (Mexico)], E-mail: tnava@imp.mx; Del Angel, P. [Instituto Mexicano del Petroleo Lazaro Cardenas 152, 07730 Mexico, D.F. (Mexico); Salmones, J. [Instituto Politecnico Nacional-ESIQIE UPALM, 07738 Mexico, D.F. (Mexico); Baggio-Saitovitch, E. [Centro Brasileiro de Pesquisas Fisicas, Rua Dr. Xavier Sigaud 150, 22290-180 Rio de Janeiro, Brasil (Brazil); Santiago, P. [Instituto de Fisica, UNAM, Mexico, D. F., 04510 Mexico (Mexico)

2007-09-30

Pt-Sn was supported on titania and silica, and the resulting interactions between the components in prepared samples and the resulting interactions between the components before and after treatment with hydrogen were characterized by Moessbauer spectroscopy, X-ray diffraction, Rietveld refinement, high-resolution transmission electron microscopy (HRTEM) and catalytic tests data. Results show the presence of Pt and SnO{sub 2} after calcinations, and Pt{sub 3}Sn, PtSn and PtSn{sub 3} after reduction. Rietveld analysis shows that some Ti{sup 4+} are replaced by Sn{sup 4+} atoms in the titania structure. Finally, HRTEM and the practically absence of activity observed confirms that metallic platinum is encapsulated.

Development and validation of a method to predict coal pillar life in South Africa

Energy Technology Data Exchange (ETDEWEB)

Van Der Merwe, J.N. [Pretoria Univ., Dept. of Mining Engineering (South Africa)

2005-07-01

One of the most difficult aspects of mine closure procedures, is to predict the long term stability of pillars in the case of coal mining. In South African coal mining, pillars have been designed since the late 1960's with the aid of a pillar strength formula based on statistical analysis of failed pillar cases by the well known team of Salamon and Munro. They developed the widely used power formula for pillar strength. Since that time, however, the data base of failed pillars has effectively doubled in size and re-analysis of the new data indicated that the original pillar strength of small pillars may have been over estimated. The data was then extensively re-analysed and a more effective linear formula for pillar strength was found. The most important differences between the two formulae are that the predicted strength of small pillars are lower and the strength of larger pillars, higher with the new formula. However, neither of the two methods explicitly cater for the prediction of the expected time of stability of coal pillars. No direct correlation between the safety factors and the period of stability of pillars could be found. It was then determined that the most frequent mode of pillar failure was by progressive scaling. Using the new formula to determine a minimum value of pillar safety factor (i.e. the safety factor at which failure can be taken as guaranteed to occur), the final sizes - after scaling - at which the failed pillars had to be in order to fail, were determined. The differences between the original dimensions and the postulated final dimensions were then used to calculate a rate of pillar scaling. The rate was then re-applied to the original data bases of both failed and intact pillar cases and distinct differences were found. The projected lives of the failed pillars were substantially shorter than the projected lives of the intact pillars. While this inspired confidence in the procedure, it was still based on an assumed and unproven

Development and validation of a method to predict coal pillar life in South Africa

International Nuclear Information System (INIS)

Van Der Merwe, J.N.

2005-01-01

One of the most difficult aspects of mine closure procedures, is to predict the long term stability of pillars in the case of coal mining. In South African coal mining, pillars have been designed since the late 1960's with the aid of a pillar strength formula based on statistical analysis of failed pillar cases by the well known team of Salamon and Munro. They developed the widely used power formula for pillar strength. Since that time, however, the data base of failed pillars has effectively doubled in size and re-analysis of the new data indicated that the original pillar strength of small pillars may have been over estimated. The data was then extensively re-analysed and a more effective linear formula for pillar strength was found. The most important differences between the two formulae are that the predicted strength of small pillars are lower and the strength of larger pillars, higher with the new formula. However, neither of the two methods explicitly cater for the prediction of the expected time of stability of coal pillars. No direct correlation between the safety factors and the period of stability of pillars could be found. It was then determined that the most frequent mode of pillar failure was by progressive scaling. Using the new formula to determine a minimum value of pillar safety factor (i.e. the safety factor at which failure can be taken as guaranteed to occur), the final sizes - after scaling - at which the failed pillars had to be in order to fail, were determined. The differences between the original dimensions and the postulated final dimensions were then used to calculate a rate of pillar scaling. The rate was then re-applied to the original data bases of both failed and intact pillar cases and distinct differences were found. The projected lives of the failed pillars were substantially shorter than the projected lives of the intact pillars. While this inspired confidence in the procedure, it was still based on an assumed and unproven rate

A Study of Clay-Epoxy Nanocomposites Consisting of Unmodified Clay and Organo Clay

Directory of Open Access Journals (Sweden)

Graham Edward

2006-04-01

Full Text Available Clay-epoxy nanocomposites were synthesized from DGEBA resin and montmorillonite clay with an in-situ polymerization. One type of untreated clay and two types of organo clay were used to produce the nanocompsoites. The aims of this study were to examine the nanocomposite structure using different tools and to compare the results between the unmodified clay and modified clays as nanofillers. Although diffractogram in reflection mode did not show any apparent peak of both types of materials, the transmitted XRD (X-Ray Difraction graphs, DSC (Differential Scanning Calorimeter analysis and TEM (Transmission Electron Microscope images revealed that the modified clay-epoxy and unmodified clay-epoxy provides different results. Interestingly, the micrographs showed that some of the modified clay layers possessed non-exfoliated layers in the modified clay-epoxy nanocomposites. Clay aggregates and a hackle pattern were found from E-SEM images for both types of nanocomposite materials. It is shown that different tools should be used to determine the nanocomposite structure.

Synthesis and characterization of natural hydroxyapatite (recycled) composites with titania

International Nuclear Information System (INIS)

Mendes Filho, Antonio Alves; Gouveia, Vitor Jose Pinto; Pereira, Renato Alves; Araujo, Fernando Gabriel da Silva; Sousa, Camila Mateus de

2010-01-01

Natural hydroxyapatite biphasic ceramics (recycled) with titania (TiO_2-Hap) were studied in this work. For the formation of such ceramic the powders were mixed natural hydroxyapatite obtained from veal bone by the hydrothermal method with titania (TiO_2), forming the composites H9T1. The powders, manually homogenized, were conformed in pellet and sintered at temperatures between 1200 and 1400 deg C The ceramic bodies were characterized by XRD and SEM/EDS. The initial results were not satisfactory and require new studies. (author)

High-density arrays of titania nanoparticles using monolayer micellar films of diblock copolymers as templates.

Science.gov (United States)

Li, Xue; Lau, King Hang Aaron; Kim, Dong Ha; Knoll, Wolfgang

2005-05-24

Highly dense arrays of titania nanoparticles were fabricated using surface micellar films of poly(styrene-block-2-vinylpyridine) diblock copolymers (PS-b-P2VP) as reaction scaffolds. Titania could be introduced selectively within P2VP nanodomains in PS-b-P2VP films through the binary reaction between water molecules trapped in the P2VP domains and the TiCl(4) vapor precursors. Subsequent UV exposure or oxygen plasma treatment removed the organic matrix, leading to titania nanoparticle arrays on the substrate surface. The diameter of the titania domains and the interparticle distance were defined by the lateral scale present in the microphase-separated morphology of the initial PS-b-P2VP films. The typical diameter of titania nanoparticles obtained by oxygen plasma treatment was of the order of approximately 23 nm. Photoluminescence (PL) properties were investigated for films before and after plasma treatment. Both samples showed PL properties with major physical origin due to self-trapped excitons, indicating that the local environment of the titanium atoms is similar.

THE EFFECT OF NANO-TITANIA ADDITION ON THE PROPERTIES OF HIGH-ALUMINA LOW-CEMENT SELF-FLOWING REFRACTORY CASTABLES

Directory of Open Access Journals (Sweden)

Sasan Otroj

2011-12-01

Full Text Available The self-flow characteristics and properties of high-alumina low-cement refractory castables added with nano-titania particles are investigated. For this reason, the reactive alumina in the castable composition is substituted by nano-titania powder in 0-1 %wt. range. The microstructures, phase composition, physical and mechanical properties of these refractory castables at different temperatures are studied. The results show that the addition of nano-titania particles has great effect on the self-flow characteristics, phase composition, physical and mechanical properties of these refractory castables. With increase of nano-titania particles in castable composition, the self-flow value and working time tend to decrease. With addition of 0.5 wt.% nano-titania in the castable composition, the mechanical strength of castable in all firing temperatures tends to increase. It is attributed to the formation of CA6 phase and enhanced ceramic bonding. Nano-titania particles can act as a nucleating agent for hibonite phase and decrease the formation temperature of hibonite. Because of perovskite phase formation, the addition of 1 wt.% nano-titania can decrease the mechanical strength of castable after firing.

Synthesis, characterization and photocatalytic activity of porous manganese oxide doped titania for toluene decomposition

International Nuclear Information System (INIS)

Jothiramalingam, R.; Wang, M.K.

2007-01-01

The present study describes the photocatalytic degradation of toluene in gas phase on different porous manganese oxide doped titanium dioxide. As synthesized birnessite and cryptomelane type porous manganese oxide were doped with titania and tested for photocatalytic decomposition of toluene in gas phase. The effects of the inlet concentration of toluene, flow rate (retention time) were examined and the relative humidity was maintained constantly. Thermal and textural characterization of manganese oxide doped titania materials were characterized by X-ray diffraction (XRD), thermogravemetry (TG), BET and TEM-EDAX studies. The aim of the present study is to synthesize the porous manganese oxide doped titania and to study its photocatalytic activity for toluene degradation in gas phase. Cryptomelane doped titania catalyst prepared in water medium [K-OMS-2 (W)] is shown the good toluene degradation with lower catalysts loading compared to commercial bulk titania in annular type photo reactor. The higher photocatalytic activity due to various factors such as catalyst preparation method, experimental conditions, catalyst loading, surface area, etc. In the present study manganese oxide OMS doped titania materials prepared by both aqueous and non-aqueous medium, aqueous medium prepared catalyst shows the good efficiency due to the presence of OH bonded groups on the surface of catalyst. The linear forms of different kinetic equations were applied to the adsorption data and their goodness of fit was evaluated based on the R 2 and standard error. The goodness to the linear fit was observed for Elovich model with high R 2 (≥0.9477) value

Titania may produce abiotic oxygen atmospheres on habitable exoplanets.

Science.gov (United States)

Narita, Norio; Enomoto, Takafumi; Masaoka, Shigeyuki; Kusakabe, Nobuhiko

2015-09-10

The search for habitable exoplanets in the Universe is actively ongoing in the field of astronomy. The biggest future milestone is to determine whether life exists on such habitable exoplanets. In that context, oxygen in the atmosphere has been considered strong evidence for the presence of photosynthetic organisms. In this paper, we show that a previously unconsidered photochemical mechanism by titanium (IV) oxide (titania) can produce abiotic oxygen from liquid water under near ultraviolet (NUV) lights on the surface of exoplanets. Titania works as a photocatalyst to dissociate liquid water in this process. This mechanism offers a different source of a possibility of abiotic oxygen in atmospheres of exoplanets from previously considered photodissociation of water vapor in upper atmospheres by extreme ultraviolet (XUV) light. Our order-of-magnitude estimation shows that possible amounts of oxygen produced by this abiotic mechanism can be comparable with or even more than that in the atmosphere of the current Earth, depending on the amount of active surface area for this mechanism. We conclude that titania may act as a potential source of false signs of life on habitable exoplanets.

Pillared clays : preparation and characterization of clay minerals and aluminum-based pillaring agents

NARCIS (Netherlands)

Kloprogge, J.T.

1992-01-01

After an extensive introductory chapter (Chapter I), in which the background and the aim of the research is dealt with, the hydrothermal synthesis and the characterization of Na-beidellite is discussed in Chapter II and III. The conditions of temperature, water pressure, and sodium activity under

Photoelectrochemical reactivity of polyoxophosphotungstates embedded in titania tubules

International Nuclear Information System (INIS)

Xie Yibing

2006-01-01

A highly ordered and crystallized titania (TiO 2 ) nanotube array is fabricated by a low-voltage anodization plus a post-embedding calcination process. Polyoxophosphotungstate-titania (POPTA-TiO 2 ) composite catalyst is synthesized by embedding POPTA in TiO 2 tubule channels to improve the photoelectrochemical properties. The morphological characteristics and crystal behaviour of POPTA-TiO 2 are examined by field-emission scanning electron microscopy and x-ray diffraction. The stability of the chemical structure has been analysed by Fourier transformed infrared spectroscopy measurements. The photoelectrochemical properties are investigated by means of the polarization current response. Photocatalytic and photoelectrocatalytic reactivities for the degradation of an endocrine disrupting chemical have also been investigated to examine the photoelectrochemical reaction efficiency of POPTA-TiO 2 composite catalyst

Adherence and scratching resistance of nanometric titania films

International Nuclear Information System (INIS)

Pascoali, S.; Dominguini, L.; Borges, J.B.

2012-01-01

TiO 2 films has been used to extend the wear resistance in bearing, seals for pumps and bone prostheses. In this study was analyzed the conventional hardness and scratch toughness. The scratching test equipment used was developed at the Laboratory of materials Labmat / UFSC. The tests were performed on Titania films deposited on glass plates and ceramics via reactive DC magnetron sputtering. The films were deposited by 10, 15 and 60 min. One of the samples has a titanium metal film of a few nanometers thick between the substrate and the Titania film, the oxide has been deposited for 30 min. At this rang of tests loads the deposited films show good adhesion to substrate, there was no cracking or spalling of the film. (author)

Photocatalytic polymerization induced by a transparent anatase titania aqueous sol and fabrication of polymer composites

Directory of Open Access Journals (Sweden)

2010-06-01

Full Text Available The surface modification of the anatase titania nanoparticles prepared via a controlled nonhydrolytic sol-gel process is achieved by the formation of the bidentate coordination between titania and methacrylic acid (MAA molecules. The in situ photocatalytic polymerization of methyl methacrylate (MMA monomer is initiated by surface modified anatase titania nanoparticles under Xe lamp irradiation. A variety of techniques including differential scanning calorimetry (DSC, thermo-gravimetric analysis (TGA and scanning electron microscopy (SEM are employed to characterize the resulting materials. The glass transition temperatures and the thermal stabilities of polymethyl methacrylate (PMMA composite materials prepared via photocatalytic polymerization are enhanced compared with pure polymer. The partial aggregation of titania nanoparticles in PMMA composite films is derived from the surface polymerization of MMA, which makes the inorganic particles hydrophobic and drives them to the water/oil interfaces.

Superhydrophobic analyte concentration utilizing colloid-pillar array SERS substrates.

Science.gov (United States)

Wallace, Ryan A; Charlton, Jennifer J; Kirchner, Teresa B; Lavrik, Nickolay V; Datskos, Panos G; Sepaniak, Michael J

2014-12-02

The ability to detect a few molecules present in a large sample is of great interest for the detection of trace components in both medicinal and environmental samples. Surface enhanced Raman spectroscopy (SERS) is a technique that can be utilized to detect molecules at very low absolute numbers. However, detection at trace concentration levels in real samples requires properly designed delivery and detection systems. The following work involves superhydrophobic surfaces that have as a framework deterministic or stochastic silicon pillar arrays formed by lithographic or metal dewetting protocols, respectively. In order to generate the necessary plasmonic substrate for SERS detection, simple and flow stable Ag colloid was added to the functionalized pillar array system via soaking. Native pillars and pillars with hydrophobic modification are used. The pillars provide a means to concentrate analyte via superhydrophobic droplet evaporation effects. A ≥ 100-fold concentration of analyte was estimated, with a limit of detection of 2.9 × 10(-12) M for mitoxantrone dihydrochloride. Additionally, analytes were delivered to the surface via a multiplex approach in order to demonstrate an ability to control droplet size and placement for scaled-up uses in real world applications. Finally, a concentration process involving transport and sequestration based on surface treatment selective wicking is demonstrated.

Numerical Analysis on Failure Modes and Mechanisms of Mine Pillars under Shear Loading

Directory of Open Access Journals (Sweden)

Tianhui Ma

2016-01-01

Full Text Available Severe damage occurs frequently in mine pillars subjected to shear stresses. The empirical design charts or formulas for mine pillars are not applicable to orebodies under shear. In this paper, the failure process of pillars under shear stresses was investigated by numerical simulations using the rock failure process analysis (RFPA 2D software. The numerical simulation results indicate that the strength of mine pillars and the corresponding failure mode vary with different width-to-height ratios and dip angles. With increasing dip angle, stress concentration first occurs at the intersection between the pillar and the roof, leading to formation of microcracks. Damage gradually develops from the surface to the core of the pillar. The damage process is tracked with acoustic emission monitoring. The study in this paper can provide an effective means for understanding the failure mechanism, planning, and design of mine pillars.

Hydroxyapatite formation on titania-based materials in a solution mimicking body fluid: Effects of manganese and iron addition in anatase.

Science.gov (United States)

Shin, Euisup; Kim, Ill Yong; Cho, Sung Baek; Ohtsuki, Chikara

2015-03-01

Hydroxyapatite formation on the surfaces of implanted materials plays an important role in osteoconduction of bone substitutes in bone tissues. Titania hydrogels are known to instigate hydroxyapatite formation in a solution mimicking human blood plasma. To date, the relationship between the surface characteristics of titania and hydroxyapatite formation on its surface remains unclear. In this study, titania powders with varying surface characteristics were prepared by addition of manganese or iron to examine hydroxyapatite formation in a type of simulated body fluid (Kokubo solution). Hydroxyapatite formation was monitored by observation of deposited particles with scale-like morphology on the prepared titania powders. The effect of the titania surface characteristics, i.e., crystal structure, zeta potential, hydroxy group content, and specific surface area, on hydroxyapatite formation was examined. Hydroxyapatite formation was observed on the surface of titania powders that were primarily anatase, and featured a negative zeta potential and low specific surface areas irrespective of the hydroxy group content. High specific surface areas inhibited the formation of hydroxyapatite because calcium and phosphate ions were mostly consumed by adsorption on the titania surface. Thus, these surface characteristics of titania determine its osteoconductivity following exposure to body fluid. Copyright © 2014 Elsevier B.V. All rights reserved.

Physicochemical characterization of functionalized-nanostructured-titania as a carrier of copper complexes for cancer treatment

International Nuclear Information System (INIS)

López, Tessy; Ortiz, Emma; Guevara, Patricia; Gómez, Esteban; Novaro, Octavio

2014-01-01

In the present paper we report the preparation and characterization of functionalized-TiO 2 (F-TiO 2 ) to obtain a biocompatible material to be used as carrier of alternative anticancer agents: copper acetate and copper acetylacetonate. The sol–gel procedure was used to prepare the fuctionalized titania material through hydrolysis and condensation of the titanium's butoxide. Sulfate, amine and phosphate ions served as functional groups which were anchored to the titania's surface. Mineral acids and gamma amine butyric acid were the precursors and they were added at the initial step of the synthesis. The copper complexes were loaded on titania and were also added to the reactor synthesis from the beginning. Infrared and ultraviolet–visible spectroscopies were the principal techniques used to the characterization of F-TiO 2 and copper complexes loaded on titania materials. Transmission Electronic Microscopy (TEM) was used to complement the characterization's studies. The biocompatibility of F-TiO 2 was evaluated by treating different cancer cell lines with increased concentration of this compound. The amine, the sulfate and the phosphate on the titania's surface, as well as the integral structures of the metal complexes on titania were well identified by infrared and ultraviolet–visible spectroscopies. The TEM photographs of Cu(acac) 2 /F-TiO 2 and Cu(Oac) 2 /F-TiO 2 materials showed the formation of nanoparticles, which have sizes ranging from 4 to 10 nm, with no morphology alterations in comparison with F-TiO 2 nanoparticles, suggesting that the presence of low quantities of copper do not affect the structure of the nanoparticles. The Energy Dispersive Spectroscopy (EDS) confirms the presence of copper on the titania's nanoparticles. The biological results indicate that there is more than 90% cell survival, thus suggesting that F-TiO 2 does not cause damage to the cells. Therefore, highly biocompatible titania was obtained by

Iron carbide on titania surface modified with group VA oxides as Fischer-Tropsch catalysts

International Nuclear Information System (INIS)

Wachs, I.E.; Fiato, R.A.; Chersich, C.C.

1986-01-01

A catalyst is described comprising iron carbide supported on a surface modified titania wherein the support comprises an oxide of a metal selected form the group consisting of niobium, vanadium, tantalum or mixture thereof supported on the titania wherein at least a portion of the supported oxide of niobium, vanandium, tantalum or mixture is in a non-crystalline form. The amount of the supported oxide ranges from about 0.5 to 25 weight percent metal oxide on the titania support based on the total support composition and the catalyst contains at least about 2 milligrams of iron, calculated as Fe/sub 2/O/sub 3/, per square meter of support surface

Enhanced photocatalytic activity of titania-silica mixed oxide prepared via basic hydrolyzation

International Nuclear Information System (INIS)

Xie Chao; Xu Zili; Yang Qiujing; Xue Baoyong; Du Yaoguo; Zhang Jiahua

2004-01-01

Two different synthesis routes were applied to prepare TiO 2 -XSiO 2 (X denotes mol% of silica in titania-silica mixed oxides) with different silica concentrations by using ammonia water as hydrolysis catalyst. Through comparing the photocatalytic performance of two sets of mixed oxides, we found that the photocatalytic activity of mixed oxides prepared via the route which can promote homogeneity, was significantly enhanced as compared with that of counterparts prepared via the another route, and the highest photocatalytic activity obtained by adding about 9.1 mol% silica into titania was much higher than that of pure TiO 2 . The mixed oxides were investigated by means of XRD, thermal analysis, UV-vis, FT-IR and XPS. The characterization results suggest that, in comparison with pure TiO 2 , the mixed oxides exhibit smaller crystallite size and higher thermal stability which can elevate the temperature of anatase to rutile phase transformation due to the addition of silica. Furthermore, Broensted acidity, which is associated with the formation of Ti-O-Si hetero linkages where tetrahedrally coordinated silica is chemically mixed with the octahedral titania matrix, may be a very important contribution to the enhanced photocatalytic activity of titania-silica mixed oxides as well

Photocatalytic degradation of paraoxon-ethyl in aqueous solution using titania nanoparticulate film

International Nuclear Information System (INIS)

Prasad, G.K.; Ramacharyulu, P.V.R.K.; Kumar, J. Praveen; Srivastava, A.R.; Singh, Beer

2012-01-01

Photocatalytic degradation of paraoxon-ethyl (o,o-diethyl o-(4-nitrophenyl) phosphate), a well known surrogate of chemical warfare agents, in aqueous solution was studied by using titania nanoparticulate film. Reaction followed pseudo first order behaviour. Photolytic degradation reaction of paraoxon-ethyl demonstrated relatively low rate with a value of rate constant of 2.5 × 10 −3 min −1 . Whereas, degradation reaction in the presence of titania nanoparticulate film and UV light displayed enhanced rate with a value of rate constant of 6.9 × 10 −3 min −1 due to photocatalysis. Gas chromatography–mass spectrometry analysis showed the formation of p-nitrophenol, o,o-diethyl phosphonic acid, o-ethyl, diphosphonic acid, phosphoric acid, dimerized product of o,o-diethyl phosphonic acid, acetaldehyde, and carbon dioxide due to photocatalytic degradation of paraoxon-ethyl. It indicates that, photocatalytic degradation reaction begins with destruction of P–O–C bonds. Subsequently, P, C atoms were found to be oxidized gradually, and contributed to its photocatalytic degradation. - Highlights: ► Synthesis of titania nanoparticles by sol–gel method. ► Fabrication of titania nanoparticulate film by dip coating. ► Paraoxon ethyl degradation reactions followed pseudo first order behaviour. ► Paraoxon-ethyl degraded to non toxic compounds like CO 2 , acetaldehyde, and nitrophenol.

Plasmonic Titania Photo catalysts Active under UV and Visible-Light Irradiation: Influence of Gold Amount, Size, and Shape

International Nuclear Information System (INIS)

Kowalska, E.; Rau, S.; Kowalska, E.; Kowalska, E.; Ohtani, B.

2012-01-01

Plasmonic titania photo catalysts were prepared by titania modification with gold by photo deposition. It was found that for smaller amount of deposited gold (≤ 0.1 wt%), anatase presence and large surface area were beneficial for efficient hydrogen evolution during methanol dehydrogenation. After testing twelve amounts of deposited gold on large rutile titania, the existence of three optima for 0.5, 2 and >6 wt% of gold was found during acetic acid degradation. Under visible light irradiation, in the case of small gold NPs deposited on fine anatase titania, the dependence of photo activity on gold amount was parabolic, and large gold amount (2 wt%), observable as an intensively coloured powder, caused photo activity decrease. While for large gold NPs deposited on large rutile titania, the dependence represented cascade increase, due to change of size and shape of deposited gold with its amount increase. It has been thought that spherical/hemispherical shape of gold NPs, in comparison with rod-like ones, is beneficial for higher level of photo activity under visible light irradiation. For all tested systems and regardless of deposited amount of gold, each rutile Au/TiO 2 photo catalyst of large gold and titania NPs exhibited much higher photo activity than anatase Au/TiO 2 of small gold and titania NPs

Asymmetric liquid wetting and spreading on surfaces with slanted micro-pillar arrays

KAUST Repository

Yang, Xiaoming

2013-01-01

Uni-directional liquid spreading on asymmetric silicone-fabricated nanostructured surfaces has recently been reported. In this work, uniformly deflected polydimethylsiloxane (PDMS) micro-pillars covered with silver films were fabricated. Asymmetric liquid wetting and spreading behaviors in a preferential direction were observed on the slanted micro-pillar surfaces and a micro-scale thin liquid film advancing ahead of the bulk liquid droplet was clearly observed by high-speed video imaging. It is found that the slanted micro-pillar array is able to promote or inhibit the propagation of this thin liquid film in different directions by the asymmetric capillary force. The spreading behavior of the bulk liquid was guided and finally controlled by this micro-scale liquid film. Different spreading regimes are defined by the relationship between the liquid intrinsic contact angle and the critical angles, which were determined by the pillar height, pillar deflection angle and inter-pillar spacing. © The Royal Society of Chemistry 2013.

Scattering of spermatozoa off cylindrical pillars

Science.gov (United States)

Bukatin, Anton; Lushi, Enkeleida; Kantsler, Vasily

2017-11-01

The motion of micro-swimmers in structured environments, even though crucial in processes such as in vivo and in vitro egg fertilization, is still not completely understood. We combine microfluidic experiments with mathematical modeling of 3D swimming near convex surfaces to quantify the dynamics of individual sperm cells in the proximity of cylindrical pillars. Our results show that the hydrodynamic and contact forces that account for the shape asymmetry and flagellar motion, are crucial in correctly describing the dynamics observed in the experiments. Last, we discuss how the size of the cylindrical obstacles determines whether the swimmers scatter off or get trapped circling the pillar.

Effect of titania particles on the microstructure and properties of the epoxy resin coatings on sintered NdFeB permanent magnets

International Nuclear Information System (INIS)

Xu, J.L.; Huang, Z.X.; Luo, J.M.; Zhong, Z.C.

2014-01-01

The nanometer titania particles enhanced epoxy resin composite coatings were prepared on the sintered NdFeB permanent magnets by cathodic electrophoretic deposition. The effects of titania particle concentrations on the microstructure and properties of the epoxy coatings were investigated by surface and cross-sectional morphologies observation, surface roughness and microhardness measurement, H 2 SO 4 solution immersion test, neutral salt spray test and magnetic properties measurement. The results showed that the thickness of epoxy coatings with and without the titania particles addition was about 40 μm. The titania particles could be uniformly dispersed and embedded in the epoxy matrix if the titania particles concentration was lower than 40 g/l. With increasing titania particle concentrations, the number of the particles embedded in the epoxy matrix increased and the surface roughness and microhardness of the composite coatings increased. At the same time, the weight loss of the coated samples immersed in H 2 SO 4 solution decreased and the neutral salt spray time of the coated samples prolonged. It could be concluded that the titania particles did not change the thickness of the epoxy coatings and did not deteriorate the magnetic properties of NdFeB substrates, but could greatly improve the microhardness and corrosion resistance of the epoxy coatings. - Highlights: • The titania particles enhanced epoxy resin coatings were prepared on sintered NdFeB by cathodic electrophoretic deposition. • The titania particles could be uniformly dispersed and embedded in the epoxy resin matrix. • With increasing titania concentrations, the surface roughness and the microhardness of composite coatings increased. • The addition of titania particles greatly improved the corrosion resistance of the epoxy coatings. • The composition coatings did not deteriorate the magnetic properties of NdFeB substrates

Effect of titania particles on the microstructure and properties of the epoxy resin coatings on sintered NdFeB permanent magnets

Energy Technology Data Exchange (ETDEWEB)

Xu, J.L., E-mail: jlxu@nchu.edu.cn; Huang, Z.X.; Luo, J.M.; Zhong, Z.C., E-mail: zzhong.2006@yahoo.com.cn

2014-04-15

The nanometer titania particles enhanced epoxy resin composite coatings were prepared on the sintered NdFeB permanent magnets by cathodic electrophoretic deposition. The effects of titania particle concentrations on the microstructure and properties of the epoxy coatings were investigated by surface and cross-sectional morphologies observation, surface roughness and microhardness measurement, H{sub 2}SO{sub 4} solution immersion test, neutral salt spray test and magnetic properties measurement. The results showed that the thickness of epoxy coatings with and without the titania particles addition was about 40 μm. The titania particles could be uniformly dispersed and embedded in the epoxy matrix if the titania particles concentration was lower than 40 g/l. With increasing titania particle concentrations, the number of the particles embedded in the epoxy matrix increased and the surface roughness and microhardness of the composite coatings increased. At the same time, the weight loss of the coated samples immersed in H{sub 2}SO{sub 4} solution decreased and the neutral salt spray time of the coated samples prolonged. It could be concluded that the titania particles did not change the thickness of the epoxy coatings and did not deteriorate the magnetic properties of NdFeB substrates, but could greatly improve the microhardness and corrosion resistance of the epoxy coatings. - Highlights: • The titania particles enhanced epoxy resin coatings were prepared on sintered NdFeB by cathodic electrophoretic deposition. • The titania particles could be uniformly dispersed and embedded in the epoxy resin matrix. • With increasing titania concentrations, the surface roughness and the microhardness of composite coatings increased. • The addition of titania particles greatly improved the corrosion resistance of the epoxy coatings. • The composition coatings did not deteriorate the magnetic properties of NdFeB substrates.

Porous titania surfaces on titanium with hierarchical macro- and mesoporosities for enhancing cell adhesion, proliferation and mineralization

International Nuclear Information System (INIS)

Han, Guang; Müller, Werner E.G.; Wang, Xiaohong; Lilja, Louise; Shen, Zhijian

2015-01-01

Titanium received a macroporous titania surface layer by anodization, which contains open pores with average pore diameter around 5 μm. An additional mesoporous titania top layer following the contour of the macropores, of 100–200 nm thickness and with a pore diameter of 10 nm, was formed by using the evaporation-induced self-assembly (EISA) method with titanium (IV) tetraethoxide as the precursor. A coherent laminar titania surface layer was thus obtained, creating a hierarchical macro- and mesoporous surface that was characterized by high-resolution electron microscopy. The interfacial bonding between the surface layers and the titanium matrix was characterized by the scratch test that confirmed a stable and strong bonding of titania surface layers on titanium. The wettability to water and the effects on the osteosarcoma cell line (SaOS-2) proliferation and mineralization of the formed titania surface layers were studied systematically by cell culture and scanning electron microscopy. The results proved that the porous titania surface with hierarchical macro- and mesoporosities was hydrophilic that significantly promoted cell attachment and spreading. A synergistic role of the hierarchical macro- and mesoporosities was revealed in terms of enhancing cell adhesion, proliferation and mineralization, compared with the titania surface with solo scale topography. - Highlights: • We developed a hierarchical macro- and mesoporous surface layer on titanium. • New surface layer was strong enough to sustain on implant surface. • New surface owned better surface wettability. • New surface can promote SaOS-2 cell adhesion, proliferation and mineralization. • Synergistic effects on cell responses occur when two porous structures coexist

Porous titania surfaces on titanium with hierarchical macro- and mesoporosities for enhancing cell adhesion, proliferation and mineralization

Energy Technology Data Exchange (ETDEWEB)

Han, Guang [Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, 10691 Stockholm (Sweden); Müller, Werner E.G.; Wang, Xiaohong [ERC Advanced Grant Research Group at the Institute for Physiological Chemistry, University Medical Center of the Johannes Gutenberg University Mainz, Duesbergweg 6, D-55128 Mainz (Germany); Lilja, Louise [Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, 10691 Stockholm (Sweden); Department of Physics, Chemistry and Biology, Linköping University, SE-581 83 Linköping (Sweden); Shen, Zhijian, E-mail: shen@mmk.su.se [Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, 10691 Stockholm (Sweden)

2015-02-01

Titanium received a macroporous titania surface layer by anodization, which contains open pores with average pore diameter around 5 μm. An additional mesoporous titania top layer following the contour of the macropores, of 100–200 nm thickness and with a pore diameter of 10 nm, was formed by using the evaporation-induced self-assembly (EISA) method with titanium (IV) tetraethoxide as the precursor. A coherent laminar titania surface layer was thus obtained, creating a hierarchical macro- and mesoporous surface that was characterized by high-resolution electron microscopy. The interfacial bonding between the surface layers and the titanium matrix was characterized by the scratch test that confirmed a stable and strong bonding of titania surface layers on titanium. The wettability to water and the effects on the osteosarcoma cell line (SaOS-2) proliferation and mineralization of the formed titania surface layers were studied systematically by cell culture and scanning electron microscopy. The results proved that the porous titania surface with hierarchical macro- and mesoporosities was hydrophilic that significantly promoted cell attachment and spreading. A synergistic role of the hierarchical macro- and mesoporosities was revealed in terms of enhancing cell adhesion, proliferation and mineralization, compared with the titania surface with solo scale topography. - Highlights: • We developed a hierarchical macro- and mesoporous surface layer on titanium. • New surface layer was strong enough to sustain on implant surface. • New surface owned better surface wettability. • New surface can promote SaOS-2 cell adhesion, proliferation and mineralization. • Synergistic effects on cell responses occur when two porous structures coexist.

Aespoe Pillar Stability Experiment. Acoustic emission and ultrasonic monitoring

Energy Technology Data Exchange (ETDEWEB)

Haycox, Jon; Pettitt, Will; Young, R. Paul [Applied Seismology Consultants Ltd., Shrewsbury (United Kingdom)

2005-12-15

This report describes the results from acoustic emission (AE) and ultrasonic monitoring of the Aespoe Pillar Stability Experiment (APSE) at SKB's Hard Rock Laboratory (HRL), Sweden. The APSE is being undertaken to demonstrate the current capability to predict spalling in a fractured rock mass using numerical modelling techniques, and to demonstrate the effect of backfill and confining pressure on the propagation of micro-cracks in rock adjacent to deposition holes within a repository. An ultrasonic acquisition system has provided acoustic emission and ultrasonic survey monitoring throughout the various phases of the experiment. Results from the entire data set are provided with this document so that they can be effectively compared to several numerical modelling studies, and to mechanical and thermal measurements conducted around the pillar volume, in an 'integrated analysis' performed by SKB staff. This document provides an in-depth summary of the AE and ultrasonic survey results for future reference. The pillar has been produced by excavating two 1.8 m diameter deposition holes 1 m apart. These were bored in 0.8 m steps using a Tunnel Boring Machine specially adapted for vertical drilling. The first deposition hole was drilled in December 2003. Preceding this a period of background monitoring was performed so as to obtain a datum for the results. The hole was then confined to 0.7 MPa internal over pressure using a specially designed water-filled bladder. The second deposition hole was excavated in March 2004. Heating of the pillar was performed over a two month period between ending in July 2004, when the confined deposition hole was slowly depressurised. Immediately after depressurisation the pillar was allowed to cool with cessation of monitoring occurring a month later. A total of 36,676 AE triggers were recorded over the reporting period between 13th October 2003 and 14th July 2004. Of these 15,198 have produced AE locations. The AE data set

Aespoe Pillar Stability Experiment. Acoustic emission and ultrasonic monitoring

International Nuclear Information System (INIS)

Haycox, Jon; Pettitt, Will; Young, R. Paul

2005-11-01

This report describes the results from acoustic emission (AE) and ultrasonic monitoring of the Aespoe Pillar Stability Experiment (APSE) at SKB's Hard Rock Laboratory (HRL), Sweden. The APSE is being undertaken to demonstrate the current capability to predict spalling in a fractured rock mass using numerical modelling techniques, and to demonstrate the effect of backfill and confining pressure on the propagation of micro-cracks in rock adjacent to deposition holes within a repository. An ultrasonic acquisition system has provided acoustic emission and ultrasonic survey monitoring throughout the various phases of the experiment. Results from the entire data set are provided with this document so that they can be effectively compared to several numerical modelling studies, and to mechanical and thermal measurements conducted around the pillar volume, in an 'integrated analysis' performed by SKB staff. This document provides an in-depth summary of the AE and ultrasonic survey results for future reference. The pillar has been produced by excavating two 1.8 m diameter deposition holes 1 m apart. These were bored in 0.8 m steps using a Tunnel Boring Machine specially adapted for vertical drilling. The first deposition hole was drilled in December 2003. Preceding this a period of background monitoring was performed so as to obtain a datum for the results. The hole was then confined to 0.7 MPa internal over pressure using a specially designed water-filled bladder. The second deposition hole was excavated in March 2004. Heating of the pillar was performed over a two month period between ending in July 2004, when the confined deposition hole was slowly depressurised. Immediately after depressurisation the pillar was allowed to cool with cessation of monitoring occurring a month later. A total of 36,676 AE triggers were recorded over the reporting period between 13th October 2003 and 14th July 2004. Of these 15,198 have produced AE locations. The AE data set shows an intense

Flexible Pillared Graphene-Paper Electrodes for High-Performance Electrochemical Supercapacitors

Energy Technology Data Exchange (ETDEWEB)

Wang, Gongkai; Sun, Xiang; Lu, Fengyuan; Sun, Hongtao; Yu, Mingpeng; Jiang, Weilin; Liu, Changsheng; Lian, Jie

2011-12-08

Flexible graphene paper (GP) pillared by carbon black (CB) nanoparticles using a simple vacuum filtration method is developed as a high-performance electrode material for supercapacitors. Through the introduction of CB nanoparticles as spacers, the self-restacking of graphene sheets during the filtration process is mitigated to a great extent. The pillared GP-based supercapacitors exhibit excellent electrochemical performances and cyclic stabilities compared with GP without the addition of CB nanoparticles. At a scan rate of 10 mV s^-1, the specific capacitance of the pillared GP is 138 F g^-1 and 83.2 F g^-1 with negligible 3.85% and 4.35% capacitance degradation after 2000 cycles in aqueous and organic electrolytes, respectively. At an extremely fast scan rate of 500 mV s^-1, the specific capacitance can reach 80 F g^-1 in aqueous electrolyte. No binder is needed for assembling the supercapacitor cells and the pillared GP itself may serve as a current collector due to its intrinsic high electrical conductivity. Finally, the pillared GP has great potential in the development of promising flexible and ultralight-weight supercapacitors for electrochemical energy storage.

Synthesis of mesoporous titania by homogeneous hydrolysis of titania oxo-sulfate in the presence of cationic and anionic surfactants

Czech Academy of Sciences Publication Activity Database

Štengl, Václav; Houšková, Vendula; Murafa, Nataliya; Bakardjieva, Snejana

2010-01-01

Roč. 54, č. 4 (2010), s. 368-378 ISSN 0862-5468 R&D Projects: GA ČR GA203/08/0334 Institutional research plan: CEZ:AV0Z40320502 Keywords : surfactant * titania * mesoporous * photocatalyst Subject RIV: CA - Inorganic Chemistry Impact factor: 0.297, year: 2010

Design of titania nanotube structures by focused laser beam direct writing

International Nuclear Information System (INIS)

Enachi, Mihai; Stevens-Kalceff, Marion A.; Sarua, Andrei; Ursaki, Veaceslav; Tiginyanu, Ion

2013-01-01

In this work, we report on electrochemical fabrication of titania films consisting of nanotubes (NTs) and their treatment by focused laser beam. The results of sample characterization by optical and scanning electron microscopy, cathodoluminescence imaging, and Raman scattering scanning spectroscopy are compared to those inherent to specimens subjected to thermal treatment in a furnace. The obtained data demonstrate possibilities for controlling crystallographic structure of TiO 2 NTs by focused laser beam direct writing. These findings open new prospects for the design and fabrication of spatial architectures based on titania nanotubes

Oxidations of amines with molecular oxygen using bifunctional gold–titania catalysts

DEFF Research Database (Denmark)

Klitgaard, Søren Kegnæs; Egeblad, Kresten; Mentzel, Uffe Vie

2008-01-01

–titania catalysts can be employed to facilitate the oxidation of amines into amides with high selectivity. Furthermore, we report that pure titania is in fact itself a catalyst for the oxidation of amines with molecular oxygen under very mild conditions. We demonstrate that these new methodologies open up for two......Over the past decades it has become clear that supported gold nanoparticles are surprisingly active and selective catalysts for several green oxidation reactions of oxygen-containing hydrocarbons using molecular oxygen as the stoichiometric oxidant. We here report that bifunctional gold...

Field emission from a single nanomechanical pillar

International Nuclear Information System (INIS)

Kim, Hyun S; Qin Hua; Westphall, Michael S; Smith, Lloyd M; Blick, Robert H

2007-01-01

We measured field emission from a silicon nanopillar mechanically oscillating between two electrodes. The pillar has a height of about 200 nm and a diameter of 50 nm, allowing resonant mechanical excitations at radio frequencies. The tunnelling barriers for field emission are mechanically modulated via displacement of the gold island on top of the pillar. We present a rich frequency-dependent response of the emission current in the frequency range of 300-400 MHz at room temperature. Modified Fowler-Nordheim field emission is observed and attributed to the mechanical oscillations of the nanopillar

Dynamic Diffraction Studies on the Crystallization, Phase Transformation, and Activation Energies in Anodized Titania Nanotubes

Directory of Open Access Journals (Sweden)

Hani Albetran

2018-02-01

Full Text Available The influence of calcination time on the phase transformation and crystallization kinetics of anodized titania nanotube arrays was studied using in-situ isothermal and non-isothermal synchrotron radiation diffraction from room temperature to 900 °C. Anatase first crystallized at 400 °C, while rutile crystallized at 550 °C. Isothermal heating of the anodized titania nanotubes by an increase in the calcination time at 400, 450, 500, 550, 600, and 650 °C resulted in a slight reduction in anatase abundance, but an increase in the abundance of rutile because of an anatase-to-rutile transformation. The Avrami equation was used to model the titania crystallization mechanism and the Arrhenius equation was used to estimate the activation energies of the titania phase transformation. Activation energies of 22 (10 kJ/mol for the titanium-to-anatase transformation, and 207 (17 kJ/mol for the anatase-to-rutile transformation were estimated.

Dynamic Diffraction Studies on the Crystallization, Phase Transformation, and Activation Energies in Anodized Titania Nanotubes.

Science.gov (United States)

Albetran, Hani; Vega, Victor; Prida, Victor M; Low, It-Meng

2018-02-23

The influence of calcination time on the phase transformation and crystallization kinetics of anodized titania nanotube arrays was studied using in-situ isothermal and non-isothermal synchrotron radiation diffraction from room temperature to 900 °C. Anatase first crystallized at 400 °C, while rutile crystallized at 550 °C. Isothermal heating of the anodized titania nanotubes by an increase in the calcination time at 400, 450, 500, 550, 600, and 650 °C resulted in a slight reduction in anatase abundance, but an increase in the abundance of rutile because of an anatase-to-rutile transformation. The Avrami equation was used to model the titania crystallization mechanism and the Arrhenius equation was used to estimate the activation energies of the titania phase transformation. Activation energies of 22 (10) kJ/mol for the titanium-to-anatase transformation, and 207 (17) kJ/mol for the anatase-to-rutile transformation were estimated.

Fabrication and structural characterization of highly ordered titania nanotube arrays

Science.gov (United States)

Shi, Hongtao; Ordonez, Rosita

Titanium (Ti) dioxide nanotubes have drawn much attention in the past decade due to the fact that titania is an extremely versatile material with a variety of technological applications. Anodizing Ti in different electrolytes has proved to be quite successful so far in creating the nanotubes, however, their degree of order is still not nearly as good as nanoporous anodic alumina. In this work, we first deposit a thin layer of aluminum (Al) onto electropolished Ti substrates, using thermal evaporation. Such an Al layer is then anodized in 0.3 M oxalic acid, forming an ordered nanoporous alumina mask on top of Ti. Afterwards, the anodization of Ti is accomplished at 20 V in solutions containing 1 M NaH2PO4 and 0.5% HF or H2SO4, which results in the creation of ordered titania nanotube arrays. The inner pore diameter of the nanotubes can be tuned from ~50 nm to ~75 nm, depending on the anodization voltage applied to Al or Ti. X-ray diffractometry shows the as-grown titania nanotubes are amorphous. Samples annealed at different temperatures in ambient atmosphere will be also reported.

Physicochemical characterization of functionalized-nanostructured-titania as a carrier of copper complexes for cancer treatment

Energy Technology Data Exchange (ETDEWEB)

López, Tessy [Nanotechnology and Nanomedicine Laboratory, Metropolitan Autonomous University-Xochimilco, Calzada del Hueso 1100, Villa Quietud, Coyoacán, 04960 México D.F. (Mexico); Nanotechnology Laboratory, National Institute of Neurology and Neurosurgery “MVS”, Avenida Insurgentes Sur 3877, La Fama, Tlalpan, 14269 México D.F. (Mexico); Department of Chemical and Biomolecular Engineering, Tulane University, 6823 St. Charles Avenue, New Orleans (United States); Ortiz, Emma, E-mail: emma170@hotmail.com [Nanotechnology Laboratory, National Institute of Neurology and Neurosurgery “MVS”, Avenida Insurgentes Sur 3877, La Fama, Tlalpan, 14269 México D.F. (Mexico); Guevara, Patricia [Neuroimmunology Laboratory, National Institute of Neurology and Neurosurgery “MVS”, Insurgentes Sur 3877, La Fama, Tlalpan, 14269 México D.F. (Mexico); Gómez, Esteban [Nanotechnology Laboratory, National Institute of Neurology and Neurosurgery “MVS”, Avenida Insurgentes Sur 3877, La Fama, Tlalpan, 14269 México D.F. (Mexico); Novaro, Octavio [Institute of Physics-UNAM, Circuito de la Investigación Científica Ciudad Universitaria, CP 04510 México D.F. (Mexico)

2014-07-01

In the present paper we report the preparation and characterization of functionalized-TiO{sub 2} (F-TiO{sub 2}) to obtain a biocompatible material to be used as carrier of alternative anticancer agents: copper acetate and copper acetylacetonate. The sol–gel procedure was used to prepare the fuctionalized titania material through hydrolysis and condensation of the titanium's butoxide. Sulfate, amine and phosphate ions served as functional groups which were anchored to the titania's surface. Mineral acids and gamma amine butyric acid were the precursors and they were added at the initial step of the synthesis. The copper complexes were loaded on titania and were also added to the reactor synthesis from the beginning. Infrared and ultraviolet–visible spectroscopies were the principal techniques used to the characterization of F-TiO{sub 2} and copper complexes loaded on titania materials. Transmission Electronic Microscopy (TEM) was used to complement the characterization's studies. The biocompatibility of F-TiO{sub 2} was evaluated by treating different cancer cell lines with increased concentration of this compound. The amine, the sulfate and the phosphate on the titania's surface, as well as the integral structures of the metal complexes on titania were well identified by infrared and ultraviolet–visible spectroscopies. The TEM photographs of Cu(acac){sub 2}/F-TiO{sub 2} and Cu(Oac){sub 2}/F-TiO{sub 2} materials showed the formation of nanoparticles, which have sizes ranging from 4 to 10 nm, with no morphology alterations in comparison with F-TiO{sub 2} nanoparticles, suggesting that the presence of low quantities of copper do not affect the structure of the nanoparticles. The Energy Dispersive Spectroscopy (EDS) confirms the presence of copper on the titania's nanoparticles. The biological results indicate that there is more than 90% cell survival, thus suggesting that F-TiO{sub 2} does not cause damage to the cells. Therefore

Macroscale and Nanoscale Morphology Evolution during in Situ Spray Coating of Titania Films for Perovskite Solar Cells.

