Fine Structure Research Articles

The Early Subcortical Response at the Fundamental Frequency of Speech Is Temporally Separated from Later Cortical Contributions.

Most parts of speech are voiced, exhibiting a degree of periodicity with a fundamental frequency and many higher harmonics. Some neural populations respond to this temporal fine structure, in particular at the fundamental frequency. This frequency-following response to speech consists of both subcortical and cortical contributions and can be measured through EEG as well as through magnetoencephalography (MEG), although both differ in the aspects of neural activity that they capture: EEG is sensitive to both radial and tangential sources as well as to deep sources, whereas MEG is more restrained to the measurement of tangential and superficial neural activity. EEG responses to continuous speech have shown an early subcortical contribution, at a latency of around 9 msec, in agreement with MEG measurements in response to short speech tokens, whereas MEG responses to continuous speech have not yet revealed such an early component. Here, we analyze MEG responses to long segments of continuous speech. We find an early subcortical response at latencies of 4-11 msec, followed by later right-lateralized cortical activities at delays of 20-58 msec as well as potential subcortical activities. Our results show that the early subcortical component of the FFR to continuous speech can be measured from MEG in populations of participants and that its latency agrees with that measured with EEG. They furthermore show that the early subcortical component is temporally well separated from later cortical contributions, enabling an independent assessment of both components toward further aspects of speech processing.

Spectral theory of the invariant Laplacian on the disk and the sphere – a complex analysis approach

Abstract The central theme of this paper is the holomorphic spectral theory of the canonical Laplace operator of the complement of the “complexified unit circle” $\{(z,w) \in \widehat {{\mathbb C}}^2 \colon z \cdot w = 1\}$ . We start by singling out a distinguished set of holomorphic eigenfunctions on the bidisk in terms of hypergeometric ${}_2F_1$ functions and prove that they provide a spectral decomposition of every holomorphic eigenfunction on the bidisk. As a second step, we identify the maximal domains of definition of these eigenfunctions and show that these maximal domains naturally determine the fine structure of the eigenspaces. Our main result gives an intrinsic classification of all closed Möbius invariant subspaces of eigenspaces of the canonical Laplacian of $\Omega $ . Generalizing foundational prior work of Helgason and Rudin, this provides a unifying complex analytic framework for the real-analytic eigenvalue theories of both the hyperbolic and spherical Laplace operators on the open unit disk resp. the Riemann sphere and, in particular, shows how they are interrelated with one another.

Quantification in high-energy resolution Auger electron spectroscopy; Proposal of a reference target convolution technique for direct spectra

Currently, high-energy resolution Auger electron spectroscopy (AES) is utilized for chemical-state qualitative analysis, such as x-ray photoelectron spectroscopy. It is highly desirable to perform quantitative analysis using the high-energy resolution direct spectra used for qualitative analysis. However, AES analysis parameters, such as relative sensitivity factors (RSFs), derived from conventional-energy resolution differentiated spectra cannot be adopted for high-energy resolution direct spectra. Furthermore, for quantification by high-energy resolution direct spectra, there is no established method for determining peak intensity, and no database of RSFs is available in surface analysis communities. Therefore, we tasked ourselves with investigating the use of the analysis parameters obtained from conventional-energy resolution-differentiated spectra obtained with a cylindrical mirror analyzer (CMA)-type AES instrument for high-energy resolution direct spectra measured with a spherical capacitor analyzer (SCA)-type AES instrument. The convolution technique proposed here is achieved by using a conventional-energy resolution spectral dataset obtained with CMA-AES as a target. By applying the convolution with the window function of the convoluted function of the Gaussian function and rectangular function, high-energy resolution direct spectra containing the inherent nature of fine structures are converted to the similar shapes of conventional-energy resolution direct spectra after the Shirley type background subtraction [Watanabe et al., J. Vac. Sci. Technol. A 41, 043209 (2023)]. Results revealed that for all spectra of conventional-energy resolution spectra taken with CMA-AES, as well as high-energy resolution spectra taken with SCA-AES with various energy resolutions, the ratios of the background-subtracted direct peak areas and the differentiated peak-to-peak intensities were well-aligned along the identical parabolic curve as a function of the kinetic energy (KE). Experimental results also revealed that the generalized conversion function f(KE;ΔE)=IareacmaIareaconv.sca(KE;ΔE), which is the ratio of the conventional-energy resolution spectral area (Iareacma) and the convoluted high-energy resolution spectral area (Iareaconv.sca), which can transform differentiated intensities of convoluted high-energy resolution spectra, such that they are similar to those of conventional-energy resolution spectra obtained using the CMA-AES instrument, being a function of KE and the energy resolution ΔE. By applying the conversion function, the historically accumulated AES analysis parameters for conventional-energy resolution differentiated spectra can be adopted to differentiated high-energy resolution spectra. Finally, the results revealed the sufficiency of the conversion function obtained by the actual measurements of the four reference specimens for the practical quantification of high-energy resolution AES direct spectra.

