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Sample records for intercalated layered double

  1. Polysulfide intercalated layered double hydroxides for metal capture applications

    Science.gov (United States)

    Kanatzidis, Mercouri G.; Ma, Shulan

    2017-04-04

    Polysulfide intercalated layered double hydroxides and methods for their use in vapor and liquid-phase metal capture applications are provided. The layered double hydroxides comprise a plurality of positively charged host layers of mixed metal hydroxides separated by interlayer spaces. Polysulfide anions are intercalated in the interlayer spaces.

  2. Polysulfide intercalated layered double hydroxides for metal capture applications

    Energy Technology Data Exchange (ETDEWEB)

    Kanatzidis, Mercouri G.; Ma, Shulan

    2017-04-04

    Polysulfide intercalated layered double hydroxides and methods for their use in vapor and liquid-phase metal capture applications are provided. The layered double hydroxides comprise a plurality of positively charged host layers of mixed metal hydroxides separated by interlayer spaces. Polysulfide anions are intercalated in the interlayer spaces.

  3. Electronic spectra of anions intercalated in layered double hydroxides

    Indian Academy of Sciences (India)

    S Radha; P Vishnu Kamath

    2013-10-01

    Transition metal complexes intercalated in layered double hydroxides have a different electronic structure as compared to their free state owing to their confinement within the interlayer gallery. UV–Vis absorptions of the intercalated complex anions show a significant shift as compared to their free state. The ligand to metal charge transfer transitions of the ferricyanide anion show a red shift on intercalation. The ferrocyanide ion shows a significant blue shift of – bands due to the increased separation between 2g and g levels on intercalation. MnO$^{-}_{4}$ ion shows a blue shift in its ligand to metal charge transfer transition since the non-bonding 1 level of oxygen from which the transition arises is stabilized.

  4. Cellular Uptake Behavior of Fluorescein: Intercalated Layered Double Hydroxide

    Science.gov (United States)

    Tanaka, Miyuki; Aisawa, Sumio; Hirahara, Hidetoshi; Narita, Eiichi; Yin, Shu; Sato, Tsugio

    2012-06-01

    In order to define the ability of layered double hydroxide (LDH) as materials for drug delivery, fluorescein (Fluo) anion intercalated LDH (Fluo/LDH) was synthesized by hydrothermal treatment and observed the cellular uptake of the Fluo/LDH for mammalian cell (L929). The synthesized Fluo/LDH showed a LDH structure, high fluorescence and low cytotoxicity. According to the fluorescence, confocal and TEM images of cells, the Fluo/LDH seemed to be internalized into the L929 cell by cellular endocytosis and dissolved inside the cell to exhibit the fluorescence of cellular cytoplasm.

  5. Preferential Intercalation of Pyridinedicarboxylates into Layered Double Hydroxides

    Institute of Scientific and Technical Information of China (English)

    李蕾; 莫丹; 陈大舟

    2005-01-01

    Intercalation of 2,3-,2,4-,2,5-,2,6-,3,4-,or3,5-pyridincdicarboxylate into the layered double hydroxide (LDH),[Mg0.73AIo.27(OH)2](CO3)0.14*1.34H2O was carried out by the reconstruction method in the molar ratio of organic acid: calcined LDH=3:8, in 80% alcoholic aqueous solution at 70℃. Selective reaction was observed in com-petitive experiments involving an equal concentration pairs of acids. The preference order of the organic acids intercalated into the Mg-Al-LDH was found to be in the order of 2,3-pyridinedicarboxylate>2,5-pyridinedicarboxylate>2,4-pyridinedicarboxylate>3,5-pyridinedicarboxylate>3,4-pyridinedicarboxylate>2,6-pyridinedic arboxylate. The structures of the intercalates formed by the reaction of six guests with Mg-Al-LDH were characterized by X-ray diffraction, infrared and thermogravimetry techniques. And the charge density on the oxygens of each of the carboxylate groups for the six anions was investigated utilizing ab initio (HF/6-31G) method by G98w. From the X-ray diffraction data, the guest size and the charge density of the oxygens of the guest, the orientation of 2,3-,2,4-,2,5-,2,6-,3,4-, or 3,5-pyridinedicarboxylate anions between the layers was determined and the preferential intercalation mechanism was discussed. These results indicate the possibility of a molecular recognition ability of LDH and it would be exploited for the chemical separation of some anions from solution.

  6. Intercalation of Layered Silicates, Layered Double Hydroxides, and Lead Iodide: Synthesis, Characterization and Properties.

    Science.gov (United States)

    Mehrotra, Vivek

    Layered silicates, layered double hydroxides, and lead iodide are lamellar solids that can incorporate guest species into the galleries between their layers. Various intercalated forms of these layered materials have been synthesized and their properties studied. The dielectric behavior of pristine fluorohectorite, a typical layered silicate, and Zn-Al layered double hydroxide is explained by considering the structural ordering and mobility of the intercalated water molecules, as well as models invoking fractal time processes and fractal structure. Intercalative polymerization of aniline and pyrrole into fluorohectorite leads to a multilayered structure consisting of single polymer chains alternately stacked with the 9.6 A thick silicate layers. The polymer chains are confined to the quasi two-dimensional interlayer space between the rigid host layers. The hybrid films exhibit highly anisotropic properties. The optical, electrical and mechanical behavior is discussed in terms of the molecular confinement of the polymer chains. Ethylenediamine functionalized C _{60} clusters have also been intercalated into fluorohectorite via an ion-exchange procedure. Intercalation results in an improved thermal stability of the functionalized C_{60} clusters. Rutherford backscattering spectrometry has been used to elucidate the mechanism of intercalative ion exchange of silver in muscovite mica, a layered silicate with a layer charge density of 2e per unit cell. It is proposed that ion-exchange progresses by intercalating successive galleries through the edges of the mica layers. Guest-host interactions have been studied in the system aniline-PbI_2. The optical and structural effects of aniline intercalation in lead iodide thin films is discussed. Intercalation leads to a large shift in the optical band gap of PbI_2. The observed change in band gap is not only due to the increased separation between the PbI_2 layers but also because of an electrostatic interaction between the

  7. Intercalation and controlled release properties of vitamin C intercalated layered double hydroxide

    Science.gov (United States)

    Gao, Xiaorui; Lei, Lixu; O'Hare, Dermot; Xie, Juan; Gao, Pengran; Chang, Tao

    2013-07-01

    Two drug-inorganic composites involving vitamin C (VC) intercalated in Mg-Al and Mg-Fe layered double hydroxides (LDHs) have been synthesized by the calcination-rehydration (reconstruction) method. Powder X-ray diffraction (XRD), Fourier transform infrared (FTIR), and UV-vis absorption spectroscopy indicate a successful intercalation of VC into the interlayer galleries of the LDH host. Studies of VC release from the LDHs in deionised water and in aqueous CO32- solutions imply that Mg3Al-VC LDH is a better controlled release system than Mg3Fe-VC LDH. Analysis of the release profiles using a number of kinetic models suggests a solution-dependent release mechanism, and a diffusion-controlled deintercalation mechanism in deionised water, but an ion exchange process in CO32- solution.

  8. Methotrexate intercalated ZnAl-layered double hydroxide

    Science.gov (United States)

    Chakraborty, Manjusha; Dasgupta, Sudip; Soundrapandian, Chidambaram; Chakraborty, Jui; Ghosh, Swapankumar; Mitra, Manoj K.; Basu, Debabrata

    2011-09-01

    The anticancerous drug methotrexate (MTX) has been intercalated into an ZnAl-layered double hydroxide (LDH) using an anion exchange technique to produce LDH-MTX hybrids having particle sizes in the range of 100-300 nm. X-ray diffraction studies revealed increases in the basal spacings of ZnAl-LDH-MTX hybrid on MTX intercalation. This was corroborated by the transmission electron micrographs, which showed an increase in average interlayer spacing from 8.9 Å in pristine LDH to 21.3 Å in LDH-MTX hybrid. Thermogravimetric analyses showed an increase in the decomposition temperature for the MTX molecule in the LDH-MTX hybrid indicating enhanced thermal stability of the drug molecule in the LDH nanovehicle. The cumulative release profile of MTX from ZnAl-LDH-MTX hybrids in phosphate buffer saline (PBS) at pH 7.4 was successfully sustained for 48 h following Rigter-Peppas model release kinetics via diffusion.

  9. Synthesis of ACECLOFENAC/HYDROXYPROPYL-β-CYCLODEXTRIN Intercalated Layered Double Hydroxides and Controlled Release Properties

    Science.gov (United States)

    Li, Shifeng; Shen, Yanming; Liu, Dongbin; Fan, Lihui; Wu, Keke; Xiao, Min

    2013-04-01

    Aceclofenac (AC)/hydroxypropyl-β-cyclodextrin (HP-β-CD) complex intercalated layered double hydroxides (LDHs) have been synthesized by reconstruction method. X-ray diffraction, Fourier transform infrared and thermal gravimetric analyses indicated a successful intercalation of AC/HP-β-CD complex into the LDHs gallery. The AC release properties were also studied in different pH values buffer solution. The results indicate that the AC/HP-β-CD intercalated LDH has a potential application in drug delivery agent.

  10. Synthesis and characterization of laurate-intercalated Mg–Al layered double hydroxide prepared by coprecipitation

    DEFF Research Database (Denmark)

    Gerds, Nathalie Christiane; Katiyar, Vimal; Koch, Christian Bender

    2012-01-01

    Effective utilization of layered double hydroxides (LDH) for industrial applications requires the synthesis of pure and well-defined LDH phases. In the present study, dodecanoate (laurate) anions were intercalated into Mg–Al-layered double hydroxide (LDH-C12) by coprecipitation in the presence...... intercalated structure, but we here demonstrate it to be magnesium laurate (Mg-C12). The LDH-C12 compound showed high structural order with a basal spacing of 2.41nm. Fourier-transform IR-spectra confirmed the intercalation of the laurate anions in the interlayer. Transmission electron microscopy showed plate...

  11. Structure and thermal decomposition of sulfated β-cyclodextrin intercalated in a layered double hydroxide

    Science.gov (United States)

    Wang, Ji; Wei, Min; Rao, Guoying; Evans, David G.; Duan, Xue

    2004-01-01

    The sodium salt of hexasulfated β-cyclodextrin has been synthesized and intercalated into a magnesium-aluminum layered double hydroxide by ion exchange. The structure, composition and thermal decomposition behavior of the intercalated material have been studied by variable temperature X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), inductively coupled plasma emission spectroscopy (ICP), and thermal analysis (TG-DTA) and a model for the structure has been proposed. The thermal stability of the intercalated sulfated β-cyclodextrin is significantly enhanced compared with the pure form before intercalation.

  12. Interlayer Structure of Bioactive Molecule, 2-Aminoethanesulfonate, Intercalated into Calcium-Containing Layered Double Hydroxides

    Directory of Open Access Journals (Sweden)

    Tae-Hyun Kim

    2012-01-01

    Full Text Available We have successfully intercalated 2-aminoethanesulfonate, a well-known biomolecule taurine, into calcium-containing layered double hydroxides via optimized solid phase intercalation. According to X-ray diffraction patterns and infrared spectroscopy, it was revealed that the intercalated taurine molecules were each directly coordinated to other calcium cation and arranged in a zig-zag pattern. Scanning electron microscopy showed that the particle size and morphology of the LDHs were not affected by the solid phase intercalation, and the surface of intercalates was covered by organic moieties. From ninhydrin amine detection tests, we confirmed that most of the taurine molecules were well stabilized between the calcium-containing LDH layers.

  13. Intercalation of papain enzyme into hydrotalcite type layered double hydroxide

    Science.gov (United States)

    Zou, N.; Plank, J.

    2012-09-01

    Intercalation of proteolytic enzyme papain into hydrotalcite type LDH structure was achieved by controlled co-precipitation at pH=9.0 in the presence of papain. Characterization of the MgAl-papain-LDH phase was carried out using X-ray powder diffraction (XRD), elemental analysis, infrared spectroscopy (IR) and thermogravimetry (TG). According to XRD, papain was successfully intercalated. The d-value for the basal spacing of MgAl-papain-LDH was found at ˜5.3 nm. Consequently, original papain (hydrodynamic diameter ˜7.2 nm) attains a compressed conformation during intercalation.Formation of MgAl-papain-LDH was confirmed by elemental analysis and transmission electron microscopy (TEM). Under SEM, MgAl-papain-LDH phases appear as nanothin platelets which are intergrown to flower-like aggregates. Steric size and activity of the enzyme was retained after deintercalation from MgAl-LDH framework, as was evidenced by light scattering and UV/vis measurements. Thus, papain is not denatured during intercalation, and LDH is a suitable host structure which can provide a time-controlled release of the biomolecule.

  14. Adsorption and intercalation of anionic surfactants onto layered double hydroxides—XRD study

    Indian Academy of Sciences (India)

    R Anbarasan; W D Lee; S S Im

    2005-04-01

    Layered double hydroxides (LDH) with brucite like structure was modified with various anionic surfactants containing sulfonate, carboxyl, phosphonate and sulfate end group through ion-exchange method. XRD reports indicated that the sulfonate group containing surfactants led to an adsorption process whereas the sulfate, carboxyl and phosphonate group containing surfactant led to an intercalation process. This can be evidenced from the change in basal spacing of LDH. The presence of anionic surfactants in the LDH was supported by FTIR spectroscopy. The FTIR spectrum indicated that complete removal of carbonate anion from the inter layer space of LDH is very difficult. The phosphonate intercalated HT showed less thermal stability than pristine LDH.

  15. Layered double hydroxides as supports for intercalation and sustained release of antihypertensive drugs

    Science.gov (United States)

    Xia, Sheng-Jie; Ni, Zhe-Ming; Xu, Qian; Hu, Bao-Xiang; Hu, Jun

    2008-10-01

    Zn/Al layered double hydroxides (LDHs) were intercalated with the anionic antihypertensive drugs Enalpril, Lisinopril, Captopril and Ramipril by using coprecipitation or ion-exchange technique. TG-MS analyses suggested that the thermal stability of Ena -, Lis - (arranged with monolayer, resulted from X-ray diffraction (XRD) and Fourier transform infrared spectra (FT-IR) analysis was enhanced much more than Cap - and Ram - (arranged with bilayer). The release studies show that the release rate of all samples markedly decreased in both pH 4.25 and 7.45. However, the release time of Ena -, Lis - were much longer compared with Cap -, Ram - in both pH 4.25 and 7.45, it is possible that the intercalated guests, arranged with monolayer in the interlayer, show lesser repulsive force and strong affinity with the LDH layers. And the release data followed both the Higuchi-square-root law and the first-order equation well. Based on the analysis of batch release, intercalated structural models as well as the TG-DTA results, we conclude that for drug-LDH, stronger the affinity between intercalated anions and the layers is, better the thermal property and the stability to the acid attack of drug-LDH, and the intercalated anions are easier apt to monolayer arrangement within the interlayer, were presented.

  16. Mechanochemical synthesis and intercalation of Ca(II)Fe(III)-layered double hydroxides

    Energy Technology Data Exchange (ETDEWEB)

    Ferencz, Zs.; Szabados, M.; Varga, G.; Csendes, Z. [Department of Organic Chemistry, University of Szeged, Dóm tér 8, Szeged H-6720 (Hungary); Materials and Solution Structure Research Group, Institute of Chemistry, University of Szeged, Aradi Vértanúk tere 1, Szeged H-6720 (Hungary); Kukovecz, Á. [Department of Applied and Environmental Chemistry, University of Szeged, Rerrich Béla tér 1, Szeged H-6720 (Hungary); MTA-SZTE “Lendület” Porous Nanocomposites Research Group, Rerrich Béla tér 1, Szeged H-6720 (Hungary); Kónya, Z. [Department of Applied and Environmental Chemistry, University of Szeged, Rerrich Béla tér 1, Szeged H-6720 (Hungary); MTA-SZTE Reaction Kinetics and Surface Chemistry Research Group, Rerrich Béla tér 1, Szeged H-6720 (Hungary); Carlson, S. [MAX IV Laboratory, Ole Römers väg 1, Lund SE-223 63 (Sweden); Sipos, P. [Materials and Solution Structure Research Group, Institute of Chemistry, University of Szeged, Aradi Vértanúk tere 1, Szeged H-6720 (Hungary); Department of Inorganic and Analytical Chemistry, University of Szeged, Dóm tér 7, Szeged H-6720 (Hungary); and others

    2016-01-15

    A mechanochemical method (grinding the components without added water – dry grinding, followed by further grinding in the presence of minute amount of water or NaOH solution – wet grinding) was used in this work for the preparation and intercalation of CaFe-layered double hydroxides (LDHs). Both the pristine LDHs and the amino acid anion (cystinate and tyrosinate) intercalated varieties were prepared by the two-step grinding procedure in a mixer mill. By systematically changing the conditions of the preparation method, a set of parameters could be determined, which led to the formation of close to phase-pure LDH. The optimisation procedure was also applied for the intercalation processes of the amino acid anions. The resulting materials were structurally characterised by a range of methods (X-ray diffractometry, scanning electron microscopy, energy dispersive analysis, thermogravimetry, X-ray absorption and infra-red spectroscopies). It was proven that this simple mechanochemical procedure was able to produce complex organic–inorganic nanocomposites: LDHs intercalated with amino acid anions. - Graphical abstract: Amino acid anion-Ca(II)Fe(III)-LDHs were successfully prepared by a two-step milling procedure. - Highlights: • Synthesis of pristine and amino acid intercalated CaFe-LDHs by two-step milling. • Identifying the optimum synthesis and intercalation parameters. • Characterisation of the samples with a range of instrumental methods.

  17. Preparation and characterization of trans-RhCl(CO)(TPPTS) 2-intercalated layered double hydroxides

    Science.gov (United States)

    Zhang, Xian; Wei, Min; Pu, Min; Li, Xianjun; Chen, Hua; Evans, David G.; Duan, Xue

    2005-09-01

    trans-RhCl(CO)(TPPTS) 2 (TPPTS= tris( m-sulfonatophenyl)phosphine) has been intercalated into Zn-Al layered double hydroxides (LDHs) by the method of ion exchange. The structure, composition and thermal stability of the composite material have been characterized by powder X-ray diffraction, Fourier transform infrared and 31P solid-state magic-angle spinning nuclear magnetic resonance spectroscopy, elemental analysis, thermogravimetry, and differential thermal analysis. The geometry of trans-RhCl(CO)(TPPTS) 2 was fully optimized using the PM3 semiempirical molecular orbital method, and a schematic model for the intercalated species has been proposed. The thermal stability of trans-RhCl(CO)(TPPTS) 2 is significantly enhanced by intercalation, which suggests that such materials may have prospective application as the basis of a supported catalyst system for the hydroformylation of higher olefins.

  18. A novel method to get methotrexatum/layered double hydroxides intercalation compounds and their release properties

    Science.gov (United States)

    Qi, Fenglin; Zhang, Xiaoqing; Li, Shuping

    2013-08-01

    In this context, the methotrexatum/layered double hydroxides (MTX/LDHs) intercalation compounds have been synthesized by a mechanochemical-hydrothermal method, which involves a grinding process and subsequent hydrothermal treatment. The influence of R (molar ratio of Mg2+ to Al3+ to MTX) values on the structure and morphology of the intercalation compounds and their release properties were investigated systematically. The resulting compounds were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), inductively coupled plasma (ICP), thermogravimetric (TG) and differential scanning calorimetry (DSC) analysis. All the results indicate that R value has significant influence on the intercalation of MTX anions into LDH interlayer and the optimal R value is 2:1:0.5. Furthermore, four dissolution-diffusion kinetic models were used to fit the in vitro release of MTX from LDH layers. The release process can be divided into two stages: firstly surface diffusion and secondly intraparticle diffusion. The study also revealed that the properties of the intercalation compounds is comparable to that obtained from standard methods such as co-precipitation method, but with time, solvent and energy saving.

  19. Structure, molecular simulation, and release of aspirin from intercalated Zn-Al-layered double hydroxides.

    Science.gov (United States)

    Meng, Zilin; Li, Xiaowei; Lv, Fengzhu; Zhang, Qian; Chu, Paul K; Zhang, Yihe

    2015-11-01

    Aspirin or acetylsalicylic acid (AA), a non-steroidal anti-inflammatory drug, is intercalated into Zn-Al-layered double hydroxides (ZnAl-LDHs) by co-precipitation and reconstruction methods. The composition, structure, and morphology of the intercalated products as well as their release behavior are determined experimentally and theoretically by Material Studio 5.5. Experimental results disclose the strong interaction between the LDHs sheets and AA in the intercalated ZnAl-LDHs produced by co-precipitation and slow release of AA from the intercalated ZnAl-LDHs in both phosphate buffered saline (PBS) and borate buffered saline (BBS) solutions. The percentage of AA released from the ZnAl-LDHs prepared by both methods in PBS (96.87% and 98.12%) are much more than those in BBS (68.59% and 81.22%) implying that both H4BO4(-) and H2PO4(-) can exchange with AA in the ZnAl-LDHs. After AA is released to PBS, ZnAl-LDHs break into small pieces. The experimental results are explained theoretically based on the calculation of the bonding energy between the anions and LDHs sheets as well as the AlO bond length change in the LDHs sheets. Copyright © 2015 Elsevier B.V. All rights reserved.

  20. Mechanochemical synthesis and intercalation of Ca(II)Fe(III)-layered double hydroxides

    Science.gov (United States)

    Ferencz, Zs.; Szabados, M.; Varga, G.; Csendes, Z.; Kukovecz, Á.; Kónya, Z.; Carlson, S.; Sipos, P.; Pálinkó, I.

    2016-01-01

    A mechanochemical method (grinding the components without added water - dry grinding, followed by further grinding in the presence of minute amount of water or NaOH solution - wet grinding) was used in this work for the preparation and intercalation of CaFe-layered double hydroxides (LDHs). Both the pristine LDHs and the amino acid anion (cystinate and tyrosinate) intercalated varieties were prepared by the two-step grinding procedure in a mixer mill. By systematically changing the conditions of the preparation method, a set of parameters could be determined, which led to the formation of close to phase-pure LDH. The optimisation procedure was also applied for the intercalation processes of the amino acid anions. The resulting materials were structurally characterised by a range of methods (X-ray diffractometry, scanning electron microscopy, energy dispersive analysis, thermogravimetry, X-ray absorption and infra-red spectroscopies). It was proven that this simple mechanochemical procedure was able to produce complex organic-inorganic nanocomposites: LDHs intercalated with amino acid anions.

  1. Intercalation and structural aspects of macroRAFT agents into MgAl layered double hydroxides

    Directory of Open Access Journals (Sweden)

    Dessislava Kostadinova

    2016-12-01

    Full Text Available Increasing attention has been devoted to the design of layered double hydroxide (LDH-based hybrid materials. In this work, we demonstrate the intercalation by anion exchange process of poly(acrylic acid (PAA and three different hydrophilic random copolymers of acrylic acid (AA and n-butyl acrylate (BA with molar masses ranging from 2000 to 4200 g mol−1 synthesized by reversible addition-fragmentation chain transfer (RAFT polymerization, into LDH containing magnesium(II and aluminium(III intralayer cations and nitrates as counterions (MgAl-NO3 LDH. At basic pH, the copolymer chains (macroRAFT agents carry negative charges which allowed the establishment of electrostatic interactions with the LDH interlayer and their intercalation. The resulting hybrid macroRAFT/LDH materials displayed an expanded interlamellar domain compared to pristine MgAl-NO3 LDH from 1.36 nm to 2.33 nm. Depending on the nature of the units involved into the macroRAFT copolymer (only AA or AA and BA, the intercalation led to monolayer or bilayer arrangements within the interlayer space. The macroRAFT intercalation and the molecular structure of the hybrid phases were further characterized by Fourier transform infrared (FTIR and solid-state 13C, 1H and 27Al nuclear magnetic resonance (NMR spectroscopies to get a better description of the local structure.

  2. Intercalation and structural aspects of macroRAFT agents into MgAl layered double hydroxides

    Science.gov (United States)

    Kostadinova, Dessislava; Cenacchi Pereira, Ana; Lansalot, Muriel; D’Agosto, Franck; Bourgeat-Lami, Elodie; Leroux, Fabrice; Taviot-Guého, Christine; Cadars, Sylvian

    2016-01-01

    Summary Increasing attention has been devoted to the design of layered double hydroxide (LDH)-based hybrid materials. In this work, we demonstrate the intercalation by anion exchange process of poly(acrylic acid) (PAA) and three different hydrophilic random copolymers of acrylic acid (AA) and n-butyl acrylate (BA) with molar masses ranging from 2000 to 4200 g mol−1 synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization, into LDH containing magnesium(II) and aluminium(III) intralayer cations and nitrates as counterions (MgAl-NO3 LDH). At basic pH, the copolymer chains (macroRAFT agents) carry negative charges which allowed the establishment of electrostatic interactions with the LDH interlayer and their intercalation. The resulting hybrid macroRAFT/LDH materials displayed an expanded interlamellar domain compared to pristine MgAl-NO3 LDH from 1.36 nm to 2.33 nm. Depending on the nature of the units involved into the macroRAFT copolymer (only AA or AA and BA), the intercalation led to monolayer or bilayer arrangements within the interlayer space. The macroRAFT intercalation and the molecular structure of the hybrid phases were further characterized by Fourier transform infrared (FTIR) and solid-state 13C, 1H and 27Al nuclear magnetic resonance (NMR) spectroscopies to get a better description of the local structure.

  3. Synthesis and characterization of organic intercalated layered double hydroxides and their application in bitumen modification

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Song [State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan 430070 (China); Yu, Jianying, E-mail: jyyu@whut.edu.cn [State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan 430070 (China); Sun, Yubin [Center for Materials Research and Analysis, Wuhan University of Technology, Wuhan 430070 (China); Wu, Shaopeng [State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan 430070 (China)

    2015-02-15

    Organic layered double hydroxides (LDHs) intercalated by sodium dodecylbenzenesulfonate (SDBS) were prepared by anion-exchange method and applied to modify bitumen aiming at improving ageing resistance of bitumen. The organic LDHs (SDBS–LDHs) were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and Ultraviolet and visible (UV–vis) spectrophotometry. The effect of SDBS–LDHs and LDHs on physical and anti-ageing properties of bitumen was evaluated by means of conventional and rheological test. The results of XRD, FTIR and SEM show that SDBS is successfully intercalated into interlayer of LDHs, and the UV–vis reflectance and absorbance curves illustrate that intercalation of SDBS enhances the UV shielding effect of LDHs. The addition of SDBS–LDHs or LDHs has little influence on physical properties of bitumen because SDBS–LDHs and LDHs are physically mixed in bitumen. Compared with pristine bitumen after TFOT and UV irradiation ageing, the introduction of SDBS–LDHs and LDHs significantly improves thermal- and photo-oxidative ageing resistance of bitumen. Notably, bitumen with SDBS–LDHs exhibits better anti-ageing performance than that with LDHs, implying more effective modification of SDBS-LDHs which is due to the enhanced UV protective ability and compatibility with bitumen of SDBS–LDHs. - Highlights: • XRD, FTIR and SEM were used to confirm the successful intercalation. • SDBS–LDHs show superior UV protective ability. • SDBS–LDHs improved the anti-ageing properties of bitumen.

  4. Photostability enhancement of azoic dyes adsorbed and intercalated into Mg-Al-layered double hydroxide

    Science.gov (United States)

    Liu, Pengfei; Liu, Pei; Zhao, Kongcao; Li, Lei

    2015-11-01

    Two azoic dyes 4-aminoazobenzene-4-sulfonic (AS) and ethyl orange (EO) were adsorbed on or intercalated into Mg-Al-CO3 layered double hydroxide (LDH) for photostability enhancement. Fluorescence analysis results showed that the photostability of two dyes could be greatly improved after being adsorbed on the surface of Mg-Al-CO3-LDH matrix. Furthermore, photostability of adsorbed dyes was superior to that of intercalated dyes. It was suggested that AS or EO was adsorbed on LDHs surface through a strong chemisorption interaction, resulting in the enhancement of photostability. After the UV irradiation under N2 atmosphere, the absorbed dyes not only show great increase of fluorescence intensity but also exhibited high stability against UV irradiation. This work provides a feasible approach to enhance the photostability of azoic dye confined in an inorganic two-dimensional (2D) matrix via changing the microenvironment, which may be considered to be a promising method of improving photostability of solid fluorescent materials.

  5. Anion-intercalated layered double hydroxides modified test strips for detection of heavy metal ions.

    Science.gov (United States)

    Wang, Nan; Sun, Jianchao; Fan, Hai; Ai, Shiyun

    2016-01-01

    In this work, a novel approach for facile and rapid detection of heavy metal ions using anion-intercalated layered double hydroxides (LDHs) modified test strips is demonstrated. By intercalating Fe(CN)6(4-) or S(2-) anions into the interlayers of LDHs on the filter paper, various heavy metal ions can be easily detected based on the color change before and after reaction between the anions and the heavy metal ions. Upon the dropping of heavy metal ions solutions to the test strips, the colors of the test strips changed instantly, which can be easily observed by naked eyes. With the decrease of the concentration, the color depth changed obviously. The lowest detection concentration can be up to 1×10(-6) mol L(-1). Due to the easily intercalation of anions into the interlayer of the LDHs on test trips, this procedure provides a general method for the construction of LDHs modified test strips for detection of heavy metal ions. The stability of the prepared test strips is investigated. Furthermore, all the results were highly reproducible. The test strips may have potential applications in environmental monitoring fields.

  6. Synthesis and reversible hydration behavior of the thiosulfate intercalated layered double hydroxide of Zn and Al

    Energy Technology Data Exchange (ETDEWEB)

    Radha, S. [Department of Chemistry, Central College, Bangalore University, Bangalore-560 001 (India); Milius, Wolfgang [Department of Inorganic Chemistry I, University of Bayreuth, Bayreuth (Germany); Breu, Josef, E-mail: josef.breu@uni-bayreuth.de [Department of Inorganic Chemistry I, University of Bayreuth, Bayreuth (Germany); Kamath, P. Vishnu, E-mail: vishnukamath8@hotmail.com [Department of Chemistry, Central College, Bangalore University, Bangalore-560 001 (India)

    2013-08-15

    The thiosulfate-intercalated layered double hydroxide of Zn and Al undergoes reversible hydration with a variation in the relative humidity of the ambient. The hydrated and dehydrated phases, which represent the end members of the hydration cycle, both adopt the structure of the 3R{sub 1} polytype. In the intermediate range of relative humidity values (40–60%), the hydrated and dehydrated phases coexist. The end members of the hydration cycle adopt the structure of the same polytype, and vary only in their basal spacings. This points to the possibility that all the intermediate phases have a kinetic origin. - Graphical abstract: Basal spacing evolution of the thiosulfate ion intercalated [Zn–Al] LDH during one complete hydration–dehydration cycle as a function of relative humidity. Display Omitted - Highlights: • Thiosulfate intercalated [Zn–Al] LDHs were synthesized by co-precipitation. • The LDH exhibits reversible hydration with variation in humidity. • Both the end members of the hydration cycle adopt the same polytype structure. • The interstratified intermediates observed are kinetic in origin.

  7. Mechanochemical synthesis of Cu-Al and methyl orange intercalated Cu-Al layered double hydroxides

    Energy Technology Data Exchange (ETDEWEB)

    Qu, Jun, E-mail: forsjun@whut.edu.cn [School of Resources and Environmental Engineering, Wuhan University of Technology, Luoshi Road 122, Wuhan, Hubei 430070 (China); He, Xiaoman; Chen, Min; Hu, Huimin [School of Resources and Environmental Engineering, Wuhan University of Technology, Luoshi Road 122, Wuhan, Hubei 430070 (China); Zhang, Qiwu, E-mail: zhangqw@whut.edu.cn [School of Resources and Environmental Engineering, Wuhan University of Technology, Luoshi Road 122, Wuhan, Hubei 430070 (China); Liu, Xinzhong [College of Ecological Environment and Urban Construction, Fujian University of Technology, Fuzhou 350118 China (China)

    2017-04-15

    In this study, a mechanochemical route to synthesize a Cu-Al layered double hydroxide (LDH) and a methyl orange (MO) intercalated one (MO-LDH) was introduced, in which basic cupric carbonate (Cu{sub 2}(OH){sub 2}CO{sub 3}) and aluminum hydroxide (Al(OH){sub 3}) with Cu/Al molar ratio at 2/1 was first dry ground for 2 h and then agitated in water or methyl orange solution for another 4 h to obtain the LDH and MO-LDH products without any heating operation. The prepared samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Thermogravimetry (TG), Differential scanning calorimetry (DSC) and Scanning electron microscopy (SEM). The products showed high crystallinity phase of Cu-Al and MO intercalated Cu-Al LDH with no evident impurities, proving that the craft introduced here was facile and effective. The new idea can be applied in other fields to produce organic-inorganic composites. - Highlights: • A facile mechanochemical route to synthesize Cu-Al and MO intercalated Cu-Al LDH. • The products possesses high crystalline of LDH phase with no impure phases. • The dry milling process induces the element substitution between the raw materials. • The agitation operation helps the grain growth of LDH.

  8. Mg-Al layered double hydroxide intercalated with porphyrin anions: molecular simulations and experiments.

    Science.gov (United States)

    Kovár, Petr; Pospísil, Miroslav; Káfunková, Eva; Lang, Kamil; Kovanda, Frantisek

    2010-02-01

    Molecular modeling in combination with powder X-ray diffraction (XRD) provided new information on the organization of the interlayer space of Mg-Al layered double hydroxide (LDH) containing intercalated porphyrin anions [5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (TPPS)]. Anion-exchange and rehydration procedures were used for the preparation of TPPS-containing LDH with an Mg/Al molar ratio of 2. Molecular modeling was carried out in the Cerius(2) and Materials Studio modeling environment. Three types of models were created in order to simulate the experimental XRD patterns of LDH intercalates with a TPPS loading of 70-80% with respect to the theoretical anion exchange capacity (AEC). The models represent single-phase systems with a 100% TPPS loading in the interlayer space (Type 1) and models represent the coexistence of two phases corresponding to the total exchange from 75 to 92% (Type 2). To cover other possible arrangements, models with the coexistence of both TPPS and NO(3)(-) anions in the same interlayer space were calculated (Type 3). The models are described and compared with experimental data. In all cases, guest TPPS anions are tilted with respect to the hydroxide layers, and are horizontally shifted to each other by up to one-half of the TPPS diameter. According to the energy characteristics and simulated XRD, the most probable arrangement is of Type 2, where some layers are saturated with TPPS anions and others are filled with original NO(3)(-) anions.

  9. Study on the supramolecular structure of sorbic acid intercalated Zn-Al layered double hydroxides and its thermal decomposition

    Institute of Scientific and Technical Information of China (English)

    MENG Jinhong; ZHANG Hui; David G. Evans; DUAN Xue

    2005-01-01

    A novel organic-inorganic composite, sorbic acid intercalated zinc aluminum layered double hydroxides (SA-ZnAl-LDHs) has been successfully assembled by a simple direct coprecipitation method. A holistic approach including normal XRD, FT-IR, and UV-Vis measurements and simultaneous TG/DTA/MS and in situ HT-XRD techniques was employed to explore the supramolecular intercalation structure and the thermal decomposition properties of as-synthesized SA-ZnAl-LDHs material.

  10. Preparation and inhibition properties of molybdate intercalated ZnAlCe layered double hydroxide

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Huajie; Wang, Jihui, E-mail: jhwang@tju.edu.cn; Zhang, Yu; Hu, Wenbin

    2016-09-05

    ZnAlCe layered double hydroxide intercalated by molybdate (ZnAlCe−MoO{sub 4} LDH) was successfully synthesized by using co-precipitation method, and the morphology, structure of ZnAlCe−MoO{sub 4} LDH were observed and characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) techniques. The inhibition behavior of ZnAlCe−MoO{sub 4} LDH for Q235 steel in 3.5%NaCl solution was determined by polarization curves, electrochemical impedance spectroscopy (EIS), inductively coupled plasma mass spectrometer (ICP-MS) and X-ray photoelectron spectrometer (XPS) methods. The results shows that the synthesized ZnAlCe−MoO{sub 4} LDH has a lamellar structure with a particle size of 0.1–2.0 μm, an average thickness of 30 nm, and a basal plane spacing of 0.898 nm. Compared with the addition of ZnAl layered double hydroxide intercalated by nitrate (ZnAl−NO{sub 3} LDH) and ZnAl layered double hydroxide intercalated by molybdate (ZnAl−MoO{sub 4} LDH) in 3.5% NaCl solution, Q235 steel in 3.5%NaCl + ZnAlCe−MoO{sub 4} LDH solution has a lower corrosion current density, larger polarization resistance and a higher inhibition efficiency. The addition of ZnAlCe−MoO{sub 4} LDH will reduce the chloride concentration in 3.5% NaCl solution by the anion exchanged with molybdate, and improve the corrosion resistance of Q235 steel owing to the formation of passive film with the composition of ferrous or iron molybdate and deposition film with zinc and cerium hydroxides. - Highlights: • ZnAlCe−MoO{sub 4} LDH compound was successfully synthesized by co-precipitation method. • ZnAlCe−MoO{sub 4} LDH has a better inhibition effect to Q235 steel in 3.5%NaCl solution. • The Cl{sup −} ions in solution was partially exchanged with MoO{sub 4}{sup 2−} ions in host layers. • The passive film and deposition film were formed by the release of LDH compound.

  11. Dynamics of Intercalation/De-Intercalation of Rhodamine B during the Polymorphic Transformation of CdAl Layered Double Hydroxide to the Brucite-Like Cadmium Hydroxide

    KAUST Repository

    Saliba, Daniel

    2016-06-23

    Cadmium-Aluminum layered double hydroxide (CdAl LDH) is thermodynamically unstable and transforms to Cd(OH)2 and Al(OH)3 in a short period of time. We present a reaction-diffusion framework that enables us to use in situ steady-state fluorescence spectroscopy to study the kinetics of intercalation of a fluorescent probe (Rhodamine B (RhB)) during the formation of the CdAl LDH and its de-intercalation upon the conversion of the LDH phase to the β phase (Cd(OH)2). The method involves the diffusion of sodium hydroxide into a hydrogel gel matrix containing the aluminum and cadmium ions as well as the species we wish to incorporate in the interlayers of the LDH. The existence of RhB between the LDH layers and its expel during the transition into the β phase are proved via fluorescence microscopy, XRD and ssNMR. The activation energies of intercalation and de-intercalation of RhB are computed and show dependence on the cationic ratio of the corresponding LDH. We find that the energies of de- intercalation are systematically higher than those of intercalation proving that the dyes are stabilized due to the probe-brucite sheets interactions.

  12. Engineering of (10-hydroxycamptothecin intercalated layered double hydroxide)@liposome nanocomposites with excellent water dispersity

    Science.gov (United States)

    Zhang, Yongfang; Wu, Xiaowen; Mi, Yuwei; Li, Haiping; Hou, Wanguo

    2017-09-01

    A hierarchical nanocomposite of 10-hydroxycamptothecin (HCPT), a nonionic and lipophilic anticancer drug, intercalated layered double hydroxide (LDH) encapsulated in liposomes was constructed. HCPT molecules were first incorporated into sodium cholate (Ch) micelles, and the resultant negatively charged HCPT-loaded Ch micelles were then co-assembled with positively charged LDH single-layer nanosheets, forming a HCPT/Ch intercalated LDH (HCPT-Ch-LDH) host-gest nanohybrid. The nanohybrid particles were further coated with liposomes (LSs), gaining a core-shell nanocomposite, denoted as (HCPT-Ch-LDH)@LS. The so-obtained samples were characterized using TEM, SAXS, FT-IR, DLS, and elemental analyses. Special emphasis was placed on the effect of liposome-coating for the HCPT-Ch-LDH on its water dispersity and drug-release. The results showed that the nanocomposite has excellent water dispersity and enhanced drug sustained-release performance in comparison with the HCPT-Ch-LDH, demonstrating that the liposome-coating for drug-LDH nanohybrids is an effective strategy to enhance their water dispersity and sustained-release performances. This work provides an effective strategy for engineering of LDH-based delivery systems for nonionic and lipophilic drugs.

  13. Synthesis and Characterization of Camptothecin Intercalated into Mg/AI Layered Double Hydroxide

    Institute of Scientific and Technical Information of China (English)

    LIU,Chun-Xia; HOU,Wan-Guo; LI,Yan; LI,Li-Fang

    2008-01-01

    The intercalation of camptothecin(CPT)into a layered inorganic host,Mg-Al layered double hydroxide(LDH),was carried out using a coprecipitation method tO obtain CPT-LDH nanohybrids.It Was found that the intercalated amounts(Ain)of CPrr-LDH nanohybrids were remarkably dependent on the molar ratios(Rc,M)of CPT tO metal ions in raw materials.The Ain value increases with the RC/M value increasing.According to the gallery heights of CPT-LDH and sizes of CPT molecule,a probably morphology of CPT molecules in the gallery of LDH was suggested that the horizontal-arranged monolayer and vertical-arranged bilayer of CPT molecules coexisted in the interlayer region of LDH.An interesting result was found that the gallery height corresponding to the bilayer of CPT-LDH sample with a high Ain value was remarkably Iower than that with low Ain value.111e/n vitro CPT release examinations from the nanohybrids showed that the CPT-LDH nanohybrids were a potential drug controlled release system.The kinetic analysis showed that the release kinetics of CPT from the nanohybrids obeyed the pseudo-first order kinetic model and the diffusion Of CPT through the LDH particle Of CPT played an important role in controlling the drug release rate.

  14. Facile synthesis of methotrexate intercalated layered double hydroxides: Particle control, structure and bioassay explore

    Energy Technology Data Exchange (ETDEWEB)

    Tian, De-Ying; Liu, Zhen-Lei [Jiangsu Key Laboratory of Biofunctional Material, College of Chemistry and Material Science, Nanjing Normal University, Nanjing 210023 (China); Li, Shu-Ping, E-mail: lishuping@njnu.edu.cn [Jiangsu Key Laboratory of Biofunctional Material, College of Chemistry and Material Science, Nanjing Normal University, Nanjing 210023 (China); Li, Xiao-Dong [Jiangsu Key Laboratory of Biofunctional Material, College of Chemistry and Material Science, Nanjing Normal University, Nanjing 210023 (China); Shenzhen Research Institute of Xiamen University, Shenzhen 518057 (China)

    2014-12-01

    To study the influence of particle size on drug efficacy and other properties, a series of methotrexate intercalated layered double hydroxides (MTX/LDHs) were synthesized through the traditional coprecipitation method, using a mixture of water and polyethylene glycol (PEG-400) as the solvent. To adjust the particle size of MTX/LDHs, the dropping way, the volume ratio of water to PEG-400 and different hydrothermal treatment time changed accordingly, and the results indicate that the particle size can be controlled between 90 and 140 nm. Elemental C/H/N and inductive coupled plasma (ICP) analysis indicated that different synthesis conditions almost have no effect on the compositions of the nanohybrids. X-ray diffraction (XRD) patterns manifested the successful intercalation of MTX anions into the LDH interlayers, and it's also found out that different volume ratios of water to PEG-400 and variable dropping way can affect the crystallinity of the final samples, i.e., the volume ratio of 3:1 and pH decreasing are proved to be optimum conditions. Furthermore, both antiparallel monolayer and bilayers adopting different orientations are suggested for four samples from XRD results. Fourier transform infrared spectroscopy (FTIR) investigations proved the coexistence of CO{sub 3}{sup 2−} and MTX anions in the interlayer of the nanohybrids. MTX/LDH particles exhibited hexagonal platelet morphology with round corner and different dropping ways can affect the morphology greatly. Moreover, a DSC study indicated that longer time treatment can weaken the bond between the MTX anions and LDH layers. The kinetic release profiles told us that larger MTX/LDH particles have enhanced the ability of LDH layers to protect interlayer molecules. At last, the bioassay study indicated that the nanohybrids with larger diameters have higher tumor suppression efficiency. - Graphical abstract: A series of methotrexate intercalated layered double hydroxides were synthesized by changing the

  15. Methotrexatum intercalated layered double hydroxides: Statistical design, mechanism explore and bioassay study

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiao-Feng [Department of Gastroenterology, Weihai municipal hospital, Weihai 264200 (China); Liu, Su-Qing [Jiangsu Key Laboratory of Biofunctional Material, College of Chemistry and Material Science, Nanjing Normal University, Nanjing 210023 (China); Li, Shu-Ping, E-mail: lishuping@njnu.edu.cn [Jiangsu Key Laboratory of Biofunctional Material, College of Chemistry and Material Science, Nanjing Normal University, Nanjing 210023 (China)

    2015-04-01

    A series of methotrexatum intercalated layered double hydroxide (MTX/LDH for short) hybrids have been synthesized by a mechanochemical–hydrothermal method, the statistical experiments are planned and conducted to find out the critical factor influencing the physicochemical properties. Four variables, i.e., addition of NaOH solution, grinding duration, hydrothermal temperature and time, are chosen to play as the examined factors in the orthogonal design. Furthermore, three respective levels, i.e., high, medium and low levels, are conducted in the design. The resulting hybrids are then characterized by X-ray diffraction (XRD) patterns, transmission electron microscope (TEM) graphs and Zeta potentials. XRD diffractions indicate that MTX anions have been successfully intercalated into LDH interlayers and the amount of NaOH solution can change the gallery height greatly. The information from TEM graphs and Zeta potentials state that the increase of alkali solution gives rise to regular morphology and the increase of Zeta potentials. As a result of the statistical analysis, addition of alkali solution is the major factor affecting the morphology and drug-loading capacity. At last, the mechanism of particle growth is explored emphatically, and the anticancer efficacy of some MTX/LDH hybrids is estimated by MTT assay on A549 cells as well. - Graphical abstract: Schematic illustration of synthesis and properties of MTX intercalated LDH hybrids. - Highlights: • Increasing NaOH solution gives rise to high drug-loading capacity. • Increasing the alkali solution leads to high layer charge and regular morphology. • The monodispersity has critical effect on the tumor suppression efficiency.

  16. Co–Fe Prussian Blue Analogue Intercalated into Diamagnetic Mg–Al Layered Double Hydroxides

    Directory of Open Access Journals (Sweden)

    Cuijuan Zhang

    2016-04-01

    Full Text Available A heterostructure of diamagnetic magnesium‒aluminium layered double hydroxides (Mg‒Al LDHs and photomag‐ netic cobalt‒iron Prussian Blue analogue (Co‒Fe PBA was designed, synthesized and then designated as LDH‒PB. The cyanide-bridged Co‒Fe PBA was two-dimensionally intercalated into the Mg‒Al LDH template by the stepwise anion exchange method. LDH‒PB showed ferrimagnetic properties with in-plane antiferromagnetic exchange interactions, as well as small photo-induced magnetization by visible light illumination due to the low dimensional structures and the characteristic photo-induced electronic states of the mixed valence of FeIII(low spin, S = 1/2‒CN‒ CoII(high spin, S = 3/2‒NC‒FeII (low spin, S = 0.

  17. Synthesis and photoluminescence of red emitting phosphors of europium complex intercalated layered double hydroxide

    Science.gov (United States)

    Gao, Xiaorui; Gao, Zhen; Yin, Xiaoru; Xie, Juan

    2015-12-01

    An inorganic-organic red emitting phosphor, europium ethylenediaminetetraacetate complex ([Eu(EDTA)]-) anions intercalated Mg/Al and Zn/Al layered double hydroxides (LDHs) were synthesized through an ion exchange method. X-ray powder diffraction (XRD) results exhibit that a nearly vertical arrangement of [Eu(EDTA)]- anions with the maximal dimension in the gallery is adopted. Measurement of the excitation and emission spectra show that the two materials display high red luminescence from Eu3+ ions. Furthermore, Mg/Al LDH containing europium complex has higher luminescence intensity than Zn/Al LDH, which probably was related with more inversion asymmetry sites of Eu3+ occurring in the Mg/Al LDH.

  18. Rapid exchange between atmospheric CO2 and carbonate anion intercalated within magnesium rich layered double hydroxide.

    Science.gov (United States)

    Sahoo, Pathik; Ishihara, Shinsuke; Yamada, Kazuhiko; Deguchi, Kenzo; Ohki, Shinobu; Tansho, Masataka; Shimizu, Tadashi; Eisaku, Nii; Sasai, Ryo; Labuta, Jan; Ishikawa, Daisuke; Hill, Jonathan P; Ariga, Katsuhiko; Bastakoti, Bishnu Prasad; Yamauchi, Yusuke; Iyi, Nobuo

    2014-10-22

    The carbon cycle, by which carbon atoms circulate between atmosphere, oceans, lithosphere, and the biosphere of Earth, is a current hot research topic. The carbon cycle occurring in the lithosphere (e.g., sedimentary carbonates) is based on weathering and metamorphic events so that its processes are considered to occur on the geological time scale (i.e., over millions of years). In contrast, we have recently reported that carbonate anions intercalated within a hydrotalcite (Mg0.75Al0.25(OH)2(CO3)0.125·yH2O), a class of a layered double hydroxide (LDH), are dynamically exchanging on time scale of hours with atmospheric CO2 under ambient conditions. (Ishihara et al., J. Am. Chem. Soc. 2013, 135, 18040-18043). The use of (13)C-labeling enabled monitoring by infrared spectroscopy of the dynamic exchange between the initially intercalated (13)C-labeled carbonate anions and carbonate anions derived from atmospheric CO2. In this article, we report the significant influence of Mg/Al ratio of LDH on the carbonate anion exchange dynamics. Of three LDHs of various Mg/Al ratios of 2, 3, or 4, magnesium-rich LDH (i.e., Mg/Al ratio = 4) underwent extremely rapid exchange of carbonate anions, and most of the initially intercalated carbonate anions were replaced with carbonate anions derived from atmospheric CO2 within 30 min. Detailed investigations by using infrared spectroscopy, scanning electron microscopy, powder X-ray diffraction, elemental analysis, adsorption, thermogravimetric analysis, and solid-state NMR revealed that magnesium rich LDH has chemical and structural features that promote the exchange of carbonate anions. Our results indicate that the unique interactions between LDH and CO2 can be optimized simply by varying the chemical composition of LDH, implying that LDH is a promising material for CO2 storage and/or separation.

  19. Methotrexatum intercalated layered double hydroxides: statistical design, mechanism explore and bioassay study.

    Science.gov (United States)

    Wang, Xiao-Feng; Liu, Su-Qing; Li, Shu-Ping

    2015-04-01

    A series of methotrexatum intercalated layered double hydroxide (MTX/LDH for short) hybrids have been synthesized by a mechanochemical-hydrothermal method, the statistical experiments are planned and conducted to find out the critical factor influencing the physicochemical properties. Four variables, i.e., addition of NaOH solution, grinding duration, hydrothermal temperature and time, are chosen to play as the examined factors in the orthogonal design. Furthermore, three respective levels, i.e., high, medium and low levels, are conducted in the design. The resulting hybrids are then characterized by X-ray diffraction (XRD) patterns, transmission electron microscope (TEM) graphs and Zeta potentials. XRD diffractions indicate that MTX anions have been successfully intercalated into LDH interlayers and the amount of NaOH solution can change the gallery height greatly. The information from TEM graphs and Zeta potentials state that the increase of alkali solution gives rise to regular morphology and the increase of Zeta potentials. As a result of the statistical analysis, addition of alkali solution is the major factor affecting the morphology and drug-loading capacity. At last, the mechanism of particle growth is explored emphatically, and the anticancer efficacy of some MTX/LDH hybrids is estimated by MTT assay on A549 cells as well.

  20. Methotrexate intercalated layered double hydroxides with the mediation of surfactants: Mechanism exploration and bioassay study

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Chao-Fan; Tian, De-Ying; Li, Shu-Ping, E-mail: lishuping@njnu.edu.cn; Li, Xiao-Dong

    2015-12-01

    Methotrexatum intercalated layered double hydroxides (MTX/LDHs) hybrids were synthesized by the co-precipitation method and three kinds of nonionic surfactants with different hydrocarbon chain lengths were used. The resulting hybrids were then characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and transmission electron microscopy (TEM). XRD and FTIR investigations manifest the successful intercalation of MTX anions into the interlayer of LDHs. TEM graphs indicate that the morphology of the hybrids changes with the variation of the chain length of the surfactants, i.e., the particles synthesized using polyethylene glycol (PEG-7) present regular disc morphology with good monodispersity, while samples with the mediation of alkyl polyglycoside (APG-14) are heavily aggregated and samples with the addition of polyvinylpyrrolidone (PVP-10) exhibit irregular branches. Furthermore, the release and bioassay experiments show that monodisperse MTX/LDHs present good controlled-release and are more efficient in the suppression of the tumor cells. - Highlights: • Surfactants could be used to modify the dispersing state of MTX/LDHs hybrids. • Surfactants have great effect on the morphology of MTX/LDHs hybrids. • MTX/LDHs with good monodisperse degree are more efficient in the suppression of the tumor cells.

  1. Molecular modeling of layered double hydroxide intercalated with benzoate, modeling and experiment.

    Science.gov (United States)

    Kovár, Petr; Pospísil, M; Nocchetti, M; Capková, P; Melánová, Klára

    2007-08-01

    The structure of Zn4Al2 Layered Double Hydroxide intercalated with benzencarboxylate (C6H5COO-) was solved using molecular modeling combined with experiment (X-ray powder diffraction, IR spectroscopy, TG measurements). Molecular modeling revealed the arrangement of guest molecules, layer stacking, water content and water location in the interlayer space of the host structure. Molecular modeling using empirical force field was carried out in Cerius(2) modeling environment. Results of modeling were confronted with experiment that means comparing the calculated and measured diffraction pattern and comparing the calculated water content with the thermogravimetric value. Good agreement has been achieved between calculated and measured basal spacing: d(calc) = 15.3 A and d(exp) = 15.5 A. The number of water molecules per formula unit (6H2O per Zn4Al2(OH)12) obtained by modeling (i.e., corresponding to the energy minimum) agrees with the water content estimated by thermogravimetry. The long axis of guest molecules are almost perpendicular to the LDH layers, anchored to the host layers via COO- groups. Mutual orientation of benzoate ring planes in the interlayer space keeps the parquet arrangement. Water molecules are roughly arranged in planes adjacent to host layers together with COO- groups.

  2. Structural features of intercalated CaFe-layered double hydroxides studied by X-ray diffractometry, infrared spectroscopy and computations

    Science.gov (United States)

    Ferencz, Zs.; Ádok-Sipiczki, M.; Hannus, I.; Sipos, P.; Pálinkó, I.

    2015-06-01

    The intercalation of various N-containing carboxylic acid anions into CaFe-layered double hydroxides was performed by the dehydration-rehydration method. Particular attention was paid to the effect of solvent mixture used during preparation. It was found that various solvent mixtures resulted in different interlayer distances and, thus, different arrangements of the anions between the layers. The dimensions of the intercalated anions and detailed analysis of the infrared spectra gave clues for the reasonable prediction of the spatial arrangements of the anions in the interlamellar space.

  3. Layered double hydroxide intercalated with p-methylbenzoate and p-bromobenzoate: molecular simulations and XRD analysis.

    Science.gov (United States)

    Kovár, Petr; Melánová, Klára; Zima, Vítezslav; Benes, Ludvík; Capková, Pavla

    2008-03-01

    Samples of Mg4Al2 layered double hydroxide (LDH) intercalated with p-methylbenzoate and p-bromobenzoate anions were prepared by reconstruction of calcined LDH. The interlayer arrangement of guests was investigated by molecular modeling combined with X-ray powder diffraction and thermogravimetry. Molecular modeling was carried out in a Cerius2 modeling environment. In both structures the guest anions adopt a nearly perpendicular arrangement of their long axis with respect to the host layers and they are anchored to the OH groups of the layers through COO* groups via electrostatic interactions. Molecular modeling revealed that both structures of the intercalates exhibit a certain disorder of guest anions in the interlayer space. In the case of LDH-p-methylbenzoate intercalate the anions tend to be situated in disordered rows, and the LDH-p-bromobenzoate intercalate exhibits a total disorientation of guest anions. A good agreement between calculated and measured X-ray diffraction patterns and between experimental and calculated basal spacings was obtained. In the LDH-p-methylbenzoate intercalate d exp=16.96 A and d calc=16.97 A, and in the case of LDH-p-bromobenzoate intercalate d exp=17.19 A and d calc=17.40 A.

  4. Mechanochemical synthesis of finite particle of layered double hydroxide-acetate intercalation compound: Swelling, thin film and ion exchange

    Science.gov (United States)

    Kuramoto, Kyoko; Intasa-Ard, Soontaree (Grace); Bureekaew, Sareeya; Ogawa, Makoto

    2017-09-01

    Acetate intercalated Mg-Al layered double hydroxide was successfully synthesized by the solid-state reactions between magnesium acetate and aluminum hydroxide as the starting materials using a planetary mil. The acetate intercalated Mg-Al layered double hydroxide prepared by the present solid-state reaction was finite particle and was processed into stable aqueous suspension with variable transparency and viscosity depending on the concentration. By drying the suspension on a substrate under nitrogen atmosphere, thin film (with the thickness of several micrometers) of the acetate intercalated Mg-Al layered double hydroxide with the basal plane oriented parallel to the substrate was obtained. The ion exchange ability of the film, which is as an advantage of the acetate form of layered double hydroxide, was shown by the ion exchange with coumarin-3-carboxylate to give a photoluminescent film. The solid-solid reaction is advantageous for the preparation of layered double hydroxides due to the simple and eco-friendly nature (no solvent) of the operation, lower possibility of carbonate contamination and finite particles of the products.

  5. Intercalation Assembly Method and Intercalation Process Control of Layered Intercalated Functional Materials

    Institute of Scientific and Technical Information of China (English)

    LI Kaitao; WANG Guirong; LI Dianqing; LIN Yanjun; DUAN Xue

    2013-01-01

    Layered intercalated functional materials of layered double hydroxide type are an important class of functional materials developed in recent years.Based on long term studies on these materials in the State Key Laboratory of Chemical Resource Engineering in Beijing University of Chemical Technology,the principle for the design of controlled intercalation processes in the light of future production processing requirements has been developed.Intercalation assembly methods and technologies have been invented to control the intercalation process for preparing layered intercalated materials with various structures and functions.

  6. Co-intercalation of Acid Red 337 and a UV absorbent into layered double hydroxides: enhancement of photostability.

    Science.gov (United States)

    Li, Dianqing; Qian, Leilei; Feng, Yongjun; Feng, Junting; Tang, Pinggui; Yang, Lan

    2014-12-10

    Organic-inorganic hybrid pigments with enhanced thermo- and photostability have been prepared by co-intercalating C.I. Acid Red 337 (AR337) and a UV absorbent (BP-4) into the interlayer of ZnAl layered double hydroxides through a coprecipitation method. The obtained compounds were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric-differential thermogravimetric-differential thermal analysis, UV-visible spectroscopy, and the International Commission on Illumination (CIE) 1976 L*a*b* color scales. The results show the successful co-intercalation of AR337 and BP-4 into the interlayer region of layered double hydroxides (LDHs) and reveal the presence of host-guest interactions between LDH host layers and guest anions of AR337 and BP-4 and guest-guest interactions between AR337 and BP-4. The intercalation can improve the thermostability of AR337 due to the protection of LDH layers. Moreover, the co-intercalation of AR337 and BP-4 not only markedly enhances the photostability of AR337 but also significantly influences the color of the hybrid pigment.

  7. Tribological performance of Mg/Al/Ce layered double hydroxides nanoparticles and intercalated products as lubricant additives

    Energy Technology Data Exchange (ETDEWEB)

    Li, Shuo; Qin, Haojing; Zuo, Ranfang; Bai, Zhimin, E-mail: zhimibai@cugb.edu.cn

    2015-10-30

    Highlights: • Mg/Al/Ce layered double hydroxides (LDHs) were synthesized by coprecipitation. • Mg/Al/Ce LDHs were intercalated with succinic acid and lauric acid respectively. • LDHs intercalated with lauric acid had the best friction properties among products. • Sliding of layers, good dispersity and a protective film decided the performance. - Abstract: Mg/Al/Ce ternary layered double hydroxides (LDHs) were synthesized via coprecipitation and intercalated by succinic acid and lauric acid through ion exchange method respectively. The LDHs products were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and Fourier transform infrared (FT-IR). Tribological properties of LDHs as lubricant additives were evaluated by four-ball friction and air compressor test. The results indicated that Mg/Al/Ce LDHs were prepared successfully with Ce/Al molar ratio of 0.05 and crystallization temperature of 140 °C. The interlayer spacing of LDHs precursor was expanded by succinic acid and lauric acid to 8.838 and 17.519 Å respectively. All the three LDHs products can reduce friction and wear of engine lubricating oil in the tests. LDHs intercalated with lauric acid showed best tribological performance among them which was attributed to sliding each other between laminates, good dispersibility in oil medium and a protective tribofilm formed on the worn surface.

  8. Ion exchange and intercalation properties of layered double hydroxides towards halide anions.

    Science.gov (United States)

    Costantino, Umberto; Vivani, Riccardo; Bastianini, Maria; Costantino, Ferdinando; Nocchetti, Morena

    2014-08-14

    A layered double hydroxide (LDH) obtained by the urea method, having an empirical formula [Zn(0.61)Al(0.39)(OH)2](CO3)(0.195)·0.50H2O, has been converted into the corresponding chloride form [Zn(0.61)Al(0.39)(OH)2]Cl(0.39)·0.47H2O by making the solid come into contact with a suitable HCl solution. The intercalation of the other halide anions (X(-) = F(-), Br(-), I(-)) via the Cl(-)/X(-) anion exchange has been attained and the respective anion exchange isotherms have been obtained with the batch method. The analysis of the isotherms indicates that the selectivity of LDH towards the halides decreases with the increase of the X(-) ionic radius, the selectivity order being F(-) > Cl(-)≥ Br(-) > I(-). The CO3(2-)/Cl(-) isotherm has also been reported to highlight the extraordinary selectivity of LDH towards carbonate anions. Samples taken from the isotherms at different exchange degrees were analyzed by X-ray diffraction, thermogravimetry and thermodiffractometry to obtain information about the ion exchange mechanism. The Cl(-)/Br(-) and the reverse Br(-)/Cl(-) exchanges occur with the formation of solid solutions, very likely because of the similar ionic radius of the exchanging anions. In contrast, in the Cl(-)/F(-) and Cl(-)/I(-) exchange, the co-existence of the Cl(-) and F(-) (or I(-)) phases in the same sample was detected, indicating the occurrence of a first order phase transition, in which the starting phase is transformed into the final phase, as the process goes on. The variation of the interlayer distances of ZnAl-X intercalation compounds with the hydration degree has been interpreted with a structural model based on the nesting of the guest species into the trigonal pockets of the brucite-like layer surface. Rietveld refinements of the phases with the maximum F(-), Br(-) and I(-) content were also performed and compared with the above model, giving indications of the arrangement and order/disorder of the halide anions in the interlayer region.

  9. A magnetic organic inorganic composite: Synthesis and characterization of magnetic 5-aminosalicylic acid intercalated layered double hydroxides

    Science.gov (United States)

    Zhang, Hui; Zou, Kang; Sun, Hui; Duan, Xue

    2005-11-01

    A core-shell structured magnetic layered organic-inorganic material involving 5-aminosalicylic acid (5-ASA) intercalated Zn-Al layered double hydroxides (LDHs) and magnesium ferrite (MgFe 2O 4) is assembled by a coprecipitation method. The powder X-ray diffraction results show the coexistence of the clear but weak diffractions of MgFe 2O 4 and ordered relatively stronger reflections of 5-ASA intercalated LDHs. The TEM image of magnetic 5-ASA intercalated LDHs reveals that the LDHs layer covers the MgFe 2O 4 particles or their aggregates with particle size of 50-80 nm. The vibration sample magnetization (VSM) measurements exhibit the increase in saturation magnetization of magnetic 5-ASA intercalated LDHs samples with increasing amount of magnetic core. The XPS analyses account for a majority of Zn, Al and O atoms on the surface of magnetic particles. It is suggested that the magnetic core MgFe 2O 4 was coated with LDHs layer probably through Zn-O-Mg and Al-O-Mg linkages, and a core-shell structured model is tentatively proposed.

  10. A combined study based on experiment and molecular dynamics: perylene tetracarboxylate intercalated in a layered double hydroxide matrix.

    Science.gov (United States)

    Yan, Dongpeng; Lu, Jun; Wei, Min; Ma, Jing; Evans, David G; Duan, Xue

    2009-10-28

    This paper describes a combined experimental and theoretical simulation investigation on the photophysical properties, thermolysis, and orientation of 3,4,9,10-perylene tetracarboxylate (PTCB) intercalated Mg-Al-layered double hydroxide (PTCB/Mg-Al-LDH). UV-vis absorption and fluorescence spectroscopy show the existence of PTCB aggregates within the gallery of LDH, indicative of H-type (blue-shifted absorption band) and J-type dimers (red-shifted absorption band). In situ high-temperature X-ray diffraction (HT-XRD), thermogravimetry and differential thermal analysis (TG-DTA) and elemental analysis were used to study the thermal decomposition properties of PTCB/Mg-Al-LDH, and it was found that the decomposition temperature of the intercalated PTCB is lower than its pristine form (460 vs 565 degrees C), indicating that the strong pi-pi interaction among PTCB was weakened by the positively charged LDH host layers. Molecular dynamics (MD) calculations were employed to simulate the molecular arrangement and aggregation behavior of intercalated PTCB in the gallery of Mg-Al-LDH. The simulation results show that the intercalated PTCB anions exhibit a tendency from tilted to vertical orientation with respect to the layers as the interlayer water content increases, furthermore, the H and J-type dimer species are most likely populated under low and high hydration conditions, respectively. Moreover, the distribution of interlayer water molecules are also discussed.

  11. Preparation of Rh-TPPTS complex intercalated layered double hydroxide and influences of host and guest compositions on its catalytic performances in hydroformylation reaction

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xian; LU Jun; JIN Lan; WEI Min

    2008-01-01

    Based on the concept of intercalation chemistry of layered double hydroxides (LDHs), RhCI(GO)-(TPPTS)2 (TPPTS: P(m-C6H4SO3Na)3) and TPPTS co-intercalated LDHs were successfully synthesized by in situ complexation method. Characterizations of structure and composition of composite materials by powder XRD, FT-IR, and ICP-AES techniques confirmed the supramolecular structures of the catalytic species intercalated LDHs. The correlation between catalytic performance of intercalated catalyst and the composition of both host layers and interlayer guest species was also investigated.

  12. In situ oligomerization of 2-(thiophen-3-yl)acetate intercalated into Zn{sub 2}Al layered double hydroxide

    Energy Technology Data Exchange (ETDEWEB)

    Tronto, Jairo, E-mail: jairotronto@ufv.br [Universidade Federal de Viçosa, Instituto de Ciências Exatas e Tecnológicas, Campus de Rio Parsanaíba, Rodovia BR 354 km 310, Cx. Postal 22, CEP, 38.810-000 Rio Paranaíba, MG (Brazil); Pinto, Frederico G.; Costa, Liovando M. da [Universidade Federal de Viçosa, Instituto de Ciências Exatas e Tecnológicas, Campus de Rio Parsanaíba, Rodovia BR 354 km 310, Cx. Postal 22, CEP, 38.810-000 Rio Paranaíba, MG (Brazil); Leroux, Fabrice; Dubois, Marc [Clermont Université, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand, BP 10448, F-63000 Clermont-Ferrand (France); CNRS, UMR 6296, ICCF, BP 80026, F-6317 Clermont-Ferrand (France); Valim, João B. [Universidade de São Paulo, Faculdade de Filosofia Ciências e Letras de Ribeirão Preto, Departamento de Química, Av. dos Bandeirantes 3900, CEP 14.040-901, Ribeirão Preto, SP (Brazil)

    2015-01-15

    A layered double hydroxide (LDH) with cation composition Zn{sub 2}Al was intercalated with 2-(thiophen-3-yl)acetate (3-TA) monomers. To achieve in situ polymerization and/or oligomerization of the intercalated monomers, soft thermal treatments were carried out, and subsequent hybrid LDH materials were analyzed by means of several characterization techniques using powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), {sup 13}C CP–MAS nuclear magnetic resonance (NMR), electron spin resonance (EPR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), inductively coupled plasma optical emission spectroscopy (ICP–OES), and elemental analysis. PXRD analysis suggested that the intercalated monomers formed a bilayer. Thermal treatment of the hybrid LDH assembly above 120 °C provokes partially the breakdown of the layered structure, generating the phase zincite. EPR results indicated that vicinal monomers (oligomerization) were bound to each other after hydrothermal or thermal treatment, leading to a polaron response characteristic of electron conductivity localized on a restricted number of thiophene-based monomer segments. Localized unpaired electrons exist in the material and interact with the {sup 27}Al nuclei of the LDH layers by superhyperfine coupling. These unpaired electrons also interact with the surface of ZnO (O{sup 2−} vacancies), formed during the thermal treatments. - Graphical abstract: We synthesized a layered double hydroxide (LDH) with cation composition Zn{sub 2}Al, intercalated with 2-(thiophen-3-yl)acetate (3-TA) monomers, by coprecipitation at constant pH. We thermally treated the material, to achieve in situ polymerization and/or oligomerization of the intercalated monomers. - Highlights: • A Zn{sub 2}Al–LDH was intercalated with 2-(thiophen-3-yl)acetate monomers. • To achieve in situ oligomerization of the monomers, thermal treatments were made.

  13. Study of the structure and luminescent properties of terbium complex intercalated Zn/Al layered double hydroxide

    Science.gov (United States)

    Gao, Xiaorui; Xie, Juan; Yin, Yaobing; Hao, Yongjing; Lian, Yiwei

    2016-01-01

    Terbium complex of ethylenediaminetetraacetate ([Tb(EDTA)]-) intercalated Zn/Al layered double hydroxide (LDH), as an inorganic-organic green-emitting phosphor, was synthesized through an ion exchange method. X-ray powder diffraction (XRD) and Fourier transform infrared (FTIR) spectra exhibit a successful intercalation of [Tb(EDTA)]- anions between the hydroxide sheets of the LDH. The basal spacing of 14.5 Å indicate a vertical arrangement of [Tb(EDTA)]- anions with the maximal dimension in the gallery is adopted. The luminescent properties of this material were studied by excitation and emission spectra. The results show that the strongest emission peak of Tb3+ ion occurs at 544 nm. This material may supply a candidate of green light emitting phosphor.

  14. Dysprosium-containing layered double hydroxides nanoparticles intercalated with biologically active species as an approach for theranostic systems

    Energy Technology Data Exchange (ETDEWEB)

    Arratia-Quijada, Jenny [Departamento de Ciencias de la Salud, Centro Universitario Tonalá, Universidad de Guadalajara, Av. Nuevo Periférico No. 555, C.P. 48525, Tonalá, Jalisco (Mexico); Sánchez Jiménez, Cecilia [Departamento de Química, Universidad de Guadalajara, Boulevard Marcelino García Barragán 1421, C.P. 44430, Guadalajara, Jalisco (Mexico); Gurinov, Andrey [Research Resources Center for Magnetic Resonance, St. Petersburg State University, Universitetskiy pr. 26, 198504 St. Petersburg (Russian Federation); NMR Core Lab, King Abdullah University of Science and Technology, Thuwal 23955-6900 (Saudi Arabia); Pérez Centeno, Armando; Ceja Andrade, Israel [Departamento de Física, Universidad de Guadalajara, Boulevard Marcelino García Barragán 1421, C.P. 44430, Guadalajara, Jalisco (Mexico); Carbajal Arízaga, Gregorio Guadalupe, E-mail: gregoriocarbajal@yahoo.com.mx [Departamento de Química, Universidad de Guadalajara, Boulevard Marcelino García Barragán 1421, C.P. 44430, Guadalajara, Jalisco (Mexico)

    2016-01-15

    Graphical abstract: - Highlights: • LDH structure including dysprosium was prepared by co-precipitation. • LDH was capable to produce contrast in the T1 mode of MRI. • LDH were intercalated with folate, ibuprofen and gallate ions. - Abstract: A layered double hydroxide structure including dysprosium cations was prepared by co-precipitation. The nanoparticles showed a linear relationship with the reciprocal relaxation spin-lattice (T1) time of water protons which is reflected as contrast in aqueous suspensions analyzed by magnetic resonance imaging. The interlayer space of dysprosium containing LDH was successfully intercalated with folate, ibuprofen and gallate ions, which are key molecules for recognition of some cancer cells and treatment of diseases. The paramagnetic property of the dysprosium-containing LDH detected in this work beside the ability to transport drugs open up the opportunity to design theranostic materials in a single crystal phase with nanometric dimensions.

  15. Dysprosium-containing layered double hydroxides nanoparticles intercalated with biologically active species as an approach for theranostic systems

    KAUST Repository

    Arratia-Quijada, Jenny

    2015-10-23

    A layered double hydroxide structure including dysprosium cations was prepared by co-precipitation. The nanoparticles showed a linear relationship with the reciprocal relaxation spin-lattice (T1) time of water protons which is reflected as contrast in aqueous suspensions analyzed by magnetic resonance imaging. The interlayer space of dysprosium containing LDH was successfully intercalated with folate, ibuprofen and gallate ions, which are key molecules for recognition of some cancer cells and treatment of diseases. The paramagnetic property of the dysprosium-containing LDH detected in this work beside the ability to transport drugs open up the opportunity to design theranostic materials in a single crystal phase with nanometric dimensions.

  16. Superhydrophobic and UV-blocking cotton fabrics prepared by layer-by-layer assembly of organic UV absorber intercalated layered double hydroxides

    Science.gov (United States)

    Zhao, Yan; Xu, Zhiguang; Wang, Xungai; Lin, Tong

    2013-12-01

    A dual-functional coating with both superhydrophobic and UV-blocking properties was prepared on cotton fabric using a hybrid layered double hydroxide (LDH) nanoplatelet intercalated with 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid (HMBS) molecules and an electrostatic layer-by-layer (LbL) assembly technique. The thermal stability of HMBS was greatly enhanced by the host-guest interaction with LDH layers. The as-prepared HMBS@LDH hybrid had a nearly neutral surface charge. To make it carry enough charge for the electrostatic LbL assembly, the HMBS@LDH nanoplatelet was further modified with 3-aminopropyltriethoxy silane. The nanoscale roughness generated by LDH nanoplatelets, together with low-surface-energy fluoroalkylsilane, endowed cotton fabrics with superhydrophobicity. The HMBS@LDH coating showed up to four-fold increase in the UV protection ability of cotton fabrics.

  17. Studies on the intercalation of naproxen into layered double hydroxide and its thermal decomposition by in situ FT-IR and in situ HT-XRD

    Science.gov (United States)

    Wei, Min; Shi, Shuxian; Wang, Ji; Li, Yong; Duan, Xue

    2004-07-01

    Layered double hydroxides, novel anionic clay, meet the first requirement as inorganic matrices for encapsulating functional drugs or biomolecules with negative charge in aqueous media. In this study, naproxen has been intercalated into Mg-Al layered double hydroxide by the methods of ion exchange. The structure and composition of the intercalated material have been studied by X-ray diffraction (XRD), UV-vis spectroscopy and inductively coupled plasma emission spectroscopy. A schematic model has been proposed. Furthermore, in situ Fourier transform infrared spectroscopy, in situ high-temperature XRD, and thermogravimetry (TG) have been used to characterize the thermal decomposition of the hybrid material. It has been found that the thermal stability of the intercalated naproxen is significantly enhanced compared with the pure form before intercalation, which suggests that this drug-inorganic layered material may have prospective application as the basis of a novel drug delivery system.

  18. Synthesis and characterization of Zn-Ti layered double hydroxide intercalated with cinnamic acid for cosmetic application

    Science.gov (United States)

    Li, Yong; Tang, Liping; Ma, Xinxu; Wang, Xinrui; Zhou, Wei; Bai, Dongsheng

    2017-08-01

    The use of sunscreen is recently growing and their efficacy and safety must be taken into account since they are applied on the skin frequently. In this work, an organic ultraviolet (UV) ray absorbent, cinnamic acid (CA) was intercalated into Zn-Ti layered double hydroxide (LDH) by anion-exchange reaction. ZnTi-CA-LDH, a new type of host-guest UV-blocking material has been synthesized. Detailed structural and surface morphology of ZnTi-CA-LDH were characterized by XRD, FT-IR, SEM and TEM. ZnTi-CA-LDH exhibits a superior UV blocking ability compared to pure CA and ZnTi-CO3-LDH. The thermal stability of the intercalated ZnTi-CA-LDH was investigated by TG-DTA, which showed that the thermostability of CA was markedly enhanced after intercalation into ZnTi-CO3-LDH. The EPR data showed greatly decreased photocatalytic activity compared to common inorganic UV blocking agents TiO2 and ZnO. Furthermore, the sample was formulated in a sunscreen cream to study the matrix protective effect towards UV rays.

