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8th World Biomaterials Congress 2008, WBC 2008

作者： Ko, Ching-Chang Ma, Alice Kaku, Masaru Liu, Kai-Li Luo, T.-J.M. Tulloch, J.F.C. Hu, W.-S. Department of Orthodontics University of North Carolina Chapel Hill NC 27599-7450 United States Applied Materials Science Program University of North Carolina Chapel Hill NC 27599-7450 United States Department of Material Science Engineering North Carolina State University Raleigh NC 27695-7907 United States Department of Chemical Engineering and Material Sciences University of Minnesota Minneapolis MN 55455 United States

ISBN: (纸本)9781615670802

It was hypothesized that the hydroxyapatite(HAP)/GEMOSIL biomaterial could promote osteoblast (MC3T3) self-organization. This study using MC3T3 cell line demonstrated formation of trabecular bone-like extracellular matrix (ECM) on the material compared to unorganized ECM on the control (no-material). The study also initiated exploratory tests for the underlying mechanisms via gene analysis and proliferation assay.

关键词： Hydroxyapatite

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Ionic liquids as additives for thermoplastics

Ionic liquids as additives for thermoplastics

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Society of Plastics Engineers Annual Technical Conference: Plastics Encounter at ANTEC 2007

作者： Park, K.I. Xanthos, M. Material Science and Engineering Program New Jersey Institute of Technology Newark NJ Otto H. York Department of Chemical Engineering New Jersey Institute of Technology Newark NJ

In attempts to develop new process modifiers for thermoplastics, two ionic liquids with long chain hydrophobic cations and different anions were introduced in a biodegradable polymer. Methods of incorporation included melt blending, solvent casting and microencapsulation from w/o/w systems at concentrations up to 10 wt%. The modified polymers were characterized Theologically and by TGA to determine process and thermal stability, respectively, and by DSC to determine miscibility and types of the polymer-ionic liquid interactions. Potential applications in plasticization, lubrication and emulsification are discussed for selected polymer-ionic liquid combinations.

关键词： Ionic liquids

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Carbon nanostructure field emission devices

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Journal of Vacuum Science and Technology B: Microelectronics and Nanometer Structures 2006年第2期24卷 1008-1012页

作者： Wong, Y.M. Kang, W.P. Davidson, J.L. Soh, K.L. Choi, B.K. Hofmeister, W. Department of Electrical Engineering and Computer Science Vanderbilt University Nashville TN 37235 Interdisciplinary Graduate Program in Material Science Vanderbilt University Nashville TN 37235 Department of Chemical Engineering Vanderbilt University Nashville TN 37235

The microwave plasma chemical vapor deposition (MPCVD) method is capable of synthesizing various forms of carbon allotropes such as diamond, carbon nanotubes (CNTs), and diamondlike carbon (DLC) while varying the growth parameters or utilizing substrate coated with catalytic thin film. In this article, needlelike carbon nanostructures (CNs) were synthesized utilizing high power (5 kW) and high working pressure (120 Torr) MPCVD on a thin catalytic film of nickel with a diffusion barrier layer of titanium on a micropatterned silicon substrate. The effects of in situ doping by trimethylboron (TMB) on the morphologies and field emission properties of the CNs were also investigated. Straight, needlelike CNs with random orientation were obtained for 15 min growth time with or without TMB doping. However, the CNs appear to transform into diamondlike nanocrystals after prolonged growth of 30 min with TMB doping. Unlike MPCVD grown CNTs, it was found that the CNs have strong adhesion to the substrate and could withstand postgrowth processing such as ultrasonic agitation cleaning in solvents. Field emission tests performed show that in situ TMB doping of the patterned needlelike CNs lowers the turn-on field of the cathode. A vacuum field emission triode with self-aligned gate utilizing CNs as the field emitter is also fabricated. © 2006 American Vacuum Society.

关键词： Carbon nanotubes

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Increased stability of PFSA proton exchange membranes under fuel cell operation by the decomposition of peroxide catalyzed by heteropoly acids

Increased stability of PFSA proton exchange membranes under ...

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Proton Exchange Membrane Fuel Cells 6 - 210th Electrochemical Society Meeting

作者： Haugen, Gregory M. Meng, Fanqin Aieta, Niccolo Horan, James L. Kuo, Mei-Chen Frey, Mathew H. Hamrock, Steven J. Herring, Andrew M. Department of Chemical Engineering Colorado School of Mines Golden CO 80401 United States 3M Fuel Cell Components Program 3M Center St Paul MN 55144 United States 3M Corporate Research Material Laboratory 3M Center St Paul MN 55144 United States

