Исследование равновесной структуры молекулы 3,4-дицианофуроксана

Objectives. The study set out to determine the equilibrium parameters of the 3,4-dicyanofuroxan molecule by means of molecule geometry optimization by quantum chemistry methods, verify the adequacy of the methods used, and compare the obtained results with X-ray diffraction analysis (XRD) and gas electron diffraction (GED) data.Methods. Quantum chemical calculations were carried out using B3LYP, MP2, and CCSD(T) methods with 6-31G(d,p), cc-pVTZ, and aug-cc-pVTZ basis sets.Results. The equilibrium molecular structure of 3,4-dicyanofuroxan was refined by means of quantum chemical calculations using the Gaussian09 program. The geometrical parameters were compared with the structure of this compound in the solid phase and a number of related compounds in gas and solid phases. It was theoretically established that the planar equilibrium structure of the dicyanofuroxan molecule has CS symmetry. The structure of the free dicyanofuroxan molecule was found to differ depending on the phase. The B3LYP and CCSD(T) methods describe the molecular structure of dicyanofuroxan more accurately than the MP2 method. A regularity was revealed, according to which an increase in the basis, as a rule, leads to a better agreement of the geometry, regardless of the functional.Conclusions. The calculations performed are in good agreement with the literature data and results of joint analysis by GED and XRD. The effect of cyano substituents on the ring geometry is observed in comparison with the literature data for the dicyanofuroxan molecule. For the molecule in question, it is better to use the B3LYP/aug-cc-pVTZ method. The values of geometric parameters obtained by this method are in better agreement with the structure in the gas phase. The discrepancies with the experimental XRD results may be due to interactions in the crystal structure. Differences in the geometric parameters obtained on the basis of different functionals and bases make this molecule interesting for experimental structural studies using GED or microwave spectroscopy, which will permit the identification of optimal methods and bases for obtaining the geometric parameters of furoxan class molecules.Цели. Определение равновесных параметров молекулы 3,4-дицианофуроксана посредством оптимизации геометрии молекулы методами квантовой химии, проверка адекватности используемых методов, а также сопоставление полученных результатов с данными рентгенодифракционного анализа (РСА) и газовой электронографии (ГЭ) родственных соединений.Методы. Квантовохимические расчеты методами B3LYP, MP2 и CCSD(T) c базисными наборами 6-31G(d,p), cc-pVTZ и aug-cc-pVTZ.Результаты. Уточнена равновесная молекулярная структура 3,4-дициано- фуроксана с помощью квантово-химических расчетов в программе Gaussian09. Проведено сравнение геометрических параметров со структурой данного соединения в твердой фазе и с рядом родственных соединений в газовой и твердой фазе. Теоретически установлено, что равновесная структура молекулы дицианофуроксана является плоской и имеет симметрию CS. Установлено, что структура свободной молекулы дицианофуроксана в зависимости от фазы различается. Методы CCSD(T) и B3LYP точнее описывает молекулярную структуру дицианофуроксана по сравнению с методом MP2. Выявлена закономерность, согласно которой увеличение базиса, как правило, приводит к лучшему согласованию геометрии независимо от функционала.Выводы. Проведенные расчеты хорошо согласуются с литературными данными, а также результатами совместного анализа методами ГЭ и РСА. Влияние циано-заместителей на геометрию кольца наблюдается в сравнении с литературными данными для молекулы дицианофуроксана. Для рассматриваемой молекулы лучше использовать метод B3LYP/aug-cc-pVTZ. Значения геометрических параметров, полученные этим методом, лучше согласуются со структурой в газовой фазе. Расхождения с экспериментальными результатами РСА могут быть обусловлены взаимодействиями в кристаллической структуре. Различия в геометрических параметрах, полученных на основе разных функционалов и базисов, делают эту молекулу интересной для проведения экспериментального структурного исследования методами ГЭ или микроволновой спектроскопии, что позволит в будущем найти оптимальные методы и базисы для получения геометрических параметров молекул класса фуроксанов

Continuous selections of multivalued mappings

This survey covers in our opinion the most important results in the theory of continuous selections of multivalued mappings (approximately) from 2002 through 2012. It extends and continues our previous such survey which appeared in Recent Progress in General Topology, II, which was published in 2002. In comparison, our present survey considers more restricted and specific areas of mathematics. Note that we do not consider the theory of selectors (i.e. continuous choices of elements from subsets of topological spaces) since this topics is covered by another survey in this volume

Concept of use of comprehensive fertilizers of long-term action on the basis of waste processing of potassium-magnesium ore as a new paradigm in improving soil fertility