Science.gov (United States)

Su, Bo; Caller-Guzman, Herbert A; Körstgens, Volker; Rui, Yichuan; Yao, Yuan; Saxena, Nitin; Santoro, Gonzalo; Roth, Stephan V; Müller-Buschbaum, Peter

2017-12-20

Mesoporous titania is a cheap and widely used material for photovoltaic applications. To enable a large-scale fabrication and a controllable pore size, we combined a block copolymer-assisted sol-gel route with spray coating to fabricate titania films, in which the block copolymer polystyrene-block-poly(ethylene oxide) (PS-b-PEO) is used as a structure-directing template. Both the macroscale and nanoscale are studied. The kinetics and thermodynamics of the spray deposition processes are simulated on a macroscale, which shows a good agreement with the large-scale morphology of the spray-coated films obtained in practice. On the nanoscale, the structure evolution of the titania films is probed with in situ grazing incidence small-angle X-ray scattering (GISAXS) during the spray process. The changes of the PS domain size depend not only on micellization but also on solvent evaporation during the spray coating. Perovskite (CH 3 NH 3 PbI 3 ) solar cells (PSCs) based on sprayed titania film are fabricated, which showcases the suitability of spray-deposited titania films for PSCs.

Synthesis and characterization of noble metal–titania core–shell nanostructures with tunable shell thickness

Directory of Open Access Journals (Sweden)

Bartosz Bartosewicz

2017-10-01

Full Text Available Core–shell nanostructures have found applications in many fields, including surface enhanced spectroscopy, catalysis and solar cells. Titania-coated noble metal nanoparticles, which combine the surface plasmon resonance properties of the core and the photoactivity of the shell, have great potential for these applications. However, the controllable synthesis of such nanostructures remains a challenge due to the high reactivity of titania precursors. Hence, a simple titania coating method that would allow better control over the shell formation is desired. A sol–gel based titania coating method, which allows control over the shell thickness, was developed and applied to the synthesis of Ag@TiO2 and Au@TiO2 with various shell thicknesses. The morphology of the synthesized structures was investigated using scanning electron microscopy (SEM. Their sizes and shell thicknesses were determined using tunable resistive pulse sensing (TRPS technique. The optical properties of the synthesized structures were characterized using UV–vis spectroscopy. Ag@TiO2 and Au@TiO2 structures with shell thickness in the range of ≈40–70 nm and 90 nm, for the Ag and Au nanostructures respectively, were prepared using a method we developed and adapted, consisting of a change in the titania precursor concentration. The synthesized nanostructures exhibited significant absorption in the UV–vis range. The TRPS technique was shown to be a very useful tool for the characterization of metal–metal oxide core–shell nanostructures.

Photocatalytic degradation of paraoxon-ethyl in aqueous solution using titania nanoparticulate film

Energy Technology Data Exchange (ETDEWEB)

Prasad, G.K., E-mail: gkprasad2001@yahoo.com; Ramacharyulu, P.V.R.K.; Kumar, J. Praveen; Srivastava, A.R.; Singh, Beer

2012-06-30

Photocatalytic degradation of paraoxon-ethyl (o,o-diethyl o-(4-nitrophenyl) phosphate), a well known surrogate of chemical warfare agents, in aqueous solution was studied by using titania nanoparticulate film. Reaction followed pseudo first order behaviour. Photolytic degradation reaction of paraoxon-ethyl demonstrated relatively low rate with a value of rate constant of 2.5 Multiplication-Sign 10{sup -3} min{sup -1}. Whereas, degradation reaction in the presence of titania nanoparticulate film and UV light displayed enhanced rate with a value of rate constant of 6.9 Multiplication-Sign 10{sup -3} min{sup -1} due to photocatalysis. Gas chromatography-mass spectrometry analysis showed the formation of p-nitrophenol, o,o-diethyl phosphonic acid, o-ethyl, diphosphonic acid, phosphoric acid, dimerized product of o,o-diethyl phosphonic acid, acetaldehyde, and carbon dioxide due to photocatalytic degradation of paraoxon-ethyl. It indicates that, photocatalytic degradation reaction begins with destruction of P-O-C bonds. Subsequently, P, C atoms were found to be oxidized gradually, and contributed to its photocatalytic degradation. - Highlights: Black-Right-Pointing-Pointer Synthesis of titania nanoparticles by sol-gel method. Black-Right-Pointing-Pointer Fabrication of titania nanoparticulate film by dip coating. Black-Right-Pointing-Pointer Paraoxon ethyl degradation reactions followed pseudo first order behaviour. Black-Right-Pointing-Pointer Paraoxon-ethyl degraded to non toxic compounds like CO{sub 2}, acetaldehyde, and nitrophenol.

Ordered microporous layered lanthanide 1,3,5-benzenetriphosphonates pillared with cationic organic molecules.

Science.gov (United States)

Araki, Takahiro; Kondo, Atsushi; Maeda, Kazuyuki

2015-04-13

Novel isomorphous pillared-layer-type crystalline lanthanide 1,3,5-benzenetriphosphonates were prepared with bpy and dbo as organic pillars (LnBP-bpy and LnBP-dbo; Ln: Ce, Pr, and Nd). Ab initio crystal structure solution using synchrotron X-ray powder diffraction data revealed that the organic pillars do not exist as neutral coordinating ligands but as cationic molecules. Especially the LnBP-dbo phases have ordered interlayer space filled with water molecules between the dbo pillars, and the interlayer water is successfully removed by heating under vacuum with slightly distorted but basically retained pillared layer structures. Microporosity of the materials is confirmed by adsorption of nitrogen, carbon dioxide, and hydrogen gases. Such microporous layered metal phosphonates pillared with cationic molecules should be unprecedented and should offer new strategies to design ordered microporous materials. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

First principles study of vibrational dynamics of ceria-titania hybrid clusters

Energy Technology Data Exchange (ETDEWEB)

Majid, Abdul, E-mail: abdulmajid40@yahoo.com; Bibi, Maryam [University of Gujrat, Department of Physics (Pakistan)

2017-04-15

Density functional theory based calculations were performed to study vibrational properties of ceria, titania, and ceria-titania hybrid clusters. The findings revealed the dominance of vibrations related to oxygen when compared to those of metallic atoms in the clusters. In case of hybrid cluster, the softening of normal modes related to exterior oxygen atoms in ceria and softening/hardening of high/low frequency modes related to titania dimmers are observed. The results calculated for monomers conform to symmetry predictions according to which three IR and three Raman active modes were detected for TiO{sub 2}, whereas two IR active and one Raman active modes were observed for CeO{sub 2}. The comparative analysis indicates that the hybrid cluster CeTiO{sub 4} contains simultaneous vibrational fingerprints of the component dimmers. The symmetry, nature of vibrations, IR and Raman activity, intensities, and atomic involvement in different modes of the clusters are described in detail. The study points to engineering of CeTiO{sub 4} to tailor its properties for technological visible region applications in photocatalytic and electrochemical devices.

Surface characterization of Ag/Titania adsorbents

International Nuclear Information System (INIS)

Samokhvalov, Alexander; Nair, Sachin; Duin, Evert C.; Tatarchuk, Bruce J.

2010-01-01

The Ag/Titania adsorbent for selective removal of the desulfurization-refractive polycyclic aromatic sulfur heterocycles (PASHs) from liquid hydrocarbon fuels was prepared, its total and the Ag specific surface area were determined and the surface reaction sites in the sorbent that may be active in the adsorptive selective desulfurization were characterized by several spectroscopic and surface science techniques. The sorbent contains Ag, Ti, O and spurious C on its surface, as by the XPS measurements. Silver is present as an oxide, as judged by the XPS Auger parameter (AP). The complementary electron spin resonance (ESR) spectroscopy confirms that the majority of Ag is present in the diamagnetic Ag 1+ form, with the minor concentration (∼0.1% of total Ag) present as Ag 2+ . The findings by XPS and ESR are confirmed by the XRD, UV-vis spectroscopy and thermodynamic considerations. The supported Ag is highly dispersed on the surface of the titania support, with the particle size of ∼30-60 A depending on Ag content, with an Ag specific surface area of ∼7-14 m 2 /g, vs. the total surface area of ∼114-58 m 2 /g.

Flexible pillared graphene-paper electrodes for high-performance electrochemical supercapacitors.

Science.gov (United States)

Wang, Gongkai; Sun, Xiang; Lu, Fengyuan; Sun, Hongtao; Yu, Mingpeng; Jiang, Weilin; Liu, Changsheng; Lian, Jie

2012-02-06

Flexible graphene paper (GP) pillared by carbon black (CB) nanoparticles using a simple vacuum filtration method is developed as a high-performance electrode material for supercapacitors. Through the introduction of CB nanoparticles as spacers, the self-restacking of graphene sheets during the filtration process is mitigated to a great extent. The pillared GP-based supercapacitors exhibit excellent electrochemical performances and cyclic stabilities compared with GP without the addition of CB nanoparticles. At a scan rate of 10 mV s(-1) , the specific capacitance of the pillared GP is 138 F g(-1) and 83.2 F g(-1) with negligible 3.85% and 4.35% capacitance degradation after 2000 cycles in aqueous and organic electrolytes, respectively. At an extremely fast scan rate of 500 mV s (-1) , the specific capacitance can reach 80 F g(-1) in aqueous electrolyte. No binder is needed for assembling the supercapacitor cells and the pillared GP itself may serve as a current collector due to its intrinsic high electrical conductivity. The pillared GP has great potential in the development of promising flexible and ultralight-weight supercapacitors for electrochemical energy storage. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Extending and implementing the Persistent ID pillars

Science.gov (United States)

Car, Nicholas; Golodoniuc, Pavel; Klump, Jens

2017-04-01

The recent double decade anniversary of scholarly persistent identifier use has triggered journal special editions such as "20 Years of Persistent Identifiers". For such a publication, it is apt to consider the longevity of some persistent identifier (PID) mechanisms (Digital Object Identifiers) and the partial disappearance of others (Life Sciences IDs). We have previously postulated a set of "PID Pillars" [1] which are design principles aimed at ensuring PIDs can survive technology and social change and thus persist for the long term that we have drawn from our observations of PIDs at work over many years. The principles: describe how to ensure identifiers' system and organisation independence; codify the delivery of essential PID system functions; mandate a separation of PID functions from data delivery mechanisms; and require generation of policies detailing how change is handled. In this presentation, first we extend on our previous work of introducing the pillars by refining their descriptions, giving specific suggestions for each and presenting some work that addresses them. Second, we propose a baseline data model for persistent identifiers that, if used, would assist the separation of PID metadata and PID system functioning. This would allow PID system function specifics to change over time (e.g. resolver services or even resolution protocols) and yet preserve the PIDs themselves. Third, we detail our existing PID system — the PID Service [2] — that partially implements the pillars and describe both its successes and shortcomings. Finally, we describe our planned next-generation system that will aim to use the baseline data model and fully implement the pillars.

EFFECTS OF SYNTHESIS PARAMETERS ON THE STRUCTURE OF TITANIA NANOTUBES

Directory of Open Access Journals (Sweden)

M. NORANI MUTI

2008-08-01

Full Text Available Detection of hydrogen is crucial for industrial process control and medical applications where presence of hydrogen in breath indicates different type of health problems particularly in infants. A better performed sensor with high sensitivity, selectivity, reliability and faster response time would be critical and sought after especially for medical applications. Titanium dioxide nanotube structure is chosen as an active component in the gas sensor because of its highly sensitive electrical resistance to hydrogen over a wide range of concentrations. The objective of the work is to investigate the effect of the anodizing conditions on the structure of titania nanotubes produced by anodizing method. The anodizing parameters namely the ambient temperature and separation of electrodes are varied accordingly to find the optimum anodizing conditions for production of good quality titania nanotubes for enhanced properties based on their uniformity, coverage, pore size and crystallinity. Samples of nanotubes produced were subjected to annealing process at varying time and temperature in order to improve the crystallinity of the nanotubes. The highly ordered porous titania nanotubes produced by this method are of tabular shape and have good uniformity and alignment over large areas. The pore size of the titania nanotubes ranges from 47 to 94 nm, while the wall thickness is in the range of 17 to 26 nm. The length of the nanotubes was found to be about 280 nm. The structure of nanotubes changes from amorphous to crystalline after undergoing annealing treatment. Nanotubes have also shown to have better crystallinity if they were subjected to annealing treatment at higher temperature. The characteristics of nanotubes obtained are found to be agreeable to those that have been reported to show improved hydrogen gas sensing properties.

Recyclable Aggregates of Mesoporous Titania Synthesized by Thermal Treatment of Amorphous or Peptized Precursors

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Maria Cristina Mascolo

2018-03-01

Full Text Available Recyclable aggregates of mesoporous titania with different anatase–rutile ratios have been prepared by thermal treatments of either amorphous or peptized precursors. These last two have been obtained by hydrolysis of either Ti(OC2H54 or of Ti(OC2H54 in mixture with 5 mol % Zr(OC3H74 at room temperature in the presence of NH4OH as a catalyzing agent. The anatase–rutile ratio, the recyclable aggregates of the nano-sized particles, the mesoporosity, the surface area and the crystallinity of the resulting crystallized products of titania can be controlled by the synthesis parameters including: concentration of ammonia catalyst, stirring time and concentration of the peptizing HNO3, drying method of peptized precursors, calcination temperature, and finally the ramp rate up to the titania crystallization temperature. A broad range of synthesis parameters control the crystal sizes of titania particles produced. This allows catalyst preparation with very different crystal size, surface area, anatase to rutile crystal ratio and various mesoporous structures. Drying by lyophilization of precursors reduce the aggregation of the primary particles giving micro-/macroporous structures.

Optimization of pillar electrodes in subretinal prosthesis for enhanced proximity to target neurons

Science.gov (United States)

Flores, Thomas; Lei, Xin; Huang, Tiffany; Lorach, Henri; Dalal, Roopa; Galambos, Ludwig; Kamins, Theodore; Mathieson, Keith; Palanker, Daniel

2018-06-01

Objective. High-resolution prosthetic vision requires dense stimulating arrays with small electrodes. However, such miniaturization reduces electrode capacitance and penetration of electric field into tissue. We evaluate potential solutions to these problems with subretinal implants based on utilization of pillar electrodes. Approach. To study integration of three-dimensional (3D) implants with retinal tissue, we fabricated arrays with varying pillar diameter, pitch, and height, and implanted beneath the degenerate retina in rats (Royal College of Surgeons, RCS). Tissue integration was evaluated six weeks post-op using histology and whole-mount confocal fluorescence imaging. The electric field generated by various electrode configurations was calculated in COMSOL, and stimulation thresholds assessed using a model of network-mediated retinal response. Main results. Retinal tissue migrated into the space between pillars with no visible gliosis in 90% of implanted arrays. Pillars with 10 μm height reached the middle of the inner nuclear layer (INL), while 22 μm pillars reached the upper portion of the INL. Electroplated pillars with dome-shaped caps increase the active electrode surface area. Selective deposition of sputtered iridium oxide onto the cap ensures localization of the current injection to the pillar top, obviating the need to insulate the pillar sidewall. According to computational model, pillars having a cathodic return electrode above the INL and active anodic ring electrode at the surface of the implant would enable six times lower stimulation threshold, compared to planar arrays with circumferential return, but suffer from greater cross-talk between the neighboring pixels. Significance. 3D electrodes in subretinal prostheses help reduce electrode-tissue separation and decrease stimulation thresholds to enable smaller pixels, and thereby improve visual acuity of prosthetic vision.

Structurally stabilized organosilane-templated thermostable mesoporous titania.

Science.gov (United States)

Amoli, Vipin; Tiwari, Rashmi; Dutta, Arghya; Bhaumik, Asim; Sinha, Anil Kumar

2014-01-13

Structurally thermostable mesoporous anatase TiO2 (m-TiO2) nanoparticles, uniquely decorated with atomically dispersed SiO2, is reported for the first time. The inorganic Si portion of the novel organosilane template, used as a mesopores-directing agent, is found to be incorporated in the pore walls of the titania aggregates, mainly as isolated sites. This is evident by transmission electron microscopy and high-angle annular dark field scanning transmission electron microscopy, combined with electron dispersive X-ray spectroscopy. This type of unique structure provides exceptional stability to this new material against thermal collapse of the mesoporous structure, which is reflected in its high surface area (the highest known for anatase titania), even after high-temperature (550 °C) calcination. Control of crystallite size, pore diameter, and surface area is achieved by varying the molar ratios of the titanium precursor and the template during synthesis. These mesoporous materials retain their porosity and high surface area after template removal and further NaOH/HCl treatment to remove silica. We investigate their performance for dye-sensitized solar cells (DSSCs) with bilayer TiO2 electrodes, which are prepared by applying a coating of m-TiO2 onto a commercial titania (P25) film. The high surface area of the upper mesoporous layer in the P25-m-TiO2 DSSC significantly increases the dye loading ability of the photoanode. The photocurrent and fill factor for the DSSC with the bilayer TiO2 electrode are greatly improved. The large increase in photocurrent current (ca. 56%) in the P25-m-TiO2 DSSC is believed to play a significant role in achieving a remarkable increase in the photovoltaic efficiency (60%) of the device, compared to DSSCs with a monolayer of P25 as the electrode. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

(Gold core)/(titania shell) nanostructures for plasmon-enhanced photon harvesting and generation of reactive oxygen species

KAUST Repository

Fang, Caihong; Jia, Henglei; Chang, Shuai; Ruan, Qifeng; Wang, Peng; Chen, Tao; Wang, Jianfang

2014-01-01

Integration of gold and titania in a nanoscale core/shell architecture can offer large active metal/semiconductor interfacial areas and avoid aggregation and reshaping of the metal nanocrystal core. Such hybrid nanostructures are very useful for studying plasmon-enhanced/enabled processes and have great potential in light-harvesting applications. Herein we report on a facile route to (gold nanocrystal core)/(titania shell) nanostructures with their plasmon band synthetically variable from ∼700 nm to over 1000 nm. The coating method has also been applied to other mono- and bi-metallic Pd, Pt, Au nanocrystals. The gold/titania nanostructures have been employed as the scattering layer in dye-sensitized solar cells, with the resultant cells exhibiting a 13.3% increase in the power conversion efficiency and a 75% decrease in the scattering-layer thickness. Moreover, under resonant excitation, the gold/titania nanostructures can efficiently utilize low-energy photons to generate reactive oxygen species, including singlet oxygen and hydroxyl radicals.

Climatic impacts of stratospheric geoengineering with sulfate, black carbon and titania injection

Directory of Open Access Journals (Sweden)

A. C. Jones

2016-03-01

Full Text Available In this paper, we examine the potential climatic effects of geoengineering by sulfate, black carbon and titania injection against a baseline RCP8.5 scenario. We use the HadGEM2-CCS model to simulate scenarios in which the top-of-the-atmosphere radiative imbalance due to rising greenhouse gas concentrations is offset by sufficient aerosol injection throughout the 2020–2100 period. We find that the global-mean temperature is effectively maintained at historical levels for the entirety of the period for all three aerosol-injection scenarios, though there is a wide range of side-effects which are discussed in detail. The most prominent conclusion is that although the BC injection rate necessary to produce an equivalent global mean temperature response is much lower, the severity of stratospheric temperature changes (> +70 °C and precipitation impacts effectively exclude BC from being a viable option for geoengineering. Additionally, while it has been suggested that titania would be an effective particle because of its high scattering efficiency, it also efficiently absorbs solar ultraviolet radiation producing a significant stratospheric warming (> +20 °C. As injection rates and climatic impacts for titania are close to those for sulfate, there appears to be little benefit in terms of climatic influence of using titania when compared to the injection of sulfur dioxide, which has the added benefit of being well-modeled through extensive research that has been carried out on naturally occurring explosive volcanic eruptions.

Surface Properties of Photocatalytic Nano-Crystalline Titania Films and Reactor for Photocatalytic Degradation of Chloroform

DEFF Research Database (Denmark)

Søgaard, Erik Gydesen; Simonsen, Morten Enggrob; Jensen, Henrik

2006-01-01

In this work two immobilizations techniques of TiO2 onto glass were investigated; deposition of previously made titania powder (PMTP) and a sol-gel method. The titania powder used in this work was Degussa P25, Hombikat UV100 and a powder prepared in our laboratory SC134. The prepared TiO2 films w...

Dispersion tailoring of a silicon strip waveguide employing Titania-Alumina thin-film coating

DEFF Research Database (Denmark)

Guo, Kai; Christensen, Jesper B.; Christensen, Erik N.

2017-01-01

We numerically demonstrate dispersion tailoring of a silicon strip waveguide employing Titania-Alumina thin-film coating using a finite-difference mode solver. The proposed structure exhibits spectrally-flattened near-zero anomalous dispersion within the telecom wavelength range. We also numerica......We numerically demonstrate dispersion tailoring of a silicon strip waveguide employing Titania-Alumina thin-film coating using a finite-difference mode solver. The proposed structure exhibits spectrally-flattened near-zero anomalous dispersion within the telecom wavelength range. We also...

A microfluidic device with pillars

DEFF Research Database (Denmark)

2014-01-01

The invention provides a microfluidic device for mixing liquid reagents, the device comprises, a chip forming at least one reaction chamber between a bottom and a top and extending between an inlet and an outlet. To enable manufacturing from less rigid materials, the device comprises pillars...

Clay membrane made of natural high plasticity clay

DEFF Research Database (Denmark)

Foged, Niels; Baumann, Jens

1998-01-01

Leachate containment in Denmark has through years been regulated by the DIF Recommendation for Sanitary Landfill Liners (DS/R 466). It states natural clay deposits may be used for membrane material provided the membrane and drainage system may contain at least 95% of all leachate created throughout...... ion transport as well as diffusion.Clay prospection for clays rich in smectite has revealed large deposits of Tertiary clay of very high plasticity in the area around Rødbyhavn on the Danish island Lolland. The natural clay contains 60 to 75% smectite, dominantly as a sodium-type. The clay material...... has been evaluated using standardised methods related to mineralogy, classification, compaction and permeability, and initial studies of diffusion properties have been carried out. Furthermore, at a test site the construction methods for establishing a 0.15 to 0.3m thick clay membrane have been tested...

Clay membrane made of natural high plasticity clay:

DEFF Research Database (Denmark)

Foged, Niels; Baumann, Jens

1999-01-01

Leachate containment in Denmark has throughout the years been regulated by the DIF Recommendation for Sanitary Landfill Liners (DS/R4669. It states that natural clay deposits may be used as membrane material provided the membrane and drainage system contains at least 95% of all leachate created...... into account advective ion transport as well as diffusion. Clay prospecting for clays rich in smectite has revealed large deposits of Tertiary clay of very high plasticity in the area around Rødbyhavn on the Danish island of Lolland. The natural clay contains 60-75% smectite, dominantly as a sodium......-type. The clay material has been evaluated using the standardized methods related to mineralogy, classification, compaction and permeability, and initial studies of diffusion properties have been carried out. Furthermore, at a test site the construction methods for establishing a 0.15-0.3 m thick clay membrane...

Controlled release of phenytoin for epilepsy treatment from titania and silica based materials

International Nuclear Information System (INIS)

Lopez, Tessy; Ortiz, Emma; Meza, Doraliz; Basaldella, Elena; Bokhimi, Xim; Magana, Carlos; Sepulveda, Antonio; Rodriguez, Francisco; Ruiz, Javier

2011-01-01

Research highlights: → Template technique was used to obtain well ordered nanostructured materials: SBA-15 and titania tubes. → Phenytoin (PH), a drug used in epilepsy treatment, was loaded in these materials to used como PH release. → Loaded PH showed a good stability inside the used materials as observed by spectroscopy analysis. → The load-release PH are faster in nanostructured TiO2 tubes than in mesoporous silica matrix. → There is an inverse effect of the surface area of the structured materials on the amount of released PH. - Abstract: Template technique was used to obtain well ordered nanostructured materials: mesoporous silica and nanostructured titania tubes. This technique permits the synthesis of solids with controlled mesoporosity, where a large variety of molecules that have therapeutic activity can be hosted and further released to specific sites. In this work phenytoin (PH), a drug used in epilepsy treatment, was loaded in ordered mesoporous silica (SBA 15) and nanostructured titania tubes (TiO 2 ). The pure materials and those containing PH were characterized by X-ray diffraction, FTIR spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and N 2 adsorption-desorption at 77 K. In order to determine the loading capacity of the antiepileptic drug on these silica- and titania-based materials, the loading and release of PH was investigated using UV-vis spectroscopy. Tubular structures were found for the titania samples, for which the X-ray diffractograms showed to be formed by anatase and rutile phases. On the other hand, an amorphous phase was found in the silica sample. A highly ordered hexagonal structure of 1D cylindrical channels was also observed for this material. Loaded PH showed a good stability inside the used materials as observed by spectroscopy analysis. The adsorption and desorption of PH are faster in nanostructured TiO 2 tubes than in mesoporous silica matrix.

Thermal volume changes in clays and clay-stones

International Nuclear Information System (INIS)

Delage, P.; Sulem, J.; Mohajerani, M.; Tang, A.M.; Monfared, M.

2012-01-01

Document available in extended abstract form only. The disposal of high activity exothermic radioactive waste at great depth in clay host rocks will induce a temperature elevation that has been investigated in various underground research laboratories in Belgium, France and Switzerland through in-situ tests. Thermal effects are better known in clays (in particular Boom clay) than in clay-stone (e.g. Opalinus clay and Callovo-Oxfordian clay-stone). In terms of volume changes, Figure 1 confirms the findings of Hueckel and Baldi (1990) that volume changes depend on the over-consolidation ratio (OCR) of the clay. In drained conditions, normally consolidated clays exhibit plastic contraction when heated, whereas over-consolidated clay exhibit elastic dilation. The nature of thermal volume changes in heated clays obviously has a significant effect on thermally induced pore pressures, when drainage is not instantaneous like what occurs in-situ. Compared to clays, the thermal volume change behaviour of clay-stones is less well known than that of clays. clay-stone are a priori suspected to behave like over-consolidated clays. In this paper, a comparison of recent results obtained in the laboratory on the drained thermal volume changes of clay-stones is presented and discussed. It is difficult to run drained mechanical tests in clay-stones like the Opalinus clay and the Callovo-Oxfordian clay-stone because of their quite low permeability (10 -12 - 10 -13 m/s). This also holds true for thermal tests. Due to the significant difference in thermal expansion coefficient between minerals and water, it is necessary to adopt very slow heating rate (0.5 - 1 C/h) to avoid any thermal pressurization. To do so, a new hollow cylinder apparatus (100 mm external diameter, 60 mm internal diameter) with lateral drainages reducing the drainage length to half the sample thickness (10 mm) has been developed (Monfared et al. 2011). The results of a drained cyclic thermal test carried out on

Surface tension-induced PDMS micro-pillars with controllable tips and tilt angles

KAUST Repository

Li, Huawei; Fan, Yiqiang; Conchouso Gonzalez, David; Foulds, Ian G.

2013-01-01

This paper reports a novel method to fabricate three-dimensional (3D) polydimethylsiloxane (PDMS) micro-pillars using a CO2 laser-machined poly(methyl methacrylate) (PMMA) mold with through-holes. This method eliminates the requirements of expensive and complicated facilities to fabricate a 3D mold. The micro-pillars were formed by the capillary force that draws PDMS into the through-holes of the PMMA mold. The tilt angles of the micro-pillars depend on the tilt angles of the through-holes in the mold, and the concave and convex micro-lens tip shapes of the PDMS micro-pillars can be modified by changing the surface wettability of the PMMA through-holes.

Surface tension-induced PDMS micro-pillars with controllable tips and tilt angles

KAUST Repository

Li, Huawei

2013-12-21

This paper reports a novel method to fabricate three-dimensional (3D) polydimethylsiloxane (PDMS) micro-pillars using a CO2 laser-machined poly(methyl methacrylate) (PMMA) mold with through-holes. This method eliminates the requirements of expensive and complicated facilities to fabricate a 3D mold. The micro-pillars were formed by the capillary force that draws PDMS into the through-holes of the PMMA mold. The tilt angles of the micro-pillars depend on the tilt angles of the through-holes in the mold, and the concave and convex micro-lens tip shapes of the PDMS micro-pillars can be modified by changing the surface wettability of the PMMA through-holes.

A statistical physics consideration about the strength of small size metallic glass pillars

NARCIS (Netherlands)

Chen, Changqiang; Pei, Yutao; De Hosson, Jeff Th. M.; Skrotzki, W; Oertel, CG; Biermann, H; Heilmaier, M

2010-01-01

We have fabricated micro-/nano-pillars of a Zr-based metallic glass, Zr(50)Ti(16.5)Cu(15)Ni(18.5), with pillar tip diameters ranging from similar to 750 nm to similar to 110 nm. These pillars were mechanically tested quantitatively in-situ in a Transmission Electron Microscope (TEM). Due to a slight

Activity of nanosized titania synthesized from thermal decomposition of titanium (IV n-butoxide for the photocatalytic degradation of diuron

Directory of Open Access Journals (Sweden)

Jitlada Klongdee, Wansiri Petchkroh, Kosin Phuempoonsathaporn, Piyasan Praserthdam, Alisa S. Vangnai and Varong Pavarajarn

2005-01-01

Full Text Available Nanoparticles of anatase titania were synthesized by the thermal decomposition of titanium (IV n-butoxide in 1,4-butanediol. The powder obtained was characterized by various characterization techniques, such as XRD, BET, SEM and TEM, to confirm that it was a collection of single crystal anatase with particle size smaller than 15 nm. The synthesized titania was employed as catalyst for the photodegradation of diuron, a herbicide belonging to the phenylurea family, which has been considered as a biologically active pollutant in soil and water. Although diuron is chemically stable, degradation of diuron by photocatalyzed oxidation was found possible. The conversions achieved by titania prepared were in the range of 70–80% within 6 h of reaction, using standard UV lamps, while over 99% conversion was achieved under solar irradiation. The photocatalytic activity was compared with that of the Japanese Reference Catalyst (JRC-TIO-1 titania from the Catalysis Society of Japan. The synthesized titania exhibited higher rate and efficiency in diuron degradation than reference catalyst. The results from the investigations by controlling various reaction parameters, such as oxygen dissolved in the solution, diuron concentration, as well as light source, suggested that the enhanced photocatalytic activity was the result from higher crystallinity of the synthesized titania.

Relations between Eastern four pillars theory and Western measures of personality traits.

Science.gov (United States)

Jung, Seung Ah; Yang, Chang Soon

2015-05-01

The present study investigated the validity of personality classification using four pillars theory, a tradition in China and northeastern Asia. Four pillars analyses were performed for 148 adults on the basis of their birth year, month, day, and hour. Participants completed two personality tests, the Korean version of Temperament and Character Inventory-Revised-Short Version (TCI) and the Korean Inventory of Interpersonal Problems; scores were correlated with four pillars classification elements. Mean difference tests (e.g., t-test, ANOVA) were compared with groups classified by four pillars index. There were no significant correlations between personality scale scores and total yin/yang number (i.e., the 8 heavenly or earthly stems), and no significant between-groups results for classifications by yin/yang day stem and the five elements. There were significant but weak (r=0.18-0.29) correlations between the five elements and personality scale scores. For the six gods and personality scales, there were significant but weak (r=0.18-0.25) correlations. Features predicted by four pillars theory were most consistent when participants were grouped according to the yin/yang of the day stem and dominance of yin/yang numbers in the eight heavenly or earthly stems. Although the major criteria of four pillars theory were not independently correlated with personality scale scores, correlations emerged when participants were grouped according to the composite yin/yang variable. Our results suggest the utility of four pillars theory (beyond fortune telling or astrology) for classifying personality traits and making behavioral predictions.

Relations between Eastern Four Pillars Theory and Western Measures of Personality Traits

Science.gov (United States)

Jung, Seung Ah

2015-01-01

Purpose The present study investigated the validity of personality classification using four pillars theory, a tradition in China and northeastern Asia. Materials and Methods Four pillars analyses were performed for 148 adults on the basis of their birth year, month, day, and hour. Participants completed two personality tests, the Korean version of Temperament and Character Inventory-Revised-Short Version (TCI) and the Korean Inventory of Interpersonal Problems; scores were correlated with four pillars classification elements. Mean difference tests (e.g., t-test, ANOVA) were compared with groups classified by four pillars index. Results There were no significant correlations between personality scale scores and total yin/yang number (i.e., the 8 heavenly or earthly stems), and no significant between-groups results for classifications by yin/yang day stem and the five elements. There were significant but weak (r=0.18-0.29) correlations between the five elements and personality scale scores. For the six gods and personality scales, there were significant but weak (r=0.18-0.25) correlations. Features predicted by four pillars theory were most consistent when participants were grouped according to the yin/yang of the day stem and dominance of yin/yang numbers in the eight heavenly or earthly stems. Conclusion Although the major criteria of four pillars theory were not independently correlated with personality scale scores, correlations emerged when participants were grouped according to the composite yin/yang variable. Our results suggest the utility of four pillars theory (beyond fortune telling or astrology) for classifying personality traits and making behavioral predictions. PMID:25837175

Hydraulic method of working large super-drift pillars

Energy Technology Data Exchange (ETDEWEB)

Rad' ko, B.V.; Syroezhkin, P.V.; Durov, V.S.

1987-03-01

Describes the method of hydraulic coal extraction introduced in the Pioneer mine belonging to the Dobropol'eugol' coal association. This method was found to reduce the number of collection and ventilation roadways needed significantly, increase their stability, reduce coal loss and increase safety, particularly when mining pillars up to 80 m high. Large scale diagram of hydraulic mining layout shows: ventilation gate, hydraulic monitors, mine roadway, cross-cut, and collection roadways. A table shows pillar dimensions and depth and economic savings for different seams in the mine.

Wettability transition of plasma-treated polystyrene micro/nano pillars-aligned patterns

Directory of Open Access Journals (Sweden)

2010-12-01

Full Text Available This paper reports the wettability transition of plasma-treated polystyrene (PS micro/nano pillars-aligned patterns. The micro/nano pillars were prepared using hot embossing on silicon microporous template and alumina nanoporous template, which were fabricated by ultraviolet (UV lithography and inductive coupled plasma (ICP etching, and two-step anodic oxidation, respectively. The results indicate that the combination of micro/nano patterning and plasma irradiation can easily regulate wettabilities of PS surfaces, i.e. from hydrophilicity to hydrophobicity, or from hydrophobicity to superhydrophilicity. During the wettability transition from hydrophobicity to hydrophilicity there is only mild hydrophilicity loss. After plasma irradiation, moreover, the wettability of PS micro/nano pillars-aligned patterns is more stable than that of flat PS surfaces. The observed wettability transition and wettability stability of PS micro/nano pillars-aligned patterns are new phenomena, which may have potential in creating programmable functional polymer surfaces.

Synthesis and characterization of silica–titania core–shell particles

Indian Academy of Sciences (India)

reactants (titanium butoxide and water) and the amount of added silica particles. Differ- ... of titania onto silica can enhance its stability and catalytic activity. It is also an .... This work has been supported by DST India under the Nanomaterials,.

Develop guidelines for the design of pillar systems for shallow and intermediate depth, tabular, hard rock mines and provide a methodology for assessing hangingwall stability and support requirements for the panels between pillars

CSIR Research Space (South Africa)

York, G

1998-12-01

Full Text Available The design of hard rock pillars, in shallow to intermediate depth hard rock mines, has been redefined as the determination of the pillar system load bearing capacity. This entails the ability to design each of the components of the pillar system...

Adsorption of CO, CO2, H2, and H2O on titania surfaces with different oxidation states

International Nuclear Information System (INIS)

Raupp, G.B.; Dumesic, J.A.

1985-01-01

The adsorptive properties of titania surfaces with different oxidation states were proved by temperature-programmed desorption (TPD) of CO, H 2 , CO 2 , and H 2 O. Auger electron spectroscopy and X-ray photoelectron spectroscopy revealed that vacuum annealing an oxidized titanium foil at temperatures from 300 to 800 K was an effective means of systematically varying the average surface oxidation state from Ti 4+ to Ti 2+ . Carbon monoxide weakly adsorbed (desorption energy of 44-49 kJ x mol -1 ) in a carbonyl fashion on coordinatively unsaturated cation sites. Titania surfaces were inert with respect to H 2 adsorption and dissociation. Carbon dioxide adsorbed in a linear molecular fashion. Water adsorbed both molecularly and dissociatively. Results are discussed in terms of the role of titania oxidation state in CO hydrogenation over titania-supported metal catalysts. 74 references, 7 figures

Visible-Light Degradation of Dyes and Phenols over Mesoporous Titania Prepared by Using Anthocyanin from Red Radish as Template

Directory of Open Access Journals (Sweden)

Zhiying Yan

2014-01-01

Full Text Available Heterogeneous photocatalysis is able to operate effectively to eliminate organic compounds from wastewater in the presence of semiconductor photocatalyst and a light source. Although photosensitization of titania by organic dyes is one of the conventional ways for visible-light utilization of titania, previous studies have not yet addressed the use of natural food coloring agents as templates in the synthesis of mesostructured materials, let alone the simultaneous achievement of highly crystalline mesoscopic framework and visible-light photocatalytic activity. In this work, anthocyanin, a natural pigment from red radish was directly used as template in synthesis of highly crystalline mesoporous titania. The synthesized mesoporous titania samples were characterized by a combination of various physicochemical techniques, such as XRD, SEM, HRTEM, nitrogen adsorption/desorption, and diffuse reflectance UV-Vis. The prepared mesoporous titania photocatalyst exhibited significant activity under visible-light irradiation for the degradation of dyes and phenols due to its red shift of band-gap-absorption onset and visible-light response as a result of the incorporation of surface carbon species.

Design and construction of porous metal-organic frameworks based on flexible BPH pillars

Energy Technology Data Exchange (ETDEWEB)

Hao, Xiang-Rong; Yang, Guang-sheng; Shao, Kui-Zhan [Institute of Functional Material Chemistry, Faculty of Chemistry, Northeast Normal University, Changchun 130024, Jilin (China); Su, Zhong-Min, E-mail: zmsu@nenu.edu.cn [Institute of Functional Material Chemistry, Faculty of Chemistry, Northeast Normal University, Changchun 130024, Jilin (China); Yuan, Gang; Wang, Xin-Long [Institute of Functional Material Chemistry, Faculty of Chemistry, Northeast Normal University, Changchun 130024, Jilin (China)

2013-02-15

Three metal-organic frameworks (MOFs), [Co{sub 2}(BPDC){sub 2}(4-BPH){center_dot}3DMF]{sub n} (1), [Cd{sub 2}(BPDC){sub 2}(4-BPH){sub 2}{center_dot}2DMF]{sub n} (2) and [Ni{sub 2}(BDC){sub 2}(3-BPH){sub 2} (H{sub 2}O){center_dot}4DMF]{sub n} (3) (H{sub 2}BPDC=biphenyl-4,4 Prime -dicarboxylic acid, H{sub 2}BDC=terephthalic acid, BPH=bis(pyridinylethylidene)hydrazine and DMF=N,N Prime -dimethylformamide), have been solvothermally synthesized based on the insertion of heterogeneous BPH pillars. Framework 1 has 'single-pillared' MOF-5-like motif with inner cage diameters of up to 18.6 A. Framework 2 has 'double pillared' MOF-5-like motif with cage diameters of 19.2 A while 3 has 'double pillared' 8-connected framework with channel diameters of 11.0 A. Powder X-ray diffraction (PXRD) shows that 3 is a dynamic porous framework. - Graphical abstract: By insertion of flexible BPH pillars based on 'pillaring' strategy, three metal-organic frameworks are obtained showing that the porous frameworks can be constructed in a much greater variety. Highlights: Black-Right-Pointing-Pointer Frameworks 1 and 2 have MOF-5 like motif. Black-Right-Pointing-Pointer The cube-like cages in 1 and 2 are quite large, comparable to the IRMOF-10. Black-Right-Pointing-Pointer Framework 1 is 'single-pillared' mode while 2 is 'double-pillared' mode. Black-Right-Pointing-Pointer PXRD and gas adsorption analysis show that 3 is a dynamic porous framework.

Clay Play

Science.gov (United States)

Rogers, Liz; Steffan, Dana

2009-01-01

This article describes how to use clay as a potential material for young children to explore. As teachers, the authors find that their dialogue about the potential of clay as a learning medium raises many questions: (1) What makes clay so enticing? (2) Why are teachers noticing different play and conversation around the clay table as compared to…

Multistack integration of three-dimensional hyperbranched anatase titania architectures for high-efficiency dye-sensitized solar cells.

Science.gov (United States)

Wu, Wu-Qiang; Xu, Yang-Fan; Rao, Hua-Shang; Su, Cheng-Yong; Kuang, Dai-Bin

2014-04-30

An unprecedented attempt was conducted on suitably functionalized integration of three-dimensional hyperbranched titania architectures for efficient multistack photoanode, constructed via layer-by-layer assembly of hyperbranched hierarchical tree-like titania nanowires (underlayer), branched hierarchical rambutan-like titania hollow submicrometer-sized spheres (intermediate layer), and hyperbranched hierarchical urchin-like titania micrometer-sized spheres (top layer). Owing to favorable charge-collection, superior light harvesting efficiency and extended electron lifetime, the multilayered TiO2-based devices showed greater J(sc) and V(oc) than those of a conventional TiO2 nanoparticle (TNP), and an overall power conversion efficiency of 11.01% (J(sc) = 18.53 mA cm(-2); V(oc) = 827 mV and FF = 0.72) was attained, which remarkably outperformed that of a TNP-based reference cell (η = 7.62%) with a similar film thickness. Meanwhile, the facile and operable film-fabricating technique (hydrothermal and drop-casting) provides a promising scheme and great simplicity for high performance/cost ratio photovoltaic device processability in a sustainable way.

The role of nanocrystalline titania coating on nanostructured austenitic stainless steel in enhancing osteoblasts functions for regeneration of tissue

Energy Technology Data Exchange (ETDEWEB)

Shah, J.S.; Venkatsurya, P.K.C.; Thein-Han, W.W. [Biomaterials and Biomedical Engineering Research Laboratory, Center for Structural and Functional Materials, University of Louisiana at Lafayette, P.O. Box 44130, Lafayette, LA 70504 (United States); Misra, R.D.K., E-mail: dmisra@louisiana.edu [Biomaterials and Biomedical Engineering Research Laboratory, Center for Structural and Functional Materials, University of Louisiana at Lafayette, P.O. Box 44130, Lafayette, LA 70504 (United States); Pesacreta, T.C. [Department of Biology, University of Louisiana at Lafayette, P.O. Box 42451, Lafayette, LA 70504 (United States); Somani, M.C.; Karjalainen, L.P. [Department of Mechanical Engineering, University of Oulu, P.O. Box 4200, 90014 Oulu (Finland)

2011-03-12

In the context of osseointegration of metallic implants, while nanostructuring the surface favorably modulates cellular response, the disinfective attributes required during the healing process are not available. Thus, in the present study, we demonstrate that nanocrystalline titania provides cumulative benefit of enhancing osteoblasts functions to promote the efficacy of metal implants together with the disinfective attributes. To this end, the primary objective here is to examine the select functions of bone forming cells (osteoblasts) on electrocrystallized nanonodular titania-coated nanograined/ultrafine grained (NG/UFG) austenitic stainless steel. The accompanying objective is to study the disinfective/antimicrobial activity. To the best of our understanding this is the first study of nanophase titania on a non-titanium substrate. The osteoblasts functions were investigated in terms of cell attachment, proliferation, and quantitative analysis of proteins, actin and vinculin. In comparison to the bare NG/UFG substrate, the nanophase titania-coated substrate exhibited higher degree of cell attachment and proliferation which are regulated via cellular and molecular interactions with proteins, actin and vinculin. The enhanced functions of osteoblasts suggest that nanophase titania adsorbs extracellular matrix proteins, fibronectin and vitronectin from serum enhancing protein, with subsequent binding of integrins and osteoblasts precursor to titania. The antimicrobial attributes assessed in terms of degradation of methyl orange and effectiveness in killing E. coli supports the viewpoint that large surface area of titania would be instrumental in reducing the detrimental effect of biologically reactive oxygen species produced by macrophages in the vicinity of the metal bone/implant interface. In summary, the study provides some new insights concerning nanostructuring of metallic substrates with specific physical and surface properties for medical devices with

Photocatalytic inactivation of hospital-associated bacteria using titania nanoparticle coated textiles

International Nuclear Information System (INIS)

Tahir, T.; Qazi, I.A.; Hashmi, I.; Baig, M.A.

2017-01-01

Modification in hospital textiles to include disinfection properties may help in the reduction of nosocomial infections. In this study, antibacterial properties were imparted to cotton fabric by modifying it with pure and (1%) silver doped titania nanoparticles. The nanoparticles were prepared by liquid impregnation process and characterized using X-ray Diffraction (XRD) spectroscopy, Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS). These nanoparticles were attached to cotton fabric using a cross linking agent succinic acid. Samples were washed at three different temperatures (30, 60 and 90 degree C), with and without detergent and for different number of cycles to test the durability of nanoparticles to the fabric. Scanning Electron Microscopy (SEM) was used for studying surface topography of fabric. Energy Dispersive X-ray fluorescence (ED-XRF) spectrometer was used to detect the titanium present on the fabric. Catalytic spectrophotometry using UV/visible spectrophotometer was used to determine titania concentration in washing effluent. The antibacterial activity of the modified fabric was examined against Methicillin Resistant Staphylococcus aureus (MRSA) under UV and fluorescent light. The maximum durability of titania nanoparticles to the fabric was retained after washing without detergent at 30 degree C. The overall results of durability testing showed that coating of nanoparticles on fabric was durable against washing at various conditions, hence suitable from an environmental perspective. Antibacterial testing showed 100% photocatalytic inactivation of MRSA after 4 and 24 h of UV and fluorescent light exposure respectively. The potential of using such textiles in hospital environment was validated through the use of modified bed linen in a local hospital for a period of three days consecutively. The viable count indicated the reduced bacterial contamination on nano-coated fabric as compared to uncoated fabric. Bed linen, curtains

Ball clay

Science.gov (United States)

Virta, R.L.

