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Metallic nanoparticles are promising objects of study, since their properties greatly differ from the properties of bulk material. In analyzing nanoparticles, it is important to investigate their size, stability, structural features, and spatial arrangement. In this study, initial and annealed silver nanoparticles from ∼2 to 10 nm in size formed on a carbon substrate by vacuum thermal evaporation are investigated by high resolution transmission electron microscopy and their shape and structure are classified. The examined nanoparticle types include faceted ellipsoid ones with a polycrystalline structure, coarse ones with a single-crystal structure and twins, icosahedral and decahedral ones with multiple twinning, and fine single-crystal nanoparticles smaller than 3.5 nm. It is established that, after annealing, the total number of nanoparticles decreases by a factor of ~1.3, the number of fine nanoparticles almost halves, and the fraction of nanoparticles with icosahedral and decahedral cross sections increases by a factor of ~1.5. It is shown that nanoparticles smaller than 5 nm become unstable already after a few seconds of exposure to high-energy electrons. For fine single-crystal nanoparticles smaller than 3.5 nm, the average crystal-lattice parameter is found by precise determination of the centers of atomic columns in their images and calculation of the local distances between atoms located in the mutually perpendicular (200) and (022) planes. It is shown that, in such nanoparticles both before and after annealing, there are no noticeable crystal-structure distortions and their lattice parameter is similar to the value characteristic of bulk silver. [ABSTRACT FROM AUTHOR]

The conditions and characteristics of intensive evaporation of very inhomogeneous drops of emulsions of water with petroleum products (gasoline, kerosene, residual oil, heavy crude, transformer oil, turbine oil) were experimentally investigated at relative volume concentrations of these products in emulsions varying in the wide range from 10 to 70% corresponding to a large number of high-temperature (1100 K) processes occurring with gas and vapor drops, such as the heat and flame purifications of water and the production of a synthetic gas from fuel emulsions and suspensions based on water. The conditions of explosion breakdown of emulsion drops in the process of their heating have been determined. Three regimes of breakdown of emulsion drops, differing in the number of small droplets formed and in their surface area, were separated. Proposals were made on the mechanisms of the physical processes leading to the transformation of the surface of emulsion drops and their explosion breakdown. [ABSTRACT FROM AUTHOR]

The macroscopic regularities of the motion of water droplets (initial size 50-500 μm) moving through a counter-flowing high-temperature gas at about 1100 K were investigated using panoramic tracer visualization optical methods (Particle Image Velocimetry and Interferometric Particle Imaging). Characteristic velocities of water droplet evaporation, as well as conditions for their retardation and subsequent carryover by high-temperature gases, were determined. The limiting initial velocities and sizes of droplets for which the conditions of retardation and carryover are implemented were established. Recommendations for improvement of the effectiveness of thermal (high-temperature) water cleaning were formulated. [ABSTRACT FROM AUTHOR]

The process of the formation of column-shaped carbon nanostructures by plasma-enhanced chemical vapor deposition is explored. Carbon nanocolumns are formed at 250°C. The structure and properties of the structures are studied by atomic-force microscopy, scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy. The electrical properties of the structures are investigated. [ABSTRACT FROM AUTHOR]

The efficient injection of electrons into a propagating relativistic laser pulse with normalized vector potential a0 ∼ 2 is demonstrated numerically and experimentally in a thin plasma layer with density 0.15–0.3 of the critical value. The injection is due to the wavebreaking of parametric plasma waves. The trapped particles gain multi-MeV (up to 20 MeV) energies by the direct laser acceleration in the plasma channel formed by the laser pulse in the lower density plasma tail. Numerical calculations were supported by experiments with micron-scale films pre-evaporated by an additional nanosecond laser pulse and a TW femtosecond laser facility. The experimentally observed bunch of electrons with energy above 1.6 MeV had a divergence of ∼0.05 rad and charge of ∼50 pC measured with photoneutron Be(g,n) reaction. [ABSTRACT FROM AUTHOR]