  19. Toxicity and metabolism of layered double hydroxide intercalated with levodopa in a Parkinson's disease model.

    Science.gov (United States)

    Kura, Aminu Umar; Ain, Nooraini Mohd; Hussein, Mohd Zobir; Fakurazi, Sharida; Hussein-Al-Ali, Samer Hasan

    2014-04-09

    Layered hydroxide nanoparticles are generally biocompatible, and less toxic than most inorganic nanoparticles, making them an acceptable alternative drug delivery system. Due to growing concern over animal welfare and the expense of in vivo experiments both the public and the government are interested to find alternatives to animal testing. The toxicity potential of zinc aluminum layered hydroxide (ZAL) nanocomposite containing anti-Parkinsonian agent may be determined using a PC 12 cell model. ZAL nanocomposite demonstrated a decreased cytotoxic effect when compared to levodopa on PC12 cells with more than 80% cell viability at 100 µg/mL compared to less than 20% cell viability in a direct levodopa exposure. Neither levodopa-loaded nanocomposite nor the un-intercalated nanocomposite disturbed the cytoskeletal structure of the neurogenic cells at their IC50 concentration. Levodopa metabolite (HVA) released from the nanocomposite demonstrated the slow sustained and controlled release character of layered hydroxide nanoparticles unlike the burst uptake and release system shown with pure levodopa treatment.

  20. Phosphate-intercalated Ca-Fe-layered double hydroxides: Crystal structure, bonding character, and release kinetics of phosphate

    Science.gov (United States)

    Woo, Myong A.; Woo Kim, Tae; Paek, Mi-Jeong; Ha, Hyung-Wook; Choy, Jin-Ho; Hwang, Seong-Ju

    2011-01-01

    The nitrate-form of Ca-Fe-layered double hydroxide (Ca-Fe-LDH) was synthesized via co-precipitation method, and its phosphate-intercalates were prepared by ion-exchange reaction. According to X-ray diffraction analysis, the Ca-Fe-LDH-NO 3- compound and its H 2PO 4--intercalate showed hexagonal layered structures, whereas the ion-exchange reaction with HPO 42- caused a frustration of the layer ordering of LDH. Fe K-edge X-ray absorption spectroscopy clearly demonstrated that the Ca-Fe-LDH lattice with trivalent iron ions was well-maintained after the ion-exchange with HPO 42- and H 2PO 4-. Under acidic conditions, phosphate ions were slowly released from the Ca-Fe-LDH lattice and the simultaneous release of hydroxide caused the neutralization of acidic media. Fitting analysis based on kinetic models indicated a heterogeneous diffusion process of phosphates and a distinct dependence of release rate on the charge of phosphates. This study strongly suggested that Ca-Fe-LDH is applicable as bifunctional vector for slow release of phosphate fertilizer and for the neutralization of acid soil.

  1. Insights into the Synthesis of Layered Double Hydroxide (LDH) Nanoparticles: Part 1. Optimization and Controlled Synthesis of Chloride-Intercalated LDH

    OpenAIRE

    Sun, Xiaodi; Neuperger, Erica; Dey, Sandwip K.

    2015-01-01

    Layered double hydroxide (LDH) nanoparticles have excellent anion-intercalating property, and their potential as theranostic nanovectors is high. However, understanding of the control of the mean particle size (MPS) and achievement of monodispersed particle size distribution (PSD) remains elusive. Herein, with the aid of statistical design of experiments on a model system of Cl−-intercalated (Zn, Al)-LDH, controlled synthesis of single crystalline nanoparticles using the coprecipitation metho...

  2. A solid state NMR study of layered double hydroxides intercalated with para-amino salicylate, a tuberculosis drug

    DEFF Research Database (Denmark)

    Jensen, Nicholai Daugaard; Bjerring, Morten; Nielsen, Ulla Gro

    2016-01-01

    Para-amino salicylate (PAS), a tubercolosis drug, was intercalated in three different layered double hydroxides (MgAl, ZnAl, and CaAl-LDH) and the samples were studied by multi-nuclear (1H, 13C, and 27Al) solid state NMR (SSNMR) spectroscopy in combination with powder X-ray diffraction (PXRD......), elemental analysis and IR-spectroscopy to gain insight into the bulk and atomic level structure of these LDHs especially with a view to the purity of the LDH-PAS materials and the concentration of impurities. The intercalations of PAS in MgAl-, ZnAl-, and CaAl-LDH's were confirmed by 13C SSNMR and PXRD...... showed that the M(II):Al ratio was higher than predicted from the bulk metal composition of MgAl-PAS and ZnAl-PAS. Moreover, the first high-resolution 1H SSNMR spectra of a CaAl LDH is reported and assigned using 1H single and double quantum experiments in combination with 27Al{1H} HETCOR....

  3. Novel layered pesticide slow/controlled release materials--supramolecular structure and slow release property of glyphosate intercalated layered double hydroxides

    Institute of Scientific and Technical Information of China (English)

    MENG Jinhong; ZHANG Hui; David G. Evans; DUAN Xue

    2005-01-01

    Two different interlayer structured glyphosate (GLY) intercalated MgAl layered double hydroxides, as novel pesticide slow/controlled release materials, have been synthesized by co-precipitation method under various reaction pH values. The slow/controlled release properties have been tested in Na2CO3 aqueous solution. The release mechanism has been interpreted on the basis of the ion-exchange between the guest GLY anions in the lamellar host and in the release media, and the diffusion process of GLY anions in the interstice and interlayer of GLY intercalates, i.e. diffusion through the particles, is the rate-limiting step of GLY release process. The GLY intercalate assembled at lower pH, possessing higher interlayer gallery height and vertical monolayered arrangement of guest anions in the interlayer with larger packing density, exhibits better slow release property than that assembled at higher pH. The results reveal that the layered double hydroxides have potential application in the pesticide slow/controlled release area.

  4. Influence of carbonate intercalation in the surface-charging behavior of Zn-Cr layered double hydroxides

    Energy Technology Data Exchange (ETDEWEB)

    Rojas, R., E-mail: rrojas@mail.fcq.unc.edu.ar [INFIQC, Departamento de Fisicoquimica, Facultad de Ciencias Quimicas, Universidad Nacional de Cordoba, Ciudad Universitaria, 5000 Cordoba (Argentina); Barriga, C. [Departamento de Quimica Inorganica e Ingenieria Quimica, Edificio Marie Curie, Campus de Rabanales, Universidad de Cordoba, 14071 Cordoba (Spain); De Pauli, C.P. [INFIQC, Departamento de Fisicoquimica, Facultad de Ciencias Quimicas, Universidad Nacional de Cordoba, Ciudad Universitaria, 5000 Cordoba (Argentina); Avena, M.J. [Departamento de Quimica, Universidad Nacional del Sur, Avenida Alem 1253, 8000 Bahia Blanca (Argentina)

    2010-01-15

    The influence of interlayer composition in the surface charge and reactivity of layered double hydroxides (LDHs) has been explored. With this purpose, a chloride-intercalated Zn-Cr-LDH has been synthesized by the constant pH coprecipitation method and afterwards exchanged with carbonate to obtain solids with different Cl{sup -}/CO{sub 3}{sup 2-} ratios. The solids structure has been characterized by elemental chemical analysis, powder X-ray diffraction and infrared spectroscopy, while its surface-charging behavior and reactivity have been studied by acid-base potentiometric titrations and electrophoretic mobility determinations. The chloride-intercalated sample shows an increasing hydroxyl adsorption with increasing pH and decreasing support electrolyte concentration and the particles present positive electrophoretic mobility in the measured pH range. As carbonate content increases in the samples, the total OH{sup -} uptake diminishes and the samples show an isoelectric point at pH around 10. When the gallery is totally occupied by carbonate anions, the OH uptake vs. pH curves registered at different electrolyte concentrations merge at around pH 10. A LDH-water interface model has been used to give an interpretation to the experimental data. The model indicates that as carbonate content increases, the sample behavior becomes similar to that of a metal (hydr)oxide and that surface (bi)carbonate anions undergo acid-base reactions.

  5. Tribological performance of Mg/Al/Ce layered double hydroxides nanoparticles and intercalated products as lubricant additives

    Science.gov (United States)

    Li, Shuo; Qin, Haojing; Zuo, Ranfang; Bai, Zhimin

    2015-10-01

    Mg/Al/Ce ternary layered double hydroxides (LDHs) were synthesized via coprecipitation and intercalated by succinic acid and lauric acid through ion exchange method respectively. The LDHs products were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and Fourier transform infrared (FT-IR). Tribological properties of LDHs as lubricant additives were evaluated by four-ball friction and air compressor test. The results indicated that Mg/Al/Ce LDHs were prepared successfully with Ce/Al molar ratio of 0.05 and crystallization temperature of 140 °C. The interlayer spacing of LDHs precursor was expanded by succinic acid and lauric acid to 8.838 and 17.519 Å respectively. All the three LDHs products can reduce friction and wear of engine lubricating oil in the tests. LDHs intercalated with lauric acid showed best tribological performance among them which was attributed to sliding each other between laminates, good dispersibility in oil medium and a protective tribofilm formed on the worn surface.

  6. Kinetics of intercalation of fluorescent probes in magnesium-aluminium layered double hydroxide within a multiscale reaction-diffusion framework

    Science.gov (United States)

    Saliba, Daniel; Al-Ghoul, Mazen

    2016-11-01

    We report the synthesis of magnesium-aluminium layered double hydroxide (LDH) using a reaction-diffusion framework (RDF) that exploits the multiscale coupling of molecular diffusion with chemical reactions, nucleation and growth of crystals. In an RDF, the hydroxide anions are allowed to diffuse into an organic gel matrix containing the salt mixture needed for the precipitation of the LDH. The chemical structure and composition of the synthesized magnesium-aluminium LDHs are determined using powder X-ray diffraction (PXRD), thermo-gravimetric analysis, differential scanning calorimetry, solid-state nuclear magnetic resonance (SSNMR), Fourier transform infrared and energy dispersive X-ray spectroscopy. This novel technique also allows the investigation of the mechanism of intercalation of some fluorescent probes, such as the neutral three-dimensional rhodamine B (RhB) and the negatively charged two-dimensional 8-hydroxypyrene-1,3,6-trisulfonic acid (HPTS), using in situ steady-state fluorescence spectroscopy. The incorporation of these organic dyes inside the interlayer region of the LDH is confirmed via fluorescence microscopy, solid-state lifetime, SSNMR and PXRD. The activation energies of intercalation of the corresponding molecules (RhB and HPTS) are computed and exhibit dependence on the geometry of the involved probe (two or three dimensions), the charge of the fluorescent molecule (anionic, cationic or neutral) and the cationic ratio of the corresponding LDH. This article is part of the themed issue 'Multiscale modelling at the physics-chemistry-biology interface'.

  7. Mössbauer and XRD study of intercalated CaFe-layered double hydroxides

    Science.gov (United States)

    Sipiczki, Mónika; Kuzmann, Ernő; Pálinkó, István; Homonnay, Zoltán; Sipos, Pál; Kukovecz, Ákos; Kónya, Zoltán

    2014-04-01

    N-containing fully saturated (L-prolinate) or aromatic (indole-2-carboxylate) heterocyclic anions were immobilised in CaFe-layered double hydroxide with the dehydration-rehydration method from aqueous ethanol or acetone. The structure of the resulting organic-inorganic hybrids was characterised mainly with powder X-ray diffraction and 57Fe Mössbauer spectroscopy, and as supplementary analysis scanning electron microscopy, energy dispersive X-ray spectroscopy with elemental mapping and molecular modelling were also applied. It was found that the solvent mixture used for the synthesis caused enormous difference in the interlayer spacings of the obtained inorganic-organic hybrids.

  8. Novel inorganic host layered double hydroxides intercalated with guest organic inhibitors for anticorrosion applications.

    Science.gov (United States)

    Poznyak, S K; Tedim, J; Rodrigues, L M; Salak, A N; Zheludkevich, M L; Dick, L F P; Ferreira, M G S

    2009-10-01

    Zn-Al and Mg-Al layered double hydroxides (LDHs) loaded with quinaldate and 2-mercaptobenzothiazolate anions were synthesized via anion-exchange reaction. The resulting compounds were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy/energy-dispersive X-ray spectroscopy. Spectrophotometric measurements demonstrated that the release of organic anions from these LDHs into the bulk solution is triggered by the presence of chloride anions, evidencing the anion-exchange nature of this process. The anticorrosion capabilities of LDHs loaded with organic inhibitors toward the AA2024 aluminum alloy were analyzed by electrochemical impedance spectroscopy. A significant reduction of the corrosion rate is observed when the LDH nanopigments are present in the corrosive media. The mechanism by which the inhibiting anions can be released from the LDHs underlines the versatility of these environmentally friendly structures and their potential application as nanocontainers in self-healing coatings.

  9. An ethylene glycol intercalated monometallic layered double hydroxide based on iron as an efficient bifunctional catalyst.

    Science.gov (United States)

    Nagarajan, Rajamani; Gupta, Pankaj; Singh, Poonam; Chakraborty, Pinki

    2016-11-01

    Given the fact that the literature describing the intercalation of organic molecules in monometallic LDH systems is scarce, the present investigation is aimed at the generation of ethylene glycol intercalated Fe(II)-Fe(III) LDH with the objective of enhancing the surface area for further catalytic applications of industrially important and environmentally harmful organics. The solvothermal reaction of FeCl3 with urea in an ethylene glycol medium yielded a brown colored powder which was characterized employing a wide range of analytical techniques including high resolution powder X-ray diffraction (PXRD), scanning electron microscopy, thermal analysis, X-ray photo electron spectroscopy (XPS), elemental (C, H, N and S) analysis, UV-visible, photoluminescence spectroscopy measurements, BET surface area and pore-size analysis. The observed reflections in the PXRD pattern were indexed in a rhombohedral symmetry with a = 3.175 and c = 31.9 Å. Combining the results from the Fe 2p core level analysis and anion contents from elemental and thermogravimetric analysis, a formula of Fe(2+)1.06 Fe(3+)0.94 (O2C2H4) (OH)4 was deduced for the sample. The intercalation of EG in the interlayer was confirmed from FTIR and Raman spectroscopy measurements. The d-d transitions of the Fe(3+)-ion and the charge transfer transition of the Fe(ii)-Fe(iii) lattice were evident in the UV-visible spectrum. Blue indigoid emission bands arising from the transitions present in the Fe(3+)-ion were noticed in the photoluminescence spectrum. The measured BET surface area and pore diameter of the sample were 144 m(2) g(-1) and 12.5 nm, respectively. Almost instant decolourisation of the Xylenol Orange (XO) dye occurred in the presence of H2O2 and the LDH sample as catalyst. Similar observations were encountered for Methyl Orange (MO) and Methylene Blue (MB) dyes. All these reactions followed pseudo first-order kinetics. The industrially important reductive conversion of nitro aromatics was catalyzed

  10. Computer simulation of interlayer arrangement in cinnamate intercalated layered double hydroxides

    Science.gov (United States)

    Greenwell, H. C.; Jones, W.; Newman, S. P.; Coveney, P. V.

    2003-02-01

    The interlayer arrangements of Mg-Al layered double hydroxides (LDHs) containing trans-cinnamate anions have been studied using molecular dynamics computer simulations. A modified version of the Dreiding forcefield was used to perform simulations of models with Mg/Al ratios of 2,3 and 6. For each Mg/Al ratio, two hydration states of 20 and 30 wt% water content were modelled. Close contacts between the olefinic carbons of the anion were analysed in an attempt to rationalize the potential outcome of the [2+2] photo-induced dimerization of the anions. In all instances, except for the model with Mg/Al=6 and 20 wt% water, the arrangement of the dimer pairs showed that syn-head-to-tail dimer formation was unfavourable. Preferred orientation of dimer pairs towards formation of head-to-head dimers was observed to undergo a transition from strongly favouring the syn-head-to-head dimer at low Mg/Al ratios to greater selectivity for the anti-head-to-head dimer with increasing Mg/Al ratio. The model with Mg/Al=6 and 20 wt% water content was observed to have a very disordered interlayer arrangement, with preference towards anion-pair arrangements favouring syn-head-to-tail dimer formation. The model with Mg/Al=6 and 30 wt% water content was predicted to exhibit only trans- cis isomerisation.

  11. Zn–Al layered double hydroxides intercalated with carbonate, nitrate, chloride and sulphate ions: Synthesis, characterisation and dye removal properties

    Directory of Open Access Journals (Sweden)

    Fatima Zahra Mahjoubi

    2017-01-01

    Full Text Available In this work, Zn–Al layered double hydroxides intercalated with carbonate, nitrate, chloride and sulphate ions were synthesised via a co-precipitation method at a constant solution pH. The as-synthesised samples were characterised by X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FTIR, transmission electron microscopy (TEM and simultaneous thermogravimetric/differential thermal analysis (TGA-DTA. The XRD patterns showed that Zn-Al-SO4 had the greatest interlayer spacing, followed by Zn-Al-Cl, Zn-Al-NO3 and Zn-Al-CO3. The FTIR spectra clearly confirmed the presence of intercalated anions in the structure of the LDHs. Batch experiments for methyl orange (MO adsorption onto synthesised samples were investigated under various conditions such as contact time, initial dye concentration and solution pH. The experimental results show that pH is the most influencing factor. The effective pH range for the MO removal was found to be 3.5–4.5. The kinetics data can be described accurately by a pseudo-second-order kinetic model instead of a pseudo-first-order model. The equilibrium data were analysed using the Langmuir, Freundlich and Dubinin–Radushkevich models. The results showed that the Langmuir and Dubinin–Radushkevich isotherm models fit well to the experimental data. The Zn-Al-LDH samples exhibited exceptional Langmuir maximum adsorption capacities of 2758, 2455, 2270 and 1684 mg/g for Zn-Al-SO4, Zn-Al-Cl, Zn-Al-NO3 and Zn-Al-CO3, respectively.

  12. Chemical reactive features of novel amino acids intercalated layered double hydroxides in As(III) and As(V) adsorption.

    Science.gov (United States)

    Shen, Liang; Jiang, Xiuli; Chen, Zheng; Fu, Dun; Li, Qingbiao; Ouyang, Tong; Wang, Yuanpeng

    2017-06-01

    Layered double hydroxides (LDHs) intercalated with amino acids such as methionine (Met) were synthesized as new adsorbents to remediate arsenic-polluted water. This Zn2Al-Met-LDHs, identified with the formula of Zn0.7Al0.3(OH)2(Met)0.3·0.32H2O, has good thermal stability. Adsorption experiments with Zn2Al-Met-LDHs showed that the residual arsenic in solution could be reduced below the regulation limit, and this adsorption process fitted Langmuir isotherm and the pseudo-second-order kinetics well. A remarkably high removal efficiency and the maximum adsorption capacity for As(III) were achieved, 96.7% and 94.1 mg/g, respectively, at 298 K. The desorption efficiency of As(III) from the arsenic-saturated Zn2Al-Met-LDHs (<8.7%), far less than that of As(V), promises a specific and reliable uptake of As(III) in sorts of solutions. More importantly, a complete and in-depth spectra analysis through FTIR, XPS and NMR was conducted to explain the excellent performance of Zn2Al-Met-LDHs in arsenic removal. Herein, two special chemical reactions were proposed as the dominant mechanisms, i.e., hydrogen bonding between the carboxyl group of the host Met and the hydroxyl group of As(III) or As(V), and the formation of a chelate ring between the guest As(III) and the S, N bidentate ligands of the intercalated Met in the LDHs.

  13. Enhancement photocatalytic degradation of rhodamine B on nanoPt intercalated Zn–Ti layered double hydroxides

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Guixiang; Qian, Shengming; Tu, Xinman, E-mail: tuxinman@126.com; Wei, Xiaoyong; Zou, Jianping; Leng, Lehui; Luo, Shenglian, E-mail: sllou@hnu.edu.cn

    2014-02-28

    NanoPt intercalated Zn–Ti layered double hydroxides (LDHs) have been synthesized by ionic exchange and photochemical reduction method from Zn–Ti LDHs in H{sub 2}PtCl{sub 6} solution. X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), N{sub 2} adsorption at 77 K, UV–vis analysis and the electrochemical impedance were adopted to investigate the structure, surface, micromorphology, photoresponsive and electrochemical properties of the as-synthesized samples. The combination of Zn–Ti-LDHs and Pt introduces some properties of Pt into photocatalysis such as excellent conductivity and controllability. Remarkable 17-fold enhancement in the degradation of rhodamine B (RhB) reaction was observed on as-prepared Pt/Zn–Ti LDHs compared with pure Zn–Ti LDHs under simulated sunlight irradiation. The enhanced photocatalytic activity could be attributed to high specific surface (111.46 m{sup 2}/g), extended photoresponding range, the negative shift in the flat-band potentials and the high migration efficiency of photoinduced electrons, which may suppress the charge recombination effectively.

  14. Synthesis, sustained release properties of magnetically functionalized organic-inorganic materials: Amoxicillin anions intercalated magnetic layered double hydroxides via calcined precursors at room temperature

    Science.gov (United States)

    Wang, Jun; Liu, Qi; Zhang, Guangchun; Li, Zhanshuang; Yang, Piaoping; Jing, Xiaoyan; Zhang, Milin; Liu, Tianfu; Jiang, Zhaohua

    2009-09-01

    Zinc-aluminum-carbonate-layered double hydroxides (ZnAl-CO 3-LDHs), loaded with magnetic substrates (Fe 3O 4), were prepared for sustained drug-targeting delivery. From the X-ray diffraction results, it was found that the magnetic substrates were successfully incorporated with LDHs and highly dispersed in the hydrotalcite structure. After intercalation with an antibiotic drug (amoxicillin) by using a calcinations-reconstruction method, the basal spacing of layered double hydroxides increased from 7.51 Å to 12.35 Å, indicating that amoxicillin was successfully intercalated into the interlay space of LDHs as a monolayer. Furthermore, in vitro drug release experiments in pH 7.4 phosphate buffer solution (PBS) showed sustained release profiles with amoxicillin as a model drug. Magnetic measurements revealed that the composite possessed paramagnetic properties at room temperature.

  15. In Vitro Inhibition of Histamine Release Behavior of Cetirizine Intercalated into Zn/Al- and Mg/Al-Layered Double Hydroxides

    Directory of Open Access Journals (Sweden)

    Muhammad Nazrul Hakim

    2012-05-01

    Full Text Available The intercalation of cetirizine into two types of layered double hydroxides, Zn/Al and Mg/Al, has been investigated by the ion exchange method to form CTZAN and CTMAN nanocomposites, respectively. The basal spacing of the nanocomposites were expanded to 31.9 Å for CTZAN and 31.2 Å for CTMAN, suggesting that cetirizine anion was intercalated into Layered double hydroxides (LDHs and arranged in a tilted bilayer fashion. A Fourier transform infrared spectroscopy (FTIR study supported the formation of both the nanocomposites, and the intercalated cetirizine is thermally more stable than its counterpart in free state. The loading of cetirizine in the nanocomposite was estimated to be about 57.2% for CTZAN and 60.7% CTMAN. The cetirizine release from the nanocomposites show sustained release manner and the release rate of cetirizine from CTZAN and CTMAN nanocomposites at pH 7.4 is remarkably lower than that at pH 4.8, presumably due to the different release mechanism. The inhibition of histamine release from RBL2H3 cells by the free cetirizine is higher than the intercalated cetirizine both in CTZAN and CTMAN nanocomposites. The viability in human Chang liver cells at 1000 μg/mL for CTZAN and CTMAN nanocomposites are 74.5 and 91.9%, respectively.

  16. Interlayer intercalation and arrangement of 2-mercaptobenzothiazolate and 1,2,3-benzotriazolate anions in layered double hydroxides: In situ X-ray diffraction study

    Science.gov (United States)

    Serdechnova, Maria; Salak, Andrei N.; Barbosa, Filipe S.; Vieira, Daniel E. L.; Tedim, João; Zheludkevich, Mikhail L.; Ferreira, Mário G. S.

    2016-01-01

    2-mercaptobenzothiazole (MBT) and 1,2,3-benzotriazole (BTA) are very promising inhibitors for the corrosion protection of aluminum alloys. These inhibitors can be incorporated in protective coatings in the form of anions intercalated into interlayers of layered double hydroxides (LDHs). Capacity and performance of such LDH-nanocontainers depend on the arrangement of the anions in their interlayers. In this work, intercalation of MBT- and BTA- into Mg-Al-NO3 and Zn-Al-NO3 LDHs were studied in detail using X-ray diffraction (XRD) methods including in situ XRD. The nitrate-to-MBT(BTA) anion exchange is much faster than considered previously. Well-formed Mg-Al-MBT, Zn-Al-MBT, Mg-Al-BTA LDHs were obtained after a 20-min exchange reaction at pH 11.5 at room temperature. It was demonstrated that Zn-Al-BTA LDH cannot be obtained under the same conditions due to the reaction between BTA and the Zn-Al hydroxide layers. Substitution of nitrates by organic anions occurs with the participation of hydroxide anions. Although no intermediate LDH phase intercalated with the combination of NO3 - and OH- appears, formation of the LDH-MBT and LDH-BTA phases results also in appearance of an LDH phase intercalated with OH- at the final stage of the anion exchange. In the LDH interlayer, MBT- and BTA- form a double layer in which these species have a tilted orientation against the layer plane (herringbone-like arrangement). Such an arrangement meets the LDH layer-interlayer electroneutrality and matches well with the observed values of the layer-interlayer distance.

  17. Organic–inorganic hybrid nanocomposites based on chitosan derivatives and layered double hydroxides with intercalated phacolysin as ocular delivery system

    Energy Technology Data Exchange (ETDEWEB)

    Qin, Zhiguo; Zhang, Jie; Chi, Huibo; Cao, Feng, E-mail: cpufengc@163.com [China Pharmaceutical University, Department of Pharmaceutics, School of Pharmacy (China)

    2015-12-15

    This study was mainly aimed to evaluate the potential use of a novel ocular drug delivery system, organic–inorganic hybrid nanocomposites based on chitosan derivatives and layered double hydroxides (LDH). Organic polymers of chitosan–glutathione (CG) and pre-activated chitosan–glutathione (CG-2MNA) were successfully synthesized and characterized. LDH with intercalated phacolysin (PCL), including larger hexagonal LDH–PCL (Lh-LDH–PCL), larger spherical LDH–PCL (Ls-LDH–PCL), smaller hexagonal LDH–PCL (Sh-LDH–PCL), CG hybrid LDH–PCL (LDH–PCL-CG), and CG-2MNA hybrid LDH–PCL (LDH–PCL-CG-2MNA), were prepared. The nanocomposites with particle size of 107.2–274.9 nm were characterized by powder X-ray diffraction, Fourier transform infrared, transmission electron micrographs, etc. In vivo precorneal retention studies showed that the detectable time of all nanocomposites was prolonged from 2 to 6 h in comparison to PCL saline. Accordingly, the AUC{sub 0–6h} values of Lh-LDH–PCL, Ls-LDH–PCL, Sh-LDH–PCL, LDH–PCL-CG, and LDH–PCL-CG-2MNA nanocomposites were increased by 2.27-, 2.08-, 3.08-, 4.67-, and 3.36-fold, respectively. The Draize test and hematoxylin and eosin staining demonstrated that modified LDH had no eye irritation after single and repeated administration. These results indicated that chitosan derivatives-LDH hybrid nanocomposite dispersion could be a promising ocular drug delivery system to improve precorneal retention time of drugs.Graphical AbstractThiolated chitosan-LDH hybrid nanocomposite dispersion could be a promising ocular drug delivery system to improve precorneal retention time of drugs and may facilitate penetration of drugs into tissues of the eyes.

  18. Nanostructural drug-inorganic clay composites: Structure, thermal property and in vitro release of captopril-intercalated Mg Al-layered double hydroxides

    Science.gov (United States)

    Zhang, Hui; Zou, Kang; Guo, Shaohuan; Duan, Xue

    2006-06-01

    A nanostructural drug-inorganic clay composite involving a pharmaceutically active compound captopril (Cpl) intercalated Mg-Al-layered double hydroxides (Cpl-LDHs) with Mg/Al molar ratio of 2.06 has been assembled by coprecipitation method. Powder X-ray diffraction (XRD), Fourier transform infrared spectra (FT-IR) and Raman spectra analysis indicate a successful intercalation of Cpl between the layers with a vertical orientation of Cpl disulphide-containing S-S linkage. SEM photo indicates that as-synthesized Cpl-LDHs possess compact and non-porous structure with approximately and linked elliptical shape particles of ca. 50 nm. TG-DTA analyses suggest that the thermal stability of intercalated organic species is largely enhanced due to host-guest interaction involving the hydrogen bond compared to pure form before intercalation. The in vitro release studies show that both the release rate and release percentages markedly decrease with increasing pH from 4.60 to 7.45 due to possible change of release mechanism during the release process. The kinetic simulation for the release data, and XRD and FT-IR analyses for samples recovered from release media indicate that the dissolution mechanism is mainly responsible for the release behaviour of Cpl-LDHs at pH 4.60, while the ion-exchange one is responsible for that at pH 7.45.

  19. Soft-chemical synthesis and catalytic activity of Ni-Al and Co-Al layered double hydroxides (LDHs intercalated with anions with different charge density

    Directory of Open Access Journals (Sweden)

    Takahiro Takei

    2014-09-01

    Full Text Available Co-Al and Ni-Al layered double hydroxides (LDHs intercalated with three types of anionic molecules, dodecylsulfate (C12H25SO4−, DS, di-2-ethylsulfosuccinate ([COOC2H3EtBu]2C2H3SO3−, D2ES, and polytungstate (H2W12O4210−, HWO were prepared by means of ion-exchange and co-precipitation processes. With the use of DS and D2ES as intercalation agents, high crystallinity was maintained after intercalation into the LDHs. In the case of HWO, the intercalated LDHs could be obtained by ion-exchange as well as co-precipitation with a decline in the crystallinity; however, unreacted LDH was detected in the ion-exchange samples, and some unwanted phases such as hydroxide and pyrochlore were generated by the co-precipitation process. The maximum specific surface area and pore volume of the Ni-Al sample with intercalated HWO, prepared by the ion-exchange process were 74 m2/g and 0.174 mL/g, respectively. The occupancies of DS, D2ES, and HWO within the interlayer space were approximately 0.3–0.4, 0.5–0.6, and 0.1–0.2, respectively, in the Co-Al and Ni-Al LDHs. Analysis of the catalytic activity demonstrated that the DS-intercalated Ni-Al LDH sample exhibited relatively good catalytic activity for conversion of cyclohexanol to cyclohexanone.

  20. Mössbauer, XRD and TEM Study on the Intercalation and the Release of Drugs in/from Layered Double Hydroxides

    Directory of Open Access Journals (Sweden)

    E. Kuzmann

    2015-12-01

    Full Text Available Layered double hydroxides (LDHs are one of the very important nano-carriers for drug delivery, due to their many advantageous features, such as the ease and low-cost of preparation, low cytotoxicity, good biocompatibility, protection for the intercalated drugs, and the capacity to facilitate the uptake of the loaded drug in the cells. In our previous studies, Mössbauer spectroscopy was applied to monitor structural changes occurring during the incorporation of Fe(III in MgFe- and CaFe-LDHs, and the intercalation of various organic compounds in anionic form. Recently, we have successfully elaborated a protocol for the intercalation and release of indol-2-carboxylate and L-cysteinate in CaFe-LDH. The corresponding structural changes in the LDH samples were studied by XRD, HR-TEM and 57Fe Mössbauer spectroscopy. The Mössbauer spectra reflected small but significant changes upon both the intercalation and the release of drugs. The changes in the basal distances could be followed by XRD measurements, and HR-TEM images made these changes visible.

  1. Simultaneous intercalation and release of 2,4-dichloro- and 4-chloro-phenoxy acetates into Zn/Al layered double hydroxide

    Directory of Open Access Journals (Sweden)

    Abbas Matrod Bashi

    2016-11-01

    Full Text Available A new nanohybrid compound was formed by the concurrent insertion of 2,4-dichlorophenoxy acetate (DPA used as herbicides and 4-chlorophenoxy acetate (CPA as plant growth regulator, the two guest anions into the interlamellar space of the host Zn/Al layered double hydroxide (LDH using co-precipitation or spontaneous self-assembly method. Two different basal spacings of 2.54 and 1.97 nm were detected by PXRD of the nanohybrid accounting for the presence of two distinct intercalated phases. Direct insertion mass spectroscopy (DIMS analyses confirm that both anions are intercalated to give a biphasic well ordered nanohybrid material. The study of the release properties shows that both ions were released, but with different rates. This opens up the possibility of using such a biphasic nanohybrid for controlled release of more than one active anionic agent at different controlled rates.

  2. Contribution of sodium dodecyl sulphate and sodium lauric acid in the one-pot synthesis of intercalated ZnAl-layered double hydroxides

    Indian Academy of Sciences (India)

    Fengzhu Lv; Zilin Meng; Penggang Li; Yihe Zhang; Guocheng Lv; Qian Zhang; Zhilei Zhang

    2015-08-01

    Anion surfactants, sodium dodecyl sulphate (SDS) and sodium lauric acid (SLA), with almost the same chain length but different anion groups were used together as intercalates to prepare intercalated ZnAl–layered double hydroxides (ZnAl–LDHs). Their composition, structure and morphology were characterized by Fourier transform infrared, X-ray fluorescence, thermogravimetric and X-ray diffraction (XRD). The results indicated SDS intended to maintain the lamellae structure of LDHs, but SLA was more likely to expand the basal spacings of LDHs in the present system. The arrangement of the surfactants in the interlayer of ZnAl–LDHs was also simulated by Materials Studio. The basal spacings of the LDHs calculated based on simulated structure consisted with that from XRD.

  3. In Situ Formation of Decavanadate-Intercalated Layered Double Hydroxide Films on AA2024 and their Anti-Corrosive Properties when Combined with Hybrid Sol Gel Films

    Directory of Open Access Journals (Sweden)

    Junsheng Wu

    2017-04-01

    Full Text Available A layered double hydroxide (LDH film was formed in situ on aluminum alloy 2024 through a urea hydrolysis method, and a decavanadate-intercalated LDH (LDH-V film fabricated through the dip coating method. The microstructural and morphological characteristics were investigated by scanning electron microscopy (SEM. The corrosion-resistant performance was analyzed by electrochemical impedance spectroscopy (EIS, scanning electrochemical microscopy (SECM, and a salt-spray test (SST.The SEM results showed that a complete and defect-free surface was formed on the LDH-VS film. The anticorrosion results revealed that the LDH-VS film had better corrosion-resistant properties than the LDH-S film, especially long-term corrosion resistance. The mechanism of corrosion protection was proposed to consist of the self-healing effect of the decavanadate intercalation and the shielding effect of the sol-gel film.

  4. Uptake of Sc 3+ and La 3+ from aqueous solution using ethylenediaminetetraacetate-intercalated Cu-Al layered double hydroxide reconstructed from Cu-Al oxide

    Science.gov (United States)

    Kameda, Tomohito; Hoshi, Kazuaki; Yoshioka, Toshiaki

    2011-02-01

    A Cu-Al layered double hydroxide intercalated with ethylenediaminetetraacetate (edta·Cu-Al LDH) was prepared by suspending Cu-Al oxide, obtained by the calcination of CO32--intercalated Cu-Al LDH, in edta solution. It was found that the reconstruction of Cu-Al oxide to Cu-Al LDH was promoted with an increase in the temperature and time. The reaction in the pH range of around 8 suggests that Hedta 3- was intercalated in the interlayer of Cu-Al LDH. Edta·Cu-Al LDH was found to take up rare metal ions such as Sc 3+ and La 3+ in an aqueous solution at a pH of around 6-6.5. The uptake of Sc 3+ was caused not only by the chelating function of Hedta 3- in the interlayer but also by the chemical behavior of Cu-Al LDH itself. On the other hand, the uptake of La 3+ was caused only by the chelating function of Hedta 3- in the interlayer. The Hedta 3- in the interlayer of edta·Cu-Al LDH had the potential to form a chelate complex more preferentially with Sc 3+ than with La 3+.

  5. Preparation of Cu-Al layered double hydroxide intercalated with ethylenediaminetetraacetate by coprecipitation and its uptake of rare earth ions from aqueous solution

    Science.gov (United States)

    Kameda, Tomohito; Hoshi, Kazuaki; Yoshioka, Toshiaki

    2013-03-01

    A Cu-Al layered double hydroxide intercalated with ethylenediaminetetraacetate (edta•Cu-Al LDH) was prepared by the dropwise addition of a Cu-Al nitrate solution to an edta solution at constant pH values of 8.0, 9.0, and 10.0. The edta•Cu-Al LDH had Hedta3- in the interlayer. Furthermore, the preparation at pH 8.0 resulted in the intercalation of Cu(edta)2-. The edta•Cu-Al LDH was found to take up rare earth ions from aqueous solution. The uptake of Sc3+ and Y3+ by edta•Cu-Al LDH was attributed to both the chelating functions of the edta ion in the interlayer and the chemical properties of Cu-Al LDH itself. The uptake of La3+ by edta•Cu-Al LDH was primarily caused by the chelating function of edta ions in the interlayer. The edta ions in the edta•Cu-Al LDH interlayer formed chelate complexes in the order Sc3+ > Y3+ > La3+ due to their relative stabilities, Sc(edta)- > Y(edta)- > La(edta)-. Thus, edta ions retain their chelating function even when intercalated in a Cu-Al LDH interlayer.

  6. Toxicity and Metabolism of Layered Double Hydroxide Intercalated with Levodopa in a Parkinson’s Disease Model

    Directory of Open Access Journals (Sweden)

    Aminu Umar Kura

    2014-04-01

    Full Text Available Layered hydroxide nanoparticles are generally biocompatible, and less toxic than most inorganic nanoparticles, making them an acceptable alternative drug delivery system. Due to growing concern over animal welfare and the expense of in vivo experiments both the public and the government are interested to find alternatives to animal testing. The toxicity potential of zinc aluminum layered hydroxide (ZAL nanocomposite containing anti-Parkinsonian agent may be determined using a PC 12 cell model. ZAL nanocomposite demonstrated a decreased cytotoxic effect when compared to levodopa on PC12 cells with more than 80% cell viability at 100 µg/mL compared to less than 20% cell viability in a direct levodopa exposure. Neither levodopa-loaded nanocomposite nor the un-intercalated nanocomposite disturbed the cytoskeletal structure of the neurogenic cells at their IC50 concentration. Levodopa metabolite (HVA released from the nanocomposite demonstrated the slow sustained and controlled release character of layered hydroxide nanoparticles unlike the burst uptake and release system shown with pure levodopa treatment.

  7. Intercalation compounds involving inorganic layered structures

    Directory of Open Access Journals (Sweden)

    CONSTANTINO VERA R. L.

    2000-01-01

    Full Text Available Two-dimensional inorganic networks can shown intracrystalline reactivity, i.e., simple ions, large species as Keggin ions, organic species, coordination compounds or organometallics can be incorporated in the interlayer region. The host-guest interaction usually causes changes in their chemical, catalytic, electronic and optical properties. The isolation of materials with interesting properties and making use of soft chemistry routes have given rise the possibility of industrial and technological applications of these compounds. We have been using several synthetic approaches to intercalate porphyrins and phthalocyanines into inorganic materials: smectite clays, layered double hydroxides and layered niobates. The isolated materials have been characterized by elemental and thermal analysis, X-ray diffraction, surface area measurements, scanning electronic microscopy, electronic and resonance Raman spectroscopies and EPR. The degree of layer stacking and the charge density of the matrices as well their acid-base nature were considered in our studies on the interaction between the macrocycles and inorganic hosts.

  8. Insights into the synthesis of layered double hydroxide (LDH) nanoparticles: Part 1. Optimization and controlled synthesis of chloride-intercalated LDH.

    Science.gov (United States)

    Sun, Xiaodi; Neuperger, Erica; Dey, Sandwip K

    2015-12-01

    Layered double hydroxide (LDH) nanoparticles have excellent anion-intercalating property, and their potential as theranostic nanovectors is high. However, understanding of the control of the mean particle size (MPS) and achievement of monodispersed particle size distribution (PSD) remains elusive. Herein, with the aid of statistical design of experiments on a model system of Cl(-)-intercalated (Zn, Al)-LDH, controlled synthesis of single crystalline nanoparticles using the coprecipitation method followed by hydrothermal treatment (HT) was achieved in three steps. First, a 2(4-1) design enabled the identification of influential parameters for MPS (i.e., salt concentration, molar ratio of carbonate to aluminum, solution addition rate, and interaction between salt concentration and stirring rate) and PSD (i.e., salt concentration and stirring rate), as well as the optimum coprecipitation conditions that result in a monodispersed PSD (i.e., low salt concentration and high stirring rate). Second, a preliminary explanation of the HT was suggested and the optimum HT conditions for obtaining ideal Gaussian PSD with chi-squared (χ(2))<3 were found to be 85°C for 5 h. Third, using a central composite design, a quantitative MPS model, expressed in terms of the significant factors, was developed and experimentally verified to synthesize nearly monodispersed LDH nanoparticles with MPS ∼200-500 nm.

  9. Real-time tracking of hydrogen peroxide secreted by live cells using MnO{sub 2} nanoparticles intercalated layered doubled hydroxide nanohybrids

    Energy Technology Data Exchange (ETDEWEB)

    Asif, Muhammad; Aziz, Ayesha [Key Laboratory for Large-Format Battery Materials and System, Ministry of Education, Hubei Key Laboratory of Material Chemistry and Service Failure, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, 430074 (China); Dao, Anh Quang [Key Laboratory for Large-Format Battery Materials and System, Ministry of Education, Hubei Key Laboratory of Material Chemistry and Service Failure, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, 430074 (China); Hue Industrial College, 70 Nguyen Hue, Hue, Thua Thien Hue, 531081 (Viet Nam); Hakeem, Abdul; Wang, Haitao; Dong, Shuang; Zhang, Guoan [Key Laboratory for Large-Format Battery Materials and System, Ministry of Education, Hubei Key Laboratory of Material Chemistry and Service Failure, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, 430074 (China); Xiao, Fei [Key Laboratory for Large-Format Battery Materials and System, Ministry of Education, Hubei Key Laboratory of Material Chemistry and Service Failure, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, 430074 (China); Shenzhen Institute of Huazhong University of Science & Technology, Shenzhen, 518000 (China); Liu, Hongfang, E-mail: liuhf@hust.edu.cn [Key Laboratory for Large-Format Battery Materials and System, Ministry of Education, Hubei Key Laboratory of Material Chemistry and Service Failure, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, 430074 (China); Shenzhen Institute of Huazhong University of Science & Technology, Shenzhen, 518000 (China)

    2015-10-22

    We report a facile and green method for the fabrication of new type of electrocatalysts based on MnO{sub 2} nanoparticles incorporated on MgAl LDH P-type semiconductive channel and explore its practical applications as high-performance electrode materials for electrochemical biosensor. A series of MgAl layered doubled hydroxide (LDH) nanohybrids with fixed Mg/Al (M{sup 2+}/M{sup 3+} atomic ratio of 3) and varied amount of MnCl{sub 2}.4H{sub 2}O are fabricated by a facile co-precipitation method. This approach demonstrates the combination of distinct properties including excellent intercalation features of LDH for entrapping nanoparticles and high loading of MnO{sub 2} nanoparticles in the host layers of LDH. Among all samples, Mn5–MgAl with 0.04% loaded manganese has a good crystalline morphology. A well-dispersed MnO{sub 2} nanoparticles encapsulated into the host matrix of hydrotalcite exhibit enhanced electrocatalytic activity towards the reduction of H{sub 2}O{sub 2} as well as excellent stability, selectivity and reproducibility due to synergistic effect of good catalytic ability of MnO{sub 2} and conductive MgAl LDH. Glass carbon electrode (GCE) modified with Mn5–MgAl possesses a wide linear range of 0.05–78 mM, lowest detection limit 5 μM (S/N = 3) and detection sensitivity of 0.9352 μAmM{sup −1}. This outstanding performance enables it to be used for real-time tracking of H{sub 2}O{sub 2} secreted by live HeLa cells. This work may provide new insight in clinical diagnosis, on-site environmental analysis and point of care testing devices. - Highlights: • MnO{sub 2}MgAl nanohybrids have been fabricated by a facile and robust co-precipitation approach. • MgAl layered doubled hydroxide can be used for the intercalation of MnO{sub 2} nanoparticles. • MgAl layered doubled hydroxide nanohybrid serves as p-type semiconductive channel for efficient electrocatalysis. • The nanohybrid electrode demonstrates excellent electrochemical performance

  10. Sustained-Release of Cefepime from Cefepime-Intercalated Layered Double Hydroxides%头孢吡肟插层水滑石的缓释性能

    Institute of Scientific and Technical Information of China (English)

    孙志茵; 倪哲明; 李远; 夏盛杰

    2013-01-01

    用共沉淀法将头孢吡肟(Cefepime)插层到含NO3-的Zn-Al水滑石(layered double hydroxides,LDHs)层间,组装得到杂化材料Cefepime-LDHs.X射线衍射结果表明:Cefepime-LDHs晶型良好,为典型的水滑石类层状材料,其层间距为2.18rm.通过对Cefepime三维尺寸的理论模拟,推测该杂化材料中的Cefepime以沿长轴方向与层板呈一定角度倾斜的方式排布于水滑石层间.此外,与Cefepime相比,该杂化材料中层间药物的释放具有一定的缓释效果,缓释过程符合一级动力学及Higuchi扩散模型.%Cefepime pillared Zn-Al layered double hydroxides (LDHs) was assembled via coprecipitation process. Cefepime intercalated Zn-Al layered double hydroxides with good crystallinity was obtained. The results by X-ray diffraction reflected that the in-terlayer spaces of as-synthesized Cefepime-LDHs was 2.18nm. According to the simulated three-dimensional molecular size, the Cefepime guests could be arranged along the long axis orientation with a constant angle in the layers. The sustained-release of Cefepime pillared hydrotalcite were enhanced to a certain extent, compared to those of Cefepime. The release process followed both the Higuchi models and first order kinetics.

  11. Highly selective and efficient removal of arsenic(V), chromium(VI) and selenium(VI) oxyanions by layered double hydroxide intercalated with zwitterionic glycine.

    Science.gov (United States)

    Asiabi, Hamid; Yamini, Yadollah; Shamsayei, Maryam

    2017-10-05

    In this study, a new strategy for highly selective and extremely efficient removal of toxic oxyanions (Cr(VI), Se(VI), and As(V)) from aqueous solutions using zwitterionic glycine intercalated layered double hydroxide (Gly-LDH) was reported. Hence, to investigate the effect of zwitterionic glycine on the adsorption capacity, selectivity factor and adsorption mechanism of LDHs, two NiAl LDHs intercalated with different inter-layer anions, including NO3(-) and glycine, were synthesized. The obtained results show that the adsorption capacity and selectivity factor of oxyanions through ion exchange mechanism in NO3-LDH is lower than Gly-LDH. Gly-LDH displayed a selectivity order of Se(VI)V) for the oxyanions. The enormous adsorption capacity of 731.6mgg(-1) for As(V) and very high distribution coefficients (Kd) of 5.98×10(7)mLg(-1), using a V/m ratio of 2000mLg(-1), were observed, which are among the highest values reported for As(V) adsorbents. The adsorption kinetic curves for As(V) fitted well with the pseudo-second order model, suggesting a chemical adsorption mechanism via As(V)NH3(+) bonding. For the As(V) (at 40mgL(-1) concentration), the adsorption is exceptionally rapid, showing a 93.5% removal within 30min, 98.0% removal within 40min, and ∼100% removal within 70min. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Thermal decomposition behavior of Cu–Al layered double hydroxide, and ethylenediaminetetraacetate-intercalated Cu–Al layered double hydroxide reconstructed from Cu–Al oxide for uptake of Y{sup 3+} from aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Kameda, Tomohito, E-mail: kameda@env.che.tohoku.ac.jp [Graduate School of Environmental Studies, Tohoku University, 6-6-07 Aoba, Aramaki, Aoba-ku, Sendai 980-8579 (Japan); Hoshi, Kazuaki; Yoshioka, Toshiaki [Graduate School of Environmental Studies, Tohoku University, 6-6-07 Aoba, Aramaki, Aoba-ku, Sendai 980-8579 (Japan)

    2012-12-15

    Graphical abstract: Display Omitted Highlights: ► Decomposition of CO{sub 3}·Cu–Al LDH occurred in four stages. ► The edta·Cu–Al LDH was found to take up Y{sup 3+} in aqueous solution. ► The edta·Cu–Al LDH could selectively take up rare earth ions from a mixed solution. -- Abstract: CO{sub 3}{sup 2−}-intercalated Cu–Al layered double hydroxide (CO{sub 3}·Cu–Al LDH) was calcined to yield Cu–Al oxide, and then ethylenediaminetetraacetate-intercalated Cu–Al LDH (edta·Cu–Al LDH) was prepared by reconstructing Cu–Al oxide in edta solution. Decomposition of CO{sub 3}·Cu–Al LDH occurred in four stages. The production of Cu–Al oxide was caused by the thermal decomposition of CO{sub 3}·Cu–Al LDH until the third stage. The first stage was the elimination of adsorbed surface water and interlayer water in CO{sub 3}·Cu–Al LDH. The second and third stages were the dehydroxylation of the brucite-like octahedral layers and the elimination of CO{sub 3}{sup 2−} intercalated in the interlayers. The edta·Cu–Al LDH was found to take up Y{sup 3+} in aqueous solution. The uptake of Y{sup 3+} was caused not only by the chelating function of Hedta{sup 3−} in the interlayer but also by the chemical behavior of Cu–Al LDH itself. The edta·Cu–Al LDH was found to selectively take up rare earth ions from a mixed solution. The degree of uptake was high, in the order Sc{sup 3+} > Y{sup 3+} > La{sup 3+} for all time durations, which was attributable to differences among the stabilities of Sc(edta){sup −}, Y(edta){sup −} and La(edta){sup −}.

  13. Influence of Hydrothermal Treatment on Physicochemical Properties and Drug Release of Anti-Inflammatory Drugs of Intercalated Layered Double Hydroxide Nanoparticles

    Directory of Open Access Journals (Sweden)

    Zi Gu

    2014-05-01

    Full Text Available The synthesis method of layered double hydroxides (LDHs determines nanoparticles’ performance in biomedical applications. In this study, hydrothermal treatment as an important synthesis technique has been examined for its influence on the physicochemical properties and the drug release rate from drug-containing LDHs. We synthesised MgAl–LDHs intercalated with non-steroidal anti-inflammatory drugs (i.e., naproxen, diclofenac and ibuprofen using a co-precipitation method with or without hydrothermal treatment (150 °C, 4 h. After being hydrothermally treated, LDH–drug crystallites increased in particle size and crystallinity, but did not change in the interlayer anion orientation, gallery height and chemical composition. The drug release patterns of all studied LDH–drug hybrids were biphasic and sustained. LDHs loaded with diclofenac had a quicker drug release rate compared with those with naproxen and ibuprofen, and the drug release from the hydrothermally-treated LDH–drug was slower than the freshly precipitated LDH–drug. These results suggest that the drug release of LDH–drugs is influenced by the crystallite size of LDHs, which can be controlled by hydrothermal treatment, as well as by the drug molecular physicochemical properties.

  14. Ethylene Glycol Intercalated Cobalt/Nickel Layered Double Hydroxide Nanosheet Assemblies with Ultrahigh Specific Capacitance: Structural Design and Green Synthesis for Advanced Electrochemical Storage.

    Science.gov (United States)

    Wang, Changhui; Zhang, Xiong; Xu, Zhongtang; Sun, Xianzhong; Ma, Yanwei

    2015-09-09

    Because of the rapid depletion of fossil fuels and severe environmental pollution, more advanced energy-storage systems need to possess dramatically improved performance and be produced on a large scale with high efficiency while maintaining low-enough costs to ensure the higher and wider requirements. A facile, energy-saving process was successfully adopted for the synthesis of ethylene glycol intercalated cobalt/nickel layered double hydroxide (EG-Co/Ni LDH) nanosheet assembly variants with higher interlayer distance and tunable transitional-metal composition. At an optimized starting Co/Ni ratio of 1, the nanosheet assemblies display a three-dimensional, spongelike network, affording a high specific surface area with advantageous mesopore structure in 2-5 nm containing large numbers of about 1.2 nm micropores for promoting electrochemical reaction. An unprecedented electrochemical performance was achieved, with a specific capacitance of 4160 F g(-1) at a discharge current density of 1 A g(-1) and of 1313 F g(-1) even at 50 A g(-1), as well as excellent cycling ability. The design and optimization of EG-Co/Ni LDH nanosheets in compositions, structures, and performances, in conjunction with the easy and relatively "green" synthetic process, will play a pivotal role in meeting the needs of large-scale manufacture and widespread application for advanced electrochemical storage.

  15. The Application of Response Surface Methodology for Lead Ion Removal from Aqueous Solution Using Intercalated Tartrate-Mg-Al Layered Double Hydroxides

    Directory of Open Access Journals (Sweden)

    Yamin Yasin

    2013-01-01

    Full Text Available Layered double hydroxide intercalated with tartrate (tartrate-Mg-Al was used as an adsorbent to remove lead ions from aqueous solutions. The effects of various optimization parameters such as contact time, solution pH, lead ion concentrations, and adsorbent dosage were investigated by the use of Response Surface Methodology (RSM. The Response Surface Methodology (RSM based on a four-level four-variable Central Composite Rotatable Design (CCRD was employed to evaluate the interactive effects of the various optimization parameters. The parameters were contact time (6–10 h, solution pH (1–3, adsorbent dosage (0.06–0.1 g, and lead ion concentrations (10–30 mg/L. The percentage of lead ions removal for each of the parameters studied was determined by Inductively Coupled Plasma-Optical Emission Spectrophotometer. Simultaneously by increasing contact time and amount of dosage of tartrate-Mg-Al used the percentage of lead ions removal from aqueous solution will increase; however, the percentage removal decreases with an increase in pH and concentrations of lead ions. The experimental percentage removal recorded under optimum conditions was compared well with the maximum predicted value from the RSM, which suggest that Central Composite Rotatable Design of RSM can be used to study the removal of lead from aqueous solution by the use of tartrate-Mg-Al as an adsorbent.

  16. Optical and Thermal Properties of Zn/Al-Layered Double Hydroxide Nanocomposite Intercalated with Sodium Dodecyl Sulfate

    Directory of Open Access Journals (Sweden)

    Samaneh Babakhani

    2014-01-01

    Full Text Available Zn/Al-LDH-SDS nanocomposites have been prepared using a coprecipitation method in different molar ratio of Zn2+/Al3+ = 2, 3, and 4 at pH = 10 and different concentrations of sodium dodecyl sulfate solution (0.2 M, 0.4 M, and 0.8 M. The XRD and FTIR data show the successful intercalation of SDS into the LDH interlayer. The XRD diffractogram showed that the basal spacing for Zn/Al–NO3- is 0.89 nm compared to 2.54–2.61 nm for the Zn/Al-SDS nanocomposite. Optical band gap of the samples was calculated using Kubelka-Munk model. Due to the presence of LDH phase, two band gap energies (Eg1 and Eg2 were observed. The values of Eg1 and Eg2 were found around 4.8 eV and 3.75 eV for Zn/Al-LDH (r = 2, 3, and 4. The values of band gap of LDH-SDS nanocomposites were found to increase to around 4.2 eV and 5.2 eV. For Zn4Al-LDH-SDS with 0.4 M and 0.8 M of SDS, only one energy gap at around 3.23 eV was observed. The optical band gap of SO42- phase increased as the amount of SDS increases. Thermal diffusivity of the resulted nanocomposite was also investigated.

  17. High pressure measurement of the uniaxial stress of host layers on intercalants and staging transformation of intercalation compounds

    CERN Document Server

    Park, T R; Kim, H; Min, P

    2002-01-01

    A layered double-hydroxide intercalation compound was synthesized to measure the uniaxial stress the host layers exert on the intercalants. To measure the uniaxial stress, we employed the photoluminescence (PL) from the intercalated species, the Sm ion complex, as it is sensitive to the deformation of the intercalants. Of the many PL peaks the Sm ion complex produces, the one that is independent of the counter-cation environment was chosen for the measurement since the Sm ion complexes are placed under a different electrostatic environment after intercalation. The peak position of the PL was redshifted linearly with increasing hydrostatic pressure on the intercalated sample. Using this pressure-induced redshifting rate and the PL difference at ambient pressure between the pre-intercalation and the intercalated ions, we found that, in the absence of external pressure, the uniaxial stress exerted on the samarium ion complexes by the host layers was about 13.9 GPa at room temperature. Time-resolved PL data also ...

  18. Highly Selective and Efficient Removal of Heavy Metals by Layered Double Hydroxide Intercalated with the MoS4(2-) Ion.

    Science.gov (United States)

    Ma, Lijiao; Wang, Qing; Islam, Saiful M; Liu, Yingchun; Ma, Shulan; Kanatzidis, Mercouri G

    2016-03-01

    The MoS4(2-) ion was intercalated into magnesium-aluminum layered double hydroxide (MgAl-NO3-LDH) to produce a single phase material of Mg0.66Al0.34(OH)2(MoS4)0.17·nH2O (MgAl-MoS4-LDH), which demonstrates highly selective binding and extremely efficient removal of heavy metal ions such as Cu(2+), Pb(2+), Ag(+), and Hg(2+). The MoS4-LDH displays a selectivity order of Co(2+), Ni(2+), Zn(2+) metal ions. The enormous capacities for Hg(2+) (∼500 mg/g) and Ag(+) (450 mg/g) and very high distribution coefficients (Kd) of ∼10(7) mL/g place the MoS4-LDH at the top of materials known for such removal. Sorption isotherm for Ag(+) agrees with the Langmuir model suggesting a monolayer adsorption. It can rapidly lower the concentrations of Cu(2+), Pb(2+), Hg(2+), and Ag(+) from ppm levels to trace levels of ≤1 ppb. For the highly toxic Hg(2+) (at ∼30 ppm concentration), the adsorption is exceptionally rapid and highly selective, showing a 97.3% removal within 5 min, 99.7% removal within 30 min, and ∼100% removal within 1 h. The sorption kinetics for Cu(2+), Ag(+), Pb(2+), and Hg(2+) follows a pseudo-second-order model suggesting a chemisorption with the adsorption mechanism via M-S bonding. X-ray diffraction patterns of the samples after adsorption demonstrate the coordination and intercalation structures depending on the metal ions and their concentration. After the capture of heavy metals, the crystallites of the MoS4-LDH material retain the original hexagonal prismatic shape and are stable at pH ≈ 2-10. The MoS4-LDH material is thus promising for the remediation of heavy metal polluted water.

  19. Intercalation of PM-19 into and in vitro Release of Anti-tumor Drug from Layered Double Hydroxide

    Institute of Scientific and Technical Information of China (English)

    WANG Zhong-liang; WANG En-bo; TIAN Shang-yi; XIAO Dong-rong; GAO Lei; WANG Li; XU Lin

    2005-01-01

    @@ Introduction Recently, controlled release of drugs and gene delivery technology have received considerable attention due to their numerous advantages including prolonged duration of action of an active agent, improved efficacy, reduced toxicity and convenience compared to the conventional dosage forms[1]. In this field typical systems are polymer delivery systems depending on the hydrolysis-induced degradation, swelling and erosion of carriers′ structures[1, 2], mesoporous silica carrier systems relying on capturing and releasing the CdS nanoparticles[3], and layered materials release systems based on ion-exchange principle[4].

  20. Equilibrium and kinetics studies on the adsorption of substituted phenols by a Cu–Al layered double hydroxide intercalated with 1-naphthol-3,8-disulfonate

    Energy Technology Data Exchange (ETDEWEB)

    Kameda, Tomohito, E-mail: kameda@env.che.tohoku.ac.jp; Uchiyama, Tomomi; Yoshioka, Toshiaki

    2016-06-15

    Cu–Al layered double hydroxides (Cu–Al LDHs) intercalated with 1-naphthol-3,8-disulfonate (1-N-3,8-DS{sup 2−}) were confirmed to easily take up substituted phenols with electron-poor benzene rings from aqueous solution. The uptake of the substituted phenols by the 1-N-3,8-DS• Cu–Al LDH was better expressed by the Langmuir-type than the Dubinin−Radushkevich (DR) adsorption model. The negative values of ΔG for all substituted phenols indicate that the adsorption process is spontaneous regardless of the temperature. The |ΔH| values for all substituted phenols are less than 20 kJ mol{sup −1}, indicating that the phenol uptake by this LDH can be considered a physical adsorption process caused by π–π stacking interactions. Although the uptake of the substituted phenols by the 1-N-3,8-DS• Cu–Al LDH can be considered a physical adsorption process caused by π–π stacking interactions, it is closely related chemically to Langmuir-type adsorption. The uptake of various substituted phenols by 1-N-3,8-DS• Cu–Al LDH followed the pseudo-second-order kinetic model. By fitting the results of phenol uptake by 1-N-3,8-DS• Cu–Al LDH to the Eyring equation, it was found that positive values of ΔH{sup ‡} and ΔG{sup ‡} indicated the presence of an energy barrier in the adsorption process. Furthermore, the positive value of ΔH{sup ‡} confirmed that the process was endothermic. - Highlights: • The uptake of the substituted phenols was better expressed by the Langmuir-type. • The uptake can be considered a physical adsorption process caused by π–π stacking interactions. • The uptake followed the pseudo-second-order kinetic model.

  1. Intercalation of p-methycinnamic acid anion into Zn-Al layered double hydroxide to improve UV aging resistance of asphalt

    Directory of Open Access Journals (Sweden)

    Chao Peng

    2015-02-01

    Full Text Available A UV absorber, p-methycinnamic acid (PMCA, was intercalated into Zn-Al layered double hydroxide (LDH by calcination recovery. Fourier transform infrared spectroscopy showed that the PMCA anions completely replaced the CO32− anions in the interlayer galleries of Zn-Al-LDH containing PMCA anions (Zn-Al-PMCA-LDH. X-ray diffraction and transmission electron microscopy showed that the interlayer distance increased from 0.78 nm to 1.82 nm after the substitution of PMCA anions for CO32− anions. The similar diffraction angles of the CO32− anion-containing Zn-Al-LDH (Zn-Al-CO32−-LDH and the Zn-Al-CO32−-LDH/styrene–butadiene–styrene (SBS modified asphalt implied that the asphalt molecules do not enter into the LDH interlayer galleries to form separated-phase structures. The different diffraction angles of Zn-Al-PMCA-LDH and Zn-Al-PMCA-LDH/SBS modified asphalt indicated that the asphalt molecules penetrated into the LDH interlayer galleries to form an expanded-phase structure. UV-Vis absorbance analyses showed that Zn-Al-PMCA-LDH was better able to block UV light due to the synergistic effects of PMCA and Zn-Al-LDH. Conventional physical tests and atomic force microscopy images of the SBS modified asphalt, Zn-Al-CO32−-LDH/SBS modified asphalt and Zn-Al-PMCA-LDH/SBS modified asphalt before and after UV aging indicated that Zn-Al-PMCA-LDH improved the UV aging resistance of SBS modified asphalts.

  2. Advanced bifunctional electrocatalyst generated through cobalt phthalocyanine tetrasulfonate intercalated Ni2Fe-layered double hydroxides for a laminar flow unitized regenerative micro-cell

    Science.gov (United States)

    Zhong, Haihong; Tian, Ran; Gong, Xiaoman; Li, Dianqing; Tang, Pinggui; Alonso-Vante, Nicolas; Feng, Yongjun

    2017-09-01

    We fabricated a NiFeOx/CoNy-C nanocomposite derived from CoPcTs-intercalated Ni2Fe-layered double hydroxides (Ni2Fe-CoPcTs-LDH), which served as high-efficiency, low-cost, and long-durability bifunctional oxygen electrocatalyst in half-cell, and a H2-O2 laminar flow unitized regenerative micro-cell (LFURMC) in alkaline media. Based on the synergistic effect between Co-Ny and NiFeOx centers, the non-noble hybrid catalyst NiFeOx/CoNy-C achieves a ΔE (η@jOER,10 - η@jORR,-3) = 0.84 V in alkaline solution, outperforming the commercial Pt/C, and very close to that of IrOx/C. In the fuel cell mode, the performance of NiFeOx/CoNy-C with the maximum power density of 56 mW cm-2 is similar to that of Pt/C (63 mW cm-2) and IrOx/C (58 mW cm-2); in the electrolysis mode, the calculated maximum electrical power consumed on NiFeOx/CoNy-C (237 mW cm-2) is more than 3 times that on Pt/C (73 mW cm-2), similar with that of IrOx/C. More importantly, the NiFeOx/CoNy-C shows a remarkable stability in alternating modes in a LFURMC system.

  3. Oxidation of Dodecanoate Intercalated Iron(II)–Iron(III) Layered Double Hydroxide to Form 2D Iron(III) (Hydr)oxide Layers

    DEFF Research Database (Denmark)

    Huang, Li‐Zhi; Ayala‐Luis, Karina B.; Fang, Liping;

    2013-01-01

    A planar trioctahedral iron(II)–iron(III) hydroxide (green rust, GR) intercalated with dodecanoate (GRC12) has been oxidized by dioxygen to produce the corresponding planar iron(III) (hydr)oxide. The formulae of GRC12 and the final iron(III) product (oxGRC12) were determined to be FeII2.00FeIII1...

  4. REMOVAL OF LEAD ION FROM AQUEOUS SOLUTION USING GLUTAMATE INTERCALATED LAYERED DOUBLE HYDROXIDE%谷氨酸插层水滑石吸附水中铅离子

    Institute of Scientific and Technical Information of China (English)

    王蕾; 肖鹏

    2013-01-01

    Glutamate intercalated Mg-Al layered double hydroxide (LDH) was prepared by co-precipitation and characterized by XRD and FT-IR.It was shown that glutamate can intercalate into the interlayer space of Mg-Al LDH.The glutamate intercalated Mg-Al LDH as adsorbent can effectively remove Pb2+ from the aqueous solution with the maximum adsorption capacity of 68.49mg/g.The adsorption of Pb2+ on glutamate intercalated Mg-A1 LDH was fitted oseudo-second-order kinetics model and the isotherm can be well defined by Langmuir model.%采用共沉淀法合成了谷氨酸插层镁铝类水滑石(LDH),对所制备的试样进行了X-射线衍射和红外光谱表征,对LDH去除水中铅离子的能力进行了讨论,研究了吸附过程的吸附动力学和吸附等温线.结果表明,谷氨酸能嵌入镁铝水滑石的层间,该插层水滑石能有效吸附水中铅离子,吸附过程符合准二级动力学模型,吸附等温曲线可用Langmuir模型来描述,吸附量可达68.49mg/g.

  5. The Effect of Single, Binary and Ternary Anions of Chloride, Carbonate and Phosphate on the Release of 2,4-Dichlorophenoxyacetate Intercalated into the Zn–Al-layered Double Hydroxide Nanohybrid

    Directory of Open Access Journals (Sweden)

    Zainal Zulkarnain

    2009-01-01

    Full Text Available Abstract Intercalation of beneficial anion into inorganic host has lead to an opportunity to synthesize various combinations of new organic–inorganic nanohybrids with various potential applications; especially, for the controlled release formulation and storage purposes. Investigation on the release behavior of 2,4-dichlorophenoxyacetate (2,4-D intercalated into the interlayer of Zn–Al-layered double hydroxide (ZAN have been carried out using single, binary and ternary aqueous systems of chloride, carbonate and phosphate. The release behavior of the active agent 2,4-D from its double-layered hydroxide nanohybrid ZANDI was found to be of controlled manner governed by pseudo-second order kinetics. It was found that carbonate medium yielded the highest accumulated release of 2,4-D, while phosphate in combination with carbonate and/or nitrate speeds up the release rate of 2,4-D. These results indicate that it is possible to design and develop new delivery system of latex stimulant compound with controlled release property based on 2,4-D that is known as a substance to increase latex production of rubber tree,Hevea brasiliensis.

  6. Preparation of Mg-Al layered double hydroxides intercalated with 1,3,6-naphthalenetrisulfonate and 3-amino-2,7-naphthalenedisulfonate and assessment of their selective uptake of aromatic compounds from aqueous solutions

    Science.gov (United States)

    Kameda, Tomohito; Yamazaki, Takashi; Yoshioka, Toshiaki

    2010-05-01

    Mg-Al layered double hydroxides (Mg-Al LDHs) intercalated with 1,3,6-naphthalenetrisulfonate (NTS 3-) and 3-amino-2,7-naphthalenedisulfonate (ANDS 2-) ions were prepared by coprecipitation and were characterized by X-ray diffraction and chemical analyses. Based on X-ray diffraction patterns, the naphthalene rings of NTS 3- and ANDS 2- were most likely oriented parallel to the brucite-like host layers of the Mg-Al LDH, midway between layers. The prepared Mg-Al LDHs were able to selectively take up aromatics from aqueous solutions, and the order of percentage uptake was as follows: 1,3-dinitrobenzene > nitrobenzene > benzaldehyde > N,N-dimethylaniline > anisole > 1,2-dimethoxybenzene. The differences in the extent of π-π stacking interactions occurring between the benzene rings of the aromatics and the naphthalene ring of the intercalated NTS 3- and ANDS 2- probably resulted in these differences among the absorbed quantities of the various aromatics.

  7. The intercalation chemistry of layered iron chalcogenide superconductors

    Science.gov (United States)

    Vivanco, Hector K.; Rodriguez, Efrain E.

    2016-10-01

    The iron chalcogenides FeSe and FeS are superconductors composed of two-dimensional sheets held together by van der Waals interactions, which makes them prime candidates for the intercalation of various guest species. We review the intercalation chemistry of FeSe and FeS superconductors and discuss their synthesis, structure, and physical properties. Before we review the latest work in this area, we provide a brief background on the intercalation chemistry of other inorganic materials that exhibit enhanced superconducting properties upon intercalation, which include the transition metal dichalcogenides, fullerenes, and layered cobalt oxides. From past studies of these intercalated superconductors, we discuss the role of the intercalates in terms of charge doping, structural distortions, and Fermi surface reconstruction. We also briefly review the physical and chemical properties of the host materials-mackinawite-type FeS and β-FeSe. The three types of intercalates for the iron chalcogenides can be placed in three categories: 1.) alkali and alkaline earth cations intercalated through the liquid ammonia technique; 2.) cations intercalated with organic amines such as ethylenediamine; and 3.) layered hydroxides intercalated during hydrothermal conditions. A recurring theme in these studies is the role of the intercalated guest in electron doping the chalcogenide host and in enhancing the two-dimensionality of the electronic structure by spacing the FeSe layers apart. We end this review discussing possible new avenues in the intercalation chemistry of transition metal monochalcogenides, and the promise of these materials as a unique set of new inorganic two-dimensional systems.

  8. 5-Fluorouracil intercalated iron oxide@layered double hydroxide core-shell nano-composites with isotropic and anisotropic architectures for shape-selective drug delivery applications.

    Science.gov (United States)

    Tuncelli, Gülsevde; Ay, Ahmet Nedim; Zümreoglu-Karan, Birgül

    2015-10-01

    We report the synthesis, characterization and in vitro release behavior of anti-cancer drug carrying iron oxide@layered double hydroxide core-shell nanocomposites with sizes ranging from 40 to 300 nm, good drug loading capacities and soft ferromagnetic properties. HRTEM analyses verified that nearly spherical isotropic carriers were obtained by coating spherical magnetite particles while anisotropic carriers were obtained by coating spindle-shaped hematite particles. They both displayed a fluctuating in vitro release profile with a higher release percentage for the anisotropic carrier.

  9. Chronopotentiometric study of intercalation of layered III-VI semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Bakhmatyuk, B.P.; Grigorchak, I.I.; Kaminskii, V.M.; Kovalyuk, Z.D.; Yurtsenyuk, S.P.

    1985-04-01

    The known group of materials open to intercalation (i.e., the incorporation of foreign ions, atoms, or molecules into the space between layers of layered crystals) has recently been enlarged by the layered semiconducting monochalcogenides of indium and gallium. This article is concerned with an electrochemical investigation of their intercalation process. The chronopotentiograms for the reduction and oxidation of electrodes made of the layered monoselenides of indium and gallium in 1 M lithium perchlorate solution in propylene carbonate were examined. The electrodes studied were examined by x-rays before and after intercalation. It is indicated that the intercalation of InSe and GaSe with lithium yields nonstoichiometric phases in the range of 0 is less than x is less than or equal to 1. Using the equilibrium potentials of the intercalated phases and known relations, the free energies of these compounds and of their formation can be determined. The electrochemical intercalation leads to the formation of ternary compounds Li /SUB x/ InSe and Li /SUB x/ GaSe. The free energies of formation of these compounds increase with increasing degree of reduction of the compounds. The intercalation of indium and gallium monoselenide with lithium can be regarded as reversible.

  10. n-Pentylamine-intercalated layered perovskite-type oxide

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A novel n-pentylamine-intercalated layered perovskite-type oxide,C5H11NH3-Sr2Nb3O10, was prepared and characterized by using XRD, FT-IR, Raman spectrascopy, and elemental analysis. It was shown that the intercalated n-pentylamine adopted a bilayer formation with some overlap and tilt, and the lattice of the perovskite layer was distorted due to the intercalation of n-pentylamine. The as-prepared sample gave clear electric hysteresis loop and did not show fatigue after 1011 switching circles, and therefore, could be considered as a new kind of fatigue-free ferroelectric materials.

  11. Intercalation of cellulase enzyme into a hydrotalcite layer structure

    Science.gov (United States)

    Zou, N.; Plank, J.

    2015-01-01

    A new inorganic-organic hybrid material whereby cellulase enzyme is incorporated into a hydrotalcite type layered double hydroxide (LDH) structure is reported. The Mg2Al-cellulase-LDH was synthesized via co-precipitation from Mg/Al nitrate at pH=9.6. Characterization was performed using X-ray powder diffraction (XRD), small angle X-ray scattering (SAXS), elemental analysis, infrared spectroscopy (IR) and thermogravimetry (TG). From XRD and SAXS measurements, a d-value of ~5.0 nm was identified for the basal spacing of the Mg2Al-cellulase-LDH. Consequently, the cellulase enzyme (hydrodynamic diameter ~6.6 nm) attains a slightly compressed conformation when intercalated. Formation of the LDH hybrid was also confirmed via scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Mg2Al-cellulase-LDH phases appear as ~20 nm thin foils which are intergrown to flower-like aggregates. Activity of the enzyme was retained after deintercalation from the Mg2Al-LDH framework using anion exchange. Accordingly, cellulase is not denatured during the intercalation process, and LDH presents a suitable host structure for time-controlled release of the biomolecule.

  12. A new route to prepare nanocomposites based on polyvinyl chloride and MgAl layered double hydroxide intercalated with laurylether phosphate

    Directory of Open Access Journals (Sweden)

    2009-09-01

    Full Text Available The MgAl layered double hydroxide (LDH with laurylether phosphate was prepared using reconstruction method. Delamilation of the LDH with laurylether phosphate (LDH-PK in tetrahydrofuran was characterized by AFM (atomic force microscopy, indicating that a large part of the LDH was delaminated into single, double and multi layers. The delaminated LDH-PK suspension was then used with polyvinyl chloride (PVC to prepare a series of high-LDH-loading nanocomposites. Both the XRD (X-ray diffraction patterns and TEM (transmission electron microscopy photographs of the as-prepared PVC/LDH nanocomposites indicated that the LDH nanolayers dispersed uniformly in the PVC matrix. With differential scanning calorimetry (DSC the glass transition temperatures of PVC phases in the PVC/LDH nanocomposites were measured and a slightly lower value than that of pristine PVC has been observed. Thermogravimetric analysis results show that the presence of LDH enhanced the dehydrochlorination temperature (Tmax1, reduced the maximum degradation rate (Rmax1 and the 5% weight loss temperature, and promoted the char formation of PVC. However, the thermal degradation temperature (Tmax2 and thermal degradation rate (Rmax2 of the dehydrochlorinated PVC were slightly affected by the presence of LDH. The apparent activation energies were calculated by the method of Flynn-Wall-Ozawa in nitrogen at four different heating rates, showing that the nanofiller increased the apparent activation energies by 10–26 kJ/mol when compared with pristine PVC, probably implying that the LDH nanolayers improve the stability of chlorine atom on the PVC chains.