2001-01-01

Part of the 2000 annual review of the industrial minerals sector. A general overview of the ball clay industry is provided. In 2000, sales of ball clay reached record levels, with sanitary ware and tile applications accounting for the largest sales. Ball clay production, consumption, prices, foreign trade, and industry news are summarized. The outlook for the ball clay industry is also outlined.

Influence of clay mineralogy on clay based ceramic products

International Nuclear Information System (INIS)

Radzali Othman; Tuan Besar Tuan Sarif; Zainal Arifin Ahmad; Ahmad Fauzi Mohd Noor; Abu Bakar Aramjat

1996-01-01

Clay-based ceramic products can either be produced directly from a suitable clay source without the need further addition or such products can be produced from a ceramic body formulated by additions of other raw materials such as feldspar and silica sand. In either case, the mineralogical make-up of the clay component plays a dominating role in the fabrication and properties of the ceramic product. This study was sparked off by a peculiar result observed in one of five local ball clay samples that were used to reformulate a ceramic body. Initial characterisation tests conducted on the clays indicated that these clays can be classified as kaolinitic. However, one of these clays produced a ceramic body that is distinctively different in terms of whiteness, smoothness and density as compared to the other four clays. Careful re-examination of other characterisation data, such as particle size distribution and chemical analysis, failed to offer any plausible explanation. Consequently, the mineralogical analysis by x-ray diffraction was repeated by paying meticulous attention to specimen preparation. Diffraction data for the clay with anomalous behaviour indicated the presence of a ∼ 10A peak that diminished when the same specimen was re-tested after heating in an oven at 12O degree C whilst the other four clays only exhibit the characteristic kaolinite (Al sub 2 O sub 3. 2SiO sub 2. 2H sub 2 0) and muscovite peaks at ∼ 7A and ∼ 10A before and after heat treatment. This suggests the presence of the mineral halloysite (A1 sub 2 0 sub 3. 2SiO sub 2.4H sub 2 0) in that particular clay. This difference in mineralogy can be attributed to account for the variations in physical properties of the final product. Consequently, this paper reviews in general the precautionary measures that must be adhered to during any mineralogical investigation of clay minerals or clay-based materials. The common pitfalls during specimen preparation, machine settings and interpretation of

An iron-57 Moessbauer spectroscopic study of titania-supported iron- and iron-iridium catalysts

International Nuclear Information System (INIS)

Berry, F.J.; Jobson, S.

1992-01-01

57 Fe Moessbauer spectroscopy shows that titania-supported iron is reduced by treatment in hydrogen at significantly lower temperatures than corresponding silica- and alumina-supported catalysts. The metallic iron formed under hydrogen at 600deg C is partially converted to carbide by treatment in carbon monoxide and hydrogen. In contrast to its alumina- and silica-supported counterparts, the remainder of the titania-supported iron is unchanged by this gaseous mixture. The 57 Fe Moessbauer spectra of EXAFS show that iron and iridium in the titania-supported iron-iridium catalysts are reduced in hydrogen at even lower temperatures and, after treatment at 600deg C, are predominantly present as the iron-iridium alloy. The treatment of these reduced catalysts in carbon monoxide and hydrogen is shown by Moessbauer spectroscopy and EXAFS to induce the segregation of iron from the iron-iridium alloy and its conversion to iron oxide. (orig.)

Characterization of sodium phenytoin co-gelled with titania for a controlled drug-release system

International Nuclear Information System (INIS)

Lopez, T.; Quintana, P.; Ortiz-Islas, E.; Vinogradova, E.; Manjarrez, J.; Aguilar, D.H.; Castillo-Ocampo, P.; Magana, C.; Azamar, J.A.

2007-01-01

Sodium phenytoin, C 15 H 11 N 2 NaO 2 , in several concentrations was co-gelled with titania (TiO 2 ), by a sol-gel process. This technique is a promising method to encapsulate several drugs, in this case, phenytoin is an anticonvulsant used to control epileptic seizures. Samples were prepared by adding different concentrations (X = 50, 100, 200 and 250 mg per 20 g of titania matrix) of sodium phenytoin (Ph) to a solution of titanium n-butoxide. The resulting titania-Ph-X materials were characterized by transmission electron microscopy (TEM), Fourier transformed infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), and Brunauer-Emmet-Teller (BET) surface areas. The porous nanomaterials showed a wide range of particle size, from 10 to 210 nm, with a mean pore diameter of 5 nm. X-ray diffraction showed an amorphous structure of the prepared samples

Evolution and Engineering of Precisely Controlled Ge Nanostructures on Scalable Array of Ordered Si Nano-pillars

Science.gov (United States)

Wang, Shuguang; Zhou, Tong; Li, Dehui; Zhong, Zhenyang

2016-06-01

The scalable array of ordered nano-pillars with precisely controllable quantum nanostructures (QNs) are ideal candidates for the exploration of the fundamental features of cavity quantum electrodynamics. It also has a great potential in the applications of innovative nano-optoelectronic devices for the future quantum communication and integrated photon circuits. Here, we present a synthesis of such hybrid system in combination of the nanosphere lithography and the self-assembly during heteroepitaxy. The precise positioning and controllable evolution of self-assembled Ge QNs, including quantum dot necklace(QDN), QD molecule(QDM) and quantum ring(QR), on Si nano-pillars are readily achieved. Considering the strain relaxation and the non-uniform Ge growth due to the thickness-dependent and anisotropic surface diffusion of adatoms on the pillars, the comprehensive scenario of the Ge growth on Si pillars is discovered. It clarifies the inherent mechanism underlying the controllable growth of the QNs on the pillar. Moreover, it inspires a deliberate two-step growth procedure to engineer the controllable QNs on the pillar. Our results pave a promising avenue to the achievement of desired nano-pillar-QNs system that facilitates the strong light-matter interaction due to both spectra and spatial coupling between the QNs and the cavity modes of a single pillar and the periodic pillars.

Cu Pillar Low Temperature Bonding and Interconnection Technology of for 3D RF Microsystem

Science.gov (United States)

Shi, G. X.; Qian, K. Q.; Huang, M.; Yu, Y. W.; Zhu, J.

2018-03-01

In this paper 3D interconnects technologies used Cu pillars are discussed with respect to RF microsystem. While 2.5D Si interposer and 3D packaging seem to rely to cu pillars for the coming years, RF microsystem used the heterogeneous chip such as GaAs integration with Si interposers should be at low temperature. The pillars were constituted by Cu (2 micron) -Ni (2 micron) -Cu (3 micron) -Sn (1 micron) multilayer metal and total height is 8 micron on the front-side of the wafer by using electroplating. The wafer backside Cu pillar is obtained by temporary bonding, thinning and silicon surface etching. The RF interposers are stacked by Cu-Sn eutectic bonding at 260 °C. Analyzed the reliability of different pillar bonding structure.

Controlled release of phenytoin for epilepsy treatment from titania and silica based materials

Energy Technology Data Exchange (ETDEWEB)

Lopez, Tessy, E-mail: tessy3@prodigy.net.mx [Universidad Autonoma Metropolitana-Xochimilco. Departamento de Microbiologia. Calzada del Hueso 1100, Col. Villa Quietud, Coyoacan, C.P. 04960, Mexico D.F. Mexico (Mexico); Instituto Nacional de Neurologia y Neurocirugia ' MVS' . Laboratorio de Nanotecnologia. Av. Insurgentes Sur 3877, Col. La Fama, Tlalpan, 14269, Mexico, D.F. Mexico (Mexico); Department of Chemical and Biomolecular Engineering, Tulane University, New Orleans, LA 70118 (United States); Ortiz, Emma [Instituto Nacional de Neurologia y Neurocirugia ' MVS' . Laboratorio de Nanotecnologia. Av. Insurgentes Sur 3877, Col. La Fama, Tlalpan, 14269, Mexico, D.F. Mexico (Mexico); Meza, Doraliz [Universidad Autonoma Metropolitana-Iztapalapa, Departamento de Quimica, Av. San Rafael Atlixco 186, A.P. 55-534, Mexico D.F., C.P. 09340 (Mexico); Basaldella, Elena [CIC-CINDECA - Universidad Nacional de La Plata - Calle 47 No 257 - La Plata (Argentina); Bokhimi, Xim; Magana, Carlos [Instituto de fisica, UNAM. Circuito de la Investigacion s/n. C.U. Mexico D.F. 01000 (Mexico); Sepulveda, Antonio; Rodriguez, Francisco; Ruiz, Javier [Departamento de Quimica Inorganica, Universidad de Alicante. Apartado 99, E-03080 Alicante, Espana Spain (Spain)

2011-04-15

Research highlights: {yields} Template technique was used to obtain well ordered nanostructured materials: SBA-15 and titania tubes. {yields} Phenytoin (PH), a drug used in epilepsy treatment, was loaded in these materials to used como PH release. {yields} Loaded PH showed a good stability inside the used materials as observed by spectroscopy analysis. {yields} The load-release PH are faster in nanostructured TiO2 tubes than in mesoporous silica matrix. {yields} There is an inverse effect of the surface area of the structured materials on the amount of released PH. - Abstract: Template technique was used to obtain well ordered nanostructured materials: mesoporous silica and nanostructured titania tubes. This technique permits the synthesis of solids with controlled mesoporosity, where a large variety of molecules that have therapeutic activity can be hosted and further released to specific sites. In this work phenytoin (PH), a drug used in epilepsy treatment, was loaded in ordered mesoporous silica (SBA 15) and nanostructured titania tubes (TiO{sub 2}). The pure materials and those containing PH were characterized by X-ray diffraction, FTIR spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and N{sub 2} adsorption-desorption at 77 K. In order to determine the loading capacity of the antiepileptic drug on these silica- and titania-based materials, the loading and release of PH was investigated using UV-vis spectroscopy. Tubular structures were found for the titania samples, for which the X-ray diffractograms showed to be formed by anatase and rutile phases. On the other hand, an amorphous phase was found in the silica sample. A highly ordered hexagonal structure of 1D cylindrical channels was also observed for this material. Loaded PH showed a good stability inside the used materials as observed by spectroscopy analysis. The adsorption and desorption of PH are faster in nanostructured TiO{sub 2} tubes than in mesoporous silica

On the determining role of network structure titania in silicone against bacterial colonization: Mechanism and disruption of biofilm

International Nuclear Information System (INIS)

Depan, D.; Misra, R.D.K.

2014-01-01

Silicone-based biomedical devices are prone to microbial adhesion, which is the primary cause of concern in the functioning of the artificial device. Silicone exhibiting long-term and effective antibacterial ability is highly desirable to prevent implant related infections. In this regard, nanophase titania was incorporated in silicone as an integral part of the silicone network structure through cross-link mechanism, with the objective to reduce bacterial adhesion to a minimum. The bacterial adhesion was studied using crystal violet assay, while the mechanism of inhibition of biofilm formation was studied via electron microscopy. The incorporation of nanophase titania in silicone dramatically reduced the viability of Staphylococcus aureus (S. aureus) and the capability to adhere on the surface of hybrid silicone by ∼ 93% in relation to stand alone silicone. The conclusion of dramatic reduction in the viability of S. aureus is corroborated by different experimental approaches including biofilm inhibition assay, zone of inhibition, and through a novel experiment that involved incubation of biofilm with titania nanoparticles. It is proposed that the mechanism of disruption of bacterial film in the presence of titania involves puncturing of the bacterial cell membrane. - Highlights: • Network structure titania in silicone imparts antimicrobial activity. • Ability to microbial adhesion is significantly reduced. • Antimicrobial mechanism involves rupture of biofilm

Deep proton writing of high aspect ratio SU-8 micro-pillars on glass

Energy Technology Data Exchange (ETDEWEB)

Ebraert, Evert, E-mail: eebraert@b-phot.org; Rwamucyo, Ben; Thienpont, Hugo; Van Erps, Jürgen

2016-12-15

Deep proton writing (DPW) is a fabrication technology developed for the rapid prototyping of polymer micro-structures. We use SU-8, a negative resist, spincoated in a layer up to 720 μm-thick in a single step on borosilicate glass, for irradiation with a collimated 12 MeV energy proton beam. Micro-pillars with a slightly conical profile are irradiated in the SU-8 layer. We determine the optimal proton fluence to be 1.02 × 10{sup 4} μm{sup −2}, with which we are able to repeatably achieve micro-pillars with a top-diameter of 138 ± 1 μm and a bottom-diameter of 151 ± 3 μm. The smallest fabricated pillars have a top-diameter of 57 ± 5 μm. We achieved a root-mean-square sidewall surface roughness between 19 nm and 35 nm for the fabricated micro-pillars, measured over an area of 5 × 63.7 μm. We briefly discuss initial testing of two potential applications of the fabricated micro-pillars. Using ∼100 μm-diameter pillars as waveguides for gigascale integration optical interconnect applications, has shown a 4.7 dB improvement in optical multimode fiber-to-fiber coupling as compared to the case where an air–gap is present between the fibers at the telecom wavelength of 1550 nm. The ∼140 μm-diameter pillars were used for mold fabrication with silicone casting. The resulting mold can be used for hydrogel casting, to obtain hydrogel replicas mimicking human tissue for in vitro bio-chemical applications.

Study on the optimum design of bus window pillar join40t; Bus window pillar ketsugo buzai no saiteki sekkei ni kansuru kenkyu

Energy Technology Data Exchange (ETDEWEB)

Tomioka, N [Nihon University, Tokyo (Japan); Lim, S; Kim, M; Lee, H; Kang, S; Bae, D

1997-10-01

Automobile body structure is generally assembled using various spot welded box sectional members. Especially, in the case of the bus, the shape of window pillar joint is assembled m T-type. This T-type member has some problem such as high stress concentration, low fatigue strength and structural rigidity. Therefore, in this report, performed a study on the optimum design of the bus window pillar joint for such problem by FEM analysis and experiments. 1 ref., 10 figs., 2 tabs.

Determine the need to research the time-related stability decay of bord and pillar systems

CSIR Research Space (South Africa)

Oberholzer, JW

1997-07-01

Full Text Available in decisions regarding research work that could be conducted to investigate the time related decay of bord and pillar workings. As the working consist of pillars of varying shapes and sizes the study concentrated mainly on the aspects of pillar decay...

Numerical Approach for Goaf-Side Entry Layout and Yield Pillar Design in Fractured Ground Conditions

Science.gov (United States)

Jiang, Lishuai; Zhang, Peipeng; Chen, Lianjun; Hao, Zhen; Sainoki, Atsushi; Mitri, Hani S.; Wang, Qingbiao

2017-11-01

Entry driven along goaf-side (EDG), which is the development of an entry of the next longwall panel along the goaf-side and the isolation of the entry from the goaf with a small-width yield pillar, has been widely employed in China over the past several decades . The width of such a yield pillar has a crucial effect on EDG layout in terms of the ground control, isolation effect and resource recovery rate. Based on a case study, this paper presents an approach for evaluating, designing and optimizing EDG and yield pillar by considering the results from numerical simulations and field practice. To rigorously analyze the ground stability, the numerical study begins with the simulation of goaf-side stress and ground conditions. Four global models with identical conditions, except for the width of the yield pillar, are built, and the effect of pillar width on ground stability is investigated by comparing aspects of stress distribution, failure propagation, and displacement evolution during the entire service life of the entry. Based on simulation results, the isolation effect of the pillar acquired from field practice is also considered. The suggested optimal yield pillar design is validated using a field test in the same mine. Thus, the presented numerical approach provides references and can be utilized for the evaluation, design and optimization of EDG and yield pillars under similar geological and geotechnical circumstances.

Numerical modeling for longwall pillar design: a case study from a typical longwall panel in China

Science.gov (United States)

Zhang, Guangchao; Liang, Saijiang; Tan, Yunliang; Xie, Fuxing; Chen, Shaojie; Jia, Hongguo

2018-02-01

This paper presents a new numerical modeling procedure and design principle for longwall pillar design with the assistance of numerical simulation of FLAC3D. A coal mine located in Yanzhou city, Shandong Province, China, was selected for this case study. A meticulously validated numerical model was developed to investigate the stress changes across the longwall pillar with various sizes. In order to improve the reliability of the numerical modeling, a calibration procedure is undertaken to match the Salamon and Munro pillar strength formula for the coal pillar, while a similar calibration procedure is used to estimate the stress-strain response of a gob. The model results demonstrated that when the coal pillar width was 7-8 m, most of the vertical load was carried by the panel rib, whilst the gateroad was overall in a relatively low stress environment and could keep its stability with proper supports. Thus, the rational longwall pillar width was set as 8 m and the field monitoring results confirmed the feasibility of this pillar size. The proposed numerical simulation procedure and design principle presented in this study could be a viable alternative approach for longwall pillar design for other similar projects.

Mechanism of the Topotactic Formation of gamma-Zirconium Phosphate Covalently Pillared with Diphosphonate Groups.

Science.gov (United States)

Alberti, G.; Giontella, E.; Murcia-Mascarós, S.; Vivani, R.

1998-09-07

The topotactic reaction of gamma-ZrPO(4)[O(2)P(OH)(2)].2H(2)O (gamma-ZrP) with benzenediphosphonic acid was examined in water and in acetone-water mixtures. This reaction was found to take place in water only on the external surface of the microcrystals, and pillared compounds were never obtained, even after very long reaction times. On the contrary, covalently pillared compounds were quickly obtained in acetone-water mixtures. The mechanism of the latter topotactic reaction was investigated by determining the rate of the phosphate groups released and the rate of the benzenediphosphonates taken up by gamma-ZrP over a long time (50 days). These data showed that pillared derivatives of gamma-ZrP can be obtained because colloidal dispersions of exfoliated lamellae are formed in acetone-water mixtures. The diphosphonate group acts initially as a monovalent species, replacing only one dihydrogen phosphate group on the surface of the exfoliated gamma-lamellae. The colloidal and partially derivatized lamellae thus formed can interact with each other by forming polylamellar pillared systems. When the number of pillared lamellae exceeds a given value (usually 5-6), flocculation of the colloidal gamma-ZrP takes place. Topotactic reactions between packets of pillared lamellae may also continue in the flocculated system. Therefore, the average number of the pillared lamellae slowly increases over time.

Dispersed-nanoparticle loading synthesis for monodisperse Au-titania composite particles and their crystallization for highly active UV and visible photocatalysts.

Science.gov (United States)

Sakamoto, Takeshi; Nagao, Daisuke; Noba, Masahiro; Ishii, Haruyuki; Konno, Mikio

2014-06-24

Submicrometer-sized amorphous titania spheres incorporating Au nanoparticles (NPs) were prepared in a one-pot synthesis consisting of a sol-gel reaction of titanium(IV) isopropoxide in the presence of chloroauric acid and a successive reduction with sodium borohydride in a mixed solvent of ethanol/acetonitrile. The synthesis was allowed to prepare monodisperse titania spheres that homogeneously incorporated Au NPs with sizes of ca. 7 nm. The Au NP-loaded titania spheres underwent different crystallization processes, including 500 °C calcination in air, high-temperature hydrothermal treatment (HHT), and/or low-temperature hydrothermal treatment (LHT). Photocatalytic experiments were conducted with the Au NP-loaded crystalline titania spheres under irradiation of UV and visible light. A combined process of LHT at 80 °C followed by calcination at 500 °C could effectively crystallize titania spheres maintaining the dispersion state of Au NPs, which led to photocatalytic activity higher than that of commercial P25 under UV irradiation. Under visible light irradiation, the Au NP-titania spheres prepared with a crystallization process of LHT at 80 °C for 6 h showed photocatalytic activity much higher than a commercial product of visible light photocatalyst. Structure analysis of the visible light photocatalysts indicates the importance of prevention of the Au NPs aggregation in the crystallization processes for enhancement of photocatalytic activity.

Aespoe Pillar Stability Experiment. Final 2D coupled thermo-mechanical modelling

Energy Technology Data Exchange (ETDEWEB)

Fredriksson, Anders; Staub, Isabelle; Outters, Nils [Golder Associates AB, Uppsala (Sweden)

2004-02-01

A site scale Pillar Stability Experiment is planned in the Aespoe Hard Rock Laboratory. One of the experiment's aims is to demonstrate the possibilities of predicting spalling in the fractured rock mass. In order to investigate the probability and conditions for spalling in the pillar 'prior to experiment' numerical simulations have been undertaken. This report presents the results obtained from 2D coupled thermo-mechanical numerical simulations that have been done with the Finite Element based programme JobFem. The 2D numerical simulations were conducted at two different depth levels, 0.5 and 1.5 m below tunnel floor. The in situ stresses have been confirmed with convergence measurements during the excavation of the tunnel. After updating the mechanical and thermal properties of the rock mass the final simulations have been undertaken. According to the modelling results the temperature in the pillar will increase from the initial 15.2 deg up to 58 deg after 120 days of heating. Based on these numerical simulations and on the thermal induced stresses the total stresses are expected to exceed 210 MPa at the border of the pillar for the level at 0.5 m below tunnel floor and might reach 180-182 MPa for the level at 1.5 m below tunnel floor. The stresses are slightly higher at the border of the confined hole. Upon these results and according to the rock mechanical properties the Crack Initiation Stress is exceeded at the border of the pillar already after the excavation phase. These results also illustrate that the Crack Damage Stress is exceeded only for the level at 0.5 m below tunnel floor and after at least 80 days of heating. The interpretation of the results shows that the required level of stress for spalling can be reached in the pillar.

Development of a method to estimate coal pillar loading

CSIR Research Space (South Africa)

Roberts, DP

2002-09-01

Full Text Available to the panel width to depth ratio, the percentage extraction and the stiffness of the surrounding strata influence the validity of the tributary area method. An underground test was conducted to assess the magnitude of changes in pillar stress. Various... stress measurement devices were installed in test pillars just prior to mining. The stress changes were monitored and compared with numerical modelling results. It was found that stresses increased by between 0.3 MPa and 0.5 MPa and that the stresses...

USHPRR FUEL FABRICATION PILLAR: FABRICATION STATUS, PROCESS OPTIMIZATIONS, AND FUTURE PLANS

Energy Technology Data Exchange (ETDEWEB)

Wight, Jared M.; Joshi, Vineet V.; Lavender, Curt A.

2018-03-12

The Fuel Fabrication (FF) Pillar, a project within the U.S. High Performance Research Reactor Conversion program of the National Nuclear Security Administration’s Office of Material Management and Minimization, is tasked with the scale-up and commercialization of high-density monolithic U-Mo fuel for the conversion of appropriate research reactors to use of low-enriched fuel. The FF Pillar has made significant steps to demonstrate and optimize the baseline co-rolling process using commercial-scale equipment at both the Y-12 National Security Complex (Y-12) and BWX Technologies (BWXT). These demonstrations include the fabrication of the next irradiation experiment, Mini-Plate 1 (MP-1), and casting optimizations at Y-12. The FF Pillar uses a detailed process flow diagram to identify potential gaps in processing knowledge or demonstration, which helps direct the strategic research agenda of the FF Pillar. This paper describes the significant progress made toward understanding the fuel characteristics, and models developed to make informed decisions, increase process yield, and decrease lifecycle waste and costs.

Optimizing sol-gel infiltration for the fabrication of high-quality titania inverse opal and its photocatalytic activity

International Nuclear Information System (INIS)

Liu Weijie; Zou Bo; Zhao Jing; Cui Haining

2010-01-01

This article reports an optimized sol-gel opal infiltration technique for the fabrication of high-quality titania inverse opal. Different from previous reports, the presently proposed method is facile, efficient and suitable for other inorganic oxide. We have compared two different infiltration strategies and their influences on the structure, photonic properties and photocatalytic activity. The obtained titania inverse opal displays excellent photonic properties with photonic band gap at 320 nm and better photocatalytic effect, which is attributed to its high-quality inverse opal nanostructure. Reproducibility tests prove that the photocatalytic activity of the resultant titania inverse opal remains intact even after five repeated photocatalytic reactions under the same procedure and experimental conditions.

Impedance response of carbon nanotube-titania electrodes dried under modified gravity

International Nuclear Information System (INIS)

Ordenana-Martinez, A.S.; Rincon, M.E.; Vargas, M.; Ramos, E.

2011-01-01

The synthesis and impregnation of porous titania films by commercial multiwalled carbon nanotubes and nanotube rich carbon soot are reported. The samples were dried under terrestrial gravity g and in a centrifuge accelerated at 13 g. X-Ray Diffraction data and Scanning Electron Microscopy images indicated differences in the crystal structure and tendency to agglomeration in both carbon types, providing different microstructures of functionally graded electrodes. Drying the samples in a centrifuge helps to the distribution of carbon nanoparticles and to the decrement of the impedance at the contact interfaces. The presence of titania weakens the differences observed in both drying protocols, but not the differences due to the carbon source. Superior capacitance and network conductivity were observed in electrodes based on commercial carbon nanotubes.

Development of a dielectric ceramic based on diatomite-titania. Part one: powder preparation and sintering study

Directory of Open Access Journals (Sweden)

Tavares Elcio Correia de Souza

1997-01-01

Full Text Available This work presents powder preparation and sintering experiments of a mixture diatomite-titania. X-ray diffraction, DTA, TGA as well as chemical and microstructural analyses were made. The sintering process was investigated as a function of sintering temperature and time, mass variation, linear shrinkage and activation energy. The results show that sintering of diatomite-titania could be described by a viscous flow mechanism.

Titania nanotubes with adjustable dimensions for drug reservoir sites and enhanced cell adhesion

Energy Technology Data Exchange (ETDEWEB)

Çalışkan, Nazlı; Bayram, Cem; Erdal, Ebru; Karahaliloğlu, Zeynep; Denkbaş, Emir Baki, E-mail: denkbas@hacettepe.edu.tr

2014-02-01

This study aims to generate a bactericidal agent releasing surface via nanotube layer on titanium metal and to investigate how aspect ratio of nanotubes affects drug elution time and cell proliferation. Titania nanotube layers were generated on metal surfaces by anodic oxidation at various voltage and time parameters. Gentamicin loading was carried out via simple pipetting and the samples were tested against S. aureus for the efficacy of the applied modification. Drug releasing time and cell proliferation were also tested in vitro. Titania nanotube layers with varying diameters and lengths were prepared after anodization and anodizing duration was found as the most effective parameter for amount of loaded drug and drug releasing time. Drug elution lasted up to 4 days after anodizing for 80 min of the samples, whereas release completed in 24 h when the samples were anodized for 20 min. All processed samples had bactericidal properties against S. aureus organism except unmodified titanium, which was also subjected to drug incorporation step. The anodization also enhanced water wettability and cell adhesion results. Anodic oxidation is an effective surface modification to enhance tissue–implant interactions and also resultant titania layer can act as a drug reservoir for the release of bactericidal agents. The use of implants as local drug eluting devices is promising but further in vivo testing is required. - Highlights: • Titanium surfaces were anodized and a nanotubular titania layer was obtained. • Drug eluting time was found to be increasing with anodizaton time. • Varying nanotube diameters has no effect in drug elution time but amount of incorporated drug.

Titania nanotubes with adjustable dimensions for drug reservoir sites and enhanced cell adhesion

International Nuclear Information System (INIS)

Çalışkan, Nazlı; Bayram, Cem; Erdal, Ebru; Karahaliloğlu, Zeynep; Denkbaş, Emir Baki

2014-01-01

This study aims to generate a bactericidal agent releasing surface via nanotube layer on titanium metal and to investigate how aspect ratio of nanotubes affects drug elution time and cell proliferation. Titania nanotube layers were generated on metal surfaces by anodic oxidation at various voltage and time parameters. Gentamicin loading was carried out via simple pipetting and the samples were tested against S. aureus for the efficacy of the applied modification. Drug releasing time and cell proliferation were also tested in vitro. Titania nanotube layers with varying diameters and lengths were prepared after anodization and anodizing duration was found as the most effective parameter for amount of loaded drug and drug releasing time. Drug elution lasted up to 4 days after anodizing for 80 min of the samples, whereas release completed in 24 h when the samples were anodized for 20 min. All processed samples had bactericidal properties against S. aureus organism except unmodified titanium, which was also subjected to drug incorporation step. The anodization also enhanced water wettability and cell adhesion results. Anodic oxidation is an effective surface modification to enhance tissue–implant interactions and also resultant titania layer can act as a drug reservoir for the release of bactericidal agents. The use of implants as local drug eluting devices is promising but further in vivo testing is required. - Highlights: • Titanium surfaces were anodized and a nanotubular titania layer was obtained. • Drug eluting time was found to be increasing with anodizaton time. • Varying nanotube diameters has no effect in drug elution time but amount of incorporated drug

Supercapacitors based on pillared graphene nanostructures.

Science.gov (United States)

Lin, Jian; Zhong, Jiebin; Bao, Duoduo; Reiber-Kyle, Jennifer; Wang, Wei; Vullev, Valentine; Ozkan, Mihrimah; Ozkan, Cengiz S

2012-03-01

We describe the fabrication of highly conductive and large-area three dimensional pillared graphene nanostructure (PGN) films from assembly of vertically aligned CNT pillars on flexible copper foils for applications in electric double layer capacitors (EDLC). The PGN films synthesized via a one-step chemical vapor deposition process on flexible copper foils exhibit high conductivity with sheet resistance as low as 1.6 ohms per square and possessing high mechanical flexibility. Raman spectroscopy indicates the presence of multi walled carbon nanotubes (MWCNT) and their morphology can be controlled by the growth conditions. It was discovered that nitric acid treatment can significantly increase the specific capacitance of the devices. EDLC devices based on PGN electrodes (surface area of 565 m2/g) demonstrate enhanced performance with specific capacitance value as high as 330 F/g extracted from the current density-voltage (CV) measurements and energy density value of 45.8 Wh/kg. The hybrid graphene-CNT nanostructures are attractive for applications including supercapacitors, fuel cells and batteries.

Synthesis, characterizations and photocatalytic studies of mesoporous titania prepared by using four plant skins as templates

Energy Technology Data Exchange (ETDEWEB)

Miao Yingchun [Department of Applied Chemistry, Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education, Yunnan University, Kunming 650091 (China); Faculty of Chemical and Life Sciences, Qujing Normal University, Qujing 655000 (China); Zhai Zhongbiao [Department of Applied Chemistry, Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education, Yunnan University, Kunming 650091 (China); Kunming Metallurgy Research Institute, Kunming 650031 (China); He Jiao; Li Bin; Li Junjie [Department of Applied Chemistry, Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education, Yunnan University, Kunming 650091 (China); Wang Jiaqiang, E-mail: jqwang@ynu.edu.cn [Department of Applied Chemistry, Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education, Yunnan University, Kunming 650091 (China)

2010-07-20

Anatase mesoporous titania with novel morphologies were synthesized by using the skins of tomatoes, bulb onions, grapes, and garlic bulbs, respectively, as templates and used for the photodegradation of Gentian violet, methyl violet, xylenol orange, and Rhodamine B under UV light. The samples were characterized by a combination of various physicochemical techniques, such as X-ray diffraction, SEM, HRTEM, N{sub 2} adsorption/desorption, diffuse reflectance UV-Vis, and FT-IR. It was found that all of the synthesized mesoporous titania samples exhibited similar morphologies to those of the original templates. The photoactivity of P25 TiO{sub 2} for the four dyes is nearly the same while the mesoporous titania samples synthesized by using the four skins as templates exhibited varied photoactivities for the four dyes.

Width design for gobs and isolated coal pillars based on overall burst-instability prevention in coal mines

Directory of Open Access Journals (Sweden)

Junfei Zhang

2016-08-01

Full Text Available An investigation was conducted on the overall burst-instability of isolated coal pillars by means of the possibility index diagnosis method (PIDM. First, the abutment pressure calculation model of the gob in side direction was established to derive the abutment pressure distribution curve of the isolated coal pillar. Second, the overall burst-instability ratio of the isolated coal pillars was defined. Finally, the PIDM was utilized to judge the possibility of overall burst-instability and recoverability of isolated coal pillars. The results show that an overall burst-instability may occur due to a large gob width or a small pillar width. If the width of the isolated coal pillar is not large enough, the shallow coal seam will be damaged at first, and then the high abutment pressure will be transferred to the deep coal seam, which may cause an overall burst-instability accident. This approach can be adopted to design widths of gobs and isolated coal pillars and to evaluate whether an existing isolated coal pillar is recoverable in skip-mining mines.

Role of binder in the synthesis of titania membrane

Indian Academy of Sciences (India)

Unknown

Abstract. The synthesis of titania membrane through sol–gel route involves hydrolysis of alkoxide, peptization of hydrous oxide of titanium to obtain a sol, adjustment of the sol viscosity by including a binder and filtration of the viscous sol through a microporous support, gelation and sintering to desired temperature.

Effect of urea on the photoactivity of titania powder prepared by sol-gel method

International Nuclear Information System (INIS)

Cheng Ping; Deng Changsheng; Gu Mingyuan; Dai Xiaming

2008-01-01

The synthesis of nanocrystalline titania powders from the hydrolysis of Ti(OBu n ) 4 in the presence of urea was investigated. DRS results showed that a redshift occurred in the absorption edge of titania with increasing the content of urea. XRD results indicated that urea showed a retarding effect on the transformation of titania from anatase to rutile. Moreover, the addition of urea resulted in a higher Brunauer-Emmett-Teller (BET) surface area as well as a larger average pore size of TiO 2 nanoparticles. The average pore size of urea/TiO 2 gels calcined at 500 deg. C increased with the increase of urea content, while the specific surface area increased with the amount of urea to reach a maximum at 10% and then decreased with further increase of the amount of urea. The maximal specific surface area of 64.4 m 2 g -1 was obtained for 10% urea/TiO 2 gels calcined at 500 deg. C, which showed an average particle size of 15 nm and pore size distribution in the range of mesopores centered at 5.8 nm. The photocatalytic experiments exhibited that titania nanoparticles prepared in the presence of urea could effectively photodegrade methyl orange under visible light irradiation due to the redshift of the absorption edge. The maximum photoactivity was achieved when the content of urea was 10%, which was attributed to the higher specific surface area

Non-lithographic method of forming ordered arrays of silicon pillars and macropores

International Nuclear Information System (INIS)

Mills, David; Kolasinski, Kurt W

2005-01-01

Micrometre-scale Si pillars are formed by chemically enhanced laser ablation using nanosecond excimer laser irradiation of a Si single crystal in the presence of SF 6 . We demonstrate the importance of precursor holes in determining the positioning of the pillars and show that we can control the initiation of precursor holes by ruling a grating into the Si substrate prior to irradiation. A rule defines an edge from which the laser light diffracts. Near-field amplification of the laser intensity enhances the formation of the precursor holes and aligns them parallel to the rule. The pillars can be thinned and eventually removed by wet chemical etching in aqueous KOH, resulting first in ordered arrays of extremely high aspect ratio pillars (e.g. tens of micrometres in length, with ∼ 10 nm tips) and then macropores. The shape of the macropore is determined by crystallography and the anisotropy of the wet etchant

Guided in Situ Polymerization of MEH-PPV in Mesoporous Titania Photoanodes.

Science.gov (United States)

Minar, Norma K; Docampo, Pablo; Fattakhova-Rohlfing, Dina; Bein, Thomas

2015-05-20

Incorporation of conjugated polymers into porous metal oxide networks is a challenging task, which is being pursued via many different approaches. We have developed the guided in situ polymerization of poly(2-methoxy-5-(2'-ethylhexyloxy)-p-phenylenevinylene) (MEH-PPV) in porous titania films by means of surface functionalization. The controlled polymerization via the Gilch route was induced by an alkoxide base and by increasing the temperature. The selected and specially designed surface-functionalizing linker molecules mimic the monomer or its activated form, respectively. In this way, we drastically enhanced the amount of MEH-PPV incorporated into the porous titania phase compared to nonfunctionalized samples by a factor of 6. Additionally, photovoltaic measurements were performed. The devices show shunting or series resistance limitations, depending on the surface functionalization prior to in situ polymerization of MEH-PPV. We suggest that the reason for this behavior can be found in the orientation of the grown polymer chains with respect to the titania surface. Therefore, the geometry of the anchoring via the linker molecules is relevant for exploiting the full electronic potential of the conjugated polymer in the resulting hybrid composite. This observation will help to design future synthesis methods for new hybrid materials from conjugated polymers and n-type semiconductors to take full advantage of favorable electronic interactions between the two phases.

Simultaneous sorption of As, B, Cr, Mo and Se from coal fly ash leachates by Al(sup3+)-pillared bentonite clay: implication for the construction of activated geo-synthetic clay liner

CSIR Research Space (South Africa)

Masindi, Vhahangwele

2017-03-01

Full Text Available successfully removed oxyanion species from generated coal FA leachates. This study shows that Al(sup3+)-modified bentonite clay is an effective adsorbent for oxyanion species in coal FA leachates and could be applied as a reactive barrier in coal FA retention...

The effect of the deposition parameters on size, distribution and antimicrobial properties of photoinduced silver nanoparticles on titania coatings

Energy Technology Data Exchange (ETDEWEB)

Piwonski, Ireneusz, E-mail: irek@uni.lodz.pl [University of Lodz, Department of Technology and Chemistry of Materials, Pomorska 163, 90-236 Lodz (Poland); Kadziola, Kinga; Kisielewska, Aneta; Soliwoda, Katarzyna [University of Lodz, Department of Technology and Chemistry of Materials, Pomorska 163, 90-236 Lodz (Poland); Wolszczak, Marian [Technical University of Lodz, Institute of Applied Radiation Chemistry, Wroblewskiego 15, 93-590 Lodz (Poland); Lisowska, Katarzyna; Wronska, Natalia; Felczak, Aleksandra [University of Lodz, Department of Industrial Microbiology and Biotechnology, Pilarskiego 14/16, 90-231 Lodz (Poland)

2011-06-01

Controlled photodeposition of silver nanoparticles (AgNP) on titania coatings using two different sources of UV light is described. Titania (anatase) thin films were prepared by the sol-gel dip-coating method on silicon wafers. AgNPs were grown on the titania surface as a result of UV illumination of titania films immersed in aqueous solutions of silver nitrate. UV xenon lamp or excimer laser, both operating at the wavelength 351 {+-} 5 nm, was used as illumination sources. The AFM topography of AgNP/TiO{sub 2} nanocomposites revealed that silver nanoparticles could be synthesized by both sources of illumination, however the photocatalysis carried out by UV light from xenon lamp illumination leads to larger AgNP than those synthesized using the laser beam. It was found that the increasing concentration of silver ions in the initial solution increases the number of Ag nanoparticles on the titania surface, while longer time of irradiation results the growth of larger size nanoparticles. Antibacterial tests performed on TiO{sub 2} covered by Ag nanoparticles revealed that increasing density of nanoparticles enhances the inhibition of bacterial growth. It was also found that antibacterial activity drops by only 10-15% after 6 cycles compared to the initial use.

The effect of the deposition parameters on size, distribution and antimicrobial properties of photoinduced silver nanoparticles on titania coatings

International Nuclear Information System (INIS)

Piwonski, Ireneusz; Kadziola, Kinga; Kisielewska, Aneta; Soliwoda, Katarzyna; Wolszczak, Marian; Lisowska, Katarzyna; Wronska, Natalia; Felczak, Aleksandra

2011-01-01

Controlled photodeposition of silver nanoparticles (AgNP) on titania coatings using two different sources of UV light is described. Titania (anatase) thin films were prepared by the sol-gel dip-coating method on silicon wafers. AgNPs were grown on the titania surface as a result of UV illumination of titania films immersed in aqueous solutions of silver nitrate. UV xenon lamp or excimer laser, both operating at the wavelength 351 ± 5 nm, was used as illumination sources. The AFM topography of AgNP/TiO 2 nanocomposites revealed that silver nanoparticles could be synthesized by both sources of illumination, however the photocatalysis carried out by UV light from xenon lamp illumination leads to larger AgNP than those synthesized using the laser beam. It was found that the increasing concentration of silver ions in the initial solution increases the number of Ag nanoparticles on the titania surface, while longer time of irradiation results the growth of larger size nanoparticles. Antibacterial tests performed on TiO 2 covered by Ag nanoparticles revealed that increasing density of nanoparticles enhances the inhibition of bacterial growth. It was also found that antibacterial activity drops by only 10-15% after 6 cycles compared to the initial use.

UV-Irradiated Photocatalytic Degradation of Nitrobenzene by Titania Binding on Quartz Tube

Directory of Open Access Journals (Sweden)

Thou-Jen Whang

2012-01-01

Full Text Available A new method for UV-irradiated degradation of nitrobenzene by titania photocatalysts was proposed, titania nanoparticles were coated on a quartz tube through the introduction of tetraethyl orthosilicate into the matrix. The dependence of nitrobenzene photodegradation on pH, temperature, concentration, and air feeding was discussed, and the physical properties such as the activation energy, entropy, enthalpy, adsorption constant, and rate constant were acquired by conducting the reactions in a variety of experimental conditions. The optimum efficiency of the photodegradation with the nitrobenzene residue as low as 8.8% was achieved according to the experimental conditions indicated. The photodegradation pathways were also investigated through HPLC, GC/MS, ion chromatography (IC, and chemical oxygen demand (COD analyses.

Rock mechanics of crown pillars between cut-and-fill stopes at the Mount Isa mine

Energy Technology Data Exchange (ETDEWEB)

Lee, M. F.; Bridges, M. C.

1980-05-15

At both levels, the leading stopes experienced bad ground conditions due to high stresses in the stope's backs when the crown pillars were about 35 m high. At 9 level, cut-and-fill mining stopped and most of the crown pillars were extracted by a slot-and-massfire method. At 11 level, cut-and-fill mining continued. Shear displacement along bedding planes began within and around the crown pillars of the leading stopes at 11 level, and spread through other crown pillars and to the hangingwall of the stoping system. Destressing and good ground conditions occurred where shear occurred, with further concentrations of stress in other areas. Crown pillars are being extracted to leave minimal 1:2 height to width diaphragms under the stopes above. Ground behavior of the 11 level crown pillars was investigated by observation, stress measurement, regional surveying of displacement and finite element models. An explanation of the ground behavior has evolved from this work. Bedding planes with an estimated angle of sliding friction of 10/sup 0/ were the main factor determining the behavior of this area.

Landslides in the area of the Jastrzebie town protective pillar

Energy Technology Data Exchange (ETDEWEB)

Rybicki, S

1986-01-01

Analyzes 76 landslides in the area of the safety pillar of Jastrzebie in the Rybnik coal region. Of 76 landslides 60% fell on natural slopes with an angle of 25-50 degrees, 22% on natural slopes with a 5-25 degree angle, 10% on man-made cuts and 8% on embankments. About 78% of the landslides was associated with water bearing layers. Of the 76 landslides 32 were situated in the safety pillar and 44 close to the pillar. Thirty-three landslides were closely associated with underground mining: 30 landslides were caused by longwall mining (landslide position was related to working face position), a further 3 were associated with mining in general. Statistical data on landslides associated with underground coal mining are analyzed: landslide area, angle of slope inclination, height, landslide range, water conditions, types of soils, types of mining areas classified according to effects of mining damage. 8 refs.

Methods for polarized light emission from CdSe quantum dot based monolithic pillar microcavities

Energy Technology Data Exchange (ETDEWEB)

Seyfried, Moritz; Kalden, Joachim; Sebald, Kathrin; Gutowski, Juergen; Kruse, Carsten; Hommel, Detlef [Institute of Solid State Physics, University of Bremen (Germany)

2010-07-01

A lifting of the polarization degeneracy of the fundamental cavity mode in pillar microcavities (MCs) would allow for controlling the polarization state of the emitted photons. Therefore, monolithic VCSEL structures were grown by molecular beam epitaxy containing either one CdSe/ZnSSe quantum dot layer or three quantum well layers as active material. By using focused-ion-beam etching, MC pillars with different geometries were prepared out of the planar samples. Among these are circularly shaped pillar MCs with diameters in the range from 500 nm up to 4 {mu}m and quality factors of up to 7860, elliptically shaped MCs, and so-called photonic molecules consisting of circular pillar MCs which are connected by small bars. Polarization dependent photoluminescence investigations of the fundamental cavity mode reveal a lifting of the polarization degeneracy for all three types of MCs. The energy splitting of up to 0.42 meV in the circularly shaped pillar MCs is probably caused by anisotropic strain conditions within the sample and directly dependent on the pillar diameter, whereas the larger energy splitting of up to 0.72 meV for the photonic molecules or even 4.5 meV for the elliptically shaped MC is based on their asymmetric cross sections.

Nanoscale roughness and morphology affect the IsoElectric Point of titania surfaces.

Directory of Open Access Journals (Sweden)

Francesca Borghi

Full Text Available We report on the systematic investigation of the role of surface nanoscale roughness and morphology on the charging behaviour of nanostructured titania (TiO2 surfaces in aqueous solutions. IsoElectric Points (IEPs of surfaces have been characterized by direct measurement of the electrostatic double layer interactions between titania surfaces and the micrometer-sized spherical silica probe of an atomic force microscope in NaCl aqueous electrolyte. The use of a colloidal probe provides well-defined interaction geometry and allows effectively probing the overall effect of nanoscale morphology. By using supersonic cluster beam deposition to fabricate nanostructured titania films, we achieved a quantitative control over the surface morphological parameters. We performed a systematical exploration of the electrical double layer properties in different interaction regimes characterized by different ratios of characteristic nanometric lengths of the system: the surface rms roughness Rq, the correlation length ξ and the Debye length λD. We observed a remarkable reduction by several pH units of IEP on rough nanostructured surfaces, with respect to flat crystalline rutile TiO2. In order to explain the observed behavior of IEP, we consider the roughness-induced self-overlap of the electrical double layers as a potential source of deviation from the trend expected for flat surfaces.

Beyond DSM-5 and IQ Scores: Integrating the Four Pillars to Forensic Evaluations.

Science.gov (United States)

Delgado, Sergio V; Barzman, Drew H

2017-03-01

The current adult and child forensic psychiatrist is well trained, familiar, and comfortable with the use of the semi-structured Diagnostic and Statistical Manual of Mental Disorders, 5th Edition, APA 2013 (DSM-5) [In APA, 2003] interview style. The author's assertion is not that this method is invalid or unreliable; rather, that it can be complemented by integrating elements of the defendant's four pillar assessment. Assessing the four pillars expands on the information provided by a semi-structured DSM-5-style interview in psychiatry. The four pillars are the foundation of a person's personality; temperament, cognition (learning abilities or weaknesses), cognitive flexibility (theory of mind) and internal working models of attachment, within the backdrop of the family and of the social and cultural environment in which they have lived. The importance of the study of four pillars is based on the understanding that human behavior and psychopathology as a complex and multifaceted process that includes the level of social-emotional maturity and cognitive abilities (In Delgado et al. Contemporary Psychodynamic Psychotherapy for Children and Adolescents: Integrating Intersubjectivity and Neuroscience. Springer, Berlin, 2015). The four pillars are not new concepts, rather they had been studied by separate non-clinical disciplines, and had not been integrated to the clinical practice. As far as we know, it wasn't until Delgado et al. (Contemporary Psychodynamic Psychotherapy for Children and Adolescents: Integrating Intersubjectivity and Neuroscience. Springer, Berlin, 2015) incorporated the four pillars in a user-friendly manner to clinical practice.

Eco-Friendly Magnetic Iron Oxide Pillared Montmorillonite for Advanced Catalytic Degradation of Dichlorophenol

Science.gov (United States)

Eco-friendly pillared montmorillonites, in which the pillars consist of iron oxide are expected to have interesting and unusual magnetic properties that are applicable for environmental decontamination. Completely “green” and effective composite was synthesized using mild reactio...

