Field-induced insulating states in a graphene superlattice

We report on high-field magnetotransport (B up to 35 T) on a gated superlattice based on single-layer graphene aligned on top of hexagonal boron nitride. The large-period moir\'e modulation (15 nm) enables us to access the Hofstadter spectrum in the vicinity of and above one flux quantum per superlattice unit cell (Phi/Phi_0 = 1 at B = 22 T). We thereby reveal, in addition to the spin-valley antiferromagnet at nu = 0, two insulating states developing in positive and negative effective magnetic fields from the main nu = 1 and nu = -2 quantum Hall states respectively. We investigate the field dependence of the energy gaps associated with these insulating states, which we quantify from the temperature-activated peak resistance. Referring to a simple model of local Landau quantization of third generation Dirac fermions arising at Phi/Phi_0 = 1, we describe the different microscopic origins of the insulating states and experimentally determine the energy-momentum dispersion of the emergent gapped Dirac quasi-particles

Essential L-Amino Acid-Functionalized Graphene Oxide for Liquid Crystalline Phase Formation

The colloidal 2D materials based on graphene and its modifications are of great interest when it comes to forming LC phases. These LC phases allow controlling the orientational order of colloidal particles, paving the way for the efficient processing of modified graphene with anisotropic properties. Here, we present the peculiarities of AA functionalization of GO, along with the formation of its LC phase and orientational behavior in an external magnetic field. We discuss the influence of pH on the GOLC, ultimately showing its pH-dependent behavior for GO-AA complexes. In addition, we observe different GO morphology changes due to the presence of AA functional groups, namely L-cysteine dimerization on the GO platform. The pH dependency of AA-functionalized LC phase of GO is examined for the first time. We believe that our studies will open new possibilities for applications in bionanotechnologies due to self-assembling properties of LCs and magnificent properties of GO.Comment: 10 pages, 16 figure

ПЕРСПЕКТИВЫ ТАМОЖЕННОГО СОЮЗА С ТОЧКИ ЗРЕНИЯ СОВРЕМЕННЫХ ТЕОРИЙ РЕГИОНАЛЬНОЙ ИНТЕГРАЦИИ

Leading the trend of world development is globalization, which covers all areas of public life, including economic, and national economies poses more challenges, fi rst and foremost – ensuring competitiveness on a global scale, fi nd their own niche in the international division of labor.The development of the global trading system is characterized by two interrelated trends – the expansion of economic openness and the formation of trade unions, to ensure the most favorable terms of trade between the participating countries. The latest trend has led to the relevance of research topic "Prospects of Customs Union from the point of view of modern theories of regional integration."The integration processes taking place in the former Soviet Union in fact since joining the former Soviet republics of the status of independent states. Already in 1991. CIS was created, which brought together 12 post-Soviet countries (all former Soviet republics except the Baltic). Since then, the integration processes in the post-Soviet space are permanent, and therefore, we set a goal – to analyze the prospects of the Customs Union from the point of view of modern theories of regional integration.Notwithstanding that goal has led to the need to address a number of problems, namely:• consideration of the role and place of regional trade (economic) union, the importance of their experience, especially for developing countries and countries with economies in transformation;• justify the importance of the openness of the national economy to generate the preconditions for sustainable economic growth, determining the levels of trade (economic) integration;• analysis of modern views on the nature of regional integration;• consideration of the characteristics of individual regional trade and economic unions, including the Customs Union, and determine their place in the modern system of world trade.The study is based on the use of a systematic approach using historical and logical methods.The result of the study was the conclusion there is a positive relationship between foreign trade and economic growth of member countries of the regional unions, including TC and the EAEC; articulated position relative to the benefi ts and future economic and political prospects of the Customs Union and the Eurasian Economic Union.The theoretical signifi cance of the article is the novelty and the possibility of further study the relationship between economic and political prospects of the vehicle and the EAEC.Ведущей тенденцией современного мирового развития остается глобализация, которая охватывает все сферы общественной жизнедеятельности, в том числе экономическую, и ставит перед национальными экономиками все более сложные задачи, прежде всего – обеспечение конкурентоспособности в мировом масштабе, поиск собственной ниши в мировом разделении труда. Развитие системы мировой торговли характеризуется двумя взаимосвязанными тенденциями - расширением экономиче- ской открытости и образованием торговых союзов, направленных на обеспечение максимально благоприятных условий торговли между странами-участницами. Последняя тенденция обусловила актуальность темы исследования «Перспективы Таможенного союза с точки зрения современных теорий региональной интеграции».Интеграционные процессы происходят на постсоветском пространстве фактически с момента вступления бывшими советскими республиками статуса независимых государств. Уже в 1991г. было создано СНГ, которое объединило 12 стран постсоветского пространства (все бывшие советские республики за исключением прибалтийских). С тех пор интеграционные процессы на постсоветском пространстве приобрели постоянный характер, в связи с чем, нами была поставлена цель – анализ перспектив Таможенного союза с точки зрения современных теорий региональной интеграции.Означенная цель обусловила необходимость решения ряда задач, а именно: рассмотрения роли и места региональных торговых (экономических) союзов, значимости их опыта, прежде всего, для развивающихся стран и стран с трансформационной экономикой; обоснования значимости открытости национальной экономики для формирования предпосылок обеспечения устойчивого экономического роста, определения уровней торговой (экономической) интеграции; анализа современных взглядов на сущность региональной интеграции; рассмотрения особенностей отдельных региональных торгово-экономических союзов, в том числе Таможенного союза, и определения их места в современной системе мировой торговли.Исследование основано на применении системного подхода с использованием исторического и логического методов.Результатом исследовании стали выводы о наличии положительной связи между внешней торговлей и экономическим ростом стран-членов региональных союзов, в том числе ТС и ЕАЭС; сформулированы положения относительно выгод и дальнейших экономических и политических перспектив Таможенного Союза и Евразийского экономического союза.Теоретическая значимость статьи заключается в новизне и возможности дальнейшего исследования взаимосвязи экономических и политических перспектив ТС и ЕАЭС

