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CLEO: science and Innovations, CLEO_SI 2013

作者： Haglund, Richard F. Mayo, Daniel C. Singaravelu, Senthilraja Park, Hee-Kuwon Grigoropoulos, Costas P. Schriver, Kenneth E. Interdisciplinary Materials Science Program Vanderbilt University Nashville TN 37234-0106 United States AppliFlex LLC 110 Space Park South Nashville TN 37211 United States Department of Mechanical Engineering University of California Berkeley CA 94720-1740s United States Department of Physics and Astronomy Vanderbilt University Nashville TN 37235-1807 United States

We demonstrate a multilayer anti-reflective conformal coating for polycarbonate substrates, using a a polymer nanocomposite, fabricated by resonant infrared pulsed laser evaporation. The coating has 97% transmission, ... 详细信息

ISBN: (纸本)9781557529725

关键词： Fabrication

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Inside Cover: Out-of-Cell Oxygen Diffusivity Evaluation in Lithium–Air Batteries (ChemElectroChem 12/2014)

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ChemElectroChem 2014年第12期1卷 2032-2032页

作者： Prof. Weidong He Xiaoning Wang Luhan Ye Yu Pan Yuanqiang Song Aifang Liu Wei Wang Hongping Zhang Hongxue Qi Ming Zhou Zhiguo Wang Kelvin H. L. Zhang James H. Dickerson School of Energy Science and Engineering University of Electronic Science and Technology (UESTC) Chengdu Sichuan 611731 (P. R. China) Interdisciplinary Program in Materials Science Vanderbilt University Nashville Tennessee 37234-0106 (USA) Vanderbilt Institute of Nanoscale Science and Engineering Vanderbilt University Nashville Tennessee 37234-0106 (USA) Shenzhen Key Laboratory for Advanced Materials Department Material Science and Engineering Shenzhen Graduate School Harbin Institute of Technology University Town Shenzhen 518055 (P. R. China) School of Materials Science and Engineering Southwest University of Science and Technology Mianyang Sichuan 621010 (P. R. China) Department of Chemistry The University of Hong Kong Pokfulam Road (Hong Kong) Department of Applied Physics University of Electronic Science and Technology of China Chengdu 610054 (P. R China) Department of Chemistry Chemistry Research Laboratory University of Oxford Mansfield Road Oxford OX1 3TA (UK) Department of Physics Brown University Providence RI 02912 (USA)

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Preliminary results on biomimetic methods based on soluble ammonium phosphate precursors for the consolidation of archaeological wall paintings

Preliminary results on biomimetic methods based on soluble a...

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作者： Balonis-Sant, Magdalena Ma, Xiao Kakoulli, Ioanna Department of Materials Science and Engineering University of California Los Angeles 410 Westwood Plaza Los Angeles CA 90005-1595 United States UCLA/Getty Conservation Program Cotsen Institute of Archaeology University of California Los Angeles 308 Charles E. Young Drive North Los Angeles CA 90095-1510 United States

ISBN: (纸本)9780841229242

This research develops hydroxyapatite (HAP)-based, inorganic mineral systems for the consolidation of powdery wall paintings of archaeological significance. The scientific approach exploits biomimetic (biologically inspired design) principles to induce in situ the formation of protective HAP crystals by triggering reactions between the calcium carbonate-rich layers in wall paintings and ammonium phosphate precursors. The high solubility and absence of toxicity of ammonium phosphate precursors and the stability of the hydroxyapatite reaction product at varying pH, renders this treatment extremely promising for consolidation and protection of weathered wall paintings. Experimental trials were carried out on wall painting test blocks applying cellulose compresses of 1M and 2M solutions of diammonium hydrogen phosphate for 3 to 6 hours contact time. The consolidating effect was evaluated through microstructurally and compositionally-sensitive analytics including VPSEM-EDS, XRF, water sorption test and scotch tape test. Preliminary results indicated the formation of a porous hydroxyapatite network at the surface and subsurface of the test blocks with improved cohesion, pH-resistivity and reduced water absorption. These data show the potential of this treatment for the consolidation of powdery wall paintings and their protection from weathering and deterioration induced by natural aging and environmental action-linked effects. Copyright © 2013 American Chemical Society.

