scholarly journals Исследование упругих свойств пленок SiC, синтезированных на подложках Si методом замещения атомов

2019 ◽  
Vol 61 (12) ◽  
pp. 2313
Author(s):  
А.С. Гращенко ◽  
С.А. Кукушкин ◽  
А.В. Осипов
Keyword(s):  
Silicon Carbide ◽  
Young’S Modulus ◽  
Elastic Properties ◽  
Silicon Substrate ◽  
Structural Characteristics ◽  
Optical Profilometry ◽  
Spectral Ellipsometry ◽  
Silicon Carbide Film ◽  
Film Roughness ◽  
First Time

The elastic properties of a nanoscale film of silicon carbide grown on a silicon substrate by atom substitution are studied. For the first time, the Young's modulus of nanoscale silicon carbide was measured by nanoindentation. Using optical profilometry and spectral ellipsometry, the structural characteristics of a silicon carbide film on silicon were studied, namely, the film roughness and its thickness were calculated.

scholarly journals MBE growth and structural properties of InAs and InGaAs nanowires with different mole fraction of In on Si and strongly mismatched SiC/Si(111) substrates

2018 ◽  
Vol 52 (5) ◽  
pp. 522
Author(s):  
R.R. Reznik ◽  
K.P. Kotlyar ◽  
I.P. Soshnikov ◽  
S.A. Kukushkin ◽  
A.V. Osipov ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Buffer Layer ◽  
Structural Properties ◽  
Mole Fraction ◽  
Silicon Substrate ◽  
Mbe Growth ◽  
Inas Nanowires ◽  
First Time

AbstractThe possibility of InAs nanowires MBE growth on silicon (111) substrates with a nanometer buffer layer of silicon carbide has been demonstrated for the first time. The NWs diameter turned out to be smaller than on the silicon substrate—the minimum of NWs diameter was less than 10 nm. In addition, dependence of structural properties of InGaAs nanowires on composition was studied.

scholarly journals Исследование методом наноиндентирования твердости и модуля Юнга в тонких приповерхностных слоях карбида кремния со стороны Si- и C-граней

2020 ◽  
Vol 46 (15) ◽  
pp. 36
Author(s):  
А.В. Осипов ◽  
А.С. Гращенко ◽  
А.Н. Горляк ◽  
А.О. Лебедев ◽  
В.В. Лучинин ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Surface Energy ◽  
Young’S Modulus ◽  
Elastic Properties ◽  
Young's Modulus ◽  
Surface Layers ◽  
Penetration Depths

This paper presents the results of a nanoindentation study of the hardness and Young’s modulus of hexagonal silicon carbide SiC-4H, obtained by the modified Lely method, in thin surface layers near the C-terminated and Si-terminated faces at small penetration depths of the indenter. It is shown that differences in the elastic properties and hardness of SiC propagate from the surface into the crystal to a depth of about 60 nm. The Young's modulus at the C-terminated face practically coincides with the Young's modulus of the bulk SiC-4H sample (~ 400 GPa), which is approximately 2.3 times higher than the Young's modulus at the Si-terminated face at a depth of 0 to 35 nm (~ 170 GPa). The value of the SiC hardness is approximately 1.5 times higher at the surface of the C-terminated face than at the Si-terminated face, on average, at a depth of 0 to 60 nm. It is concluded from the obtained data that the surface energy of the C-terminated face is also approximately 1.5 times higher than the surface energy of the Si-terminated face since a new surface is formed upon deformation or cracking of the crystal

scholarly journals Micro alloying of SiC by radioisotope

2019 ◽  
Vol 222 ◽  
pp. 02013
Author(s):  
Alina Kuznetsova ◽  
Mikhail Dolgopolov ◽  
Albina Gurskaya ◽  
Viktor Chepurnov ◽  
Galina Puzyrnaya ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Silicon Carbide ◽  
Carbon Isotope ◽  
Silicon Substrate ◽  
Stable Carbon Isotope ◽  
Normal Pressure ◽  
Stable Carbon ◽  
Radioactive Carbon ◽  
Silicon Carbide Film ◽  
Gas Chamber

