Low-energy quasiparticle states at superconductor-CDW interfaces

Quasiparticle bound states are found theoretically on transparent interfaces of d-wave superconductors (dSC) with charge density wave solids (CDW), as well as s-wave superconductors (sSC) with d-density waves (DDW). These bound states represent a combined effect of Andreev reflection from the superconducting side and an unconventional quasiparticle Q-reflection from the density wave solid. If the order parameter for a density wave state is much less than the Fermi energy, bound states with almost zero energy take place for an arbitrary orientation of symmetric interfaces. For larger values of the order parameter, dispersionless zero-energy states are found only on (110) interfaces. Two dispersive energy branches of subgap quasiparticle states are obtained for (100) symmetric interfaces. Andreev low-energy bound states, taking place in junctions with CDW or DDW interlayers, result in anomalous junction properties, in particular, the low-temperature behavior of the Josephson critical current.Comment: 6 pages, 2 figure

Coherent transport in homojunction between excitonic insulator and semimetal

From the solution of a two-band model, we predict that the thermal and electrical transport across the junction of a semimetal and an excitonic insulator will exhibit high resistance behavior and low entropy production at low temperatures, distinct from a junction of a semimetal and a normal semiconductor. This phenomenon, ascribed to the dissipationless exciton flow which dominates over the charge transport, is based on the much longer length scale of the change of the effective interface potential for electron scattering due to the coherence of the condensate than in the normal state.Comment: RevTeX 4.0, 13 pages, 5 b/w figures, 1 colour figure, 1 table. Version modified with respect to the original, which will appear in Physical Review Letters. This version includes the supplementary (EPAPS) material as an Appendix, and it is slightly longer than the accepted version (more text and references

The Financial Component of the Scientific Publication’s Value Original article

Publication activity in modern society is presented as a driving force of scientific and technological development and as an indicator of university management reporting. The article is devoted to the study of approaches to determining the monetary value of a scientific publication, taking into account different behavior’s motives of researchers and teachers in higher education as authors. The methodological basis of the study was formed by concepts of creating a public good and financial good, concepts of scientific productivity and academic remuneration, neoclassical and neoinstitutional economic theories, approaches to the implementation of state policy in the field of science and education in terms of stimulating scientific publications. Research methods: critical and comparative analysis, with the inclusion of three groups of methods: a) the study of direct and indirect authors’ motives and traps in the publication of scientific papers; b) asset evaluation methods; c) a combination of socio-economic campaigns for monetary evaluation of the results of scientific research. Asset valuation approaches have been adapted to assess the scientific publication’s value from the position of the author as a beneficiary. The theoretical and practical significance of the research lies in the contribution to the value dimension of scientific publications for their authors in the conditions of academic capitalism with potential opportunities to receive monetary income from the results of their research

Current Problems of the Tertiary Education Modernization and Reform Practices

The sphere of postgraduate studies is the most governance reform-sensitive element of high school educational system in Russia.The article focuses on the governmental decisions taken to address difficulties in high school modernization sphere. The article posits that the mainstream modernization vector of educational system connected with the upgraded scientific and pedagogical personnel education is performed in accordance with transformational process set forth in Bologna declaration signed by the Russian Federation. The Covid-19 pandemic challenged the postgraduate reform results in Russia. The article provides a thorough and discourse analysis of scientific publications, expert interviews and normative documents. The study concludes that the set of fundamental approaches to further Russian system of postgraduate studies is currently semi-functional.Current reforms seek to overcome a destructive impact of the current postgraduate studies system

Comparative study of hydrotalcite-derived supported Pd₂Ga and PdZn intermetallic nanoparticles as methanol synthesis and methanol steam reforming catalysts

An effective and versatile synthetic approach to produce well-dispersed supported intermetallic nanoparticles is presented that allows a comparative study of the catalytic properties of different intermetallic phases while minimizing the influence of differences in preparation history. Supported PdZn, Pd2Ga, and Pd catalysts were synthesized by reductive decomposition of ternary Hydrotalcite-like compounds obtained by co-precipitation from aqueous solutions. The precursors and resulting catalysts were characterized by HRTEM, XRD, XAS, and CO-IR spectroscopy. The Pd2+ cations were found to be at least partially incorporated into the cationic slabs of the precursor. Full incorporation was confirmed for the PdZnAl-Hydrotalcite-like precursor. After reduction of Ga- and Zn-containing precursors, the intermetallic compounds Pd2Ga and PdZn were present in the form of nanoparticles with an average diameter of 6 nm or less. Tests of catalytic performance in methanol steam reforming and methanol synthesis from CO2 have shown that the presence of Zn and Ga improves the selectivity to CO2 and methanol, respectively. The catalysts containing intermetallic compounds were 100 and 200 times, respectively, more active for methanol synthesis than the monometallic Pd catalyst. The beneficial effect of Ga in the active phase was found to be more pronounced in methanol synthesis compared with steam reforming of methanol, which is likely related to insufficient stability of the reduced Ga species in the more oxidizing feed of the latter reaction. Although the intermetallic catalysts were in general less active than a Cu-/ZnO-based material prepared by a similar procedure, the marked changes in Pd reactivity upon formation of intermetallic compounds and to study the tunability of Pd-based catalysts for different reactions

