Orbitally induced hierarchy of exchange interactions in zigzag antiferromagnetic state of honeycomb silver delafossite Ag3Co2SbO6

We report the revised crystal structure, static and dynamic magnetic properties of quasi-two dimensional honeycomb-lattice silver delafossite Ag3Co2SbO6. The magnetic susceptibility and specific heat data are consistent with the onset of antiferromagnetic long range order at low temperatures with N\'eel temperature TN ~ 21.2 K. In addition, the magnetization curves revealed a field-induced (spin-flop type) transition below TN in moderate magnetic fields. The GGA+U calculations show the importance of the orbital degrees of freedom, which maintain a hierarchy of exchange interaction in the system. The strongest antiferromagnetic exchange coupling was found in the shortest Co-Co pairs and is due to direct and superexchange interactions between the half-filled xz+yz orbitals pointing directly to each other. The other four out of six nearest neighbor exchanges within the cobalt hexagon are suppressed, since for these bonds active half-filled orbitals turned out to be parallel and do not overlap. The electron spin resonance (ESR) spectra reveal a Gaussian shape line attributed to Co2+ ion in octahedral coordination with average effective g-factor g=2.3+/-0.1 at room temperature and shows strong divergence of ESR parameters below 120 K, which imply an extended region of short-range correlations. Based on the results of magnetic and thermodynamic studies in applied fields, we propose the magnetic phase diagram for the new honeycomb-lattice delafossite

Increase housing provision of citizens as a priority direction of social and economic development of the region

Set out the results of the study provide citizens with housing as a priority direction of social and economic development of the market; showed the causes of low housing provision of citizens of the Belgorod region, made conclusions and identified measures to increase housing provision in the cities of RussiayesBelgorod State National Research Universit

Improving the Learning and Teaching of Mathematical Logic Elements Using Maple

The study of the elements of mathematical logic and its sections, especially in the process of teaching in high school in general and specialized courses of mathematics or higher educational institutions, is a rather tricky task. The paper demonstrates how one can design and develop a package of interactive applications to help learn, understand, and apply the essential elements of mathematical logic. The research aims to develop and describe an interactive application for studying the order of constructing truth tables and studying and demonstrating the production of principal normal disjunctive and conjunctive forms. The development is based on the methods of the Maple computer algebra system of the Maplet library. In addition, other methods are used to solve the research issues – theoretical and accurate analytical solutions to mathematical logic issues. All constructed material (Maplet) will serve as a good simulator for students, allowing one to perform an infinite number of attempts to analyze, synthesize, and build truth tables

The impact of Nd3+/La3+ substitution on the cation distribution and phase diagram in the La2SrAl2O7-Nd2SrAl2O7 system

Received: 28.04.2018. Accepted: 09.05.2018. Published: 10.05.2018.The effect of isovalent cation substitution of lanthanum atoms in the structure of La2SrAl2O7 oxide, and phase equilibria (solidus-liquidus curves) in the binary system La2SrAl2O7-Nd2SrAl2O7 were studied. It was found that Nd3+ substitution for La3+ has effect on the structure of La2SrAl2O7 in respect of the character of cation distribution in the solid solution La2–xNdxSrAl2O7 from statistically disordered to the ordered one where strontium cations predominantly occupied the rock-salt layers, as reflected by the solidus-liquidus lines

Molecular genetic methods for identifying raw materials in meat products: Diversity, opportunities and prospects

