hexagonal form
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2021 ◽  
Author(s):  
B. Khandsuren ◽  
J. Prokisch

AbstractIn recent years, the importance of nanomaterials in food science, medicine, etc. has been increasing quickly. Herein, organic and inorganic red selenium nanoparticles synthesised by the reduction of sodium selenite with chemical and biological reducing agents. Grey hexagonal form in aqueous and powder was assembled at a high temperature of 85 °C for 10 min. Also, selenium enriched yogurt powder was made that contained about 2,000 mg kg−1 selenium, 93.8% of which is in nano form with a size of 50–500 nm. The synthesised nanoparticles were characterised by Dynamic Light Scattering Particle Size Analyzer (DLS), X-ray Diffraction Analysis (XRD), Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM). The prepared SeNPs could be promising additive for a wide range of applications.


2018 ◽  
Vol 51 (5) ◽  
pp. 1467-1473 ◽  
Author(s):  
Masayuki Okugawa ◽  
Ryusuke Nakamura ◽  
Akihiko Hirata ◽  
Manabu Ishimaru ◽  
Hidehiro Yasuda ◽  
...  

Pristine thin films of amorphous Ge prepared by sputtering are unstable and form coarse crystalline particles of 100 nm in size upon crystallization by electron irradiation. These crystalline particles exhibit unusual diffraction patterns that cannot be understood from the diamond cubic structure. The structure has previously been assumed to be a metastable hexagonal form. In the present work, the structure of the coarse crystalline particles has been analysed in detail by transmission electron microscopy, considering the possibility that those diffraction patterns might occur with the diamond cubic structure if the particle consists of thin twin layers. By high-resolution lattice imaging the particles have been shown to be of the diamond cubic structure containing a high density of twins and stacking faults parallel to {111}. With such defects, diffraction patterns can be complex because of the following effects: superposition of two or more diffraction patterns of the same structure but of different orientations, double diffraction through twin crystals, and streaks parallel to the thin crystal which give rise to extra diffraction spots. It is found that diffraction patterns taken from various orientations can be explained in terms of these effects.


2017 ◽  
Vol 139 (5) ◽  
Author(s):  
Farhad Farzbod

Periodic structures have interesting acoustic and vibration properties making them suitable for a wide variety of applications. In a periodic structure, the number of frequencies for each wavevector depends on the degrees-of-freedom of the unit cell. In this paper, we study the number of wavevectors available at each frequency in a band diagram. This analysis defines the upper bound for the maximum number of wavevectors for each frequency in a general periodic structure which might include damping. Investigation presented in this paper can also provide an insight for designing materials in which the interaction between unit cells is not limited to the closest neighbor. As an example application of this work, we investigate phonon dispersion curves in hexagonal form of boron nitride to show that first neighbor interaction is not sufficient to model dispersion curves with force-constant model.


2016 ◽  
Vol 56 (5) ◽  
pp. 409-416 ◽  
Author(s):  
Wei Wen ◽  
Siamak Khatibi

The current camera has made a huge progress in the sensor resolution and the lowluminance performance. However, we are still far from having an optimal camera as powerful as our eye is. The study of the evolution process of our visual system indicates attention to two major issues: the form and the density of the sensor. High contrast and optimal sampling properties of our visual spatial arrangement are related directly to the densely hexagonal form. In this paper, we propose a novel software-based method to create images on a compact dense hexagonal grid, derived from a simulated square sensor array by a virtual increase of the fill factor and a half a pixel shifting. After that, the orbit functions are proposed for a hexagonal image processing. The results show it is possible to achieve an image processing in the orbit domain and the generated hexagonal images are superior, in detection of curvature edges, to the square images. We believe that the orbit domain image processing has a great potential to be the standard processing for hexagonal images.


Author(s):  
Manel Sonni ◽  
Riadh Marzouki ◽  
Mohamed Faouzi Zid ◽  
Amira Souilem

The title compound, nonasodium chromium(III) hexakis[molybdate(VI)], β-Na9CrMo6O24, was prepared by solid-state reactions. This alluaudite-type structure is constituted of infinite layers formed by links betweenM2O10(M= C/Na) dimers and MoO4tetrahedra. The Na+and Cr3+cations are located in the same site with, respectively, 0.25 and 0.75 occupancies. The layers are connected to each other through MoO4sharing corners, resulting an in open three-dimensional framework with hexagonal-form cavities occupied by Na+cations. The proposed structural model is supported by charge-distribution (CHARDI) and bond-valence-sum (BVS) analysis. All atoms are on general positions except for one Mo, two Na (site symmetry 2) and another Na site (site symmetry -1). A comparison is made with the similar structures Na4Co(MoO4)3, Na2Ni(MoO4)2, Cu1.35Fe3(PO4)3and NaAgFeMn2(PO4)3.


2015 ◽  
Vol 63 (1) ◽  
Author(s):  
Paweł Strzelczyk ◽  
Grzegorz D Bujacz ◽  
Piotr Kiełbasiński ◽  
Jarosław Błaszczyk

During crystallization screenings of commercially available hydrolytic enzymes, the new, hexagonal crystal form of CAL-B, has been discovered and hereby reported. The NAG molecules, which were closing the glycosylation site in the orthorhombic form, in hexagonal structure make the glycosylation site open. It is unknown whether the opening and closing of the glycosylation site by the 'lid' NAG molecules, could be related to the opening and closing of the active center of the enzyme upon substrate binding and product release.


2015 ◽  
Vol 34 (3_suppl) ◽  
pp. 53S-60S ◽  
Author(s):  
Monice M. Fiume ◽  
Wilma F. Bergfeld ◽  
Donald V. Belsito ◽  
Ronald A. Hill ◽  
Curtis D. Klaassen ◽  
...  

The Cosmetic Ingredient Review Expert Panel (Panel) assessed the safety of boron nitride which functions in cosmetics as a slip modifier (ie, it has a lubricating effect). Boron nitride is an inorganic compound with a crystalline form that can be hexagonal, spherical, or cubic; the hexagonal form is presumed to be used in cosmetics. The highest reported concentration of use of boron nitride is 25% in eye shadow formulations. Although boron nitride nanotubes are produced, boron nitride is not listed as a nanomaterial used in cosmetic formulations. The Panel reviewed available chemistry, animal data, and clinical data and concluded that this ingredient is safe in the present practices of use and concentration in cosmetic formulations.


2015 ◽  
Vol 2015 (CICMT) ◽  
pp. 000282-000286
Author(s):  
Jaroslaw Kita ◽  
Annica Brandenburg ◽  
Irina Sudina ◽  
Ralf Moos

This contribution shows results of 3D-shaping experiments of ceramic tapes. The structures were made by wrapping structured tapes around a hexagonal alumina rod. After lamination, the rod was removed and the structure was finally fired, similarly as reported in [1]. One out of many possible applications of such structures is a miniaturized furnace for sintering of critical materials, which could contaminate expensive chamber furnaces, for tempering of single gas sensors, or for fast heating at controlled rate. While LTCC technology can be applied only up to 600–700 °C, application of HTCC tapes can extend temperature range to above 1000 °C. Therefore, 99.99% alumina tape (ESL 44007) was used. The here-shown miniaturized furnace has a hexagonal form. For a proper temperature distribution in the furnace chamber, the furnace was equipped with six platinum heaters that can be controlled independently. Finite Elements Analysis (FEM) supported the design process. The paper discusses manufacturing route, beginning with a design process supported by FEM through 3D-shaping by wrapping structured tapes around an alumina rod and finally firing and functionality tests.


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