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Blockchain technologies can enable secure computing environments among mistrusting parties. Permissioned blockchains are particularly enlightened by companies, enterprises, and government agencies due to their efficiency, customizability, and governance-friendly features. Obviously, seamlessly fusing blockchain and cloud computing can significantly benefit permissioned blockchains; nevertheless, most blockchains implemented on clouds are originally designed for loosely-coupled networks where nodes communicate asynchronously, failing to take advantages of the closely-coupled nature of cloud servers. In this paper, we propose an innovative cloud-oriented blockchain – CloudChain, which is a modularized three-layer system composed of the network layer, consensus layer, and blockchain layer. CloudChain is based on a shared-memory model where nodes communicate synchronously by direct memory accesses. We realize the shared-memory model with the Remote Direct Memory Access technology, based on which we propose a shared-memory consensus algorithm to ensure presistence and liveness, the two crucial blockchain security properties countering Byzantine nodes. We also implement a CloudChain prototype based on a RoCEv2-based testbed to experimentally validate our design, and the results verify the feasibility and efficiency of CloudChain. [ABSTRACT FROM AUTHOR]

A Diels–Alder (DA) bond containing poly(tetrahydrofuran)-co-(ethyleneoxide) (PET) based linear polyurethane (PET-DA-PU) was synthesized via a prepolymer process using PET as raw material, DA diol as chain extender agent, and toluene-2,4-diisocyanate (TDI) as coupling agent. The structure of PET-DA-PU was characterized by attenuated total reflectance-Fourier transform-infrared spectroscopy (ATR-FTIR), proton nuclear magnetic resonance spectrometry (1H NMR) and carbon nuclear magnetic resonance spectrometry (13C NMR). The thermal performance and self-healing behavior of PET-DA-PU were investigated by differential scanning calorimetry (DSC), polarized optical microscope, universal testing machine, scanning electron microscopy (SEM) and NMR, respectively. The glass transition temperature of PET-DA-PU was found to be −59 °C. Under the heat treatment at 100 °C, the crack on PET-DA-PU film completely disappeared in 9 min, and the self-healing efficiency that was determined by the recovery of the largest tensile strength after being damaged and healed at 100 °C for 20 min can reach 89.1%. SEM images revealed the micro-cracks along with the blocky aggregated hard segments which were the important reasons for fracture. NMR spectroscopy indicated that the efficiency of retro DA reaction of PET-DA-PU was 70% after 20 min heating treatment at 100 °C. Moreover, the PET-DA-PU/Al/Na2SO4 composite was also prepared to simulate propellant formulation and investigated by universal testing machine and SEM; its healing efficiency was up to 87.8% under the same heat treatment process and exhibits good self-healing ability. Therefore, PET-DA-PU may serve as a promising thermally self-healing polymeric binder for future propellant formulations. [ABSTRACT FROM AUTHOR]

Despite the discovery of superconducting properties in thin films with an infinite-layer structured nickelate has paved the way for exploring unconventional superconductivity, opening up new possibilities in this field. However, the challenges related to fabricating these samples have greatly restricted research in this area. In this study, we successfully fabricated superconducting thin films of La 0.8 Sr 0.2 NiO 2 and investigated their tolerance to different environmental factors. To analyze the stability of the superconducting La 0.8 Sr 0.2 NiO 2 thin films, we assessed their tolerance to temperature by examining the peak intensities in X-ray diffraction (XRD) and monitoring the changes in resistance curves at varying temperatures. In addition, we investigated the films' sensitivity to acidity and alkalinity by immersing them in acidic and alkaline solutions for various durations. We also studied the stability of the thin films under various conditions, including heating in air, heating in a vacuum, exposure to acid and alkali, as well as exposure to the organic solvent acetone solution. Our findings highlight the successful preparation of superconducting La 0.8 Sr 0.2 NiO 2 thin films and shed light on their stability in different environments. This research provides valuable insights for further exploration of their potential applications and laid the foundation for advancements in the field of unconventional superconductivity. [Display omitted] • We successfully fabricated superconducting thin films of La 0.8 Sr 0.2 NiO 2 and investigated their tolerance to different environmental factors. • We investigated the resistance and X-ray diffraction changes in nickelate under various conditions, including heating in air and vacuum, and exposure to 10M NaOH, 1M HCl, and acetone. Our findings indicate that the stability of La 0.8 Sr 0.2 NiO 2 superconductivity is affected by environmental factors, losing its superconductivity at 160°C in air and 220°C in vacuum. • Our research shows that our superconducting sample loses superconductivity upon immersion in an acidic solution but remains stable in an alkaline environment, maintaining zero resistance for up to 2 h in 10M NaOH before losing superconductivity after 3 hours. Additionally, La 0.8 Sr 0.2 NiO 2 loses superconductivity and exhibits insulating behavior after 330 minutes in acetone. [ABSTRACT FROM AUTHOR]