Effect of titania on the characteristics of a Tin-Platinum catalyst

Energy Technology Data Exchange (ETDEWEB)

Morales-Gil, P., E-mail: moralesp@imp.mx; Nava, N. [Instituto Mexicano del Petróleo (Mexico); Baggio-Saitovitch, E. [Centro Brasileiro de Pesquisas Físicas (Brazil)

2015-06-15

Pt-Sn bimetallic catalysts dispersed on alumina are commonly used for reforming and dehydrogenation reactions. In this research work, Pt and Sn were supported on titania. The resulting interactions between the components in the prepared samples, before and after treatment with hydrogen, were studied by Mössbauer spectroscopy, X-ray diffraction and Rietveld refinement. The results show the presence of Pt and SnO{sub 2} after calcinations. After the reduction process, metallic Pt, PtSn, and Pt{sub 3}Sn alloys were identified. The Rietveld refinement analysis shows that some Ti{sup 4+} atoms were replaced by Sn{sup 4+} atoms in the titania structure. Finally, the Mössbauer spectroscopy and X-ray diffraction results indicate that metallic platinum and SnO{sub 2} are encapsulated by a TiOx layer.

Dynamic Diffraction Studies on the Crystallization, Phase Transformation, and Activation Energies in Anodized Titania Nanotubes

OpenAIRE

Hani Albetran; Victor Vega; Victor M. Prida; It-Meng Low

2018-01-01

The influence of calcination time on the phase transformation and crystallization kinetics of anodized titania nanotube arrays was studied using in-situ isothermal and non-isothermal synchrotron radiation diffraction from room temperature to 900 °C. Anatase first crystallized at 400 °C, while rutile crystallized at 550 °C. Isothermal heating of the anodized titania nanotubes by an increase in the calcination time at 400, 450, 500, 550, 600, and 650 °C resulted in a slight reduction in anatase...

Manipulating the optical properties of CdSe/ZnSSe quantum dot based monolithic pillar microcavities

Energy Technology Data Exchange (ETDEWEB)

Seyfried, Moritz; Kalden, Joachim; Lohmeyer, Henning; Sebald, Kathrin; Gutowski, Juergen [Semiconductor Optics, Institute of Solid state Physics, University of Bremen (Germany); Kruse, Carsten; Hommel, Detlef, E-mail: Seyfried@ifp.uni-bremen.d [Semiconductor Epitaxy, Institute of Solid state Physics, University of Bremen (Germany)

2010-02-01

A customization of the optical properties of pillar microcavities on the desired applications is essential for their future use as quantum-optical devices. Therefore, all-epitaxial cavities with CdSe quantum dot embedded in pillar structures with different geometries have been realized by focused-ion-beam etching. The quality factors of circularly shaped pillar microcavities have been measured and their dependence on the excitation power is discussed. As a possibility to achieve polarized light emission, asymmetrically shaped microcavities are presented. Examples of an elliptically shaped pillar as well as of photonic molecules are investigated with respect to their photoluminescence characteristics and polarization.

The Sloan-C Pillars: Towards a Balanced Approach to Measuring Organizational Learning

Science.gov (United States)

Yeo, Kee Meng; Mayadas, A. Frank

2010-01-01

The Sloan Pillars have set the standard for university-wide online learning program assessment for more than a dozen years. In this paper, the authors propose the extension of the Pillars to corporate e-learning, offering an alternative to traditional enterprise learning assessments. Claiming that conventional methods stress individual courses or…

Design and construction of porous metal-organic frameworks based on flexible BPH pillars

Science.gov (United States)

Hao, Xiang-Rong; Yang, Guang-sheng; Shao, Kui-Zhan; Su, Zhong-Min; Yuan, Gang; Wang, Xin-Long

2013-02-01

Three metal-organic frameworks (MOFs), [Co2(BPDC)2(4-BPH)·3DMF]n (1), [Cd2(BPDC)2(4-BPH)2·2DMF]n (2) and [Ni2(BDC)2(3-BPH)2 (H2O)·4DMF]n (3) (H2BPDC=biphenyl-4,4'-dicarboxylic acid, H2BDC=terephthalic acid, BPH=bis(pyridinylethylidene)hydrazine and DMF=N,N'-dimethylformamide), have been solvothermally synthesized based on the insertion of heterogeneous BPH pillars. Framework 1 has "single-pillared" MOF-5-like motif with inner cage diameters of up to 18.6 Å. Framework 2 has "double pillared" MOF-5-like motif with cage diameters of 19.2 Å while 3 has "double pillared" 8-connected framework with channel diameters of 11.0 Å. Powder X-ray diffraction (PXRD) shows that 3 is a dynamic porous framework.

Influência do método de síntese no processo de pilarização com titânio de uma esmectita da região amazônica Influence of the synthesis method on the process of pillarization of smectite from the amazonic region with titanium

Directory of Open Access Journals (Sweden)

D. L. Guerra

2006-12-01

Full Text Available Amostras de argila esmectítica provenientes do município de Serra Madureira no Estado do Acre foram utilizadas no processo de pilarização. As matrizes natural e pilarizada foram caracterizadas por difração de raios X, espectroscopia no infravermelho com transformada de Fourier, análises térmicas diferencial e gravimétrica, microscopia eletrônica de varredura, espectroscopia de raios X por energia dispersiva e análise textural. As soluções pilarizantes de titânio, Ti(OC2H54 e TiCl4, foram analisadas por espectroscopia no infravermelho com transformada de Fourier. O íon intercalante foi obtido através da reação química entre as soluções de Ti(OC2H54 e HCl na proporção aproximada de HCl/Ti=1 e soluções de TiCl4 em reação com etanol com relação Ti/argila= 25 mmol Ti/g. A intercalação da notronita foi efetuada utilizando-se de dois métodos: com a solução de acido clorídrico incorporada paulatinamente na solução de etóxido de titânio, e utilizando o cloreto de titânio em solução de etanol, com vigorosa agitação a 25 ºC durante 3 h e com calcinação a 450 ºC e 600 ºC. Os resultados de difração de raios X do processo de pilarização mostraram alterações no espaçamento basal de 15,30 Å para 18,76 Å, e na área de superfície específica de 44,37 m²/g para 188,72 m²/g. A estabilidade térmica da argila natural foi otimizada com o processo de pilarização.Smectite clays of the State of Acre, Brazil, were used for the pillarization process. The natural and pillarized matrices were characterized by X-ray diffraction, Fourier transform infrared spectroscopy (FTIR, thermal analysis, scanning electron microscopy, energy dispersive spectroscopy and textural analysis. The titanium pillarized solutions Ti(OC2H54 and TiCl4 were analyzed by FTIR. The intercalation ion was obtained by reacting Ti(OC2H54 with HCl (HCl/Ti ~ 1 and TiCl4 with ethanol (Ti/clay ~ 25 mmol Ti/g. The notronite intercalation was

Structure and Optical Properties of Titania-PDMS Hybrid Nanocomposites Prepared by In Situ Non-Aqueous Synthesis

Directory of Open Access Journals (Sweden)

Antoine R. M. Dalod

2017-12-01

Full Text Available Organic-inorganic hybrid materials are attractive due to the combination of properties from the two distinct types of materials. In this work, transparent titania-polydimethylsiloxane hybrid materials with up to 15.5 vol. % TiO2 content were prepared by an in situ non-aqueous method using titanium (IV isopropoxide and hydroxy-terminated polydimethylsiloxane as precursors. Spectroscopy (Fourier transform infrared, Raman, Ultraviolet-visible, ellipsometry and small-angle X-ray scattering analysis allowed to describe in detail the structure and the optical properties of the nanocomposites. Titanium alkoxide was successfully used as a cross-linker and titania-like nanodomains with an average size of approximately 4 nm were shown to form during the process. The resulting hybrid nanocomposites exhibit high transparency and tunable refractive index from 1.42 up to 1.56, depending on the titania content.

Clay Houses

Science.gov (United States)

Pedro, Cathy

2011-01-01

In this article, the author describes a project designed for fourth-graders that involves making clay relief sculptures of houses. Knowing the clay houses will become a family heirloom makes this lesson even more worth the time. It takes three classes to plan and form the clay, and another two to underglaze and glaze the final products.

Mine flooding and barrier pillar hydrology in the Pittsburgh basin

International Nuclear Information System (INIS)

Leavitt, B.R.

1999-01-01

Pennsylvania began requiring barrier pillars between mines as early as 1930. The Ashley formula, resulting from a early commission on the problem, requires 20 feet of coal plus a thickness of coal equal to four times the seam height plus an additional thickness of coal equal to one tenth of the overburden thickness, or the maximum potential hydraulic head. For a 6-foot thick coal seam under 400 feet of cover, the barrier would be 20+24+40=84 feet. The Ashley formula is intended to protect coal miners from a catastrophic failure of a barrier pillar which has a high head of water impounded behind it. The paper gives several examples of flooded and unflooded mines and the performance of their barrier pillars with respect to acid mine drainage. It is concluded that for all practical purposes, barrier pillars designed with the Ashley formula are able to hydrologically isolate mines from one another. This hydrologic isolation promotes the inundation of closed mines. Inundation effectively stops acid formation, thus, fully inundated mines do not represent a perpetual source of acid mine drainage. Infiltrating ground water improves the mine water chemistry resulting in a net alkaline discharge which has greatly lowered iron concentrations. The best locations for acid mine drainage treatment plants is at the lowest surface elevation above the mine with mine flooded to near that elevation

High-aspect-ratio, silicon oxide-enclosed pillar structures in microfluidic liquid chromatography.

Science.gov (United States)

Taylor, Lisa C; Lavrik, Nickolay V; Sepaniak, Michael J

2010-11-15

The present paper discusses the ability to separate chemical species using high-aspect-ratio, silicon oxide-enclosed pillar arrays. These miniaturized chromatographic systems require smaller sample volumes, experience less flow resistance, and generate superior separation efficiency over traditional packed bed liquid chromatographic columns, improvements controlled by the increased order and decreased pore size of the systems. In our distinctive fabrication sequence, plasma-enhanced chemical vapor deposition (PECVD) of silicon oxide is used to alter the surface and structural properties of the pillars for facile surface modification while improving the pillar mechanical stability and increasing surface area. The separation behavior of model compounds within our pillar systems indicated an unexpected hydrophobic-like separation mechanism. The effects of organic modifier, ionic concentration, and pressure-driven flow rate were studied. A decrease in the organic content of the mobile phase increased peak resolution while detrimentally effecting peak shape. A resolution of 4.7 (RSD = 3.7%) was obtained for nearly perfect Gaussian shaped peaks, exhibiting plate heights as low as 1.1 and 1.8 μm for fluorescein and sulforhodamine B, respectively. Contact angle measurements and DART mass spectrometry analysis indicate that our employed elastomeric soft bonding technique modifies pillar properties, creating a fortuitous stationary phase. This discovery provides evidence supporting the ability to easily functionalize PECVD oxide surfaces by gas-phase reactions.

Role of binder in the synthesis of titania membrane

Indian Academy of Sciences (India)

The synthesis of titania membrane through sol–gel route involves hydrolysis of alkoxide, peptization of hydrous oxide of titanium to obtain a sol, adjustment of the sol viscosity by including a binder and filtration of the viscous sol through a microporous support, gelation and sintering to desired temperature. The binder plays ...

Scanning probe microscopy studies on the adsorption of selected molecular dyes on titania

Directory of Open Access Journals (Sweden)

Jakub S. Prauzner-Bechcicki

2016-11-01

Full Text Available Titanium dioxide, or titania, sensitized with organic dyes is a very attractive platform for photovoltaic applications. In this context, the knowledge of properties of the titania–sensitizer junction is essential for designing efficient devices. Consequently, studies on the adsorption of organic dyes on titania surfaces and on the influence of the adsorption geometry on the energy level alignment between the substrate and an organic adsorbate are necessary. The method of choice for investigating the local environment of a single dye molecule is high-resolution scanning probe microscopy. Microscopic results combined with the outcome of common spectroscopic methods provide a better understanding of the mechanism taking place at the titania–sensitizer interface. In the following paper, we review the recent scanning probe microscopic research of a certain group of molecular assemblies on rutile titania surfaces as it pertains to dye-sensitized solar cell applications. We focus on experiments on adsorption of three types of prototypical dye molecules, i.e., perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA, phtalocyanines and porphyrins. Two interesting heteromolecular systems comprising molecules that are aligned with the given review are discussed as well.

Studies of Dye Sensitisation Kinetics and Sorption Isotherms of Direct Red 23 on Titania

Directory of Open Access Journals (Sweden)

Peter J. Holliman

2008-01-01

Full Text Available Sorption kinetics and isotherms have been measured for a commercial dye (Direct Red 23 on different samples of powdered Titania, and the data were analysed to better understand the dye sensitization process for dye sensitised solar cells (DSSCs. For the sorption kinetics, the data show rapid initial sorption (<1 hour followed by slower rate of increasing uptake between 1 and 24 hours. While higher initial concentrations of dye correspond to higher sorption overall, less dye is absorbed from higher initial dye concentrations when considered as percentage uptake. The correlation between the sorption data and model isotherms has been considered with time. The Langmuir model shows better correlations compared to the Freundlich isotherm. The dye uptake data has also been correlated with Titania characterization data (X-ray diffraction, scanning electron microscopy, BET and zero point charge analysis. Kinetic data show significantly better fits to second-order models compared to first order. This suggests that chemisorption is taking place and that the interaction between the dye sorbate and the Titania sorbent involves electron sharing to form an ester bond.

The systems containing clays and clay minerals from modified drug release: a review.

Science.gov (United States)

Rodrigues, Luís Alberto de Sousa; Figueiras, Ana; Veiga, Francisco; de Freitas, Rivelilson Mendes; Nunes, Lívio César Cunha; da Silva Filho, Edson Cavalcanti; da Silva Leite, Cleide Maria

2013-03-01

Clays are materials commonly used in the pharmaceutical industry, either as ingredients or as active ingredients. It was observed that when they are administered concurrently, they may interact with drugs reducing their absorption. Therefore, such interactions can be used to achieve technological and biopharmaceutical advantages, regarding the control of release. This review summarizes bibliographic (articles) and technological (patents) information on the use of systems containing clays and clay minerals in modified drug delivery. In this area, formulations such natural clay, commercial clay, synthetic clay, composites clay-polymers, nanocomposites clay-polymers, films and hidrogels composites clay-polymers are used to slow/extend or vectorize the release of drugs and consequently they increase their bioavailability. Finally, this review summarizes the fields of technology and biopharmaceutical applications, where clays are applied. Copyright © 2012 Elsevier B.V. All rights reserved.

Fabrication of Pillar Shaped Electrode Arrays for Artificial Retinal Implants

Directory of Open Access Journals (Sweden)

Sung June Kim

2008-09-01

Full Text Available Polyimide has been widely applied to neural prosthetic devices, such as the retinal implants, due to its well-known biocompatibility and ability to be micropatterned. However, planar films of polyimide that are typically employed show a limited ability in reducing the distance between electrodes and targeting cell layers, which limits site resolution for effective multi-channel stimulation. In this paper, we report a newly designed device with a pillar structure that more effectively interfaces with the target. Electrode arrays were successfully fabricated and safely implanted inside the rabbit eye in suprachoroidal space. Optical Coherence Tomography (OCT showed well-preserved pillar structures of the electrode without damage. Bipolar stimulation was applied through paired sites (6:1 and the neural responses were successfully recorded from several regions in the visual cortex. Electrically evoked cortical potential by the pillar electrode array stimulation were compared to visual evoked potential under full-field light stimulation.

Strain relief InGaN/GaN MQW micro-pillars for high brightness LEDs

KAUST Repository

Shen, Chao

2013-01-01

Micro-structured group-III-nitrides are considered as promising strain relief structures for high efficiency solid state lighting. In this work, the strain field in InGaN/GaN multi-quantum wells (MQWs) micro-pillars is investigated using micro-Raman spectroscopy and the design of micro-pillars were studied experimentally. We distinguished the strained and strain-relieved signatures of the GaN layer from the E2 phonon peak split from the Raman scattering signatures at 572 cm-1 and 568 cm-1, respectively. The extent of strain relief is examined considering the height and size of micro-pillars fabricated using focused ion beam (FIB) micro-machining technique. A significant strain relief can be achieved when one micro-machined through the entire epi-layers, 3 μm in our study. The dependence of strain relief on micro-pillar diameter (D) suggested that micro-pillar with D < 3 μm showed high degree of strain relief. Our results shed new insights into designing strain-relieved InGaN/GaN microstructures for high brightness light emitting diode arrays. © 2013 IEEE.

Electrical characterization of Ge–Sb–Te phase change nano-pillars using conductive atomic force microscopy

International Nuclear Information System (INIS)

Bae, Byeong-Ju; Hong, Sung-Hoon; Hwang, Seon-Yong; Hwang, Jae-Yeon; Yang, Ki-Yeon; Lee, Heon

2009-01-01

The electrical characteristic of phase change material was studied in nano-scale using nanoimprint lithography and a conducting atomic force microscopy measurement system. Nanoimprint lithography was used to fabricate the nano-scale phase change material pattern. A Pt-coated AFM tip was used as a top electrode to measure the electrical characteristics of the GST nano-pillar. The GST nano-pillar, which is 200 nm in diameter, was amorphized by 2 V and 5 ns reset pulse and was then brought back to the crystalline phase by applying 1.3 V and 150 ns set pulse. Using this measurement system, the GST nano-pillar was switched between the amorphous and crystalline phases more than five times. The results of the reset and the set current measurement with the GST nano-pillar sizes show that the reset and the set currents also decreased with the decrease of the GST pillar size

Silicon based near infrared photodetector using self-assembled organic crystalline nano-pillars

Energy Technology Data Exchange (ETDEWEB)

Ajiki, Yoshiharu, E-mail: yoshiharu-ajiki@ot.olympus.co.jp, E-mail: isao@i.u-tokyo.ac.jp [Micromachine Center, 67 Kanda Sakumagashi, Chiyoda-ku, Tokyo 100-0026 (Japan); Kan, Tetsuo [Department of Mechano-Informatics, Graduate School of Information Science and Technology, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656 (Japan); Yahiro, Masayuki; Hamada, Akiko; Adachi, Chihaya [Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi, Fukuoka 819-0395 (Japan); Adachi, Junji [Office for Strategic Research Planning, Kyushu University, 6-10-1 Hakozaki, Higashi, Fukuoka 812-8581 (Japan); Matsumoto, Kiyoshi [IRT Research Initiative, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656 (Japan); Shimoyama, Isao, E-mail: yoshiharu-ajiki@ot.olympus.co.jp, E-mail: isao@i.u-tokyo.ac.jp [Department of Mechano-Informatics, Graduate School of Information Science and Technology, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656 (Japan); IRT Research Initiative, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656 (Japan)

2016-04-11

We propose a silicon (Si) based near-infrared photodetector using self-assembled organic crystalline nano-pillars, which were formed on an n-type Si substrate and were covered with an Au thin-film. These structures act as antennas for near-infrared light, resulting in an enhancement of the light absorption on the Au film. Because the Schottky junction is formed between the Au/n-type Si, the electron excited by the absorbed light can be detected as photocurrent. The optical measurement revealed that the nano-pillar structures enhanced the responsivity for the near-infrared light by 89 (14.5 mA/W) and 16 (0.433 mA/W) times compared with those of the photodetector without nano-pillars at the wavelengths of 1.2 and 1.3 μm, respectively. Moreover, no polarization dependency of the responsivity was observed, and the acceptable incident angle ranged from 0° to 30°. These broad responses were likely to be due to the organic nano-pillar structures' having variation in their orientation, which is advantageous for near-infrared detector uses.

Fabrication of porous silver/titania composite hollow spheres with enhanced photocatalytic performance

International Nuclear Information System (INIS)

Li, Sa; Halperin, Shakked O.; Wang, Chang-An

2015-01-01

Silver/titania composite hollow spheres were first synthesized through an in-situ chemical reaction using functional-grouped carbon spheres as the template in this study. The prepared samples were characterized through an X-ray diffraction, N 2 adsorption–desorption, scanning electron microscopy, transmission electron microscopy and UV–Vis spectrophotometer. The photocatalytic activity of as-prepared samples was evaluated by photocatalytic decolorization of Methyl orange (MO) aqueous solution at ambient temperature under UV light. We found a structure with an optimal Ag:TiO 2 composition that exhibited a photodecomposition rate constant more than twice as high as titania hollow spheres lacking silver, and over three times higher than a commercial photocatalyst. - Highlights: • Ag/silver composites. • Hollow spheres. • Photocatalysis enhancement

Gas sensor based on photoconductive electrospun titania nanofibres operating at room temperature

Energy Technology Data Exchange (ETDEWEB)

Zampetti, E., E-mail: emiliano.zampetti@artov.imm.cnr.it; Macagnano, A.; Bearzotti, A. [Consiglio Nazionale delle Ricerche, Istituto per la Microelettronica e Microsistemi (CNR IMM) (Italy)

2013-04-15

An important drawback of semiconductor gas sensors is their operating temperature that needs the use of heaters. To overcome this problem a prototyping sensor using titania nanofibres (with an average diameter of 50 nm) as sensitive membrane were fabricated by electrospinning directly on the transducer of the sensor. Exploiting the effect of titania photoconductivity, resistance variations upon gas interaction under continuous irradiation of ultra violet light were measured at room temperature. The resistive sensor response was evaluated towards ammonia, nitrogen dioxide and humidity. The sensor exhibited a higher response to ammonia than to nitrogen dioxide, especially for concentrations larger than 100 ppb. For 200 ppb of ammonia and nitrogen dioxide, the responses were {approx}2.8 and 1.5 %, respectively.

Soft template strategy to synthesize iron oxide-titania yolk-shell nanoparticles as high-performance anode materials for lithium-ion battery applications.

Science.gov (United States)

Lim, Joohyun; Um, Ji Hyun; Ahn, Jihoon; Yu, Seung-Ho; Sung, Yung-Eun; Lee, Jin-Kyu

2015-05-18

Yolk-shell-structured nanoparticles with iron oxide core, void, and a titania shell configuration are prepared by a simple soft template method and used as the anode material for lithium ion batteries. The iron oxide-titania yolk-shell nanoparticles (IO@void@TNPs) exhibit a higher and more stable capacity than simply mixed nanoparticles of iron oxide and hollow titania because of the unique structure obtained by the perfect separation between iron oxide nanoparticles, in combination with the adequate internal void space provided by stable titania shells. Moreover, the structural effect of IO@void@TNPs clearly demonstrates that the capacity retention value after 50 cycles is approximately 4 times that for IONPs under harsh operating conditions, that is, when the temperature is increased to 80 °C. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Magnetic behaviour of arrays of Ni nanowires by electrodeposition into self-aligned titania nanotubes

International Nuclear Information System (INIS)

Prida, V.M.; Hernandez-Velez, M.; Cervera, M.; Pirota, K.; Sanz, R.; Navas, D.; Asenjo, A.; Aranda, P.; Ruiz-Hitzky, E.; Batallan, F.; Vazquez, M.; Hernando, B.; Menendez, A.; Bordel, N.; Pereiro, R.

2005-01-01

Arrays of Ni nanowires electrodeposited into self-aligned and randomly disordered titania nanotube arrays grown by anodization process are investigated by X-ray diffraction, SEM, rf-GDOES and VSM magnetometry. The titania nanotube outer diameter is about 160 nm, wall thickness ranging from 60 to 70 nm and 300 nm in depth. The so-obtained Ni nanowires reach above 100 nm diameter and 240 nm length, giving rise to coercive fields of 98 and 200 Oe in the perpendicular or parallel to the nanowires axis hysteresis loops, respectively. The formation of magnetic vortex domain states is also discussed

InGaN micro-LED-pillar as the building block for high brightness emitters

KAUST Repository

Shen, Chao; Cha, Dong Kyu; Ng, Tien Khee; Ooi, Boon S.; Yang, Yang

2013-01-01

In summary, we confirmed the improved electrical and optical characteristics, with reduced efficiency droop in InGaN μLED-pillars when these devices were scaled down in size. We demonstrated that strain relief contributed to further improvement in EQE characteristics in small InGaN μLED-pillars (D < 50 μm), apart from the current spreading effect. The μLED-pillar can be deployed as the building block for large effective-area, high brightness emitter. © 2013 IEEE.

Enhanced visible-light activity of titania via confinement inside carbon nanotubes

KAUST Repository

Chen, Wei

2011-09-28

Titania confined inside carbon nanotubes (CNTs) was synthesized using a restrained hydrolysis method. Raman spectra and magnetic measurements using a SQUID magnetometer suggested the formation of remarkable oxygen vacancies over the encapsulated TiO 2 in comparison with nanoparticles dispersed on the outer surface of CNTs, extending the photoresponse of TiO 2 from the UV to the visible-light region. The CNT-confined TiO 2 exhibited improved visible-light activity in the degradation of methylene blue (MB) relative to the outside titania and commercial P25, which is attributed to the modification of the electronic structure of TiO 2 induced by the unique confinement inside CNTs. These results provide further insight into the effect of confinement within CNTs, and the composites are expected to be promising for applications in visible-light photocatalysis. © 2011 American Chemical Society.

Synthesis, characterization and performance of NiMo catalysts supported on titania modified alumina for the hydroprocessing of different gas oils derived from Athabasca bitumen

Energy Technology Data Exchange (ETDEWEB)

Ferdous, D.; Bakhshi, N.N.; Dalai, A.K. [Catalysis and Chemical Reactor Engineering Laboratories, Department of Chemical Engineering, University of Saskatchewan, 57 Campus Drive, Saskatoon, Sask. (Canada); Adjaye, J. [Syncrude Canada Ltd., Edmonton Research Center, No. 9421, 17th Avenue, Edmonton, Alta. (Canada)

2007-03-08

In this work, a series of NiMo/Al{sub 2}O{sub 3} catalyst was prepared using different Al{sub 2}O{sub 3} supports modified by titania (0-9 wt%). All modified supports and fresh catalysts were characterized by BET surface area, pore volume and pore diameter measurement, TPR, TPD, XRD, FTIR and Raman spectroscopy analyses. The initial activity of these catalysts were tested in a trickle-bed reactor using three different gas oils such as light gas oil (LGO), blended gas oil (blended: 50% LGO and 50% HGO) and heavy gas oil (HGO), all derived from Athabasca bitumen. Little structural change in alumina was observed with the incorporation of titania. XRD analysis showed the well dispersion of Ni and Mo on the support. Titania in alumina increased the formation of polymolybdenum oxide on the catalyst as evident from TPR and Raman analyses. Weak-intermediate-strong acid sites on the catalyst were observed at all titania concentrations. The Lewis and Bronsted acidity on the catalyst surface increased with the increase in titania concentration from 0 to 9 wt%. Nitrogen conversion increased from 57 to 71 wt%, from 83 to 93 wt% and from 75 to 80 wt% for LGO, blended and HGO, respectively and also sulfur conversion of LGO increased from 86 to 92 wt% when titania concentration was increased from 0 to 9 wt%. For blended and HGO, sulfur conversion was in the range 96-99 wt% at all titania concentrations. (author)

Trajectory generation algorithm for smooth movement of a hybrid-type robot Rocker-Pillar

Energy Technology Data Exchange (ETDEWEB)

Jung, Seung Min; Choi, Dong Kyu; Kim, Jong Won [School of Mechanical and Aerospace Engineering, Seoul National University, Seoul (Korea, Republic of); Kim, Hwa Soo [Dept. of Mechanical System Engineering, Kyonggi University, Suwon (Korea, Republic of)

2016-11-15

While traveling on rough terrain, smooth movement of a mobile robot plays an important role in carrying out the given tasks successfully. This paper describes the trajectory generation algorithm for smooth movement of hybrid-type mobile robot Rocker-Pillar by adjusting the angular velocity of its caterpillar as well as each wheel velocity in such a manner to minimize a proper index for smoothness. To this end, a new Smoothness index (SI) is first suggested to evaluate the smoothness of movement of Rocker-Pillar. Then, the trajectory generation algorithm is proposed to reduce the undesired oscillations of its Center of mass (CoM). The experiment are performed to examine the movement of Rocker-Pillar climbing up the step whose height is twice larger than its wheel radius. It is verified that the resulting SI is improved by more than 40 % so that the movement of Rocker-Pillar becomes much smoother by the proposed trajectory algorithm.

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

Science.gov (United States)

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

2013-06-28

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

Reverse engineering of B-pillar with 3D optical scanning for manufacturing of non-uniform thickness part

OpenAIRE

Islam Md. Tasbirul; Abdullah A.B.; Mahmud Mohamad Zihad

2017-01-01

This paper presents reverse engineering (RE) of a complex automobile structural part, B-pillar. As a major part of the automobile body-in white (BiW), B-pillar has substantial opportunity for weight reduction by introducing variable thickness across its sections. To leverage such potential, an existing B-pillar was reverse engineered with a 3D optical scanner and computer aided design (CAD) application. First, digital data (i.e. in meshes) of exiting B-pillar was obtained by the scanner, and ...

Geochemical of clay formations : study of Spanish clay REFERENCE

International Nuclear Information System (INIS)

Turrero, M. J.; Pena, J.

2003-01-01

Clay rocks are investigated in different international research programs in order to assess its feasibility for the disposal of high level radioactive wastes. This is because different sepcific aspects: they have low hydraulic conductivity (10''-11-10''-15 m/s), a high sorption capacity, self-sealing capacity of facults and discontinuities and mechanical resistance. Several research programs on clay formations are aimed to study the chemistry of the groundwater and the water-rock reactions that control it: e. g. Boom Clay (Mol, Belgium), Oxford Clay /Harwell, United Kingdom), Toarcian Clay (Tournemire, France), Palfris formation (Wellenberg, Switzerland), Opalinus Clay (Bure, France). Based on these studies, considerable progress in the development of techniques for hydrologic, geochemical and hydrogeochemical characterization of mudstones has been accomplished (e. g. Beaufais et al. 1994, De Windt el al. 1998. Thury and Bossart 1999, Sacchi and Michelot 2000) with important advances in the knowledge of geochemical process in these materials (e. g. Reeder et al. 1993, Baeyens and Brandbury 1994, Beaucaire et al. 2000, Pearson et al., 2003).Furtermore, geochemical modeling is commonly used to simulate the evolution of water chemistry and to understand quantitatively the processes controlling the groundwater chemistry (e. g. Pearson et al. 1998, Tempel and Harrison 2000, Arcos et al., 2001). The work presented here is part of a research program funded by Enresa in the context of its R and D program. It is focused on the characterization of a clay formation (reference Argillaceous Formation, RAF) located within the Duero Basin (north-centralSpain). The characterisation of th ephysical properties,, fluid composition, mineralogy, water-rock reaction processes, geochemical modelling and sorption properties of the clays from the mentioned wells is the main purpose of this work. (Author)

Effect of orientation and loading rate on compression behavior of small-scale Mo pillars

International Nuclear Information System (INIS)

Schneider, A.S.; Clark, B.G.; Frick, C.P.; Gruber, P.A.; Arzt, E.

2009-01-01

Recently, much work has focused on the size effect in face centered cubic (fcc) structures, however few pillar studies have focused on body centered cubic (bcc) metals. This paper explores the role of bcc crystal structure on the size effect, through compression testing of [001] and [235] Molybdenum (Mo) small-scale pillars manufactured by focused ion beam (FIB). The pillar diameters ranged from 200 nm to 5 μm. Results show that the relationship between yield stress and diameter exhibits an inverse relationship (σ y ∝ d -0.22 for [001] Mo and σ y ∝ d -0.34 for [235] Mo) weaker than that observed for face centered cubic (fcc) metals (σ y ∝ d -0.6to-1.0 ). Additional tests at various loading rates revealed that small-scale Mo pillars exhibit a strain rate sensitivity similar to bulk Mo.

The possibility of increasing the efficiency of accessible coal deposits by optimizing dimensions of protective pillars or the scope of exploitation

Science.gov (United States)

Bańka, Piotr; Badura, Henryk; Wesołowski, Marek

2017-11-01

One of the ways to protect objects exposed to the influences of mining exploitation is establishing protective pillars for them. Properly determined pillar provides effective protection of the object for which it was established. Determining correct dimensions of a pillar requires taking into account contradictory requirements. Protection measures against the excessive influences of mining exploitation require designing the largest possible pillars, whereas economic requirements suggest a maximum reduction of the size of resources left in the pillar. This paper presents algorithms and programs developed for determining optimal dimensions of protective pillars for surface objects and shafts. The issue of designing a protective pillar was treated as a nonlinear programming task. The objective function are the resources left in a pillar while nonlinear limitations are the deformation values evoked by the mining exploitation. Resources in the pillar may be weighted e.g. by calorific value or by the inverse of output costs. The possibility of designing pillars of any polygon shape was taken into account. Because of the applied exploitation technologies the rectangular pillar shape should be considered more advantageous than the oval one, though it does not ensure the minimization of resources left in a pillar. In this article there is also presented a different approach to the design of protective pillars, which instead of fixing the pillar boundaries in subsequent seams, the length of longwall panels of the designed mining exploitation is limited in a way that ensures the effective protection of an object while maximizing the extraction ratio of the deposit.

Fractal dimension and energetic heterogeneity of gold-modified Al-Fe-Ce pilc's

International Nuclear Information System (INIS)

Carriazo, J.G.; Molina, R.; Moreno, S.

2008-01-01

This paper studies the energetic and topographical changes that occur on the surface of a series of clays pillared with the mixed Al-Fe-Ce system and on the surface of solids synthesized by the deposition of gold nanoparticles over these pillared clays. The energetic heterogeneity of the solids was analyzed by means of the distribution of the adsorption potential, while the variations in the fractal dimension were determined from the nitrogen adsorption isotherms at 77 K, using the equation proposed by Avnir-Jaroniec. Results show the generation of microporous structures with important topographical modifications indicating an increase in the roughness (fractal geometry) of the surface of the solids as a consequence of the pillaring, revealing a positive effect of cerium addition in the synthesis process and the possible formation of nanoparticles of iron species and gold on the surface of pillared clays. The solids were also analyzed by transmission electron microscopy (TEM), confirming the formation of nanoparticles on the surface.

Aespoe Pillar Stability Experiment. Modelling of fracture development of APSE by FRACOD

International Nuclear Information System (INIS)

Rinne, Mikael; Baotang Shen; Lee, Hee-Suk

2004-03-01

An in-situ experiment has started at Aespoe HRL to investigate the stability of a pillar between two closely located boreholes of deposition hole scale. This full-scale experiment is named the Aespoe Pillar Stability Experiment (APSE). One of the holes will be pressurized with 0.8 MPa water pressure to simulate confinement by backfill. Thermal stresses will be applied in the pillar by the use of electric heaters to reach the spalling conditions. To quantify the degree of damage during the experiment, an Acoustic Emission (AE) system will be used and strain measurements will be installed. FRACOD is a two dimensional BEM/DDM code for fracturing analysis in rock material. Here it has been used to model the rock mass response during the planned sequences of excavation-confinement-heating. The models predict the stress and displacement fields, fracture initiation and propagation, coalescence and the final failure of the rock mass. The presences of pre-existing fractures, which may have significant influence on the pillar behaviour, have also been considered in the modelling. This report summarises the modelling work using FRACOD to simulate the various experimental stages

Hazard reduction for the application of titania nanoparticles in environmental technology

NARCIS (Netherlands)

Reijnders, L.

2008-01-01

Photocatalytically active titania (TiO2) nanoparticles are applied, and considered for application, in the degradation of hazardous substances. However, these nanoparticles are also hazardous by themselves. High efficiency immobilization of TiO2 nanoparticles on large inorganic supports that are not

Allowable pillar to diameter ratio for strategic petroleum reserve caverns.

Energy Technology Data Exchange (ETDEWEB)

Ehgartner, Brian L.; Park, Byoung Yoon

2011-05-01

This report compiles 3-D finite element analyses performed to evaluate the stability of Strategic Petroleum Reserve (SPR) caverns over multiple leach cycles. When oil is withdrawn from a cavern in salt using freshwater, the cavern enlarges. As a result, the pillar separating caverns in the SPR fields is reduced over time due to usage of the reserve. The enlarged cavern diameters and smaller pillars reduce underground stability. Advances in geomechanics modeling enable the allowable pillar to diameter ratio (P/D) to be defined. Prior to such modeling capabilities, the allowable P/D was established as 1.78 based on some very limited experience in other cavern fields. While appropriate for 1980, the ratio conservatively limits the allowable number of oil drawdowns and hence limits the overall utility and life of the SPR cavern field. Analyses from all four cavern fields are evaluated along with operating experience gained over the past 30 years to define a new P/D for the reserve. A new ratio of 1.0 is recommended. This ratio is applicable only to existing SPR caverns.

In situ EPR studies of reaction pathways in Titania photocatalyst-promoted alkylation of alkenes.

Science.gov (United States)

Rhydderch, Shona; Howe, Russell F

2015-03-03

In situ EPR spectroscopy at cryogenic temperatures has been used to observe and identify paramagnetic species produced when titania is irradiated in the presence of reactants used in the photocatalytic alkylation of maleimide with t-butyl carboxylic acid or phenoxyacetic acid. It is shown that maleimide acts as an acceptor of conduction band electrons. Valence band holes oxidise t-butyl carboxylic acid to the t-butyl radical and phenoxyacetic acid to the phenoxyacetic acid radical cation. In the presence of maleimide, the phenoxymethyl radical is formed from phenoxyacetic acid. The relevance of these observations to the mechanisms of titania photocatalyst-promoted alkylation of alkenes is discussed.

A DFT study on the effect of supporting titania on silica graphene epoxy graphene and carbon nanotubes - Interfacial properties and optical response

CSIR Research Space (South Africa)

Kiarii, EM

2017-08-01

Full Text Available A first principles study of the Titania is done as used in photo-catalysis to generate charge carries. Models of titania, silica, graphene, epoxy graphene monoxide, single wall Carbon nanotubes and their respective layer were studied in order...

Crystallography of Representative MOFs Based on Pillared Cyanonickelate (PICNIC Architecture

Directory of Open Access Journals (Sweden)

Winnie Wong-Ng

2016-09-01

Full Text Available The pillared layer motif is a commonly used route to porous coordination polymers or metal organic frameworks (MOFs. Materials based on the pillared cyano-bridged architecture, [Ni’(LNi(CN4]n (L = pillar organic ligands, also known as PICNICs, have been shown to be especially diverse where pore size and pore functionality can be varied by the choice of pillar organic ligand. In addition, a number of PICNICs form soft porous structures that show reversible structure transitions during the adsorption and desorption of guests. The structural flexibility in these materials can be affected by relatively minor differences in ligand design, and the physical driving force for variations in host-guest behavior in these materials is still not known. One key to understanding this diversity is a detailed investigation of the crystal structures of both rigid and flexible PICNIC derivatives. This article gives a brief review of flexible MOFs. It also reports the crystal structures of five PICNICS from our laboratories including three 3-D porous frameworks (Ni-Bpene, NI-BpyMe, Ni-BpyNH2, one 2-D layer (Ni-Bpy, and one 1-D chain (Ni-Naph compound. The sorption data of BpyMe for CO2, CH4 and N2 is described. The important role of NH3 (from the solvent of crystallization as blocking ligands which prevent the polymerization of the 1-D chains and 2-D layers to become 3D porous frameworks in the Ni-Bpy and Ni-Naph compounds is also addressed.

Titania Supported Pt and Pt/Pd Nano-particle Catalysts for the Oxidation of Sulfur Dioxide

DEFF Research Database (Denmark)

Koutsopoulos, Sotiris; Johannessen, Tue; Eriksen, Kim Michael

2006-01-01

Several types of titania (anatase) were used as supports for pure platinum and Pt–Pd bimetallic alloy catalysts. The preparation methods, normal wet impregnation technique and flame aerosol synthesis, obtained metal loadings of 2% by weight. The prepared catalysts were tested for SO2 oxidation...... activity at atmospheric pressure in the temperature range 250–600 °C. The SO2 to SO3 conversion efficiency of the Pt–Pd alloy was significantly higher than that of the individual metals. The effects of the preparation method and the titania type used on the properties and activity of the resulting catalyst...

Workshops around the pillar system design computer program produced in SIMRAC project GAP334

CSIR Research Space (South Africa)

York, G

2000-03-01

Full Text Available with the actual Pillar System Design program. Four workshops were held, three in the Bushveld Complex, and one at the Conference Centre at CSIR Miningtek. The delegates comprised most of the industry rock mechanics practitioners who deal with pillar system design...

A Monte Carlo model for the intermittent plasticity of micro-pillars

International Nuclear Information System (INIS)

Ng, K S; Ngan, A H W

2008-01-01

Earlier compression experiments on micrometre-sized aluminium pillars, fabricated by focused-ion beam milling, using a flat-punch nanoindenter revealed that post-yield deformation during constant-rate loading was jerky with interspersing strain bursts and linear elastic segments. Under load hold, the pillars crept mainly by means of sporadic strain bursts. In this work, a Monte Carlo simulation model is developed, with two statistics gathered from the load-ramp experiments as input, to account for the jerky deformation during the load ramp as well as load hold. Under load-ramp conditions, the simulations successfully captured other experimental observations made independently from the two inputs, namely, the diverging behaviour of the jerky stress–strain response at higher stresses, the increase in burst frequency and burst size with stress and the overall power-law distribution of the burst size. The model also predicts creep behaviour agreeable with the experimental observations, namely, the occurrence of sporadic bursts with frequency depending on stress, creep time and pillar dimensions

Comprehensive review of geosynthetic clay liner and compacted clay liner

Science.gov (United States)

Shankar, M. Uma; Muthukumar, M.

2017-11-01

Human activity inevitably produces waste materials that must be managed. Some waste can be reused. However many wastes that cannot be used beneficially must be disposed of ensuring environmental safety. One of the common methods of disposal is landfilling. The most common problems of the landfill site are environmental degradation and groundwater contamination caused by leachate produced during the decomposition process of organic material and rainfall. Liner in a landfill is an important component which prevent leachate migration and prevent groundwater contamination. Earthen liners have been widely used to contain waste materials in landfill. Liners and covers for municipal and hazardous waste containment facilities are often constructed with the use of fine-grained, low plasticity soils. Because of low permeability geosynthetic clay liners and compacted clay liners are the main materials used in waste disposal landfills. This paper summaries the important geotechnical characteristics such as hydraulic conductivity, liquid limit and free swell index of geosynthetic clay liner and compacted clay liner based on research findings. This paper also compares geosynthetic clay liner and compacted clay liner based on certain criteria such as thickness, availability of materials, vulnerability to damage etc.

In-plane confinement and waveguiding of surface acoustic waves through line defects in pillars-based phononic crystal

Directory of Open Access Journals (Sweden)

Abdelkrim Khelif

2011-12-01

Full Text Available We present a theoretical analysis of an in-plane confinement and a waveguiding of surface acoustic waves in pillars-based phononic crystal. The artificial crystal is made up of cylindrical pillars placed on a semi-infinite medium and arranged in a square array. With a well-chosen of the geometrical parameters, this pillars-based system can display two kinds of complete band gaps for guided waves propagating near the surface, a low frequency gap based on locally resonant mode of pillars as well as a higher frequency gap appearing at Bragg scattering regime. In addition, we demonstrate a waveguiding of surface acoustic wave inside an extended linear defect created by removing rows of pillars in the perfect crystal. We discuss the transmission and the polarization of such confined mode appearing in the higher frequency band gap. We highlight the strong similarity of such defect mode and the Rayleigh wave of free surface medium. An efficient finite element analysis is used to simulate the propagation of guided waves through silicon pillars on a silicon substrate.

Synthesis and luminescence properties of hybrid organic-inorganic transparent titania thin film activated by in-situ formed lanthanide complexes

International Nuclear Information System (INIS)

Wang Yige; Wang Li; Li Huanrong; Liu Peng; Qin Dashan; Liu Binyuan; Zhang Wenjun; Deng Ruiping; Zhang Hongjie

2008-01-01

Stable transparent titania thin films were fabricated at room temperature by combining thenoyltrifluoroacetone (TTFA)-modified titanium precursors with amphiphilic triblock poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO, P123) copolymers. The obtained transparent titania thin films were systematically investigated by IR spectroscopy, PL emission and excitation spectroscopy and transmission electron microscopy. IR spectroscopy indicates that TTFA coordinates the titanium center during the process of hydrolysis and condensation. Luminescence spectroscopy confirms the in-situ formation of lanthanide complexes in the transparent titania thin film. TEM image shows that the in-situ formed lanthanide complexes were homogeneously distributed throughout the whole thin film. The quantum yield and the number of water coordinated to lanthanide metal center have been theoretically determined based on the luminescence data. - Graphical abstract: Novel stable luminescent organic-inorganic hybrid titania thin film with high transparency activated by in-situ formed lanthanide complexes have been obtained at room temperature via a simple one-pot synthesis approach by using TTFA-modified titanium precursor with amphiphilic triblock copolymer P123. The obtained hybrid thin film displays bright red (or green), near-monochromatic luminescence due to the in-situ formed lanthanide complex

Surface layer composition of titania produced by various methods. The change of layer state under illumination

International Nuclear Information System (INIS)

Zakharenko, V; Daibova, E; Zmeeva, O; Kosova, N

2016-01-01

The comparative analysis of experimental data over titanium dioxide powders prepared by various ways under ambient air is carried out. The results over TiO 2 prepared by high-temperature heating of anatase, produced by burning of titanium micro particles and grinding of rutile crystal are used for that comparison. Water and carbon dioxide were the main products released from the surface of the titania powders. It was found that under UV irradiation absorbed by titania, in absent oxygen, water effectively reacts with lattice oxygen of titanium dioxide. (paper)

Electrochemical coating of dental implants with anodic porous titania for enhanced osteointegration

Directory of Open Access Journals (Sweden)

Amirreza Shayganpour

2015-11-01

Full Text Available Clinical long-term osteointegration of titanium-based biomedical devices is the main goal for both dental and orthopedical implants. Both the surface morphology and the possible functionalization of the implant surface are important points. In the last decade, following the success of nanostructured anodic porous alumina, anodic porous titania has also attracted the interest of academic researchers. This material, investigated mainly for its photocatalytic properties and for applications in solar cells, is usually obtained from the anodization of ultrapure titanium. We anodized dental implants made of commercial grade titanium under different experimental conditions and characterized the resulting surface morphology with scanning electron microscopy equipped with an energy dispersive spectrometer. The appearance of nanopores on these implants confirm that anodic porous titania can be obtained not only on ultrapure and flat titanium but also as a conformal coating on curved surfaces of real objects made of industrial titanium alloys. Raman spectroscopy showed that the titania phase obtained is anatase. Furthermore, it was demonstrated that by carrying out the anodization in the presence of electrolyte additives such as magnesium, these can be incorporated into the porous coating. The proposed method for the surface nanostructuring of biomedical implants should allow for integration of conventional microscale treatments such as sandblasting with additive nanoscale patterning. Additional advantages are provided by this material when considering the possible loading of bioactive drugs in the porous cavities.

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

Science.gov (United States)

Peiris, Thelge Manindu Nirasha

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

Double-sided anodic titania nanotube arrays: a lopsided growth process.

