Conventional superconductivity at 203 K at high pressures

A superconductor is a material that can conduct electricity with no resistance below its critical temperature (Tc). The highest Tc that has been achieved in cuprates1 is 133 K at ambient pressure2 and 164 K at high pressures3. As the nature of superconductivity in these materials has still not been explained, the prospects for a higher Tc are not clear. In contrast, the Bardeen-Cooper-Schrieffer (BCS) theory gives a guide for achieving high Tc and does not put bounds on Tc, all that is needed is a favorable combination of high frequency phonons, strong electron-phonon coupling, and a high density of states. These conditions can be fulfilled for metallic hydrogen and covalent compounds dominated by hydrogen4,5. Numerous calculations support this idea and predict Tc of 50-235 K for many hydrides6 but only moderate Tc=17 K has been observed experimentally7. Here we studied sulfur hydride8 where a Tc~80 K was predicted9. We found that it transforms to a metal at pressure ~90 GPa. With cooling superconductivity was found deduced from a sharp drop of the resistivity to zero and a decrease of Tc with magnetic field. The pronounce isotope shift of Tc in D2S is evidence of an electron-phonon mechanism of superconductivity that is consistent with the BCS scenario. The superconductivity has been confirmed by magnetic susceptibility measurements with Tc=203K. The high Tc superconductivity most likely is due to H3S which is formed from H2S under its decomposition under pressure. Even higher Tc, room temperature superconductivity, can be expected in other hydrogen-based materials since hydrogen atoms provide the high frequency phonon modes as well as the strong electron-phonon coupling

Experience in the implementation of palliative, combined and expanded operations in emergency surgery of gastric cancer

В статье рассмотрен опыт выполнения неотложных абдоминальных онкохирургических операций, выполненных на базе отделения абдоминальной онкологии за период 2012–2014 гг. Всего в исследование включен 51 больной, которым выполнены ургентные и срочные плановые операции по поводу осложнений рака желудка. Всего выполнено 27 паллиативных, 6 расширенных, 15 комбинированных операций. По-настоящему ургентных было только 2, во время которых были выполнены в обоих случаях гастрэктомии со спленэктомией без выполнения расширенных лимфодиссекций. Сделан вывод, что выполнение радикальных операций не увеличивает летальность при осложненном течении рака желудка. В мировой ургентной медицине используются различные классификации срочных, в т. ч. неотложных операций, наиболее унифицированной из которых является классификация WSES-2013. Традиционное, “отечественное” распределение неотложных онкологических операций на ургентные/срочные/плановые или даже чаще на ургентные/ плановые является устоявшимся и необходимым. Индивидуализация подхода к каждой ургентной операции, как и вообще тенденция к индивидуализации в онкологии, представляется неотъемлемым мотивом грядущих методологических перемен в неотложной онкохирургии.The article describes the experience of urgent oncosurgical abdominal operations carried out on the basis of Abdominal Oncology Department for the period 2012–2014 years. In total, the study included 51 patients, who underwent emergent and urgent elective surgery for complications of stomach cancer. Total holds 27 palliative, 6 advanced, 15 combined operations. The really emergent were only 2, during which were performed in both cases gastrectomy with splenectomy without performing extended lymph node dissection. It was concluded that the implementation of radical surgery does not increase mortality rate in complicated gastric cancer. In the world of emergent medicine there are used different classification approaches, including emergency operations, most of which is a unified classification WSES-2013. The traditional distribution of urgent cancer operations in urgent / emergency / routine or even more frequently in the urgent / routine is well established and necessary. Personalisation approach to each of urgent surgical case, as well as general trend towards individualization in oncology seems to be inherent motive of future methodological changes in emergency cancer surgery

колективна монографія

Кримінальний процесуальний кодекс 2012 року: ідеологія та практика правозастосування: колективна монографія / за заг. ред. Ю. П. Аленіна ; відпов. за вип. І. В. Гловюк. - Одеса : Видавничий дім «Гельветика», 2018. - 1148 с

Biological approaches to artificial photosynthesis: general discussion

Metals in Catalysis, Biomimetics & Inorganic Material

Synthetic approaches to artificial photosynthesis: general discussion

Metals in Catalysis, Biomimetics & Inorganic Material

Correlation Between T_c and Hyperfine Parameters of Fe in Layered Chalcogenide Superconductors

Although pairing mechanism in unconventional superconductors is still an open question, the density of states at the Fermi level is considered to be one of the factors affecting the superconducting transition temperature. Herein, we report on Fe-57-Mossbauer studies of beta-FeSe, FeSe Te-0.5 (0.5), and Rb Fe-0.8 Se-1.6 (2) superconductors as well as two intercalate products consisting of FeSe layers and a lithium-containing molecular spacer in between. In these materials, the hyperfine parameters of Fe-57 are directly related to the 3d-electron density on Fe atoms and show strong correlation with superconducting properties

Phase Separation in Rb_xFe_2-ySe₂ Probed by Non-stoichiometry and Cu Doping

The paper presents Mossbauer spectroscopy investigation on superconducting Rb Fe-0.8 Se-1.6 (2) exhibiting nanoscale phase separation and two its derivatives: Cu-doped Rb Fe-0.8 Cu-1.56 Se-0.04 (2) and Fe-deficient Rb Fe-0.7 Se-1.4 (2). The spectra reveal the presence of the same dominant magnetic sextet in the samples, which is assigned to the Fe 16i sites of the ae5xae5x1 superstructure. This magnetic part is independent on the modification of the sample and does not undergo any changes after doping or deviation of stoichiometry. In contrast, the minor non-magnetic doublet in the spectra of Rb Fe-0.8 Se-1.6 (2), which is attributed to the superconducting nanoscale phase, is sensitive to such modifications. After doping with Cu, the relative intensity of non-magnetic doublet significantly decreases together with suppression of superconductivity. On the other hand, the Fe-deficient sample is entirely magnetically ordered below 250 K including in the minor nanoscale phase. A discussion of Mossbauer spectroscopic data and comparison with previous studies on other Fe chalcogenide analogues allow to conclude the nanosized phase separation is also observed in non-stoichiometric and doped modifications of Rb Fe-0.8 Se-1.6 (2)

Intercalation effect on hyperfine parameters of Fe in FeSe superconductor with T_c=42K

Fe-57-Mossbauer spectra of superconducting beta-FeSe, the Li/NH3 intercalate product and a subsequent sample of this intercalate treated with moist He gas have been measured in the temperature range 4.7-290 K. A correlation is established between hyperfine parameters and critical temperature T-c in these phases. A strong increase of the isomer shift upon intercalation is explained by a charge transfer from the Li/NH3 intercalate to the FeSe layers resulting in an increase of Tc up to 42K. A significant decrease of the quadrupole splitting above 240 K has been attributed to diffusive motion of Li+ ions within the interlamellar space. Copyright (C) EPLA, 201