ISBN: (纸本)1566775019

Proton exchange membranes were cast from mixtures of the 3M perfluorinated sulfonic acid ionomer, with side chain -O-(CF2)4-SO 3H, and various heteropoly acids (HPAs) at a 10 or 20 wt% doping level. The membrane electrode assemblies (MEAs) prepared from these membranes were subjected to a fuel cell testing protocol involving incubation to steady state, temperature challenge, accelerated testing, and post mortem analysis. The cell temperature was varied from 70-100°C under relatively dry conditions, 70°C dewpoint, to avoid leaching of the HPA. The most important finding from this study was that the more stable HPAs, H4SiW12O 40, α-H3P2W18O62, and H6P2W21O71 reduce the rate of F- release threefold and improve the performance of the MEA dramatically under these conditions. For HPAs that possibly rearrange in peroxide or at elevated temperatures, H3PW12O 40, H6CoW12O40, H 5SiAlW11O39, H6As2W 21O69, and H21B3W39O 162, the results were mixed as fragments of these molecules possibly interfere with the fuel cell electrochemistry. copyright The Electrochemical Society.

关键词： Ion exchange membranes

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Spectroscopic and SAXS studies of heteropoly acid-doped 3M perfluorinated sulfonic acid polymer membranes

Spectroscopic and SAXS studies of heteropoly acid-doped 3M p...

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208th Meeting of the Electrochemical Society

作者： Meng, Fanqin Dec, Steven F. Willimason, Don Frey, Matthew H. Hamrock, Steven J. Turner, John A. Herring, Andrew M. Departments of Chemical Engineering Colorado School of Mines Golden CO 80401 United States Departments of Chemistry and Geochemistry Colorado School of Mines Golden CO 80401 United States Departments of Physics Colorado School of Mines Golden CO 80401 United States 3M Fuel Cell Components Program 3M Center St Paul MN 55144 United States 3M Corporate Research Material Laboratory 3M Center St Paul MN 55144 United States Hydrogen and Electricity Systems and Infrastructure Group National Renewable Energy Laboratory Golden CO 80401 United States

ISBN: (纸本)1566774969

3M PFSA ionomer membranes were doped with heteropolyacids (HPA) and the ionomer/HPA interaction characterized by attenuated total reflection FTIR, pulse field gradient spin echo NMR and small-angle X-ray scattering. The HPA doping was achieved by casting a solution containing both components. Three Keggin-type HPAs were used in this work: 12-phosphotungstic acid, 12-silicotungstic acid, and 12-zincotungstic acid, at doping concentrations of 1 and 5 wt %, respectively. FTIR spectra of the composite membranes clearly show the presence of the HPA and evidence for different interactions under different hydration states. Proton diffusion coefficients were determined by PFGSE NMR under dry and 100 % RH from ambient to 130°C. SAXS patterns of the control PFSA and the HPA-doped PFSA membranes were recorded under dry and wet conditions. Scattering behaviour for different samples and conditions are remarkably different, consistent with the incorporation of HPA and the swelling of ionomer clusters under hydration. copyright The Electrochemical Society.

关键词： Ion exchange membranes

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The effects of process parameters on size, density, structure, and field emission properties of Pd-catalyzed carbon nanotubes synthesized by thermal chemical vapor deposition

The effects of process parameters on size, density, structur...

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International Conference on Vacuum Nanoelectronics (IVNC)

作者： S. Wei W.P. Kang W.H. Hofmeister J.L. Davidson Y.M. Wong J.H. Huang Interdisciplinary Graduate Program in Material Science Vanderbilt University Nashville TN USA Department of Electrical Engineering and Computer Science Vanderbilt University Nashville TN USA Department of Chemical Engineering Vanderbilt University Nashville TN USA Department of Materials Science and Engineering National Tsing Hua University Hsinchu Taiwan

In this study, various thicknesses of Pd catalytic films were deposited on Ti/Si substrates and pretreated with NH/sub 3/. The effects of catalyst deposition parameters and NH/sub 3/ pretreatment time (0, 1, and 10 minutes) on the size distribution of Pd catalytic particles, and subsequently, on the diameter and density of synthesized carbon nanotubes (CNTs) were investigated. The CNTs were synthesized by thermal CVD at 750/spl deg/C using methane (CH/sub 4/) as the carbon source, and a mixture of Ar/H/sub 2/ (80 vol.%/20 vol.%) as the carrier gas.

关键词： Carbon nanotubes chemical vapor deposition Argon Hydrogen Scanning electron microscopy Morphology Substrates materials science and technology Transmission electron microscopy Carbon dioxide

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Synthesis of dipotassium dimethylsilanediolate monohydrate

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Silicon Chemistry 2002年第2期1卷 89-97页

作者： Clarke, Stephen Matisons, Janis G. Owen, Michael J. Graiver, Dan STEP Program – Faculty of Science and Engineering School of Chemistry Physics & Earth Sciences Flinders University of South Australia Adelaide Australia School of Chemistry Physics and Earth Sciences Flinders University Adelaide Australia Nanotechnology Research Group School of Chemistry Physics and Earth Sciences Flinders University Adelaide Australia Department of Material Science and Chemical Engineering Michigan State University Lansing USA

Dipotassium dimethylsilanediolate monohydrate has been synthesised for the first time. The compound has been extensively characterised. The utilization of this new compound as an initiator or monomer in the interfacia...

