Mixed Transition Research Articles

Hydrothermal synthesis of mesoporous NiMnO3 nanostructures for supercapacitor application: Effect of electrolyte

In recent days, energy storage devices like supercapacitors are gaining increasing interest. However, the real challenge of getting high specific capacitance with significant mechanical stability and high energy density at an affordable cost for the supercapacitors based on mixed transition metal oxides continues. Herein, mesoporous NiMnO3 (NMO) nanostructures have been prepared by the hydrothermal method. Electrochemical performance of the NMONickel foam (NF) electrode is investigated by cyclic voltammetry at various scan rates of 5–100 mVs−1, galvanostatic charge-discharge at various current densities of 3–5 mAcm−2, and electrochemical impedance spectroscopy over a frequency range of 100 Hz to 100 kHz in 1 M KOH, 1 M NaOH, and 1 M Na2SO4 electrolytes. The NMONF working electrode displayed a high specific capacitance of 435 Fg−1 at a scan rate of 5 mVs−1 and 100% cyclic stability for 2000 cycles, in 1 M KOH electrolyte. The determined values of specific energy, specific power, and coulombic efficiency for NMO- NF electrodes are 11.13 Whkg−1, 198.52 Wkg−1, and 98.1%, respectively.

Floquet dynamical phase transition and entanglement spectrum

We explore both pure and mixed states Floquet dynamical quantum phase transitions (FDQFTs) in the one-dimensional p-wave superconductor with a time-driven pairing phase. In the Fourier space, the model is recast to the non-interacting quasi-spins subjected to a time-dependent effective magnetic field. We show that FDQFTs occur within a range of driving frequency without resorting to any quenches. Moreover, FDQFTs appear in the region where quasi-spins are in the resonance regime. In the resonance regime, the population completely cycles the population between the spin down and up states. Additionally, we study the conditions for the appearance of FDQFTs using the entanglement spectrum and purity entanglement measure. Our results imply that the entanglement spectrum can truly capture the resonance regime where FDQFTs occur. Particularly, the dynamical topological region results in the degeneracy of the entanglement spectrum. It is shown that the boundary of the driven frequency range, over which the system reveals FDQFTs, signaled by the purity entanglement measure.

Theoretical investigation on Stark-induced transition probabilities of hydrogen-like ions

Based on the nondegenerate perturbation theory, the Stark-induced transitions are studied for hydrogen-like isoelectronic sequences (<i>Z</i> = 1–92). The Stark-induced mixing coefficients and transition probabilities between the 2s<sub>1/2</sub>-1s<sub>1/2</sub> levels of hydrogen-like ions are reported. The trend of Stark-induced transition probabilities varying with atomic number <i><i>Z</i></i> between 2s<sub>1/2</sub>-1s<sub>1/2</sub> levels of hydrogen-like ions and the relativistic effect on the Stark-induced mixing coefficients and transition probabilities are discussed. The scaling relations of the nonrelativistic and relativistic Stark-induced transition probabilities with atomic number <i>Z</i> are obtained. The results show that the Stark-induced transition probabilities of hydrogen-like ions decrease monotonically along the isoelectronic sequence with the increase of atomic number <i>Z</i>. In addition, the relativistic effect reduces the Stark-induced transition probabilities of hydrogen-like ions, for example, by about 55% at <i>Z</i> = 92.

Tax aspects of mining companies in V4 countries

Presently there is no definite agreement of taxes definition. Most of the statistics include to tax incomes all obligatory fee of the public sector, which is not based on principles of equivalency. In this case, taxes can be defined as obligatory fees of the public sector, to which governments do not provide direct equal consideration. Modern tax systems are based on the taxation of incomes, consumption, and property. The trend in the area of EU countries taxation is a transition of the tax burden from incomes and capital to consumption. Mainly conditions of mining organisations are presented in the contribution when tax rates and trends in the area of income tax of mining organisations are described. The goal of the contribution is to describe the tax burden of business subjects (mining and extraction organisations) in Hungary, Slovakia, Poland, and the Czech Republic. In the contribution, we orientate the research to a detailed analysis of tax rates in chosen countries. The contribution consists of results conclusions, found by analysis, as well as by comparison of the tax burden of V4 business subjects. The result of the problem analysis presents suggestions of the tax mix change and transition to the relatively high tax burden of a job, mainly for low-income employees, to the lower tax burden of high taxes, as for example, environmental taxes. The results are useful for the management of mining organisations, which provide a possibility of financial savings. On the international level, the results serve for the comparing of the financial situation of mining organisations in V4 countries, which is suitable for a determination of raw material states policies.

