One-year periodization of training loads of Russian and Norwegian elite cross-country skiers

The study intended to compare the training load volume (TrV) distribution of elite Russian (RuXC) and Norwegian (NorXC) cross-country skiers in a one-year macrocycle. Daily TrV of 11 RuXC skiers averaged for the period 2014/15–2017/18. The NorXC skiers’ TrV obtained from the study by Sandbakk (2017). RuXC skiers had a lower volume of low-intensity (LIT, below aerobic threshold) and high-intensity (HIT, above anaerobic threshold) endurance training. They used a “pyramidal” model of intensity ratio during the entire macrocycle and did not decrease the volume of moderate-intensity (MIT) endurance training in competition periods (CPs). Conversely, NorXC skiers followed the “pyramidal” model of intensity in the preparation period (PP) but the “polarized” model in CP, significantly reducing the volume of MIT and increasing that of HIT. RuXC skiers increased TrVs more rapidly at the beginning of PPs, achieving TrV peak in June, and then gradually decreased them by March. NorXC skiers increased TrVs gradually by July and then maintained this approximate volume until November. RuXC skiers had peak volumes of LIT and strength training simultaneously in June; NorXC skiers engaged in large amounts of strength training in May and June until reaching maximum endurance loads. RuXC skiers had two “blocks” of strength training; NorXC skiers had three. A comparative analysis of the TrV distributions among the RuXC and NorXC skiers revealed significant similarity. Therefore, they can consider as models of the modern annual periodization of training loads for this kind of sport

Cathodoluminescence of zinc oxide crystals grown from melt under high pressure in the presence of ytterbium oxide

A mixture of poly- and single crystals of zinc and ytterbium (2 at.%) oxides have been grown from the melt at high temperature (1430°C) and high pressure (3.8 GPa). The crystals were transparent under examination with naked eye. The diameter of crystals was in the range from 0.005 to 2 mm. X-ray diffraction confirmed presence of individual zinc and ytterbium oxides in the recovered samples. No change of zinc oxide lattice parameters was observed compared to pristine zinc oxide. Cathodoluminescence spectra of the mixture were recorded at 77 and 293 K. The collected spectra exhibit UV, green and near-infrared bands due to exciton recombination, presence of oxygen vacancies and ytterbium ions in ZnO crystals, respectively

White Photoluminescence in Dy-Doped Oxyfluoride Glasses

Dy3+-doped, Ag and Dy3+-co-doped, and Tm3+ and Dy3+-co-doped oxyfluoride glasses have been prepared by a conventional melt-quenching method. White and yellowish light emissions were generated in the glasses under excitation in the range from 350 to 390 nm. Changes in the excitation wavelength in the ultraviolet (UV) range do not significantly alter the emission tint of the Dy and Ag and Dy-co-doped glasses. On the contrary, the tint of the Tm and Dy co-doped glasses considerably varies under excitation in the same range

Growth and Structure of Single-Crystal ZnO Nanorods Codoped with Fe and Li for Multiferroic Applications

ZnO nanorods codoped with Fe, Li (ZnO:Fe,Li) with a diameter of 50–100 nm and a length of 0.5–5 μm were obtained by thermal growth from salt mixtures. The HAADF-STEM, EDX, and AAS analysis showed that the nanorods grew in the [001] direction as single crystals with a wurtzite structure and contain 2.05% Fe and 1.95% Li. A detailed study of ZnO:Fe,Li nanorods using X-ray diffraction, X-ray absorption, Mössbauer spectroscopy, and cathodoluminescence spectroscopy revealed the incorporation of Fe and Li atoms into the nanocrystal lattice, which can lead to ferroelectric behavior of ZnO multiferroic structures, usually fabricated by codoping with transition metals and lithium

Wavelength-dependent nonlinear optical properties of Ag nanoparticles dispersed in a glass host

