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This communication aims to address the recent surge of interest in reconfigurable intelligent surfaces (RISs) among both academic and industrial communities, which has largely neglected the historical developments of two other underpinning technologies, i.e., liquid crystal on silicon (LCOS) and liquid crystal reflectarray antenna (LCRA). Specifically, this communication focuses on the state of the art of LC-RIS, highlighting the unique features of this newly raised enabling technology for post-5G (6G) networks and comparing it to LCOS, which operates at different frequencies and is suited to different use cases. Drawing on insights from existing knowledge of LCOS and LCRA, opportunities and challenges are explored for LC-RIS’s technical advancements in enhancing the coverage, capacity, and energy efficiency of wireless networks. In particular, the development status and roadmap of LC-RIS in China is reviewed.

Revving up the rollout of high-data-rate low-latency next-generation communication and beyond (5G and 6G), the trend of developing tunable components based on tunable dielectrics is feeding the appetite for precise beam steering and wavefront phase control with more reconfigurability and bandwidth, as well as power-efficient stepless controllability (continuous analogue tuning) for mission-critical systems [...]

With global warming increasing at a faster rate in recent decades than at any other moment in recorded history, nuclear power, among a wide range of energy-efficient technologies, has been identified as the primary energy source in decarbonization for the improvement of security and efficiency [...]

Computationally modelling a nuclear reactor startup core for a benchmark against the existing models is highly desirable for an independent assessment informing nuclear engineers and energy policymakers. For the first time, this work presents a startup core model of the UK’s first Evolutionary Pressurised Water Reactor (EPR) based on Monte Carlo simulations of particle collisions using Serpent 2, a state-of-the-art continuous-energy Monte Carlo reactor physics burnup code. Coupling between neutronics and thermal-hydraulic conditions with the fuel depletion is incorporated into the multi-dimensional branches, obtaining the thermal flux and fission reaction rate (power) distributions radially and axially from the three dimensional (3D) single assembly level to a 3D full core. Shannon entropy is quantified to characterise the convergence behaviour of the fission source distribution, with 3 billion neutron histories tracked by parallel computing. Source biasing is applied for the variance reduction. Benchmarking the proposed Monte Carlo 3D full-core model against the traditional deterministic transport computation suite used by the UK Office for Nuclear Regulation (ONR), a reasonably good agreement within statistics is demonstrated for the safety-related reactivity coefficients, which creates trust in the EPR safety report and informs the decision-making by energy regulatory bodies and global partners.

A new phosphorus/nitrogen flame retardant (FR) containing reactive –P–O − NH 4 + groups was synthesized from glycerol, phosphoric acid, and urea. At high temperatures, the –P–O − NH 4 + group decomposed into –P–O − H + group, which produced phosphonic anhydride under the action of dicyandiamide catalyst. Phosphonic anhydride dehydrated and condensed with a hydroxyl group on the 6-position carbon atom in the glucose ring of cotton fiber, firmly binding the FR molecule to the fiber through a strong P–O–C bond. The structure of the FR was determined by Fourier-transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance spectroscopy ( 1 H NMR, 13 C NMR, and 31 P NMR). The effects of FR treatment on the flame retardancy, durability, and thermal stability of cotton fabrics were systematically investigated by measuring limiting oxygen index (LOI) and performing UL-94 vertical burning, cone calorimetry (CONE), thermogravimetric (TG), and differential scanning calorimetry tests. In addition, scanning electron microscopy-energy dispersive spectroscopy, FT-IR, and X-ray photoelectron spectrometry studies verified that FR molecules were grafted onto cotton fabrics. X-ray diffraction showed that FR did not affect their crystal structure. The treated cotton fabric with a weight gain of 25.3% exhibited an LOI of 40.5%, which was significantly higher than that obtained for the untreated cotton (17.0%); additionally, the treated cotton showed good self-extinguishing properties during the UL-94 vertical burning test. Furthermore, the results of CONE analysis indicated that the peak heat release rate of the untreated cotton reduced from 171.1 to 15.1 kW/m 2 after FR treatment, and its total heat release decreased from 6.3 to 1.1 MJ/m 2 . TG data revealed that FR finishing reduced the initial thermal degradation temperature of the untreated cotton under heating conditions to 225.9 and 221.8 °C in N 2 and air atmospheres, respectively, while the whiteness and mechanical properties of the treated cotton remained in the usable range. Analysis of the flame retardation mechanism of the FR showed that the dense phosphorus/nitrogen char layer that formed in the condensed phase effectively hindered the release of heat and diffusion of flammable volatile substances. This study provides new insights into the design and manufacturing of environmentally friendly FR-treated cotton fabrics with excellent flame retardancy and durability. Graphical abstract

The main objectives of this study incorporate the ecological environment index (ENV) and the digital economy index (DIG) into the environmental Kuznets (EKC) model and examine the income effects, scale effects, structural effects, technology effects, and government expenditures on the ecological environment, collating panel data for 31 provincial administrative regions in China over the period 2011–2019. The panel entropy value method was first applied to calculate the ecological environment index (ENV) and the digital economy composite index (DIG). Secondly, a threshold effect test is conducted with the digital economy as the threshold variable, and it is found that there are two threshold values in the model. From the threshold regression results, the impact of the digital economy on the ecological environment shows a positive “U” shape. At this stage, except for individual years in each province, most of the provinces are in the second half of the positive “U” curve. The coefficients of the income effect and scale effect are not significant, while the coefficients of structural effect and technology effect and government expenditure are significantly positive. From the results of the study, it is clear that the digital economy has a significant contribution to the improvement of the ecological environment in China at this stage. Policymakers should go further to promote the development of the digital economy while encouraging regional industrial structure optimization and increasing technological input support to ensure that the environment and economic development are coordinated in the digital economy era.

