Double Transition Research Articles

Research on optimization of multimodal hub-and-spoke transport network under uncertain demand

In the cargo transportation system, the hub-and-spoke transport network can make full use of the scale effect between logistics hubs and reduce logistics costs. Joint transportation of multiple modes of transportation can give full play to the advantages of different modes of transportation, which not only reduces logistics costs but also improves transportation efficiency. Therefore, this paper combines the advantages of multimodal transportation and hub-and-spoke network, and establishes an optimization model of multimodal hub-and-spoke transport network under demand uncertainty. The model takes into account hub capacity constraints and customer satisfaction with respect to transportation time, and to facilitate the model solution, we utilize the fuzzy expected value method and the fuzzy chance constraints based on credibility to clarify the uncertain variables in the model. We use mixed coding to describe the selection of hubs, assignment of nodes, and choice of transportation modes in this study and use the NSGA-II algorithm with local reinforcement to solve the problem. Finally, numerical experiments are designed to verify the validity of the model and algorithm through sensitivity analysis of relevant parameters, determine the reasonable number of hubs and confidence level, and obtain the influence of the change of hub capacity limit and the ratio of single and double hub transit on the research objectives. The results show that: the NSGA-II algorithm with local reinforcement can significantly improve the convergence speed of the algorithm; There is benefit inversion between economic cost and time cost, and the pursuit of economic cost minimization and time cost minimization, respectively, will lead to different choices of the number of hubs; Increasing the ratio of goods transfer between hubs is beneficial for fully utilizing the scale effect between hubs, achieving the goal of reducing economic costs, but at the same time, it will increase time costs.

Deformed Shell Model Applications to Weak Interaction Processes

The deformed shell model (DSM), based on Hartree–Fock intrinsic states with angular momentum projection and band mixing, has been found to be quite successful in describing many spectroscopic properties of nuclei in the A = 60–100 region. More importantly, DSM has been used recently with good success in calculating nuclear structure factors, which are needed for a variety of weak interaction processes. In this article, in addition to giving an overview of this, we discuss the applications of DSM to obtain cross-sections for coherent and incoherent neutrino nucleus scattering on 96,98,100Mo targets and also for obtaining two neutrino double beta decay nuclear transition matrix elements for 100Mo.

Synthesis of Ti1‐xWx Solid Solution MAX Phases and Derived MXenes for Sodium‐Ion Battery Anodes

AbstractA distinguishing feature of MAX phases and their MXene derivatives is their remarkable chemical diversity. This diversity, coupled with the 2D nature of MXenes, positions them as outstanding candidates for a wide range of electrochemical applications. Chemical disorder introduced by a solid solution can improve electrochemical behavior. Up to now, adding considerable amount of tungsten (W) in MAX phase and MXenes solid solutions, which can enhance electrochemical performance, proved challenging. In this study, the synthesis of M site Ti1‐xWx solid solution MAX phases are reported. The 211‐type (Ti1‐xWx)2AlC exhibits a disordered solid solution, whereas the 312‐type (Ti1‐xWx)3AlC2 displays a near‐ordered structure, resembling o‐MAX, with W atoms preferentially occupying the outer planes. Solid‐solution MXenes, Ti2.4W0.6C2Tz, and Ti1.6W0.4CTz, are synthesized via selective etching of high‐purity MAX powder precursors containing 20% W. These MXenes are evaluated as sodium‐ion battery anodes, with Ti1.6W0.4CTz showing exceptional capacity, outperforming existing multilayer MXene chemistries. This work not only demonstrates the successful integration of W in meaningful quantities into a double transition metal solid solution MAX phase, but also paves the way for the development of cost‐effective MXenes containing W. Such advancements significantly widen their application spectrum by fine‐tuning their physical, electronic, mechanical, electrochemical, and catalytic properties.

Correlation between neutrinoless double-β decay and double Gamow-Teller transitions

The neutrinoless double-β (0νββ) decay and the double Gamow-Teller (DGT) transition are investigated with the state-of-the-art Relativistic Configuration-interaction Density functional theory. A strong linear correlation between the nuclear matrix elements (NMEs) of the 0νββ decay and the DGT transition is demonstrated. This linear correlation is found to originate from the similarity of the leading-order term of the 0νββ-decay operator and the DGT-transition one, as revealed by expanding the 0νββ-decay operator in terms of the spherical harmonics. The present results provide a strong support to constrain the 0νββ-decay NMEs through the double charge-exchange reactions.

