Hydrophobic Two-Dimensional Layered Superstructure of a Polyoxometalate Cluster as the Cathode Material for Aqueous Zinc-Ion Batteries.

Aqueous zinc-ion batteries hold promise for sustainable energy storage, yet challenges in finding high-performance cathode materials persist. Polyoxovanadates (POVs) are emerging as potential candidates due to their structural diversity and robust redox activity. Despite their potential, issues like dissolution in electrolytes, structural degradation, and byproduct accumulation persist. This work introduces a POV-based hydrophobic two-dimensional (2D) layered superstructure that addresses these challenges. The hydrophobic nature minimizes POV dissolution, enhancing structural stability and inhibiting phase transitions during cycling. The 2D arrangement ensures a larger surface area and improved electronic conductivity, resulting in faster kinetics and higher specific capacity. The superstructure demonstrates improved cycle life and an increased operating voltage, marking a significant advancement in POV-based cathode materials for aqueous zinc-ion batteries.

Biomimetic Transparent Layered Tough Aerogels for Thermal Superinsulation and Triboelectric Nanogenerator.

Transparent aerogels are ideal candidates for thermally insulating windows, solar thermal receivers, electronics, etc. However, they are usually prepared via energy-consuming supercritical drying and show brittleness and low tensile strength, significantly restricting their practical applications. It remains a great challenge to prepare transparent aerogels with high tensile strength and toughness. Herein, biomimetic transparent tough cellulose nanofiber-based nanocomposite aerogels with a layered nanofibrous structure are achieved by vacuum-assisted self-assembly combined with ambient pressure drying. The nacre-like layered homogeneous nanoporous structures can reduce light scattering and effectively transfer stress and prevent stress concentration under external forces. The aerogels exhibit an attractive combination of excellent transparency and hydrophobicity, high compressive and tensile strengths, high toughness, excellent machinability, thermal superinsulation, and wide working temperature range (-196 to 230 °C). It is demonstrated that they can be used for superinsulating windows of buildings and high-efficient thermal management for electronics and human bodies. In addition, a prototype of transparent flexible aerogel-based triboelectric nanogenerator is developed. This work provides a promising pathway toward transparent tough porous materials for energy saving/harvesting, thermal management, electronics, sensors, etc.

Layered K0.37MnO2·0.25H2O as cathode material for potassium ion batteries.

Lithium supply shortages have prompted the search for alternatives to widespread grid system applications. Potassium-ion batteries (PIBs) have emerged to promising candidates for this purpose. Nonetheless, the large radius of K+(1.38 Å) impedes the march of satisfactory cathode materials. Here, we used solid-phase synthesis to prepare a layered K0.37MnO2·0.25H2O (KMO) cathode, comprising alternately connected MnO6octahedra with a large interlayer spacing (0.71 nm) to accommodate the migration and transport of K+ions. The cathode material achieved initial specific capacities of 102.3 and 88.1 mA h g-1at current densities of 60 mA g-1and 1 A g-1, respectively. The storage mechanism of K+ions in PIBs was demonstratedex situusing x-ray diffraction, x-ray photoelectron spectroscopy, and Raman spectroscopy measurements. Overall, our proposed KMO was confirmed as an auspicious cathode material for potential use in PIBs.

Investigation of Ca Insertion into α-MoO3 Nanoparticles for High Capacity Ca-Ion Cathodes.

Calcium-ion batteries (CIBs) are a promising alternative to lithium-ion batteries (LIBs) due to the low redox potential of calcium metal and high abundance of calcium compounds. Due to its layered structure, α-MoO3 is regarded as a promising cathode host lattice. While studies have reported that α-MoO3 can reversibly intercalate Ca ions, limited electrochemical activity has been noted, and its reaction mechanism remains unclear. Here, we re-examine Ca insertion into α-MoO3 nanoparticles with a goal to improve reaction kinetics and clarify the storage mechanism. The α-MoO3 electrodes demonstrated a specific capacity of 165 mA h g-1 centered near 2.7 V vs Ca2+/Ca, stable long-term cycling, and good rate performance at room temperature. This work demonstrates that, under the correct conditions, layered oxides can be a promising host material for CIBs and renews prospects for CIBs.

Review of Polymer-Based Composites for Electromagnetic Shielding Application.

