Rich States Research Articles

Localization of a Bose-Einstein condensate in a two-leg ladder subject to an artificial magnetic field

We investigate the localization of a Bose-Einstein condensate trapped in a two-leg ladder in the presence of an artificial magnetic field via Bose-Hubbard model and discuss its abundant localized phenomena using variational approximation and direct numerical simulation. A two-leg bosonic ladder provides an ideal platform to study the complex dynamics of Bose-Einstein condensates in an optical lattice subject to an artificial magnetic field. As a main result, the system displays rich interesting localized states including self-trapping, soliton and breather. The coupling of the repulsive atomic interaction, artificial magnetic field, the rung-to-leg coupling ratio of the ladder, and the initial population difference of atoms between the two legs of the ladder results in the transitions between the localized states. The critical conditions for the transitions between the localized states are given analytically and are intuitively demonstrated in the phase diagram. Particularly, when the rung-to-leg coupling radio of the ladder satisfies a critical condition, we have the localized states with no local atomic currents between the two legs, otherwise, we observe the localized states with local atomic currents between the two legs. Finally, the results obtained via variational method are confirmed by the numerical simulations of the full discrete nonlinear Schrödinger equation describing the system.

Epitaxial Growth of Free-Standing Bismuth Film on Graphene Embedded with Nontrivial Properties

Topological insulators (TIs) have become one of the intensely pursed topics during the past few years due to their robust gapless edge states, among which bismuth (Bi) enjoys a good reputation because of its rich quantum states. However, bulk Bi itself is topologically trivial. While thin Bi film has long been theoretically perceived to be a two-dimensional topological insulator, it still remains a challenge to construct free-standing Bi(111) film experimentally. Herein, we investigate the epitaxial growth of bismuth films on graphene with the film facet ranging from (110) to (111) with increasing coverage and demonstrate the topologically nontrivial property embedded in Bi(111) layers by angle-resolved photoemission spectroscopy (ARPES) and density functional theory (DFT) calculations. In contrast to the bulk Bi with semimetallicity, a metallic surface state is revealed in the 7-bilayer Bi(111) with a circle-shape photoemission intensity plot, while the stacking of free-standing bismuth bilayers on graphene is rationalized to be responsible for the nontrivial characteristics of Bi(111) with an odd crossing of the Fermi level. Our report herein proposes an intriguing approach toward fabricating topologically nontrivial bismuth film, as well as advancing the fundamental understanding of Bi(111) bilayers. Importantly, the combination of the nontrivial Bi(111) film and graphene might also shed useful insights into the development of nanotronics and spintronics.

Dual: Deploy stateful virtual network function chains by jointly allocating data-control traffic

Network Function Virtualization (NFV) allows to deploy network functions at low cost and high flexibility. Usually traffic needs to pass through several network functions in a particular order, which is known as network function chaining. Due to capacity limitation, one instance of a particular network function in the chain usually needs to be scaled to multiple instances when the traffic load increases. Recent studies show that network functions maintain rich internal states, which correlate with flows and determine their processing actions. In order to guarantee network functions to behave the same as before the scaling, these states on multiple instances need to be synchronized. As a result, communication requirement for synchronizing these states arises. Our experimental investigations show that such communication traffic for state synchronization is non-negligible. Unfortunately, to our best knowledge, no existing work for network function chain deployment considered such traffic. In this paper, we consider the problem of allocating both flow traffic and synchronization traffic with the goal to minimize the consumption of network interface card’s bandwidth, which is considered as the bottleneck resource of the network. The main challenge is that such two kinds of traffic are correlated and even conflicting. To deal with this challenge, a new graph-based model named Dual (Deploy Stateful Virtual Network Function Chains by Jointly Allocating Data-Control Traffic) is proposed, which characterizes the interaction of data-control traffic in an elegant manner. Based on Dual, the problem mentioned above is formulated through ILP and an approximation algorithm is designed. Extensive simulations show that the proposed approach is effective in terms of reducing server bandwidth usage.

