Asymmetric Structure Research Articles

In Situ Forming Asymmetric Gel Polymer Electrolyte Enhances the Performance of High-Voltage Lithium Metal Batteries.

With the rapid evolution of electric vehicle technology, concerns regarding range anxiety and safety have become increasingly pronounced. Battery systems with high specific energy and enhanced security, featuring ternary cathodes paired with lithium (Li) metal anodes, are poised to emerge as next-generation electrochemical devices. However, the asymmetric configuration of the battery structure, characterized by the robust oxidative behavior of the ternary cathodes juxtaposed with the vigorous reductive activity of the Li metal anodes, imposes elevated requisites for the electrolytes. Herein, a well-designed gel polymer electrolyte with asymmetric structure was successfully prepared based on the Ritter reaction of cyanoethyl poly(vinyl alcohol) (PVA-CN) and cationic ring-opening polymerization of s-Trioxane. With the aid of the sieving effect of separator, the in situ asymmetric gel polymer electrolyte has good compatibility with both the high-voltage cathodes and Li anodes. The amide groups generated by PVA-CN after the Ritter reaction and additional cyano groups can tolerate high voltages up to 5.1 V, matching with ternary cathodes without any challenges. The functional amide and cyano groups participate in the formation of the cathode electrolyte interface and stabilize the cathode structure. Meanwhile, the in situ formed ether-based polyformaldehyde electrolyte is beneficial for promoting uniform Li deposition on anode surfaces. Li-Li symmetric cells demonstrate sustained stability over 2000 h of cycling at a current density of 1 mA cm-2 for 1 mAh cm-2. Furthermore, the capacity retention rate of Li(Ni0.6Mn0.2Co0.2)O2-Li cells with 0.5 C cycling after 300 cycles is 92.2%, demonstrating excellent cycle stability. The electrolyte preparation strategy provides a strategy for the progress of high-performance electrolytes and promotes the rapid development of high-energy-density Li metal batteries.

A robust coverless image-synthesized video steganography based on asymmetric structure

Due to the ability of hiding secret information without modifying image content, coverless image stegonagraphy has gained higher level of security and become a research hot spot. However, in existing methods, the issue of image order disruption during network transmission is overlooked. In this paper, the image-synthesized video carrier is proposed for the first time. The selected images which represent secret information are synthesized to a video in order, thus the image order will not be disrupted during transmission and the effective capacity is greatly increased. Additionally, an asymmetric structure is designed to improve the robustness, in which only the receiver utilizes a robust image retrieval algorithm to restore secret information. Specifically, certain images are randomly selected from a public image database to create multiple coverless image datasets (MCIDs), with each image in a CID mapped to hash sequence. Images are indexed based on secret segments and synthesized into videos. After that, the synthesized videos are sent to the receiver. The receiver decodes the video into frames, identifies the corresponding CID of each frame, retrieves original image, and restores the secret information with the same mapping rule. Experimental results indicate that the proposed method outperforms existing methods in terms of capacity, robustness, and security.

Asymmetric bridge structure based on NiFe bimetallic sites for optimizing nitrate reduction reaction

Asymmetric bridge structure based on NiFe bimetallic sites for optimizing nitrate reduction reaction

Observation of multifunctional robust topological states based on asymmetric C4 photonic crystals

Recent advancements in high-order topological insulators have heralded new opportunities for the innovation and utilization of optical devices. This paper presents a composite asymmetric C4 photonic crystal to achieve multifunctional, robust topological states. Through detailed analysis of the fine changes in the topological bandgap induced by distortion parameters, we facilitate the realization of topological edge states in wavelength division multiplexing applications. We utilize both trivial and nontrivial properties of the topological bandgap to precisely manipulate zero-dimensional angular states, one-dimensional topological boundary states, and two-dimensional body states. Through simulations and experimental results, our advanced asymmetric C4 photonic crystal structure demonstrates superior robustness for the transmission of topological edge states. Our research paves the way for the deployment of more robust topological boundary state transmission systems and advances the application potential of higher-order topological states.