High super capacitive performance of mixed transition and inner transition metal oxide-based hybrid nanostructures

Abstract Nowadays, imminent deficiency of primary energy sources and environmental issues have been raised, so huge exploration of the environment and natural resources can be improved by green and sustainable power sources. Especially, supercapacitors are developing as one of the renewable energy sources attributable to their desirable properties. In this research article, ternary CoO-NiO-Er2O3 (CNEO) were synthesized using co-precipitation method and are characterized by field-emission scanning electron microscope (FESEM), transmission electron microscope (TEM) and electrochemical characterization by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) and galvanostatic charge–discharge (GCD) method. The devices how maximum specific capacitance of 232.39F g-1, making them good candidates for future energy storage.

Di- and tri-component spinel ferrite nanocubes: synthesis and their comparative characterization for theranostic applications.

Spinel ferrite nanocubes (NCs), consisting of pure iron oxide or mixed ferrites, are largely acknowledged for their outstanding performance in magnetic hyperthermia treatment (MHT) or magnetic resonance imaging (MRI) applications while their magnetic particle imaging (MPI) properties, particularly for this peculiar shape different from the conventional spherical nanoparticles (NPs), are relatively less investigated. In this work, we report on a non-hydrolytic synthesis approach to prepare mixed transition metal ferrite NCs. A series of NCs of mixed zinc-cobalt-ferrite were prepared and their magnetic theranostic properties were compared to those of cobalt ferrite or zinc ferrite NCs of similar sizes. For each of the nanomaterials, the synthesis parameters were adjusted to obtain NCs in the size range from 8 up to 15 nm. The chemical and structural nature of the different NCs was correlated to their magnetic properties. In particular, to evaluate magnetic losses, we compared the data obtained from calorimetric measurements to the data measured by dynamic magnetic hysteresis obtained under alternating magnetic field (AMF) excitation. Cobalt-ferrite and zinc-cobalt ferrite NCs showed high specific adsorption rate (SAR) values in aqueous solutions but their heating ability was drastically suppressed once in viscous media even for NCs as small as 12 nm. On the other hand, non-stoichiometric zinc-ferrite NCs showed significant but lower SAR values than the other ferrites, but these zinc-ferrite NCs preserved almost unaltered their heating trend in viscous environments. Also, the presence of zinc in the crystal lattice of zinc–cobalt ferrite NCs showed increased contrast enhancement for MRI with the highest T2 relaxation time and in the MPI signal with the best point spread function and signal-to-noise ratio in comparison to the analogue cobalt-ferrite NC. Among the different compositions investigated, non-stoichiometric zinc-ferrite NCs can be considered the most promising material as a multifunctional theranostic platform for MHT, MPI and MRI regardless of the media viscosity in which they will be applied, while ensuring the best biocompatibility with respect to the cobalt ferrite NCs.

Efficient Electrocatalytic Overall Water Splitting on a Cu-Based High Entropy Alloy: An Electrochemical Study

The development of active, durable, cost-effective, and stable electrocatalysts are of urgent need for various industrial fields including renewable energy systems. State-of-the-art catalysts suffer from poor water splitting activity in alkaline media due to sluggish kinetics, high cost and scarcity on earth to be scaled up. Herein, we present an electrochemical analysis of a nanostructured electrocatalyst based on face center cubic Cu-Ni-Fe-Co-Cr high entropy alloy (HEA) with quasi-spherical morphology. Single-phase, face-center cubic HEA was prepared by a one-step electrochemical deposition technique on a highly porous nickel substrate. Electrochemical studies determine the enhanced electrocatalytic activity of HEA induced by the synergistic effect of mixed transition metals. It is shown that the performance of the HEA electrocatalyst for both oxygen evolution reaction and hydrogen evolution reaction is superior to recently reported electrocatalysts for overall water splitting. Benefiting from its long-term durability, the material can pave a way to develop high-performance electrocatalysts for full electrochemical water splitting.