Zinc cobalt sulfide nanoparticles as high performance electrode material for asymmetric supercapacitor

Zinc cobalt sulfide (ZCS) is a promising and high performance electrode material for pseudocapacitors due to its good electrical conductivity, abundant active sites and rich valence states. In this work, zinc cobalt oxide (ZCO) nanoparticles are firstly synthesized via a hydrothermal method assisted by hexadecyltrimethyl ammonium bromide (CTAB), and then transformed into zinc cobalt sulfide nanoparticles (ZCS NPs) using a facile sulfuration process. The average diameter of ZCS NPs is estimated to be about 15 nm, which is beneficial for Faradaic redox reactions in energy storage process due to their numerous active surfaces. The ZCS NPs are then coated onto a nickel foam to form the working electrode of supercapacitors. Because the ZCS electrode has lower series and charge transfer resistance, and also higher ion diffusion rate than that of the ZCO electrode, it achieves a large specific capacitance of 1269.1 F g−1 at 0.5 A g−1 in 2 M KOH electrolyte, which is four times more than that of the ZCO electrode (e.g., 295.8 F g−1 at 0.5 A g−1). In addition, an asymmetric supercapacitor using the ZCS NPs as the positive electrode and activated carbon as the negative electrode is assembled, which delivers a high energy density of 45.4 Wh kg−1 at a power density of 805.0 W kg−1, with an excellent cycling stability (91.6% retention of the initial capacitance over 5000 cycles).

Soil Quality Analysis in Newly Increased Cultivated Land

In order to explore soil physical-chemical properties and water quality in Bailiang town, Heyang county of Shaanxi Province, the soil physical-chemical properties of newly increased cultivated land, the water heavy metal contents of chromium, copper, zinc, arsenic, selenium, cadmium, mercury and lead of Yellow River water and groundwater in the project area were measured. The results showed that the pH value, total salt content and heavy metal content of the Yellow River and groundwater were all in line with the farmland irrigation water quality Standard, which could guarantee irrigation use. The type of soil in the 0∼30 cm was sandy loam, the bulk density of 0∼30 cm soil layer was 1.52 g cm−3, and the saturated hydraulic conductivity was 229.41 cm d−1, which could meet the needs of planting soil quality requirements, but sandy loam soil with large saturated water conductivity was easy to leak water and fertilizer. Meanwhile, the content of exchangeable calcium of 0∼30 cm soil layer was in a very rich state(38.6∼90.1 cmol kg -1), and the content of available potassium (36∼128 mg kg−1)and effective boron(0.56∼0.89 mg kg−1)were moderate, the content of organic matter(1.06∼2.65 g kg−1), total nitrogen(0.18∼0.33 g kg−1), available phosphorus(3.2∼8.4 mg kg−1) and available silicon content(41.0∼68.6 mg kg−1)were in a state of lack. These results indicate that the organic fertilizer, green manure, straw and small amounts of fertilizer could be used to increase the content of organic matter, and other nutrient elements in the cultivated layer. It was recommended to design the loess tillage layer and plow pan layer, which played the role of water retention and fertilizer retention, and was suitable for the growth of aquatic crops.

Refuge and History

Refuge: Transforming a Broken Refugee System. Alexander Betts and Paul Collier. Oxford: Oxford University Press, 2017.

Non-parametric material state field extraction from full field measurements

Data-driven computations propose a completely new paradigm to the computational mechanics research community and to experimentalists. Classically, admissible material states can only be obtained experimentally for homogeneous stress/strain configurations or using a parametric optimization of material laws based on heterogeneous tests. Data-driven algorithms aim at circumventing these limitations. However, data-driven algorithms require a large database of admissible material states, otherwise extrapolation is required and some limitations of the classical constitutive equation based approach remain. In this paper, an inverse data-driven approach based on full field measurements is presented. The main idea is to extract, with no assumption on the constitutive equations, rich (i.e. heterogeneous and multiaxial) material state fields from displacement fields and external load measurements. The capability of the proposed method to extract databases of admissible material states and to evaluate stress fields without parametric constitutive equations is illustrated through three examples dedicated to non-linear elasticity, plasticity and dynamics.