\u3cp\u3eThe linear and nonlinear optical properties of metal nanoparticles are highly tunable by variation of parameters such as particle size, shape, composition, and environment. To fully exploit this tunability, however, quantitative information on nonlinear absorption cross sections is required, as well as a sufficient understanding of the physical mechanism underlying these nonlinearities. In this work, we present a detailed and systematic investigation of the wavelength-dependent nonlinear optical properties of Ag nanoparticles embedded in a glass host, in which the most important parameters determining the nonlinear behavior of the system are characterized. This allows a proper quantification of absorption cross sections and elucidation of the excitation mechanism. Based on small-angle X-ray scattering measurements average particle diameters of 3 and 17 nm are estimated for the studied samples. The nonlinear optical properties of the nanoparticle-glass composite are studied in an extended wavelength range with the open aperture z-scan technique. The experiments reveal a strong dependence of the nonlinear optical response on the excitation wavelength. Based on the wavelength-dependent response, excited-state absorption is determined as the excitation mechanism of the nanoparticles. Electromagnetic simulations demonstrate that the contributions from electric field enhancement and plasmonic coupling between the particles in the diluted glasses are limited, which implies that the very high two-photon absorption cross section at 460 nm ((6.9 ± 1.6) × 10\u3csup\u3e6\u3c/sup\u3e GM for the 3 nm particles and (19.5 ± 2.2) × 10\u3csup\u3e9\u3c/sup\u3e GM for the 17 nm particles) is an intrinsic property. In addition, irradiance-dependent measurements elucidate the role of saturation of the excited-state absorption process on the observed nonlinearities.\u3c/p\u3

Energy-transfer luminescence of a zinc oxide/ytterbium oxide nanocomposite

© The Royal Society of Chemistry 2012. A newly structured nanocomposite material based on nanocrystalline ZnO/Yb 2 O 3 has been prepared by thermal decomposition of Yb-doped zinc carbonate hydroxide. Transmission electron microscopy has revealed that the prepared nanopowder consists of ZnO nanocrystals of about 50 to 100 nm size decorated by attached smaller Yb 2 O 3 nanocrystals of about 10 to 15 nm size. X-Ray absorption spectroscopy, in particular XANES and EXAFS, indicate the charge of Yb ions equals to +3 and their coordination is oxygen octahedral with the Yb-O and Yb-Yb interatomic distances the same as in bulk Yb 2 O 3 . Photoluminescence spectroscopy unambiguously proves an efficient excitation energy transfer from the ZnO nanocrystals to the Yb 3+ ions. The energy transfer from the ZnO nanocrystals (absorption range from 250 to 400 nm) to the Yb 3+ ions (emission range from 950 to 1100 nm) has been explained by a model, which considers the quantum cutting effect. The prepared nanocomposite is promising for application as a down-conversion layer for enhanced solar cells.status: publishe

New Hybrid Tetrahydropyrrolo[3,2,1-<i>ij</i>]quinolin-1-ylidene-2-thioxothiazolidin-4-ones as New Inhibitors of Factor Xa and Factor XIa: Design, Synthesis, and In Silico and Experimental Evaluation

Despite extensive research in the field of thrombotic diseases, the prevention of blood clots remains an important area of study. Therefore, the development of new anticoagulant drugs with better therapeutic profiles and fewer side effects to combat thrombus formation is still needed. Herein, we report the synthesis and evaluation of novel pyrroloquinolinedione-based rhodanine derivatives, which were chosen from 24 developed derivatives by docking as potential molecules to inhibit the clotting factors Xa and XIa. For the synthesis of new hybrid derivatives of pyrrolo[3,2,1-ij]quinoline-2-one, we used a convenient structural modification of the tetrahydroquinoline fragment by varying the substituents in positions 2, 4, and 6. In addition, the design of target molecules was achieved by alkylating the amino group of the rhodanine fragment with propargyl bromide or by replacing the rhodanine fragment with 2-thioxoimidazolidin-4-one. The in vitro testing showed that eight derivatives are capable of inhibiting both coagulation factors, two compounds are selective inhibitors of factor Xa, and two compounds are selective inhibitors of factor XIa. Overall, these data indicate the potential anticoagulant activity of these molecules through the inhibition of the coagulation factors Xa and XIa