Low temperature double transition charge transport mechanism in co-doped polyaniline nanocomposites

Low temperature double transition charge transport mechanism in co-doped polyaniline nanocomposites

Structural and Optical Properties of Bi4Six/2Gex/2V2-xO11-x/2 Compounds: Effect of Double Substitution and Phase Transitions

Structural and Optical Properties of Bi4Six/2Gex/2V2-xO11-x/2 Compounds: Effect of Double Substitution and Phase Transitions

Double transitions of Chinese students in the ‘2 + 2’ articulation program under the influence of field coupling and social capital

ABSTRACT In the ‘2 + 2’ articulation program, Chinese students encounter many challenges in academic study and sociocultural life. There is debate regarding their intercultural transition experiences – whether they undergo acculturation, adhering to the home/original culture or adapting to the host/new culture, or remain in between the home/original and host/new culture in a ‘third space’? Existing research refers to numerous institutional and individual factors that influence students’ intercultural transition experiences. However, investigations are lacking regarding the cross-field effect triggered by field coupling and students’ three types of social capital: bonding, bridging, and linking. This study considers eight Chinese student participants who studied at a Sino-foreign cooperative university (SFCU) in China for the first two years and then transitioned to its partner university in the UK for the following two years. The findings showed that they experienced academic acculturation over time (from year one to three) and sociocultural in-betweenness across space (from the SFCU to the British partner university). The tight academic coupling and loose sociocultural coupling between the two educational fields, as well as students’ bonding, bridging, and linking social capital, led to disparate experiences in these double transitions. This study provides suggestions for higher education institutions to strengthen coupling and improve ‘2 + 2’ articulation programs.

Effect of biaxial tensile strain on the thermoelectric properties of monolayer ZrTiCO2

Using ab-initio calculation principle calculations, we investigate the effect of biaxial tensile strain on the stability and electronic properties of the two-dimensional double transition metal MXenes ZrTiCO2. The monolayer ZrTiCO2 has stability and semiconducting properties under different strain conditions. The results of thermoelectric properties under other strain conditions calculated by Boltzmann transport theory and Slack model show that biaxial tensile strain can improve the electrical transport properties of monolayer ZrTiCO2 materials and lead to the decrease of lattice thermal conductivity. The thermoelectric efficiency of a material can be evaluated using the figure of merit ZT. The n-type ZrTiCO2 has a maximum ZT value of 1.49 at 900 K without adding biaxial strain and reaches a ZT value of 2.86 with 2% biaxial strain. The monolayer ZrTiCO2 material has the potential to become a thermoelectric material, and its thermoelectric properties can be improved by biaxial tensile strain.

Two-dimensional MXene supported Ru-Cr(OH)x clusters as an efficient electrocatalyst for hydrogen oxidation reaction

The development of high-performance non-platinum catalysts remains a key challenge for the practical application of anion-exchange membrane fuel cells due to the sluggish kinetics response of the hydrogen oxidation reaction (HOR) in alkaline electrolytes. Herein, we report an outstanding HOR electrocatalyst using a facile one-step method with the two-dimensional double transition metal MXene (Mo2TiC2Tx) as a carrier mixed with metallic ruthenium and Cr(OH)x clusters (Ru-Cr(OH)x/MXene). Specifically, the as-prepared Ru-Cr(OH)x/MXene electrocatalyst exhibits a high apparent kinetic current (jk) of 18.32 mA cm−2 and exchange current (j0) of 1.64 mA cm−2 at an overpotential of 50 mV, respectively, which are 4.74 and 1.46 times as high as those of Pt/C catalyst. Additionally, mechanism experiments indicated that the Ru-Cr(OH)x/MXene electrocatalyst could attenuate the adsorption of hydrogen intermediate (Had) and enhance the adsorption of hydroxyl species (OHad) to promote CO oxidation, which resulted in a significant increase in the HOR activity and enhanced tolerance to CO. Furthermore, combining theoretical studies via density functional theory calculations, our work confirm that the interaction effect of each components of Ru-Cr(OH)x/MXene can optimize the binding energy of the Had and OHad for the HOR. This work develops a new approach to design of HOR electrocatalyst with MXene-based materials.

Double transition of young migrants in Luxembourg: vulnerable, resilient and empowering integration trajectories in the period of youth.