Critical analysis of the case of Kazakhstan’s accession to the World Trade Organization

Kazakhstan’s application to join the World Trade Organization began less than five years after achieving full independence from the Soviet Union, when economy of the country required reforms and progress. The accession process differs on a case-by-case basis depending on the country’s economy and policy. In comparison with General agreement trade and tariffs, the World Trade Organization accession has become more political due to the negotiation issues subject to the domestic politics of the country and geopolitical considerations World Trade Organization Membership is regarded as a fundamental step towards Kazakhstan’s full integration into the international economy. As a hydrocarbon rich state, the government realized that by remaining outside the World Trade Organization, the country would lose economic opportunities to take benefits of global market. Kazakhstan’s involvement in the international trade through the World Trade Organization would commence a new wave of economic growth. Nineteen years later on, the Republic of Kazakhstan has become the full member of the World Trade Organization. In this article the complex and lengthy process of Kazakhstani accession to the World Trade Organization will be explored. Specifically, referring to Kazakhstan’s accession case, the essay will critically analyse some of the main issues of accession in terms of legal perspective view.Keу words: General agreement trade and tariffs, World Trade Organization, accession negotiation, the Marrakesh agreement, multilateral trade agreement.

Novel Sub‐5 nm Layered Niobium Phosphate Nanosheets for High‐Voltage, Cation‐Intercalation Typed Electrochemical Energy Storage in Wearable Pseudocapacitors

AbstractLayered niobium phosphates have been considered very promising energy storage materials because of their high theoretical operating voltage window and the rich oxidation states of niobium. However, their development has been stymied by the phase‐controlled synthesis due to the insolubility of niobium sources except in concentrated hydrofluoric (HF) acid systems. Herein, a new avenue is opened for layered acid niobium phosphate (2NbOPO4·H3PO4·H2O) synthesis in a mild oxalic acid system. Taking advantage of this strategy, in situ growth of sub‐5 nm 2NbOPO4·H3PO4·H2O nanosheet (NPene) arrays on conductive carbon fiber cloth (CFC) substrates is achieved as self‐standing electrodes for solid‐state supercapacitors. Interestingly, the NPene@CFC electrode exhibits a typical cation (H+ or Li+)‐intercalation kinetics with a wide potential window of 0–1.0 V in aqueous electrolytes. Given the wide potential window and highly exposed active surface, the solid‐state asymmetric supercapacitors constructed from such a NPenes@CFC electrode display a high working potential of 2.0 V, energy density of 122.2 W h kg−1 at a power density of 589.7 W kg−1, cycle stability with a capacitance retention of 94.2% after 10 000 cycles, and also outstanding flexible and wearable characteristics.

Facile Surface Engineering of Ag–In–Zn–S Quantum Dot Photocatalysts by Mixed-Ligand Passivation with Improved Charge Carrier Lifetime

I–III–VI quantum dots (QDs) play an important role in visible-light-driven photocatalysis due to their unique optical properties and widely tunable bandgap. However, these materials suffer from rich defect states and high charge carrier recombination. In this work, a facile mixed-ligand method was developed for the manipulation of the optical and photocatalytic properties of multinary Ag–In–Zn–S QDs by introducing 3-mecaptopropionic acid (MPA) into the l-cysteine (Cys) capped QDs system during synthesis. The effect and mechanism of MPA addition was systematically investigated. With the increase of MPA/Cys, the photoluminescence (PL) quantum yield (QY) of the QDs shows an obvious increase at the first stage (MPA/Cys < 5:5), whereas the particle size and UV–Vis absorption remain almost unchanged. Photocatalytic properties of QDs shows similar trend as PL QY with the increase of MPA/Cys, where the hydrogen production rate was doubled with MPA/Cys = 5:5. With ascorbic acid (AA) as the sacrificial reagent, the MPA/Cys capped QDs gave a hydrogen production rate as high as 6.64 mmol g−1 h−1, which is comparable to the state-of-the-art results but without any cocatalyst, indicating the fascination of the simple mixed-ligand method. Further mechanism study indicates that the introduced MPA resulted in dramatic increase of the PL lifetime and the reduction of nonradiative decay, which can be ascribed to the strong passivation effect of MPA. The MPA/Cys capped QDs also show compressed charge recombination as indicated in electrochemical impedance spectra, slightly more negative ζ-potential and reduced hydrated particle radius, which may also contribute to the improved charge transfer for photocatalysis. Our method provides a super simple strategy for the defect manipulation of the Ag–In–Zn–S QDs without the sacrifice of charge transfer, which could be a useful guideline for efficient QDs-based visible-active photocatalysts. Mixed-ligand-modified Ag–In–Zn–S quantum dots with improved hydrogen production were prepared.

