scholarly journals Hash Unit Cell Shape Used To Enhancement Gain and Bandwidth of Metasurface Antenna

2020 ◽  
Vol 1664 ◽  
pp. 012022
Author(s):  
Qahtan Mutar Gatea ◽  
Nasr Al-Kafahji ◽  
Faris Mohammed Ali ◽  
Abdulkadhum Jaafar Alyasiri
Keyword(s):  
Cell Shape ◽  
Unit Cell

Relationship between crystal shape and unit cell shape: crystal shape modification via co-crystallization toward SXRD-suitable crystals

CrystEngComm ◽  
2021 ◽  
Author(s):  
Misaki Okayasu ◽  
Shoko Kikkawa ◽  
Hidemasa Hikawa ◽  
Isao Azumaya
Keyword(s):  
Cell Shape ◽  
Unit Cell ◽  
Crystal Shape ◽  
Shape Modification ◽  
Molecular Arrangement ◽  
The Relationship

We demonstrated that crystal shape is related to the unit cell shape and that a molecular arrangement can be altered to a desired employing co-crystallization. We investigated the relationship between...

scholarly journals Effect of unit cell shape and strut size on flexural properties of ordered Copper foam

2019 ◽  
Vol 12 (3) ◽  
Author(s):  
Pulak M Pandey ◽  
Gurminder Singh
Keyword(s):  
Cell Shape ◽  
Flexural Modulus ◽  
Unit Cell ◽  
The Body ◽  
Flexural Properties ◽  
Copper Foam ◽  
Simple Cubic ◽  
Unit Cells ◽  
Cell Shapes ◽  
Different Shapes

The effect of unit cell shape and strut size variation was studied on the flexural properties of the ordered copper foam in the present study. The developed rapid manufacturing method using 3D printing and ultrasonic vibrationassisted pressureless sintering was employed to fabricate samples. Two different shapes such as simple cubic (SC) and body-centred cubic (BCC) were used as the unit cells for the samples with three different strut sizes 1, 1.3 and 1.6 mm. Three-point bend test was performed to obtain the flexural properties such as flexural modulus and ultimate flexural strength. Different shapes of failure curves were noticed during the test, which was owing to the different unit cell shapes. The fracture was obtained to be brittle in nature due to the micro-pores of the struts. The fractured surfaces of the two different unit cells were also studied. The samples with the simple cubic unit cell shapes possessed better flexural properties as compared to the body-centred cubic unit cell samples.

scholarly journals Numerical Evaluation and Prediction of Porous Implant Design and Flow Performance

2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Jian Li ◽  
Diansheng Chen ◽  
Huiqin Luan ◽  
Yingying Zhang ◽  
Yubo Fan
Keyword(s):  
Mass Transfer ◽  
Shear Stress ◽  
Flow Velocity ◽  
Surface Area ◽  
Tissue Regeneration ◽  
Cell Shape ◽  
Control Design ◽  
Unit Cell ◽  
Physical Parameters ◽  
Porous Implant

Porous structure has been widely acknowledged as important factor for mass transfer and tissue regeneration. This study investigates effect of aimed-control design on mass transfer and tissue regeneration of porous implant with regular unit cell. Two shapes of unit cells (Octet truss, and Rhombic dodecahedron) were selected, which have similar symmetrical structure and are commonly used in practice. Through parametric design, porous scaffolds with the strut sizes ofφ0.5, 0.7, 0.9, and 1.1mm were created, respectively. Then using fluid flow simulation method, flow velocity, permeability, and shear stress which could reflect the properties of mass transfer and tissue regeneration were compared and evaluated, and the relationships between porous structure’s physical parameters and flow performance were studied. Results demonstrated that unit cell shape and strut size greatly determine and influence other physical parameters and flow performances of porous implant. With the increasing of strut size, pore size and porosity linearly decrease, but the volume, surface area, and specific surface area increased. Importantly, implant with smaller strut size resulted in smaller flow velocity directly but greater permeability and more appropriate shear stress, which should be beneficial to cell attachment and proliferation. This study confirmed that porous implant with different unit cell shows different performances of mass transfer and tissue regeneration, and unit cell shape and strut size play vital roles in the control design. These findings could facilitate the quantitative assessment and optimization of the porous implant.

