bluuebunny/crossref_metadata_2025_split huggingface dataset:
Surface Plasmon Resonance Spectroscopic Study on Pore-Forming Behavior of Streptolysin O on Supported Phospholipid Bilayers
Authors: Wilkop Thomas , Xu Danke , Cheng Quan 
Published: June 2019

AbstractA novel supported bilayer membrane was formed on top of a hydrophobic spacer layer of hexyl thioctate (HT) and its application in the detection of pore forming toxins was demonstrated. The formation kinetics, effect of different flow rates on the fusion process of vesicles and perforation by incubation with streptolysin O (SLO) and pristine membranes were investigated. Individual layers of the multilayer structure were successfully characterized with surface plasmon resonance (SPR), and the resulting spectra were analyzed in order to determine the layer thickness and other membrane properties. The interaction of SLO with the pristine biomimetic membrane resulted in a pronounced change in the reflectivity spectrum. Elements of these spectral changes were analyzed to explain the process of toxin binding and pore formation taking place on the lipid membrane.
Composition and Surface Topography Effects on Apatite-Forming Ability of Ceramic-Polymer Composites
Authors: Rea Susan M. , Best Serena M. , Bonfield William 
Published: June 2019

AbstractHAPEXTM (40 vol% hydroxyapatite in a high-density polyethylene matrix) and AWPEX (40 vol% apatite-wollastonite glass ceramic in a high density polyethylene matrix) are composites designed to provide bioactivity and to match the mechanical properties of human cortical bone. HAPEXTM has had clinical success in middle ear and orbital implants, and there is great potential for further orthopaedic applications of these materials. However, more detailed in vitro investigations must be performed to better understand the biological interactions of the composites and so the bioactivity of each material was assessed in this study. Specifically, the effects of controlled surface topography and ceramic filler composition on apatite layer formation in acellular simulated body fluid (SBF) with ion concentration similar to those of human blood plasma were examined. Samples were prepared as 1 cm × 1 cm × 1 mm tiles with polished, roughened, or parallel-grooved surface finishes, and were incubated in 20 ml of SBF at 36.5 °C for 1, 3, 7, or 14 days. The formation of a biologically active apatite layer on the composite surface after immersion was demonstrated by thin-film x-ray diffraction (TF-XRD), environmental scanning electron microscopy (ESEM) imaging and energy dispersive x-ray (EDX) analysis. Variations in sample weight and solution pH over the period of incubation were also recorded. Significant differences were found between the two materials tested, with greater bioactivity in AWPEX than HAPEXTM overall. Results also indicate that within each material the surface topography is highly important, with rougher samples correlated to earlier apatite formation.
Quantum Dots Stabilized By Genetically Engineered Proteins
Authors: Ding S.-Y. , Rumbles G. , Jones M. , Tucker M.P. , Nedeljkovic J. , Wall J. , Himmel M.E. 
Published: June 2019

AbstractColloidal quantum dots (QDs) exhibit unique optical and electronic properties due to their physical size and the semi-conductor material from which they are made [1,2]. While the isolated properties of these nanoparticles offer a number of potential applications, such as bioimaging, their future use in novel electronic devices will require large arrays of known order. The assembling of these arrays is non-trivial and requires a monodisperse sample of quantum dots in order to facilitate the self-assembling process [3,4]. We propose first to validate the concept of using natural and/or recombined (genetic engineered) proteins to build stable, water soluble QD-protein conjugates [5]. Eventually, strategies to design these structures with highly controlled patterns will emerge.
Osteoblast-like Cell Response to Apatite-Wollastonite/Polyethylene Bone Replacement Composites
Authors: Rea Susan M. , Brooks Roger A. , Best Serena M. , Bonfield William 
Published: June 2019