In the current economic situation, after easing the Covid pandemic restrictions, almost all laboratories, which are focused on evaluation of the conformity of food products, have faced issues in supplying for their laboratories. In this regard, in the last years many laboratories have been forced to validate new approaches and introduce new methods for assessing conformity of the food products. Very often it is not possible to use only one method to resolve the issue of the food product ingredients, especially for the purpose of traceability of their names and the used raw materials, listed on the label. Survey of the raw food materials to determine whether they correspond to the type name is a simpler task, in contrast to survey of the multicomponent food product. Many researchers have to estimate the opportunities and feasibility of application of various methodologies in their workplaces. Therefore, this review is relevant for the researchers in this field, as it focuses on aspects and special features of similar methodologies. The prospect of molecular genetic methods for identification of the raw materials used for manufacturing of meat products is presented below. This review also represents characteristics of methods for identification of the sources of raw materials used for the manufacturing of the meat products, based on the recognition of species-specific sections within the nucleic acids structures. The variety of methods (hybridization methods, polymerase chain reaction, different types of isothermal amplifications, methods using CRISPR/Cas systems), the principles of their implementation, and achieved analytical characteristics are considered. The capacities and competitive potential of various methods are discussed, as well as approaches being developed to overcome the existing limitations.In the current economic situation, after easing the Covid pandemic restrictions, almost all laboratories, which are focused on evaluation of the conformity of food products, have faced issues in supplying for their laboratories. In this regard, in the last years many laboratories have been forced to validate new approaches and introduce new methods for assessing conformity of the food products. Very often it is not possible to use only one method to resolve the issue of the food product ingredients, especially for the purpose of traceability of their names and the used raw materials, listed on the label. Survey of the raw food materials to determine whether they correspond to the type name is a simpler task, in contrast to survey of the multicomponent food product. Many researchers have to estimate the opportunities and feasibility of application of various methodologies in their workplaces. Therefore, this review is relevant for the researchers in this field, as it focuses on aspects and special features of similar methodologies. The prospect of molecular genetic methods for identification of the raw materials used for manufacturing of meat products is presented below. This review also represents characteristics of methods for identification of the sources of raw materials used for the manufacturing of the meat products, based on the recognition of species-specific sections within the nucleic acids structures. The variety of methods (hybridization methods, polymerase chain reaction, different types of isothermal amplifications, methods using CRISPR/Cas systems), the principles of their implementation, and achieved analytical characteristics are considered. The capacities and competitive potential of various methods are discussed, as well as approaches being developed to overcome the existing limitations

Latitudinal pattern in community-wide herbivory does not match the pattern in herbivory averaged across common plant species

The latitudinal herbivory hypothesis (LHH) predicts that plant losses to herbivores decrease from low to high latitudes. Although the LHH is a community-level hypothesis, it has been rarely tested with data on community-wide herbivory, i.e. the percentage of annual production of foliar biomass consumed by insects from all plant species at a given site. Therefore, we asked whether community-wide leaf herbivory follows the same latitudinal pattern as observed for an unweighted average of herbivory across common plant species. We selected 10 study sites in boreal forests from 60 to 69 degrees N along a 1,000-km long latitudinal gradient in NW Russia. We measured relative foliar losses to insect herbivores in seven woody plant species (jointly comprising over 95% of the community-wide above-ground biomass) and estimated their current-year foliar biomass. We averaged leaf herbivory for all seven species and calculated community-wide leaf herbivory by weighting the relative foliar losses of each plant species against the contribution of that species to the annual foliar biomass production. Leaf herbivory was five-fold higher in deciduous species than in conifers. Latitudinal patterns in herbivory varied from a significant poleward decrease in all deciduous species to a significant poleward increase in Norway spruce. Herbivory values, averaged across seven plant species, decreased with latitude and followed the pattern observed in deciduous plants due to their higher foliar losses compared with conifers. By contrast, community-wide herbivory did not change with latitude. This discrepancy emerged because the proportion of deciduous plant foliage in the community increased with increasing latitude, and this increase counterbalanced the simultaneous poleward decrease in losses of these species to insects. Synthesis. The herbivory measured by averaging relative losses of individual plant species and community-wide herbivory is likely to show different latitudinal patterns in various plant communities. The contributions of plant species to the total foliar biomass production should be taken into account in studies of spatial patterns of herbivory which test community-level hypotheses. This approach may provide new insight into macroecological research on biotic interactions and improve our understanding of the role of insect herbivores in ecosystem-level processes