  13. 超分子结构二氟尼柳插层镁铝水滑石的合成与表征%Synthesis and Characterization of Magnesium Aluminum Layered Double Hydroxides Intercalated with Diflunisal

    Institute of Scientific and Technical Information of China (English)

    李丹; 倪哲明; 王力耕

    2006-01-01

    采用离子交换和共沉淀两种不同方法将二氟尼柳插入镁铝水滑石层间,得到一种新型的有机-无机层状复合材料.通过X射线粉末衍射、红外光谱、元素分析和热重-差热等手段对材料进行了表征.结果表明,离子交换法和共沉淀法成功地将二氟尼柳插入水滑石,得到的材料层状结构完整、晶相单一,且层间距均大于二氟尼柳分子尺寸,扩大为1.81~2.14 nm;二氟尼柳插入后,复合水滑石材料的热稳定性大幅度提高.客体二氟尼柳与主体层板之间存在超分子作用力,二氟尼柳分子的羧基与水滑石层板之间相互作用,以双层倾斜交替地排列于层板之间.此外,根据其超分子作用力建立了二氟尼柳插层镁铝水滑石的超分子结构模型.%A new organic-inorganic hybrid material was obtained by the intercalation of the drug diflunisal into magnesium aluminum layered double hydroxides (LDHs). The intercalation was performed by ion exchange and co-precipitation method, respectively. The complex materials were characterized using powder X-ray diffractometry (XRD), Fourier-transform infrared (FTIR), ICP and TG-DTA. The results show that the interlayer spaces of the materials are expanded to 1.81~2.14 nm and the thermal stability of material increases after the intercalation of diflunisal. A supramolecular structure model for Diflunisal-LDHs is suggested, i.e. diflunisal molecules form a titled alternate bilayer with carboxylate groups pointing towards the LDHs layers.

  14. Synthesis of Li-Al layered double hydroxide intercalated with amino tris(methylene phosphonic acid) and kinetic and equilibrium studies of the uptake of Nd3+ and Sr2+ ions

    Science.gov (United States)

    Kameda, Tomohito; Shinmyou, Tetsu; Yoshioka, Toshiaki

    2016-03-01

    A Li-Al layered double hydroxide intercalated with amino tris(methylene phosphonic acid) (AMP·Li-Al LDH) was synthesized by the drop-wise addition of an Al-containing solution to a Li-AMP solution at a constant pH of 8.0. The AMP·Li-Al LDH was found to take up Nd3+ and Sr2+ ions from aqueous solutions; this phenomenon was attributable to the metal-chelating functionality of the AMP ions in the interlayers of the AMP·Li-Al LDH. Further, the AMP·Li-Al LDH was found to take up Nd3+ ions preferentially than Sr2+ ions. This was attributable to the stability of the Nd-AMP complex being higher than that of the Sr-AMP complex. The mass-transfer-controlled shrinking-core model could describe the uptake behavior better than the surface-reaction-control model. The AMP ions in the AMP·Li-Al LDH interlayers rapidly formed chelate complexes with the Nd3+ or Sr2+ ions. As a result, the transfer of Nd3+ and Sr2+ ions through the product layer was the rate-limiting step. Furthermore, this reaction could be explained by a Langmuir-type adsorption mechanism, indicating that it involved chemical adsorption; this was consistent with the formation of chelate complexes between Nd3+ and Sr2+ ions and the AMP ions in the interlayers of the AMP·Li-Al LDH.

  15. 甲氨蝶呤柱撑水滑石超分子结构层柱材料的插层组装%Intercalation and assembly of supramolecular materials of methotrexate pillared layered double hydroxides

    Institute of Scientific and Technical Information of China (English)

    刘翠娟; 慎爱民; 杨治伟; 王旭; 沙靖全; 吕玉光

    2011-01-01

    用共沉淀和离子交换法将抗肿瘤类药物甲氨蝶呤(MTX)插层组装到水滑石层间,制备了一种新型的结晶度高、晶相单一且MTX在层间有序排列的超分子结构的药物-无机复合层柱材料.用XRD、原子光谱、元素分析、FT/IR、SEM及TG-DSC分析表征了超分子结构层柱材料的结构,并给出其结构模型.%A new drug-inorganic composite involving an antitumor compound methotrexate intercalated layered double hydroxides was assembled with coprecipitation and ion-exchange methods, from which high crystallized supramolecular materials were obtained and methotrexate were ordered between layers without impurities. The structures of supramolecular materials were characterized by powder X-ray diffraction, atom absorbed spectra, FT-IR spectra,scanning electron microscope and TG-DSC and the structure models were Suggested.

  16. Intercalation and Stability of Layered Semiconductive Material in Corrosive Environment

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The intercalation of 4-methyl pyridine (4-picoline) into layered semiconductive material (MnPS3) and the stability of the resulting materials in corrosive environments (water, HCI and open atmosphere) were investigated.Powder X-ray diffraction (XRD) indicated that the presence of water and hydrochloric acid greatly influenced the existing form of intercalation and its orientation in the interlayer of the host. Atmospheric environment (open air) affected the guest orientation in the interlayer of the host material. Phase transformation occurred and the material was stable. The intercalated compounds could be indexed in the trigonal unit cell. The XRD patterns exhibited sharp hkl reflections of the intercalated compounds, which formed in water and HCI,confirming that the materials were well crystalline and stable in corrosive environments.

  17. Selection of Inorganic Layered Double Hydroxide Materials for Intercalation of a Cisplatin-Guanosine Adduct%无机层状复合氢氧化物中顺铂-DNA模型分子的选择性插入

    Institute of Scientific and Technical Information of China (English)

    杨贞; 郭子建

    2003-01-01

    Selective encapsulation and controlled release of drug molecules are challenging projects for modern medicine.It is shown in this work that a cisplatin-DNA model adduct, cis-[Pt(NH3)2(5′-GMP)2] (5′-GMP, guanosine 5′-monophosphate), can be intercalated into a layered double hydroxide (LDH) [Zn0. 68Al0. 32(OH)2] (NO3)0.32 @mH2O. However, the same adduct cannot be inserted into a Li/Al LDH under the same reaction condition, whichmay be due to the higher charge density between hydroxide layers of the latter makes the ion-exchange reactionunfavorable. The spectroscopic data showed that the intercalated platinum adduct remains intact. This work mayprovide a novel route for the delivery of platinated DNA.%药物分子的选择性包裹和控制释放是药物研究领域中具有挑战性的研究方向.本文研究表明:顺铂-DNA模型分子cis-[Pt(NH3)2(5′-GMP)2](5′-CMP 5′-单磷酸鸟苷)可插入无机层状复合氢氧化物[Zn0 68Al0.32(OH)2](NO3)0.32@mH2O.但另一种层状复合氢氧化物[LiAl2(OH)6]Cl@H2O由于其阳离子层中正电荷密度较高、阳离子层与层间阴离子之间静电作用较强,因而顺铂-DNA模型分子不能通过离子交换方式插入其层间.光谱数据证实插入层间的顺铂-DNA模型分子结构不变.这可能为铂-DNA分子的传递提供新的方法.

  18. Hydroxy double salts loaded with bioactive ions: Synthesis, intercalation mechanisms, and functional performance

    Energy Technology Data Exchange (ETDEWEB)

    Kaassis, Abdessamad Y.A. [UCL School of Pharmacy, University College London, 29-39 Brunswick Square, London WC1N 1AX (United Kingdom); Xu, Si-Min; Guan, Shanyue; Evans, David G. [State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Wei, Min, E-mail: weimin@mail.buct.edu.cn [State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Williams, Gareth R., E-mail: g.williams@ucl.ac.uk [UCL School of Pharmacy, University College London, 29-39 Brunswick Square, London WC1N 1AX (United Kingdom)

    2016-06-15

    The intercalation of the anions of diclofenac (Dic), naproxen (Nap), and valproic acid (Val) into three hydroxy double salts (HDSs) has been explored in this work. Experiments were performed with [Co{sub 1.2}Zn{sub 3.8}(OH){sub 8}](NO{sub 3}){sub 2}·2H{sub 2}O (CoZn-NO{sub 3}), [Ni{sub 2}Zn{sub 3}(OH){sub 8}](NO{sub 3}){sub 2}·2H{sub 2}O (NiZn-NO{sub 3}) and [Zn{sub 5}(OH){sub 8}](NO{sub 3}){sub 2}·2H{sub 2}O (Zn-NO{sub 3}). It proved possible to intercalate diclofenac and naproxen into all three HDSs. In contrast, Val could be intercalated into CoZn-NO{sub 3} but when it was reacted with Zn-NO{sub 3} the HDS structure was destroyed, and the product comprised ZnO. Successful intercalation was verified by X-ray diffraction, IR spectroscopy, and elemental microanalysis. Molecular dynamics simulations showed the Dic and Nap ions to arrange themselves in an “X” shape in the interlayer space, forming a bilayer. Val was found to adopt a position with its aliphatic groups parallel to the HDS layer, again in a bilayer. In situ time resolved X-ray diffraction experiments revealed that intercalation of Dic and Nap into CoZn-NO{sub 3} and Zn-NO{sub 3} is mechanistically complex, with a number of intermediate phases observed. In contrast, the intercalation of all three guests into NiZn-NO{sub 3} and of Val into CoZn-NO{sub 3} are simple one step reactions proceeding directly from the starting material to the product. The HDS-drug composites were found to have sustained release profiles. - Graphical abstract: Seven new drug intercalates of hydroxy double salts (HDSs) have been prepared and characterised. The intercalation mechanisms have been explored, and the drug release properties of the HDS/drug composites quantified. Display Omitted.

  19. Layered Double Hydroxide as Cordycepin Delivery Nanocarrier

    Institute of Scientific and Technical Information of China (English)

    Qin Zheng YANG; Jing YANG; Chang Kai ZHANG

    2006-01-01

    Layered double hydroxide was investigated as cordycepin delivery nanocarrier for the first time in this study. Negatively charged biomolecule-cordycepin was intercalated in the gallery spaces of [Mg-Al-NO3], which was confirmed by the results of X-ray diffraction and electrophoretic mobility. Cell experiment suggested that the new bio-LDH nanohybrid could prevent cordycepin decomposition by adenosine deaminase. This new formulation could possibly be used as a novel form cordycepin intravenous injection.

  20. Hydroxy double salts loaded with bioactive ions: Synthesis, intercalation mechanisms, and functional performance

    Science.gov (United States)

    Y. A. Kaassis, Abdessamad; Xu, Si-Min; Guan, Shanyue; Evans, David G.; Wei, Min; Williams, Gareth R.

    2016-06-01

    The intercalation of the anions of diclofenac (Dic), naproxen (Nap), and valproic acid (Val) into three hydroxy double salts (HDSs) has been explored in this work. Experiments were performed with [Co1.2Zn3.8(OH)8](NO3)2·2H2O (CoZn-NO3), [Ni2Zn3(OH)8](NO3)2·2H2O (NiZn-NO3) and [Zn5(OH)8](NO3)2·2H2O (Zn-NO3). It proved possible to intercalate diclofenac and naproxen into all three HDSs. In contrast, Val could be intercalated into CoZn-NO3 but when it was reacted with Zn-NO3 the HDS structure was destroyed, and the product comprised ZnO. Successful intercalation was verified by X-ray diffraction, IR spectroscopy, and elemental microanalysis. Molecular dynamics simulations showed the Dic and Nap ions to arrange themselves in an "X" shape in the interlayer space, forming a bilayer. Val was found to adopt a position with its aliphatic groups parallel to the HDS layer, again in a bilayer. In situ time resolved X-ray diffraction experiments revealed that intercalation of Dic and Nap into CoZn-NO3 and Zn-NO3 is mechanistically complex, with a number of intermediate phases observed. In contrast, the intercalation of all three guests into NiZn-NO3 and of Val into CoZn-NO3 are simple one step reactions proceeding directly from the starting material to the product. The HDS-drug composites were found to have sustained release profiles.

  1. Preparation and Inhibition Performance of Aspartic Acid Intercalated ZnAl Layered Double Hydroxides%天冬氨酸插层ZnAl双金属氢氧化物的制备及其对铜的缓蚀性能研究

    Institute of Scientific and Technical Information of China (English)

    全贞兰; 张冬梅; 侯万国

    2011-01-01

    Aspartic acids (Asp) were intercalated into ZnAl layered double hydroxides(ZnAlLDHs) by ion exchange method. The products were characterized by powder X-ray diffration (PXRD) and fourier transform infrared spectroscopy (FTIR). The results showed that Asp-LDHs nanohybrids were formed by the intercalation of the aspartic acid into the ZnAl layered double hydroxides. The nanohybrids were deposited on copper by colloid deposition method, and the quality and protection performance of the resulted film against corrosion were evaluated by electrochemical impedance spectroscopy (EIS) and polarization curves. All the results demonstrated that aspartic acid intercalated Zn-Al LDHs could inhibit the corrosion of copper effectively.%以锌铝层状双金属氢氧化物(LDHs)为主体,夭冬氨酸(aspartic acid,Asp)为客体,采用离子交换法合成了Asp-LDHs杂化物.粉末X射线衍射(PXRD)和傅里叶变换红外光谱(FTIR)分析结果表明,天冬氨酸成功插入LDHs层间,形成杂化物.用胶体沉积技术将杂化物沉积在铜基底上,电化学阻抗谱(EIS)和极化曲线研究表明,Asp-LDHs杂化物薄膜对铜具有良好的缓蚀作用.

  2. Selective and low temperature transition metal intercalation in layered tellurides

    Science.gov (United States)

    Yajima, Takeshi; Koshiko, Masaki; Zhang, Yaoqing; Oguchi, Tamio; Yu, Wen; Kato, Daichi; Kobayashi, Yoji; Orikasa, Yuki; Yamamoto, Takafumi; Uchimoto, Yoshiharu; Green, Mark A.; Kageyama, Hiroshi

    2016-12-01

    Layered materials embrace rich intercalation reactions to accommodate high concentrations of foreign species within their structures, and find many applications spanning from energy storage, ion exchange to secondary batteries. Light alkali metals are generally most easily intercalated due to their light mass, high charge/volume ratio and in many cases strong reducing properties. An evolving area of materials chemistry, however, is to capture metals selectively, which is of technological and environmental significance but rather unexplored. Here we show that the layered telluride T2PTe2 (T=Ti, Zr) displays exclusive insertion of transition metals (for example, Cd, Zn) as opposed to alkali cations, with tetrahedral coordination preference to tellurium. Interestingly, the intercalation reactions proceed in solid state and at surprisingly low temperatures (for example, 80 °C for cadmium in Ti2PTe2). The current method of controlling selectivity provides opportunities in the search for new materials for various applications that used to be possible only in a liquid.

  3. 毒死蜱/环糊精在锌铝类水滑石中插层的制备和性能%Preparation and Characterization of Chlorpyrifos/Cyclodextrin Complex Intercalation into ZnAl-Layered Double Hydroxide

    Institute of Scientific and Technical Information of China (English)

    刘洁翔; 任纪辉; 赵乔; 石婷静; 刘志芳; 罗诏; 张晓光

    2016-01-01

    Chlorpyrifos (CPF) was firstly included in sulfonated hydroxyethyl-β-cyclodextrin (SBECD) and carboxymethyl-β-cyclodextrin (CMCD) in an ethanol or 1-methyl-2-pyrrolidinone (NMP) solvent. Inclusion complexes (CPF/SBECD and CPF/CMCD) were then intercalated into the gal eries of ZnAl-layered double hydroxides (ZAL) to synthesize ZAL-SBECD-CPF and ZAL-CMCD-CPF intercalated materials. The structure and thermal stability of nanohybrids were characterized by powder X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, and thermal gravimetric and differential thermal analysis (TG-DTA). The results showed that both CPF/SBECD and CPF/SBECD were successful y intercalated in the interlayer. The samples prepared in the NMP solvent had a stronger diffraction peak intensity than those prepared with ethanol. The intercalated CPF molecules had a high thermal stability. Furthermore, the release behaviors of CPF from ZAL-SBECD-CPF and ZAL-CMCD-CPF nanohybrids were investigated and analyzed at pH 5.0 and 6.8. ZAL-SBECD-CPF had almost no slow-release behavior, while ZAL-CMCD-CPF showed distinct slow-release, which was caused by the different arrangements of cyclodextrin (CD) in the interlayer. BC release from nanohybrids was faster and the amount released higher at pH 6.8 than at pH 5.0. This was closely correlated with the structural type of CD and the release media. The CPF release kinetic process can be fitted wel by pseudo-second-order and parabolic diffusion models. ZAL-CMCD-CPF remarkably exhibited control ed release behavior, suggesting that it can be potential y applied as a control ed release pesticide formulation.%以层状锌铝类水滑石(ZAL)为主体,分别以磺丁基醚-β-环糊精(SBECD)和羧甲基-β-环糊精(CMCD)包结毒死蜱(CPF)为客体分子,分别在乙醇和N-甲基吡咯烷酮(NMP)溶剂条件下制备ZAL-SBECD-CPF和ZAL-CMCD-CPF插层材料,采用X射线粉末衍射(XRD)、傅里叶变换红外(FT-IR)光谱和热重-差热

  4. Layered intercalated functional materials based on efficient utilization of magnesium resources in China

    Institute of Scientific and Technical Information of China (English)

    David; G; EVANS

    2010-01-01

    Mg-based layered intercalated functional materials of the layered double hydroxide type are a significant class of magnesium compounds.Based on long-term studies of these materials in the State Key Laboratory of Chemical Resource Engineering in Beijing University of Chemical Technology,two principles of "using the intended application of a material as a guide to its structure design and synthesis process" and "the design of controlled intercalation processes in the light of future production processing requirements" have been developed.To achieve these objectives,the composition of the host layers and guest interlayer anions was tailored at the microlevel,while the mesostructure and macrostructure were controlled to fabricate different kinds of Mg-based layered intercalated functional materials.These materials have diverse applications in key areas such as catalysis,the environment,and construction,and as polymer additives.Therefore,China’s magnesium resources may be utilized more efficiently for the benefit of society.

  5. Adsorption performance of citrate intercalated MgAl layered double hydroxides on Zn2+ in aqueous solution%柠檬酸插层MgAl水滑石对水溶液中Zn2+的吸附性能

    Institute of Scientific and Technical Information of China (English)

    申延明; 张僖; 赵晓蕾; 刘东斌; 樊丽辉; 李士凤

    2015-01-01

    采用离子交换法制得柠檬酸插层MgAl水滑石吸附剂,对吸附剂进行XRD、IR、SEM和BET表征,考察制备的吸附剂对溶液中 Zn2+的吸附能力,探讨吸附剂投加量、Zn2+溶液浓度、pH 以及吸附温度对 Zn2+吸附率的影响,并进行动力学和热力学特征的研究.结果表明:吸附条件对Zn2+的吸附能力影响较大,适宜的水滑石投加量为2~3 g/L,pH以弱酸性为宜,对于Zn2+浓度不超过80 mg/L的溶液,室温下Zn2+吸附率在60%以上,而高温有利于提高Zn2+吸附率.吸附过程符合二级动力学模型,吸附等温曲线可用R-P模型来描述.吸附过程能够自发进行,为吸热过程.%The citrate intercalated MgAl layered double hydroxides adsorbent was prepared by anion-exchange method. The absorbents prepared were characterized by XRD, IR, SEM, BET and used to adsorb Zn2+ from aqueous solutions. The effects of adsorbent dosage, initial Zn2+ concentration, pH, adsorption temperature on the Zn2+ adsorption rate were investigated. The thermodynamics and kinetics characters were discussed. The results show that the adsorption capacity for Zn2+ is affected by adsorption conditions. The suitable adsorbent dosage is 2-3 g/ L, and pH is weak acidity. Under the above conditions, Zn2+ adsorption efficiency is over 60% at the Zn2+ concentration less than 80 mg/ L, and high temperature is benefit to improve Zn2+ adsorption rate. Adsorption process conforms to the secondary kinetics model, and the isothermal adsorption curve can be described by R-P model. The adsorption process is spontaneous and endothermic.

  6. Fabrication of a novel NiFe2O4/Zn-Al layered double hydroxide intercalated with EDTA composite and its adsorption behavior for Cr(VI) from aqueous solution

    Science.gov (United States)

    Deng, Lin; Shi, Zhou; Wang, Li; Zhou, Shiqing

    2017-05-01

    A novel magnetic NiFe2O4/Zn-Al layered double hydroxide intercalated with EDTA composite (NiFe2O4/ZnAl-EDTA LDH) was prepared through modified coprecipitation method and employed for adsorptive removal of Cr(VI) from aqueous solution. The adsorbents were characterized using Brunauer-Emmett-Teller (BET), scanning electron microscopy (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), vibrating sample magnetometer (VSM), and X-ray photoelectron spectroscopy (XPS). Factors affecting the Cr(VI) adsorption, such as initial solution pH, adsorbent dosage, contact time, initial Cr(VI) concentration, temperature and coexisting ions, were studied systematically. Experiments results show that the magnetic NiFe2O4/ZnAl-EDTA LDH exhibits high adsorption efficiency within a wide pH range of 3.0-7.0 (R>80% at Cr(VI) concentration 50 mg L-1, contact time 360 min, and adsorbent dosage 2 g/L) and quick separation property. The adsorption process is fitted well with the Langmuir isotherm and pseudo-second-order kinetic model. The maximum theoretical adsorption capacity is found to be 77.22 mg g-1 at pH 6.0 and 318 K. The positive ΔH value (2.907 kJ mol-1) and negative ΔG value (-4.722 kJ mol-1) at 298-318 K reveals that the adsorption process is feasible, spontaneous and endothermic. Coexisting anions (PO43-, SO42-, CO32-, HCO3-, Cl-, and NO3-) have no significant effect on Cr(VI) removal. The mechanism study indicates that the adsorption of Cr(VI) onto NiFe2O4/ZnAl-EDTA LDH mainly involves electrostatic attraction and ion exchange interaction. It is interesting to note that a proportion of Cr(VI) adsorbed on the adsorbent surface are reduced to Cr(III) during the adsorption process. Results from this study demonstrate the potential utility of the magnetic NiFe2O4/ZnAl-EDTA LDH that could be developed into a viable technology for efficient removal of Cr(VI) from aqueous solution.

  7. On the dielectric response of complex layered oxides: Mica-type silicates and layered double hydroxides

    Science.gov (United States)

    Mehrotra, Vivek; Giannelis, Emmanuel P.

    1992-08-01

    The dielectric properties of mica-type silicates and layered double hydroxides have been studied in the pristine and various intercalated forms in the frequency range 101-107 Hz. A relaxation peak has been observed for the pristine silicate, whereas the pristine layered double hydroxide exhibits an anomalous low-frequency dispersion. The dielectric response is rationalized in terms of structural ordering and fluctuation of charge carriers as well as models invoking fractal time processes and fractal structure. The response is also related to the structure and mobility of the intercalated water molecules. In both pristine hosts, the predominant conduction mechanism is proton hopping between sites generated by a network of intercalated water molecules. Silicate intercalated with the insulating form of polyaniline exhibits an almost frequency-independent response. In the case of conducting polyaniline intercalated silicate, where polarons are the majority charge carriers, an anomalous low-frequency dispersion is observed and the response is typical of a metal-insulator composite. Finally, impedance measurements have been used to calculate the spatial disorder and/or surface irregularity of the host layers, expressed by the fractal dimension ds. The changes observed in ds upon intercalation of high-charge ions are correlated to the stacking disorder of the host layers.

  8. Hydrogen storage in Li-doped fullerene-intercalated hexagonal boron nitrogen layers

    Science.gov (United States)

    Cheng, Yi-Han; Zhang, Chuan-Yu; Ren, Juan; Tong, Kai-Yu

    2016-10-01

    New materials for hydrogen storage of Li-doped fullerene (C20, C28, C36, C50, C60, C70)-intercalated hexagonal boron nitrogen ( h-BN) frameworks were designed by using density functional theory (DFT) calculations. First-principles molecular dynamics (MD) simulations showed that the structures of the C n -BN ( n = 20, 28, 36, 50, 60, and 70) frameworks were stable at room temperature. The interlayer distance of the h-BN layers was expanded to 9.96-13.59 Å by the intercalated fullerenes. The hydrogen storage capacities of these three-dimensional (3D) frameworks were studied using grand canonical Monte Carlo (GCMC) simulations. The GCMC results revealed that at 77 K and 100 bar (10 MPa), the C50-BN framework exhibited the highest gravimetric hydrogen uptake of 6.86 wt% and volumetric hydrogen uptake of 58.01 g/L. Thus, the hydrogen uptake of the Li-doped C n -intercalated h-BN frameworks was nearly double that of the non-doped framework at room temperature. Furthermore, the isosteric heats of adsorption were in the range of 10-21 kJ/mol, values that are suitable for adsorbing/desorbing the hydrogen molecules at room temperature. At 193 K (-80 °C) and 100 bar for the Li-doped C50-BN framework, the gravimetric and volumetric uptakes of H2 reached 3.72 wt% and 30.08 g/L, respectively.

  9. Mixing Acid Salts and Layered Double Hydroxides in Nanoscale under Solid Condition

    OpenAIRE

    2014-01-01

    The immobilization of potassium sorbate, potassium aspartate and sorbic acid in layered double hydroxide under solid condition was examined. By simply mixing two solids, immobilization of sorbate and aspartate in the interlayer space of nitrate-type layered double hydroxide, so called intercalation reaction, was achieved, and the uptakes, that is, the amount of immobilized salts and the interlayer distances of intercalation compounds were almost the same as those obtained in aqueous solution...

  10. Polymerization reaction in restricted space of layered double hydroxides (LDHs)

    Institute of Scientific and Technical Information of China (English)

    SI Lichun; WANG Ge; CAI Fuli; WANG Zhiqiang; DUAN Xue

    2004-01-01

    This paper reported the preparation of styrene sulfonate intercalated layered double hydroxides (LDHs) material, SS-LDHs by coprecipitation method, followed by in-situ polymerization of the monomers in the interlayer space of LDHs. The polymerization reaction was monitored by UV and NMR. It is confirmed that when the reaction occurred at 100℃ for 24 h, part of monomers did not react .When the reaction was carried out at 150℃, the polymeriza tion of the intercalated monomers is complete to afford the polymer intercalated product PSS-LDHs. During the polymerization process, the layered structure remains well. At thesame time the gallery height increases with the lengthening of reaction time. This is preliminarily because that the PSS becomes more swelling with the amount of water it absorbs due to its hygroscopicity property.

  11. Mixing Acid Salts and Layered Double Hydroxides in Nanoscale under Solid Condition

    Directory of Open Access Journals (Sweden)

    Hirokazu Nakayama

    2014-07-01

    Full Text Available The immobilization of potassium sorbate, potassium aspartate and sorbic acid in layered double hydroxide under solid condition was examined. By simply mixing two solids, immobilization of sorbate and aspartate in the interlayer space of nitrate-type layered double hydroxide, so called intercalation reaction, was achieved, and the uptakes, that is, the amount of immobilized salts and the interlayer distances of intercalation compounds were almost the same as those obtained in aqueous solution. However, no intercalation was achieved for sorbic acid. Although intercalation of sorbate and aspartate into chloride-type layered double hydroxide was possible, the uptakes for these intercalation compounds were lower than those obtained using nitrate-type layered double hydroxide. The intercalation under solid condition could be achieved to the same extent as for ion-exchange reaction in aqueous solution, and the reactivity was similar to that observed in aqueous solution. This method will enable the encapsulation of acidic drug in layered double hydroxide as nano level simply by mixing both solids.

  12. Room Temperature Ferromagnetism in InTe Layered Semiconductor Crystals Intercalated by Cobalt

    Directory of Open Access Journals (Sweden)

    V.B. Boledzyuk

    2015-03-01

    Full Text Available The magnetic properties of CoxInTe layered crystals electrochemically intercalated with cobalt in constant gradient magnetic field and the morphology of the van der Waals surfaces of layers of these crystals were studied. It was established that impurity clusters consisting of cobalt nanoparticles are formed in the intercalates under investigation on the van der Waals planes in the interlayer space. It was revealed that at room temperature the investigated CoxInTe intercalates exhibit magnetic properties characteristic for magnetically hard ferromagnetic materials.

  13. Unforeseen high temperature and humidity stability of FeCl3 intercalated few layer graphene

    DEFF Research Database (Denmark)

    Wehenkel, Dominique Joseph; Bointon, Thomas Hardisty; Booth, Tim

    2015-01-01

    We present the first systematic study of the stability of the structure and electrical properties of FeCl3 intercalated few-layer graphene to high levels of humidity and high temperature. Complementary experimental techniques such as electrical transport, high resolution transmission electron...... twice higher than the temperature at which the intercalation is conducted. The stability of FeCl3 intercalated few-layer graphene together with its unique values of low square resistance and high optical transparency, makes this material an attractive transparent conductor in future flexible electronic...

  14. Layered and intercalated hydrotalcite-like materials as thermal stabilizers in PVC resin

    Science.gov (United States)

    Lin, Yanjun; Wang, Jianrong; Evans, David G.; Li, Dianqing

    2006-05-01

    In the light of the accepted mechanism of thermal stabilization of PVC by layered double hydroxides (LDHs), the layer cations and interlayer counterions in LDHs were tailored to give MgZnAl-CO3-LDH and MgZnAl-maleate-LDH. These materials were characterized by XRD, FT-IR, and TG DTA. The thermal stability of PVC composites containing different LDH additives was tested in sheets having a thickness of about 1 mm. The results showed that compared with MgAl-CO3-LDH, MgZnAl-CO3-LDH enhances the thermal stability of PVC in terms of both long-term stability and early coloring. After intercalation of maleate in the LDH by reaction of maleic acid with the MgZnAl-CO3-LDH precursor, the interlayer distance increases from 0.75 to 1.11 nm. Since Cl- promotes the autocatalytic dehydrochlorination of PVC, which is responsible for its degradation, an increased interlayer distance should facilitate entry of Cl- into the interlayer galleries and inhibit the decomposition of PVC. In addition, maleic acid has a conjugated C=C double bond which can react with double bond formed in the dehydrochlorination of PVC and thus further inhibit the autocatalytic degradation reaction. The results show that the early coloring of PVC is markedly improved and the long-term stability slightly reduced by addition of the MgZnAl-maleate-LDH.

  15. Modification of nano-sized layered double hydroxides by long-chain organic aliphatic surfactants

    OpenAIRE

    RAMASAMY ANBARASAN; SEUNG SOON IM; WANDUC LEE

    2008-01-01

    The inter-layer anion of layered double hydroxides (LDH) with a hydrotalcite (HT)-like structure was ion-exchanged with various organic surfactants, particularly with long chain aliphatic surfactants. After the ion-exchange process, the basal spacing of the LDH was increased and the increase of the basal spacing depended on various factors, such as the intercalation capacity functionality and orientation capability of the surfactant. Of the employed surfactants, stearic acid intercalated LDH ...

  16. Millisecond analysis of double stranded DNA with fluorescent intercalator by micro-thermocontrol-device.

    Science.gov (United States)

    Arata, Hideyuki F; Gillot, Frederic; Collard, Dominique; Fujita, Hiroyuki

    2009-08-15

    Study of interaction between DNA and intercalator at molecular level is important to understand the mechanisms of DNA replication and repair. A micro-fabricated local heating thermodevice was adapted to perform denaturation experiments of DNA with fluorescent intercalator on millisecond time scale. Response time of complete unzipping of double stranded DNA, 16 microm in length, was measured to be around 5 min by commercial thermocycler. Response time of quenching of double stranded DNA with fluorescent intercalator SYBR Green was measured to be 10 ms. Thus, quenching properties owing to strand unzipping and denaturation at base pair level were distinguished. This method has provided easy access to measure this parameter and may be a powerful methodology in analyzing biomolecules on millisecond time scale.

  17. In situ intercalation dynamics in inorganic-organic layered perovskite thin films.

    Science.gov (United States)

    Ahmad, Shahab; Kanaujia, Pawan K; Niu, Wendy; Baumberg, Jeremy J; Vijaya Prakash, G

    2014-07-09

    The properties of layered inorganic semiconductors can be manipulated by the insertion of foreign molecular species via a process known as intercalation. In the present study, we investigate the phenomenon of organic moiety (R-NH3I) intercalation in layered metal-halide (PbI2)-based inorganic semiconductors, leading to the formation of inorganic-organic (IO) perovskites [(R-NH3)2PbI4]. During this intercalation strong resonant exciton optical transitions are created, enabling study of the dynamics of this process. Simultaneous in situ photoluminescence (PL) and transmission measurements are used to track the structural and exciton evolution. On the basis of the experimental observations, a model is proposed which explains the process of IO perovskite formation during intercalation of the organic moiety through the inorganic semiconductor layers. The interplay between precursor film thickness and organic solution concentration/solvent highlights the role of van der Waals interactions between the layers, as well as the need for maintaining stoichiometry during intercalation. Nucleation and growth occurring during intercalation matches a Johnson-Mehl-Avrami-Kolmogorov model, with results fitting both ideal and nonideal cases.

  18. Preparation and Characterization of Layered Compound Zirconium Bis(monohydrogenphosphate) Intercalated with Rare Earth Complex

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Layered compound zirconium bis(monohydrogenphosphate)(α -ZrP) intercalated with rare earth complex Eu(DBM)3phen was prepared. The pre-intercalation of p-methoxyaniline into α -ZrP makes the interlayer separation large enough to exchange PMA with europium complex, thus, the luminescent assembly was prepared. This was confirmed by X-ray diffraction, UV-visible spectra and elemental analysis. The fluorescence spectra and lifetime of the assembly were also presented.

  19. Hydroxy double salts intercalated with Mn(II) complexes as potential contrast agents

    Science.gov (United States)

    Jin, Miao; Li, Wanjing; Spillane, Dominic E. M.; Geraldes, Carlos F. G. C.; Williams, Gareth R.; Bligh, S. W. Annie

    2016-03-01

    A series of Mn(II) aminophosphonate complexes were successfully synthesized and intercalated into the hydroxy double salt [Zn5(OH)8]Cl2·yH2O. Complex incorporation led to an increase in the interlayer spacing from 7.8 to 10-12 Å. Infrared spectroscopy showed the presence of the characteristic vibration peaks of the Mn(II) complexes in the intercalates' spectra, indicating successful incorporation. The complex-loaded composites had somewhat lower proton relaxivities than the pure complexes. Nevertheless, these intercalates may have use as MRI contrast agents for patients with poor kidney function, where traditional Gd(III)-based contrast agents cause severe renal failure.

  20. Structural Analysis of Layered Polymer Crystals and Application to Photofunctional Materials Using Organic Intercalation

    Institute of Scientific and Technical Information of China (English)

    Shinya Oshita; Akikazu Matsumoto

    2005-01-01

    @@ 1Introduction We reported that layered polymer crystals are obtained by the topochemical polymerization of 1,3-diene monomers and provided as host material for organic intercalation[1]. For intercalation using various long-alkyl amines as the guest species, its reaction behavior, mechanism, characteristics, and potential to application have been clarified[2]. We also succeeded in the synthesis of several host layered polymer crystals with different tacticities and layer structures[3]. We describe here intercalation using various stereoregular poly(muconic acid)s (PMA) and n-alkylamines as the host and guest compounds, respectively. The reaction behavior and the layered structure of the obtained ammonium polymers are discussed from the viewpoint of stereochemical structure of the host polymers.

  1. Structure and Properties of Mg/A1 Layered Double Hydroxides Intercalated with Glutamic Acid: Experimental and Theoretical Studies%谷氨酸插层镁铝水滑石微观结构与性能:实验与理论研究

    Institute of Scientific and Technical Information of China (English)

    杨金田; 潘国祥; 倪哲明

    2012-01-01

    采用共沉淀法合成了谷氨酸插层镁铝水滑石(LDHs-Glu),并使用XRD表征技术以及分子动力学模拟方法对其微观结构与性能进行了研究。结果表明随着LDHs-Glu中水分子数量增加,层间距d003逐渐增大。XRD表征得到其层间距为1.328 nm,与理论模拟得到的当水分子数Nw=7时的水滑石层间距d003=1.323 nm相近。随着层间水分子数量增加,水合能逐渐增大,最终趋于流体水的特征值(-41.8 kJ/mol)。水合过程中,水滑石层板与阴离子间的氢键逐渐减少,而层板与水分子间的氢键逐渐增多,说明水分子与层板间的亲和力更强。实验表征与理论模拟相结合的研究方法,有望成为插层复合材料微观结构研究的重要手段。%Mg/Al layered double hydroxides intercalated with glutamic acid (LDHs-Glu) were synthesized by coprecipitation method.And the structure and properties of LDHs-Glu were in-depth studied by XRD characterization and molecular dynamics simulations(MD).The results show that the interlayer spacing of LDHs-Glu increases with increasing water contents.The d003 value of MD modeling is 1.323 nm when Nw=7,which is close to the experimental result(d003=1.328 nm) of LDHs-Glu.With increasing water content,the energetics of hydration gradually increases,and approaches the characteristic value of bulk liquid water(-41.8 kJ/mol).In the process of hydration,the hydrogen bonds between the layers and anions are gradually reduced,and between the layer and water molecules are gradually increased.It means water molecules have more affinity than the glutamic acid molecules with layer.The combined method with experimental characterization and theoretical modeling would become to an important method to investigate the microstructure of intercalated materials.

  2. Flammability and Mechanical Property of Nylon6 Composite Containing Dihydrogen Phosphate Anion-intercalated Layered Double Hydroxides%插层改性水滑石对尼龙6阻燃及力学性能的影响

    Institute of Scientific and Technical Information of China (English)

    刘喜山; 谷晓昱; 侯慧娟; 董明哲; 江玉; 张胜

    2013-01-01

    The non-halogen flame retarded PA6 composite containing Mg-Al-CO2-3 layered double hydroxides ( CO3-LDHs) and Mg-Al- H2PO4- layered double hydroxides ( H2PO4-LDHs) which was modified by an anion exchange method were prepared. X-ray diffraction ( XRD) and Fourier transform infrared spectroscopy ( FTIR) were used to characterize the structures of CO3-LDHs and H2PO4-LDHs. The XRD and FTIR results showed that the CO3 was successfully replaced by H2PO4 . Static mechanics test and Limiting oxygen index (LOI) and thermal gravimetric (TG) were used to characterize the mechanical property, flammability and thermal behavior of PA6 composite. It was found that the obtained composite displayed not only significant improvement in thermal stability, but also enhancement in flammability. The fire performance and tensile strength of PA6 containing H2PO4-LDHs were superior to that of PA6 containing CO3-LDHs with the same loading. The mechanism had been proposed;the lamellar structure of LDH to protect the PA6 chains;the release of the constituent water in LDH to dilute the flammable gases and decrease the temperature;the replaced H2PO4 into LDHs molecules could promote the char formation during burning process.%以尼龙6(PA6)为基体,分别用镁铝-碳酸根水滑石(CO3-LDHs)和磷酸二氢根插层改性后的镁铝水滑石(H2PO4-LDHs)作为阻燃剂,制备了PA6/CO3-LDHs和PA6/ H2PO4-LDHs无卤阻燃复合材料.通过红外光谱(FTIR)、X射线衍射(XRD)对CO3-LDHs及H2PO4--LDHs进行了结构表征,结果表明:H2PO4-成功插层进入到层间取代了CO32-.通过静态力学测试、极限氧指数(LOI)和垂直燃烧等级(UL-94)的测试,研究了水滑石对材料力学性能以及阻燃性能的影响.结果表明:H2PO4-LDHs更有利于加强PA6阻燃性能和热稳定性,并能在一定程度上提高材料的力学性能.提出了LDH的存在对PA6复合材料燃烧过程的影响机理:水滑石的层状结构能够保护分子链;层间水和结构水的释

  3. Synthesis of Molybdate Inhibitor Based on Intercalated Layered Double Hydroxide(LDH) and Its Anticorrosive Properties%LDH型MoO42-缓蚀剂的合成及防腐性能

    Institute of Scientific and Technical Information of China (English)

    于湘; 俞志东; 程丽华; 潘奇

    2013-01-01

    采用共沉淀法制备了镁铝氢氧化物为层板、MoO42-柱撑的LDH型MoO42-缓蚀剂(记为MoO42-LDH),利用XRD和Raman光谱对样品进行表征.通过缓释实验,讨论了LDH型缓蚀剂的释放能力以及缓蚀剂的缓蚀机理.SEM-EDS、ICP、N2吸附脱附和极化曲线测试结果表明,合成的LDH型MoO42-缓蚀剂具有很好的离子交换和吸附Cl-的性能,释放出MoO42-缓蚀剂进入电解液,24 h内对镁合金的腐蚀电流保持在9.129 μA/cm2,减缓了镁合金腐蚀.添加质量分数20% MoO42-LDH颜料的环氧涂层在质量分数3.5% NaCl溶液中的EIS测试体现出较好的耐蚀作用,耐盐雾腐蚀187 h以上.%Mg-Al layered double hydroxide ( LDH) loaded with molybdate anions were synthesized via coprecipitation method. The resulting compounds were characterized respectively by means of X-ray diffraction (XRD) and Raman spectra. The properties of the release of inhibitor and the inhibition mechanism were observed and analyzed by slow-release experiment. The SEM - EDS, ICP and N2 adsorption-desorption measurements demonstrated the excellent anion-exchange and adsorption capabilities for chloride ion. Polarization curves measurements showed that the filtrate as electrolyte exhibited a lower corrosion current density value due to the presence of MoO2-4 . The results indicate that the released inhibitor can provide adequate corrosion protection, maintaining a corrosion current density at approximately 9. 129 μA/cm2 for magnesium alloy within 24 h. The coatings containing 20% MoO2-4-LDH pigment keep excellent corrosion resistance by electrochemical impedance spectroscopy (EIS) during immersion in 3.5% NaCl solution with more than 187 hours of exposure to salt spray test.

  4. Dynamic tuning of DNA-nanoparticle superlattices by molecular intercalation of double helix.

    Science.gov (United States)

    Pal, Suchetan; Zhang, Yugang; Kumar, Sanat K; Gang, Oleg

    2015-04-01

    Nanoparticle (NP) assembly using DNA recognition has emerged as a powerful tool for the fabrication of 3D superlattices. In addition to the vast structural diversity, this approach provides an avenue for dynamic 3D NP assembly, which is promising for the modulation of interparticle distances and, hence, for example, for in situ tuning of optical properties. While several approaches have been explored for changing NP separations in the lattices using responsiveness of single-stranded DNA (ss-DNA), far less work has been done for the manipulation of most abundant double-stranded DNA (ds-DNA) motifs. Here, we present a novel strategy for modulation of interparticle distances in DNA linked 3D self-assembled NP lattices by molecular intercalator. We utilize ethidium bromide (EtBr) as a model intercalator to demonstrate selective and isotropic lattice expansion for three superlattice types (bcc, fcc, and AlB2) due to the intercalation of ds-DNA linking NPs. We further show the reversibility of the lattice parameter using n-butanol as a retrieving agent as well as an increased lattice thermal stability by 12-14 °C due to the inclusion of EtBr. The proposed intercalator-based strategy permits the creation of reconfigurable and thermally stable superlattices, which could lead to tunable and functionally responsive materials.

  5. Bionanocomposites based on layered double hydroxides as drug delivery systems

    Science.gov (United States)

    Aranda, Pilar; Alcântara, Ana C. S.; Ribeiro, Ligia N. M.; Darder, Margarita; Ruiz-Hitzky, Eduardo

    2012-10-01

    The present work introduces new biohybrid materials involving layered double hydroxides (LDH) and biopolymers to produce bionanocomposites, able to act as effective drug delivery systems (DDS). Ibuprofen (IBU) and 5-aminosalicylic acid (5-ASA) have been chosen as model drugs, being intercalated in a Mg-Al LDH matrix. On the one side, the LDHIBU intercalation compound prepared by ion-exchange reaction was blended with the biopolymers zein, a highly hydrophobic protein, and alginate, a polysaccharide widely applied for encapsulating drugs. On the other side, the LDH- 5-ASA intercalation compound prepared by co-precipitation was assembled to the polysaccharides chitosan and pectin, which show mucoadhesive properties and resistance to acid pH values, respectively. Characterization of the intercalation compounds and the resulting bionanocomposites was carried out by means of different experimental techniques: X-ray diffraction, infrared spectroscopy, chemical and thermal analysis, as well as optical and scanning electron microscopies. Data on the swelling behavior and drug release under different pH conditions are also reported.

  6. Degradation of methyl orange photocatalyzed by polyoxometalate-intercalated layered double hydroxide%杂多酸阴离子[Co2Bi2W20O70]10-柱撑水滑石光催化降解甲基橙

    Institute of Scientific and Technical Information of China (English)

    彭芋杰; 许林

    2012-01-01

    采用离子交换法合成了一种新型的杂多酸阴离子[C02Bi2W20O70]10-柱撑水滑石类层状化合物,利用X射线衍射仪和傅立叶变换红外光谱仪分析了其晶相结构;研究了[Co2 Bi2W20O70]10柱撑水滑石光催化降解甲基橙的活性.结果表明,合成的[Co2B12W20O70]10-杂多酸阴离子柱撑水滑石较好地保持了水滑石原有的晶体形貌,具有较高的离子交换度.与此同时,杂多酸阴离子替换NO3后,可以在一定程度上提高催化剂的催化活性.这主要归因于水滑石材料中杂多酸阴离子和水滑石层板之间的协同效应.%Polyoxometalate-intercalated layered double hydroxide (POM-LDH) was obtained by aqueous ion exchange of a Zn-Al LDH precursor in nitrate. The crystalline structure of result-ant POM-LDH with polyoxometalate anion [Co2Bi2W20O70]10-was analyzed by means of X-ray diffraction and Fourier transform infrared spectrometry. It has been found that as-synthesized POM-LDH well retains the crystalline morphology of hydrotalcite and possesses a high ion ex-change capacity. In the meantime, the intercalation of large cluster anion [Co2 Bi2 W20 O70 ]10 into LDH contributes to increase the catalytic activity to the degradation to cationic dye methyl orange. This is mainly attributed to the synergistic effect between the polyoxometalate anion [Co2Bi2 W20O70]10- and the layered structure of the hydrotalcite.

  7. Intercalation-controlled cyclodehydration of sorbitol in water over layered-niobium-molybdate solid acid.

    Science.gov (United States)

    Morita, Yuya; Furusato, Shogo; Takagaki, Atsushi; Hayashi, Shigenobu; Kikuchi, Ryuji; Oyama, S Ted

    2014-03-01

    Layered niobium molybdate (HNbMoO6 ) was used in the aqueous-phase dehydration of sorbitol and was found to exhibit remarkable selectivity toward its monomolecular-dehydrated intermediate 1,4-sorbitan. This was attributed to the selective intercalation of sorbitol within the interlayers with strong Brønsted acid sites.

  8. 酸性黄25插层水滑石薄膜的制备及其性能研究%Synthesis and Properties of Acid Yellow 25 Dye-Intercalated Layered Double Hydroxides Film

    Institute of Scientific and Technical Information of China (English)

    祝海峰; 唐平贵; 冯拥军; 李殿卿; 段雪

    2012-01-01

    采用原位生长法在铝片基底表面制备了ZnAl-NO3-LDHs水滑石薄膜,以其为前驱体,在弱酸性条件下通过离子交换反应将酸性黄25阴离子插层至ZnAl-LDHs/Al薄膜层间,制备了酸性黄25插层水滑石薄膜,并采用XRD、SEM、FTIR、TG-DTA、UV-Vis和色差计等手段对薄膜进行了表征.XRD和FTIR表征结果表明,酸性黄25阴离子成功地插层到了水滑石薄膜层间,ZnAl-LDHs的层间距由0.87 nm增加到2.96 nm,NO3-阴离子在1 384 cm-1处的特征吸收峰消失,同时出现了酸性黄25阴离子的特征吸收峰.SEM照片显示,水滑石晶片主要以c轴平行于铝片基底生长.TG-DTA分析、UV-Vis分析、色差分析和紫外光老化结果表明,插层后酸性黄25阴离子的耐热性和耐光性均得到了提高.%A ZnAl-NO3-LDHs film was fabricated on aluminum by in situ growth method. The Acid Yellow 25 (p -[5-hydroxy-3-methyl-4-[[3-(phenylsulfamoyl)-p-tolyl]azo]-pyrazol-l-yl] benzenesulfonic acid monosodium salt) (denoted as PTAB) anion intercalated LDHs/Al film was synthesized through ion-exchange method using the ZnAl-NO3-LDHs/Al film as precursor. The prepared film was investigated by powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), Thermogravimetricdifferential thermal analysis (TG-DTA), UV-visible spectroscopy and automatic colorimeter. XRD patterns and FTIR spectra confirm the successful incorporation of PTAB anions into the interlayer galleries of ZnAl-LDHs with an expansion of d-spacing from 0.87 nm to 2.96 nm, the disappearance of characteristic absorption band of NO3-anions at 1 384 cm-1 and the presence of the characteristic absorption of PTAB anions. The SEM morphologies show that the LDHs films are mainly oriented with the c axis of the platelet crystallites parallel to the substrate surface. The TG-DTA analysis, UV-Vis analysis, aberration analysis and photoaging results demonstrate that both the thermal

  9. Layered double hydroxides as containers of inhibitors in organic coatings for corrosion protection of carbon steel

    OpenAIRE

    Hang, To Thi Xuan; Truc, Trinh Anh; Duong, Nguyen Thuy; Pébère, Nadine; Olivier, Marie-Georges

    2012-01-01

    International audience; The present work focuses on the use of layered double hydroxides (LDH) as containers for corrosion inhibitors in an epoxy coating. 2-Benzothiazolylthio-succinic acid (BTSA), used as corrosion inhibitor, was intercalated by co-precipitation in magnesium-aluminum layered double hydroxides. The obtained LDH-BTSA was characterized by infrared spectroscopy, X-ray diffraction and scanning electron microscopy. BTSA release from LDH-BTSA in NaCl solutions was investigated by U...

  10. Hybrid Doping of Few-Layer Graphene via a Combination of Intercalation and Surface Doping

    KAUST Repository

    Mansour, Ahmed

    2017-05-23

    Surface molecular doping of graphene has been shown to modify its work function and increase its conductivity. However, the associated shifts in work function and increases in carrier concentration are highly coupled and limited by the surface coverage of dopant molecules on graphene. Here we show that few-layer graphene (FLG) can be doped using a hybrid approach, effectively combining surface doping by larger (metal-)organic molecules, while smaller molecules, such as Br2 and FeCl3, intercalate into the bulk. Intercalation tunes the carrier concentration more effectively, whereas surface doping of intercalated FLG can be used to tune its work function without reducing the carrier mobility. This multi-modal doping approach yields a very high carrier density and tunable work function for FLG, demonstrating a new versatile platform for fabricating graphene-based contacts for electronic, optoelectronic and photovoltaic applications.

  11. Large-scale simulations of layered double hydroxide nanocomposite materials

    Science.gov (United States)

    Thyveetil, Mary-Ann

    Layered double hydroxides (LDHs) have the ability to intercalate a multitude of anionic species. Atomistic simulation techniques such as molecular dynamics have provided considerable insight into the behaviour of these materials. We review these techniques and recent algorithmic advances which considerably improve the performance of MD applications. In particular, we discuss how the advent of high performance computing and computational grids has allowed us to explore large scale models with considerable ease. Our simulations have been heavily reliant on computational resources on the UK's NGS (National Grid Service), the US TeraGrid and the Distributed European Infrastructure for Supercomputing Applications (DEISA). In order to utilise computational grids we rely on grid middleware to launch, computationally steer and visualise our simulations. We have integrated the RealityGrid steering library into the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) 1 . which has enabled us to perform re mote computational steering and visualisation of molecular dynamics simulations on grid infrastruc tures. We also use the Application Hosting Environment (AHE) 2 in order to launch simulations on remote supercomputing resources and we show that data transfer rates between local clusters and super- computing resources can be considerably enhanced by using optically switched networks. We perform large scale molecular dynamics simulations of MgiAl-LDHs intercalated with either chloride ions or a mixture of DNA and chloride ions. The systems exhibit undulatory modes, which are suppressed in smaller scale simulations, caused by the collective thermal motion of atoms in the LDH layers. Thermal undulations provide elastic properties of the system including the bending modulus, Young's moduli and Poisson's ratios. To explore the interaction between LDHs and DNA. we use molecular dynamics techniques to per form simulations of double stranded, linear and plasmid DNA up

  12. Oxidative leaching of chromium from layered double hydroxides: Mechanistic studies

    Indian Academy of Sciences (India)

    A V Radha; P Vishnu Kamath

    2004-08-01

    The layered double hydroxide (LDH) of Zn with Cr on treatment with a hypochlorite solution releases chromate ions as a result of oxidative leaching by a dissolution–reprecipitation mechanism. The residue is found to be -Zn(OH)2. The LDH of Mg with Cr on the other hand is resistant to oxidative leaching. In contrast, a X-ray amorphous gel of the coprecipitated hydroxides of Mg and Cr yields chromate ions. These results suggest that the oxidation potential of Cr(III) in LDHs is determined by the nature of the divalent ion and the crystallinity of the phase while being unaffected by the nature of the intercalated anions.

  13. The photoluminescence of Co-Al-layered double hydroxide

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    We report a new optical behaviour of pure Co-Al-layered double hydroxide (LDH). It was found that the Co-Al-LDH sample could emit fluorescence without any fluorescent substances intercalated. Its excitation spectrum shows a maximum peak near the wavelength 370 nm, the maximum emission peak appears at 430 nm and the photoluminescence colour of the Co-Al-LDH sample is blue. This new optical property will be expected to extend the potential applications of LDHs in optical materials field.

  14. Critical Dispersion Distance of Silicon Nanoparticles Intercalated between Graphene Layers

    Directory of Open Access Journals (Sweden)

    Shuze Zhu

    2012-01-01

    Full Text Available Nanocomposites of silicon nanoparticles (Si NPs dispersed in between graphene layers emerge as potential anode materials of high-charge capacity for lithium-ion batteries. A key design requirement is to keep Si NPs dispersed without aggregation. Experimental design of the Si NP dispersion in graphene layers has remained largely empirical. Through extensive molecular dynamics simulations, we determine a critical NP dispersion distance as the function of NP size, below which Si NPs in between graphene layers evolve to bundle together. These results offer crucial and quantitative guidance for designing NP-graphene nanocomposite anode materials with high charge capacity.

  15. 10th International School of Materials Science and Technology : Intercalation in Layered Materials "Ettore Majorana"

    CERN Document Server

    1986-01-01

    This volume is prepared from lecture notes for the course "Intercalation in Layered Materials" which was held at the Ettore Majorana Centre for Scientific Culture at Erice, Sicily in July, 1986, as part of the International School of Materials Science and Tech­ nology. The course itself consisted of formal tutorial lectures, workshops, and informal discussions. Lecture notes were prepared for the formal lectures, and short summaries of many of the workshop presentations were prepared. This volume is based on these lecture notes and research summaries. The material is addressed to advanced graduate students and postdoctoral researchers and assumes a background in basic solid state physics. The goals of this volume on Intercalation in Layered Materials include an introduc­ tion to the field for potential new participants, an in-depth and broad exposure for stu­ dents and young investigators already working in the field, a basis for cross-fertilization between workers on various layered host materials...

  16. Energy dissipation in intercalated carbon nanotube forests with metal layers

    Science.gov (United States)

    Boddu, Veera M.; Brenner, Matthew W.

    2016-02-01

    Vertically aligned carbon nanotube (CNT) forests were synthesized to study their quasi-static mechanical properties in a layered configuration with metallization. The top and bottom surfaces of CNT forests were metalized with Ag, Fe, and In using paste, sputtering, and thermal evaporation, respectively. Stacks of one, two, and three layers of these forests were assembled and compressed to measure their mechanical properties. The samples were strain limited to 0.7, and the results indicate that energy dissipation is approximately linear with respect to the number of layers and relatively independent of metal type. The energy per unit volume was approximately the same for all samples. Successive stacking of CNT forests reduces local buckling events, which is enhanced with a thick Ag deposition on the CNT forest surface. Young's modulus was also observed to increase as the number of layers was increased. These results are useful in the design of composite materials for high energy absorption and high stiffness applications.

  17. A chiroptical switch based on DNA/layered double hydroxide ultrathin films.

    Science.gov (United States)

    Shi, Wenying; Jia, Yankun; Xu, Simin; Li, Zhixiong; Fu, Yi; Wei, Min; Shi, Shuxian

    2014-11-04

    A highly oriented film was fabricated by layer-by-layer self-assembly of DNA and MgAl-layered double hydroxide nanosheets, and its application in chiroptical switch was demonstrated via intercalation and deintercalation of an achiral molecule into the DNA cavity. DNA molecules are prone to forming an ordered and dispersive state in the interlayer region of rigid layered double hydroxide (LDH) nanosheets as confirmed by scanning electron microscopy and atomic force microscopy. The induced chiroptical ultrathin film (UTF) is achieved via the intercalation of an achiral chromophore [5,10,15,20-tetrakis(4-N-methylpyridyl)porphine tetra(p-toluenesulfonate) (TMPyP)] into the spiral cavity of DNA stabilized in the LDH matrix [denoted as TMPyP-(DNA/LDH)20]. Fluorescence and circular dichroism spectroscopy are utilized to testify the intercalation of TMPyP into (DNA/LDH)20 UTF that involves two steps: the electrostatic binding of TMPyP onto the surface of (DNA/LDH)20 followed by intercalation into base pairs of DNA. In addition, the TMPyP-(DNA/LDH)20 UTF exhibits good reversibility and repeatability in induced optical chirality, based on the intercalation and deintercalation of TMPyP by alternate exposure to HCl and NH3/H2O vapor, which can be potentially used as a chiroptical switch in data storage.

  18. Immobilization of laccase on hybrid layered double hydroxide

    Directory of Open Access Journals (Sweden)

    David Isidoro Camacho Córdova

    2009-01-01

    Full Text Available Crystals of Mg/Al layered double hydroxide were synthesized by alkaline precipitation and treated in an aqueous solution of glutamic acid. The glutamate ions were not intercalated into the interlayer space, but were detected in the material by Fourier transform infrared spectroscopy, suggesting that only the external surfaces of crystals were modified with glutamate ions. The resulting hybrid material was tested as a support for immobilization of the enzyme laccase (Myceliophthora thermophila. The immobilized enzyme preparation was characterized by electronic paramagnetic resonance spectroscopy and by assays of catalytic activity. The activity of the immobilized laccase was 97% of the activity in the free enzyme. Layered double hydroxide is a suitable support for use in remediation of soil studies.

  19. Lithium intercalation into layered LiMnO2

    DEFF Research Database (Denmark)

    Vitins, G.; West, Keld

    1997-01-01

    Recently Armstrong and Bruce(1) reported a layered modification of lithium manganese oxide, LiMnO2, isostructural with LiCoO2. LiMnO2 obtained by ion exchange from alpha-NaMnO2 synthesized in air is characterized by x-ray diffraction and by electrochemical insertion and extraction of lithium in a...

  20. Energy dissipation in intercalated carbon nanotube forests with metal layers

    Science.gov (United States)

    Vertically aligned carbon nanotube (CNT) forests were synthesized to study their quasi-static mechanical properties in a layered configuration with metallization. The top and bottom surfaces of CNT forests were metalized with Ag, Fe, and In using paste, sputtering, and thermal evaporation, respectiv...

  1. Intermolecular interactions between imidazole derivatives intercalated in layered solids. Substituent group effect

    Energy Technology Data Exchange (ETDEWEB)

    González, M.; Lemus-Santana, A.A. [Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada, Unidad Legaria, Instituto Politécnico Nacional, México, DF (Mexico); Rodríguez-Hernández, J. [Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada, Unidad Legaria, Instituto Politécnico Nacional, México, DF (Mexico); Instituto de Ciencia y Tecnología de Materiales, Universidad de La Habana, Havana (Cuba); Aguirre-Velez, C.I. [Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada, Unidad Legaria, Instituto Politécnico Nacional, México, DF (Mexico); Knobel, M. [Institute of Physics “Gleb Wataghin”, UNICAMP, 13083-970 Campinas, SP (Brazil); Reguera, E., E-mail: edilso.reguera@gmail.com [Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada, Unidad Legaria, Instituto Politécnico Nacional, México, DF (Mexico)

    2013-08-15

    This study sheds light on the intermolecular interactions between imidazole derive molecules (2-methyl-imidazole, 2-ethyl-imidazole and benzimidazole) intercalated in T[Ni(CN){sub 4}] layers to form a solid of formula unit T(ImD){sub 2}[Ni(CN){sub 4}]. These hybrid inorganic–organic solids were prepared by soft chemical routes and their crystal structures solved and refined from X-ray powder diffraction data. The involved imidazole derivative molecules were found coordinated through the pyridinic N atom to the axial positions for the metal T in the T[Ni(CN){sub 4}] layer. In the interlayers region ligand molecules from neighboring layers remain stacked in a face-to-face configuration through dipole–dipole and quadrupole–quadrupole interactions. These intermolecular interactions show a pronounced dependence on the substituent group and are responsible for an ImD-pillaring concatenation of adjacent layers. This is supported by the structural information and the recorded magnetic data in the 2–300 K temperature range. The samples containing Co and Ni are characterized by presence of spin–orbit coupling and pronounced temperature dependence for the effective magnetic moment except for 2-ethyl-imidazole related to the local distortion for the metal coordination environment. For this last one ligand a weak ferromagnetic ordering ascribed to a super-exchange interaction between T metals from neighboring layers through the ligands π–π interaction was detected. - Graphical abstract: In the interlayers region imidazole derivative molecules are oriented according to their dipolar and quadrupolar interactions and minimizing the steric impediment. Highlights: • Imidazole derivatives intercalation compounds. • Intermolecular interaction between intercalated imidazole derivatives. • Hybrid inorganic–organic solids. • Pi–pi interactions and ferromagnetic coupling. • Dipolar and quadrupolar interactions between intercalated imidazole derivatives.

  2. Layered materials with improved magnesium intercalation for rechargeable magnesium ion cells

    Energy Technology Data Exchange (ETDEWEB)

    Doe, Robert E.; Downie, Craig M.; Fischer, Christopher; Lane, George H.; Morgan, Dane; Nevin, Josh; Ceder, Gerbrand; Persson, Kristin A.; Eaglesham, David

    2016-01-19

    Electrochemical devices which incorporate cathode materials that include layered crystalline compounds for which a structural modification has been achieved which increases the diffusion rate of multi-valent ions into and out of the cathode materials. Examples in which the layer spacing of the layered electrode materials is modified to have a specific spacing range such that the spacing is optimal for diffusion of magnesium ions are presented. An electrochemical cell comprised of a positive intercalation electrode, a negative metal electrode, and a separator impregnated with a nonaqueous electrolyte solution containing multi-valent ions and arranged between the positive electrode and the negative electrode active material is described.

  3. Layered materials with improved magnesium intercalation for rechargeable magnesium ion cells

    Energy Technology Data Exchange (ETDEWEB)

    Doe, Robert Ellis; Downie, Craig Michael; Fischer, Christopher; Lane, George Hamilton; Morgan, Dane; Nevin, Josh; Ceder, Gerbrand; Persson, Kristin Aslaug; Eaglesham, David

    2016-07-26

    Electrochemical devices which incorporate cathode materials that include layered crystalline compounds for which a structural modification has been achieved which increases the diffusion rate of multi-valent ions into and out of the cathode materials. Examples in which the layer spacing of the layered electrode materials is modified to have a specific spacing range such that the spacing is optimal for diffusion of magnesium ions are presented. An electrochemical cell comprised of a positive intercalation electrode, a negative metal electrode, and a separator impregnated with a nonaqueous electrolyte solution containing multi-valent ions and arranged between the positive electrode and the negative electrode active material is described.

  4. Formation and rejoining of deoxyribonucleic acid double-strand breaks induced in isolated cell nuclei by antineoplastic intercalating agents.

    Science.gov (United States)

    Pommier, Y; Schwartz, R E; Kohn, K W; Zwelling, L A

    1984-07-03

    The biochemical characteristics of the formation and disappearance of intercalator-induced DNA double-strand breaks (DSB) were studied in nuclei from mouse leukemia L1210 cells by using filter elution methodology [Bradley, M. O., & Kohn, K.W. (1979) Nucleic Acids Res. 7, 793-804]. The three intercalators used were 4'-(9-acridinylamino)-methanesulfon-m-anisidide (m-AMSA), 5-iminodaunorubicin (5-ID), and ellipticine. These compounds differ in that they produced predominantly DNA single-strand breaks (SSB) (m-AMSA) or predominantly DNA double-strand breaks (ellipticine) or a mixture of both SSB and DSB (5-ID) in whole cells. In isolated nuclei, each intercalator produced DSB at a frequency comparable to that which is produced in whole cells. Moreover, these DNA breaks reversed within 30 min after drug removal. It thus appeared that neither ATP nor other nucleotides were necessary for intercalator-dependent DNA nicking-closing reactions. The formation of the intercalator-induced DSB was reduced at ice temperature. Break formation was also reduced in the absence of magnesium, at a pH above 6.4 and at NaCl concentrations above 200 mM. In the presence of ATP and ATP analogues, the intercalator-induced cleavage was enhanced. These results suggest that the intercalator-induced DSB are enzymatically mediated and that the enzymes involved in these reactions can catalyze DNA double-strand cleavage and rejoining in the absence of ATP, although the occupancy of an ATP binding site might convert the enzyme to a form more reactive to intercalators. Three inhibitors of DNA topoisomerase II--novobiocin, nalidixic acid, and norfloxacin--reduced the formation of DNA strand breaks.(ABSTRACT TRUNCATED AT 250 WORDS)

  5. Regenerable Cu-intercalated MnO2 layered cathode for highly cyclable energy dense batteries

    Science.gov (United States)

    Yadav, Gautam G.; Gallaway, Joshua W.; Turney, Damon E.; Nyce, Michael; Huang, Jinchao; Wei, Xia; Banerjee, Sanjoy

    2017-03-01

    Manganese dioxide cathodes are inexpensive and have high theoretical capacity (based on two electrons) of 617 mAh g-1, making them attractive for low-cost, energy-dense batteries. They are used in non-rechargeable batteries with anodes like zinc. Only ~10% of the theoretical capacity is currently accessible in rechargeable alkaline systems. Attempts to access the full capacity using additives have been unsuccessful. We report a class of Bi-birnessite (a layered manganese oxide polymorph mixed with bismuth oxide (Bi2O3)) cathodes intercalated with Cu2+ that deliver near-full two-electron capacity reversibly for >6,000 cycles. The key to rechargeability lies in exploiting the redox potentials of Cu to reversibly intercalate into the Bi-birnessite-layered structure during its dissolution and precipitation process for stabilizing and enhancing its charge transfer characteristics. This process holds promise for other applications like catalysis and intercalation of metal ions into layered structures. A large prismatic rechargeable Zn-birnessite cell delivering ~140 Wh l-1 is shown.

  6. Zn-Al LAYERED DOUBLE HYDROXIDE PILLARED BY DIFFERENT DICARBOXYLATE ANIONS

    Directory of Open Access Journals (Sweden)

    S. Gago

    2004-12-01

    Full Text Available Zn-Al layered double hydroxides (LDHs intercalated by terephthalate (TPH and biphenyl-4,4'-dicarboxylate (BPH anions have been synthesized by direct co-precipitation from aqueous solution. The Zn/Al ratio in the final materials was 1.8. The products were characterized by powder X-ray diffraction, thermogravimetric analysis, FTIR and FT Raman spectroscopy, and MAS NMR spectroscopy. The basal spacing for the TPH-LDH intercalate was 14.62 Å, indicating that the guest anions stack to form a monolayer with the aromatic rings perpendicular to the host layers. For the LDH intercalate containing BPH anions, a basal spacing of at least 19.2 Å would be expected if the anions adopted an arrangement similar to that for the TPH anions. The observed spacing was 18.24 Å, suggesting that the anions are tilted slightly with respect to the host layers.

  7. Intercalation of Mg-ions in layered V2O5 cathode materials for rechargeable Mg-ion batteries

    DEFF Research Database (Denmark)

    Sørensen, Daniel Risskov; Johannesen, Pætur; Christensen, Christian Kolle

    The development of functioning rechargeable Mg-ion batteries is still in its early stage, and a coarse screening of suitable cathode materials is still on-going. Within the intercalation-type cathodes, layered crystalline materials are of high interest as they are known to perform well in Li......-ion intercalation batteries and are also increasingly being explored for Na-ion batteries. Here, we present an investigation of the layered material orthorhombic V2O5, which is a classical candidate for an ion-intercalation material having a high theoretical capacity1. We present discharge-curves for the insertion...

  8. Chronopotentiometric study of the intercalation of layer semiconductors of A/sup 3/B/sup 6/ type

    Energy Technology Data Exchange (ETDEWEB)

    Bakhmatyuk, B.P.; Grigorchak, I.I.; Kovalyuk, Z.D.; Yurtsenyuk, S.P.; Kaminskij, V.M. (AN Ukrainskoj SSR, Kiev. Inst. Problem Materialovedeniya)

    1984-10-01

    By the electrochemical method the process of the intercalation of layer semiconductor indium and gallium monochalcogenides is investigated. The chromopotentiograms of the processes of reduction and oxidation of electrodes from layer indium and gallium monoselenides in a monomolar propylene carbonate lithium perchlorate solution are studied. It is shown that the electrochemical intercalation leads to formation of Lisub(x)InSe and Lisub(x)GaSe ternary compounds. The formation free energy of these compounds is increased with the growth of the degree of reduction of these compounds. Simultaneously one can conclude on the reversibility of the intercalation process by lithium of indium and gallium monoselenides.

  9. An Electromagnetic GL Double Layered Cloak

    CERN Document Server

    Xie, Ganquan; Xie, Feng; Xie, Lee

    2009-01-01

    In this paper, we propose a new electromagnetic (EM) GL double layered cloak. The GL double layered cloak is consist of two sphere annular layers, $R_1 \\le r \\le R_2$ and $R_2 \\le r \\le R_3$. Two type cloak materials are proposed and installed in the each layer, respectively. The outer layer cloak of the GL double layered cloak has the invisible function, the inner layer cloak has fully absorption function. The GL double layered metamaterials are weak degenerative and weak dispersive. When the source is located outside of the GL double layered cloak, the excited EM wave field propagation outside of the double layered cloak is as same as in free space and never be disturbed by the cloak; also, the exterior EM wave can not penetrate into the inner layer and concealment. When local sources are located inside of the GL double cloaked concealment with the normal EM materials, the excited EM wave is propagating under Maxwell equation governing, it is complete absorbed by the inner layer cloak of GL double cloak and...

  10. Synthesis and properties of mecoprop-intercalated layered double hydroxide

    Science.gov (United States)

    Ahmed Khan, Modabber; Choi, Choong-Lyeal; Lee, Dong-Hoon; Park, Man; Lim, Bu-Kug; Lee, Jong-Yoon; Choi, Jyung

    2007-08-01

    This study carried out to elucidate the synthesis of MCPP LDH hybrid, release pattern of MCPP from MCPP LDH hybrid and their properties. MCPP LDH hybrid was synthesized from MCPP and Mg Al complex. Release pattern of MCPP from MCPP LDH hybrid was slower in distilled water and soil solution but it was slower in distilled water than soil solution. MCPP LDH hybrid has shown more stable condition than CO32- form of LDH in thermal and acidic condition. Therefore, MCPP LDH hybrid would lead as functional and benign pesticide to minimize the harmful effects on soil environment by bulk herbicides.

  11. Optical and Electrochemical Properties of Layered Crystals GaSe Intercalated by the Nickel

    Directory of Open Access Journals (Sweden)

    S.G. Barbutsa

    2013-10-01

    Full Text Available The presented results of the investigations of the optical and electrochemical properties indicate the possibility of intercalation of layered GaSe crystals with nickel ions. Established that the electrochemical introduction of Ni leads to a monotonic growth in electrode potential of layered semiconductors GaSe when a concentration of intercalants nNi  1018-1020сm – 3. In consequence of intercalation of nickel in GaSe crystal at T  293 K, occurred ncreases in the energy position of the exciton peak Eeks 6 meV (from 2.008 to 2.014 eV and the half-width of the exciton absorption bands of H by 5.2 meV. At a temperature T  77 K was detected non- monotonous concentration dependence of the excitonic maximum energy location for Еeks NiGaSe compounds. The dependence Еeks(nNi for these compounds are explained as a result of the introduction of competition between contributions of inter - and intralayer deformations which have the opposite signs of deformation potential.

  12. The Study of Surfaces' Micro- and Nanostructure on Interlayer Cleavages of InSe Layered Crystals Intercalated by Nickel

    Directory of Open Access Journals (Sweden)

    P.V. Galiy

    2016-03-01

    Full Text Available This paper presents the results of experimental study concerning element-phase composition, crystallographic structure, topography and electron-energy structure of interlayer cleavage (0001 surfaces, obtained for nickel intercalated (Ni3dInSe intercalate InSe layered crystals, by means of qualitative and quantitative X-ray photoelectron spectroscopy (XPS, low energy electron diffraction (LEED and scanning tunneling microscopy/spectroscopy (STM/STS. It was established that for all layered crystals' intercalates with different concentrations of nickel in initial synthesized InSe + x at.% Ni (x ≤ 10,0 % alloys and layered crystals further grown from them by Bridgman-Stockbarger method and subjected to intercalation, the maximum concentration of nickel on the cleavage (0001 surfaces of NiхInSe intercalates and, accordingly, in the interlayer gaps of up to 7.67 at. % is observed at 0.75 at. % of nickel in synthesized alloys. Nickel doesn't interact with selenium and indium and there are also no interaction with oxygen and carbon. It is established that nickel is placed in the interlayer gaps of NiхInSe intercalates and, accordingly, appears on the interlayer cleavage (0001 surfaces as fine-phase metal nickel clusters. The studied NiхInSe intercalate system is the perfect hybrid structure with the ability to use in magnetoelectronics.

  13. PREDICTION OF THE VISCOELASTIC PROPERTIES OF THE EQUIVALENT PARTICLE FOR THE INTERCALATED MULTI-LAYER STACK OF NANOPLASTICS

    Institute of Scientific and Technical Information of China (English)

    Weimin Zhang; Ping Zhang; Xuhui Deng; Chunyuan Zhang

    2007-01-01

    The aim of this paper is to apply the asymptotic homogenization method to determining analytically and numerically the transversely isotropic viscoelastic relaxation moduli of the equivalent particle for the intercalated multi-layer stack of intercalated type nanoplastics. A two-phase multilayered material containing n layers is considered. The matrix is assumed to be an isotropic viscoelastic standard linear body and the reinforcement is assumed to be an isotropic elastic body. Final explicit analytical formulae for the effective elastic moduli of the multilayered material are derived first; and then the correspondence principle is employed to obtain the homogenized relaxation moduli of the equivalent intercalated particle. A numerical example is given. Final explicit analytical formulae in the time domain derived here make it convenient to estimate the influence of all the particle parameters of micro-structural details on the effective properties of the equivalent intercalated particle. The results of this paper can also be applied to multi-layer composites.

  14. Layer Number Dependence of Li(+) Intercalation on Few-Layer Graphene and Electrochemical Imaging of Its Solid-Electrolyte Interphase Evolution.

    Science.gov (United States)

    Hui, Jingshu; Burgess, Mark; Zhang, Jiarui; Rodríguez-López, Joaquín

    2016-04-26

    A fundamental question facing electrodes made out of few layers of graphene (FLG) is if they display chemical properties that are different to their bulk graphite counterpart. Here, we show evidence that suggests that lithium ion intercalation on FLG, as measured via stationary voltammetry, shows a strong dependence on the number of layers of graphene that compose the electrode. Despite its extreme thinness and turbostratic structure, Li ion intercalation into FLG still proceeds through a staging process, albeit with different signatures than bulk graphite or multilayer graphene. Single-layer graphene does not show any evidence of ion intercalation, while FLG with four graphene layers displays limited staging peaks, which broaden and increase in number as the layer number increases to six. Despite these mechanistic differences on ion intercalation, the formation of a solid-electrolyte interphase (SEI) was observed on all electrodes. Scanning electrochemical microscopy (SECM) in the feedback mode was used to demonstrate changes in the surface conductivity of FLG during SEI evolution. Observation of ion intercalation on large area FLG was conditioned to the fabrication of "ionic channels" on the electrode. SECM measurements using a recently developed Li-ion sensitive imaging technique evidenced the role of these channels in enabling Li-ion intercalation through localized flux measurements. This work highlights the impact of nanostructure and microstructure on macroscopic electrochemical behavior and provides guidance to the mechanistic control of ion intercalation using graphene, an atomically thin interface where surface and bulk reactivity converge.

