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We report the preparation of SmS@Y
2
O
2
S and Y
2
O
2
S@SmS ceramics with a core–shell nanostructure via 1123-K sulfidation of rare-earth oxides prepared by the sol–gel method, involving ...precipitation from starting metal nitrate solutions with NH
4
OH as a precipitant, followed by annealing of the resultant sulfide phases in an induction furnace at 1473 K. Using X-ray diffraction and scanning electron microscopy data, we have evaluated the average crystallite size in the materials and examined the morphology of the constituent phases in them. In addition, the short-range order in the coexisting nanostructures has been analyzed in detail using Raman spectroscopy and X-ray photoelectron spectroscopy data.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The pyroelectric and electrocaloric effects and also the dielectric properties in a biasing electric field have been studied in lead–strontium magnoniobate–titanate solid solutions. The specific ...features of the temperature and field dependences of the pyroelectric and electrocaloric effects are discussed.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The atom oxidation states were determined using the binding energies of the core S2p-, Cu2p-, Cr2p-, and Ln3d-levels in CuCr
Ln
S
(Ln = Dy-Lu) solid solutions. The charge distribution on the matrix ...elements (Cu, Cr, and S) remained unaffected after cationic substitution. The sulfur atoms were found to be in the S
oxidation state, the copper-Cu
, and the chromium-Cr
. The cationic substitution of the initial CuCrS
-matrix occurred via the isovalent mechanism. The obtained results were compared with the electrophysical properties for CuCr
Ln
S
. The measured carrier concentration was from 10
to 10
cm
. The largest Seebeck coefficient value of 157 µV/K was measured for CuCr
Yb
S
at 500 K. The cationic substitution with lanthanides allowed one to enhance the Seebeck coefficient of the initial CuCrS
-matrix.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
The study of the valence state, local environment structure and magnetic properties of novel type CuCr
0.99
Ln
0.01
S
2
(Ln = La, Ce) solid solutions was carried out using X-ray absorption ...spectroscopy, finite difference method simulations and static magnetic susceptibility measurements. The good agreement between experimental and calculated data indicates that cationic substitution does not lead to significant changes in the copper, chromium and sulfur local environment character and electronic density distribution. The copper atoms were found to be in Cu
+
oxidation state, the sulfur atoms—in S
2−
oxidation state and the chromium atoms—in Cr
3+
state. The cationic substitution of chromium by lanthanum and cerium in CuCrS
2
does not significantly affect the effective magnetic moment and exchange interactions character. The lanthanum-doped CuCr
0.99
Ln
0.01
S
2
solid solution demonstrates the Seebeck coefficient value 4 times greater than for CuCrS
2
-matrix at 500 K.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The charge distribution study of metal atoms in CuCr
Ln
S
(Ln = Pr-Tb) solid solutions was carried out using X-ray photoelectron spectroscopy (XPS). The analysis of the binding energy of S2p, Cu2p, ...Cr2p, Ln3d and Ln4d levels allows one to determine the oxidation state of atoms. Copper atoms were found to be monovalent. Chromium and lanthanide atoms were found to be in the trivalent state. Sulfur atoms were found to be in the divalent state. Cationic substitution was found to occur via an isovalent mechanism of Cr
to Ln
. The obtained results were used for the interpretation of the Seebeck coefficient increase for CuCr
Ln
S
solid solutions in contrast to the initial CuCrS
matrix. The largest Seebeck coefficient values of 142 and 148 µV/K were observed at 500 K for CuCr
Sm
S
and CuCr
Pr
S
, respectively. The obtained values are 1.4 times greater in comparison with those for the initial matrix (105 µV/K).
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
The present work is devoted to the prediction of the excavation stability and analysis of the geo-mechanical processes near the excavation under dynamic impact. The development of a numerical model ...of the forecast of the development of a stress-strain state with allowance for the dynamic effect taking into account the geometric parameters of the mining development, the speed and nature of the application of the load, and the formation of zones of intense fracturing in its vicinity are performed. The influence of the intensity of the dynamic effect on the nature of the manifestation of geo-mechanical and geodynamic processes in the vicinity, the movement of the contour of the rock excavation, and the probability of ejection of the rock mass are determined.
Background: The main cause of mortality in patients with atherosclerosis of aorta and peripheral arteries of the lower extremities is ischemic heart disease. The presence of peripheral artery ...atherosclerosis suggests a high probability of simultaneous coronary involvement. To reduce the risk of cardiac complications, these patients are offered myocardial revascularization as the first step of the intervention; however, the choice of a conduit for coronary artery bypass in these patients remains challenging.Case report: A 58-year old man with combined coronary artery stenoses, high occlusion of the aorta and common iliac arteries underwent autoarterial myocardial revascularization with the right internal thoracic artery (ITA) and left radial artery ("off pump”). In the early postoperative period, significant progression of the right leg ischemia was observed, related to partitioning of the main collateral flow between the right ITA and the inferior epigastric artery, that had contributed to blood supply to the right lower extremity. Taking into account the lack of efficacy of medical treatment and progression of the leg ischemia, at day 4 postoperatively the patient underwent resection of the infrarenal aorta with aortobifemoral bypass grafting and restoration of blood supply to the lower extremities and resolution of ischemia.Conclusion: ITA has been recognized as the conduit of choice for surgical treatment of ischemic heart disease; however, its use may result in significant progression of ischemia. When choosing a conduit, ITA at the side of less ischemic lower extremity is preferred. ITA imaging by computed tomography-angiography or by selective ITA angiography can be helpful for assessment of the ITA significance at the side of less ischemic leg. Also, the appearance of retrograde flow in the inferior epigastric artery at Doppler ultrasound examination can be a conditional valuable criterion.
The electrocaloric effect and also the dielectric, pyroelectric, acoustic, and piezoelectric properties of a lead magnoniobate–scandoniobate solid solution in a biasing electric field have been ...studied. The dielectric and electromechanical contributions to the pyroelectric and electrocaloric effects are discussed.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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