Science.gov (United States)

Sun, Lidong; Zhang, Sam; Sun, Xiao Wei; Wang, Xiaoyan; Cai, Yanli

2010-12-07

In the past decade, the pore diameter of anodic titania nanotubes was reported to be influenced by a number of factors in organic electrolyte, for example, applied potential, working distance, water content, and temperature. All these were closely related to potential drop in the organic electrolyte. In this work, the essential role of electric field originating from the potential drop was directly revealed for the first time using a simple two-electrode anodizing method. Anodic titania nanotube arrays were grown simultaneously at both sides of a titanium foil, with tube length being longer at the front side than that at the back side. This lopsided growth was attributed to the higher ionic flux induced by electric field at the front side. Accordingly, the nanotube length was further tailored to be comparable at both sides by modulating the electric field. These results are promising to be used in parallel configuration dye-sensitized solar cells, water splitting, and gas sensors, as a result of high surface area produced by the double-sided architecture.

Self-assembly of protein-based biomaterials initiated by titania nanotubes.

Science.gov (United States)

Forstater, Jacob H; Kleinhammes, Alfred; Wu, Yue

2013-12-03

Protein-based biomaterials are a promising strategy for creating robust highly selective biocatalysts. The assembled biomaterials must sufficiently retain the near-native structure of proteins and provide molecular access to catalytically active sites. These requirements often exclude the use of conventional assembly techniques, which rely on covalent cross-linking of proteins or entrapment within a scaffold. Here we demonstrate that titania nanotubes can initiate and template the self-assembly of enzymes, such as ribonuclease A, while maintaining their catalytic activity. Initially, the enzymes form multilayer thick ellipsoidal aggregates centered on the nanotube surface; subsequently, these nanosized entities assemble into a micrometer-sized enzyme material that has enhanced enzymatic activity and contains as little as 0.1 wt % TiO2 nanotubes. This phenomenon is uniquely associated with the active anatase (001)-like surface of titania nanotubes and does not occur on other anatase nanomaterials, which contain significantly fewer undercoordinated Ti surface sites. These findings present a nanotechnology-enabled mechanism of biomaterial growth and open a new route for creating stable protein-based biomaterials and biocatalysts without the need for chemical modification.

Characterization of vanadium-doped mesoporous titania and its adsorption of gaseous benzene

Energy Technology Data Exchange (ETDEWEB)

Nguyen-Phan, Thuy-Duong; Song, Myoung Bock; Yun, Hyunran; Kim, Eui Jung; Oh, Eun-Suok [School of Chemical Engineering and Bioengineering, University of Ulsan, Mugeo-dong, Nam-gu, Ulsan 680-749 (Korea, Republic of); Shin, Eun Woo, E-mail: ewshin@mail.ulsan.ac.kr [School of Chemical Engineering and Bioengineering, University of Ulsan, Mugeo-dong, Nam-gu, Ulsan 680-749 (Korea, Republic of)

2011-01-01

A series of vanadium-doped mesoporous titania with different metal contents was synthesized in the study via a sol-gel process with the assistance of a dodecylamine surfactant. The existence of vanadium ions not only suppressed crystallization and sintering but also enhanced the porosity of the mesoporous TiO{sub 2}. Varying the vanadium concentration led to significant changes in the chemical oxidation state of each component. The presence of metal dopants significantly improved the removal efficiency of benzene and the doping the titania with 5 mol% vanadium removed the most benzene, regardless of the adsorption temperature. The adsorption behavior was elucidated by the specific surface area, the interactions between surface hydroxyl groups and the {pi}-electrons of benzene, and the formation of {sigma}-bonding and d-{pi}* back-donation between the adsorbent and organic compounds.

Clay dispersibility and soil friability – testing the soil clay-to-carbon saturation concept

OpenAIRE

Schjønning, P.; de Jonge, L.W.; Munkholm, L.J.; Moldrup, P.; Christensen, B.T.; Olesen, J.E.

2011-01-01

Soil organic carbon (OC) influences clay dispersibility, which affects soil tilth conditions and the risk of vertical migration of clay colloids. No universal lower threshold of OC has been identified for satisfactory stabilization of soil structure. We tested the concept of clay saturation with OC as a predictor of clay dispersibility and soil friability. Soil was sampled three years in a field varying in clay content (~100 to ~220 g kg-1 soil) and grown with different crop rotations. Clay ...

A diabetic retinopathy detection method using an improved pillar K-means algorithm.

Science.gov (United States)

Gogula, Susmitha Valli; Divakar, Ch; Satyanarayana, Ch; Rao, Allam Appa

2014-01-01

The paper presents a new approach for medical image segmentation. Exudates are a visible sign of diabetic retinopathy that is the major reason of vision loss in patients with diabetes. If the exudates extend into the macular area, blindness may occur. Automated detection of exudates will assist ophthalmologists in early diagnosis. This segmentation process includes a new mechanism for clustering the elements of high-resolution images in order to improve precision and reduce computation time. The system applies K-means clustering to the image segmentation after getting optimized by Pillar algorithm; pillars are constructed in such a way that they can withstand the pressure. Improved pillar algorithm can optimize the K-means clustering for image segmentation in aspects of precision and computation time. This evaluates the proposed approach for image segmentation by comparing with Kmeans and Fuzzy C-means in a medical image. Using this method, identification of dark spot in the retina becomes easier and the proposed algorithm is applied on diabetic retinal images of all stages to identify hard and soft exudates, where the existing pillar K-means is more appropriate for brain MRI images. This proposed system help the doctors to identify the problem in the early stage and can suggest a better drug for preventing further retinal damage.

Unusual mechanism of capillary condensation in pores modified with chains forming pillars.

Science.gov (United States)

Borówko, M; Patrykiejew, A; Sokołowski, S

2011-08-07

Density functional approach is applied to study the phase behavior of Lennard-Jones(12,6) fluid in pillared slit-like pores. Our focus is in the evaluation of phase transitions in fluid adsorbed in the pore of a fixed width. If the length of pillars is sufficiently large, we observe additional phase transitions of the first and second order due to the symmetry breaking of the distribution of chain segments and fluid species with respect to the slit-like pore center. Re-entrant symmetry changes and additional critical, critical end points and tricritical points then are observed. The scenario of phase changes is sensitive to the energy of fluid-solid interaction, the amount, and the length of the pillars. Quantitative trends and qualitative changes of the phase diagrams topology are examined depending on the values of these parameters.

Titania nanotubes with adjustable dimensions for drug reservoir sites and enhanced cell adhesion.

Science.gov (United States)

Çalışkan, Nazlı; Bayram, Cem; Erdal, Ebru; Karahaliloğlu, Zeynep; Denkbaş, Emir Baki

2014-02-01

This study aims to generate a bactericidal agent releasing surface via nanotube layer on titanium metal and to investigate how aspect ratio of nanotubes affects drug elution time and cell proliferation. Titania nanotube layers were generated on metal surfaces by anodic oxidation at various voltage and time parameters. Gentamicin loading was carried out via simple pipetting and the samples were tested against S. aureus for the efficacy of the applied modification. Drug releasing time and cell proliferation were also tested in vitro. Titania nanotube layers with varying diameters and lengths were prepared after anodization and anodizing duration was found as the most effective parameter for amount of loaded drug and drug releasing time. Drug elution lasted up to 4 days after anodizing for 80 min of the samples, whereas release completed in 24 h when the samples were anodized for 20 min. All processed samples had bactericidal properties against S. aureus organism except unmodified titanium, which was also subjected to drug incorporation step. The anodization also enhanced water wettability and cell adhesion results. Anodic oxidation is an effective surface modification to enhance tissue-implant interactions and also resultant titania layer can act as a drug reservoir for the release of bactericidal agents. The use of implants as local drug eluting devices is promising but further in vivo testing is required. Copyright © 2013 Elsevier B.V. All rights reserved.

Sol-gel titania-coated needles for solid phase dynamic extraction-GC/MS analysis of desomorphine and desocodeine.

Science.gov (United States)

Su, Chi-Ju; Srimurugan, Sankarewaran; Chen, Chinpiao; Shu, Hun-Chi

2011-01-01

Novel sol-gel titania film coated needles for solid-phase dynamic extraction (SPDE)-GC/MS analysis of desomorphine and desocodeine are described. The high thermal stability of titania film permits efficient extraction and analysis of poorly volatile opiate drugs. The influences of sol-gel reaction time, coating layer, extraction and desorption time and temperature on the SPDE needle performance were investigated. The deuterium labeled internal standard was introduced either during the extraction of analyte or directly injected to GC after the extraction process. The latter method was shown to be more sensitive for the analysis of water and urine samples containing opiate drugs. The proposed conditions provided a wide linear range (from 5-5000 ppb), and satisfactory linearity, with R(2) values from 0.9958 to 0.9999, and prominent sensitivity, LOQs (1.0-5.0 ng/g). The sol-gel titania film coated needle with SPDE-GC/MS will be a promising technique for desomorphine and desocodeine analysis in urine.

Au-coated 3-D nanoporous titania layer prepared using polystyrene-b-poly(2-vinylpyridine) block copolymer nanoparticles.

Science.gov (United States)

Shin, Won-Jeong; Basarir, Fevzihan; Yoon, Tae-Ho; Lee, Jae-Suk

2009-04-09

New nanoporous structures of Au-coated titania layers were prepared by using amphiphilic block copolymer nanoparticles as a template. A 3-D template composed of self-assembled quaternized polystyrene-b-poly(2-vinylpyridine) (Q-PS-b-P2VP) block copolymer nanoparticles below 100 nm was prepared. The core-shell-type nanoparticles were well ordered three-dimensionally using the vertical immersion method on the substrate. The polar solvents were added to the polymer solution to prevent particle merging at 40 degrees C when considering the interaction between polymer nanoparticles and solvents. Furthermore, Au-coated PS-b-P2VP nanoparticles were prepared using thiol-capped Au nanoparticles (3 nm). The 3-D arrays with Au-coated PS-b-P2VP nanoparticles as a template contributed to the preparation of the nanoporous Au-coated titania layer. Therefore, the nanoporous Au-coated titania layer was fabricated by removing PS-b-P2VP block copolymer nanoparticles by oxygen plasma etching.

Synthesis and luminescence properties of hybrid organic-inorganic transparent titania thin film activated by in- situ formed lanthanide complexes

Science.gov (United States)

Wang, Yige; Wang, Li; Li, Huanrong; Liu, Peng; Qin, Dashan; Liu, Binyuan; Zhang, Wenjun; Deng, Ruiping; Zhang, Hongjie

2008-03-01

Stable transparent titania thin films were fabricated at room temperature by combining thenoyltrifluoroacetone (TTFA)-modified titanium precursors with amphiphilic triblock poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO, P123) copolymers. The obtained transparent titania thin films were systematically investigated by IR spectroscopy, PL emission and excitation spectroscopy and transmission electron microscopy. IR spectroscopy indicates that TTFA coordinates the titanium center during the process of hydrolysis and condensation. Luminescence spectroscopy confirms the in-situ formation of lanthanide complexes in the transparent titania thin film. TEM image shows that the in-situ formed lanthanide complexes were homogeneously distributed throughout the whole thin film. The quantum yield and the number of water coordinated to lanthanide metal center have been theoretically determined based on the luminescence data.

Study of hybrid solar cells made of multilayer nanocrystalline titania and poly(3-octylthiophene) or poly-(3-(2-methylhex-2-yl)-oxy-carbonyldithiophene)

DEFF Research Database (Denmark)

Antoniadou, Maria; Stathatos, Elias; Boukos, Nikolaos

2009-01-01

Hybrid solar cells have been constructed by using nanocrystalline titania and hole-transporting polymers. Titania was deposited on fluorine-doped tin-oxide transparent electrodes in three layers: a blocking layer and two nanostructured layers, giving densely packed or open structures. Open...

Amperometric biosensor for hydrogen peroxide based on hemoglobin entrapped in titania sol-gel film

International Nuclear Information System (INIS)

Yu Jiuhong; Ju Huangxian

2003-01-01

Hemoglobin (Hb) was entrapped in a titania sol-gel matrix and used as a mimetic peroxidase to construct a novel amperometric biosensor for hydrogen peroxide. The Hb entrapped titania sol-gel film was obtained with a vapor deposition method, which simplified the traditional sol-gel process for protein immobilization. The morphologies of both titania sol-gel and the Hb films were characterized using scanning electron microscopy (SEM) and proved to be chemically clean, porous, homogeneous. This matrix provided a biocompatible microenvironment for retaining the native structure and activity of the entrapped Hb and a very low mass transport barrier to the substrates. H 2 O 2 could be reduced by the catalysis of the entrapped hemoglobin at -300 mV without any mediator. The reagentless H 2 O 2 sensor exhibited a fast response (less than 5 s) and sensitivity as high as 1.29 mA mM -1 cm -2 . The linear range for H 2 O 2 determination was from 5.0x10 -7 to 5.4x10 -5 M with a detection limit of 1.2x10 -7 M. The apparent Michaelis-Menten constant of the encapsulated hemoglobin was calculated to be 0.18±0.02 mM. The stability of the biosensor was also evaluated

Microscopic Pillars and Tubes Fabricated by Using Fish Dentine as a Molding Template

Directory of Open Access Journals (Sweden)

Weiqun Li

2014-08-01

Full Text Available Biomaterials in nature exhibit delicate structures that are greatly beyond the capability of the current manufacturing techniques. Duplicating these structures and applying them in engineering may help enhance the performance of traditional functional materials and structures. Inspired by gecko’s hierarchical micro- and nano-fibrillar structures for adhesion, in this work we fabricated micro-pillars and tubes by adopting the tubular dentine of black carp fish teeth as molding template. The adhesion performances of the fabricated micro-pillars and tubes were characterized and compared. It was found that the pull-off force of a single pillar was about twice of that of the tube with comparable size. Such unexpected discrepancy in adhesion was analyzed based on the contact mechanics theories.

Electrostatic Self-Assembly Enabling Integrated Bulk and Interfacial Sodium Storage in 3D Titania-Graphene Hybrid.

Science.gov (United States)

Xu, Gui-Liang; Xiao, Lisong; Sheng, Tian; Liu, Jianzhao; Hu, Yi-Xin; Ma, Tianyuan; Amine, Rachid; Xie, Yingying; Zhang, Xiaoyi; Liu, Yuzi; Ren, Yang; Sun, Cheng-Jun; Heald, Steve M; Kovacevic, Jasmina; Sehlleier, Yee Hwa; Schulz, Christof; Mattis, Wenjuan Liu; Sun, Shi-Gang; Wiggers, Hartmut; Chen, Zonghai; Amine, Khalil

2018-01-10

Room-temperature sodium-ion batteries have attracted increased attention for energy storage due to the natural abundance of sodium. However, it remains a huge challenge to develop versatile electrode materials with favorable properties, which requires smart structure design and good mechanistic understanding. Herein, we reported a general and scalable approach to synthesize three-dimensional (3D) titania-graphene hybrid via electrostatic-interaction-induced self-assembly. Synchrotron X-ray probe, transmission electron microscopy, and computational modeling revealed that the strong interaction between titania and graphene through comparably strong van der Waals forces not only facilitates bulk Na + intercalation but also enhances the interfacial sodium storage. As a result, the titania-graphene hybrid exhibits exceptional long-term cycle stability up to 5000 cycles, and ultrahigh rate capability up to 20 C for sodium storage. Furthermore, density function theory calculation indicated that the interfacial Li + , K + , Mg 2+, and Al 3+ storage can be enhanced as well. The proposed general strategy opens up new avenues to create versatile materials for advanced battery systems.

Electrostatic Self-Assembly Enabling Integrated Bulk and Interfacial Sodium Storage in 3D Titania-Graphene Hybrid

Energy Technology Data Exchange (ETDEWEB)

Xu, Gui-Liang [Chemical; Xiao, Lisong [Center; Sheng, Tian [Collaborative; Liu, Jianzhao [Chemical; Hu, Yi-Xin [Chemical; Department; Ma, Tianyuan [Chemical; Amine, Rachid [Materials; Xie, Yingying [Chemical; Zhang, Xiaoyi [X-ray Science; Liu, Yuzi [Nanoscience; Ren, Yang [X-ray Science; Sun, Cheng-Jun [X-ray Science; Heald, Steve M. [X-ray Science; Kovacevic, Jasmina [Center; Sehlleier, Yee Hwa [Center; Schulz, Christof [Center; Mattis, Wenjuan Liu [Microvast Power Solutions, 12603; Sun, Shi-Gang [Collaborative; Wiggers, Hartmut [Center; Chen, Zonghai [Chemical; Amine, Khalil [Chemical

2017-12-15

Room temperature sodium-ion batteries have attracted increased attention for energy storage due to the natural abundance of sodium. However, it remains a huge challenge to develop versatile electrode materials with favorable properties, which requires smart structure design and good mechanistic understanding. Herein, we reported a general and scalable approach to synthesize 3D titania-graphene hybrid via electrostatic-interaction-induced self-assembly. Synchrotron X-ray probe, transmission electron microscopy and computational modeling revealed that the strong interaction between Titania and graphene through comparably strong van-der-Waals forces not only facilitates bulk Na+ intercalation but also enhances the interfacial sodium storage. As a result, the titania-graphene hybrid exhibits exceptional long-term cycle stability up to 5000 cycles, and ultrahigh rate capability up to 20 C for sodium storage. Furthermore, density function theory calculation indicated that the interfacial Li+, K+, Mg2+ and Al3+ storage can be enhanced as well. The proposed general strategy opens up new avenues to create versatile materials for advanced battery systems.

Titania-Coated Silica Alone and Modified by Sodium Alginate as Sorbents for Heavy Metal Ions

Science.gov (United States)

Kołodyńska, D.; Gęca, M.; Skwarek, E.; Goncharuk, O.

2018-04-01

The novel organic-inorganic biohybrid composite adsorbent was synthesized based on nanosized silica-titania modified with alginate within the development of effective adsorbent for heavy metal ions. Effects of metal species Cu(II), Zn(II), Cd(II), and Pb(II); concentrations; pH; temperature; and adsorption onto titania-coated silica (ST20) initial or modified by sodium alginate (ST20-ALG) were studied. The equilibrium and kinetic data of metal ions adsorption were analyzed using Langmuir and Freundlich adsorption models and kinetic models: pseudo first order, pseudo second order, intraparticle kinetic model, and Elovich. The maximum sorption capacities observed were higher for the ST20-ALG composite compared to the initial ST20 oxide for all studied metal ions, namely their values for ST20-ALG were 22.44 mg g- 1 for Cu(II) adsorption, 19.95 mg g- 1 for Zn(II), 18.85 mg g- 1 for Cd(II), and 32.49 mg g- 1 for Pb(II). Structure and properties of initial silica-titania ST20 and modified by sodium alginate ST20-ALG adsorbents were analyzed using nitrogen adsorption/desorption isotherms, ATR-FTIR, SEM-EDS, and pHpzc techniques.

Basic Principle of Advanced Oxidation Technology : Hybrid Technology Based on Ozone and Titania

International Nuclear Information System (INIS)

Widdi Usada; Agus Purwadi

2007-01-01

One of problems in health environment is organic liquid waste from many pollutant resources. Environmental friendly technology for degrading this waste is ozone which produced by plasma discharge technology, but its capability is limited. However, it is needed a new environmental friendly technology which has stronger capability. This new technology is so called advanced oxidation technology. Advanced oxidation technology is a hybrid of ozone, peroxide, UV light and photo catalyst. In this paper, it is introduced basic principle of hybrid of ozone and titania photo catalyst semiconductor. The capability of organic liquid degradation will be stronger because there is new radical which is produced by chemical reaction between electron-hole pair from photo catalyst titania and water or oxygen. This new radical then degrades this organic pollutant. This technology is used to degrade phenol. (author)

Multiscale Micromechanical Modeling of Polymer/Clay Nanocomposites and the Effective Clay Particle

Science.gov (United States)

Sheng, Nuo; Boyce, Mary C.; Parks, David M.; Manovitch, Oleg; Rutledge, Gregory C.; Lee, Hojun; McKinley, Gareth H.

2003-03-01

Polymer/clay nanocomposites have been observed to exhibit enhanced mechanical properties at low weight fractions (Wp) of clay. Continuum-based composite modeling reveals that the enhanced properties are strongly dependent on particular features of the second-phase ¡°particles¡+/-; in particular, the particle volume fraction (fp), the particle aspect ratio (L/t), and the ratio of particle mechanical properties to those of the matrix. However, these important aspects of as-processed nanoclay composites have yet to be consistently and accurately defined. A multiscale modeling strategy was developed to account for the hierarchical morphology of the nanocomposite: at a lengthscale of thousands of microns, the structure is one of high aspect ratio particles within a matrix; at the lengthscale of microns, the clay particle structure is either (a) exfoliated clay sheets of nanometer level thickness or (b) stacks of parallel clay sheets separated from one another by interlayer galleries of nanometer level height. Here, quantitative structural parameters extracted from XRD patterns and TEM micrographs are used to determine geometric features of the as-processed clay ¡°particles¡+/-, including L/t and the ratio of fp to Wp. These geometric features, together with estimates of silicate lamina stiffness obtained from molecular dynamics simulations, provide a basis for modeling effective mechanical properties of the clay particle. The structure-based predictions of the macroscopic elastic modulus of the nanocomposite as a function of clay weight fraction are in excellent agreement with experimental data. The adopted methodology offers promise for study of related properties in polymer/clay nanocomposites.

Organically pillared layered zinc hydroxides

International Nuclear Information System (INIS)

Kongshaug, K.O.; Fjellvaag, Helmer

2004-01-01

The two organically pillared layered zinc hydroxides [Zn 2 (OH) 2 (ndc)], CPO-6, and [Zn 3 (OH) 4 (bpdc)], CPO-7, were obtained in hydrothermal reactions between 2,6-naphthalenedicarboxylic acid (ndc) and zinc nitrate (CPO-6) and 4,4'biphenyldicarboxylate (bpdc) and zinc nitrate (CPO-7), respectively. In CPO-6, the tetrahedral zinc atoms are connected by two μ 2 -OH groups and two carboxylate oxygen atoms, forming infinite layers extending parallel to the bc-plane. These layers are pillared by ndc to form a three-dimensional structure. In CPO-7, the zinc hydroxide layers are containing four-, five- and six coordinated zinc atoms, and the layers are built like stairways running along the [001] direction. Each step is composed of three infinite chains running in the [010] direction. Both crystal structures were solved from conventional single crystal data. Crystal data for CPO-6: Monoclinic space group P2 1 /c (No. 14), a=11.9703(7), b=7.8154(5), c=6.2428(4) A, β=90.816(2) deg., V=583.97(6) A 3 and Z=4. Crystal data for CPO-7: Monoclinic space group C2/c (No. 15), a=35.220(4), b=6.2658(8), c=14.8888(17) A, β=112.580(4) deg., V=3033.8(6) A 3 and Z=8. The compounds were further characterized by thermogravimetric- and chemical analysis

Clay intercalation and influence on crystallinity of EVA-based clay nanocomposites

International Nuclear Information System (INIS)

Chaudhary, D.S.; Prasad, R.; Gupta, R.K.; Bhattacharya, S.N.

2005-01-01

Various polymer clay nanocomposites (PCNs) were prepared from ethylene vinyl acetate copolymer (EVA) with 9, 18 and 28% vinyl acetate (VA) content filled with different wt.% (2.5, 5 and 7.5) of a Montmorillonite-based organo-modified clay (Cloisite[reg] C15A and C30B). The PCNs were prepared using melt blending techniques. Morphological information regarding intercalation and exfoliation were determined by using wide-angle X-ray scattering (WAXS) and transmission electron microscopy (TEM). WAXS and TEM confirmed that increasing the VA content was necessary to achieve greater clay-polymer interaction as seen from the comparatively higher intercalation of clay platelets with 28% VA. The effect of addition of clay on the development and the modification of crystalline morphology in EVA matrix was also studied using WAXS and temperature-modulated differential scanning calorimetry (MDSC). Results are presented showing that the addition of clay platelets does not increase the matrix crystallinity but the morphology was significantly modified such that there was an increase in the 'rigid' amorphous phase. Mechanical properties were also evaluated against the respective morphological information for each specimen and there are indications that the level of clay-polymer interaction plays a significant role in such morphological modification, and in such a way that affects the final PCN mechanical properties which has wide and significant applications in the packaging industries

Clay Dispersibility and Soil Friability-Testing the Soil Clay-to-Carbon Saturation Concept

DEFF Research Database (Denmark)

Schjønning, Per; de Jonge, Lis Wollesen; Munkholm, Lars Juhl

2012-01-01

Soil organic carbon (OC) influences clay dispersibility, which affects soil tilth conditions and the risk of vertical migration of clay colloids. No universal lower threshold of OC has been identified for satisfactory stabilization of soil structure. We tested the concept of clay saturation with OC...... as a predictor of clay dispersibility and soil friability. Soil was sampled 3 yr in a field varying in clay content (∼100 to ∼220 g kg−1 soil) and grown with different crop rotations. Clay dispersibility was measured after end-over-end shaking of field-moist soil and 1- to 2-mm sized aggregates either air......-dried or rewetted to −100 hPa matric potential. Tensile strength of 1- to 2-, 2- to 4-, 4- to 8-, and 8- to 16-mm air-dried aggregates was calculated from their compressive strength, and soil friability estimated from the strength–volume relation. Crop rotation characteristics gave only minor effects on clay...

SBR Brazilian organophilic/clay nanocomposites

International Nuclear Information System (INIS)

Guimaraes, Thiago R.; Valenzuela-Diaz, Francisco R.; Morales, Ana Rita; Paiva, Lucilene B.

2009-01-01

The aim of this work is the obtaining of SBR composites using a Brazilian raw bentonite and the same bentonite treated with an organic salt. The clays were characterized by XRD. The clay addition in the composites was 10 pcr. The composites were characterized by XRD and had measured theirs tension strength (TS). The composite with Brazilian treated clay showed TS 233% higher than a composite with no clay, 133% higher than a composite with Cloisite 30B organophilic clay and 17% lower than a composite with Cloisite 20 A organophilic clay. XRD and TS data evidence that the composite with Brazilian treated clay is an intercalated nanocomposite. (author)

Atrazine biodegradation modulated by clays and clay/humic acid complexes

International Nuclear Information System (INIS)

Besse-Hoggan, Pascale; Alekseeva, Tatiana; Sancelme, Martine; Delort, Anne-Marie; Forano, Claude

2009-01-01

The fate of pesticides in the environment is strongly related to the soil sorption processes that control not only their transfer but also their bioavailability. Cationic (Ca-bentonite) and anionic (Layered Double Hydroxide) clays behave towards the ionisable pesticide atrazine (AT) sorption with opposite tendencies: a noticeable sorption capacity for the first whereas the highly hydrophilic LDH showed no interactions with AT. These clays were modified with different humic acid (HA) contents. HA sorbed on the clay surface and increased AT interactions. The sorption effect on AT biodegradation and on its metabolite formation was studied with Pseudomonas sp. ADP. The biodegradation rate was greatly modulated by the material's sorption capacity and was clearly limited by the desorption rate. More surprisingly, it increased dramatically with LDH. Adsorption of bacterial cells on clay particles facilitates the degradation of non-sorbed chemical, and should be considered for predicting pesticide fate in the environment. - The biodegradation rate of atrazine was greatly modulated by adsorption of the pesticide and also bacterial cells on clay particles.

Influence of Polymer-Clay Interfacial Interactions on the Ignition Time of Polymer/Clay Nanocomposites.

Science.gov (United States)

Zope, Indraneel S; Dasari, Aravind; Yu, Zhong-Zhen

2017-08-11

Metal ions present on smectite clay (montmorillonite) platelets have preferential reactivity towards peroxy/alkoxy groups during polyamide 6 (PA6) thermal decomposition. This changes the decomposition pathway and negatively affects the ignition response of PA6. To restrict these interfacial interactions, high-temperature-resistant polymers such as polyetherimide (PEI) and polyimide (PI) were used to coat clay layers. PEI was deposited on clay by solution-precipitation, whereas PI was deposited through a solution-imidization-precipitation technique before melt blending with PA6. The absence of polymer-clay interfacial interactions has resulted in a similar time-to-ignition of PA6/PEI-clay (133 s) and PA6/PI-clay (139 s) composites as neat PA6 (140 s). On the contrary, PA6 with conventional ammonium-based surfactant modified clay has showed a huge drop in time-to-ignition (81 s), as expected. The experimental evidences provided herein reveal the role of the catalytic activity of clay during the early stages of polymer decomposition.

Colloidal titania-silica-iron oxide nanocomposites and the effect from silica thickness on the photocatalytic and bactericidal activities

Energy Technology Data Exchange (ETDEWEB)

Chanhom, Padtaraporn [Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330 (Thailand); Charoenlap, Nisanart [Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok 10210 (Thailand); Tomapatanaget, Boosayarat [Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330 (Thailand); Insin, Numpon, E-mail: Numpon.I@chula.ac.th [Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330 (Thailand)

2017-04-01

New types of colloidal multifunctional nanocomposites that combine superparamagnetic character and high photocatalytic activity were synthesized and investigated. The superparamagnetic nanocomposites composed of anatase titania, silica, and iron oxide nanoparticles (TSI) were synthesized using thermal decomposition method followed by microemulsion method, without calcination at high temperature. Different techniques including X-ray diffraction (XRD) and transmission electron microscope (TEM) were used to characterize and confirm the structure of the nanocomposites. These nanocomposites showed high photocatalytic activity when used in the photodegradation of methylene blue under irradiation with a black light lamp. Moreover, the nanocomposites exhibited high antibacterial properties. From our study, the nanocomposites can be useful in various applications such as removal of pollutants with readily separation from the environment using an external magnetic field. These composites could effectively photo-degrade the dye at least three cycles without regeneration. The effects of silica shell thickness on the photocatalytic activity was investigated, and the thickness of 6 nm of the silica interlayer is enough for the inhibition of electron translocation between titania and iron oxide nanoparticles and maintaining the efficiency of photocatalytic activity of titania nanoparticles. - Highlights: • New colloidal nanocomposites of iron oxide-silica-titania were prepared. • The nanocomposites exhibited high photocatalytic activity with magnetic response. • The effects of silica thickness on photocatalytic activity were investigated. • Bactericidal activity of the nanocomposites was demonstrated.

Solving the critical thermal bowing in 3C-SiC/Si(111) by a tilting Si pillar architecture

Science.gov (United States)

Albani, Marco; Marzegalli, Anna; Bergamaschini, Roberto; Mauceri, Marco; Crippa, Danilo; La Via, Francesco; von Känel, Hans; Miglio, Leo

2018-05-01

The exceptionally large thermal strain in few-micrometers-thick 3C-SiC films on Si(111), causing severe wafer bending and cracking, is demonstrated to be elastically quenched by substrate patterning in finite arrays of Si micro-pillars, sufficiently large in aspect ratio to allow for lateral pillar tilting, both by simulations and by preliminary experiments. In suspended SiC patches, the mechanical problem is addressed by finite element method: both the strain relaxation and the wafer curvature are calculated at different pillar height, array size, and film thickness. Patches as large as required by power electronic devices (500-1000 μm in size) show a remarkable residual strain in the central area, unless the pillar aspect ratio is made sufficiently large to allow peripheral pillars to accommodate the full film retraction. A sublinear relationship between the pillar aspect ratio and the patch size, guaranteeing a minimal curvature radius, as required for wafer processing and micro-crack prevention, is shown to be valid for any heteroepitaxial system.

Super/Subcritical Fluid Extractions for Preparation of the Crystalline Titania

Czech Academy of Sciences Publication Activity Database

Matějová, Lenka; Cajthaml, Tomáš; Matěj, Z.; Benada, Oldřich; Klusoň, Petr; Šolcová, Olga

2010-01-01

Roč. 52, č. 2 (2010), s. 215-221 ISSN 0896-8446 R&D Projects: GA ČR GP104/09/P290; GA ČR GA104/09/0694 Institutional research plan: CEZ:AV0Z40720504; CEZ:AV0Z50200510 Keywords : titania * supercritical fluid extraction * pressurised fluid extraction Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.986, year: 2010

Lamellar Micelles - Mediated Synthesis of Nanoscale Thick Sheets of Titania

Czech Academy of Sciences Publication Activity Database

Klusoň, P.; Lusková, H.; Šolcová, Olga; Matějová, Lenka; Cajthaml, Tomáš

2007-01-01

Roč. 61, 14-15 (2007), s. 2931-2934 ISSN 0167-577X R&D Projects: GA ČR(CZ) GA104/04/0963; GA ČR(CZ) GD203/03/H140 Institutional research plan: CEZ:AV0Z40720504; CEZ:AV0Z50200510 Keywords : nanostructures * lamellar titania * templating Subject RIV: CA - Inorganic Chemistry Impact factor: 1.625, year: 2007

Probing the Effects of Templating on the UV and Visible Light Photocatalytic Activity of Porous Nitrogen-Modified Titania Monoliths for Dye Removal.

Science.gov (United States)

Nursam, Natalita M; Wang, Xingdong; Tan, Jeannie Z Y; Caruso, Rachel A

2016-07-13

Porous nitrogen-modified titania (N-titania) monoliths with tailored morphologies were prepared using phase separation and agarose gel templating techniques. The doping and templating process were simultaneously carried out in a one-pot step using alcohol amine-assisted sol-gel chemistry. The amount of polymer used in the monoliths that were prepared using phase separation was shown to affect both the physical and optical properties: higher poly(ethylene glycol) content increased the specific surface area, porosity, and visible light absorption of the final materials. For the agarose-templated monoliths, the infiltration conditions affected the monolith morphology. A porous monolith with high surface area and the least shrinkage was obtained when the N containing alkoxide precursor was infiltrated into the agarose scaffolds at 60 °C. The effect of the diverse porous morphologies on the photocatalytic activity of N-titania was studied for the decomposition of methylene blue (MB) under visible and UV light irradiation. The highest visible light activity was achieved by the agarose-templated N-titania monolith, in part due to higher N incorporation. This sample also showed better UV activity, partly because of the higher specific surface area (up to 112 m(2) g(-1)) compared to the phase separation-induced monoliths (up to 103 m(2) g(-1)). Overall, agarose-templated, porous N-titania monoliths provided better features for effectively removing the MB contaminant.

Highly-ordered mesoporous titania thin films prepared via surfactant assembly on conductive indium-tin-oxide/glass substrate and its optical properties

International Nuclear Information System (INIS)

Uchida, Hiroshi; Patel, Mehul N.; May, R. Alan; Gupta, Gaurav; Stevenson, Keith J.; Johnston, Keith P.

2010-01-01

Highly ordered mesoporous titanium dioxide (titania, TiO 2 ) thin films on indium-tin-oxide (ITO) coated glass were prepared via a Pluronic (P123) block copolymer template and a hydrophilic TiO 2 buffer layer. The contraction of the 3D hexagonal array of P123 micelles upon calcination merges the titania domains on the TiO 2 buffer layer to form mesoporous films with a mesochannel diameter of approximately 10 nm and a pore-to-pore distance of 10 nm. The mesoporous titania films on TiO 2 -buffered ITO/glass featured an inverse mesospace with a hexagonally-ordered structure, whereas the films formed without a TiO 2 buffer layer had a disordered microstructure with submicron cracks because of non-uniform water condensation on the hydrophobic ITO/glass surface. The density of the mesoporous film was 83% that of a bulk TiO 2 film. The optical band gap of the mesoporous titania thin film was approximately 3.4 eV, larger than that for nonporous anatase TiO 2 (∼ 3.2 eV), suggesting that the nanoscopic grain size leads to an increase in the band gap due to weak quantum confinement effects. The ability to form highly-ordered mesoporous titania films on electrically conductive and transparent substrates offers the potential for facile fabrication of high surface area semiconductive films with small diffusion lengths for optoelectronics applications.

Electrochemical performance of mixed crystallographic phase nanotubes and nanosheets of titania and titania-carbon/silver composites for lithium-ion batteries

International Nuclear Information System (INIS)

Das, Shyamal K.; Bhattacharyya, Aninda J.

2011-01-01

Highlights: → Carbon wired TiO 2 nanotubes as anode for lithium ion batteries. → Mixed phase nanotubes show higher energy and power density than titania nanosheets. → Lithium storage and phase stabilization influenced by morphology of carbon coating. - Abstract: The role of homogeneity in ex situ grown conductive coatings and dimensionality in the lithium storage properties of TiO 2 is discussed here. TiO 2 nanotube and nanosheet comprising of mixed crystallographic phases of anatase and TiO 2 (B) have been synthesized by an optimized hydrothermal method. Surface modifications of TiO 2 nanotube are realized via coating the nanotube with Ag nanoparticles and amorphous carbon. The first discharge cycle capacity (at current rate = 10 mA g -1 ) for TiO 2 nanotube and nanosheet were 355 mAh g -1 and 225 mAh g -1 , respectively. The conductive surface coating stabilized the titania crystallographic structure during lithium insertion-deinsertion processes via reduction in the accessibility of lithium ions to the trapping sites. The irreversible capacity is beneficially minimized from 110 mAh g -1 for TiO 2 nanotubes to 96 mAh g -1 and 57 mAh g -1 respectively for Ag and carbon modified TiO 2 nanotubes. The homogeneously coated amorphous carbon over TiO 2 renders better lithium battery performance than randomly distributed Ag nanoparticles coated TiO 2 due to efficient hopping of electrons.

The detection of improvised nonmilitary peroxide based explosives using a titania nanotube array sensor

International Nuclear Information System (INIS)

Banerjee, Subarna; Mohapatra, Susanta K; Misra, Mano; Mishra, Indu B

2009-01-01

There is a critical need to develop an efficient, reliable and highly selective sensor for the detection of improvised nonmilitary explosives. This paper describes the utilization of functionalized titania nanotube arrays for sensing improvised organic peroxide explosives such as triacetone triperoxide (TATP). TATP forms complexes with titania nanotube arrays (prepared by anodization and sensitized with zinc ions) and thus affects the electron state of the nanosensing device, which is signaled as a change in current of the overall nanotube material. The response is rapid and a signal of five to eight orders of magnitude is observed. These nanotube array sensors can be used as hand-held miniaturized devices as well as large scale portable units for military and homeland security applications.

The detection of improvised nonmilitary peroxide based explosives using a titania nanotube array sensor.

Science.gov (United States)

Banerjee, Subarna; Mohapatra, Susanta K; Misra, Mano; Mishra, Indu B

2009-02-18

There is a critical need to develop an efficient, reliable and highly selective sensor for the detection of improvised nonmilitary explosives. This paper describes the utilization of functionalized titania nanotube arrays for sensing improvised organic peroxide explosives such as triacetone triperoxide (TATP). TATP forms complexes with titania nanotube arrays (prepared by anodization and sensitized with zinc ions) and thus affects the electron state of the nanosensing device, which is signaled as a change in current of the overall nanotube material. The response is rapid and a signal of five to eight orders of magnitude is observed. These nanotube array sensors can be used as hand-held miniaturized devices as well as large scale portable units for military and homeland security applications.

PS buildings : reinforced concrete structure for shielding "bridge" pillar

CERN Multimedia

CERN PhotoLab

1956-01-01

The PS ring traverses the region between the experimental halls South and North (buildings Nos 150 and 151) under massive bridge-shaped concrete beams. This pillar stands at the S-W end of the structure.

Phosphonium modified clay/polyimide nanocomposites

International Nuclear Information System (INIS)

Ceylan, Hatice; Çakmakçi, Emrah; Beyler-Çiǧil, Asli; Kahraman, Memet Vezir

2014-01-01

In this study, octyltriphenylphosphonium bromide [OTPP-Br] was prepared from the reaction of triphenylphosphine and 1 -bromooctane. The modification of clay was done by ion exchange reaction using OTPP-Br in water medium. Poly(amic acid) was prepared from the reaction of 3,3',4,4'-Benzophenonetetracarboxylic dianhydride (BTDA) and 4,4'-Oxydianiline (ODA). Polyimide(PI)/clay hybrids were prepared by blending of poly(amic acid) and organically modified clay as a type of layered clays. The morphology of the Polyimide/ phosphonium modified clay hybrids was characterized by scanning electron microscopy (SEM). Chemical structures of polyimide and Polyimide/ phosphonium modified clay hybrids were characterized by FTIR. SEM and FTIR results showed that the Polyimide/ phosphonium modified clay hybrids were successfully prepared. Thermal properties of the Polyimide/ phosphonium modified clay hybrids were characterized by thermogravimetric analysis (TGA)

Comparison of the cohesive and delamination fatigue properties of atomic-layer-deposited alumina and titania ultrathin protective coatings deposited at 200 °C

Directory of Open Access Journals (Sweden)

Farzad Sadeghi-Tohidi

2014-01-01

Full Text Available The fatigue properties of ultrathin protective coatings on silicon thin films were investigated. The cohesive and delamination fatigue properties of 22 nm-thick atomic-layered-deposited (ALD titania were characterized and compared to that of 25 nm-thick alumina. Both coatings were deposited at 200 °C. The fatigue rates are comparable at 30 °C, 50% relative humidity (RH while they are one order of magnitude larger for alumina compared to titania at 80 °C, 90% RH. The improved fatigue performance is believed to be related to the improved stability of the ALD titania coating with water compared to ALD alumina, which may in part be related to the fact that ALD titania is crystalline, while ALD alumina is amorphous. Static fatigue crack nucleation and propagation was not observed. The underlying fatigue mechanism is different from previously documented mechanisms, such as stress corrosion cracking, and appears to result from the presence of compressive stresses and a rough coating–substrate interface.

PVA assisted low temperature anatase to rutile phase transformation (ART) and properties of titania nanoparticles

International Nuclear Information System (INIS)

Mondal, Shrabani; Madhuri, Rashmi; Sharma, Prashant K.

2015-01-01

Anatase to rutile phase transformation (ART) of titania nanoparticles is observed at very low temperature (180 °C) just by introducing polyvinyl alcohol (PVA) during co-precipitation followed by hydrothermal synthesis. The detailed investigations pertaining to the structural, optical and electrochemical properties of the nanosized titania and titania/PVA nanohybrid has been carried out. The crystallite size and crystal structure is confirmed using X-ray diffraction (XRD). Transmission electron microscopic (TEM) image reveals formation of spherical NPs in both the cases. Identification of functional groups is done using Fourier transform infrared spectroscopy (FTIR). The photoluminescence studies showed that emission slightly shifts towards higher wavelength side with remarkable decrease in intensity for TiO 2 /PVA nanocomposite (rutile samples). The remarkable decrease in PL intensity in TiO 2 /PVA nanocomposite (rutile samples) is explained considering the surface passivation during growth process. Ion transportation is monitored via Cyclic voltammetric (CV) and Electrochemical Impedance Spectroscopy (EIS) measurements. A significant enhancement of peak cathodic current in case of nanocomposite modified electrode is observed. It is assumed that TiO 2 /PVA (rutile) nanoparticles provided the conducting path for the electrons and hence enhanced the electrochemical reaction. - Graphical abstract: Present work reports anatase to rutile phase transformation (ART) of titania nanoparticles at very low temperature (180 °C) just by introducing polyvinyl alcohol (PVA) during co-precipitation followed by hydrothermal synthesis. - Highlights: • Low temperature phase transformation of TiO 2 nanoparticles from anatase to rutile. • Role of PVA in phase transformation. • Synthesis of spherical shaped uniformly distributed PVA capped TiO 2 NPs. • Explained the charge transfer process among anatase to rutile phase transformation via luminescence studies. • Enhanced

Titania may produce abiotic oxygen atmospheres on habitable exoplanets

OpenAIRE

Norio Narita; Takafumi Enomoto; Shigeyuki Masaoka; Nobuhiko Kusakabe

2015-01-01

The search for habitable exoplanets in the Universe is actively ongoing in the field of astronomy. The biggest future milestone is to determine whether life exists on such habitable exoplanets. In that context, oxygen in the atmosphere has been considered strong evidence for the presence of photosynthetic organisms. In this paper, we show that a previously unconsidered photochemical mechanism by titanium (IV) oxide (titania) can produce abiotic oxygen from liquid water under near ultraviolet ...

Surface displacements and pillar stresses associated with nuclear waste disposal in salt

International Nuclear Information System (INIS)

Hardy, M.P.; St John, C.M.

1977-01-01

A numerical model for regional analysis of stresses and displacement, resulting from heat generating waste placement in underground salt excavations, is presented. The model, which is an extension of that described by McClain and Starfield (1971), is based upon the displacement discontinuity method of stress analysis. It incorporates an empirical characterization of creep behavior of material on the excavation horizon and accounts for thermally induced stresses and displacements. The versatility of this approach is illustrated by the results of three relatively short simulations of test scale disposal facilities at shallow and greater depths. In addition, a three-dimensional code was used to evaluate the surface displacement history for a full-scale repository. This latter code, a thermoelastic analysis, gives an upper bound for the surface movements. It is concluded that the pillar stresses are the result of a complex non-linear interaction of many variables, and the maximum pillar stress can reach several multiples of the tributory-area pillar stress

Effective coating of titania nanoparticles with alumina via atomic layer deposition

Science.gov (United States)

Azizpour, H.; Talebi, M.; Tichelaar, F. D.; Sotudeh-Gharebagh, R.; Guo, J.; van Ommen, J. R.; Mostoufi, N.

2017-12-01

Alumina films were deposited on titania nanoparticles via atomic layer deposition (ALD) in a fluidized bed reactor at 180 °C and 1 bar. Online mass spectrometry was used for real time monitoring of effluent gases from the reactor during each reaction cycle in order to determine the optimal dosing time of precursors. Different oxygen sources were used to see which oxygen source, in combination with trimethyl aluminium (TMA), provides the highest alumina growth per cycle (GPC). Experiments were carried out in 4, 7 and 10 cycles using the optimal dosing time of precursors. Several characterization methods, such as high resolution transmission electron microscopy (HRTEM), Brunauer-Emmett-Teller (BET), energy dispersive X-ray spectroscopy (EDX), Fourier transform infrared (FTIR), X-ray diffraction (XRD) and instrumental neutron activation analysis (INAA), were conducted on the products. Formation of the alumina film was confirmed by EDX mapping and EDX line profiling, FTIR and TEM. When using either water or deuterium oxide as the oxygen source, the thickness of the alumina film was greater than that of ozone. The average GPC measured by TEM for the ALD of TMA with water, deuterium oxide and ozone was about 0.16 nm, 0.15 nm and 0.11 nm, respectively. The average GPC calculated using the mass fraction of aluminum from INAA was close to those measured from TEM images. Excess amounts of precursors lead to a higher average growth of alumina film per cycle due to insufficient purging time. XRD analysis demonstrated that amorphous alumina was coated on titania nanoparticles. This amorphous layer was easily distinguished from the crystalline core in the TEM images. Decrease in the photocatalytic activity of titania nanoparticles after alumina coating was confirmed by measuring degradation of Rhodamine B by ultraviolet irradiation.

Estimating the coordinates of pillars and posts in the parking lots for intelligent parking assist system

Science.gov (United States)

Choi, Jae Hyung; Kuk, Jung Gap; Kim, Young Il; Cho, Nam Ik

2012-01-01

This paper proposes an algorithm for the detection of pillars or posts in the video captured by a single camera implemented on the fore side of a room mirror in a car. The main purpose of this algorithm is to complement the weakness of current ultrasonic parking assist system, which does not well find the exact position of pillars or does not recognize narrow posts. The proposed algorithm is consisted of three steps: straight line detection, line tracking, and the estimation of 3D position of pillars. In the first step, the strong lines are found by the Hough transform. Second step is the combination of detection and tracking, and the third is the calculation of 3D position of the line by the analysis of trajectory of relative positions and the parameters of camera. Experiments on synthetic and real images show that the proposed method successfully locates and tracks the position of pillars, which helps the ultrasonic system to correctly locate the edges of pillars. It is believed that the proposed algorithm can also be employed as a basic element for vision based autonomous driving system.