Technology for the production and use of new multiple slow-release fertilizers from clay-salt waste (sludge) remaining as a result of potassium fertilizers production from natural K-Mg ores, is elaborated in Perm Federal Research Center. The main processes in the technology are waste enrichment and subsequent high-temperature calcination of the enriched concentrate. As a result, the product, received the name the calcine of clay-salt sludge, was formed having the properties of multiple slow-release fertilizer and ameliorant. Laboratory and field experiments on the calcine use as a potassium fertilizer were fulfilled. The studied crops were spring wheat, barley, and potato. The experimental scheme included such treatments: control (without fertilizers), NP – background; NP + KCl and NP + calcine. The use of calcine for grain crops (wheat, barley) on the NP background promoted the yield gains by 1.7–1.9 t/ha compared with the control, the use of standard NPK fertilizers – by 1.8–2.0 t/ha, the difference was within the error of the experiment (HCP05 = 0.21; 0.38 t/ha). The content of nitrogen, phosphorus and potassium in the grain and straw of both crops in the treatments using calcine was approximately equal to the variants using standard fertilizer and significantly higher compared to the control. Differences between calcine treatments were not significant. The application of N90P90 and full mineral fertilizer (N90P90K90) contributed to the yield increase of potato tubers by 1.43–4.51 t/ha respectively. The use of unconventional potassium fertilizer – calcine on the background of NP was not inferior in efficiency to the use of traditional fertilizer – potassium chloride. The quality parameters of the potato crop (dry matter and starch content in tubers, the content of heavy metals) were also not inferior compared to the use of traditional potassium fertilizer. The use of calcine for potato and cereals in rates equal to K60-120 did not lead to deterioration of the fertility indicators of sod-podzolic soil. Upon receipt of the cinder, one can use the additional unlimited set of components. In other words, this is a conceptual model for creating new types of mineral fertilizers with desired properties for different soil and climatic conditions and crops with different requirements for mineral nutrition

Is diet partly responsible for differences in COVID-19 death rates between and within countries?

Correction: Volume: 10 Issue: 1 Article Number: 44 DOI: 10.1186/s13601-020-00351-w Published: OCT 26 2020Reported COVID-19 deaths in Germany are relatively low as compared to many European countries. Among the several explanations proposed, an early and large testing of the population was put forward. Most current debates on COVID-19 focus on the differences among countries, but little attention has been given to regional differences and diet. The low-death rate European countries (e.g. Austria, Baltic States, Czech Republic, Finland, Norway, Poland, Slovakia) have used different quarantine and/or confinement times and methods and none have performed as many early tests as Germany. Among other factors that may be significant are the dietary habits. It seems that some foods largely used in these countries may reduce angiotensin-converting enzyme activity or are anti-oxidants. Among the many possible areas of research, it might be important to understand diet and angiotensin-converting enzyme-2 (ACE2) levels in populations with different COVID-19 death rates since dietary interventions may be of great benefit.Peer reviewe

Clinical features of post-COVID-19 period. Results of the international register “Dynamic analysis of comorbidities in SARS-CoV-2 survivors (AKTIV SARS-CoV-2)”. Data from 6-month follow-up

Aim. To study the clinical course specifics of coronavirus disease 2019 (COVID-19) and comorbid conditions in COVID-19 survivors 3, 6, 12 months after recovery in the Eurasian region according to the AKTIV register. Material and methods.The AKTIV register was created at the initiative of the Eurasian Association of Therapists. The AKTIV register is divided into 2 parts: AKTIV 1 and AKTIV 2. The AKTIV 1 register currently includes 6300 patients, while in AKTIV 2 — 2770. Patients diagnosed with COVID-19 receiving in- and outpatient treatment have been anonymously included on the registry. The following 7 countries participated in the register: Russian Federation, Republic of Armenia, Republic of Belarus, Republic of Kazakhstan, Kyrgyz Republic, Republic of Moldova, Republic of Uzbekistan. This closed multicenter register with two nonoverlapping branches (in- and outpatient branch) provides 6 visits: 3 in-person visits during the acute period and 3 telephone calls after 3, 6, 12 months. Subject recruitment lasted from June 29, 2020 to October 29, 2020. Register will end on October 29, 2022. A total of 9 fragmentary analyzes of the registry data are planned. This fragment of the study presents the results of the post-hospitalization period in COVID-19 survivors after 3 and 6 months. Results. According to the AKTIV register, patients after COVID-19 are characterized by long-term persistent symptoms and frequent seeking for unscheduled medical care, including rehospitalizations. The most common causes of unplanned medical care are uncontrolled hypertension (HTN) and chronic coronary artery disease (CAD) and/or decompensated type 2 diabetes (T2D). During 3- and 6-month follow-up after hospitalization, 5,6% and 6,4% of patients were diagnosed with other diseases, which were more often presented by HTN, T2D, and CAD. The mortality rate of patients in the post-hospitalization period was 1,9% in the first 3 months and 0,2% for 4-6 months. The highest mortality rate was observed in the first 3 months in the group of patients with class II-IV heart failure, as well as in patients with cardiovascular diseases and cancer. In the pattern of death causes in the post-hospitalization period, following cardiovascular causes prevailed (31,8%): acute coronary syndrome, stroke, acute heart failure. Conclusion. According to the AKTIV register, the health status of patients after COVID-19 in a serious challenge for healthcare system, which requires planning adequate health system capacity to provide care to patients with COVID-19 in both acute and post-hospitalization period

The structure of the 1,3,5-tribromo-, 1,3,5-trichloro-, and 1,3,5-trimethyl-2,4,6-trinitrobenzene molecules according to gas electron diffraction data and quantum-mechanical calculations

Dorofeeva OV, Vishnevskii YV, Shishkov IF, Vilkov LV. The structure of the 1,3,5-tribromo-, 1,3,5-trichloro-, and 1,3,5-trimethyl-2,4,6-trinitrobenzene molecules according to gas electron diffraction data and quantum-mechanical calculations. Russian Journal of Physical Chemistry. 2005;79(11):1814-1820