Calcination Behaviour of Nsuta Rhodochrosite Ore in the Presence and Absence of End-of-Life High Density Polyethylene

This research investigated the calcination behaviour of the Nsuta Rhodochrosite (MnCO3) in the presence and absence of end-of-life high density polyethylene (HDPE) using a custom-made palm kernel shell fired furnace. Samples of pulverised Nsuta rhodochrosite were heated rapidly for 30, 40, 50 and 60 minutes, coupled with temperature measurements to determine the maximum temperature attained in the fireclay crucible. The procedure at 60 min was repeated using three blends of rhodochrosite samples containing different masses of HDPE (30 g, 40 g and 50 g) and heated for an hour. For gas analyses studies during calcination, cylindrical compacts of rhodochrosite ore in a LECOTM crucible were heated rapidly with and without high density polyethylene (HDPE at C/O ratio = 1.0, 1.5, and 2.0) in a horizontal tube furnace for 600 s at 1150 °C under high purity argon gas and the off gas was continuously analysed for CH4, CO and CO2 using an online infrared gas analyser. The content of H2 in the off gas was detected using a GC3 gas chromatographic analyser equipped with a thermal conductivity detector. The Nsuta rhodochrosite ore was found to consist of a mixture of manganese II carbonate (MnCO3), silica (SiO2), mixed transition metal carbonate of the form Ca(Mn, Mg)(CO3)2 and mixed metal silicate of the form Ca0.6Mg1.94Si2O6. Calcination results indicated visible colour changes (from grey to dark brown), along with significant changes in the mass before and after calcination. In the absence and presence of the polymer, measured temperatures in the crucible ranged from 1001 °C to 1366 °C and 1361 °C to 1369 °C, respectively. Analyses by XRF showed marginal increase in the content of Mn in the calcined ore with HDPE addition. Gas analyses indicate that blending the carbonate with HDPE before heating results in significant decrease in the amount of CO2 emitted.
 
 Keywords: Land Tenure Security, Registration, Spatial Data, Attribute Data

Synergistic Interactions of Different Electroactive Components for Superior Lithium Storage Performance

The fusion of different electroactive components of lithium-ion batteries (LIBs) sometimes brings exceptional electrochemical properties. We herein report the reduced graphene-oxide (rGO)-coated Zn2SnO4z@NiO nanofibers (ZSO@NiO@G NFs) formed by the synergistic fusion of three different electroactive components including ZnO, SnO2, and NiO that exhibit exceptional electrochemical properties as negative electrodes for LIBs. The simple synthetic route comprised of electrospinning and calcination processes enables to form porous one-dimensional (1D) structured ZSO, which is the atomic combination between ZnO and SnO2, exhibiting effective strain relaxation during battery operation. Furthermore, the catalytic effect of Ni converted from the surface-functional NiO nanolayer on ZSO significantly contributes to improved reversible capacity. Finally, rGO sheets formed on the surface of ZSO@NiO NFs enable to construct electrically conductive path as well as a stable SEI layer, resulting in excellent electrochemical performances. Especially, exceptional cycle lifespan of more than 1600 cycles with a high capacity (1060 mAh g-1) at a high current density (1000 mA g-1), which is the best result among mixed transition metal oxide (stannates, molybdates, cobaltates, ferrites, and manganates) negative electrodes for LIBs, is demonstrated.

Multiprincipal Component P2-Na0.6(Ti0.2Mn0.2Co0.2Ni0.2Ru0.2)O2 as a High-Rate Cathode for Sodium-Ion Batteries.