The endotaxia is the process of growth of one crystal structure inside the volume of another. In this case we are talking about the formation of the Silicon Carbide film in the Silicon substrate. The Silicon substrate is placed in the gas chamber. The sample is exposed to the stream of methane gas CH4 at temperature of 1360 - 1380 ◦C and at normal pressure. Moreover, gas contains both the stable Carbon isotope C12 and the radioactive Carbon isotope C14, and hydrogen H2 in the gas acts as a carrier of Carbon.

scholarly journals Structure-Properties Correlation of Cross-Linked Penicillin G Acylase Crystals

Crystals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 451
Author(s):  
Marta Kubiak ◽  
Janine Mayer ◽  
Ingo Kampen ◽  
Carsten Schilde ◽  
Rebekka Biedendieck
Keyword(s):  
Mechanical Stability ◽  
Structural Characteristics ◽  
Penicillin G ◽  
Bacillus Species ◽  
Diffusion Limitations ◽  
Small Water ◽  
Long Term Stability ◽  
Atomic Force ◽  
First Time

In biocatalytic processes, the use of free enzymes is often limited due to the lack of long-term stability and reusability. To counteract this, enzymes can be crystallized and then immobilized, generating cross-linked enzyme crystals (CLECs). As mechanical stability and activity of CLECs are crucial, different penicillin G acylases (PGAs) from Gram-positive organisms have proven to be promising candidates for industrial production of new semisynthetic antibiotics, which can be crystallized and cross-linked to characterize the resulting CLECs regarding their mechanical and catalytic properties. The greatest hardness and Young’s modulus determined by indentation with an atomic force microscope were observed for CLECs of Bacillus species FJAT-PGA CLECs (26 MPa/1450 MPa), followed by BmPGA (Priestia megaterium PGA, 23 MPa/1170 MPa) and BtPGA CLECs (Bacillus thermotolerans PGA, 11 MPa/614 MPa). In addition, FJAT- and BtPGA CLECs showed up to 20-fold higher volumetric activities compared to BmPGA CLECs. Correlation to structural characteristics indicated that a high solvent content and low number of cross-linking residues might lead to reduced stability. Furthermore, activity seems to be restricted by small water channels due to severe diffusion limitations. To the best of our knowledge, we show for the first time in this study that the entire process chain for the characterization of diverse industrially relevant enzymes can be performed at the microliter scale to discover the most important relationships and limitations.

scholarly journals A Quasi-Static Quantitative Ultrasound Elastography Algorithm Using Optical Flow

Sensors ◽  
2021 ◽  
Vol 21 (9) ◽  
pp. 3010
Author(s):  
Raphael Lamprecht ◽  
Florian Scheible ◽  
Marion Semmler ◽  
Alexander Sutor
Keyword(s):  
Optical Flow ◽  
Young’S Modulus ◽  
Elastic Properties ◽  
Young's Modulus ◽  
Image Data ◽  
Maximum Error ◽  
Ultrasound Elastography ◽  
Static Compression ◽  
Tissue Properties ◽  
A Performance

Ultrasound elastography is a constantly developing imaging technique which is capable of displaying the elastic properties of tissue. The measured characteristics could help to refine physiological tissue models, but also indicate pathological changes. Therefore, elastography data give valuable insights into tissue properties. This paper presents an algorithm that measures the spatially resolved Young’s modulus of inhomogeneous gelatin phantoms using a CINE sequence of a quasi-static compression and a load cell measuring the compressing force. An optical flow algorithm evaluates the resulting images, the stresses and strains are computed, and, conclusively, the Young’s modulus and the Poisson’s ratio are calculated. The whole algorithm and its results are evaluated by a performance descriptor, which determines the subsequent calculation and gives the user a trustability index of the modulus estimation. The algorithm shows a good match between the mechanically measured modulus and the elastography result—more precisely, the relative error of the Young’s modulus estimation with a maximum error 35%. Therefore, this study presents a new algorithm that is capable of measuring the elastic properties of gelatin specimens in a quantitative way using only the image data. Further, the computation is monitored and evaluated by a performance descriptor, which measures the trustability of the results.

