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Shape Control (shape + control)

Distribution by Scientific Domains

Polymers and Materials Science	66%
Information Science and Computing	16%
Chemistry	16%

Selected Abstracts

Nanocrystal Shape Control: Synthesis and Structure,Property Correlation in Shape-Controlled ZnO Nanoparticles Prepared by Chemical Vapor Synthesis and their Application in Dye-Sensitized Solar Cells (Adv. Funct.

ADVANCED FUNCTIONAL MATERIALS, Issue 6 2009
Mater.
Chemical vapor synthesis is a convenient one-step synthesis process for the production of nanocrystalline powders. On page 875, Bacsa et al. report that by controlled variation of experimental parameters, tetrapods (as in image) or spherical ZnO nanocrystals can be selectively obtained directly from Zn metal precursor. Shape control leads to improved optical properties and a better performance when applied as electrodes in dye sensitized solar cells. [source]

Graphene Shape Control by Multistage Cutting and Transfer

ADVANCED MATERIALS, Issue 44 2009
Lijie Ci
Cutting graphene by a catalytic hydrogenation process can generate graphene pieces with smooth edges of atomic precision and well-defined shapes. Controlled cutting of graphene by creating graphene step edges by oxidation or plasma etching is demonstrated. A combination of cutting, transfer, and lithography is shown to allow the fabrication of isolated graphene devices with specific edge and shape control. [source]

Anisotropic Shape Control of Colloidal Inorganic Nanocrystals,

ADVANCED MATERIALS, Issue 5 2003
S.-M. Lee
Abstract The systematic shape control of colloidal nanocrystals including one-dimensional (1D) nanorods remains a key issue in the "bottom,up" approach of nanoscience. Here, we examine the anisotropic structural evolution of various semiconductor nanocrystals and systematically elucidate the key growth parameters for their shape control. The crystalline phase of nucleating seeds and kinetic growth regimes controlled by changing growth parameters are crucial for the determination of the 1D nanocrystal geometry. [source]

Recrystallization and Shape Control of Crystals of the Organic Dye Acid Green 27 in a Mixed Solvent

CHEMISTRY - A EUROPEAN JOURNAL, Issue 5 2007
Huai-Ping Cong
Abstract Recrystallization of the unstructured dye acid green 27 (AG27) in a mixed solvent of alcohol (ethanol or methanol) and water was systematically studied. The results demonstrated that AG27 crystals with uniform sizes and controllable shapes can be produced by simply changing the volume ratio of ethanol (or methanol) and deionized water (DIW). Rodlike and shuttlelike AG27 crystals can be selectively synthesized. The XRD analyses revealed the periodic structures of the organic crystals. Furthermore, crystallization in another mixed solvent of N,N -dimethylformamide (DMF) and DIW results in the formation of longer fibers with high aspect ratio, which further validates the remarkable effects of mixed solvent on the shape of the AG27 crystals. This method of recrystallization in a mixed solvent is expected to facilitate the synthesis of other functional organic crystals with unusual shapes. [source]

Stylized lighting for cartoon shader

COMPUTER ANIMATION AND VIRTUAL WORLDS (PREV: JNL OF VISUALISATION & COMPUTER ANIMATION), Issue 2-3 2009
Hideki Todo
Abstract In the context of non-photorealistic imaging, such as digital cel animation, lighting is symbolic and stylized to depict the scene's mood and the geometric or physical features of the objects in the scene. Stylized light and shade should therefore be intentionally animated rather than rigorously simulated. However, it is difficult to achieve smooth animation of light and shade that are stylized with a user's intention, because such stylization cannot be achieved using just conventional 3D lighting. To address this problem, we propose a 3D stylized lighting method, focusing on several stylized effects including straight lighting, edge lighting, and detail lighting which are important features in hand-drawn cartoon animation. Our method is an extension of the conventional cartoon shader and introduces a light coordinate system for light shape control with smooth animations of light and shade. We also extend a toon mapping process for detailed feature lighting. Having these algorithms in a real-time cartoon shader, our prototype system allows the interactive creation of stylized lighting animations. We show several animation results obtained by our method to illustrate usefulness and effectiveness of our method. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Geodesic-Controlled Developable Surfaces for Modeling Paper Bending

COMPUTER GRAPHICS FORUM, Issue 3 2007
Pengbo Bo
Abstract We present a novel and effective method for modeling a developable surface to simulate paper bending in interactive and animation applications. The method exploits the representation of a developable surface as the envelope of rectifying planes of a curve in 3D, which is therefore necessarily a geodesic on the surface. We manipulate the geodesic to provide intuitive shape control for modeling paper bending. Our method ensures a natural continuous isometric deformation from a piece of bent paper to its flat state without any stretching. Test examples show that the new scheme is fast, accurate, and easy to use, thus providing an effective approach to interactive paper bending. We also show how to handle non-convex piecewise smooth developable surfaces. [source]

