Cu NMR evidence for enhanced antiferromagnetic correlations around Zn impurities in YBa2Cu3O6.7

Doping the high-Tc superconductor YBa2Cu3O6.7 with 1.5 % of non-magnetic Zn impurities in CuO2 planes is shown to produce a considerable broadening of 63Cu NMR spectra, as well as an increase of low-energy magnetic fluctuations detected in 63Cu spin-lattice relaxation measurements. A model-independent analysis demonstrates that these effects are due to the development of staggered magnetic moments on many Cu sites around each Zn and that the Zn-induced moment in the bulk susceptibility might be explained by this staggered magnetization. Several implications of these enhanced antiferromagnetic correlations are discussed.Comment: 4 pages including 2 figure

Activation of students ' activity in the conditions of training in cooperation technology

Competence-based approach, becoming dominant in the system of higher education, marked the transition from traditional methods and means of education to the use of innovative technologies. Modern higher schools under the influence of the requirements of Federal state educational standards seek to optimize their own activities in order to improve the quality of education and seek new ways to build competence. Today, within the framework of the competence-based approach having a practice-oriented focus, technologies of training in cooperation that meet the requirements for modern training of students are becoming more popular. The purpose of the article is to present the experience of using learning technologies in cooperation, activating the students’ performance. A powerful argument in favor of training in cooperation technologies implementation is their wide functionality in the development of professional competence of a specialist. Since the development of student competence takes place within the framework of various activities, we consider the technology of training in cooperation, allowing students to maximize their potential in the process of interaction with classmates. The article identifies such important advantages of the technology under consideration as the development of independence, creative component, skills of effective interaction and the ability to conduct a constructive dialogue. We consider ideas of training in cooperation technology in detail as well as carry the analysis on the example of pedagogical courses. The presented research allowed establishing increase of students’ activity in studying of pedagogical courses at the expense of identification of an average score in studied profiles

Продовольственная безопасность, продовольственные потери и фудшеринг: концептуальный анализ

Authors emphasize that food in the modern world is becoming less accessible due to the present global economic, geopolitical and climatic situation. At the same time a large share of food produced in the world goes to waste. It means that there is a need to implement tools that could provide people with access to food and reduce amount of food waste. Food sharing, a novel tool of collaborative food consumption, can be used to solve this problem. The paper introduces the concept of distributive food sharing and describes its different types. A description of the present state of distributive food sharing in Russia. We state that the environment for development of distributive food sharing in Russia is not favorable. The main conclusion of the article is the need to create conditions for the development of the concept of food sharing to provide those in need with food and minimize waste.Авторы подчеркивают, что в современном мире продукты питания становятся все менее доступными в связи со сложившейся глобальной экономической, геополитической и климатической ситуацией. В то же время значительная часть производимого в мире продовольствия используется нерационально и попадает в отходы. Это означает, что существует необходимость внедрения инструментов, которые могли бы обеспечить людям доступ к продуктам питания и сократить количество пищевых отходов. Для решения этой проблемы может быть использована раздача продовольствия как новый инструмент коллаборативного потребления еды. В статье представлено понятие распределительного способа раздачи продуктов питания и описаны его различные виды. Описано современное состояние распределительного способа раздачи продуктов питания в России. Мы констатируем, что условия для развития распределительного способа раздачи продовольствия в России неблагоприятны. Основной вывод статьи —  необходимо создать условий для развития концепции раздачи продовольствия для обеспечения нуждающихся слоев населения продуктами питания и для минимизации количества выбрасываемого продовольствия

Phase diagram of YBa2_2Cu3_3O7−y_{7-y} at T<<Tc_c based on Cu(2) transverse nuclear relaxation

Two maxima in transverse relaxation rate of Cu(2) nuclei in YBa$_2$Cu$_3$O$_{7-y}$ are observed, at T = 35 K and T = 47 K. Comparison of the $^{63}$Cu(2) and $^{65}$Cu(2) rates at T = 47 K indicates the magnetic character of relaxation. The enhancement at T = 47 K of fluctuating local magnetic fields perpendicular to the CuO$_2$ planes is connected with the critical fluctuations of orbital currents. Maximum at T = 35 K is connected with the appearance of inhomogeneous supeconducting phase. Together with data published to date, our experimental results allow to suggest a qualitatively new phase diagram of the superconducting phase.Comment: 4 LaTEX pages + 3 figures in *.ps forma

63Cu NMR Evidence for Enhanced Antiferromagnetic Correlations around Zn Impurities in YBa2Cu3O6.7

Doping the high-Tc, superconductor YBa2Cu3O6.7- with 1.5% of nonmagnetic Zn impurities in CuO2 planes is shown to produce a considerable broadening of 63Cu NMR spectra, as well as an increase of low-energy magnetic fluctuations detected in 63Cu spin-lattice relaxation measurements. A modelindependent analysis demonstrates that these effects are due to the development of staggered magnetic moments on many Cu sites around each Zn and that the Zn-induced moment in the bulk susceptibility might be explained by this staggered magnetization. Several implications of these enhanced antiferromagnetic correlations are discussed

Chemical evolution of cementitious materials with high proportion of fly ash and slag

