Аналіз застосовності комерційно доступного хімічного простору для використання у 19F ЯМР FAXS методі на прикладі НВП «Єнамін»

Aim. To analyze commercially available fluorine containing compounds for the possibility of their use in the 19F NMR FAXS method.Materials and methods. The selection of fluorine-containing fragments for the study was performed using 3.9 million instock screening compounds and 248,000 in-stock building-blocks from Enamine Ltd library. The selection and classification of the compounds was carried out using the DataWarrior and KNIME software. The Fluorinated Fragments library of Enamine Ltd. containing 6377 compounds, was also analyzed. To analyze the abovementioned sets of substances, the multistep workflows specially designed were used.Results and discussion. As a result of applying the workflow developed to the compound sets (both screening compounds and building blocks), 13 800 compounds were selected and further classified according to the presence of one out of 12 fluorine-containing groups. The Fluorinated Fragments library was also subjected to a similar workflow. For the latter, 8 out of 12 fluorine-containing groups were identified. Additionally, experimental 19F NMR chemical shift values for Fluorinated Fragments library compounds spectra were analyzed. It has been found that some structural classes have areas of chemical shifts intersection. On the other hand, the ranges from –40 to –60 ppm and beyond –160 ppm are free from any group of compounds from the library analyzed.Conclusions. The analysis has shown that commercially available fluorine-containing fragments do not satisfy the needs of the 19F NMR FAXS method, and further expansion of the chemical space of fluorine-containing compounds by increasing their diversity is required.Мета. Проаналізувати комерційно доступні флуоровмісні сполуки на можливість їх застосування в конкурентному скринінгу за допомогою 19F ЯМР FAXS методу.Матеріали та методи. Відбір флуоровмісних фрагментів для дослідження проводили з використанням наявних на складі компанії ТОВ «НВП «Єнамін» 3,9 млн скринінгових сполук та 248000 будівельних блоків. Відбір та розподіл сполук по групах виконували за допомогою програм DataWarrior та KNIME. Проаналізували бібліотеку флуорованих фрагментів ТОВ «НВП «Єнамін», що містить 6377 сполук. Для аналізу вищезазначених наборів речовин використовували спеціально розроблені багатоступеневі алгоритми.Результати та їх обговорення. У результаті застосування розробленого алгоритму до скринінгових сполук та будівельних блоків відібрано 13800 представників, які додатково класифіковано за наявністю однієї з 12 флуоровмісних груп. Бібліотеку флуорованих фрагментів також піддано подібній процедурі. Для останньої групи досліджуваних сполук ідентифіковано наявність 8 з 12 флуоровмісних фрагментів. Крім того, проаналізовано експериментальні значення хімічного зсуву, отримані із 19F ЯМР спектрів бібліотеки флуорованих фрагментів. З’ясовано, що деякі структурні класи мають зони перетину хімічних зсувів. З іншого боку, у діапазонах від –40 до –60 м.д. і більше –160 м.д. не представлено жодної сполуки з аналізованої бібліотеки.Висновки. Аналіз засвідчив, що наявні комерційно доступні флуоровмісні фрагменти не задовольняють потреби 19F NMR FAXS методу, а тому необхідно розширювати хімічний простір флуоровмісних сполук шляхом збільшення їх різноманіття

Biological resources of the Hyssopus l on the south of European Russia and prospects of its introduction

The south of European Russia (geographically - the southern part of the Central Russian Upland) has large biological and plant genetic resources. There is a concept considering the region as the second anthropogenic microgen center of formation of economically valuable plants. In the south of the Central Russian Upland, the genus Hyssopus L. is represented by two species: Hyssopus cretaceus Dubjan. and Hyssopus officinalis L. Accomplished the study of biological resources of species of the genus Hyssopus L. in vivo and in vitr

Remote atomic clock synchronization via satellites and optical fibers

In the global network of institutions engaged with the realization of International Atomic Time (TAI), atomic clocks and time scales are compared by means of the Global Positioning System (GPS) and by employing telecommunication satellites for two-way satellite time and frequency transfer (TWSTFT). The frequencies of the state-of-the-art primary caesium fountain clocks can be compared at the level of 10e-15 (relative, 1 day averaging) and time scales can be synchronized with an uncertainty of one nanosecond. Future improvements of worldwide clock comparisons will require also an improvement of the local signal distribution systems. For example, the future ACES (atomic clock ensemble in space) mission shall demonstrate remote time scale comparisons at the uncertainty level of 100 ps. To ensure that the ACES ground instrument will be synchronized to the local time scale at PTB without a significant uncertainty contribution, we have developed a means for calibrated clock comparisons through optical fibers. An uncertainty below 50 ps over a distance of 2 km has been demonstrated on the campus of PTB. This technology is thus in general a promising candidate for synchronization of enhanced time transfer equipment with the local realizations of UTC . Based on these experiments we estimate the uncertainty level for calibrated time transfer through optical fibers over longer distances. These findings are compared with the current status and developments of satellite based time transfer systems, with a focus on the calibration techniques for operational systems