Heterogeneous photo-Fenton decolorization of Orange II over Al-pillared Fe-smectite: Response surface approach, degradation pathway, and toxicity evaluation

Energy Technology Data Exchange (ETDEWEB)

Li, Huiyuan; Li, Yanli [Department of Environmental Engineering, Wuhan University, Wuhan 430079 (China); Xiang, Luojing [Department of Environmental Engineering, Wuhan University, Wuhan 430079 (China); Université de Poitiers, UMR CNRS 7285, IC2MP, ENSIP, B1, 1 rue Marcel Doré, TSA 41105, Poitiers 86073 Cedex 9 (France); Huang, Qianqian; Qiu, Juanjuan [Department of Environmental Engineering, Wuhan University, Wuhan 430079 (China); Zhang, Hui, E-mail: eeng@whu.edu.cn [Department of Environmental Engineering, Wuhan University, Wuhan 430079 (China); Sivaiah, Matte Venkata; Baron, Fabien; Barrault, Joel; Petit, Sabine [Université de Poitiers, UMR CNRS 7285, IC2MP, ENSIP, B1, 1 rue Marcel Doré, TSA 41105, Poitiers 86073 Cedex 9 (France); Valange, Sabine, E-mail: sabine.valange@univ-poitiers.fr [Université de Poitiers, UMR CNRS 7285, IC2MP, ENSIP, B1, 1 rue Marcel Doré, TSA 41105, Poitiers 86073 Cedex 9 (France)

2015-04-28

Highlights: • Al-pillared Fe-smectite was synthesized and used as the photo-Fenton catalyst. • Response surface methodology was used to study the effects of reaction parameters. • The main intermediate products were identified by GC–MS technique. • A possible degradation pathway of Orange II was proposed. • All the generated products of Orange II were less toxic than the original dye. - Abstract: A ferric smectite clay material was synthesized and further intercalated with Al{sub 2}O{sub 3} pillars for the first time with the aim of evaluating its ability to be used as heterogeneous catalyst for the photo-Fenton decolorization of azo dye Orange II. UV irradiation was found to enhance the activity of the catalyst in the heterogeneous photo-Fenton process. Catalyst loading of 0.5 g/L and hydrogen peroxide concentration of 13.5 mM yielded a remarkable color removal, accompanied by excellent catalyst stability. The decolorization of Orange II followed the pseudo-first-order kinetics for initial dye concentrations from 20 to 160 mg/L. The central composite design (CCD) based on the response surface methodology (RSM) was applied to evaluate the effects of several operating parameters, namely initial pH, catalyst loading and hydrogen peroxide concentration, on the decolorization efficiency. The RSM model was derived and the response surface plots were developed based on the results. Moreover, the main intermediate products were separated and identified using gas chromatography–mass spectrometry (GC–MS) and a possible degradation pathway was proposed accordingly. The acute toxicity experiments illustrated that the Daphniamagna immobilization rate continuously decreased during 150 min reaction, indicating that the effluent was suitable for sequential biological treatment.

Common clay and shale

Science.gov (United States)

Virta, R.L.

2000-01-01

Part of the 1999 Industrial Minerals Review. The clay and shale market in 1999 is reviewed. In the U.S., sales or use of clay and shale increased from 26.4 million st in 1998 to 27.3 million st in 1999, with an estimated 1999 value of production of $143 million. These materials were used to produce structural clay products, lightweight aggregates, cement, and ceramics and refractories. Production statistics for clays and shales and for their uses in 1999 are presented.

Effects of modified Clay on the morphology and thermal stability of PMMA/clay nanocomposites

International Nuclear Information System (INIS)

Tsai, Tsung-Yen; Lin, Mei-Ju; Chuang, Yi-Chen; Chou, Po-Chiang

2013-01-01

The potential to improve the mechanical, thermal, and optical properties of poly(methyl methacrylate) (PMMA)/clay nanocomposites prepared with clay containing an organic modifier was investigated. Pristine sodium montmorillonite clay was modified using cocoamphodipropionate, which absorbs UVB in the 280–320 nm range, via ion exchange to enhance the compatibility between the clay platelets and the methyl methacrylate polymer matrix. PMMA/clay nanocomposites were synthesized via in situ free-radical polymerization. Three types of clay with various cation-exchange capacities (CEC) were used as inorganic layered materials in these organic–inorganic hybrid nanocomposites: CL42, CL120, and CL88 with CEC values of 116, 168, and 200 meq/100 g of clay, respectively. We characterized the effects of the organoclay dispersion on UV resistance, effectiveness as an O 2 gas barrier, thermal stability, and mechanical properties of PMMA/clay nanocomposites. Gas permeability analysis demonstrated the excellent gas barrier properties of the nanocomposites, consistent with the intercalated or exfoliated morphologies observed. The optical properties were assessed using UV–Visible spectroscopy, which revealed that these materials have good optical clarity, UV resistance, and scratch resistance. The effect of the dispersion capability of organoclay on the thermal properties of PMMA/clay nanocomposites was investigated by thermogravimetric analysis and differential scanning calorimetry; these analyses revealed excellent thermal stability of some of the modified clay nanocomposites. - Highlights: ► We control the dispersion morphology by protonation of K2 into the clay. ► The CL120 and CL88, with the higher CEC, are more random intercalated by K2. ► We report these materials have good optical clarity, and UV resistance

Photocatalytic Activity and Characterization of Carbon-Modified Titania for Visible-Light-Active Photodegradation of Nitrogen Oxides

Directory of Open Access Journals (Sweden)

Chun-Hung Huang

2012-01-01

Full Text Available A variety of carbon-modified titania powders were prepared by impregnation method using a commercial available titania powder, Hombikat UV100, as matrix material while a range of alcohols from propanol to hexanol were used as precursors of carbon sources. Rising the carbon number of alcoholic precursor molecule, the modified titania showed increasing visible activities of NOx photodegradation. The catalyst modified with cyclohexanol exhibited the best activities of 62%, 62%, 59%, and 54% for the total NOx removal under UV, blue, green, and red light irradiation, respectively. The high activity with long wavelength irradiation suggested a good capability of photocatalysis in full visible light spectrum. Analysis of UV-visible spectrum indicated that carbon modification promoted visible light absorption and red shift in band gap. XPS spectroscopic analysis identified the existence of carbonate species (C=O, which increased with the increasing carbon number of precursor molecule. Photoluminescence spectra demonstrated that the carbonate species suppressed the recombination rate of electron-hole pair. As a result, a mechanism of visible-light-active photocatalyst was proposed according to the formation of carbonate species on carbon-modified TiO2.

Selective Clay Placement Within a Silicate-Clay Epoxy Blend Nanocomposite

Science.gov (United States)

Miller, Sandi G (Inventor)

2013-01-01

A clay-epoxy nanocomposite may be prepared by dispersing a layered clay in an alkoxy epoxy, such as a polypropylene oxide based epoxide before combining the mixture with an aromatic epoxy to improve the nanocomposite's thermal and mechanical properties.

Clay nanoparticles for regenerative medicine and biomaterial design: A review of clay bioactivity.

Science.gov (United States)

Mousa, Mohamed; Evans, Nicholas D; Oreffo, Richard O C; Dawson, Jonathan I

2018-03-01

Clay nanoparticles, composites and hydrogels are emerging as a new class of biomaterial with exciting potential for tissue engineering and regenerative medicine applications. Clay particles have been extensively explored in polymeric nanocomposites for self-assembly and enhanced mechanical properties as well as for their potential as drug delivery modifiers. In recent years, a cluster of studies have explored cellular interactions with clay nanoparticles alone or in combination with polymeric matrices. These pioneering studies have suggested new and unforeseen utility for certain clays as bioactive additives able to enhance cellular functions including adhesion, proliferation and differentiation, most notably for osteogenesis. This review examines the recent literature describing the potential effects of clay-based nanomaterials on cell function and examines the potential role of key clay physicochemical properties in influencing such interactions and their exciting possibilities for regenerative medicine. Copyright © 2018 Elsevier Ltd. All rights reserved.

Thixotropic Properties of Latvian Clays

OpenAIRE

Lakevičs, Vitālijs; Stepanova, Valentīna; Ruplis, Augusts

2015-01-01

This research studies Latvia originated Devon (Tūja, Skaņkalne), quaternary (Ceplīši), Jurassic, (Strēļi) and Triassic (Vadakste) deposit clays as well as Lithuania originated Triassic (Akmene) deposit clays. Thixotropic properties of clay were researched by measuring relative viscosity of clay in water suspensions. Relative viscosity is measured with a hopper method. It was detected that, when concentration of suspension is increased, clay suspension’s viscosity also increases. It happens un...

Reverse engineering of B-pillar with 3D optical scanning for manufacturing of non-uniform thickness part

Directory of Open Access Journals (Sweden)

Islam Md. Tasbirul

2017-01-01

Full Text Available This paper presents reverse engineering (RE of a complex automobile structural part, B-pillar. As a major part of the automobile body-in white (BiW, B-pillar has substantial opportunity for weight reduction by introducing variable thickness across its sections. To leverage such potential, an existing B-pillar was reverse engineered with a 3D optical scanner and computer aided design (CAD application. First, digital data (i.e. in meshes of exiting B-pillar was obtained by the scanner, and subsequently, this information was utilized in developing a complete 3D CAD model. CATIA V5 was used in the modeling where some of the essential work benches were “Digitized Shape Editor”, “Quick Surface Reconstruction”, “Wireframe and Surface Design”, “Freestyle”, “Generation Shape Design” and “Part design”. In the final CAD design, five different thicknesses were incorporated successfully in order to get a B-pillar with non-uniform sections. This research opened opportunities for thickness optimization and mold tooling design in real time manufacturing.

Degradation of organophosphorus pesticide parathion methyl on nanostructured titania-iron mixed oxides

Czech Academy of Sciences Publication Activity Database

Henych, Jiří; Štengl, Václav; Slušná, Michaela; Matys Grygar, Tomáš; Janoš, P.; Kuráň, P.; Šťastný, M.

2015-01-01

Roč. 344, JUL (2015), s. 9-16 ISSN 0169-4332 R&D Projects: GA ČR(CZ) GAP106/12/1116 Institutional support: RVO:61388980 Keywords : Titania-iron oxides * Homogeneous hydrolysis * Degradation of organophosphates * Parathion methyl Subject RIV: CA - Inorganic Chemistry Impact factor: 3.150, year: 2015

Plasma sprayed alumina-titania coatings

International Nuclear Information System (INIS)

Steeper, T.J.; Rotolico, A.J.; Nerz, J.E.; Riggs, W.L. II; Varacalle, D.J. Jr.; Wilson, G.C.

1992-01-01

This paper presents an experimental study of the air plasma spraying (APS) of alumina-titania powder using argon-hydrogen working gases. This powder system is being used in the fabrication of heater tubes that emulate nuclear fuel tubes for use in thermal-hydraulic testing. Experiments were conducted using a Taguchi fractional-factorial design parametric study. Operating parameters were varied around the typical spray parameters in a systematic design of experiments in order to display the range of plasma processing conditions and their effect on the resultant coatings. The coatings were characterized by hardness and electrical tests, surface profilometry, image analysis, optical metallography, and x-ray diffraction. Coating qualities are discussed with respect to dielectric strength, hardness, porosity, surface roughness, deposition efficiency, and microstructure. attempts are made to correlate the features of the coatings with the changes in operating parameters

Commercial and home-made nitrogen modified titanias. A short reflection about the advantageous/disadvantageous properties of nitrogen doping in the frame of their applicability

Science.gov (United States)

Pap, Zs.; Mogyorósi, K.; Veréb, G.; Dombi, A.; Hernádi, K.; Danciu, V.; Baia, L.

2014-09-01

As visible light driven photocatalysis became more and more intensively studied, the first commercial products showed up on the market. Simultaneously controversial results appeared in the literature generating an intensive debate regarding the advantages and draw-backs of nitrogen doping of titania. Hence, the present work focuses on two commercially available and four sol-gel made nitrogen modified titania powders regarding their structure and activity. It is demonstrated that the interstitial nitrogen entities “leak out” from the catalysts if the material is irradiated with UV light, while substitutional nitrogen remains stable. However, the latter one was proven to be less important in the photocatalytic point of view. These observations were also valid in the case of sol-gel made nitrogen modified titanias. Furthermore, the results obtained after applying different spectroscopic methods (IR, XPS and DRS) shown that the yellow color of the titanias, does not necessary mean that a successful doping is achieved.

Clay minerals behaviour in thin sandy clay-rich lacustrine turbidites (Lake Hazar, Turkey)

Science.gov (United States)

El Ouahabi, Meriam; Hubert-Ferrari, Aurelia; Lamair, Laura; Hage, Sophie

2017-04-01

Turbidites have been extensively studied in many different areas using cores or outcrop, which represent only an integrated snapshot of a dynamic evolving flow. Laboratory experiments provide the missing relationships between the flow characteristics and their deposits. In particular, flume experiments emphasize that the presence of clay plays a key role in turbidity current dynamics. Clay fraction, in small amount, provides cohesive strength to sediment mixtures and can damp turbulence. However, the degree of flocculation is dependent on factors such as the amount and size of clay particles, the surface of clay particles, chemistry and pH conditions in which the clay particles are dispersed. The present study focuses on thin clayey sand turbidites found in Lake Hazar (Turkey) occurring in stacked thin beds. Depositional processes and sources have been previously studied and three types were deciphered, including laminar flows dominated by cohesion, transitional, and turbulence flow regimes (Hage et al., in revision). For the purpose of determine the clay behavior in the three flow regimes, clay mineralogical, geochemical measurements on the cores allow characterising the turbidites. SEM observations provide further information regarding the morphology of clay minerals and other clasts. The study is particularly relevant given the highly alkaline and saline water of the Hazar Lake. Clay minerals in Hazar Lake sediments include kaolinite (1:1-type), illite and chlorite (2:1-type). Hazar lake water is alkaline having pH around 9.3, in such alkaline environment, a cation-exchange reaction takes place. Furthermore, in saline water (16‰), salts can act as a shield and decrease the repulsive forces between clay particle surfaces. So, pH and salt content jointly impact the behaviour of clays differently. Since the Al-faces of clay structures have a negative charge in basic solutions. At high pH, all kaolinite surfaces become negative-charged, and then kaolinite

Hybrid Dye-Sensitized Solar Cells Consisting of Double Titania Layers for Harvesting Light with Wide Range of Wavelengths

Science.gov (United States)

Sadamasu, Kengo; Inoue, Takafumi; Ogomi, Yuhei; Pandey, Shyam S.; Hayase, Shuzi

2011-02-01

We report a hybrid dye-sensitized solar cell consisting of double titania layers (top and bottom layers) stained with two dyes. A top layer fabricated on a glass was mechanically pressed with a bottom layer fabricated on a glass cloth. The glass cloth acts as a supporter of a porous titania layer as well as a holder of electrolyte. The incident photon to current efficiency (IPCE) curve had two peaks corresponding to those of the two dyes, which demonstrates that electrons are collected from both the top and bottom layers.

Fe(0)-clays interactions at 90°C under anoxic conditions: a comparative study between clay fraction of Callovo-Oxfordian and other purified clays

International Nuclear Information System (INIS)

Rivard, C.; Pelletier, M.; Villieras, F.; Barres, O.; Galmiche, M.; Ghanbaja, J.; Kohler, A.; Michau, N.

2010-01-01

Document available in extended abstract form only. In the context of the geological disposal of high-level radioactive waste it is of prime importance to understand the interactions between the saturated clay formation and steel containers. This can be achieved through an in-depth analysis of iron-clay interactions. Previous studies on the subject investigated the influence of solid/liquid ratio, iron/clay ratio, temperature and reaction time. The aim of the present study is to explain Callovo-Oxfordian-Fe(0) interactions by determining the role of each mineral phases present in the Callovo-Oxfordian (clay minerals, quartz, carbonates and pyrite) on the mechanisms of interaction between metal iron and clay particles. In that context, it is especially important to understand in detail the influence of clay nature and to obtain some insight about the relationships between interaction mechanisms at the molecular scale and crystallographic properties (particle size, TO or TOT layers, amount of edge faces...). The influence of the combination of different clays and the addition of other minerals must also be studied. In a first step, the Callovo-Oxfordian argillite from the Andra's underground research laboratory was purified to extract the clay fraction (illite, illite-smectite, kaolinite and chlorite). Batch experiments were carried out in anoxic conditions at 90 deg. C in the presence of background electrolyte (NaCl 0.02 M.L -1 , CaCl 2 0.04 M.L -1 ) for durations of one, three or nine months in the presence of metallic iron powder. Experiments without iron were used as control. The iron/clay ratio was fixed at 1/3 with a solid/liquid ratio of 1/20. The above mentioned experiments were also carried out in parallel on other purified clays: two smectites (Georgia bentonite and SWy2 from the Clay Minerals Society), one illite (illite du Puy) and one kaolinite (KGa2, from the Clay Minerals society). At the end of the experiments, solid and liquid phases were

Euroclay 95. Clays and clay materials sciences. Book of abstracts

Energy Technology Data Exchange (ETDEWEB)

Elsen, A; Grobet, P; Keung, M; Leeman, H; Schoonheydt, R; Toufar, H [eds.

1995-08-20

The document contains the abstracts of the invited lecturers (18) and posters (247) presented at EUROCLAY `95. Clays and clay materials sciences. 13 items (4 from the invited lecturers and 12 from posters) have been considered within the INIS Subject Scope and indexed separately.

Euroclay 95. Clays and clay materials sciences. Book of abstracts

International Nuclear Information System (INIS)

Elsen, A.; Grobet, P.; Keung, M.; Leeman, H.; Schoonheydt, R.; Toufar, H.

1995-01-01

The document contains the abstracts of the invited lecturers (18) and posters (247) presented at EUROCLAY '95. Clays and clay materials sciences. 13 items (4 from the invited lecturers and 12 from posters) have been considered within the INIS Subject Scope and indexed separately

Clay particles as binder for earth buildings materials: a fresh look into rheology of dense clay suspensions

Science.gov (United States)

Landrou, Gnanli; Brumaud, Coralie; Habert, Guillaume

2017-06-01

In the ceramic industry and in many sectors, clay minerals are widely used. In earthen construction technique, clay plays a crucial role in the processing. The purpose of this research is to understand and modify the clay properties in earth material to propose an innovative strategy to develop a castable earth-based material. To do so, we focused on the modification of clay properties at fresh state with inorganic additives. As the rheological behaviour of clays is controlled by their surface charge, the addition of phosphate anion allows discussing deep the rheology of concentrated clay suspensions. We highlighted the thixotropic and shear thickening behaviour of a dispersed kaolinite clay suspensions. Indeed, by adding sodium hexametaphosphate the workability of clay paste increases and the behaviour is stable during time after a certain shear is applied. Moreover, we stress that the aging and the shift in critical strain in clay system are due to the re-arrangement of clay suspension and a decrease of deformation during time. The understanding of both effect: thixotropy and aging are crucial for better processing of clay-based material and for self-compacting clay concrete. Yet, studies need to pursue to better understand the mechanism.

Thermal stability of titanate nanorods and titania nanowires formed from titanate nanotubes by heating

Czech Academy of Sciences Publication Activity Database

Brunátová, T.; Matěj, Z.; Oleynikov, P.; Vesely, J.; Danis, S.; Popelková, Daniela; Kuzel, R.

2014-01-01

Roč. 98, December (2014), s. 26-36 ISSN 1044-5803 Institutional support: RVO:61389013 Keywords : titania nanowires * titanate nanorods * X-ray diffraction Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.845, year: 2014

Numerical Simulations of Pillar Structured Solid State Thermal Neutron Detector Efficiency and Gamma Discrimination

Energy Technology Data Exchange (ETDEWEB)

Conway, A; Wang, T; Deo, N; Cheung, C; Nikolic, R

2008-06-24

This work reports numerical simulations of a novel three-dimensionally integrated, {sup 10}boron ({sup 10}B) and silicon p+, intrinsic, n+ (PIN) diode micropillar array for thermal neutron detection. The inter-digitated device structure has a high probability of interaction between the Si PIN pillars and the charged particles (alpha and {sup 7}Li) created from the neutron - {sup 10}B reaction. In this work, the effect of both the 3-D geometry (including pillar diameter, separation and height) and energy loss mechanisms are investigated via simulations to predict the neutron detection efficiency and gamma discrimination of this structure. The simulation results are demonstrated to compare well with the measurement results. This indicates that upon scaling the pillar height, a high efficiency thermal neutron detector is possible.

Strength Reduction of Coal Pillar after CO2 Sequestration in Abandoned Coal Mines

Directory of Open Access Journals (Sweden)

Qiuhao Du

2017-02-01

Full Text Available CO2 geosequestration is currently considered to be the most effective and economical method to dispose of artificial greenhouse gases. There are a large number of coal mines that will be scrapped, and some of them are located in deep formations in China. CO2 storage in abandoned coal mines will be a potential option for greenhouse gas disposal. However, CO2 trapping in deep coal pillars would induce swelling effects of coal matrix. Adsorption-induced swelling not only modifies the volume and permeability of coal mass, but also causes the basic physical and mechanical properties changing, such as elastic modulus and Poisson ratio. It eventually results in some reduction in pillar strength. Based on the fractional swelling as a function of time and different loading pressure steps, the relationship between volumetric stress and adsorption pressure increment is acquired. Eventually, this paper presents a theory model to analyze the pillar strength reduction after CO2 adsorption. The model provides a method to quantitatively describe the interrelation of volumetric strain, swelling stress, and mechanical strength reduction after gas adsorption under the condition of step-by-step pressure loading and the non-Langmuir isothermal model. The model might have a significantly important implication for predicting the swelling stress and mechanical behaviors of coal pillars during CO2 sequestration in abandoned coal mines.

Planning maximum extraction of a safety pillar in the Most surface mine

Energy Technology Data Exchange (ETDEWEB)

Helis, P; Hess, L; Kubiznak, K [SHR - Banske Projekty, Teplice (Czechoslovakia)

1990-11-01

Discusses planned coal surface mining in the Most mine in the area of the Hnevin safety pillar with coal reserves amounting to about 7.5 Mt. The following aspects are evaluated: coal reserves and their distribution in the pillar, coal seam thickness and dip angles, water conditions, water influx rates, mechanical properties of the overburden and strata situated in the seam floor, slope stability and hazards of landslides, effects of water influx on landslide hazards, types of bucket wheel excavators used for overburden removal and mining, types of belt conveyors used for mine haulage, stackers, position of mining equipment in the mine. A scheme developed by Banske Projekty Teplice for partial extraction of the safety pillar would result in extraction of 4.5 Mt coal. About 1.7 Mt coal would be left in a safety coal layer about 10.0 m thick situated in the floor in zones with landslide hazards. KU 300 bucket wheel excavators, belt conveyors 1,200 mm wide and ZP 2,500 stackers would be used. 4 refs.

Controlling drug delivery kinetics from mesoporous titania thin films by pore size and surface energy

Directory of Open Access Journals (Sweden)

Karlsson J

2015-07-01

Full Text Available Johan Karlsson, Saba Atefyekta, Martin Andersson Department of Chemical and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden Abstract: The osseointegration capacity of bone-anchoring implants can be improved by the use of drugs that are administrated by an inbuilt drug delivery system. However, to attain superior control of drug delivery and to have the ability to administer drugs of varying size, including proteins, further material development of drug carriers is needed. Mesoporous materials have shown great potential in drug delivery applications to provide and maintain a drug concentration within the therapeutic window for the desired period of time. Moreover, drug delivery from coatings consisting of mesoporous titania has shown to be promising to improve healing of bone-anchoring implants. Here we report on how the delivery of an osteoporosis drug, alendronate, can be controlled by altering pore size and surface energy of mesoporous titania thin films. The pore size was varied from 3.4 nm to 7.2 nm by the use of different structure-directing templates and addition of a swelling agent. The surface energy was also altered by grafting dimethylsilane to the pore walls. The drug uptake and release profiles were monitored in situ using quartz crystal microbalance with dissipation (QCM-D and it was shown that both pore size and surface energy had a profound effect on both the adsorption and release kinetics of alendronate. The QCM-D data provided evidence that the drug delivery from mesoporous titania films is controlled by a binding–diffusion mechanism. The yielded knowledge of release kinetics is crucial in order to improve the in vivo tissue response associated to therapeutic treatments. Keywords: mesoporous titania, controlled drug delivery, release kinetics, alendronate, QCM-D

Clay particles as binder for earth buildings materials: a fresh look into rheology of dense clay suspensions

Directory of Open Access Journals (Sweden)

Landrou Gnanli

2017-01-01

Full Text Available In the ceramic industry and in many sectors, clay minerals are widely used. In earthen construction technique, clay plays a crucial role in the processing. The purpose of this research is to understand and modify the clay properties in earth material to propose an innovative strategy to develop a castable earth-based material. To do so, we focused on the modification of clay properties at fresh state with inorganic additives. As the rheological behaviour of clays is controlled by their surface charge, the addition of phosphate anion allows discussing deep the rheology of concentrated clay suspensions. We highlighted the thixotropic and shear thickening behaviour of a dispersed kaolinite clay suspensions. Indeed, by adding sodium hexametaphosphate the workability of clay paste increases and the behaviour is stable during time after a certain shear is applied. Moreover, we stress that the aging and the shift in critical strain in clay system are due to the re-arrangement of clay suspension and a decrease of deformation during time. The understanding of both effect: thixotropy and aging are crucial for better processing of clay-based material and for self-compacting clay concrete. Yet, studies need to pursue to better understand the mechanism.

Synthesis of templated carbons starting from clay and clay-derived zeolites for hydrogen storage applications

CSIR Research Space (South Africa)

Musyoka, Nicholas M

2014-10-01

Full Text Available 57 58 59 60 For Peer Review 1 Synthesis of templated carbons starting from clay and clay-derived zeolites for hydrogen storage applications N. M. Musyoka1*, J. Ren1, H. W. Langmi1, D. E. C. Rogers1, B. C. North1, M. Mathe1 and D. Bessarabov2... clear (filtered) extract of cloisite clay, SNC for zeolite from unfiltered cloisite clay extract and SBC for zeolite from unfiltered South African bentonite clay extract. Furfuryl alcohol (Sigma Aldrich, C5H6O2, 98%) and Ethylene gas were used...

Effect of Mn doped-titania on the activity of metallocene catalyst by in situ ethylene polymerization

KAUST Repository

Abdul Kaleel, S. H.

2012-09-01

Ethylene polymerization was carried out using highly active metallocene catalysts (Cp 2ZrCl 2 and Cp 2TiCl 2) in combination with methylalumoxane. Titanium(IV) oxide containing 1% Mn as dopant was used as nanofillers. The influence of filler concentration, reaction temperature and pressure on the catalytic activity and polymer properties was investigated. There was a fourfold increase in the activity of zirconocene catalyst by addition of doped-titania. The morphology indicates that the doped-titania nanoparticles have a nucleus effect on the polymerization and caused a homogeneous PE shell around them. The optimum condition for polymerization was found to be 30°C. © 2012 The Korean Society of Industrial and Engineering Chemistry.

Improvement of thermoelectric properties induced by uniquely ordered lattice field in Bi2Se0.5Te2.5 pillar array

International Nuclear Information System (INIS)

Tan, Ming; Hao, Yanming; Wang, Gangzhi

2014-01-01

In this study, it was found that uniquely ordered lattice field favors transport of carriers but hinder that of phonons. The n-Bi 2 Se 0.5 Te 2.5 pillar array film was successfully achieved by a simple ion beam assisted deposition technique. This oriented pillar array structure is clear with pillar diameter of about 30 nm, exhibiting a uniquely ordered lattice field. The properties of the ordered Bi 2 Se 0.5 Te 2.5 pillar array were greatly enhanced in comparison with those of the ordinary film. The Bi 2 Se 0.5 Te 2.5 pillar array with a thermoelectric dimensionless figure-of-merit ZT=1.28 was obtained at room temperature. The in-plane transport mechanisms of the ordered pillar array and the ordinary structures, lattice field model, are proposed and investigated. The specially ordered lattice field is the main reason for the properties enhancement observed in the Bi 2 Se 0.5 Te 2.5 film. Introduction of such ordered lattice field into TE films is therefore a very promising approach. - Graphical abstract: In this study, it was found that uniquely ordered lattice field favors transport of carriers but hinder that of phonons. The Bi 2 Se 0.5 Te 2.5 pillar array film with a thermoelectric dimensionless figure-of-merit ZT=1.28 was obtained at room temperature. The in-plane transport mechanisms of the ordered pillar array and the ordinary structures, the lattice field model, are proposed and investigated. The specially ordered lattice field is the main reason for the properties enhancement observed in the Bi 2 Se 0.5 Te 2.5 pillar array. Introduction of such uniquely ordered lattice field into TE films is therefore a very promising approach. In (a) TEM and (b) HRTEM images of the ordered Bi 2 Se 0.5 Te 2.5 column array. - Highlights: • Uniquely ordered Bi 2 Se 0.5 Te 2.5 pillar array was achieved by an IBAD method. • The pillar array with an ordered lattice field exhibits attractive TE property. • The transport mechanism of such ordered pillar array is proposed and

Charge transport in nanoscale vertical organic semiconductor pillar devices

NARCIS (Netherlands)

Wilbers, J.G.E.; Xu, B.; Bobbert, P.A.; de Jong, M.P.; van der Wiel, W.G.

2017-01-01

We report charge transport measurements in nanoscale vertical pillar structures incorporating ultrathin layers of the organic semiconductor poly(3-hexylthiophene) (P3HT). P3HT layers with thickness down to 5 nm are gently top-contacted using wedging transfer, yielding highly reproducible, robust

Aespoe Pillar Stability Experiment. Final coupled 3D thermo-mechanical modeling. Preliminary particle mechanical modeling

International Nuclear Information System (INIS)

Wanne, Toivo; Johansson, Erik; Potyondy, David

2004-02-01

SKB is planning to perform a large-scale pillar stability experiment called APSE (Aespoe Pillar Stability Experiment) at Aespoe HRL. The study is focused on understanding and control of progressive rock failure in hard crystalline rock and damage caused by high stresses. The elastic thermo-mechanical modeling was carried out in three dimensions because of the complex test geometry and in-situ stress tensor by using a finite-difference modeling software FLAC3D. Cracking and damage formation were modeled in the area of interest (pillar between two large scale holes) in two dimensions by using the Particle Flow Code (PFC), which is based on particle mechanics. FLAC and PFC were coupled to minimize the computer resources and the computing time. According to the modeling the initial temperature rises from 15 deg C to about 65 deg C in the pillar area during the heating period of 120 days. The rising temperature due to thermal expansion induces stresses in the pillar area and after 120 days heating the stresses have increased about 33% from the excavation induced maximum stress of 150 MPa to 200 MPa in the end of the heating period. The results from FLAC3D model showed that only regions where the crack initiation stress has exceeded were identified and they extended to about two meters down the hole wall. These could be considered the areas where damage may occur during the in-situ test. When the other hole is pressurized with a 0.8 MPa confining pressure it yields that 5 MPa more stress is needed to damage the rock than without confining pressure. This makes the damaged area in some degree smaller. High compressive stresses in addition to some tensile stresses might induce some AE (acoustic emission) activity in the upper part of the hole from the very beginning of the test and are thus potential areas where AE activities may be detected. Monitoring like acoustic emissions will be measured during the test execution. The 2D coupled PFC-FLAC modeling indicated that

Aespoe Pillar Stability Experiment. Final coupled 3D thermo-mechanical modeling. Preliminary particle mechanical modeling

Energy Technology Data Exchange (ETDEWEB)

Wanne, Toivo; Johansson, Erik; Potyondy, David [Saanio and Riekkola Oy, Helsinki (Finland)

2004-02-01

SKB is planning to perform a large-scale pillar stability experiment called APSE (Aespoe Pillar Stability Experiment) at Aespoe HRL. The study is focused on understanding and control of progressive rock failure in hard crystalline rock and damage caused by high stresses. The elastic thermo-mechanical modeling was carried out in three dimensions because of the complex test geometry and in-situ stress tensor by using a finite-difference modeling software FLAC3D. Cracking and damage formation were modeled in the area of interest (pillar between two large scale holes) in two dimensions by using the Particle Flow Code (PFC), which is based on particle mechanics. FLAC and PFC were coupled to minimize the computer resources and the computing time. According to the modeling the initial temperature rises from 15 deg C to about 65 deg C in the pillar area during the heating period of 120 days. The rising temperature due to thermal expansion induces stresses in the pillar area and after 120 days heating the stresses have increased about 33% from the excavation induced maximum stress of 150 MPa to 200 MPa in the end of the heating period. The results from FLAC3D model showed that only regions where the crack initiation stress has exceeded were identified and they extended to about two meters down the hole wall. These could be considered the areas where damage may occur during the in-situ test. When the other hole is pressurized with a 0.8 MPa confining pressure it yields that 5 MPa more stress is needed to damage the rock than without confining pressure. This makes the damaged area in some degree smaller. High compressive stresses in addition to some tensile stresses might induce some AE (acoustic emission) activity in the upper part of the hole from the very beginning of the test and are thus potential areas where AE activities may be detected. Monitoring like acoustic emissions will be measured during the test execution. The 2D coupled PFC-FLAC modeling indicated that

Fabrication of modified lithium orthosilicate pebbles by addition of titania

Energy Technology Data Exchange (ETDEWEB)

Knitter, R., E-mail: regina.knitter@kit.edu [Karlsruhe Institute of Technology (KIT), Institute for Applied Materials (IAM-WPT), Karlsruhe, 76021 (Germany); Kolb, M.H.H.; Kaufmann, U. [Karlsruhe Institute of Technology (KIT), Institute for Applied Materials (IAM-WPT), Karlsruhe, 76021 (Germany); Goraieb, A.A. [Goraieb Versuchstechnik (GVT), Karlsruhe, 76227 (Germany)

2013-11-15

Highlights: ► Lithium orthosilicate pebbles with additions of titania were fabricated by a modified melt-based process. ► The fabricated pebbles exhibit a very fine-grained microstructure with lithium metatitanate as a secondary phase. ► Due to the addition of titanate, the crush load of the pebbles was significantly increased. ► The closed porosity was found to be slightly increased with increasing titanate content. -- Abstract: Lithium orthosilicate pebbles are one of the ceramic tritium breeder materials destined for the European solid breeder test blanket modules of ITER, the large-scale scientific experiment intended to prove the viability of fusion as an energy source, presently under construction in Cadarache, France. While the current reference material is fabricated by melt-spraying with 2.5 wt.% excess of silica, resulting in a two-phase material of lithium orthosilicate and metasilicate, a modified melt-based process was used to fabricate breeder pebbles with additions of titania in order to obtain pebbles with lithium metatitanate as a secondary phase. The fabricated two-phase pebbles exhibit a fine-grained microstructure and increased crush loads. The optimum titanate content has yet to be evaluated, nonetheless the pebbles may have the potential to combine the advantages of both lithium orthosilicate and metatitanate breeder ceramics.

Investigations into the residual strength of a 2.5 m wide Bushveld Merensky Reef crush pillar

CSIR Research Space (South Africa)

Watson, BP

2008-08-01

Full Text Available of falls of ground in already dangerous areas, and the larger pillars decrease the extraction ratio. This paper describes the evaluation of stress measurements conducted in two boreholes over a crush pillar with dimensions 2.5 m x 4.0 m, and a height of 1...

Cell motility regulation on a stepped micro pillar array device (SMPAD) with a discrete stiffness gradient.

Science.gov (United States)

Lee, Sujin; Hong, Juhee; Lee, Junghoon

2016-02-28

Our tissues consist of individual cells that respond to the elasticity of their environment, which varies between and within tissues. To better understand mechanically driven cell migration, it is necessary to manipulate the stiffness gradient across a substrate. Here, we have demonstrated a new variant of the microfabricated polymeric pillar array platform that can decouple the stiffness gradient from the ECM protein area. This goal is achieved via a "stepped" micro pillar array device (SMPAD) in which the contact area with the cell was kept constant while the diameter of the pillar bodies was altered to attain the proper mechanical stiffness. Using double-step SU-8 mold fabrication, the diameter of the top of every pillar was kept uniform, whereas that of the bottom was changed, to achieve the desired substrate rigidity. Fibronectin was immobilized on the pillar tops, providing a focal adhesion site for cells. C2C12, HeLa and NIH3T3 cells were cultured on the SMPAD, and the motion of the cells was observed by time-lapse microscopy. Using this simple platform, which produces a purely physical stimulus, we observed that various types of cell behavior are affected by the mechanical stimulus of the environment. We also demonstrated directed cell migration guided by a discrete rigidity gradient by varying stiffness. Interestingly, cell velocity was highest at the highest stiffness. Our approach enables the regulation of the mechanical properties of the polymeric pillar array device and eliminates the effects of the size of the contact area. This technique is a unique tool for studying cellular motion and behavior relative to various stiffness gradients in the environment.

PREPARATION OF TITANIA SOL-GEL COATINGS CONTAINING SILVER IN VARIOUS FORMS AND MEASURING OF THEIR BACTERICIDAL EFFECTS AGAINST E. COLI

Directory of Open Access Journals (Sweden)

Diana Horkavcova

2015-09-01

Full Text Available The work describes titania coatings containing various forms of silver applied on a titanium substrate by a dip-coating sol-gel technique. Silver was added into the basic titania sol in form of colloid particles of Ag, crystals of AgNO3, particles of AgI, particles of Ag3PO4 and Ag3PO4 developed in situ (in the sol by reaction of AgNO3 with added calcium phosphate (brushite or monetite. Mechanically and chemically treated titanium substrates were dipped at a constant rate into individual types of sols. Subsequently, they were slowly fired. The fired coatings contained microcracks. All over the surface there were evenly distributed spherical nanoparticles of silver (Ag, AgNO3 or microcrystals of AgI and Ag3PO4. The prepared coatings were tested under static conditions for their bactericidal effects against gram-negative bacteria Escherichia coli (E. coli. The coated substrates were immersed into a suspension of E. coli in physiological solution for 24 and 4 hours. The basic titania coatings with no silver demonstrated no bactericidal properties. Very good bactericidal effect against E. coli in both types of bactericidal test showed the titania coatings with AgNO3, Ag3PO4 crystals and Ag3PO4 developed in situ.

Arsenic Removal from Aqueous Solution Using Pure and Metal-Doped Titania Nanoparticles Coated on Glass Beads: Adsorption and Column Studies

Directory of Open Access Journals (Sweden)

M. Ihsan Danish

2013-01-01

Full Text Available Nanosized metal oxide, Titania, provides high surface area and specific affinity for the adsorption of heavy metals, including arsenic (As, which is posing a great threat to the world population due to its carcinogenic nature. In this study, As(III adsorption was studied on pure and metal- (Ag- and Fe- doped Titania nanoparticles. The nanoparticles were synthesized by liquid impregnation method with some modifications, with crystallite size in the range of 30 to 40 nm. Band gap analysis, using Kubelka-Munk function showed a shift of absorption band from UV to visible region for the metal-doped Titania. Effect of operational parameters like dose of nanoparticles, initial As(III concentration, and pH was evaluated at 25°C. The data obtained gave a good fit with Langmuir and Freundlich isotherms and the adsorption was found to conform to pseudo-second-order kinetics. In batch studies, over 90% of arsenic removal was observed for both types of metal-doped Titania nanoparticles from a solution containing up to 2 ppm of the heavy metal. Fixed bed columns of nanoparticles, coated on glass beads, were used for As(III removal under different operating conditions. Thomas and Yoon-Nelson models were applied to predict the breakthrough curves and to find the characteristic column parameters useful for process design. The columns were regenerated using 10% NaOH solution.

Silica intercalated crystalline zirconium phosphate-type materials

NARCIS (Netherlands)

1988-01-01

The present invention relates to intercalated crystalline zirconium phosphate-types compositions wherein the interlayers of said composition have been intercalated with three-dimensional silicon oxide pillars whereby the pillars comprise at least two silicon atom layers parallel to the clay

Kinetics of the water formation in the propene epoxidation over gold-titania catalysts

NARCIS (Netherlands)

Nijhuis, T.A.; Weckhuysen, B.M.

2007-01-01

The kinetics of the hydrogen oxidation were determined for a number of different gold catalysts supported on titania, silica, and silicalite-1. A dual site Langmuir-Hinshelwood kinetic model was able to describe the reaction well. The kinetic parameters are independent of the support. Water was

Research of Deformation of Clay Soil Mixtures Mixtures

OpenAIRE

Romas Girkontas; Tadas Tamošiūnas; Andrius Savickas

2014-01-01

The aim of this article is to determine clay soils and clay soils mixtures deformations during drying. Experiments consisted from: a) clay and clay mixtures bridges (height ~ 0,30 m, span ~ 1,00 m); b) tiles of clay and clay, sand and straw (height, length, wide); c) cylinders of clay; clay and straw; clay, straw and sand (diameter; height). According to the findings recommendations for clay and clay mixtures drying technology application were presented. During the experiment clay bridge bear...

Hydrothermal crystallization of amorphous titania films deposited using low temperature atomic layer deposition

Energy Technology Data Exchange (ETDEWEB)

Mitchell, D.R.G. [Institute of Materials Engineering, ANSTO, PMB 1, Menai, NSW 2234 (Australia)], E-mail: drm@ansto.gov.au; Triani, G.; Zhang, Z. [Institute of Materials Engineering, ANSTO, PMB 1, Menai, NSW 2234 (Australia)

2008-10-01

A two stage process (atomic layer deposition, followed by hydrothermal treatment) for producing crystalline titania thin films at temperatures compatible with polymeric substrates (< 130 deg. C) has been assessed. Titania thin films were deposited at 80 deg. C using atomic layer deposition. They were extremely flat, uniform and almost entirely amorphous. They also contained relatively high levels of residual Cl from the precursor. After hydrothermal treatment at 120 deg. C for 1 day, > 50% of the film had crystallized. Crystallization was complete after 10 days of hydrothermal treatment. Crystallization of the film resulted in the formation of coarse grained anatase. Residual Cl was completely expelled from the film upon crystallization. As a result of the amorphous to crystalline transformation voids formed at the crystallization front. Inward and lateral crystal growth resulted in voids being localized to the film/substrate interface and crystallite perimeters resulting in pinholing. Both these phenomena resulted in films with poor adhesion and film integrity was severely compromised.

Template-directed synthesis of pillared-porous carbon nanosheet architectures: High-performance electrode materials for supercapacitors

Energy Technology Data Exchange (ETDEWEB)

Fan, Zhuangjun; Liu, Yang; Yan, Jun; Wang, Qian; Wei, Tong [Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education College of Material Science and Chemical Engineering, Harbin Engineering University, Harbin (China); Ning, Guoqing [State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Beijing, Changping (China); Zhi, Linjie [National Center for Nanoscience and Technology of China, Zhongguancun, Beijing (China); Wei, Fei [Beijing Key Laboratory of Green Chemical Reaction Engineering and Technology, Department of Chemical Engineering, Tsinghua University, Beijing (China)

2012-04-15

3D pillared-porous carbon nanosheets with supporting carbon pillars between the carbon layers is prepared by the carbonization of pitch on porous MgO templates. This unique structure endows the high-rate transportation of electrolyte ions and electrons throughout the electrode matrix, resulting in excellent electrochemical performance. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Selective epoxidation of allylic alcohols with a titania-silica aerogel

Energy Technology Data Exchange (ETDEWEB)

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

1998-12-31

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

Quality factors of nonideal micro pillars

DEFF Research Database (Denmark)

Gregersen, Niels; Nielsen, Torben Roland; Tromborg, Bjarne

2007-01-01

The influence of fabrication-induced imperfections and material absorption on the quality (Q) factor of a microcavity pillar is studied numerically. The dependence on sidewall inclination, selective underetch, and intrinsic loss is quantified. The authors show that imperfections can lead to an im...... to an improvement in Q and that a sidewall inclination angle of less than 1° causes a dramatic change in the Q factor. The variations in Q can be attributed to a delicate balance between effective index contrasts, mode overlap, and higher-order mode contributions....

HDPE/clay hybrids: the effect of clay modified with poly(diphenyl siloxanes) on thermal and rheological properties

Energy Technology Data Exchange (ETDEWEB)

Monasterio, Fernanda E.; Carrera, Maria C.; Erdmann, Eleonora; Destefanis, Hugo A., E-mail: ferelenakq@gmail.co [Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET), Buenos Aires (Argentina). Inst. de Investigaciones para la Industria Quimica; Pita, Victor J.R.R.; Dias, Marcos L. [Universidade Federal do Rio de Janeiro (IMA/UFRJ), RJ (Brazil). Inst. de Macromoleculas Profa. Eloisa Mano

2009-07-01

Poly(diphenyl siloxanes) (PDPhS) were synthesized in presence of organophilic clay in order to modify its nano structure. Two silane monomers were used: dimethoxydiphenylsilane and dichlorodiphenylsilane. The following characterizations were performed for all clays: XRD, FTIR and TGA/DTG. These siloxane-modified clays were more hydrophobic and had enhanced thermal stability. Solvent extraction was carried out in the siloxane-modified clays and the PDPhS soluble fraction analyzed according the molecular weight via GPC. The presence of free and grafted oligomers on clay surface was identified. The modified clays were added to HDPE by melt processing to obtain HDPE/clay hybrids which exhibited marked differences in the rheological behavior when compared with neat HDPE. (author)

HDPE/clay hybrids: the effect of clay modified with poly(diphenyl siloxanes) on thermal and rheological properties

International Nuclear Information System (INIS)

Monasterio, Fernanda E.; Carrera, Maria C.; Erdmann, Eleonora; Destefanis, Hugo A.; Pita, Victor J.R.R.; Dias, Marcos L.

2009-01-01

Poly(diphenyl siloxanes) (PDPhS) were synthesized in presence of organophilic clay in order to modify its nano structure. Two silane monomers were used: dimethoxydiphenylsilane and dichlorodiphenylsilane. The following characterizations were performed for all clays: XRD, FTIR and TGA/DTG. These siloxane-modified clays were more hydrophobic and had enhanced thermal stability. Solvent extraction was carried out in the siloxane-modified clays and the PDPhS soluble fraction analyzed according the molecular weight via GPC. The presence of free and grafted oligomers on clay surface was identified. The modified clays were added to HDPE by melt processing to obtain HDPE/clay hybrids which exhibited marked differences in the rheological behavior when compared with neat HDPE. (author)

Crystallite size distribution of clay minerals from selected Serbian clay deposits

Directory of Open Access Journals (Sweden)

Simić Vladimir

2006-01-01

Full Text Available The BWA (Bertaut-Warren-Averbach technique for the measurement of the mean crystallite thickness and thickness distributions of phyllosilicates was applied to a set of kaolin and bentonite minerals. Six samples of kaolinitic clays, one sample of halloysite, and five bentonite samples from selected Serbian deposits were analyzed. These clays are of sedimentary volcano-sedimentary (diagenetic, and hydrothermal origin. Two different types of shape of thickness distribution were found - lognormal, typical for bentonite and halloysite, and polymodal, typical for kaolinite. The mean crystallite thickness (T BWA seams to be influenced by the genetic type of the clay sample.