关键词： Hydroxyapatite

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Origin of Overstretching Transitions in Single-Stranded Nucleic Acids

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Physical Review Letters 2013年第18期111卷 188302-188302页

作者： Zackary N. Scholl Mahir Rabbi David Lee Laura Manson Hanna S-Gracz Piotr E. Marszalek Program in Computational Biology and Bioinformatics Duke University Durham North Carolina 27708 USA Department of Mechanical Engineering and Materials Science Center for Biologically Inspired Materials and Material Systems Duke University Durham North Carolina 27708 USA Department of Molecular and Structural Biochemistry North Carolina State University Raleigh North Carolina 27708 USA

We combined single-molecule force spectroscopy with nuclear magnetic resonance measurements and molecular mechanics simulations to examine overstretching transitions in single-stranded nucleic acids. In single-stranded DNA and single-stranded RNA there is a low-force transition that involves unwinding of the helical structure, along with base unstacking. We determined that the high-force transition that occurs in polydeoxyadenylic acid single-stranded DNA is caused by the cooperative forced flipping of the dihedral angle formed between four atoms, O5’-C5’-C4’-C3’ (γ torsion), in the nucleic acid backbone within the canonical B-type helix. The γ torsion also flips under force in A-type helices, where the helix is shorter and wider as compared to the B-type helix, but this transition is less cooperative than in the B type and does not generate a high-force plateau in the force spectrums of A-type helices. We find that a similar high-force transition can be induced in polyadenylic acid single-stranded RNA by urea, presumably due to disrupting the intramolecular hydrogen bonding in the backbone. We hypothesize that a pronounced high-force transition observed for B-type helices of double stranded DNA also involves a cooperative flip of the γ torsion. These observations suggest new fundamental relationships between the canonical structures of single-and double-stranded DNA and the mechanism of their molecular elasticity.

关键词： NUCLEAR magnetic resonance spectroscopy SINGLE-stranded DNA NUCLEOTIDE sequence DEOXYRIBOSE ATOMIC force microscopy

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Mechanisms of fragmentation and microstructure of debris generated during explosive testing of Al-W granular composite rings

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Journal of Physics: Conference Series 2014年第11期500卷

作者： Po-Hsun Chiu K L Olney C Braithwaite A Jardine A Collins D J Benson V F Nesterenko Materials Science and Engineering Program University of California San Diego San Diego CA 92027 USA Department of Mechanical and Aerospace Engineering University of California San Diego San Diego CA 92027 USA Fracture and Shock Physics SMF Group Department of Physics Cavendish Laboratory Cambridge CB3 0HE UK Department of Structural Engineering University of California San Diego San Diego CA 92027 USA

Highly heterogeneous materials comprised of elements with drastically different densities and shock impedances (e.g., Al and W) may provide additional mesoscale fragmentation mechanisms reducing the characteristic fragment size in comparison with solid materials with similar density (e.g., Stainless Steel 304). Explosively driven expanding ring experiments were conducted with Al-W granular composite rings, processed using hot and cold isostatic pressing, with different morphologies (W polyhedral particles or W rods with high aspect ratio and bonded/unbonded Al spherical particles with different sizes). In comparison to homogeneous samples with a similar density, these granular/porous composites generated fragments with a significantly smaller characteristic size. Scanning Electron Microscopy revealed that fragments had a propensity to be composed of clustered Al and W particles. Finite element simulations were conducted to gain an insight into the mesoscale fragmentation mechanisms and the clustering behavior observed in the experiments. Understanding the mesoscale mechanisms of explosively driven pulverization is important for tailoring the size of the fragments through the alteration of mesostructural properties.

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Porous hydroxyapatite-polyhydroxybutyrate composites fabricated by a novel method via centrifugation

Porous hydroxyapatite-polyhydroxybutyrate composites fabrica...

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2012 Annual Conference on Experimental and Applied Mechanics

作者： Porter, Michael M. Lee, Steve Tanadchangsaeng, Nuttapol Jaremko, Matt J. Yu, Jian Meyers, Marc McKittrick, Joanna Materials Science and Engineering Program University of California San Diego 9500 Gilman Dr. San Diego CA 92093 United States Hawaii Natural Energy Institute University of Hawaii at Manoa 1680 East West Road Honolulu HI 98622 United States Department of Mechanical and Aerospace Engineering University of California San Diego 9500 Gilman Dr. San Diego CA 92093 United States

