The Mediterranean problems in the context of the international aspects of the civil war in Spain 1936-1939

In their study, the researchers has made an attempt to analyze such international aspects of the Spanish Civil War as the Mediterranean aspect. The researchers looks at it in the context of international relations on the base of the materials from the Archives of Foreign policy of the Russian Ministry of Foreign Affairs, published diplomacy documents of main European countrie

Specific heat of Ca0.32_{0.32}Na0.68_{0.68}Fe2_2As2_2 single crystals: unconventional s±_\pm multi-band superconductivity with intermediate repulsive interband coupling and sizable attractive intraband couplings

We report a low-temperature specific heat study of high-quality single crystals of the heavily hole doped superconductor Ca$_{0.32}$Na$_{0.68}$Fe$_2$As$_2$. This compound exhibits bulk superconductivity with a transition temperature $T_c \approx 34$\,K, which is evident from the magnetization, transport, and specific heat measurements. The zero field data manifests a significant electronic specific heat in the normal state with a Sommerfeld coefficient $\gamma \approx 53$ mJ/mol K$^{2}$. Using a multi-band Eliashberg analysis, we demonstrate that the dependence of the zero field specific heat in the superconducting state is well described by a three-band model with an unconventional s$_\pm$ pairing symmetry and gap magnitudes $\Delta_i$ of approximately 2.35, 7.48, and -7.50 meV. Our analysis indicates a non-negligible attractive intraband coupling,which contributes significantly to the relatively high value of $T_c$. The Fermi surface averaged repulsive and attractive coupling strengths are of comparable size and outside the strong coupling limit frequently adopted for describing high-$T_c$ iron pnictide superconductors. We further infer a total mass renormalization of the order of five, including the effects of correlations and electron-boson interactions.Comment: 8 Figures, Submitted to PR

Evidence for Triplet Superconductivity in a Superconductor-Ferromagnet Spin Valve

We have studied the dependence of the superconducting (SC) transition temperature on the mutual orientation of magnetizations of Fe1 and Fe2 layers in the spin valve system CoO_x/Fe1/Cu/Fe2/Pb. We find that this dependence is nonmonotonic when passing from the parallel to the antiparallel case and reveals a distinct minimum near the orthogonal configuration. The analysis of the data in the framework of the SC triplet spin valve theory gives direct evidence for the long-range triplet superconductivity arising due to noncollinearity of the two magnetizations.Comment: 5 pages (including 4 EPS figures). Version 2: final version as published in PR

First coordination polymer based on diterpenoids. Synthesis, structure, and magnetic properties

© 2017, Springer Science+Business Media, LLC. One-dimensional coordination polymer was obtained by cation exchange reaction of triethylammonium salt of methyl ent-16α-H-phosphonyloxybeyeran-19-oate with CuCl 2 . Its structure was determined by single crystal X-ray diffraction analysis. The formation of hydrophilic channels consisting of phosphorus containing fragments, copper atoms, and water, which are framed by hydrophobic surroundings from tetracyclic bulky beyeran substituents, is observed in the crystal. The study of the temperature dependence of the static magnetic susceptibility of the polymer indicates a weak antiferromagnetic interaction between the copper spins

Electron Transfer and Unusual Chemical Transformations of F4-TCNQ in a Reaction with Mn-Phthalocyanine

© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim The interaction of manganese phthalocyanine with F4-TCNQ is accompanied by the transformation of the acceptor molecule into a new organic ligand, the 4-(dicyanomethanido)tetra-fluorobenzoate dianion, resulting in the formation of a unique MnIII charge-transfer complex, in which two Mn phthalocyanine moieties are bridged by the dianion, with parallel arrangement of all aromatic fragments and an interplanar distance of 3.30 Å. The formation of the complex takes place in a 2:1 ratio, with the two electrons transferring from two donor molecules to an acceptor molecule. Magnetic measurements reveal that MnIII ions in the studied complex occur in the high-spin state S = 2 and are coupled antiferromagnetically, presumably by the superexchange mechanism through the 4-(dicyanomethanido)tetrafluorobenzoate dianion bridge, with an interaction constant of J = 5 cm–1 (7 K). According to the electrochemical data, the new complex appears to have unusual redox properties and might be described as an electronic reservoir with strong acceptor ability, being able to take seven electrons. Notably, all of the reduction–oxidation steps are reversible, proceeding without structural changes

Several aspects of stellate ganglion block

Background and Study Goal. Stellate ganglion block (SGB) has been used in the treatment of cerebral derangements associated with headache, for the purpose of reliving spasm and presumably increasing the cerebral blood flow, normalizing endovascular resistance. Materials and Methods. 30 volunteers underwent unilateral SGB, 30–40 years (21 females, 9 males), with cluster headache. 5 ml 0,25 % ropivacaine were administered + 4 mg dexamethasone under C6 level paratracheal ultrasound guid. The confirmation was the presence of Horner´s syndrome. The resistive index (RI) was measured by ultrosound transcranial CV doppler of middle cerebral artery at the baseline and 1 min, and 10 min after SGB on both sides (the other side was taken for control). Normal values of RI corresponded to the age. Results and discussion. Our observations showed that after SGB in all patients there was a significant change in RI with normalization of cerebral blood flow, reduction or disappearance of headache. Conclusions. The difference between the block and the nonblock sides was significant before procedure (p < 0,0001) and after 10 min become the same with an insignificant difference (p = 0,001). A higher RI in patients with a cluster headache may be as an indicator for choosing the block side. Ultrasound technique will be helpfull for providing safe block and effect control