  15. Modification of nano-sized layered double hydroxides by long-chain organic aliphatic surfactants

    Directory of Open Access Journals (Sweden)

    RAMASAMY ANBARASAN

    2008-03-01

    Full Text Available The inter-layer anion of layered double hydroxides (LDH with a hydrotalcite (HT-like structure was ion-exchanged with various organic surfactants, particularly with long chain aliphatic surfactants. After the ion-exchange process, the basal spacing of the LDH was increased and the increase of the basal spacing depended on various factors, such as the intercalation capacity functionality and orientation capability of the surfactant. Of the employed surfactants, stearic acid intercalated LDH showed the highest increase of the basal spacing, which was confirmed by XRD analysis. FTIR results supported the interaction of the surfactants with the LDH. In addition, an increase in the thermal stability of the dodecanedioic acid intercalated HT was evidenced by the TGA method.

  16. Preparation of poly(ethylene terephthalate/layered double hydroxide nanocomposites by in-situ polymerization and their thermal property

    Directory of Open Access Journals (Sweden)

    Q. Jiao

    2012-06-01

    Full Text Available Terephthalate (TA intercalated layered double hydroxides (LDHs were synthesized using hydroxides as raw materials, and poly(ethylene terephthalate (PET/LDH nanocomposites with different contents of TA intercalated LDHs were prepared by in-situ polymerization. The structure, morphology and thermal property of PET/LDH nanocomposites were investigated. The TA intercalated LDHs were partially exfoliated and well dispersed in PET matrix. The PET/LDH nanocomposites exhibit enhanced thermal stability relative to pure PET, confirmed by the thermogravimetric analysis results. The results of differential scanning calorimetry suggest that LDH nanoparticles could effectively promote the nucleation and crystallization of PET.

  17. Adsorption of Ni2+ from the aqueous solution by the tartrate intercalated MgAl layered double hydroxides%酒石酸柱撑水滑石吸附水中的Ni2+的特性研究∗

    Institute of Scientific and Technical Information of China (English)

    申延明; 赵晓蕾; 张僖; 刘东斌; 樊丽辉; 李士凤

    2015-01-01

    采用离子交换法制得酒石酸插层 MgAl 水滑石(MgAl-TA LDHs),并进行了 XRD、IR、SEM、比表面积及孔径分析表征。考察了 MgAl-TA LDHs 吸附剂对溶液中Ni2+的吸附能力,探讨了水滑石吸附剂投加量、Ni2+溶液浓度、p H 值以及吸附温度对 Ni2+吸附率的影响,并进行了动力学和热力学特征的研究。结果表明,适宜的水滑石投加量为2 g/L,p H 值以中性为宜,对于 Ni2+浓度不超过100 mg/L 的溶液室温下Ni2+吸附率在60%以上,而高温有利于提高 Ni2+吸附率。吸附过程符合二级动力学模型,吸附等温曲线可用R-P模型来描述。吸附过程能够自发进行,为吸热过程,属于化学吸附。%The tartrate intercalated MgAl layered double hydroxides (MgAl-TA LDHs)was prepared by anion-exchange method.The samples prepared were characterized by XRD,FT-IR and used to uptake Ni2+ from the aqueous solutions.The effects of adsorbent dosage,initial Ni2+ concertration,pH,adsorption temperature on the Ni2+ adsorption efficiency were investigated.The characters of thermodynamics and kinetics were discussed. The results showed that the suitable adsorbent dosage was 2 g/L,and pH was neutral.Under the above contidi-tions,Ni2+ adsorption efficiency was over 60% at the Ni2+ concentration less than 100 mg/L.High temperature was beneficial to improving Ni2+ adsorption efficiency.Adsorption process conforms to the second-order kinetics model and the isothermal adsorption curve can be described by R-P model.The adsorption process was sponta-neous and endothermic,and was belonged to chemisorption.

  18. Incorporation of fluorophosphate into zinc–aluminium–nitrate layered double hydroxide by ion exchange

    Indian Academy of Sciences (India)

    El Hassan Elkhattabi; Mohamed Badreddine; Moha Berraho; Ahmed Legrouri

    2012-08-01

    The intercalation of fluorophosphate (PO3F2-, FP) in the [Zn–Al] layered double hydroxides (LDHs) was investigated. A nitrate precursor was prepared by coprecipitaion at pH 9. An attempt to intercalate FP by direct coprecipitation reaction led to a poorly crystalline LDH phase. The effects of pH, aging time and anion concentration were studied and allowed to confirm that the best crystalline material, with high exchange extent, was obtained by carrying out the exchange at 25 °C in 0.1 M FP solution at pH 9 with at least 20 h of aging time.

  19. Nanocomposite Material Based on GaSe and InSe Layered Crystals Intercalated by RbNO3 Ferroelectric

    Directory of Open Access Journals (Sweden)

    Z.R. Kudrynskyi

    2013-10-01

    Full Text Available In the present study, we established for the first time that single-crystal samples of gallium GaSe and indium InSe selenides can be intercalated by molecules of RbNO3 ferroelectric salt rubidium nitrate. We investigated kinetics of the intercalation process at different temperature-time regimes. Structural properties of the intercalate nanocomposites were studied by X-ray diffraction. The studied structures can be presented as composite superlattices which consist of a lattice of anisotropic layered semiconductor with embedded ferroelectric layers. We established that GaSe nanocomposite material exhibits electric energy storage properties. Energy storage properties are associated with polarization of the intercalated ferroelectric under external electric field. We developed a solid state electric energy storage device on the basis of GaSe nanocomposite material.

  20. Dynamical Aspects of Electrostatic Double Layers

    DEFF Research Database (Denmark)

    Raadu, M.A.; Juul Rasmussen, J.

    1988-01-01

    Electrostatic double layers have been proposed as an acceleration mechanism in solar flares and other astrophysical objects. They have been extensively studied in the laboratory and by means of computer simulations. The theory of steady-state double layers implies several existence criteria...

  1. Stationary Double Layers in a Collisionless Magnetoplasma

    DEFF Research Database (Denmark)

    Noriyoshi, Sato; Mieno, Tetsu; Hatakeyama, Rikizo;

    1983-01-01

    Stationary double layers are generated in a magnetoplasma by applying potential differences between two heated plates on which the plasma is produced by surface ionization. By measuring the double-layer formation process, a localized potential drop is found to be formed initially in front of the ...

  2. Chemical modification of zinc hydroxide nitrate and Zn-Al-layered double hydroxide with dicarboxylic acids.

    Science.gov (United States)

    Arizaga, Gregorio Guadalupe Carbajal; Mangrich, Antonio Salvio; da Costa Gardolinski, José Eduardo Ferreira; Wypych, Fernando

    2008-04-01

    A zinc hydroxide nitrate (ZHN), Zn5(OH)8(NO3)2.2H2O, and a layered double hydroxide (LDH), Zn/Al-NO3 were doped with 0.2 mol% of Cu2+ during alkaline chemical precipitation. Both compounds were intercalated with adipate ((-)OOC(CH2)4COO(-)), azelate ((-)OOC(CH2)7COO(-)), and benzoate (C6H5COO(-)) ions through ion exchange reactions. Solid state 13C nuclear magnetic resonance spectroscopy showed only one signal of carboxylic carbon for adipate and azelate intercalated into LDH, indicating that the carboxylic ends of both acids were equivalent, whereas the signal split when the intercalation was into the ZHN matrix. The electron paramagnetic resonance (EPR) spectrum of copper in octahedral cation sites of LDH layers showed a Hamiltonian parameter ratio g ||/A ||=170 cm and, after intercalation of adipate, the change was not significant: g ||/A ||=174 cm. This result indicates that the carboxylate ions did not coordinate with copper centers. Nonetheless, the intercalation of azelate increased the ratio to g ||/A ||=194 cm, similar to the spectra of ZHN modified with adipate, g ||/A ||=199 cm, and azelate, g ||/A ||=183 and 190 cm, which are associated with the coordination of copper by weak carboxylate anion ligands. Copper occupies octahedral or tetrahedral sites in ZHN layers, and the EPR spectra indicate that the dicarboxylate anions reacted preferentially with octahedral sites, whereas benzoate reacted with both sites.

  3. Electric fields and double layers in plasmas

    Science.gov (United States)

    Singh, Nagendra; Thiemann, H.; Schunk, R. W.

    1987-05-01

    Various mechanisms for driving double layers in plasmas are briefly described, including applied potential drops, currents, contact potentials, and plasma expansions. Some dynamical features of the double layers are discussed. These features, as seen in simulations, laboratory experiments, and theory, indicate that double layers and the currents through them undergo slow oscillations which are determined by the ion transit time across an effective length of the system in which double layers form. It is shown that a localized potential dip forms at the low potential end of a double layer, which interrupts the electron current through it according to the Langmuir criterion, whenever the ion flux into the double is disrupted. The generation of electric fields perpendicular to the ambient magnetic field by contact potentials is also discussed. Two different situations were considered; in one, a low-density hot plasma is sandwiched between high-density cold plasmas, while in the other a high-density current sheet permeates a low-density background plasma. Perpendicular electric fields develop near the contact surfaces. In the case of the current sheet, the creation of parallel electric fields and the formation of double layers are also discussed when the current sheet thickness is varied. Finally, the generation of electric fields and double layers in an expanding plasma is discussed.

  4. Rare earth and zinc layered hydroxide salts intercalated with the 2-aminobenzoate anion as organic luminescent sensitizer

    Energy Technology Data Exchange (ETDEWEB)

    Cursino, Ana Cristina Trindade, E-mail: anacursino@ufpr.br [CEPESQ – Research Centre of Applied Chemistry, Department of Chemistry, Universidade Federal do Paraná – P.O. Box 19081, 81531-980 Curitiba, PR (Brazil); Rives, Vicente, E-mail: vrives@usal.es [GIR-QUESCAT – Department of Inorganic Chemistry, Universidad de Salamanca, Plaza de la Merced S/N, 37998 Salamanca (Spain); Arizaga, Gregorio Guadalupe Carbajal, E-mail: gregoriocarbajal@yahoo.com.mx [Universidad de Guadalajara, Department of Chemistry, Boulevard Marcelino García Barragán 1421, C.P. 44430 Guadalajara, Jalisco (Mexico); Trujillano, Raquel, E-mail: rakel@usal.es [GIR-QUESCAT – Department of Inorganic Chemistry, Universidad de Salamanca, Plaza de la Merced S/N, 37998 Salamanca (Spain); Wypych, Fernando, E-mail: wypych@ufpr.br [CEPESQ – Research Centre of Applied Chemistry, Department of Chemistry, Universidade Federal do Paraná – P.O. Box 19081, 81531-980 Curitiba, PR (Brazil)

    2015-10-15

    Rare earth (RE = Eu, Y and Tb) and zinc layered hydroxide salts intercalated with nitrate anions were synthesized, followed by exchange with 2-aminobenzoate. The UV absorption ability was improved after intercalation/grafting in relation to that shown by the parent material. - Highlights: • Rare earth (RE = Eu, Y and Tb) and zinc layered hydroxide were synthesized. • Intercalated nitrate anions were exchanged by 2-aminobenzoate. • In all the 2-aminobenzoate containing compounds, the grafting reaction was detected. • The UV absorption ability was improved after the exchange reactions. • Rare earth hydroxide salts are potential matrixes to produce luminescent materials. - Abstract: Rare earth (RE = Eu, Y and Tb) and zinc layered hydroxide salts intercalated with nitrate anions were synthesized, followed by exchange with 2-aminobenzoate. The obtained compounds were characterized by powder X-ray diffraction (PXRD), Fourier transform infrared (FTIR) and ultraviolet visible (UV–vis) spectroscopies, fluorescence measurements and thermal analysis (TGA/DTA). The results from FTIR spectroscopy suggest a direct coordination of 2-aminobenzoate to the metal cations of the inorganic layered structure. The organic derivative products from the intercalation reactions absorb a broader range of UV-light in relation to that shown by the parent material; the photoluminescence measurements present a strong violet, blue and green luminescence under UV-light excitation for layered compounds with, Zn, Y and Tb, respectively. Rare earth hydroxide salts (RE-LHS) are potential alternative matrices for the immobilization of organic species to produce luminescent materials.

  5. Study on the Effect of Pt Intercalation into Layered Niobate Perovskite for Photocatalytic Behavior.

    Science.gov (United States)

    Xu, Nan; Takei, Takahiro; Miura, Akira; Kumada, Nobuhiro; Katsumata, Ken-ichi; Matsushita, Nobuhiro; Okada, Kiyoshi

    2015-07-14

    A novel photocatalyst consisting of an intercalated perovskite H(1-2x)Pt(x)LaNb2O7 was fabricated by ion exchange. Synchrotron X-ray diffraction and X-ray photoelectron spectroscopy results confirmed that Pt(2+) exists within the interlayer space of the layered perovskite. H(1-2x)Pt(x)LaNb2O7 composed of layered niobate perovskite and intercalated Pt(2+) completely degraded a 20 ppm phenol solution in 3 h under irradiation by Xe light, which exhibits photocatalytic activity superior to those of RbLaNb2O7, Pt-deposited RbLaNb2O7, and HLaNb2O7. From first-principles density functional theory simulation, high photocatalytic activity of H(1-2x)Pt(x)LaNb2O7 is attributed to the emergence of a new O 2p-Pt 5d hybridized band on top of the valence band.

  6. Layered lithium cobalt nitrides: A new class of lithium intercalation compounds

    Energy Technology Data Exchange (ETDEWEB)

    Ducros, J.B.; Bach, S.; Pereira-Ramos, J.P. [Institut de Chimie et des Materiaux Paris Est, GESMAT, UMR CNRS 7182, 2 rue Henri-Dunant, 94320 Thiais (France); Willmann, P. [Centre National d' Etudes Spatiales, 118 avenue Edouard Belin, 31401 Toulouse Cedex 9 (France)

    2008-01-03

    Lithium cobalt nitrides Li{sub 3-2x}Co{sub x}N (0.1 {<=} x {<=} 0.44) have been prepared and investigated as negative electrode in the 1/0.02 V potential window. The evolution of the unit cell parameters and unit cell volume with the Co content show a solid solution behaviour. Whatever the Co content, all these nitrides are electroactive with a single step around 0.6 V/0.7 V for the discharge and charge processes, respectively. The electrochemical behaviour observed is typical of a Li intercalation compound and involves the Co{sup 2+}/Co{sup +} redox couple in the interlayer plane combined with the reversible accommodation of Li{sup +} ions in the cation vacancies located in Li{sub 2}N{sup -} layers. XRD experiments performed after discharge, charge and cycling tests clearly indicate the hexagonal layered structure of the host lattice is maintained. This intercalation process explains the excellent capacity retention found after 50 cycles. A specific capacity of 180 mAh g{sup -1} at C/20 and 130 mAh g{sup -1} at C/5 rate (100 mA cm{sup -2}) is achieved for Li{sub 2.23}Co{sub 0.39}N. ac impedance measurements have allowed to characterize the kinetics of the reaction. (author)

  7. Layered Double Hydroxide-Based Nanocarriers for Drug Delivery

    Science.gov (United States)

    Bi, Xue; Zhang, Hui; Dou, Liguang

    2014-01-01

    Biocompatible clay materials have attracted particular attention as the efficient drug delivery systems (DDS). In this article, we review developments in the use of layered double hydroxides (LDHs) for controlled drug release and delivery. We show how advances in the ability to synthesize intercalated structures have a significant influence on the development of new applications of these materials. We also show how modification and/or functionalization can lead to new biotechnological and biomedical applications. This review highlights the most recent progresses in research on LDH-based controlled drug delivery systems, focusing mainly on: (i) DDS with cardiovascular drugs as guests; (ii) DDS with anti-inflammatory drugs as guests; and (iii) DDS with anti-cancer drugs as guests. Finally, future prospects for LDH-based drug carriers are also discussed. PMID:24940733

  8. Layered Double Hydroxide-Based Nanocarriers for Drug Delivery

    Directory of Open Access Journals (Sweden)

    Xue Bi

    2014-06-01

    Full Text Available Biocompatible clay materials have attracted particular attention as the efficient drug delivery systems (DDS. In this article, we review developments in the use of layered double hydroxides (LDHs for controlled drug release and delivery. We show how advances in the ability to synthesize intercalated structures have a significant influence on the development of new applications of these materials. We also show how modification and/or functionalization can lead to new biotechnological and biomedical applications. This review highlights the most recent progresses in research on LDH-based controlled drug delivery systems, focusing mainly on: (i DDS with cardiovascular drugs as guests; (ii DDS with anti-inflammatory drugs as guests; and (iii DDS with anti-cancer drugs as guests. Finally, future prospects for LDH-based drug carriers are also discussed.

  9. Hexagonal boron nitride intercalated multi-layer graphene: a possible ultimate solution to ultra-scaled interconnect technology

    Directory of Open Access Journals (Sweden)

    Yong-Jun Li

    2012-03-01

    Full Text Available We proposed intercalation of hexagonal boron nitride (hBN in multilayer graphene to improve its performance in ultra-scaled interconnects for integrated circuit. The effect of intercalated hBN layer in bilayer graphene is investigated using non-equilibrium Green's functions. We find the hBN intercalated bilayer graphene exhibit enhanced transport properties compared with pristine bilayer ones, and the improvement is attributed to suppression of interlayer scattering and good planar bonding condition of inbetween hBN layer. Based on these results, we proposed a via structure that not only benefits from suppressed interlayer scattering between multilayer graphene, but also sustains the unique electrical properties of graphene when many graphene layers are stacking together. The ideal current density across the structure can be as high as 4.6×109 A/cm2 at 1V, which is very promising for the future high-performance interconnect.

  10. Phosphor Dysprosium-Doped Layered Double Hydroxides Exchanged with Different Organic Functional Groups

    Directory of Open Access Journals (Sweden)

    David Ricardo Martínez Vargas

    2013-01-01

    Full Text Available The layers of a Zn/Al layered double hydroxide (LDH were doped with Dy3+ cations. Among some compositions, the Zn2+ : Al3+ : Dy3+ molar ratio equal to 30 : 9 : 1 presented a single crystalline phase. Organic anions with carboxylic, amino, sulfate, or phosphate functional groups were intercalated as single layers between LDH layers as confirmed by X-ray diffraction and infrared spectroscopy. Photoluminescence spectra of the nitrate intercalated LDH showed a wide emission band with strong intensity in the yellow region (around 574 nm, originated due to symmetry distortion of the octahedral coordination in dysprosium centers. Moreover, a broad red band emission was also detected apparently due to the presence of zinc oxide. The distorted symmetry of the dysprosium coordination environment, also confirmed by X-ray photoelectron spectroscopy analysis, was modified after the intercalation with phenyl phosphonate (PP, aspartate (Asp, adipate (Adip, and serinate (Ser anions; the emission as measured from PL spectra of these LDH was more intense in the blue region (ca. 486 nm, thus indicating an increase in symmetry of dysprosium octahedrons. The red emission band from zinc oxide kept the same intensity after intercalation of dodecyl sulfate (DDS. An additional emission of unknown origin at λ = 767 nm was present in all LDHs.

  11. Cation ordering and superstructures in natural layered double hydroxides.

    Science.gov (United States)

    Krivovichev, Sergey V; Yakovenchuk, Victor N; Zolotarev, Andrey A; Ivanyuk, Gregory N; Pakhomovsky, Yakov A

    2010-01-01

    Layered double hydroxides (LDHs) constitute an important group of materials with many applications ranging from catalysis and absorption to carriers for drug delivery, DNA intercalation and carbon dioxide sequestration. The structures of LDHs are based upon double brucite-like hydroxide layers [M(2+)(n)M(3+)(m)(OH)(2(m+n)](m+), where M(2+) = Mg(2+), Fe(2+), Mn(2+), Zn(2+), etc.; M(3+) = Al(3+), Fe(3+), Cr(3+), Mn(3+), etc. Structural features of LDHs such as cation ordering, charge distribution and polytypism have an immediate influence upon their properties. However, all the structural studies on synthetic LDHs deal with powder samples that prevent elucidation of such fine details of structure architecture as formation of superstructures due to cation ordering. In contrast to synthetic materials, natural LDHs are known to form single crystals accessible to single-crystal X-ray diffraction analysis, which provides a unique possibility to investigate 3D cation ordering in LDHs that results in formation of complex superstructures, where 2D cation order is combined with a specific order of layer stacking (polytypism). Therefore LDH minerals provide an indispensable source of structural information for modeling of structures and processes happening in LDHs at the molecular and nanoscale levels.

  12. Double layer dynamics in a collisionless magnetoplasma

    DEFF Research Database (Denmark)

    Iizuka, S.; Michelsen, Poul; Juul Rasmussen, Jens

    1985-01-01

    Investigations of double layer dynamics are performed in a Q-machine plasma by applying a positive step potential to a cold end-plate collector. The double layer created at the grounded plasma source just after the pulse is applied propagates towards the collector with the plasma flow speed. Large...... oscillations occur in the plasma current which is related to a recurring formation and propagation of the double layer. The current is limited during the propagation by a growing negative potential dip formed on the low-potential tail. Similar phenomena appear on the low-potential tail of the stationary double...... layer formed by applying a potential difference between two plasma sources...

  13. Double Layer Dynamics in a Collisionless Magnetoplasma

    DEFF Research Database (Denmark)

    Iizuka, S.; Michelsen, Poul; Juul Rasmussen, Jens

    An experimental investigation of the dynamics of double layers is presented. The experiments are performed in a Q-machine plasma and the double layers are generated by applying a positive step potential to a cold collector plate terminating the plasma column. The double layer is created...... at the grounded plasma source just after the pulse is applied and it propagates towards the collector with a speed around the ion acoustic speed. When the collector is biased positively, large oscillations are obserced in the plasma current. These oscillations are found to be related to a recurring formation...... difference is applied between two plasmas in a Q-machine with two sources. In this case a stationary double layer forms in the plasma column, but the low potential tail is subject to "back and forth" oscillations leading to large amplitude current oscillations....

  14. Organo-layered double hydroxides composite thin films deposited by laser techniques

    Energy Technology Data Exchange (ETDEWEB)

    Birjega, R. [National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Str., 77125 Bucharest-Magurele (Romania); Vlad, A., E-mail: angela.vlad@gmail.com [National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Str., 77125 Bucharest-Magurele (Romania); Matei, A.; Dumitru, M.; Stokker-Cheregi, F.; Dinescu, M. [National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Str., 77125 Bucharest-Magurele (Romania); Zavoianu, R. [University of Bucharest, Faculty of Chemistry, Department of Chemical Technology and Catalysis, 4-12 Regina Elisabeta Bd., Bucharest 030018 (Romania); Raditoiu, V.; Corobea, M.C. [National R.& D. Institute for Chemistry and Petrochemistry, ICECHIM, 202 Splaiul Independentei Str., CP-35-274, 060021 Bucharest (Romania)

    2016-06-30

    Highlights: • PLD and MAPLE was successfully used to produce organo-layered double hydroxides. • The organic anions (dodecyl sulfate-DS) were intercalated in co-precipitation step. • Zn2.5Al-LDH (Zn/Al = 2.5) and Zn2.5Al-DS thin films obtained in this work could be suitable for further applications as hydrophobic surfaces. - Abstract: We used laser techniques to create hydrophobic thin films of layered double hydroxides (LDHs) and organo-modified LDHs. A LDH based on Zn-Al with Zn{sup 2+}/Al{sup 3+} ratio of 2.5 was used as host material, while dodecyl sulfate (DS), which is an organic surfactant, acted as guest material. Pulsed laser deposition (PLD) and matrix assisted pulsed laser evaporation (MAPLE) were employed for the growth of the films. The organic anions were intercalated in co-precipitation step. The powders were subsequently used either as materials for MAPLE, or they were pressed and used as targets for PLD. The surface topography of the thin films was investigated by atomic force microscopy (AFM), the crystallographic structure of the powders and films was checked by X-ray diffraction. FTIR spectroscopy was used to evidence DS interlayer intercalation, both for powders and the derived films. Contact angle measurements were performed in order to establish the wettability properties of the as-prepared thin films, in view of functionalization applications as hydrophobic surfaces, owing to the effect of DS intercalation.

  15. Insights into the Synthesis of Layered Double Hydroxide (LDH) Nanoparticles: Part 2. Formation Mechanisms of LDH

    OpenAIRE

    Sun, Xiaodi; Dey, Sandwip K.

    2015-01-01

    This study demonstrates the effect of (co)intercalated anion compositions on nanostructure evolution to understand the formation mechanisms of layered double hydroxide (LDH) nanoparticles following coprecipitation and hydrothermal treatments (HT). Initially, the room temperature coprecipitation resulted in amorphous primary nanoparticles that agglomerated at the edges due to low surface charge densities. The reversibility of such agglomeration was determined by the crystalline quality upon HT...

  16. Synthesis and Characteristics of Valeric Acid-Zinc Layered Hydroxide Intercalation Material for Insect Pheromone Controlled Release Formulation

    Directory of Open Access Journals (Sweden)

    Rozita Ahmad

    2016-01-01

    Full Text Available A new intercalation compound of insect pheromone, valeric acid (VA, based on zinc layered hydroxide (ZLH as host release material, was successfully prepared through coprecipitation method. The as-produced organic-inorganic nanolayered material, valerate nanohybrid, VAN, shows the formation of a new peak at lower 2θ angle with basal spacing of 19.8 Å with no ZnO reflections, which indicate that the intercalation of anion between the inorganic ZLH interlamellae was accomplished. The elemental, FTIR, and ATR analyses of the nanohybrid supported the fact that the intercalation with the percentage anion loading was calculated to be 23.0% (w/w. The thermal stability property of the resulting nanohybrid was enhanced compared to the unbound anion. Field emission scanning electron micrograph of the ZnO has a nonuniform granular structure but transforms into flake-like structure with various sizes after the intercalation process. Release kinetics of anion from the interlayer of intercalated compound exhibited a slow release behavior governed by the pseudo-second-order kinetic model at different pHs of aqueous media. The valerate anion was released from VAN with the highest release rate at pH 4. These findings provide the basis to further development of controlled release formulation for insect pheromone based on ZLH intercalation.

  17. Three step double layers in the laboratory. [plasma physics

    Science.gov (United States)

    Bailey, Andrew, III; Hershkowitz, Noah

    1988-01-01

    A new class of stationary double layer structure, with three or more distinct steps, is demonstrated in the laboratory. A large monotonic potential increase results from a series of smaller double layers. In many respects, these double layer structures resemble those inferred from satellite measurements of auroral double layers. This new class of double layer appears to depend on turbulence for its existence and to be a hybrid structure, intermediate between anomalous resistivity and BGK double layers.

  18. Sensitive elements of pressure transducers made of layered intercalated InSe, GaSe, and Bi2Te3 crystals

    Science.gov (United States)

    Kudrynskyi, Z. R.; Kovalyuk, Z. D.

    2013-12-01

    It is shown that layered InSe, GaSe, and Bi2Te3 semiconductors are promising for sensitive elements of pressure transducers. Two ways for measuring pressure with layered crystals are suggested: from the pressure dependence of the intercalation parameter (current) and from the pressure dependence of the intercalate electromotive force.

  19. Intercalated water layers promote thermal dissipation at bio-nano interfaces

    Science.gov (United States)

    Wang, Yanlei; Qin, Zhao; Buehler, Markus J.; Xu, Zhiping

    2016-09-01

    The increasing interest in developing nanodevices for biophysical and biomedical applications results in concerns about thermal management at interfaces between tissues and electronic devices. However, there is neither sufficient knowledge nor suitable tools for the characterization of thermal properties at interfaces between materials of contrasting mechanics, which are essential for design with reliability. Here we use computational simulations to quantify thermal transfer across the cell membrane-graphene interface. We find that the intercalated water displays a layered order below a critical value of ~1 nm nanoconfinement, mediating the interfacial thermal coupling, and efficiently enhancing the thermal dissipation. We thereafter develop an analytical model to evaluate the critical value for power generation in graphene before significant heat is accumulated to disturb living tissues. These findings may provide a basis for the rational design of wearable and implantable nanodevices in biosensing and thermotherapic treatments where thermal dissipation and transport processes are crucial.

  20. Synthesis of layered double hydroxides from eggshells

    Energy Technology Data Exchange (ETDEWEB)

    Li Songnan [Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, 150001 (China); Wang Fangyong [College of Engineering and Technology, Northeast Forestry University, 150001 (China); Jing Xiaoyan [Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, 150001 (China); Wang Jun, E-mail: zhqw1888@sohu.com [Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, 150001 (China); Saba, Jamil; Liu Qi; Ge Lan; Song Dalei; Zhang Milin [Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, 150001 (China)

    2012-01-16

    Graphical abstract: This is the XRD pattern and TEM image of 4Ca-Al layered double hydroxide, which is obtained from eggshells. It can be seen that the sample is of layered double hydroxide and shows the plate-like agglomerations with an average size of 20-100 nm. Highlights: Black-Right-Pointing-Pointer We synthesize layered double hydroxides from eggshells. Black-Right-Pointing-Pointer Eggshells are the mainly material in this method. Black-Right-Pointing-Pointer The additional alkaline solution is not required. - Abstract: Ca-Al and Ca-Fe layered double hydroxides (LDHs) were successfully synthesized from chicken eggshells by an ultrasonic wave assistant method. The products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FT-IR) techniques. XRD and TEM analyses showed that the 4Ca-Al LDHs were of high purity but other samples were not. The present study provides a simple, efficient and environmental friendly method to obtain LDHs from biowaste eggshells, in which additional alkaline solution is not required for synthesis. Moreover, eggshells provide all the requisite bivalent metal ions, which are needed to form layered double hydroxides.

  1. Use of layered double hydroxides and their derivatives as adsorbents for inorganic and organic pollutants

    Science.gov (United States)

    You, Youwen

    Contamination of surface and groundwaters by hazardous inorganic and organic pollutants has become an increasing threat to the safety of drinking waters. Cleanup of contaminated surface and groundwaters has, therefore, become a major focus of environmental research. Primary objectives of this dissertation study were to examine the adsorption properties of layered double hydroxides (LDHs) and their derivatives for inorganic and organic contaminants and to identify potential technologies that utilize LDHs and their derivatives for environment remediation. Studies examined the adsorption characteristics of anionic selenium, arsenic and dicamba (3,6 dichloro-2-methoxy benzoic acid) on original LDHs and calcined-LDHs. Adsorption of selenium and arsenic on LDHs was a function of pH. Competing anions in solution strongly affected adsorption of all three contaminants, with divalent anions decreasing adsorption more intensely than monovalent anions. Adsorbed selenium, arsenic and dicamba could be released from LDHs in anion solutions. Adsorption isotherms for selenium and arsenic retention could be fitted to a simple Langmuir equation. Calcination processes significantly increased adsorption capacities of LDHs. Because of adsorption-desorpion characteristics, LDHs could be recycled. X-ray diffraction patterns revealed an increase of d-spacing coupling with adsorption of contaminants, verifying the intercalation of contaminants into layer structure of LDHs. Long chain anionic surfactants intercalated into LDHs modified their surface properties, resulting in organo-LDHs with hydrophobic surface properties. Various organo-LDHs were developed by incorporating different surfactants into LDHs via different synthesis methods. Surfactant intercalation properties were examined and the geometrical arrangements of the intercalated surfactants were characterized. Results revealed that surfactant molecules could adopt various configurations within the LDH interlayer space. Intercalation

  2. Mg–Al layered double hydroxide–methotrexate nanohybrid drug delivery system: Evaluation of efficacy

    Energy Technology Data Exchange (ETDEWEB)

    Chakraborty, Jui [Central Glass and Ceramic Research Institute, CSIR, 196 Raja S.C. Mullick Road, Kolkata-700032 (India); Roychowdhury, Susanta [Indian Institute of Chemical Biology, CSIR, Kolkata-700032 (India); Sengupta, Somoshree [Central Glass and Ceramic Research Institute, CSIR, 196 Raja S.C. Mullick Road, Kolkata-700032 (India); Ghosh, Swapankumar, E-mail: swapankumar.ghosh2@mail.dcu.ie [Central Glass and Ceramic Research Institute, CSIR, 196 Raja S.C. Mullick Road, Kolkata-700032 (India)

    2013-05-01

    Mg–Al layered double hydroxide nanoparticles were synthesized by one-pot co-precipitation method and anticancerous drug methotrexate was incorporated into it by in-situ ion exchange. The LDH–MTX nanohybrid produced moderately stable suspension in water, as predicted by zeta potential measurement. X-ray diffraction revealed that the basal spacing increased to nearly twice the same for pristine LDH on MTX intercalation. Thermogravimetric analyses confirmed an increase in thermal stability of the intercalated drug in the LDH framework. A striking enhancement in efficacy/sensitivity of MTX on the HCT-116 cells was obtained when intercalated within the LDH layers, as revealed by the attainment of half maximal inhibitory concentration of LDH–MTX nanohybrid by 48 h, whereas, bare MTX required 72 h for the same. The MTX release from MgAl-LDH–MTX hybrids in phosphate buffer saline at pH 7.4 followed a relatively slow, first order kinetics and was complete within 8 days following diffusion and crystal dissolution mechanism. Highlights: ► MgAl-LDH–methotrexate nanohybrid synthesized by one-pot synthetic strategy ► IC{sub 50} for LDH–MTX indicates the efficacy of nanohybrid as an efficient drug carrier. ► XRD and TEM study on nanohybrid revealed successful intercalation of methotrexate. ► TG analyses showed ∼ 13.1 wt.% of methotrexate loading into the nanohybrid.

  3. Synthesis and Characterization of Layered Double Hydroxides Containing Optically Active Transition Metal Ion

    Science.gov (United States)

    Tyagi, S. B.; Kharkwal, Aneeta; Nitu; Kharkwal, Mamta; Sharma, Raghunandan

    2017-01-01

    The acetate intercalated layered double hydroxides of Zn and Mn, have been synthesized by chimie douce method. The materials were characterized by XRD, TGA, CHN, IR, XPS, SEM-EDX and UV-visible spectroscopy. The photoluminescence properties was also studied. The optical properties of layered hydroxides are active transition metal ion dependent, particularly d1-10 system plays an important role. Simultaneously the role of host - guest orientation has been considered the basis of photoluminescence. Acetate ion can be exchanged with iodide and sulphate ions. The decomposed product resulted the pure phase Mn doped zinc oxide are also reported.

  4. EFFECT OF AMPHIPHILIC POLY (STYRENE-B-ETHYLENE OXIDE) DIBLOCK COPOLYMER INTERCALATED LAYERED SILICATE AS FILLER ON ACRYLONITRILE-BUTADIENE-STYRENE RESIN

    Institute of Scientific and Technical Information of China (English)

    Guo Tianying; Zhang Jie; Hao Guangjie; Song Moudao; Zhang Banghua

    2003-01-01

    The diblock copolymers intercalated layered silicate was prepared via a melt dispersion technique. Then the effect of intercalated hybrid as filler on acrylonitrile- butadiene-styrene resin was characterized by X-ray diffraction, transmission electron microscopy, stress-strain measurements in elongation.

  5. Small molecule intercalation with double stranded DNA: implications for normal gene regulation and for predicting the biological efficacy and genotoxicity of drugs and other chemicals.

    Science.gov (United States)

    Hendry, Lawrence B; Mahesh, Virendra B; Bransome, Edwin D; Ewing, Douglas E

    2007-10-01

    The binding of small molecules to double stranded DNA including intercalation between base pairs has been a topic of research for over 40 years. For the most part, however, intercalation has been of marginal interest given the prevailing notion that binding of small molecules to protein receptors is largely responsible for governing biological function. This picture is now changing with the discovery of nuclear enzymes, e.g. topoisomerases that modulate intercalation of various compounds including certain antitumor drugs and genotoxins. While intercalators are classically flat, aromatic structures that can easily insert between base pairs, our laboratories reported in 1977 that a number of biologically active compounds with greater molecular thickness, e.g. steroid hormones, could fit stereospecifically between base pairs. The hypothesis was advanced that intercalation was a salient feature of the action of gene regulatory molecules. Two parallel lines of research were pursued: (1) development of technology to employ intercalation in the design of safe and effective chemicals, e.g. pharmaceuticals, nutraceuticals, agricultural chemicals; (2) exploration of intercalation in the mode of action of nuclear receptor proteins. Computer modeling demonstrated that degree of fit of certain small molecules into DNA intercalation sites correlated with degree of biological activity but not with strength of receptor binding. These findings led to computational tools including pharmacophores and search engines to design new drug candidates by predicting desirable and undesirable activities. The specific sequences in DNA into which ligands best intercalated were later found in the consensus sequences of genes activated by nuclear receptors implying intercalation was central to their mode of action. Recently, the orientation of ligands bound to nuclear receptors was found to match closely the spatial locations of ligands derived from intercalation into unwound gene sequences

  6. Small molecule intercalation with double stranded DNA: Implications for normal gene regulation and for predicting the biological efficacy and genotoxicity of drugs and other chemicals

    Energy Technology Data Exchange (ETDEWEB)

    Hendry, Lawrence B. [Accelerated Pharmaceuticals Inc., Augusta, GA (United States)], E-mail: lhendry@comcast.net; Mahesh, Virendra B.; Bransome, Edwin D.; Ewing, Douglas E. [Accelerated Pharmaceuticals Inc., Augusta, GA (United States)

    2007-10-01

    The binding of small molecules to double stranded DNA including intercalation between base pairs has been a topic of research for over 40 years. For the most part, however, intercalation has been of marginal interest given the prevailing notion that binding of small molecules to protein receptors is largely responsible for governing biological function. This picture is now changing with the discovery of nuclear enzymes, e.g. topoisomerases that modulate intercalation of various compounds including certain antitumor drugs and genotoxins. While intercalators are classically flat, aromatic structures that can easily insert between base pairs, our laboratories reported in 1977 that a number of biologically active compounds with greater molecular thickness, e.g. steroid hormones, could fit stereospecifically between base pairs. The hypothesis was advanced that intercalation was a salient feature of the action of gene regulatory molecules. Two parallel lines of research were pursued: (1) development of technology to employ intercalation in the design of safe and effective chemicals, e.g. pharmaceuticals, nutraceuticals, agricultural chemicals; (2) exploration of intercalation in the mode of action of nuclear receptor proteins. Computer modeling demonstrated that degree of fit of certain small molecules into DNA intercalation sites correlated with degree of biological activity but not with strength of receptor binding. These findings led to computational tools including pharmacophores and search engines to design new drug candidates by predicting desirable and undesirable activities. The specific sequences in DNA into which ligands best intercalated were later found in the consensus sequences of genes activated by nuclear receptors implying intercalation was central to their mode of action. Recently, the orientation of ligands bound to nuclear receptors was found to match closely the spatial locations of ligands derived from intercalation into unwound gene sequences

  7. Intercalation and adsorption of ciprofloxacin by layered chalcogenides and kinetics study.

    Science.gov (United States)

    Li, Jian-Rong; Wang, Yun-Xia; Wang, Xu; Yuan, Baoling; Fu, Ming-Lai

    2015-09-01

    The hydrothermally synthesized layered chalcogenide, K(2x)Mn(x)Sn(3-x)S6 (x=0.5-0.95) (KMS-1), was applied to remove ciprofloxacin from aqueous solution. Kinetic data showed the removal reaction followed a pseudo-second-order kinetic model and the rate controlling step was both through external film and intraparticle diffusion. The adsorption of CIP by KMS-1 is endothermic and the maximum adsorption capacity of KMS-1 was 199.6, 230.9 and 269.5 mg/g at temperature of 10, 25 and 40°C, respectively. The heavy metal ions had great effect on the removal efficiency of CIP and the degree of inhibition followed the order: Pb(2+)>Zn(2+)>Cd(2+)>Ni(2+). The shift of Bragg peaks from XRD at various pH accompanying CIP removal and FE-SEM images confirmed that cation exchange is the major mechanism for the adsorption of CIP by KMS-1. In the pH range of 4.0-7.0, the intercalation of cationic CIP adopted a titled orientation of di-molecular CIP in KMS-1 with the titling angle of 68° and 42°, respectively. A vertical arrangement of the zwitterionic CIP adsorbed on the surface of KMS-1 was also confirmed. These results suggested that KMS-1 is an effective adsorbent to remove CIP from water. Copyright © 2015 Elsevier Inc. All rights reserved.

  8. Synthesis and characterization of 10-hydroxycamptothecin - sebacate - layered double hydroxide nanocomposites

    Science.gov (United States)

    Pang, Xiujiang; Ma, Xiuming; Li, Dongxiang; Hou, Wanguo

    2013-02-01

    10-Hydroxycamptothecin (HCPT) as a hydrophobic anticancer drug brings many challenges in the clinical applications due to its poor water solubility and the presence of a chemically unstable lactone ring. In this work, the nanocomposites of HCPT intercalated layered double hydroxide (LDH) were prepared by a secondary intercalation method, and the encapsulated HCPT could keep the biologically active lactone form. A Zn-Al-NO3 LDH was pillared with sebacate anions by a co-precipitation method in an aqueous medium, and then HCPT was intercalated into the LDH's gallery via hydrophobic interaction in an ethanol medium. The parallel alkyl chains of perpendicularly arranged sebacate anions in the LDH gallery provide a hydrophobic space for the drug intercalation. The in vitro release kinetics of HCPT from the nanocomposites could be fitted with the pseudo-second-order kinetic model, and the diffusion of HCPT through the LDH particles played an important role in controlling the drug release. The nanocomposites can be considered as a potential drug delivery system.

  9. Double layered tailorable advanced blanket insulation

    Science.gov (United States)

    Falstrup, D.

    1983-01-01

    An advanced flexible reusable surface insulation material for future space shuttle flights was investigated. A conventional fly shuttle loom with special modifications to weave an integral double layer triangular core fabric from quartz yarn was used. Two types of insulating material were inserted into the cells of the fabric, and a procedure to accomplish this was developed. The program is follow up of a program in which single layer rectangular cell core fabrics are woven and a single type of insulating material was inserted into the cells.

  10. Reversible Heating in Electric Double Layer Capacitors.

    Science.gov (United States)

    Janssen, Mathijs; van Roij, René

    2017-03-03

    A detailed comparison is made between different viewpoints on reversible heating in electric double layer capacitors. We show in the limit of slow charging that a combined Poisson-Nernst-Planck and heat equation, first studied by d'Entremont and Pilon [J. Power Sources 246, 887 (2014)JPSODZ0378-775310.1016/j.jpowsour.2013.08.024], recovers the temperature changes as predicted by the thermodynamic identity of Janssen et al. [Phys. Rev. Lett. 113, 268501 (2014)PRLTAO0031-900710.1103/PhysRevLett.113.268501], and disagrees with the approximative model of Schiffer et al. [J. Power Sources 160, 765 (2006)JPSODZ0378-775310.1016/j.jpowsour.2005.12.070] that predominates the literature. The thermal response to the adiabatic charging of supercapacitors contains information on electric double layer formation that has remained largely unexplored.

  11. Synthesis, characterization, and efficacy of antituberculosis isoniazid zinc aluminum-layered double hydroxide based nanocomposites.

    Science.gov (United States)

    Saifullah, Bullo; El Zowalaty, Mohamed Ezzat; Arulselvan, Palanisamy; Fakurazi, Sharida; Webster, Thomas J; Geilich, Benjamin Mahler; Hussein, Mohd Zobir

    2016-01-01

    The chemotherapy for tuberculosis (TB) is complicated by its long-term treatment, its frequent drug dosing, and the adverse effects of anti-TB drugs. In this study, we have developed two nanocomposites (A and B) by intercalating the anti-TB drug isoniazid (INH) into Zn/Al-layered double hydroxides. The average size of the nanocomposites was found to bê164 nm. The efficacy of the Zn/Al-layered double hydroxides intercalated INH against Mycobacterium tuberculosis was increased by approximately three times more than free INH. The nanocomposites were also found to be active against Gram-positive and -negative bacteria. Compared to the free INH, the nanodelivery formulation was determined to be three times more biocompatible with human normal lung fibroblast MRC-5 cells and 3T3 fibroblast cells at a very high concentration of 50 µg/mL for up to 72 hours. The in vitro release of INH from the Zn/Al-layered double hydroxides was found to be sustained in human body-simulated buffer solutions of pH 4.8 and 7.4. This research is a step forward in making the TB chemotherapy patient friendly.

  12. Double layers and double wells in arbitrary degenerate plasmas

    Science.gov (United States)

    Akbari-Moghanjoughi, M.

    2016-06-01

    Using the generalized hydrodynamic model, the possibility of variety of large amplitude nonlinear excitations is examined in electron-ion plasma with arbitrary electron degeneracy considering also the ion temperature effect. A new energy-density relation is proposed for plasmas with arbitrary electron degeneracy which reduces to the classical Boltzmann and quantum Thomas-Fermi counterparts in the extreme limits. The pseudopotential method is employed to find the criteria for existence of nonlinear structures such as solitons, periodic nonlinear structures, and double-layers for different cases of adiabatic and isothermal ion fluids for a whole range of normalized electron chemical potential, η0, ranging from dilute classical to completely degenerate electron fluids. It is observed that there is a Mach-speed gap in which no large amplitude localized or periodic nonlinear excitations can propagate in the plasma under consideration. It is further revealed that the plasma under investigation supports propagation of double-wells and double-layers the chemical potential and Mach number ranges of which are studied in terms of other plasma parameters. The Mach number criteria for nonlinear waves are shown to significantly differ for cases of classical with η0 0 regimes. It is also shown that the localized structure propagation criteria possess significant dissimilarities for plasmas with adiabatic and isothermal ions. Current research may be generalized to study the nonlinear structures in plasma containing positrons, multiple ions with different charge states, and charged dust grains.

  13. Layered Double Hydroxide as a Vehicle to Increase Toxicity of Gallate Ions against Adenocarcinoma Cells

    Directory of Open Access Journals (Sweden)

    Jenny Arratia-Quijada

    2016-07-01

    Full Text Available The antineoplasic activity of gallic acid has been reported. This compound induces apoptosis and inhibits the growth of several neoplasic cells. However, this molecule is easily oxidized and degraded in the body. The aim of this work was to intercalate gallate ions into layered double hydroxide (LDH nanoparticles under controlled conditions to reduce oxidation of gallate and to evaluate its toxicity against the A549 adenocarcinoma cell line. An isopropanol medium under nitrogen atmosphere was adequate to intercalate gallate ions with a lesser oxidation degree as detected by electron spin resonance spectroscopy. Concentrations of the hybrid LDH-gallate nanoparticles between 0.39 and 25 µg/mL reduced the cell viability to 67%, while the value reached with the pure gallic acid and LDH was 90% and 78%, respectively, thus proving that the combination of gallate ions with the inorganic nanoparticles increases the toxicity potential within this dose range.

  14. In situ optical measurement of the rapid Li intercalation and deintercalation dynamics in colloidal 2D layered TiS2 nanodiscs

    Science.gov (United States)

    Ren, Jiageng; Camacho-Forero, Luis E.; Rossi, Daniel; Park, Yerok; Balbuena, Perla B.; Son, Dong Hee

    2016-05-01

    We report the in situ optical measurements of the rapid Li intercalation and deintercalation dynamics in 2-dimensional (2D) layered transition metal dichalcogenide (TMD) with a nanoscale lateral dimension using thin films fabricated with size-controlled colloidal TiS2 nanodiscs. The films exhibiting high optical homogeneity, where the interband absorption changes near-linearly to the amount of intercalated Li, enabled facile optical probing of the intercalation dynamics overcoming the shortcomings of amperometry susceptible to complications from non-Faradaic processes. The time scale of Li intercalation and deintercalation was on the order of seconds in the nanodiscs of ~100 nm lateral dimension, indicating sufficiently rapid dynamic control of the intercalation-induced material properties with a reduced lateral dimension. The change in the rate and reversibility of the dynamics during the multiple intercalation/deintercalation cycles was also measured, providing a unique window to observe the effect of potential structural changes on the intercalation and deintercalation dynamics in 2D layered TMD structures with a nanoscale lateral dimension.We report the in situ optical measurements of the rapid Li intercalation and deintercalation dynamics in 2-dimensional (2D) layered transition metal dichalcogenide (TMD) with a nanoscale lateral dimension using thin films fabricated with size-controlled colloidal TiS2 nanodiscs. The films exhibiting high optical homogeneity, where the interband absorption changes near-linearly to the amount of intercalated Li, enabled facile optical probing of the intercalation dynamics overcoming the shortcomings of amperometry susceptible to complications from non-Faradaic processes. The time scale of Li intercalation and deintercalation was on the order of seconds in the nanodiscs of ~100 nm lateral dimension, indicating sufficiently rapid dynamic control of the intercalation-induced material properties with a reduced lateral dimension

  15. Fast charging self-powered electric double layer capacitor

    Science.gov (United States)

    Parida, Kaushik; Bhavanasi, Venkateswarlu; Kumar, Vipin; Wang, Jiangxin; Lee, Pooi See

    2017-02-01

    Self-powered electrochemical energy storage devices, which store energy upon application of mechanical force, have emerged as a promising technology for the realization of autonomous systems for maintenance-free, independent and multifunctional operations. However, the existing state-of-the-art technology demonstrates slow self-charging due to slow Faradaic reactions and intercalation mechanism. Here, we report a fast self-charging, self-powered electrochemical energy storage device owing to the formation of an electric double layer with fast adsorption and desorption of ions at the carbon nanotube (CNT) electrode upon application of mechanical force. The device charges up to 70 mV from the open-circuit potential, storing a capacitance of 95 μFcm-2 upon application of a mechanical pressure of 70 N at a frequency of 5 Hz. More importantly, it takes less than 10 s to achieve 90% of the increment in the potential (60 mV), which is more than one order of magnitude faster than all of the previously reported self-powered energy storage devices.

  16. Controlled supramolecular structure of guanosine monophosphate in the interlayer space of layered double hydroxide

    Directory of Open Access Journals (Sweden)

    Gyeong-Hyeon Gwak

    2016-12-01

    Full Text Available Guanosine monophosphates (GMPs were intercalated into the interlayer space of layered double hydroxides (LDHs and the molecular arrangement of GMP was controlled in LDHs. The intercalation conditions such as GMP/LDH molar ratio and reaction temperature were systematically adjusted. When the GMP/LDH molar ratio was 1:2, which corresponds to the charge balance between positive LDH sheets and GMP anions, GMP molecules were well-intercalated to LDH. At high temperature (100 and 80 °C, a single GMP molecule existed separately in the LDH interlayer. On the other hand, at lower temperature (20, 40 and 60 °C, GMPs tended to form ribbon-type supramolecular assemblies. Differential scanning calorimetry showed that the ribbon-type GMP assembly had an intermolecular interaction energy of ≈101 kJ/mol, which corresponds to a double hydrogen bond between guanosine molecules. Once stabilized, the interlayer GMP orientations, single molecular and ribbon phase, were successfully converted to the other phase by adjusting the external environment by stoichiometry or temperature control.

  17. Powder, paper and foam of few-layer graphene prepared in high yield by electrochemical intercalation exfoliation of expanded graphite.

    Science.gov (United States)

    Wu, Liqiong; Li, Weiwei; Li, Peng; Liao, Shutian; Qiu, Shengqiang; Chen, Mingliang; Guo, Yufen; Li, Qi; Zhu, Chao; Liu, Liwei

    2014-04-09

    A facile and high-yield approach to the preparation of few-layer graphene (FLG) by electrochemical intercalation exfoliation (EIE) of expanded graphite in sulfuric acid electrolyte is reported. Stage-1 H2SO4-graphite intercalation compound is used as a key intermediate in EIE to realize the efficient exfoliation. The yield of the FLG sheets (graphene structures. Flexible and freestanding graphene papers made of the FLG flakes retain excellent conductivity (≈24,500 S m(-1)). Three-dimensional (3D) graphene foams with light weight are fabricated from the FLG flakes by the use of Ni foams as self-sacrifice templates. Furthermore, 3D graphene/Ni foams without any binders, which are used as supercapacitor electrodes in aqueous electrolyte, provide the specific capacitance of 113.2 F g(-1) at a current density of 0.5 A g(-1), retaining 90% capacitance after 1000 cycles.

  18. Control of crystallite and particle size in the synthesis of layered double hydroxides: Macromolecular insights and a complementary modeling tool.

    Science.gov (United States)

    Galvão, Tiago L P; Neves, Cristina S; Caetano, Ana P F; Maia, Frederico; Mata, Diogo; Malheiro, Eliana; Ferreira, Maria J; Bastos, Alexandre C; Salak, Andrei N; Gomes, José R B; Tedim, João; Ferreira, Mário G S

    2016-04-15

    Zinc-aluminum layered double hydroxides with nitrate intercalated (Zn(n)Al-NO3, n=Zn/Al) is an intermediate material for the intercalation of different functional molecules used in a wide range of industrial applications. The synthesis of Zn(2)Al-NO3 was investigated considering the time and temperature of hydrothermal treatment. By examining the crystallite size in two different directions, hydrodynamic particle size, morphology, crystal structure and chemical species in solution, it was possible to understand the crystallization and dissolution processes involved in the mechanisms of crystallite and particle growth. In addition, hydrogeochemical modeling rendered insights on the speciation of different metal cations in solution. Therefore, this tool can be a promising solution to model and optimize the synthesis of layered double hydroxide-based materials for industrial applications.

  19. Mg-Al layered double hydroxide-methotrexate nanohybrid drug delivery system: evaluation of efficacy.

    Science.gov (United States)

    Chakraborty, Jui; Roychowdhury, Susanta; Sengupta, Somoshree; Ghosh, Swapankumar

    2013-05-01

    Mg-Al layered double hydroxide nanoparticles were synthesized by one-pot co-precipitation method and anticancerous drug methotrexate was incorporated into it by in-situ ion exchange. The LDH-MTX nanohybrid produced moderately stable suspension in water, as predicted by zeta potential measurement. X-ray diffraction revealed that the basal spacing increased to nearly twice the same for pristine LDH on MTX intercalation. Thermogravimetric analyses confirmed an increase in thermal stability of the intercalated drug in the LDH framework. A striking enhancement in efficacy/sensitivity of MTX on the HCT-116 cells was obtained when intercalated within the LDH layers, as revealed by the attainment of half maximal inhibitory concentration of LDH-MTX nanohybrid by 48 h, whereas, bare MTX required 72 h for the same. The MTX release from MgAl-LDH-MTX hybrids in phosphate buffer saline at pH7.4 followed a relatively slow, first order kinetics and was complete within 8 days following diffusion and crystal dissolution mechanism.

  20. Intercalation-induced phases in layer compounds of the A /SUP III/ B /SUP VI/ -type

    Energy Technology Data Exchange (ETDEWEB)

    Kovalyuk, Z.D.; Pyrlya, M.N.; Seredyuk, A.I.; Tovstyuk, K.D.

    1986-03-01

    The authors investigate the kinetics of combined electrochemical intercalation and the physicochemical properties of the introduced phases. InSe and GaSe single crystals were used in the experiments; the crystals were grown by the Bridgman method. The authors determined the concentration dependences of the electrode potentials and electrical conductivity of the compounds InSe and GaSe intercalated with lithium and lead. The results of the measurements are presented. Lithium and lead enter into the matrix of the crystals in a nonconducting state.

  1. Nanohybrids of Mg/Al layered double hydroxide and long-chain (C18) unsaturated fatty acid anions: Structure and sorptive properties

    Science.gov (United States)

    Long-chain (C18) unsaturated fatty acid anions, elaidate (ELA), oleate (OLE), linoleate (LINO), and linolenate (LINOLEN), were intercalated into Mg/Al (3:1) layered double hydroxide (LDH) and the resultant organo-LDH nanohybrid materials were characterized and subsequently evaluated as sorbents of s...

  2. Room temperature oxidative intercalation with chalcogen hydrides: Two-step method for the formation of alkali-metal chalcogenide arrays within layered perovskites

    Energy Technology Data Exchange (ETDEWEB)

    Ranmohotti, K.G. Sanjaya; Montasserasadi, M. Dariush; Choi, Jonglak; Yao, Yuan; Mohanty, Debasish; Josepha, Elisha A.; Adireddy, Shiva; Caruntu, Gabriel [Department of Chemistry and the Advanced Materials Research Institute, University of New Orleans, New Orleans, LA 70148-2820 (United States); Wiley, John B., E-mail: jwiley@uno.edu [Department of Chemistry and the Advanced Materials Research Institute, University of New Orleans, New Orleans, LA 70148-2820 (United States)

    2012-06-15

    Highlights: ► Topochemical reactions involving intercalation allow construction of metal chalcogenide arrays within perovskite hosts. ► Gaseous chalcogen hydrides serve as effect reactants for intercalation of sulfur and selenium. ► New compounds prepared by a two-step intercalation strategy are presented. -- Abstract: A two-step topochemical reaction strategy utilizing oxidative intercalation with gaseous chalcogen hydrides is presented. Initially, the Dion-Jacobson-type layered perovskite, RbLaNb{sub 2}O{sub 7}, is intercalated reductively with rubidium metal to make the Ruddlesden-Popper-type layered perovskite, Rb{sub 2}LaNb{sub 2}O{sub 7}. This compound is then reacted at room-temperature with in situ generated H{sub 2}S gas to create Rb-S layers within the perovskite host. Rietveld refinement of X-ray powder diffraction data (tetragonal, a = 3.8998(2) Å, c = 15.256(1) Å; space group P4/mmm) shows the compound to be isostructural with (Rb{sub 2}Cl)LaNb{sub 2}O{sub 7} where the sulfide resides on a cubic interlayer site surrounded by rubidium ions. The mass increase seen on sulfur intercalation and the refined S site occupation factor (∼0.8) of the product indicate a higher sulfur content than expected for S{sup 2−} alone. This combined with the Raman studies, which show evidence for an H-S stretch, indicate that a significant fraction of the intercalated sulfide exists as hydrogen sulfide ion. Intercalation reactions with H{sub 2}Se{sub (g)} were also carried out and appear to produce an isostructural selenide compound. The utilization of such gaseous hydride reagents could significantly expand multistep topochemistry to a larger number of intercalants.

  3. Current-free double layers: A review

    Science.gov (United States)

    Singh, Nagendra

    2011-12-01

    During the last decade, there has been an upsurge in the research on current-free DLs (CFDLs). Research includes theory, laboratory measurements, and various applications of CFDLs ranging from plasma thrusters to acceleration of charged particles in space and astrophysical plasmas. The purpose of this review is to present a unified understanding of the basic plasma processes, which lead to the formation of CFDLs. The review starts with the discussion on early research on electric fields and double layers (DLs) and ion acceleration in planar plasma expansion. The review continues with the formation of DLs and rarefaction shocks (RFS) in expanding plasma with two electron populations with different temperatures. The basic theory mitigating the formation of a CFDL by two-electron temperature population is reviewed; we refer to such CFDLs as double layers structures formation by two-temperature electron populations (TET-CFDLs). Application of TET-CFDLS to ion acceleration in laboratory and space plasmas was discussed including the formation of stationary steady-state DLs. A quite different type of CFDLs forms in a helicon plasma device (HPD), in which plasma abruptly expands from a narrow plasma source tube into a wide diffusion tube with abruptly diverging magnetic fields. The formation mechanism of the CFDL in HPD, referred here as current free double layer structure in helicon plasma device (HPD-CFDL), and its applications are reviewed. The formation of a TET-CFDL is due to the self-consistent separation of the two electron populations parallel to the ambient magnetic field. In contrast, a HPD-CFDL forms due to self-consistent separation of electrons and ion perpendicular to the abruptly diverging magnetic field in conjunction with the conducting wall of the expansion chamber in the HPD. One-dimensional theoretical models of CFDLs based on steady-state solution of Vlasov-Poisson system of equations are briefly discussed. Applications of CFDLs ranging from helicon

  4. A new nanostructured material based on fluorophosphate incorporated into a zinc–aluminium layered double hydroxide by ion exchange

    Indian Academy of Sciences (India)

    EL HASSAN ELKHATTABI; MOHAMED LAKRAIMI; MOHA BERRAHO; AHMED LEGROURI; RADOUAN HAMMAL; LAYLA EL GAINI

    2017-08-01

    Layered double hydroxides (LDHs), also called anionic clays, consist of cationic brucite-like layers and exchangeable interlayer anions. These hydrotalcite-like compounds, with Zn and Al in the layers and chloride in the interlayer space, were prepared following the coprecipitation method at constant pH. The effect of pH, aging time and anion concentration on the intercalation of fluorophosphate (PO$_3$F$_2$−, FP) in the [Zn–Al] LDH was investigated. The best crystalline material, with high exchange extent, was obtained by carrying out the exchange at 25◦C in a 0.03 M FP solution at pH 7 with at least 42 h of aging time. A mechanism for the FP intercalation was confirmed by X-ray diffraction, infrared spectroscopy and thermogravimetry (TG) analyses (TG and DTG curves).

  5. The in vitro sustained release profile and antitumor effect of etoposide-layered double hydroxide nanohybrids

    Directory of Open Access Journals (Sweden)

    Qin LL

    2013-05-01

    Full Text Available Lili Qin,1 Mei Wang,2 Rongrong Zhu,3 Songhui You,1 Ping Zhou,1 Shilong Wang31Department of Physical Education, Tongji University, Shanghai, People's Republic of China; 2Department of Chemistry, Tongji University, Shanghai, People's Republic of China; 3School of Life Science and Technology, Tongji University, Shanghai, People's Republic of ChinaAbstract: Magnesium-aluminum layered double hydroxides intercalated with antitumor drug etoposide (VP16 were prepared for the first time using a two-step procedure. The X-ray powder diffraction data suggested the intercalation of VP16 into layers with the increased basal spacing from 0.84–1.18 nm was successful. Then, it was characterized by X-ray powder diffraction, Fourier transform infrared spectroscopy, thermogravimetry and differential thermal analysis, and transmission electron microscopy. The prepared nanoparticles, VP16-LDH, showed an average diameter of 62.5 nm with a zeta potential of 20.5 mV. Evaluation of the buffering effect of VP16-LDH indicated that the nanohybrids were ideal for administration of the drugs that treat human stomach irritation. The loading amount of intercalated VP16 was 21.94% and possessed a profile of sustained release. The mechanism of VP16-LDH release in the phosphate buffered saline solution at pH 7.4 is likely controlled by the diffusion of VP16 anions from inside to the surface of LDH particles. The in vitro cytotoxicity and antitumor assays indicated that VP16-LDH hybrids were less toxic to GES-1 cells while exhibiting better antitumor efficacy on MKN45 and SGC-7901 cells. These results imply that VP16-LDH is a potential antitumor drug for a broad range of gastric cancer therapeutic applications.Keywords: layered double hydroxides, etoposide, drug delivery, antitumor effect, sustained release

  6. Modular Polyoxometalate-Layered Double Hydroxide Composites as Efficient Oxidative Catalysts.

    Science.gov (United States)

    Chen, Yang; Yao, Zhixiao; Miras, Haralampos N; Song, Yu-Fei

    2015-07-20

    The exploitation of intercalation techniques in the field of two-dimensional layered materials offers unique opportunities for controlling chemical reactions in confined spaces and developing nanocomposites with desired functionality. In this study, the exploitation of the novel and facile "one-pot" anion-exchange method for the functionalization of layered double hydroxides (LDHs) is demonstrated. As a proof-of-concept, we demonstrate the intercalation of a series of polyoxometalate (POM) clusters, Na3[PW12O40]⋅15 H2O (Na3PW12), K6[P2W18O62]⋅14 H2O (K6P2W18), and Na9LaW10O36⋅32 H2O (Na9LaW10) into tris(hydroxymethyl)aminomethane (Tris)-modified layered double hydroxides (LDHs) under ambient conditions without the necessity of degassing CO2. Investigation of the resultant intercalated materials of Tris-LDHs-PW12 (1), Tris-LDH-P2W18 (2), and Tris-LDH-LaW10 (3) for the degradation of methylene blue (MB), rhodamine B (RB) and crystal violet (CV) has been carried out, where Tris-LDH-PW12 reveals the best performance in the presence of H2O2. Additionally, degradation of a mixture of RB, MB and CV by Tris-LDH-PW12 follows the order of CV>MB>RB, which is directly related to the designed accessible area of the interlayer space. Also, the composite can be readily recycled and reused at least ten cycles without measurable decrease of activity.

  7. Synthesis of protocatechuic acid–zinc/aluminium–layered double hydroxide nanocomposite as an anticancer nanodelivery system

    Energy Technology Data Exchange (ETDEWEB)

    Barahuie, Farahnaz [Materials Synthesis and Characterisation Laboratory, Institute of Advanced Technology (ITMA), Universiti Putra Malaysia, 43400 UPM, Serdang, Selangor (Malaysia); Hussein, Mohd Zobir, E-mail: mzobir@upm.edu.my [Materials Synthesis and Characterisation Laboratory, Institute of Advanced Technology (ITMA), Universiti Putra Malaysia, 43400 UPM, Serdang, Selangor (Malaysia); Gani, Shafinaz Abd [Department of Biochemistry, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400 UPM, Serdang, Selangor (Malaysia); Laboratory of Vaccines and Immunotherapeutics, Institute of Bioscience, Universiti Putra Malaysia, 43400 UPM, Serdang, Selangor (Malaysia); Fakurazi, Sharida [Laboratory of Vaccines and Immunotherapeutics, Institute of Bioscience, Universiti Putra Malaysia, 43400 UPM, Serdang, Selangor (Malaysia); Department of Human Anatomy, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400 UPM, Serdang, Selangor (Malaysia); Zainal, Zulkarnain [Materials Synthesis and Characterisation Laboratory, Institute of Advanced Technology (ITMA), Universiti Putra Malaysia, 43400 UPM, Serdang, Selangor (Malaysia)

    2015-01-15

    Protocatechuic acid, an active anticancer agent, has been intercalated into Zn/Al–layered double hydroxide at Zn/Al=2) using two different preparation methods, co-precipitation and ion-exchange, which are labelled as PZAE and PZAC, respectively. The release of protocatechuate from the nanocomposites occurred in a controlled manner and was fitted satisfactorily to pseudo-second order kinetics. The basal spacing of the resulting nanocomposites PZAE and PZAC was 10.2 and 11.0 Å, respectively, indicating successful intercalation of protocatechuate anions into the interlayer galleries of Zn/Al–NO{sub 3}–LDH in a monolayer arrangement with angles of 24 and 33° from the z-axis in PZAE and PZAC, respectively. The formation of nanocomposites was further confirmed by a Fourier transform infrared study. Thermogravimetric and differential thermogravimetric analyses indicated that the thermal stability of the intercalated protocatechuic acid was significantly enhanced compared to its free protocatechuic acid, and the drug content in the nanocomposites was estimated to be approximately 32.6% in PZAE and 29.2% in PZAC. Both PZAE and PZAC nanocomposites inhibit the growth of human cervical, liver and colorectal cancer cell lines and exhibit no toxic effects towards normal fibroblast 3T3 cell after 72 h of treatment. - Graphical abstract: Protocatechuate anions were arranged in monolayer mode with the angle of 24° for PZAE and 33° for PZAC from Z axis to maximize interaction between carboxylate groups and brucite-like layers. - Highlights: • Two methods gave nanocomposites with slightly different physico-chemical properties. • PZAE and PZAC have the potential to be used as a controlled release formulation. • The thermal stability of PA is markedly enhanced upon the intercalation process. • Higher cancer cell growth inhibition for PZAE and PZAC nanocomposites than for PA.

  8. Dual nutraceutical nanohybrids of folic acid and calcium containing layered double hydroxides

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Tae-Hyun; Oh, Jae-Min, E-mail: jaemin.oh@yonsei.ac.kr

    2016-01-15

    Dual nutraceutical nanohybrids consisting of organic nutrient, folic acid (FA), and mineral nutrient, calcium, were prepared based on layered double hydroxide (LDH) structure. Among various hybridization methods such as coprecipitation, ion exchange, solid phase reaction and exfoliation-reassembly, it was found that exfoliation-reassembly was the most effective in terms of intercalation of FA moiety between Ca-containing LDH layers. X-ray diffraction patterns and infrared spectra indicated that FA molecules were well stabilized in the interlayer space of LDHs through electrostatic interaction. From the atomic force and scanning electron microscopic studies, particle thickness of LDH was determined to be varied with tens, a few and again tens of nanometers in pristine, exfoliated and reassembled state, respectively, while preserving particle diameter. The result confirmed layer-by-layer hybrid structure of FA and LDHs was obtained by exfoliation-reassembly. Solid UV–vis spectra showed 2-dimensional molecular arrangement of FA moiety in hybrid, exhibiting slight red shift in n→π* and π→π* transition. The chemical formulae of FA intercalated Ca-containing LDH were determined to Ca{sub 1.30}Al(OH){sub 4.6}FA{sub 0.74}·3.33H{sub 2}O and Ca{sub 1.53}Fe(OH){sub 5.06}FA{sub 2.24}·9.94H{sub 2}O by inductively coupled plasma-atomic emission spectroscopy, high performance liquid chromatography and thermogravimetry, showing high nutraceutical content of FA and Ca. - Highlights: • We successfully intercalated FA molecules into Ca-containing LDHs. • Exfoliation-reassembly was proven to be the most effective. • The interaction between LDH and FA were studied by FT-IR and UV–vis spectra. • Thermal stability of FA were enhanced by electrostatic interaction with LDH layers.

  9. One-step synthesis of layered yttrium hydroxides in immiscible liquid–liquid systems: Intercalation of sterically-bulky hydrophobic organic anions and doping of europium ions

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, Mebae; Fujihara, Shinobu, E-mail: shinobu@applc.keio.ac.jp

    2014-02-15

    Inorganic–organic layered rare-earth compounds were synthesized on the basis of a biphasic liquid–liquid system in one pot. Layered yttrium hydroxides (LYHs) were chosen as a host material for the intercalation of hydrophobic organic guest anions such as benzoate, sebacate, or laurate. In a typical synthesis, an organic phase dissolving carboxylic acid was placed in contact with an equal amount of an aqueous phase dissolving yttrium nitrate n-hydrate and urea. At elevated temperatures up to 80 °C, urea was hydrolyzed to release hydroxyl anions which were used to form yttrium hydroxide layers. LYHs were then precipitated with the intercalation of carboxylate anions delivered from the organic phase under the distribution law. The structure and the morphology of the LYHs could be modulated by the intercalated anions. Doped with Eu{sup 3+} ions, the LYHs exhibited red photoluminescence which was enhanced by the intercalated anions due to the antenna effect. - Graphical abstract: The Eu{sup 3+}-doped layered yttrium hydroxide exhibits intense red photoluminescence after intercalation of benzoate ions. Display Omitted - Highlights: • Immiscible biphasic liquid systems were introduced to synthesize layered yttrium hydroxides. • The temperature of the biphasic systems does not exceed 80 °C in one step of the synthesis. • Hydrophobic organic anions were intercalated between the hydroxide layers in one pot. • Structure and morphology of the hydroxides were modulated by changing the kind of organic anions. • Eu{sup 3+}-doping led to red luminescence from the hydroxides in association with the intercalated organic anions.

  10. Dual nutraceutical nanohybrids of folic acid and calcium containing layered double hydroxides

    Science.gov (United States)

    Kim, Tae-Hyun; Oh, Jae-Min

    2016-01-01

    Dual nutraceutical nanohybrids consisting of organic nutrient, folic acid (FA), and mineral nutrient, calcium, were prepared based on layered double hydroxide (LDH) structure. Among various hybridization methods such as coprecipitation, ion exchange, solid phase reaction and exfoliation-reassembly, it was found that exfoliation-reassembly was the most effective in terms of intercalation of FA moiety between Ca-containing LDH layers. X-ray diffraction patterns and infrared spectra indicated that FA molecules were well stabilized in the interlayer space of LDHs through electrostatic interaction. From the atomic force and scanning electron microscopic studies, particle thickness of LDH was determined to be varied with tens, a few and again tens of nanometers in pristine, exfoliated and reassembled state, respectively, while preserving particle diameter. The result confirmed layer-by-layer hybrid structure of FA and LDHs was obtained by exfoliation-reassembly. Solid UV-vis spectra showed 2-dimensional molecular arrangement of FA moiety in hybrid, exhibiting slight red shift in n→π* and π→π* transition. The chemical formulae of FA intercalated Ca-containing LDH were determined to Ca1.30Al(OH)4.6FA0.74·3.33H2O and Ca1.53Fe(OH)5.06FA2.24·9.94H2O by inductively coupled plasma-atomic emission spectroscopy, high performance liquid chromatography and thermogravimetry, showing high nutraceutical content of FA and Ca.

  11. Antibacterial carboxymethyl cellulose/Ag nanocomposite hydrogels cross-linked with layered double hydroxides.

    Science.gov (United States)

    Yadollahi, Mehdi; Namazi, Hassan; Aghazadeh, Mohammad

    2015-08-01

    This paper deals with the preparation of antibacterial nanocomposite hydrogels through the combination of carboxy methyl cellulose (CMC), layered double hydroxides (LDH), and silver nanoparticles (AgNPs). CMC-LDH hydrogels were prepared by intercalating CMC into different LDHs. Then, Ag/CMC-LDH nanocomposite hydrogels were prepared through in situ formation of AgNPs within the CMC-LDHs. XRD analysis confirmed the intercalating CMC into the LDH sheets and formation of intercalated structures, as well as formation of AgNPs within the CMC-LDHs. SEM and TEM micrographs indicated well distribution of AgNPs within the Ag/CMC-LDHs. The prepared hydrogels showed a pH sensitive swelling behavior. The Ag/CMC-LDH nanocomposite hydrogels have rather higher swelling in different aqueous solutions in comparison with CMC-LDHs. The antibacterial activity of CMC-LDHs increased considerably after formation of AgNPs and was stable for more than one month. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. Organo-layered double hydroxides composite thin films deposited by laser techniques

    Science.gov (United States)

    Birjega, R.; Vlad, A.; Matei, A.; Dumitru, M.; Stokker-Cheregi, F.; Dinescu, M.; Zavoianu, R.; Raditoiu, V.; Corobea, M. C.

    2016-06-01

    We used laser techniques to create hydrophobic thin films of layered double hydroxides (LDHs) and organo-modified LDHs. A LDH based on Zn-Al with Zn2+/Al3+ ratio of 2.5 was used as host material, while dodecyl sulfate (DS), which is an organic surfactant, acted as guest material. Pulsed laser deposition (PLD) and matrix assisted pulsed laser evaporation (MAPLE) were employed for the growth of the films. The organic anions were intercalated in co-precipitation step. The powders were subsequently used either as materials for MAPLE, or they were pressed and used as targets for PLD. The surface topography of the thin films was investigated by atomic force microscopy (AFM), the crystallographic structure of the powders and films was checked by X-ray diffraction. FTIR spectroscopy was used to evidence DS interlayer intercalation, both for powders and the derived films. Contact angle measurements were performed in order to establish the wettability properties of the as-prepared thin films, in view of functionalization applications as hydrophobic surfaces, owing to the effect of DS intercalation.

  13. Development of polymer nanocomposites based on layered double hydroxides

    Directory of Open Access Journals (Sweden)

    Sipusic, J.

    2009-05-01

    Full Text Available Polymeric nanocomposites are commonly considered as systems composed of a polymeric matrix and - usually inorganic - filler. The types of nanofillers are indicated in Fig. 1. Beside wellknown layered silicate fillers, recent attention is attracted to layered double hydroxide fillers (LDH, mainly of synthetic origin. The structure of LDH is based on brucite, or magnesium hydroxide, Mg(OH2 and is illustrated in Fig. 2. The modification of LDHs is commonly done by organic anions, to increase the original interlayer distance and to improve the organophilicity of the filler, keeping in mind their final application as fillers for, usually hydrophobic, polymer matrices. We have used the modified rehydration procedure for preparing organically modified LDH. The stoichiometric quantities of Ca33Al2O6, CaO and benzoic (B (or undecenoic (U acid were mixed with water and some acetone. After long and vigorous shaking, the precipitated fillers were washed, dried and characterized. X-ray diffraction method (XRD has shown the increase of the original interlayer distance for unmodified LDH (OH–-saturated of 0.76 nm to the 1.6 nm in LDH-B or LDH-U fillers (Fig. 3. Infrared spectroscopy method (FTIR has confirmed the incorporation of benzoic anion within the filler layers (Fig. 4. For the preparation of LDH-B and LDH-U composites with polystyrene (PS, poly(methyl methacrylate (PMMA and copolymer (SMMA matrices, a two-step in situ bulk radical polymerization was selected (Table 1 for recipes, azobisisobutyronitrile as initiator, using conventional stirred tank reactor in the first step, and heated mold with the movable wall (Fig. 6 in the second step of polymerization. All the prepared composites with LDH-U fillers were macroscopically phase-separated, as was the PMMA/LDH-B composite.PS/LDH-B and SMMA/LDH-B samples were found to be transparent and were further examined for deduction of their structure (Fig. 5 and thermal properties. FTIR measurements showed that

  14. Study on Synthesis and Intercalation Behavior of Layered Zirconium Proline-N-methylphosphonate-phosphate

    Institute of Scientific and Technical Information of China (English)

    Xiao Ping RAO; Xiang Kai FU; Kai RAO

    2004-01-01

    Zirconium proline-N-methylphosphonate-phosphate (α-ZPMPP) was prepared in the presence of HF for the first time. The α-ZPMPP sample is highly crystallized with interlayer distance of 1.52 nm. The interlayer distance of complex of α-ZPMPP with n-butylamine (α-ZPMPP-BA) is in 0.45 nm larger than that of α-ZPMPP. The α-ZPMPP possesses different intercalation behavior of host-guest compound from α-ZP.

