Journals
2015 EN
Konstantin Oblov · Anastasia Ivanova · Sergey Soloviev
+4 more
The layout of experimental samples of microhotplate based on nanocomposite material consisting of ruthenium dioxide and borosilicate glass binder were formed by selective laser sintering method. The resulting structures were used as microhotplate to measure changes in thermal conductivity of gases. The comparison of power consumption of standard platinum wire coil element widely used in thermocatalytic (calorimetric) sensors and microhotplate produced by the new technology showed strong advantage of the latter one
Journals
2015 EN
J. van der Plicht · В. И. Молодин · Yaroslav V. Kuzmin
+3 more
We obtained new data on the existence of giant deer (Megaloceros giganteus Blum.) in Siberia during the Holocene. Bones and antler of giant deer from new localities in western (Baraba forest steppe) and eastern (Angara River basin) Siberia are dated by radiocarbon, ranging 7900-10,300 BP (ca 8800-12,200 cal BP). Based on these data, we can extend the 'Siberian' Early Holocene habitat of giant deer at least 2400 km to the east compared to previous works. The final extinction of giant deer turned out to be more complex than it was previously thought, with perhaps relatively large refugium in Western Siberia at 7900-7000 BP (ca 8800-7900 cal BP) which was reduced to the Trans-Urals region at 7000-6800 BP (ca 7900-7600 cal BP)
Journals
2015 EN
Sergey Vasiliev
Taking up the torch from my fellow co-editors who have addressed substantive and methodological issues of international criminal law (ICL) in their contributions, I propose to turn to the current state and prospects of its scholarship. The moment is opportune for such a reflection. The questions raised by the production and dissemination of international legal scholarship were the leitmotif of past editorials and its (changing) role was chosen as the theme of the latest LJIL symposium. The professional functions of international legal scholars have been the subject of renewed interest and debate. To give an impulse to a similar debate in ICL, I will try to capture the zeitgeist of its academia and offer some observations on the positioning of scholarship vis-à-vis practice in ICL. Perspectives from this specialized field may enrich the existing conceptualizations of international legal scholarship and provide a new angle on its place within the profession
Cambridge University Press
Journals
2015 EN
Yuanyuan Zhou · A. L. Vasiliev · Wenwen Wu
+4 more
The crystal morphology of organolead trihalide perovskite (OTP) light absorbers can have profound influence on the perovskite solar cells (PSCs) performance. Here we have used a combination of conventional transmission electron microscopy (TEM) and high-resolution TEM (HRTEM), in cross-section and plan-view, to characterize the morphologies of a solution-processed OTP (CH3NH3PbI3 or MAPbI3) within mesoporous TiO2 scaffolds and within capping and planar layers. Studies of TEM specimens prepared with and without the use of focused ion beam (FIB) show that FIBing is a viable method for preparing TEM specimens. HRTEM studies, in conjunction with quantitative X-ray diffraction, show that MAPbI3 perovskite within mesoporous TiO2 scaffold has equiaxed grains of size 10-20 nm and relatively low crystallinity. In contrast, the grain size of MAPbI3 perovskite in the capping and the planar layers can be larger than 100 nm in our PSCs, and the grains can be elongated and textured, with relatively high crystallinity. The observed differences in the performance of planar and mesoscopic-planar hybrid PSCs can be attributed in part to the striking differences in their perovskite-grain morphologies.
American Chemical Society
Journals
2015 EN
C. H. P. Wen · H. C. Xu · C. Chen
+9 more
In FeSe-derived superconductors, the lack of a systematic and clean controlon the carrier concentration prevents the comprehensive understanding on thephase diagram and the interplay between different phases. Here by K dosing andangle resolved photoemission study on thick FeSe films andFeSe$_{0.93}$S$_{0.07}$ bulk crystals, the phase diagram of FeSe as a functionof electron doping is established, which is extraordinarily different fromother Fe-based superconductors. The correlation strength remarkably increaseswith increasing doping, while an insulting phase emerges in the heavilyoverdoped regime. Between the nematic phase and the insulating phase, a dome ofenhanced superconductivity is observed, with the maximum superconductingtransition temperature of 44$\pm$2~K. The enhanced superconductivity isindependent of the thickness of FeSe, indicating that it is intrinsic to FeSe.Our findings provide an ideal system with variable doping for understanding thedifferent phases and rich physics in the FeSe family.
Journals
2015 EN
Qisi Wang · Yao Shen · Bingying Pan
+13 more
Elucidating the microscopic origin of nematic order in iron-basedsuperconducting materials is important because the interactions that drivenematic order may also mediate the Cooper pairing. Nematic order breaksfourfold rotational symmetry in the iron plane, which is believed to be drivenby either orbital or spin degrees of freedom. However, as the nematic phaseoften develops at a temperature just above or coincides with a stripe magneticphase transition, experimentally determining the dominant driving force ofnematic order is difficult. Here, we use neutron scattering to studystructurally the simplest iron-based superconductor FeSe, which displays anematic (orthorhombic) phase transition at $T_s=90$ K, but does not orderantiferromagnetically. Our data reveal substantial stripe spin fluctuations,which are coupled with orthorhombicity and are enhanced abruptly on cooling tobelow $T_s$. Moreover, a sharp spin resonance develops in the superconductingstate, whose energy (~4 meV) is consistent with an electron boson coupling moderevealed by scanning tunneling spectroscopy, thereby suggesting a spinfluctuation-mediated sign-changing pairing symmetry. By normalizing the dynamicsusceptibility into absolute units, we show that the magnetic spectral weightin FeSe is comparable to that of the iron arsenides. Our findings supportrecent theoretical proposals that both nematicity and superconductivity aredriven by spin fluctuations.
