Semi-empirical Gibbs free energy formulations for minerals and fluids for use in thermodynamic databases of petrological interest

The P-T partition function in statistical thermodynamics can be used to derive semi-empirical formulations of the Gibbs free energy G for minerals and fluids. Parameterization of these equations includes simultaneous regression of experimental heat capacity and molar volume data, allowing fitting, appraisal and optimization of various data sources, as required in the construction of internally consistent petrological data bases. This approach can also be extended to minerals with λ-transitions and to fluids by considering the Gibbs free energy as a function of pressure P, temperature T and an ordering parameter Xα, so that accurate modelled representation and extrapolation of the thermodynamic properties of large numbers of petrologically significant minerals and coexisting fluids can be attained. The ordering parameter is chosen to denote the equilibrium mole fraction (thermodynamic probability) of ordered clusters (structural units) in a substance when G(T,P, Xα)=min. The procedure is tested on existing experimental data for the system MgO-SiO2-H2O. The proposed Gibbs free energy formulation permits thermodynamic properties of minerals, fluids and phase equilibria to be described and extrapolated over a wide range of pressure (0-800 kbar) and temperature (20-3000 K), thus allowing effective use in thermodynamic data bases of petrological interes

СУЧАСНИЙ СТАН І НАПРЯМИ ПОКРАЩЕННЯ БОРГОВОЇ БЕЗПЕКИ УКРАЇНИ

The article examines the debt safety as a priority trend to ensure financial safety of Ukraine and its main component. It considers modern scientific views of defining the nature of the debt safety and effects of the debt burden on the economy of Ukraine. In order to reveal the factors that affect the assessment of the debt safety of Ukraine, we have analyzed the dynamics of the state safety debt by means of a system of indicators. It researches on the main indicators of debt safety state reflecting the content and effectiveness of public debt management through taking into account some boundary values which allowed us to specify the main factors that caused some negative tendencies in the calculated indicators. The study has identified the most dangerous values of the indicators directly affecting the state of the debt safety in Ukraine. In particular, this is a ratio of the total public debt to GDP and the external debt per person in the US dollars. This study also conducted a detailed economic assessment of the state of the debt safety in Ukraine during 2013–2016. It provides some estimates of the public debt, internal and external public debt which is based on the cost of its maintenance, the ratio of total public and publicly guaranteed debt to GDP. We suggest some ways of increasing the debt safety of Ukraine, taking in account political instability and military conflict in the East of the country.В статье раскрыта долговая безопасность, как приоритетное направление обеспечения финансовой безопасности Украины. Исследованы современные научные взгляды относительно определения сущности долговой безопасности и проблем долговой нагрузки на экономику Украины. Произведена оценка долговой безопасности Украины с помощью системы показателей, что дало возможность раскрыть факторы, которые имеют влияние на состояние долговой безопасности Украины. Рассчитаны основные индикаторы состояния долговой безопасности, которые отображают результативность управления государственным долгом с учетом предельных значений, что дало возможность установить основные факторы, которые повлекли негативные тенденции рассчитанных показателей. Предложены направления относительно повышения уровня долговой безопасности Украины. У статті розкрито боргову безпеку, як пріоритетний напрям забезпечення фінансової безпеки України. Досліджено сучасні наукові погляди щодо визначення сутності боргової безпеки та проблем боргового навантаження на економіку України. Дано оцінку боргової безпеки України за допомогою системи показників, що дало змогу розкрити чинники, які мають вплив на стан боргової безпеки України. Розраховано основні індикатори стану боргової безпеки, які відображають зміст і результативність управління державним боргом з урахуванням граничних значень, що дало змогу встановити основні фактори, які спричинили негативні тенденції розрахованих показників. Запропоновано напрями щодо підвищення рівня боргової безпеки України

Order/disorder phase transition in cordierite and its possible relationship to the development of symplectite reaction textures in granulites

Based on a consistent set of empirical interatomic potentials, static structure energy calculations of various Al/Si configurations in the supercell of Mg-cordierite and Monte Carlo simulations the phase transition between the orthorhombic and hexagonal modifications of cordierite (Crd) is predicted at 1623 K. The temperature dependences of the enthalpy, entropy, and free energy of the Al/Si disorder were calculated using the method of thermodynamic integration. The simulations suggest that the commonly observed crystallization of cordierite in the disordered hexagonal form could be related to a tendency of Al to occupy T1 site, which is driven by local charge balance. The increase in the Al fraction in the T1 site over the ratio of 2/3(T1): 1/3(T2), that characterizes the ordered state, precludes formation of the domains of the orthorhombic phase. This intrinsic tendency to the crystallization of the metastable hexagonal phase could have significantly postponed the formation of the association of orthorhombic cordierite and orthopyroxene over the association of quartz and garnet in metapelites subjected to granulite facies metamorphism. The textures of local metasomatic replacement (the formation of Crd + Opx or Spr + Crd symplectites between the grains of garnet and quartz) indicate the thermodynamic instability of the association of Qtz + Grt at the moment of the metasomatic reaction. This instability could have been caused by the difficulty of equilibrium nucleation of orthorhombic cordierite