AbstractApatite-wollastonite (A-W)/high-density polyethylene composite (AWPEX) materials have been designed to match the mechanical strength of human cortical bone and to provide favorable bioactivity, with potential use in many orthopaedic applications. To better understand AWPEX properties, the effects of surface finish and ceramic filler size and content on osteoblast-like cell attachment, proliferation, and differentiation were examined. Glass ceramic content was tested at 30 and 50 vol% and median particle size at 4.5 and 7.7 μm. Samples were prepared as 10 × 10 × 1 mm3 tiles with polished or roughened surfaces, sterilized by gamma irradiation (2.5 Mrad), and characterized by SEM, surface energy, and surface profilometry. Saos-2 human osteoblastlike cells were cultured on each surface at an initial concentration of 4500 cells/cm2 in McCoy's medium and incubated at 37C in a humidified atmosphere with 5% CO2 for 1, 3, or 7 days. At each time point, adenosine triphosphate (ATP) and alkaline phosphatase (ALP) levels were measured to assess cell number and osteoblast differentiation. Significant differences were found at 7 days, confirmed by ANOVA post-hoc testing using Bonferroni's correction. Overall, increased exposure of the A-W phase in AWPEX through surface polishing, higher volume fraction, and/or larger particle size, was found to lead to an improved cell response.
Amelogenin Induces Biomimetic Mineralization at Specific pH
Authors: Habelitz Stefan , Ford Dustin , Marshall Sally J. , DenBesten Pamela K. , Balooch Mehdi , Marshall Grayson W. , Li Wu 
Published: June 2019

AbstractAmelogenin proteins are assumed to control the calcification of dental enamel with a nanoscale precision that facilitates the formation of fibrous apatite crystals organized in a remarkable microstucture. In this study, recombinant full-length human amelogenin induced protein-guided mineralization and the formation of an enamel-like composite material at specific physical-chemical conditions as observed by atomic force microscopy (AFM). Amelogenin bound specifically to fluoroapatite crystals (FAP) of a glass-ceramic substrate at Ca2+ and PO43- concentrations similar to in-vivo conditions and at pH 8. Layers up to 400 nm high, containing elongated crystals, formed on the (001)-planes of FAP within 24h in supersaturated solutions. In contrast, (hk0)-faces grew by only 10-30 nm, but showed nanospheres aligned parallel to the c-axis of FAP. At pHs different from 8, proteins bound non-specifically to substrate and layers on FAP reached only 5-15 nm thickness. Micro-Raman spectroscopy and AFM revealed the formation of a composite material that resembled a structure and composition comparable to human enamel. These observations suggest that certain conditions are required to activate amelogenin to control and promote crystal growth of apatite along the c-axis and to synthesize an enamel-like material.
Synthesis and Electronic Transport Studies of Single-Crystalline In2O3 Nanowires
Authors: Li Chao , Zhang Daihua , Han Song , Liu Xiaolei , Tang Tao , Lei Bo , Zhou Chongwu 
Published: June 2019

AbstractSingle crystalline In203 nanowires were successful synthesized using a laser ablation method. Extensive material characterization such as X-ray diffraction (XRD) and selected area electron diffraction (SAED) revealed a cubic crystal structure for these nanowires with [110] as the growth direction. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) are used to determine the diameter and length of our nanowires. By using monodispersed gold clusters as the catalyst, these nanowires can be grown with well-defined diameters around 10 nm. Individual In2O3 nanowires have been utilized to construct field effect transistors, which confirmed In2O3 nanowires as n-type semiconductors and exhibited on / off ratios as high as 104 at room temperature. The temperature-dependence of the conductance revealed thermal emission as the dominating transport mechanism. Our work can lead to important applications such as chemical sensing for In2O3 nanowires.
Supercritical Fluids as New Reaction Media to Synthesize Nanostructured Materials
Authors: Aymonier Cyril , Desmoulins-Krawiec Sophie , Loppinet-Serani Anne , Weill François , Cansell François 
Published: June 2019

AbstractSupercritical fluids exhibit a range of unusual properties that can be exploited for the development of new reactions for material synthesis. These reactions are different from those performed in classical solid-state chemistry. Supercritical fluids are interesting as reaction media for the synthesis of nanostructured materials because fluid properties such as density, viscosity, diffusivity and solubility of reagents can be continuously tuned from gas to liquid with small variations in pressure and temperature. Moreover, supercritical fluid processing offers the possibility of using solvents with low toxicity that result in nanostructured materials free of solvent contamination. The process developed at ICMCB obtains nanostructured materials by chemically transforming a metal precursor inside a supercritical fluid. The synthesis of nanostructured materials such as metals, oxides or nitrides is possible at lower temperatures than the classic solid-state chemistry route. Based on experimental results and simulations, the nanostructured material nature, size and morphology can be continuously adjusted as a function of the operating condutions. Our process provides a great contribution in the development of self-assembled nanostructured materials by controlling the chemical composition, size, morphology and the surface properties of nanobricks.
Fluorinated Surfactant Templating of Ordered Nanoporous Silica
Authors: Rankin Stephen E. , Tan Bing , Lehmler Hans-Joachim , Knutson Barbara L. 
Published: June 2019