PROCEDURE FOR DETERMINING THE NATURE OF CALCIUM CARBONATE FORMATION ON OILFIELD EQUIPMENT

In the article, the authors propose to use the method of X-ray diffraction analysis (XRD) to establish the nature of the formation of oilfield deposits using of calcium carbonate as an example. It was shown for the first time that comparative diffraction patterns of natural and technogenic carbonate mineral deposits of oilfield equipment differ significantly in the physical broadening of diffraction reflections. In addition, it has been established that the diffraction reflections of technogenic calcite are characterized by shifts to the region of large scattering angles. These facts are taken as the basis for establishing the nature of the formation of carbonate deposits using X-ray diffraction analysis. It has been shown that natural (core) carbonate minerals are characterized by narrow reflections with good resolution of doublet lines, while in minerals formed under borehole conditions, the diffraction maxima are much broader, and low-intensity reflections are not resolved. Precision analysis of diffraction patterns showed that the reasons for such atypical broadenings and shifts of reflections in technogenic mineral deposits are the relatively small sizes of grains — crystallites and high microdistortions of the crystal lattice compared to their natural analogues. It is shown that in order to establish the nature of carbonate deposits of oilfield equipment, it is necessary to measure diffraction patterns of natural and technogenic minerals under the same shooting conditions. Subsequently, the obtained diffraction patterns are analyzed and X-ray diffraction data on the microstructure of the studied minerals are determined. It has been established that in technogenic calcite the crystallite sizes in all arbitrarily selected directions (hkl) are more than 1.6 times smaller than in its natural analogue. The X-ray diffraction method has shown that the average value of microdistortion of the crystal lattice of technogenic calcite is 1.7 times greater than that of its natural analogue. As a result of comparing X-ray diffraction data on the fine structure of mineral deposits of oilfield equipment with those obtained from core material, the nature of the formation of the analyzed minerals is established. To confirm the XRD results, visual studies using scanning electron microscopy (SEM) were also carried out.

Investigating the evolution of the fine structure in cassava starch during growth and its correlation with gelatinization performance

The evolution of the starch fine structure during growth and its impact on the gelatinization behavior of cassava starch (CS) was investigated by isolating starch from South China 6068 (SC6068) cassava harvested from the 4th to 9th growth period. During growth, the short-range ordered structure, crystallinity as well as particle size distribution of starch were increased. Meanwhile, the starch molecular size and amylopectin (AP) proportion increased, while the proportion of amylose (AM) exhibited a decreasing tendency. The chains of short-AM (X ~ 100–1000) were mainly significantly reduced, whereas the short and medium-AP chains (X ~ 6–24) had the most increment in AP. The solubility, thermal stability, shear resistance, and retrogradation resistance of starch were enhanced after gelatinized under the influence of the results mentioned above. This study presented a deeper insight into the variation of starch fine structure during growth and its influence on gelatinization behavior, which would provide a theoretical basis for starch industrial applications.