Journals
2015 EN
Soon-Gil Jung · Ji-Hoon Kang · Eunsung Park
+5 more
We investigate the relation of the critical current density (Jc) and theremarkably increased superconducting transition temperature (Tc) for the FeSesingle crystals under pressures up to 2.43 GPa, where the Tc is increased by ~8K/GPa. The critical current density corresponding to the free flux flow ismonotonically enhanced by pressure which is due to the increase in Tc, whereasthe depinning critical current density at which the vortex starts to move ismore influenced by the pressure-induced magnetic state compared to the increaseof Tc. Unlike other high-Tc superconductors, FeSe is not magnetic, butsuperconducting at ambient pressure. Above a critical pressure where magneticstate is induced and coexists with superconductivity, the depinning Jc abruptlyincreases even though the increase of the zero-resistivity Tc is negligible,directly indicating that the flux pinning property compared to the Tcenhancement is a more crucial factor for an achievement of a large Jc. Inaddition, the sharp increase in Jc in the coexisting superconducting phase ofFeSe demonstrates that vortices can be effectively trapped by the competingantiferromagnetic order, even though its antagonistic nature againstsuperconductivity is well documented. These results provide new guidance towardtechnological applications of high-temperature superconductors.
Journals
2015 EN
A. N. Vasiliev · Nidhu Lal Banik · Rémi Marsac
+4 more
Low molecular weight organics (LMWO; e.g. acetate, propionate, lactate) can significantly impact the speciation and mobility of radionuclides in aqueous media. Natural clay rock formation, considered as a potential host rock for nuclear waste disposal, can contain a significant amount of organic matter. There are less thermodynamic data reported for the complexation of pentavalent actinides with LMWO, especially under elevated temperature conditions, relevant for assessing the long-term safety of disposal options for heat-producing high-level nuclear waste. In the present study, the complexation of Np(v) with propionate is studied using spectroscopic techniques in 0.5-4 M NaCl solutions by systematic variation of the ligand concentration and temperature. Slope analysis shows the formation of the 1 : 1 NpO2-propionate complex (NpO2Prop). The local structure of the NpO2-propionate complex is determined by extended X-ray absorption fine structure spectroscopy, the results of which suggest that propionate binds to Np(v) in a bidentate mode. Using the specific ion interaction theory (SIT), the stability constant at zero ionic strength and 25 °C is determined as log β°1,1 = 1.26 ± 0.03. The stability constants increase continuously with increasing temperature between 20 and 85 °C. The log β0 values are linearly correlated with the reciprocal temperature, indicating ΔrH = const. and ΔrC = 0, allowing the calculation of ΔrH and ΔrS for the formation of the NpO2-propionate complex using the integrated van't Hoff equation. The thermodynamic evaluation indicates that the reaction is endothermic and entropy driven.
Royal Society of Chemistry
Journals
2015 EN
Nadezda V. Tarakina · А. P. Tyutyunnik · Г. В. Базуев
+4 more
The authors regret a spelling mistake in the surname of one of authors. The surname given as ‘Vasilev’ should be ‘Vasiliev’.Furthermore a second affiliation for the author A. D. Vasiliev was inadvertently omitted. The correct spelling and affiliations ofall the authors for this paper is as shown above.The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers
Royal Society of Chemistry
Journals
2015 EN
E. A. Zvereva · M. I. Stratan · A. V. Ushakov
+6 more
We report the revised crystal structure, static and dynamic magneticproperties of quasi-two dimensional honeycomb-lattice silver delafossiteAg3Co2SbO6. The magnetic susceptibility and specific heat data are consistentwith the onset of antiferromagnetic long range order at low temperatures withN\'eel temperature TN ~ 21.2 K. In addition, the magnetization curves revealeda field-induced (spin-flop type) transition below TN in moderate magneticfields. The GGA+U calculations show the importance of the orbital degrees offreedom, which maintain a hierarchy of exchange interaction in the system. Thestrongest antiferromagnetic exchange coupling was found in the shortest Co-Copairs and is due to direct and superexchange interactions between thehalf-filled xz+yz orbitals pointing directly to each other. The other four outof six nearest neighbor exchanges within the cobalt hexagon are suppressed,since for these bonds active half-filled orbitals turned out to be parallel anddo not overlap. The electron spin resonance (ESR) spectra reveal a Gaussianshape line attributed to Co2+ ion in octahedral coordination with averageeffective g-factor g=2.3+/-0.1 at room temperature and shows strong divergenceof ESR parameters below 120 K, which imply an extended region of short-rangecorrelations. Based on the results of magnetic and thermodynamic studies inapplied fields, we propose the magnetic phase diagram for the newhoneycomb-lattice delafossite.
Royal Society of Chemistry