Method of obtaining the stable unit-cell shape in the strained superlattice

1994 ◽  
Vol 50 (20) ◽  
pp. 15138-15141
Author(s):  
Takeshi Kurimoto ◽  
Noriaki Hamada
Keyword(s):  
Cell Shape ◽  
Unit Cell ◽  
Stable Unit

The X-Ray Studies on Amorphous Fe78Nb2B20 Alloy

2010 ◽  
Vol 163 ◽  
pp. 239-242
Author(s):  
Małgorzata Karolus
Keyword(s):  
Crystallite Size ◽  
Cell Shape ◽  
Crystalline State ◽  
Amorphous State ◽  
Unit Cell ◽  
Line Broadening ◽  
Unit Cell Parameters ◽  
Hypothetical Model ◽  
X Ray ◽  
Cell Parameters

In this paper there are presented results of structure analyses of the Fe78Nb2B20 amorphous alloy after annealing. Basing on the initial analyses the “hypothetical” model structure was chosen as the combination of different kind of the Fe structure deformations: change of unit cell parameters (change of unit cell shape) and change of line broadening (change of crystallite size). The crystallite size (in meaning of the size of the ordered regions) for the amorphous state is in a range of 7 – 37 Å and for the crystalline state is about of 1100 Å. The comparison of the values of the unit cell parameters shows that the value of the basic – hypothetical unit cell in an amorphous state is bigger of 0.2 Å than in a crystalline state. After crystallisation there are detected Fe and Fe3B phases.

High-resolution structure determination by ALCHEMI

1983 ◽  
Vol 41 ◽  
pp. 178-181 ◽  
Author(s):  
Peter G. Self ◽  
Peter R. Buseck
Keyword(s):  
Site Occupancy ◽  
Real Space ◽  
Unit Cell ◽  
Bragg Angle ◽  
Electron Current ◽  
High Resolution Structure ◽  
Beam Incident ◽  
Crystallographic Planes ◽  
Electron Beam Incident ◽  
Resolution Structure

ALCHEMI (Atom Location by CHanneling Enhanced Microanalysis) enables the site occupancy of atoms in single crystals to be determined. In this article the fundamentals of the method for both EDS and EELS will be discussed. Unlike HRTEM, ALCHEMI does not place stringent resolution requirements on the microscope and, because EDS clearly distinguishes between elements of similar atomic number, it can offer some advantages over HRTEM. It does however, place certain constraints on the crystal. These constraints are: a) the sites of interest must lie on alternate crystallographic planes, b) the projected charge density on the alternate planes must be significantly different, and c) there must be at least one atomic species that lies solely on one of the planes.An electron beam incident on a crystal undergoes elastic scattering; in reciprocal space this is seen as a diffraction pattern and in real space this is a modulation of the electron current across the unit cell. When diffraction is strong (i.e., when the crystal is oriented near to the Bragg angle of a low-order reflection) the electron current at one point in the unit cell will differ significantly from that at another point.

The External Shape of Human γ GI Immunoglobulin from Crystal Sections

1971 ◽  
Vol 29 ◽  
pp. 428-429
Author(s):  
L. W. Labaw
Keyword(s):  
Molecular Weight ◽  
Sodium Phosphate ◽  
Osmium Tetroxide ◽  
Unit Cell ◽  
Monoclinic Space Group ◽  
X Ray ◽  
Large Molecular Weight ◽  
Cell Dimensions ◽  
Unit Cell Dimensions ◽  
Crystallographic Axes