Options for Scaling up Community-Based Health Insurance for Rural Communities in Armenia

This paper summarises the results of a study which examined international experience with regard to community-based health financing (CBHF) schemes, scaling up CBHF schemes, and the feasibility of scaling up community-based health insurance (CBHI) in Armenia. It was based on a literature review of international experience and qualitative research in Armenia. The recommendations derived from this study have relevance both for Armenia and for the use of CBHI schemes as a tool for promoting pro-poor health system reform in low-resource settings more generally

Solution of the Dirac equation with non-minimal coupling to noncentral three-vector potential

We introduce non-minimal coupling to three-vector potential in the 3+1 dimensional Dirac equation. The potential is noncentral (angular-dependent) such that the Dirac equation separates completely in spherical coordinates. The relativistic energy spectrum and spinor wavefunctions are obtained for the case where the radial component of the vector potential is proportional to 1/r. The non-minimal coupling presented in this work is a generalization of that which was introduced by Moshinsky and Szczepaniak in the Dirac-Oscillator problem.Comment: 8 page

Detecting induced p±ipp \pm ip pairing at the Al-InAs interface with a quantum microwave circuit

Superconductor-semiconductor hybrid devices are at the heart of several proposed approaches to quantum information processing, but their basic properties remain to be understood. We embed a two-dimensional Al-InAs hybrid system in a resonant microwave circuit, probing the breakdown of superconductivity due to an applied magnetic field. We find a strong fingerprint from the two-component nature of the hybrid system, and quantitatively compare with a theory that includes the contribution of intraband $p \pm i p$ pairing in the InAs, as well as the emergence of Bogoliubov-Fermi surfaces due to magnetic field. Separately resolving the Al and InAs contributions allows us to determine the carrier density and mobility in the InAs.Comment: 6+17 pages, 5+13 figure

E-Beam Induced Micropattern Generation and Amorphization of L-Cysteine-Functionalized Graphene Oxide Nano-composites

The evolution of dynamic processes in graphene-family materials are of great interest for both scientific purposes and technical applications. Scanning electron microscopy and transmission electron microscopy outstand among the techniques that allow both observing and controlling such dynamic processes in real time. On the other hand, functionalized graphene oxide emerges as a favorable candidate from graphene-family materials for such an investigation due to its distinctive properties, that encompass a large surface area, robust thermal stability, and noteworthy electrical and mechanical properties after its reduction. Here, we report on studies of surface structure and adsorption dynamics of L-Cysteine on electrochemically exfoliated graphene oxides basal plane. We show that electron beam irradiation prompts an amorphization of functionalized graphene oxide along with the formation of micropatterns of controlled geometry composed of L-Cysteine-Graphene oxide nanostructures. The controlled growth and predetermined arrangement of micropatterns as well as controlled structure disorder induced by e beam amorphization, in its turn potentially offering tailored properties and functionalities paving the way for potential applications in nanotechnology, sensor development, and surface engineering. Our findings demonstrate that graphene oxide can cover L-Cysteine in such a way to provide a control on the positioning of emerging microstructures about 10-20 um in diameter. Besides, Raman and SAED measurement analyses yield above 50% amorphization in a material. The results of our studies demonstrate that such a technique enables the direct creation of micropatterns of L-Cysteine-Graphene oxide eliminating the need for complicated mask patterning procedures

Equity in community health insurance schemes: evidence and lessons from Armenia

Introduction Community health insurance (CHI) schemes are growing in importance in low-income settings, where health systems based on user fees have resulted in significant barriers to care for the poorest members of communities. They increase revenue, access and financial protection, but concerns have been expressed about the equity of such schemes and their ability to reach the poorest. Few programmes routinely evaluate equity impacts, even though this is usually a key objective. This lack of evidence is related to the difficulties in collecting reliable data on utilization and socio-economic status. This paper describes the findings of an evaluation of the equity of Oxfam's CHI schemes in rural Armenia

Phonon-assisted resonant tunneling of electrons in graphene–boron nitride transistors

We observe a series of sharp resonant features in the differential conductance of graphene-hexagonal boron nitride-graphene tunnel transistors over a wide range of bias voltages between 10 and 200 mV. We attribute them to electron tunneling assisted by the emission of phonons of well-defined energy. The bias voltages at which they occur are insensitive to the applied gate voltage and hence independent of the carrier densities in the graphene electrodes, so plasmonic effects can be ruled out. The phonon energies corresponding to the resonances are compared with the lattice dispersion curves of graphene–boron nitride heterostructures and are close to peaks in the single phonon density of states

Tuning the valley and chiral quantum state of Dirac electrons in van der Waals heterostructures

Chirality is a fundamental property of electrons with the relativistic spectrum found in graphene and topological insulators. It plays a crucial role in relativistic phenomena, such as Klein tunneling, but it is difficult to visualize directly. Here we report the direct observation and manipulation of chirality and pseudospin polarization in the tunneling of electrons between two almost perfectly aligned graphene crystals. We use a strong in-plane magnetic field as a tool to resolve the contributions of the chiral electronic states that have a phase difference between the two components of their vector wavefunction. Our experiments not only shed light on chirality, but also demonstrate a technique for preparing graphene’s Dirac electrons in a particular quantum chiral state in a selected valley