Electron transport through a mesoscopic metal-CDW-metal junction

In this work we study the transport properties of a finite Peierls-Fr\"ohlich dielectric with a charge density wave of the commensurate type. We show that at low temperatures this problem can be mapped onto a problem of fractional charge transport through a finite-length correlated dielectric, recently studied by Ponomarenko and Nagaosa [Phys. Rev. Lett {\bf 81}, 2304 (1998)]. The temperature dependence of conductance of the charge density wave junction is presented for a wide range of temperatures.Comment: Latex, Revtex 3.0, 7 pages, 2 EPS figures (uses epfs

ĐẶC ĐIỂM ĐỊA HÓA THẠCH HỌC ĐÁ MAGMA BAZAN VÀ ĐẶC ĐIỂM NGUỒN MANTI KHU VỰC BIỂN ĐÔNG VÀ LÂN CẬN TRONG KAINOZOI

The East Vietnam Sea is one of the largest marginal basins in western Pacific Ocenan, formed by breaking of continental margin in the Late Mesozoic. Geochemical data of the Miocene - Pleistocene bazanic samples collected in the East Sea and neighboring areas show two major eruption trends that reflect the formation and development of the region. The early eruption event is characterized by low alkaline, TiO2, Na2O, K2O and P2O5, and high SiO2 group, comprising olivine and tholeiitic bazans. The later eruption demonstrates high alkaline, TiO2, Na2O, K2O and P2O5, and low SiO2 group, mainly generated by central-type volcanic eruptions, consisting of alkaline olivine and olivine bazans. Distinctive geochemistry of the volcanic rocks within the East Vietnam Sea and adjacent areas is illustrated by wide range of Magnesium index (Mg#= 35-75). At the values of Mg#>65, the relation between Mg# and major oxides is unclear. In contrast, Mg#65 (Olivine differentiation) the isotope ratios start changing. The primitive components are computed based on the principle of olivine compensation. The computed results show that the critical pressure for Tholeiite melting was estimated from ~11.97-20.33 Kb (ca. 30 - 60 km deep) and the Alkaline melting pressure varies from ~16.87-34.93 Kb (corresponding to the depths of ~60 km to 100 km). The continuous range of melting pressures suggests two trends of tholeiitic and alkaline eruptions occurr at various depths in the same magmatic source. Hight temperature and melting pressure of the primitive magma are dependent on partial melting pressure. Possibly, this process was triggered by the asthenosphere intrusion resulted from the closure of the Neo-Tethys following the India - Eurasia collision. This event has not only made the mantle hotter and easily melted but also triggered the opening of the marginal seas, including the East Vietnam Sea.Biển Đông là một trong những biển rìa lớn nhất thuộc rìa tây Thái Bình Dương hình thành do phá vỡ một bộ phận của rìa lục địa vào cuối Mesozoi. Kết quả thành phần địa hóa các đá bazan tuổi Miocen - Pleitocen khu vực Biển Đông và lân cận cho thấy hai xu thế phun trào chính phản ánh quá trình hình thành và phát triển khu vực. Xu thế phun trào sớm có đặc điểm thấp Kiềm, TiO2 và P2O5 và cao SiO2 chủ yếu là các Tholeit, Olivin bazan. Xu thế phun trào muộn thường cao Kiềm, TiO2 và P2O5 và cao SiO2, chủ yếu tập trung tại các khu vực phun trào kiểu trung tâm, thành phần là các bazan Olivin và Nephenin. Đặc trưng địa hóa của đá núi lửa khu vực Biển Đông và lân cận là sự phân bố rộng của chỉ số Magie (Mg#=35-75). Tại giá trị Mg#>65, quan hệ giữa Mg# và các hợp phần oxit chính là không rõ ràng. Ngược lại, tại giá trị Mg

Orientation-controlled, low-temperature plasma growth and applications of h-BN nanosheets

Dimensionality and orientation of hexagonal boron nitride (h-BN) nanosheets are promising to create and control their unique properties for diverse applications. However, low-temperature deposition of vertically oriented h-BN nanosheets is a significant challenge. Here we report on the low-temperature plasma synthesis of maze-like h-BN nanowalls (BNNWs) from a mixture of triethylamine borane (TEAB) and ammonia at temperatures as low as 400 °C. The maze-like BNNWs contained vertically aligned stacks of h-BN nanosheets. Wavy h-BN nanowalls with randomly oriented nanocrystalline structure are also fabricated. Simple and effective control of morphological type of BNNWs by the deposition temperature is demonstrated. Despite the lower synthesis temperature, thermal stability and oxidation resistivity of the maze-like BNNWs are higher than for the wavy nanowalls. The structure and oxidation of the nanowalls was found to be the critical factor for their thermal stability and controlled luminescence properties. Cytotoxic study demonstrated significant antibacterial effect of both maze-like and wavy h-BN nanowalls against E. coli. The reported results reveal a significant potential of h-BN nanowalls for a broad range of applications from electronics to biomedicine. [Figure not available: see fulltext.]. © 2018, Tsinghua University Press and Springer-Verlag GmbH Germany, part of Springer Nature