scholarly journals A parametric prediction of the Young’s modulus of polymers enhanced with ΜWCNTs

2018 ◽  
Vol 233 ◽  
pp. 00025
Author(s):  
P.V. Polydoropoulou ◽  
K.I. Tserpes ◽  
Sp.G. Pantelakis ◽  
Ch.V. Katsiropoulos
Keyword(s):  
Young’S Modulus ◽  
Elastic Properties ◽  
Young's Modulus ◽  
Experimental Results ◽  
Scale Model ◽  
Fe Model ◽  
Multi Scale ◽  
Unit Cells ◽  
Random Dispersion

In this work a multi-scale model simulating the effect of the dispersion, the waviness as well as the agglomerations of MWCNTs on the Young’s modulus of a polymer enhanced with 0.4% MWCNTs (v/v) has been developed. Representative Unit Cells (RUCs) have been employed for the determination of the homogenized elastic properties of the MWCNT/polymer. The elastic properties computed by the RUCs were assigned to the Finite Element (FE) model of a tension specimen which was used to predict the Young’s modulus of the enhanced material. Furthermore, a comparison with experimental results obtained by tensile testing according to ASTM 638 has been made. The results show a remarkable decrease of the Young’s modulus for the polymer enhanced with aligned MWCNTs due to the increase of the CNT agglomerations. On the other hand, slight differences on the Young’s modulus have been observed for the material enhanced with randomly-oriented MWCNTs by the increase of the MWCNTs agglomerations, which might be attributed to the low concentration of the MWCNTs into the polymer. Moreover, the increase of the MWCNTs waviness led to a significant decrease of the Young’s modulus of the polymer enhanced with aligned MWCNTs. The experimental results in terms of the Young’s modulus are predicted well by assuming a random dispersion of MWCNTs into the polymer.

scholarly journals High-Temperature Elastic Properties of Yttrium-Doped Barium Zirconate

Metals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 968
Author(s):  
Fumitada Iguchi ◽  
Keisuke Hinata
Keyword(s):  
High Temperature ◽  
Young’S Modulus ◽  
Elastic Properties ◽  
Measurement Method ◽  
Young's Modulus ◽  
Barium Zirconate ◽  
Shear Moduli ◽  
Ceramic Fuel ◽  
Yttrium Concentration ◽  
Ceramic Fuel Cells

The elastic properties of 0, 10, 15, and 20 mol% yttrium-doped barium zirconate (BZY0, BZY10, BZY15, and BZY20) at the operating temperatures of protonic ceramic fuel cells were evaluated. The proposed measurement method for low sinterability materials could accurately determine the sonic velocities of small-pellet-type samples, and the elastic properties were determined based on these velocities. The Young’s modulus of BZY10, BZY15, and BZY20 was 224, 218, and 209 GPa at 20 °C, respectively, and the values decreased as the yttrium concentration increased. At high temperatures (>20 °C), as the temperature increased, the Young’s and shear moduli decreased, whereas the bulk modulus and Poisson’s ratio increased. The Young’s and shear moduli varied nonlinearly with the temperature: The values decreased rapidly from 100 to 300 °C and gradually at temperatures beyond 400 °C. The Young’s modulus of BZY10, BZY15, and BZY20 was 137, 159, and 122 GPa at 500 °C, respectively, 30–40% smaller than the values at 20 °C. The influence of the temperature was larger than that of the change in the yttrium concentration.