Experimental studies on fillet weldment joints by artisans in Ghana’s Western Region

Constant progress, demand in the manufacturing of mechanisms parts, and the ability to join parts together is another critical aspect of manufacturing for assemblers. Joining methods plays a significant role and welding must be constantly improved, experimented with, and upgraded due to its increasing use in all aspects of manufacturing. The quality of a weld joint is highly dependent on the process parameter. Welds are examined to ensure that they meet specifications through various experimental processes ranging from computational networks, evolutionary algorithms, non-destructive testing (NDT) and destructive testing (DE) to ascertain the quality of joints. The main objective of the study was to ascertain the quality of welded joints through non-destructive evaluation (NDE). To achieve this goal, an experimental method of four (4) NDE methods were employed to evaluate the quality of weldment joints on a mild steel material joined using manual metal arc welding (MMAW) process in selected fabrication shops in Takoradi-Kokompe, Ghana. Steel specimens were prepared and taken to the artisans to be created into corner joints using the fillet method. The specimens were tested using non-destructive testing techniques. The results on the welded joints were evaluated using the AWS D1.1 code of acceptance for structural steels. The results revealed that all welded joints from fabricators failed to meet the AWS D1.1:2000 acceptance criteria and, thus, had to be rejected. The results implies that through the artisans have worked for many years in the welding trade, their lack of competence and skills in the selection of right input welding parameters contributed to the results. The results implies that, the finished artefacts may look fine but internal structures may contribute to future failure of the fabricated artefacts.

Demonstration of Sensitivity of the Total-Electron-Yield Extended X-ray Absorption Fine Structure Method on Plastic Deformation of the Surface Layer

X-ray Absorption Fine Structure Spectroscopy (XAFS) has proven instrumental for the study of atomic-scale structures across diverse materials. This study conducts a meticulous comparative analysis between total electron yield (TEY) and absorption coefficients at the K absorption edge of polycrystalline Fe and Zr60Cu20Fe20 alloy. Our findings not only highlight differences between TEY and transmission XAFS measurements but also demonstrate the capabilities and limitations inherent in these measurement modes within the context of XAFS. This article provides an experimental exploration of widely used X-ray absorption spectroscopy methods, shedding light on the nuances of TEY and transmission XAFS. Through presenting experimental results, we aim to offer insights crucial to the material science community, guiding experimentalists in optimizing measurements while raising awareness about potential misinterpretations.

STGIC: A graph and image convolution-based method for spatial transcriptomic clustering.

Spatial transcriptomic (ST) clustering employs spatial and transcription information to group spots spatially coherent and transcriptionally similar together into the same spatial domain. Graph convolution network (GCN) and graph attention network (GAT), fed with spatial coordinates derived adjacency and transcription profile derived feature matrix are often used to solve the problem. Our proposed method STGIC (spatial transcriptomic clustering with graph and image convolution) is designed for techniques with regular lattices on chips. It utilizes an adaptive graph convolution (AGC) to get high quality pseudo-labels and then resorts to dilated convolution framework (DCF) for virtual image converted from gene expression information and spatial coordinates of spots. The dilation rates and kernel sizes are set appropriately and updating of weight values in the kernels is made to be subject to the spatial distance from the position of corresponding elements to kernel centers so that feature extraction of each spot is better guided by spatial distance to neighbor spots. Self-supervision realized by Kullback-Leibler (KL) divergence, spatial continuity loss and cross entropy calculated among spots with high confidence pseudo-labels make up the training objective of DCF. STGIC attains state-of-the-art (SOTA) clustering performance on the benchmark dataset of 10x Visium human dorsolateral prefrontal cortex (DLPFC). Besides, it's capable of depicting fine structures of other tissues from other species as well as guiding the identification of marker genes. Also, STGIC is expandable to Stereo-seq data with high spatial resolution.

