Diffusion control of the Diels-Alder reaction rate at elevated pressures

The influence of the temperature and external pressure on the rate of the Diels-Alder reaction between 9,10-dimethylanthracene and maleic anhydride was studied in the series of solvents with wide intervals of viscosity (0.3-43.2 mPa s), dielectric constant (2-38), and internal pressure (3-8.8 kbar). At a standard pressure these properties of the solvent exert a weak and irregular effect on the reaction rate constant and activation enthalpy and entropy. The effect of the external pressure on the rate constant was studied in a high-pressure (up to 1 kbar) optical cell in acetonitrile and silicon oil and in a barostat cell (up to 6 kbar, toluene, silicon oil). Close values of the activation volume were obtained in all solvents. In toluene the reaction rate increases smoothly in the whole pressure interval. In more viscous silicon oil a similar dependence is observed up to 3 kbar, and the reaction rate decreases sharply with the further increase in the pressure and viscosity because of the diffusion control of the process

Course of COVID-19 in Patients with Inflammatory Bowel Disease: Regional Experience

Aim: to study the course of COVID-19 in patients with inflammatory bowel diseases (IBD) using the example of the region of the Republic of Tatarstan.Material and methods. The study included 101 patients diagnosed with IBD and COVID-19, who were observed in two infectious diseases hospitals in Kazan (Republican Clinical Hospital of the Ministry of Health of the Republic of Tatarstan and City Clinical Hospital No. 7) and on an outpatient basis from April 2020 to March 2022. All patients underwent physical examination, laboratory and instrumental diagnostic methods, including a PCR test for SARSCoV-2. Chest computed tomography was performed in patients with clinical signs of moderate to severe COVID-19.Results. Ulcerative colitis (UC) was diagnosed in 60 (59.4 %) patients, Crohn's disease (CD) — in 41 (40.6 %) patients. The mean age of the patients was 41.0 ± 14.7 years, of which 59 (58.4 %) were men and 42 (41.6 %) were women. A comparative analysis of patients with and without IBD and CT-verified lung disease was carried out. It was found that the development of viral pneumonia was influenced by age over 55 years (39.2 ± 9.7 vs. 46.3 ± 10.6, p < 0.05), increased Body Mass Index (BMI) (23.1 ± 5.35 vs. 30.25 ± 6.17, p < 0.05), hypertension (6 (8.3 %) vs. 8 (27.6 %), p < 0.05), diabetes mellitus (2 (2.7 %) vs. 5 (17.2 %), p < 0.05), the use of corticosteroids in the treatment of IBD (8 (11.1 %) vs. 10 (34.5 %), p < 0.05). In a comparative analysis of patients with IBD and COVID-19 from the SECURE-IBD database and own data, it was found that the average age of patients was comparable (42.7 vs 41.0). At the same time, in our group of male patients, there were slightly more people with DM, increased BMI, and an active course of IBD. The proportion of hospitalized patients was higher. In our cohort, there were fewer patients receiving biological therapy, but more patients on 5-aminosalicylic acid (5-ASA) and systemic corticosteroids. At the same time, lethal outcomes were comparable.Conclusion. In patients with IBD, the development of viral pneumonia was influenced by known risk factors for COVID-19: age over 55 years (p < 0.05, odds ratio (OR) 3.153), increased BMI (p < 0.05, OR 1.667), hypertension  (p < 0.05, OR 2.724), diabetes (p < 0.05, OR 1.489), as well as the use of systemic corticosteroids (p < 0.05, OR 1.5)

Lattice vibrations of alpha'-NaV2O5

We have measured far infrared reflectance and transmittance spectra as well as Raman scattering spectra of \alpha'-NaV2O5 single crystals for all the principal polarizations. The temperature range above the phase transition temperature T_c=35 K was investigated, mainly. On the basis of this experimental study and of the lattice dynamics calculations we conclude that the symmetry of NaV2O5 in the high temperature phase is described by the centrosymmetric D_{2h}^{13} space group. The assignment of the observed phonons is given. Values of dielectric constants are obtained from the infrared data. Asymmetric shapes of several infrared lines as well as higher order infrared vibrational spectra are discussed. The crystal field energy levels of the 3d electron localized at the V^{4+} site have been calculated in the framework of the exchange charge model using the values of effective charges obtained from the lattice dynamics calculations. According to the results of these calculations, the earlier observed broad optical bands in the region of 1 eV can be interpreted as phonon assisted d-d transitions.Comment: 12 pages, 8 figures, 5 tables; submitted to PR

МОРАЛЬНО-НРАВСТВЕННЫЙ ПОТЕНЦИАЛ ФОРМИРОВАНИЯ ДУХОВНОЙ КУЛЬТУРЫ МОЛОДЕЖИ (НА МАТЕРИАЛАХ РЕСПУБЛИКИ ТАТАРСТАН)