Migrant integration trajectories have become more complex, open, uncertain, and continuously changing, over time. For young migrants, their integration endeavour intersects with their process of transition to adulthood, a double transition that poses additional challenges. Recent theoretical perspectives such as "liquid integration" aim at focusing on the dynamic, processual, and temporal nature of migrant integration. The present article focuses on the dynamic interplay of obstacles and enablers that, over time, interact to construct complex, often non-linear, and open-ended integration and coming of age trajectories of young migrants (aged from 18 to 30 years) coming from outside the European Union (EU) to EU countries. Empirical results from the H2020 MIMY (Empowerment through liquid Integration of Migrant Youth in vulnerable conditions) research project in Luxembourg will be presented. In order to address the goal of the research, qualitative data were gathered by means of N = 38 interviews with young migrants with different migratory paths, characteristics and experiences, and specifically included: young migrants from non-EU Portuguese-speaking countries (N = 16), refugees living in reception centres (N = 15), migrants who since arriving in Luxembourg have become publicly visible (N = 7). Content analysis of the interviews allowed a twofold purpose: (1) capturing the unfolding of intersectional integration obstacles that over time play a decisive role in the building of conditions of vulnerability of the double transition under analysis; (2) capturing the multidimensional resources that interactively build up to give rise to resilient and empowering integration and coming of age experiences. The identification of decisive multidimensional obstacles and resources present in the integration endeavour during the process of coming of age allowed us to capture differentiated routes of vulnerability, on the one hand, and resilience/ empowerment on the other. Key ingredients of both vulnerable and more resilient and empowering integration and coming of age trajectories are identified as well as their relational dynamics, enabling to address key challenges for the resilience and empowerment of young migrants in the process of negotiating their transition to adulthood amidst their integration challenges in the Luxembourgish society.

Tuning the Electronic and Magnetic Properties of Double Transition Metal (MCrCT2, M = Ti, Mo) Janus MXenes for Enhanced Spintronics and Nanoelectronics

Tuning the Electronic and Magnetic Properties of Double Transition Metal (MCrCT₂, M = Ti, Mo) Janus MXenes for Enhanced Spintronics and Nanoelectronics

Multimodule microwave assembly for fast readout and charge-noise characterization of silicon quantum dots

Fast measurements of quantum devices is useful in areas such as quantum sensing, quantum computing, and nanodevice quality analysis. Here, we develop a superconductor-semiconductor multimodule microwave assembly to demonstrate charge-state readout at the state of the art. The assembly consist of a superconducting readout resonator interfaced to a silicon-on-insulator (SOI) chiplet containing quantum dots (QDs) in a high-κ nanowire transistor. The superconducting chiplet contains resonant and coupling elements as well as LC filters that, when interfaced with the silicon chip, result in a resonant frequency f=2.12 GHz, a loaded quality factor Q=850, and a resonator impedance Z=470Ω. Combined with the large gate lever arms of SOI technology, we achieve a minimum integration time for single and double QD transitions of 2.77 and 13.5 ns, respectively. We utilize the assembly to measure charge noise over 9 decades of frequency up to 500 kHz and find a 1/f dependence across the whole frequency spectrum as well as a charge-noise level of 4μeV/Hz at 1 Hz. The modular microwave circuitry presented here can be directly utilized in conjunction with other quantum devices to improve the readout performance as well as enable large bandwidth noise spectroscopy, all without the complexity of superconductor-semiconductor monolithic fabrication. Published by the American Physical Society 2024

Structure and activity relationships of AMn2O4 (A = Mg and Zn) spinels in selective catalytic reduction of NOx with NH3

Mn-based spinel as a catalyst for low-temperature selective catalytic reduction with ammonia (NH3-SCR) has been widely studied. However, most researchers have focused on double transition metal Mn-based spinel and the reports about doping with non-transition metal are not common. Herein, Mg2+ and Zn2+ with similar ionic radii were used to prepare high purity MgMn2O4 and ZnMn2O4 (named MMO and ZMO) to study their structure and activity relationships in NH3-SCR. It was found that the denitration performance of the two showed significant differences at low temperature despite have a very similar crystal structure. A series of characterization methods and first-principles calculations demonstrates that the relatively weak bonding strength and basic adsorption sites of MMO catalyst are the key factors contributing to its superior reactivity at low temperatures. This work provides novel insights and ideas in comprehending the catalytic function of non-transition metal-doped Mn-based spinels in NH3-SCR reactions.