ПЕРСПЕКТИВИ ВИКОРИСТАННЯ КРИПТОВАЛЮТИ БІТКОЇН ЯК ФІНАНСОВОЇ ІННОВАЦІЇ В ІНФОРМАЦІЙНІЙ ЕКОНОМІЦІ УКРАЇНИ

We have established that a relatively new market of cryptocurrency is the subject of great interest for research under the current conditions of financial innovations in payment services. Our findings have revealed objective prerequisites for creating cryptocurrency as an innovative means of information-based payment. Cryptocurrency poses a challenge to the financial system of Ukraine since both the central bank and other state regulators can not control its emission and circulation. They show the growth dynamics in cryptocurrency market capitalization where Bitcoin predominates. Although cryptocurrency is not included in the National Register of payment systems and it is officially prohibited for circulation in Ukraine, our country ranks among the world’s top five countries by number of users of different bitcoin-wallets. We have examined the strengths of Bitcoin that have made this cryptocurrency a convenient means of international payment with a high investment potential. The results show disadvantages to using cryptocurrency for both the whole country in general and ordinary consumers in particular. We have defined main threats that national governments can face in case of an unregulated spread of cryptocurrency. Also this study, based on the works of leading foreign scientists and financial market experts, systematizes factors that influence the price of Bitcoin. It substantiates opportunities and prospects for the cryptocurrency market development in Ukraine. The study has shown that cryptocurrencies have their own niche in payment systems; they are quite competitive and reliable financial instruments. The growth dynamics of cryptocurrency market capitalization in the world makes Bitcoin the most successful example of the use of virtual currency in the information economy. As the modern society is being inevitably virtualized, our country’s economy should follow the path of innovations by finding solutions to a number of technical, economic and legal issues on the cryptocurrency market development in Ukraine through involving the experience of the leading European countries.Встановлено, що у сучасних умовах розвитку фінансових інновацій у сфері платіжних послуг предметом наукових дискусій є відносно новий і малодосліджений ринок криптовалюти. Розкрито об’єктивні передумови створення криптовалюти як інноваційного платіжного засобу заснованого на інформації. Криптовалюта стала викликом для фінансової системи України, оскільки її емісію та обіг не може контролювати центральний банк та інші державні регулюючі органи. Показано динаміку зростання капіталізації ринку криптовалют із домінуючою часткою біткоїна. І хоча криптовалюта не внесена до національного Реєстру платіжних систем, і є офіційно забороненою для обігу на території України, наша держава ввійшла до п’ятірки країн світу за кількістю користувачів різних біткоїн-гаманців. Визначено сильні сторони біткоїна, які зробили цю криптовалюту зручним міжнародним платіжним засобом з високим інвестиційним потенціалом. Висвітлено недоліки обігу криптовалюти як для пересічних споживачів, так і держави в цілому. Виокремлено основні загрози нерегульованого поширення криптовалюти для національних урядів. Ґрунтуючись на працях провідних зарубіжних науковців і експертів фінансового ринку, систематизовано фактори впливу на ціну біткоїна. Обґрунтовано можливості та перспективи розвитку ринку криптовалюти в Україні. У результаті дослідження встановлено, що криптовалюти зайняли свою нішу в платіжних системах і є конкурентоспроможними та надійними фінансовими інструментами. Зважаючи на динаміку росту капіталізації ринку криптовалют у світі, біткоїн є поки що найуспішнішим прикладом використання віртуальної валюти в інформаційній економіці. Оскільки процес віртуалізації сучасного суспільства невідворотний, економіка нашої держави має підтримувати курс на інноваційність шляхом вирішення низки технічних, економічних та правових питань щодо розвитку ринку криптовалют в Україні, спираючись на досвід провідних європейських країн

Concerning the issue of early diagnostics of low tannin content in faba bean seeds (<i>Vicia faba</i> L.)

