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Aerogel fibers garner tremendous scientific interest due to their unique properties such as ultrahigh porosity, large specific surface area, and ultralow thermal conductivity, enabling diverse potential applications in textile, environment, energy conversion and storage, and high‐tech areas. Here, the fabrication methodologies to construct the aerogel fibers starting from nanoscale building blocks are overviewed, and the spinning thermodynamics and spinning kinetics associated with each technology are revealed. The huge pool of material choices that can be assembled into aerogel fibers is discussed. Furthermore, the fascinating properties of aerogel fibers, including mechanical, thermal, sorptive, optical, and fire‐retardant properties are elaborated on. Next, the nano‐confining functionalization strategy for aerogel fibers is particularly highlighted, touching upon the driving force for liquid encapsulation, solid–liquid interface adhesion, and interfacial stability. In addition, emerging applications in thermal management, smart wearable fabrics, water harvest, shielding, heat transfer devices, artificial muscles, and information storage, are discussed. Last, the existing challenges in the development of aerogel fibers are pointed out and light is shed on the opportunities in this burgeoning field. Aerogel fibers emerge as rising stars in diverse fields of thermal management, smart wearable fabrics, water harvest, shielding, heat‐transfer devices, artificial muscles, and information storage. Starting from nanoscale building blocks, spinning thermodynamics and spinning kinetics associated with a variety of technologies are revealed. Aerogel fibers will earn an irreplaceable place with the advances in materials and fabrication methodologies.

In recent years, many studies have shown that it is meaningful to place rocks under stress paths corresponding to various loading and unloading conditions. However, the deformation evolution of rock under cyclic loading with consideration of the mechanical behavior and characteristics has rarely been studied under triaxial cyclic unloading and loading conditions. In practical engineering, particularly in underground or mining engineering, the stress increase in the rock mass in areas affected by mining is mainly caused by crack initiation and development when the rock is subjected to the effects of cyclic unloading and loading. In this study, variations in the stress–strain curves, irreversible strain, elastic modulus, and Poisson’s ratio are discussed and explained. The test results demonstrate that in comparison with a lower initial confining stress, increasing the initial confining pressure restrains the radial deformation of sandstone samples, and the degree of compaction of the sandstone samples rapidly increases in the failure stage. This results in the loss of the failure buffering process of the sandstone sample. Changes in the degree of compaction of the rock samples lead to obvious differences in the irreversible strain of the rock under different initial confining pressures and different limit unloading and loading cyclic confining stresses. The scanning electron microscopy and analysis results demonstrate that the macroscopic mechanical and microscopic physical properties of sandstone show different characteristics under different initial confining stresses.

This work aims at investigating the fracture evolution and energy characteristics of marble subjected to fatigue cyclic loading and confining pressure unloading (FC-CPU) conditions. Although rocks under separated fatigue cyclic loading and triaxial unloading conditions have been well studied, little is known about the dependence of the fatigue damage accumulation on the subsequent confining pressure unloading condition that influences the rock fracture behaviors. In this work, the servo-controlled GCTS 2000 rock mechanical system combined with the post-test X-ray computed tomography (CT) scanning technique were used to reveal the fracture behaviors of the marble samples. The samples were tested at three stages: the static loading stage, the fatigue cyclic loading stage, and the confining pressure unloading stage. Results show that the damage index-cycle number curve shows a different pattern—the damage increasing rate is different for the samples experiencing different fatigue damage. The damage accumulation at the fatigue cyclic stage influences the final failure mode and energy conversion. In addition, post-test CT scanning further reveals the effects of fatigue cycles on the crack pattern, as well as the stimulated crack scale and density after FC-CPU testing depending on the fatigue cycle. Furthermore, the stored elastic energy decreases and the dissipated energy increases with increasing fatigue cycle at the fatigue loading stage, and the energy conversion is consistent with the crack pattern analysis. By investigating the failure mechanism of marble under FC-CPU conditions, a theoretical basis for rock dynamic disaster prediction can be created.