Background. The psbA-trnH intergenic spacer (IGS) is one of the most commonly used in the molecular taxonomy and DNA-barcoding regions of the chloroplast genome. The advantages of this region are the possibility of direct sequencing of PCR products, a small size that facilitates PCR amplification and a moderately high nucleotide polymorphism, compared to other fragments of the cpDNA. However, the sequences of psbA-trnH for many plants are still absent in databases, which makes it difficult to identify them. This, in particular, concerns Lathyrus venetus (Mill.) Wohlf - the Red list species of the legume flora of Ukraine. The aim of current study was to amplify and sequence the IGS psbA-trnH of this species and to estimate the possibility of using it for DNA barcoding. Methods. PCR amplification was performed using the Maxima Hot Start PCR Master Mix (Thermo Scientific) polymerase. For the amplification, the primers complementary to the flanking IGS regions of psbA and trnH genes were used. The primers annealing temperature was 61 ° C. The obtained PCR products were sequenced and the nucleotide sequence was analyzed using bioinformatics methods. Finding the matches in the GenBank database was conducted using the Blast program. Results. The sequence of IGS psbA-trnH for L. venetus has the length of 241 bp. The search in the Genbank database showed that the sequence of IGS of L. niger L. is most closely related to L. venetus among the deposited sequences. The calculated percentage of similarity between IGS of these species was 98.7 %. The vast majority of other Lathyrus species have a similar percentage of similarity to IGS of L. venetus in the range of 97.1 to 97.9 %. In comparison to all the aforementioned species IGS psbA-trnH L. venetus has two oligonucleotide insertions and one polynucleotide deletion at the 3’-end. Unexpectedly, the same deletion was found to be characteristic for the IGS of the genus Pisum L. Also, several point nucleotide substitutions have been identified. In general, it is important for DNA-barcoding that the nucleotide sequence of IGS psbA-trnH allows a clear distinction between L. venetus and other species of Lathyrus genus. Conclusions. At the next stage of our study, there will be conducted a sequencing of IGS psbA-trnH for closely related to L. venetus, but more abundant species L. vernus (L.) Bernh., which often forms morphologically similar hybrids with L. venetus. This complicates the control of the latter. Also, in order to better identify the hybrid forms, we plan to pick up the DNA-barcode of nuclear localization and use them together. [ABSTRACT FROM AUTHOR]

Background. The genes encoding the ribosomal RNA (rDNA), in particular, 5S rDNA represent a convenient model for studying molecular evolution in eukaryotes. Taking into consideration that in insects this genomic region still remains insufficiently studied, the aim of our experiments was to analyze the molecular organization and polymorphism of 5S rDNA spacer region in different subspecies of honeybee. Methods. The bees used in our study were obtained from breading farms of Austria and Greece. Total DNA was extracted from the body of bee using CTAB. Amplification of 5S rDNA repeats was performed using polymerase chain reaction (PCR) with primers RV0803 and RV1406 that are complementary to the conservative region coding for 5S rRNA. Purified PCR products were cloned into the pGEM™ -T vector (Promega™). The recombinant plasmids containing the 5S rDNA inserts were sequenced and analyzed using the Lasergene software package. Results. It was found that the sequence of the 5S rDNA coding region was identical for all analyzed clones. The length of the amplified portion of the coding region without primers was 80 bp, and it was identical to the 5S rDNA coding regions of honey bees available in GenBank database. In contrast to the coding region, the 5S rDNA intergenic spacer (IGS) of the analyzed clones demonstrated polymorphism in both structure and length. The obtained clones were compared to the sequences from the genome of A. mellifera, which is presented in GenBank. The analysis revealed several clusters of 5S rRNA genes, which are located on the chromosome 17. It was found that the IGS sequences of several A. m. carnica 5S rDNA clones, which were obtained in our experiments (e.g., SKL47#2 pl2 and SKL47#2 pl3) show a high similarity with the 5S rDNA clusters No 1 and No 4 detected in GenBank. At the same time, clone SKL47#2 pl4 demonstrate[s] a high similarity with the IGS characteristic for clusters No 2 and No 3, suggesting the presence of several variants of intergenic spacers in the genome of A. m. carnica. We also compared the rDNA clones obtained for subspecies A. m. carnica and A. m. macedonica. It was found that the IGS sequences of A. m.macedonica significantly differ from each other. The sequences comparison showed that the level of similarity between the IGS of both subspecies and that of GenBank ranged from 90 to 93 %, except for the A. m. macedonica clone 1#pl5, which appeared to be identical to the IGS variants from GenBank cluster No 3. Conclusions. The analysis of the molecular organization of the IGS region showed that several variants of 5S rDNA are present in the genomes of honeybee subspecies, A. m. carnica and A. m. macedonica. [ABSTRACT FROM AUTHOR]

