Polarization states of polydomain epitaxial Pb(Zr1-xTix)O3 thin films and their dielectric properties

Ferroelectric and dielectric properties of polydomain (twinned) single-crystal Pb(Zr1-xTix)O3 thin films are described with the aid of a nonlinear thermodynamic theory, which has been developed recently for epitaxial ferroelectric films with dense laminar domain structures. For Pb(Zr1-xTix)O3 (PZT) films with compositions x = 0.9, 0.8, 0.7, 0.6, 0.5, and 0.4, the "misfit strain-temperature" phase diagrams are calculated and compared with each other. It is found that the equilibrium diagrams of PZT films with x > 0.7 are similar to the diagram of PbTiO3 films. They consist of only four different stability ranges, which correspond to the paraelectric phase, single-domain tetragonal ferroelectric phase, and two pseudo-tetragonal domain patterns. In contrast, at x = 0.4, 0.5, and 0.6, the equilibrium diagram displays a rich variety of stable polarization states, involving at least one monoclinic polydomain state. Using the developed phase diagrams, the mean out-of-plane polarization of a poled PZT film is calculated as a function of the misfit strain and composition. Theoretical results are compared with the measured remanent polarizations of PZT films grown on SrTiO3. Dependence of the out-of-plane dielectric response of PZT films on the misfit strain in the heterostructure is also reported.Comment: 23 pages, 4 figure

Effect of cold rolling on consistent pattern and mechanisms deformation, structural and phase transitions and mechanical properties of single crystals steel Fe-28Mn-2.6Al-1.3C

The dependence of microhardness of Fe-28Mn-2.6Al-1.3C single crystals on the degree of precipitation and deformation temperature is established. It can be divided into three sections: in sections I and III, the microhardness is slightly dependent on the orientation of the sample, while in section II the orientation dependence of microhardness is manifested. The orientation dependence of the microhardness is determined by the orientation dependence of the dislocation structure and the deformation mechanism (slip and / or twinning). Rolling does not lead to the realization of deformation phase transitions of steel Fe-28Mn-2.6Al-1.3C

Lending system for agricultural enterprises: Prospects for development and transformation

The article examines the current situation of using lending, leasing and factoring instruments for agricultural producers in modern Russia. The authors note that the current lending and leasing system requires transformation to take into account the conditions for the activities of agricultural enterprises, taking into account seasonality and the delayed effect of obtaining results. A transformation system for leasing is also proposed to make the instrument more flexible through the introduction of commercial instruments and the abandonment of exclusively government regulation of the activity in question. The authors note the effectiveness of the transformation of the proposed methods of lending, leasing and factoring by increasing demand and reducing the risk of repayment for both enterprises and participants in the banking sector

The necessity and complexity of standardization

-The standards are one of the most important infrastructural elements of the economy. The relationship between all factors ensuring product quality and safety is carried out by using complex standardization. The standards establish and ensure the technically achievable level of safety, quality and competitiveness of products. The main factors of standardization object: the object composition, object production and monitoring, in their turn, form the following more precise groups of factors, determining the object quality: primary products and materials, component nodes and parts, production technology, equipment, tools and appliances, measurement means, and test methods. On the example of a specific standard, the "tree of references" of the first and second levels and the problems of an integrated approach for establishing quality requirements for a specific product is considered. The necessity and complexity of updating the requirements that ensure the systematization, optimization and coordination of all interacting factors influencing a specific object of standardization and providing an economically optimal level of quality of the object are demonstrated. © 2020, World Scientific and Engineering Academy and Society. All rights reserved

Melatonin and its regulatory effect on the hormone, tissue and cellular levels

Проведен анализ ряда работ отечественной и зарубежной литературы, посвященных изучению регуляторного влияния мелатонина на организм. Показана возрастная динамика синтеза мелатонина, определенные механизмы влияния на репродуктивную функцию, антиоксидантные и иммуномодулирующие свойства, участие в процессах канцерогенеза, посредством изменения пролиферативной и апоптозной активности, угнетения активности теломеразы. В результате проведенного анализа можно заключить наличие у мелатонина способности регулировать биологические ритмы, антиоксидантной и противоопухолевой активности, контроля над эндокринной, нервной, иммунной системами, способности обеспечивать естественную структуру сна, замедлять процессы старения, влияния на развитие беременности и плод.The analysis of a number of works of domestic and foreign literature devoted to the study of regulatory impact on melatonin hormone, tissue and cellular levels. Has been shown age dynamics of the synthesis of melatonin, has been highlighted certain mechanisms of influence on the reproductive function, antioxidant and immunomodulatory properties. The results of many studies melatonin has confirmed participation in the carcinogenesis process, by changing the proliferative and apoptotic activity, inhibition of telomerase activity. As a result of the carried-out analysis it is possible to conclude existence at melatonin of ability to regulate biological rhythms, antioxidatic and antitumoral activity, control over endocrine, nervous, immune systems, ability to provide natural structure of a dream, to slow down processes of aging, influence on development of pregnancy and a fetus

A practical route to fluoroalkyl- and fluoroarylamines by base-catalyzed [1,3]-proton shift reaction

The base-catalyzed [1,3]-proton shift reaction is shown to be an efficient general approach to fluoroalkyl and fluoroaryl amines starting from appropriate carbonyl compounds and benzylamine. The base-catalyzed [1,3]-proton shift reaction is shown to be a convenient general method for preparation of primary fluoroalkyl and fluoroaryl amines starting from appropriate carbonyl compounds and benzylamine

Transamination of fluorinated β-keto carboxylic esters. A biomimetic approach to β-polyfluoroalkyl-β-amino acids.

The base-catalyzed isomerization of N-benzylimines (or enamines) of β-polyfluoroalkyl-β-ketocarboxylic esters cleanly affords the N-benzylidene derivatives of β-polyfluoro-β-aminocarboxylic esters which are hydrolyzed to corresponding amino acids in high overall yields