Synthesis of Carbon Nanostructures on Iron Nanopowders Obtained by Electrical Explosion of Wires

This work presents the results of experiments on synthesis of carbon nanostructures by the method of thermal chemical vapor deposition using iron nanopowders obtained by the method of electrical explosion of wires as catalysts. To study the process of nucleation and growth of individual carbon nanostructures, experiments were conducted not only on nanopowders, but also on the separated clusters. To determine the optimum conditions of the carbon nanostructures synthesis and lower temperature limit, experiments were performed at different temperatures (300–700 °C) and pressures (100–400 mbar). The experiments have shown that the lower temperature limit for carbon nanostructures synthesis on the iron nanopowders is 350 °C and in this process the growth of carbon nanostructures is not so massive. Stable growth of carbon nanostructures for nanopowders as well as for the separated clusters began from 400 °C during the entire range of pressures. In contrast to the carbon nanostructures on nanopowders, in the case of the separated clusters a strong dependence of their nucleation and growth on temperature and pressure was traced

Study on the Structure and Morphology of Iron Nanopowders Obtained by the Method of Electric Explosion of Wires

This article presents the results of comprehensive study on the structure and morphology of iron nanopowders synthesized by electric explosive evaporation of metal wire. The results of scanning and transmission electron microscopy showed that nanoclusters have a spherical shape with an average diameter of 65 nm. It was revealed based on the analysis of the diffraction patterns that nanoparticles of nanopowders obtained in electric explosion have a crystal lattice with a parameter less than a standard cell. The results of computer experiments are in good agreement with the findings of X-ray analysis. However, the question about the reasons of distortion of the crystal lattice of nanoclusters remains controversial

Synthesis of Carbon Nanofibers on Copper Nanopowders by Low-Temperature CVD

The article presents the results of experiments on the synthesis of carbon nanofibers by thermal chemical vapor deposition using copper nanopowders obtained by electric explosion of wire as catalysts. Stable growth of carbon nanofibers was carried out at temperatures significantly lower than normally used. The process parameters that are optimal for low-temperature growth of carbon nanofibers have been identified during the performed experiments. The synthesized samples have different diameters and morphology (from spiral to direct). Copper clusters are both at the ends and inside the fibers. The results of IR spectroscopy indicate that the structure of the obtained carbon nanofibers is polymeric. X-ray analysis revealed the presence of a halo on the diffraction patterns at small values of the angle 2θ, which proves that the grown structures have an amorphous nature. There are no groups that are responsible for long-range order in all Raman spectra. Studies by transmission electron microscopy showed that nanostructures do not have an internal channel and nanofibers are solid

Technological Aspects of Introduction Crocus Alatavicus According to GACP Requirements

According to the forecasts of the World Health Organization, the share of herbal medicines in the global pharmaceutical market is more than 40%. The pronounced growth trend of phytopreparations can lead to depletion of stocks of medicinal plants and the introduction of medicinal plants into the culture is a suitable solution to the problem. In order to ensure the quality of medicinal plants, in 2003 the World Health Organization (WHO) issued guidelines on Good cultivation and harvesting practices (GACP) medicinal plants. This article presents the results of the introduction of the Crocus alatavicus plant by seeds. The aim of the study is to develop a technology for the introduction of Crocus alatavicus by the method of seed propagation according to the principles of GACP. The development of the introduction technology according to the principles of GACP guarantees the provision of domestic pharmaceutical production with high-quality plant raw materials. The introduction was carried out at the pilot production plantation of "Phytoleum" LLP. The results of the study showed that during seed propagation, autumn sowing of Crocus alatavicus seeds is preferable. The introduction of organic fertilizer of vermicompost before sowing seeds has a positive effect on the germination of seeds and the survival of seedlings. The plant in the fourth year of vegetation goes into the generative period and the fruit will form. The results of the introduction of Crocus alatavicus by seeds in the period from 2018 to 2022 showed good seed germination and high survival of seedlings, which makes it possible to recommend the plant for introduction into culture. It is important to emphasize that the ability to cultivate C. alatavicus from seeds creates new opportunities for use as domestic raw materials for the purpose of further rational use in scientific and practical medicine, preserving this species in culture