Mixing transition metal cations in nearly equiatomic proportions in layered oxide cathode materials is a new strategy for improving the performances of Na-ion batteries. The mixing of cations not only offers entropic stabilization of the crystal structure but also benefits the diffusion of Na ions with tuned diffusion activation energy barriers. In light of this strategy, a high-rate Na0.6(Ti0.2Mn0.2Co0.2Ni0.2Ru0.2)O2 cathode was designed, synthesized, and investigated, combining graph-based deep learning calculations and complementary experimental characterizations. This new cathode material delivers high discharge capacities of 164 mA g–1 at 0.1 C and 68 mAh g–1 at a very high rate of 86 C, demonstrating an outstanding high rate capability. Ex situ and operando synchrotron X-ray diffraction were used to reveal the detailed structural evolution of the cathode upon cycling. Using the climbing-image nudged elastic-band calculation and Ab initio molecular dynamics simulations, we show that the optimal transition metal composition enables a percolating network of low barrier pathways for fast, macroscopic Na diffusion, resulting in the observed high rate performance.

Percolation on interdependent networks with cliques and weak interdependence

Previous researches on cascading failures on interdependent networks with cliques mainly consider “strong” interdependence, that is, once a clique fails, its dependency partner in the other layer will fail completely. However, many interdependent systems in real-world may have self-sustaining abilities, and the failure of one clique may only destroy part of the function of its dependency partner, which can be called “weak” interdependence. In this paper, based on the framework of percolation, a cascading failure model on the interdependent networks with cliques and weak interdependence is investigated analytically and numerically. The results of extensive simulations show that the type of the phase transitions of both layers can be altered from discontinuous phase transitions to continuous phase transitions with the decrease of interdependence strength. In addition, in the process from discontinuous phase transitions to continuous phase transitions, the whole system exhibits a surprising phenomenon of mixed phase transitions: layer with large size of cliques percolates continuously while layer with small size of cliques percolates discontinuously. It indicates that weak interdependence strength and the structure of cliques can enhance the robustness of the interdependent networks. The theoretical and numerical predictions agree well with each other.

Material-versus energy-related impacts: Analysing environmental trade-offs in building retrofit scenarios in the Netherlands

The construction sector is responsible for a substantial share of adverse environmental impacts from materials usage, waste generation, energy use and greenhouse gas emissions. At the same time, the construction sector is a major creator of economic and societal value. Retrofitting existing residential buildings can contribute to the achievement of policy goals in building energy efficiency and reduction of energy use. Effects of retrofit activity pertain to both operational energy impacts and material-based impacts. To select effective retrofit strategies, both types of impact need to be taken into consideration, and trade-off effects examined. This study compares environmental impacts of different retrofit scenarios for three residential building archetypes in the Netherlands. Collectively, these archetypes represent 80% of the current Dutch residential building stock. A total of twenty scenarios are defined and analysed using process-based Life Cycle Assessment. Each scenario represents a unique combination of building archetype, construction period, insulation measures, and installations-based refurbishments. The results of the analysis show that under current Dutch energy mix conditions, energy-related impacts are more significant than material-based impacts. The analysis also shows that retrofit measures targeting replacement of installations must tackle both heating and electricity-generation in order to be effective. Improving insulation contributes to a significant reduction of environmental impacts in all retrofit scenarios, and can be considered a relatively low-cost, “no regret” element of any retrofit strategy. Sensitivity analyses show that the balance between operational energy impacts and materials-related impacts shifts if and when the energy mix transitions to a more sustainable composition. This finding highlights the complex dynamic facing decision-makers, researchers and practitioners: retrofit strategies that appear effective today may become less advantageous as framework conditions shift. Retrofitting leads to shifts in environmental impacts between impact categories. These shifts need to be factored into policy and decision making to avoid the risk of beneficial environmental impacts in terms of residential buildings leading to adverse impacts in other policy domains.