The fusion in air of four femtosecond laser beams each with the peak power several times higher than the critical self-focusing power has been studied experimentally. It has been shown that a superfilament formed in such a regime ensures the efficient energy input to a medium. It has been shown that the linear density of the input energy increases approximately quadratically with both the energy of a laser pulse and the number of fused beams. [ABSTRACT FROM AUTHOR]

The hot plasma formed onto the surface of nanostructured targets by a relativistically intense (up to 4 × 10 W/cm), high contrast femtosecond laser radiation is studied. The nanoscale structures (pores, spheres, grass) were produced via laser ablation or chemical etching of bulk silicon and molybdenum. We report one of the first experimentally observed manifold enhancements of gamma yield at the background of hot electron energy growth from 200 to >600 keV, compared to the case of initially flat substrate in the relativistic regime of interaction. The efficiency of hot particle production is significantly affected by the shape of the structures. Experimental results are supported by 2D3V Particle-In-Cell simulations of laser-plasma interaction. It is shown that a laser-based plasma source, formed onto the surface of a solid target may be utilized for phase contrast X-ray imaging in a wide energy range of photons. [ABSTRACT FROM AUTHOR]

The results of studying the growth of filamentous Ge structures in aqueous electrolytes at various temperatures using In and Sn nanoparticle arrays as nucleation sites are given. The temperature of Ge cathodic deposition process from aqueous solutions has a significant effect on the layer structure deposited onto the surface. In the presence of metal particles in the molten state, filamentous Ge structures grow due to the cathodic reduction of Ge-containing ions on the electrode surface, followed by dissolution and crystallization in the melt at the substrate interface. The results obtained show the crucial role of liquid metal particles during the electrochemical formation of germanium nanowires. [ABSTRACT FROM AUTHOR]

We present results from the experimental and numerical study of electron heating and acceleration under the action of a 50 fs high contrast laser pulse [intensities ~(1-4)×1018 W/cm2] with a controlled preplasma that was created by a 6 ns laser "prepulse" with intensity ~1012 W/cm2. A substantial increase both in the gamma yield and "temperature" was obtained by the proper adjustment of the time delay between the two pulses (0-5 ns), while the gamma yield dropped to almost zero values if the nanosecond pulse came 10-20 ns in advance of the femtosecond one. Comprehensive optical diagnostics (shadowgraphy, interferometry, and angular resolved self-emission measurements) data allowed us to estimate the electron density profile. The latter profile was used for making numerical Particle-in-cell simulations which describe the gamma yield enhancement well. We also illustrate how the observed drop in the gamma yield within a certain range of delays was due to ionization defocusing of the femtosecond beam in an expanding long-scale (L/λ > 1) preplasma. [ABSTRACT FROM AUTHOR]

We observed huge, almost two orders of magnitude, increase in the energy of the forward terahertz (THz) emission by the long femtosecond filament if transverse electrostatic field is applied along its full length. This proves summation of emission both from different parts of a single filament and from multiple filaments. The observed THz radiation has a narrow angular shape with a maximum in the direction of laser radiation and a spectrum in the range of 0.05–0.3 THz with a maximum at about 0.1 THz. Numerical simulations based on the UPPE well explain the experimental findings. [ABSTRACT FROM AUTHOR]

The results of electron microscopy studies of an epitaxial InAlAs layer on a GaAs(100) substrate are reported. It is established that there exist misfit dislocations at the interface between the materials and there are residual strains distorting the lattice in the layer. From the measurements of lattice parameters in the directions parallel and orthogonal to the growth direction away from misfit dislocations, the local nominal lattice parameter of the layer is calculated and the relative content of indium is determined. [ABSTRACT FROM AUTHOR]

This paper describes the study of hot electron generation under the action of intense (~1018W/cm²) femtosecond pulses onto the surface of a solid target, in the presence of a long pre-plasma, which varied with different spatial extents and densities. The corona was formed by pre-pulses with varied intensities and temporal profiles (amplified spontaneous emission (ASE) and short pre-pulses). The most efficient fast electron acceleration, to energies well beyond the ponderomotive potential, was observed if the ASE was able to form to the extent of ~100 im a slightly undercritical plasma. Energy of accelerated electrons underwent further growth if the laser pulse duration increased from ~45 to ~350 fs at constant energy fluence. The experimental results were supported by numerical simulations using 3D3V Mandor PIC code. [ABSTRACT FROM AUTHOR]

