scholarly journals Изменение температуры Дебая при аморфизации однокомпонентного вещества

2019 ◽  
Vol 45 (20) ◽  
pp. 32
Author(s):  
М.Н. Магомедов
Keyword(s):  
Basic Research ◽  
Amorphous Structure ◽  
Nonlinear Dependence ◽  
Structure Packing ◽  
Jones Potential ◽  
Packing Factor ◽  
Debye Temperatures ◽  
Amorphous Structures ◽  
Basic Research Project ◽  
Academy Of Sciences

Based on the nonlinear dependence of the first coordination number versus of the structure-packing factor (kp), a method for calculating of the Debye temperature for the amorphous structure of a monoatomic substance is proposed. By means of the parameters of pairwise Mie-Lennard-Jones potential, the Debye temperatures were calculated for the crystalline and amorphous structures of a number of pure metals, diamond, Si, Ge. Good agreement is obtained with the estimates of other authors. It is shown that at kp = 0.45556 the minimum of the Helmholtz specific free energy is reached, i.e. this packing is the thermodynamically stable amorphous structure. This work was supported by the Russian Foundation for Basic Research (project no. 18-29-11013_mk) and the program no. I.13 of the Presidium of the Russian Academy of Sciences.

scholarly journals Уравнение состояния и поверхностные свойства аморфного железа

2020 ◽  
Vol 90 (10) ◽  
pp. 1731
Author(s):  
М.Н. Магомедов
Keyword(s):  
Liquid Phase ◽  
Chemical Potential ◽  
Interatomic Potential ◽  
Solid Phase ◽  
Amorphous Solid ◽  
Amorphous Structure ◽  
State Equation ◽  
Nonlinear Dependence ◽  
Amorphous Structures ◽  
Special Points

It is shown that on the nonlinear dependence of the first coordination number (kn) versus the packing coefficient (kp) of the structure of a mono-component substance, three special points corresponding to the amorphous structure can be distinguished. Based on the pairwise interatomic potential of Mie–Lennard-Jones, the state equation and properties of iron for both these three amorphous structures and the crystal state are calculated. It is shown that at kp = 0.45556 and kn = 6.2793 the minimum chemical potential is reached, i.e. this point is corresponding a thermodynamically stable amorphous structure into the liquid phase. An energetically equivalent point with the same kn value, but with kp = 0.6237, is a thermodynamically unstable amorphous structure corresponding to the solid phase. It is shown that the specific surface energy of an amorphous solid metal is greater than that of an amorphous liquid phase, but less than that of a metal in the crystalline state. This should lead to the fact that the surface of the crystal metal should tend to amorphize.

scholarly journals Изменение термодинамических свойств твердого раствора Si-Ge при уменьшении размера нанокристалла

2019 ◽  
Vol 61 (11) ◽  
pp. 2169
Author(s):  
М.Н. Магомедов
Keyword(s):  
Solid Solution ◽  
Thermodynamic Properties ◽  
Binary Alloy ◽  
Specific Volume ◽  
Pressure Range ◽  
Basic Research ◽  
State Equation ◽  
The State ◽  
Basic Research Project ◽  
Academy Of Sciences

In the framework of the “medium atom” model for a binary alloy, the state equation and the thermodynamic properties of the Si0.5-Ge0.5 solid solution are calculated. Using the RP model of the nanocrystal, the changes of both the state equation and thermodynamic properties are calculated during the transition from a macrocrystal to a nanocrystal of 222 atoms with a geometric Gibbs surface. The calculations were carried out along the isotherms T = 100, 300 and 1000 K, in the pressure range: – 1 < P < 7 GPa. The change in the properties of both at the isochoric and at isobaric (P = 0) decrease in the number of atoms in a nanocrystal were studied. It is shown that at an isobaric (P = 0) decrease of size, the specific volume of the Si0.5-Ge0.5 nanocrystal increases the more, the higher the nanocrystal temperature. This work was supported by the Russian Foundation for Basic Research (project no. 18-29-11013_mk) and the program no. 6 of the Presidium of the Russian Academy of Sciences (grant no. 2-13)