The rapid advancement of electronic communication technology has greatly aided human productivity and quality of life, but it has also resulted in significant electromagnetic pollution issues. Traditional metals and alloys are often used for electromagnetic interference (EMI) shielding due to their excellent electrical conductivity. However, they have drawbacks such as being heavy, expensive, and having low corrosion resistance, which limits their application in electromagnetic shielding. Therefore, it is crucial to develop novel EMI shielding materials. Polymers, being highly flexible, corrosion-resistant, and possessing high specific strength, are frequently employed in electromagnetic shielding materials. In this review, we firstly introduce the basic theory of electromagnetic shielding. Then, we outline the processing methods and recent developments of polymer-based electromagnetic shielding composites, including uniform-, foam-, layered-, and segregated structures. Lastly, we present the challenges and prospects for the field, aiming to provide direction and inspiration for the study of polymer-based electromagnetic shielding composite materials.

Effect of Layered Aminovanadic Oxalate Phosphate on Flame Retardancy of Epoxy Resin.

To alleviate the fire hazard of epoxy resin (EP), layered ammonium vanadium oxalate-phosphate (AVOPh) with the structural formula of (NH4)2[VO(HPO4)]2(C2O4)·5H2O is synthesized using the hydrothermal method and mixed into an EP matrix to prepare EP/AVOPh composites. The thermogravimetric analysis (TGA) results show that AVOPh exhibits a similar thermal decomposition temperature to EP, which is suitable for flame retardancy for EP. The incorporation of AVOPh nanosheets greatly improves the thermal stability and residual yield of EP/AVOPh composites at high temperatures. The residue of pure EP is 15.3% at 700 °C. In comparison, the residue of EP/AVOPh composites is increased to 23.0% with 8 wt% AVOPh loading. Simultaneously, EP/6 wt% AVOPh composites reach UL-94 V1 rating (t1 + t2 =16 s) and LOI value of 32.8%. The improved flame retardancy of EP/ AVOPh composites is also proven by the cone calorimeter test (CCT). The results of CCT of EP/8 wt% AVOPh composites show that the peak heat release rate (PHHR), total smoke production (TSP), peak of CO production (PCOP), and peak of CO2 production (PCO2P) decrease by 32.7%, 20.4%, 37.1%, and 33.3% compared with those of EP, respectively. This can be attributed to the lamellar barrier, gas phase quenching effect of phosphorus-containing volatiles, the catalytic charring effect of transition metal vanadium, and the synergistic decomposition of oxalic acid structure and charring effect of phosphorus phase, which can insulate heat and inhibit smoke release. Based on the experimental data, AVOPh is expected to serve as a new high-efficiency flame retardant for EP.

An in-plane supercapacitor obtained by facile template method with high performance Mn-Co sulfide-based oxide electrode.

Designing in-plane supercapacitors with high electrode materials selectivity is an indispensable approach to improve electrochemical performance. In this work, a facile template method was employed to fabricate in-plane supercapacitors. This template method could select any electrochemical active materials as electrode materials of in-plane supercapacitors. Hence, a high electrochemical performance material Mn-Co LDO-2S with optimized metal-sulfur bonds proportion and abundant sulfur vacancies was employed as electrode material of symmetrical in-plane supercapacitor (SPS). SPS exhibits excellent electrochemical performance finally, and has considerable area energy density 55.0µWh cm-2with an area power density of 0.7 mW cm-2. As a result, introducing sulfur atoms and sulfur vacancies are efficient approaches to improve electrode materials' electrochemical performance, and template method that proposed in this work is a promising approach to widen selectivity of in-plane supercapacitors' electrode materials.

Robust Template Matching Using Multiple-Layered Absent Color Indexing.

Color is an essential feature in histogram-based matching. This can be extracted as statistical data during the comparison process. Although the applicability of color features in histogram-based techniques has been proven, position information is lacking during the matching process. We present a conceptually simple and effective method called multiple-layered absent color indexing (ABC-ML) for template matching. Apparent and absent color histograms are obtained from the original color histogram, where the absent colors belong to low-frequency or vacant bins. To determine the color range of compared images, we propose a total color space (TCS) that can determine the operating range of the histogram bins. Furthermore, we invert the absent colors to obtain the properties of these colors using threshold hT. Then, we compute the similarity using the intersection. A multiple-layered structure is proposed against the shift issue in histogram-based approaches. Each layer is constructed using the isotonic principle. Thus, absent color indexing and multiple-layered structure are combined to solve the precision problem. Our experiments on real-world images and open data demonstrated that they have produced state-of-the-art results. Moreover, they retained the histogram merits of robustness in cases of deformation and scaling.

Possible Topological Hall Effect above Room Temperature in Layered Cr1.2Te2 Ferromagnet.