First report of Pyricularia oryzae the cause of blast disease in upland rice, in Lombok, West Nusa Tenggara

Rice (Oryza sativa L.) is a maincrop cultivated by farmers in Indonesia. The demand for rice has increased, but rice production has decreased due to attacks by plant pests, including pathogen blast disease. This research aims to (i) determine the symptoms of blast disease in upland rice in Lombok, (ii) determine the incidence of blast disease in upland rice in Lombok, (iii) and identify the pathogen that causes blast disease in upland rice in Lombok. The research was conducted in Lombok, West Nusa Tenggara. A sampling of rice crop tissue infected by blast disease was taken from 50 dryland locations in Lombok West Nusa Tenggara. From each point, three samples of rice crops with blast symptoms were taken to obtain 150 samples. Samples are then isolated and identified at the macroscopic, microscopic, and molecular levels. The study results showed that the macroscopic characteristics of rice leaves were rhombus-shaped and brown, and the pathogen produced white mycelium with a fine structure. In contrast, microscopic characteristics showed that the shape of the hyphae was septate, the structure of conidiophore with autophagic cell death, long pyriform microconidia, and long pyriform macroconidia. Based on 18S rRNA gene analysis, the Blast Lombok isolate had a DNA fragment of ±550bp. Based on these results, it can be concluded that the cause of blast disease in upland rice in Lombok, West Nusa Tenggara, is P. oryzae.

Nanoindentation Hardness and Modulus of Al2O3–SiO2–CaO and MnO–SiO2–FeO Inclusions in Iron

AbstractOxide inclusions appear in steel as a subproduct of steelmaking. These are generally detrimental to alloy properties; however, variations exist in the extent to which different inclusions are harmful because their properties vary as a function of their chemical composition. We use nanoindentation to measure the local elastic modulus and hardness of individual oxide particles, produced by precipitation within liquid iron, that belong to the systems Al2O3–SiO2–CaO and MnO–SiO2–FeO. Measured inclusion hardness values are typically in the range of 8 to 13 GPa and can reach 26 GPa for alumina-rich inclusions. Calcium aluminates rich in alumina are significantly stiffer than iron, with elastic moduli that can reach 350 GPa. On the contrary, calcium aluminates that are expected as a result of successful calcium treatment (i.e., with less than about 80 wt pct Al2O3 content) have elastic moduli below that of iron. This is also the case for the wide range of calcium aluminosilicates and of manganese silicates studied here. In addition, silicates containing about 70 to 80 wt pct MnO are observed to have a fine multiphase structure and an elastic modulus of ≈ 180 GPa. Those inclusions thus emerge as possible candidates if one aims to minimise, in loaded steel, stress concentrations associated with matrix-inclusion elastic mismatch.

Size dependence of luminescence decay process in CsPbBr3 nanocrystals

Lead halide perovskite nanocrystals (NCs) have superior luminescence properties compared to classical semiconductor NCs and they are considered promising materials for next-generation emitters. In this work, we measured the size and temperature dependence of the luminescence decay curve in CsPbBr3 NCs. To reproduce the experimental results, a simple model including one and two-phonon transitions between the exciton fine structures is introduced. It is found that the temperature dependence of the decay rates in small NCs is better reproduced by the two-phonon model rather than by the one-phonon model. However, the one-phonon process becomes more important for large NCs as the bright-dark splitting decreases.

Local laser heating effects in diamond probed by photoluminescence of SiV− centers at low temperatures

The accurate measurement of thermal conductivity of diamond below 10 K has always been a challenge, mainly due to significant error in temperature sensing using the thermocouple method. Diamond is generally considered to have high thermal conductivity, so little attention has been paid to the laser heating effects. Here, we observed the dynamic redshift and broadening of zero phonon line of silicon-vacancy (SiV−) centers at 4 K. Utilizing the intrinsic temperature response of the fine structure spectra of SiV− as a probe, we confirmed that laser heating effect appears and the temperature rising results from high defect concentration. By simulating the thermal diffusion process, we have estimated the thermal conductivity of around 1 W/(m K), which is a two-order magnitude lower than that of single-crystal diamond. Our results provide a feasible scheme for all-optical non-contact temperature sensing and help to solve the problem of accurate measurement of thermal conductivity at cryogenic temperatures.