Achieving "Ion Diode" Salt Resistance in Solar Interfacial Evaporation by a Tesla Valve-Like Water Transport Structure.

Salt deposition is a disturbing problem that limits the development of passive solar-driven interfacial evaporation. Inspired by the passive fluid control mechanism of the Tesla valve, a novel solar evaporator is proposed with a Tesla valve-like water transport structure to prevent salt accumulation at the evaporation interface. A unique "ion diode" salt resistance of this evaporator is significantly achieved by optimizing the two asymmetric water transport structures, consisting of one Tesla valve-like side and one wide-leg side, which establish a reverse-suppressing and forward-accelerating water transport channel. In contrast to the limited ion migration of the typical symmetric solar evaporator, such a channel caused by the water/salt ions transport difference between two water supply structures, reinforces the water/salt ions supply on the wide-leg side, thus leading to an apparent unidirectional salt ions migration from the wide-leg side to bulk water through the Tesla valve-like side. Consequently, an evaporation rate of 3.25kg m-2h-1 and a conversion efficiency of 83.27% under 2suns are achieved in 16wt% NaCl solution. The development of the Tesla Valve-like evaporator provides a new perspective for solving salt deposition and realizing scalable applications of solar-driven interfacial evaporation.

Kinematics of Supernova Remnants Using Multiepoch Maximum Likelihood Estimation: Chandra Observation of Cassiopeia A as an Example

Decadal changes in a nearby supernova remnant (SNR) were analyzed using a multiepoch maximum likelihood estimation (MLE) approach. To achieve greater accuracy in capturing the dynamics of SNRs, kinematic features and point-spread function effects were integrated into the MLE framework. Using Cassiopeia A as a representative example, data obtained by the Chandra X-ray Observatory in 2000, 2009, and 2019 were utilized. The proposed multiepoch MLE was qualitatively and quantitatively demonstrated to provide accurate estimates of various motions, including shock waves and faint features, across all regions. To investigate asymmetric structures, such as singular components that deviate from the direction of expansion, the MLE method was extended to combine multiple computational domains and classify kinematic properties using the k-means algorithm. This approach allowed for the mapping of different physical states onto the image, and one classified component was suggested to interact with circumstellar material by comparison with infrared observations from the James Webb Space Telescope. Thus, this technique will help quantify the dynamics of SNRs and discover their unique evolution.

Unionised dockworkers and port ownership structure in an international oligopoly

In an international duopoly with two markets and two ports, this paper investigates the role of dockworkers unionisation in determining the endogenous choice by governments of port ownership structure. While private ports maximise profits, public ports maximise domestic welfare and face a budget constraint, which is binding when unions are sufficiently wage-oriented and shipping costs are not too high. State-owned ports appear as the most likely equilibrium result although all possible configurations may arise in equilibrium, including an asymmetric structure with a state-owned port and a private port. Country size asymmetry, product differentiation and price competition in product markets favour the rise of a joint public ownership structure of ports. This structure also maximises domestic welfare when unions are wage-oriented.

What is the role of environmental stress on public health? Asymmetric evidence on carbon emissions, ecological footprint, and load capacity factor

The aim of this paper is to analyze the effects of carbon emission, ecological footprint, which takes into account the demand side of the environment, and load capacity factor, which takes into account both the supply and demand sides of the environment, on health expenditures with conventional and quantile methods. According to the conventional co-integration approach, there is no relationship between the environment and health expenditures. The other side, the findings obtained from the quantile co-integration method, which can give robust results in the presence of tailed distributions and possible endogeneity problems and consider the asymmetric structure in the data set, show the existence of a long-term relationship between the variables. According to the coefficient estimates, while carbon emission and ecological footprint increase health expenditures, the load capacity factor decreases.