First-principles study of electronic structure, chemical bonding and elastic properties for new superconductor CaFeAs2

2017 ◽  
Vol 31 (02) ◽  
pp. 1650263
Author(s):  
J. G. Yan ◽  
Z. J. Chen ◽  
G. B. Xu ◽  
Z. Kuang ◽  
T. H. Chen ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Elastic Properties ◽  
Density Of States ◽  
First Principles ◽  
Elastic Anisotropy ◽  
First Principles Calculation ◽  
Hard Material ◽  
Dirac Cone ◽  
First Time ◽  
New Superconductor

Using first-principles calculation we investigated the structural, electronic and elastic properties of paramagnetic CaFeAs2. Our results indicated that the density of states (DOS) was dominated predominantly by Fe-3[Formula: see text] states at Fermi levels, and stronger hybridization exists between As1 and As1 atoms. Three hole pockets are formed at [Formula: see text] and Z points, and two electronic pockets are formed at A and E points. The Dirac cone-like bands appear near B and D points. For the first time we calculated the elastic properties and found that CaFeAs2 is a mechanically stable and moderately hard material, it has elastic anisotropy and brittleness, which agrees well with the bonding picture and the calculation of Debye temperature ([Formula: see text]).

scholarly journals Extraction, Structural Characterization, and Anti-Hepatocellular Carcinoma Activity of Polysaccharides From Panax ginseng Meyer

2021 ◽  
Vol 11 ◽  
Author(s):  
Hui Jia ◽  
Bin Zhao ◽  
Fangfang Zhang ◽  
Ramesh Kumar Santhanam ◽  
Xinying Wang ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Hepg2 Cells ◽  
Cytotoxic Effect ◽  
Structural Characteristics ◽  
Gel Permeation Chromatography ◽  
Salting Out ◽  
Gel Permeation ◽  
Acidic Polysaccharides ◽  
Hepg2 Cell Lines ◽  
First Time

Polysaccharides are the main active ingredients of ginseng. To extract the most effective polysaccharides against hepatocellular carcinoma (HCC), we isolated and characterized the polysaccharides from the mountain cultivated ginseng (MCG) and compared their composition and cytotoxic effect with cultivated ginseng (CG) polysaccharide against HepG2 cell lines for the first time. MCG polysaccharides and CG polysaccharides were fractionated into two fractions such as MTPS-1, MTPS-2 and CTPS-1, CTPS-2 by salting out, respectively. Compared to CG, MCG possessed appreciable cytotoxic effect against HepG2 cells among that MTPS-1 possess fortified effect. Then, MTPS-1 was selected for further isolation process and seven acidic polysaccharides (MCGP-1–MCGP-7) were obtained using ethanol precipitation, ion-exchange, and gel permeation chromatography techniques. Structural characteristics of the polysaccharides (MCGP-1–MCGP-7) were done by adapting methylation/GC-MS and NMR analysis. Overall, MCGP-3 polysaccharide was found to possess significant cytotoxic effect against HepG2 cells with the IC50 value.

scholarly journals Major characteristics of mixed fir and beech virgin forests in the National park Biogradska Gora in Montenegro

2011 ◽  
pp. 157-172 ◽  
Author(s):  
Milic Curovic ◽  
Milan Medarevic ◽  
Rade Cvjeticanin ◽  
Mirko Knezevic
Keyword(s):  
National Park ◽  
Forest Ecosystems ◽  
Structural Characteristics ◽  
Forest Types ◽  
Beech Forests ◽  
Basic Characteristics ◽  
Definition Of ◽  
First Time ◽  
Production Characteristics

In order to manage forest ecosystems at a sufficiently high biodiversity level it is necessary to study the ecological, structural and production characteristics of virgin forests. The research was directed towards identifying the characteristics of mixed fir and beech forests (Abieti-Fagetum s. lat.) in the area of the strict reserve of the National Park Biogradska Gora in Montenegro. Basic characteristics of these forests were researched in the process of definition of forest types. In this manner, it is for the first time that a realistic base for typological management of forests and forest ecosystems with similar ecological and structural characteristics was provided for the specific sites.

Sign in / Sign up

Export Citation Format

Share Document