Continuous satellite measurements of the Earth's magnetic field have advanced the characterization of spatial‐temporal variations of the main field over the past two decades. To comprehend the underlying mechanism responsible for the geomagnetic field variations, we develop a novel core surface flow inversion scheme based on physics‐informed neural networks. The inversion method can account for the secular variation contributed by the interaction between the core flow and undetectable small‐scale magnetic fields. Based on the novel inversion framework, we derive a time‐dependent core surface flow model between 2000 and 2022 from the CHAOS‐7 core field model. The inverted core flow is then analyzed using the dynamic mode decomposition to extract wave‐like fluid motions. By calculating the magnetic secular acceleration contributed by each dynamic mode, we identify that the dynamic modes with period of about 10 and 7 years are responsible for geomagnetic jerks in the Atlantic and Pacific equatorial regions. Plain Language Summary Over the past two decades, satellites have been continuously monitoring the Earth's magnetic field. The major part of the field comes from the liquid part of the Earth's core. Geomagnetic measurements show quick changes in the field, including sudden shifts known as geomagnetic jerks. These shifts are believed to be linked to specific fluid motions in the Earth's core. Our study aims to better understand these flows and their effects. We use a method involving neural networks to figure out the patterns of flow at the core surface from the satellite data. We then use a technique to separate these flow patterns into simpler wave‐like forms. This helps us see how each wave pattern affects changes in the magnetic field. Our findings suggest that wave‐like motions with period of about 10 and 7 years caused geomagnetic jerks in the Atlantic and Pacific regions near the equator. Key Points A novel core surface flow inversion scheme based on physics‐informed neural networks is developed The inverted flow from the CHAOS‐7 model is analyzed using the dynamic mode decomposition to extract wave‐like flow patterns Geomagnetic jerks in the Atlantic and Pacific equator are related to two dynamic modes with period about 10 and 7 years

A systematic probabilistic safety assessment for a boiling water nuclear reactor core is performed using fault trees and event trees analysis models. Based on a survey of the BWR’s safety systems against potential hazards, eight independent failure modes (initiating events) triggered scenarios are modelled and evaluated in the assembled fault-event trees, obtaining the two key outcome probabilities of interest, i.e., complete core meltdown (CCMD) frequency and minor core damage (MCD) frequency. The analysis results indicate that the complete loss of heat sink accounts for the initiating accident most vulnerable to CCMD (with a frequency of 1.8 × 10−5 10−5 per year), while the large break in the reactor pressure vessel is the least susceptible one (with a frequency of 2.9 × 10−12 10−12 per year). The quantitative risk assessment and independent review conducted in this case study contributed a reference reliability model for defense-in-depth core optimizations with reduced costs, informing risk-based policy decision making, licensing, and public understanding in nuclear safety systems.

This work proposes and examines the feasibility of next-generation 0.3 THz phase shifters realized with liquid crystals (LCs) as tunable dielectrics coaxially filled in the transmission line. The classic coaxial transmission line topology is robust to electromagnetic interference and environmental noise, but is susceptible to higher-order modes from microwave to millimeter-wave towards terahertz (THz) wavelength ranges, which impedes the low-insertion-loss phase-shifting functionality. This work thus focuses primarily on the suppression of the risky higher-order modes, particularly the first emerging TE11 mode impacting the dielectric loss and metal losses in diverse manners. Based on impedance matching baselines at diverse tuning states of LCs, this work analytically derives and models two design geometries; i.e., design 1 for the coaxial geometry matched at the isotopically referenced state of LC for 50 Ω, and design 2 for geometry matched at the saturated bias of LC with the maximally achievable permittivity. The Figure-of-Merit for design 1 and design 2 reports as 35.15°/dB and 34.73°/dB per unit length, respectively. We also propose a constitutive power analysis method for understanding the loss consumed by constitutive materials. Notably, for the 0.3 THz design, the isotropic LC state results in an LC dielectric loss of 63.5% of the total input power (assuming 100%), which becomes the primary constraint on achieving low-loss THz operations. The substantial difference in the LC dielectric loss between the isotropic LC state and saturated bias state for the 0.3 THz design (35.76% variation) as compared to that of our past 60 GHz design (13.5% variation) indicates that the LC dielectric loss’s escalating role is further enhanced with the rise in frequency, which is more pronounced than the conductor losses. Overall, the results from analytical and finite-element optimization in this work shape the direction and feasibility of the unconventional THz coaxial phase shifting technology with LCs, actioned as continuously tunable dielectrics.