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Anisotropic Growth (anisotropic + growth)

Distribution by Scientific Domains
Polymers and Materials Science57%

Selected Abstracts

Growth of Diamond Nanoplatelets by CVD,

CHEMICAL VAPOR DEPOSITION, Issue 7-8 2008
Hou-Guang Chen
Abstract Hexagonal, single-crystalline, diamond nanoplatelets synthesized by microwave plasma (MP)CVD on Au-Ge alloy and nanocrystalline diamond (nc-diamond) film substrates, respectively, are reported. On the nc-diamond matrix, hexagonal diamond nanoplatelets can grow to a thickness of as little as approximately 10,nm. The effects of various processing parameters, such as methane concentration, microwave power, and gas pressure, on the growth of diamond nanoplatelets are explored. High-resolution transmission electron microscopy (HRTEM) reveals that the diamond nanoplatelets contain multi-parallel twins, and the side faces of the platelets exhibit {100}/{111} ridge-and-trough structure. Anisotropic growth of diamond nanoplatelet is believed to result from the side face structure of the twinned platelets and intensive plasma reaction. [source]

Synthesis and Structural Characterization of Branched Palladium Nanostructures

ADVANCED MATERIALS, Issue 22 2009
John Watt
The controlled formation of branched palladium nanostructures has been performed using a simple reaction procedure carried out at room temperature. Structural characterization of an as-synthesized palladium tripod gives an insight into anisotropic growth occurring from highly symmetrical face centered cubic crystal structures. [source]

Single-Catalyst Confined Growth of ZnS/Si Composite Nanowires,

ADVANCED MATERIALS, Issue 2 2005
J. Zhan
Side-by-side ZnS/Si composite nanowires have been prepared by tin-catalyst confined growth. Simultaneous thermal evaporation of ZnS and Si powders provides precursor vapors that condense on metallic Sn droplets, resulting in the nucleation and anisotropic growth of composite nanowires made of adjacent ZnS and Si domains (see Figure). The diameters of composite nanowires can reach as low as 15,nm. [source]

The initiation and development of metamorphic foliation in the Otago Schist, Part 1: competitive oriented growth of white mica

JOURNAL OF METAMORPHIC GEOLOGY, Issue 6 2005
A. STALLARD
Abstract The 3D shape, size and orientation data for white mica grains sampled along two transects of increasing metamorphic grade in the Otago Schist, New Zealand, reveal that metamorphic foliation, as defined by mica shape-preferred orientation (SPO), developed rapidly at sub-greenschist facies conditions early in the deformation history. The onset of penetrative strain metamorphism is marked by the rapid elimination of poorly oriented large clastic mica in favour of numerous new smaller grains of contrasting composition, higher aspect ratios and a strong preferred orientation. The metamorphic mica is blade shaped with long axes defining the linear aspect of the foliation and intermediate axes a partial girdle about the lineation. Once initiated, foliation progressively intensified by an increase in the aspect ratio, size and alignment of grains, although highest grade samples within the chlorite zone record a decrease in aspect ratio and reduction in SPO strength despite continued increase in grain size. These trends are interpreted in terms of progressive competitive anisotropic growth of blade-shaped grains so that the fastest growth directions and blade lengths tend to parallel the extension direction during deformation. The competitive nature of mica growth is indicated by the progressive increase in size and resultant decrease in number of metamorphic mica with increasing grade, from c. 1000 relatively small mica grains per square millimetre of thin section at lower grades, to c. 100 relatively large grains per square millimetre in higher grade samples. Reversal of SPO intensity and grain aspect ratio trends in higher grade samples may reflect a reduction in the strain rate or reduction in the deviatoric component of the stress field. [source]

Development of an in situ polarization-dependent total-reflection fluorescence XAFS measurement system

JOURNAL OF SYNCHROTRON RADIATION, Issue 2 2001
Wang-Jae Chun
An in situ polarization-dependent total-reflection fluorescence X-ray absorption fine structure (PTRF-XAFS) spectroscopy system has been developed, which enables PTRF-XAFS experiments to be performed in three different orientations at various temperatures (273,600,K) and pressures (10,10,760,torr). The system consists of a measurement chamber and a preparation chamber. The measurement chamber has a high-precision six-axis goniometer and a multi-element solid-state detector. Using a transfer chamber, also operated under ultra-high-vacuum conditions, the sample can be transferred to the measurement chamber from the preparation chamber, which possesses low-energy electron diffraction, Auger electron spectroscopy and X-ray photoelectron spectroscopy facilities, as well as a sputtering gun and an annealing system. The in situ PTRF-EXAFS for Cu species on TiO2 (110) has been measured in three different orientations, revealing anisotropic growth of Cu under the influence of the TiO2 (110) surface. [source]

Direct Formation of Crystalline Gadolinium-Doped Ceria Powder via Polymerized Precursor Solution

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 7 2002
Shuqiang Wang
Synthesis of Ce0.9Gd0.1O1.95 (CGO) powder from a polymeric precursor solution containing a mixture of nitrates, nitric acid, and ethylene glycol was investigated with emphasis on the effect of polymerization of the precursor solution on the crystallization and morphology of the derived solid intermediate and the final oxide powder. It is shown for the first time in this work that the solid intermediate derived from the polymerized solution is present in the form of well-crystallized cerium-gadolinium formate solid solution, Ce1,xGdx(HCOO)3, exhibiting anisotropic growth. Further polymerization of the precursor solution resulted in the direct formation of loosely agglomerated nanoscaled CGO oxide powder from the polymerized solution at temperatures as low as 130°C. [source]

Mum, this bud's for you: Where do you want it? roles for Cdc42 in controlling bud site selection in Saccharomyces cerevisiae

BIOESSAYS, Issue 9 2003
W. James Nelson
The generation of asymmetric cell shapes is a recurring theme in biology. In budding yeast, one form of cell asymmetry occurs for division and is generated by anisotropic growth of the mother cell to form a daughter cell bud. Previous genetic studies uncovered key roles for the small GTPase Cdc42 in organizing the actin cytoskeleton and vesicle delivery to the site of bud growth,1,2 but a recent paper has also raised questions about how control of Cdc42 activity is integrated into a proposed hierarchical regulatory pathway that specifies a unique site of bud formation.3 BioEssays 25:833,836, 2003. © 2003 Wiley Periodicals, Inc. [source]