Crystals of a human γGl immunoglobulin have the external morphology of diamond shaped prisms. X-ray studies have shown them to be monoclinic, space group C2, with 2 molecules per unit cell. The unit cell dimensions are a = 194.1, b = 91.7, c = 51.6Å, 8 = 102°. The relatively large molecular weight of 151,000 and these unit cell dimensions made this a promising crystal to study in the EM.Crystals similar to those used in the x-ray studies were fixed at 5°C for three weeks in a solution of mother liquor containing 5 x 10-5M sodium phosphate, pH 7.0, and 0.03% glutaraldehyde. They were postfixed with 1% osmium tetroxide for 15 min. and embedded in Maraglas the usual way. Sections were cut perpendicular to the three crystallographic axes. Such a section cut with its plane perpendicular to the z direction is shown in Fig. 1.This projection of the crystal in the z direction shows periodicities in at least four different directions but these are only seen clearly by sighting obliquely along the micrograph.

The orientation of sickle hemoglobin fibers within fascicles

1988 ◽  
Vol 46 ◽  
pp. 400-401
Author(s):  
Christopher A. Miller ◽  
Bridget Carragher ◽  
William A. McDade ◽  
Robert Josephs
Keyword(s):  
Sickle Cell ◽  
Sickle Cell Anemia ◽  
Relative Orientation ◽  
Unit Cell ◽  
Red Cell ◽  
High Ph ◽  
Sickle Hemoglobin ◽  
Polar Crystal ◽  
Helical Configuration

Highly ordered bundles of deoxyhemoglobin S (HbS) fibers, termed fascicles, are intermediates in the high pH crystallization pathway of HbS. These fibers consist of 7 Wishner-Love double strands in a helical configuration. Since each double strand has a polarity, the odd number of double strands in the fiber imparts a net polarity to the structure. HbS crystals have a unit cell containing two double strands, one of each polarity, resulting in a net polarity of zero. Therefore a rearrangement of the double strands must occur to form a non-polar crystal from the polar fibers. To determine the role of fascicles as an intermediate in the crystallization pathway it is important to understand the relative orientation of fibers within fascicles. Furthermore, an understanding of fascicle structure may have implications for the design of potential sickling inhibitors, since it is bundles of fibers which cause the red cell distortion responsible for the vaso-occlusive complications characteristic of sickle cell anemia.

Kinematical and Dynamical CBED Pattern Models: Increasing the Accuracy of the Unit-Cell Parameter Measurements Based on CBED Patterns

1990 ◽  
Vol 48 (2) ◽  
pp. 540-541
Author(s):  
I.N. Yadhikov ◽  
S.K. Maksimov
Keyword(s):  
Reciprocal Lattice ◽  
Unit Cell ◽  
Reciprocal Lattice Vector ◽  
Unit Cell Parameters ◽  
Lattice Vector ◽  
Cell Parameters ◽  
Accuracy Of Measurements ◽  
The Difference ◽  
Image Position ◽  
Convergent Beam

Convergent beam electron diffraction (CBED) is widely used as a microanalysis tool. By the relative position of HOLZ-lines (Higher Order Laue Zone) in CBED-patterns one can determine the unit cell parameters with a high accuracy up to 0.1%. For this purpose, maps of HOLZ-lines are simulated with the help of a computer so that the best matching of maps with experimental CBED-pattern should be reached. In maps, HOLZ-lines are approximated, as a rule, by straight lines. The actual HOLZ-lines, however, are different from the straights. If we decrease accelerating voltage, the difference is increased and, thus, the accuracy of the unit cell parameters determination by the method becomes lower.To improve the accuracy of measurements it is necessary to give up the HOLZ-lines substitution by the straights. According to the kinematical theory a HOLZ-line is merely a fragment of ellipse arc described by the parametric equationwith arc corresponding to change of β parameter from -90° to +90°, wherevector, h - the distance between Laue zones, g - the value of the reciprocal lattice vector, g‖ - the value of the reciprocal lattice vector projection on zero Laue zone.

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