  15. Wet Permeability Characteristics of Double-layer Knitted Fabrics

    Institute of Scientific and Technical Information of China (English)

    WANG Qi; XI Bai-jun

    2007-01-01

    In order to solve the problem that sweat flows back into the internal layer from the external layer in doublelayer knits, a fabric structure model is set up and the conditions that keep the sweat from flowing back into the internal layer from the external layer are presented. It can be used to improve the design of the double-layer knitstheoretically.

  16. Optical and Electrical Characteristics of Graphene Double Layer Formed by a Double Transfer of Graphene Single Layers.

    Science.gov (United States)

    Kim, Young Jun; Bae, Gi Yoon; Chun, Sungwoo; Park, Wanjun

    2016-03-01

    We demonstrate formation of double layer graphene by means of a double transfer using two single graphene layers grown by a chemical vapor deposition method. It is observed that shiftiness and broadness in the double-resonance of Raman scattering are much weaker than those of bilayer graphene formed naturally. Transport characteristics examined from transmission line measurements and field effect transistors show the similar behavior with those of single layer graphene. It indicates that interlayer separation, in electrical view, is large enough to avoid correlation between layers for the double layer structure. It is also observed from a transistor with the double layer graphene that molecules adsorpted on two inner graphene surfaces in the double layered structure are isolated and conserved from ambient environment.

  17. In vitro controlled release of vitamin C from Ca/Al layered double hydroxide drug delivery system.

    Science.gov (United States)

    Gao, Xiaorui; Chen, Le; Xie, Juan; Yin, Yaobing; Chang, Tao; Duan, Yancong; Jiang, Nan

    2014-06-01

    A new drug delivery system for vitamin C (VC), Ca/Al layered double hydroxide (LDH), is demonstrated in this work. VC anions were intercalated successfully in the Ca/Al LDH gallery by a coprecipitation method. The interlayer space of 9.8Å suggests that VC anions are vertical to the LDH layers in the form of interdigitated bilayer. The loading of VC in LDH is 36.4wt.%. The thermal stability of VC is significantly enhanced after intercalation. In vitro VC release results show that the release time of VC in a phosphate buffer at pH7.4 was significantly extended, and the maximal percentage of VC released is 80% of the total. The Avrami-Erofe'ev equation most satisfactorily explains the release kinetics of VC, which is that the release of VC is mainly dominated by the ion-exchange reaction.

  18. Intercalation assembly of optical hybrid materials based on layered terbium hydroxide hosts and organic sensitizer anions guests

    Institute of Scientific and Technical Information of China (English)

    Liang-Liang Liu; Qin Wang; Dan Xia; Ting-Ting Shen; Ming-Hui Yu; Wei-Sheng Liu; Yu Tang

    2013-01-01

    Optical hybrid materials based on inorganic hosts and organic sensitizer guests hold promise for a virtually unlimited number of applications.In particular,the interaction and the combination of the properties of a defined inorganic matrix and a specific sensitizer could lead to synergistic effects in luminescence enhancing and tuning.The current article focuses on the intercalation assembly of optical hybrid materials based on the layered terbium hydroxide (LTbH) hosts and organic divalent carboxylic sensitizer anion guests by a hydrothermal process.The studies on the interactions between hosts and guests indicate that the type and arrangement of organic guests in the layer spacing of the LTbH hosts can make a difference in the luminescence of the hybrid inorganic-organic materials.

  19. Layered double hydroxide-based nanomaterials as highly efficient catalysts and adsorbents.

    Science.gov (United States)

    Li, Changming; Wei, Min; Evans, David G; Duan, Xue

    2014-11-01

    Layered double hydroxides (LDHs) are a class of anion clays consisting of brucite-like host layers and interlayer anions, which have attracted increasing interest in the fields of catalysis/adsorption. By virtue of the versatility in composition, morphology, and architecture of LDH materials, as well as their unique structural properties (intercalation, topological transformation, and self-assembly with other functional materials), LDHs display great potential in the design and fabrication of nanomaterials applied in photocatalysis, heterogeneous catalysis, and adsorption/separation processes. Taking advantage of the structural merits and various control synthesis strategies of LDHs, the active center structure (e.g., crystal facets, defects, geometric and electronic states, etc.) and macro-nano morphology can be facilely manipulated for specific catalytic/adsorbent processes with largely enhanced performances. In this review, the latest advancements in the design and preparation of LDH-based functional nanomaterials for sustainable development in catalysis and adsorption are summarized.

  20. Texture effect of layered double hydroxides on chemisorption of Orange II

    Science.gov (United States)

    Géraud, Erwan; Bouhent, Mustapha; Derriche, Zoubir; Leroux, Fabrice; Prévot, Vanessa; Forano, Claude

    2007-05-01

    The chemisorption properties of hydrotalcite (HT) with novel macroporous properties have been investigated for azo dye, Orange II (O-II), and compared to coprecipitated HT and their calcined derivatives. Adsorption isotherms satisfactorily fit the Langmuir model. Adsorption capacities of the layered double hydroxides (LDH) macroporous structures are very high, particularly for the calcined materials (4.34 mmol/g) compared to standard HT (0.504 mmol/g), showing that accessibility to the LDH layer surface insures better sorptive properties. For both synthetic materials, the calcination/reconstruction process gives rise to highest concentrations of adsorbed O-II and a partial intercalation of O-II molecules in the structure as shown by the expansion of the basal spacing (d=2.4nm). Conversely, the uncalcined HT phases mainly display a surface exchange chemisorption process.

  1. Layered double hydroxides as carriers for quantum dots@silica nanospheres

    Science.gov (United States)

    Stoica, Georgiana; Castelló Serrano, Iván.; Palomares, Emilio

    2013-02-01

    Quantum dot-hydrotalcite layered nanoplatforms were successfully prepared following a one-pot synthesis. The process is very fast and a priori delamination of hydrotalcite is not a prerequisite for the intercalation of quantum dots. The novel materials were extensively characterized by X-ray diffraction, thermogravimetry, infrared spectroscopy, transmission electron microscopy, true color fluorescence microscopy, photoluminescence, and nitrogen adsorption. The quantum dot-hydrotalcite nanomaterials display extremely high stability in mimicking physiological media such as saline serum (pH 5.5) and PBS (pH 7.2). Yet, quantum dot release from the solid structure is noted. In order to prevent the leaking of quantum dots we have developed a novel strategy which consists on using tailor made double layered hydrotalcites as protecting shells for quantum dots embedded into silica nanospheres without changing either the materials or the optical properties.

  2. PREPARATION OF POLY(METHYL METHACRYLATE)/LAYERED DOUBLE HYDROXIDES NANOCOMPOSITES via in situ SOLUTION POLYMERIZATION

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    An exfoliated layered double hydroxides/poly(methyl methacrylate) (LDHs/PMMA) nanocomposite was prepared by in situ solution polymerization of methyl methacrylate (MMA) in the presence of 4-vinylbenzenesulfonate intercalated LDHs(MgAl-VBS LDHs). MgAl-VBS LDHs was prepared by the ion exchange method, and the structure and composition of the MgAl-VBS LDHs were determined by X-ray diffraction (XRD), infrared spectroscopy and elemental analysis. XRD and transmission electron microscopy (TEM) were employed to examine the structure of LDHs/PMMA nanocomposite. It was indicated that the LDHs layers were well exfoliated and dispersed in the PMMA matrix. The grafting of PMMA onto LDHs was confirmed by the extraction result and the weight fraction of grafted PMMA increased as the weight fraction of LDHs in the nanocomposites increased.

  3. Synthesis of layered double hydroxide nanosheets by coprecipitation using a T-type microchannel reactor

    Science.gov (United States)

    Pang, Xiujiang; Sun, Meiyu; Ma, Xiuming; Hou, Wanguo

    2014-02-01

    The synthesis of Mg2Al-NO3 layered double hydroxide (LDH) nanosheets by coprecipitation using a T-type microchannel reactor is reported. Aqueous LDH nanosheet dispersions were obtained. The LDH nanosheets were characterized by X-ray diffraction, transmission electron microscopy, atomic force microscopy and particle size analysis, and the transmittance and viscosity of LDH nanosheet dispersions were examined. The two-dimensional LDH nanosheets consisted of 1-2 brucite-like layers and were stable for ca. 16 h at room temperature. In addition, the co-assembly between LDH nanosheets and dodecyl sulfate (DS) anions was carried out, and a DS intercalated LDH nanohybrid was obtained. To the best of our knowledge, this is the first report of LDH nanosheets being directly prepared in bulk aqueous solution. This simple, cheap method can provide naked LDH nanosheets in high quantities, which can be used as building blocks for functional materials.

  4. Double-Layer Systems at Zero Magnetic Field

    OpenAIRE

    ~Hanna, C. ~B.; Haas, Dylan; Diaz-Velez, J.C.

    2000-01-01

    We investigate theoretically the effects of intralayer and interlayer exchange in biased double-layer electron and hole systems, in the absence of a magnetic field. We use a variational Hartree-Fock-like approximation to analyze the effects of layer separation, layer density, tunneling, and applied gate voltages on the layer densities and on interlayer phase coherence. In agreement with earlier work, we find that for very small layer separations and low layer densities, an interlayer-correlat...

  5. The electric double layer in hydriding metals

    Directory of Open Access Journals (Sweden)

    K. Jamroziak

    2008-12-01

    Full Text Available Purpose: The effect of penetration hydrogen into fatigue load metals is widely investigated by many researchers.Hydrogen is the chemical element which plays negative role in fatigue durability of structures. It decides on fatiguebrittle cracking. In the paper authors carry out an analysis of fatigue durability. Making use of naturally coming intoexistence the electric double layer phenomenon authors discussed the model of absorbing hydrogen into fatigue gap.Design/methodology/approach: A proposed model of the mechanism of hydrogen absorption by metal wasbased on particle hydrogen and water vapor from the air.Findings: It assumes that the EDL has crucial role in intercepting of polar dipole particles of hydrogenand water’s vapor, especially in an already formed fatigue micro-gaps and gaps by effects of its electrostaticattraction force. The authors assume that the main source of hydrogen is water’s vapor, and number of hydrogendipoles is negligible.Practical implications: The problems of metals’ fragility/durability were also discussed in other papersin which author mainly tried to develop new methods of materials’ production with the consideration of assumedfatigue durability.Originality/value: Currently, in progress are works on proposing a model for hydrogen absorption by metal.Such approach to optimization in production and development of the new technologies is an essence of modernconstructions that work in all variety of mechanical stress conditions.

  6. Double-layered Aurivillius-type ferroelectrics with magnetic moments

    NARCIS (Netherlands)

    Missyul, A. B.; Zvereva, I. A.; Palstra, T. T. M.; Kurbakov, A. I.

    2010-01-01

    We have synthesized the double-layer Aurivillius phase Bi(2)LnNbTiO(9) where Ln = Nd-Gd, Bi. All compounds adopt the orthorhombic polar space group A2(I)am. The magnetic Ln-ion occupies the cuboctahedral position in the middle of the perovskite double-layer, and thus controls the octahedral tilt of

  7. From nicotinate-containing layered double hydroxides (LDHs) to NAD coenzyme-LDH nanocomposites - Syntheses and structural characterization by various spectroscopic methods

    Science.gov (United States)

    Muráth, Szabolcs; Dudás, Csilla; Kukovecz, Ákos; Kónya, Zoltán; Sipos, Pál; Pálinkó, István

    2017-07-01

    The syntheses of nicotinate anion- and NAD coenzyme-layered double hydroxide (LDH) composites were performed with the aim of having the organic component among the layers. In-house prepared CaAl-LDHs were the host materials. Intercalation was attempted by direct ion exchange or by the dehydration-rehydration method applying aqueous solvent mixtures (containing ethanol, propanol, acetone, N,N-dimethylformamide). For structural characterization, beside X-ray diffractometry, X-ray photoelectron and IR spectroscopies, transmission and scanning electron microscopies as well as energy-dispersive X-ray analysis were used. Molecular modelling served for the visualization of the arrangements of the intercalated ions among the layers of the LDH samples. Although not all the intercalation methods and solvent mixtures led to intercalated composite materials, successful ones could be identified. The combination of spectroscopic methods helped in proposing sensible spatial arrangements for the intercalated anions. The NAD-CaAl-LDH composite proved to be an active catalyst in the oxidation of hydroquinone to 1,4-bezoquinoe in the presence of H2O2.

  8. Synthesis, Characterization, and In Vitro Drug Delivery Capabilities of (Zn, Al-Based Layered Double Hydroxide Nanoparticles

    Directory of Open Access Journals (Sweden)

    Vinay J. Nagaraj

    2015-01-01

    Full Text Available There is an urgent need for the development of alternative strategies for effective drug delivery to improve the outcome of patients suffering from deadly diseases such as cancer. Nanoparticles, in particular layered double hydroxide (LDH nanoparticles, have great potential as nanocarriers of chemotherapeutic molecules. In this study, we synthesized (Zn, Al-LDH nanoparticles and report their enhanced pH-dependent stability in comparison to the commonly used (Mg, Al-LDH nanoparticles. Fluorescein isothiocyanate (FITC and valproate (VP were intercalated into (Zn, Al-LDH nanoparticles to study cellular uptake, biocompatibility, and drug delivery capabilities using cultured pancreatic adenocarcinoma BxPC3 cells. Fluorescence measurements indicated that FITC-intercalated LDH nanoparticles showed a greater degree of energy-dependent uptake rather than passive uptake by BxPC3 cells, especially at high concentrations of nanoparticles. Tetrazolium-based colorimetric assays indicated that BxPC3 cells treated with VP-intercalated LDH nanoparticles showed a significant reduction in cell viability along with about 30-fold reduction in IC50 compared to the drug alone. In contrast, the non-drug-intercalated LDH nanoparticles did not affect the cell viability indicating very low innate cytotoxicity. Our research indicates that the superior properties of (Zn, Al-LDH nanoparticles make them ideal candidates for further development as in vivo chemotherapy drug delivery agents.

  9. Layered double hydroxide stability. 1. Relative stabilities of layered double hydroxides and their simple counterparts

    Science.gov (United States)

    Boclair, J. W.; Braterman, P. S.

    1999-01-01

    Solutions containing di- and trivalent metal chlorides [M(II) = Mg2+, Zn2+, Co2+, Ni2+, Mn2+; M(III) = Al3+, Fe3+] were titrated with NaOH to yield hydrotalcite-like layered double hydroxides (LDH), [[M(II)]1-x[M(III)]x(OH)2][Cl]x yH2O, by way of M(III) hydroxide/hydrous oxide intermediates. Analysis of the resultant titration curves yields nominal solubility constants for the LDH. The corresponding LDH stabilities are in the order Mg hydroxides/hydrous oxides is discussed.

  10. Controlled release and angiotensin-converting enzyme inhibition properties of an antihypertensive drug based on a perindopril erbumine-layered double hydroxide nanocomposite

    Directory of Open Access Journals (Sweden)

    Hussein Al Ali SH

    2012-04-01

    Full Text Available Samer Hasan Hussein Al Ali1, Mothanna Al-Qubaisi2, Mohd Zobir Hussein1,3, Maznah Ismail2,4, Zulkarnain Zainal1, Muhammad Nazrul Hakim51Department of Chemistry, Faculty of Science, 2Laboratory of Molecular Biomedicine, Institute of Bioscience, 3Advanced Materials and Nanotechnology Laboratory, Institute of Advanced Technology, 4Department of Nutrition and Dietetics, Faculty of Medicine and Health Science, 5Department of Biomedical Science, Faculty of Medicine and Health Science, Universiti Putra Malaysia, Serdang, Selangor, MalaysiaBackground: The intercalation of perindopril erbumine into Zn/Al-NO3-layered double hydroxide resulted in the formation of a host-guest type of material. By virtue of the ion-exchange properties of layered double hydroxide, perindopril erbumine was released in a sustained manner. Therefore, this intercalated material can be used as a controlled-release formulation.Results: Perindopril was intercalated into the interlayers and formed a well ordered, layered organic-inorganic nanocomposite. The basal spacing of the products was expanded to 21.7 Å and 19.9 Å by the ion-exchange and coprecipitation methods, respectively, in a bilayer and a monolayer arrangement, respectively. The release of perindopril from the nanocomposite synthesized by the coprecipitation method was slower than that of its counterpart synthesized by the ion-exchange method. The rate of release was governed by pseudo-second order kinetics. An in vitro antihypertensive assay showed that the intercalation process results in effectiveness similar to that of the antihypertensive properties of perindopril.Conclusion: Intercalated perindopril showed better thermal stability than its free counterpart. The resulting material showed sustained-release properties and can therefore be used as a controlled-release formulation.Keywords: perindopril erbumine, layered double hydroxides, ion-exchange, coprecipitation, sustained release, angiotensin-converting enzyme

  11. Preparation and structural evolution of SiO(2)-TiO(2) pillared layered manganese oxide nanocomposite upon intercalating reaction.

    Science.gov (United States)

    Wang, Jianfang; Liu, Zong-Huai; Tang, Xiuhua; Ooi, Kenta

    2007-03-15

    SiO(2)-TiO(2) pillared layered manganese oxide nanohybrid was successfully synthesized by preliminarily expanding the interlayer of H-type layered manganese oxide using dodecylamine, followed by reacting it with a mixture solution of titanium isopropoxide and tetraethylorthosilicate. The basal spacing and the pillared agent content of the obtained materials connected with the length of intercalated n-alkylamine, incorporated Si/Ti molar ratios and the solvothermal treatment temperature. The structural evolution of SiO(2)-TiO(2) pillared layered manganese oxide nanohybrid was characterized by XRD, DSC-TGA, SEM, IR, N(2) adsorption-desorption and element analyses. TiO(2) particles exhibited a stronger affinity for the negatively charged manganese layers, and the TiO(2) particles incorporated were independently intercalated without any distinct chemical bonding with the co-intercalated SiO(2) particles. SiO(2)-TiO(2) pillared layered manganese oxide nanohybrid had a BET surface area of 98 m(2)/g with a gallery height of about 1.43 nm between layers. The obtained SiO(2)-TiO(2) co-pillared layered manganese oxide nanohybrid is expected as a selective catalyst, or an improved battery material.

  12. Synthesis of nanocomposite 2-methyl-4-chlorophenoxyacetic acid with layered double hydroxide: physicochemical characterization and controlled release properties

    Energy Technology Data Exchange (ETDEWEB)

    Sarijo, Siti Halimah, E-mail: izaddinizaddin@yahoo.com; Ghazali, Sheikh Ahmad Izaddin Sheikh Mohd [Faculty of Applied Sciences, Universiti Teknologi MARA (Malaysia); Hussein, Mohd Zobir [Universiti Putra Malaysia, Department of Chemistry, Faculty of Science (Malaysia); Sidek, Norizzah Jaafar [Faculty of Applied Sciences, Universiti Teknologi MARA (Malaysia)

    2013-01-15

    A new organic-inorganic hybrid nanocomposite Zn-Al-MCPA-layered double hydroxide (ZAM) was prepared by intercalation of 2-methyl-4-chlorophenoxyacetic acid (MCPA) into Zn-Al-layered double hydroxide (ZAL) at various concentration of MCPA ranging from 0.1 to 0.7 M. The pH of the synthesis was kept constant at 7.5. Well-ordered hybrid nanocomposite was obtained with 0.4 M MCPA with an expansion of basal spacing from 8.9 Angstrom-Sign in the ZAL to 19.7 Angstrom-Sign in the resulting nanocomposite. The FTIR spectra of the nanocomposite show resemblance peaks of the MCPA and Zn-Al-layered double hydroxide indicating the inclusion of MCPA into the layered double hydroxide. The average particle size of ZAL and ZAM in this study was 115 and 128 nm, respectively. Percentage loading of MCPA was found to be 45.0 % (w/w), calculated based on the percentage of carbon in the sample. The release of MCPA into various aqueous solution was found to be dependent to the anion in the aqueous solution in the order of phosphate > sulfate > chloride with the percentage release of 80, 44, and 8%, respectively. This study shows that Zn-Al-layered double hydroxide can be used as a host carrier for herbicide, MCPA, with controlled release capability.

  13. Synthesis of nanocomposite 2-methyl-4-chlorophenoxyacetic acid with layered double hydroxide: physicochemical characterization and controlled release properties

    Science.gov (United States)

    Sarijo, Siti Halimah; Ghazali, Sheikh Ahmad Izaddin Sheikh Mohd; Hussein, Mohd Zobir; Sidek, Norizzah Jaafar

    2013-01-01

    A new organic-inorganic hybrid nanocomposite Zn-Al-MCPA-layered double hydroxide (ZAM) was prepared by intercalation of 2-methyl-4-chlorophenoxyacetic acid (MCPA) into Zn-Al-layered double hydroxide (ZAL) at various concentration of MCPA ranging from 0.1 to 0.7 M. The pH of the synthesis was kept constant at 7.5. Well-ordered hybrid nanocomposite was obtained with 0.4 M MCPA with an expansion of basal spacing from 8.9 Å in the ZAL to 19.7 Å in the resulting nanocomposite. The FTIR spectra of the nanocomposite show resemblance peaks of the MCPA and Zn-Al-layered double hydroxide indicating the inclusion of MCPA into the layered double hydroxide. The average particle size of ZAL and ZAM in this study was 115 and 128 nm, respectively. Percentage loading of MCPA was found to be 45.0 % (w/w), calculated based on the percentage of carbon in the sample. The release of MCPA into various aqueous solution was found to be dependent to the anion in the aqueous solution in the order of phosphate > sulfate > chloride with the percentage release of 80, 44, and 8 %, respectively. This study shows that Zn-Al-layered double hydroxide can be used as a host carrier for herbicide, MCPA, with controlled release capability.

  14. Sodium montmorillonite/amine-containing drugs complexes: new insights on intercalated drugs arrangement into layered carrier material.

    Directory of Open Access Journals (Sweden)

    Murilo L Bello

    Full Text Available Layered drug delivery carriers are current targets of nanotechnology studies since they are able to accommodate pharmacologically active substances and are effective at modulating drug release. Sodium montmorillonite (Na-MMT is a clay that has suitable properties for developing new pharmaceutical materials due to its high degree of surface area and high capacity for cation exchange. Therefore Na-MMT is a versatile material for the preparation of new drug delivery systems, especially for slow release of protonable drugs. Herein, we describe the intercalation of several amine-containing drugs with Na-MMT so we can derive a better understanding of how these drugs molecules interact with and distribute throughout the Na-MMT interlayer space. Therefore, for this purpose nine sodium montmorillonite/amine-containing drugs complexes (Na-MMT/drug were prepared and characterized. In addition, the physicochemical properties of the drugs molecules in combination with different experimental conditions were assessed to determine how these factors influenced experimental outcomes (e.g. increase of the interlayer spacing versus drugs arrangement and orientation. We also performed a molecular modeling study of these amine-containing drugs associated with different Na-MMT/drug complex models to analyze the orientation and arrangement of the drugs molecules in the complexes studied. Six amine-containing drugs (rivastigmine, doxazosin, 5-fluorouracil, chlorhexidine, dapsone, nystatin were found to successfully intercalate Na-MMT. These findings provide important insights on the interlayer aspect of the molecular systems formed and may contribute to produce more efficient drug delivery nanosystems.

  15. Intracellular release of fluorescein anion from layered double hydroxide nanoparticles indicating endosomal escape

    Science.gov (United States)

    Tanaka, M.; Aisawa, S.; Hidetoshi, H.; Narita, E.; Dong, Q.; Yin, S.; Sato, T.

    2013-12-01

    In recent years, layered double hydroxide (LDH) has been attempted to be applied to a molecular container due to their anion exchange ability, low cytotoxicity and good biocompatibility. In this paper, we investigated the intracellular behaviour of LDH particles in mammalian cells after internalization. Nanoparticles of fluorescein (Fluo) intercalated LDH, Fluo/LDH, were prepared by the coprecipitation followed by subsequent hydrothermal treatment. As-prepared Fluo/LDH particles have the LDH structure and morphology of hexagonal sheet of 100 nm on the average. In addition, Fluo/LDH also exhibited high green fluorescence and low cytotoxicity. By a confocal laser scanning microscopy, the dim green fluorescence was observed throughout cells, including the nucleus. This result indicated that Fluo/LDH released guest anion (Fluo) from LDH structure inside cells. Furthermore, because the fluorescence was observed throughout the cell, Fluo was not retained within endosome structure, i.e., Fluo/LDH was dissolved to release Fluo from endosome.

  16. Preparation and antibacterial activity of lysozyme and layered double hydroxide nanocomposites.

    Science.gov (United States)

    Yang, Qin-Zheng; Chang, Ying-Yue; Zhao, Hua-Zhang

    2013-11-01

    It is necessary to develop "green" disinfection technology which does not produce disinfection by-products. Lysozyme-layered double hydroxide nanocomposites (LYZ-LDHs) were prepared by intercalating LYZ in LDH for the first time. Their antibacterial activity was evaluated using staphylococcus aureus as a target. The bacteria removal mechanism was also studied. Characterization of LYZ-LDHs by X-ray diffraction and Fourier transform infrared spectroscopy indicated that LYZ was successfully intercalated in LDH, compressed and deformed without secondary structural change. LYZ-LDHs showed excellent bactericidal effectiveness against staphylococcus aureus. The antibacterial performance of LYZ-LDHs was found to be affected by the LYZ/LDH ratio and the pH of the bacteria-containing water. The bacteria removal efficiency of LYZ-LDHs with LYZ/LDH mass ratio of 0.8 was consistently above 94% over the pH range of 3-9. LYZ-LDHs adsorbed bacteria to their surface by LDH and then killed them by the immobilized LYZ. This new material integrated the bactericidal ability of LYZ and adsorption ability of LDH. Moreover, the antibacterial ability of LYZ-LDHs was persistent and not limited by the adsorption capacity.

  17. Superior coagulation of graphene oxides on nanoscale layered double hydroxides and layered double oxides.

    Science.gov (United States)

    Zou, Yidong; Wang, Xiangxue; Chen, Zhongshan; Yao, Wen; Ai, Yuejie; Liu, Yunhai; Hayat, Tasawar; Alsaedi, Ahmed; Alharbi, Njud S; Wang, Xiangke

    2016-12-01

    With the development and application of graphene oxides (GO), the potential toxicity and environmental behavior of GO has become one of the most forefront environmental problems. Herein, a novel nanoscale layered double hydroxides (glycerinum-modified nanocrystallined Mg/Al layered double hydroxides, LDH-Gl), layered double oxides (calcined LDH-Gl, LDO-Gl) and metallic oxide (TiO2) were synthesized and applied as superior coagulants for the efficient removal of GO from aqueous solutions. Coagulation of GO as a function of coagulant contents, pH, ionic strength, GO contents, temperature and co-existing ions were studied and compared, and the results showed that the maximum coagulation capacities of GO were LDO-Gl (448.3 mg g(-1)) > TiO2 (365.7 mg g(-1)) > LDH-Gl (339.1 mg g(-1)) at pH 5.5, which were significantly higher than those of bentonite, Al2O3, CaCl2 or other natural materials due to their stronger reaction active and interfacial effect. The presence of SO3(2-) and HCO3(-) inhibited the coagulation of GO on LDH-Gl and LDO-Gl significantly, while other cations (K(+), Mg(2+), Ca(2+), Ni(2+), Al(3+)) or anion (Cl(-)) had slightly effect on GO coagulation. The interaction mechanism of GO coagulation on LDO-Gl and TiO2 might due to the electrostatic interactions and strong surface complexation, while the main driving force of GO coagulation on LDH-Gl might be attributed to electrostatic interaction and hydrogen bond, which were further evidenced by TEM, SEM, FT-IR and XRD analysis. The results of natural environmental simulation showed that LDO-Gl, TiO2 or other kinds of natural metallic oxides could be superior coagulants for the efficient elimination of GO or other toxic nanomaterials from aqueous solutions in real environmental pollution cleanup.

  18. Synthesis of layered double hydroxide nanosheets by coprecipitation using a T-type microchannel reactor

    Energy Technology Data Exchange (ETDEWEB)

    Pang, Xiujiang; Sun, Meiyu; Ma, Xiuming [State Key Laboratory Base of Eco-chemical Engineering, College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042 (China); Hou, Wanguo, E-mail: wghou@sdu.edu.cn [Key Laboratory of Colloid and Interface Chemistry (Ministry of Education), Shandong University, Jinan 250100 (China)

    2014-02-15

    The synthesis of Mg{sub 2}Al–NO{sub 3} layered double hydroxide (LDH) nanosheets by coprecipitation using a T-type microchannel reactor is reported. Aqueous LDH nanosheet dispersions were obtained. The LDH nanosheets were characterized by X-ray diffraction, transmission electron microscopy, atomic force microscopy and particle size analysis, and the transmittance and viscosity of LDH nanosheet dispersions were examined. The two-dimensional LDH nanosheets consisted of 1–2 brucite-like layers and were stable for ca. 16 h at room temperature. In addition, the co-assembly between LDH nanosheets and dodecyl sulfate (DS) anions was carried out, and a DS intercalated LDH nanohybrid was obtained. To the best of our knowledge, this is the first report of LDH nanosheets being directly prepared in bulk aqueous solution. This simple, cheap method can provide naked LDH nanosheets in high quantities, which can be used as building blocks for functional materials. - Graphical abstract: Layered double hydroxide (LDH) nanosheets were synthesized by coprecipitation using a T-type microchannel reactor, and could be used as basic building blocks for LDH-based functional materials. Display Omitted - Highlights: • LDH nanosheets were synthesized by coprecipitation using a T-type microchannel reactor. • Naked LDH nanosheets were dispersed in aqueous media. • LDH nanosheets can be used as building blocks for functional materials.

  19. EXAFS and FTIR studies of selenite and selenate sorption by alkoxide-free sol-gel generated Mg-Al-CO3 layered double hydroxide with very labile interlayer anions

    NARCIS (Netherlands)

    Chubar, N.

    2014-01-01

    Current research on Layered Double Hydroxides (LDHs, also known as hydrotalcites, HTs) is predominantly focused on their intercalations, but the industrial application of LDHs for anion exchange adsorption has not yet been achieved. It was recently recognized that, to develop LDH applications, these

  20. Comparative study of Mg/Al- and Zn/Al-layered double hydroxide-perindopril erbumine nanocomposites for inhibition of angiotensin-converting enzyme.

    Science.gov (United States)

    Hussein Al Ali, Samer Hasan; Al-Qubaisi, Mothanna; Hussein, Mohd Zobir; Ismail, Maznah; Zainal, Zulkarnain; Hakim, Muhammad Nazrul

    2012-01-01

    The intercalation of a drug active, perindopril, into Mg/Al-layered double hydroxide for the formation of a new nanocomposite, PMAE, was accomplished using a simple ion exchange technique. A relatively high loading percentage of perindopril of about 36.5% (w/w) indicates that intercalation of the active took place in the Mg/Al inorganic interlayer. Intercalation was further supported by Fourier transform infrared spectroscopy, and thermal analysis shows markedly enhanced thermal stability of the active. The release of perindopril from the nanocomposite occurred in a controlled manner governed by pseudo-second order kinetics. MTT assay showed no cytotoxicity effects from either Mg/Al-layered double hydroxide or its nanocomposite, PMAE. Mg/Al-layered double hydroxide showed angiotensin-converting enzyme inhibitory activity, with 5.6% inhibition after 90 minutes of incubation. On incubation of angiotensin-converting enzyme with 0.5 μg/mL of the PMAE nanocomposite, inhibition of the enzyme increased from 56.6% to 70.6% at 30 and 90 minutes, respectively. These results are comparable with data reported in the literature for Zn/Al-perindopril.

  1. Electrospun fibers of layered double hydroxide/biopolymer nanocomposites as effective drug delivery systems

    Energy Technology Data Exchange (ETDEWEB)

    Miao, Yue-E.; Zhu Hong; Chen Dan; Wang Ruiyu [State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University, Shanghai 200433 (China); Tjiu, Weng Weei [Institute of Materials Research and Engineering, A-STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore 117602 (Singapore); Liu Tianxi, E-mail: txliu@fudan.edu.cn [State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University, Shanghai 200433 (China)

    2012-06-15

    Ibuprofen intercalated layered double hydroxide (LDH-IBU)/polycaprolactone (PCL) and LDH-IBU/polylactide (PLA) nanocomposite fibers are electrospun based on a combination of LDH-IBU with two kinds of biopolymers (i.e. PCL and PLA), to act as effective drug delivery systems. Ibuprofen (IBU) is chosen as a model drug, which is intercalated in MgAl-LDH by coprecipitation. Poly(oxyethylene-b-oxypropylene-b-oxyethylene) (Pluronic) is also added into PLA-based fibers as hydrophilicity enhancer and release modulator. LDH-IBU nanoparticles are uniformly dispersed throughout the nanocomposite fibers, as evidenced by transmission electron microscopy (TEM) observations. In vitro drug release studies show that initial IBU liberation from LDH-IBU/PCL composite fibers is remarkably slower than that from IBU/PCL fibers due to the sustained release property of LDH-IBU and heterogeneous nucleation effect of LDH-IBU on PCL chain segments. Surprisingly, the initial IBU release from LDH-IBU/PLA and LDH-IBU/PLA/Pluronic composite fibers is faster than that from the corresponding IBU/PLA and IBU/PLA/Pluronic fibers. This effect can be attributed to the strong interaction between alkyl groups in IBU molecules and methyl substituent groups of PLA as well as the hydrophilicity of LDH-IBU, which lead to an easier diffusion of water with a faster release of IBU from LDH-IBU/PLA and LDH-IBU/PLA/Pluronic composite fibers. - Graphical abstract: Ibuprofen intercalated layered double hydroxide (LDH-IBU)/polycaprolactone (PCL) and LDH-IBU/polylactide (PLA) nanocomposite fibers are electrospun based on the combination of LDHs with two kinds of biopolymers (i.e. PCL and PLA). LDH-IBU nanoparticles are uniformly dispersed throughout all the electrospun nanocomposite fibers even at a high loading level of 5 wt%. By combining the tunable drug release property of LDHs and electrospinning technique, the new drug delivery system is anticipated for effective loading and sustained release of drugs

  2. Redox Active Cation Intercalation/Deintercalation in Two-Dimensional Layered MnO2 Nanostructures for High-Rate Electrochemical Energy Storage.

    Science.gov (United States)

    Xiong, Pan; Ma, Renzhi; Sakai, Nobuyuki; Bai, Xueyin; Li, Shen; Sasaki, Takayoshi

    2017-02-22

    Two-dimensional (2D) layered materials with a high intercalation pseudocapacitance have long been investigated for Li(+)-ion-based electrochemical energy storage. By contrast, the exploration of guest ions other than Li(+) has been limited, although promising. The present study investigates intercalation/deintercalation behaviors of various metal ions in 2D layered MnO2 with various interlayer distances, K-birnessite nanobelt (K-MnO2), its protonated form (H-MnO2), and a freeze-dried sample of exfoliated nanosheets. Series of metal ions, such as monovalent Li(+), Na(+), and K(+) and divalent Mg(2+), exhibit reversible intercalation during charge/discharge cycling, delivering high-rate pseudocapacitances. In particular, the freeze-dried MnO2 of exfoliated nanosheets restacked with the largest interlayer spacing and a less compact 3D network exhibits the best rate capability and a stable cyclability over 5000 cycles. Both theoretical calculation and kinetic analysis reveal that the increased interlayer distance facilitates the fast diffusion of cations in layered MnO2 hosts. The results presented herein provide a basis for the controllable synthesis of layered nanostructures for high-rate electrochemical energy storage using various single- and multivalent ions.

  3. Surface-plasmons lasing in double-graphene-layer structures

    Energy Technology Data Exchange (ETDEWEB)

    Dubinov, A. A. [Research Institute for Electrical Communication, Tohoku University, Sendai 980-8577 (Japan); Institute for Physics of Microstructures of Russian Academy of Sciences, and Lobachevsky State University of Nizhny Novgorod, Nizhny Novgorod 603950 (Russian Federation); Aleshkin, V. Ya. [Institute for Physics of Microstructures of Russian Academy of Sciences, and Lobachevsky State University of Nizhny Novgorod, Nizhny Novgorod 603950 (Russian Federation); Ryzhii, V. [Research Institute for Electrical Communication, Tohoku University, Sendai 980-8577 (Japan); Center for Photonics and Infrared Engineering, Bauman Moscow State Technical University, Moscow 105005 (Russian Federation); Shur, M. S. [Department of Electrical, Electronics, and System Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); Otsuji, T. [Research Institute for Electrical Communication, Tohoku University, Sendai 980-8577 (Japan)

    2014-01-28

    We consider the concept of injection terahertz lasers based on double-graphene-layer (double-GL) structures with metal surface-plasmon waveguide and study the conditions of their operation. The laser under consideration exploits the resonant radiative transitions between GLs. This enables the double-GL laser room temperature operation and the possibility of voltage tuning of the emission spectrum. We compare the characteristics of the double-GL lasers with the metal surface-plasmon waveguides with those of such laser with the metal-metal waveguides.

  4. Preparation, characterization and dye adsorption of Au nanoparticles/ZnAl layered double oxides nanocomposites

    Science.gov (United States)

    Zhang, Yu Xin; Hao, Xiao Dong; Kuang, Min; Zhao, Han; Wen, Zhong Quan

    2013-10-01

    In this work, Au/ZnAl-layer double oxides (LDO) nanocomposties were prepared through a facile calcination process of AuCl4- intercalated ZnAl-layered double hydroxides (LDHs) nanocomposites. The morphology and crystal structure of these nanocomposites were characterized by Scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (XRD), and N2 sorption analysis. By tailoring the process parameter, such as calcination temperature, heating time and the component composition, the adsorption properties of methyl orange (MO) on the Au/ZnAl-LDO nanocomposites were investigated in this work. In a typical adsorption process, it was found that 0.985 mg of MO (0.01 g L-1, 100 mL, 1 mg of MO in total) can be removed in 60 min by utilizing only 2.5 mg of Au/ZnAl-LDO (Au content, 1%) as adsorbents. Our adsorption data obtained from the Langmuir model also gave good values of the determination coefficient, and the saturated adsorption capacity of Au/ZnAl-LDO nanocomposites for MO was found to be 627.51 mg/g under ambient condition (e.g., room temperature, 1 atm). In principle, these hybrid nanostructures with higher adsorption abilities could be very promising adsorbents for wastewater treatment.

  5. Weak localization effects in Ga-intercalated layered compound NbS{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Niazi, A. [Jawaharlal Nehru Univ., New Delhi (India). School of Physical Science; Rastogi, A.K. [Jawaharlal Nehru Univ., New Delhi (India). School of Physical Science

    1996-07-01

    Ga{sub x}NbS{sub 2}(x=0-0.33) was prepared in two batches-{proportional_to}1000 C (LT) and {proportional_to}1125 C (HT). X-ray diffraction shows random stacking of 2H-NbS{sub 2} layers in the HT phase. Resistivity and thermopower measurements from 15 to 300 K show metallic behaviour and anomalies around 45 K. The disordered phases indicate weak localisation effects in conductivity above 45 K and a log T variation in the x=0.25 compound indicating 2-D conduction. The thermopower is unaffected by the disorder. The 45 K transition suppresses this localisation. (orig.).

  6. Radiation induced topotactic [2 + 2] dimerisation of acrylate derivatives among the layers of a CaFe layered double hydroxide followed by IR spectroscopy

    Science.gov (United States)

    Srankó, D. F.; Canton, S.; Enghdahl, A.; Muráth, Sz.; Kukovecz, Á.; Kónya, Z.; Sipiczki, M.; Sipos, P.; Pálinkó, I.

    2013-07-01

    Various acrylates [E-phenylpropenoate, E-3(4‧-nitrophenyl)propenoate, E-3(2‧,5‧-difluorphenyl)propenoate, E-3(2‧-thienyl)propenoate, E-3(4‧-imidazolyl)propenoate or E-2,3-dimethylpropenoate] were successfully intercalated into Ca(II)Fe(III) layered double hydroxide (CaFe-LDH) verified by a range of instrumental methods. The possible arrangements for the organic anions were suggested on the basis of basal spacing data, layer thickness and the dimensions of the quantum chemically optimised structures of the acrylate ions. Using the acrylate-CaFe-LDHs as reactant-filled nanoreactors, photoinitiated topotactic [2 + 2] cyclisation reactions followed by IR spectroscopy could be performed with many representatives [E-phenylpropenoate-, E-3(4‧-nitrophenyl)propenoate-, E-3(2‧,5‧-difluorphenyl)propenoate- or E-3(2‧-thienyl)propenoate-CaFe-LDHs] resulting in cyclobutane derivatives within the layers of the host material indicating that there were domains where the intercalated anions were in close proximity to each other and in proper arrangement for the reaction to occur.

  7. [Role of layered double hydroxide (LDH) in the protection of herring testis DNA from heavy metals].

    Science.gov (United States)

    Tang, Yi-Ni; Wu, Ping-Xiao; Zhu, Neng-Wu

    2012-10-01

    The role of layered double hydroxide (LDH) in the protection of herring testis DNA from heavy metals Cd2+ and Pb2+ was studied by X-ray diffraction ( XRD) spectra, Fourier transform infrared (FTIR) spectra, Scanning Electron Microscopy (SEM), Cyclic Voltammetry and Ultraviolet Spectrometry. Size expansion of the basal spacing (003) from 0. 76 nm in LDH to 2. 30 nm was observed in the resulting DNA-LDH nanohybrids and it gave peaks corresponding to C=O (1 534 cm(-1) and 1488 cm(-1)) in skeleton and bases, C-O stretching vibration (1228 cm(-1)), and P-O symmetrical stretching vibration (1096 cm(-1)) in functional groups of DNA, indicating that DNA were intercalated into the LDH by the ion exchange. However, the displacement of NO3(-) was not fully complete (partial intercalation of DNA). The DNA outside LDH interlayers was absorbed on the surface of LDH. The cyclic voltammetric curves showed that DNA in the composites exhibited a very similar peaks, which corresponded to the two reduction current peaks (E(P) = - 1.2 mV and E(P) = -2.4 mV) of free DNA. Also there was no cathode sag emerging in cyclic voltammetric curves, suggesting that both Cd2+ and Pb2+ cannot insert into the groove of DNA to associate with base pairs or other groups when DNA was bound on LDH. The results showed that, on the one hand, both Cd2+ and Pb2+ were absorbed on the external surface of LDH for immobilization, on the other hand, the layer of LDH provided ideal space for DNA by the action of protecting DNA molecules from Cd2+ and Pb2+.

  8. Single and Double-Layer Antireflection Coatings on Silicon

    Science.gov (United States)

    Kavakli, Ýpek Gýrgýn; Kantarli, Kayhan

    2002-09-01

    In this study, the effect of single and double-layer thin film coatings on the reflectance spectrum of silicon surfaces has been investigated. Thin film coatings have been prepared by vacuum evaporation of the materials with suitable refractive index. Reflectance measurements in the visible and near infrared have shown that the coated samples acquire antireflection properties. Thickness and wavelength dependence of the antireflection properties of SiO, CeO2 and ZnS single-layer coatings with optical thickness of one quarter wavelength has been studied. In double-layer coatings, a thin film of SiO, CeO2 and ZnS with optical thickness of quarter wavelength were used as inner layer while a thin film of MgF2 with equal optical thickness was used as outer layer. It was shown that double-layer coatings can produce a significantly broader low reflectance region than does the single-layer coating. The results have been discussed by considering the zero reflectance conditions for the refractive index and the optical thickness of layers.

  9. FMR measurements on CoCr/NiFe double layers

    OpenAIRE

    Stam, M.T.H.C.W.; Gerritsma, G.J.; Lodder, J. C.; Popma, Th.J.A.

    1988-01-01

    CoCr/NiFe double layers were measured by ferromagnetic resonance (FMR) for different angles of the applied field. Several resonance curves were observed for CoCr, which are attributed to the different layers of a magnetically stratified CoCr. This was investigated by carrying out FMR measurements on a single CoCr sample and removing successive layers by ion beam milling. The origin of some of the curves is still unclear. One resonance curve is attributed to the top or bulk layer and another t...

  10. An experimental study on the preparation of tochilinite-originated intercalation compounds comprised of Fe 1-xS host layers and various kinds of guest layers

    Science.gov (United States)

    Peng, Yiya; Xi, Guangcheng; Zhong, Chang; Wang, Linping; Lu, Jun; Sun, Ximeng; Zhu, Lu; Han, Qikun; Chen, Lin; Shi, Lei; Sun, Mei; Li, Qianrong; Yu, Min; Yin, Mingwen

    2009-08-01

    Tochilinite represents a mineral group of ordered mixed-layer structures containing alternating Fe 1-xS layers with mackinawite-like structure and metal hydroxide layers with Mg(OH) 2-like structure. In this article, we report the preparation of a series of tochilinite-originated (or Fe 1-xS-based) intercalation compounds (ICs). According to their preparation procedures, these ICs can be divided into four kinds. The first kind of IC was sodium tochilinite (Na-tochilinite), which was prepared by the hydrothermal reaction of metallic Fe particles with concentrated Na 2S·9H 2O aqueous solutions. The hydroxide layer of the Na-tochilinite was a mixed hydroxide of Na + ions along with a certain amount of Fe 2+ ions. When the hydroxide layer of the Na-tochilinite completely dissolved in aqueous solutions, a Fe-deficient mackinawite-like phase Fe 1-xS was obtained, which was probably an electron-deficient p-type conductor. The second kind of ICs was prepared by 'low-temperature direct intercalation in aqueous solutions, using Na-tochilinite as a parental precursor. When the Na-tochilinite was ultrasonicated in aqueous solutions containing Lewis basic complexing agents (like NH 3, N 2H 4, 2,2'-bipyridine (bipy), and 1,10-phenanthroline (phen)), the Na + ions of the Na-tochilinite were removed and the Lewis basic complexing agents entered the hydroxide layer of the Na-tochilinite and became coordinated with the Fe 2+ ions, and the second kind of ICs was thus produced. The second kind of ICs includes NH 3 IC, N 2H 4 IC, N 2H 4-NH 3 IC, [Fe(bipy) 3] 2+-containing IC and [Fe(phen) 3] 2+-containing IC. The third kind of ICs, which includes NH 3 IC, N 2H 4-NH 3 IC and N 2H 4-LiOH (NaOH) IC, was prepared by the hydrothermal reaction of metallic Fe particles with (NH 4) 2S aqueous solution, S (elemental) + N 2H 4·H 2O aqueous solution, and S + N 2H 4·H 2O + LiOH (NaOH) aqueous solution, respectively. The third kind of ICs has a close relationship with the second kind of ICs both

  11. Zinc layered hydroxide salts: intercalation and incorporation into low-density polyethylene

    Directory of Open Access Journals (Sweden)

    Silvia Jaerger

    2014-12-01

    Full Text Available In this study, polymer composites using low-density polyethylene (LDPE and layered hydroxide salts (LHS were synthesized. The following compositions of LHS were obtained Zn5(OH8(An-2/n.yH2O, where A was varied in order to obtain hydrophilic (A = NO3- or hydrophobic (A = DDS- - dodecyl sulfate or DBS- - dodecyl benzene sulfonate. Synthesis was carried out by co-precipitation in alkaline medium and drying, being followed by characterization via Fourier-transform infrared spectroscopy, thermogravimetric analysis, X-ray diffraction and scanning electron microscopy. A variable amount of filler was then incorporated into the LDPE via extrusion, which was then injection molded to obtain specimens for evaluating tensile properties (Young's modulus, tensile strength, strain at break and toughness. For comparison, the sodium salts of the surfactants (NaDDS and NaDBS were also used as fillers in LDPE. The X-ray diffraction results indicated that the hydrophobic LHS were exfoliated in the polymer matrix, whereas the hydrophilic LHS was only delaminated. In the LDPE composites, melting and crystallization temperatures were nearly constant, along with the crystallinity indexes. The mechanical properties were mainly varied when the organophilic LHS was used. Overall, fillers based on LHS, especially those containing hydrophobic anions, may be interesting alternatives in the production of reinforced thermoplastics.

  12. USING COLLOIDAL LAYERED DOUBLE HYDROXIDES AS CATIONIC MICROPARTICULATE COMPONENT

    Institute of Scientific and Technical Information of China (English)

    Songlin Wang; Wenxia Liu

    2004-01-01

    Layered double hydroxides consisting of layers with cationic charges may be potential candidates of cationic microparticles forming synergetic retention effect with anionic polyacrylamide. In this work, the layered double hydroxides with various molar ratios of Mg/Al were synthesized by co-precipitation of magnesium chloride and aluminum chloride and peptized by intense washing with water. The chemical formula, particle size, Zeta potential of the layered double hydroxide were analyzed. It was found that positively charged magnesium aluminum hydroxide with particle diameter in nanoparticle size could be prepared. The Zeta potential and particle size vary with the feed molar ratio of Mg/Al and the peptizing process, respectively. The Zeta potential is also pH dependent. The retention experiments carried out on DDJ show that when used together with anionic polyacrylamide, the positively charged colloidal double hydroxide greatly improves the retention of reed pulps. The chemical formula, particle size and Zeta potential of the colloidal double hydroxide all affect its retention behavior.

  13. Double layer -- a particle accelerator in the magnetosphere

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Xiangrong [Los Alamos National Laboratory

    2015-07-16

    Slides present the material under the following topics: Introduction (What is a double layer (DL)? Why is it important? Key unsolved problems); Theory -- time-independent solutions of 1D Vlasov--Poisson system; Particle-in-cell simulations (Current-driven DLs); and Electron acceleration by DL (Betatron acceleration). Key problems include the generation mechanism, stability, and electron acceleration. In summary, recent observations by Van Allen Probes show large number of DLs in the outer radiation belt, associated with enhanced flux of relativistic electrons. Simulations show that ion acoustic double layers can be generated by field-aligned currents. Thermal electrons can gain energy via betatron acceleration in a dipole magnetic field.

  14. Electric double layer of anisotropic dielectric colloids under electric fields

    Science.gov (United States)

    Han, M.; Wu, H.; Luijten, E.

    2016-07-01

    Anisotropic colloidal particles constitute an important class of building blocks for self-assembly directed by electrical fields. The aggregation of these building blocks is driven by induced dipole moments, which arise from an interplay between dielectric effects and the electric double layer. For particles that are anisotropic in shape, charge distribution, and dielectric properties, calculation of the electric double layer requires coupling of the ionic dynamics to a Poisson solver. We apply recently proposed methods to solve this problem for experimentally employed colloids in static and time-dependent electric fields. This allows us to predict the effects of field strength and frequency on the colloidal properties.

  15. Theory of current-free double layers in plasmas

    Science.gov (United States)

    Goswami, K. S.; Saharia, K.; Schamel, H.

    2008-06-01

    The existence of current-free double layers in unmagnetized plasma is studied by means of the quasipotential method applied to the Vlasov-Poisson system. Crucial for its existence are trapped particle populations that are characterized by notches (dips) in the velocity distribution functions at resonant velocity becoming flat at large amplitude limit. The potential drop across the double layer, or its amplitude ψ, can be arbitrarily strong covering the whole range 0pressures. It is, hence, the effective electron (ion) temperature increase (decrease) with increasing potential, caused by the trapped particles, which is responsible for the existence of this two-parameter family of solutions.

  16. Insights from theory and simulation on the electrical double layer.

    Science.gov (United States)

    Henderson, Douglas; Boda, Dezso

    2009-05-28

    Despite the fact that our conceptual understanding of the electrical double layer has advanced during the past few decades, the interpretation of experimental and applied work is still largely based on the venerable Poisson-Boltzmann theory of Gouy, Chapman and Stern. This is understandable since this theory is simple and analytic. However, it is not very accurate because the atomic/molecular nature of the ions/solvent and their correlations are ignored. Simulation and some theoretical studies by ourselves and others that have advanced our understanding are discussed. These studies show that the GCS theory predicts a narrow double layer with monotonic profiles. This is not correct. The double layer is wider, and there can be substantial layering that would be even more pronounced if explicit solvent molecules are considered. For many years, experimental studies of the double layer have been directed to the use of electrochemistry as an analytical tool. This is acceptable for analytic chemistry studies. However, the understanding of electrochemical reactions that typically occur at the electrode surface, where simulation and theory indicate that the GCS theory can have substantial errors, requires modern approaches. New, fundamental experimental studies that would lead to deeper insights using more novel systems would be desirable. Further, biophysics is an interesting field. Recent studies of the selectivity of ion channels and of the adsorption of ions in a binding sites of a protein have shown that the linearized GCS theory has substantial errors.

  17. Double-layered cell transfer technology for bone regeneration.

    Science.gov (United States)

    Akazawa, Keiko; Iwasaki, Kengo; Nagata, Mizuki; Yokoyama, Naoki; Ayame, Hirohito; Yamaki, Kazumasa; Tanaka, Yuichi; Honda, Izumi; Morioka, Chikako; Kimura, Tsuyoshi; Komaki, Motohiro; Kishida, Akio; Izumi, Yuichi; Morita, Ikuo

    2016-09-14

    For cell-based medicine, to mimic in vivo cellular localization, various tissue engineering approaches have been studied to obtain a desirable arrangement of cells on scaffold materials. We have developed a novel method of cell manipulation called "cell transfer technology", enabling the transfer of cultured cells onto scaffold materials, and controlling cell topology. Here we show that using this technique, two different cell types can be transferred onto a scaffold surface as stable double layers or in patterned arrangements. Various combinations of adherent cells were transferred to a scaffold, amniotic membrane, in overlapping bilayers (double-layered cell transfer), and transferred cells showed stability upon deformations of the material including folding and trimming. Transplantation of mesenchymal stem cells from periodontal ligaments (PDLSC) and osteoblasts, using double-layered cell transfer significantly enhanced bone formation, when compared to single cell type transplantation. Our findings suggest that this double-layer cell transfer is useful to produce a cell transplantation material that can bear two cell layers. Moreover, the transplantation of an amniotic membrane with PDLSCs/osteoblasts by cell transfer technology has therapeutic potential for bone defects. We conclude that cell transfer technology provides a novel and unique cell transplantation method for bone regeneration.

  18. Influence of window layer thickness on double layer antirefiection coating for triple junction solar cells*

    Institute of Scientific and Technical Information of China (English)

    Wang Lijuan; Zhan Feng; Yu Ying; Zhu Yan; Liu Shaoqing; Huang Shesong; Ni Haiqiao; Niu Zhichuan

    2011-01-01

    The optimization of a SiO2/TiO2, SiO2/ZnS double layer antireflection coating (ARC) on Ga0.5ln0.5P/ln0.02Ga0.98As/Ge solar cells for terrestrial application is discussed. The Al0.5In0.5P window layer thickness is also taken into consideration. It is shown that the optimal parameters of double layer ARC vary with the thickness of the window layer.

  19. The electric double layer has a life of its own

    CERN Document Server

    Merlet, Céline; Salanne, Mathieu; Van Roij, René; Madden, Paul A; Chandler, David; Rotenberg, Benjamin

    2014-01-01

    Using molecular dynamics simulations with recently developed importance sampling methods, we show that the differential capacitance of a model ionic liquid based double-layer capacitor exhibits an anomalous dependence on the applied electrical potential. Such behavior is qualitatively incompatible with standard mean-field theories of the electrical double layer, but is consistent with observations made in experiment. The anomalous response results from structural changes induced in the interfacial region of the ionic liquid as it develops a charge density to screen the charge induced on the electrode surface. These structural changes are strongly influenced by the out-of-plane layering of the electrolyte and are multifaceted, including an abrupt local ordering of the ions adsorbed in the plane of the electrode surface, reorientation of molecular ions, and the spontaneous exchange of ions between different layers of the electrolyte close to the electrode surface. The local ordering exhibits signatures of a fir...

  20. Accessing the biocompatibility of layered double hydroxide by intramuscular implantation: histological and microcirculation evaluation

    Science.gov (United States)

    Cunha, Vanessa Roberta Rodrigues; de Souza, Rodrigo Barbosa; da Fonseca Martins, Ana Maria Cristina Rebello Pinto; Koh, Ivan Hong Jun; Constantino, Vera Regina Leopoldo

    2016-01-01

    Biocompatibility of layered double hydroxides (LDHs), also known as hydrotalcite-like materials or double metal hydroxides, was investigated by in vivo assays via intramuscular tablets implantation in rat abdominal wall. The tablets were composed by chloride ions intercalated into LDH of magnesium/aluminum (Mg2Al-Cl) and zinc/aluminum (Zn2Al-Cl). The antigenicity and tissue integration capacity of LDHs were assessed histologically after 7 and 28 days post-implantation. No fibrous capsule nearby the LDH was noticed for both materials as well any sign of inflammatory reactions. Sidestream Dark Field imaging, used to monitor in real time the microcirculation in tissues, revealed overall integrity of the microcirculatory network neighboring the tablets, with no blood flow obstruction, bleeding and/or increasing of leukocyte endothelial adhesion. After 28 days Mg2Al-Cl promoted multiple collagen invaginations (mostly collagen type-I) among its fragments while Zn2Al-Cl induced predominantly collagen type–III. This work supports previous results in the literature about LDHs compatibility with living matter, endorsing them as functional materials for biomedical applications. PMID:27480483

  1. Comparative study of Mg/Al- and Zn/Al-layered double hydroxide-perindopril erbumine nanocomposites for inhibition of angiotensin-converting enzyme

    Directory of Open Access Journals (Sweden)

    Hussein Al Ali SH

    2012-08-01

    Full Text Available Samer Hasan Hussein Al Ali,1 Mothanna Al-Qubaisi,2 Mohd Zobir Hussein,1,3 Maznah Ismail,2,4 Zulkarnain Zainal,1 Muhammad Nazrul Hakim51Department of Chemistry, Faculty of Science, 2Laboratory of Molecular Biomedicine, Institute of Bioscience, 3Advanced Materials and Nanotechnology Laboratory, Institute of Advanced Technology, 4Department of Nutrition and Health Science, 5Department of Biomedical Science, Faculty of Medicine and Health Science, Universiti Putra Malaysia, Selangor, MalaysiaAbstract: The intercalation of a drug active, perindopril, into Mg/Al-layered double hydroxide for the formation of a new nanocomposite, PMAE, was accomplished using a simple ion exchange technique. A relatively high loading percentage of perindopril of about 36.5% (w/w indicates that intercalation of the active took place in the Mg/Al inorganic interlayer. Intercalation was further supported by Fourier transform infrared spectroscopy, and thermal analysis shows markedly enhanced thermal stability of the active. The release of perindopril from the nanocomposite occurred in a controlled manner governed by pseudo-second order kinetics. MTT assay showed no cytotoxicity effects from either Mg/Al-layered double hydroxide or its nanocomposite, PMAE. Mg/Al-layered double hydroxide showed angiotensin-converting enzyme inhibitory activity, with 5.6% inhibition after 90 minutes of incubation. On incubation of angiotensin-converting enzyme with 0.5 µg/mL of the PMAE nanocomposite, inhibition of the enzyme increased from 56.6% to 70.6% at 30 and 90 minutes, respectively. These results are comparable with data reported in the literature for Zn/Al-perindopril.Keywords: magnesium, aluminum, layered double hydroxide, perindopril erbumine, ion exchange, angiotensin-converting enzyme, Chang cells line

  2. Damping of double wall panels including a viscothermal air layer

    NARCIS (Netherlands)

    Basten, T.G.H.; Stainhaouer, G.; Bakamidis, S.; Charalabopoulou, F.

    2001-01-01

    This paper deals with the dynamic behaviour of double wall panels, with emphasis on damping and sound radiation. It will be shown that a narrow air layer separating the two plates of a panel significantly alters the mentioned quantities by its viscothermal properties. Numerical and experimental resu

  3. Modeling Electric Double-Layers Including Chemical Reaction Effects

    DEFF Research Database (Denmark)

    Paz-Garcia, Juan Manuel; Johannesson, Björn; Ottosen, Lisbeth M.

    2014-01-01

    A physicochemical and numerical model for the transient formation of an electric double-layer between an electrolyte and a chemically-active flat surface is presented, based on a finite elements integration of the nonlinear Nernst-Planck-Poisson model including chemical reactions. The model works...

  4. Electric Double-Layer Capacitors Applying to Voltage Sag Compensator

    Science.gov (United States)

    Nara, Hidetaka

    Recently the electric double-layer capacitor (EDLC) which is rapidly charged and discharged and offers long life, maintenance-free, has been developed as a new energy storage element. Therefore, we developed the uninterruptible power supply as voltage sag compensator utilizing EDLC. This paper describes an abstract of EDLC and applying to voltage sag compensation.

  5. Recent progress in polymer/layered double hydroxide nanocomposites

    Institute of Scientific and Technical Information of China (English)

    DING Peng; CHEN Wei; QU Baojun

    2006-01-01

    New developments in the studies of nanocomposites based on polymer matrixes and layered double hydroxides (LDHs)in recent years are reviewed combining our relative research work, among which the synthesis techniques, the physicochemical characterizations, and the improved material properties are especially discussed. The possible application of polymer/LDH nanocomposites is also proposed.

  6. The electric double layer has a life of its own

    NARCIS (Netherlands)

    Merlet, Céline; Limmer, David T.; Salanne, Mathieu; Van Roij, René; Madden, Paul A.; Chandler, David; Rotenberg, Benjamin

    2014-01-01

    Using molecular dynamics simulations with recently developed importance sampling methods, we show that the differential capacitance of a model ionic liquid based double-layer capacitor exhibits an anomalous dependence on the applied electrical potential. Such behavior is qualitatively incompatible w

  7. USING COLLOIDAL LAYERED DOUBLE HYDROXIDES AS CATIONICMICROPARTICULATE COMPONENT

    Institute of Scientific and Technical Information of China (English)

    SonglinWang; WenxiaLiu

    2004-01-01

    Layered double hydroxides consisting of layers withcationic charges may be potential candidates ofcationic microparticles forming synergetic retentioneffect with anionic polyacrylamide. In this work, thelayered double hydroxides with various molar ratiosof Mg/AI were synthesized by co-precipitation ofmagnesium chloride and aluminum chloride and pep-tized by intense washing with water. The chemicalformula, particle size, Zeta potential of the layereddouble hydroxide were analyzed. It was found thatpositively charged magnesium aluminum hydroxidewith particle diameter in nanoparticle size could beprepared. The Zeta potential and particle size varywith the feed molar ratio of Mg/A1 and the peptizingprocess, respectively. The Zeta potential is also pHdependent. The retention experiments carried out onDDJ show that when used together with anionic poly-acrylamide, the positively charged colloidal doublehydroxide greatly improves the retention of reedpulps. The chemical formula, particle size and Zetapotential of the colloidal double hydroxide all affectits retention behavior.

  8. Molecular modeling of the structure and dynamics of the interlayer species of ZnAlCl layered double hydroxide.

    Science.gov (United States)

    Pisson, J; Morel, J P; Morel-Desrosiers, N; Taviot-Guého, C; Malfreyt, P

    2008-07-03

    Molecular dynamics simulations of the ZnAl layered double hydroxide containing interlayer chloride anions have been performed in the NpT and Np(zz)T statistical ensembles for metal Zn/Al ratios of 2 and 3. We have monitored the interlayer spacing as a function of the number of intercalated water molecules for each statistical ensemble. We have studied how these profiles are affected by the method of calculation of the charges of the hydroxide layer atoms. Diffusion coefficients of the interlayer water molecules have been calculated for different Zn/Al ratios. The calculation of the chemical potential of the interlayer water molecules has been carried out for three amounts of interlayer water molecules. The calculation showed a qualitative agreement with the bulk water chemical potential within a range of interlayer water molecule contents.

  9. Epigallocatechin Gallate/Layered Double Hydroxide Nanohybrids: Preparation, Characterization, and In Vitro Anti-Tumor Study.

    Directory of Open Access Journals (Sweden)

    Seyedeh Sara Shafiei

    Full Text Available In recent years, nanotechnology in merging with biotechnology has been employed in the area of cancer management to overcome the challenges of chemopreventive strategies in order to gain promising results. Since most biological processes occur in nano scale, nanoparticles can act as carriers of certain drugs or agents to deliver it to specific cells or targets. In this study, we intercalated Epigallocatechin-3-Gallate (EGCG, the most abundant polyphenol in green tea, into Ca/Al-NO3 Layered double hydroxide (LDH nanoparticles, and evaluated its efficacy compared to EGCG alone on PC3 cell line. The EGCG loaded LDH nanohybrids were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy (TEM and nanosizer analyses. The anticancer activity of the EGCG-loaded LDH was investigated in prostate cancer cell line (PC3 while the release behavior of EGCG from LDH was observed at pH 7.45 and 4.25. Besides enhancing of apoptotic activity of EGCG, the results showed that intercalation of EGCG into LDH can improve the anti- tumor activity of EGCG over 5-fold dose advantages in in-vitro system. Subsequently, the in-vitro release data showed that EGCG-loaded LDH had longer release duration compared to physical mixture, and the mechanism of diffusion through the particle was rate-limiting step. Acidic attack was responsible for faster release of EGCG molecules from LDH at pH of 4.25 compared to pH of 7.4. The results showed that Ca/Al-LDH nanoparticles could be considered as an effective inorganic host matrix for the delivery of EGCG to PC3 cells with controlled release properties.

  10. Insights into the synthesis of layered double hydroxide (LDH) nanoparticles: Part 2. Formation mechanisms of LDH.

    Science.gov (United States)

    Sun, Xiaodi; Dey, Sandwip K

    2015-11-15

    This study demonstrates the effect of (co)intercalated anion compositions on nanostructure evolution to understand the formation mechanisms of layered double hydroxide (LDH) nanoparticles following coprecipitation and hydrothermal treatments (HT). Initially, the room temperature coprecipitation resulted in amorphous primary nanoparticles that agglomerated at the edges due to low surface charge densities. The reversibility of such agglomeration was determined by the crystalline quality upon HT and consequent surface charge density, which in turn were strongly influenced by the composition of the intercalated anions. Upon crystallization, the agglomerated Zn2Al(OH)6(NO3)0.3(CO3)0.35⋅xH2O primary nanoparticles re-dispersed, but the Zn2Al(OH)6(NO3)⋅xH2O nanoparticles with much lower stability and higher disorder (especially at the edges) exhibited irreversible agglomeration, and transformed into secondary nanoparticles via aggregational growth. Additionally, the stability studies on Zn2Al(OH)6(NO3)y(CO3)0.5(1-y)⋅xH2O nanoparticles (y=0-1) showed that the size difference between the cointercalated anions caused phase separation when 0.9⩾y⩾0.6, leading to bimodal size distributions. Moreover, the coarsening rates were controlled through the cointercalated anion compositions. By gradually varying the ratio of cointercalated NO3(-) to CO3(2-), monodispersed Zn2Al(OH)6(NO3)y(CO3)0.5(1-y)⋅xH2O (0.5⩾y⩾0) nanoparticles with systematic variation in the particle size of ∼200-400nm were obtained after HT at 85°C for 12h.

  11. Electric-double-layer potential distribution in multiple-layer immiscible electrolytes

    NARCIS (Netherlands)

    Das, Siddhartha; Hardt, Steffen

    2011-01-01

    In this Brief Report, we calculate the electric-double-layer (EDL) electrostatic potential in a system of several layers of immiscible electrolytes. Verwey-Niessen theory predicts that at the interface between two immiscible electrolytes back-to-back EDLs are formed. The present analysis extends thi

  12. Potential for Layered Double Hydroxides-Based, Innovative Drug Delivery Systems

    Directory of Open Access Journals (Sweden)

    Kai Zhang

    2014-04-01

    Full Text Available Layered Double Hydroxides (LDHs-based drug delivery systems have, for many years, shown great promises for the delivery of chemical therapeutics and bioactive molecules to mammalian cells in vitro and in vivo. This system offers high efficiency and drug loading density, as well as excellent protection of loaded molecules from undesired degradation. Toxicological studies have also found LDHs to be biocompatible compared with other widely used nanoparticles, such as iron oxide, silica, and single-walled carbon nanotubes. A plethora of bio-molecules have been reported to either attach to the surface of or intercalate into LDH materials through co-precipitation or anion-exchange reaction, including amino acid and peptides, ATPs, vitamins, and even polysaccharides. Recently, LDHs have been used for gene delivery of small molecular nucleic acids, such as antisense, oligonucleotides, PCR fragments, siRNA molecules or sheared genomic DNA. These nano-medicines have been applied to target cells or organs in gene therapeutic approaches. This review summarizes current progress of the development of LDHs nanoparticle drug carriers for nucleotides, anti-inflammatory, anti-cancer drugs and recent LDH application in medical research. Ground breaking studies will be highlighted and an outlook of the possible future progress proposed. It is hoped that the layered inorganic material will open up new frontier of research, leading to new nano-drugs in clinical applications.

  13. Potential for layered double hydroxides-based, innovative drug delivery systems.

    Science.gov (United States)

    Zhang, Kai; Xu, Zhi Ping; Lu, Ji; Tang, Zhi Yong; Zhao, Hui Jun; Good, David A; Wei, Ming Qian

    2014-01-01

    Layered Double Hydroxides (LDHs)-based drug delivery systems have, for many years, shown great promises for the delivery of chemical therapeutics and bioactive molecules to mammalian cells in vitro and in vivo. This system offers high efficiency and drug loading density, as well as excellent protection of loaded molecules from undesired degradation. Toxicological studies have also found LDHs to be biocompatible compared with other widely used nanoparticles, such as iron oxide, silica, and single-walled carbon nanotubes. A plethora of bio-molecules have been reported to either attach to the surface of or intercalate into LDH materials through co-precipitation or anion-exchange reaction, including amino acid and peptides, ATPs, vitamins, and even polysaccharides. Recently, LDHs have been used for gene delivery of small molecular nucleic acids, such as antisense, oligonucleotides, PCR fragments, siRNA molecules or sheared genomic DNA. These nano-medicines have been applied to target cells or organs in gene therapeutic approaches. This review summarizes current progress of the development of LDHs nanoparticle drug carriers for nucleotides, anti-inflammatory, anti-cancer drugs and recent LDH application in medical research. Ground breaking studies will be highlighted and an outlook of the possible future progress proposed. It is hoped that the layered inorganic material will open up new frontier of research, leading to new nano-drugs in clinical applications.

  14. Synthesis of Layered Double Hydroxide Single-Layer Nanosheets in Formamide.

    Science.gov (United States)

    Yu, Jingfang; Liu, Jingjing; Clearfield, Abraham; Sims, Johnathan E; Speiegle, Michael T; Suib, Steven L; Sun, Luyi

    2016-11-21

    Layered double hydroxide (LDH) single-layer nanosheets were synthesized through a single-step process in the presence of formamide. This one-step process is simple, fast, and efficient and thus is potentially viable for large-scale production. Two key factors for the growth of LDH single-layer nanosheets, formamide concentration and LDH layer charge, were investigated thoroughly. A higher formamide concentration and a higher LDH layer charge are favorable for the growth of LDH single-layer nanosheets. The LDH single-layer nanosheets obtained at the premium formamide concentration and LDH layer charge were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and atomic force micrscopy (AFM). Poly(vinyl alcohol) (PVA)/LDH nanocomposite coatings were also prepared. The coated polyethylene terephthalate (PET) and poly(lactic acid) (PLA) films exhibited significantly improved oxygen gas barrier properties thanks to the well-dispersed and -aligned LDH single-layer nanosheets in the coating.

  15. Characterization of organic-inorganic hybrid layered perovskite and intercalated compound (n-C12H25NH3)2ZnCl4

    Science.gov (United States)

    Abdel-Kader, M. M.; Aboud, A. I.; Gamal, W. M.

    2016-05-01

    We report on some electrical properties and solid-solid phase transitions of organic-inorganic hybrid layered halide perovskite and intercalated compound (n-C12H25NH3)2ZnCl4 which is one member of the long-chain compounds of the series (n-CnH2n+1NH3)2,(n = 8-18). The complex dielectric permittivity ɛ*(ω,T) and the ac conductivity σ (ω,T) were measured as functions of temperature 100 K phase transition at T ≈ (362 ± 2) K, where the compound changes its state from intercalation to non-intercalation with a drastic increase in the c-axis by about 16.4%. The behavior of the frequency-dependent conductivity follows the Jonscher universal power law: σ (ω, T) αῳs(ῳ,T). The mechanism of electrical conduction in the low-temperature phase (phase II) can be described as quantum mechanical tunneling model.

  16. Deep Penetration of Spudcan Foundation into Double Layered Soils

    Institute of Scientific and Technical Information of China (English)

    LIU Jun; HU Yu-xia; KONG Xian-jing

    2005-01-01

    The spudcan foundation has been widely used in offshore engineering for jack-up rigs. However, "punch through"failure often occurs where a stronger soil layer overlays a softer soil layer. In this study, spudcan penetration into double layered soils is investigated numerically. The soil profile is set up as a stronger soil layer overlaying a softer soil layer,with the soil strength ratio ( bottom soil strength / top soil strength) varied from 0.1 to 1.0 ( 1 means uniform soil). The bearing behaviour is discussed and the bearing capacity factors are given for various cases involving different layer thicknesses and different strength ratios of the two clay layers. The development of the plastic zones and the effect of soil selfweight on the bearing capacity are also discussed. From this study, it is found that, when a spudcan is distant from the soil layer boundary, the spudcan can be analysed with single soil layer data. However, when a spudcan becomes closer to the soil boundary layer, the influence of the lower soft soil layer is significant, and the bearing capacity of the spudcan decreases. The critical distance is an indication of the occurrence of "punch through" failure. The critical distance between the spudcan and the layer boundary is larger for a rough spudcan than the one for a smooth one, and the critical distance decreases with increasing soil strength ratio. The depth of cavity formed during initial spudcan penetration depends on the top layer soil strength, soil strength ratio and unit soil self-weight, and the cavity affects the spudcan bearing behaviour as well.

  17. Self-assembling organomodified Co/Al based layered double hydroxides (LDH) via one-step route

    Institute of Scientific and Technical Information of China (English)

    WANG De-yi; A.LEUTERITZ; U.WAGENKNECHT; G.HEINRICH

    2009-01-01

    The preparation of self-assembling organomodified Co/Al-layered double hydroxide (LDH) via one-step route was studied.A common surfactant,sodium dodecylbenzenesulfonate (DBS),was employed as an organic modifier.The behavior and structure of self-assembled intercalated organic Co/Al-LDH were investigated by FTIR,SEM,WAXS,element analysis and TGA.Based upon the WAXS results and calculation by Bragg equation,the interlayer distance (d value) for organic Co/Al-LDH is enlarged from 0.75 nm to 3.10 nm,showing that the self-assembling behavior has been carried out successfully.Considering the observation from SEM,the product shows the morphology of organic Co/Al-LDH of a layered structure.In addition,FTIR,element analysis and TGA analysis show that the modifier is intercalated into the gallery of the Co/Al-LDH.Since organic modification for nanofiller is deemed to be necessary before applying it into polymer,the successful preparation of organomodified Co/Al-LDH will be significantly beneficial to the preparation and investigation of novel polymer/LDH nanocomposite.