Creating an Innovative Ecosystem for the Development of Unmanned Aviation in Ukraine: Synergy Between Science and Industry

Abstract In this paper we advocate for the establishment of an aviation “innovative ecosystem” in Ukraine, particularly regarding the technology of unmanned aerial vehicles (UAVs). This ambitious strategy necessitates the introduction of new business models, taking advantage of new opportunities for achieving sustainable development goals in the increasingly resource-limited world. Moreover, this initiative faces a notable challenge: navigating the “double transition” of adopting both green and digital transformations across multiple domains. We believe the solution to creating an innovative ecosystem lies in harnessing the intellectual and infrastructural capabilities of top-tier research institutions – which in Ukraine include the National Aviation University (NAU) and the National Technical University “KPI.” By combining the efforts of Ukrainian higher education institutions and actively enhancing international cooperation, in particular with the Łukasiewicz Research Network – Institute of Aviation in Warsaw – we argue – Ukraine can expedite the development of “factories” of ideas and innovations by supporting the training, incubation and growth of startups, encourage the formation of micro and small high-tech enterprises and bringing their products to global and regional markets, improving the mechanisms of interaction of the startup teams with venture capital funds and investment companies.

Investing in European Public Goods While Maintaining Fiscal Discipline at Home

Abstract Putting the high public debt ratios on a downward path after the surge during the pandemic and allocating sufficient resources to deliver on the green and digital transition will be among the priorities confronting the EU institutions emerging from the June 2024 European elections. After a long and painful debate, EU institutions have agreed upon a new fiscal rulebook that aims to incentivise the reallocation of national public spending to the green and digital transition. However, the additional public investment is unlikely to suffice to comply with the goals of net zero that the EU has set for itself. In particular, investments of a transnational nature will remain undersupplied. This article proposes setting up a successor to NextGenerationEU – a new EU fund until 2030 for financing European public goods (EPGs) to address the double transition. Access to the facility would be conditional on adherence to the EU fiscal rules. By tying up the implementation of the new fiscal framework, the debate on the future of NextGenerationEU and the next multiannual EU budget post-2027, the credibility and internal consistency of these various instruments will be greatly enhanced.

Long-term Study of the First Galactic Ultraluminous X-Ray Source Swift J0243.6+6124 Using NICER

We present the results obtained from detailed X-ray timing and spectral studies of X-ray pulsar Swift J0243.6+6124 during its giant and normal X-ray outbursts between 2017 and 2023 observed by the Neutron star Interior Composition Explorer (NICER). We focused on a timing analysis of the normal outbursts. A distinct break is found in the power density spectra of the source. The corresponding break frequency and slopes of the power laws around the break vary with luminosity, indicating a change in the accretion dynamics with the mass accretion rate. Interestingly, we detected quasiperiodic oscillations within a specific luminosity range, providing further insights into the underlying physical processes. We also studied the neutron star spin period evolution and a luminosity variation in the pulse profile during the recent 2023 outburst. The spectral analysis was conducted comprehensively for the giant and all other normal outbursts. We identified a double transition at luminosities of ≈7.5 × 1037 and 2.1 × 1038 erg s−1 in the evolution of continuum parameters like the photon index and cutoff energy with luminosity. This indicates three distinct accretion modes experienced by the source, mainly during the giant X-ray outburst. A soft blackbody component with a temperature of 0.08–0.7 keV is also detected in the spectra. The observed temperature undergoes a discontinuous transition when the pulsar evolves from a sub- to super-Eddington state. Notably, in addition to an evolving 6–7 keV iron line complex, a 1 keV emission line was observed during the super-Eddington state of the source, implying X-ray reflection from the accretion disk or outflow material.

Two‐dimensional Bimetal‐Embedded Expanded Phthalocyanine Monolayers: A Class of Multifunctional Materials with Fascinating Properties

AbstractThe expanded phthalocyanine (EPc) single‐layer sheets with embedded double transition metals (labeled as TM2EPc) are predicted to be a novel class of highly stable 2D materials with a series of fascinating properties by means of systematic first‐principles calculations, molecular dynamics, and Monte Carlo simulations. Excitingly, the ferromagnetic Cr2EPc and antiferromagnetic Mn2– and Fe2–EPc have high magnetic transition temperatures of 223 (TC), 217 (TN), and 325 K (TN), respectively. This makes them promising candidates for low‐dimensional spintronic applications. Unexpectedly, V2EPc is an antiferromagnetic metal with Dirac cone, while ferromagnetic Cr2EPc exhibits Dirac half‐metallicity. The ultra‐high Fermi velocities near Dirac cones render them promising candidates for applications in high‐speed nanoelectronics and spintronics. Several architectured type‐II heterojunctions show promising power conversion efficiency with maximum 25.19% for Ni2EPc/2H‐WSe2, which has great potential in excitonic solar cell applications. Diverse promising properties endow this class of materials multifunction, which paves the way towards the future applications in nanoelectronics, spintronics, optoelectronics, and photovoltaics.