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Electrospinning of Polymeric Nanofibers: Analysis of Jet Formation

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MRS Online Proceedings Library 2001年第1期661卷 KK5.9.1-KK5.9.6页

作者： Senador, Antonio E. Shaw, Montgomery T. Mather, Patrick T. Chemical Engineering University of Connecticut Storrs USA Polymer Program Institute of Material Science University of Connecticut Storrs USA

Producing nanofiber-diameter polymeric fibers presents an attractive and robust approach toward the processing of nanocomposites, with applications ranging from clear optical components to toughened structural materials. In this work, we are examining the electrospinning process for the production of nanometer-diameter polymer fibers, giving particular attention to the following key features: jet-initiation, fiber architecture, and fiber distribution. A wide range of polymer systems and polymer-solvent combinations were studied in order to broaden the applicability of our conclusions to other systems. Specifically, a dimensional analysis was applied to jet-formation data obtained by quantifying the conditions required for the expulsion of fibers from a charged capillary to a grounded collection plate. The relationships between various dimensionless groups were compared with the expressions for the critical voltage that have been proposed for electrospinning of polymer solutions.

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Structure development and physical properties achieved in the drawing and/or annealing of PEN fibers

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Journal of Polymer Science 2000年第11期38卷

作者： Gang Wu Ming Liu Xiaoning Li John A. Cuculo College of Material Science and Engineering Beijing University of Chemical Technology Beijing 100029 China Department of Fibrous Material Engineering Beijing Institute of Clothing Technology Beijing 100029 China Fiber & Polymer Science Program College of Textiles North Carolina State University Raleigh North Carolina 27695

As-spun poly(ethylene-2,6-naphthalate) (PEN) fibers (i.e., precursors) prepared from high molecular weight polymer were drawn and/or annealed under various conditions. Structure and property variations taking place during the treatment process were followed via wide-angle X-ray scattering (WAXS), small-angle X-ray scattering, differential scanning calorimetry (DSC), and mechanical testing. Both the WAXS and DSC measurements of the cold-drawn samples stretched from a low-speed-spun amorphous fiber indicate that strain-induced crystallization can occur at a temperature below the glass-transition temperature and that the resultant crystal is in the α-form modification. In contrast, when the same precursor was subjected to constrained annealing, its amorphous characteristics remained unchanged even though the annealing was performed at 200 °C. These results may imply that the application of stretching stress is more important than elevated temperatures in producing α-form crystallization. The crystalline structure of the hot-drawn samples depends significantly on the morphology of the precursor fibers. When the precursor was wound at a very low speed and in a predominantly amorphous state, hot drawing induced the formation of crystals that were apparently pure α-form modification. For the β-form crystallized precursors wound at higher speeds, a partial crystalline transition from the β form to the α form was observed during the hot drawing. In contrast with the mechanical properties of the as-spun fibers, those of the hot-drawn products are not improved remarkably because the draw ratio is extremely limited for most as-spun fibers in which an oriented crystalline structure has already formed. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1424–1435, 2000

关键词： poly(ethylene-2,6-naphthalate) fiber drawing annealing structural change crystalline transition

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Improvement of heterologous protein productivity using recombinantYarrowia lipolyticaand cyclic fed‐batch process strategy

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Biotechnology and Bioengineering 2000年第3期59卷

作者： Ching Chuan Chang Dewey D. Y. Ryu Cheon Seok Park Jeong‐Yoon Kim Process Development Division Development Center for Biotechnology 81 Chang‐Hsing Street Taipei Taiwan Republic of China Biochemical Engineering Program Department of Chemical Engineering and Material Science University of California Davis California 95616 Department of Microbiology Chungnam National University Taejon Korea

A cyclic fed‐batch bioprocess is designed and a significant improvement of rice α‐amylase productivity of recombinant Yarrowia lipolytica is illustrated. A bioprocess control strategy developed and reported here entails use of a genetically stable recombinant cloned for heterologous protein, use of optimized media for cell growth and enzyme production phases, and process control strategy enabling high cell‐density culture and high α‐amylase productivity. This process control can be achieved through maintaining a constant optimal specific cell growth rate at a predetermined value (i.e., 0.1 h −1 ), controlling medium feed rate commensurate with the cell growth rate, and maintaining a high cell‐density culture (i.e., 60–70 g/L) for high productivity of cloned heterologous protein. The volumetric enzyme productivity (1,960 units/L · h) achieved from the cyclic fed‐batch process was about 3‐fold higher than that of the fed‐batch culture process (630 units/L · h). © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 59:379–385, 1998.

关键词： recombinant Yarrowia lipolytica heterologous protein expression improvement of rice α‐amylase productivity cyclic fed‐batch culture bioprocess control strategy

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