Aromaticity is one of fundamental characteristics of unsaturated organic molecules, which significantly determine chemical properties. By definition, aromatic molecules mast be cyclic, planar, have a complete conjugated π- electrons, and the number of π-electrons mast be 4n+2, where n is any integer number. Aromatic molecules are chemically very stable and have low reactive ability. In the contrary, anti-aromatic molecules, which have conjugated 4n π-electrons, highly unstable, preferably isomerize into aromatic composition, and demonstrate high chemical activity. In this paper, we study properties of typical aromatic and anti-aromatic compounds on the example of pentalene, phenylacetylene, and benzocyclobutadiene, and compare the change of their photochemical properties with changing the electric charge (under the single and double ionization). It was found that aromaticity of the molecules is really changing due to the loss of electrons. Dissociation reactions of pentalene, phenylacetylene and benzocyclobutadiene, as far as their cationic and dicationic forms were investigated. The effect of Coulomb repulsion in doubly ionized molecules also has been observed.
It is well known that the processes of vertical propagation and dissipation of acoustic-gravity waves (AGWs) play an important role in the realization of connections between the dynamic processes in different layers of the atmosphere. This work presents the results of lidar probing of tropospheric aerosols, performed in Kaliningrad, Russia (54°N, 20 °E). The observations used a two-wave atmospheric lidar (with wavelengths of 532 and 1064 nm), which allows investigation of properties of troposphere up to the altitudes of 10-12 km. During the observations, the intensity of the lidar signal scattered in the troposphere was determined. Measurements that were carried out in the period of 2011–2018 that made it possible to determine the features of the vertical structure and the dynamics of aerosol particles. Analysis of the results of the observations revealed an increase of the wave activity in the troposphere during the periods of passage of the solar terminator in the range from 2 to 20 minutes.
Ensuring reliable functioning and stability of GNSS systems in any natural and man-made conditions is an urgent task. Understanding the physico-chemical processes developing in the atmosphere is important for successful solving these problems. The paper presents the results of the analysis of observations of atmospheric and ionospheric parameters during the development of storm meteorological disturbances in the Kaliningrad region. The data of observations of the atmosphere and ionosphere parameters were obtained using the methods of lidar sensing of the troposphere and vertical sensing of the ionosphere. Analysis of observations of atmospheric and ionospheric parameters showed that the development of such meteorological disturbances is accompanied by increased activity of wave processes in the troposphere with periods of 2-20 minutes. Perturbations with the same periods are observed in variations of ionospheric parameters. The obtained results indicate the correlation of dynamic processes in the lower atmosphere and ionosphere.
Studying the processes occurring in biological systems under irradiation is critically important for understanding the principles of working of biological systems. One of the main problems, which stimulate interest to the processes of photo-induced excitation and ionization of biomolecules, is the necessity of their identification by various mass spectrometry (MS) methods. While simple analysis of small molecules became a standard MS technique long time ago, recognition of large molecules, especially carbohydrates, is still a difficult problem, and requires sophisticated techniques and complicated computer analysis. Due to the large variety of substances in the samples, as far as the complexity of the processes occurring after excitation/ionization of the molecules, the recognition efficiency of MS technique in terms of carbohydrates is still not high enough. Additional theoretical and experimental analysis of ionization and dissociation processes in various kinds of polysaccharides, beginning from the simplest ones, is necessary. In our work, we extent previous theoretical and experimental studies of saccharides, and concentrate our attention to protonated glucose. In this article we paid the most attention to the cross-ring dissociation and water loss reactions due to their importance for identification of various isomers of hydrocarbon molecules (for example, distinguish α- and β-glucose).
Photochemical properties of carbohydrates, including mono- and polysaccharides, as well as various kinds of glycoproteins, proteoglycans, and glycolipids, take great attention last decades due to their significance for clarifying physical and chemical processes happening in biological molecules under irradiation. Understanding of excitation and ionization processes is important for interpretation of mass spectrometric (MS) experiments, which is the main instrument for quick and reliable analysis of biological samples. While polynucleotides and simple proteins can be easily studied by standard MS techniques (MALDI, ESI, and CID), carbohydrates and complicated biomolecules containing oligosaccharide residues are difficult to be ionized. Carbohydrates give a low signal yield. Their detection and analysis requires the special equipment and technology. Therefore, the development of new efficient methods for identification of carbohydrates in biological samples currently is the critical scientific and technical problem. In this work we study dissociation processes taking place in potassiated α- and β-glucose, which can be concerned as the modelling molecule for investigation of wide range of carbohydrates and carbohydrate fragments of biomolecules containing potassium ion as the ionization source. Here we compare deionization process with H2O and KOH elimination channels, as far as their competition with cross-ring dissociation processes. Potential energy surface were optimized by the density functional B3LYP/6-31G* method. Single point energy calculations in minima and transition state points were performed by G3(MP2,CCSD) ab initio method.
The structure of intermetallic clusters Au12M (M=Hf, Ta, W, Re, Os) and features of their interaction with electron donors and acceptor atoms, i.e. H and F, were investigated making use computer calculation based of density functional theory. In was found that metal clusters with effective electron number equal to 18 have more symmetrical shape then that with a number of electrons differing from 18. The interaction of gold nanoparticles with silica was modeled by attachment of SiO4H groups and the connection of the electronic structure with electronic transitions in spaser is discussed.
The paper revealed the using of industrial production equipment ALTI "Karavella-1", "Karavella-1M", "Karavella-2" and "Karavella-2M" precision components of IEP production [1–4]. The basis for the ALTI using in the IEP have become the positive results of research and development of technologies of foil (0.01–0.2 mm) and thin sheets (0.3–1 mm) materials micromachining by pulsed radiation CVL [5, 6]. To assess the micromachining quality and precision the measuring optical microscope (UHL VMM200), projection microscope (Mitutoyo PV5100) and Carl Zeiss microscope were used.