Topological Hall effect (THE) has been used as a powerful tool to unlock spin chirality in novel magnetic materials. Recent focus has been widely paid to THE and possible chiral spin textures in two-dimensional (2D) layered magnetic materials. However, the room-temperature THE has been barely reported in 2D materials, which hinders its practical applications in 2D spintronics. In this paper, we report a possible THE signal featuring antisymmetric peaks in a wide temperature window up to 320 K in Cr1.2Te2, a new quasi-2D ferromagnetic material. The temperature, thickness, and magnetic field dependences of the THE lead to potential spin chirality origin that is associated with the spin canting under external magnetic fields. Our work holds promise for practical applications in future chiral spin-based vdW spintronic devices.

Swimmers Heal on the Move Following Catastrophic Damage.

Herein, we describe the development of 2D self-healing small-scale swimmers capable of autonomous propulsion and "on-the-fly" structural recovery in large containers. Incorporation of magnetic Nd2Fe14B microparticles in specialized printed strips results in rapid reorientation and reattachment of the moving tail to its complementary broken static piece to restore the original swimmer structure and propulsion behavior. The swimmers display functional recovery independent of user input. Measurements of the magnetic hysteresis and fields were used to assess the behavior of the healing mechanism in real swimming situations. Damage position and multiple magnetic strip patterns have been examined and their influence upon the recovery efficiency has been compared. Owing to its versatility, fast response, and simplicity the new self-healing strategy represents an important step toward the development of new "on-the-fly" repairing strategies for small-scale swimmers and robots.

Neutron Total Scattering Investigation of the Dissolution Mechanism of Trehalose in Alkali/Urea Aqueous Solution.

The atomic picture of cellulose dissolution in alkali/urea aqueous solution is still not clear. To reveal it, we use trehalose as the model molecule and total scattering as the main tool. Three kinds of alkali solution, i.e., LiOH, NaOH and KOH are compared. The most probable all-atom structures of the solution are thus obtained. The hydration shell of trehalose has a layered structure. The smaller alkali ions can penetrate into the glucose rings around oxygen atoms to form the first hydration layer. The larger urea molecules interact with hydroxide groups to form complexations. Then, the electronegative complexation can form the second hydration layer around alkali ions via electrostatic interaction. Therefore, the solubility of alkali aqueous solution for cellulose decreases with the alkali cation radius, i.e., LiOH > NaOH > KOH. Our findings are helpful for designing better green solvents for cellulose.

Anisotropic 2D SiAs for High-Performance UV-Visible Photodetectors.

Recently, extensive efforts have been directed at finding novel 2D-layered structures with anisotropic crystal structures. Herein, the in-plane anisotropic optical and (photo)electrical properties of 2D SiAs nanosheets synthesized using a solid-state reaction and subsequent mechanical exfoliation are reported. The angle-resolved polarized Raman spectrum shows high in-plane anisotropy of the phonon vibration modes, which are consistent with the theoretical prediction. Field-effect transistor devices fabricated using the SiAs nanosheets demonstrate significant anisotropy in the hole mobility with an anisotropic ratio as high as 5.5. Photodetectors fabricated with single SiAs nanosheet exhibit high sensitivity in the UV-visible region, and the anisotropic ratio of the photocurrent reaches 5.3 at 514.5 nm and 2.3 at 325 nm. This work lays the foundation for future research in anisotropic 2D materials.

A water drop-shaped slingshot in plants: geometry and mechanics in the explosive seed dispersal of Orixa japonica (Rutaceae).

BACKGROUND AND AIMS: In angiosperms, many species disperse their seeds autonomously by rapid movement of the pericarp. The fruits of these species often have long rod- or long plate-shaped pericarps, which are suitable for ejecting seeds during fruit dehiscence by bending or coiling. However, here we show that fruit with a completely different shape can also rely on pericarp movement to disperse seeds explosively, as in Orixa japonica. METHODS: Fruit morphology was observed by hard tissue sectioning, scanning electron microscopy and micro-computed tomography, and the seed dispersal process was analysed using a high-speed camera. Comparisons were made of the geometric characteristics of pericarps before and after fruit dehiscence, and the mechanical process of pericarp movement was simulated with the aid of the finite element model. KEY RESULTS: During fruit dehydration, the water drop-shaped endocarp of O. japonica with sandwich structure produced two-way bending deformation and cracking, and its width increased more than three-fold before opening. Meanwhile the same shaped exocarp with uniform structure could only produce small passive deformation under relatively large external forces. The endocarp forced the exocarp to open by hygroscopic movement before seed launching, and the exocarp provided the acceleration for seed launching through a reaction force. CONCLUSIONS: Two layers of water drop-shaped pericarp in O. japonica form a structure similar to a slingshot, which launches the seed at high speed during fruit dehiscence. The results suggest that plants with explosive seed dispersal appear to have a wide variety of fruit morphology, and through a combination of different external shapes and internal structures, they are able to move rapidly using many sophisticated mechanisms.