  18. Effect of monobutylether ethylene glycol on Mg/Al layered double hydroxide: a physicochemical and conductivity study

    Energy Technology Data Exchange (ETDEWEB)

    Paulo, Maria Joao [Materiaux et Telecommunications, Institut National de la Rechercher Scientifique - Energie (Canada); Matos, Bruno Ribeiro de [Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP (Brazil); Ntais, Spyridon [Materiaux et Telecommunications, Institut National de la Rechercher Scientifique - Energie (Canada); Coral Fonseca, Fabio [Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP (Brazil); Tavares, Ana C., E-mail: tavares@emt.inrs.ca [Materiaux et Telecommunications, Institut National de la Rechercher Scientifique - Energie (Canada)

    2013-02-15

    Mg-Al hydrotalcite-like compounds with OH{sup -} ions intercalated in the gallery and modified with monobutylether ethylene glycol (mbeeg) were prepared from Mg{sub 6}Al{sub 2}(CO{sub 3})(OH){sub 16}{center_dot}4H{sub 2}O by the reconstruction method. The effect of the ethylene glycol, a moderate surfactant, on the textural properties and on the vapor water sorption of the layered double hydroxides was investigated by transmission electron microscopy and nitrogen and water sorption techniques. The ion conductivity of the samples was measured at 98 % RH up to 180 Degree-Sign C. The compounds are formed by nanoplatelets with a lateral size inferior to 20 nm. The addition of the ethylene glycol was found to increase the specific surface area, total pore volume, and water sorption capacity of the Mg-Al layered double hydroxide. However, it also decreased the average pore diameter, and the ion conductivity of the ethylene glycol modified layered double hydroxide was lower than expected based on the samples' specific surface area and water content.

  19. Effect of monobutylether ethylene glycol on Mg/Al layered double hydroxide: a physicochemical and conductivity study

    Science.gov (United States)

    Paulo, Maria Joao; de Matos, Bruno Ribeiro; Ntais, Spyridon; Fonseca, Fabio Coral; Tavares, Ana C.

    2013-02-01

    Mg-Al hydrotalcite-like compounds with OH- ions intercalated in the gallery and modified with monobutylether ethylene glycol ( mbeeg) were prepared from Mg6Al2(CO3)(OH)16·4H2O by the reconstruction method. The effect of the ethylene glycol, a moderate surfactant, on the textural properties and on the vapor water sorption of the layered double hydroxides was investigated by transmission electron microscopy and nitrogen and water sorption techniques. The ion conductivity of the samples was measured at 98 % RH up to 180 °C. The compounds are formed by nanoplatelets with a lateral size inferior to 20 nm. The addition of the ethylene glycol was found to increase the specific surface area, total pore volume, and water sorption capacity of the Mg-Al layered double hydroxide. However, it also decreased the average pore diameter, and the ion conductivity of the ethylene glycol modified layered double hydroxide was lower than expected based on the samples' specific surface area and water content.

  20. Shear deformation plate continua of large double layered space structures

    Science.gov (United States)

    Hefzy, Mohamed Samir; Nayfeh, Adnan H.

    1986-01-01

    A simple method is presented to model large rigid-jointed lattice structures as continuous elastic media with couple stresses using energy equivalence. In the analysis, the transition from the discrete system to the continuous media is achieved by expanding the displacements and the rotations of the nodal points in a Taylor series about a suitable chosen origin. The strain energy of the continuous media with couple stresses is then specialized to obtain shear deformation plate continua. Equivalent continua for single layered grids, double layered grids, and three-dimensional lattices are then obtained.

  1. Double layers in a modestly collisional electronegative discharge

    CERN Document Server

    Sheridan, T E

    1999-01-01

    The effect of ion-neutral collisions on the structure and ion flux emanating from a steady-state, planar discharge with two negative components is investigated. The positive ion component is modelled as a cold fluid subject to constant-mobility collisions, while the electrons and negative ions obey Boltzmann relations. The model includes the collisionless limit. When the negative ions are sufficiently cold three types of discharge structures are found. For small negative ion concentrations or high collisionality, the discharge is 'stratified', with an electronegative core and an electropositive edge. For the opposite conditions, the discharge is 'uniform' with the negative ion density remaining significant at the edge of the plasma. Between these cases lies the special case of a double-layer-stratified discharge, where quasi-neutrality is violated at the edge of the electronegative core. Double-layer-stratified solutions are robust in that they persist for moderate collisionality. Numerical solutions for fini...

  2. Superconductivity in Electric Double Layer Capacitor under Pressure

    Science.gov (United States)

    McCann, Duncan; Misek, Martin; Kamenev, Konstantin; Huxley, Andrew

    2015-03-01

    Chemical doping generally provides the most common method for tuning into the superconducting state of a material yet can be difficult to control and also potentially introduces structural disorder complicating the underlying physics. Electric Double Layer devices however provide a means to electrostatically dope materials with high electric fields allowing continuous tuning of a 2D superconducting state thus avoiding such issues. One such device is the Electric Double Layer Capacitor which can detect the onset of superconductivity through AC magnetisation measurements. We make use of a similar device in an attempt to electrostatically dope and tune the superconductivity in the cuprate compound La1.93Sr0.07CuO4 as well as investigating whether application of pressure improves its efficiency.

  3. Electrical power generation by mechanically modulating electrical double layers.

    Science.gov (United States)

    Moon, Jong Kyun; Jeong, Jaeki; Lee, Dongyun; Pak, Hyuk Kyu

    2013-01-01

    Since Michael Faraday and Joseph Henry made their great discovery of electromagnetic induction, there have been continuous developments in electrical power generation. Most people today get electricity from thermal, hydroelectric, or nuclear power generation systems, which use this electromagnetic induction phenomenon. Here we propose a new method for electrical power generation, without using electromagnetic induction, by mechanically modulating the electrical double layers at the interfacial areas of a water bridge between two conducting plates. We find that when the height of the water bridge is mechanically modulated, the electrical double layer capacitors formed on the two interfacial areas are continuously charged and discharged at different phases from each other, thus generating an AC electric current across the plates. We use a resistor-capacitor circuit model to explain the results of this experiment. This observation could be useful for constructing a micro-fluidic power generation system in the near future.

  4. Experimental investigation of current free double layers in helicon plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Sahu, B. B. [Department of Applied Sciences and Humanities, Dronacharya College of Engineering, Gurgaon 123506 (India); Tarey, R. D. [Department of Physics, Indian Institute of Technology, New Delhi 110016 (India); Ganguli, A. [Centre for Energy Studies, Indian Institute of Technology, New Delhi 110016 (India)

    2014-02-15

    The paper presents investigations of current free double layer (CFDL) that forms in helicon plasmas. In contrast to the other work reporting on the same subject, in the present investigations the double layer (DL) forms in a mirror-like magnetic field topology. The RF compensated Langmuir probe measurements show multiple DLs, which are in connection with, the abrupt fall of densities along with potential drop of about 24 V and 18 V. The DLs strengths (e ΔV{sub p})/(k T{sub e}) are about 9.5 and 6, and the corresponding widths are about 6 and 5 D lengths. The potential drop is nearly equal to the thermal anisotropies between the two plasma regions forming the DL, which is present in the plateau region of mirror, unlike the earlier studies on the DL formation in the region of strong gradients in the magnetic field. Also, it presents a qualitative discussion on the mechanism of DL formation.

  5. The mechanism of caesium intercalation of graphene.

    Science.gov (United States)

    Petrović, M; Šrut Rakić, I; Runte, S; Busse, C; Sadowski, J T; Lazić, P; Pletikosić, I; Pan, Z-H; Milun, M; Pervan, P; Atodiresei, N; Brako, R; Šokčević, D; Valla, T; Michely, T; Kralj, M

    2013-01-01

    Properties of many layered materials, including copper- and iron-based superconductors, topological insulators, graphite and epitaxial graphene, can be manipulated by the inclusion of different atomic and molecular species between the layers via a process known as intercalation. For example, intercalation in graphite can lead to superconductivity and is crucial in the working cycle of modern batteries and supercapacitors. Intercalation involves complex diffusion processes along and across the layers; however, the microscopic mechanisms and dynamics of these processes are not well understood. Here we report on a novel mechanism for intercalation and entrapment of alkali atoms under epitaxial graphene. We find that the intercalation is adjusted by the van der Waals interaction, with the dynamics governed by defects anchored to graphene wrinkles. Our findings are relevant for the future design and application of graphene-based nano-structures. Similar mechanisms can also have a role for intercalation of layered materials.

  6. Hydrothermal Synthesis of Ni/Al Layered Double Hydroxide Nanorods

    OpenAIRE

    Yun Zhao; Fenfei Xiao; Qingze Jiao

    2011-01-01

    Ni/Al layered double hydroxide (LDH) nanorods were successfully synthesized by the hydrothermal reaction. The crystal structure of the products was characterized by X-ray diffraction (XRD). The morphology of the products was observed using transmission electron microscopy (TEM) and field emission scanning electron microscopy (SEM). The influences of reaction time and pH value on the morphology of the Ni/Al LDHs were investigated. The result showed that the well-crystallized nanorods of Ni/Al ...

  7. Carrier relaxation time divergence in single and double layer cuprates

    Science.gov (United States)

    Schneider, M. L.; Rast, S.; Onellion, M.; Demsar, J.; Taylor, A. J.; Glinka, Y.; Tolk, N. H.; Ren, Y. H.; Lüpke, G.; Klimov, A.; Xu, Y.; Sobolewski, R.; Si, W.; Zeng, X. H.; Soukiassian, A.; Xi, X. X.; Abrecht, M.; Ariosa, D.; Pavuna, D.; Krapf, A.; Manzke, R.; Printz, J. O.; Williamsen, M. S.; Downum, K. E.; Guptasarma, P.; Bozovic, I.

    2003-12-01

    We report the transient optical pump-probe reflectivity measurements on single and double layer cuprate single crystals and thin films of ten different stoichiometries. We find that with sufficiently low fluence the relaxation time (tauR) of all samples exhibits a power law divergence with temperature (T): tauR ∝ T^{-3 ± 0.5}. Further, the divergence has an onset temperature above the superconducting transition temperature for all superconducting samples. Possible causes of this divergence are discussed.

  8. Selective oxidation catalysts obtained by immobilization of iron(III) porphyrins on thiosalicylic acid-modified Mg-Al layered double hydroxides.

    Science.gov (United States)

    de Freitas Castro, Kelly Aparecida Dias; Wypych, Fernando; Antonangelo, Ariana; Mantovani, Karen Mary; Bail, Alesandro; Ucoski, Geani Maria; Ciuffi, Kátia Jorge; Cintra, Thais Elita; Nakagaki, Shirley

    2016-09-15

    Nitrate-intercalated Mg-Al layered double hydroxides (LDHs) were synthesized and exfoliated in formamide. Reaction of the single layer suspension with thiosalicylic acid under different conditions afforded two types of solids: LDHA1, in which the outer surface was modified with the anion thiosalicylate, and LDHA2, which contained the anion thiosalicylate intercalated between the LDH layers. LDHA1 and LDHA2 were used as supports to immobilize neutral (FeP1 and FeP2) and anionic (FeP3) iron(III) porphyrins. For comparison purposes, the iron(III) porphyrins (FePs) were also immobilized on LDH intercalated with nitrate anions obtained by the co-precipitation method. Chemical modification of LDH facilitated immobilization of the FePs through interaction of the functionalizing groups in LDH with the peripheral substituents on the porphyrin ring. The resulting FePx-LDHAy solids were characterized by X-ray diffraction (powder) and UV-Vis and EPR spectroscopies and were investigated as catalysts in the oxidation of cyclooctene and cyclohexane. The immobilized neutral FePs and their homogeneous counterparts gave similar product yields in the oxidation of cyclooctene, suggesting that immobilization of the FePs on the thiosalicylate-modified LDHs only supported the catalyst species without interfering in the catalytic outcome. On the other hand, in the oxidation of cyclohexane, the thiosalicylate anions on the outer surface of LDHA1 or intercalated between the LDHA2 layers influenced the catalytic activity of FePx-LDHAy, leading to different efficiency and selectivity results. FeP1-LDHA2 performed the best (29.6% alcohol yield) due to changes in the polarity of the surface of the support and the presence of FeP1. Interestingly, FeP1 also performed better in solution as compared to the other FePs. Finally, it was possible to recycle FeP1-LDHA2 at least three times.

  9. Electrostatic supersolitons and double layers at the acoustic speed

    Energy Technology Data Exchange (ETDEWEB)

    Verheest, Frank, E-mail: frank.verheest@ugent.be [Sterrenkundig Observatorium, Universiteit Gent, Krijgslaan 281, B–9000 Gent (Belgium); School of Chemistry and Physics, University of KwaZulu-Natal, Durban 4000 (South Africa); Hellberg, Manfred A., E-mail: hellberg@ukzn.ac.za [School of Chemistry and Physics, University of KwaZulu-Natal, Durban 4000 (South Africa)

    2015-01-15

    Supersolitons are characterized by subsidiary extrema on the sides of a typical bipolar electric field signature or by association with a root beyond double layers in the fully nonlinear Sagdeev pseudopotential description. It has been proven that supersolitons may exist in several plasmas having at least three constituent species, but they cannot be found in weakly nonlinear theory. Another recent aspect of pseudopotential theory is that in certain plasma models and parameter regimes solitons and/or double layers can exist at the acoustic speed, having no reductive perturbation counterparts. Importantly, they signal coexistence between solitons having positive and negative polarity, in that one solution can be realized at a time, depending on infinitesimal perturbations from the equilibrium state. Weaving the two strands together, we demonstrate here that one can even find supersolitons and double layers at the acoustic speed, as illustrated using the model of cold positive and negative ions, in the presence of nonthermal electrons following a Cairns distribution. This model has been discussed before, but the existence and properties of supersolitons at the acoustic speed were not established at the time of publication.

  10. Preparation of layered double hydroxide/chlorophyll a hybrid nano-antennae: a key step.

    Science.gov (United States)

    Sommer Márquez, Alicia E; Lerner, Dan A; Fetter, Geolar; Bosch, Pedro; Tichit, Didier; Palomares, Eduardo

    2014-07-21

    In the first step to obtain an efficient nano-antenna in a bottom-up approach, new hybrid materials were synthesized using a set of layered double hydroxides (LDHs) with basic properties and pure chlorophyll a (Chl a). The stability of the adsorbed monolayer of Chl a was shown to be dependent on the nature and the ratio of the different metal ions present in the LDHs tested. The hybrid materials turned out to be adequate for stabilizing Chl a on Mg/Al LDHs for more than a month under ambient conditions while a limited catalytic decomposition was observed for the Ni/Al LDHs leading to the formation of pheophytin. These changes were followed by namely XRD, DR-UV-vis and fluorescence spectroscopies of the hybrid antennae and of the solutions obtained from their lixiviation with acetone or diethylether. On Mg/Al hydrotalcites the stability of the adsorbed Chl a was equivalent for values of the metal atom ratio ranging from 2 to 4. The latter hybrids should constitute a good basis to form efficient nanoscale light harvesting units following intercalation of selected dyes. This work describes an efficient preparation of Chl a that allows scale-up as well as the obtention of a stable Chl a monolayer on the surface of various LDHs.

  11. Layered Double Hydroxide Modified by PEGylated Hyaluronic Acid as a Hybrid Nanocarrier for Targeted Drug Delivery

    Institute of Scientific and Technical Information of China (English)

    董岸杰; 李雪; 王伟伟; 韩尚聪; 刘鉴锋; 刘金剑; 赵军强; 许舒欣; 邓联东

    2016-01-01

    In recent years, organic-inorganic hybrid nanocarriers are explored for effective drug delivery and pref-erable disease treatments. In this study, using 5-fluorouracil(5-FU)as electronegative model drug, a new type of organic-inorganic hybrid drug delivery system(LDH/HA-PEG/5-FU)was conceived and manufactured by the ad-sorption of PEGylated hyaluronic acid(HA-PEG)on the surface of layered double hydroxide(LDH, prepared via hydrothermal method)and the intercalation of 5-FU in the interlamination of LDH via ion exchange strategy. The drug loading amount of LDH/HA-PEG/5-FU achieved as high as 34.2%. LDH, LDH/5-FU and LDH/HA-PEG/5-FU were characterized by FT-IR, XRD, TGA, laser particle size analyzer and SEM. With the benefit of pH-degradable feature of LDH and enzyme-degradable feature of HA, LDH/HA-PEG/5-FU showed pH-degradable and enzyme-degradable capacity inin vitro drug release. Moreover, the drug carrier LDH/HA-PEG contained biocom-patible PEG and tumor-targeted HA, resulting in lower cytotoxicity and better endocytosis compared with LDHin vitro. It was suggested that the organic-inorganic hybrid drug delivery system, which was endowed with the proper-ties of controlled release, low toxicity and tumor-targeting delivery for ameliorative cancer therapy, was advisable and might be applied further to fulfill other treatments.

  12. Morphological control of layered double hydroxide through a biomimetic approach using carboxylic and sulfonic acids

    Directory of Open Access Journals (Sweden)

    Taishi Yokoi

    2015-09-01

    Full Text Available Layered double hydroxides (LDHs have intercalation properties and are used in various applications. The performances of the LDH materials can be improved by controlling crystal morphology. Morphology of inorganic crystals is controlled by organic molecules in biomineralization. Inspired by biomineralization, we investigated the effect of the addition of mono, di and triacids as morphological control agents on crystal morphology of LDH synthesized by the homogeneous precipitation method. Morphology of LDH was changed from hexagonal plate to stacked disc by addition of monoacids, namely acetic acid and methanesulfonic acid, in the reaction solution. Flower-shaped LDH crystals were formed in the presence of diacids and a triacid, namely succinic acid, 1,2-ethanedisulfonic acid and 1,2,3-propanetricarboxylic acid. We found that the morphology of the LDH crystals was controlled by the number of functional group on the morphological control agent rather than the type of functional group. These findings can contribute for the development of novel and functional LDH materials with precisely controlled morphology.

  13. Structure and thermal evolution of Mg-Al layered double hydroxide containing interlayer organic glyphosate anions

    Energy Technology Data Exchange (ETDEWEB)

    Li Feng; Zhang Lihong; Evans, David G.; Forano, Claude; Duan Xue

    2004-12-15

    Layered double hydroxide (LDH) with the Mg{sup 2+}/Al{sup 3+} molar ratio of 2.0 containing interlayer organic pesticide glyphosate anions (MgAl-Gly-LDH) has been synthesized by the use of anion exchange and coprecipitation routes. Intercalation experiments with glyphosate (Gly) reveal a correlation between the temperatures for thermal treatments and the types of reaction it undergoes with Gly. The grafting of the Gly anion onto hydroxylated sheets of LDH by moderate thermal treatments (hydrothermal treatments and calcinations) was confirmed by a combination of several techniques, including powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetry analysis (TGA-DTG), and {sup 31}P nuclear magnetic resonance (NMR). The thermal decomposition of MgAl-Gly-LDH results in the removal of loosely held interlayer water, grafting reaction between the interlayer anions and hydroxyl groups on the lattice of LDH, dehydroxylation of the lattice and decomposition of the interlayer species in succession, thus leading to a variety of crystallographic transitions.

  14. Study on Intercalative Nanohybrid of Cordycepin in Layered Double Hydroxide

    Institute of Scientific and Technical Information of China (English)

    Jian Ya LING; Jing YANG; Qin Zheng YANG; Jun Feng PENG; Han Xing ZHANG; Chang Kai ZHANG

    2003-01-01

    A novel negatively charged biomolecule-cordycepin has been intercalated within thegallery spaces of [Mg-Al-NO3]. Results of TEM, PXRD and FT-IR spectroscopy confirmed thatcordycepin could be intercalated into [Mg-Al-NO3] interlayers as the charge-compensating species.Initial studies suggest that the new bioinorganic nanocomposite may be used as a novel inorganicreservoir or carrier of pharmaceutically active compounds.

  15. Detection of polyaromatic hydrocarbons using DNA intercalation

    Energy Technology Data Exchange (ETDEWEB)

    Weetall, H.H.; Pandey, P.; Horuath, J. [National Institute of Standards and Technology, Gaithersburg, MD (United States)

    1995-12-01

    Polyaromatic hydrocarbons (PAH`S) have be monitored using intercalation of double stranded DNA. Three approaches have been examined. The first, an electrochemical method uses an electroactive intercalating agent. When intercalated into DNA it cannot transfer electrons to an electrode. When displaced by a PAH, it can be detected electrochemically. The second method utilizes fluorescence polarization. A fluorescent intercalating agent, when intercalated into DNA will show increased polarization. When displaced by a competing PAH, a decrease in polarization is observed. The third technique involves evanescent wave technology. Double stranded DNA in close proximity to the wave guide will show a decreased fluorescence when a fluorescent intercalator is displaced by a PAH. Each of these techniques will be described and examples of results presented.

  16. Synthesis and physical properties of new layered double hydroxides based on ionic liquids: Application to a polylactide matrix

    KAUST Repository

    Livi, Sébastien

    2012-12-01

    Ionic liquids based on tetraalkylphosphonium salts combined with different anions (decanoate and dodecylsulfonate) have been used as intercalating agents of layered double hydroxides (LDHs) by ion exchange. The synthesized phosphonium-treated LDHs display a dramatically improved thermal degradation and a significant increase in the interlayer distance as confirmed by thermogravimetric analysis (TGA) and X-ray Diffraction (XRD), respectively. To highlight the effect of thermostable ionic liquids, a very low amount of LDHs has been introduced within a polylactide (PLA) matrix and PLA/LDHs nanocomposites have been processed in melt by twin-screw extrusion. Then, transmission electron microscopy (TEM) analysis has been used to investigate the influence of ILs on the different morphologies of these nanocomposites. Even though the thermal stability of PLA matrix decreased, an excellent stiffness-toughness compromise has been obtained. © 2012 Elsevier Inc.

  17. Development of a biocompatible nanodelivery system for tuberculosis drugs based on isoniazid-Mg/Al layered double hydroxide.

    Science.gov (United States)

    Saifullah, Bullo; Arulselvan, Palanisamy; El Zowalaty, Mohamed Ezzat; Fakurazi, Sharida; Webster, Thomas J; Geilich, Benjamin M; Hussein, Mohd Zobir

    2014-01-01

    The primary challenge in finding a treatment for tuberculosis (TB) is patient non-compliance to treatment due to long treatment duration, high dosing frequency, and adverse effects of anti-TB drugs. This study reports on the development of a nanodelivery system that intercalates the anti-TB drug isoniazid into Mg/Al layered double hydroxides (LDHs). Isoniazid was found to be released in a sustained manner from the novel nanodelivery system in humans in simulated phosphate buffer solutions at pH 4.8 and pH 7.4. The nanodelivery formulation was highly biocompatible compared to free isoniazid against human normal lung and 3T3 mouse fibroblast cells. The formulation was active against Mycobacterium tuberculosis and gram-positive bacteria and gram-negative bacteria. Thus results show significant promise for the further study of these nanocomposites for the treatment of TB.

  18. Transport measurements on individual CuO 2 double layers

    Science.gov (United States)

    Mößle, M.; Kleiner, R.; Gatt, R.; Onellion, M.; Müller, P.

    2000-11-01

    Oxygen loss at the surface of Bi 2Sr 2CaCu 2O 8+ x single crystals provides CuO 2 layers with different critical temperatures. Particularly for overdoped crystals this allows to achieve a T c maximum near the surface. We performed transport measurements of this oxygen depleted layer. Samples were prepared by evaporating four Pb or Ag electrodes on top of freshly cleaved Bi 2Sr 2CaCu 2O 8+ x single crystals. Using overdoped crystals with a bulk T c of 55 to 60 K, the outermost layer was found to be underdoped with T c down to 30 K while the adjacent one was near optimal doping with T c between 80 and 90 K. The T c of the third layer was close to the bulk value. For temperatures above the bulk T c often only one CuO 2 double layer was found to be superconducting. We discuss current transport measurements with current flow along the CuO 2 layers.

  19. Large-amplitude double layers in a dusty plasma with an arbitrary streaming ion beam

    Indian Academy of Sciences (India)

    Brindaban Das; Debkumar Ghosh; Prasanta Chatterjee

    2010-06-01

    Formation of large-amplitude double layers in a dusty plasma whose constituents are electrons, ions, warm dust grains and positive ion beam are studied using Sagdeev’s pseudopotential technique. Existence of double layers is investigated. It is found that both the temperature of dust particles and ion beam temperature play significant roles in determining the region of the existence of double layers.

  20. Small amplitude ion-acoustic double layers with cold electron beam and q-nonextensive electrons

    Energy Technology Data Exchange (ETDEWEB)

    Ali Shan, S., E-mail: shaukatshan@gmail.com [Theoretical Plasma Physics Division, PINSTECH, Nilore, 44000 Islamabad (Pakistan); National Centre for Physics (NCP), Shahdra Valley Road, 44000 Islamabad (Pakistan); Department of Mathematics and Applied Physics (DPAM), PIEAS, Islamabad (Pakistan); Saleem, H., E-mail: saleemhpk@hotmail.com [National Centre for Physics (NCP), Shahdra Valley Road, 44000 Islamabad (Pakistan); Department of Mathematics and Applied Physics (DPAM), PIEAS, Islamabad (Pakistan)

    2014-02-01

    Small amplitude ion-acoustic double layers in an unmagnetized and collisionless plasma consisting of cold positive ions, q-nonextensive electrons, and a cold electron beam are investigated. Small amplitude double layer solution is obtained by expanding the Sagdeev potential truncated method. The effects of entropic index q, speed and density of cold electron beam on double layer structures are discussed.

  1. Tailoring surface properties and structure of layered double hydroxides using silanes with different number of functional groups

    Science.gov (United States)

    Tao, Qi; He, Hongping; Li, Tian; Frost, Ray L.; Zhang, Dan; He, Zisen

    2014-05-01

    Four silanes, trimethylchlorosilane (TMCS), dimethyldiethoxylsilane (DMDES), 3-aminopropyltriethoxysilane (APTES) and tetraethoxysilane (TEOS), were adopted to graft layered double hydroxides (LDH) via an induced hydrolysis silylation method (IHS). Fourier transform infrared spectra (FTIR) and 29Si MAS nuclear magnetic resonance spectra (29Si MAS NMR) indicated that APTES and TEOS can be grafted onto LDH surfaces via condensation with hydroxyl groups of LDH, while TMCS and DMDES could only be adsorbed on the LDH surface with a small quantity. A combination of X-ray diffraction patterns (XRD) and 29Si MAS NMR spectra showed that silanes were exclusively present in the external surface and had little influence on the long range order of LDH. The surfactant intercalation experiment indicated that the adsorbed and/or grafted silane could not fix the interlamellar spacing of the LDH. However, they will form crosslink between the particles and affect the further surfactant intercalation in the silylated samples. The replacement of water by ethanol in the tactoids and/or aggregations and the polysiloxane oligomers formed during silylation procedure can dramatically increase the value of BET surface area (SBET) and total pore volumes (Vp) of the products.

  2. Drug delivery system for an anticancer agent, chlorogenate-Zn/Al-layered double hydroxide nanohybrid synthesised using direct co-precipitation and ion exchange methods

    Energy Technology Data Exchange (ETDEWEB)

    Barahuie, Farahnaz [Materials Synthesis and Characterization Laboratory, Institute of Advanced Technology (ITMA), Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia); Hussein, Mohd Zobir, E-mail: mzobir@putra.upm.edu.my [Materials Synthesis and Characterization Laboratory, Institute of Advanced Technology (ITMA), Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia); Arulselvan, Palanisamy [Laboratory of Vaccines and Immunotherapeutics, Institute of Bioscience, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia); Fakurazi, Sharida [Laboratory of Vaccines and Immunotherapeutics, Institute of Bioscience, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia); Department of Human Anatomy, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia); Zainal, Zulkarnain [Materials Synthesis and Characterization Laboratory, Institute of Advanced Technology (ITMA), Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia)

    2014-09-15

    A nano-structured drug-inorganic clay hybrid involving an active anticancer compound, which is chlorogenic acid (CA) intercalated into Zn/Al-layered double hydroxide, has been assembled via ion-exchange and co-precipitation methods to form a nanohybrid CZAE (a chlorogenic acid-Zn/Al nanohybrid synthesised using an ion-exchange method) and CZAC (a chlorogenic acid-Zn/Al nanohybrid synthesised using a direct method), respectively. The X-ray diffraction (XRD) results confirmed that the CA-LDH had a hybrid structure in which the anionic chlorogenate is arranged between the interlayers as a horizontal monolayer at 90 and 20° angles from the x axis for CZAE and CZAC, respectively. Both nanohybrids have the properties of mesoporous materials. The high loading percentage of chlorogenic acid (approximately 43.2% for CZAE and 45.3% for CZAC) with basal spacings of 11.7 and 12.6 Å for CZAE and CZAC, respectively, corroborates the successful intercalation of chlorogenic acid into the interlayer gallery of layered double hydroxides. Free chlorogenic acid and the synthesised nanocomposites (CZAE, CZAC) were assessed for their cytotoxicity against various cancer cells. The Fourier transform infrared data supported the formation of both nanohybrids, and a thermal analysis showed that the nanohybrids are more thermally stable than their counterparts. The chlorogenate shows a sustained release, and the release rate of chlorogenate from CZAE and CZAC nanohybrids at pH 7.4 is remarkably lower than that at pH 4.8 due to their different release mechanisms. The release rate of chlorogenate from both nanohybrids can be described as pseudo-second order. The present investigation revealed the potential of the nanohybrids to enhance the in vitro anti-tumour effect of chlorogenic acid in liver and lung cancer cells in vitro. - Highlights: • We intercalated chlorogenic into Zn/Al-layered double hydroxide by ion-exchange and coprecipitation methods. • The two methods gave nanocomposites

  3. Synthesis, structure refinement and chromate sorption characteristics of an Al-rich bayerite-based layered double hydroxide

    Energy Technology Data Exchange (ETDEWEB)

    Britto, Sylvia, E-mail: sylviabritto11@gmail.com; Kamath, P. Vishnu

    2014-07-01

    “Imbibition” of Zn{sup 2+} ions into the cation vacancies of bayerite–Al(OH){sub 3} and NO{sub 3}{sup −} ions into the interlayer gallery yields an Al-rich layered double hydroxide with Al/Zn ratio ∼3. NO{sub 3}{sup −} ions are intercalated with their molecular planes inclined at an angle to the plane of the metal hydroxide slab and bonded to it by hydrogen bonds. Rietveld refinement of the structure shows that the monoclinic symmetry of the precursor bayerite is preserved in the product, showing that the imbibition is topochemical in nature. The nitrate ion is labile and is quantitatively replaced by CrO{sub 4}{sup 2−} ions from solution. The uptake of CrO{sub 4}{sup 2−} ions follows a Langmuir adsorption isotherm, thus showing that the hydroxide is a candidate material for green chemistry applications for the removal of CrO{sub 4}{sup 2−} ions from waste water. Rietveld refinement of the structure of the hydroxide after CrO{sub 4}{sup 2−} inclusion reveals that the CrO{sub 4}{sup 2−} ion is intercalated with one of its 2-fold axes parallel to the b-crystallographic axis of the crystal, also the principal 2 axis of the monoclinic cell. - Graphical abstract: The structure of the [Zn–Al4-nitrate] LDH viewed along the a-axis. - Highlights: • Synthesis of Al-rich layered double hydroxide with Al/Zn ratio ∼3. • Rietveld refinement indicates that the imbibition of Zn into Al(OH){sub 3} is topochemical in nature. • The uptake of CrO{sub 4}{sup 2−} ions follows a Langmuir adsorption isotherm.

  4. Removal of Naphthol Green B from Aqueous Solution by Calcined Layered Double Hydroxides:Adsorption Property and Mechanism Studies

    Institute of Scientific and Technical Information of China (English)

    ZHANG Feng; NI Zheming; XIA Shengjie; LIU Xiaoming; WANG Qiaoqiao

    2009-01-01

    The adsorption of naphthol green B(NGB)by Mg/Al-LDO(layered double oxides)with a Mg/Al molar ratio of librium is 193.4 mg and the percentage of absorption is 96.7%,with an adsorbent dose of 1.0 g/L under the following condition:200 mg/L NGB concentration,temperature 298 K,pH 10.0 and an equilibrium time of 80 min.Langmuir and Freundlich adsorption models were used for fitting the isotherms,and the thermodynamic parameters have been calculated,which showed that the adsorption process was spon 'taneous and exothermic in nature.In the light of so called "memory effect",the Mg/Al-LDO was found to recover their original layered structure after adsorption,and part of NGB ions intercalated into the interlayer of LDH(layered double hydroxides),which has been supported by XRD and FTIR.In addition,the competitive anions for adsorption and the regeneration of Mg/AI-LDO have also been investigated.

  5. Highly stable layered double hydroxide colloids: a direct aqueous synthesis route from hybrid polyion complex micelles.

    Science.gov (United States)

    Layrac, Géraldine; Destarac, Mathias; Gérardin, Corine; Tichit, Didier

    2014-08-19

    Aqueous suspensions of highly stable Mg/Al layered double hydroxide (LDH) nanoparticles were obtained via a direct and fully colloidal route using asymmetric poly(acrylic acid)-b-poly(acrylamide) (PAA-b-PAM) double hydrophilic block copolymers (DHBCs) as growth and stabilizing agents. We showed that hybrid polyion complex (HPIC) micelles constituted of almost only Al(3+) were first formed when mixing solutions of Mg(2+) and Al(3+) cations and PAA3000-b-PAM10000 due to the preferential complexation of the trivalent cations. Then mineralization performed by progressive hydroxylation with NaOH transformed the simple DHBC/Al(3+) HPIC micelles into DHBC/aluminum hydroxide colloids, in which Mg(2+) ions were progressively introduced upon further hydroxylation leading to the Mg-Al LDH phase. The whole process of LDH formation occurred then within the confined environment of the aqueous complex colloids. The hydrodynamic diameter of the DHBC/LDH colloids could be controlled: it decreased from 530 nm down to 60 nm when the metal complexing ratio R (R = AA/(Mg + Al)) increased from 0.27 to 1. This was accompanied by a decrease of the average size of individual LDH particles as R increased (for example from 35 nm at R = 0.27 down to 17 nm at R = 0.33), together with a progressive favored intercalation of polyacrylate rather than chloride ions in the interlayer space of the LDH phase. The DHBC/LDH colloids have interesting properties for biomedical applications, that is, high colloidal stability as a function of time, stability in phosphate buffered saline solution, as well as the required size distribution for sterilization by filtration. Therefore, they could be used as colloidal drug delivery systems, especially for hydrosoluble negatively charged drugs.

  6. Near infrared organic photodetector utilizing a double electron blocking layer.

    Science.gov (United States)

    Shafian, Shafidah; Hwang, Heewon; Kim, Kyungkon

    2016-10-31

    A near infrared organic photodiode (OPD) utilizing a double electron blocking layer (EBL) fabricated by the sequential deposition of molybdenum (VI) oxide (MoO3) and poly(3,4ethylenedioxythiophene):poly(styrene-sulfonate) (PEDOT:PSS) is reported. The double EBL improves the on/off current ratio of OPD up to 1.36 x 104 at -1V, which is one order of magnitude higher than PEDOT:PSS single EBL (2.45 x 103) and three orders of magnitude higher than that of MoO3 single EBL (7.86). The detectivity at near infrared (800 nm) at -1V is 4.90 x 1011 Jones, which is 2.83 times higher than the PEDOT:PSS single EBL and 2 magnitudes higher compared to the MoO3 single EBL.

  7. Tunable magnetic resonance in double layered metallic structures.

    Science.gov (United States)

    Zhou, L; Zhu, Y Y

    2011-12-01

    Double layered metallic gratings have been investigated both theoretically and experimentally. The authors have reported that tunable magnetic resonance (MR) can be achieved by modulating the vertical chirped width dh which could be controlled conveniently in the common electron and/or ion beam microfabrications. The linear relationship between MR wavelength and dh has been reported. By introducing the difference of electric and magnetic penetration depth, an analytic formula deduced from a modified LC model has shown good agreement with the simulation results, and an effective width for trapezoidal sandwiched microstructures has been presented. Our results may provide an alternative choice for tunable MR and broad bandwidth of magnetic metamaterials.

  8. LAYERED DOUBLE HYDROXIDES: NANOMATERIALS FOR APPLICATIONS IN AGRICULTURE

    Directory of Open Access Journals (Sweden)

    Luíz Paulo Figueredo Benício

    2015-02-01

    Full Text Available The current research aims to introduce Layered Double Hydroxides (LDH as nanomaterials to be used in agriculture, with particular reference to its use as storage and slow release matrix of nutrients and agrochemicals for plant growing. Structural characteristics, main properties, synthesis methods and characterization of LDH were covered in this study. Moreover, some literature data have been reported to demonstrate their potential for storage and slow release of nitrate, phosphate, agrochemicals, besides as being used as adsorbent for the wastewater treatment. This research aims to expand, in near future, the investigation field on these materials, with application in agriculture, increasing the interface between chemistry and agronomy.

  9. Carrier Rexlaxation Time Divergence in Single and Double Layer Cuprates.

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, M.; Rast, S.; Onellion, M.; Demsar, J.; Taylor, A. J.; Glinka, Y.; Tolk, N. H.; Ren, Y. H.; Lupke, G.; Klimov, A.; Sobolewski, R.; Xu, Y.; Si, Weidong; Zeng, X. H.; Soukiassian, A.; Xi, X. X.; Abrecht, M.; Ariosa, D.; Pavuna, D.; Drapf, A.; Manzke, R.; Printz, J. O.; Williamsen, M. S.; Downum, K. E.; Guptasarma, P.

    2003-06-20

    We report the transient optical pump-probe reflectivity measurements on single and double layer cuprate single crystals and thin films of ten different stoichiometries. We find that with sufficiently low fluence the relaxation time (tau [sub R] of all samples exhibits a power law divergence with temperature (T): tau [sub R] [proportional to] T[sup -3 [plus or minus] 0.5]. Further, the divergence has an onset temperature above the superconducting transition temperature for all superconducting samples. Possible causes of this divergence are discussed.

  10. Candidate organic electrolytes for electric double-layer capacitor application

    Institute of Scientific and Technical Information of China (English)

    B.Fang; Y.Wei; K.Suzuki; M.Kumagai

    2004-01-01

    Electrolytic conductivity,viscosity and electrochemical behavior were investigated for organic electrolytes based on PC(Propylene carbonate),MAN(Methoxy acetonitrile) and GBL(γ-Butyrolactone) solvents.It was found that 1 mol/L Et4NBF4-MAN had the highest conductivity,lowest viscosity and acceptable potential window.The specific capacitance and energy density obtained from the capacitor using 1 mol/L Et4NBF4-MAN as electrolyte were the highest among all the tested electrolytes.1 mol/L Et4NBF4-GBL also seemed promising to be used in electric double-layer capacitor (EDLCs).

  11. Electrochemical and Spectroscopic Analysis of Mg2+ Intercalation into Thin Film Electrodes of Layered Oxides: V2O5 and MoO3

    Energy Technology Data Exchange (ETDEWEB)

    Gershinsky, G; Yoo, HD; Gofer, Y; Aurbach, D

    2013-08-27

    Electrochemical, surface, and structural studies related to rechargeable Mg batteries were carried out with monolithic thin-film cathodes comprising layered V2O5 and MoO3. The reversible intercalation reactions of these electrodes with Mg ion in nonaqueous Mg salt solutions were explored using a variety of analytical tools. These included slow-scan rate cyclic voltammetry (SSCV), chrono-potentiometry (galvanostatic cycling), Raman and photoelectron spectroscopies, high-resolution microscopy, and XRD. The V2O5 electrodes exhibited reversible Mg-ion intercalation at capacities around 150-180 mAh g(-1) with 100% efficiency. A capacity of 220 mAh g(-1) at >95% efficiency was obtained with MoO3 electrodes. By applying the electrochemical driving force sufficiently slowly it was possible to measure the electrodes at equilibrium conditions and verify by spectroscopy, microscopy, and diffractometry that these electrodes undergo fully reversible structural changes upon Mg-ion insertion/deinsertion cycling.

  12. Layered double hydroxide catalyst for the conversion of crude vegetable oils to a sustainable biofuel

    Science.gov (United States)

    Mollaeian, Keyvan

    Over the last two decades, the U.S. has developed the production of biodiesel, a mixture of fatty acid methyl esters, using chiefly vegetable oils as feedstocks. However, there is much concern about the availability of high-quality vegetable oils for longterm biodiesel production. Problems have also risen due to the production of glycerol, an unwanted byproduct, as well as the need for process wash water. Therefore, this study was initiated to produce not only fatty acid methyl esters (FAMEs) but also fatty acid glycerol carbonates (FAGCs) by replacing methanol with dimethyl carbonate (DMC). The process would have no unnecessary byproducts and would be a simplified process compared to traditional biodiesel. In addition, this altering of the methylating agent could convert triglycerides, free fatty acids, and phospholipids to a sustainable biofuel. In this project, Mg-Al Layered Double Hydroxide (LDH) was optimized by calcination in different temperature varied from 250°C to 450°C. The gallery between layers was increased by intercalating sodium dodecylsulfate (SDS). During catalyst preparation, the pH was controlled ~10. In our experiment, triazabicyclodecene (TBD) was attached with trimethoxysilane (3GPS) as a coupling agent, and N-cetyl-N,N,N-trimethylammonium bromide (CTAB) was added to remove SDS from the catalyst. The catalyst was characterized by XRD, FTIR, and Raman spectroscopy. The effect of the heterogeneous catalyst on the conversion of canola oil, corn oil, and free fatty acids was investigated. To analyze the conversion of lipid oils to biofuel an in situ Raman spectroscopic method was developed. Catalyst synthesis methods and a proposed mechanism for converting triglycerides and free fatty acids to biofuel will be presented.

  13. Influence of localised double suction on a turbulent boundary layer

    Science.gov (United States)

    Oyewola, O.; Djenidi, L.; Antonia, R. A.

    2007-07-01

    The effects of localised suction applied through a pair of porous wall strips on a turbulent boundary layer have been quantified through the measurements of mean velocity and Reynolds stresses. The results indicate that the use of second strip extends the pseudo-relaminarisation zone but also reduces the overshoot in the longitudinal and normal r.m.s. velocities. While the minimum r.m.s. occurs at x/δo=3.0 (one strip) and x/δo=12 (two strips), the reduction observed for the latter case is larger. Relative to no suction, the turbulence level is modified by suction and the effect is enhanced with double suction. This increased effectiveness reflects the fact that the second strip acts on a boundary layer whose near-wall active motion has been seriously weakened by the first strip.

  14. A novel vibrational energy harvester with electric double layer electrets

    Science.gov (United States)

    Ono, S.; Miwa, K.; Iori, J.; Mitsuya, H.; Ishibashi, K.; Sano, C.; Toshiyoshi, H.; Fujita, H.

    2016-11-01

    We propose a new type of vibrational energy harvester with an electric double layer (EDL) electrets. Instead of using any external bias-voltage source or dielectric layer on top of the metal electrode to sustain EDL, we succeed to anchor the ions to polymer network to form the EDL electrets. By changing contact area between the EDL electrets and the electrode, large electric current is generated in the circuit. Owing to extremely large capacitance of the EDL electret, vibrational energy harvesters have the unique capability to leverage the high- density charge accumulation to the electrode and obtained current density becomes as high as 200 μA/cm2 with output voltage of 1V even with low frequency vibrations as low as 1 Hz.

  15. Structural characterisation of a layered double hydroxide nanosheet

    Science.gov (United States)

    Funnell, Nicholas P.; Wang, Qiang; Connor, Leigh; Tucker, Matthew G.; O'Hare, Dermot; Goodwin, Andrew L.

    2014-06-01

    We report the atomic-scale structure of a Zn2Al-borate layered double hydroxide (LDH) nanosheet, as determined by reverse Monte Carlo (RMC) modelling of X-ray total scattering data. This study involves the extension of the RMC method to enable structural refinement of two-dimensional nanomaterials. The refined LDH models show the intra-layer geometry in this highly-exfoliated phase to be consistent with that observed in crystalline analogues, with the reciprocal-space scattering data suggesting a disordered arrangement of the Zn2+ and Al3+ cations within the nanosheet. The approach we develop is generalisable and so offers a method of characterising the structures of arbitrary nanosheet phases, including systems that support complex forms of disorder within the nanosheets themselves.We report the atomic-scale structure of a Zn2Al-borate layered double hydroxide (LDH) nanosheet, as determined by reverse Monte Carlo (RMC) modelling of X-ray total scattering data. This study involves the extension of the RMC method to enable structural refinement of two-dimensional nanomaterials. The refined LDH models show the intra-layer geometry in this highly-exfoliated phase to be consistent with that observed in crystalline analogues, with the reciprocal-space scattering data suggesting a disordered arrangement of the Zn2+ and Al3+ cations within the nanosheet. The approach we develop is generalisable and so offers a method of characterising the structures of arbitrary nanosheet phases, including systems that support complex forms of disorder within the nanosheets themselves. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr01265h

  16. Interface phenomena in double-layer organic photoreceptors

    Science.gov (United States)

    Sasvari, G.; Juhasz, C.; Hirsch, J.

    1997-07-01

    Single photogeneration layers of a phthalocyanine pigment dispersed in a polyvinyl butyral binder, and double layers consisting of the photogeneration layer coated with hole transport layers of TPTA, DEH and BD molecularly dispersed in polycarbonate were exposed to single-shot light excitation. The charge collected was measured as a function of temperature, electric field, exposure intensity and duration. The resulting mean transport level of TPTA was found to be 0.17 eV, and that of DEH 0.11 eV, below the valence band of the pigment, but that of BD was found to be 0.09 eV above it. The injection efficiencies were independent of field and amounted to 0953-8984/9/30/015/img1 for TPTA and 0.02 for DEH, at room temperature, but that for BD was 0.1 independently of temperature. Models for the injection efficiencies in these cases are also discussed in this work for the first time.

  17. Physical properties of fixed-charge layer double hydroxides

    Science.gov (United States)

    Hines, D. R.; Solin, S. A.; Costantino, Umberto; Nocchetti, Morena

    2000-05-01

    The physical properties of a series of layer double hydroxides (LDH) of the form [(CO3)0.195(1-x)Cl0.39x(H2O)y]:[Zn0.61Al0.39(OH)2], 0layer water molecules form a hydration ring which defines the height of the solvated, nested Cl anion. The water molecules can tilt around their C2v axis such that the height of the solvated Cl ion is a function of the number of molecules forming the hydration ring. The composition dependence of the basal spacing, determined from x-ray-diffraction powder patterns measured as a function of humidity and temperature for these materials, is a function of both the Cl concentration (x) and the number of guest layer water molecules (y). Distinct basal spacing curves are observed for fully hydrated, partially hydrated, and dehydrated materials. At x=1 the Cl end-member material exhibits a change in stacking sequence from a 3R polytype to a 2H polytype upon dehydration. The dehydrated form of this material also exhibits a (3×3)R30° superlattice ordering of the Cl ions. Due to the nesting of the Cl ion and the active nature of the water molecules, the basal spacing vs x curve for the dehydrated materials is the only curve that can be fit by the discrete finite layer rigidity model. The interlayer rigidity parameter for LDH materials has been determined to be p=4.84+/-0.06 indicating that these materials are stiffer than class-II layered solids but not as stiff as class-III layered solids.

  18. Selectivity of Crystal Growth Direction in Layered Double Hydroxides

    Institute of Scientific and Technical Information of China (English)

    赵芸; 梁吉; 李峰; 段雪

    2004-01-01

    Investigation of selectivity of crystal growth direction in layered double hydroxides is helpful to control their particle sizes in different directions. Mg-Al layered double hydroxides (LDHs) were synthesized using a coprecipitation method. The influences of aging temperature, aging time, and Mg/Al molar ratio on the crystal structure, the LDHs particle size, and the selectivity of crystal growth in different directions were investigated. The results show that the size of the crystallites in the a direction is larger than that in the c direction for all experimental conditions, indicating faster crystal growth in the a direction than in the c direction. The crystallite sizes in the a and c directions both increase with decreasing Mg/Al molar ratio but with less difference between the sizes in the two directions. Therefore, the crystal growth rate in the c direction increases more than that in the a direction as the Mg/Al molar ratio decreases. The influence of the aging time, aging temperature, and Mg/Al molar ratio on the selectivity of the crystal growth direction can be used to prepare LDHs with selected sizes in the a and c directions.

  19. Resonance scattering characteristics of double-layer spherical particles

    Institute of Scientific and Technical Information of China (English)

    Xuejin Dong; Mingxu Su; Xiaoshu Cai

    2012-01-01

    Based on the principle of ultrasonic resonance scattering,sound-scattering characteristics of double-layer spherical particles in water were numerically studied in this paper.By solving the equations of the scattering matrix,the scattering coefficient determined by the boundary conditions can be obtained,thus the expression for the sound-scattering function of a single double-layer spherical particle can be derived.To describe the resonance scattering characteristics of a single particle,the reduced scattering cross section and reduced extinction cross section curves were found through numerical calculation.Similarly,the numerically calculated sound attenuation coefficient curves were used to depict the resonance scattering characteristics of monodisperse and polydisperse particles.The results of numerical calculation showed that,for monodisperse particles,the strength of the resonance was mainly related to the particle size and the total number of particles; while for polydisperse particles,it was primarily affected by the particle size,the coverage of the particle size distribution and the particle concentration.

  20. Partial double-layered patella in a nondysplasic adolescent.

    Science.gov (United States)

    García-Mata, Serafín; Hidalgo-Ovejero, Angel

    2016-11-01

    Double-layered patella (DLP) is a rare patella-formation abnormality reported in association with multiple epiphyseal dysplasia. DLP is one of the five types of bipartite patella, caused by a coronal septum that divides the patella into anterior and posterior segments. Although the double layer of bone has been reported as complete, it may also manifest as partial, as in our case. A 13-year-old male patient attended A&E after accidentally falling and sustaining a direct injury to his left knee, with pain in the anterior surface of the right patella. He was diagnosed with an incomplete vertical fracture of the left patella. An axial view radiography indicated an external partial DLP. No bone dysplasia was found. Computed tomographic scan and MRI showed partial DLP and bone marrow oedema because of the injury in the femoral condyle, but no fracture. The reason for highlighting this type of patella abnormality is to present the case of a patient without bone dysplasia, either partial or incomplete, that has not been reported previously. We also wish to emphasize the importance of not confusing it with a fracture in standard radiographies.

  1. Biodiesel synthesis using calcined layered double hydroxide catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Schumaker, J. Link [University of Kentucky; Crofcheck, Czarena [University of Kentucky; TAckett, S. Adam [University of Kentucky; Santillan-Jimenez, Eduardo [University of Kentucky; Morgan, Tonya [University of Kentucky; Ji, Yaying [University of Kentucky; Crocker, Mark [University of Kentucky; Toops, Todd J [ORNL

    2008-01-01

    The catalytic properties of calcined Li-Al, Mg-Al and Mg-Fe layered double hydroxides (LDHs) were examined in two transesterification reactions, namely, the reaction of glyceryl tributyrate with methanol, and the reaction of soybean oil with methanol. While the Li-Al catalysts showed high activity in these reactions at the reflux temperature of methanol, the Mg-Fe and Mg-Al catalysts exhibited much lower methyl ester yields. CO2 TPD measurements revealed the presence of sites of weak, medium and strong basicity on both Mg-Al and Li-Al catalysts, the latter showing higher concentrations of medium and strong base sites; by implication, these are the main sites active in transesterification catalyzed by calcined Li-Al LDHs. Maximum activity was observed for the Li-Al catalysts when a calcination temperature of 450-500 aC was applied, corresponding to decomposition of the layered double hydroxide to the mixed oxide without formation of crystalline lithium aluminate phases.

  2. Ru[(bpy)₂(dppz)]²⁺ and Rh[(bpy)₂(chrysi)]³⁺ targeting double strand DNA: the shape of the intercalating ligand tunes the free energy landscape of deintercalation.

    Science.gov (United States)

    Franco, Duvan; Vargiu, Attilio V; Magistrato, Alessandra

    2014-08-04

    Octahedral metal complexes can bind to double strand (ds) DNA either by intercalation or by insertion, this latter mechanism being observed in the case of mismatched base pairs (bps). In this work we modeled the process of deintercalation from the major groove for Δ-Ru[(bpy)2(dppz)](2+) (1) and Δ-Rh[(bpy)2(chrysi)](3+) (2), prototypical examples of metallo-intercalators and metallo-insertors, respectively. By using advanced sampling techniques, we show that the two complexes have comparable deintercalation barriers and that in both systems the main cost of deintercalation is due to disruption of π-π stacking interactions between the intercalating moiety and the bps flanking the binding site. A striking difference between dppz and chrysi is found in their intercalation modes, being their longest axes, respectively, perpendicular and parallel to the P-P direction between opposite DNA strands. This leads the two ligands to deintercalate from the DNA through different mechanisms. Compound 1 goes through the formation of a metastable short-lived intermediate, with an overall free energy barrier of ~14.5 kcal/mol, in line with experimental findings. Due to the length of the dppz intercalating moiety, an extended plateau appears in the free energy landscape at ~3 kcal/mol above the most stable minimum. Compound 2 must cross a similar barrier (~15.5 kcal/mol), but does not form intermediates along the deintercalation path, and the deintercalation profile is steeper than that found for 1. Thus, the shape of the intercalating moiety affects the deintercalation mechanism of these inorganic molecules. This work is a first step to rationalize from a computational perspective the factors tuning the preferential binding mode of inorganic molecules (such as diagnostic probes, therapeutic agents, or regulators of DNA expression) to ds DNA.

  3. Local anodic oxidation on hydrogen-intercalated graphene layers: oxide composition analysis and role of the silicon carbide substrate.

    Science.gov (United States)

    Colangelo, Francesco; Piazza, Vincenzo; Coletti, Camilla; Roddaro, Stefano; Beltram, Fabio; Pingue, Pasqualantonio

    2017-03-10

    We investigate nanoscale local anodic oxidation (LAO) on hydrogen-intercalated graphene grown by controlled sublimation of silicon carbide (SiC). Scanning probe microscopy was used as a lithographic and characterization tool in order to investigate the local properties of the nanofabricated structures. The anomalous thickness observed after the graphene oxidation process is linked to the impact of LAO on the substrate. Micro-Raman (μ-Raman) spectroscopy was employed to demonstrate the presence of two oxidation regimes depending on the applied bias. We show that partial and total etching of monolayer graphene can be achieved by tuning the bias voltage during LAO. Finally, a complete compositional characterization was achieved by scanning electron microscopy and energy dispersive spectroscopy.

  4. Local anodic oxidation on hydrogen-intercalated graphene layers: oxide composition analysis and role of the silicon carbide substrate

    Science.gov (United States)

    Colangelo, Francesco; Piazza, Vincenzo; Coletti, Camilla; Roddaro, Stefano; Beltram, Fabio; Pingue, Pasqualantonio

    2017-03-01

    We investigate nanoscale local anodic oxidation (LAO) on hydrogen-intercalated graphene grown by controlled sublimation of silicon carbide (SiC). Scanning probe microscopy was used as a lithographic and characterization tool in order to investigate the local properties of the nanofabricated structures. The anomalous thickness observed after the graphene oxidation process is linked to the impact of LAO on the substrate. Micro-Raman (μ-Raman) spectroscopy was employed to demonstrate the presence of two oxidation regimes depending on the applied bias. We show that partial and total etching of monolayer graphene can be achieved by tuning the bias voltage during LAO. Finally, a complete compositional characterization was achieved by scanning electron microscopy and energy dispersive spectroscopy.

  5. Characteristics of Double Tropopause Layers Observed During TORERO

    Science.gov (United States)

    Haggerty, J. A.; Mahoney, M. J.; Campos, T. L.; Pierce, B.; Volkamer, R. M.

    2012-12-01

    The existence of double tropopauses is indicated in data collected during the Tropical Ocean tRoposphere Exchange of Reactive halogen species and Oxygenated VOC (TORERO) experiment in January - February 2012. Airborne remote and in situ measurements from the NSF/NCAR Gulfstream V place tropopause heights at ~12-13 km and ~16-17 km during oceanic flights westward and southward from Antofagasta, Chile. Coastal radiosonde profiles confirm the locations of these tropopause layers. Various measurements define and characterize the transition layer between the upper troposphere and lower stratosphere. The Microwave Temperature Profiler (MTP), a scanning radiometer which measures emitted radiation at three frequencies, provides temperature vertical structure over a layer several kilometers above and below the aircraft with vertical resolution sufficient to resolve the tropopause. Tropopause height as determined from the temperature profile is based on the cold point and lapse rate transitions. In situ measurements of trace gases such as ozone, carbon monoxide, and water vapor also provide distinct signatures at the tropopause, although the aircraft did not always reach sufficient altitudes to detect the second tropopause. Model profiles of temperature and trace gases were also generated by the Real-time Air Quality Modeling System (RAQMS) during TORERO. RAQMS is a global meteorological, chemical and aerosol assimilation/forecasting system that assimilates real-time stratospheric ozone retrievals from the Microwave Limb Sounder (MLS), total column ozone from the Ozone Monitoring Instrument (OMI), and aerosol optical depth (AOD) from the Moderate Resolution Imaging Spectroradiometer (MODIS). In this paper, observations of the TORERO double tropopause features as defined by temperature and trace gas profiles are presented and compared to model-defined tropopause properties.

  6. Weak localization in electric-double-layer gated few-layer graphene

    Science.gov (United States)

    Gonnelli, R. S.; Piatti, E.; Sola, A.; Tortello, M.; Dolcini, F.; Galasso, S.; Nair, J. R.; Gerbaldi, C.; Cappelluti, E.; Bruna, M.; Ferrari, A. C.

    2017-09-01

    We induce surface carrier densities up to  ˜7\\centerdot {{10}14} cm-2 in few-layer graphene devices by electric double layer gating with a polymeric electrolyte. In 3-, 4- and 5-layer graphene below 20-30 K we observe a logarithmic upturn of resistance that we attribute to weak localization in the diffusive regime. By studying this effect as a function of carrier density and with ab initio calculations we derive the dependence of transport, intervalley and phase coherence scattering lifetimes on total carrier density. We find that electron-electron scattering in the Nyquist regime is the main source of dephasing at temperatures lower than 30 K in the  ˜1013 cm-2 to  ˜7\\centerdot {{10}14} cm-2 range of carrier densities. With the increase of gate voltage, transport elastic scattering is dominated by the competing effects due to the increase in both carrier density and charged scattering centers at the surface. We also tune our devices into a crossover regime between weak and strong localization, indicating that simultaneous tunability of both carrier and defect density at the surface of electric double layer gated materials is possible.

  7. Nanosized Ni–Al layered double hydroxides—Structural characterization

    Energy Technology Data Exchange (ETDEWEB)

    Jitianu, Mihaela, E-mail: jitianum@wpunj.edu [William Paterson University, Department of Chemistry, 300 Pompton Road, Wayne, NJ 07470 (United States); Gunness, Darren C. [William Paterson University, Department of Chemistry, 300 Pompton Road, Wayne, NJ 07470 (United States); Aboagye, Doreen E. [Lehman College – City University of New York, Department of Chemistry, Davis Hall, 250 Bedford Boulevard West, Bronx, NY 10468 (United States); Zaharescu, Maria [Institute of Physical Chemistry, 202 Splaiul Independentei, 060021 Bucharest (Romania); Jitianu, Andrei, E-mail: andrei.jitianu@lehman.cuny.edu [Lehman College – City University of New York, Department of Chemistry, Davis Hall, 250 Bedford Boulevard West, Bronx, NY 10468 (United States)

    2013-05-15

    Highlights: ► The takovite anionic clays were obtained using the sol–gel method. ► The effect of samples’ composition on the structural and textural characteristics has been investigated. ► X-ray analysis. ► FTIR spectroscopy evidenced a disordered interlayer structure. ► FESEM and TEM analysis showed that the samples have high porosity. - Abstract: Takovite, a natural mineral with the formula Ni{sub 6}Al{sub 2}(OH){sub 6}CO{sub 3}·5H{sub 2}O belongs to the large class of layered double hydroxides (LDHs) and contains positively charged Ni(II) and Al(III) layers alternating with layers containing carbonate ions and water molecules. Mesoporous takovite-type layered double hydroxides (LDH) of the general formula [Ni{sub 1−x}Al{sub x}(OH){sub 2}]{sup x+}(CO{sub 3}{sup 2−}){sub x/2}·nH{sub 2}O with different Ni/Al molar ratios (1.9–2.8) have been successfully synthesized by the sol–gel method, followed by anionic exchange using nickel acetylacetonate and aluminum isopropylate as cation precursors. A single LDH phase and an anisotropic growth of very small crystallites (below 4 nm) have been evidenced by X-ray diffraction. The effect of samples’ composition on their structural and textural characteristics has been investigated. The BET surface area values are in the range of 100–122 m{sup 2}/g. BJH pore radius decreased with increase in the Al(III) content in the LDHs. FESEM micrographs show large aggregates of highly porous LDH particles, while TEM analysis reveals irregular agglomerates of crystallites, among which some of them displayed a developing hexagonal shape. The average particle size variation with the Al(III) content in the samples follows the same trend as the pore radius, the sample with the highest Ni/Al ratio displaying also the smallest particle size. This sample becomes even more interesting, since TEM analysis shows agglomerates with inside circular structures, feature not observed for the other Ni/Al ratios investigated.

  8. Inference of Polymer Adsorption from Electrical Double Layer Measurements : the Silver Iodide-Polyvinyl Alcohol System

    NARCIS (Netherlands)

    Koopal, L.K.

    1978-01-01

    The purpose of this study was to investigate how the double layer properties of charged particles are modified by the presence of adsorbed polymer molecules and to obtain information on the conformation of the polymer layer from the observed alterations in the double layer properties.In chapter 1. t

  9. Biological evaluation of layered double hydroxides as efficient drug vehicles

    Energy Technology Data Exchange (ETDEWEB)

    Li Yan; Liu Dan; Chang Qing; Liu Dandan; Xia Ying; Liu Shuwen; Peng Nanfang; Yang Xu [Hubei Key Laboratory of Genetic Regulation and Integrative Biology, College of Life Science, Huazhong Normal University, Wuhan 430079 (China); Ai Hanhua [College of Physical Science and Technology, Huazhong Normal University, Wuhan 430079 (China); Xi Zhuge, E-mail: yangxu@mail.ccnu.edu.cn [Tianjin Institutes of Health and Environmental Medicine, Tianjin 300050 (China)

    2010-03-12

    Recently there has been a rapid expansion of the development of bioinorganic hybrid systems for safe drug delivery. Layered double hydroxides (LDH), a variety of available inorganic matrix, possess great promise for this purpose. In this study, an oxidative stress biomarker system, including measurement of reactive oxygen species, glutathione content, endogenous nitric oxide, carbonyl content in proteins, DNA strand breaks and DNA-protein crosslinks, was designed to evaluate the biocompatibility of different concentrations of nano-Zn/Al-LDH with a Hela cell line. The drug delivery activity of the LDH-folic-acid complex was also assessed. The resulting data clearly demonstrated that nano-LDH could be applied as a relatively safe drug vehicle with good delivery activity, but with the caveat that the effects of high dosages observed here should not be ignored when attempting to maximize therapeutic activity by increasing LDH concentration.

  10. Hydrothermal Synthesis of Ni/Al Layered Double Hydroxide Nanorods

    Directory of Open Access Journals (Sweden)

    Yun Zhao

    2011-01-01

    Full Text Available Ni/Al layered double hydroxide (LDH nanorods were successfully synthesized by the hydrothermal reaction. The crystal structure of the products was characterized by X-ray diffraction (XRD. The morphology of the products was observed using transmission electron microscopy (TEM and field emission scanning electron microscopy (SEM. The influences of reaction time and pH value on the morphology of the Ni/Al LDHs were investigated. The result showed that the well-crystallized nanorods of Ni/Al LDHs could be obtained when the pH value was about 10.0 with a long reaction time (12–18 h at 180°C.

  11. Electric Double-layer Capacitor Based on Activated Carbon Material

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In this study electric double-layer capacitors (EDLCs) based on activated carbon material and organic electrolyte (tetraethyl ammonium tetrafluoroborate) were explored. The fabrication method for EDLC is presented and the performance of EDLC was examined by using the cyclic voltammetry, constant-current charging and discharging technique, electrochemical impedance spectroscopy measurements. Influence of various components and design parameters on the performance of the capacitors were preliminarily investigated. Up to now, EDLC based on carbon materials can deliver 20.7 W/kg at the discharge rate ofI=0.3 mA, together with the energy density of 8.5 Wh/kg. Equivalent series resistance (ESR) is 0.716 Ω.cm2. The specific power of the capacitor is low and further attempts to raise the power capability of the capacitors are necessary. Some considerations are put forward to further improve the performance of EDLC.

  12. Prediction of Double Layer Grids' Maximum Deflection Using Neural Networks

    Directory of Open Access Journals (Sweden)

    Reza K. Moghadas

    2008-01-01

    Full Text Available Efficient neural networks models are trained to predict the maximum deflection of two-way on two-way grids with variable geometrical parameters (span and height as well as cross-sectional areas of the element groups. Backpropagation (BP and Radial Basis Function (RBF neural networks are employed for the mentioned purpose. The inputs of the neural networks are the length of the spans, L, the height, h and cross-sectional areas of the all groups, A and the outputs are maximum deflections of the corresponding double layer grids, respectively. The numerical results indicate that the RBF neural network is better than BP in terms of training time and performance generality.

  13. Structure and Capacitance of Electrical Double Layers inside Micropores

    Science.gov (United States)

    Feng, Guang; Qiao, Rui; Huang, Jingsong; Sumpter, Bobby G.; Meunier, Vincent

    2010-03-01

    Recent experiments indicate that the specific capacitance of micropores (diameter less than 2nm) increases anomalously as the pore size decreases^[1]. To understand the physical origin of this discovery, we performed a series of molecular dynamics simulations to study the electrical double layers (EDLs) in micropores with different shapes (tube vs slit) and pore sizes (0.668nm - 3.342nm). Several different aqueous electrolytes (K^+, Na^+, Cl^-, and F^- in water) were used in these micropores. We quantified the structure of EDLs inside the pores, and computed the capacitance of EDLs. The scaling of capacitance shows a qualitative agreement with the experimental observations. We attribute the anomalous enhancement of capacitance in micropores to the short-range ionelectrode and ionsolvent interactions.[1] J. Chmiola, G. Yushin, Y. Gogotsi, C. Portet, P. Simon, and P.L. Taberna, Science 2006, 313, 1760.

  14. pH-dependent assembly of two inorganic-organic hybrid compounds based on octamolybdates: an unusual intercalated layer and a 3D 4-connected framework.

    Science.gov (United States)

    Liu, Hai-Yan; Yang, Jin; Liu, Ying-Ying; Ma, Jian-Fang

    2012-09-07

    Two novel inorganic-organic hybrid compounds based on octamolybdates, namely, [Cu(H(2)L)(2)(γ-Mo(8)O(26))]·(Mo(6)O(19))·2H(2)O (1) and [Cu(H(2)L)(γ-Mo(8)O(26))(H(2)O)(2)]·5H(2)O (2), where L = 1,1'-(1,5-pentanediyl)bis[2-(4-pyridyl)benzimidazole], have been successfully synthesized at different pH values under hydrothermal conditions. Compound 1, which is hydrothermally prepared at pH ≈ 3.5, exhibits an entirely new type of intercalated layer. The nanosized hexamolybdate anions as guests are introduced into the layers. When the pH value is adjusted to 2, a structurally-different complex 2 was obtained. Compound 2 shows a unique 3D 4-connected framework constructed by inorganic layers and H(2)L(2+) ligands as bridges. The two compounds were characterized by elemental analyses, IR spectra and TGA. In addition, the electrochemical properties of 1-modified carbon paste electrode (CPE) have also been investigated in 1 M H(2)SO(4) aqueous solution.

  15. Nanohybrid based on antibiotic encapsulated layered double hydroxide as a drug delivery system.

    Science.gov (United States)

    Khan, Sher Bahadar; Alamry, Khalid A; Alyahyawi, Nedaa A; Asiri, Abdullah M; Arshad, Muhammad Nadeem; Marwani, Hadi M

    2015-02-01

    Nanohybrid of cefuroxime (CFO) with layered double hydroxide (LDH) has been prepared, and the rate of dissolution and bioavailability of CFO using nanohybrid as a drug delivery system has been broadly studied. The intercalation process was confirmed by X-ray diffraction, Fourier transform infrared spectroscopy, and thermogravimetric analysis. The CFO contents were found to be 19.0 wt% in the nanohybrid. The release mechanism of CFO was investigated with respect to anion and pH of the dissolution media such as gastric, intestinal and blood simulated media. The effect of pH was evaluated on the release of CFO from nanohybrid, and the dissolution of CFO from the nanohybrid was found to be a slow process at pH 4.0, 6.8, and 7.4. Further the addition of Cl ion and PAM in release media did not affect the release rate of drug at pH 4.0 and 6.8, while at pH 7.4, Cl ion and PAM have significant role on the drug release. At pH 1.2, the release study shows that LDH dissolved in the acidic medium and CFO released in its molecular form. The release behavior suggests two mechanisms that are responsible for the release of CFO from nanohybrid: weathering (dependent on the pH) and ion exchange (highly dependent on the anions). Surface reactions mediated by solid weathering ruled the release in gastric fluid, whereas anion exchange determined CFO release in lysosomal, intestinal, and blood medium. In order to evaluate the drug release mechanism, the released data were fitted by mathematical models describing various kinetic.

  16. Comparative X-ray diffraction and infrared spectroscopy study of Zn-Al layered double hydroxides: Vanadate vs nitrate

    Science.gov (United States)

    Salak, Andrei N.; Tedim, João; Kuznetsova, Alena I.; Ribeiro, José L.; Vieira, Luís G.; Zheludkevich, Mikhail L.; Ferreira, Mário G. S.

    2012-03-01

    Zn-Al layered double hydroxides (LDH) are promising as nanocontainers of corrosion inhibitors in self-healing corrosion protection coatings. Zn(2)Al-vanadate (Zn/Al = 2:1) is prepared by anion exchange from the parent composition Zn(2)Al-nitrate at pH ˜ 8. Crystal structure and vibrational spectra of both LDHs have been studied in comparison. Their interlayer distances are rather larger than those corresponding to the most compact arrangement of the intercalated anions. Nevertheless, no sign of a turbostratic disorder has been detected in these LDH. Based on the analysis of the spectroscopic data in combination with the XRD results, it has been shown that vanadate anion, which substitutes nitrate at the anion exchange, is pyrovanadate, VO74-. The observed disorder in the hydroxide layers in Zn(2)Al-V2O7 is likely to result from strong interactions between V5+ and Zn2+/Al3. Although Zn(2)Al-NO3 is less disordered than Zn(2)Al-V2O7, it exhibits no long-range order in arrangement of cations in the hydroxide layers.

  17. Layered double hydroxides as electrode materials for Ni based batteries and as novel inorganic/organic hybrid materials

    Energy Technology Data Exchange (ETDEWEB)

    Caravaggio, G.

    2002-07-01

    This study examined the electrochemical properties of layered double hydroxides (LDH) in half-cells to determine if they can be used in nickel-cadmium (Ni-Cd) and nickel-metal hydride (NiMH) batteries. The LDHs were prepared by coprecipitation and were characterized by X-ray diffraction analysis. The nickel-aluminium LDHs were found to be the most stable during potassium hydroxide electrolyte discharge because the aluminium acted in a two fold manner. The high charge to radius ratio increased the electrostatic interaction between the anions and the metal layers. The acidity of the hydroxyl groups was due to the high exchange of electrons. The powders had lower discharge capacity compared to commercial electrode materials because of their low density. The nickel-vanadium LDHs exchanged only up to 1.2 electrons and were stable only up to a maximum of 14 days in electrolytic solutions of the cells. Zinc-aluminium LDHs were also synthesized and intercalated with phenyl phosphonic acid or 1,4-phenylene bis phosphonic acid to create microporous materials. X-ray diffraction, infra-red spectroscopy and nuclear magnetic resonance was used to characterize the compounds and determine crystallographic spacing. Grafting of both phosphonates to the metal layers had occurred and both materials showed little or no microporosity.

  18. Layered double oxide (LDO) particle containing photoreactive hybrid layers with tunable superhydrophobic and photocatalytic properties

    Science.gov (United States)

    Deák, Ágota; Janovák, László; Csapó, Edit; Ungor, Ditta; Pálinkó, István; Puskás, Sándor; Ördög, Tibor; Ricza, Tamás; Dékány, Imre

    2016-12-01

    Inorganic/organic hybrid layers have been prepared having superhydrophobic as well as photoreactive properties. The hybrid thin films with micro- and nanosized dual-scale surface roughness consist of ∼25 μm layered double oxide (LDO) photocatalyst particles and low surface energy poly(perfluorodecyl acrylate) [p(PFDAc)] fluoropolymer binder material. The application of [p(PFDAc)] resulted in the decrease in the surface free energy of the hydrophilic LDO. The structured surface LDO with ∼12% ZnO phase content were synthesized from layer double hydroxide (LDH) spheres. The determined excitation wavelength and the calculated band gap energy values were 386 nm and 3.23 eV, respectively. The hybrid thin films were prepared by a simple spray-coating method, which is a low-cost, fast and scalable film-forming technique. The surface roughness and also the wetting properties of the two-component hybrid layers proved to be finely adjustable by the LDO:fluoropolymer ratio. It was found that at 80-90 wt% LDO content, the thin films with a surface free energy value of ∼12 mJ/m2 displayed superhydrophobic behaviour (Θ > 150°) with satisfactory photocatalytic properties. This means special photoreactive surfaces with superhydrophobic properties instead of the conventional superhydropilic photocatalyst layers. According to the benzoic acid photodegradation test experiments of benzoic acid, the hybrid layers with 80-90 wt% LDO content photooxidized 22-24% of the initial test molecule concentration (0.17 g/L) under UV-A (λmax = 365 nm) illumination.

  19. Hybrid Materials Based on Magnetic Layered Double Hydroxides: A Molecular Perspective.

    Science.gov (United States)

    Abellán, Gonzalo; Martí-Gastaldo, Carlos; Ribera, Antonio; Coronado, Eugenio

    2015-06-16

    Design of functional hybrids lies at the very core of synthetic chemistry as it has enabled the development of an unlimited number of solids displaying unprecedented or even improved properties built upon the association at the molecular level of quite disparate components by chemical design. Multifunctional hybrids are a particularly appealing case among hybrid organic/inorganic materials. Here, chemical knowledge is used to deploy molecular components bearing different functionalities within a single solid so that these properties can coexist or event interact leading to unprecedented phenomena. From a molecular perspective, this can be done either by controlled assembly of organic/inorganic molecular tectons into an extended architecture of hybrid nature or by intercalation of organic moieties within the empty channels or interlamellar space offered by inorganic solids with three-dimensional (MOFs, zeolites, and mesoporous hosts) or layered structures (phosphates, silicates, metal dichalcogenides, or anionic clays). This Account specifically illustrates the use of layered double hydroxides (LDHs) in the preparation of magnetic hybrids, in line with the development of soft inorganic chemistry processes (also called "Chimie Douce"), which has significantly contributed to boost the preparation hybrid materials based on solid-state hosts and subsequent development of applications. Several features sustain the importance of LDHs in this context. Their magnetism can be manipulated at a molecular level by adequate choice of constituting metals and interlayer separation for tuning the nature and extent of magnetic interactions across and between planes. They display unparalleled versatility in accommodating a broad range of anionic species in their interlamellar space that encompasses not only simple anions but chemical systems of increasing dimensionality and functionalities. Their swelling characteristics allow for their exfoliation in organic solvents with high

  20. Layered-double-hydroxide-modified electrodes: electroanalytical applications.

    Science.gov (United States)

    Tonelli, Domenica; Scavetta, Erika; Giorgetti, Marco

    2013-01-01

    Two-dimensional inorganic solids, such as layered double hydroxides (LDHs), also defined as anionic clays, have open structures and unique anion-exchange properties which make them very appropriate materials for the immobilization of anions and biomolecules that often bear an overall negative charge. This review aims to describe the important aspects and new developments of electrochemical sensors and biosensors based on LDHs, evidencing the research from our own laboratory and other groups. It is intended to provide an overview of the various types of chemically modified electrodes that have been developed with these 2D layered materials, along with the significant advances made over the last several years. In particular, we report the main methods used for the deposition of LDH films on different substrates, the conductive properties of these materials, the possibility to use them in the development of membranes for potentiometric anion analysis, the early analytical applications of chemically modified electrodes based on the ability of LDHs to preconcentrate redox-active anions and finally the most recent applications exploiting their electrocatalytic properties. Another promising application field of LDHs, when they are employed as host structures for enzymes, is biosensing, which is described considering glucose as an example.