Optical, mechanical and TEM assessment of titania-doped Bi2V1 ...

Indian Academy of Sciences (India)

2016-08-26

Aug 26, 2016 ... Home; Journals; Bulletin of Materials Science; Volume 37; Issue 7. Optical, mechanical and TEM assessment of titania-doped Bi2V1−TiO5.5−δ bismuth vanadate oxides. Gurbinder Kaur Gary Pickrell Vishal Kumar Om Prakash Pandey Kulvir Singh Daniel Homa. Volume 37 Issue 7 December 2014 pp ...

Aspects of clay/concrete interactions

International Nuclear Information System (INIS)

Oscarson, D.W.; Dixon, D.A.; Onofrei, M.

1997-01-01

In the Canadian concept for nuclear fuel waste management, both clay-based materials and concrete are proposed for use as barriers, seals or supporting structures. The main concern when clays and concrete are in proximity is the generation of a high-pH environment by concrete since clay minerals are relatively unstable at high pH. Here we examine the OH - -generating capacity of two high-performance concretes when in contact with several solutions. We also investigate various aspects of claylconcrete interactions. They are: (1) the alkalimetric titration of clay suspensions, (2) the effect of Ca(OH) 2 (portlandite) on the swelling and hydraulic properties of compacted bentonite, and (3) the influence of cement grout on a backfill clay retrieved from the 900-d Buffer/Container Experiment at the Underground Research Laboratory of AECL. The results indicate that although high-performance concretes establish significantly lower poresolution pH (9 to 10) than does ordinary portland cement, the pH is still somewhat higher than that of clay/groundwater systems of about pH 8. Hence, even if high-performance concrete is used in a disposal vault, the potential still exists for clay minerals to alter over long periods of time if in contact with this concrete. The data show, however, that clays have a substantial buffering capacity, and clay-based barriers can thus neutralize much of the OH - potentially released from concrete in a vault. Moreover, even after reacting for 120 d at 85 o C with up to 5 wt.% Ca(OH) 2 , compacted bentonite (dry density = 1.2 Mg/m 3 ) retains much of its swelling capacity and has a permeability low enough (hydraulic conductivity ≤ 10 -11 m/s) to ensure that molecular diffusion will be the main transport mechanism through compacted clay-based barriers. Furthermore, according to X-ray diffractometry, the clay mineral component of backfill was not altered by contact with a cement grout for 900 d in the Buffer/Container Experiment

Physical Properties of Latvian Clays

OpenAIRE

Jurgelāne, I; Stepanova, V; Ločs, J; Mālers, J; Bērziņa-Cimdiņa, L

2012-01-01

Physical and chemical properties of clays mostly depends on its mineral and chemical composition, particle size and pH value. The mutual influence of these parameters is complex. Illite is the most abundant clay mineral in Latvia and usually used in building materials and pottery. The viscosity and plasticity of Latvian clays from several deposits were investigated and correlated with mineral composition, particle size and pH value. Fractionated and crude clay samples were used. The p...

In situ fabrication of nanostructured titania coating on the surface of titanium wire: A new approach for preparation of solid-phase microextraction fiber

International Nuclear Information System (INIS)

Cao Dandan; Lue Jianxia; Liu Jingfu; Jiang Guibin

2008-01-01

Nanostructured titania-based solid-phase microextraction (SPME) fibers were fabricated through the in situ oxidation of titanium wires with H 2 O 2 (30%, w/w) at 80 deg. C for 24 h. The obtained SPME fibers possess a ∼1.2 μm thick nanostructured coating consisting of ∼100 nm titania walls and 100-200 nm pores. The use of these fibers for headspace SPME coupled with gas chromatography with electron capture detection (GC-ECD) resulted in improved analysis of dichlorodiphenyltrichloroethane (DDT) and its degradation products. The presented method to detect DDT and its degradation products has high sensitivity (0.20-0.98 ng L -1 ), high precision (relative standard deviation R.S.D. = 9.4-16%, n = 5), a wide linear range (5-5000 ng L -1 ), and good linearity (coefficient of estimation R 2 = 0.991-0.998). As the nanostructured titania was in situ formed on the surface of a titanium wire, the coating was uniformly and strongly adhered on the titanium wire. Because of the inherent chemical stability of the titania coating and the mechanical durability of the titanium wire substrate, this new SPME fiber exhibited long life span (over 150 times)

Empirical approach for designing of support system in mechanized coal pillar mining

Energy Technology Data Exchange (ETDEWEB)

Kushwaha, A.; Singh, S.K.; Tewari, S.; Sinha, A. [Central Institute of Mining & Fuel Research, Dhanbad (India)

2010-10-15

Mechanized room-and-pillar system of coal pillar mining using side dump loading machine or load haul dumper machine, or by continuous miner, is the presently most dominant under ground method of extraction in India. Under this method of extraction, strata control is a major problem affecting safety and productivity of the mine. As per existing Director General of Mine Safety guidelines, systematic support rules must be followed at the depillaring faces irrespective of immediate roof rock type and competency. Therefore, there is a high chance that sometimes these systematic support rules give unnecessarily high support, or sometimes inadequate support, which may lead to roof failure at the face. As a result, there is a big loss of life and material including coal in terms of left-outribs/stooks and other associated mining equipment deployed at the faces. Therefore, in the present paper, authors attempted to develop generalized empirical equations for estimating the required support load density at different places of the face based on geotechnical parameters of the mine and physico-mechanical properties of the immediate roof rocks for designing of support system during mechanized coal pillar mining.

Enchanted Clays: 44th Annual Meeting of the Clay Minerals Society (June 2007)

Energy Technology Data Exchange (ETDEWEB)

Randall T. Cygan

2007-06-01

“Enchanted Clays: 44th Annual Meeting of the Clay Minerals Society” was held in early June 2007 in beautiful and historic Santa Fe, New Mexico, USA. Santa Fe provided an idyllic location in the southwestern United States for the attendees to enjoy technical and social sessions while soaking up the diverse culture and wonderful climate of New Mexico—The Land of Enchantment. The meeting included a large and varied group of scientists, sharing knowledge and ideas, benefitting from technical interactions, and enjoying the wonderful historic and enchanted environs of Santa Fe. Including significant number of international scientists, the meeting was attended by approximately two hundred participants. The meeting included three days of technical sessions (oral and poster presentations), three days of field trips to clay and geological sites of northern New Mexico, and a full day workshop on the stabilization of carbon by clays. Details can be found at the meeting web site: www.sandia.gov/clay.

Evaluation of the bleaching flux in clays containing hematite and different clay minerals

International Nuclear Information System (INIS)

Silva Junior, E.M.; Lusa, T.; Silva, T.M.; Medeiros, B.B.; Santos, G.R. dos; Morelli, M.R.

2016-01-01

Previous studies have shown that the addition of a synthetic flux in a clay mineral constituted by illite phase in the presence of iron oxide with the hematite, promotes color change of the firing products, making the reddish color firing into whiteness. This flow is constituted of a vitreous phase of the silicates family obtained by fusion/solidification of oxides and carbonates. Thus, the objective of this work was that of studying the interaction of the iron element in the final color mechanism of the different types of mineral crystal phase of the clays. In order to study the phenomenon, we obtained different compositions between the select clays and the synthetic flow, and characterization using X-ray diffraction (XRD) and visual analysis. The results showed that the action of the synthetic flow as a modifying agent for color depends on the mineral crystal phase of the clays. The color firing modification does not occur in the clays content high levels of kaolinite mineral phase. (author)

Structural transformation of nanocrystalline titania by sol-gel and the growth kinetics of crystallites

International Nuclear Information System (INIS)

Hu Linhua; Dai Songyuan; Wang Kongjia

2002-05-01

Structural transformation of nanocrystalline titania prepared by sol-gel with hydrolysis precursor titanium isopropoxide was investigated. At the same time, the growth kinetics of titania powders was also studied here. It was found that the grain size of the powders increased slowly with autoclave heating temperature up to 230 degree C, when hydrolysis pH was 0.9, but grew rapidly when heating temperature was higher that 230 degree C. The activation energies for growth of anatase crystallites in two temperature regions were calculated to be 18.5 kJ/mol and 59.7 kJ/mol respectively. The X-ray diffraction results show that the transformation from anatase phase to rutile phase starts at 230 degree C and structural transformation finished when temperature raises to 270 degree C, which is a temperature much more lower than that of the transformation by conventional literature reports

Columns in Clay

Science.gov (United States)

Leenhouts, Robin

2010-01-01

This article describes a clay project for students studying Greece and Rome. It provides a wonderful way to learn slab construction techniques by making small clay column capitols. With this lesson, students learn architectural vocabulary and history, understand the importance of classical architectural forms and their influence on today's…

Hydrothermal synthesis of nanostructured titania

International Nuclear Information System (INIS)

Yoshito, Walter Kenji; Ferreira, Nildemar A.M.; Rumbao, Ana Carolina S. Coutinho; Lazar, Dolores R.R.; Ussui, Valter

2009-01-01

Titania ceramics have many applications due to its surface properties and, recently, its nanostructured compounds, prepared by hydrothermal treatments, have been described to improve these properties. In this work, commercial titanium dioxide was treated with 10% sodium hydroxide solution in a pressurized reactor at 150°C for 24 hours under vigorous stirring and then washed following two different procedures. The first one consisted of washing with water and ethanol and the second with water and hydrochloric acid solution (1%). Resulting powders were characterized by X-ray diffraction, N 2 gas adsorption and field emission gun scanning and transmission electronic microscopy. Results showed that from an original starting material with mainly rutile phase, both anatase and H 2 Ti 3 O 7 phase could be identified after the hydrothermal treatment. Surface area of powders presented a notable increase of one order of magnitude and micrographs showed a rearrangement on the microstructure of powders. (author)

Hydrothermal synthesis of nanostructured titania

International Nuclear Information System (INIS)

Yoshito, W.K.; Ferreira, N.A.M.; Lazar, D.R.R.; Ussui, V.; Rumbao, A.C.S.

2011-01-01

Titania ceramics have many applications due to its surface properties and, recently, its nanostructured compounds, prepared by hydrothermal treatments, have been described to improve these properties. In this work, commercial titanium dioxide was treated with 10% sodium hydroxide solution in a pressurized reactor at 150 deg C for 24 hours under vigorous stirring and then washed following two different procedures. The first one consisted of washing with water and ethanol and the second with water and hydrochloric acid solution (1%). Resulting powders were characterized by X-ray diffraction, N 2 gas adsorption and field emission gun scanning and transmission electronic microscopy. Results showed that from an original starting material with mainly rutile phase, both anatase and H 2 Ti 3 O 7 phase could be identified after the hydrothermal treatment. Surface area of powders presented a notable increase of one order of magnitude and micrographs showed a rearrangement on the microstructure of powders. (author)

An array of ordered pillars with retentive properties for pressure-driven liquid chromatography fabricated directly from an unmodified cyclo olefin polymer

NARCIS (Netherlands)

Illa, Xavi; de Malsche, Wim; Bomer, Johan G.; Gardeniers, Johannes G.E.; Eijkel, Jan C.T.; Morante, Joan Ramon; Romano-Rodriguez, Albert; Desmet, Gert

2009-01-01

The current paper describes the development and characterization of a pillar array chip that is constructed out of a sandwich of cyclo olefin polymer (COP) sheets. The silicon master of a 5 cm long pillar array was embossed into the COP, yielding 4.3 µm deep pillars of 15.3 µm diameter with an

Effects of Different Types of Clays and Maleic Anhydride Modified Polystyrene on Polystyrene/Clay Nanocomposites

Directory of Open Access Journals (Sweden)

M. Mehrabzadeh

2013-01-01

Full Text Available Polymer/clay nanocomposites are considered as a new subject of research in Iran and the world. Addition of a minimum amount of clay (2-5wt% can improve the mechanical properties, enhance barrier properties and reduce flammability dramatically. Polystyrene (PS exhibits high strength, high modulus and excellent dimensional stability, but it has poor ductility, elongation, and flexural modulus. By incorporating clay into polystyrene these properties can be improved. In this study preparation of polystyrene/clay nanocomposite, effects of different types of clays (Cloisite 10A andNanomer I.30TC and maleic anhydride modified polystyrene on mechanical properties of the prepared polystyrene/clay nanocomposites were evaluated. Samples were prepared by a twin screw extruder. Transmission electron microscopy (TEM and X-ray diffraction (XRD techniques were employed to evaluate the extent of intercalation and exfoliation of silicate layers in the nanocomposites. Mechanical tests show that by addition of clay and maleic anhydride modified polystyrene the flexural modulus (~30% and elongation-at-break (~40% of prepared nanocomposites have been improved. XRD and TEM results show that nanocomposite have an intercalated structure with ability to change to further exfoliation structure.

In-vitro bioactivity and electrochemical behavior of polyaniline encapsulated titania nanotube arrays for biomedical applications

Science.gov (United States)

Agilan, P.; Rajendran, N.

2018-05-01

Titania nanotube arrays (TNTA) have attracted increasing attention due to their outstanding properties and potential applications in biomedical field. Fabrication of titania nanotubes on titanium surface enhances the biocompatibility. Polyaniline (PANI) is one of the best conducting polymers with remarkable corrosion resistance and reasonable biocompatibility. In this work, the corrosion resistance and biocompatibility of polyaniline encapsulated TiO2 nanotubes for orthopaedic applications were investigated. The vertically oriented, highly ordered TiO2 nanotubes were fabricated on titanium by electrochemical anodization process using fluoride containing electrolytes. The anodization parameters viz., voltage, pH, time and electrolyte concentration were optimized to get orderly arranged TNTA. Further, the conducting polymer PANI was encapsulated on TNTA by electropolymerization process to enhance the corrosion resistance. The nanostructure of the fabricated TNTA and polyaniline encapsulated titania nanotube arrays (PANI-TNTA) were investigated by HR SEM analysis. The formed phases and functional groups were find using XRD, ATR-FTIR. The hydrophilic surface of TNTA and PANI-TNTA was identified by water contact angle studies. The corrosion behavior of specimens was evaluated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization studies. In-vitro immersion studies were carried out in simulated body fluid solution (Hanks' solution) to evaluate the bioactivity of the TNTA and PANI-TNTA. The surface morphological studies revealed the formation of PANI on the TNTA surface. Formation of hydroxyapatite (HAp) on the surfaces of TNTA and PANI-TNTA enhanced the bioactivity and corrosion resistance.

Thixotropic Properties of Latvian Illite Containing Clays

OpenAIRE

Lakevičs, Vitālijs; Stepanova, Valentīna; Niedra, Santa; Dušenkova, Inga; Ruplis, Augusts

2015-01-01

Thixotropic properties of Latvian Devonian and Quaternary clays were studied. Dynamic viscosity of the water clay suspensions were measured with a rotating viscometer. Influence of concentration, pH and modifiers on the thixotropic clay properties was analyzed. It was found that Latvian clays have thixotropic properties. Stability of clay suspensions is described with the thixotropy hysteresis loop. Increasing the speed of the viscometer rotation, dynamic viscosity of the clay suspension decr...

Clay exfoliation and polymer/clay aerogels by supercritical carbon dioxide

Directory of Open Access Journals (Sweden)

Simona eLongo

2013-11-01

Full Text Available Supercritical carbon dioxide (scCO2 treatments of a montmorillonite (MMT intercalated with ammonium cations bearing two long hydrocarbon tails (organo-modified MMT, OMMT led to OMMT exfoliation, with loss of the long-range order in the packing of the hydrocarbon tails and maintenance of the long-range order in the clay layers. The intercalated and the derived exfoliated OMMT have been deeply characterized, mainly by X-ray diffraction analyses. Monolithic composite aerogels, with large amounts of both intercalated and exfoliated OMMT and including the nanoporous-crystalline δ form of syndiotactic polystyrene (s-PS, have been prepared, by scCO2 extractions of s-PS-based gels. Also for high OMMT content, the gel and aerogel preparation procedures occur without re-aggregation of the exfoliated clay, which is instead observed for other kinds of polymer processing. Aerogels with the exfoliated OMMT have more even dispersion of the clay layers, higher elastic modulus and larger surface area than aerogels with the intercalated OMMT. Extremely light materials with relevant transport properties could be prepared. Moreover, s-PS-based aerogels with exfoliated OMMT could be helpful for the handling of exfoliated clay minerals.

Material versatility using replica molding for large-scale fabrication of high aspect-ratio, high density arrays of nano-pillars

International Nuclear Information System (INIS)

Li, Y; Menon, C; Ng, H W; Gates, B D

2014-01-01

Arrays of high aspect-ratio (AR) nano-pillars have attracted a lot of interest for various applications, such as for use in solar cells, surface acoustic sensors, tissue engineering, bio-inspired adhesives and anti-reflective surfaces. Each application may require a different structural material, which can vary in the required chemical composition and mechanical properties. In this paper, a low cost fabrication procedure is proposed for large scale, high AR and high density arrays of nano-pillars. The proposed method enables the replication of a master with high fidelity, using the subsequent replica molds multiple times, and preparing arrays of nano-pillars in a variety of different materials. As an example applied to bio-inspired dry adhesion, polymeric arrays of nano-pillars are prepared in this work. Thermoset and thermoplastic nano-pillar arrays are examined using an atomic force microscope to assess their adhesion strength and its uniformity. Results indicate the proposed method is robust and can be used to reliably prepare nano-structures with a high AR. (paper)

Experimental study of the retention properties of a cyclo olefin polymer pillar array column in reversed-phase mode

NARCIS (Netherlands)

Illa, Xavi; de Malsche, Wim; Gardeniers, Johannes G.E.; Desmet, Gert; Romano-Rodriguez, Albert

2010-01-01

Experimental measurements to study the retention capacity and band broadening under retentive conditions using micromachined non-porous pillar array columns fabricated in cyclo olefin polymer are presented. In particular, three columns with different depths but with the same pillar structure have

Titania Supported Co-Mn-Al Oxide Catalysts in Total Oxidation of Ethanol

Czech Academy of Sciences Publication Activity Database

Ludvíková, Jana; Jirátová, Květa; Klempa, Jan; Böhmová, Vlasta; Obalová, L.

2012-01-01

Roč. 179, č. 1 (2012), s. 164-169 ISSN 0920-5861 R&D Projects: GA ČR GAP106/10/1762; GA ČR GD203/08/H032 Institutional research plan: CEZ:AV0Z40720504; CEZ:AV0Z30130516 Keywords : mixed oxide catalysts * voc oxidation * titania Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 2.980, year: 2012

What makes a natural clay antibacterial?

Science.gov (United States)

Williams, Lynda B.; Metge, David W.; Eberl, Dennis D.; Harvey, Ronald W.; Turner, Amanda G.; Prapaipong, Panjai; Port-Peterson, Amisha T.

2011-01-01

Natural clays have been used in ancient and modern medicine, but the mechanism(s) that make certain clays lethal against bacterial pathogens has not been identified. We have compared the depositional environments, mineralogies, and chemistries of clays that exhibit antibacterial effects on a broad spectrum of human pathogens including antibiotic resistant strains. Natural antibacterial clays contain nanoscale (2+ solubility.

Viscosity and Plasticity of Latvian Illite Clays

OpenAIRE

Jurgelāne, I; Vecstaudža, J; Stepanova, V; Mālers, J; Bērziņa-Cimdiņa, L

2012-01-01

Due to viscosity and plasticity, clays and clay minerals are used in civil engineering, pottery and also in cosmetics and medicine as thickening agents and emulsion and suspension stabilizers. The rheological properties of clay suspensions are complex. Mostly it is an interaction between mineral composition, clay particle size and pH value and also depends on clay minerals. Clay-water suspension is non-Newtonian fluid showing thixotropic and pseudoplastic properties. Results showed that plast...

Rockburst Disaster Prediction of Isolated Coal Pillar by Electromagnetic Radiation Based on Frictional Effect

Science.gov (United States)

Zhao, Tongbin; Yin, Yanchun; Xiao, Fukun; Tan, Yunliang; Zou, Jianchao

2014-01-01

Based on the understanding that charges generated during coal cracking are due to coal particle friction, a microstructure model was developed by considering four different variation laws of friction coefficient. Firstly, the frictional energy release of coal sample during uniaxial compressive tests was investigated and discussed. Then electromagnetic radiation method was used to predict the potential rockburst disaster in isolated coal pillar mining face, Muchengjian Colliery. The results indicate that the friction coefficient of coal particles decreases linearly with the increase of axial loading force. In predicting the strain-type rockburst, the high stress state of coal must be closely monitored. Field monitoring shows that electromagnetic radiation signal became abnormal before the occurrence of rockburst during isolated coal pillar mining. Furthermore, rockburst tends to occur at the early and ending stages of isolated coal pillar extraction. Mine-site investigation shows the occurrence zone of rockburst is consistent with the prediction, proving the reliability of the electromagnetic radiation method to predict strain-type rockburst disaster. PMID:25054186

Rockburst Disaster Prediction of Isolated Coal Pillar by Electromagnetic Radiation Based on Frictional Effect

Directory of Open Access Journals (Sweden)

Tongbin Zhao

2014-01-01

Full Text Available Based on the understanding that charges generated during coal cracking are due to coal particle friction, a microstructure model was developed by considering four different variation laws of friction coefficient. Firstly, the frictional energy release of coal sample during uniaxial compressive tests was investigated and discussed. Then electromagnetic radiation method was used to predict the potential rockburst disaster in isolated coal pillar mining face, Muchengjian Colliery. The results indicate that the friction coefficient of coal particles decreases linearly with the increase of axial loading force. In predicting the strain-type rockburst, the high stress state of coal must be closely monitored. Field monitoring shows that electromagnetic radiation signal became abnormal before the occurrence of rockburst during isolated coal pillar mining. Furthermore, rockburst tends to occur at the early and ending stages of isolated coal pillar extraction. Mine-site investigation shows the occurrence zone of rockburst is consistent with the prediction, proving the reliability of the electromagnetic radiation method to predict strain-type rockburst disaster.

Clay Portrait Boxes

Science.gov (United States)

Wilbert, Nancy Corrigan

2009-01-01

In an attempt to incorporate sculptural elements into her ceramics program, the author decided to try direct plaster casting of the face to make a plaster mold for clay. In this article, the author shares an innovative ceramics lesson that teaches students in making plaster casts and casting the face in clay. This project gives students the…

Clay matrix voltammetry

International Nuclear Information System (INIS)

Perdicakis, Michel

2012-01-01

Document available in extended abstract form only. In many countries, it is planned that the long life highly radioactive nuclear spent fuel will be stored in deep argillaceous rocks. The sites selected for this purpose are anoxic and satisfy several recommendations as mechanical stability, low permeability and low redox potential. Pyrite (FeS 2 ), iron(II) carbonate, iron(II) bearing clays and organic matter that are present in very small amounts (about 1% w:w) in soils play a major role in their reactivity and are considered today as responsible for the low redox potential values of these sites. In this communication, we describe an electrochemical technique derived from 'Salt matrix voltammetry' and allowing the almost in-situ voltammetric characterization of air-sensitive samples of soils after the only addition of the minimum humidity required for electrolytic conduction. Figure 1 shows the principle of the developed technique. It consists in the entrapment of the clay sample between a graphite working electrode and a silver counter/quasi-reference electrode. The sample was previously humidified by passing a water saturated inert gas through the electrochemical cell. The technique leads to well-defined voltammetric responses of the electro-active components of the clays. Figure 2 shows a typical voltammogram relative to a Callovo-Oxfordian argillite sample from Bure, the French place planned for the underground nuclear waste disposal. During the direct scan, one can clearly distinguish the anodic voltammetric signals for the oxidation of the iron (II) species associated with the clay and the oxidation of pyrite. The reverse scan displays a small cathodic signal for the reduction of iron (III) associated with the clay that demonstrates that the majority of the previously oxidized iron (II) species were transformed into iron (III) oxides reducible at lower potentials. When a second voltammetric cycle is performed, one can notice that the signal for iron (II

Reactive magnetron sputtering deposition of bismuth tungstate onto titania nanoparticles for enhancing visible light photocatalytic activity

Energy Technology Data Exchange (ETDEWEB)

Ratova, Marina, E-mail: marina_ratova@hotmail.com [Surface Engineering Group, School of Engineering, Manchester Metropolitan University, Manchester, M1 5GD (United Kingdom); Kelly, Peter J.; West, Glen T. [Surface Engineering Group, School of Engineering, Manchester Metropolitan University, Manchester, M1 5GD (United Kingdom); Tosheva, Lubomira; Edge, Michele [School of Science and the Environment, Manchester Metropolitan University, Manchester M1 5GD (United Kingdom)

2017-01-15

Highlights: • Bismuth tungstate coatings were deposited by reactive magnetron sputtering. • Oscillating bowl was introduced to the system to enable coating of nanopartulates. • Deposition of Bi{sub 2}WO{sub 6} enhanced visible light activity of titania nanoparticles. • The best results were obtained for coating with Bi:W ratio of approximately 2:1. • Deposition of Bi{sub 2}WO{sub 6} onto TiO{sub 2} resulted in more efficient electron-hole separation. - Abstract: Titanium dioxide − bismuth tungstate composite materials were prepared by pulsed DC reactive magnetron sputtering of bismuth and tungsten metallic targets in argon/oxygen atmosphere onto anatase and rutile titania nanoparticles. The use of an oscillating bowl placed beneath the two magnetrons arranged in a co-planar closed field configuration enabled the deposition of bismuth tungstate onto loose powders, rather than a solid substrate. The atomic ratio of the bismuth/tungsten coatings was controlled by varying the power applied to each target. The effect of the bismuth tungstate coatings on the phase, optical and photocatalytic properties of titania was investigated by X-ray diffraction, energy-dispersive X-ray spectroscopy (EDX), Brunauer–Emmett–Teller (BET) surface area measurements, transmission electron microscopy (TEM), UV–vis diffuse reflectance spectroscopy and an acetone degradation test. The latter involved measurements of the rate of CO{sub 2} evolution under visible light irradiation of the photocatalysts, which indicated that the deposition of bismuth tungstate resulted in a significant enhancement of visible light activity, for both anatase and rutile titania particles. The best results were achieved for coatings with a bismuth to tungsten atomic ratio of 2:1. In addition, the mechanism by which the photocatalytic activity of the TiO{sub 2} nanoparticles was enhanced by compounding it with bismuth tungstate was studied by microwave cavity perturbation. The results of these

Clay Animals and Their Habitats

Science.gov (United States)

Adamson, Kay

2010-01-01

Creating clay animals and their habitats with second-grade students has long been one of the author's favorite classroom activities. Students love working with clay and they also enjoy drawing animal homes. In this article, the author describes how the students created a diorama instead of drawing their clay animal's habitat. This gave students…

Surface modification of montmorillonite on surface Acid-base characteristics of clay and thermal stability of epoxy/clay nanocomposites.

Science.gov (United States)

Park, Soo-Jin; Seo, Dong-Il; Lee, Jae-Rock

2002-07-01

In this work, the effect of surface treatments on smectitic clay was investigated in surface energetics and thermal behaviors of epoxy/clay nanocomposites. The pH values, X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR) were used to analyze the effect of cation exchange on clay surface and the exfoliation phenomenon of clay interlayer. The surface energetics of clay and thermal properties of epoxy/clay nanocomposites were investigated in contact angles and thermogravimetric analysis (TGA), respectively. From the experimental results, the surface modification of clay by dodecylammonium chloride led to the increases in both distance between silicate layers of about 8 A and surface acid values, as well as in the electron acceptor component (gamma(+)(s)) of surface free energy, resulting in improved interfacial adhesion between basic (or electron donor) epoxy resins and acidic (electron acceptor) clay interlayers. Also, the thermal stability of nanocomposites was highly superior to pure epoxy resin due to the presence of the well-dispersed clay nanolayer, which has a barrier property in a composite system.

Composite templates synthesis of mesoporous titania from industrial titanyl sulfate solution under external outfields

International Nuclear Information System (INIS)

Tian Congxue

2008-01-01

The precursors of mesoporous titania were synthesized via supra-molecular self-assembly route induced by composite templates (CTAB/P-123) from industrial titanyl sulfate solution under ultrasonic irradiation, microwave and hydrothermal condition. The hydrolysis and polycondensation rates of TiOSO 4 solution were controlled by adjusting the pH value at about 1.0. Mesoporous titania with anatase phase was obtained after templates removal by calcinations. The as-prepared powder was characterized by X-ray diffraction (XRD), N 2 isothermal adsorption-desorption, HRTEM and SAD. External outfields with enhancing polar action and soft hydrothermal condition were beneficial to prepare better mesoporous TiO 2 . Ultrasonic vibration promoted the formation of mesoporous structure. Under microwave irradiation, mesoporous TiO 2 was synthesized with BET specific surface area of 190.6 m 2 g -1 , average pore diameter of 2.57 nm and crystal size of 13.65 nm. And ultrasonic irradiation, microwave and hydrothermal conditions were making for forming and stabilizing the mesoporous structure

21 CFR 186.1256 - Clay (kaolin).

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Clay (kaolin). 186.1256 Section 186.1256 Food and... Substances Affirmed as GRAS § 186.1256 Clay (kaolin). (a) Clay (kaolin) Al2O3.2SiO2.nH2O, Cas Reg. No. 1332-58-7) consists of hydrated aluminum silicate. The commercial products of clay (kaolin) contain...

Quantifying the effect of squirt flow dispersion from compliant clay porosity in clay bearing sandstones

DEFF Research Database (Denmark)

Sørensen, Morten Kanne; Fabricius, Ida Lykke

2013-01-01

Compliant porosity in the form of cracks is known to cause significant attenuation and velocity dispersion through pore pressure gradients and consequent relaxation, dubbed squirt flow. Squirt flow from cracks vanish at high confining stress due to crack closing. Studies on clay bearing sandstones......-squirt flow on the bulk modulus of a clay bearing sandstone. The predicted magnitude of the clay-squirt effect on the bulk modulus is compared with experimental data. The clay-squirt effect is found to possibly account for a significant portion of the deviances from Gassmann fluid substitution in claybearing...... sandstones....

A micro-pillar array to trap magnetic beads in microfluidic systems

KAUST Repository

Gooneratne, Chinthaka Pasan

2012-12-01

A micro-pillar array (MPA) is proposed in this paper to trap and separate magnetic beads (MBs) in microfluidic systems. MBs are used in many biomedical applications due to being compatible in dimension to biomolecules, the large surface area available to attach biomolecules, and the fact that they can be controlled by a magnetic field. Trapping and separating these labeled biomolecules is an important step toward achieving reliable and accurate quantification for disease diagnostics. Nickel Iron (Ni50Fe 50) micro-pillars were fabricated on a Silicon (Si) substrate by standard microfabrication techniques. Experimental results showed that MBs could be trapped on the MPA at the single bead level and separated from other non-target particles. This principle can easily be extended to trap and separate target biomolecules in heterogeneous biological samples. © 2012 IEEE.

Modeling plastic deformation of post-irradiated copper micro-pillars

Energy Technology Data Exchange (ETDEWEB)

Crosby, Tamer, E-mail: tcrosby@ucla.edu; Po, Giacomo, E-mail: gpo@ucla.edu; Ghoniem, Nasr M., E-mail: ghoniem@ucla.edu

2014-12-15

We present here an application of a fundamentally new theoretical framework for description of the simultaneous evolution of radiation damage and plasticity that can describe both in situ and ex situ deformation of structural materials [1]. The theory is based on the variational principle of maximum entropy production rate; with constraints on dislocation climb motion that are imposed by point defect fluxes as a result of irradiation. The developed theory is implemented in a new computational code that facilitates the simulation of irradiated and unirradiated materials alike in a consistent fashion [2]. Discrete Dislocation Dynamics (DDD) computer simulations are presented here for irradiated fcc metals that address the phenomenon of dislocation channel formation in post-irradiated copper. The focus of the simulations is on the role of micro-pillar boundaries and the statistics of dislocation pinning by stacking-fault tetrahedra (SFTs) on the onset of dislocation channel and incipient surface crack formation. The simulations show that the spatial heterogeneity in the distribution of SFTs naturally leads to localized plastic deformation and incipient surface fracture of micro-pillars.

In situ measurements of Merensky pillar behaviour at Impala Platinum

CSIR Research Space (South Africa)

Watson, BP

2009-12-01

Full Text Available to stabilize the stoping excavations. This paper describes the in situ measurement, of stress within a Merensky pillar from Impala Platinum. These measurements were used to derive a stress-strain curve that includes pre and post failure behaviour. 2D FLAC...

In situ fabrication of nanostructured titania coating on the surface of titanium wire: A new approach for preparation of solid-phase microextraction fiber

Energy Technology Data Exchange (ETDEWEB)

Cao Dandan [State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085 (China); Environmental Science Division, School of Earth and Space Science, University of Science and Technology of China, Hefei, Anhui Province 230026 (China); Lue Jianxia [State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085 (China); Liu Jingfu [State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085 (China)], E-mail: jfliu@rcees.ac.cn; Jiang Guibin [State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085 (China)

2008-03-17

Nanostructured titania-based solid-phase microextraction (SPME) fibers were fabricated through the in situ oxidation of titanium wires with H{sub 2}O{sub 2} (30%, w/w) at 80 deg. C for 24 h. The obtained SPME fibers possess a {approx}1.2 {mu}m thick nanostructured coating consisting of {approx}100 nm titania walls and 100-200 nm pores. The use of these fibers for headspace SPME coupled with gas chromatography with electron capture detection (GC-ECD) resulted in improved analysis of dichlorodiphenyltrichloroethane (DDT) and its degradation products. The presented method to detect DDT and its degradation products has high sensitivity (0.20-0.98 ng L{sup -1}), high precision (relative standard deviation R.S.D. = 9.4-16%, n = 5), a wide linear range (5-5000 ng L{sup -1}), and good linearity (coefficient of estimation R{sup 2} = 0.991-0.998). As the nanostructured titania was in situ formed on the surface of a titanium wire, the coating was uniformly and strongly adhered on the titanium wire. Because of the inherent chemical stability of the titania coating and the mechanical durability of the titanium wire substrate, this new SPME fiber exhibited long life span (over 150 times)

Polyaniline nanowire array encapsulated in titania nanotubes as a superior electrode for supercapacitors

Science.gov (United States)

Xie, Keyu; Li, Jie; Lai, Yanqing; Zhang, Zhi'an; Liu, Yexiang; Zhang, Guoge; Huang, Haitao

2011-05-01

Conducting polymer with 1D nanostructure exhibits excellent electrochemical performances but a poor cyclability that limits its use in supercapacitors. In this work, a novel composite electrode made of polyaniline nanowire-titania nanotube array was synthesized via a simple and inexpensive electrochemical route by electropolymerizing aniline onto an anodized titania nanotube array. The specific capacitance was as high as 732 F g-1 at 1 A g-1, which remained at 543 F g-1 when the current density was increased by 20 times. 74% of the maximum energy density (36.6 Wh kg-1) was maintained even at a high power density of 6000 W kg-1. An excellent long cycle life of the electrode was observed with a retention of ~86% of the initial specific capacitance after 2000 cycles. The good electrochemical performance was attributed to the unique microstructure of the electrode with disordered PANI nanowire arrays encapsulated inside the TiO2 nanotubes, providing high surface area, fast diffusion path for ions and long-term cycle stability. Such a nanocomposite electrode is attractive for supercapacitor applications.

Mineral acquisition from clay by budongo forest chimpanzees

NARCIS (Netherlands)

Reynolds, Vernon; Lloyd, Andrew W.; English, Christopher J.; Lyons, Peter; Dodd, Howard; Hobaiter, Catherine; Newton-Fisher, Nicholas; Mullins, Caroline; Lamon, Noemie; Schel, Anne Marijke; Fallon, Brittany

2015-01-01

Chimpanzees of the Sonso community, Budongo Forest, Uganda were observed eating clay and drinking clay-water from waterholes. We show that clay, clay-rich water, and clay obtained with leaf sponges, provide a range of minerals in different concentrations. The presence of aluminium in the clay

Experimental study of the retention properties of a cyclo olefin polymer pillar array column in reversed-phase mode.

Science.gov (United States)

Illa, Xavi; De Malsche, Wim; Gardeniers, Han; Desmet, Gert; Romano-Rodríguez, Albert

2010-11-01

Experimental measurements to study the retention capacity and band broadening under retentive conditions using micromachined non-porous pillar array columns fabricated in cyclo olefin polymer are presented. In particular, three columns with different depths but with the same pillar structure have been fabricated via hot embossing and pressure-assisted thermal bonding. Separations of a mixture of four coumarins using varying mobile phase compositions have been monitored to study the relation between the retention factor and the ratio of organic solvent in the aqueous mobile phase. Moreover, the linear relation between the retention and the surface/volume ratio predicted in theory has been observed, achieving retention factors up to k=2.5. Under the same retentive conditions, minimal reduced plate height values of h(min)=0.4 have been obtained at retention factors of k=1.2. These experimental results are compared with the case of non-porous and porous silicon pillars. Similar results for the plate heights are achieved while retention factors are higher than the non-porous silicon column and considerably smaller than the porous pillar column, given the non-porous nature of the used cyclo olefin polymer. The feasibility of using this polymer column as an alternative to the pillar array silicon columns is corroborated.

Evaluation of kaolinite clays of Moa for the production of cement based clinker-calcined clay-limestone (LC3

Directory of Open Access Journals (Sweden)

Roger S. Almenares-Reyes

2016-12-01

Full Text Available Clay materials from two outcrops of the Moa region were analyzed to determine their potential use as supplementary cementitious material in the production of ternary cements based on limestone-calcined clay. The clays were characterized by atomic absorption spectroscopy (EAA, X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FTIR and thermogravimetric analysis (ATG. These methods revealed high aluminum in clays, moderate kaolinite content, a disordered structure and the presence of impurities. The solubility of aluminum and silicon in alkali and the compressive strength of LC3 systems is proportional to their content in clay, being higher for the one with higher kaolinite content and greater structural disorder (outcrop D1, although the clay of both outcrops may constitute supplementary cementitious materials in the production of ternary cements based clinker-calcined clay-limestone. The suitable thermal activation range for both clays is between 650 ° C and 850 ° C.

Fabrication and characterization of Au dimer antennas on glass pillars with enhanced plasmonic response

Directory of Open Access Journals (Sweden)

Sadeghi Pedram

2017-06-01

Full Text Available We report on the fabrication and dark-field spectroscopy characterization of Au dimer nanoantennas placed on top of SiO2 nanopillars. The reported process enables the fabrication of nanopillar dimers with gaps down to 15 nm and heights up to 1 μm. A clear dependence of the plasmonic resonance position on the dimer gap is observed for smaller pillar heights, showing the high uniformity and reproducibility of the process. It is shown how increasing the height of nanopillars significantly affects the recorded elastic scattering spectra from Au nanoantennas. The results are compared to finite-difference time-domain (FDTD and finite-element method (FEM simulations. Additionally, measured spectra are accompanied by dark-field microscopy images of the dimers, showing the pronounced change in color. Placing nanoantennas on nanopillars with a height comparable to the in-plane dimer dimensions results in an enhancement of the scattering response, which can be understood through reduced interaction of the near-fields with the substrate. When increasing the pillar height further, scattering by the pillars themselves manifests itself as a strong tail at lower wavelengths. Additionally, strong directional scattering is expected as a result of the interface between the nanoantennas and nanopillars, which is taken into account in simulations. For pillars of height close to the plasmonic resonance wavelength, the scattering spectra become more complex due to additional scattering peaks as a result of larger geometrical nonuniformities.

Influence of herbicide structure, clay acidity, and humic acid coating on acetanilide herbicide adsorption on homoionic clays.

Science.gov (United States)

Liu, Weiping; Gan, Jianying; Yates, Scott R

2002-07-03

Adsorption of chloroacetanilide herbicides on homoionic montmorillonite was studied by coupling batch equilibration and FT-IR analysis. Adsorption decreased in the order metolachlor > acetochlor > alachlor > propachlor on Ca(2+)- or Mg(2+)-saturated clays and in the order metolachlor > alachlor > acetachlor > propachlor on Al(3+)- or Fe(3+)-saturated clays. FT-IR spectra showed that the carbonyl group of the herbicide molecule was involved in bonding. For the same herbicide, adsorption of alachlor, acetachlor, and metolachlor on clay followed the order Ca(2+) approximately Mg(2+) < Al(3+) < or = Fe(3+), which coincided with the increasing acidity of homoionic clays. Adsorption of propachlor, however, showed an opposite dependence, suggesting a different governing interaction. In clay and humic acid mixtures, herbicide adsorption was less than that expected from independent additive adsorption by the individual constituents, and the deviation was dependent on the clay-to-humic acid ratio, with the greatest deviation consistently occurring at a 60:40 clay-to-humic acid ratio.

Fabrication of Self-Cleaning, Reusable Titania Templates for Nanometer and Micrometer Scale Protein Patterning.

Science.gov (United States)

Moxey, Mark; Johnson, Alexander; El-Zubir, Osama; Cartron, Michael; Dinachali, Saman Safari; Hunter, C Neil; Saifullah, Mohammad S M; Chong, Karen S L; Leggett, Graham J

2015-06-23

The photocatalytic self-cleaning characteristics of titania facilitate the fabrication of reuseable templates for protein nanopatterning. Titania nanostructures were fabricated over square centimeter areas by interferometric lithography (IL) and nanoimprint lithography (NIL). With the use of a Lloyd's mirror two-beam interferometer, self-assembled monolayers of alkylphosphonates adsorbed on the native oxide of a Ti film were patterned by photocatalytic nanolithography. In regions exposed to a maximum in the interferogram, the monolayer was removed by photocatalytic oxidation. In regions exposed to an intensity minimum, the monolayer remained intact. After exposure, the sample was etched in piranha solution to yield Ti nanostructures with widths as small as 30 nm. NIL was performed by using a silicon stamp to imprint a spin-cast film of titanium dioxide resin; after calcination and reactive ion etching, TiO2 nanopillars were formed. For both fabrication techniques, subsequent adsorption of an oligo(ethylene glycol) functionalized trichlorosilane yielded an entirely passive, protein-resistant surface. Near-UV exposure caused removal of this protein-resistant film from the titania regions by photocatalytic degradation, leaving the passivating silane film intact on the silicon dioxide regions. Proteins labeled with fluorescent dyes were adsorbed to the titanium dioxide regions, yielding nanopatterns with bright fluorescence. Subsequent near-UV irradiation of the samples removed the protein from the titanium dioxide nanostructures by photocatalytic degradation facilitating the adsorption of a different protein. The process was repeated multiple times. These simple methods appear to yield durable, reuseable samples that may be of value to laboratories that require nanostructured biological interfaces but do not have access to the infrastructure required for nanofabrication.

Numerical Analysis of Warpage Induced by Thermo-Compression Bonding Process of Cu Pillar Bump Flip Chip Package

Energy Technology Data Exchange (ETDEWEB)

Kwon, Oh Young; Jung, Hoon Sun; Lee, Jung Hoon; Choa, Sung-Hoon [Seoul Nat’l Univ. of Science and Technology, Seoul (Korea, Republic of)

2017-06-15

In flip chip technology, the conventional solder bump has been replaced with a copper (Cu) pillar bump owing to its higher input/output (I/O) density, finer pitch, and higher reliability. However, Cu pillar bump technology faces several issues, such as interconnect shorting and higher low-k stress due to stiffer Cu pillar structure when the conventional reflow process is used. Therefore, the thermal compression bonding (TCB) process has been adopted in the flip chip attachment process in order to reduce the package warpage and stress. In this study, we investigated the package warpage induced during the TCB process using a numerical analysis. The warpage of the TCB process was compared with that of the reflow process.

Improving the photovoltaic parameters in Quantum dot sensitized solar cells through employment of chemically deposited compact titania blocking layer

Energy Technology Data Exchange (ETDEWEB)

Rajendra Prasad, M.B., E-mail: rajendraprasadmb75@gmail.com [Advanced Physics Laboratory, Department of Physics, SavitibaiPhule Pune University, Pune, 411007 (India); National Defence Academy, Khadakwasla, Pune, 411023 (India); Kadam, Vishal [Advanced Physics Laboratory, Department of Physics, SavitibaiPhule Pune University, Pune, 411007 (India); Joo, Oh-Shim [Korea Institute of Science and Technology, PO Box No. 131, Chongryang, Seoul, 130-650 (Korea, Republic of); Pathan, Habib M. [Advanced Physics Laboratory, Department of Physics, SavitibaiPhule Pune University, Pune, 411007 (India)

2017-06-15

Incorporation of compact blocking layer at the Transparent Conducting Oxide (TCO)/Electrolyte interface is an effective method to improve the device performance in QDSSC through mitigation of electron recombinations at this interface. This paper reports the most facile and cost effective method of depositing a rutile titania Compact Layer (CL) over Fluorine doped Tin Oxide (FTO) substrate and its application in titania based CdS QD sensitized solar cells. The deposited compact layers are characterized to study their structural, optical, morphological and electrochemical properties using X-Ray Diffractometry, UV–Visible spectroscopy, Scanning electron microscopy, Cyclic Voltammetry and Contact Angle measurements. Sandwich solar cells are fabricated using these CL based electrodes and characterized using Electrochemical Impedance Spectroscopy, Open Circuit Voltage Decay and J-V characteristics. The CL incorporated CdS QDSSC showed more than 100% increase in the photoconversion efficiency (1.68%) as compared to its bare FTO counterpart (0.73%) proving the efficacy of employed strategy. - Highlights: • Deposited titania compact layer by a facile room temperature chemical bath method. • Employed this to mitigate back electron transfer at TCO/Electrolyte interface. • Compact layer incorporation has improved the solar cell performance by 130%.

Clay shale as host rock. A geomechanical contribution about Opalinus clay

International Nuclear Information System (INIS)

Lempp, Christof; Menezes, Flora; Sachwitz, Simon

2016-01-01

The Opalinuston is a prominent rock representing the type of organic clay shales or clay stones within the sequence of Triassic and Jurassic marine sediments in Southern Germany. The rock forms a homogenous unit some ten meters thick. The degree of consolidation of this type of pelitic rock depends mainly on the former load conditions, but is also dependent on the long-term weathering and even on the present exposition. The geomechanical parameters such as shear strength, tensional strength and permeability vary with the state of consolidation and become important when the use is discussed of such rocks for radioactive waste disposal. A tunneling project at the northern escarpment of the Swabian Alb (Southwest Germany) within the Opalinus clay offered the rare opportunity to obtain fresh unweathered rock samples in greater amounts compared to fresh drilling cores from which geomechanical investigations are usually undertaken. Consequently, the results of geomechanical laboratory testings are presented in order to compare here the results of multistep triaxial compression tests, of hydraulic fracturing laboratory tests and of some other tests for rock characterization with the corresponding results of Opalinus clay sites in Switzerland that were investigated by the Swiss Nagra Company for host rock characterization. After a discussion of the relevant state of fresh Opalinus clay, especially of suction pressure conditions and saturation state, the results of triaxial shear tests are presented. Increasing shear deformation at increasing pressure and unchanged water saturation do not result in a significant strength reduction of the Opalinus clay. The rock shows increasing cohesion and stiffness, if multiple loading has repeatedly reached the failure point. Thus there is no increased permeability with continued shearing. Only at the beginning of the shearing process is a temporarily increased permeability to be expected due to dilatation processes. An increased

Evaluating 8 pillars of Total Productive Maintenance (TPM) implementation and their contribution to manufacturing performance

Science.gov (United States)

Adesta, E. Y. T.; Prabowo, H. A.; Agusman, D.