A special place in identifying priorities in Tatarstan ideology occupies by socio-political sphere’s values. The political culture of a society grows on the foundation of his general culture. Music, as part of the general culture and moral potential of personality, contributes to the formation of spiritual and cultural development of the society.Особое место при выявлении приоритетов татарстанской идеологии занимают ценности общественно-политической сферы. Политическая культура общества вырастает на фундаменте его общей культуры. Музыка, являясь частью общей культуры и морально-нравственным потенциалом личности, вносит свой вклад в формирование духовно-культурного развития общества

Diffusion control of the Diels-Alder reaction rate at elevated pressures

The influence of the temperature and external pressure on the rate of the Diels-Alder reaction between 9,10-dimethylanthracene and maleic anhydride was studied in the series of solvents with wide intervals of viscosity (0.3-43.2 mPa s), dielectric constant (2-38), and internal pressure (3-8.8 kbar). At a standard pressure these properties of the solvent exert a weak and irregular effect on the reaction rate constant and activation enthalpy and entropy. The effect of the external pressure on the rate constant was studied in a high-pressure (up to 1 kbar) optical cell in acetonitrile and silicon oil and in a barostat cell (up to 6 kbar, toluene, silicon oil). Close values of the activation volume were obtained in all solvents. In toluene the reaction rate increases smoothly in the whole pressure interval. In more viscous silicon oil a similar dependence is observed up to 3 kbar, and the reaction rate decreases sharply with the further increase in the pressure and viscosity because of the diffusion control of the process

Diffusion control of the Diels-Alder reaction rate at elevated pressures

The influence of the temperature and external pressure on the rate of the Diels-Alder reaction between 9,10-dimethylanthracene and maleic anhydride was studied in the series of solvents with wide intervals of viscosity (0.3-43.2 mPa s), dielectric constant (2-38), and internal pressure (3-8.8 kbar). At a standard pressure these properties of the solvent exert a weak and irregular effect on the reaction rate constant and activation enthalpy and entropy. The effect of the external pressure on the rate constant was studied in a high-pressure (up to 1 kbar) optical cell in acetonitrile and silicon oil and in a barostat cell (up to 6 kbar, toluene, silicon oil). Close values of the activation volume were obtained in all solvents. In toluene the reaction rate increases smoothly in the whole pressure interval. In more viscous silicon oil a similar dependence is observed up to 3 kbar, and the reaction rate decreases sharply with the further increase in the pressure and viscosity because of the diffusion control of the process

Diffusion control of the Diels-Alder reaction rate at elevated pressures

The influence of the temperature and external pressure on the rate of the Diels-Alder reaction between 9,10-dimethylanthracene and maleic anhydride was studied in the series of solvents with wide intervals of viscosity (0.3-43.2 mPa s), dielectric constant (2-38), and internal pressure (3-8.8 kbar). At a standard pressure these properties of the solvent exert a weak and irregular effect on the reaction rate constant and activation enthalpy and entropy. The effect of the external pressure on the rate constant was studied in a high-pressure (up to 1 kbar) optical cell in acetonitrile and silicon oil and in a barostat cell (up to 6 kbar, toluene, silicon oil). Close values of the activation volume were obtained in all solvents. In toluene the reaction rate increases smoothly in the whole pressure interval. In more viscous silicon oil a similar dependence is observed up to 3 kbar, and the reaction rate decreases sharply with the further increase in the pressure and viscosity because of the diffusion control of the process

Al2O3/GeO2/P2O5/F-Doped Silica Large-Mode-Area Optical Fibers for High-Power Single-Frequency Radiation Delivery

A new design of a passive optical fiber waveguide with a large mode area (LMA) and strong stimulated Brillouin scattering (SBS) suppression is proposed. The fiber core consists of two parts: a central one, doped with Al2O3 and GeO2, and a peripheral one, doped with P2O5 and F. The doping profiles form a gradient-increasing profile of the acoustic refractive index, which effectively implements the acoustic multimode SBS suppression method. Measurements of the SBS gain spectrum and SBS threshold power were carried out, showing an increase in the SBS threshold of no less than 11 dB compared to a conventional uniformly doped passive LMA fiber. © 2023 by the authors.Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Hyperfine structure of submillimeter EPR spectra of non-kramers lanthanide ions in crystals

The hyperfme structures of submillimeter EPR spectra of CsCdBr3:Tm3+ and CaF2:Dy2+ single crystals have been resolved and analyzed. The crystal field parameters and the magnetic hyperfine constants are obtained from fitting the envelopes of the simulated spectra to the measured signals. From the specific peculiarities of the hyperfine structure the energy of the interion interaction in the thulium dimers in CsCdBr3 is determined. The isotopic shift of the crystal field splitting in energy patterns of dysprosium isotopes in CaF2 is estimated. © Springer-Verlag 1998 Printed in Austria