Engineered Electrolyte-Electrocatalyst Nanocomposites for Enhanced CO2 Electroreduction

The development of a viable approach to capture, store, and convert carbon dioxide into fuels and chemicals may offer a means to mitigate climate change while also creating value added commodity chemicals. Critical bottlenecks in existing technologies that have impeded commercialization of CO2 electrosynthesis include catalysts with high overpotentials and limited selectivities. Furthermore, current approaches often employ PEM-based electrolyzers that suffer from low CO2 solubility in acidic aqueous solutions, limiting mass transport and reaction rates, or AEM-based systems which have much higher CO2 solubilites in alkaline electrolytes, but have the added problem of membrane poisoning by bicarbonate and carbonate.We have recently developed an electrochemical reactor that overcomes many of the shortcomings that have limited the above technologies. Our preliminary results suggest that onset potentials for CO2 reduction are more than 200 mV lower than with current densities in excess of 150 mA/cm2 at -1 V vs RHE. The selectivities for CO are in excess of 90% and the electrocatalysts. We have examined several cathode electrocatalysts and some of the most promising include a series of nanostructured mixed and/or doped transition metal and main group metal oxides that also suppress the hydrogen evolution reaction. We will present detailed electrochemical and structural studies and will comment on possible reaction mechanisms as well as the key features of the reactor that enable the enhanced kinetics.

Tuning of D-Band Center of Platinum Nanoparticles By Changing Transition Metal Oxide Support Materials for Enhancement of Oxygen Reduction Reaction (2)

The enhancement of oxygen reduction reaction (ORR) on platinum nanoparticles (Pt NPs) was examined by changing transition metal oxide as a support material for Pt NPs. In order to use transition metal oxide having low electron conductivity as electrocatalyst support materials, thin transition metal oxide supports were formed on cup-stacked carbon nanotubes (CSCNT). In addition, mixed transition metal oxides having various ratios of two transition metal ions were prepared to produce continuous changes in the electron state (d-band center) of Pt NPs that was interacted electrically with the mixed transition metal oxides. The ORR activity measured in an acidic aqueous solution depended on the kinds of the metal oxide supports. The plot of the d-band center of Pt NPs deposited on the metal oxides vs. their ORR activity showed a volcano shape. That is, the volcano plot could be drawn by changing the support materials for the first time and maximum ORR activity could be observed at an optimized level of the d-band center. The metal oxide of TiNbOx (Ti:Nb = 1:6.6) could produce the optimized d-band level and could reach the ORR activity to the maximum activity. It was made clear from X-ray photoelectron spectroscopy (XPS) measurements that the d-band center could be down-shifted moderately by donation of electron from the metal oxide supports to Pt NPs for enhancing the ORR. Figure 1. Schematic illustrations of (A-E) preparation of Pt NPs/metal oxide/CSCNT samples and possible positions of Pt NPs deposited on metal oxides and contacted with metal oxides. Figure 1

Atomic Layer Deposition of a Manganese-Iron Mixed Oxide As a Bifunctional Oxygen Catalyst for Zinc-Air Batteries