Simulated Directional Wave Spectra of the Wind Sea and Swell under Typhoon Mangkhut

A third-generation wave model is driven by the synthetic wind field combined with the revised Holland wind and surface wind product from the National Centers for Environmental Prediction (NCEP). The temporal and spatial characteristics of the wind waves and swell during the typhoon are studied, as well as the responses of their wave energy spectra to the source terms. The results show that the typhoon waves have a more complicated asymmetric structure than the wind field, and the maximum significant wave height is always located on the right side of the direction along which the typhoon is moving, where wind waves are dominant, due to the extended fetch. The nonlinear wave–wave interaction helps to redistribute the energy of the wind seas at a high frequency to the remotely generated swells at a low frequency, ensuring that the typhoon wave’s energy spectrum remains unimodal. This process occurs in regions without extended fetch, and a similar continued downshift in frequency as the wave–wave interaction occurs for the wind input as well when the waves outrun the typhoon, due to the nonlinear coupling between the wind and growing swells.

An asymmetric STNS-MZI structure and its applications in temperature and Cd2+ monitoring

In this paper, an asymmetric fiber Mach-Zehnder interferometer (MZI) is presented and investigated. The proposed asymmetric MZI structure is mainly constructed with thin core fiber (TCF) and no core fiber (NCF), sandwiched between single mode fibers (SMFs). Note that the TCF is spliced with a slight offset such that higher order cladding modes could be effectively exited. The SMF-TCF-NCF-SMF (STNS) structure is adjusted by a finite-difference beam propagation method simulation to achieve an optimal interference spectrum. Temperature monitoring performance is addressed and the calculated sensing resolution is about 0.28℃ with high precision of ± 0.3 °C. Moreover, as for the Cd2+ monitoring application, the TCF is further etched and then coated with 1-allyl-2-thiourea (ATU) forming cross-linked “-S-Cd-S-” structure. The results show that the resolution of Cd2+ could reach 2.37 × 10−11mol /L, which shows a four order of magnitude improvement compared with our previous work. Therefore, the proposed asymmetric STNS-MZI interference structure has great potential in future applications.

High performance self-powered photodetection and X-ray detection realized by CH3NH3PbI3 single crystal with planar asymmetric Schottky structure

Organic-inorganic hybrid perovskite CH3NH3PbI3 (MAPbI3) single crystals (SCs) have been widely investigated in photodetection and X-ray detection. However, external electric-field-driven ion migration seriously affect the stability of MAPbI3 SCs based optoelectronic devices. Self-powered device can operate without any external power supply, which is suitable for mitigating the ion migration of MAPbI3 SCs. To realize self-powered MAPbI3 SC based photodetector and X-ray detector, an asymmetric Au/CH3NH3PbI3 SC/Au planar Schottky structure is employed in this work. At 0 V, the self-powered photodetector can achieve the responsivity of 11.1 mA/W at the wavelength of 795 nm, and the sensitivity of the self-powered X-ray detector can reach 477.1 μC Gy-1cm-2 with the detection limit of as low as 140.3 nGy s-1. Moreover, the self-powered optoelectronic device exhibits good stability in both photodetection and X-ray detection. Most importantly, high-quality near-infrared bioimaging and X-ray imaging are successfully realized by the above self-powered optoelectronic device.

Boosting Oxygen Evolution Reaction Performance on NiFe-Based Catalysts Through d-Orbital Hybridization

HighlightsThe NiFeLa catalyst with 3d-5d orbital coupling exhibits remarkable oxygen evolution reaction (OER) activity and stability, enabling an anion-exchange membrane water electrolyzers device to achieve a cell voltage of only 1.58 V at 1 A cm−2 as well as long-term stability over 600 h.The introduction of La disrupts the symmetry of Ni-Fe units and optimize d band center, which affects the d-p orbital hybridization between the metal sites on the surface of the catalyst and oxygen-containing intermediates during the OER process.The 5d-introduced NiFeLa has enhanced adsorption strength of oxygen intermediates, which can reduce the rate-determining step energy barrier and prevent catalyst dissolution.

Construction of Yolk@shell Nanocomposite Particles with Controlled Multisized Pore Structures by Monomicelle Confined Assembly.