High-performance flexible thermoelectric modules based on high crystal quality printed TiS2/hexylamine.

Printed electronics implies the use of low-cost, scalable, printing technologies to fabricate electronic devices and circuits on flexible substrates, such as paper or plastics. The development of this new electronic is currently expanding because of the emergence of the internet-of-everything. Although lot of attention has been paid to functional inks based on organic semiconductors, another class of inks is based on nanoparticles obtained from exfoliated 2D materials, such as graphene and metal sulfides. The ultimate scientific and technological challenge is to find a strategy where the exfoliated nanoparticle flakes in the inks can, after solvent evaporation, form a solid which displays performances equal to the single crystal of the 2D material. In this context, a printed layer, formed from an ink composed of nano-flakes of TiS2 intercalated with hexylamine, which displays thermoelectric properties superior to organic intercalated TiS2 single crystals, is demonstrated for the first time. The choice of the fraction of exfoliated nano-flakes appears to be a key to the forming of a new self-organized layered material by solvent evaporation. The printed layer is an efficient n-type thermoelectric material which complements the p-type printable organic semiconductors The thermoelectric power factor of the printed TiS2/hexylamine thin films reach record values of 1460 µW m-1 K-2 at 430 K, this is considerably higher than the high value of 900 µW m-1 K-2 at 300 K reported for a single crystal. A printed thermoelectric generator based on eight legs of TiS2 confirms the high-power factor values by generating a power density of 16.0 W m-2 at ΔT = 40 K.

Electronic States and Magnetic Response of MnBi2Te4 by Scanning Tunneling Microscopy and Spectroscopy.

Exotic quantum phenomena have been demonstrated in recently discovered intrinsic magnetic topological insulator MnBi2Te4. At its two-dimensional limit, the quantum anomalous Hall effect and axion insulator state were observed in odd and even layers of MnBi2Te4, respectively. Here, we employ low-temperature scanning tunneling microscopy to study the electronic properties of MnBi2Te4. The quasiparticle interference patterns indicate that the electronic structures on the topmost layer of MnBi2Te4 are different from those of the expected out-of-plane A-type antiferromagnetic phase. The topological surface states may be embedded in deeper layers beneath the topmost surface. Such novel electronic structure is presumably related to the modification of crystalline structure during sample cleaving and reorientation of the magnetic moment of Mn atoms near the surface. Mn dopants substituted at the Bi site on the second atomic layer are observed. The electronic structures fluctuate at atomic scale on the surface, which can affect the magnetism of MnBi2Te4.

Microstructure Characteristics of Cathode Materials for Rechargeable Magnesium Batteries.

Rechargeable magnesium batteries (RMBs) that use pure Mg or Mg alloy as anode and materials allowing Mg ions to insert/extract as cathode have many advantages such as high energy density, environmental friendliness, low cost, and safety of handling. RMBs are regarded as a promising candidate for portable power sources and heavy load energy devices. However, there are still some technological issues impeding their commercial application. The most important issue is the absence of applicable cathode materials because of the high charge density, strong polarization effect, and very slow insertion/extraction speed of Mg2+ ions. In recent years, the research reports on the cathode materials of RMBs have increased significantly. Here, an extensive number of research papers are reviewed in terms of the microstructure characteristics of cathode materials for RMBs. The status and issues of cathode materials are analyzed and discussed in detail. The future development directions and perspectives are prospected for providing an understanding of the related research activities on RMBs.

Indium Phosphite-Based Porous Solids Exhibiting Organic Sensing and a Facile Route to Superhydrophobicity.

In searching for practical crystalline porous solids, two unique hybrid materials with featured functions, In-bpy and In-dpe, were prepared without deliberately designed organic linker units or complex post-modification procedures. Composed of oxalate-embedded metal phosphite (MPO) sheets and bipyridyl-type ligands of varied molecular lengths, they show a common pillar-layered topology but are the first well-characterized organo-MPOs to possess genuine porosity, substantiated by CO2 adsorption, and structural stability under harsh conditions. In-bpy exhibits a turn-on fluorescence signal when in contact with p-xylene, making it the first MPO-based sensing material with selectivity and recyclability. Furthermore, In-dpe demonstrates a facile and unprecedented route to the superhydrophobicity of porous solids via a [2+2] photocycloaddition reaction between linker and foreign units. Our findings suggest that MPO may serve as a promising platform for hybrid frameworks to create many more functional porous materials.