The deformation and failure of rocks result from the dissipation and release of their internal energy. The energy evolution throughout the processes of deformation and failure in rock is a critical research topic. The triaxial cyclic loading and unloading tests under five confining pressures were carried out on high-temperature rock samples to investigate the influences of the confining pressure (σ3) and temperature (T) on their energy evolution and distribution characteristics. The energy densities of rock samples under various confining pressures were calculated by determining the area between the loading and unloading curves, including axial energy densities (u10, u1e, u1d) and circumferential strain energy density (u30). The energy accumulation and dissipation and the effect of σ3 and T on the energy distribution laws of loaded rock samples were analysed. The characteristic energy density (u1t) was used to analyse the accumulation, dissipation and release of energy of the loaded rock sample. u1t increased with the increase in σ3 and decreased with the increase in T. Furthermore, u30 increased with the increase in σ3, which effectively limited the energy dissipation and release due to fracture or failure of the rock sample. With the increase in T, the circumferential strain of the rock sample increased, which led to an increase in u30. At the pre-peak stage, energy accumulation characterised the energy behaviour of the loaded rock sample, and the proportion of the elastic energy density (k1e) was large. At the post-peak stage, energy release and dissipation characterised the energy behaviour of the loaded rock sample, the dissipated energy density proportion (k1d) increased gradually, and the change law for k1e and k1d was considerably affected by the confining pressure and temperature effect. The dissipated energy density of the loaded rock sample was used to establish the energy damage variable and analyse the evolution law of the dissipated energy damage variable of the high-temperature rock sample with σ3 and T. The results of this study can provide guidance for the research on high-temperature rock damage mechanisms and prevention of dynamic disasters of rock underground engineering.

Quantum communications promise to revolutionize the way information is exchanged and protected. Unlike their classical counterpart, they are based on dim optical pulses that cannot be amplified by conventional optical repeaters. Consequently, they are heavily impaired by propagation channel losses, confining their transmission rate and range below a theoretical limit known as repeaterless secret key capacity. Overcoming this limit with today’s technology was believed to be impossible until the recent proposal of a scheme that uses phase-coherent optical signals and an auxiliary measuring station to distribute quantum information. Here, we experimentally demonstrate such a scheme for the first time and over significant channel losses, in excess of 90 dB. In the high loss regime, the resulting secure key rate exceeds the repeaterless secret key capacity, a result never achieved before. This represents a major step in promoting quantum communications as a dependable resource in today’s world.A proof-of-principle experiment on twin-field quantum key distribution is demonstrated. The key rate overcomes the repeaterless secret key capacity bound limit at channel losses of 85 dB, corresponding to 530 km of ultralow-loss optical fibre.

In underground engineering constructions, fractured rock masses are likely to be subjected to three-dimensional static stress and dynamic loading simultaneously. In this study, via a modified split Hopkinson pressure bar (SHPB) system, a series of triaxial dynamic tests are carried on sandstone containing a pre-existing flaw under different radial confining pressures ranging from 5.7 to 22.7 MPa and different strain rates varying by 85–252 s−1. The results indicate that both the dynamic strength and energy dissipation density of single-flawed sandstone feature a positive correlation with the rising radial confining pressure and strain rate; while the dynamic elastic modulus, failure strain and energy utilization efficiency all exhibit an evident radial confining pressure enhancement effect, these are insensitive to the strain rate. Moreover, the fragment distributions of single-flawed sandstone are adequately characterized by combining sieving tests and generalized extreme value function. Under a higher strain rate, the single-flawed specimen is featured by smaller average fragment size and wider fragment distribution range, while the higher confining pressure has the opposite effect. By post-mortem examination, three main failure types are classified, and the fracturing mechanism of new cracks is revealed by microscopic observation using a scanning electron microscope (SEM). The macro oblique shear crack and through shear crack are mainly induced by the shear slip mechanism, while the quasi-coplanar crack is tensile dominated.HighlightsConducted a series of triaxial SHPB tests on the three-dimensional confined sandstone containing a pre-existing flaw.Investigated the radial confining pressure and strain rate effect on the dynamic mechanical response and failure characteristics of flawed rocks.Revealed the fracturing mechanism of new cracks from a microscopic perspective by the scanning electron microscope.

Selective partial oxidation of methane to methanol suffers from low efficiency. Here, we report a heterogeneous catalyst system for enhanced methanol productivity in methane oxidation by in situ generated hydrogen peroxide at mild temperature (70°C). The catalyst was synthesized by fixation of AuPd alloy nanoparticles within aluminosilicate zeolite crystals, followed by modification of the external surface of the zeolite with organosilanes. The silanes appear to allow diffusion of hydrogen, oxygen, and methane to the catalyst active sites, while confining the generated peroxide there to enhance its reaction probability. At 17.3% conversion of methane, methanol selectivity reached 92%, corresponding to methanol productivity up to 91.6 millimoles per gram of AuPd per hour.