Hollow nanoparticles with tunable structures and spatial and chemical specificity are considered as promising carriers. However, it remains a formidable challenge to endow hollow nanomaterials with precisely controlled multisized macro/mesoporous structures up to now. This paper demonstrates a "polydopamine (PDA) expansion-shrinkage" strategy combined with a monomicelle interfacial confined assembly method to achieve the highly controllable preparation of a series of yolk@shell PDA@SiO2 composite nanoparticles with structural asymmetry and a tunable multisized pore in the shell. The strategy allows systematic manipulation of the average pore size of large slit pores in the range of 15.4-86.5 nm by adjusting the reaction temperature. Benefiting from advantages such as an asymmetric structure and multilevel porosity, they exhibit excellent performance in the applications of on-demand loading of dual-sized cargoes, dual-propelled nanomotors, and particle size-selected encapsulation and separation. These findings provide inspiration for the construction of asymmetric yolk@shell structures with tunable multisized pores for a wide range of biological and chemical applications.

Unveiling the tunable electronic, optoelectronic, and strain-sensitive gas sensing properties of Janus ZrBrCl: Insights from DFT study

Janus monolayers materials exhibit extraordinary physical and chemical properties because of crystal field changes caused by their asymmetric structures. Here, we investigate the electronic, switching, optoelectronic, and strain-sensitive gas-sensing properties of a Janus ZrBrCl monolayer via density-functional theory and the nonequilibrium Green’s function methods. The electronic properties can be tuned by applying biaxial strain and electric fields. In particular, the band gap can be changed from indirect to direct via applied a + 8 % biaxial tensile strain. It can be transformed from a semiconductor to a metal with an applied −14 % biaxial compressive strain, with a 1011 switching ratio. In addition, a biaxial strain and an electric field can modulate visible light absorption and photocurrents. Under a −12 % biaxial compressive strain, the absorption coefficient increased to 5.26 × 105 cm−1 from the intrinsic 4.08 × 105 cm−1. Across biaxial strains from −4% to + 4 %, the photocurrent density peak displayed red and blue shifts, respectively, with increasing tensile and compressive strains. NH3, NO2, and NO physically adsorb on the Br side of the ZrBrCl monolayer. Maximum gas sensitivity values of a ZrBrCl sensor are 52 % in the zigzag direction and 21 % in the armchair direction. After application of the −14 % biaxial strain, the maximum values respectively increased to 76 % and 179 %. The biaxial compressive strain-sensitive gas-sensing properties are driven by changes in the electrostatic potential difference between the Br and Cl surfaces. These findings indicate promising candidate materials for high-performance switching and optoelectronic devices, and also provide a strategy for improved gas sensors.

Morphological evidence of an explosive eruption event in October 2023 at Sofu Seamount in the Izu-Bonin Arc