In the present paper, we establish two Erdélyi-type integrals for Saran's hypergeometric function F K , which has applications in specific branches of applied physics and statistics (see below). We employ methods based on the k-dimensional fractional integration by parts to obtain our main integral identities. The first integral generalizes Koschmieder's result and the second integral extends one of Erdélyi's classical hypergeometric integral. Some useful special cases and important remarks are also discussed. [ABSTRACT FROM AUTHOR]

Electronic skin plays an important role in the age of artificial intelligence. Capacitive pressure sensors, capable of sensing pressure changes through contact, still need to improve their basic performance and comfort of use. In this paper, a flexible strontium alginate film with finely folded crater microstructure prepared by spraying method is introduced as a dielectric layer, together with PDMS film and conductive cloth as a capacitive sensor. The internal and external displacement, potential, and elastic volume ratio of the sensor were simulated using finite element analysis. The sensor has good sensitivity (R2 up to 0.99), very low response and relaxation time (≤ 50 ms), and good cyclic stability. The sensor was also used for performing several simple applications tests. • A transparent and ultrathin flexible film with crater microstructure and uniform fine pleated structure prepared by spraying method. • The dielectric constant of the SCA film reached 15.3, which was 1.18 times higher than that of the SA film and 4.5 times higher than that of the PDMS film. • The relative dielectric constant of the dielectric layer increases due to ion displacement polarization generated at the surface of the SCA film. • The capacitive pressure sensor presents high sensitivity, very short response and relaxation times, and good cycling stability. [ABSTRACT FROM AUTHOR]

In a potassium-ion battery, concentration gradients of K+ and electrons along electrode thickness usually result in uneven potassiation of electrode material. It is highly possible that the electrode material on the collector side will never reach full stage of charge like that on the separator side especially for thick electrodes. Herein, we develop a unique and huge cobblestone-shaped Fe 3 O 4 /C heterostructure in hope to address this problem by converting unidirectional concentration gradient into a three-dimensional one. This structure that comprises labyrinthine carbon skeleton and encapsulated Fe 3 O 4 nanoparticles is propitious to reduce tortuosity beyond particles and accelerate K+ transportation to collector on potassiation. In battery use, Fe 3 O 4 nanoparticles boost K+-storage capability through conversion mechanism, while carbon capsules physically isolate Fe 3 O 4 nanoparticles and serve as nano-reactors for their conversion reactions. Moreover, the carbon skeleton also improves electronic conductivity of the structure and enhances K+-storage capability/cyclability through electrical double-layer capacitive mechanism. As a result, this structure delivers high capacity of ∼406 mAh g−1 at 0.1 A g−1 after 200 cycles and exhibits exceptional cyclability over 700 cycles at 2 A g−1 with capacity of 309 mAh g−1. Besides, the full-cell test shows capacity of ∼112 mAh g−1 at 0.2 A g−1 after 500 cycles. [Display omitted] • Fe 3 O 4 nanoparticles are encapsulated in carbon capsules to form a heterostructure. • It delivers K+-storage capacity of ∼406 mAh g−1 at 0.1 A g−1 after 200 cycles. • It shows good cyclability over 700 cycles at 2 A g−1 with a capacity of 309 mAh g−1. • Its full cell delivers a capacity of ∼112 mAh g−1 at 0.2 A g−1 after 500 cycles. [ABSTRACT FROM AUTHOR]

