scholarly journals Effective Relative Permittivity Determination of 3D Printed Artificial Dielectric Substrates Based on a Cross Unit Cell

2021 ◽  
Vol 30 (4) ◽  
pp. 595-610
Author(s):  
P. Kadera ◽  
J. Lacik ◽  
H. Arthaber
1990 ◽  
Vol 55 (4) ◽  
pp. 1010-1014 ◽  
Author(s):  
Jiří Kameníček ◽  
Richard Pastorek ◽  
František Březina ◽  
Bohumil Kratochvíl ◽  
Zdeněk Trávníček

The crystal and molecular structure of the title compound (C8H16N2NiS4) was solved by the heavy atom method and the structure was refined anisotropically to a final R factor of R = 0.029 (wR = 0.037) for 715 observed reflections. The crystal is monoclinic, space group P21/c with a = 948.3(2), b = 776.9(2), c = 1 167.4(2) pm, β = 125.14(2)°, Z = 2. The molecule contains two four-membered NiSCS rings of approximately planar configuration with the Ni atom situated at a centre of symmetry. The molecules are arranged in chains along the c-axis of the unit cell.


Machines ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 150
Author(s):  
Andrei Marius Mihalache ◽  
Gheorghe Nagîț ◽  
Laurențiu Slătineanu ◽  
Adelina Hrițuc ◽  
Angelos Markopoulos ◽  
...  

3D printing is a process that has become widely used in recent years, allowing the production of parts with relatively complicated shapes from metallic and non-metallic materials. In some cases, it is challenging to evaluate the ability of 3D printers to make fine details of parts. For such an assessment, the printing of samples showing intersections of surfaces with low angle values was considered. An experimental plan was designed and materialized to highlight the influence of different factors, such as the thickness of the deposited material layer, the printing speed, the cooling and filling conditions of the 3D-printed part, and the thickness of the sample. Samples using areas in the form of isosceles triangles with constant height or bases with the same length, respectively, were used. The mathematical processing of the experimental results allowed the determination of empirical mathematical models of the power-function type. It allowed the detection of both the direction of actions and the intensity of the influence exerted by the input factors. It is concluded that the strongest influence on the printer’s ability to produce fine detail, from the point of view addressed in the paper, is exerted by the vertex angle, whose reduction leads to a decrease in printing accuracy.


1984 ◽  
Vol 19 (1) ◽  
pp. K1-K3 ◽  
Author(s):  
H. Fichtner-Schmittler ◽  
U. Lohse ◽  
G. Engelhardt ◽  
V. Patzelová

1999 ◽  
Vol 55 (6) ◽  
pp. 975-983 ◽  
Author(s):  
M. Quiquandon ◽  
A. Katz ◽  
F. Puyraimond ◽  
D. Gratias

It is well known that the crystallography of approximants is directly related to that of the parent quasicrystal, once its unit-cell vectors are identified as parallel projections of certain N-dimensional lattice nodes {\bf A}^{i}. Derived here are explicit simple relations for calculating the shear matrices {\boldvarepsilon} and the related crystallographic properties of the corresponding approximants, including diffraction indexing and the determination of the lattice in perpendicular space. Applied to low-dimensional approximants, the derivation shows that the systematic `accidental' extinction rules observed in the pentagonal phases are generic extinctions that are due to the geometrical properties of the projected 1D lattice and are independent of the actual model of the quasicrystal.


2016 ◽  
Vol 8 (48) ◽  
pp. 32940-32947 ◽  
Author(s):  
Ying Hong ◽  
Meiyan Wu ◽  
Guangwei Chen ◽  
Ziyang Dai ◽  
Yizhou Zhang ◽  
...  

2009 ◽  
Vol 42 (2) ◽  
pp. 259-264 ◽  
Author(s):  
Xinguo Hong ◽  
Quan Hao

Solving the phase problem remains central to crystallographic structure determination. A six-dimensional search method of molecular replacement (FSEARCH) can be used to locate a low-resolution molecular envelope determined from small-angle X-ray scattering (SAXS) within the crystallographic unit cell. This method has now been applied using the higher-resolution envelope provided by combining SAXS and WAXS (wide-angle X-ray scattering) data. The method was tested on horse hemoglobin, using the most probable model selected from a set of a dozen bead models constructed from SAXS/WAXS data using the programGASBORat 5 Å resolution (qmax= 1.25 Å−1) to phase a set of single-crystal diffraction data. It was found that inclusion of WAXS data is essential for correctly locating the molecular envelope in the crystal unit cell, as well as for locating heavy-atom sites. An anomalous difference map was calculated using phases out to 8 Å resolution from the correctly positioned envelope; four distinct peaks at the 3.2σ level were identified, which agree well with the four iron sites of the known structure (Protein Data Bank code 1ns9). In contrast, no peaks could be found close to the iron sites if the molecular envelope was constructed using the data from SAXS alone (qmax= 0.25 Å−1). The initial phases can be used as a starting point for a variety of phase-extension techniques, successful application of which will result in complete phasing of a crystallographic data set and determination of the internal structure of a macromolecule to atomic resolution. It is anticipated that the combination ofFSEARCHand WAXS techniques will facilitate the initial structure determination of proteins and provide a good foundation for further structure refinement.


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