Rate limited filament formation in Al-ZnO-Al bipolar ReRAM cells and its impact on early current window closure during cycling

Early current window closure effect has been investigated in ZnO bipolar resistive random access memory cell having reactive contacts (aluminum). From spatial oxygen vacancy mapping through low frequency noise (LFN) measurements, a gradual spatial mismatch between the oxygen vacancy profiles of HRS (high resistance state) and LRS (low resistance state) has been found to develop in the cycled cells. A rate limited release of O2– ions from reactive contacts has been mainly attributed to this phenomenon, which suggests that in addition to the field and temperature as the expected natural impetus for ion migration, chemical reaction at the reactive contacts also impacts the complete dissolution of the conductive filament, which leads to the population of a Zn rich donor state (Zni∙∙/Zni∙) in the HRS of post-cycled cells. Zni∙∙/Zni∙is located relatively far from the ZnO conduction band edge; thus, when an LFN probe was fixed to the oxygen vacancy level (V0∙/V0×), it was found to decrease particularly in the HRS of post-cycled cells, which justifies the increase in the HRS current level over the uncycled ZnO cells. We also examined the complementary behavior of the (V0∙/V0×) profile in the LRS of cycled cells, and finally, we validated, through a different nature of current conduction in pre- and post-cycled cells, the current window narrowing effect due to dissimilarities between the spatial profiles of oxygen vacancies.

Quantum valley Hall effects and spin-valley locking in topological Kane-Mele circuit networks

The Kane-Mele model of time-reversal symmetry, which simultaneously contains spin and valley degrees of freedom, is simulated in a topological circuit network. By varying capacitances and inductances, we are able to demonstrate the quantum valley Hall states, in addition to the quantum spin Hall states, as well as the topological phase transition between them. We also study the rich topological interface states between nontrivial phases with different spin and valley Chern numbers via tuning capacitances and inductances so as to tune the couplings and gauge fields. Finally, we demonstrate the spin-valley locking in the Kane-Mele circuit network. The topological circuit network provides us with a platform to simultaneously control spin and valley degrees of freedom so that a spin splitter and a valley splitter can be realized.

The Geopolitics of Renewables in Kazakhstan and Russia

ABSTRACT This article examines recent renewable energy initiatives in two hydrocarbon rich states of Eurasia: Kazakhstan and Russia. The global nature of challenges surrounding energy and natural resource use demand that sustainability and “energy transition” policies be understood as geopolitical issues, which are increasingly (re)defining political relations among and within states. Existing research and media coverage of international energy politics in Eurasia is overwhelmingly dominated by a focus on oil and gas extraction, especially in Kazakhstan and Russia, due to their central place in traditional hydrocarbon fuels markets. As elsewhere in the world, however, political and economic leaders in both countries have started to adopt the language of promoting environmental sustainability, the “green economy,” and renewable energy infrastructures. Taking a critical geopolitics lens to recent developments, this article considers who is involved in advancing renewable energy in contexts that have traditionally been dependent on traditional energy sources, and what this may portend for the shifting energy landscape of Eurasia.