Consumer behavior in the context of global economic transformations

Transition to alternative methods of service and omnichannelity allows the buyer to be more demanding and discerning. The current trends in the development of retail trade caused by globalization forcing the redistribution of consumer budget from a high-margin offline cart to a low-margin online cart that instigate not only the necessity of transformations in management, but also the study of consumer behavior. Dynamical development of trading innovative technologies allows the buyers not only to expand the range of their aspiration, but also to become participants in the cognitive and learning processes, where the acquirement of the new experience and emotions influences the traditional ways of making purchases on offline trading. To remain competitive, retailers should not only provide high-quality goods and services at the best prices, but also to contribute to their high-quality and get-to-able supply. Most purchasing decisions are made "by feel", that contradict to the theories of rational choice and theories using marketing concepts. The article gives views on the factors and criteria that determine consumers behavior in online and offline trade.peer-reviewe

Reação adaptativa do sistema simpático de adrenalina de meninas em atividade física

The study of the functional state of the sympatho-adrenal system in girls of 11-16 years old undergoing graduated physical activity was performed on the basis of excretion rates of epinephrine, norepinephrine, dopamine and DOPA. As a functional test, a graduated cycloergometric load of 50% of the individually determined PWC170 was used. The results obtained made it possible to establish the heterochronic nature of the maturation of the hormonal and mediator links of the sympathetic adrenal system. The highest reactivity of the adrenal link of SAS is observed in girls of 12 years old, the lowest – in senior schoolgirls (15-16 years old). In girls of 12-13 years old, the reaction of urgent adaptation to the graduated physical activity is carried out against a background of high excretion of epinephrine (E), norepinephrine (NE), but without sufficient replenishment of the reserve capabilities of SAS, which is confirmed by minimal shifts in the excretion of dopamine (DA) and DOPA in these age groups. At 14-16 years, moderate shifts of E and NE as a reaction to activity are noted against the background of a significant increase in the excretion of precursors, which characterizes the SAS response to the functional test as more saving, with increasing reserve capacities.El estudio del estado funcional del sistema simpato-adrenal en niñas de 11-16 años sometidas a actividad física graduada se realizó sobre la base de las tasas de excreción de epinefrina, norepinefrina, dopamina y DOPA. Como prueba funcional, se utilizó una carga cicloergométrica graduada del 50% de la PWC170 determinada individualmente. Los resultados obtenidos permitieron establecer la naturaleza heterócrona de la maduración de los enlaces hormonales y mediadores del sistema adrenal simpático. La mayor reactividad del enlace suprarrenal de SAS se observa en niñas de 12 años, la más baja - en niñas de escuela secundaria (15-16 años). En niñas de 12-13 años de edad, la reacción de adaptación urgente a la actividad física gradual se lleva a cabo en un contexto de alta excreción de epinefrina (E), norepinefrina (NE), pero sin un reabastecimiento suficiente de las capacidades de reserva de SAS. que se confirma por cambios mínimos en la excreción de dopamina (DA) y DOPA en estos grupos de edad. A los 14-16 años, se observan cambios moderados de E y NE como reacción a la actividad en el contexto de un aumento significativo en la excreción de precursores, que caracteriza la respuesta SAS a la prueba funcional como más ahorro, con el aumento de la capacidad de reserva.O estudo do estado funcional das raparigas do sistema simpático-envelhecido 11-16 anos, submetidos a actividade física realizada classificados com base em taxas de excreção de epinefrina, norepinefrina, dopamina e DOPA. Como teste funcional, utilizou-se uma carga cicloergométrica graduada de 50% do PWC170 individualmente determinado. Os resultados obtidos permitiram estabelecer a natureza heterocrônica da maturação dos laços hormonais e mediadores do sistema adrenal simpático. A reatividade mais alta do elo adrenal de SAS observa-se em meninas de 12 anos, o mais baixo - em meninas de escola secundária (15-16 anos). Em raparigas com idades entre 12-13, reacção urgente de adaptação gradual da actividade física ocorre em um contexto de elevada excreção de adrenalina (E), norepinefrina (NE), mas sem capacidades de reabastecimento suficientes Reserva SAS. o que é confirmado por alterações mínimas na excreção de dopamina (DA) e DOPA nestes grupos etários. Aos 14-16 anos, E e NE variações moderadas em resposta à actividade no contexto de um aumento significativo da excreção de precursores, o que caracteriza a resposta SAS para um teste funcional, mais economia, com o aumento observado a capacidade de reserva