bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structure/Property Relationships of Seashells
Authors: Scurr David J. , Eichhorn Stephen J. 
Published: April 2011

ABSTRACTThis study uses various characterisation techniques on the razor shell (Ensis siliqua), to relate the shell's microstructure to its mechanical properties. Scanning electron microscopy (SEM) has shown that the outer and inner regions of the shell are composed of simple and complex crossed lamellar microstructures respectively. These layers are interspersed by prismatic layers of a completely different crystallographic orientation. Nanoindentation and microhardness measurements have shown that the structure is anisotropic, and Raman band shifts have been observed within these indented/deformed areas of shell, showing that the microstructure deforms rather than generating surface damage. The use of energy variable synchrotron X-ray diffraction has shown that the calcium carbonate crystals of the shell are preferentially orientated as a function of depth and that opposing residual stresses exist at the outer and inner regions of the shell. This study has analysed several microstructural features of the shell and provided an insight into how they prevent failure of the material.
Microstructure of Brachiopod Shells - An Inorganic/Organic Fibre Composite with Nanocrystalline Protective Layer
Authors: Griesshaber E. , Schmahl W. , Neuser R. , Job R. , Bluem M. , Brand U. 
Published: April 2011

ABSTRACTWe investigated the ultrastructure of the modern calcitic brachiopods Megerlia truncata (Linnaeus) and Terebratalia transversa (Sowerby) with SEM, electron backscattering diffraction and microhardness indentation. The outer, primary shell layer can be regarded as a nanocrystalline thin film that forms a hard protective coating around the inner, much softer secondary layer that can be expressed as an inorganic/organic fibre composite. The fibrous, curved growth of the secondary shell layer crystals occurs in arbitrary directions perpendicular to the <0 0 0 1> triad symmetry direction of calcite and is most likely obtained by simple confinement to a protein sheath rather than by biomolecular adsorbates blocking growth of any specific crystal face. The curvature of the fibres is caused by rearrangements of the secreting cell array during growth, whereby the existing crystal lattice is not distorted. It serves as a substrate for continued crystal growth. Thus biologically mediated calcite crystallization is a purposeful process and seems to be significantly different to the inorganic crystallization of calcite.
Structure Property Characterization of Nonlinear Optical Materials
Authors: Rogers Joy E. , Slagle Jonathan E. , McLean Daniel G. , Hall Benjamin C. , Cooper Thomas M. , Fleitz Paul A. 
Published: April 2011

ABSTRACTThis research is comprised of understanding the linear photophysical properties of various dyes to better understand the more complicated nonlinear optical properties. Determining structure property relationships of a series of structurally closely related chromophores is the key in understanding the drivers for the various photophysical properties. In this paper we survey the effect of physically changing the Pt poly-yne structure on the S0-S1 and T1-Tn absorption properties for each of the chromophores. A series of structurally modified platinum poly-ynes have been studied using experimental methods including UV/Vis absorption and nanosecond laser flash photolysis. We found that with extension of the ligand length both the ground and triplet excited state absorption shift to lower energies. Comparing the absorption properties of the ligands and butadiynes with the platinum containing versions reveal that the S1 and Tn exciton is localized on one portion of the ligand with extension and not conjugated through the whole molecule. Changing the phosphine R group results in little effect to the absorption properties except when the R group is conjugated in the case of phenyl. However, changing the R group results in varied materials properties.
Platinum-Functionalized Chiral Molecular Squares as Light-Emitting Materials
Authors: Zhang Lin , Niu Yu-Hua , Jen Alex K.-Y. , Lin Wenbin 
Published: April 2011

ABSTRACTA family of new chiral metallocycles based on Pt(II) diimine metallocornors and bis(acetylene) bridging ligands have been synthesized, and characterized by a variety of techniques including 1H and 13C NMR, UV-visible, luminescence, infrared, and circular dichroism (CD) spectroscopies, and mass spectrometry. All metallocycles exhibit very strong phosphorescence with quantum yields of 8.3 to 15.7%. Chiral Pt(II)-based molecular squares were used as the light-emitting layer in multiplayer devices, and a maximum brightness of 5470 cd/m2 with a maximum luminous efficiency of 0.93 cd/A was achieved.
Optical and Electronic Properties of Metal-containing Poly-ynes and their Organic Precursors
Authors: Jura Marek , Koentjoro Olivia F. , Raithby Paul R. , Sharp Emma L. , Wilson Paul J. 
Published: April 2011