Background. The use of faba bean (Vicia faba L.) as a feed and food plant is hindered by the presence of antinutritional substances and in particular phenolic compounds – tannins – in the seed coat. The existence of low-tannin or zero-tannin forms in the faba bean gene pool allows breeders to promote this trait. The aim of this work was to carry out biochemical validation of a known morphological marker of low tannin content and identify relationships of some phenotypic traits characterized by accumulation of phenolic compounds (tannins and anthocyanins) with their concentration for use as additional morphological markers of the low content of these antinutrients in bean seeds.Materials and methods. Associations of the presence/absence of anthocyanin in seedlings, pigmentation on petals, and dark extrafloral nectaries on stipules with the content of tannins and anthocyanins were analyzed in 10 faba bean accessions with different seed coat colors from the VIR collection. The plants were grown and evaluated in Leningrad Province in 2020–2021. Tannins in seeds were assessed using Leventhal’s method. Anthocyanins were analyzed in the green biomass of plants using a spectrophotometric method.Results and conclusion. Different combinations of the studied morphological features associated with the coloration of the studied organs were found. A high positive correlation between the levels of anthocyanins and tannins (r = 0.79) was identified as well as a direct connection of the high value of these traits with the presence of a dark extrafloral nectary on stipules and anthocyanin in seedlings. The absence of anthocyanin staining on seedlings and the absence of dark-colored extrafloral nectaries on stipules can serve as markers of low-tannin genotypes in the early stages of plant development. The light seed coat color that does not darken for a long time may also be the evidence of low tannin content

Selection of an optimal method for screening the collection of narrow-leaved lupine held by the Vavilov Institute for the qualitative and quantitative composition of seed alkaloids

Narrow-leaved lupine (Lupinus аngustifolius L.) is a widely cultivated leguminous forage and green manure crop with a potential for human nutrition. However, the presence of secondary metabolites – alkaloids – in lupine seeds considerably affects the quality of raw produce, reducing its nutritive value; in addition, high concentrations of alkaloids are toxic to humans and animals. Therefore, plant breeders working with lupine need to gain knowledge about the variability of alkaloid content in seeds of different genotypes and search for the sources of their low concentrations in the crop’s gene pool. The collection of narrow-leaved lupine genetic resources held by the N.I. Vavilov Institute of Plant Genetic Resources (VIR) offers wide opportunities for such search by means of mass screening. For its part, largescale gene pool screening requires the selection of an optimal technique to measure alkaloid content in seeds, so that it would be easily reproducible and as little labor-, time- and fund-consuming as possible. The results of the search for such method are presented. Qualitative and quantitative indices were compared when target compounds had been extracted with multicomponent mixtures and individual reagents (chloroform, methanol, etc.) and the extracts analyzed using gas chromatography-mass spectrometry. High-performance liquid chromatography combined with mass spectrometry was also employed. Five major alkaloids were found to be present in all types of extracts: lupanine, 13-hydroxylupanine (dominant ones), angustifoline, sparteine, and isolupanine. The fullest extraction of alkaloids was observed when the extractant with an added alkaline agent was used (425 mg/100 g). The lowest level of extraction was registered with chloroform (216 mg/100 g). The significance of the differences was confirmed statistically

Atomistic model of diopside–K-jadeite (CaMgSi2O6–KAlSi2O6) solid solution

Atomistic model was proposed to describe the thermodynamics of mixing in the diopside–K-jadeite solid solution (CaMgSi2O6–KAlSi2O6). The simulations were based on minimization of the latticeenergies of 800 structures within a 2 × 2 × 4 supercell of C2/c diopside with the compositions betweenCaMgSi2O6 and KAlSi2O6 and with variable degrees of order/disorder in the arrangement of Ca/K cations in M2 site and Mg/Al in Ml site. The energy minimization was performed with the help of a force-field model. The results of the calculations were used to define a generalized Ising model, which included 37 pair interaction parameters. Isotherms of the enthalpy of mixing within the range of 273–2023 K were calculated with a Monte Carlo algorithm, while the Gibbs free energies of mixing were obtained by thermodynamic integration of the enthalpies of mixing. The calculated T–X diagram for the system CaMgSi2O6–KAlSi2O6 at temperatures below 1000 K shows several miscibility gaps, which are separated by intervals of stability of intermediate ordered compounds. At temperatures above 1000 K a homogeneous solid solution is formed. The standard thermodynamic properties of K-adeite (KAlSi2O6) evaluated from quantum mechanical calculations were used to determine location of several mineral reactions with the participation of the diopside–K-jadeite solid solution. The results of the simulations suggest that the low content of KalSi2O6 in natural clinopyroxenes is not related to crystal chemical factors preventing isomorphism, but is determined by relatively high standard enthalpy of this end member

