The ratio of the reactivity calculated from the solution of a conditionally critical problem for the neutron flux density and the reactivity obtained using the measured values of the ...ionization-chamber currents. The efficacy of the emergency protection was measured at reactor startup of the Nos. 6 and 7 power units of the Novovoronezh NPP and No 5 unit of the Leningrad NPP. The ionization chambers are situated in the biological-protection concrete. The measured and calculated values of the efficiency of the emergency protection are compared using the results of design modeling based on calculations of the ionization-chamber currents. The measured values of the quantities are compared with the calculated values.
The article presents the results of numerical simulation of the experiments conducted during the physical start-up of unit 1 of the Novovoronezh II NPP. The list of measured parameters includes the ...critical concentration of boric acid and the scram efficiency. The calculations were performed using both the RAINBOW-TPP code intended for the combined neutronics and thermal-hydraulic calculation of the reactor facility and precision neutronics Monte Carlo codes. The scram efficiency was defined from steady-state calculations and using the inverse kinetics equation solution method based on numerical simulation of the neutron flux at the location of the ionization chambers. The results of the numerical simulation of the scram efficiency were compared with the measured data defined in the course of the physical start-up.
Endothelial and smooth muscle cells are considered promising resources for regenerative medicine and cell replacement therapy. It has been shown that both types of cells are heterogeneous depending ...on the type of vessels and organs in which they are located. Therefore, isolation of endothelial and smooth muscle cells from tissues relevant to the area of research is necessary for the adequate study of specific pathologies. However, sources of specialized human endothelial and smooth muscle cells are limited, and the search for new sources is still relevant. The main goal of our study is to demonstrate that functional endothelial and smooth muscle cells can be obtained from an available source-post-surgically discarded cardiac tissue from the right atrial appendage and right ventricular myocardium.
Heterogeneous primary cell cultures were enzymatically isolated from cardiac explants and then grown in specific endothelial and smooth muscle growth media on collagen IV-coated surfaces. The population of endothelial cells was further enriched by immunomagnetic sorting for CD31, and the culture thus obtained was characterized by immunocytochemistry, ultrastructural analysis and in vitro functional tests. The angiogenic potency of the cells was examined by injecting them, along with Matrigel, into immunodeficient mice. Cells were also seeded on characterized polycaprolactone/chitosan membranes with subsequent analysis of cell proliferation and function.
Endothelial cells isolated from cardiac explants expressed CD31, VE-cadherin and VEGFR2 and showed typical properties, namely, cytoplasmic Weibel-Palade bodies, metabolism of acetylated low-density lipoproteins, formation of capillary-like structures in Matrigel, and production of extracellular matrix and angiogenic cytokines. Isolated smooth muscle cells expressed extracellular matrix components as well as α-actin and myosin heavy chain. Vascular cells derived from cardiac explants demonstrated the ability to stimulate angiogenesis in vivo. Endothelial cells proliferated most effectively on membranes made of polycaprolactone and chitosan blended in a 25:75 ratio, neutralized by a mixture of alkaline and ethanol. Endothelial and smooth muscle cells retained their functional properties when seeded on the blended membranes.
We established endothelial and smooth muscle cell cultures from human right atrial appendage and right ventricle post-operative explants. The isolated cells revealed angiogenic potential and may be a promising source of patient-specific cells for regenerative medicine.
The effect of transtraumatic epidural electrostimulation (TEES) above (T5) and below (L2) spinal cord injury in the lower thoracic region (T8-T9) in combination with treadmill exercise in pigs was ...evaluated using electrophysiological examination methods and behavioral tests. Two weeks after spinal cord injury, motor evoked potentials of
m. soleus
were recorded during electrostimulation at the level of T5 and L2 segments, which indicated activation of spinal cord structures above and below the focus of injury. After 6 weeks of TEES in combination with physical training, restoration of the characteristics of M-response and H-reflex of the soleus muscle in response to stimulation of the sciatic nerve, improvement of joint mobility, and appearance of voluntary motor activity in the hindlimbs were observed. Neuromodulation with TEES had been proven to be an effective way to stimulate posttraumatic spinal cord regeneration and can be used in the development of a neurorehabilitation protocol for patients with spinal cord injury.
