Rare earth elements materials production from apatite ores

The paper deals with the study of processing apatite ores with nitric acid and extraction of the rare earth elements. The rare earth elements can be successfully separated and recovered by extraction from the nitrate- phosphate solution, being an tributyl phosphate as extraction agent. The developed scheme of the processing apatite concentrate provides obtaining rare earth concentrates with high qualitative characteristics

Профили авторов и организаций в информационных системах Dimensions и Lens: исследование возможностей

The paper demonstrates the features of author and organizational publication profiles in Dimensions and Lens information systems. In recent years, these systems have been successfully competing with many subscription-based systems. The authors discuss the advantages of these databases in terms of coverage of research content in publication profiles as compared to that of commercial bibliographic platforms, as well as the wide range of functional capabilities. As illustrated by publication profiles of two research organizations and their authors, we describe original approaches to searching bibliographic information, as well as editing bibliographic errors in databases. These features enable (a) to monitor effectively the scholarly output of research organizations and authors, and (b) to enhance visibility of research findings in the international information space. Solving information-retrieval problems and editing publication profiles of Russian organizations and authors in Dimensions and Lens prove to be similar to that of commercial systems, i. e. Web of Science and Scopus. The vast experience of working with proprietary databases and subscription-based systems, would enable Russian academic libraries to adapt to new interfaces in a short time frame.Показаны особенности работы с публикационными профилями авторов и научных организаций в информационных системах Dimensions и Lens, роль которых существенно возросла в последнее десятилетие и которые всё успешнее конкурируют с коммерческими системами. Продемонстрировано превосходство этих баз данных (БД) в наполнении публикационных профилей научным контентом по сравнению с платными библиографическими платформами, а также широкий набор их функциональных возможностей. На примере профилей двух научных учреждений и их сотрудников описаны реализованные авторами статьи подходы к поиску библиографической информации, а также к внесению необходимых корректировок в БД. Описанные подходы, с одной стороны, позволяют эффективно отслеживать публикационную активность организаций и авторов, а с другой – повышать видимость их научных результатов в международном информационном пространстве. Показано, что решение информационно-поисковых задач и редактирование публикационных профилей в Dimensions и Lens во многом схожи с ранее проводимой аналогичной работой в коммерческих системах Web of Science и Scopus. Поэтому, с учётом накопленного российскими библиотеками значительного практического опыта работы с проприетарными БД, адаптация к работе с новыми системами может быть реализована в значительно более краткие сроки

Критерии авторства и проблема его атрибуции в научных публикациях

A complication of academic research, the emergence of new subject areas at the intersection of different scientific disciplines, increase in international collaboration are accompanied by an increase in the number of co-authors resulting in the problem of author attribution requiring the development of new approaches to detecting authors’ roles and formation of new authorship criteria. The solution of the problem of authorship attribution should specify actual contribution of the scientist to preparing research and the paper, distinguish areas of responsibility of co-authors, and enable certain researchers to accumulate their own reputation capital. The current study presents a review of Russian and foreign approaches for solving this problem including the development of new sections in articles for naming persons who do not match authorship criteria and introduction of models of sequence order of authors. The paper also traces the main stages in the development of authorship criteria, describes the advantages and disadvantages of authorship model as compared to new contributorship model. Transition to the fractional calculation of the contribution of each participant of a research paper is believed to be promising implying significance of the author’s position in the byline and an increased role of paper sections describing the specific contribution of each author.Усложнение научных исследований, появление новых областей на стыках различных дисциплин, расширение международного сотрудничества способствуют росту числа авторов в расчёте на научную публикацию, а также увеличению числа соавторов. Это ведёт к проблеме атрибуции авторства, требующей разработки новых подходов к выявлению авторских ролей и формированию новых критериев авторства. Решение проблемы атрибуции авторства призвано установить действительный вклад учёного в подготовку исследования и статьи по его результатам, разграничить зоны ответственности соавторов, позволить отдельным учёным накапливать собственный репутационный капитал. В статье представлен обзор отечественных и зарубежных подходов к решению обозначенной проблемы, включая формирование новых разделов публикаций для указания лиц, не соответствующих критериям авторства, и разработку моделей упорядочения имён авторов. Прослежены основные этапы формирования критериев авторства, отражены преимущества и недостатки модели авторства посредством противопоставления новой модели описания видов участия в научном исследовании. Перспективным представляется переход к фракционному учёту вклада каждого из создателей научного произведения, при котором возрастает значение позиции авторов в авторской строке и усиливается роль разделов публикации с конкретным описанием авторского вклада

Shape resonance for the anisotropic superconducting gaps near a Lifshitz transition: the effect of electron hopping between layers

The multigap superconductivity modulated by quantum confinement effects in a superlattice of quantum wells is presented. Our theoretical BCS approach captures the low-energy physics of a shape resonance in the superconducting gaps when the chemical potential is tuned near a Lifshitz transition. We focus on the case of weak Cooper-pairing coupling channels and strong pair exchange interaction driven by repulsive Coulomb interaction that allows to use the BCS theory in the weak-coupling regime neglecting retardation effects like in quantum condensates of ultracold gases. The calculated matrix element effects in the pairing interaction are shown to yield a complex physics near the particular quantum critical points due to Lifshitz transitions in multigap superconductivity. Strong deviations of the ratio $2\Delta/T_c$ from the standard BCS value as a function of the position of the chemical potential relative to the Lifshitz transition point measured by the Lifshitz parameter are found. The response of the condensate phase to the tuning of the Lifshitz parameter is compared with the response of ultracold gases in the BCS-BEC crossover tuned by an external magnetic field. The results provide the description of the condensates in this regime where matrix element effects play a key role.Comment: 12 pages, 6 figure