Preparation of a concentric layered structure of an electrospun nanofiber column for solid-phase extraction of mass viscous crude extracts.

The packed nanofiber solid-phase extraction of crude extracts of a mass viscous sample is challenging because the interference and recalcitrant particulates in the sample may attach to the nanofiber and block the column, which leads to insufficient sample extraction. A novel concentric layered nanofiber solid-phase extraction (SPE) column using polystyrene-based electrospun nanofiber as the stationary phase has been employed for the pretreatment of mass viscous crude extracts. The layered column was fabricated by using untouched nanofiber with its natural morphology rather than hand-packing of spoiled fiber to the control packing density of the column. In the novel column, the SPE packed bed was divided into a multi-layer structure to provide uniform radial and axial packing and to part the mobile phase stream by the isolated layer with great superiority in aspects such as lower column pressure and faster elution speed. The feasibility and efficiency of the LFSPE column were then evaluated via determination of rhodamine B (RB) from spiked chili samples. Based on the LFSPE column, a linear spiked calibration curve in the range of 0.02-5 mg/kg was obtained. The limit of detection (LOD) and limit of quantification (LOQ) of the method were 0.001 and 0.004 mg/kg, respectively; recoveries at 0.1, 1, and 2 mg/kg (n = 3) were all up to 95 %; and the RSD values of inter-day and intra-day were all below 5 %. This novel LFSPE column overcame heterogeneous packing and exploited the wall effect in subtle ways, and exhibited great superiority by comparison with some existing methods. Graphical Abstract ᅟ.

The Characterization of Surface Acoustic Wave Devices Based on AlN-Metal Structures.

We report in this paper on the study of surface acoustic wave (SAW) resonators based on an AlN/titanium alloy (TC4) structure. The AlN/TC4 structure with different thicknesses of AlN films was simulated, and the acoustic propagating modes were discussed. Based on the simulation results, interdigital transducers with a periodic length of 24 µm were patterned by lift-off photolithography techniques on the AlN films/TC4 structure, while the AlN film thickness was in the range 1.5-3.5 µm. The device performances in terms of quality factor (Q-factor) and electromechanical coupling coefficient (k²) were determined from the measure S11 parameters. The Q-factor and k² were strongly dependent not only on the normalized AlN film thickness but also on the full-width at half-maximum (FWHM) of AlN (002) peak. The dispersion curve of the SAW phase velocity was analyzed, and the experimental results showed a good agreement with simulations. The temperature behaviors of the devices were also presented and discussed. The prepared SAW resonators based on AlN/TC4 structure have potential applications in integrated micromechanical sensing systems.

Observation of sGAG content of human hip joint cartilage in different old age groups based on EPIC micro-CT.

OBJECTIVES: To observe the age-related changes of sulfated glycosaminoglycan (sGAG) content of hip joint cartilage of elderly people based on Equilibrium Partitioning of an Ionic Contrast Agent (EPIC) micro-CT. METHODS: Seventy human hip cartilage-bone samples were collected from hip-fracture patients (ages 51-96) and divided into five groups (10 years in an age group). They were first immersed in 20% concentration of the contrast agent Meglumine Diatrizoate (MD) for 6 h at 37 °C, and then scanned by micro-CT. Following scanning, samples were stained for sGAG with toluidine blue. The X-ray attenuation and sGAG optical density were calculated by image processing. The correlation between X-ray attenuation and sGAG optical density was then analyzed. RESULTS: The X-ray mean attenuation of the cartilage increased by 18.81% from the 50-80 age groups (p < 0.01), but decreased by 7.15% in the 90 age group compared to the 80 age group. The X-ray mean attenuation of the superficial layer and middle layer increased by 31.60 % and 44.68% from the 50-80 age groups, respectively (p < 0.01), but reduced by 4.67% and 6.05% separately in the 90 age group. However, the deep layer showed no significant change with aging. The sGAG optical density showed a linear correlation (r = -0.91, p < 0.01) with the X-ray attenuation. CONCLUSION: The sGAG content of hip joint cartilage varied with aging in elderly people. The changes in superficial layer and middle layer were more evident than deep layer.