ABSTRACTA series of platinum(II) di-yne complexes with the general formula [PhPt(PR3)2-C≡C-X-C≡C-Pt(PR3)2Ph] where R = Et, nBu and X = a range of extended hetero-aromatic spacer groups, have been prepared by the coupling reaction between two molar equivalents of [PhPt(PR3)2Cl] and one molar equivalent of the terminal dialkyne, HC≡C-X-C≡CH, in the presence of CuI catalyst. The complexes have been characterised by IR, NMR and optical spectroscopy. These materials, which are precursors to related platinum(II) poly-yne polymers, have been specifically designed to be incorporated into metal-molecule-metal junctions in nanoelectronic devices.
Percolation-Enhanced Supercontinuum and Second-Harmonic Generation from Metal Nanoshells
Authors: Rohde Charles , Hasegawa Keisuke , Chen Aiqing , Deutsch Miriam 
Published: April 2011

ABSTRACTWe present results for linear and nonlinear light scattering experiments from percolative silver nanoshells on dielectric silica cores. Using ultrashort pulsed laser illumination we observe strong nonlinear optical (NLO) responses from single metallodielectric core-shell (MDSC) spheres and disordered MDSC sphere aggregates. Finally, combining scaling theory with core-shell Mie scattering formalism we obtain a new model for the observed linear extinction signals.
Ambipolar injection in a submicron channel light-emitting tetracene transistor with distinct source and drain contacts
Authors: Reynaert J. , Cheyns D. , Janssen D. , Arkhipov V. I. , Borghs G. , Genoe J. , Heremans P. 
Published: April 2011

ABSTRACTOver the last decade, organic semiconductor thin film transistors have been the focus of many research groups because of their potential application in low-cost integrated circuits. Recently, an organic light-emitting field-effect transistor (OLEFET) was reported. In an OLEFET structure, optimal injection of both holes and electrons into the light-emitting layer are required for maximum quantum efficiency, whereas the gate serves as a controlling electrode. In this work, we achieved an OLFET structure with interdigitated hole-injecting Au and electron-injecting Ca contacts within a submicrometer channel length. Both contacts are bottom contacts to the upper-lying tetracene organic semiconductor. The study of IV-characteristics and light emission from these devices shined light on the underlying physics of the OLEFETs.
Novel and Efficient electroluminescent organo-iridium phosphorescent OLED materials
Authors: Huang Heh-Lung , Shen Kou-Hui , Jhu Miao-Cai , Tseng Mei-Rurng , Liu Jia-Ming 
Published: April 2011

ABSTRACTWe investigated and synthesized different orientation and substituted group of the thieno-pyridine framework organo-iridium complexes (PO-01, PO-02, PO-03). These materials exhibited yellow light. Fabrication of these emissive phosphorescent dopants with the device configuration of ITO/ NPB/ CBP: Ir-complex (4–6%) /BCP/Alq3/LiF/Al showed the EL emitting peak from 532nm to 564nm. The electroluminescent efficiencies of the devices were from 9.62 lm/W to 30.41 lm/W and maximum brightness was all above 7000 cd/m2. We demonstrated high-efficiency, high-brightness and saturated yellow Ir-complex phosphorescent materials for OLED.
Photo-induced Optical and Chemical Properties of Polysilane/Inorganic Nano-Hybrids
Authors: Matsukawa Kimihiro , Matsuura Yukihito 
Published: April 2011

ABSTRACTPolysilane/inorganic (silica, titania) nano-hybrids might be attractive materials for organic photonics. Polymethylphenylsilane (PMPS)/silica nano-hybrid thin films were prepared by a sol-gel reaction of PMPS block copolymers with alkoxysilanes. The refractive index of hybrid thin films could be controlled with the composition ratio of PMPS, and the value was changed by UV irradiation accompanying photodecomposition of PMPS. After development of the irradiated hybrid thin films, nano porous (ca. 20nm) silica thin films were generated by removing the decomposed PMPS segments and a high refractive index difference occurred between irradiated and non-irradiated part in the hybrid thin films. Furthermore, under photodecomposition of polysilane copolymers, polysilane functioned as a reducing agent of gold (III) ions to prepare the gold nanoparticles.
Crystallization of POSS in a PEG-Based Multiblock Polyurethane: Toward A Hybrid Hydrogel
Authors: Wu Jian , Ge Qing , Burke Kelly A. , Mather Patrick T. 
Published: April 2011