Carbon-free energy sources will become a necessary step in order to mitigate the effects of climate change. In order to integrate these renewable energy sources, which are usually intermittent and not on-demand, into the power grid, a significant amount of energy storage will be required. The popularity of lithium-ion batteries as an energy storage option has exploded in recent years; however, a safer and less expensive alternative may be zinc-air batteries.Zinc-air batteries combine zinc, an abundant and safe metal, with oxygen from the air. Using oxygen as a battery component, however, presents issues because of the slow kinetics of both oxygen reduction and oxygen evolution, the necessary steps in battery discharge and charge, respectively [1]. To compensate, catalysts are utilized that improve reaction kinetics for both the charge and discharge reactions. The benchmark in oxygen reaction catalysis is rare and expensive noble metals, such as platinum and ruthenium, which hinders practicality. On the other hand, inexpensive and abundant transition metal oxides have also shown promising catalytic activity towards these oxygen reactions [2]. Unfortunately, transition metal oxide catalysts that improve the reaction kinetics of the oxygen reduction reaction are typically not active towards the oxygen evolution reaction, and vice versa. However, a ternary oxide of two transition metals may result in a bifunctional catalyst, which is active towards both charge and discharge reactions.The aim of this work is to produce a bifunctional, mixed oxide catalyst through atomic layer deposition (ALD). ALD employs self-terminating surface reactions of a metal-containing gaseous precursor and an oxygen co-reactant to produce very conformal and thin oxide films. Highly porous carbon paper, which typically serves as the air electrode in metal-air batteries, acts as the substrate for ALD of these transition metal oxide films. ALD can conformally coat the high surface area substrate with minimal loss in porosity. Furthermore, ALD can penetrate deeper into the pores of the electrode as compared with other deposition techniques. Together this allows ALD to yield high surface area nanostructured catalysts that maximizes the three-phase region between gaseous oxygen, liquid electrolyte, and the solid catalyst, thereby improving battery performance [3].Previously studies have shown manganese oxides to be active towards the oxygen reduction reaction, while iron oxide is a component of many oxygen evolution catalysts [3]–[5]. Therefore, a recipe to deposit iron oxide films using ethylferrocene and an oxygen plasma is combined with an already established manganese oxide deposition procedure, with the ultimate goal of creating a mixed transition metal oxide catalyst. Electrochemical characterization techniques are employed to evaluate the bifunctional activity of synthesized transition metal oxides films. The atomic-level control of ALD means that the mixed oxide can be grown in various different proportions. An optimization process to establish the best ALD sequence is showcased, resulting in a bifunctional efficiency of 55% at 20 mA/cm2 for a 10 nm catalytic film.[1] F. Cheng and J. Chen, “Metal-air batteries: From oxygen reduction electrochemistry to cathode catalysts,” Chem. Soc. Rev., vol. 41, no. 6, pp. 2172–2192, 2012.[2] H. Osgood, S. V. Devaguptapu, H. Xu, J. Cho, and G. Wu, “Transition metal (Fe, Co, Ni, and Mn) oxides for oxygen reduction and evolution bifunctional catalysts in alkaline media,” Nano Today, vol. 11, no. 5, pp. 601–625, 2016.[3] M. P. Clark, M. Xiong, K. Cadien, and D. G. Ivey, “High Performance Oxygen Reduction/Evolution Electrodes for Zinc − Air Batteries Prepared by Atomic Layer Deposition of MnOx,” ACS Appl. Energy Mater., vol. 3, no. 1, pp. 603–313, 2020.[4] M. Xiong, M. P. Clark, M. Labbe, and D. G. Ivey, “A horizontal zinc-air battery with physically decoupled oxygen evolution/reduction reaction electrodes,” J. Power Sources, vol. 393, pp. 108–118, 2018.[5] D. Aasen, M. P. Clark, and D. G. Ivey, “(Co,Fe)3O4 Decorated Nitrogen-Doped Carbon Nanotubes in Nano-Composite Gas Diffusion Layers as Highly Stable Bifunctional Catalysts for Rechargeable Zinc-Air Batteries,” Batter. Supercaps, vol. 3, no. 2, pp. 174–184, 2020.

Erosion Resistance Improvement of Polymer Matrix Composites by Detonation-Sprayed Multilayered Coatings

Compared with their metal counterparts, the insufficient erosion resistance of polymer matrix composites (PMC) is a key issue for application in aero-engines. In this study, multilayered coatings were deposited on carbon fiber reinforced bismaleimide polymer composites using detonation spraying to improve their erosion resistance. The coatings consisted of a polymer–aluminum mixed transition layer, pure aluminum bond layer, and WC-17Co top layer The microstructure and bond strength of the coatings were characterized by using scanning electron/transmission electron microscopy and mechanical testing, respectively. Furthermore, solid particle erosion tests were conducted on coated and uncoated PMC at 25 and 250 °C using an air jet. The tests showed that the coatings 150 µm thick were well bonded to the PMC substrate. Substantial enhancement of the coating adhesion up to 16.5 ± 0.5 MPa was achieved by the optimization of the polymer–aluminum mixed transition layer. Under the same erosion conditions, the volume loss of the coated PMC was less than 1/10 of that of uncoated PMC, indicating the effectiveness of the coating to prevent the PMC from the foreign objects’ impact damage. Finally, the coating erosion mechanisms are discussed.