Creation of Plasmidless and Markerless Escherichia coli Succinate Producing Strain and Evaluation of its Biosynthetic Potential during Utilization of Lignocellulosic Sugars

2020 ◽  
Vol 36 (2) ◽  
pp. 3-11
Author(s):  
O.A. Zhuravliova ◽  
Т.А. Voeikova ◽  
A.Yu. Gulevich ◽  
V.G. Debabov
Keyword(s):  
Escherichia Coli ◽  
Succinic Acid ◽  
Plant Biomass ◽  
Anaerobic Fermentation ◽  
Basic Research ◽  
Acid Fermentation ◽  
Mixed Acid ◽  
Gene Coding ◽  
Lignocellulosic Sugars ◽  
Basic Research Project

The plasmidless and markerless Escherichia coli succinate producing strain SGM2.0Pyc-int has been engineered and characterized. The strain has the inactivated main mixed-acid fermentation pathways due to the deletions of ldhA,poxB, ackA,pta, and adhE genes, constitutively expresses the genes of the aceEF-lpdA operon encoding components of pyravate dehydrogenase complex, and possesses the chromosomally integrated Bacillus subtilis pycA gene coding for pyruvate carboxylase. The capacity of the strain to synthesize succinic acid in course of dual-phase aerobic-anaerobic fermentation with lignocellulosic sugars as substrates was studied. The SGM2.0Pyc-int strain synthesized succinic acid from glucose, xylose, and arabinose with a molar yields of 1.41 mol/mol, 1.18 mol/mol, and 1.18 mol/mol, respectively, during the anaerobic production stage. The constructed strain has great potential for developing efficient processes for the succinic acid production from plant biomass-derived sugars. Escherichia coli, fermentation, arabinose, glucose, xylose, succinic acid. The work was supported by a Grant from the Russian Foundation for Basic Research (Project no. 18-29-14005).

Utilization of a hydrate cellulose film for investigation of Arabidopsis thaliana L. root system growth and development

2020 ◽  
Vol 36 (1) ◽  
pp. 36-43
Author(s):  
I.O. Konovalova ◽  
T.N. Kudelina ◽  
S.O. Smolyanina ◽  
A.I. Lilienberg ◽  
T.N. Bibikova
Keyword(s):  
Arabidopsis Thaliana ◽  
Root System ◽  
Life Support ◽  
Higher Plants ◽  
Plant Root ◽  
Lateral Roots ◽  
Basic Research ◽  
Cellulose Film ◽  
A New Technique ◽  
Basic Research Project

A new technique for Arabidopsis thaliana cultivation has been proposed that combines the use of a phytogel-based nutrient medium and a hydrophilic membrane of hydrate cellulose film, separating the root system of the plant from the medium thickness. Growth rates of both main and lateral roots were faster in the plants cultivated on the surface of hydrate cellulose film than in the plants grown in the phytogel volume. The location of the root system on the surface of the transparent hydrate film simplifies its observation and analysis and facilitates plant transplantation with preservation of the root system configuration. The proposed technique allowed us to first assess the effect of exogenous auxin on the growth of lateral roots at the 5-6 developmental stage. methods to study plant root systems, hydrate cellulose film, A. thaliana, lateral roots, differential root growth rate, auxin The work was financially supported by the Russian Foundation for Basic Research (Project Bel_mol_a 19-54-04015) and the basic topic of the Russian Academy of Sciences - IBMP RAS «Regularities of the Influence of Extreme Environmental Factors on the Processes of Cultivation of Higher Plants and the Development of Japanese Quail Tissues at Different Stages of its Ontogenesis under the Conditions of Regenerative Life Support Systems».