It is shown experimentally that the mean energy of accelerated electrons generated by irradiating a dense target with a pair of 13-ns-delay femtosecond laser pulses forming radiation with an energy contrast of 100–500 and an intensity of about 1018 W/cm2 increases significantly in comparison with the case of high contrast ∼106. [ABSTRACT FROM AUTHOR]

We present atomic, energy, and charge spectra of ions accelerated at thefrontsurface of a silicon target irradiated by a high-contrast femtosecond laser pulse with an intensity of 3×1016 W/cm2, which is delayed with respect to a cleaning nanosecond laser pulse of 3-J/cm2 energy density. A tremendous increase in the number of fast silicon ions and a significant growth of their maximum charge in the case of the cleaned target from 5+ to 12+ have been observed. The main specific features of the atomic, energy, and charge spectra have been analyzed by means of one-dimensional hydrodynamic transient-ionization modeling. It is shown that fast highly charged silicon ions emerge from the hot plasma layer with a density a few times less than the solid one, and their charge distribution is not deteriorated during plasma expansion. [ABSTRACT FROM AUTHOR]

We investigated the conditions, characteristics, and outcomes of liquid droplet interaction in the gas medium using video frame processing. The frequency of different droplet collision outcomes and their characteristics were determined. Four interaction regimes were identified: bounce, separation, coalescence, and disruption. Collision regime maps were drawn up using the Weber, Reynolds, Ohnesorge, Laplace, and capillary numbers, as well as dimensionless linear and angular parameters of interaction. Significant differences were established between interaction maps under ideal conditions (two droplets colliding without a possible impact of the neighboring ones) and collision of droplets as aerosol elements. It was shown that the Weber number could not be the only criterion for changing the collision mode, and sizes and concentration of droplets in aerosols influence collision modes. It was established that collisions of droplets in a gaseous medium could lead to an increase in the liquid surface area by 1.5–5 times. Such a large-scale change in the surface area of the liquid significantly intensifies heat transfer and phase transformations in energy systems. [ABSTRACT FROM AUTHOR]

ISSR-PCR markers were used to assess genetic diversity and to elucidate relatedness among 21 Ukrainian and 3 West European sweet cherry varieties, which are widely cultivated in Ukraine. The discriminatory potential was tested for 11 ISSR-PCR primers, which produced 193 amplicons. UBC 835, 836, 841 and 881 were identified as the best primers suitable for routine application. The studied cultivars appear to be genetically highly heterogenic and can be divided in two main groups. The first one includes closely related cultivars obtained by hybridization of Drogan’s Yellow (Drogans gelbe Knorpelkirsche), Valerii Chkalov and some other forms. The second group comprises less similar cultivars derived from several West-European and unknown ancestors. Origin of several Ukrainian cultivars is discussed.

The article shortly describes the life path of Erwin Chargaff, one of the most famous figures in the history of molecular biology and genetics. Chargaff was born in Chernivtsi (Austria-Hungary, now Ukraine) but during the First World War his family was forced to move to Vienna. After graduating from the University of Vienna, Chargaff worked in Berlin, where he studied bacterial lipids. Due to Nazis coming to power in Germany, Chargaff moved to Paris and later (1935) emigrated to the USA and obtained a position at Columbia University, where he initially investigated the role of phospholipids in blood clotting. In 1944, applying novel methods Chargaff initiated intensive investigation of the chemical composition of nucleic acids from taxonomically distant species and established two rules which were later named after him. The first Chargaff's rule provided a significant support to Watson and Crick in construction of their double helical DNA model. The explosion of atomic bombs over Hiroshima and Nagasaki forced Chargaff to think about the moral responsibility of researchers and science to mankind. He begins to raise these issues in the press and manifests himself as a talented journalist, who criticized the bureaucratization of science and its transformation into a way of earning money. Despite decades of life in America, spiritually Erwin Chargaff always remained a European, who never forgot his roots and always remembered his native land.

In order to clarify molecular organization of the genomic region encoding 5S rRNA in diploid species Rosa rugosa several 5S rDNA repeated units were cloned and sequenced. Analysis of the obtained sequences revealed that only one length variant of 5S rDNA repeated units, which contains intact promoter elements in the intergenic spacer region (IGS) and appears to be transcriptionally active is present in the genome. Additionally, a limited number of 5S rDNA pseudogenes lacking a portion of coding sequence and the complete IGS was detected. A high level of sequence similarity (from 93.7 to 97.5%) between the IGS of major 5S rDNA variants of East Asian R. rugosa and North American R. nitida was found indicating comparatively recent divergence of these species.