This study focuses on the transport properties and permeability evolution characteristics of fluid flow through thermally treated rock samples containing single fractures. First, splitting fractures were generated in cylindrical granite samples after high-temperature exposure (25–800 °C). Then a series of water flow tests through both intact and fractured samples were conducted in a triaxial cell under different confining pressures (10–30 MPa) and varying inlet hydraulic pressures (0.4–6 MPa). The results show that as the temperature increases from 25 to 800 °C, the standard deviations of the 3D spatial distribution parameters, including the asperity height, slope angle, and aspect direction of the fracture surface mesh element planes, all increase, indicating gradually increasing fracture surface roughness. The relationships between the pressure gradient and flow rate of intact samples, fractured rock samples, and the fractures themselves can all be well fitted using the Forchheimer’s law. Both linear and nonlinear coefficients in the Forchheimer’s law increase with increasing confining pressure. An exponential function is used to evaluate the equivalent permeability of intact samples based on temperature levels. The permeability undergoes an increasing trend as the temperature increases due to thermally induced defects, but undergoes a decreasing trend as the confining pressure increases due to defect closure. Two representative types of flow characteristics through the fractured rock samples, dominated by either the rock matrix or fracture flow, are identified. In the temperature range of 25–800 °C, the critical Reynolds number of the fractures declines, which first remains generally constant for temperatures of 25–400 °C and then experiences a dramatic decrease for temperatures of 400–800 °C. The nonlinear coefficient bf in Forchheimer’s law versus the hydraulic aperture eh curves displays a decreasing trend following a power-law relationship. The Forchheimer’s law results are evaluated by plotting the normalized transmissivity against the pressure gradient. An increase in the confining pressure shifts the fitted curves downward. As the temperature increases, the contribution of the matrix to the overall discharge capacity of the fractured rock samples gradually enhances, while that for the fractures weakens. The reduction extent in permeability of the rough-walled fractures is more remarkable than that of the matrix under an applied confining pressure.

High-efficiency blue phosphorescence emission is essential for organic optoelectronic applications. However, synthesizing heavy-atom-free organic systems having high triplet energy levels and suppressed non-radiative transitions—key requirements for efficient blue phosphorescence—has proved difficult. Here we demonstrate a simple chemical strategy for achieving high-performance blue phosphors, based on confining isolated chromophores in ionic crystals. Formation of high-density ionic bonds between the cations of ionic crystals and the carboxylic acid groups of the chromophores leads to a segregated molecular arrangement with negligible inter-chromophore interactions. We show that tunable phosphorescence from blue to deep blue with a maximum phosphorescence efficiency of 96.5% can be achieved by varying the charged chromophores and their counterions. Moreover, these phosphorescent materials enable rapid, high-throughput data encryption, fingerprint identification and afterglow display. This work will facilitate the design of high-efficiency blue organic phosphors and extend the domain of organic phosphorescence to new applications. A strategy to confine phosphorescent organic chromophores within ionic crystals proves effective in suppressing non-radiative recombination channels and increasing the phosphorescence efficiency of blue-emitting heavy-atom-free emitters.

Photonic integrated circuits have the potential to pervade into multiple applications traditionally limited to bulk optics. Of particular interest for new applications are ferroelectrics such as Lithium Niobate, which exhibit a large Pockels effect, but are difficult to process via dry etching. Here we demonstrate that diamond-like carbon (DLC) is a superior material for the manufacturing of photonic integrated circuits based on ferroelectrics, specifically LiNbO 3 . Using DLC as a hard mask, we demonstrate the fabrication of deeply etched, tightly confining, low loss waveguides with losses as low as 4 dB/m. In contrast to widely employed ridge waveguides, this approach benefits from a more than one order of magnitude higher area integration density while maintaining efficient electro-optical modulation, low loss, and offering a route for efficient optical fiber interfaces. As a proof of concept, we demonstrate a III-V/LiNbO 3 based laser with sub-kHz intrinsic linewidth and tuning rate of 0.7 PHz/s with excellent linearity and CMOS-compatible driving voltage. We also demonstrated a MZM modulator with a 1.73 cm length and a halfwave voltage of 1.94 V. Lithium niobate (LN) is difficult to process via dry etching. Here, authors demonstrate the fabrication of deeply etched, tightly confining, low loss LN photonic integrated circuits with losses 4 dB/m using diamond like carbon as a hard mask.