AbstractWe will describe the first synthesis of ordered mesoporous silica using a fluorinated surfactant template. Nitrogen adsorption, x-ray diffraction and TEM results will be presented that show that at room temperature, we form particles with well-ordered 2D hexagonal pores using a cationic surfactant with a partially fluorinated octyl (C8) tail. The pore diameter determined by the inflection in the nitrogen adsorption isotherm is on the order of 2.6 nm and the pore size distribution is very narrow. Consistent diameters are found with a modified Kelvin equation approach and with nonlocal density functional theory. The same pore size and long-range order are found for a range of surfactant to silica ratios.
Luminescence Properties of Europium-Doped Yttrium Oxides Derived from Their Dodecylsulfate-Templated Mesostructure and Nanotube Forms
Authors: Kijima Tsuyoshi , Iwanaga Kenichi , Hamasuna Tomomi , Mohri Shinji , Yada Mitsunori , Sekita Masami , Machida Masato 
Published: June 2019

AbstractEuropium-doped hexagonal-mesostructured and nanotubular yttrium oxides templated by dodecylsulfate species as well as surfactant free bulk oxides were synthesized by the homogeneous precipitation method. All the as grown nanostructured or bulk materials with amorphous or poorly crystalline frameworks showed weak luminescence bands at room temperature. On calcination at 1000°C these materials were converted into highly crystalline yttrium oxides, resulting in a total increase in intensity of all the bands by one order of magnitude. In the hexagonal-mesostructured system, the main band due to the 5D0-7F2 transition for the calcined phases showed a sharp but asymmetrical multiplet splitting indicating multiple Eu sites. Concentration quenching was found at a Eu content of 3 mol% or above for these phases. In contrast, the main emission for the calcined solids in the nanotubular system occurred as poorly resolved broad band and the intensity of the main band at higher Eu content was significantly enhanced compared with those for the other two systems.
Sol-gel Elaboration of Porous Oxide Coatings as Interphase in SiC/SiC Ceramic Matrix Composites
Authors: Verdenelli M. , Parola S. , Chassagneux F. , Jacques S. , Vincent H. , Dazord J. , Scharff J.P. , Bourgeat-Lami E. 
Published: June 2019

AbstractCombinations of meso-, macro- and microporous coatings with a chemical composition of 90%Al2O3-10%SiO2were elaborated on SiC Hi-Nicalon fibers using the sol-gel process. They were evaluated as porous interphase for the reinforcement of CMC. The mesoporous oxide, in contact with the fiber, allows cracks deviation whereas the macroporous one, in contact with the matrix, avoids the gaseous infiltration of the mesopores during the SiC CVD matrix process. It also prevents from oxygen diffusion during high temperature under air. The characterization of the composites was performed by SEM (scanning electron microscopy), TEM (transmission electron microscopy), X-ray diffraction, and EDS (energy dispersive spectrometry). TEM evidenced the porosity gradient as expected. A tensile test on the composites revealed brittle behavior (fracture) and no fiber debonding was observed.
Encapsulation of Ibuprofen in Mesoporous Silica: Solid State NMR Characterization
Authors: Babonneau Florence , Camus Lydie , Steunou Nathalie , Ramila Ainhoa , Vallet-Regi Maria 
Published: June 2019

AbstractMesoporous silica materials have been studied for the time-dependent delivery of bioactive agents. It has already been shown that ibuprofen molecules can be encapsulated with loading as high as 30 wt% in MCM-41 silica, functionalized or not by amino groups. Interactions between the guest molecules and the host matrix have been investigated by 1H, 29Si and 13C solid state NMR spectroscopy. These experiments demonstrate an extremely high mobility of the ibuprofen molecules when the matrix is not functionalized, despite of the presence of a carboxylic function on the ibuprofen molecules. On the contrary, when the silica matrix is functionalized by amino groups, the 13C NMR response shows a strong restriction in mobility suggesting the existence of interactions between the amino groups and the carboxylic groups.
Vapor Treatments of Spin-On Mesostructured Silica Films for the Enhancement of Structural Stability
Authors: Tanaka Shunsuke , Nishiyama Norikazu , Egashira Yasuyuki , Oku Yoshiaki , Ueyama Korekazu 
Published: June 2019