Two length variants of 5S rDNA repeated units were detected in the genome of East European butterfly Melitaea trivia. Both repeat variants contain the 5S rRNA coding region of the same length of 120 bp, but possess the intergenic spacer region (IGS) of different size, 78 and 125 bp, respectively. The level of sequence similarity between the two 5S rDNA variants amounts to 43.9-45.5% in the IGS, whereas the coding region appears to be more conservative. In the IGS, microsatellite sequence motives were found; amplification of these motives could be involved in the evolution of the 5S rDNA.

Ribosomal DNA comprises a considerable part of a plant genome and is organized in tandemly arranged repeats composed of conservative coding sequences for ribosomal RNA and rapidly evolving spacer elements. We determined the nucleotide sequences of intergenic spacer regions (IGS) for five species from Solanacaea family: Solanum tuberosum, Atropa belladonna, Nicotiana tabacum, N. tomentosiformis, and N. sylvestris. The detailed comparative analysis of these and some other rDNA sequences allowed us to reveal the general regularities of evolution and functional organization of the rDNA spacer region and to clarify better phylogenetic relationships between the species within Solanacea family. A large body of experimental data on the application of rDNA in plant breeding, taxonomical studies and biotechnology are provided and discussed.

It has been found that Cu and Ni at contents of 17 mg/kg and 64 mg/kg dry weight respectively in leaves tissues have no visible effect on morphological and physiological characteristics of plants and increase [3H]uridine incorporation in various types of RNA. Under these conditions synthesise of nuclear RNA has been found 1.8-2.4 more intense, transport RNA -2.0-2.8 intense and ribosomal RNA-1.2-2.8 intense in comparison with control. Analysing our data it is possible to suggest that the activation of the RNA synthesis under the heavy metals influence may be one of the protective mechanism connected with the plant cell adaptation to the stressful conditions.

The nucleotide sequence of the intergenic spacer (IGS) region between the 25S and the 18S rRNA coding regions has been determined for tobacco (Nicotiana tabacum). The IGS (5140 bp in length) can be subdivided into several regions (I-VII) two of which, upstream and downstream of the putative transcription initiation site (TIS), contain prominent subrepeats (A and C). The unique sequence in the central part of the IGS (region IV) preceding the TIS is extremely AT-rich. The distance from the putative TIS to the 5' end of the 18S rRNA gene is 3005 bp. The IGS sequences are compared with potato (Solanum tuberosum) and tomato (Lycopersicon esculentum) IGS. Restriction mapping of 13 Nicotiana species shows that considerable rDNA repeat length heterogeneity in this genus is probably due to different numbers of A and C subrepeats.

14C-leucine incorporation in cytoplasmic protein was compared for three haploid forms, three derivative autodiploid lines and four hybrid forms of maize. It has been found that the precursor incorporation in the haploid forms was by 15-20% higher that in appropriate autodiploid lines. However, the level of protein synthesis wes practically the same for all investigated diploid forms. Thus, the increase of the ploidy level correlates with the decrease of the cytoplasmic protein synthesis. It was also shown that the protein content was practically equal in haploid and diploid forms. Proceeding from the authors' data one can conclude that the protein distraction may also have different intensity. The next step of the investigation was the study of the effects of the chemical factor of cytoplasmic protein synthesis in maize seedlings with different ploidy levels in vivo. It has been revealed, that the rate of 14C-leucine incorporation in the cytoplasmic proteins differ for the haploid forms which grew on the Knop media with the addition of phenol (0.05%) and without pollutant. Nevertheless, approximately equal level of 14C-leucine incorporation was observed for autodiploids. Recently it was demonstrated that the synthetic intensity of different RNA fractions is higher in the haploid maize forms than in the diploid ones and that the haploid and diploid forms of maize display the different reaction on phenol pollution. When comparing our data with the published results it is possible to conclude that the hypothesis about the low intensity of metabolism in haploid plants, existing in literature, is not true. The authors suppose that the high activity of synthesis of nuclear, transfer and ribosomal RNA and cytoplasmic proteins in the haploid plants may be connected with high mitotic activity. The authors' data are in agreement with the hypothesis that the ratio of nuclear volume and surface determines the metabolism rate.