1,609,941 research outputs found
Three-Leaf Dart-Shaped Single-Crystal BN Formation Promoted by Surface Oxygen
Two-dimensional hexagonal boron nitride (h-BN) single crystals with various
shapes have been synthesized by chemical vapor deposition over the past several
years. Here we report the formation of three-leaf dart (3LD)-shaped single
crystals of h-BN on Cu foil by atmospheric-pressure chemical vapor deposition.
The leaves of the 3LD-shaped h-BN are as long as 18 {\mu}m and their edges are
smooth armchair on one side and stepped armchair on the other. Careful analysis
revealed that surface oxygen plays an important role in the formation of the
3LD shape. Oxygen suppressed h-BN nucleation by passivating Cu surface active
sites and lowered the edge attachment energy, which caused the growth kinetics
to change to a diffusion-controlled mode.Comment: 7 pages,6 figure
-Stars or On Extending a Drawing of a Connected Subgraph
We consider the problem of extending the drawing of a subgraph of a given
plane graph to a drawing of the entire graph using straight-line and polyline
edges. We define the notion of star complexity of a polygon and show that a
drawing of an induced connected subgraph can be extended with at
most bends per edge, where is the
largest star complexity of a face of and is the size of the
largest face of . This result significantly improves the previously known
upper bound of [5] for the case where is connected. We also show
that our bound is worst case optimal up to a small additive constant.
Additionally, we provide an indication of complexity of the problem of testing
whether a star-shaped inner face can be extended to a straight-line drawing of
the graph; this is in contrast to the fact that the same problem is solvable in
linear time for the case of star-shaped outer face [9] and convex inner face
[13].Comment: Appears in the Proceedings of the 26th International Symposium on
Graph Drawing and Network Visualization (GD 2018
Multi-site H-bridge breathers in a DNA--shaped double strand
We investigate the formation process of nonlinear vibrational modes
representing broad H-bridge multi--site breathers in a DNA--shaped double
strand.
Within a network model of the double helix we take individual motions of the
bases within the base pair plane into account. The resulting H-bridge
deformations may be asymmetric with respect to the helix axis. Furthermore the
covalent bonds may be deformed distinctly in the two backbone strands.
Unlike other authors that add different extra terms we limit the interaction
to the hydrogen bonds within each base pair and the covalent bonds along each
strand. In this way we intend to make apparent the effect of the characteristic
helicoidal structure of DNA. We study the energy exchange processes related
with the relaxation dynamics from a non-equilibrium conformation. It is
demonstrated that the twist-opening relaxation dynamics of a radially distorted
double helix attains an equilibrium regime characterized by a multi-site
H-bridge breather.Comment: 27 pages and 10 figure
Wideband L-Probe Fed Inverted Hybrid E-H Microstrip Patch Antennas For IMT-2000 Band
This Paper Presents A Novel Wideband L-Probe Fed Inverted Hybrid E-H Shaped Microstrip Patch Antenna (LIEH) Covering The International Mobile Telecommunications - 2000 (IMT-2000) Band. The Design Adopts Contemporary Techniques; L-Probe Feeding, Inverted Patch Structure With Air-Filled Dielectric, And Slotted Patch. The Composite Effect Of Integrating These Techniques And Introducing The Novel E-H Patch Shaped Offers A Low Profile, Broadband, High Gain,
Low Crosspolarization, And Compact Antenna Element. Measurement Result Showed Satisfactory Performance With An Achievable Bandwidth Of 17.20% At 14 Db Return Loss (SWR = 1.5), Maximum Achievable Gain Of 8 Dbi With 1 Db Gain Variations, And Crosspolarization Level Of 23 Db Below The
Main Lobe Level. The LIEH Patch Has A Compact Dimension Of 79 × 41 Mm2. The Design Is Suitable For Array Applications Especially For IMT-2000 Base Station Antenna
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