AbstractOrganically functionalized mesoporous silica films were prepared by a novel synthesis procedure. The synthesis procedure involves a vapor infiltration technique for mesostructured silica films prepared through a spin-coating process. Organic-functional groups were incorporated into the mesochannel wall by the vapor infiltration treatment using organosiloxanes. The structural stability of spin-on mesostructured silica films is generally low, resulting in a structural shrinkage or a collapse of the mesostructure under calcination process. On the other hand, the treated films did not contract during calcination, indicating high structural stability. A contact angle of water on the treated film was large, showing high hydrophobicity. FTIR analysis suggested that the residual silanol groups were replaced with the organosilyl groups after vapor infiltration treatment. The increase in the film thickness was hardly observed under vapor infiltration, suggesting no deposition of organosiloxanes vapor on the surface of the film.
Nanowire and Nanotube Syntheses Through Self-assembled Nanoporous AAO Templates
Authors: Wang H. Hau , Han Catherine Y. , Willing Gerold A. , Xiao Zhili 
Published: June 2019

AbstractNanowires and nanotubes have attracted significant interest during recent years due to their novel electrical, magnetic, and photonic properties. Quantum confinement, proximity interaction, and surface plasmon enhancement effects are among a few unique phenomena associated with these materials. A convenient procedure to prepare these materials is through anodized aluminum oxide (AAO) template synthesis. Nanoporous AAO membranes with pore diameters ranging from 10 to 200 nm can be prepared with anodization in oxalic, sulfuric and phosphoric acids under various reaction conditions. With repeated anodization-etching cycles, highly ordered straight channels can be prepared through self-organization. With electro- and electroless deposition, a variety of nanowires and nanotubes such as Ni, Co, Au, Pb, Bi, etc. have been prepared. The synthesis, characterization, and physical properties of these materials are presented.
Bio-Inspired Submicron Electrodes
Authors: Stanish Ivan , Lowy Daniel A. , Singh Alok 
Published: June 2019

AbstractImmobilized polymerized electroactive vesicles (IPEVs) are submicron biocapsules capable of storing charge in confined environments and chemisorbing on surfaces. Methods to immobilize stable submicron sized electroactive vesicles and the means to measure electroactivity of IPEVs at nanolevels have been demonstrated. IPEVs can withstand steep potential gradients applied across their membrane, maintain their structural integrity against surfaces poised at high/low electrical potentials, retain electroactive material over several days, and reversibly mediate (within the membrane) electron flow between the electrode surface and vesicle interior. IPEVs have strong potential to be used for charge storage and electron coupling applications that operate on the submicron scale and smaller.
Hygroscopic Growth of Self-Assembled Layered Surfactant Molecules at the Interface between Air and Organic salts
Authors: Shin Yongsoon , Wang Li-Qiong , Fryxell Glen E. , Exarhos Greg J. 
Published: June 2019

AbstractIn this paper, we report a self-assembly of surfactant molecules at the interface of air/hygroscopic quaternary ammonium salts such as tetrabutylammonium acetate (TBAAc), tetrabutylammonium bromide (TBAB), and tetrabutylammonium nitrate (TBAN), where they show different hygroscopicity, TBAAc > TBAB > TBAN. Homogeneously dissolved surfactants rearrange themselves when they contact air due to high moisture adsorption behavior of such organic salts. Highly ordered lamellar phases with different lattice spacings have been observed when surfactants with long alkyl chains were used. Alkylammonium halides form monolayers, while neutral alkylamines forms bilayers based upon basal spacings of their X-ray diffraction patterns. The change in basal spacings in lamellar patterns, the alkyl chain conformation of surfactants, and Hbonding property of neutral amine surfactants are discussed in detail.
Polymeric One-Dimensional Reflectors Based on Self-Organization of Comb-Shaped Supramolecules
Authors: Kosonen Harri , Valkama Sami , Ruokolainen Janne , Brinke Gerrit ten , Ikkala Olli 
Published: June 2019