Cement mixtures containing high proportions of slag and fly ash were tested to assess their suitability to immobilize simulated off-gas waste solutions after vitrification of low-level radioactive tank wastes stored at Hanford. Materials were mixed with carbonated or alkaline solutions and cured initially adiabatically, then at 70{degrees}C. Chemical changes were monitored for 7 months using X-ray diffraction, selective dissolution and SEM; NMR was utilized to follow the polymerization of silicate species. The process of hydration during the first months of curing was characterized by formation of quite crystalline Al-substituted C-S-H structurally related to 1.1 nm tobermorite and traces of zeolites in some materials. A low content of calcium hydroxide was found in all materials after I month of curing. The SEM examination demonstrated rapidly decreasing porosity, making the mixtures favorable for long-term durability

Spin dynamics and ordering of a cuprate stripe-antiferromagnet

In La1.48Nd0.4Sr0.12CuO4 the 139La and 63Cu NQR relaxation rates and signal wipe-out upon lowering temperature are shown to be due to purely magnetic fluctuations. They follow the same renormalized classical behavior as seen in neutron data, when the electronic spins order in stripes, with a small spread in spin stiffness (15% spread in activation energy). The La signal, which reappears at low temperatures, is magnetically broadened and experiences additional wipe-out due to slowing down of the Nd fluctuations.Comment: 4 pages including 3 figures - ref. 16 adde

Two novel mutations associated with ataxia-telangiectasia identified using an ion ampliSeq inherited disease panel

© 2017 Kuznetsova, Trofimov, Shubina, Kochetkova, Karetnikova, Barkov, Bakharev, Gusev and Sukhikh. Ataxia-telangiectasia (A-T), or Louis-Bar syndrome, is a rare neurodegenerative disorder associated with immunodeficiency. For families with at least one affected child, timely A-T genotyping during any subsequent pregnancy allows the parents to make an informed decision about whether to continue to term when the fetus is affected. Mutations in the ATM gene, which is 150 kb long, give rise to A-T; more than 600 pathogenic variants in ATM have been characterized since 1990 and new mutations continue to be discovered annually. Therefore, limiting genetic screening to previously known SNPs by PCR or hybridization with microarrays may not identify the specific pathog enic genotype in ATM for a given A-T family. However, recent developments in next-generation sequencing technology offer prompt high-throughput full-length sequencing of genomic fragments of interest. This allows the identification of the whole spectrum of mutations in a gene, including any novel ones. We report two A-T families with affected children and current pregnancies. Both families are consanguineous and originate from Caucasian regions of Russia and Azerbaijan. Before our study, no ATM mutations had been identified in the older children of these families. We used ion semiconductor sequencing and an Ion AmpliSeq ™ Inherited Disease Panel to perform complete ATM gene sequencing in a single member of each family. Then we compared the experimentally determined genotype with the affected/normal phenotype distribution in the whole family to provide unambiguous evidence of pathogenic mutations responsible for A-T. A single novel SNP was allocated to each family. In the first case, we found a mononucleotide deletion, and in the second, a mononucleotide insertion. Both mutations lead to truncation of the ATM protein product. Identification of the pathogenic mutation in each family was performed in a timely fashion, allowing the fetuses to be tested and diagnosed. The parents chose to continue with both pregnancies as both fetuses had a healthy genotype and thus were not at risk of A-T

The influence of rice husk ash addition on the properties of metakaolin-based geopolymers

This paper investigates the replacement of metakaolin (MK) with rice husk ash (RHA) in the production of alkali-activated binders or geopolymers. The influence of the RHA addition on compressive and flexural strength, as well as water absorption and apparent porosity were determined, in terms of the percentage of RHA in the mixture and molar ratios of the mixes. Fourier Transform Infrared (FTIR) spectroscopy and Energy Dispersive spectroscopy (EDS) were carried out to assess the changes in the microstructure of the geopolymer matrices with the RHA addition. Results have shown that RHA may be a supplementary precursor for geopolymers. The composition of the geopolymer matrices containing 0-40% RHA is very similar, which indicates that the additional Si provided by RHA is not incorporated to the geopolymer matrix. In addition, geopolymers with RHA content higher than 40% present a plastic behavior, characterized by extremely low strength and high deformation, which can be attributed to the formation of silica gel in formulations containing variable Si/Al ratio

An investigation of the mechanisms for strength gain or loss of geopolymer mortar after exposure to elevated temperature

When fly ash-based geopolymer mortars were exposed to a temperature of 800 °C, it was found that the strength after the exposure sometimes decreased, but at other times increased. This paper shows that ductility of the mortars has a major correlation to this strength gain/loss behaviour. Specimens prepared with two different fly ashes, with strengths ranging from 5 to 60 MPa, were investigated. Results indicate that the strength losses decrease with increasing ductility, with even strength gains at high levels of ductility. This correlation is attributed to the fact that mortars with high ductility have high capacity to accommodate thermal incompatibilities. It is believed that the two opposing processes occur in mortars: (1) further geopolymerisation and/or sintering at elevated temperatures leading to strength gain; (2) the damage to the mortar because of thermal incompatibility arising from non-uniform temperature distribution. The strength gain or loss occurs depending on the dominant process