We report on growth of polycrystalline diamond (PCD) by chemical vapor deposition (CVD) in a microwave plasma reactor under high absorbed microwave power density (MWPD) and high pressures, in ...conditions more typical for single crystal diamond epitaxy. The growth rates as high as 30–36 μm/h have been achieved in CH4-H2 mixtures at pressure of 320 Torr and MWPD of ~700 W/cm3 even at relatively low (3%) CH4 concentration, using PCD substrates with diameter of 5–20 mm and different textures. The structure and quality of the produced PCD thick films were assessed with SEM, Raman and X-ray diffraction. The plasma shapes and spatial profiles of species (excited atomic hydrogen and C2 dimer) were characterized with spatially resolved optical emission spectroscopy (OES) at moderate and high MWPD. The maximum rotational gas temperature Tg significantly enhanced to 3700 K in the latter case (675 W/cm3) compared with Tg ≈ 3100 K for lower pressure and MWPD (100 Torr, 160 W/cm3), being in agreement with the obtained high growth rates at high pressures. Analysis of numerous literature data on PCD growth rate vs substrate size in MPCVD reactors reveals a clear trend of enhanced growth rate with diminishing of the substrate dimension, our findings further confirming this tendency indirectly related to a change in absorbed power density.
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•Polycrystalline diamond (PCD) films are grown by MPCVD at growth rates as high as 30–36 μm/h.•The growth is realized on 5–15 mm diameter PCD substrates at high microwave power density (MWPD) of 700 W/cm3.•The trend of enhanced growth rate with decrease of substrate size is based on present and literature data.
We theoretically describe a driven two-electron four-level double-quantum dot (DQD) tunnel coupled to a fermionic sea using the rate-equation formalism. This approach allows to find occupation ...probabilities of each DQD energy level in a relatively simple way, compared to other methods. Calculated dependencies are compared with the experimental results. The system under study is irradiated by a strong driving signal, and as a result, one can observe Landau–Zener–Stückelberg–Majorana (LZSM) interferometry patterns which are successfully described by the considered formalism. The system operation regime depends on the amplitude of the excitation signal and the energy detuning, so one can transfer the system to the necessary quantum state in the most efficient way by setting these parameters. Obtained results give insights about initializing, characterizing, and controlling the quantum system states.
A comprehensive study of the magnetic behavior, morphology, and composition of Fe-containing oxide coatings on aluminum and titanium has been carried out to investigate the origin of their ...ferromagnetism. The coatings have been formed by the plasma electrolytic oxidation (PEO) technique in slurry electrolytes containing colloidal particles of iron(III) hydroxides. On the surface of coatings on Al, iron is distributed unevenly concentrating in defective areas with a large number of small pores, and near large pores. On the surface of coatings on Ti, iron and titanium are distributed in antiphase in areas of comparable size. Within the pores, iron concentration appears about 5–10 times higher and oxygen concentration 3–4 times lower than their average concentration over the surface. In both cases, localization of the areas with ferromagnetic properties follows the peculiarities of iron distribution on the surface. The magnetic fraction in the coatings on aluminum appears to be represented by iron-aluminum spinel Fe3-xAlxO4 with x > 0.06, likely cation-deficient. Elemental iron and traces of iron hydroxides are also possibly present. In the coatings on titanium, titanomagnetite (Fe3-xTixO4, where x ∼ 0.2–0.3) or its oxidized analogue, titanomaghemite, appear to be present, and possibly also some Fe–Ti alloy particles.
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•Oxide layers are formed on Al and Ti in electrolytes with iron hydroxides.•Ferromagnetism at 2–900 K, composition and surface morphology were studied.•The concentration of iron in the pores is 5–10 times higher than on the surface.•Iron oxides and/or Fe-particles are responsible for ferromagnetism of Al samples.•Titanomagnetites and/or Fe–Ti particles give ferromagnetic properties to Ti-samples.
The aim of the study was to evaluate the role of pseudocontinuous arterial spin labeling perfusion (pCASL-perfusion) in preoperative assessment of cerebral glioma grades. The study group consisted of ...253 patients, aged 7-78 years with supratentorial gliomas (65 low-grade gliomas (LGG), 188 high-grade gliomas (HGG)). We used 3D pCASL-perfusion for each patient in order to calculate the tumor blood flow (TBF). We obtained maximal tumor blood flow (maxTBF) in small regions of interest (30 ± 10 mm
) and then normalized absolute maximum tumor blood flow (nTBF) to that of the contralateral normal-appearing white matter of the centrum semiovale. MaxTBF and nTBF values significantly differed between HGG and LGG groups (p < 0.001), as well as between patient groups separated by the grades (grade II vs. grade III) (p < 0.001). Moreover, we performed ROC-analysis which demonstrated high sensitivity and specificity in differentiating between HGG and LGG. We found significant differences for maxTBF and nTBF between grade III and IV gliomas, however, ROC-analysis showed low sensitivity and specificity. We did not observe a significant difference in TBF for astrocytomas and oligodendrogliomas. Our study demonstrates that 3D pCASL-perfusion as an effective diagnostic tool for preoperative differentiation of glioma grades.
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