Sofu Seamount is one of the poorly studied submarine edifices in the Izu-Bonin Arc. There is no known historical record of volcanic activity, thus its eruptive history and volcanic features are completely unknown. However, on October 9, 2023, at least 14 T-phases originating near Sofu Seamount were observed. An 80 km-long raft of floating pumice was observed off Sofu Seamount on October 20. These spatially and temporally coherent observations indicate that an eruption occurred from a deep seafloor vent somewhere near Sofu Seamount. In order to investigate the origin of this submarine eruption, we collected new bathymetric data in 2024 and compared it with older bathymetric data collected in 2022, 2007 and 1987. The bathymetric comparison revealed evidence for explosive eruptions at Sofu Seamount between 2022 and 2024. During this time, a crater, 1.6 km wide and 400 m deep, was formed at the pre-existing central cone on the western part of Sofu Seamount, whose pre-eruption summit depth was 737 m. The maximum negative depth change was 451 m and a volume of 430 × 106 m3 was removed due to the crater formation. A dome-like structure, 1 km wide and 100 m high was constructed northeast of the crater, part of which collapsed as a result of the crater formation. The volcanic products were transported over 6 km downslope and emplaced on the adjacent seafloor where positive depth changes up to 75 m were observed. Landslides also occurred around the crater. The largest slide on the northern flank formed a slide scar that is 3.8 km long and 1 km wide. Here, the maximum negative depth change was 148 m and 140 × 106 m3 of material was removed. The slide materials were deposited downslope where positive depth changes up to 61 m were observed. Considering the occurrence of the earthquake swarm on October 2–8, 2023 and T-phase swarm on October 9, the timing of the eruption can be constrained within October 2023.An analysis of volcanic and tectonic morphology reveals a distinct tectonic influence on volcanism at Sofu Seamount. Sofu Seamount is located in a back-arc rift zone where the N–S trending Torishima and Sofu Rifts have formed. The new bathymetric data showed that the rifts have an asymmetric structure and can be divided into two segments, which are identified here as inner and outer rifts. The inner rifts are bounded by steeper fault scarps that have experienced more subsidence than the outer rifts. The western part of Sofu Seamount, where the eruption occurred, is located within the inner rifts, and is heavily dissected by rifting-related normal faults, while the eastern part is located outward of the inner rifts and is not dissected by faults. The October earthquake swarm was more concentrated in the area of the inner rifts and some large earthquakes showed normal fault focal mechanisms with a tension axis approximately in E–W direction. Our morphological observations combined with recent seismic events show that the inner rifts are the currently active tectonic structures and young volcanism at Sofu Seamount is controlled by the back-arc rifting of the Izu-Bonin Arc.

Detection and Anti-Detection with Microwave-Infrared Compatible Camouflage Using Asymmetric Composite Metasurface.

Detection and anti-detection with multispectral camouflage are of pivotal importance, while suffer from significant challenges due to the inherent contradiction between detection and anti-detection and conflict microwave and infrared (IR) stealth mechanisms. Here, a strategy is proposed to asymmetrically control transmitted microwave wavefront under radar-IR bi-stealth scheme using composite metasurface. It is engineered composed of infrared stealth layer (IRSL), microwave absorbing layer (MAL), and asymmetric microwave transmissive structure (AMTS) with polarization conversion from top to bottom. Therein, IR emissivity, microwave reflectivity, and transmissivity are simultaneously modulated by elaborately designing the filling ratio of ITO square patches on IRSL, which ensures both efficient microwave transmission and IR camouflage. Furthermore, full-polarized backward microwave stealth is achieved on MAL by transmitting and absorbing microwaves under x- and y- polarization, respectively, while forward wavefront is controlled by precise curvature phase compensation on AMTS according to ray-tracing technology. For verification, a proof-of-concept metadevice is numerically and experimentally characterized. Both results coincide well, demonstrating spiral detective wavefront manipulation under y-polarized forward wave excitation while effective reduction of radar cross section within 8-18GHz and low IR emissivity (<0.3) for backward detection. This strategy provides a new paradigm for integration of detection and anti-detection with multispectral camouflage.

Efficiency maximization of fuel cell electric bus using asymmetric multi-stack fuel cells

Fuel cell electric vehicles (FCEVs) have been widely studied as alternative ecofriendly vehicles based on multi-stack fuel cell (MFC) systems. An MFC system has the advantages of considerable efficiency, reliability, and durability compared with a single-stack fuel cell system. In this study, a novel MFC concept with an asymmetric structure is proposed to maximize the efficiency of a fuel cell electric bus (FCEB). The proposed concept was designed with a cascade electrical architecture composed of differently rated power stacks, and the optimal energy distribution between the stacks was determined to leverage the asymmetric structure. This facilitates the use of high-efficiency areas of the fuel cell stacks throughout most of the output power range. To confirm the performance of the proposed mechanism, dynamic programming, a global optimization technique, was used as the energy management strategy, and the FCEB was tested on Manhattan, Hanoi, and Seoul bus driving cycles. As a result, a significant reduction in the total fuel consumption of the proposed MFC electric bus compared with that of the conventional FCEB was verified.