ISBN: (纸本)9781461444268

Porous hydroxyapatite-polyhydroxybutyrate (HA-PHB) composites were fabricated by infiltrating PHB micro-/nano-particles into rigid HA scaffolds via centrifugation, followed by subsequent heating at 175°C to melt the PHB into the scaffolds. HA scaffolds were obtained by heating trabecular bovine femur bone at 1,350°C to remove the organic and sinter the HA. PHB particles were recovered and purified from microbial cells by two different chemical methods, which either filled the apparent porosity of the scaffolds or coated the trabecular network of the scaffolds after heating. The mechanical properties, porosity, HA/PHB volume fractions and surface adhesion of the resulting HA-PHB composites were investigated and compared to the original HA scaffolds. The final porosities of the filled and coated composites were ∼54% and ∼67%, respectively. All of the HA-PHB composites showed a slight increase in strength with the addition of PHB. The filled composites showed no change in stiffness from the addition of PHB, while the coated composites showed an increase in stiffness over the original HA scaffolds from ∼35 to ∼105 MPa. The enhanced stiffness in the coated composites was due to strong interactions between its HA and PHB constituent phases. Very little inter-constituent adhesion was observed in the filled composites. © The Society for Experimental Mechanics, Inc. 2013.

关键词： Hydroxyapatite

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Processing and characterization of cyanate ester- MWNT nanocomposites 54

Processing and characterization of cyanate ester- MWNT nanoc...

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54th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and materials Conference

作者： Lao, Si-Chon Moon, Tess J. Koo, Joseph H. Horváth, Zsolt E. Materials Science and Engineering Graduate Program University of Texas at Austin 204 E. Dean Keeton St./C2201 Austin TX 78712-0292 United States Department of Mechanical Engineering University of Texas at Austin 204 E. Dean Keeton St./C2200 Austin TX 78712-0292 United States Department of Mechanical Engineering Polymer Nanocomposites Technology Laboratory University of Texas at Austin 204 E. Dean Keeton St./C2200 Austin TX 78712-0292 United States Research Institute for Technical Physics and Materials Science Hungarian Academy of Sciences P.O. Box: 49 H-1525 Budapest Hungary

ISBN: (数字)9781624102233

ISBN: (纸本)9781624102233

In this study, a low viscosity, high performance cyanate ester (CE) resin system was used with non-functionalized and functionalized multiwall carbon nanotubes (MWNTs) to create cyanate ester-MWNT nanocomposites. Effects of three different standard functionalizations (i.e. -OH, -COOH, and -NH2) of MWNTs on their dispersion into the CE resin will be studied. Different mixing instruments, such as a high shear mixer, ultrasonicater, planetary mixer, etc. were used to disperse the nanotubes in the cyanate ester resin matrix. Several processing parameters were examined to produce optimal uniform dispersions of nanoparticles into the resin matrix. The parameters studied were mixing speed and duration, and the combination of different mixing techniques. Polymer nanocomposites (PNCs) morphological microstructures were characterized by transmission electron microscopy (TEM) and high resolution scanning electron microscopy (HR-SEM) to determine whether nanotubes are distributed uniformly within the polymer matrix. Thermogravimetric analysis (TGA) and microscale combustion calorimetry (MCC) were used to study the thermal stability and combustion characteristics of these nanocomposites. Dynamic mechanical thermal analysis (DMTA) was used to determine the glass transition temperature (T g) of the PNCs. © 2012 AIAA.

关键词： High resolution transmission electron microscopy

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Rotational and translational diffusion of anisotropic gold nanoparticles in liquid crystals controlled by varying surface anchoring

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Physical Review E 2013年第6期88卷 062507-062507页

作者： Bohdan Senyuk David Glugla Ivan I. Smalyukh Department of Physics University of Colorado at Boulder Boulder Colorado 80309 USA Department of Electrical Computer and Energy Engineering University of Colorado at Boulder Boulder Colorado 80309 USA Liquid Crystals Materials Research Center and Materials Science and Engineering Program University of Colorado at Boulder Boulder Colorado 80309 USA Renewable and Sustainable Energy Institute National Renewable Energy Laboratory and University of Colorado at Boulder Boulder Colorado 80309 USA

We study translational and rotational diffusion of anisotropic gold nanoparticles (NPs) dispersed in the bulk of a nematic liquid crystal fluid host. Experimental data reveal strong anisotropy of translational diffusion with respect to the uniform far-field director, which is dependent on shape and surface functionalization of colloids as well as on their ground-state alignment. For example, elongated NPs aligned parallel to the far-field director translationally diffuse more rapidly along the director whereas diffusion of NPs oriented normal to the director is faster in the direction perpendicular to it while they are also undergoing elasticity-constrained rotational diffusion. To understand physical origins of these rich diffusion properties of anisotropic nanocolloids in uniaxially anisotropic nematic fluid media, we compare them to diffusion of prolate and oblate ellipsoidal particles in isotropic fluids as well as to diffusion of shape-isotropic particles in nematic fluids. We also show that surface functionalization of NPs with photosensitive azobenzene groups allows for in situ control of their diffusivity through trans-cis isomerization that changes surface anchoring.