Non-Hermitian nodal-line semimetals with an anomalous bulk-boundary correspondence

Recently, topological quantum states of non-Hermitian systems, exhibiting rich new exotic states, have attracted great attention in condensed-matter physics. As for the demonstration, most of non-Hermitian topological phenomena previously focused on are in one- and two-dimensional systems. Here, we investigate three-dimensional non-Hermitian nodal-line semimetals in the presence of a particle gain-and-loss perturbation. It is found that this perturbation will split the original nodal ring into two exceptional rings (ERs). The topological nature of the bulk electronic structure is characterized by two different topological invariants, namely, the vorticity and the winding number defined for a one-dimensional loop in momentum space, both of which are shown to take half-integer (integer) values when an odd (even) number of ERs thread through the loop. The conventional bulk-surface correspondence in non-Hermitian nodal-line semimetals is found to break down, where the surface zero-energy flat bands are no longer bounded by projections of bulk ERs. Alternatively, a macroscopic fraction of the bulk eigenstates can be localized near the surface, thus leading to the so-called non-Hermitian skin effect.

Gender Dimensions of Poverty and Food Security: A Case Study of Palamu District of Jharkhand

A wide regional and inter-district disparity exists in the state of Jharkhand. The rankings of its districts on indicators of development reveal that those located in the north-western parts of Jharkhand including Palamu and its north-eastern parts are less developed compared to the ones falling in the central and western parts of the state (Planning-cum-Finance Department, 2017, Jharkhand Economic Survey 2016–17, Ranchi: Government of Jharkhand). Jharkhand is one of the most poverty-stricken states of India with a sharp contrast between rural and urban poverty. Studies often show that the process of liberalisation and economic reforms in India has a mixed impact on a mineral rich state like Jharkhand. The well-known phenomenon of ‘resource curse’ is particularly observed in the case of Jharkhand where manufacturing sector growth is increasing but the state is lagging behind in terms of human development indicators. The political instability and unplanned exploitation of its mineral wealth without benefiting the tribal population clearly indicate that the state suffers from the deficit of governance and development. It is in this context that this article analyses the patterns of poverty and food security among tribals and other social groups in seven villages of Manatu block under Palamu district of Jharkhand from a gender perspective. The article also explores the factors influencing the dynamics of household food security in Palamu district through empirical findings. It examines how the poor rural/tribal communities cope with food insecurity through case studies. Finally, the article critically analyses the implementation of social policies in addressing food security problem of Jharkhand.

Protein Flexibility and Stiffness Enable Efficient Enzymatic Catalysis.

The enormous rate accelerations observed for many enzyme catalysts are due to strong stabilizing interactions between the protein and reaction transition state. The defining property of these catalysts is their specificity for binding the transition state with a much higher affinity than substrate. Experimental results are presented which show that the phosphodianion-binding energy of phosphate monoester substrates is used to drive conversion of their protein catalysts from flexible and entropically rich ground states to stiff and catalytically active Michaelis complexes. These results are generalized to other enzyme-catalyzed reactions. The existence of many enzymes in flexible, entropically rich, and inactive ground states provides a mechanism for utilization of ligand-binding energy to mold these catalysts into stiff and active forms. This reduces the substrate-binding energy expressed at the Michaelis complex, while enabling the full and specific expression of large transition-state binding energies. Evidence is presented that the complexity of enzyme conformational changes increases with increases in the enzymatic rate acceleration. The requirement that a large fraction of the total substrate-binding energy be utilized to drive conformational changes of floppy enzymes is proposed to favor the selection and evolution of protein folds with multiple flexible unstructured loops, such as the TIM-barrel fold. The effect of protein motions on the kinetic parameters for enzymes that undergo ligand-driven conformational changes is considered. The results of computational studies to model the complex ligand-driven conformational change in catalysis by triosephosphate isomerase are presented.