Modelling asymmetric and nonlinear features in the natural resource wealth-economic complexity nexus: empirical insights from Nigeria

AbstractContrary to previous research, this study makes a unique contribution to the global discussion by incorporating asymmetric structure and nonlinearity into the analysis of how changes in natural resource wealth affect economic complexity. To achieve this objective, the study uses a nonlinear autoregressive distributed lag (ARDL) and a fully modified ordinary least squares estimator, utilizing data from Nigeria spanning the period 1984–2021. Unlike earlier studies, this study establishes robust evidence of nonlinearity and asymmetry in the sensitivity of economic complexity to changes in natural resource rents in the short and long run. The cumulative increases (positive shock components) in natural resource wealth provide strong stimuli and incentives that promote economic complexity in the short run, while the cumulative decreases (negative shock components) deteriorate economic complexity upgrades. Meanwhile, long-run estimates indicate that both positive and negative shock components are catalysts that impede Nigeria’s manufacturing structures’ ability to improve technological innovation and knowledge-based productive capacity for producing sophisticated and globally competitive exports. These findings imply that the resource curse phenomenon holds true regarding economic complexity in Nigeria in the long run. In conclusion, this study finds that Nigeria’s natural resource endowments breed complacency, racketeering, shrewdness, corrupt practices, and opportunistic behaviour, which impair innovative initiatives that spur economic complexity. This study outlines the policy implications and insights from the findings.

Tailoring the selective generation of high-valent cobalt-oxo by asymmetrically coordinated single-atom cobalt-activated peracetic acid for efficient water decontamination

The novel nonradical Fenton-like oxidation based on high-valent cobalt-oxo [CoIVO] species is a promising candidate for selectively removing emerging organic contaminants (EOCs) in complex water; however, efficient and targeted generation of CoIVO is hampered by the high Co-3d orbital occupancy and high bond dissociation energy of deprotonation. Herein, an O doping strategy to construct asymmetric coordination (CoN3O) in Co single-atom catalyst (Co-SAC) is developed to steer peracetic acid (PAA) activation for selectively generating CoIVO. Theoretical calculations suggest that asymmetric coordination of CoN3O could induce significant electron delocalization around Co centers, thus promote adsorption and peroxy O–O bond cleavage of PAA. The asymmetric electronic structure also exerts an additional local electric field, which favors the cleavage of O–H bond via a proton-coupled electron transfer pathway for subsequent CoIVO generation. Consistent with the theoretical prediction, the established CoN3O/PAA system exhibits admirable Fenton-like activity in degrading various EOCs to low-toxicity intermediates through exclusive generation of CoIVO, greatly reducing potential environmental risks. Our work provides a fundamental understanding of the structure–activity–selectivity relationships at an atomic level and provides a design guide to develop advanced CoIVO-involved Fenton-like catalyst for more extensive applications.

Asymmetric electric field structure boosts photocharge spatial separation and transfer to enhance antibiotics removal: In-situ construction and directed induction

The symmetric electric field structure within layered Bi-based photocatalysts hinders the long-distance transport and spatial separation of bulk photocharges. Herein, the BiOI/BiOIO3 heterostructures featuring a strong interfacial electric field were prepared through in-situ hydrothermal reduction, disrupting the symmetry of the internal electric field in pristine BiOIO3. The intrinsic polarization electric field ({0 1 0}) and the interfacial electric field ({0 0 1}) within the BiOI/BiOIO3 heterostructure directionally induced the separation and transport of photocharges along distinct pathways, significantly enhancing the dynamics of photogenerated charges and improving photocatalytic activity. Specifically, with the addition of 15 mL of glycol, the CBI-15 sample with a BiOI/BiOIO3 structure achieved a 75.5 % removal rate of tetracycline and a 99.1 % removal rate of sulfisoxazole, which were 1.50 and 1.23 times higher than those of BiOIO3, respectively. Furthermore, continuous flow degradation experiments using photocatalytic membranes (CBI-PVDF) in real water media demonstrated the promising potential of CBI-15 for antibiotic removal. This work presents a novel approach to the directional induction of photocharges separation and transfer, providing valuable insights for developing highly efficient photocatalysts aimed at antibiotic removal.