Impact of weather and climate on seed protein and oil content of soybean in the North Сaucasus

For a targeted search of initial breeding material for the quality of soybean seeds, it is necessary to know the patterns of the dependence of the corresponding seed characters on the weather and climatic conditions in a particular region. Global climatic change, the concretization of which is relevant, has a share in this dependence. Thus, the aim of this work was to identify the relationship between the variability of protein and oil content in soybean seeds with climatic parameters in the North Caucasus as well as trends in this variability over a long time period. The study of 1 442 soybean accessions from VIR collection in the Krasnodar region during 1987–2015 had been carried out and the tendencies of the variability of protein and oil content in seeds in this environment were estimated. The regression analysis in differences with forward stepwise selection of variables has been used to construct models for the dependence of the protein and oil content on generalized agrometeorological indices. During 1987–2015, for the period with temperatures above 10 °C, the sums of active temperatures increased by 218 °C/10 years and precipitation decreased by 20.9 mm/10 years. In the dynamics of protein content, a trend has been revealed as an increase by 2.5 % over 10 years, while there is no reliable trend in oil content. The maximum average mean of oil content and the smallest protein were in the middle-maturing accessions (22.2 and 38.8 %), and a relatively high protein content was detected, on average, in the early- (21.6 and 40.0 %) and late-maturing (20.2 and 39.9 %) varieties. The protein content had been increasing with a growth of the duration of the period with temperatures above 22 °C and decreasing with a raise in precipitation over a period of temperatures above 18 °C. The accumulation of oil in seeds was promoted by an increase of the hydrothermal coefficient over the period with temperatures above 19 °C, and, in late-maturating varieties, prevented by a prolonged autumn period with temperatures below 15 °C. Long-term growth in protein content is due to both climatic change and genetic improvement of varieties

Radiation-Induced Cerebro-Ophthalmic Effectsin Humans

: Exposure to ionizing radiation (IR) could affect the human brain and eyes leading to both cognitive and visual impairments. The aim of this paper was to review and analyze the current literature, and to comment on the ensuing findings in the light of our personal contributions in this field. The review was carried out according to the PRISMA guidelines by searching PubMed, Scopus, Embase, PsycINFO and Google Scholar English papers published from January 2000 to January 2020. The results showed that prenatally or childhood-exposed individuals are a particular target group with a higher risk for possible radiation effects and neurodegenerative diseases. In adulthood and medical/interventional radiologists, the most frequent IR-induced ophthalmic effects include cataracts, glaucoma, optic neuropathy, retinopathy and angiopathy, sometimes associated with specific neurocognitive deficits. According to available information that eye alterations may induce or may be associated with brain dysfunctions and vice versa, we propose to label this relationship “eye-brain axis”, as well as to deepen the diagnosis of eye pathologies as early and easily obtainable markers of possible low dose IR-induced brain damage

Systematic Dissection and Trajectory-Scanning Mutagenesis of the Molecular Interface That Ensures Specificity of Two-Component Signaling Pathways

Two-component signal transduction systems enable bacteria to sense and respond to a wide range of environmental stimuli. Sensor histidine kinases transmit signals to their cognate response regulators via phosphorylation. The faithful transmission of information through two-component pathways and the avoidance of unwanted cross-talk require exquisite specificity of histidine kinase-response regulator interactions to ensure that cells mount the appropriate response to external signals. To identify putative specificity-determining residues, we have analyzed amino acid coevolution in two-component proteins and identified a set of residues that can be used to rationally rewire a model signaling pathway, EnvZ-OmpR. To explore how a relatively small set of residues can dictate partner selectivity, we combined alanine-scanning mutagenesis with an approach we call trajectory-scanning mutagenesis, in which all mutational intermediates between the specificity residues of EnvZ and another kinase, RstB, were systematically examined for phosphotransfer specificity. The same approach was used for the response regulators OmpR and RstA. Collectively, the results begin to reveal the molecular mechanism by which a small set of amino acids enables an individual kinase to discriminate amongst a large set of highly-related response regulators and vice versa. Our results also suggest that the mutational trajectories taken by two-component signaling proteins following gene or pathway duplication may be constrained and subject to differential selective pressures. Only some trajectories allow both the maintenance of phosphotransfer and the avoidance of unwanted cross-talk