Investigation of SiC and C Nanostructures Obtained by MWCVD

The results of experiments on the synthesis of SiC and C nanostructures by chemical vapor deposition in microwave plasma are presented in this article. The single crystal silicon plates with orientations [100] and [111] which previously passed chemical purification were used as substrates. Also, the substrates of porous silicon were prepared in order to activate the surface during the synthesis. The synthesis temperature ranged from 700 to 900 °C in steps of 100 °C. The pressure in the chamber was changed depending on the power of the plasma. Studies by scanning electron microscopy (SEM) showed that formed nanostructures have a diameter of 200‒350 nm and a rough surface. The formation of nanostructures on the polished Si occurs on the SiC buffer layer. Analysis of SEM images of the samples shows that growth of NS on the surface of porous silicon is more widespread in contrast to the polished Si. The results of X-Ray spectral microanalysis showed that the carbon content in samples of nanostructures on polished Si varies from 10 to 20% and remains constant on porous silicon ~ 25%. The results of studies by Raman scattering confirmed that SiC film with structure of 3C-SiC is formed on the polished Si. Besides, the presence of main carbon peaks on both types of substrates in the range of 1338.2 and 1583 cm‒1 should be noted, which correspond to the carbon nanostructures

Study of Operating Characteristics of Pyrotechnic Reserve Power Source Based on Magnesium and Zinс

This paper presents the results of studies of operating parameters of pyrotechnic reserve power source (PRPS). This battery was activated by the pyrotechnic compositions contained in the electrodes. Once the ignition impulse worked, the pyrotechnic compositions took fire immediately and melted the electrolyte. Then the rest pyrotechnic compositions served as anode and cathode. The battery began to discharge. The following characteristics of PRPS were evaluated during the study: release time to operating regime of the electric current, the duration of the PRPS work and initiation temperature of PRPS. A detailed evaluation of the Mg/LiF/PbF2 electrochemical system and Zn/LiF/PbF2 one is undertaken. Test results show that the electric current value using powder of zinc and granular zinc in these experiments was 0.179 A and 0.1 A, respectively, and the operating time at these values of elecrtic current was 40 and 151 sec, respectively

Single hadron response measurement and calorimeter jet energy scale uncertainty with the ATLAS detector at the LHC

The uncertainty on the calorimeter energy response to jets of particles is derived for the ATLAS experiment at the Large Hadron Collider (LHC). First, the calorimeter response to single isolated charged hadrons is measured and compared to the Monte Carlo simulation using proton-proton collisions at centre-of-mass energies of sqrt(s) = 900 GeV and 7 TeV collected during 2009 and 2010. Then, using the decay of K_s and Lambda particles, the calorimeter response to specific types of particles (positively and negatively charged pions, protons, and anti-protons) is measured and compared to the Monte Carlo predictions. Finally, the jet energy scale uncertainty is determined by propagating the response uncertainty for single charged and neutral particles to jets. The response uncertainty is 2-5% for central isolated hadrons and 1-3% for the final calorimeter jet energy scale.Comment: 24 pages plus author list (36 pages total), 23 figures, 1 table, submitted to European Physical Journal

Measurements of Higgs boson production and couplings in diboson final states with the ATLAS detector at the LHC

Measurements are presented of production properties and couplings of the recently discovered Higgs boson using the decays into boson pairs, H →γ γ, H → Z Z∗ →4l and H →W W∗ →lνlν. The results are based on the complete pp collision data sample recorded by the ATLAS experiment at the CERN Large Hadron Collider at centre-of-mass energies of √s = 7 TeV and √s = 8 TeV, corresponding to an integrated luminosity of about 25 fb−1. Evidence for Higgs boson production through vector-boson fusion is reported. Results of combined fits probing Higgs boson couplings to fermions and bosons, as well as anomalous contributions to loop-induced production and decay modes, are presented. All measurements are consistent with expectations for the Standard Model Higgs boson

Standalone vertex finding in the ATLAS muon spectrometer

A dedicated reconstruction algorithm to find decay vertices in the ATLAS muon spectrometer is presented. The algorithm searches the region just upstream of or inside the muon spectrometer volume for multi-particle vertices that originate from the decay of particles with long decay paths. The performance of the algorithm is evaluated using both a sample of simulated Higgs boson events, in which the Higgs boson decays to long-lived neutral particles that in turn decay to bbar b final states, and pp collision data at √s = 7 TeV collected with the ATLAS detector at the LHC during 2011