关键词： ANISOTROPY GOLD nanoparticles ROTATIONAL diffusion COLLOIDAL dispersions NEMATIC liquid crystals COLLOIDS AZOBENZENE

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Graphene-like nanostructures obtained from Biomass

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MRS Online Proceedings Library 2013年第1期1505卷 1-6页

作者： Borin Barin, Gabriela Honorato Santos, Yane Alves Rocha, Jennyfer Pereira da Costa, Luiz Gomes Souza Filho, Antônio de Fátima Gimenez, Iara Silva Barreto, Ledjane Pos-graduation Program of Science and Materials Engineering Federal University of Sergipe São Cristóvão Brazil Department of Chemistry Federal University of Sergipe São Cristóvão Brazil Pos Graduation Program of Industrial Biotechnology Tiradentes University Aracaju Brazil Department of Physic Federal University of Ceara Ceará USA

Two dimensional (2D) carbon nanomaterials such as few graphite layers or graphene are extensively studied due to their unique properties suitable to be exploiting in a wide range of technological applications. Recently, the growth of high quality graphene monolayers using insects and waste as carbon precursors was reported in the literature. This methodology opened a new way to convert the waste carbon into a high-value-added product. In the present work coconut coir dust, an agroindustrial biomass, was used as biotemplate for preparing carbonaceous materials. Carbon structures were synthesized through pyrolysis under nitrogen atmosphere (100mL/min) at 500, 1000, and 1500°C during 2 hours. Starting materials were coconut coir dust in natura and coconut coir dust hydrothermally treated. The samples were characterized by X-ray diffraction, Raman Spectroscopy, Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). Raman spectra showed the D band for all samples, related to the presence of defects in sp2 carbon structure and G band, indicative of graphite crystallites. It was also observed that the sample carbonized at 1500°C from coconut coir dust treated by hydrothermal method showed G’ band at 2685cm-1 associated with the stacking order along the c-axis. X-ray diffraction analysis showed a broad peak around 2θ= 22° related to the presence of amorphous carbon. By increasing the pyrolysis temperature changes in XRD diffractograms were observed and the sample which was pyrolysed at 1500°C from coconut coir dust hydrothermally treated showed peaks at 2θ= 26.5°, 43° e 45° assigned to (002), (100) (101) graphite plans, respectively. Scanning electron microscopy images showed the presence of overlapping sheets and plates. Transmission Electron Microscopy (TEM) images of coconut coir dust in natura unveiled the formation of amorphous sheet. Coconut coir dust in natura and treated by the hydrothermal method pyrolysed at 1500°C, lead to the formation of

关键词： carbonization hydrothermal nanostructure

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Modeling and simulation of the microalgae derived hydrogen process in compact photobioreactors

Modeling and simulation of the microalgae derived hydrogen p...

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IEEE Conference on Technologies for Sustainability

作者： J. V. C. Vargas D. A. Mitchell A. B. Mariano D. O. Correa J. C. Ordonez Graduate Program in Engineering and Materials Science PIPE and Sustainable Energy Research and Development Center NPDEAS Federal University of Parana Department of Mechanical Engineering Energy and Sustainability Center and Center for Advanced Power Systems Florida State University FSU

ISBN: (纸本)9781467346290

A general transient mathematical model for managing microalgae derived hydrogen production, with temperature dependence of the cultivation medium is developed. For that, the simplified physical model combines principles of classical thermodynamics, mass, species and heat transfer, resulting in a system of differential equations which are discretized in space using a three-dimensional cell-centered finite volume scheme. A Michaelis-Menten type expression is proposed for modeling the rate of H_2 production with dependence on O_2 inhibition. Tridimensional simulations are performed in order to determine the mass fractions distributions inside a compact photobioreactor (PBR), under different operating conditions. A relatively coarse mesh was used (6048 volume elements) to obtain converged results for a large compact PBR computational domain (5m×2m×8m). The largest computational time required for obtaining results was 560 s, i.e., less than 10 min. The numerical results for microalgal growth are validated by direct comparison to experimental measurements. Hydrogen production simulations are conducted to demonstrate PBR intermittent operation (aerobic and anaerobic stages) feasibility and adequate species evolution trends in an indirect biophotolysis approach. Therefore, after experimental validation for a particular H_2 production system, it is reasonable to state that the model could be used as an efficient tool for PBR systems thermal design, control and optimization for maximum H_2 production.

关键词： Chlamydomonas reinhardtii Scenedesmus sp. Photobioreactor architecture Early stage design tool

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