Curing of epoxy resin DER-331by Hexakis (4-acetamidophenoxy) cyclotriphosphazene and properties of the prepared composition

The method of optical wedge revealed that the optimum temperature for compatibility of hexakis(4-acetamidophenoxy)cyclotriphosphazene (ACP) and DER-331 epoxy resin is in the range of 220–260◦C. The interdiffusion time of components at these temperatures is about 30 min. The TGA and differential scanning calorimetry (DSC) methods revealed the curing temperature of 280◦C for thiscomposition. IRspectroscopyconfirmedthatthereactionbetweentheresinandACPiscompleted within 10 mi

Controlling circular polarization of light emitted by quantum dots using chiral photonic crystal slab

We study the polarization properties of light emitted by quantum dots that are embedded in chiral photonic crystal structures made of achiral planar GaAs waveguides. A modification of the electromagnetic mode structure due to the chiral grating fabricated by partial etching of the wave\-guide layer has been shown to result in a high circular polarization degree $\rho_c$ of the quantum dot emission in the absence of external magnetic field. The physical nature of the phenomenon can be understood in terms of the reciprocity principle taking into account the structural symmetry. At the resonance wavelength, the magnitude of $|\rho_c|$ is predicted to exceed 98%. The experimentally achieved value of $|\rho_c|=81$% is smaller, which is due to the contribution of unpolarized light scattered by grating defects, thus breaking its periodicity. The achieved polarization degree estimated removing the unpolarized nonresonant background from the emission spectra can be estimated to be as high as 96%, close to the theoretical prediction

Laser acceleration of ion beams

We consider methods of charged particle acceleration by means of high-intensity lasers. As an application we discuss a laser booster for heavy ion beams provided, e.g. by the Dubna nuclotron. Simple estimates show that a cascade of crossed laser beams would be necessary to provide additional acceleration to gold ions of the order of GeV/nucleon.Comment: 4 pages, 4 figures, Talk at the Helmholtz International Summer School "Dense Matter in heavy Ion Collisions and Astrophysics", August 21 - September 1, 2006, JINR Dubna, Russia; v2, misprints correcte

Mobilization of genetic resources of Hyssopus Officinalis L. for selection for seed productivity and essential oil content

We studied 52 varieties and breeding samples from the collection of medicinal hyssop in the Botanical Garden of Belgorod State University (2017-2020). Of these, 16 varieties of domestic selection included in the State Register of Breeding Achievements approved for use in the Russian Federation, as well as 33 breeding samples obtained by selection from wild cenopopulations of the Volokonovsky district of the Belgorod region and 3 breeding samples obtained by selection from local selection varieties ‘Volokonovsky’ (2 samples) and ‘Lazar’ (1 sample

BBGKY kinetic approach for an e-e+gamma plasma created from the vacuum in a strong laser-generated electric field: The one-photon annihilation channel

In the present work a closed system of kinetic equations is obtained from the truncation of the BBGKY hierarchy for the description of the vacuum creation of an electron - positron plasma and secondary photons due to a strong laser field. This truncation is performed in the Markovian approximation for the one-photon annihilation channel which is accessible due to the presence of the strong external field. Estimates of the photon production rate are obtained for different domains of laser field parameters (frequency nu and field strength E). A huge quantity of optical photons of the quasiclassical laser field is necessary to satisfy the conservation laws of energy and momentum of the constituents (e-, e+, gamma) in this channel. Since the number of these optical photons corresponds to the order of perturbation theory, a vanishingly small photon production rate results for the optical region and strongly subcritical fields E << E_c. In the gamma-ray region nu <~ m the required number of laser photons is small and the production rate of photons from the one-photon annihilation process becomes accessible to observations for subcritical fields E <~ E_c. In the infrared region the photon distribution has a 1/k spectrum typical for flicker noise.Comment: 14 pages, 1 figure, one reference with referring text added and one citation correcte

Nucleon-induced fission cross-sections of tantalum and separated tungsten isotopes and "compound nucleus" effect in intermediate energy region

Neutron- and proton-induced fission cross-sections of separated isotopes of tungsten (182W, 183W, 184W, and 186W) and 181Ta relative to 209Bi have been measured in the incident nucleon energy region 50 - 200 MeV using fission chambers based on thin-film breakdown counters (TFBC) using quasi-monoenergetic neutrons from the 7Li(p,n) reaction and at the proton beams of The Svedberg Laboratory (TSL), Uppsala University (Uppsala, Sweden). The results are compared with predictions by the CEM03.01 event generator, as well as with the recent data for nuclei in the lead-bismuth region. The effect of "compound nucleus" in the intermediate energy region is discussed, displaying in exponential dependence of nucleon-induced fission cross-sections on the parameter Z^2/A of the composite system (projectile+target nucleus), and in other characteristics of the fission process for which parameter Z^2/A plays a role similar to the one of the usual liquid-drop parameter Z^2/A of compound nuclei.Comment: 4 pages, 3 figures, 2 tables, only pdf file, to be published in Proc. Int. Conf. on Nucl. Data for Sci. and Technology (ND2007), Nice, France, April 22-27, 200