Improvement of carbon black based polymer composite electrical conductivity with additions of MWCNT

Owing to their exceptional mechanical, electrical and thermal properties, carbon nanotubes (CNTs) are ideal candidates for improving the performances of polymer composites. In the present work, we investigated the effect of CNT addition on the electrical conductivity of two types of carbon black (CB) filled polymer. Also, two different methods of compounding were applied and their effects are compared: mixing by a laboratory compounder Haake Rheomix Polylab and mixing by a twin-roller mixer.Composites containing a total of 10% by weight of different carbon fillers (CB, CNTs and their mixtures in a ratio of 8/2) were thus obtained, characterized by scanning electron microscopy and their frequency dependence of the electrical conductivity was measured.It is shown that the alternating current (AC) conductivities display two regions: a low frequency region of constant conductivity and a higher frequency region of increasing conductivity with increasing frequency (following the percolation scaling law). It was also observed that the samples compounded with twin-roller mixer exhibit a higher electrical conductivity than those obtained with the laboratory compounder. Moreover, the conductivity of the composites containing CNTs in addition to CB is found to be higher than the conductivity of the composites containing only CB

Mechanical and electrical properties of ethylene-1-octene and polypropylene composites filled with carbon nanotubes

In the present work, the effect of carbon nanotubes (CNTs) addition on the electrical conductivity and mechanical properties of thermoplastic polymers was investigated. CNTs were incorporated into the polymer matrix either in high concentrations (masterbatch) or as an additive in small quantity (dilution source of masterbatches in a polymeric binder). Masterbatches containing a 5–20% by weight of CNTs and composites obtained through their addition in polypropylene - the actual content of CNTs in polymer 0.1 and 0.01 wt% - were synthesized and characterized by mechanical tests and scanning electron microscopy. Also, the frequency dependence of the AC electrical conductivity of masterbatches and dilute composites were measured. It has been shown that the introduction of masterbatches containing 10 wt% of CNT provides a more efficient reinforcement of the composite than those using masterbatches with 5 and 20 wt% of CNTs. It is also found that the alternating current (AC) conductivities display two or three regions: regions of constant conductivity and regions where the conductivity increases with increasing frequency (following the percolation scaling law). It was also observed that the conductivity increases drastically with increasing CNT content in the investigated concentration range (from 0 to 20 wt%)

Mechanical and electrical properties of ethylene-1-octene and polypropylene composites filled with carbon nanotubes

In the present work, the effect of carbon nanotubes (CNTs) addition on the electrical conductivity and mechanical properties of thermoplastic polymers was investigated. CNTs were incorporated into the polymer matrix either in high concentrations (masterbatch) or as an additive in small quantity (dilution source of masterbatches in a polymeric binder). Masterbatches containing a 5–20% by weight of CNTs and composites obtained through their addition in polypropylene - the actual content of CNTs in polymer 0.1 and 0.01 wt% - were synthesized and characterized by mechanical tests and scanning electron microscopy. Also, the frequency dependence of the AC electrical conductivity of masterbatches and dilute composites were measured. It has been shown that the introduction of masterbatches containing 10 wt% of CNT provides a more efficient reinforcement of the composite than those using masterbatches with 5 and 20 wt% of CNTs. It is also found that the alternating current (AC) conductivities display two or three regions: regions of constant conductivity and regions where the conductivity increases with increasing frequency (following the percolation scaling law). It was also observed that the conductivity increases drastically with increasing CNT content in the investigated concentration range (from 0 to 20 wt%)

Structure and Properties of Multiwall Carbon Nanotubes/Polystyrene Composites Prepared via Coagulation Precipitation Technique

Coagulation technique was applied for preparation of multiwall carbon nanotube- (MWNT-)containing polystyrene (PSt) composite materials with different MWNT loading (0.5–10 wt.%). Scanning and transmission electron microscopies were used for investigation of the morphology and structure of produced composites. It was shown that synthesis of MWNT/PSt composites using coagulation technique allows one to obtain high dispersion degree of MWNT in the polymer matrix. According to microscopy data, composite powder consists of the polystyrene matrix forming spherical particles with diameter ca. 100–200 nm, and the surface of MWNT is strongly wetted by the polymer forming thin layer with 5–10 nm thickness. Electrical conductivity of MWNT/PSt composites was investigated using a four-probe technique. Observed electrical percolation threshold of composite materials is near to 10 wt.%, mainly due to the insulating polymer layer deposited on the surface of nanotubes. Electromagnetic response of prepared materials was investigated in broadband region (0.01–4 and 26–36 GHz). It was found that MWNT/PSt composites are almost radiotransparent for low frequency region and possess high absorbance of EM radiation at higher frequencies