AbstractPolystyrene-block-poly(4-vinylpyridine) (PS-block-P4VP) diblock copolymer was complexed with dodecylbenzenesulfonic acid (DBSA), leading to comb-coil polymeric supramolecules PS-block-P4VP(DBSA)y(y= 1.0, 1.5, and 2.0). Complexes formed hierarchical lamellar structure with long period of ca. 1400 Å. Due to periodicity and refractive index contrast between the layers, transmission and reflectance measurements showed a relatively narrow incomplete bandgap at ca. 460 nm. The angular dependence of the bandgap was also studied using different angles (ø) relative to the surface normal. The mid-gap was blue-shifted when the incident angle was increased indicating that the lamellar structure was partly oriented by the surfaces of quartz glasses.
Spin-Coating Self-Assembly for Micropatterning of Ultrathin Multilayer Films
Authors: Jang Hongseok , Kim Sangcheol , Char Kookheon 
Published: June 2019

AbstractA new approach to create layer-by-layer assembled multilayer ultrathin films with welldefined micropatterns in a short process time is introduced. To achieve such micropatterns with high line resolution in organic multilayer films, microfluidic channels were combined with the convective self-assembly process employing both hydrogen bonding and electrostatic intermolecular interactions. The channels were initially filled with polymer solution by capillary pressure and the residual solution was then removed by spinning process. The micropatterns with distinct line boundaries were obtained and the small ridges were also observed at the edges of the patterned lines. Spin self-assembled vertical heterostructural multilayer patterning using (PVP/PAA)5 micropatterns, which were prepared with microfluidic channels, as a template was also investigated.
Self-Organization of Gold Nanoparticles on Surface-Modified Conducting Polymer Films
Authors: Zhang Donghui , Klapman Sarah , Hanks Timothy W. 
Published: June 2019

AbstractThiol-coated gold nanoparticles with a diameter of approximately 7.5 nanometers and a narrow particle distribution were prepared from sodium tetrachloroaurate under phase transfer conditions. The thiols used were 1-mercaptododecane (1) and 1-mercapto-9,11-heptadecadiyne (4). The particles were cast onto thin films of polyaniline and poly (3,4-ethylenedioxythiophene), as well as onto thiol-coated versions of the same polymer. Surface modification of the polymers with long chain thiols encourages the spontaneous self-assembly of the particles into twodimensional arrays and may offer a unique method for stabilization of nanoparticle assemblies on polymer substrates.
Novel Conjugated Polymer/Silica Nanocomposites with Tunable Mesostructure Synthesized by a Robust Pd Catalyst
Authors: McCaughey Byron , Costello Chris , Hampsey J. Eric , Wang Donghai , Li Chaojun , Lu Yunfeng 
Published: June 2019

AbstractConjugated poly(2,5-thienylene ethynylene) (PTE)/silica nanocomposites with cubic and lamellar mesostructures have been synthesized. Surfactant directed assembly coorganized 2,5-diiodothiophene monomer and palladium-based catalyst within a silica matrix. Subsequent polymerization initiated by exposing the monomer/catalyst/silica nanostructures to acetylene gas resulted in the formation of an ordered, mesostructured poly(2,5-thienylene ethynylene)/silica nanocomposite as determined by XRD, UV-vis, FTIR, and TEM experiments. Mesostructured PTE with 287m2/g surface area is obtained after silica removal. Further polymerization of PTE oligomers occurs after exposure to acetylene gas due to active Pd catalyst attached to the polymer chains. This novel approach provides a unique route to synthesize mesostructured conjugated polymer/inorganic nanocomposites and porous mesostructured PTE.
One and Two-dimensional Semiconducting Nanostructures Self-assembly of Conjugated Oligomers
Authors: Leclère Ph. , Surin M. , Jonkheijm P. , Henze O. , Schenning A.P.H.J. , Biscarini F. , Grimsdale A.C. , Feast W.J. , Meijer E.W. , Müllen K. , Brédas J.L. , Lazzaroni R. 
Published: June 2019

AbstractThe properties of organic electronic materials in the solid-state are determined not only by those of individual molecules but also by those of ensembles of molecules. The ability to control the architectures of these ensembles is thus essential for optimising the properties of conjugated materials for use in electronic devices (light emitting diodes, field effect transistors, solar cells,…) and is primordial for potential technological applications in nanoelectronics.Here, we report on the observation by atomic force microscopy (AFM) of 1D and 2D nanoscale architectures obtained in the solid-state from solutions of molecularly-dissolved conjugated block copolymers or oligomers, and demonstrate that the conjugated molecules can organize onto a surface over lengthscales from nanometers to several microns, forming semiconducting fibrils by π-stacking processes.