Spin-Orbit Effects on Exciton Complexes in Diamond.

Ultrafine splittings are found in the optical absorption spectra of boron-doped diamond measured with high resolution. An analytical model of an exciton complex is developed, which permits assigning all absorption lines and sizing the interactions among the constituent charges and crystal field. We conclude that the entry of split-off holes in the acceptor-bound exciton fine structure yields two triplets separated by a spin-orbit splitting of 14.3meV. Our findings thereby resolve a long-standing controversy [R. Sauer et al., Revised fine splitting of excitons in diamond, Phys. Rev. Lett. 84, 4172 (2000).PRLTAO0031-900710.1103/PhysRevLett.84.4172; M. Cardona et al., Comment on "Revised fine splitting of excitons in diamond,", Phys. Rev. Lett. 86, 3923 (2001).PRLTAO0031-900710.1103/PhysRevLett.86.3923; R. Sauer and K. Thonke, Sauer and Thonke reply, Phys. Rev. Lett. 86, 3924 (2001).PRLTAO0031-900710.1103/PhysRevLett.86.3924], revealing the underlying physics common in diverse semiconductors, including diamond.

Effects of Salt Stress on Grain Quality and Starch Properties of High-Quality Rice Cultivars

In recent days, there has been a noticeable surge in demand for high-quality rice. However, the influences of salinity on the quality and starch properties of high-quality rice remain unclear. Three high-quality rice cultivars (Nanjing 9108, Nanjing 5055, and Nanjing 46) were studied to investigate the responses of grain quality to salt stress. There were three treatments, including a control zero salt level (0 g·kg−1, CK), and two salt levels of 0.1 g·kg−1 (0.1% salt stress, T1) and 0.2 g·kg−1 (0.2% salt stress, T2). The study involved the assessment of the appearance, milling, cooking, and eating qualities of rice. We also conducted an analysis of pasting properties, an evaluation of starch thermal properties, and an examination of the fine structure of amylopectin. The findings suggest that as the level of salt stress increases, the yield of rice gradually declines, which is primarily due to a significant reduction in the total spikelet number and the ratio of filled grains. Compared with CK treatment, the appearance and milling quality of rice were significantly improved within the T1 treatment. In addition, the protein concentration and amylose concentration were significantly decreased, the gel consistency was significantly increased, and the cooking and eating qualities were improved. In terms of starch properties, the peak viscosity, breakdown value, infrared ratio (1022/995), and short-chain-length amylopectin ratio increased significantly, while the setback value, pasting temperature, gelatinization enthalpy, relative crystallinity, and infrared ratio (1045/1022) decreased significantly. When comparing T2 with CK, the appearance quality and cooking and eating quality had deteriorated, and the milling quality was improved. The changes in the structural and physicochemical properties of starch were opposite to those in the comparison between the T1 treatment and the CK group. Accordingly, we propose that moderate salt stress has the potential to enhance rice quality, even though there may be a slight decrease in yield. This indicates that it is feasible to cultivate high-quality rice in saline–alkali beach areas.

Compressed sensing for rapid tabletop X-ray absorption spectroscopy

X-ray Absorption Fine Structure (XAFS) spectroscopy is an analytical technique of chemical insight. Improvements to this technique are continuously carried out for reduction of the acquisition time and increasing the resolution, especially for studying operando processes. The accurate reconstruction of XAFS signals requires that the collected data are noise-free to extract elemental structure information in post-processing. A novel approach to rapid sampling (encoded measurement) is validated conceptually. The technique relies on sparse signal recovery, i.e. using compressed sensing to reconstruct under-sampled signals. The proof of concept is demonstrated by using a python code to reconstruct under-sampled XAFS spectra. A case study of transition metal samples and their oxides is considered for this purpose. The results demonstrate a robust recovery of chemical information from a 30% sampled signal for the near-edge region analysis and from a 45% sampled signal for extended-edge region analysis. The application of this procedure is important for demonstrating the feasibility of tabletop operation using laboratory X-ray sources which are not continuously tunable.