Optimal Design of Large Signal Performance of AlN/GaN Hetero-Structural IMPATT and MITATT Diodes

Hetero-structure of AlxGa1-xN/GaN exhibits important applications in high frequency and large power devices. In this paper, AlN/GaN is adopted to optimal design the large power impact avalanche transit time (IMPATT) and mixed tunneling avalanche transit time (MITATT) diodes operating at the atmospheric low loss window frequency of 0.85 THz. The static state and large signal characteristics of the devices are numerically simulated. The values of peak electric field strength, break-down voltage, avalanche voltage, the maximum generation rates of avalanche and tunneling, admittance-frequency relation, output power, conversion efficiency, quality factor of the proposed hetero-structural IMPATT and MITATT diodes are calculated, respectively. Via comparing the obtained results of (n)AlN/(p)GaN and (n)GaN/(p)AlN IMPATT diodes to those of the MITATT counterparts, there exists little performance difference between IMPATT and MITATT devices while implies significant difference between the (n)AlN/(p)GaN and (n)GaN/(p)AlN diodes.

Preparation and study of the catalytic application in the synthesis of xanthenedione pharmaceuticals of a hybrid nano-system based on copper, zinc and iron nanoparticles

A novel efficiently mixed transition metal oxides catalytic system with high catalytic activity and heterogeneity constructed of copper and zinc oxide nanoparticles is presented. For preparation of this hybrid catalytic system, carrageenan as a natural polymeric matrix has been chosen to add biocompatibility to the heterogeneous catalyst. Then, the carrageenan textures have been magnetized through the composition with iron oxide nanoparticles. Copper and zinc metallic sites are employed as the main catalytic sites for catalyzing the synthesis of xanthenedione pharmaceutical derivatives from aldehyde and dimedone. Due to the magnetic behavior of the catalyst, the purification process is carried out with high convenience. Herein, a plausible mechanism for the catalytic process is suggested and reusability of the presented catalyst is also investigated. In this report, it has been well-proven that high reaction yields are obtained for xanthenedione derivatives under mild conditions, through applying the presented hybrid catalytic system.

A rational policy decision or political deal? A multiple streams' examination of the Russia-China natural gas pipeline

After more than twenty years of waiting, the first gas pipeline connecting Russia and China—the Power of Siberia—began transporting gas in December 2019. Although much has been discussed concerning disputes over pricing and the route of this pipeline, the relevant events inside each nation, e.g. China's energy mix transition, its gas pricing reform, the reshuffle of Russia's natural gas industry, etc., that helped catalyze the deal have yet to be fleshed out. This paper analyzes the decision-making behind the deal using the multiple streams framework (MSF) which is well suited for the examination of decision-making under circumstances of ambiguity. Our analysis demonstrates the ambiguous policymaking circumstances for the gas deal and reveals how policy disputes over price and routing paralleled and interacted with the changing political landscapes and shifting problem agendas in both nations before they were coupled together by political leaders in 2014. The insights derived here are also helpful in analyzing other cross-border pipeline deals.

Floquet dynamical quantum phase transition in the extended XY model: Nonadiabatic to adiabatic topological transition

We investigate both pure and mixed states Floquet dynamical quantum phase transition (DQPT) in the periodically time-dependent extended XY model. We exactly show that the proposed Floquet Hamiltonian of interacting spins can be expressed as a sum of noninteracting quasi-spins imposed by an effective time dependent magnetic field (Schwinger-Rabi model). The calculated Chern number indicates that there is a topological transition from nonadiabatic to adiabatic regime. In the adiabatic regime, the quasi-spins trace the time dependent effective magnetic field and then oscillate between spin up and down states. While in the nonadiabatic regime, the quasi-spins cannot follow the time dependent effective magnetic field and feel an average magnetic field. We find the range of driving frequency over which the quasi-spins experience adiabatic cyclic processes. Moreover, we obtain the exact expression of the Loschmidt amplitude and generalized Loschmidt amplitude of the proposed Floquet system. The results represent that both pure and mixed states dynamical phase transition occurs when the system evolves adiabatically. In other words, the minimum required driving frequency for the appearance of Floquet DQPT is equal to the threshold frequency needed for transition from nonadiabatic to adiabatic regime.