2018-01-01

TPM is one method to improve manufacturing performance through an emphasis on maintenance that involves everyone in the organization. Research on the application of TPM and its relevance to the manufacturing performance has been performed quite a lot. However, to the best of our knowledge, a study that deliberates how the application of 8 pillars TPM (especially in developing countries) is still hard to find. This paper attempts to evaluate in more detail about how the 8 pillars of TPM are applied in Indonesia and their impact on manufacturing performance. This research is a pilot study with a target of 50 companies. From the results of data collection, only 22 companies (44%) are eligible to process. Data processing was performed using SPSS and Smart PLS tools. From the validity and reliability tests, it can be seen that all items/indicators for TPM pillars are valid and reliable with correlation value (R) of 0.614 - 0.914 and with Cronbach’s alpha equal to 0.753. As for the Manufacturing Performance construct, the Delivery indicator was not valid. In overall, the model is reliable with Cronbach’s alpha of 0.710. From the results of Confirmatory Factors Analysis (CFA) for TPM, it can be seen that four indicators (pillars) are highly significant while four other indicators are less significant. For MP, three indicators are significant, and two are not significant. In general, the structural model of the relationship between TPM and MP is relatively strong and positive with values R = 0.791, and R squared = 0.626. This means that the TPM Pillars can explain 62.6% MP variability construct variable, while the other 37.4% can be explained by unrelated variables.

Determination of concrete cover thickness in a reinforced concrete pillar by observation of the scattered electromagnetic field

Science.gov (United States)

Di Gregorio, Pietro Paolo; Frezza, Fabrizio; Mangini, Fabio; Pajewski, Lara

2017-04-01

The electromagnetic scattered field by a reinforced concrete structure is calculated by means of frequency-domain numerical simulations and by making use of the scattered-field formulation. The concrete pillar, used as supporting architectural element, is modelled as a parallelepiped shell made of concrete material inside which are present steel bars. In order to make the model simpler, the steel bars are supposed running parallel to the air-pillar interface. To excite the model, a linearly-polarized plane wave impinging normally with respect to the pillars surface, is adopted. We consider two different polarizations in order to determine the most useful in terms of scattered-field sensitivity. Moreover, a preliminary frequency sweep allows us to choose the most suitable operating frequency depending on the dimensions of the pillar cross-section, the steel bars cross-section and the concrete cover. All the three components of the scattered field are monitored along a line just above the interface air-pillar. The electromagnetic properties of the materials employed in this study are present in the literature and, since a frequency-domain technique is adopted, no further approximation is needed. The results obtained for different values of the concrete cover are compared, with the goal of determining the scattered field dependence on the concrete cover thickness. Considering different concrete cover thicknesses, we want to provide an electromagnetic method to obtain this useful parameter by observation of the scattered electromagnetic field. One of the practical applications of this study in the field of Civil Engineering may be the use of ground penetrating radar (GPR) techniques to monitor the thickness of the concrete that separates the metal bars embedded in the pillar from the outer surface. A correct distance is useful because the concrete cover serves as a protection against external agents avoiding corrosion of the bars that might prejudice the reinforced

Nanosized catalysts based on Fe oxide for combustion of n-hexane

International Nuclear Information System (INIS)

Picasso, Gino; Hermoza, Emilia; Lopez, Alcides; Gomez, Gemma; Pina, Maria Pilar; Herguido, Javier

2009-01-01

In this work, nanosized catalysts on Fe oxide have been prepared for total combustion on n-hexane (2000 ppmV). The synthesis of Fe oxide have been performed following sol-gel procedure starting from precursors based on nitrate salts. According to XRD analysis, nanoparticles formed α-hematite and the average particle size estimated by TEM was 9 nm with formation of agglomerations of 140 nm. Moreover, different clays pillared with Al (Al-PILC), Ti (Ti-PILC) and Fe (Fe-PILC) have been synthesized. Some samples based on Fe-Mn equimolar mixed supported on Al-PILC (FeMn/Al-PILC) and on Ti-PILC (FeMn/Ti-PILC) have been prepared in order to study the cooperative effect of Mn. Experimental conditions of calcination were adjusted in order to obtain samples with high thermal stability. XRD analysis of pillared samples revealed the formation of stable pillars, except for Fe-PILC which described a delaminated structure. As a consequence of pillaring, an enhancement of total surface area compared to starting clay material is observed. Concerning surface area, the decreasing order series of pillared material was: Ti-PILC > Fe-PILC > Al-PILC. Depression of total surface area decreasing of basal spacing d 001 with no modification of basal structure of starting natural clay have been observed due to the incorporation of Fe-Mn active phase into the structures of Ti-PILC and Al-PILC. The Fe-Mn mixed phase supported over pillared material exhibited higher catalytic activity than the Fe-PILC sample, which was attributed to the cooperative effect of Mn. This effect could be associated with redox properties of Mn and improving of surface oxygen mobility. Delaminated structure and strong interaction of Fe with clay porous network into the Fe-PILC sample could be the reason of lower activities. However, higher performances were observed in the case of Fe oxide nanoparticles prepared with surfactant agent over bentonite, due to a lesser extent of Fe-porous structure interaction presented in

Efficacy of radiosensitizing doped titania nanoparticles under hypoxia and preparation of an embolic microparticle

Directory of Open Access Journals (Sweden)

Morrison RA

2017-05-01

Full Text Available Rachel A Morrison,1,* Malgorzata J Rybak-Smith,1,* James M Thompson,2 Bénédicte Thiebaut,3 Mark A Hill,2 Helen E Townley1,4 1Department of Engineering Science, 2Gray Laboratories, CRUK/MRC Oxford Institute for Radiation Oncology, University of Oxford, Oxford, 3Johnson Matthey, Technology Centre, Reading, Berkshire, 4Nuffield Department of Obstetrics and Gynaecology, John Radcliffe Hospital, University of Oxford, Oxford, UK *These authors have contributed equally to this work Abstract: The aim of this study was to develop a manufacturing protocol for large-scale production of doped titania radiosensitizing nanoparticles (NPs to establish their activity under hypoxia and to produce a multimodal radiosensitizing embolic particle for cancer treatment. We have previously shown that radiosensitizing NPs can be synthesized from titania doped with rare earth elements, especially gadolinium. To translate this technology to the clinic, a crucial step is to find a suitable, scalable, high-throughput method. Herein, we have described the use of flame spray pyrolysis (FSP to generate NPs from titanium and gadolinium precursors to produce titania NPs doped with 5 at% gadolinium. The NPs were fully characterized, and their capacity to act as radiosensitizers was confirmed by clonogenic assays. The integrity of the NPs in vitro was also ascertained due to the potentially adverse effects of free gadolinium in the body. The activity of the NPs was then studied under hypoxia since this is often a barrier to effective radiotherapy. In vitro radiosensitization experiments were performed with both the hypoxia mimetics deferoxamine and cobalt chloride and also under true hypoxia (oxygen concentration of 0.2%. It was shown that the radiosensitizing NPs were able to cause a significant increase in cell death even after irradiation under hypoxic conditions such as those found in tumors. Subsequently, the synthesized NPs were used to modify polystyrene embolization

Development and characterization of ceramic composites alumina-titania based reinforced with lanthanum oxide for fabrication of inert coatings for metallic tanks of the oil industry; Desenvolvimento e caracterizacao de compositos ceramicos baseados em alumina-titania reforcados com oxido de lantanio para fabricacao de revestimentos inertes em tanques metalicos da industria petrolifera

Energy Technology Data Exchange (ETDEWEB)

Bandeira, J.M.; Yadava, Y.P.; Silva, N.D.G.; Ferreira, R.A.S., E-mail: julianamb91@gmail.com, E-mail: yadava@ufpe.br [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Centro de Tecnologia e Geociencias. Departamento de Engenharia Mecanica

2016-07-01

Crude petroleum is highly corrosive causing superficial degradation in metallic tanks used for storage and transportation of this material, which causes a serious problem in the oil industry. An alternative to solve this problem is to use some kind of coating that is inert to this kind of corrosion. Alumina and titania are interesting materials for several engineering applications because, when compared with other ceramic materials, they present superior mechanical properties, e.g. high mechanical strength, good chemical stability and high fracture toughness combined with good wear resistance and a coefficient of thermal expansion close to the iron's, which makes them fit to use in ceramic hardening process and coating. In this paper, alumina-titania ceramic composites with 5%, 10%, 15% and 20% of titania (TiO2) and reinforced with 2% of lanthanum oxide of were produced by thermo-mechanical processing and sintering techniques at 1350 deg C. In these composites, microstructure and mechanical properties were analyzed using X-ray spectroscopy, optical microscopy, scanning electron microscopy and Vickers hardness in order to evaluate their applicability. X-ray spectroscopy showed the formation of composite without the presence of other phases. Optical microscopy and scanning electron microscopy showed a homogeneous microstructure in terms of particle size and distribution. Vickers hardness test showed a gradual decrease in hardness with the addition of titania. The composite with 5% of titania and 2% of lanthanum oxide is the best choice for structural applications. The composites were submerged in crude petroleum for 30 days to study their stability in such environment. Through the analysis of X-ray spectroscopy, optical microscopy and Vickers hardness before and after the submersion in crude petroleum, it was not observed structural or microstructural degradation nether alterations in mechanical properties. This way, it was concluded that these composites have

Recovery evaluation of organophosphorus pesticides from bee pollen by matrix solid-phase dispersion extraction using sorbents based on silica and titania

International Nuclear Information System (INIS)

Torres-Perea, C; Muñoz-Rodríguez, D; Carrera-Figueiras, C; Medina-Peralta, S; Moguel-Ordóñez, Y B

2013-01-01

This work focused on the evaluation of the recovery of organophosphorus pesticides from bee pollen after matrix solid phase-dispersion extraction (MSPD). Materials based on silica, titania and titania modified with polivylnylimidazole or polyestirene were used as adsorbents for the extraction of pesticides. Small amounts of fortified pollen (0.1 g, at 1 micro-g/g of pesticides), adsorbent (0.4 g) and solvent elution (1 mL de acetonitrile – ACN) were used in the extractions. For recovery evaluation, pollen extracts were analyzed by gas chromatography coupled with mass spectrometry.

Adsorption and degradation of model volatile organic compounds by a combined titania-montmorillonite-silica photocatalyst

International Nuclear Information System (INIS)

Chen Jiangyao; Li Guiying; He Zhigui; An Taicheng

2011-01-01

Highlights: → Adsorptive combined titania-montmorillonite-silica photocatalysts synthesized. → All catalysts had relatively high adsorption capacities of multinary VOCs. → All catalysts preferred to adsorb the VOCs with higher polarity. → CTMS80 can effectively photocatalytically remove VOCs of various components. - Abstract: A series of adsorptive photocatalysts, combined titania-montmorillonite-silica were synthesized. The resultant photocatalysts consisted of more and more spherically agglomerated TiO 2 particles with increasing of TiO 2 content, and anatase was the only crystalline phase with nano-scale TiO 2 particles. With increasing of the cation exchange capacity to TiO 2 molar ratio, specific surface area and pore volume increased very slightly. In a fluidized bed photocatalytic reactor by choosing toluene, ethyl acetate and ethanethiol as model pollutants, all catalysts had relatively high adsorption capacities and preferred to adsorb higher polarity pollutants. Langmuir isotherm model better described equilibrium data compared to Freundlich model. Competitive adsorptions were observed for the mixed pollutants on the catalysts, leading to decrease adsorption capacity for each pollutant. The combined titania-montmorillonite-silica photocatalyst exhibited excellent photocatalytic removal ability to model pollutants of various components. Almost 100% of degradation efficiency was achieved within 120 min for each pollutant with about 500 ppb initial concentration, though the efficiencies of multi-component compounds slightly decreased. All photocatalytic reactions followed the Langmuir-Hinshelwood model. Degradation rate constants of multi-component systems were lower than those for single systems, following the order of toluene < ethyl acetate < ethanethiol, and increased with the increase of adsorption capacities for different pollutants of various components.

Mineralogy and geotechnical characteristics of some pottery clay

Directory of Open Access Journals (Sweden)

Mujib Olamide ADEAGBO

2016-12-01

Full Text Available The physical properties of soils, which are tremendously influenced by the active clay minerals in soil, are of great importance in geotechnical engineering. This paper investigates the clay-sized particles of the Igbara-Odo pottery clay, and compares results obtained with available data on the bulk sample, to determine their correlation and underline the dependence of the geotechnical properties of the bulk clay material on the clay-sized particles. The bulk clay sample consists of 52% sand-size particles, 21% silt and 27% clay. Analysis of the clay-sized particles and the bulk materials shows: specific gravity of 2.07 and 2.66, liquid limit of 91.0% and 33.0%, plastic limit of 27.5% and 14.3%, plasticity index of 63.5% and 18.7% and a linear shrinkage of 7.9% and 5.4%, for both clay-sized particles and bulk clay respectively. The activity value of the clay material (0.64 suggests the presence of Kaolinite and Ilite; and these were confirmed with X-Ray diffraction on the bulk sample and clay-sized particles. X-Ray diffraction patterns shows distinctive peaks which highlight the dominance of Kaolinite (with 8 peaks in the pottery clay sample for both clay-sized particles and bulk material; while traces of other clay minerals like Illite and Halloysite and rock minerals like Mica, Feldspar and Chrysotile were also found. These results suggest that the clay possesses high viability in the manufacturing of ceramics, refractory bricks, paper, fertilizer and paint. The clay material can be used as a subgrade in road construction, since it possesses low swelling characteristics.

Novel sulfonated poly (ether ether ketone)/phosphonic acid-functionalized titania nanohybrid membrane by an in situ method for direct methanol fuel cells

Science.gov (United States)

Wu, Hong; Cao, Ying; Li, Zhen; He, Guangwei; Jiang, Zhongyi

2015-01-01

Sulfonated poly (ether ether ketone)/phosphonic acid-functionalized titania nanohybrid membranes are prepared by an in situ method using titanium tetrachloride (TiCl4) as inorganic precursor and amino trimethylene phosphonic acid (ATMP) as modifier. Phosphonic acid-functionalized titania nanoparticles with a uniform particle size of ∼50 nm are formed and dispersed homogeneously in the SPEEK matrix with good interfacial compatibility. Accordingly, the nanohybrid membranes display remarkably enhanced proton conduction property due to the incorporation of additional sites for proton transport and the formation of well-connected channels by bridging the hydrophilic domains in SPEEK matrix. The nanohybrid membrane with 6 wt. % of phosphonic acid-functionalized titania nanoparticles exhibits the highest proton conductivity of 0.334 S cm-1 at 65 °C and 100% RH, which is 63.7% higher than that of pristine SPEEK membrane. Furthermore, the as-prepared nanohybrid membranes also show elevated thermal and mechanical stabilities as well as decreased methanol permeability.

Pretest parametric calculations for the heated pillar experiment in the WIPP In-Situ Experimental Area

International Nuclear Information System (INIS)

Branstetter, L.J.

1983-03-01

Results are presented for a pretest parametric study of several configurations and heat loads for the heated pillar experiment (Room H) in the Waste Isolation Pilot Plant (WIPP) In Situ Experimental Area. The purpose of this study is to serve as a basis for selection of a final experiment geometry and heat load. The experiment consists of a pillar of undisturbed rock salt surrounded by an excavated annular room. The pillar surface is covered by a blanket heat source which is externally insulated. A total of five thermal and ten structural calculations are described in a four to five year experimental time frame. Results are presented which include relevant temperature-time histories, deformations, rock salt stress component and effective stress profiles, and maximum stresses in anhydrite layers which are in close proximity to the room. Also included are predicted contours of a conservative post-processed measure of potential salt failure. Observed displacement histories are seen to be highly dependent on pillar and room height, but insensitive to other geometrical variations. The use of a tensile cutoff across slidelines is seen to produce more accurate predictions of anhydrite maximum stress, but to have little effect on rock salt stresses. The potential for salt failure is seen to be small in each case for the time frame of interest, and is only seen at longer times in the center of the room floor

Mechanical properties of nano and bulk Fe pillars using molecular dynamics and dislocation dynamics simulation

Directory of Open Access Journals (Sweden)

S. K. Deb Nath

2017-10-01

Full Text Available Using molecular dynamics simulation, tension and bending tests of a Fe nanopillar are carried out to obtain its Young’s modulus and yield strength. Then the comparative study of Young’s modulus and yield strength of a Fe nanopillar under bending and tension are carried out varying its diameter in the range of diameter 1-15nm. We find out the reasons why bending Young’s modulus and yield strength of a Fe nanopillar are higher than those of tension Young’s modulus and yield strength of a Fe nanopillar. Using the mobility parameters of bulk Fe from the experimental study [N. Urabe and J. Weertman, Materials Science and Engineering 18, 41 (1975], its temperature dependent stress-strain relationship, yield strength and strain hardening modulus are obtained from the dislocation dynamics simulations. Strain rate dependent yield strength and strain hardening modulus of bulk Fe pillars under tension are studied. Temperature dependent creep behaviors of bulk Fe pillars under tension are also studied. To verify the soundness of the present dislocation dynamics studies of the mechanical properties of bulk Fe pillars under tension, the stress vs. strain relationship and dislocation density vs. strain of bulk Fe pillars obtained by us are compared with the published results obtained by S. Queyreau, G. Monnet, and B. Devincre, International Journal of Plasticity 25, 361 (2009.

Preparation of Nanocrystalline Titania Thin Films by Using Pure and Water-modified Supercritical Carbon Dioxide.

Czech Academy of Sciences Publication Activity Database

Sajfrtová, Marie; Cerhová, Marie; Dřínek, Vladislav; Daniš, S.; Matějová, L.

2016-01-01

Roč. 117, NOV 2016 (2016), s. 289-296 ISSN 0896-8446 R&D Projects: GA ČR GA14-23274S Institutional support: RVO:67985858 Keywords : titania thin films * supercritical carbon dioxide * crystallization Subject RIV: CA - Inorganic Chemistry Impact factor: 2.991, year: 2016

A micro-pillar array to trap magnetic beads in microfluidic systems

KAUST Repository

Gooneratne, Chinthaka Pasan; Kosel, Jü rgen

2012-01-01

A micro-pillar array (MPA) is proposed in this paper to trap and separate magnetic beads (MBs) in microfluidic systems. MBs are used in many biomedical applications due to being compatible in dimension to biomolecules, the large surface area

Wave liquefaction in soils with clay content

DEFF Research Database (Denmark)

Kirca, Özgür; Sumer, B. Mutlu; Fredsøe, Jørgen

2012-01-01

The paper presents the results of an experimental study of the influence of clay content (in silt-clay and sand-clay mixtures) on liquefaction beneath progressive waves. The experiments showed that the influence of clay content is very significant. Susceptibility of silt to liquefaction is increa...

Characterization of clay minerals

International Nuclear Information System (INIS)

Diaz N, C.; Olguin, M.T.; Solache R, M.; Alarcon H, T.; Aguilar E, A.

2002-01-01

The natural clays are the more abundant minerals on the crust. They are used for making diverse industrial products. Due to the adsorption and ion exchange properties of these, a great interest for developing research directed toward the use of natural clays for the waste water treatment has been aroused. As part of such researches it is very important to carry out previously the characterization of the interest materials. In this work the results of the mineral and elemental chemical composition are presented as well as the morphological characteristics of clay minerals from different regions of the Mexican Republic. (Author)

Mean wall-shear stress measurements using the micro-pillar shear-stress sensor MPS3

International Nuclear Information System (INIS)

Große, S; Schröder, W

2008-01-01

A new sensor to measure the mean turbulent wall-shear stress in turbulent flows is described. The wall-shear stress sensor MPS 3 has been tested in a well-defined fully developed turbulent pipe flow at Reynolds numbers Re b based on the bulk velocity U b and the pipe diameter D in the range of Re b = 10 000–20 000. The results demonstrate a convincing agreement of the mean wall-shear stress obtained with the new sensor technique with analytical and experimental results from the literature. The sensor device consists of a flexible micro-pillar that extends from the wall into the viscous sublayer. Bending due to the exerting fluid forces, the pillar-tip deflection serves as a measure for the local wall-shear stress. The sensor concept, calibration techniques, the achievable accuracy and error estimates, the fields of application and the sensor limits will be discussed. Furthermore, a first estimate of the pillar dynamic response will be derived showing the potential of the sensor to also measure the turbulent fluctuating wall-shear stress

Photovoltaic behaviour of titanyl phthalocyanine thin films and titania bilayer films

Czech Academy of Sciences Publication Activity Database

Drabik, M.; Zachary, A. M.; Choi, Y.; Hanuš, J.; Toušek, J.; Toušková, J.; Cimrová, Věra; Slavinská, D.; Biederman, H.; Hanley, L.

2008-01-01

Roč. 268, č. 1 (2008), s. 57-60 ISSN 1022-1360. [Microsymposium on Advanced Polymer Materials for Photonics and Electronics /47./. Prague, 15.07.2007-19.07.2007] R&D Projects: GA MŠk(CZ) 1M06031 Grant - others:National Science Foundation(US) CHE0241425; GA MŠk(CZ) 1P05ME754 Institutional research plan: CEZ:AV0Z40500505 Keywords : conjugated polymers * photovoltaics * phthalocyanine * thin films * titania Subject RIV: BM - Solid Matter Physics ; Magnetism

Characterization of nanocrystalline anatase titania: an in situ HTXRD study

International Nuclear Information System (INIS)

Jagtap, Neelam; Bhagwat, Mahesh; Awati, Preeti; Ramaswamy, Veda

2005-01-01

Nanocrystalline titania was synthesized by the hydrolysis of titanium iso-propoxide using ultrasonication. The powder XRD patterns of the sample were recorded in static air and vacuum using a Philips X-pert Pro diffractometer equipped with a high-temperature attachment (HTK16) from room temperature (298 K) to 1173 K and were analyzed by the Rietveld refinement technique. The anatase to rutile phase transformation was observed at 1173 K for the data collected in static air. Only 3% of anatase titania transformed to rutile when the experiments were carried out at 1173 K in vacuum. The phase transformation from anatase to rutile is accompanied by a continuous increase in the crystallite size of the anatase phase from 9 nm at room temperature to 28 nm at 873 K and then to 50 nm at 1173 K in air while the process of crystallite growth was suppressed in vacuum. A linear increase in the unit cell parameters 'a' and 'c', and thus, an overall linear increase in the unit cell volume was observed as a function of temperature in static air as well as vacuum. The lattice and volume thermal expansion coefficients (TEC), α a , α c and α V at 873 K are 8.57 x 10 -6 , 8.71 x 10 -6 and 25.91 x 10 -6 K -1 in air and 18.01 x 10 -6 , 14.95 x 10 -6 and 51.13 x 10 -6 K -1 in vacuum, respectively

Clays and Clay Minerals and their environmental application in Food Technology

Science.gov (United States)

del Hoyo Martínez, Carmen; Cuéllar Antequera, Jorge; Sánchez Escribano, Vicente; Solange Lozano García, Marina; Cutillas Díez, Raul

2013-04-01

The clay materials have led to numerous applications in the field of public health (del Hoyo, 2007; Volzone, 2007) having been demonstrated its effectiveness as adsorbents of all contaminants. Some biodegradable materials are used for for adsorption of chemical contaminants: lignins (Valderrabano et al., 2008) and also clays and clay minerals, whose colloidal properties, ease of generating structural changes, abundance in nature, and low cost make them very suitable for this kind of applications. Among the strategies used at present to preserve the quality of the water and this way to diminish the environmental risk that supposes the chemical pollution, stands out the use of adsorbents of under cost, already they are natural or modified, to immobilize these compounds and to avoid the pollution of the water with the consequent reduction of environmental and economic costs Thanks to the development of the science and the technology of the nourishment in the last 50 years, there have revealed itself several new substances that can fulfill beneficial functions in the food, and these substances, named food additives, are today within reach of all. The food additives recover a very important role in the complex nourishing supply. The additives fulfill several useful functions in the food, which often we give for sat. Nevertheless the widespread use of food additives in the food production also influences the public health. The food industries, which are very important for the economy, spill residues proved from its activity that they have to be controlled to evaluate the environmental impact and to offer the necessary information about the quantitative evaluation of the chemical risk of the use of food additives for the public health. We have studied the adsorption of several contaminants by natural or modified clays, searching their interaction mechanisms and the possible recycling of these materials for environmental purposes and prevention of the health. References

The molecular environment of the pillar-like features in the H II region G46.5-0.2

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Paron, S.; Celis Peña, M.; Ortega, M. E.; Fariña, C.; Petriella, A.; Rubio, M.; Ashley, R. P.

2017-10-01

At the interface of H II regions and molecular gas, peculiar structures appear, some of them with pillar-like shapes. Understanding their origin is important for characterizing triggered star formation and the impact of massive stars on the interstellar medium. In order to study the molecular environment and influence of radiation on two pillar-like features related to the H II region G46.5-0.2, we performed molecular line observations with the Atacama Submillimeter Telescope Experiment and spectroscopic optical observations with the Isaac Newton Telescope. From the optical observations, we identified the star that is exciting the H II region as spectral type O4-6. The molecular data allowed us to study the structure of the pillars and an HCO+ cloud lying between them. In this HCO+ cloud, which has no well-defined 12CO counterpart, we found direct evidence of star formation: two molecular outflows and two associated near-IR nebulosities. The outflow axis orientation is perpendicular to the direction of the radiation flow from the H II region. Several Class I sources are also embedded in this HCO+ cloud, showing that it is usual that young stellar objects (YSOs) form large associations occupying a cavity bounded by pillars. On the other hand, it was confirmed that the radiation-driven implosion (RDI) process is not occurring in one of the pillar tips.

Straightforward Generation of Pillared, Microporous Graphene Frameworks for Use in Supercapacitors.

Science.gov (United States)

Yuan, Kai; Xu, Yazhou; Uihlein, Johannes; Brunklaus, Gunther; Shi, Lei; Heiderhoff, Ralf; Que, Mingming; Forster, Michael; Chassé, Thomas; Pichler, Thomas; Riedl, Thomas; Chen, Yiwang; Scherf, Ullrich

2015-11-01

Microporous, pillared graphene-based frameworks are generated in a simple functionalization/coupling procedure starting from reduced graphene oxide. They are used for the fabrication of high-performance supercapacitor devices. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effects of focused ion beam milling on the compressive behavior of directionally solidified micro-pillars and the nanoindentation response of an electro-polished surface

International Nuclear Information System (INIS)

Shim, Sang Hoon; Bei, Hongbin; Miller, Michael K; Pharr, George Mathews; George, Easo P

2009-01-01

Focused ion beam (FIB) milling is the typical way in which micro-pillars are fabricated to study small-scale plasticity and size effects in uniaxial compression. However, FIB milling can introduce defects into the milled pillars. To investigate the effects of FIB damage on mechanical behavior, we tested Mo-alloy micro-pillars that were FIB milled following directional solidification, and compared their compressive response to pillars that were not FIB milled. We also FIB milled at glancing incidence a Mo-alloy single-crystal surface, and compared its nanoindentation response to an electro-polished surface of the same crystal. Consequences for the interpretation of data obtained from FIB milled micro-pillars are discussed

A family of porous lonsdaleite-e networks obtained through pillaring of decorated kagomé lattice sheets

KAUST Repository

Schoedel, Alexander; Boyette, Wesley; Wojtas, Łukasz; Eddaoudi, Mohamed; Zaworotko, Michael J.

2013-01-01

A new and versatile class of metal-organic materials (MOMs) with augmented lonsdaleite-e (lon-e-a) topology is presented herein. This family of lon-e nets are built by pillaring of hexagonal two-dimensional kagomé (kag) lattices constructed from well-known [Zn2(CO2R)4] paddlewheel molecular building blocks (MBBs) connected by 1,3- benzenedicarboxylate (bdc2-) linkers. The pillars are [Cr 3(μ3-O)(RCO2)]6 trigonal prismatic primary MBBs decorated by six pyridyl moieties (tp-PMBB-1). The three-fold symmetry (D3h) of tp-PMBB-1 is complementary with the alternating orientation of the axial sites of the paddlewheel MBBs and enables triple cross-linking of the kag layers by each pillar. These MOMs represent the first examples of axial-to-axial pillared undulating kag layers, and they are readily fine-tuned because the bdc2- moieties can be varied at their 5-position without changing the overall structure. This lon-e platform possesses functionalized hexagonal channels since the kag lattices are necessarily eclipsed. The effects of the substituent at the 5-positions of the bdc 2- linkers upon gas adsorption, particularly the heats of adsorption of carbon dioxide and methane, were studied. © 2013 American Chemical Society.

A family of porous lonsdaleite-e networks obtained through pillaring of decorated kagomé lattice sheets

KAUST Repository

Schoedel, Alexander

2013-09-25

A new and versatile class of metal-organic materials (MOMs) with augmented lonsdaleite-e (lon-e-a) topology is presented herein. This family of lon-e nets are built by pillaring of hexagonal two-dimensional kagomé (kag) lattices constructed from well-known [Zn2(CO2R)4] paddlewheel molecular building blocks (MBBs) connected by 1,3- benzenedicarboxylate (bdc2-) linkers. The pillars are [Cr 3(μ3-O)(RCO2)]6 trigonal prismatic primary MBBs decorated by six pyridyl moieties (tp-PMBB-1). The three-fold symmetry (D3h) of tp-PMBB-1 is complementary with the alternating orientation of the axial sites of the paddlewheel MBBs and enables triple cross-linking of the kag layers by each pillar. These MOMs represent the first examples of axial-to-axial pillared undulating kag layers, and they are readily fine-tuned because the bdc2- moieties can be varied at their 5-position without changing the overall structure. This lon-e platform possesses functionalized hexagonal channels since the kag lattices are necessarily eclipsed. The effects of the substituent at the 5-positions of the bdc 2- linkers upon gas adsorption, particularly the heats of adsorption of carbon dioxide and methane, were studied. © 2013 American Chemical Society.

The Issue of Data Protection and Data Security in the (Pre-Lisbon EU Third Pillar

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Maria O'Neill

2010-06-01

Full Text Available The key functional operability in the pre-Lisbon PJCCM pillar of the EU is the exchange of intelligence and information amongst the law enforcement bodies of the EU. The twin issues of data protection and data security within what was the EU’s third pillar legal framework therefore come to the fore. With the Lisbon Treaty reform of the EU, and the increased role of the Commission in PJCCM policy areas, and the integration of the PJCCM provisions with what have traditionally been the pillar I activities of Frontex, the opportunity for streamlining the data protection and data security provisions of the law enforcement bodies of the post-Lisbon EU arises. This is recognised by the Commission in their drafting of an amending regulation for Frontex , when they say that they would prefer “to return to the question of personal data in the context of the overall strategy for information exchange to be presented later this year and also taking into account the reflection to be carried out on how to further develop cooperation between agencies in the justice and home affairs field as requested by the Stockholm programme.” The focus of the literature published on this topic, has for the most part, been on the data protection provisions in Pillar I, EC. While the focus of research has recently sifted to the previously Pillar III PJCCM provisions on data protection, a more focused analysis of the interlocking issues of data protection and data security needs to be made in the context of the law enforcement bodies, particularly with regard to those which were based in the pre-Lisbon third pillar. This paper will make a contribution to that debate, arguing that a review of both the data protection and security provision post-Lisbon is required, not only in order to reinforce individual rights, but also inter-agency operability in combating cross-border EU crime. The EC’s provisions on data protection, as enshrined by Directive 95/46/EC, do not apply

Mineral Acquisition from Clay by Budongo Forest Chimpanzees.

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Vernon Reynolds

Full Text Available Chimpanzees of the Sonso community, Budongo Forest, Uganda were observed eating clay and drinking clay-water from waterholes. We show that clay, clay-rich water, and clay obtained with leaf sponges, provide a range of minerals in different concentrations. The presence of aluminium in the clay consumed indicates that it takes the form of kaolinite. We discuss the contribution of clay geophagy to the mineral intake of the Sonso chimpanzees and show that clay eaten using leaf sponges is particularly rich in minerals. We show that termite mound soil, also regularly consumed, is rich in minerals. We discuss the frequency of clay and termite soil geophagy in the context of the disappearance from Budongo Forest of a formerly rich source of minerals, the decaying pith of Raphia farinifera palms.

Mineral Acquisition from Clay by Budongo Forest Chimpanzees.

Science.gov (United States)

Reynolds, Vernon; Lloyd, Andrew W; English, Christopher J; Lyons, Peter; Dodd, Howard; Hobaiter, Catherine; Newton-Fisher, Nicholas; Mullins, Caroline; Lamon, Noemie; Schel, Anne Marijke; Fallon, Brittany

2015-01-01

Chimpanzees of the Sonso community, Budongo Forest, Uganda were observed eating clay and drinking clay-water from waterholes. We show that clay, clay-rich water, and clay obtained with leaf sponges, provide a range of minerals in different concentrations. The presence of aluminium in the clay consumed indicates that it takes the form of kaolinite. We discuss the contribution of clay geophagy to the mineral intake of the Sonso chimpanzees and show that clay eaten using leaf sponges is particularly rich in minerals. We show that termite mound soil, also regularly consumed, is rich in minerals. We discuss the frequency of clay and termite soil geophagy in the context of the disappearance from Budongo Forest of a formerly rich source of minerals, the decaying pith of Raphia farinifera palms.

Influence of carbonate micro-fabrics on the failure strength of Callovo-Oxfordian clay stones and Opalinus Clay

International Nuclear Information System (INIS)

Klinkenberg, M.; Dohrmann, R.; Kaufhold, S.; Siegesmund, S.

2010-01-01

Document available in extended abstract form only. The potential use of clay stones as host rock for radioactive waste disposal is currently investigated. For this application, hydraulic conductivity, swelling properties, water uptake, rheological and mechanical properties are of great importance. The Opalinus Clay (Mont-Terri, Switzerland) and the Callovo- Oxfordian clay stone (France) are the most frequently studied clay stones. One goal is to develop a numerical model being able to predict the mechanical behaviour of clay stones under repository-like conditions. Experimental investigations reveal that Opalinus Clay and Callovo-Oxfordian clay stone behave different with respect to the dependence of mechanical strength on the carbonate content. The failure strength of Opalinus Clay decreases with increasing carbonate content, whereas it increases with increasing carbonate content when Callovo-Oxfordian clay stone is considered. To supply proper data and enable reliable model assumptions, the use of suitable experimental techniques for the description of the microstructure is indispensable. After mechanical testing, samples were taken perpendicular to the bedding and polished sections were prepared. The micro-fabrics were investigated using scanning electron microscopy (SEM) and image analysis. Backscattered electron (BSE) images were used for the image analysis because carbonates can be extracted by grey level analysis. The image analysis of the extracted particles provides the following parameters: area, longest and shortest axis of an ellipse (surrounding the particle), perimeter, the angle to horizontal (longest axis), and the aspect ratio (longest axis/shortest axis). Callovo-Oxfordian clay stone shows a homogenous distribution of fine-grained carbonates and dovetail connection of calcium carbonate with the clayey matrix. In contrast Opalinus Clay shows large elongated carbonate grains (high aspect ratios) of shell fragments. Cracks are mostly related to these

Preparation of nanocomposites polyurethane water bone with clay montmorillonite sodica and organophilic clay

International Nuclear Information System (INIS)

Garcia, Claudia P.; Delpech, Marcia C.; Coutinho, Fernanda M.B.; Mello, Ivana L.

2009-01-01

Nanocomposites based on water bone polyurethane (NWPU's) were synthesized based on poli(propylene glycol), dimethylolpropionic acid (DMPA), isophorone diisocyanate (IPDI) and hydrazine (HYD), as chain extender. Two kinds of clays were employed: hydrophilic and organophilic. The nanocomposites were characterized by infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electronic microscopy (SEM) and the mechanical properties were evaluated. The FTIR results showed the presence of specific groups of clay and the XRD suggested that occurred their intercalation/exfoliation through polyurethane matrix. The mechanical resistance of the systems showed significant increase when compared to water dispersions synthesized without clay. (author)

Porous Structures in Stacked, Crumpled and Pillared Graphene-Based 3D Materials.

Science.gov (United States)

Guo, Fei; Creighton, Megan; Chen, Yantao; Hurt, Robert; Külaots, Indrek

2014-01-01

Graphene, an atomically thin material with the theoretical surface area of 2600 m 2 g -1 , has great potential in the fields of catalysis, separation, and gas storage if properly assembled into functional 3D materials at large scale. In ideal non-interacting ensembles of non-porous multilayer graphene plates, the surface area can be adequately estimated using the simple geometric law ~ 2600 m 2 g -1 /N, where N is the number of graphene sheets per plate. Some processing operations, however, lead to secondary plate-plate stacking, folding, crumpling or pillaring, which give rise to more complex structures. Here we show that bulk samples of multilayer graphene plates stack in an irregular fashion that preserves the 2600/N surface area and creates regular slot-like pores with sizes that are multiples of the unit plate thickness. In contrast, graphene oxide deposits into films with massive area loss (2600 to 40 m 2 g -1 ) due to nearly perfect alignment and stacking during the drying process. Pillaring graphene oxide sheets by co-deposition of colloidal-phase particle-based spacers has the potential to partially restore the large monolayer surface. Surface areas as high as 1000 m 2 g -1 are demonstrated here through colloidal-phase deposition of graphene oxide with water-dispersible aryl-sulfonated ultrafine carbon black as a pillaring agent.

Potassium effects on kinetics of propane oxydehydrogenation on vanadia-titania catalyst

International Nuclear Information System (INIS)

Grabowski, R.; Samson, K.

2003-01-01

Oxidative dehydrogenation of propane (ODH) over V 2 O 5 /TiO 2 and V 2 O 5 /TiO 2 doped with K was carried out by measuring conversions and selectiveness for various feed compositions, contact times and temperatures. The results obtained for both catalysts were interpreted on the basis of the mechanism, in which propene is formed through Eley-Rideal sequence of steps, i.e. without participation of the adsorbed propane species. Kinetic constants (activation energies, pre-exponential factors) for the model of ODH reaction of propane on these catalysts, obtained on the basis of steady-state results, are given. Addition of K to vanadia-titania catalysts leads to decrease of total combustion of propane and consecutive combustion of propene. It has been found that the direct propane total oxidation is 5 - 9 times lower than that of the consecutive propene oxidation and is almost temperature independent for potassium doped catalyst, whereas it quickly decreases with temperature for a non-doped catalyst. Secondly, the addition of K to a vanadia-titania catalyst decreases the activation energies for propene formation (k 1 ), parallel formation of CO x (k 3 ) and reoxidation of the catalyst (k os ). Potassium exhibits a stronger inhibitory effect on the secondary propene combustion, what reflects the lower activity of V 5+ cations modified by the strongly basic alkali oxide species. (author)

Crude oil polycyclic aromatic hydrocarbons removal via clay-microbe-oil interactions: Effect of acid activated clay minerals.

Science.gov (United States)

Ugochukwu, Uzochukwu C; Fialips, Claire I

2017-07-01

Acid treatment of clay minerals is known to modify their properties such as increase their surface area and surface acidity, making them suitable as catalysts in many chemical processes. However, the role of these surface properties during biodegradation processes of polycyclic aromatic hydrocarbons (PAHs) is only known for mild acid (0.5 M Hydrochloric acid) treated clays. Four different clay minerals were used for this study: a montmorillonite, a saponite, a palygorskite and a kaolinite. They were treated with 3 M hydrochloric acid to produce acid activated clay minerals. The role of the acid activated montmorillonite, saponite, palygorskite and kaolinite in comparison with the unmodified clay minerals in the removal of PAHs during biodegradation was investigated in microcosm experiments. The microcosm experiments contained micro-organisms, oil, and clays in aqueous medium with a hydrocarbon degrading microorganism community predominantly composed of Alcanivorax spp. Obtained results indicated that acid activated clays and unmodified kaolinite did not enhance the biodegradation of the PAHs whereas unmodified montmorillonite, palygorskite and saponite enhanced their biodegradation. In addition, unmodified palygorskite adsorbed the PAHs significantly due to its unique channel structure. Copyright © 2017 Elsevier Ltd. All rights reserved.

From clay bricks to deep underground storage

International Nuclear Information System (INIS)

2012-05-01

This booklet issued by the Swiss National Cooperative for the Disposal of Radioactive Waste NAGRA takes a look at the use of clay strata for the storage of radioactive wastes in deep-lying repositories. First of all, a geological foray is made concerning the history of the use of clay and its multifarious uses. The characteristics of clay and its composition are examined and its formation in the geological past is explained. In particular Opalinus clay is looked at and the structures to be found are discussed. The clay's various properties and industrial uses are examined and its sealing properties are examined. Also, Bentonite clay is mentioned and work done by Nagra and co-researchers is noted

Microstructure and Thermal Properties of Polypropylene/Clay Nanocomposites with TiCl4/MgCl2/Clay Compound Catalyst

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Limei Wang

2015-01-01

Full Text Available Polypropylene (PP/clay nanocomposites were synthesized by in situ intercalative polymerization with TiCl4/MgCl2/clay compound catalyst. Microstructure and thermal properties of PP/clay nanocomposites were studied in detail. Fourier transform infrared (FTIR spectra indicated that PP/clay nanocomposites were successfully prepared. Both wide-angle X-ray diffraction (XRD and transmission electron microscopy (TEM examination proved that clay layers are homogeneously distributed in PP matrix. XRD patterns also showed that the α phase was the dominate crystal phase of PP in the nanocomposites. Thermogravimetric analysis (TGA examinations confirmed that thermal stability of PP/clay nanocomposites was markedly superior to pure PP. Differential scanning calorimetry (DSC scans showed that the melt temperature and the crystallinity of nanocomposites were slightly lower than those of pure PP due to crystals imperfections.

Single macroscopic pillars as model system for bioinspired adhesives: influence of tip dimension, aspect ratio, and tilt angle.

Science.gov (United States)

Micciché, Maurizio; Arzt, Eduard; Kroner, Elmar

2014-05-28

The goal of our study is to better understand the design parameters of bioinspired dry adhesives inspired by geckos. For this, we fabricated single macroscopic pillars of 400 μm diameter with different aspect ratios and different tip shapes (i.e., flat tips, spherical tips with different radii, and mushroom tips with different diameters). Tilt-angle-dependent adhesion measurements showed that although the tip shape of the pillars strongly influences the pull-off force, the pull-off strength is similar for flat and mushroom-shaped tips. We found no tilt-angle dependency of adhesion for spherical tip structures and, except for high tilt angle and low preload experiments, no tilt-angle effect for mushroom-tip pillars. For flat-tip pillars, we found a strong influence of tilt angle on adhesion, which decreased linearly with increasing aspect ratio. The experiments show that for the tested aspect ratios between 1 and 5, a linear decrease of tilt-angle dependency is found. The results of our studies will help to design bioinspired adhesives for application on smooth and rough surfaces.

Sensitization of Xanthophylls-Chlorophyllin Mixtures on Titania Solar Cells

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Indriana Kartini

2015-03-01

Full Text Available Co-sensitization of natural dyes on TiO2 for dye-sensitized solar cell (DSSC was proposed between chlorophyllin (C and xanthophylls (X at various volume ratios of C/X. Chlorophyllin is chlorophyll derivative providing -COOH groups essential for binding to TiO2. The chlorophyll was extracted from dried spinach (amaranthus viridis leaves in a mixture of methanol-acetone (70%:30%. Chlorophyll extract dye was obtained after partition of the crude extracts in diethyl ether solution. Then, it was hydrolyzed under alkaline condition to get chlorophyllin. Xanthophyll was extracted from fresh petal of chrysanthemum (chrysanthemum indicum flowers. Blending of chlorophyllin and xanthophyll was carried out at various volume ratios of C to X (1:0, 5:1, 1:1, 1:5, 0:1. Titania solar cells were constructed in sandwich system of conducting glass-titania/dyes as the photoanode and conducting glass-platinum as the photocathode. Electrolyte solution containing I-/I3- was inserted between the electrodes by capillary action. All dye extracts and blending solutions were analyzed by UV-Vis spectrophotometer. It is shown that the absorption spectra of blending dyes are complimentary in the visible region resulted in a panchromatic response of the dyes. From the cyclic voltammogram of the dyes and blended-dyes, it is found that the energy level of xanthophyll is the lowest. The I-V test at 100 mw/cm2 irradiation confirmed that the energy conversion efficiency (h of the blended dyes of xanthophyll and chlorophyllin-sensitized solar cell resulted in significant improvement than those of the single dye. Beneficially, the mixed dyes can be adsorbed from solution blend using single dipping step.

Iodide Sorption to Clays and the Relationship to Surface Charge and Clay Texture - 12356

Energy Technology Data Exchange (ETDEWEB)

Miller, Andrew; Kruichiak, Jessica; Tellez, Hernesto; Wang, Yifeng [Sandia National Laboratories, Albuquerque, NM 87185 (United States)

2012-07-01

Iodine is assumed to behave conservatively in clay barriers around nuclear waste repositories and in natural sediments. Batch experiments tend to show little to no sorption, while in column experiments iodine is often retarded relative to tritiated water. Current surface complexation theory cannot account for negatively charged ion sorption to a negatively charged clay particle. Surface protonation and iodide sorption to clay minerals were examined using surface titrations and batch sorption experiments with a suite of clay minerals. Surface titrations were completed spanning a range of both pH values and ionic strengths. For reference, similar titrations were performed on pure forms of an Al-O powder. The titration curves were deconvoluted to attain the pKa distribution for each material at each ionic strength. The pKa distribution for the Al-O shows two distinct peaks at 4.8 and 7.5, which are invariant with ionic strength. The pKa distribution of clays was highly variable between the different minerals and as a function of ionic strength. Iodide sorption experiments were completed at high solid:solution ratios to exacerbate sorption properties. Palygorskite and kaolinite had the highest amount of iodide sorption and montmorillonite had the least. (authors)

Series-Interconnected Plastic Dye-Sensitized Solar Cells Prepared by Low- Temperature Binder-Free Titania Paste

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Erlyta Septa Rosa

2014-10-01

Full Text Available The aim of this research is to study dye-sensitized solar cells (DSSC. This was implemented on a flexible polyethylene terephthalate (PET substrate using a mixture of transparent and scattered mesoporous anatase-titania as the electron transport layer for the photoelectrode. This mixture of anatase titania performed a dual function of light scattering and efficient dye absorption. In this study, a porous nano-TiO2 film was prepared on indium tin oxide (ITO coated polyethylene terephthalate (PET by using a binder-free titania paste; on it, a DSSC was fabricated. The paste which contained a mixture of TiO2 nanoparticles, acid chloride, and ethanol was printed on two patterns of 1x6 cm2 active areas followed by sintered at 120 ºC to form TiO2 films. A commercial dye, N719, was adsorbed on the surface of TiO2 films and assembled to two platinized conductive plastic patterns to form a counter electrode and thus a sandwich-type dye cell. Finally, a solution of KI/I2 electrolytes was injected into the cell in which a couple of sandwich-type dye cells with an active area of 6 cm2 for each cell were series interconnected with a z-type interconnection between the photoelectrode of one cell and the counter electrode of another cell. The cell performance was characterized by employing simulated solar light at an intensity of 50 mW/cm2. The results showed interconnected cells generating a short-circuit photocurrent density of 2.34 mA/cm2, an open-circuit voltage of 1.10 volt, and overall 0.172% power conversion efficiency.