  1. The double-layered chemical structure in DB white dwarfs

    CERN Document Server

    Althaus, L G

    2004-01-01

    We study the structure and evolution of white dwarf stars with helium-rich atmospheres (DB) in a self-consistent way with the predictions of time-dependent element diffusion. Our treatment of diffusion includes gravitational settling and chemical and thermal diffusion. OPAL radiative opacities for arbitrary metallicity and carbon-and oxygen-rich compositions are employed. Emphasis is placed on the evolution of the diffusion-modeled double-layered chemical structure. This structure, which is characterized by a pure helium envelope atop an intermediate remnant shell rich in helium, carbon and oxygen, is expected for pulsating DB white dwarfs, assuming that they are descendants of hydrogen-deficient PG1159 post-AGB stars. We find that, depending on the stellar mass, if DB white dwarf progenitors are formed with a helium content smaller than \\approx 10^-3 M_*, a single-layered configuration is expected to emerge during the DB pulsation instability strip. We also explore the consequences of diffusively evolving ch...

  2. Plasmons in spatially separated double-layer graphene nanoribbons

    Science.gov (United States)

    Bagheri, Mehran; Bahrami, Mousa

    2014-05-01

    Motivated by innovative progresses in designing multi-layer graphene nanostructured materials in the laboratory, we theoretically investigate the Dirac plasmon modes of a spatially separated double-layer graphene nanoribbon system, made up of a vertically offset armchair and metallic graphene nanoribbon pair. We find striking features of the collective excitations in this novel Coulomb correlated system, where both nanoribbons are supposed to be either intrinsic (undoped/ungated) or extrinsic (doped/gated). In the former, it is shown the low-energy acoustical and the high-energy optical plasmon modes are tunable only by the inter-ribbon charge separation. In the later, the aforementioned plasmon branches are modified by the added doping factor. As a result, our model could be useful to examine the existence of a linear Landau-undamped low-energy acoustical plasmon mode tuned via the inter-ribbon charge separation as well as doping. This study might also be utilized for devising novel quantum optical waveguides based on the Coulomb coupled graphene nanoribbons.

  3. Propagation characteristics of ion-acoustic double layer in multicomponent inhomogeneous auroral zone plasma

    Indian Academy of Sciences (India)

    HARVINDER KAUR; TARSEM SINGH GILL; PARVEEN BALA

    2017-08-01

    In the present investigation, ion-acoustic double layers in an inhomogeneous plasma consisting of Maxwellian and non-thermal distributions of electrons are studied.We have derived a modified Korteweg–de Vries (mKdV) equation for ion-acoustic double layers propagating in a collisionless inhomogeneous plasma. It is observed that the non-thermal parameters affect the amplitude and width of the double layer which further depend on the density.

  4. Polymethyl methacrylate and polystyrene with layered double hydroxide nano composites: In situ synthesis, morphology and thermal properties; Nanocompositos de polimetacrilato de metila e poliestireno com hidroxido duplo lamelar: sintese in situ, morfologia e propriedades termicas

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2011-07-01

    Over the past decade, polymer nanocomposites have attracted interest, both in industry and in academia, because they often exhibit remarkable improvement in their properties when compared with pure polymer or conventional micro and macro-composites using low levels of reinforcements. In this work polymethyl methacrylate and polystyrene reinforced with layered double hydroxide, which was intercalated with sodium dodecyl sulfate were synthesized by in situ bulk polymerization. The nanocomposites were characterized and compared by X-ray diffraction, thermogravimetric analysis and flammability test. The X-ray diffraction demonstrated that synthesized nanocomposites showed a high global dispersion of layered double hydroxide, suggesting exfoliated morphology. The result of thermogravimetric analysis and flammability test for synthesized polystyrene/ layered double hydroxide nanocomposite presented a significant improvement in thermal stability and flammability property when compared with pure polymer. (author)

  5. Cu2+ ions as a paramagnetic probe to study the surface chemical modification process of layered double hydroxides and hydroxide salts with nitrate and carboxylate anions.

    Science.gov (United States)

    Arizaga, Gregorio Guadalupe Carbajal; Mangrich, Antonio Salvio; Wypych, Fernando

    2008-04-01

    A layered zinc hydroxide nitrate (Zn5(OH)8(NO3)2.2H2O) and a layered double hydroxide (Zn/Al-NO3) were synthesized by coprecipitation and doped with different amounts of Cu2+ (0.2, 1, and 10 mol%), as paramagnetic probe. Although the literature reports that the nitrate ion is free (with D3h symmetry) between the layers of these two structures, the FTIR spectra of two zinc hydroxide nitrate samples show the C2v symmetry for the nitrate ion, whereas the g ||/A || value in the EPR spectra of Cu2+ is high. This fact suggests bonding of some nitrate ions to the layers of the zinc hydroxide nitrate. The zinc hydroxide nitrate was used as matrix in the intercalation reaction with benzoate, o-chlorobenzoate, and o-iodobenzoate ions. FTIR spectra confirm the ionic exchange reaction and the EPR spectroscopy reveals bonding of the organic ions to the inorganic layers of the zinc hydroxide nitrate, while the layered double hydroxides show only exchange reactions.

  6. Electrochemical double-layer capacitors based on functionalized graphene

    Science.gov (United States)

    Pope, Michael Allan

    Graphene is a promising electrode material for electrochemical double-layer capacitors (EDLCs) used for energy storage due to its high electrical conductivity and theoretical specific surface area. However, the intrinsic capacitance of graphene is known to be low and governed by the electronic side of the interface. Furthermore, graphene tends to aggregate and stack together when processed into thick electrode films. This significantly lowers the ion-accessible specific surface area (SSA). Maximizing both the SSA and the intrinsic capacitance are the main problems addressed in this thesis in an effort to improve the specific capacitance and energy density of EDLCs. In contrast to pristine graphene, functionalized graphene produced by the thermal exfoliation of graphite oxide contains residual functional groups and lattice defects. To study how these properties affect the double-layer capacitance, a model electrode system capable of measuring the intrinsic electrochemical properties of functionalized graphene was developed. To prevent artifacts and uncertainties related to measurements on porous electrodes, the functionalized graphene sheets (FGSs) were assembled as densely tiled monolayers using a Langmuir-Blodgett technique. In this way, charging can be studied in a well-defined 2D geometry. The possibility of measuring and isolating the intrinsic electrochemical properties of FGS monolayers was first demonstrated by comparing capacitance and redox probe measurements carried out on coatings deposited on passivated gold and single crystal graphite substrates. This monolayer system was then used to follow the double-layer capacitance of the FGS/electrolyte interface as the structure and chemistry of graphene was varied by thermal treatments ranging from 300 °C to 2100 °C. Elemental analysis and Raman spectroscopy were used to determine the resulting chemical and structural transformation upon heat treatment. It was demonstrated that intrinsically defective

  7. Supermolecular layered dou- ble hydroxides

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Research progresses in the layered double hydroxides ·mH2O intercalated with metal coordinate ions or oxometalates in the last ten years are reviewed. These layered double hydroxides are mainly intercalated with polyoxometalate (POM) ions, a LiAl-LDH photochemical assembly containing TiO2 and CH3(CH2)12COO- anions, together with Zn(TPPC) (porphy-rin derivate) and macrocyclic ligand-containing porphyrin derivate anions. Emphasis is put on the synthesis methods for intercalation of the anions into the interlayer regions, the characterization techniques and structures for the layered compounds and the newest research progress in the fields such as catalysis. The review also forecasts the prospects of the field.

  8. [Raman and infrared spectrograms of organic borate intercalated hydrotalcite].

    Science.gov (United States)

    Zhang, Jing-Yu; Bai, Zhi-Min; Zhao, Dong

    2013-03-01

    The pattern of X-ray diffraction, the Raman and infrared spectra of organic borate intercalated hydrotalcite were discussed. The well crystallized zinc-aluminum layered double hydroxides (Zn-Al LDHs) intercalated by carbonate ions and borate ions were respectively prepared by co-precipitation method. Patterns of X-ray diffraction showed that the (003) reflection of borate-LDHs was sharp and symmetric and shifted to lower angle than that of carbonate-LDHs. The gallery height of borate-LDHs increased from 0. 28 nm to 0.42 nm after intercalation, indicating that interlayered carbonate ions were substituted by borate anions. The Raman and IR spectra showed that specific bands of carbonate ions in the borate-LDHs disappeared, but with the presence of B3O3(OH)4- X B4O5(OH)4(2-) and B(OH)4- in the interlayer galleries. The hydroxide interlayer anions had a significant influence on the band positions in Raman and infrared spectra of modes related to the hydroxyl group. Our results indicate that single phase and pure borate-pillared LDHs can be obtained using tributyl orthoborate as intercalating agents, and the change in the structure and nature of hydrotalcite can be detected precisely by Raman spectroscopy.

  9. Electron emission from a double-layer metal under femtosecond laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Li, Shuchang; Li, Suyu; Jiang, Yuanfei; Chen, Anmin, E-mail: amchen@jlu.edu.cn; Ding, Dajun; Jin, Mingxing, E-mail: mxjin@jlu.edu.cn

    2015-01-01

    In this paper we theoretically investigate electron emission during femtosecond laser ablation of single-layer metal (copper) and double-layer structures. The double-layer structure is composed of a surface layer (copper) and a substrate layer (gold or chromium). The calculated results indicate that the double-layer structure brings a change to the electron emission from the copper surface. Compared with the ablation of a single-layer, a double-layer structure may be helpful to decrease the relaxation time of the electron temperature, and optimize the electron emission by diminishing the tailing phenomenon under the same absorbed laser fluence. With the increase of the absorbed laser fluence, the effect of optimization becomes significant. This study provides a way to optimize the electron emission which can be beneficial to generate laser induced ultrafast electron pulse sources.

  10. Epitaxial Growth of High-Quality Silicon Films on Double-Layer Porous Silicon

    Institute of Scientific and Technical Information of China (English)

    黄宜平; 竺士炀; 李爱珍; 王瑾; 黄靖云; 叶志镇

    2001-01-01

    The epitaxial growth of a high-quality silicon layer on double-layer porous silicon by ultra-high vacuum/chemical vapour deposition has been reported. The two-step anodization process results in a double-layer porous silicon structure with a different porosity. This double-layer porous silicon structure and an extended low-temperature annealing in a vacuum system was found to be helpful in subsequent silicon epitaxial growth. X-ray diffraction,cross-sectional transmission electron microscopy and spreading resistance testing were used in this work to study the properties of epitaxial silicon layers grown on the double-layer porous silicon. The results show that the epitaxial silicon layer is of good crystallinity and the same orientation with the silicon substrate and the porous silicon layer.

  11. Proton Acceleration with Double-Layer Targets in the Radiation Pressure Dominant Regime

    Institute of Scientific and Technical Information of China (English)

    LU Hai-Yang; WANG Cheng; LIU Jian-Sheng

    2011-01-01

    @@ Acceleration of protons by a circularly polarized laser pulse irradiating on a double-layer target is investigated by a theoretical model and particle-in-cell simulations.The target is made up of a heavy ion layer coated with a proton layer on the rear surface.The results show that when the first layer is transparent induced by the hole-boring effect, the whole proton layer is accelerated by the transmitted laser pulse to high energy with low energy spread.The quality of the proton beam generated from a double-layer target is better than that from a single-layer target.The improvement is attributed to the flat top structure of the electrostatic field caused by the electrons injected into the second layer.It is easier to control the spectrum quality by using a double-layer target rather than using a single-layer one when the radiation pressure acceleration is dominant.

  12. Self-Assembly of 1D/2D Hybrid Nanostructures Consisting of a Cd(II Coordination Polymer and NiAl-Layered Double Hydroxides

    Directory of Open Access Journals (Sweden)

    Gonzalo Abellán

    2015-12-01

    Full Text Available The preparation and characterization of a novel hybrid material based on the combination of a 2D-layered double hydroxide (LDH nanosheets and a 1D-coordination polymer (1D-CP has been achieved through a simple mixture of suspensions of both building blocks via an exfoliation/restacking approach. The hybrid material has been thoroughly characterized demonstrating that the 1D-CP moieties are intercalated as well as adsorbed on the surface of the LDH, giving rise to a layered assembly with the coexistence of the functionalities of their initial constituents. This hybrid represents the first example of the assembly of 1D/2D nanomaterials combining LDH with CP and opens the door for a plethora of different functional hybrid systems.

  13. Mechanical and thermal properties of polypropylene and layered double hydroxides nanocomposites; Propriedades mecanicas e termicas de nanocompositos de polipropileno e hidroxidos duplos lamelares

    Energy Technology Data Exchange (ETDEWEB)

    Duarte de Farias, A.M.; Fraga, M.A.; Oliveira, R.B.; Oliveira, M.G., E-mail: marcia.oliveira@int.gov.b [Instituto Nacional de Tecnologia (INT), Rio de Janeiro, RJ (Brazil)

    2010-07-01

    The recent interest in polymer nanocomposites involving layered double hydroxides (LDH) is due to improved thermal stability, flame resistance, mechanical and barrier properties. The LDHs are structurally described as the stacking of layers with positively charged hydrated anions intercalated between these lamellae. In this paper, polypropylene nanocomposites with Mg / Al-HDL unmodified and modified with sodium dodecyl sulfate (DS) were prepared in the internal mixing chamber equipped with roller rotors and heated to 190 deg C. The nanocomposites were injected molded and then morphology, mechanical and thermal properties were evaluated by X-ray diffraction, tensile tests and DSC, respectively. The results revealed that both LDH and LDH-DS reached a good degree of dispersion in the PP matrix, resulting in increased stiffness, but reduced capacity for deformation and toughness of nanocomposites. The crystallinity of the nanocomposites was higher compared to the PP matrix. (author)

  14. Energy distribution of elastically scattered electrons from double layer samples

    Science.gov (United States)

    Tőkési, K.; Varga, D.

    2016-02-01

    We present a theoretical description of the spectra of electrons elastically scattered from thin double layered Au-C samples. The analysis is based on the Monte Carlo simulation of the recoil and Doppler effects in reflection and transmission geometries of the scattering at a fixed angle of 44.3 ° and a primary energy of 40 keV. The relativistic correction is taken into account. Besides the experimentally measurable energy distributions the simulations give many partial distributions separately, depending on the number of elastic scatterings (single, and multiple scatterings of different types). Furthermore, we present detailed analytical calculations for the main parameters of the single scattering, taking into account both the ideal scattering geometry, i.e. infinitesimally small angular range, and the effect of the real, finite angular range used in the measurements. We show our results for intensity ratios, peak shifts and broadenings for four cases of measurement geometries and layer thicknesses. While in the peak intensity ratios of gold and carbon for transmission geometries were found to be in good agreement with the results of the single scattering model, especially large deviations were obtained in reflection geometries. The separation of the peaks, depending on the geometry and the thickness, generally smaller, and the peak width generally larger than it can be expected from the nominal values of the primary energy, scattering angle, and mean kinetic energy of the atoms. We also show that the peaks are asymmetric even for the case of the single scattering due to the finite solid angle. Finally, we present a qualitative comparison with the experimental data. We find our resulting energy distribution of elastically scattered electrons to be in good agreement with recent measurements.

  15. Layered double hydroxides as fillers in poly(l-lactide nanocomposites, obtained by in situ bulk polymerization

    Directory of Open Access Journals (Sweden)

    Telma Nogueira

    2016-01-01

    Full Text Available Abstract In this study in situ bulk polymerization of L-lactide filled with layered double hydroxides (LDH was investigated. Four different LDHs intercalated with two different organic anions (salicylate and sebacate were synthesized and characterized. After characterization, these synthetic layered compounds were used as fillers in poly(L-lactide (PLLA nanocomposites with two different fillers’s loadings (1 wt% and 2 wt%. PLLA and PLLA nanocomposites were evaluated by X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FTIR, ultraviolet and visible spectroscopy, thermogravimetric analysis (TGA, dynamical mechanical analysis (DMA, flexural testing and differential scanning calorimetry (DSC. The results demonstrated that, compared to PLLA, the nanocomposite containing 1 wt% of Zn/Al salicylate transmitted less UVA and UVB light, while keeping a similar transparency in the visible region. Thermogravimetric analysis revealed that the nanocomposite with 1 wt% of Zn/Al salicylate exhibited the highest thermal stability. In general the flexural and dynamical mechanical properties were reduced in compassion to neat PLLA. DSC results, demonstrated that, compared to PLLA, all the nanocomposites exhibited lower glass transition temperature and melting temperature values.

  16. Layered double hydroxides as fillers in poly(l-lactide nanocomposites, obtained by in situ bulk polymerization

    Directory of Open Access Journals (Sweden)

    Telma Nogueira

    Full Text Available Abstract In this study in situ bulk polymerization of L-lactide filled with layered double hydroxides (LDH was investigated. Four different LDHs intercalated with two different organic anions (salicylate and sebacate were synthesized and characterized. After characterization, these synthetic layered compounds were used as fillers in poly(L-lactide (PLLA nanocomposites with two different fillers’s loadings (1 wt% and 2 wt%. PLLA and PLLA nanocomposites were evaluated by X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FTIR, ultraviolet and visible spectroscopy, thermogravimetric analysis (TGA, dynamical mechanical analysis (DMA, flexural testing and differential scanning calorimetry (DSC. The results demonstrated that, compared to PLLA, the nanocomposite containing 1 wt% of Zn/Al salicylate transmitted less UVA and UVB light, while keeping a similar transparency in the visible region. Thermogravimetric analysis revealed that the nanocomposite with 1 wt% of Zn/Al salicylate exhibited the highest thermal stability. In general the flexural and dynamical mechanical properties were reduced in compassion to neat PLLA. DSC results, demonstrated that, compared to PLLA, all the nanocomposites exhibited lower glass transition temperature and melting temperature values.

  17. Hidróxidos duplos lamelares: nanopartículas inorgânicas para armazenamento e liberação de espécies de interesse biológico e terapêutico Layered double hydroxides: inorganic nanoparticles for storage and release of species of biological and therapeutic interest

    Directory of Open Access Journals (Sweden)

    Vanessa R. R. Cunha

    2010-01-01

    Full Text Available Studies about the inorganic nanoparticles applying for non-viral release of biological and therapeutic species have been intensified nowadays. This work reviews the preparation strategies and application of layered double hydroxides (LDH as carriers for storing, carrying and control delivery of intercalated species as drugs and DNA for gene therapy. LDH show low toxicity, biocompatibility, high anion exchange capacity, surface sites for functionalization, and a suitable equilibrium between chemical stability and biodegradability. LDH can increase the intercalated species stability and promote its sub-cellular uptake for biomedical purposes. Concerning the healthy field, LDH have been evaluated for clinical diagnosis as a biosensor component.

  18. Junction conditions in quadratic gravity: thin shells and double layers

    CERN Document Server

    Reina, Borja; Vera, Raül

    2015-01-01

    The junction conditions for the most general gravitational theory with a Lagrangian containing terms quadratic in the curvature are derived. We include the cases with a possible concentration of matter on the joining hypersurface -termed as thin shells, domain walls or braneworlds in the literature- as well as the proper matching conditions where only finite jumps of the energy-momentum tensor are allowed. In the latter case we prove that the matching conditions are more demanding than in General Relativity. In the former case, we show that generically the shells/domain walls are of a new kind because they possess, in addition to the standard energy-momentum tensor, a double layer energy-momentum contribution which actually induces an external energy flux vector and an external scalar pressure/tension on the shell. We prove that all these contributions are necessary to make the entire energy-momentum tensor divergence-free, and we present the field equations satisfied by these energy-momentum quantities. The ...

  19. Carbon aerogels for electric double-layer capacitors

    Institute of Scientific and Technical Information of China (English)

    ZHANG Lin; LIU Hongbo; WANG Ming; LIU Wei

    2006-01-01

    In this study, carbon aerogels were derived via the pyrolysis of resorcinol-formaldehyde (RF) aerogels, which were cost-effectively manufactured from RF wet gels by an ambient drying technique instead of conventional supercritical drying. By varying the R/C ratio (molar ratio of resorcinol to catalyst), mesoporous carbon aerogels with high specific surface area were prepared successfully and further investigated as electrode materials for electric double-layer capacitors (EDLCs). The textural properties of carbon aerogels obtained were characterized by nitrogen adsorption/desorption analysis and SEM. The electrochemical performances of carbon aerogels were investigated by impedance spectroscopy, galvanostatic charge/discharge and cyclic voltammetry methods. The results show that BET surface area and specific capacitance increase with R/C ratio, the maximum values of 727 m2·g-1 and 132 F·g-1 are achieved at R/C ratio will of 300. Increasing R/C ratio increase the average pore size of carbon aerogel electrode, which has improved the rate capability. Furthermore, EDLC with carbon aerogel electrodes has an excellent stability at large discharge current and long cycle life.

  20. Enhanced aerobic sludge granulation with layered double hydroxide

    Directory of Open Access Journals (Sweden)

    Jizhi Zhou

    2014-06-01

    Full Text Available Aerobic granular sludge technology has been developed for the biochemical treatment of wastewater in the present study. A fast cultivation of aerobic granular sludge was realized in Sequencing Batch Reactor (SBR, where Mg-Al layered double hydroxide (LDH was used as a carrier for granules growth. In comparison, the sludge particle size with LDH addition was bigger than those without LDH, with more than 50% of compact granular sludge >1.4 mm in size. This indicatestheLDH improved the growth ofthegranular sludge. The frequency of LDH addition had little effect on the granule growth. Moreover, the formation of granules led to the low sludge volume index (SVI and high mixed liquid suspended solids (MLSS in SBR reactor. With the formation of granular sludge, more than 80% of COD was removed in SBR reactor. The high COD removal efficiency of wastewater was observed regardless of various COD loading strength. The results suggest that the growth of granular sludge with LDH as a carrier enhanced the treatment efficiency. Therefore, our results have provided a promising way to prepare the granular sludge for wastewater treatment.

  1. Immobilization of Penicillin G Acylase on Calcined Layered Double Hydroxides

    Institute of Scientific and Technical Information of China (English)

    REN Ling-ling; HE Jing; Evans D. G.; DUAN Xue

    2003-01-01

    A hydrotalcite-like Mg2+/Al3+ layered double hydroxide(LDH) material was prepared by means of a modified coprecipitation method involving a rapid mixing step followed by a separate aging process. LDH calcined at 500 ℃, denoted as CLDH, was characterized by XRD, IR and BET surface area measurements. CLDH has a poor crystalline MgO-like structure with a high surface area and porosity. CLDH was used as a support for the immobilization of penicillin G acylase(PGA). The effect of varying the immobilization conditions, such as pH, contact time and the ratio of enzyme to support, on the activity of the immobilized enzyme in the hydrolysis of penicillin G has been studied. It was found that the activity of the immobilized enzyme decreased slightly with decreasing pH and reached a maximum after a contact time of 24 h. The activity of the immobilized enzyme increased with increasing the ratio of enzyme to support. It was found that the adsorption of PGA inhibited the expected reaction of CLDH with an aqueous medium to regenerate a LDH phase. Its original activity(36%) after 15 cycles of reuse of the immobilized enzyme was retained, but no further loss in the activity was observed.

  2. Lubrication approximation in completed double layer boundary element method

    Science.gov (United States)

    Nasseri, S.; Phan-Thien, N.; Fan, X.-J.

    This paper reports on the results of the numerical simulation of the motion of solid spherical particles in shear Stokes flows. Using the completed double layer boundary element method (CDLBEM) via distributed computing under Parallel Virtual Machine (PVM), the effective viscosity of suspension has been calculated for a finite number of spheres in a cubic array, or in a random configuration. In the simulation presented here, the short range interactions via lubrication forces are also taken into account, via the range completer in the formulation, whenever the gap between two neighbouring particles is closer than a critical gap. The results for particles in a simple cubic array agree with the results of Nunan and Keller (1984) and Stoksian Dynamics of Brady etal. (1988). To evaluate the lubrication forces between particles in a random configuration, a critical gap of 0.2 of particle's radius is suggested and the results are tested against the experimental data of Thomas (1965) and empirical equation of Krieger-Dougherty (Krieger, 1972). Finally, the quasi-steady trajectories are obtained for time-varying configuration of 125 particles.

  3. Novel synthesis of layered double hydroxides (LDHs) from zinc hydroxide

    Science.gov (United States)

    Meng, Zilin; Zhang, Yihe; Zhang, Qian; Chen, Xue; Liu, Leipeng; Komarneni, Sridhar; Lv, Fengzhu

    2017-02-01

    The most common synthesis methods for layered double hydroxides (LDHs) are co-precipitation and reconstruction, which can have some limitations for application. Here, we report a novel synthesis method for LDHs. We use zinc hydroxide as the precursor to synthesize LDHs phase through a simple transformation process of zinc hydroxide phase. For this transformation process, aluminum can enter into zinc hydroxide and replace zinc quickly to transform it into LDH by creating positive charges in the zinc hydroxide solid phase. The mechanism of LDH formation was through Al3+ reaction first with zinc hydroxide followed by recrystallization of the original structure of zinc hydroxide. Thus, the new process of LDH formation involves a reaction of Al to substitute for Zn and recrystallization leading to LDH and the final pH influences the crystallization of LDHs by this process. In addition, Cr3+ was employed as a trivalent cation for LDH formation to react with zinc hydroxide, which also led to LDH structure.

  4. Experimental investigation of double layers in expanding plasmas

    CERN Document Server

    Plihon, N; Corr, C S

    2015-01-01

    Double layers (DLs) have been observed in a plasma reactor composed of a source chamber attached to a larger expanding chamber. Positive ion beams generated across the DL were characterized in the low plasma potential region using retarding field energy analyzers. In electropositive gases, DLs were formed at very low pressures between 0.1 and 1 mTorr with the plasma expansion forced by a strongly diverging magnetic field. The DL remains static, robust to changes in boundary conditions, and its position is related to the magnetic field lines. The voltage drop across the DL increases with decreasing pressure, i.e., with increasing electron temperature around 20 V at 0.17 mTorr. DLs were also observed in electronegative gases without a magnetic field over a greater range of pressure 0.5 to 10 mTorr. The actual profile of the electronegative DL is very sensitive to external parameters and intrusive elements, and they propagate at high negative ion fraction. Electrostatic probes measurements and laser-induced phot...

  5. Junction conditions in quadratic gravity: thin shells and double layers

    Science.gov (United States)

    Reina, Borja; Senovilla, José M. M.; Vera, Raül

    2016-05-01

    The junction conditions for the most general gravitational theory with a Lagrangian containing terms quadratic in the curvature are derived. We include the cases with a possible concentration of matter on the joining hypersurface—termed as thin shells, domain walls or braneworlds in the literature—as well as the proper matching conditions where only finite jumps of the energy-momentum tensor are allowed. In the latter case we prove that the matching conditions are more demanding than in general relativity. In the former case, we show that generically the shells/domain walls are of a new kind because they possess, in addition to the standard energy-momentum tensor, a double layer energy-momentum contribution which actually induces an external energy flux vector and an external scalar pressure/tension on the shell. We prove that all these contributions are necessary to make the entire energy-momentum tensor divergence-free, and we present the field equations satisfied by these energy-momentum quantities. The consequences of all these results are briefly analyzed.

  6. Preparation and controlled-release studies of a protocatechuic acid-magnesium/aluminum-layered double hydroxide nanocomposite

    Directory of Open Access Journals (Sweden)

    Barahuie F

    2013-05-01

    Full Text Available Farahnaz Barahuie,1 Mohd Zobir Hussein,1 Samer Hasan Hussein-Al-Ali,2 Palanisamy Arulselvan,3 Sharida Fakurazi,3,4 Zulkarnain Zainal11Materials Synthesis and Characterization Laboratory, Institute of Advanced Technology (ITMA, 2Laboratory of Molecular Biomedicine, Institute of Bioscience, 3Laboratory of Vaccines and Immunotherapeutics, Institute of Bioscience, 4Department of Human Anatomy, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Serdang, MalaysiaAbstract: In the study reported here, magnesium/aluminum (Mg/Al-layered double hydroxide (LDH was intercalated with an anticancer drug, protocatechuic acid, using ion-exchange and direct coprecipitation methods, with the resultant products labeled according to the method used to produce them: “PANE” (ie, protocatechuic acid-Mg/Al nanocomposite synthesized using the ion-exchange method and “PAND” (ie, protocatechuic acid-Mg/Al nanocomposite synthesized using the direct method, respectively. Powder X-ray diffraction and Fourier transform infrared spectroscopy confirmed the intercalation of protocatechuic acid into the inter-galleries of Mg/Al-LDH. The protocatechuic acid between the interlayers of PANE and PAND was found to be a monolayer, with an angle from the z-axis of 8° for PANE and 15° for PAND. Thermogravimetric and differential thermogravimetric analysis results revealed that the thermal stability of protocatechuic acid was markedly enhanced upon intercalation. The loading of protocatechuic acid in PANE and PAND was estimated to be about 24.5% and 27.5% (w/w, respectively. The in vitro release study of protocatechuic acid from PANE and PAND in phosphate-buffered saline at pH 7.4, 5.3, and 4.8 revealed that the nanocomposites had a sustained release property. After 72 hours incubation of PANE and PAND with MCF-7 human breast cancer and HeLa human cervical cancer cell lines, it was found that the nanocomposites had suppressed the growth of these cancer cells

  7. Finite-Thickness and Charge Relaxation in Double-Layer Interactions

    NARCIS (Netherlands)

    Torres, A.; Roij, R. van; Téllez, G.

    2006-01-01

    We extend the classical Gouy-Chapman model of two planar parallel interacting double-layers, which is used as a first approximation to describe the force between colloidal particles, by considering the finitethickness of the colloids. The formation of two additional double layers due to this finite

  8. Finite-Thickness and Charge Relaxation in Double-Layer Interactions

    NARCIS (Netherlands)

    Torres, A.; Roij, R. van; Téllez, G.

    2006-01-01

    We extend the classical Gouy-Chapman model of two planar parallel interacting double-layers, which is used as a first approximation to describe the force between colloidal particles, by considering the finitethickness of the colloids. The formation of two additional double layers due to this

  9. The electric double layer put to work : thermal physics at electrochemical interfaces

    NARCIS (Netherlands)

    Janssen, M.A.

    2017-01-01

    Where charged electrode surfaces meet fluids that contain mobile ions, so-called electric double layers (EDLs) form to screen the electric surface charge by a diffuse cloud of counterionic charge in the fluid phase. This double layer has been studied for over a century and is of paramount importance

  10. Experimental validation of sound field control with a circular double-layer array of loudspeakers

    DEFF Research Database (Denmark)

    Chang, Jiho; Jacobsen, Finn

    2013-01-01

    This paper is concerned with experimental validation of a recently proposed method of controlling sound fields with a circular double-layer array of loudspeakers [Chang and Jacobsen, J. Acoust. Soc. Am. 131(6), 4518-4525 (2012)]. The double-layer of loudspeakers is realized with 20 pairs of closed-box...

  11. Facile synthesis of NiAl-layered double hydroxide/graphene hybrid with enhanced electrochemical properties for detection of dopamine

    Science.gov (United States)

    Li, Meixia; Zhu, Jun E.; Zhang, Lili; Chen, Xu; Zhang, Huimin; Zhang, Fazhi; Xu, Sailong; Evans, David G.

    2011-10-01

    Layered double hydroxides (LDHs), also known as hydrotalcite-like anionic clays, have been investigated widely as promising electrochemical active materials. Due to the inherently weak conductivity, the electrochemical properties of LDHs were improved typically by utilization of either functional molecules intercalated between LDH interlayer galleries, or proteins confined between exfoliated LDH nanosheets. Here, we report a facile protocol to prepare NiAl-LDH/graphene (NiAl-LDH/G) nanocomposites using a conventional coprecipitation process under low-temperature conditions and subsequent reduction of the supporting graphene oxide. Electrochemical tests showed that the NiAl-LDH/G modified electrode exhibited highly enhanced electrochemical performance of dopamine electrooxidation in comparison with the pristine NiAl-LDH modified electrode. Results of high-resolution transmission electron microscopy and Raman spectra provide convincing information on the nanostructure and composition underlying the enhancement. Our results of the NiAl-LDH/G modified electrodes with the enhanced electrochemical performance may allow designing a variety of promising hybrid sensors via a simple and feasible approach.Layered double hydroxides (LDHs), also known as hydrotalcite-like anionic clays, have been investigated widely as promising electrochemical active materials. Due to the inherently weak conductivity, the electrochemical properties of LDHs were improved typically by utilization of either functional molecules intercalated between LDH interlayer galleries, or proteins confined between exfoliated LDH nanosheets. Here, we report a facile protocol to prepare NiAl-LDH/graphene (NiAl-LDH/G) nanocomposites using a conventional coprecipitation process under low-temperature conditions and subsequent reduction of the supporting graphene oxide. Electrochemical tests showed that the NiAl-LDH/G modified electrode exhibited highly enhanced electrochemical performance of dopamine

  12. A novel lithium intercalation compound based on the layered structure of lithium nitridonickelates Li{sub 3-2x}Ni{sub x}N

    Energy Technology Data Exchange (ETDEWEB)

    Ducros, J.B.; Bach, S.; Pereira-Ramos, J.P. [Institut de Chimie et des Materiaux Paris Est, GESMAT, UMR 7182, CNRS-Universite Paris XII 2, rue Henri-Dunant 94320 Thiais (France); Willmann, P. [Centre National d' udes Spatiales, 118 avenue Edouard Belin, 31401 Toulouse Cedex 9 (France)

    2007-08-01

    New lithium nickel nitrides Li{sub 3-2x}Ni{sub x}N (0.20 {<=} x {<=} 0.60) have been prepared and investigated as negative electrode in the 0.85/0.02 V potential window. These materials are prepared from a Ni/Li{sub 3}N mixture at 700 C under a nitrogen flow. Their structural characteristics as well as their electrochemical behaviour are investigated as a function of the nickel content. For the first time are reported here the electrochemical properties of a lithium intercalation compound based on a layered nitride structure. The Li{sub 3-2x}Ni{sub x}N compounds can be reversibly reduced and oxidized around 0.5 V versus Li/Li{sup +} leading to specific capacities in the range 120-160 mAh/g depending on the nickel content and the C rate. Due to a large number of lithium vacancies, the structural stability provides an excellent capacity retention of the specific capacity upon cycling. (author)

  13. A novel lithium intercalation compound based on the layered structure of lithium nitridonickelates Li{sub 3-2x}Ni {sub x}N

    Energy Technology Data Exchange (ETDEWEB)

    Ducros, J.B. [Institut de Chimie et des Materiaux Paris Est, GESMAT, UMR 7182, CNRS-Universite Paris XII 2, rue Henri-Dunant 94320 Thiais (France); Bach, S. [Institut de Chimie et des Materiaux Paris Est, GESMAT, UMR 7182, CNRS-Universite Paris XII 2, rue Henri-Dunant 94320 Thiais (France)]. E-mail: bach@glvt-cnrs.fr; Pereira-Ramos, J.P. [Institut de Chimie et des Materiaux Paris Est, GESMAT, UMR 7182, CNRS-Universite Paris XII 2, rue Henri-Dunant 94320 Thiais (France); Willmann, P. [Centre National d' udes Spatiales, 118 avenue Edouard Belin, 31401 Toulouse Cedex 9 (France)

    2007-08-01

    New lithium nickel nitrides Li{sub 3-2x}Ni {sub x}N (0.20 {<=} x {<=} 0.60) have been prepared and investigated as negative electrode in the 0.85/0.02 V potential window. These materials are prepared from a Ni/Li{sub 3}N mixture at 700 {sup o}C under a nitrogen flow. Their structural characteristics as well as their electrochemical behaviour are investigated as a function of the nickel content. For the first time are reported here the electrochemical properties of a lithium intercalation compound based on a layered nitride structure. The Li{sub 3-2x}Ni {sub x}N compounds can be reversibly reduced and oxidized around 0.5 V versus Li/Li{sup +} leading to specific capacities in the range 120-160 mAh/g depending on the nickel content and the C rate. Due to a large number of lithium vacancies, the structural stability provides an excellent capacity retention of the specific capacity upon cycling.

  14. Layered double hydroxide stability. 2. Formation of Cr(III)-containing layered double hydroxides directly from solution

    Science.gov (United States)

    Boclair, J. W.; Braterman, P. S.; Jiang, J.; Lou, S.; Yarberry, F.

    1999-01-01

    Solutions containing divalent metal [M(II) = Mg2+, Zn2+, Co2+, Ni2+, Mn2+] chlorides and CrCl3 6H2O were titrated with NaOH to yield, for M(II) = Zn, Co, and Ni, hydrotalcite-like layered double hydroxides (LDHs), [[M(II)]1-z[Cr(III)]z(OH)2][Cl]z yH2O, in a single step, without intermediate formation of chromium hydroxide. Analysis of the resultant titration curves yields solubility constants for these compounds. These are in the order Zn < Ni approximately Co, with a clear preference for formation of the phase with z = 1/3. With Mg2+ as chloride, titration gives a mixture of Cr(OH)3 and Mg(OH)2, but the metal sulfates give Mg2Cr(OH)6 1/2(SO4) by a two-step process. Titrimetric and spectroscopic evidence suggests short-range cation order in the one-step LDH systems.

  15. Magnetism in intercalated graphene

    Energy Technology Data Exchange (ETDEWEB)

    Ali, Sajid [Department of Electrical Engineering, Indian Institute of Technology Madras, Chennai – 600036 (India); Nanda, B. R. K. [Department of Physics, Indian Institute of Technology Madras, Chennai – 600036 (India)

    2016-05-23

    Using density functional calculations we explore the possibilities of inducing spin moments in otherwise non-magnetic electronic structure of graphene. Through intercalation of H, N, O and F atoms between two hexagonal stacked graphene layers, we show that unpaired electrons can be generated when the planar coordinates of the functional atoms coincide with the center of the graphene hexagon. The spin-half states are realized at the functional sites for certain values of interlayer separations. For oxygen and fluorine these interlayer separations represent the natural stable phases and for hydrogen and nitrogen they induce instability which can be overcome by applying external pressure. We attribute the formation of spin-half states to the one dimensional confinement potential exerted by the graphene layers on the valence electrons of the functional elements.

  16. Magnetism in intercalated graphene

    Science.gov (United States)

    Ali, Sajid; Nanda, B. R. K.

    2016-05-01

    Using density functional calculations we explore the possibilities of inducing spin moments in otherwise non-magnetic electronic structure of graphene. Through intercalation of H, N, O and F atoms between two hexagonal stacked graphene layers, we show that unpaired electrons can be generated when the planar coordinates of the functional atoms coincide with the center of the graphene hexagon. The spin-half states are realized at the functional sites for certain values of interlayer separations. For oxygen and fluorine these interlayer separations represent the natural stable phases and for hydrogen and nitrogen they induce instability which can be overcome by applying external pressure. We attribute the formation of spin-half states to the one dimensional confinement potential exerted by the graphene layers on the valence electrons of the functional elements.

  17. Does the plasma radiate near a Double Layer?

    Science.gov (United States)

    Pottelette, Raymond; Berthomier, Matthieu; Pickett, Jolene

    2016-04-01

    Earth is an intense radio source in the kilometer wavelength range. Being a direct consequence of the parallel acceleration processes taking place in the Earth's auroral region, the radiation contains fundamental information on the characteristic spatial and temporal scales of the turbulent accelerating layer. It is now widely assumed that the cyclotron maser instability leads to Auroral Kilometric Radiation (AKR) generation. It has been suggested from the FAST measurements that the AKR results from a so-called horseshoe electron distribution. This distribution is generated when a localized parallel electric field - called Double Layer (DL) - accelerates earthward the electrons that propagate into an increasing magnetic field. The magnetic moment of the electrons is conserved so that their pitch angle is increased. This results in the creation of a horseshoe-like shape for the electron distribution exhibiting large positive velocity gradients in the direction perpendicular to B, thereby providing free energy for the AKR generation which takes place at the local electron gyrofrequency. In these circumstances, the radiation is generated far away (several thousand kilometers) from a DL, because the parallel accelerated electrons need to travel a long distance before forming a horseshoe distribution. From an experimental point of view, it is not an easy task to highlight the presence of DLs, because they are moving transient structures so that high time resolution measurements are needed. A detailed analysis suggests that these large-amplitude parallel electric fields are located inside sharp density gradients at the interface separating the cold, dense ionospheric plasma from the hot, tenuous magnetospheric plasma. We present some FAST observations which illustrate the generation of elementary radiation events in the neighborhood of a DL. The events occur 10 to 20% above the local electron gyrofrequency in association with the presence of nonlinear coherent structures

  18. Development of high energy density electrical double layer capacitors

    Science.gov (United States)

    Devarajan, Thamarai selvi

    Electrochemical Double Layer capacitors (EDLCs) have shown themselves as a viable energy storage alternative. EDLCs have high power density, faster charge/discharge, wide operating temperature and long cycle life compared to batteries since it stores charge by physical separation. Despites all their advantages, their low energy density stand as a bottleneck for capacitors. This research aims to increase the energy density of EDLC without compromising the power density. Energy is proportional to the square of cell voltage. Cell voltage is mainly dependent on electrolyte breakdown. Electrolytes also provide ions for charge separation and conduction. Therefore various electrolytes (Solutes and Solvents) which can give high concentration, solubility and decomposition potential were characterized in the first part of the research. In that study, a novel ionic liquid OPBF4 had higher capacitance and comparable voltage window compared to commercial TEABF4 in Acetonitrile. However, the increased polarity of the fixed ring O-atom and the ion-ion interaction in OPBF4 was responsible for lowering its conductivity. Oxygenated ionic compounds with alkyl groups had lower stability due to beta elimination between two electron withdrawing atoms. Volume based thermodynamics and quantum chemical calculations were used to calculate ion size, HOMO/LUMO energies, and free energy changes and establish relationship with capacitance, redox potential and melting points respectively. In addition free energy of fusion was used to predict the melting point. Ion size had correlation with capacitance due to compact double layer formation. Free energy changes did not explain the differences in melting point and predicted dielectric constant was inconsistent with the polarity. This is presumably due to using Van der Waals volume instead of crystal structure volume and insufficient incorporation of polarization term. The HOMO/LUMO energies gave direct relation between oxidation and reduction

  19. Photo-oxidation of EPDM/layered double hydroxides composites: Influence of layered hydroxides and stabilizers

    Directory of Open Access Journals (Sweden)

    2007-11-01

    Full Text Available The photo-oxidation of ethylene propylene diene monomer (EPDM/ layered double hydroxide (LDH composites as well as EPDM/LDH with stabilizers is studied under accelerated UV irradiation (λ≥290 nm at 60°C for different time intervals. The development of functional groups during oxidation was monitored by FT-IR spectroscopy. The photodegradation of the pristine polymer and composites take place and the increase in hydroxyl and carbonyl groups with irradiation times, was estimated. EPDM filled LDH showed higher degradation rate than pristine EPDM, while in acidic medium EPDM/LDH showed almost equal degradation as in isolated conditions. These results show the advantages of LDHs as a filler as well as an acid killer. The effect of stabilizers is very less because of their concentration in comparison of LDH.

  20. Vertically aligned carbon nanotubes/diamond double-layered structure for improved field electron emission stability

    Energy Technology Data Exchange (ETDEWEB)

    Yang, L., E-mail: qiaoqin.yang@mail.usask.ca; Yang, Q.; Zhang, C.; Li, Y.S.

    2013-12-31

    A double-layered nanostructure consisting of a layer of vertically aligned Carbon Nanotubes (CNTs) and a layer of diamond beneath has been synthesized on silicon substrate by Hot Filament Chemical Vapor Deposition. The synthesis was achieved by first depositing a layer of diamond on silicon and then depositing a top layer of vertically aligned CNTs by applying a negative bias on the substrate holder. The growth of CNTs was catalyzed by a thin layer of spin-coated iron nitride. The surface morphology and structure of the CNTs/diamond double-layered structure were characterized by Scanning Electron Microscope, Energy Dispersive X-ray spectrum, and Raman Spectroscopy. Their field electron emission (FEE) properties were measured by KEITHLEY 237 high voltage measurement unit, showing much higher FEE current stability than single layered CNTs. - Highlights: • A new double-layered nanostructure consisting of a layer of vertically aligned CNTs and a layer of diamond beneath has been synthesized by hot filament chemical vapor deposition. • This double-layered structure exhibits superior field electron emission stability. • The improvement of emission stability is due to the combination of the unique properties of diamond and CNTs.

  1. Enhanced charge separation and oxidation kinetics of BiVO4 photoanode by double layer structure

    Science.gov (United States)

    Yang, Lin; Xiong, Yuli; Dong, Hongmei; Peng, Huarong; Zhang, Yunhuai; Xiao, Peng

    2017-03-01

    Monoclinic bismuth vanadate (BiVO4) is a promising semiconductor for photoelectrochemical water splitting. Here, we developed a facile fabrication of BiVO4 double layer photoanode on the fluorine-doped tin oxide substrate by electrodeposition. The BiVO4 double layer photoanode is composed by a dense BiVO4 film as the inner layer and a nanoporous BiVO4 film as the outer layer. Compared to the BiVO4 single layer photoanode, the optimized BiVO4 double layer photoanode produced a much higher photocurrent of 1.15 mA/cm2 at 0.6 V vs. Ag/AgCl under AM 1.5G (100 mW/cm2) illumination. The results of the photoelectric conversion kinetics for different samples revealed that the charge separation and oxidation kinetics efficiencies for the BiVO4 double layer are 47.2% and 51.6% at 0.6 V vs. Ag/AgCl, while the values for BiVO4 single layer are 32.3% and 35.8%, respectively. The improved photoelectrochemical performance for BiVO4 double layer is mainly ascribed to the decrease of defect state at the interface after inserting a dense BiVO4 as an inner layer to prevent the recombination of photogenerated electron-hole pairs.

  2. Intercalation chemistry of zirconium 4-sulfophenylphosphonate

    Energy Technology Data Exchange (ETDEWEB)

    Svoboda, Jan [Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovský Sq. 2, 162 06 Prague 6 (Czech Republic); Zima, Vítězslav, E-mail: vitezslav.zima@upce.cz [Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovský Sq. 2, 162 06 Prague 6 (Czech Republic); Melánová, Klára [Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovský Sq. 2, 162 06 Prague 6 (Czech Republic); Beneš, Ludvík [Faculty of Chemical Technology, University of Pardubice, 532 10 Pardubice (Czech Republic); Trchová, Miroslava [Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovský Sq. 2, 162 06 Prague 6 (Czech Republic)

    2013-12-15

    Zirconium 4-sulfophenylphosphonate is a layered material which can be employed as a host for the intercalation reactions with basic molecules. A wide range of organic compounds were chosen to represent intercalation ability of zirconium 4-sulfophenylphosphonate. These were a series of alkylamines from methylamine to dodecylamine, 1,4-phenylenediamine, p-toluidine, 1,8-diaminonaphthalene, 1-aminopyrene, imidazole, pyridine, 4,4′-bipyridine, poly(ethylene imine), and a series of amino acids from glycine to 6-aminocaproic acid. The prepared compounds were characterized by powder X-ray diffraction, thermogravimetry analysis and IR spectroscopy and probable arrangement of the guest molecules in the interlayer space of the host is proposed based on the interlayer distance of the prepared intercalates and amount of the intercalated guest molecules. - Graphical abstract: Nitrogen-containing organic compounds can be intercalated into the interlayer space of zirconium 4-sulfophenylphosphonate. - Highlights: • Zirconium 4-sulfophenylphosphonate was examined as a host material in intercalation chemistry. • A wide range of nitrogen-containing organic compounds were intercalated. • Possible arrangement of the intercalated species is described.

  3. Thermodynamical and structural insights of orange II adsorption by Mg RAlNO 3 layered double hydroxides

    Science.gov (United States)

    Mustapha Bouhent, Mohamed; Derriche, Zoubir; Denoyel, Renaud; Prevot, Vanessa; Forano, Claude

    2011-05-01

    [Mg 1- x Al x(OH) 2][(NO 3) x, nH 2O] Layered Double Hydroxide (LDH) sorbents with variable Mg/Al molar ( R=(1- x)/ x) ratios were investigated for adsorption of azo dye, orange II (OII) at various pH and temperature conditions. Mg 2AlNO 3 displays the highest adsorption capacity with 3.611 mmol of OII per gram of Mg 2AlNO 3 at 40 °C. Adsorption isotherms have been fitted using the Langmuir model and free energy of adsorption (Δ G°), enthalpy (Δ H°) and entropy (Δ S°) were calculated. The experimental values for Δ G° in temperature range between 10 and 40 °C were found to be negative indicating that a spontaneous process occurred. Positive calculated enthalpy values, characteristic of an endothermic process were found. Characterization of solids (PXRD, FTIR, UV-vis, TGA/DTA, adsorption isotherm BET analysis, SEM and Zetametry) before and after adsorption showed that adsorption proceeds in two steps. First, adsorption occurs at the LDH surface, followed by intercalation via anion exchange.

  4. Layered Double Hydroxides as Effective Adsorbents for U(VI and Toxic Heavy Metals Removal from Aqueous Media

    Directory of Open Access Journals (Sweden)

    G. N. Pshinko

    2013-01-01

    Full Text Available Capacities of different synthesized Zn,Al-hydrotalcite-like adsorbents, including the initial carbonate [Zn4Al2(OH12]·CO3·8H2O and its forms intercalated with chelating agents (ethylenediaminetetraacetic acid (EDTA, diethylenetriaminepentaacetic acid (DTPA, and hexamethylenediaminetetraacetic acid (HMDTA and heat-treated form Zn4Al2O7, to adsorb uranium(VI and ions of toxic heavy metals have been compared. Metal sorption capacities of hydrotalcite-like adsorbents have been shown to correlate with the stability of their complexes with the mentioned chelating agents in a solution. The synthesized layered double hydroxides (LDHs containing chelating agents in the interlayer space are rather efficient for sorption purification of aqueous media free from U(VI irrespective of its forms of natural abundance (including water-soluble bi- and tricarbonate forms and from heavy metal ions. [Zn4Al2(OH12]·EDTA·nH2O is recommended for practical application as one of the most efficient and inexpensive synthetic adsorbents designed for recovery of both cationic and particularly important anionic forms of U(VI and other heavy metals from aqueous media. Carbonate forms of LDHs turned out to be most efficient for recovery of Cu(II from aqueous media with pH0≥7 owing to precipitation of Cu(II basic carbonates and Cu(II hydroxides. Chromate ions are efficiently adsorbed from water only by calcinated forms of LDHs.

  5. Mechanical and Morphological Properties of Poly-3-hydroxybutyrate/Poly(butyleneadipate-co-terephthalate/Layered Double Hydroxide Nanocomposites

    Directory of Open Access Journals (Sweden)

    Yen Leng Pak

    2013-01-01

    Full Text Available Nanocomposites of poly-3-hydroxybutyrate/poly(butyleneadipate-co-terephthalate/layered double hydroxide (PHB/PBAT/LDH were prepared from a binary blend of PHB/PBAT and stearate-Zn3Al LDH via a solution casting method using chloroform as solvent in this study. The pristine Zn3Al LDH was synthesized from nitrate salts solution at pH 7 by using coprecipitation technique and then was modified by stearate anions surfactant via ion exchange reaction. As a result, the basal spacing of the LDH was increased from 8.77 to 24.94 Å after the modification. Intercalated nanocomposites were formed due to the presence of diffraction peak in XRD diffractograms. The infrared spectrum of stearate-Zn3Al LDH exhibited the existence of stearate anions in the synthesized Zn3Al LDH. Mechanical properties with 2 wt% stearate-Zn3Al LDH loading nanocomposites showed 56 wt% improvements in elongation at break compared to those of the blend.

  6. In vitro antioxidant activity and in vivo antifatigue effect of layered double hydroxide nanoparticles as delivery vehicles for folic acid

    Directory of Open Access Journals (Sweden)

    Qin LL

    2014-12-01

    Full Text Available Lili Qin,1,* Wenrui Wang,2,* Songhui You,1 Jingmei Dong,1 Yunhe Zhou,1 Jibing Wang1 1Department of Physical Education, 2School of Life Science and Technology, Tongji University, Shanghai, People’s Republic of China *These authors contributed equally to this work Abstract: Folic acid antioxidants were successfully intercalated into layered double hydroxides (LDH nanoparticles according to a previous method with minor modification. The resultant folic acid-LDH constructs were then characterized by X-ray powder diffraction and transmission electron microscopy. The in vitro antioxidant activities, cytotoxicity effect, and in vivo anti­fatigue were examined by a series of assays. The results showed that folic acid-LDH antioxidant system can scavenge 1,1-diphenyl-2-picrylhydrazyl and hydroxyl free radicals and chelate pro-oxidative Cu2+. The in vitro cytotoxicity assays indicated that folic acid-LDH antioxidant system had no significant cytotoxic effect or obvious toxicity to normal cells. It also prolonged the forced swimming time of the mice by 32% and 51% compared to folic acid and control groups, respectively. It had an obvious effect on decreasing the blood urea nitrogen and blood lactic acid, while increasing muscle and hepatic glycogen levels. Therefore, folic acid-LDH might be used as a novel antioxidant and antifatigue nutritional supplement. Keywords: antioxidant supplementation, free radicals, biomaterials, drug delivery

  7. Coagulation Behavior of Graphene Oxide on Nanocrystallined Mg/Al Layered Double Hydroxides: Batch Experimental and Theoretical Calculation Study.

    Science.gov (United States)

    Zou, Yidong; Wang, Xiangxue; Ai, Yuejie; Liu, Yunhai; Li, Jiaxing; Ji, Yongfei; Wang, Xiangke

    2016-04-01

    Graphene oxide (GO) has attracted considerable attention because of its remarkable enhanced adsorption and multifunctional properties. However, the toxic properties of GO nanosheets released into the environment could lead to the instability of biological system. In aqueous phase, GO may interact with fine mineral particles, such as chloridion intercalated nanocrystallined Mg/Al layered double hydroxides (LDH-Cl) and nanocrystallined Mg/Al LDHs (LDH-CO3), which are considered as coagulant molecules for the coagulation and removal of GO from aqueous solutions. Herein the coagulation of GO on LDHs were studied as a function of solution pH, ionic strength, contact time, temperature and coagulant concentration. The presence of LDH-Cl and LDH-CO3 improved the coagulation of GO in solution efficiently, which was mainly attributed to the surface oxygen-containing functional groups of LDH-Cl and LDH-CO3 occupying the binding sites of GO. The coagulation of GO by LDH-Cl and LDH-CO3 was strongly dependent on pH and ionic strength. Results of theoretical DFT calculations indicated that the coagulation of GO on LDHs was energetically favored by electrostatic interactions and hydrogen bonds, which was further evidenced by FTIR and XPS analysis. By integrating the experimental results, it was clear that LDH-Cl could be potentially used as a cost-effective coagulant for the elimination of GO from aqueous solutions, which could efficiently decrease the potential toxicity of GO in the natural environment.

  8. Electrochemical Double Layered Capacitor Development and Implementation System

    Science.gov (United States)

    Strunk, Gavin P.

    Electrochemical Double Layered Capacitors (EDLC's) are becoming a more popular topic of research for hybrid power systems, especially vehicles. They are known for their high power density, high cycle life, low internal resistance, and wider operating temperature compared to batteries. They are rarely used as a standalone power source; however, because of their lack of energy density compared to batteries and fuel cells. Researchers are now discovering the benefits of using them in hybrid systems. The increased complexity of a hybrid power source presents many challenges. A major drawback of this complexity is the lack of design tools to assist a designer in translating a simulation all the way to a full scale implementation. A full spectrum of tools was designed to assist designers at all stages of implementation including: single cell testing, a multi-cell management system, and a full scale vehicle data acquisition system to monitor performance. First, the full scale vehicle data acquisition is described. The system is isolated from the electric shuttle bus it was tested on to allow the system to be ported to other vehicles and applications. This was done to modularize the system to characterize a wide variety of full scale applications. Next, a single cell test system was designed that allows the designer to characterize cell specifications, as well as, test control and safety systems in a controlled environment. The goal is to ensure safety systems can be thoroughly tested to ensure robustness as the bank is scaled up. This system also includes simulation models that provide examples of using the simulation to predict the behavior of a cell and the test system to validate the results of the simulation. This information is then used by the designer to more effectively design sensor ranges for the bank. Finally, a multi-cell EDLC management system was designed to implement a bank. It incorporates 12 series EDLC cells per control module, and the modular design

  9. Electrochemical intercalation of potassium into graphite in KF melt

    Energy Technology Data Exchange (ETDEWEB)

    Liu Dongren [College of Chemistry and Chemical Engineering, Central South University, South Lushan Road, Changsha 410083, Hunan (China); Department of Chemical and Environmental engineering, Jiaozuo University, JiaoZuo 454003, Henan (China); Yang Zhanhong, E-mail: zhyang@mail.csu.edu.c [College of Chemistry and Chemical Engineering, Central South University, South Lushan Road, Changsha 410083, Hunan (China); Li Wangxing; Qiu Shilin; Luo Yingtao [Zhengzhou Research Institute of Chalco, Zhengzhou 450041, Henan (China)

    2010-01-01

    Electrochemical intercalation of potassium into graphite in molten potassium fluoride at 1163 K was investigated by means of cyclic voltammetry, galvanostatic electrolysis and open-circuit potential measurements. It was found that potassium intercalated into graphite solely between graphite layers. In addition, the intercalation compound formed in graphite bulk in molten KF was quite unstable and decomposed very fast. X-ray diffraction measurements indicate that a very dilute potassium-graphite intercalation compound was formed in graphite matrix in the fluoride melt. Analysis with scanning electron microscope and transmission electron microscope shows that graphite was exfoliated to sheets and tubes due to lattice expansion caused by intercalation of potassium in molten KF.

  10. Synthesis of graphene oxide-intercalated alpha-hydroxides by metathesis and their decomposition to graphene/metal oxide composites

    OpenAIRE

    2010-01-01

    Graphene oxide-intercalated alpha-metal hydroxides were prepared using layers from the delaminated colloidal dispersions of cetyltrimethylammonium-intercalated graphene oxide and dodecylsulfate-intercalated alpha-hydroxide of nickel/cobalt as precursors. The reaction of the two dispersions leads to de-intercalation of the interlayer ions from both the layered solids and the intercalation of the negatively charged graphene oxide sheets between the positively charged layers of the alpha-hydroxi...

  11. Improved thermal stability of poly(vinyl chloride) by nanoscale layered double hydroxide particles grafted with toluene-2,4-di-isocyanate

    Energy Technology Data Exchange (ETDEWEB)

    Liu Jun [Beijing National Laboratory for Molecular Sciences (BNLMS), Laboratory of New Materials, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Key Laboratory of Aerospace Materials and Performance (Ministry of Education), School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Chen Guangming, E-mail: chengm@iccas.ac.cn [Beijing National Laboratory for Molecular Sciences (BNLMS), Laboratory of New Materials, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Yang Jiping, E-mail: jyang@buaa.edu.cn [Key Laboratory of Aerospace Materials and Performance (Ministry of Education), School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Ding Liping [Beijing National Laboratory for Molecular Sciences (BNLMS), Center for Physiochemical Analysis and Measurement (CPAM), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China)

    2009-12-15

    A novel interlamellar surface modification of layered double hydroxides (LDHs) via covalent bonding by toluene-2,4-di-isocyanate (TDI) has been successfully obtained, and poly(vinyl chloride) (PVC)/TDI-modified LDH nanocomposites have been prepared via solution intercalation process. After the interlamellar modification, TDI was grafted to the surface hydroxyl groups of LDHs with nitrate, dodecyl sulfate or stearate anion as counterion anion. The structures of the TDI-modified LDHs and the nanocomposites were characterized by powder X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectra, and transmission electron microscopy (TEM) techniques. The enhanced thermal stability of PVC/TDI-modified LDH nanocomposites was confirmed by means of conventional Congo Red test and dynamic thermogravimetric analysis (TGA). In addition, the thermal degradation mechanism was briefly discussed on the basis of the above experimental results.

  12. New treatment method for boron in aqueous solutions using Mg–Al layered double hydroxide: Kinetics and equilibrium studies

    Energy Technology Data Exchange (ETDEWEB)

    Kameda, Tomohito, E-mail: kameda@env.che.tohoku.ac.jp; Oba, Jumpei; Yoshioka, Toshiaki

    2015-08-15

    Highlights: • NO{sub 3}·Mg–Al LDHs and Cl·Mg–Al LDHs could take up boron from aqueous solutions. • Boron was removed by anion exchange of B(OH){sub 4}{sup −} with intercalated NO{sub 3}{sup −} and Cl{sup −}. • The residual concentration of B was less than the effluent standards in Japan. • The removal of B was well described by a pseudo second-order kinetic equation. • The adsorption of B followed a Langmuir-type adsorption. - Abstract: Mg–Al layered double hydroxides (LDHs) intercalated with NO{sub 3}{sup −} (NO{sub 3}·Mg–Al LDHs) and with Cl{sup −} (Cl·Mg–Al LDHs) were found to take up boron from aqueous solutions. Boron was removed by anion exchange of B(OH){sub 4}{sup −} in solution with NO{sub 3}{sup −} and Cl{sup −} intercalated in the interlayer of the LDH. Using three times the stoichiometric quantity of NO{sub 3}·Mg–Al LDH, the residual concentration of B decreased from 100 to 1.9 mg L{sup −1} in 120 min. Using five times the stoichiometric quantity of Cl·Mg–Al LDH, the residual concentration of B decreased from 100 to 5.6 mg L{sup −1} in 120 min. It must be emphasized that, in both cases, the residual concentration of B was less than the effluent standards in Japan (10 mg L{sup −1}). The rate-determining step of B removal by the NO{sub 3}·Mg–Al and Cl·Mg–Al LDHs was found to be chemical adsorption involving anion exchange of B(OH){sub 4}{sup −} with intercalated NO{sub 3}{sup −} and Cl{sup −}. The removal of B was well described by a pseudo second-order kinetic equation. The adsorption of B by NO{sub 3}·Mg–Al LDH and Cl·Mg–Al LDH followed a Langmuir-type adsorption. The values of the maximum adsorption and the equilibrium adsorption constant were 3.6 mmol g{sup −1} and 1.7, respectively, for NO{sub 3}·Mg–Al LDH, and 3.8 mmol g{sup −1} and 0.7, respectively, for Cl·Mg–Al LDH. The B(OH){sub 4}{sup −} in B(OH){sub 4}·Mg–Al LDH produced by removal of B was found to undergo

  13. Mesoporous layer-by-layer ordered nanohybrids of layered double hydroxide and layered metal oxide: highly active visible light photocatalysts with improved chemical stability.

    Science.gov (United States)

    Gunjakar, Jayavant L; Kim, Tae Woo; Kim, Hyo Na; Kim, In Young; Hwang, Seong-Ju

    2011-09-28

    Mesoporous layer-by-layer ordered nanohybrids highly active for visible light-induced O(2) generation are synthesized by self-assembly between oppositely charged 2D nanosheets of Zn-Cr-layered double hydroxide (Zn-Cr-LDH) and layered titanium oxide. The layer-by-layer ordering of two kinds of 2D nanosheets is evidenced by powder X-ray diffraction and cross-sectional high resolution-transmission electron microscopy. Upon the interstratification process, the original in-plane atomic arrangements and electronic structures of the component nanosheets remain intact. The obtained heterolayered nanohybrids show a strong absorption of visible light and a remarkably depressed photoluminescence signal, indicating an effective electronic coupling between the two component nanosheets. The self-assembly between 2D inorganic nanosheets leads to the formation of highly porous stacking structure, whose porosity is controllable by changing the ratio of layered titanate/Zn-Cr-LDH. The resultant heterolayered nanohybrids are fairly active for visible light-induced O(2) generation with a rate of ∼1.18 mmol h(-1) g(-1), which is higher than the O(2) production rate (∼0.67 mmol h(-1) g(-1)) by the pristine Zn-Cr-LDH material, that is, one of the most effective visible light photocatalysts for O(2) production, under the same experimental condition. This result highlights an excellent functionality of the Zn-Cr-LDH-layered titanate nanohybrids as efficient visible light active photocatalysts. Of prime interest is that the chemical stability of the Zn-Cr-LDH is significantly improved upon the hybridization, a result of the protection of the LDH lattice by highly stable titanate layer. The present findings clearly demonstrate that the layer-by-layer-ordered assembly between inorganic 2D nanosheets is quite effective not only in improving the photocatalytic activity of the component semiconductors but also in synthesizing novel porous LDH-based hybrid materials with improved chemical

  14. Effect of Zn/Al Layered Double Hydroxide Containing 2-Hydroxy-4-n-octoxy-benzophenone on UV Aging Resistance of Asphalt

    Directory of Open Access Journals (Sweden)

    Chao Peng

    2015-01-01

    Full Text Available UV radiation is a main factor to reduce the service life of asphalt pavement due to the UV aging of asphalt binder. To obtain enhanced UV aging resistance, an organic UV absorber called 2-hydroxy-4-n-octoxy-benzophenone (HNOB had been intercalated into an inorganic UV absorber called Zn/Al layered double hydroxide (LDH to play a combined anti-UV role in asphalt binder. Fourier transform infrared spectroscopy revealed that HNOB anions have been intercalated into the interlayer galleries of Zn/Al-LDH containing HNOB anions (Zn/Al-HNOB−-LDH. X-ray diffraction results of Zn/Al-LDH containing CO32− anions (Zn/Al-CO32--LDH and Zn/Al-CO32--LDH/styrene-butadiene-styrene (SBS modified asphalt disclosed that asphalt molecules entered into LDH interlayer galleries to form an expanded phase structure. UV-Vis absorbance patterns showed that Zn/Al-HNOB−-LDH has a better capacity of blocking UV light due to the synergetic effect of HNOB and Zn/Al-LDH. The chemical fractions analysis, conventional physical tests, and rheological tests of SBS modified asphalt, Zn/Al-CO32--LDH/SBS modified asphalt, and Zn/Al-HNOB−-LDH/SBS modified asphalt before and after UV aging testified that Zn/Al-HNOB−-LDH can improve the UV aging resistance of SBS modified asphalt more significantly.

  15. Drug delivery system for an anticancer agent, chlorogenate-Zn/Al-layered double hydroxide nanohybrid synthesised using direct co-precipitation and ion exchange methods

    Science.gov (United States)

    Barahuie, Farahnaz; Hussein, Mohd Zobir; Arulselvan, Palanisamy; Fakurazi, Sharida; Zainal, Zulkarnain

    2014-09-01

    A nano-structured drug-inorganic clay hybrid involving an active anticancer compound, which is chlorogenic acid (CA) intercalated into Zn/Al-layered double hydroxide, has been assembled via ion-exchange and co-precipitation methods to form a nanohybrid CZAE (a chlorogenic acid-Zn/Al nanohybrid synthesised using an ion-exchange method) and CZAC (a chlorogenic acid-Zn/Al nanohybrid synthesised using a direct method), respectively. The X-ray diffraction (XRD) results confirmed that the CA-LDH had a hybrid structure in which the anionic chlorogenate is arranged between the interlayers as a horizontal monolayer at 90 and 20° angles from the x axis for CZAE and CZAC, respectively. Both nanohybrids have the properties of mesoporous materials. The high loading percentage of chlorogenic acid (approximately 43.2% for CZAE and 45.3% for CZAC) with basal spacings of 11.7 and 12.6 Å for CZAE and CZAC, respectively, corroborates the successful intercalation of chlorogenic acid into the interlayer gallery of layered double hydroxides. Free chlorogenic acid and the synthesised nanocomposites (CZAE, CZAC) were assessed for their cytotoxicity against various cancer cells. The Fourier transform infrared data supported the formation of both nanohybrids, and a thermal analysis showed that the nanohybrids are more thermally stable than their counterparts. The chlorogenate shows a sustained release, and the release rate of chlorogenate from CZAE and CZAC nanohybrids at pH 7.4 is remarkably lower than that at pH 4.8 due to their different release mechanisms. The release rate of chlorogenate from both nanohybrids can be described as pseudo-second order. The present investigation revealed the potential of the nanohybrids to enhance the in vitro anti-tumour effect of chlorogenic acid in liver and lung cancer cells in vitro.

  16. Synthesis and Characterization of Chitosan-Coated Near-Infrared (NIR Layered Double Hydroxide-Indocyanine Green Nanocomposites for Potential Applications in Photodynamic Therapy

    Directory of Open Access Journals (Sweden)

    Pei-Ru Wei

    2015-09-01

    Full Text Available We designed a study for photodynamic therapy (PDT using chitosan coated Mg–Al layered double hydroxide (LDH nanoparticles as the delivery system. A Food and Drug Administration (FDA approved near-infrared (NIR fluorescent dye, indocyanine green (ICG with photoactive properties was intercalated into amine modified LDH interlayers by ion-exchange. The efficient positively charged polymer (chitosan (CS coating was achieved by the cross linkage using surface amine groups modified on the LDH nanoparticle surface with glutaraldehyde as a spacer. The unique hybridization of organic-inorganic nanocomposites rendered more effective and successful photodynamic therapy due to the photosensitizer stabilization in the interlayer of LDH, which prevents the leaching and metabolization of the photosensitizer in the physiological conditions. The results indicated that the polymer coating and the number of polymer coats have a significant impact on the photo-toxicity of the nano-composites. The double layer chitosan coated LDH–NH2–ICG nanoparticles exhibited enhanced photo therapeutic effect compared with uncoated LDH–NH2–ICG and single layer chitosan-coated LDH–NH2–ICG due to the enhanced protection to photosensitizers against photo and thermal degradations. This new class of organic-inorganic hybrid nanocomposites can potentially serve as a platform for future non-invasive cancer diagnosis and therapy.

  17. Study of 2,4-dichlorophenoxyacetic acid (2,4-D) removal by Cu-Fe-layered double hydroxide from aqueous solution

    Science.gov (United States)

    Nejati, Kamellia; Davary, Soheila; Saati, Marziye

    2013-09-01

    The hydrotalcite-like compound of Cu-Fe-layered double hydroxide was studied as a potential adsorbent of herbicide 2,4-dichlorophenoxyacetic acid (2,4-D). The nanoparticles of Cu-Fe layered double hydroxide were prepared by Cu/Fe molar ratio of 2:1 using a coprecipitation method at pH 8.5 and characterized by the X-ray powder diffraction (XRD), the Fourier transform infrared spectroscopy (FT-IR), the thermal gravimetric analysis (TGA) and the elemental analysis. The size and morphology of nanoparticles were examined by the transmission electron microscopy (TEM). The adsorption experiments on LDH, on the other hand, were conducted in three different procedures, namely, time-dependent, pH-dependent and temperature-dependent. Characterization of the adsorption products by the XRD method indicates that the intercalation of 2,4-D between the LDH layers has not occurred and the surface adsorption had taken place. The adsorption kinetic was tested for pseudo-first-order, pseudo-second-order, Elovich and Intra-particle diffusion kinetic models and the rate constants were calculated. The equilibrium adsorption data were described by Langmuir and Freundlich equations. It was observed that, the Langmuir isotherm slightly better fitted to the experimental data rather than that of Freundlich. In the adsorption experiments, the Gibbs free energy values, ΔG°, the enthalpy, ΔH°, and the entropy, ΔS° were also determined.

  18. Drug intercalation in layered double hydroxide clay: Application in the development of a nanocomposite film for guided tissue regeneration

    DEFF Research Database (Denmark)

    Chakraborti, M.; Jackson, J.K.; Plackett, David

    2011-01-01

    It has been proposed that localized and controlled delivery of alendronate and tetracycline to periodontal pocket fluids via guided tissue regeneration (GTR) membranes may be a valuable adjunctive treatment for advanced periodontitis. The objectives of this work were to develop a co-loaded, contr...

  19. RESISTANCE EFFECT OF ELECTRIC DOUBLE LAYER ON LIQUID FLOW IN MICROCHANNEL

    Institute of Scientific and Technical Information of China (English)

    GONG Lei; WU Jian-kang

    2006-01-01

    Poisson-Boltzmann equation for EDL (electric double layer) and NavierStokes equation for liquid flows were numerically solved to investigate resistance effect of electric double layer on liquid flow in microchannel. The dimension analysis indicates that the resistance effect of electric double layer can be estimated by an electric resistance number, which is proportional to the square of the liquid dielectric constant and the solid surface zeta potential, and inverse-proportional to the liquid dynamic viscosity, electric conductivity and the square of the channel width. An "electric current density balancing" (ECDB) condition was proposed to evaluate the flow-induced streaming potential,instead of conventional "electric current balancing" (ECB) condition which may induce spurious local backflow in neighborhood of the solid wall of the microchannel. The numerical results of the flow rate loss ratio and velocity profile are also given to demonstrate the resistance effect of electric double layer in microchannel.

  20. Unravelling the electrochemical double layer by direct probing of the solid/liquid interface

    Science.gov (United States)

    Favaro, Marco; Jeong, Beomgyun; Ross, Philip N.; Yano, Junko; Hussain, Zahid; Liu, Zhi; Crumlin, Ethan J.

    2016-08-01

    The electrochemical double layer plays a critical role in electrochemical processes. Whilst there have been many theoretical models predicting structural and electrical organization of the electrochemical double layer, the experimental verification of these models has been challenging due to the limitations of available experimental techniques. The induced potential drop in the electrolyte has never been directly observed and verified experimentally, to the best of our knowledge. In this study, we report the direct probing of the potential drop as well as the potential of zero charge by means of ambient pressure X-ray photoelectron spectroscopy performed under polarization conditions. By analyzing the spectra of the solvent (water) and a spectator neutral molecule with numerical simulations of the electric field, we discern the shape of the electrochemical double layer profile. In addition, we determine how the electrochemical double layer changes as a function of both the electrolyte concentration and applied potential.

  1. Characterization of Microporous Activated Carbon Electrodes for Electric Double-layer Capacitors

    Institute of Scientific and Technical Information of China (English)

    MENG Qing-han; LIU Ling; SONG Huai-he

    2004-01-01

    Activated carbons (ACs) with a wide range of surface areas were made from petroleum coke by means of KOH activation. The electrochemical characterization was carried out for several activated carbons used as polariz able electrodes of electric double-layer capacitors (EDLCs) in an aqueous electrolytic solution. The porous structures and electrochemical double-layer capacitance of the activated carbons were investigated by virtue of nitrogen gas adsorption and constant current cycling(CCC) methods. The relationship among the surface area, pore volume of the activated carbons and specific double-layer capacitance was discussed. It was found that the specific capacitance of ACs increased linearly with the increase of surface area. The presence of mesopores in the activated carbons with very high surface area(>2000 m2/g) was not very effective for them to be used as EDLCs. The influence of chemical characteristics of the activated carbons on the double layer formation could be considered to be negligible.

  2. Double-layer-gate architecture for few-hole GaAs quantum dots

    Science.gov (United States)

    Wang, D. Q.; Hamilton, A. R.; Farrer, I.; Ritchie, D. A.; Klochan, O.

    2016-08-01

    We report the fabrication of single and double hole quantum dots using a double-layer-gate design on an undoped accumulation mode {{Al}}x{{Ga}}1-x{As}/GaAs heterostructure. Electrical transport measurements of a single quantum dot show varying addition energies and clear excited states. In addition, the two-level-gate architecture can also be configured into a double quantum dot with tunable inter-dot coupling.

  3. Influence of binder solvent on carbon-layer structure in electrical-double-layer capacitors

    Indian Academy of Sciences (India)

    A Banerjee; P Suresh Kumar; A K Shukla

    2013-09-01

    Porous activated-carbons with a large surface-area have been the most common materials for electrical-double-layer capacitors (EDLCs). These carbons having a wide pore distribution ranges from micropores to macropores in conjunction with a random pore connection that facilitates the high specific-capacitance values. Pore distribution plays a central role in controlling the capacitance value of EDLCs, since electrolyte distribution inside the active material mainly depends on the pore distribution. This has a direct influence on the distribution of resistance and capacitance values within the electrode. As a result, preparation of electrodes remains a vital issue in realising high-performance EDLCs. Generally, carbon materials along with some binders are dispersed into a solvent and coated onto the current collectors. This study examines the role of binder solvents used for the carbon-ink preparation on the microstructure of the electrodes and the consequent performance of the EDLCs. It is observed that the physical properties of the binder solvent namely its dielectric constant, viscosity and boiling point have important role in determining the pore-size distribution as well as the microstructure of electrodes which influence their specific capacitance values.