ABSTRACTBuilding upon earlier success in forming materials with crystalline ordering of POSS via the telechelic architecture with POSS end-capping polyethylene glycols, here we report similar ordering in PEG-POSS thermoplastic polyurethane applicable to a novel hybrid hydrogel. Thus, a unique series of hybrid thermoplastic polyurethanes (TPUs) were synthesized using poly(ethylene glycol) (PEG) as soft segment and incorporating an isobutyl-functionalized POSS diol (TMP POSS diol) in the hard segment. The molecular weight of PEG was systematically varied to include 10, 20, and 35 kDa while the mole ratio of PEG to POSS diol (as chain extender) was chosen as 8:1. The diisocyanate employed for TPU polymerization was 4, 4'-methylenebis(phenyl-isocyanate) (MDI). Wide-angle X-ray diffraction (WAXD) studies revealed that both the hydrophilic soft segments (PEG) and hydrophobic hard segments (POSS) can form crystalline structures driven by micro-phase separation, itself due to thermodynamic incompatibility. Differential scanning calorimetry (DSC) and rheological studies revealed that thermal history is important in controlling the crystallization of a POSS-rich nanophase. Increasing the cooling rate monotonically decreases the crystallinity of POSS-rich phase and results in a decrease in the ultimate dynamic storage modulus following POSS crystallization and an increase of the loss angle for temperatures above Tm of PEG and below Tm of POSS. We conclude that both composition and thermal history are key factors in determing the internal network built by the POSS nanophase, which will have a significant influence on the properties of the resulting hybrid hydrogels now being studied.
Bioactive organic-inorganic hybrid aerogels
Authors: Esquivias Luis , Morales-Flórez Víctor , Piñero Manuel , Rosa-Fox Nicolás de la , Ramírez Julio , González-Calbet José , Salinas Antonio , Vallet-Regí María 
Published: April 2011

ABSTRACTWe have prepared organic-inorganic hybrid materials (OIHM), incorporating an organic phase in the inorganic precursor sol, using high power ultrasound for assistance with agitation. A sono-ormosil results after gelation. Colloidal silica particles have been added to these hybrids to enable network porous volume and pore radius to be tailored to specific requirements. Finally, in vitro bioactivity of this material has been promoted by adding calcium to the initial sol. The structure and bioactivity of these materials have been subjected to preliminary study, including their mechanical behaviour. These materials have a very fine structure especially after colloidal silica particles have been included. When immersed in a solution simulating blood plasma, they are bioactive, and the sample with colloid particles presents a better behaviour in vitro
Di-Urethane Cross-linked Poly(oxyethylene)/Siloxane Nanohybrids Doped With Eu(CF3SO3)3
Authors: Gonçalves M. C. , de Zea Bermudez V. , Sá Ferreira R. A. , Ostrovskii D. , Carlos L. D. 
Published: April 2011

ABSTRACTAttractive sol-gel derived di-urethane cross-linked poly(oxyethylene), POE/siloxane hybrids (di-urethanesils) doped with europium triflate, Eu(CF3SO3)3 were examined by Fourier Transform mid-infrared (FT-IR), Raman (FT-Raman) and Photoluminescence spectroscopies with the main goal of elucidating the chemical environment of the cations in these materials. In these hybrids the POE chains contain about 13 oxyethylene repeat units. Samples with compositions ∞ > n ≥ 5 (where n indicates the ratio of (OCH2CH2) moieties per Eu3+ion) were investigated. The FT-IR and FT-Raman data obtained provided unequivocal evidence that the ether oxygen atoms of the polymer chains start to interact with the Eu3+ ions at n = 20. The presence of a crystalline POE/Eu(CF3SO3)3 complex was detected at n ≥ 20. Photoluminescence results demonstrated that the doped di-urethanesils studied here are room temperature (RT) efficient full-color emitters. Two distinct cation local sites were unequivocally identified at n = 200 and 20. These Eu3+ local coordination sites involve the oxygen atoms of the urethane carbonyl groups and weakly coordinated Eu3+/CF3SO3 ionic species. For the most concentrated hybrid (n=5) evidences of a third local-environment probably involving the oxygen atoms of the polymer chains was observed.
Femtosecond fluorescence studies of Auramine O in hybrid sol-gel derived films
Authors: Prosposito P. , Quatela A. , Zhang H. , Glasbeek M. 
Published: April 2011