Benzylamines as Versatile Agents for the One-Pot Synthesis and Highly Ordered Stacking of Anatase Nanoplatelets

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 6 2008
Georg Garnweitner
Abstract The simple reaction of titanium isopropoxide in benzylamine is shown to lead to remarkably complex, highly ordered hybrid structures. These structures consist of anatase nanoplatelets that were stacked in a lamellar fashion with a small organic layer in between. By careful characterization of these structures, we show that indeed solely the benzylamine solvent is present in the organic moiety between the nanocrystals, which thereby provides both shape control and alignment of the inorganic crystals. The solvent also plays a central role during the anatase formation itself; hence, it enacts control on the forming materials on a multitude of levels.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source]

PY181 Pigment Microspheres of Nanoplates Synthesized via Polymer-Induced Liquid Precursors

ADVANCED FUNCTIONAL MATERIALS, Issue 13 2009
Yurong Ma
Abstract Organic pigments are important crystalline substances, and their properties and applications rely on size and shape control. Pigment Yellow 181 (PY181) is an industrial azo pigment that is light and weatherfast and suitable for high temperature processing. One disadvantage is its needle-like shape in the default , -phase, which makes the pigment difficult to process in industry, e.g., in polymer melts, where a spherical structure would be ideal. Here, we show for the first time, that polymer-induced liquid precursor structures can be formed even in association to a chemical reaction. Furthermore, it is demonstrated that biomineralization principles can be exploited for the generation of advanced functional materials, such as pigments with novel complex morphology and different properties. Stable PY181 microspheres of nanoplates in the , -phase were obtained in mixed solvents of water and isopropanol by direct azo coupling under the directing influence of a designed copolymer additive aminobenzoylaminobenzamide-acetoacetyl-poly(ethylene imine)- block -poly(ethylene glycol) (ABABA-acetoacetyl-PEI- b -PEG). [source]

Fabrication and Electromechanical Characterization of a Piezoelectric Structural Fiber for Multifunctional Composites

ADVANCED FUNCTIONAL MATERIALS, Issue 4 2009
Yirong Lin
Abstract The use of piezoceramic materials for structural sensing and actuation is a fairly well developed practice that has found use in a wide variety of applications. However, just as advanced composites offer numerous benefits over traditional engineering materials for structural design, actuators that utilize the active properties of piezoelectric fibers can improve upon many of the limitations encountered when using monolithic piezoceramic devices. Several new piezoelectric fiber composites have been developed; however, almost all studies have implemented these devices such that they are surface-bonded patches used for sensing or actuation. This paper will introduce a novel active piezoelectric structural fiber that can be laid up in a composite material to perform sensing and actuation, in addition to providing load bearing functionality. The sensing and actuation aspects of this multifunctional material will allow composites to be designed with numerous embedded functions, including structural health monitoring, power generation, vibration sensing and control, damping, and shape control through anisotropic actuation. This effort has developed a set of manufacturing techniques to fabricate the multifunctional fiber using a SiC fiber core and a BaTiO3 piezoelectric shell. The electromechanical coupling of the fiber is characterized using an atomic force microscope for various aspect ratios and is compared to predictions made using finite element modeling in ABAQUS. The results show good agreement between the finite element analysis model and indicate that the fibers could have coupling values as high as 68% of the active constituent used. [source]

Shape-Controlled Synthesis of Pd Nanocrystals in Aqueous Solutions

ADVANCED FUNCTIONAL MATERIALS, Issue 2 2009
Byungkwon Lim
Abstract This article provides an overview of recent developments regarding synthesis of Pd nanocrystals with well-controlled shapes in aqueous solutions. In a solution-phase synthesis, the final shape taken by a nanocrystal is determined by the twin structures of seeds and the growth rates of different crystallographic facets. Here, the maneuvering of these factors in an aqueous system to achieve shape control for Pd nanocrystals is discussed. L -ascorbic acid, citric acid, and poly(vinyl pyrrolidone) are tested for manipulating the reduction kinetics, with citric acid and Br, ions used as capping agents to selectively promote the formation of {111} and {100} facets, respectively. The distribution of single-crystal versus multiple-twinned seeds can be further manipulated by employing or blocking oxidative etching. The shapes obtained for the Pd nanocrystals include truncated octahedron, icosahedron, octahedron, decahedron, hexagonal and triangular plates, rectangular bar, and cube. The ability to control the shape of Pd nanocrystals provides a great opportunity to systematically investigate their catalytic, electrical, and plasmonic properties. [source]