Refinement of the uranium dispersion corrections from anomalous diffraction

The evolution of the uranium chemical state in uranium compounds, principally in the oxides, is of concern in the context of nuclear fuel degradation under storage and repository conditions, and in accident scenarios. The U–O system shows complicated phase relations between single-valence uranium dioxide (UO2) and different mixed-valence compounds (e.g. U4O9, U3O7 and U3O8). To try resolving the electronic structure associated with unique atomic positions, a combined application of diffraction and spectroscopic techniques, such as diffraction anomalous fine structure (DAFS), can be considered. Reported here is the application of two newly developed routines for assessing a DAFS data set, with the aim of refining the uranium X-ray dispersion corrections. High-resolution anomalous diffraction data were acquired from polycrystalline powder samples of UO2 (containing tetravalent uranium) and potassium uranate (KUO3, containing pentavalent uranium) using synchrotron radiation in the vicinity of the U L 3 edge (17.17 keV). Both routines are based on an iterative refinement of the dispersion corrections, but they differ in either using the intensity of a selection of reflections or doing a full-pattern (Rietveld method) refinement. The uranium dispersion corrections obtained using either method are in excellent agreement with each other, and they show in great detail the chemical shifts and differences in fine structure expected for tetravalent and pentavalent uranium. This approach may open new possibilities for the assessment of other, more complicated, materials such as mixed-valence compounds. Additionally, the DAFS methodology can offer a significant resource optimization because each data set contains both structural (diffraction) and chemical (spectroscopy) information, which can avoid the requirement to use multiple experimental stations at synchrotron sources.

Corrosion behavior of erbium modified Zn-11Al-3Mg cast alloy in stagnant 3.5 wt% NaCl solution

Zn-11Al and Zn-11Al-3Mg-xEr (x=0, 0.05, 0.1, 0.5) alloys were prepared, and the microstructures and corrosion resistance of the alloys were investigated by scanning electron microscopy (SEM), x-ray diffraction (XRD), and electrochemical methods. The results show that the primary Al-rich phase in Zn-11Al alloys is corroded as the main anode. The electronegativity of the primary Al phase in Zn-11Al-3Mg alloys is higher than the primary MgZn2 phase, and the electronegativity of Al-rich and Mg2Zn11 phases is higher than that of the η-Zn phase in ternary eutectic structure. The primary Al-rich phase and Mg2Zn11 phases in the alloy are corroded as the main anodes. On the other hand, the erbium (Er) reacts with Al to form the AlEr phase, and the AlEr phase has a significant refining and homogenizing effect on the primary Al-rich phase in the Zn-11Al-3Mg alloy. When the content of Er is 0.05%, the primary Al phase transforms into fine discontinuous cellular structure. However, the increase of Er addition promotes the growth of primary Al-rich phase and the reduction of ternary eutectic, which weakens the corrosion resistance of the alloy.

Effect of Mn addition on microstructure and corrosion behavior of AlCoCrFeNi high-entropy alloy