ABSTRACTFemtosecond fluorescence upconversion experiments have been performed on Auramine O (a diphenylmethane dye) in polymethylmethacrylate (PMMA) and in hybrid organic/inorganic solgel based films.All the investigated samples showed a fast decay (few picoseconds) and a long decay (hundreds of picoseconds). The fast components are representative of the rapid cooling of the excess excitation energy to the matrices. The long components are representative of the excited-state lifetime of the probed molecules. Auramine O in solid matrices showed lifetimes longer than in liquid solutions. Torsional diffusion motions of the two phenyl rings of the molecule are held responsible for the excited-state dynamics.A dynamic Stokes shift has been observed for all samples. The lack of a rise time when detection was on the red side is explained in terms of an adiabatic coupling between emissive and nonemissive excited states, as is the case of liquid solutions. Different spectral shifts in PMMA and hybrid glasses have been measured. A different coupling between the emissive and nonemissive excited states for the two types of matrices is considered.
Reliability Analysis of an Inorganic-Organic Hybrid Sol-gel Material System for Waveguiding Applications
Authors: O'Brien S. , Winfield R. J. , Connell A. , Crean G. M. 
Published: April 2011

ABSTRACTA novel epoxy-functionalised sol-gel material system for use in photonic waveguiding applications has been developed for use in short-range optical interconnect applications. The sol-gel material is deposited by spin coating to form a thin-film up to 25μm in thickness. The resulting film is selectively cross-linked using photo-lithography, as part of a UV-thermal curing process. A tunable film refractive index over the range 1.48–1.515 is demonstrated. The near-field images of transmitted radiation (633nm) from fabricated waveguide structures shows both waveguiding and efficient light confinement within the UV-thermally produced core regions. A thermal stability analysis of the waveguides following “Telcordia” environmental testing protocols for passive devices is presented. It is concluded that this materials system has the potential for use in waveguiding applications in environments where enhanced thermo-mechanical stability is required.
Preparation of Intercalative Organic/MoO3 Nanohybrid Thin Films and Their VOC Gas Sensing Properties
Authors: Matsubara Ichiro , Murayama Norimitsu , Shin Woosuck , Izu Noriya 
Published: April 2011

ABSTRACTOrganic/MoO3 nanohybrid thin films have been successfully prepared by an ex-situ intercalation process. The host MoO3 films were first deposited on LaAlO3 (LAO) single crystal substrates by using a CVD method followed by the intercalation of butylammonium ions, (BuNH3)+, into the MoO3 films to give (BuNH3)xMoO3 thin films. The preparation of highly b-axis oriented MoO3 films is crucial to prepare the (BuNH3)xMoO3 films. The (BuNH3)xMoO3 thin films exhibit a resistance-increasing response to aldehyde gases as in the case of bulk samples, whereas no response was observed for methanol, ethanol, chloroform, acetone, toluene, and xylene. The thin film process developed for intercalative organic-inorganic hybrid makes it possible to apply this material in VOC sensor devices.
From Hybrid Films to Mesoorganized Multi-metal-oxide Nanocrystalline Films (M3NF), preparation and characterization.
Authors: Boissière Cédric , Grosso David , Smarsly Bernt , Brezesinski Torsten , Lepoutre Sophie , Nicole Lionel , Valle Marcos J. C. , Antonietti Marcus , Sanchez Clément 
Published: April 2011

ABSTRACTHigh quality and reproducible thin silica and non-silica mesoporous films were obtained with mono-oriented organised mesoporosity, fitting various symmetry groups (i.e. p6m, Pm3n, Im3m, …). The Evaporation Induced Self Assembly (EISA) mechanism of structuration was studied through in-situ time-resolved SAXS, interferometry and spectroscopic ellipsometry investigations during dip-coating. A Modulable Steady State (MSS) was found during which the system is in quasi-equilibrium with its environment and during which the final structure is formed. The corresponding Self-Assembly mechanism was found to be governed by a competition between evaporation, micellization and condensation that depend on various critical chemical and processing parameters the influence of which have been summarized into directly usable phase diagrams. Calcined SiO2 and TiO2 mesoporous films structure (pore size and anisotropy, porous volume and surface) and mechanical properties (young modulus) were investigated by UV-Visible spectroscopic ellipsometry. Finally, thanks to a specially designed block copolymer, one further step was accomplished by achieving the dip coating and controlled nano-crystallisation of various metallic and multi-metal-oxides films (M3NF) of composition CoxTi(1-x)O(2-x) with ilmenite or doped Anatase structure, and SrTiO3 and MgTa2O6 with perovskite structure. Attending the well known magnetic, dielectric and catalytic properties of these structures, M3NF are highly compatible with high technology applications in microelectronic, energy transfer devices, spintronic, nano-mechanical adjustments, data storage, oxide fuel cells …
Modification of Metal Alkoxide Precursors by Organofunctional Bidentate Ligands: Chemical Problems and Opportunities for Materials Syntheses
Authors: Schubert Ulrich , Bauer Ulrike , Fric Helmut , Puchberger Michael , Rupp Wolfgang , Torma Viktoria 
Published: April 2011

