Catalytic and physico-chemical properties of La1?xSrxCoO3 perovskites

Catalytic properties of strontium-substituted lanthanum cobaltites La_1–xSr_xCoO₃ in the reaction of CO oxidation were compared with the data about chemical composition of the surface and bulk defect structure. It was found that (1) the initial catalytic activity correlates with the cobalt concentration on the surface; (2) surface composition differs from the bulk one; (3) the steady-state activity is proportional to the density of bulk extended defects. Under our experimental conditions no role of point defects was noted.     

Virtual Screening and Hit Selection of Natural Compounds as Acetylcholinesterase Inhibitors

Acetylcholinesterase (AChE) is one of the classical targets in the treatment of Alzheimer’s disease (AD). Inhibition of AChE slows down the hydrolysis of acetycholine and increases choline levels, improving the cognitive function. The achieved success of plant-based natural drugs acting as AChE inhibitors, such as galantamine (GAL) from Galanthus genus and huperzine A from Huperzia serrate (approved drug in China), in the treatment of AD, and the fact that natural compounds (NCs) are considered as safer and less toxic compared to synthetic drugs, led us to screen the available NCs (almost 150,000) in the ZINC12 database for AChE inhibitory activity. The compounds were screened virtually by molecular docking, filtered for suitable ADME properties, and 32 ligands from 23 structural groups were selected. The stability of the complexes was estimated via 1 μs molecular dynamics simulation. Ten compounds formed stable complexes with the enzyme and had a vendor and a reasonable price per mg. They were tested for AChE inhibitory and antioxidant activity. Five compounds showed weak AChE inhibition and three of them exhibited high antioxidant activity.     

Synthesis and Antiviral Properties against SARS-CoV-2 of Epoxybenzooxocino[4,3-b]Pyridine Derivatives

The COVID-19 pandemic is ongoing as of mid-2022 and requires the development of new therapeutic drugs, because the existing clinically approved drugs are limited. In this work, seven derivatives of epoxybenzooxocinopyridine were synthesized and tested for the ability to inhibit the replication of the SARS-CoV-2 virus in cell cultures. Among the described compounds, six were not able to suppress the SARS-CoV-2 virus’ replication. One compound, which is a derivative of epoxybenzooxocinopyridine with an attached side group of 3,4-dihydroquinoxalin-2-one, demonstrated antiviral activity comparable to that of one pharmaceutical drug. The described compound is a prospective lead substance, because the half-maximal effective concentration is 2.23 μg/μL, which is within a pharmacologically achievable range.     

Novel Inhibitors of 2′-O-Methyltransferase of the SARS-CoV-2 Coronavirus

The COVID-19 pandemic is still affecting many people worldwide and causing a heavy burden to global health. To eliminate the disease, SARS-CoV-2, the virus responsible for the pandemic, can be targeted in several ways. One of them is to inhibit the 2′-O-methyltransferase (nsp16) enzyme that is crucial for effective translation of viral RNA and virus replication. For methylation of substrates, nsp16 utilizes S-adenosyl methionine (SAM). Binding of a small molecule in the protein site where SAM binds can disrupt the synthesis of viral proteins and, as a result, the replication of the virus. Here, we performed high-throughput docking into the SAM-binding site of nsp16 for almost 40 thousand structures, prepared for compounds from three libraries: Enamine Coronavirus Library, Enamine Nucleoside Mimetics Library, and Chemdiv Nucleoside Analogue Library. For the top scoring ligands, semi-empirical quantum-chemical calculations were performed, to better estimate protein–ligand binding enthalpy. Relying upon the calculated binding energies and predicted docking poses, we selected 21 compounds for experimental testing.     

Strain localization under dynamic loading

A spallation model of strain localization is suggested according to which localization bands under pulsed loading result from unloading wave interference such that negative stresses in the extension zone are lower than the ultimate strength of the material. The temperature in the localization band is estimated to be close to the environmental temperature.     

Thermochemical properties of new N,O-chelate Sc, Eu, and Tb complexes for OLED-devices

A new class of Sc, Eu, and Tb complexes with N,O-chelate ligands was synthesized for the first time. The mass spectra, thermogravimetric analysis, differential scanning calorimetry data, as well as the data on the saturated vapor pressure of the compounds were obtained. The main thermochemical parameters of the compounds were calculated.     

DMSA and its complexes with radioisotopes: review

Meso-2,3-dimercaptosuccinic acid (DMSA) forms stable complexes with a remarkable wide range of metal ions. This relatively small molecule has attracted increasing attention in the field of radiopharmacy, treatment of heavy metal intoxications and nanoparticles preparation. In this review detailed summary of all physical, chemical and biological properties of DMSA and its complex compounds with ^99mTc, ^186/188Re, ¹⁶⁶Ho, ¹⁷⁷Lu and ⁹⁰Y is provided. The clinical utilisation of DMSA complexes in the nuclear medicine and its use for treatment of heavy metal intoxication is briefly summarised. The aspects of its application in the field of nanoparticles preparation is behind the scope of this review, therefore it is only shortly described.     

X-ray amplification in intense ultrashort KrF laser–Xe cluster interactions

In earlier work, a time-dependent, ionization dynamic model of a cluster of xenon atoms was constructed [2], [3] in an effort to determine conditions under which the X-ray line amplification data that was observed experimentally at wavelengths between 2.71 and 2.88 Å [1] could be replicated. Model calculations showed that, at laser intensities greater than 10¹⁹ W/cm², the outermost N-shell electrons of xenon would be stripped away by tunnel ionization in less than a femtosecond. They also showed that L-shell electrons within the resulting cluster of Ni-like ions could be photoionized at a sufficient rate as to generate population inversions between these hole states and the states they radiatively decayed into. These inversions only lasted for several femtoseconds, and they were generated early in time when the cluster was being rapidly heated and the cluster's density was rapidly evolving, but was still high. They were seen to depend on the heating and expansion dynamics of the cluster, which had not been modeled in detail in this early work. In this paper, molecular dynamics calculations are described in which the rapidly evolving temperatures and ion densities of an intensely laser-heated cluster are calculated for different peak laser intensities and for two different sized xenon nano-clusters. This data is then used as an input to the ionization dynamic calculations in order to determine the influence of cluster size and of peak laser intensity on the gain coefficient calculations. In these calculations, inner-shell photoionization rates are shaped by the temperature and density dependence of the bremsstrahlung emissions under the assumption that these emissions drive the photoionizations. This shaping produces calculated gain coefficients that agree well with the measured ones.     

Mu+H2 and Mu+D2 reaction kinetics from 480 To 675 K

This paper reports preliminary new measurements of the thermal reaction rate constants of muonium (Mu) with hydrogen and deuterium gases in the range 480–675 K. From Arrhenius plots of the measured reaction rate constants new values of the pre-exponential factors log₁₀ (A) and activation energies E_a have been determined for these reactions, representing a significant improvement over earlier results.