Single-and double transition metal atoms anchored C2N as a high-activity catalyst for CO oxidation: A first-principles study

The oxidation of CO has attracted great interest in recent years due to its important role in enhancing the catalyst durability in fuel cells and solving the growing environmental problems caused by CO emissions. Consequently, the catalytic oxidation of CO at double non-noble metal atoms anchored C2N is investigated using density functional theory (DFT) computations. All the screened Ti@C2N and Ti2@C2N are thermodynamically stable based on their binding energy calculations. The electronic characteristics, the natural bond orbital analyses (NBO), Frontier orbital, statistical thermodynamics, projected densities of states (PDOS) characteristics, non-covalent interactions (NCI), and quantum theory of atoms in molecules (QTAIM) descriptors of these systems have been examined to analyze the interaction process. Our comparative study suggested that the newly predicted double-atom catalyst (Ti2@C2N) is highly active for CO oxidation, which is a useful guideline for further development. The calculated static first-order hyperpolarizability (βo) illustrated that the double-atom catalyst under investigation can be considered a potential candidate for non-linear optical behavior and could be used for NLO applications. CO oxidation on Ti2@C2N along the Eley–Rideal (ER) mechanism with a low energy barrier of 0.16 eV, which is smaller than the maximum energy barrier (0.73 eV) of CO oxidation along the Langmuir–Hinshelwood (LH) mechanism. Consequently, the ER mechanism is more favorable both thermodynamically and dynamically. This work can provide useful insights and guidelines for future theoretical and experimental investigations to promote the design and development of highly effective and low-cost non-precious-metal Ti2@C2N nanocatalysts towards CO oxidation at ambient temperature.

Critical role of zero-valent iron in the efficient activation of H2O2 for 4-CP degradation by bimetallic peroxidase-like.

Peroxidase-like based on double transition metals have higher catalytic activity and are considered to have great potential for application in the field of pollutant degradation. First, in this paper, a novel Fe0-doped three-dimensional porous Fe0@FeMn-NC-like peroxidase was synthesized by a simple one-step thermal reduction method. The doping of manganese was able to reduce part of the iron in Fe-Mn binary oxides to Fe0 at high temperatures. In addition, Fe0@FeMn-NC has excellent peroxidase-like mimetic activity, and thus, it was used for the rapid degradation of p-chlorophenol (4-CP). During the degradation process, Fe0 was able to rapidly replenish the constantly depleted Fe2+ in the reaction system and brought in a large number of additional electrons. The ineffective decomposition of H2O2 due to the use of H2O2 as an electron donor in the reduction reactions from Fe3+ to Fe2+ and from Mn3+ to Mn2+ was avoided. Finally, based on the experimental results of LC-MS and combined with theoretical calculations, the degradation process of 4-CP was rationally analyzed, in which the intermediates were mainly p-chloro-catechol, p-chloro resorcinol, and p-benzoquinone. Fe0@FeMn-NC nano-enzymes have excellent catalytic activity as well as structural stability and perform well in the treatment of simulated wastewater containing a variety of phenolic pollutants as well as real chemical wastewater. It provides some insights and methods for the application of peroxidase-like enzymes in the degradation of organic pollutants.

Direct Exchange in Ultra‐Thin Ferromagnetic Janus MXenes

The development of spintronic devices urgently requires ultra‐thin two‐dimensional (2D) ferromagnetic materials with high Curie temperature (Tc), TC however, there are few natural intrinsic ferromagnetic 2D materials. The successful synthesis of Janus monolayer MoSSe in experiments provides a new approach for designing new 2D materials. By replacing transition metal carbides with two different transition metal atoms, we have designed over 70 Janus MXence materials and determined that 30+ materials have ferromagnetic ground states, of which three have robust ferromagnetism through density functional theory analysis. The ferromagnetic coupling in such materials mainly originates from the direct exchange of d‐orbitals between transition metal atoms in different layers. Further, using K‐nearest neighbours (KNN) machine learning (ML) method, six out of the remaining 360 Janus MXence systems were screened for ferromagnetism, with one system exhibiting strong ferromagnetism. This work provides an alternative and convenient method for developing ultra‐thin 2D magnetic materials for next generation spintronic device applications.