ABSTRACTBidentate ligands are potentially useful to modify metal alkoxides precursors for sol-gel processing. However, anionic bidentate ligands are needed to get a strong coordination, while diamines as neutral bidentate ligand form coordination polymers [Ti2(OR)8(diamine)2]∞ when reacted with Ti(OR)4. The Lewis acidity of metal alkoxides may cause organic side reactions. The first is the formation of ester and water in the reaction with carboxylic acids, and therefore carboxylate-substituted metal oxide clusters of the general composition MnOx(OH/OR)y(OOCR)z are obtained instead of substituted monomeric precursors. The second side reaction discussed is the cleavage of β-diketones by metal alkoxides. Despite this side reaction, 3-acetyl-6-trimethoxy-silyl-hexane-2-one is a useful compound to prepare single-source precursos for silica/metal oxide composites.
Three Dimensional Structure and Liquid Transport Behavior of Siloxane Gels with Co-continuous Macropores
Authors: Saito Haruko , Nakanishi Kazuki , Hirao Kazuyuki , Jinnai Hiroshi , Morisato Kei , Minakuchi Hiroyoshi 
Published: April 2011

ABSTRACTThe geometrical properties of co-continuous macroporous silica monoliths have been studied by laser scanning confocal microscopy (LSCM) and a comparison with mercury intrusion method has been made. From three-dimensional images obtained by LSCM observation, probability density distributions of curvatures have been calculated on gel skeleton surface by the “sectioning and fitting method”. Measured liquid transport behavior in macroporous siloxane gels has been related to the obtained curvature distributions.
Rational Design of Macrocellular TiO2 and V2O5 Monoliths Obtained Through Soft Chemistry and Air-liquid Foams
Authors: Carn F. , Steunou N. , Colin A. , Livage J. , Sanchez C. , Backov R. 
Published: April 2011

ABSTRACTChemistry of shapes appears as a strong interdisciplinary field of research that encompasses both the area of soft matter, physical-chemistry and soft chemistry. In this general context, hierarchical inorganic macrocellular monoliths have been obtained using air-liquid foams as a macroscopic pattern while lyotropic mesophases are employed to create porosity at the mesoscale. At the macroscopic length scale, both cell sizes and shapes as well as the Plateau borders thickness and topologies can be designed with a strong degree of control. Some examples with different inorganic network as TiO2 and V2O5 are depicted with specific characterizations.
Pattern Formation on Silicon-on-Insulator
Authors: Flack Frank S. , Yang Bin , Huang Minghuang , Marcus Matt , Simmons Jason , Castellini Olivia M. , Eriksson Mark A. , Liu Feng , Lagally Max G. 
Published: April 2011

ABSTRACTThe strain driven self-assembly of faceted Ge nanocrystals during epitaxy on Si(001) to form quantum dots (QDs) is by now well known. We have also recently provided an understanding of the thermodynamic driving force for directed assembly of QDs on bulk Si (extendable to other QD systems) based on local chemical potential and curvature of the surface. Silicon-on-insulator (SOI) produces unique new phenomena. The essential thermodynamic instability of the very thin crystalline layer (called the template layer) resting on an oxide can cause this layer, under appropriate conditions, to dewet, agglomerate, and self-organize into an array of Si nanocrystals. Using low-energy electron microscopy (LEEM), we observe this process and, with the help of first-principles total-energy calculations, we provide a quantitative understanding of this pattern formation. The Si nanocrystal pattern formation can be controlled by lithographic patterning of the SOI prior to the dewetting process. The resulting patterns of electrically isolated Si nanocrystals can in turn be used as a template for growth of nanostructures, such as carbon nanotubes (CNTs). Finally we show that this growth may be controlled by the flow dynamics of the feed gas across the substrate.
Controlling (In, Ga)As quantum structures on high index GaAs surfaces
Authors: Seydmohamadi Sh. , Wen H. , Wang Zh. M. , Salamo G. J. 
Published: April 2011

AbstractWe investigate the formation of (In, Ga)As self assembled quantum structures grown on different orientations of a GaAs substrate along one side of the stereographic triangle between (100) and (111)A surfaces. The samples were grown by Molecular Beam Epitaxy, monitored by Reflection High-Energy Electron Diffraction during the growth and characterized by in-situ Scanning Tunneling Microscopy and Atomic Force Microscopy. A systematic transition from zero dimensional (In, Ga)As quantum dots to one dimensional quantum wires was observed as the substrate was varied along the side of the triangle within 25° miscut from the (100) toward (111)A, which includes several high index surfaces. We propose an explanation for the role of the substrate in determining the type of the nanostructure that is formed.