  4. Anomalous double layer step formation on Si(100) in hydrogen ambient

    Energy Technology Data Exchange (ETDEWEB)

    Doescher, Henning; Kleinschmidt, Peter; Dobrich, Anja; Brueckner, Sebastian; Supplie, Oliver; Luczak, Johannes; Hannappel, Thomas [Helmholtz-Zentrum Berlin fuer Materialien und Energie, Berlin (Germany)

    2011-07-01

    Generation of double layer steps on Si(100) is desirable for subsequent anti-phase domain-free heteroepitaxy of III-V semiconductors. In UHV established procedures exist for the formation of double layer steps at the clean Si(100) surface. In the (metal-organic) vapour phase epitaxy environment the situation is more complicated due to the presence of hydrogen in the process ambient. Both theory and experiment of the hydrogenated surfaces suggest that under equilibrium conditions no preference for double layer steps is to be expected. Previously, we have shown that annealing in hydrogen at near atmospheric pressure leads to termination of the surface by monohydride. Here, we show that a process using Si(100) with an intermediate offcut of 2 in <011> can lead to a double layer stepped surface. Our process consists of deoxidation, homoepitaxial growth employing silane, annealing and slow cooling to 500 C in hydrogen ambient. We observe the formation of double layer steps using Fourier-transform infrared spectroscopy, low-energy electron diffraction and scanning tunneling microscopy. In sharp contrast to established UHV results, the double layer steps are of the D{sub A} type, where dimer rows of the reconstructed surface are parallel to the step edges.

  5. Thermal analysis of double-layer metal films during femtosecond laser heating

    Science.gov (United States)

    Chen, A. M.; Jiang, Y. F.; Sui, L. Z.; Liu, H.; Jin, M. X.; Ding, D. J.

    2011-05-01

    In this paper, the primary interest is the heat effect of the bottom-layer metal on the temperature distribution of the top-layer metal in a double-layer metal structure during femtosecond laser irradiation. The evolution of the surface electron and lattice temperature depends a lot on the thermal parameters of the substrate. The damage threshold can be increased by using a substrate material with high electron-lattice coupling factor. Next, we choose chrome as the bottom-layer material. The results of modeling show that the surface lattice temperature of top-layer gold can be reduced remarkably. For a fixed entire thickness of the double-layer film, there is an optimal proportion of top and bottom layers for which the damage threshold is the highest possible. Also, for increasing the damage threshold, a substrate with higher melting temperature should be chosen.

  6. Patch holography using a double layer microphone array

    DEFF Research Database (Denmark)

    Gomes, Jesper Skovhus

    in which the sound field is represented by a set of monopoles placed inside the source. In this paper these monopoles are distributed so that they surround the array, and the reconstruction is compared with the IBEM-based approach. The comparisons are based on computer simulations with a planar double...

  7. Double layers at amphifunctionally electrified interfaces in the presence of electrolytes containing specifically adsorbing ions

    NARCIS (Netherlands)

    Duval, J.F.L.; Kleijn, J.M.; Lyklema, J.; Leeuwen, van H.P.

    2002-01-01

    Amphifunctional double layers are defined by the coupling of electronic and ionic surface charging processes. They may be present at interfaces of the type metal | oxide layer | solution or semiconducting oxide | solution. In the present paper, the simultaneous effects of charge-determining ions H+/

  8. Mg/Al Ordering in Layered Double Hydroxides Revealed by Multinuclear NMR Spectroscopy

    DEFF Research Database (Denmark)

    Nielsen, Ulla Gro; Grey, Clare P.; Sideris, Paul J.

    2008-01-01

    The anion- exchange ability of layered double hydroxides ( LDHs) has been exploited to create materials for use in catalysis, drug delivery, and environmental remediation. The specific cation arrangements in the hydroxide layers of hydrotalcite- like LDHs, of general formula Mg1-x2+Alx3+OH2(Anion...

  9. Study of the Electrical Double Layer of a Spherical Micelle:Functional Theoretical Approach

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    By using the iterative method in functional theory, an analytic expression of the Poisson-Boltzmann equation (PB eq.), which describes the distribution of the potential of electrical double layer of a spherical micelle, has been carried out under the general potential condition for the first time. The method also can give the radius, the surface potential, and the thickness of the layer.

  10. Storylines in intercalation chemistry.

    Science.gov (United States)

    Lerf, A

    2014-07-21

    Intercalation chemistry will soon be a hundred years old. The period of greatest activity in this field of solid state chemistry and physics was from about 1970 to 1990. The intercalation reactions are defined as topotactic solid state reactions and the products--the intercalation compounds--are clearly distinguished from inclusion and interstitial compounds. After a short historical introduction emphasizing the pioneering work of Ulrich Hofmann, the central topics and concepts will be reviewed and commented on. The most important ones, in my view, are: dichalcogenide intercalation compounds, the electrochemical intercalation and the search for new battery electrodes, the physics of graphite intercalation compounds, and the staging and interstratification phenomena. The relation to other fields of actual research and the demands for forthcoming research will also be addressed.

  11. Intercalated hybrid graphite fiber composite

    Science.gov (United States)

    Gaier, James R. (Inventor)

    1993-01-01

    The invention is directed to a highly conductive lightweight hybrid material and methods of producing the same. The hybrid composite is obtained by weaving strands of a high strength carbon or graphite fiber into a fabric-like structure, depositing a layer of carbon onto the structure, heat treating the structure to graphitize the carbon layer, and intercalating the graphitic carbon layer structure. A laminate composite material useful for protection against lightning strikes comprises at least one layer of the hybrid material over at least one layer of high strength carbon or graphite fibers. The composite material of the present invention is compatible with matrix compounds, has a coefficient of thermal expansion which is the same as underlying fiber layers, and is resistant to galvanic corrosion in addition to being highly conductive. These materials are useful in the aerospace industry, in particular as lightning strike protection for airplanes.

  12. Fracture Characteristics Analysis of Double-layer Rock Plates with Both Ends Fixed Condition

    Directory of Open Access Journals (Sweden)

    S. R. Wang

    2014-07-01

    Full Text Available In order to research on the fracture and instability characteristics of double-layer rock plates with both ends fixed, the three-dimension computational model of double-layer rock plates under the concentrated load was built by using PFC3D technique (three-dimension particle flow code, and the mechanical parameters of the numerical model were determined based on the physical model tests. The results showed the instability process of the double-layer rock plates had four mechanical response phases: the elastic deformation stage, the brittle fracture of upper thick plate arching stage, two rock-arch bearing stage and two rock-arch failure stage; moreover, with the rock plate particle radius from small to large change, the maximum vertical force of double rock-arch appeared when the particle size was a certain value. The maximum vertical force showed an upward trend with the increase of the rock plate temperature, and in the case of the same thickness the maximum vertical force increased with the increase of the upper rock plate thickness. When the boundary conditions of double-layer rock plates changed from the hinged support to the fixed support, the maximum horizontal force observably decreased, and the maximum vertical force showed small fluctuations and then tended towards stability with the increase of cohesive strength of double-layer rock plates.

  13. Double-layered target and identification method of individual target correlated with evaporation residues

    Energy Technology Data Exchange (ETDEWEB)

    Kaji, D., E-mail: daiya@riken.jp; Morimoto, K.

    2015-08-21

    A double-layered target system and an identification method (target ID) for individual targets mounted on a rotating wheel using correlation with evaporation residues were newly developed for the study of superheavy elements (SHE). The target system can be used in three modes: conventional single-layered mode, double-layered mode, and energy-degrader mode. The target ID method can be utilized for masking a target, measuring an excitation function without changing the beam energy from the accelerator, and searching for SHE nuclides using multiple targets during a single irradiation.

  14. Wrinkle Behavior of Hydroforming of Aluminum Alloy Double-Layer Sheets

    Science.gov (United States)

    Zhou, Bin-Jun; Xu, Yong-Chao

    2016-07-01

    In this article, the wrinkling behavior and thickness distribution of 5A06 aluminum alloy sheets in an annealed state with thickness of 1.0 mm and 2.5 mm was numerically and experimentally investigated under different hydraulic pressures in the hydroforming of single-layer and double-layer sheets. Note that, in double-layer sheets hydroforming, an upper-aided sheet is needed. The upper, thicker sheet synchronously deforms with the lower, thinner sheet during hydroforming. When the double-layer sheets are separated, a thinner curved sheet part will be manufactured. As can be seen from the simulation and experimental results, the upper, thicker sheet could effectively suppress the wrinkles of the lower, thinner sheet and improve the thickness distribution due to the increasing anti-wrinkle ability of the formed sheet and the interfacial friction between the double-layer sheets. In addition, the maximum hydraulic pressure can be decreased via hydroforming of double-layer sheets; this approach reduces the drawing force for large sheet parts and meets the requirement of energy conservation.

  15. Laser ion acceleration from a double-layer metal foil

    Energy Technology Data Exchange (ETDEWEB)

    Lecz, Zsolt

    2013-11-12

    The laser-ion acceleration with ultra-intense and ultra-short laser pulses has opened a new field of accelerator physics over the last decade. Fast development in laser systems are capable of delivering short pulses of a duration of a few hundred femtoseconds at intensities between 10{sup 18}-10{sup 20} W/cm{sup 2}. At these high intensities the laser-matter interaction induces strong charge separation, which leads to electric fields exceeding the acceleration gradients of conventional devices by 6 orders of magnitude. The particle dynamics and energy absorption of the laser pulse can be understood by means of high-performance simulation tools. In the framework of the LIGHT (Laser Ion Generation, Handling and Transport) project our goal is to provide an analytical description of the 3D distribution of the protons accelerated via TNSA (Target Normal Sheath Acceleration). In this acceleration mechanism the short pulse impinging on a metal foil heats the electrons to relativistic energies, which triggers the strong charge separation field on the opposite target surface (Debye-sheath). The accelerated light ions (proton, carbon, oxygen) observed in the experiments originate from the contamination layer deposited on the surface. The thickness of this layer in the experiments is not known exactly. According to our study these ions can be accelerated in three different regimes depending on layer thickness: quasi-static acceleration (QSA, for thin layers), plasma expansion (for thick layers) and a not well understood intermediate (or combined) regime. In a laser-plasma simulations time-dependent hot electron density and temperature are observed, therefore we performed plasma simulations with a well defined and constant initial hot electron distribution. Thus the simulation results are easier to compare with analytical models. In our case the theoretical investigation of the TNSA involves the understanding of the charge separation effects at the surface of a two

  16. High Corrosion-Resistance Double-Layer Ni-P Coating on Steels

    Institute of Scientific and Technical Information of China (English)

    JIANG Hai; LIU Xian-li; JIANG Zhang-hao; LI Guang-yu; LIAN Jian-she; GU Chang-dong

    2004-01-01

    Double-layer Ni-P alloy coating with a thickness about 20 μm and different Ni-P layers was prepared by electroless deposition and its corrosion resistance was studied. The microstructure and corrosion-resistance of the coatings were analyzed by SEM, XRD, electrochemical polarization measurements and salt spray tests. The salt spray tests showed that the double-layer coating exhibits better corrosion resistance. The time of the emergence of the first red rust spot on the coating surface can reach 384 hours, and the gray rusts were firstly emergered during the salt spray tests. The electrochemical analysis revealed that the difference in the corrosion potential between the double layers plays a very important role in protecting the substrate from rusting.

  17. NUMERICAL MODELING OF THE PROBLEM OF DOUBLE-LAYER REINFORCEMENT

    Directory of Open Access Journals (Sweden)

    Nizomov Dzhakhongir Nizomovich

    2012-10-01

    The proposed solution is applicable in the lining of tunnels and subterranean structures in rock massifs, as well as galleries arranged in the body of earth dams. It represents two layers of concrete with different values of the modulus of elasticity and Poisson ratio. Tangential stress and reinforcement ring graphs are presented in the article.

  18. Improved Reliability of Small Molecule Organic Solar Cells by Double Anode Buffer Layers

    Directory of Open Access Journals (Sweden)

    Pao-Hsun Huang

    2014-01-01

    Full Text Available An optimized hybrid planar heterojunction (PHJ of small molecule organic solar cells (SM-OSCs based on copper phthalocyanine (CuPc as donor and fullerene (C60 as acceptor was fabricated, which obviously enhanced the performance of device by sequentially using both MoO3 and pentacene as double anode buffer layers (ABL, also known as hole extraction layer (HEL. A series of the vacuum-deposited ABL, acting as an electron and exciton blocking layer, were examined for their characteristics in SM-OSCs. The performance and reliability were compared between conventional ITO/ABL/CuPc/C60/BCP/Ag cells and the new ITO/double ABL/CuPc/C60/BCP/Ag cells. The effect on the electrical properties of these materials was also investigated to obtain the optimal thickness of ABL. The comparison shows that the modified cell has an enhanced reliability compared to traditional cells. The improvement of lifetime was attributed to the idea of double layers to prevent humidity and oxygen from diffusing into the active layer. We demonstrated that the interfacial extraction layers are necessary to avoid degradation of device. That is to say, in normal temperature and pressure, a new avenue for the device within double buffer layers has exhibited the highest values of open circuit voltage (Voc, fill factor (FF, and lifetime in this work compared to monolayer of ABL.

  19. Design of a beta-hairpin peptide-intercalator conjugate for simultaneous recognition of single stranded and double stranded regions of RNA.

    Science.gov (United States)

    Cline, Lauren L; Waters, Marcey L

    2009-11-21

    Designing receptors that bind RNA is a challenging endeavor because of the unique and sometimes complex structure of RNA. However these structural features provide regions for ligands to bind using different types of interactions. To increase specificity and binding affinity to RNA, divalent systems have been designed which incorporate more than one binding motif into one molecule. Using this approach, we have designed a two part heteroconjugate, WKWK-Int, which contains a beta-hairpin peptide covalently linked to an RNA intercalator. This heteroconjugate was designed to bind duplex RNA through intercalation and simultaneously interact with a single stranded bulge region using the side chains of the beta-hairpin peptide. We have used fluorescence anisotropy experiments to show that the heteroconjugate has an increased binding affinity over either one of the individual ligands. Additionally, RNase footprinting experiments show that the structure of the peptide is necessary for the protection of one particular base in the RNA bulge region. When tested against other RNA molecules containing a stem-bulge structure, the designed heteroconjugate was found to be specific for this RNA sequence. This work provides evidence that the covalent linkage of two weak RNA ligands can greatly increase the binding affinity and also provide specificity to the binding event.

  20. Double Charged Surface Layers in Lead Halide Perovskite Crystals

    KAUST Repository

    Sarmah, Smritakshi P.

    2017-02-01

    Understanding defect chemistry, particularly ion migration, and its significant effect on the surface’s optical and electronic properties is one of the major challenges impeding the development of hybrid perovskite-based devices. Here, using both experimental and theoretical approaches, we demonstrated that the surface layers of the perovskite crystals may acquire a high concentration of positively charged vacancies with the complementary negatively charged halide ions pushed to the surface. This charge separation near the surface generates an electric field that can induce an increase of optical band gap in the surface layers relative to the bulk. We found that the charge separation, electric field, and the amplitude of shift in the bandgap strongly depend on the halides and organic moieties of perovskite crystals. Our findings reveal the peculiarity of surface effects that are currently limiting the applications of perovskite crystals and more importantly explain their origins, thus enabling viable surface passivation strategies to remediate them.

  1. Manufacturing uniform field silicon drift detector using double boron layer

    Energy Technology Data Exchange (ETDEWEB)

    Golshani, Negin, E-mail: negingolshani@gmail.com; Beenakker, C.I.M; Ishihara, R.

    2015-09-11

    Novel SDDs with continuous junctions on both sides are fabricated using pure boron (PureB) depositions to create a shallow junction in the entrance window side and a continuous rectifying junction with different potentials as function of the drift coordinate in the device side. The SDDs made in this material offer lower leakage current. In addition, continuous SDD designed with two boron layers with different sheet resistances displays uniform electric field.

  2. Umbilical Cord Mesenchymal Stem Cells Combined With a Collagenfibrin Double-layered Membrane Accelerates Wound Healing.

    Science.gov (United States)

    Nan, Wenbin; Liu, Rui; Chen, Hongli; Xu, Zhihao; Chen, Jiannan; Wang, Manman; Yuan, Zhiqing

    2015-05-01

    The aim of this study was to examine the effects of human umbilical cord mesenchymal stem cells (hUCMSCs) in combination with a collagen-fibrin double-layered membrane on wound healing in mice. A collagen-fibrin double-layered membrane was prepared, and the surface properties of the support material were investigated using a scanning electron microscope. Twenty-four mice were prepared for use as full-thickness skin wound models and randomly divided into 3 groups: group A, a control group in which the wounds were bound using a conventional method; group B, a group treated with hUCMSCs combined with a collagen membrane; and group C, a group treated with hUCMSCs combined with a collagen-fibrin double-layered membrane. The postoperative concrescence of the wounds was observed daily to evaluate the effects of the different treatments. Scanning electron microscope observation showed the collagen-fibrin scaffolds exhibited a highly porous and interconnected structure, and wound healing in the double-layered membrane group was better than in groups A or B. Treatment with hUCMSCs combined with a collagen-fibrin double-layered membrane accelerated wound healing.

  3. Double-layered ZnO nanostructures for efficient perovskite solar cells

    KAUST Repository

    Mahmood, Khalid

    2014-01-01

    To date, a single layer of TiO2 or ZnO has been the most successful implementations of any electron transport layer (ETL) in solution-processed perovskite solar cells. In a quest to improve the ETL, we explore a new nanostructured double-layer ZnO film for mesoscopic perovskite-based thin film photovoltaics. This approach yields a maximum power conversion efficiency of 10.35%, which we attribute to the morphology of oxide layer and to faster electron transport. The successful implementation of the low-temperature hydrothermally processed double-layer ZnO film as ETL in perovskite solar cells highlights the opportunities to further improve the efficiencies by focusing on the ETL in this rapidly developing field. This journal is

  4. Cladding layer on well-defined double-wall TiO2 nanotubes.

    Science.gov (United States)

    Xue, Chaorui; Yonezawa, Tetsu; Nguyen, Mai Thanh; Lu, Xu

    2015-02-03

    Highly ordered double-wall TiO2 nanotube arrays were obtained by a two-step anodization method in a fluoride-containing glycerol based electrolyte. The low water and fluoride content and high viscosity of the electrolyte support a partly undissolved fluoride-rich layer, and its hydrolyzed products remain on the tube walls. The double-wall structure and a cladding layer originating from the fluoride-rich layer were clearly observed after annealing. The morphology and crystal structure of the cladding layer were investigated. The study of the cladding layer gives a fundamental insight into the wall structure design of the anodic TiO2 nanotubes in the glycerol-based electrolyte.

  5. In situ platelets formation into aqueous polymer colloids: The topochemical transformation from single to double layered hydroxide (LSH-LDH) uncovered.

    Science.gov (United States)

    Stimpfling, Thomas; Langry, Arthur; Hintze-Bruening, Horst; Leroux, Fabrice

    2016-01-15

    Layered Single Hydroxide (LSH) of chemical composition Zn5(OH)8(acetate)2·nH2O is synthesized under in situ condition in an aqueous dispersion of an amphiphilic, carboxylate bearing polyester via a modified polyol route. The one-pot LSH generation yields agglomerates of well intercalated platelets, 9-10nm separated from each other. However the corresponding Layered Double Hydroxide (LDH) of formal composition Zn2Al(OH)6 (acetate)·nH2O is found to proceed via the formation of crystallized, similarly spaced LSH sheets in the neighborhood of amorphous Al rich domains as evidenced by X-ray diffraction and transmission electron micrographs. The initial phase segregation effaces over time while LSH platelets convert into the LDH phase. Fingerprinted by the change of in-plane cation accommodation, the associated topochemical reaction of the edge-sharing octahedral LSH platelets involves the transformation of metal lacunae, adjacently covered by one tetrahedral coordinated cation on each side to balance the negative surcharge, into fully occupied and monolayered platelets of edge-sharing octahedral LDH, the former voids being occupied by trivalent cations. This replenishing process of empty sites, coupled with the dissolution of tetrahedral sites is likely to be observed for the first time due to the presence of well separated, polymer intercalated platelets. TEM pictures vision crystal growth arising from the zone of the LSH edge-slab and by using solid state kinetics formalism the associated high activation energy of the first-order reaction agrees well with a plausible dissolution re-precipitation mechanism. The conversion of LSH into LDH platelets may be extended to others cations as Co(2+), Cu(2+), as well as the aluminum source (AlCl3) and the water-soluble polymer (NVP), thus indicating it is a new prevalent facet of LDH.

  6. Application of double-layered skin phantoms for optical flow imaging during laser tattoo treatments

    Science.gov (United States)

    Lee, Byeong-il; Song, Woosub; Kim, Hyejin; Kang, Hyun Wook

    2016-05-01

    The feasible application of double-layered skin phantoms was evaluated to identify artificial blood flow with a Doppler optical coherence tomography (DOCT) system for laser tattoo treatments. Polydimethylsiloxane (PDMS) was used to fabricate the artificial phantoms with flow channels embedded. A double-integrating sphere system with an inverse adding-doubling method quantified both the absorption and the reduced scattering coefficients for epidermis and dermis phantoms. Both OCT and caliper measurements confirmed the double-layered phantom structure (epidermis = 136 ± 17 µm vs. dermis = 3.0 ± 0.1 mm). The DOCT method demonstrated that high flow rates were associated with high image contrast, visualizing the position and the shape of the flow channel. Application of the channel-embedded skin phantoms in conjunction with DOCT can be a reliable technique to assess dynamic variations in the blood flow during and after laser tattoo treatments.

  7. A novel controllable double-layer magnetic lattice with cold atoms

    Institute of Scientific and Technical Information of China (English)

    Min Yun; Jianping Yin

    2005-01-01

    We propose a novel array of controllable double-well magnetic microtraps for cold atoms by using an array of square current-carrying wires and two additional bias magnetic fields. Arrays of double layer magnetooptical traps (MOTs) and Ioffe traps can be constructed by using same wire configurations and different currents and bias fields. Furthermore, the array of double-well magnetic microtraps can be continuously evolved as an array of single-well magnetic microtraps by reducing the currents in the wires. Our study shows that our scheme can be used to realize a controllable double-layer magnetic lattice with cold atoms, to form array of Bose-Einstein condensations (BECs), or to study atom interference, and so on.

  8. An optical sensor based on H-acid/layered double hydroxide composite film for the selective detection of mercury ion.

    Science.gov (United States)

    Sun, Zhiyong; Jin, Lan; Zhang, Shitong; Shi, Wenying; Pu, Min; Wei, Min; Evans, David G; Duan, Xue

    2011-09-19

    A novel optical chemosensor was fabricated based on 1-amino-8-naphthol-3,6-disulfonic acid sodium (H-acid) intercalated layered double hydroxide (LDH) film via the electrophoretic deposition (EPD) method. The film of H-acid/LDH with the thickness of 1 μm possesses a well c-orientation of the LDH microcrystals confirmed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The fluorescence detection for Hg(II) in aqueous solution was performed by using the H-acid/LDH film sensor at pH 7.0, with a linear response range in 1.0 × 10(-7) to 1.0 × 10(-5) mol L(-1) and a detection limit of 6.3 × 10(-8) mol L(-1). Furthermore, it exhibits excellent selectivity for Hg(II) over a large number of competitive cations including alkali, alkaline earth, heavy metal and transitional metals. The specific fluorescence response of the optical sensor is attributed to the coordination between Hg(II) and sulfonic group in the H-acid immobilized in the LDH matrix, which was verified by NMR spectroscopy and UV-vis spectra. In addition, density functional theory (DFT) calculation further confirms that the coordination occurs between one Hg(2+) and two O atoms in the sulfonic group, which is responsible for the significant fluorescence quenching of the H-acid/LDH film. The results indicate that the H-acid/LDH composite film can be potentially used as a chemosensor for the detection of Hg(2+) in the environmental and biomedical field.

  9. Synthesis of mesoporous Cu/Mg/Fe layered double hydroxide and its adsorption performance for arsenate in aqueous solutions

    Institute of Scientific and Technical Information of China (English)

    Yanwei Guo; Zhiliang Zhu; Yanling Qiu; Jianfu Zhao

    2013-01-01

    The mesoporous Cu/Mg/Fe layered double hydroxide (Cu/Mg/Fe-LDH) with carbonate intercalation was synthesized and used for the removal of arsenate from aqueous solutions.The Cu/Mg/Fe-LDH was characterized by Fourier transform infrared spectrometry,X-ray diffraction crystallography,scanning electron microscopy,X-ray photoelectron spectroscopy and Brunauer-Emmett-Teller.Effects of various physico-chemical parameters such as pH,adsorbent dosage,contact time and initial arsenate concentration on the adsorption of arsenate onto Cu/Mg/Fe-LDH were investigated.Results showed that it was efficient for the removal of arsenate,and the removal efficiency of arsenate increased with the increment of the adsorbent dosage,while the arsenate adsorption capacity decreased with increase of initial pH from 3 to 11.The adsorption isotherms can be well described by the Langmuir model with R2 > 0.99.Its adsorption kinetics followed the pseudo second-order kinetic model.Coexisting ions such as HPO42-,CO32-,SO42-and NO3-could compete with arsenate for adsorption sites on the Cu/Mg/Fe-LDH.The adsorption of arsenate on the adsorbent can be mainly attributed to the ion exchange process.It was found that the synthesized Cu/Mg/Fe-LDH can reduce the arsenate concentration down to a final level of < 10 μg/L under the experimental conditions,and makes it a potential material for the decontamination of arsenate polluted water.

  10. Layered double hydroxides as an effective additive in polymer gelled electrolyte based dye-sensitized solar cells.

    Science.gov (United States)

    Ho, Hsu-Wen; Cheng, Wei-Yun; Lo, Yu-Chun; Wei, Tzu-Chien; Lu, Shih-Yuan

    2014-10-22

    Layered double hydroxides (LDH), a class of anionic clay materials, were developed as an effective additive for polymer gelled electrolytes for use in dye-sensitized solar cells (DSSC). Carbonate and chloride intercalated Zn-Al LDHs, ZnAl-CO3 LDH, and ZnAl-Cl LDH were prepared with coprecipitation methods. The addition of the two LDHs significantly improved, in terms of power conversion efficiency (PCE), over the plain poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) gelled electrolyte and competed favorably with the liquid electrolyte based DSSCs, 8.13% for the liquid electrolyte, 7.48% for the plain PVDF-HFP gelled electrolyte, 8.11% for the ZnAl-CO3 LDH/PVDF-HFP gelled electrolyte, and 8.00% for the ZnAl-Cl LDH/PVDF-HFP gelled electrolyte based DSSCs. The good performance in PCEs achieved by the LDH-loaded DSSCs came mainly from the significant boost in open circuit voltages (Voc), from 0.74 V for both the liquid electrolyte and PVDF-HFP gelled electrolyte based DSSCs to 0.79 V for both the ZnAl-CO3 LDH/PVDF-HFP and ZnAl-Cl LDH/PVDF-HFP gelled electrolyte based DSSCs. The boost in Voc was contributed mainly by the positive shift in redox potential of the redox couple, I(-)/I3(-), as revealed from cyclic voltammetry analyses. As for the long-term stability, PCE retention rates of 96 and 99% after 504 h were achieved by the ZnAl-CO3 LDH/PVDF-HFP and ZnAl-Cl LDH/PVDF-HFP gelled electrolyte based DSSCs, respectively, appreciably better than 92% achieved by the liquid electrolyte based one after 480 h.

  11. New Power Lateral Double Diffused Metal-Oxide-Semiconductor Transistor with a Folded Accumulation Layer

    Institute of Scientific and Technical Information of China (English)

    DUAN Bao-Xing; ZHANG Bo; LI Zhao-Ji

    2007-01-01

    A new lateral double diffused metal oxide semiconductor field effect transistor with a double-charge accumulation layer using a folded silicon substrate is proposed to improve the performance of the breakdown voltage and specific on-resistance. Three kinds of technologies, which are the additional electric field modulation effect, majority carrier accumulation and increasing the effective conduction area, are applied simultaneously by a semi-insulating polycrystalline silicon layer deposited over the top of thin oxide covering the drift region. It is indicated that by the simulator, the ideal silicon limits of the breakdown voltage and specific on-resistance have been broken due to the complete three-dimensional reduced surface field effect and the doubled majority carrier accumulation layer.

  12. A Ni-Fe Layered Double Hydroxide-Carbon Nanotube Complex for Water Oxidation

    CERN Document Server

    Gong, Ming; Wang, Hailiang; Liang, Yongye; Wu, Justin Zachary; Zhou, Jigang; Wang, Jian; Regier, Tom; Wei, Fei; Dai, Hongjie

    2013-01-01

    Highly active, durable and cost-effective electrocatalysts for water oxidation to evolve oxygen gas hold a key to a range of renewable energy solutions including water splitting and rechargeable metal-air batteries. Here, we report the synthesis of ultrathin nickel iron layered double hydroxide nanoplates on mildly oxidized multi-walled carbon nanotubes. Incorporation of Fe into the nickel hydroxide induced the formation of NiFe-layered double hydroxide. The nanoplates were covalently attached to a network of nanotubes, affording excellent electrical wiring to the nanoplates. The ultra-thin Ni-Fe layered double hydroxide nanoplates/carbon nanotube complex was found to exhibit unusually high electro-catalytic activity and stability for oxygen evolution and outperformed commercial precious metal Ir catalysts.

  13. Low frequency solitons and double layers in a magnetized plasma with two temperature electrons

    Energy Technology Data Exchange (ETDEWEB)

    Rufai, O. R. [Department of Physics, University of the Western Cape, Private Bag X17, Bellville 7535 (South Africa); Bharuthram, R. [Office of the Deputy Vice Chancellor (Academic), University of the Western Cape, Bellville (South Africa); Singh, S. V. [Indian Institute of Geomagnetism, New Panvel (W), Navi Mumbai-410218 (India); School of Chemistry and Physics, University of Kwa-Zulu Natal, Durban (South Africa); Lakhina, G. S. [Indian Institute of Geomagnetism, New Panvel (W), Navi Mumbai-410218 (India)

    2012-12-15

    Finite amplitude non-linear ion-acoustic solitary waves and double layers are studied in a magnetized plasma with cold ions fluid and two distinct groups of Boltzmann electrons, using the Sagdeev pseudo-potential technique. The conditions under which the solitary waves and double layers can exist are found both analytically and numerically. We have shown the existence of negative potential solitary waves and double layers for subsonic Mach numbers, whereas in the unmagnetized plasma they can only in the supersonic Mach number regime. For the plasma parameters in the auroral region, the electric field amplitude of the solitary structures comes out to be 49 mV/m which is in agreement of the Viking observations in this region.

  14. Droplet transfer behavior of the stainless steel coated electrode with double-layer coating

    Institute of Scientific and Technical Information of China (English)

    孙咸; 马成勇; 王宝; 张汉谦

    2002-01-01

    In this paper, the droplet transfer behavior of the stainless steel coated electrode with double-layer coating is researched by means of those experimental methods, such as high speed camera, collecting droplet in water, surfacing on the steel plate et al. The results show that the droplet transfer indexes of coated electrode are mainly controlled by the size of droplet, which affects the transfer behavior of droplet. The distribution characteristic of the droplet size of the electrode affects the numerical relationship among droplet transfer indexes. The metallurgical process of the coated electrode with double-layer coating is carried out continuously in different zones. The main reason for the coated electrode with double-layer coating gaining excellent usability quality is that the droplets realize the "quasi flux wall guided transfer pattern".

  15. Interfacial double layer mediated electrochemical growth of thin-walled platinum nanotubes

    Science.gov (United States)

    Zhang, Liqiu; Kim, Sang Min; Cho, Sanghyun; Jang, Hee-Jeong; Liu, Lichun; Park, Sungho

    2017-01-01

    This work demonstrates that thin-walled platinum nanotubes can be readily synthesized by controlling the interfacial double layer in alumina nanochannels. The gradient distribution of ions in nanochannels enables the creation of Pt nanotubes with walls as thin as 5 nm at the top end when using a solution containing polyvinylpyrrolidone (PVP) and chloroplatinic acid (H2PtCl6) under the influence of an electric potential in nanochannels. The highly efficient formation of thin-walled Pt nanotubes is a result of the concentration gradient of {{{{PtCl}}}6}2- and a thick double layer, which was caused by the low concentration of Pt precursors and the enhanced surface charge density induced by protonated PVP steric adsorption. This well-controlled synthesis reveals that the interfacial double layer is a useful tool to tailor the structure of nanomaterials in a nanoscale space, and holds promise in the construction of more complex functional nanostructures.

  16. New insights into the intercalation chemistry of Al(OH)3.

    Science.gov (United States)

    Williams, Gareth R; Moorhouse, Saul J; Prior, Timothy J; Fogg, Andrew M; Rees, Nicholas H; O'Hare, Dermot

    2011-06-14

    This paper reports a number of recent developments in the intercalation chemistry of Al(OH)(3). From Rietveld refinement and solid-state NMR, it has been possible to develop a structural model for the recently reported [M(II)Al(4)(OH)(12)](NO(3))(2)·yH(2)O family of layered double hydroxides (LDHs). The M(2+) cations occupy half of the octahedral holes in the Al(OH)(3) layers, and it is thought that there is complete ordering of the metal ions while the interlayer nitrate anions are highly disordered. Filling the remainder of the octahedral holes in the layers proved impossible. While the intercalation of Li salts into Al(OH)(3) is facile, it was found that the intercalation of M(II) salts is much more capricious. Only with Co, Ni, Cu, and Zn nitrates and Zn sulfate were phase-pure LDHs produced. In other cases, there is either no reaction or a phase believed to be an LDH forms concomitantly with impurity phases. Reacting Al(OH)(3) with mixtures of M(II) salts can lead to the production of three-metal M(II)-M(II)'-Al LDHs, but it is necessary to control precisely the starting ratios of the two M(II) salts in the reaction gel because Al(OH)(3) displays selective intercalation of M nitrate (Li > Ni > Co ≈ Zn). The three-metal M(II)-M(II)'-Al LDHs exhibit facile ion exchange intercalation, which has been investigated in the first energy dispersive X-ray diffraction study of a chemical reaction system performed on Beamline I12 of the Diamond Light Source.

  17. Megavolt parallel potentials arising from double-layer streams in the Earth's outer radiation belt.

    Science.gov (United States)

    Mozer, F S; Bale, S D; Bonnell, J W; Chaston, C C; Roth, I; Wygant, J

    2013-12-06

    Huge numbers of double layers carrying electric fields parallel to the local magnetic field line have been observed on the Van Allen probes in connection with in situ relativistic electron acceleration in the Earth's outer radiation belt. For one case with adequate high time resolution data, 7000 double layers were observed in an interval of 1 min to produce a 230,000 V net parallel potential drop crossing the spacecraft. Lower resolution data show that this event lasted for 6 min and that more than 1,000,000 volts of net parallel potential crossed the spacecraft during this time. A double layer traverses the length of a magnetic field line in about 15 s and the orbital motion of the spacecraft perpendicular to the magnetic field was about 700 km during this 6 min interval. Thus, the instantaneous parallel potential along a single magnetic field line was the order of tens of kilovolts. Electrons on the field line might experience many such potential steps in their lifetimes to accelerate them to energies where they serve as the seed population for relativistic acceleration by coherent, large amplitude whistler mode waves. Because the double-layer speed of 3100  km/s is the order of the electron acoustic speed (and not the ion acoustic speed) of a 25 eV plasma, the double layers may result from a new electron acoustic mode. Acceleration mechanisms involving double layers may also be important in planetary radiation belts such as Jupiter, Saturn, Uranus, and Neptune, in the solar corona during flares, and in astrophysical objects.

  18. Transport spectroscopy in bilayer graphene using double layer heterostructures

    Science.gov (United States)

    Lee, Kayoung; Jung, Jeil; Fallahazad, Babak; Tutuc, Emanuel

    2017-09-01

    We provide a comprehensive study of the chemical potential of bilayer graphene in a wide range of carrier density, at zero and high magnetic (B)-fields, and at different transverse electric (E)-fields, using high quality double bilayer graphene heterostructures. Using a direct thermodynamic transport spectroscopic technique, we probe the chemical potential as a function of carrier density in six samples. The data clearly reveal the non-parabolicity and electron-hole asymmetry of energy-momentum dispersion in bilayer graphene. The tight-binding hopping amplitudes, t 0, t 1, and t 4, renormalized by electron-electron interaction are extracted from the chemical potential versus density dependence. A diverse set of electron-electron interaction driven phenomena were also clearly discerned at zero and high B-fields. We measure the gaps at integer fillings with orbital index N  =  0, 1, and discuss about the dependence of the N  =  0, 1 quantum Hall phases on the carrier density (or filling factor), E-field, and B-field.

  19. Impact single versus double layer uterine closure in caesarean section to uterine rupture

    OpenAIRE

    Budi Iman Santoso; Raymond Surya; Rima Irwinda

    2016-01-01

    Caesarean section (CS) is one of the most frequent delivery methods in the world whereas the rates of CS were varied according to developing (from 3.5 to 29.2%) and developed countries (21.1%). The study aims to known the impact of single versus double layer uterine closure to uterine rupture in the history of cesarean section (CS). In this case report, the clinical question is single versus double-layer uterine closure on the previous CS, gives better outcome to reduce the risk of uterine ru...

  20. Tooth preparation and fabrication of porcelain veneers using a double-layer technique.

    Science.gov (United States)

    Chpindel, P; Cristou, M

    1994-09-01

    This article discusses proper tooth preparation when using the double-layered porcelain technique for constructing porcelain veneers designed to produce strength and translucency. Indications for this technique include color correction, restoration of lost tooth structure or improper tooth size, and overall smile design. A new indication--misalignment--has been added. The objective of this article is to review tooth preparation and double-layered laboratory techniques using hydrothermal ceramics in combination. Four cases are used to illustrate the procedure, concentrating on the correction of misaligned teeth.

  1. Oceanic Double-Diffusive Layer Thicknesses in the Presence of Turbulence

    Science.gov (United States)

    Shibley, Nicole; Timmermans, Mary-Louise

    2016-11-01

    Double-diffusive stratification in the ocean is characterized by staircase structures consisting of mixed layers separated by high-gradient interfaces in temperature and salinity. Several past studies have examined mechanisms that govern the observed thicknesses of staircase mixed layers. In one formalism, the mixed-layer thickness is set by layer formation that arises when a heat source is applied at the base of water that is stably-stratified in salinity; in another, the equilibrium thickness of mixed layers has been explained as the product of "merging," where thin layers continue to grow until they reach a thickness determined by a criterion relating the ratio of heat flux to salt flux and the density ratio. We extend the above two theories to consider the influence of turbulence on mixed-layer thicknesses. The study has implications for the Arctic Ocean where double-diffusive staircases are widely present, and mixed-layer thicknesses are well-resolved by ocean measurements. Our theoretical framework provides a means to determine turbulent diffusivities (in regions where microstructure measurements are not available) by considering only observations of density ratio, stratification, and layer thicknesses.

  2. Expanded graphite—Phenolic resin composites based double layer microwave absorber for X-band applications

    Science.gov (United States)

    Gogoi, Jyoti Prasad; Bhattacharyya, Nidhi Saxena

    2014-11-01

    In this investigation, double layer microwave absorbers are designed and developed with paired combination of 5 wt. %, 7 wt. %, 8 wt. %, and 10 wt. % expanded graphite-novolac phenolic resin (EG-NPR) composites, in the frequency range of 8.2-12.4 GHz. The thickness and compositional combination of the two layers constituting the absorber are optimized to achieve minimum value of reflection loss (dB) and a broad microwave absorption bandwidth. Double layer combinations showing -25 dB absorption bandwidth >2 GHz and -30 dB absorption bandwidth >1 GHz are chosen for fabrication. The total thickness of the fabricated double layer microwave absorber is varied from 3 mm to 3.4 mm. Absorption bandwidths at -10 dB, -20 dB, -25 dB and -30 dB are determined for the fabricated structure. The maximum -25 dB and -30 dB absorption bandwidth of 2.47 GHz and 1.77 GHz, respectively, are observed for the double layer structure with (5 wt. %-8 wt. %) EG-NPR composites with total thickness of 3.2 mm, while -10 dB bandwidth covers the entire X-band range.

  3. Preparation and enhanced properties of polyaniline/grafted intercalated ZnAl-LDH nanocomposites

    Science.gov (United States)

    Hu, Jinlong; Gan, Mengyu; Ma, Li; Zhang, Jun; Xie, Shuang; Xu, Fenfang; Shen, JiYue Zheng Xiaoyu; Yin, Hui

    2015-02-01

    The polymeric nanocomposites (PANI/AD-LDH) were prepared by in situ polymerization based on polyaniline (PANI) and decavanadate-intercalated and γ-aminopropyltriethoxysilane (APTS)-grafted ZnAl-layered double hydroxide (AD-LDH). FTIR and XRD studies confirm the grafting of APTS with decavanadate-intercalated LDH (D-LDH). The extent of grafting (wt%) has also been estimated on the basis of the residue left in nitrogen atmosphere at 800 °C in TGA. SEM and XPS studies show the partial exfoliation of grafted LDH in the PANI matrix and the interfacial interaction between PANI and grafted LDH, respectively. The grafted intercalated layered double hydroxide in reinforcing the properties of the PANI nanocomposites has also been investigated by open circuit potential (OCP), tafel polarization curves (TAF), electrochemical impendence spectroscopy (EIS), salt spray test and TGA-DTA. The experimental results indicate that the PANI/AD-LDH has a higher thermal stability and anticorrosion properties relative to the PANI.

  4. Functionalized layered double hydroxide-based epoxy nanocomposites with improved flame retardancy and mechanical properties

    OpenAIRE

    Ehsan Naderi Kalali; Xin Wanga; De-Yi Wang

    2015-01-01

    Functionalized layered double hydroxides (LDHs) based on a multi-modifier system composed of hydroxypropyl-sulfobutyl-beta-cyclodextrin sodium (sCD), dodecylbenzenesulfonate (DBS) and taurine (T) have been designed and fabricated in this paper, aiming at developing high performance fire retardant epoxy nanocomposites. In this multi-modifier system, sCD was utilized to improve the char yield, DBS was used to enlarge the inter-layer distance of LDH and T was used to enhance the interaction betw...

  5. Bias-dependent molecular-level structure of electrical double layer in ionic liquid on graphite.

    Science.gov (United States)

    Black, Jennifer M; Walters, Deron; Labuda, Aleksander; Feng, Guang; Hillesheim, Patrick C; Dai, Sheng; Cummings, Peter T; Kalinin, Sergei V; Proksch, Roger; Balke, Nina

    2013-01-01

    Here we report the bias-evolution of the electrical double layer structure of an ionic liquid on highly ordered pyrolytic graphite measured by atomic force microscopy. We observe reconfiguration under applied bias and the orientational transitions in the Stern layer. The synergy between molecular dynamics simulation and experiment provides a comprehensive picture of structural phenomena and long and short-range interactions, which improves our understanding of the mechanism of charge storage on a molecular level.

  6. Understanding surface interactions in aqueous miscible organic solvent treated layered double hydroxides.

    OpenAIRE

    Erastova, Valentina; Degiacomi, Matteo T.; O'Hare, Dermot; Greenwell, H. Chris

    2016-01-01

    Layered materials are of interest for use in a wealth of technological applications, many of which require a high surface area for optimal properties and performance. Recently, an industrially scalable method to create high surface area layered double hydroxide (LDH) materials, which may be readily dispersed in non-polar solvents, has been developed. This method involves treatment of LDHs with aqueous miscible organic (AMO) solvents. Here, molecular modeling is exploited to elucidate the AMO ...

  7. Morphologies, Preparations and Applications of Layered Double Hydroxide Micro-/Nanostructures

    Directory of Open Access Journals (Sweden)

    Mingdong Dong

    2010-12-01

    Full Text Available Layered double hydroxides (LDHs, also well-known as hydrotalcite-like layered clays, have been widely investigated in the fields of catalysts and catalyst support, anion exchanger, electrical and optical functional materials, flame retardants and nanoadditives. This feature article focuses on the progress in micro-/nanostructured LDHs in terms of morphology, and also on the preparations, applications, and perspectives of the LDHs with different morphologies.

  8. Asymptotic theory of double layer and shielding of electric field at the edge of illuminated plasma

    Energy Technology Data Exchange (ETDEWEB)

    Benilov, M. S. [Departamento de Física, CCCEE, Universidade da Madeira, Largo do Município, 9000 Funchal (Portugal); Thomas, D. M. [Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2BW (United Kingdom)

    2014-04-15

    The method of matched asymptotic expansions is applied to the problem of a collisionless plasma generated by UV illumination localized in a central part of the plasma in the limiting case of small Debye length λ{sub D}. A second-approximation asymptotic solution is found for the double layer positioned at the boundary of the illuminated region and for the un-illuminated plasma for the plane geometry. Numerical calculations for different values of λ{sub D} are reported and found to confirm the asymptotic results. The net integral space charge of the double layer is asymptotically small, although in the plane geometry it is just sufficient to shield the ambipolar electric field existing in the illuminated region and thus to prevent it from penetrating into the un-illuminated region. The double layer has the same mathematical nature as the intermediate transition layer separating an active plasma and a collisionless sheath, and the underlying physics is also the same. In essence, the two layers represent the same physical object: a transonic layer.

  9. Interaction between electrical double layers of soil colloids and Fe/Al oxides in suspensions.

    Science.gov (United States)

    Hou, Tao; Xu, Renkou; Tiwari, Diwakar; Zhao, Anzhen

    2007-06-15

    Phyllosilicates with net negative surface charge and Fe/Al oxides with net positive surface charge coexist in variable-charge soils, and the interaction between these oppositely charged particles affects the stability of mixed colloids, aggregation, and even the surface chemical properties of variable-charge soils. The interaction of the diffuse layers of electrical double layers between the negatively charged soil colloidal particles and the positively charged particles of goethite or gamma-Al(2)O(3) was investigated in this article through the comparison of zeta potentials between single-soil colloidal systems and binary systems containing soil colloids and Fe/Al oxides. The results showed that the presence of goethite and gamma-Al(2)O(3) increased the zeta potential of the binary system containing soil colloids and Fe/Al oxides, which clearly suggests the overlapping of the diffuse layers in soil colloids and Fe/Al oxides. The overlapping of the diffuse layers leads to a decrease in the effective negative charge density on soil colloid and thus causes a shift of pH-zeta potential curves toward the more positive-value side. The interaction of the electrical double layers is also related to the charge characteristics on the Fe/Al oxides: the higher the positive charge density on Fe/Al oxides, the stronger the interaction of the electrical double layers between the soil colloid particles and the Fe/Al oxides.

  10. Hierarchical Supervisor and Agent Routing Algorithm in LEO/MEO Double-layered Optical Satellite Network

    Science.gov (United States)

    Li, Yongjun; Zhao, Shanghong

    2016-09-01

    A novel routing algorithm (Hierarchical Supervisor and Agent Routing Algorithm, HSARA) for LEO/MEO (low earth orbit/medium earth orbit) double-layered optical satellite network is brought forward. The so-called supervisor (MEO satellite) is designed for failure recovery and network management. LEO satellites are grouped according to the virtual managed field of MEO which is different from coverage area of MEO satellite in RF satellite network. In each LEO group, one LEO satellite which has maximal persistent link with its supervisor is called the agent. A LEO group is updated when this optical inter-orbit links between agent LEO satellite and the corresponding MEO satellite supervisor cuts off. In this way, computations of topology changes and LEO group updating can be decreased. Expense of routing is integration of delay and wavelength utilization. HSARA algorithm simulations are implemented and the results are as follows: average network delay of HSARA can reduce 21 ms and 31.2 ms compared with traditional multilayered satellite routing and single-layer LEO satellite respectively; LEO/MEO double-layered optical satellite network can cover polar region which cannot be covered by single-layered LEO satellite and throughput is 1% more than that of single-layered LEO satellite averagely. Therefore, exact global coverage can be achieved with this double-layered optical satellite network.

  11. Probing the electric field in organic double layer-system by optical second harmonic generation

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Eunju; Shibata, Yoshinori; Manaka, Takaaki [Department of Physical Electronics, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro-ku, Tokyo 152-8552 (Japan); Iwamoto, Mitsumasa, E-mail: iwamoto@ome.pe.titech.ac.j [Department of Physical Electronics, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro-ku, Tokyo 152-8552 (Japan)

    2009-11-30

    Optical electric field induced second harmonic generation (EFISHG) measurements were employed to probe the electric field in the active layer of organic field effect transistors (OFETs) and organic light emitting diodes (OLEDs). The OFETs used were double-layered with an active layer of pentacene/poly (3-hexyl thiophene) P3HT on SiO{sub 2} gate insulator with Au source and drain electrodes. It was shown that SHG from the P3HT bottom layer could be selectively probed at a wavelength of 450 nm. Similarly, by using OLEDs comprised of a double layer of Tris(8-hydroxyquinolinato) aluminium (Alq{sub 3}) and N'-di(1-naphthyl)-N,N'-diphenylbenzidine ({alpha}-NPD) with a device structure of indium-zinc oxide (IZO)/{alpha}-NPD/Alq{sub 3}/Al, it was shown that EFISHG from the Alq{sub 3} layer could be selectively probed at a wavelength of 1000 nm by reflective laser beam irradiation from IZO-side. The results show that the spectroscopic nature of materials allows us to selectively probe the electric field distribution in each layer of multi-layer in organic devices.

  12. Preparation and properties of hydrogen-intercalated indium and gallium monoselenides

    Energy Technology Data Exchange (ETDEWEB)

    Koz' mik, I.D.; Kovalyuk, Z.D.; Grigorchak, I.I.; Bakhmatyuk, B.P.

    1987-10-01

    Indium and gallium monoselenides can be intercalated by hydrogen ions. Thermodynamic parameters have been calculated for the intercalation and the proton diffusion coefficient in the van der Waals' spaces has been determined. The effects of hydrogen intercalation on the resistance perpendicular to the layers in InSe and GaSe have been determined.

  13. Hydrotalcite Intercalated siRNA: Computational Characterization of the Interlayer Environment

    Directory of Open Access Journals (Sweden)

    Sean C. Smith

    2012-06-01

    Full Text Available Using molecular dynamics (MD simulations, we explore the structural and dynamical properties of siRNA within the intercalated environment of a Mg:Al 2:1 Layered Double Hydroxide (LDH nanoparticle. An ab initio force field (Condensed-phase Optimized Molecular Potentials for Atomistic Simulation Studies: COMPASS is used for the MD simulations of the hybrid organic-inorganic systems. The structure, arrangement, mobility, close contacts and hydrogen bonds associated with the intercalated RNA are examined and contrasted with those of the isolated RNA. Computed powder X-ray diffraction patterns are also compared with related LDH-DNA experiments. As a method of probing whether the intercalated environment approximates the crystalline or rather the aqueous state, we explore the stability of the principle parameters (e.g., the major groove width that differentiate both A- and A'- crystalline forms of siRNA and contrast this with recent findings for the same siRNA simulated in water. We find the crystalline forms remain structurally distinct when intercalated, whereas this is not the case in water. Implications for the stability of hybrid LDH-RNA systems are discussed.

  14. Electric-Field-Induced Superconductivity Detected by Magnetization Measurements of an Electric-Double-Layer Capacitor

    NARCIS (Netherlands)

    Kasahara, Yuichi; Nishijima, Takahiro; Sato, Tatsuya; Takeuchi, Yuki; Ye, Jianting; Yuan, Hongtao; Shimotani, Hidekazu; Iwasa, Yoshihiro

    We report evidence for superconductivity induced by the application of strong electric fields onto the surface of a band insulator, ZrNCl, provided by the observation of a shielding diamagnetic signal. We introduced an electric-double-layer capacitor configuration and in situ magnetization

  15. Electric double layer transistors with ferroelectric BaTiO3 channels

    NARCIS (Netherlands)

    Ito, M.; Matsubara, Y.; Kozuka, Y.; Takahashi, K. S.; Kagawa, F.; Ye, J. T.; Iwasa, Y.; Ueno, K.; Tokura, Y.; Kawasaki, M.

    2014-01-01

    We report the surface conduction of a BaTiO3 thin film using electric double layer transistor (EDLT) structure. A transistor operation was observed at 220 K with an on/off ratio exceeding 10(5), demonstrating that ionic liquid gating is effective to induce carriers at the surface of ferroelectric ma

  16. Double layered self-expanding metal stents for malignant esophageal obstruction, especially across the gastroesophageal junction

    Institute of Scientific and Technical Information of China (English)

    Min Dae Kim; Su Bum Park; Dae Hwan Kang; Jae Hyung Lee; Cheol Woong Choi; Hyung Wook Kim; Chung Uk Chung

    2012-01-01

    AIM:TO evaluate the clinical outcomes of double-layered self-expanding metal stents (SEMS) for treatment of malignant esophageal obstruction according to whether SEMS crosses the gastroesophageal junction (GEJ).METHODS:Forty eight patients who underwent the SEMS insertion for malignant esophageal obstruction were enrolled.Patients were classified as GEJ group (SEMS across GEHm 18 patients) and non-GEJ group (SEMS above GEJ,30 patients) according to SEMS position.Double layered (outer uncovered and inner covered stent) esophageal stents were placed.RESULTS:The SEMS insertion and the clinical improvement were achieved in all patients in both groups.Stent malfunction occurred in seven patients in the GEJ group and nine patients in the non-GEJ group.Tumor overgrowth occurred in five and eight patients,respectively,food impaction occurred in one patient in each group,and stent migration occurred in one and no patient,respectively.There were no significant differences between the two groups.Reflux esophagitis occurred more frequently in the GEJ group (eight vs five patients,P =0.036) and was controlled by proton pump inhibitor.Aspiration pneumonia occurred in zero and five patients,respectively,and tracheoesophageal fistula occurred in zero and two patients,respectively.CONCLUSION:Double-layered SEMS are a feasible and effective treatment when placed across the GEJ for malignant esophageal obstruction.Double-layered SEMS provide acceptable complications,especially migration,although reflux esophagitis is more common in the GEJ group.

  17. Internal energy and specific heat in a ferromagnetic-antiferromagnetic double layers

    Institute of Scientific and Technical Information of China (English)

    Jiang Wei; Guo An-Bang

    2007-01-01

    The internal energy and specific heat of a Heisenberg ferro- antiferromagnetic double-layer system are studied by using spin-wave theory and the retarded Green function method at low temperatures. Numerical results show that the antiferromagnetic intralayer coupling J2 has an important influence on internal energy and specific heat for a four-sublattice system with antiferromagnetic (or ferrimagnetic) interlayer couplings.

  18. Small amplitude variable charge dust Bernstein-Greene-Kruskal double layers

    Energy Technology Data Exchange (ETDEWEB)

    Amour, Rabia [Plasma Physics Group, Theoretical Physics Laboratory, Faculty of Sciences - Physics, U.S.T.H.B, Bab-Ezzouar, B.P. 32, El Alia, Algiers 16111 (Algeria); Tribeche, Mouloud [Plasma Physics Group, Theoretical Physics Laboratory, Faculty of Sciences - Physics, U.S.T.H.B, Bab-Ezzouar, B.P. 32, El Alia, Algiers 16111 (Algeria)], E-mail: mouloud-tribeche@lycos.com

    2009-05-11

    A first theoretical attempt is made to investigate small amplitude, variable charge dust Bernstein-Greene-Kruskal (BGK) double layers (DLs). The nature of the dust BGK-DLs (compressive or rarefactive), their strength and thickness depend sensitively on the net negative charge residing on the grain surface, the dust grain dynamics and, more interestingly, on the ion-to-electron temperatures ratio.

  19. Laser cutting silicon-glass double layer wafer with laser induced thermal-crack propagation

    Science.gov (United States)

    Cai, Yecheng; Yang, Lijun; Zhang, Hongzhi; Wang, Yang

    2016-07-01

    This study was aimed at introducing the laser induced thermal-crack propagation (LITP) technology to solve the silicon-glass double layer wafer dicing problems in the packaging procedure of silicon-glass device packaged by WLCSP technology, investigating the feasibility of this idea, and studying the crack propagation process of LITP cutting double layer wafer. In this paper, the physical process of the 1064 nm laser beam interact with the double layer wafer during the cutting process was studied theoretically. A mathematical model consists the volumetric heating source and the surface heating source has been established. The temperature and stress distribution was simulated by using finite element method (FEM) analysis software ABAQUS. The extended finite element method (XFEM) was added to the simulation as the supplementary features to simulate the crack propagation process and the crack propagation profile. The silicon-glass double layer wafer cutting verification experiment under typical parameters was conducted by using the 1064 nm semiconductor laser. The crack propagation profile on the fracture surface was examined by optical microscope and explained from the stress distribution and XFEM status. It was concluded that the quality of the finished fracture surface has been greatly improved, and the experiment results were well supported by the numerical simulation results.

  20. Hydrothermal Synthesis and Characterization of 3R Polytypes of Mg-Al Layered Double Hydroxides

    NARCIS (Netherlands)

    Budhysutanto, W.N.

    2010-01-01

    Layered Double Hydroxides (LDH) is a unique group of clays that have an anionic exchange capability. This research explored the hydrothermal method as an alternative method to synthesize Mg-Al LDH. It is a simple and more environmentally friendly compared to the conventional method of co-precipitati

  1. The recording characteristics of particulate double layers with hard-magnetic and soft-magnetic underlayers

    NARCIS (Netherlands)

    Lalbahadoersing, S.; Groenland, J.P.J.; Luitjens, S.B.; Lodder, J.C.

    2002-01-01

    Particulate double-layer tape samples with magnetic underlayers have been investigated by performing magnetic recording measurements and by computer simulation.The presence of soft-magnetic underlayers resulted in decreased signal output and better overwrite behavior. Hard-magnetic underlayers showe

  2. Theoretical analysis and experimental study on the influence of electric double layer on thin film lubrication

    Institute of Scientific and Technical Information of China (English)

    WANG Xin-jie; BAI Shao-xian; HUANG Ping

    2006-01-01

    A new mathematical model for thin film lubrication is established by taking into account the effect of an electric double layer.In the present paper,experiments are carried out on a self-made tester.With a composite block and a rotating disk,influence of electric double layer on thin film lubrication is studied.Two different methods are used to reconstruct the field of electric double layer so as to change its effect.One is to change the ionic concentration of lubricants by adding additives,and the other is to apply an external electric field on friction pairs.According theoretical analysis,both the methods will apparently change the electro-viscosity of the lubricant film so as to change the lubrication performances.After theoretical calculation of electro-viscosity is amended according to the experimental results,the equations of electro-viscosity are presented.The results show that the equivalent viscosity of fluid induced by the effect of electric double layer apparently increases with the decrease of thickness of the film while the lubrication film is thin enough.The effect of electro-viscosity is weakened as the thickness of the film increases.Moreover,the effect of electro-viscosity increases with the increase of external electric field at first.When the voltage reaches a certain value,the electro-viscosity begins to decrease.

  3. Studies on Synthesis and Properties of Mg-Al-nitrate Layered Double Hydroxides

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    A positive Mg-Al-nitrate layered double hydroxides (LDHs) has been synthesized using a non-steady coprccipitation method. The shape, size, chemical composition, electrical property and anion exchange property of the positive nanoparticle were studied by SEM, XRD, FTIR,chemical analysis, spectroanalysis and measuring of electrophoretic mobilities. Preliminary results show the positive nanopartiele is a promising precursor ofpolymer/LDHs nanocomposite.

  4. Formation of nematic liquid crystals of sterically stabilized layered double hydroxide platelets

    NARCIS (Netherlands)

    Mourad, M.C.D.; Devid, E.J.; van Schooneveld, M.M.; Vonk, Ch.; Lekkerkerker, H.N.W.

    2008-01-01

    Colloidal platelets of hydrotalcite, a layered double hydroxide, have been prepared by coprecipitation at pH 11−12 of magnesium nitrate and aluminum nitrate at two different magnesium to aluminum ratios. Changing the temperature and ionic strength during hydrothermal treatment, the platelets were ta

  5. Using a double-layered palmaris longus tendon for suspension of facial paralysis

    DEFF Research Database (Denmark)

    Toyserkani, Navid Mohamadpour; Bakholdt, Vivi; Sørensen, Jens Ahm

    2015-01-01

    INTRODUCTION: Facial palsy is a debilitating condition entailing both cosmetic and functional limitations. Static suspension procedures can be performed when more advanced dynamic techniques are not indicated. Since 2006, we have used a double-layered palmaris longus tendon graft through an ovular...

  6. Steric-effect-induced enhancement of electrical-double-layer overlapping phenomena

    NARCIS (Netherlands)

    Das, Siddhartha; Chakraborty, Suman

    2011-01-01

    In this paper, we demonstrate that nontrivial interactions between steric effect and electrical-double-layer (EDL) overlap phenomena may augment the effective extent of EDL overlap in narrow fluidic confinements to a significant extent by virtue of rendering the channel centerline potential tending

  7. Electric-Field-Induced Superconductivity Detected by Magnetization Measurements of an Electric-Double-Layer Capacitor

    NARCIS (Netherlands)

    Kasahara, Yuichi; Nishijima, Takahiro; Sato, Tatsuya; Takeuchi, Yuki; Ye, Jianting; Yuan, Hongtao; Shimotani, Hidekazu; Iwasa, Yoshihiro

    2011-01-01

    We report evidence for superconductivity induced by the application of strong electric fields onto the surface of a band insulator, ZrNCl, provided by the observation of a shielding diamagnetic signal. We introduced an electric-double-layer capacitor configuration and in situ magnetization measureme

  8. Electric-Field-Induced Superconductivity Detected by Magnetization Measurements of an Electric-Double-Layer Capacitor

    NARCIS (Netherlands)

    Kasahara, Yuichi; Nishijima, Takahiro; Sato, Tatsuya; Takeuchi, Yuki; Ye, Jianting; Yuan, Hongtao; Shimotani, Hidekazu; Iwasa, Yoshihiro

    2011-01-01

    We report evidence for superconductivity induced by the application of strong electric fields onto the surface of a band insulator, ZrNCl, provided by the observation of a shielding diamagnetic signal. We introduced an electric-double-layer capacitor configuration and in situ magnetization measureme

  9. Optimization of layered double hydroxide stability and adsorption capacity for anionic surfactants

    NARCIS (Netherlands)

    Schouten, Natasja; Ham, Louis G.J. van der; Euverink, Gert-Jan W.; Haan, André B. de

    2007-01-01

    Low cost adsorption technology offers high potential to clean up laundry rinsing water. From an earlier selection of adsorbents, layered double hydroxide (LDH) proved to be an interesting material for the removal of anionic surfactant, linear alkyl benzene sulfonate (LAS) which is the main contamina

  10. Optimization of layered double hydroxide stability and adsorption capacity for anionic surfactants

    NARCIS (Netherlands)

    Schouten, Natasja; Ham, van der Louis G.J.; Euverink, Gert-Jan W.; Haan, de André B.

    2007-01-01

    Low cost adsorption technology offers high potential to clean up laundry rinsing water. From an earlier selection of adsorbents (Schouten et al. 2007), layered double hydroxide (LDH) proved to be an interesting material for the removal of anionic surfactant, linear alkyl benzene sulfonate (LAS) whic

  11. Bio-Inspired Aquaporinz Containing Double-Skinned Forward Osmosis Membrane Synthesized through Layer-by-Layer Assembly

    Directory of Open Access Journals (Sweden)

    Shuzheng Wang

    2015-08-01

    Full Text Available We demonstrated a novel AquaporinZ (AqpZ-incorporated double-skinned forward osmosis (FO membrane by layer-by-layer (LbL assembly strategy. Positively charged poly(ethyleneimine (PEI and negatively charged poly(sodium 4-styrenesulfonate (PSS were alternately deposited on both the top and bottom surfaces of a hydrolyzed polyacrylonitrile (H-PAN substrate. Subsequently, an AqpZ-embedded 1,2-dioleloyl-sn-glycero-3-phosphocholine (DOPC/1,2-dioleoyl-3-trimethylammonium- propane (chloride salt (DOTAP supported lipid bilayer (SLB was formed on PSS-terminated (T-PSS membrane via vesicle rupture method. The morphology and structure of the biomimetic membranes were characterized by in situ atomic force microscopy (AFM, scanning electron microscope (SEM, Fourier transform infrared spectrometer using the attenuated total reflection technique (ATR-FTIR, and contact angle. Moreover, the FO performance of the resultant membrane was measured by using 2 M MgCl2 solution as draw solution and deionized (DI water as feed solution, respectively. The membrane with a protein-to-lipid weight ratio (P/L of 1/50 exhibits 13.2 L/m2h water flux and 3.2 g/m2h reversed flux by using FO mode, as well as 15.6 L/m2h water flux and 3.4 L/m2h reversed flux for PRO mode (the draw solution is placed against the active layer. It was also shown that the SLB layer of the double-skinned FO membrane can increase the surface hydrophilicity and reduce the surface roughness, which leads to an improved anti-fouling performance against humic acid foulant. The current work introduced a new method of fabricating high performance biomimetic FO membrane by combining AqpZ and a double-skinned structure based on LbL assembly.

  12. Dust acoustic double layers in a magnetized dusty self-gravitating plasma with superthermal particles

    Science.gov (United States)

    Sabetkar, Akbar; Dorranian, Davoud

    2016-08-01

    Our prime objective of this paper is to examine the parametric regimes for the existence and polarity of dust acoustic double layers (DADLs) and its solitary structures arising from a magnetized self-gravitating opposite polarity dust-plasma (OPDP) model. The constituents of the OPDP model are two species of positively and negatively charged dust grains, Maxwellian electrons and kappa distributed ions. Contributions of gravitational force only on dust grains are taken into account. For weakly nonlinear analysis, the multiple time scale technique has been used to construct the extended Korteweg-de Vries (E-KdV) and modified Korteweg-de Vries (M-KdV) equations. They pinpoint the evolution of DADLs and solitary structures associated with dust acoustic (DA) mode, respectively. The relevant configurational parameters in our study include the superthermality of ions (κ), obliqueness of propagation (θ), ion concentration (δi), static magnetic field B0 (via ω c p , ω c n ), and self-gravitational field (via γ), as well as the density (μ0), charge (α), and mass (β) ratio of positive to negative dust species. The proposed OPDP model permits positive and negative double layer polarities, while higher order nonlinear equation dictates us only positive polarity solitary structures. The main modification due to an increase in self-gravitational field (via γ) is an enhancement in the spatial width of double layers, yet leaving their amplitude, phase speed, and polarity practically unaffected. With enhanced superthermality and other intrinsic parameters in OPDP model, there is an opposite trend in both amplitude and width of double layers, while the amplitude and the width of solitary waves (via M-KdV equation) undergo the identical behaviors. In particular, the amplitude of solitary waves manifests monotonic behavior for permissible range of obliqueness θ, whereas this scenario is acceptable to only width of double layers. The results are discussed in the context of

  13. Ion acoustic solitons/double layers in two-ion plasma revisited

    Energy Technology Data Exchange (ETDEWEB)

    Lakhina, G. S., E-mail: gslakhina@gmail.com; Singh, S. V., E-mail: satyavir@iigs.iigm.res.in; Kakad, A. P., E-mail: amar@iigs.iigm.res.in [Indian Institute of Geomagnetism, New Panvel (W), Navi Mumbai 410218 (India)

    2014-06-15

    Ion acoustic solitons and double layers are studied in a collisionless plasma consisting of cold heavier ion species, a warm lighter ion species, and hot electrons having Boltzmann distributions by Sagdeev pseudo-potential technique. In contrast to the previous results, no double layers and super-solitons are found when both the heavy and lighter ion species are treated as cold. Only the positive potential solitons are found in this case. When the thermal effects of the lighter ion species are included, in addition to the usual ion-acoustic solitons occurring at M > 1 (where the Mach number, M, is defined as the ratio of the speed of the solitary wave and the ion-acoustic speed considering temperature of hot electrons and mass of the heavier ion species), slow ion-acoustic solitons/double layers are found to occur at low Mach number (M < 1). The slow ion-acoustic mode is actually a new ion-ion hybrid acoustic mode which disappears when the normalized number density of lighter ion species tends to 1 (i.e., no heavier species). An interesting property of the new slow ion-acoustic mode is that at low number density of the lighter ion species, only negative potential solitons/double layers are found whereas for increasing densities there is a transition first to positive solitons/double layers, and then only positive solitons. The model can be easily applicable to the dusty plasmas having positively charged dust grains by replacing the heavier ion species by the dust mass and doing a simple normalization to take account of the dust charge.

  14. Theoretical Study of Monolayer and Double-Layer Waveguide Love Wave Sensors for Achieving High Sensitivity.

    Science.gov (United States)

    Li, Shuangming; Wan, Ying; Fan, Chunhai; Su, Yan

    2017-03-22

    Love wave sensors have been widely used for sensing applications. In this work, we introduce the theoretical analysis of the monolayer and double-layer waveguide Love wave sensors. The velocity, particle displacement and energy distribution of Love waves were analyzed. Using the variations of the energy repartition, the sensitivity coefficients of Love wave sensors were calculated. To achieve a higher sensitivity coefficient, a thin gold layer was added as the second waveguide on top of the silicon dioxide (SiO₂) waveguide-based, 36 degree-rotated, Y-cut, X-propagating lithium tantalate (36° YX LiTaO₃) Love wave sensor. The Love wave velocity was significantly reduced by the added gold layer, and the flow of wave energy into the waveguide layer from the substrate was enhanced. By using the double-layer structure, almost a 72-fold enhancement in the sensitivity coefficient was achieved compared to the monolayer structure. Additionally, the thickness of the SiO₂ layer was also reduced with the application of the gold layer, resulting in easier device fabrication. This study allows for the possibility of designing and realizing robust Love wave sensors with high sensitivity and a low limit of detection.

  15. Improving thermal stability and light fastness of Acid Red 114 by incorporating its anions in a ZnAl-layered double hydroxides matrix

    Institute of Scientific and Technical Information of China (English)

    Haifeng Zhu; Liren Wang; Pinggui Tang; Yongjun Feng; Dianqing Li

    2012-01-01

    Incorporation of anions of Acid Red 114 dye (1,3-naphthalenedisulfonic acid,8-[2-[3,3'-dimethyl-4'-[2-[4-[[(4-methylphenyl)sulfonyl]oxy] phenyl]diazenyl] [1,1'-biphenyl]-4-yl]diazenyl]-7-hydroxy-,disodium salt) (denoted as NPDA) into ZnAl-layered double hydroxides (LDHs) has been carried out by an anionexchange method in an effort to improve their thermal stability and light fastness.After intercalation of NPDA anions,the interlayer distance of the LDHs increases from 0.87 to 2.18nm,confirming their incorporation into the interlayer galleries of the LDHs host.Infrared spectroscopy and thermogravimetric analysis revealed the presence of host-guest interactions between LDHs layers and NPDA anions.The thermal stability of NPDA and ZnAl-NPDA-LDHs was compared by thermogravimetric-differential thermal analysis,UV-visible spectroscopy and infrared spectroscopy.It was found that the thermal stability of NPDA anions was markedly improved by incorporation into the ZnAl-LDHs matrix,while the light fastness was also enhanced.

  16. Adsorption Properties for Direct Sky Blue 5B by n-alkylamines-intercalated Layered Tetratitanate%有机胺插层四钛酸对直接湖蓝5B的吸附性能研究

    Institute of Scientific and Technical Information of China (English)

    张国辉; 孔春梅; 唐永明; 杨文忠

    2012-01-01

    在微波辅助下对四钛酸进行了有机胺插层,获得了正辛胺、正十二胺、正十六胺插层四钛酸材料,研究了3种层状物质作为吸附剂,pH、震荡时间、吸附剂用量等因素对直接湖蓝5B偶氮染料吸附的影响,确定了3种材料吸附的最佳条件.研究表明:微波有机胺插层四钛酸材料具有优良的吸附性能,pH=1.0时,正辛胺插层四钛酸用量为0.8 g/L、振荡时间40min,正十二胺插层材料和正十六插层材料用量为0.4 g/L、振荡时间分别30 min和50 min时,吸附脱色效果最好.随染料浓度增大,温度升高,插层四钛酸材料会发生板层分离,表现为常规的物理吸附过程.在50℃时,正辛胺、正十二胺、正十六插层四钛酸对直接湖蓝5B染料的吸附量分别达到636 mg/g、3 349 mg/g、2 856 mg/g.%Organic titanate acid was obtained by intercalation of n-CnH2n+1NH2(n=8,12,16)under microwave irradiation. The adsorption properties under various conditions such as pH value, adsorbent time and adsorbent dosage were investigated and the optimal experimental conditions were obtained. Results indicated that the grafted aminated tetratitanate acid had a higher adsorption capacity and adsorption speed for removing dyes from dye wastewater. The optimal adsorption conditions were presented for n-octylamines -intercalated layered tetratitanate at pH 1, adsorption time 40min and dosage 0.8 g/L; for n-dodecylamines -intercalated n -hexadecylamines -intercalated layered tetratitanate at pH 1.0, adsorption time 50 min and dosage 0.4 g/L. With the increase in dye concentration and temperature, the layers of n-alkylamines-intercalated tetratitanate will be separated with performance for regular physical adsorption process. The maximum adsorption capacities of direct sky blue 5B over n-CnH2n+1NH2(n=8,12,16)pillared tetratitanate were 636 mg/g, 3 349 mg/g and 2 856 mg/g at 50 ℃ respectively.

  17. Effects of fabricated error on transmission performance of double layer frequency selective surface configuration

    Institute of Scientific and Technical Information of China (English)

    HE Bin; SUN Lian-chun

    2005-01-01

    Based on the experimental results, in which the fabricated error of the double layer frequency selective surface (FSS) leads to the transmission loss and the resonant frequency leaves away the design resonant frequency, the inter-layer separation distance (ISD) and the unit cell aligning error (UAE) were used as main variables to study the transmission performance attenuation of the double layer FSS configuration. The numerical analysis model for ISD and UAE was established and also was used to simulate the ring unit cell FSS transmission performance by the finite element and periodic moment methods. The double layer ring aperture FSS configuration designed was used as the numerical model. As a result of the numerical analysis, it is shown that both ISD and UAE produce insertion transmission loss (ITL) and insertion phase distortion (IPD) directly. Furthermore, ISD results in more loss of the amplitude of the transmitted signal for the FSS than UAE. It is significant for the designer of the multiplayer FSS to assign the fabricated error of the FSS dielectric layers. The UAE introduces the insertion phase variation badly.

  18. Impact single versus double layer uterine closure in caesarean section to uterine rupture

    Directory of Open Access Journals (Sweden)

    Budi Iman Santoso

    2016-07-01

    Full Text Available Caesarean section (CS is one of the most frequent delivery methods in the world whereas the rates of CS were varied according to developing (from 3.5 to 29.2% and developed countries (21.1%. The study aims to known the impact of single versus double layer uterine closure to uterine rupture in the history of cesarean section (CS. In this case report, the clinical question is single versus double-layer uterine closure on the previous CS, gives better outcome to reduce the risk of uterine rupture. To answer this question, we search the evidence from Pub Med and Cochrane database with the keywords: and ldquo;cesarean section" and "uterine rupture" and and ldquo;uterine closure and rdquo;. The inclusion criteria are written in English and focused comparing single and double layer uterine closure to uterine rupture in the previous CS. From the searching literature, we found 3 systematic reviews and 23 articles which were relevant to the topic. After screening the abstract and language, we got 2 systematic reviews and 4 articles. At the end, only 4 articles consisting of 1 systematic review and 3 articles were included to be appraised. Based on evidences, single layer uterine closure did not increase the risk of uterine rupture. Apart from that, shorter operative times and lower estimated blood loss became the superiority of single-layer uterine closure. [Int J Reprod Contracept Obstet Gynecol 2016; 5(7.000: 2074-2078

  19. Bromine intercalated graphite for lightweight composite conductors

    KAUST Repository

    Amassian, Aram

    2017-07-20

    A method of fabricating a bromine-graphite/metal composite includes intercalating bromine within layers of graphite via liquid-phase bromination to create brominated-graphite and consolidating the brominated-graphite with a metal nanopowder via a mechanical pressing operation to generate a bromine-graphite/metal composite material.

  20. First steps towards the realization of a double layer perceptron based on organic memristive devices

    Directory of Open Access Journals (Sweden)

    A. V. Emelyanov

    2016-11-01

    Full Text Available Memristors are widely considered as promising elements for the efficient implementation of synaptic weights in artificial neural networks (ANNs since they are resistors that keep memory of their previous conductive state. Whereas demonstrations of simple neural networks (e.g., a single-layer perceptron based on memristors already exist, the implementation of more complicated networks is more challenging and has yet to be reported. In this study, we demonstrate linearly nonseparable combinational logic classification (XOR logic task using a network implemented with CMOS-based neurons and organic memrisitive devices that constitutes the first step toward the realization of a double layer perceptron. We also show numerically the ability of such network to solve a principally analogue task which cannot be realized by digital devices. The obtained results prove the possibility to create a multilayer ANN based on memristive devices that paves the way for designing a more complex network such as the double layer perceptron.