Structure and properties of a phenylethynyl-terminated PMDA-type asymmetric polyimide

2018 ◽  
Vol 31 (3) ◽  
pp. 261-272 ◽  
Author(s):  
Yixiang Zhang ◽  
Masahiko Miyauchi ◽  
Steven Nutt
Keyword(s):  
Mechanical Properties ◽  
Thermal Processing ◽  
Amorphous Structure ◽  
Decomposition Temperature ◽  
Thermal And Mechanical Properties ◽  
Chain Mobility ◽  
Amorphous Structures ◽  
The Cross ◽  
Imide Oligomers ◽  
The Relationship

A new polymerized monomeric reactant (PMR)-type polyimide, designated TriA X, was investigated to determine polymer structure, processability, thermal, and mechanical properties and establish the relationship between the molecular structure and those properties. TriA X is a PMR-type polyimide with an asymmetric, irregular, and nonplanar backbone. Both the imide oligomers and the cross-linked polyimides of TriA X exhibited loose-packed amorphous structures, independent of thermal processing. The peculiar structures were attributed to the asymmetric backbone, which effectively prevented the formation of closed-packed chain stacking typically observed in polyimides. The imide oligomers exhibited a lower melt viscosity than a control imide oligomer (symmetric and semi-crystalline), indicating a higher chain mobility above the glass transition temperature ( Tg). The cured polyimide exhibited a Tg = 362°C and a decomposition temperature = 550°C. The cross-linked TriA X exhibited exceptional toughness and ductility (e.g. 15.1% at 23°C) for a polyimide, which was attributed to the high-molecular-weight oligomer and loose-packed amorphous structure. The thermal and mechanical properties of TriA X surpass those of PMR-15 and AFR-PE-4.

scholarly journals Исследование кинетики твердофазного перехода в тетракозане С-=SUB=-24-=/SUB=-Н-=SUB=-50-=/SUB=- методом высокоразрешающей синхротронной рентгеновской порошковой дифракции

2019 ◽  
Vol 61 (6) ◽  
pp. 1190
Author(s):  
B.A. Марихин ◽  
П.В. Дороватовский ◽  
Я.B. Зубавичус ◽  
M.B. Байдакова ◽  
E.M. Иванькова ◽  
...  
Keyword(s):  
Phase Transition ◽  
Small Angle ◽  
Diffuse Phase Transition ◽  
Basic Research ◽  
X Ray Diffraction ◽  
Kurchatov Institute ◽  
X Ray ◽  
First Order ◽  
Basic Research Project ◽  
Diffuse Phase

With the help of small angle X-ray diffraction using synchrotron X-ray beamline"Belok" in NRC «Kurchatov Institute» was shown that the first order sold phase transition in the tetracosane C24H50 develops by a heterogeneous mechanism in a very narrow thermal interval (delta ≈0,1K ) in accordance with the theory of diffuse phase transition. The work was financially supported by the Presidium RAN Program №32 "Nanostructures: physics, chemistry, biology, basics of technology" and Russian Foundation of Basic Research (project 16-03-00493А) using beamline "Belok" in NRC

scholarly journals Funding system reform for excellence in science: an interview with Jinghai Li, President of NSFC

2019 ◽  
Vol 6 (1) ◽  
pp. 177-181 ◽  
Author(s):  
Zhonghe Zhou ◽  
Weijie Zhao
Keyword(s):  
Natural Science ◽  
Strong Support ◽  
Basic Research ◽  
Funding Agency ◽  
System Reform ◽  
Funding System ◽  
Reform Plan ◽  
Funding Programs ◽  
Excellence In Science ◽  
Academy Of Sciences

Abstract The National Natural Science Foundation of China (NSFC) is the major funding agency for China's basic research in natural science. The total budget for NSFC was 26.7 billion Yuan (RMB) in 2017, accounting for 27% of China's total investment in basic research. In the past decades, continuous increases in the National Natural Science Fund and other funding programs provided strong support for the rapid growth in China's science and technology (S&T). In the second half of 2018, NSFC unveiled a deep reform plan that aims to build a fair, efficient and standardized new funding system that meets the demands of excellence in science in the twenty-first century in 5–10 years. Why did NSFC propose this reform? What are the major tasks of this reform? And how would NSFC implement this reform? All-in-all, this reform would not only have profound effect on S&T in China but also matters the world for the global collaborative efforts for the science. Recently, National Science Review had an exclusive interview with Jinghai Li, President of NSFC and Academician of the Chinese Academy of Sciences, to learn his views and perspectives of the future of NSFC.

Sign in / Sign up

Export Citation Format

Share Document