729 research outputs found
Investigation of the mass-transfer under mixing by the turbine mixer in the partition vessels
Наведено результати експериментальних досліджень фізичного розчинення твердої речовини в залежності від кількості вертикальних перегородок, встановлених у посудинах, виявлено вплив кількості перегородок на інтенсивність масопередачі і потужність, що споживається мішалкою, розраховано коефіцієнти масовіддачі за різних режимів роботи установки.The results of experimental researches of physical dissolution of hard matter depending on the amount of the vertical partitions set in a vessel are resulted, exposed influence of amount of partitions on intensity of mass transfer and power which is consumed by a mixer, the coefficients of mass rejection at different modes of operations of setting are expected
Measuring velocity of sound with nuclear resonant inelastic x-ray scattering
Nuclear resonant inelastic x-ray scattering is used to measure the projected
partial phonon density of states of materials. A relationship is derived
between the low-energy part of this frequency distribution function and the
sound velocity of materials. Our derivation is valid for harmonic solids with
Debye-like low-frequency dynamics. This method of sound velocity determination
is applied to elemental, composite, and impurity samples which are
representative of a wide variety of both crystalline and noncrystalline
materials. Advantages and limitations of this method are elucidated
Dynamics of Metal Centers Monitored by Nuclear Inelastic Scattering
Nuclear inelastic scattering of synchrotron radiation has been used now since
10 years as a tool for vibrational spectroscopy. This method has turned out
especially useful in case of large molecules that contain a M\"ossbauer active
metal center. Recent applications to iron-sulfur proteins, to iron(II) spin
crossover complexes and to tin-DNA complexes are discussed. Special emphasis is
given to the combination of nuclear inelastic scattering and density functional
calculations
Importance of correlation effects in hcp iron revealed by a pressure-induced electronic topological transition
We discover that hcp phases of Fe and Fe0.9Ni0.1 undergo an electronic
topological transition at pressures of about 40 GPa. This topological change of
the Fermi surface manifests itself through anomalous behavior of the Debye
sound velocity, c/a lattice parameter ratio and M\"ossbauer center shift
observed in our experiments. First-principles simulations within the dynamic
mean field approach demonstrate that the transition is induced by many-electron
effects. It is absent in one-electron calculations and represents a clear
signature of correlation effects in hcp Fe
The dynamics of the non-heme iron in bacterial reaction centers from Rhodobacter sphaeroides
AbstractWe investigate the dynamical properties of the non-heme iron (NHFe) in His-tagged photosynthetic bacterial reaction centers (RCs) isolated from Rhodobacter (Rb.) sphaeroides. Mössbauer spectroscopy and nuclear inelastic scattering of synchrotron radiation (NIS) were applied to monitor the arrangement and flexibility of the NHFe binding site. In His-tagged RCs, NHFe was stabilized only in a high spin ferrous state. Its hyperfine parameters (IS=1.06±0.01mm/s and QS=2.12±0.01mm/s), and Debye temperature (θD0~167K) are comparable to those detected for the high spin state of NHFe in non-His-tagged RCs. For the first time, pure vibrational modes characteristic of NHFe in a high spin ferrous state are revealed. The vibrational density of states (DOS) shows some maxima between 22 and 33meV, 33 and 42meV, and 53 and 60meV and a very sharp one at 44.5meV. In addition, we observe a large contribution of vibrational modes at low energies. This iron atom is directly connected to the protein matrix via all its ligands, and it is therefore extremely sensitive to the collective motions of the RC protein core. A comparison of the DOS spectra of His-tagged and non-His-tagged RCs from Rb. sphaeroides shows that in the latter case the spectrum was overlapped by the vibrations of the heme iron of residual cytochrome c2, and a low spin state of NHFe in addition to its high spin one. This enabled us to pin-point vibrations characteristic for the low spin state of NHFe
Study of the surface microrelief of copper nanoparticles by the method of scanning probe microscopy
This work was supported by grants from the RFBR № 17-07-00407-а and № 17-32-50137-mol_nr
Magnetic Phase Separation and Magnetic Moment Alignment in Ordered Alloys FE 65
The structure and the magnetic state of ordered Fe65Al35-xMx (Mx = Ga, B; x = 0; 5 at.%) alloys are investigated using X-ray diffraction, Mössbauer spectroscopy, and magnetic measurements. The behavior of the magnetic characteristics and Mössbauer spectra of the binary alloy Fe65Al35 and the ternary alloy with gallium addition Fe65Al30Ga5 is explained in terms of the phase separation into two magnetic phases: a ferromagnetic one and a spin density wave. It is shown that the addition of boron to the initial binary alloy Fe65Al35 results in the ferromagnetic behavior of the ternary alloy
Study of in-medium meson properties in Ap, pA and AA collisions
We propose to investigate the in-medium properties of vector mesons
at the normal nuclear density in Ap(pA) collisions and at higher density in AA
collisions at the ITEP accelerator facility TWAC. Using of the inverse Ap
kinematics will permit us to study the meson production in a wide
momentum interval included the not yet explored range of small meson momenta
relative to the projectile nuclei where the mass modification effect in nuclear
matter is expected to be the strongest. Momentum dependence of the in-medium
meson width will be studied in the traditional pA kinematics. We
intend to use the electromagnetic calorimeter for reconstruction of the
meson invariant mass by detecting photons from the decay. The model calculations and simulations with
RQMD generator show feasibility of the proposed experiment. Available now
intensity of the ion beams provides a possibility to collect large statistics
and make decisive conclusion about the meson properties at density of
normal nuclei. At the second stage of the investigation the meson
properties will be studied in AA collisions at higher density. Interpretation
of these measurements will be based on the results obtained in Ap(pA)
interactions. Further investigation of the in-medium properties of light
unflavored and charmed mesons can be performed at ITEP and at GSI(FAIR) where
higher ion energies will be accessible in near future.Comment: 26 pages, 10 figures, 2 table
Comparative evaluation of the effectiveness of a peptide-containing drug and polyoxydonium in the treatment of chronic parodontitis
Currently, the available methods of treating parodontitis are not able to have a complex effect. Therefore, in recent years, there has been an active search and development of new methods of treatment and new drugs that have a complex etiopathogenetic effect on this disease. This article provides a comparative evaluation of the classical and experimental methods of treating chronic periodontitis. Based on the reconstruction of an experimental model of chronic inflammation of periodontal tissues of the Wistar rat line, we compared methods of topical therapy by “Organosilicon Glycerohydrogel – Peptide” and “Polyoxidonium” compositions. A comparative assessment of the activity of these drugs with control groups, which were treated with “Organosilicon Glycerohydrogel” and “Metrogyl Denta”, was carried out. Previously, we carried out separate studies of the effectiveness of the use of the composition “organosilicon glycerohydrogel – peptide”, as well as the method of treatment of periodontitis, by injecting the drug “Polyoxidonium”. They have been compared with the classic treatment for this disease to obtain relevant data and results. In our opinion, the data obtained are of considerable interest. The assessment and comparison of clinical and histological data have been carried out, which showed that all drugs had a positive effect on the processes of tissue regeneration. However, the composition “Organosilicon Glycerohydrogel-peptide”, due to the characteristics of the hydrogel, which is acting as a transcutaneous conductor, showed a faster antimicrobial and pathogenetic effect, which allows a comprehensive approach to solving this problem. In comparison with the groups of “Organosilicon Glycerohydrogel” and “Polyoxidonium”, the period of clinical improvement increased by 57% in the group of “Glycerohydrogel-Peptide”, and, in the “Metrogyl Denta” group, the indicators improved by 15% approximately
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