Topological properties of graphene moiré superlattice systems and recent optical studies

When 2D materials with different lattice constants or lattice rotation angles are stacked together, a periodic moiré pattern will appear. Such moiré superlattice introduces a new two dimensional periodic potential, which can greatly change the physical properties of the original systems. Recent experimental studies of moiré superlattices formed by graphene on graphene and graphene on hexagonal boron nitride have revealed very rich strong correlation effects and topological effects due to novel states in superlattice minibands. It has been shown that flat bands in graphene-based moiré superlattice systems can host both topological states and strongly correlated states, which can be controlled by an external electric field. In bilayer graphene, ABC stacked trilayer graphene and twisted bilayer-bilayer graphene, the number of valence and conduction bands near the Dirac point and even the band topology and bandwidth can be changed by varying the stacking angle between graphene layers or the applied bias voltage. Moreover, the competition between kinetic energy and coulomb interaction depends on the bandwidth and the external electric field, and at the so-called magic angle mott insulator states and superconductivity were observed. Twisted bilayer-bilayer graphene has also been predicted to show similar intriguing properties, including electrically tunable strongly correlated insulators, superconductivity and many rich topological states. In graphene-based moiré systems, the combination of topological states and strong correlations is expected to lead to a broad range of novel phenomena that are not achievable in other material systems. Therefore, graphene moiré systems is likely to bring substantial progress to the study of topological materials. In this paper, we review theoretical and experimental investigations of the topological properties of graphene moiré superlattices, including topological domain wall states in bilayer graphene and topological effects in twisted bilayer graphene, ABC trilayer graphene and twisted double bilayer graphene. The origins of topological properties of these systems are discussed as well as topological phenomena observed in various experiments. Finally, recent near-field optical studies of the band structure and novel topological properties of graphene moiré superlattices are discussed.

Topological nodal lines and nodal points in the antiferromagnetic material β-Fe2PO5

Antiferromagnetic β-Fe2PO5 is a new topological semimetal with coexisting rich fermionic states, and with the potential to be applied in topological antiferromagnetic spintronics.

Genetic diversity and distribution of cucumber (Cucumis sativus L.) landraces in India: A study using DIVA-GIS approach

DIVA-GIS, a Geographical Information System is designed to assist the plant genetic resources and biodiversity communities to map the range of distribution of species in which they are interested. The regions where diverse accessions occur could be found by analysing the geographical diversity distribution. In the present study, 50 landraces of cucumber procured from ICAR-NBPGR, New Delhi was evaluated for six yield contributing traits in Augmented Block Design. To study the diversity and distribution of germplasm, geo-referenced points of the collection sites of the genotypes and the agro->morphological data recorded were supplemented to shape files and map geo-referenced points using DIVA-GIS software. A wide range of variability was observed for the quantitative traits studied, as evidenced by the wide range of SDI for days to first harvest (0–0.350 to 1.356–2.000) to fruit length (0–0.450 to 1.840–3.000). Highest yield per plant was observed in IC613477 (2205.29 g), a collection from West Bengal and lowest in IC331627 (94.53 g), from Uttarakhand, with an overall mean of 1189.03 g. High SDI of 1.73 to 3.00 was recorded for accessions collected from Andaman and Nicobar Islands, Tripura and Uttarakhand for yield per plant. Collections from West Bengal, Tripura and Mizoram possessed diversity for days to first harvest, fruit weight, fruit diameter and yield per plant, as indicated by the appearance of red grids in these states for these characters. Hence, future germplasm collections can be targeted from these diversity rich states and adjoining areas.

Does Technology and ICT Capabilities Affect Performance of a Firm: An Exploration of Small &amp; Medium Enterprises?

&lt;p&gt;The study explores the relationship between technology and the competitive performance of SME’s involved in the agro-food processing business in developing countries like India. The study focuses on describing firm level competitiveness through the technology of selected agro-food processing firms of agriculture and horticulture rich state of India i.e. Jammu and Kashmir. The study is exploratory in nature. The study is largely based upon the primary data collected through a well-structured questionnaire. The results indicate a positive relationship between technology competence &amp;amp; total competitive performance and supports the importance of the technology in improving firm level competitiveness. The results of the present study will be helpful to the SME’s in shaping their present and future competitive position as well as improving the competitiveness. The results can also be beneficial to the policymakers in formulating competitiveness related policies and strategic development of the SME’s.&lt;/p&gt;