In this study, the effects of Mn content on the microstructure and corrosion resistance of AlCoCrFeNiMnx (x = 0, 0.25, 0.5, 0.75, and 1) high-entropy alloys were investigated. The results indicate that with increasing Mn content, the HEAs consistently comprise nanophase BCC geometry with different shapes embedded in the ordered B2-phase matrix, and the morphology of the microstructure changes from a coarse dendritic structure to a fine dendritic structure, then to a completely columnar dendrite structure. The microhardness of the HEAs increases gradually to 620 HV0.2 when x = 1, owing to the solid-solution and fine-grain strengthening. The corrosion resistance of the HEAs in 3.5 wt% NaCl solution first increases and then decreases, reaching a maximum with the lowest self-corrosion current density of 2.869 × 10−8 A∙cm−2 when x = 0.5. Improvement in corrosion resistance is related to a reduction in degree of composition segregation in the microstructure of HEAs, which leads to the formation of a dense and complete passivation film on the surface of the alloys. However, when the Mn content is in the range of 0–0.5, the pitting potential of the HEAs gradually decreases, although the passivation current density also gradually decreases. Higher Mn content (x > 0.5) leads to a transition of the HEAs from passivation to active dissolution. This indicates that the stability of the passivation film on the HEAs decreases with higher Mn content. XPS analysis revealed a gradual decline in the relative content of Cr2O3 and a gradual increase in the presence of unstable oxides such as MnO and Mn2O3 in the passivation film, leading to this phenomenon. The present work reveals that the addition of Mn in the AlCoCrFeNi HEA affects not only the microstructure and composition segregation but also the composition and stability of the passivation film, leading to a non-monotonic variation in the corrosion performance of the present HEAs with respect to the Mn content.

Enhanced thermal shock resistance of gradient high-entropy (La0.2Nd0.2Sm0.2Eu0.2Gd0.2)2Ce2O7/YSZ thermal barrier coatings

High-entropy (La0.2Nd0.2Sm0.2Eu0.2Gd0.2)2Ce2O7 (LECO) has been verified as a potential candidate for thermal barrier coatings (TBCs). In this work, two different structured LECO coatings were constructed and the thermal shock behavior was systematically investigated. In the classical double-layered LECO coating (D-LECO), the cracks initially originated from the edge and completely exfoliated from substrate after failure. To strengthen the thermal stress resistance of the coating, a gradient multilayered LECO/YSZ coating (M-LECO) was designed with five ceramic sub-layers. The thermal shock life of M-LECO was greatly enhanced by approximately 4 times. Unlike the typical TBCs, the delamination first appeared at an annular region on the surface, located away from the center and edge. Besides, the spalling only occurred in the topmost LECO layer with a thickness loss of less than 5%. After failure, the underneath coating could still provide efficient thermal protection to substrate. The better thermal shock resistance of M-LECO was mainly attributed to the fine gradient structure of the coating and the intrinsic property of high-entropy LECO. The microhardness and fracture toughness in M-LECO were strengthened layer by layer along the thickness direction, alleviating the thermal stress accumulation in the coating and greatly improving the cracking resistance of the interface. Moreover, the high-entropy effect and sluggish diffusion effect of LECO improved its sintering resistance, thereby enhancing the thermal shock resistance of M-LECO. Such design not only fully utilizes the unique thermo-physical properties of high-entropy ceramics, but also effectively solves the problem of weak adhesion between the LECO and the substrate during thermal shock.

Direct linearly polarized electroluminescence from perovskite nanoplatelet superlattices

AbstractPolarized light is critical for a wide range of applications, but is usually generated by filtering unpolarized light, which leads to substantial energy losses and requires additional optics. Here we demonstrate the direct emission of linearly polarized light from light-emitting diodes made of CsPbI3 perovskite nanoplatelet superlattices. The use of solvents with different vapour pressures enables the self-assembly of the nanoplatelets with fine control over their orientation (either face-up or edge-up) and therefore their transition dipole moment. As a result of the highly uniform alignment of the nanoplatelets, as well as their strong quantum and dielectric confinement, large exciton fine-structure splitting is achieved at the film level, leading to pure red light-emitting diodes with linearly polarized electroluminescence exhibiting a high degree of polarization of 74.4% without any photonic structures. This work demonstrates the potential of perovskite nanoplatelets as a promising source of linearly polarized light, opening up the development of next-generation three-dimensional displays and optical communications from a highly versatile, solution-processable system.