Aiming to obtain the acoustic attenuation performance of exhaust muffler of diesel engine and the influence of main structural parameters on its acoustic attenuation characteristics, the finite element analysis method and acoustic theory were adopted to numerically investigate the acoustic attenuation performance under the boundary condition of acoustic adiabatic propagation and muffler wall. It suggested that the noise cancellation effect of muffler was poor at the middle and low frequency in range of 0–3000 Hz, and the transfer loss of muffler was basically 0 dB pass frequency at 1100 Hz. According to previous single-factor study experience, the structural factors, such as the expansion ratio, insertion length of outlet perforated pipe, the distance between the diaphragm and the front part of muffler, have influences on the acoustic performance of muffler at low frequency. Thus, they were taken as the starting point to study the influence of multiple interaction factors on the muffling performance by using orthogonal design method combined with the finite element analysis method. The influence degree of different structure parameters on the acoustic performance of muffler and the optimized structure parameters were obtained. Through the analysis on the acoustic characteristic of the optimized muffler, it indicated that the transmission loss of the improved muffler had significant increase in other frequency range except the range of 650–800 Hz and 2500–2700 Hz, especially at frequency of 1100 Hz compared with the original muffler. In the range of 0–3000 Hz, the mean of transmission loss of the improved muffler was about 9.8 dB larger than that of original muffler, which indicated that better noise cancellation effect was achieved. The improved muffler also provided a certain reference for the structural improvement of similar muffler. [ABSTRACT FROM AUTHOR]

Cinnamomum camphora fruit extract was used to biosynthesise silver nanoparticles (AgNPs), and the optimised synthesis system was ascertained through solution colour change and ultraviolet–visible absorption spectra. It contained 20 ml of fruit extract, 4 mM Ag nitrate, and pH 7. AgNPs obtained based on such conditions were spherical and finely dispersed, with an average size of 20.3 nm. As‐synthesised AgNPs exhibited excellent antifungal effect against Fusarium oxysporum. At a dose of 400 μg/ml of AgNPs, the inhibition rate of colony growth reached 61.00% and an IC50 value of 154.39 μg/ml. In addition, the conidia germination was totally inhibited at 100 μg/ml of AgNPs. Results of this study provide a new approach for biological control of plant pathogenic fungi, and it makes that possible for developing a brand new fungistat. [ABSTRACT FROM AUTHOR]

• The effect of electric field on frost crystal growth and jumping is investigated. • The effect of electric field on frost quality was investigated. When the electric field strength reached 6 kV/cm, the frost quality decreased by 54.5 %. • Frost jumping under an electric field is beneficial for anti-icing/frosting. The frosting phenomenon under the influence of an electric field deserves is of interest. It is closely related to the frosting problems of transmission conductors, power devices, etc. In the present study, the growth and jumping characteristics of frost on a frozen droplet were investigated by the visual experiments under an electric field. It is shown that the electric field promotes the growth of primary branch of the frost crystal, while the lateral branch constrains the growth. When the EF (electric field strength) reached 6 kV/cm, the frost crystal became a non-lateral branch structure. In addition, the frost jumping behavior induced by the electric field has changed the frost morphology, and the regularity of frost jumping at different EF has been analyzed. The frequency of frost jumping increases with the increase of EF. When the EF reaches 6 kV/cm, the frost mass drops by 54.5 %. According to the present study, a potential innovation in anti-frosting/icing technology is to propose a rational structural arrangement of the cooling surface under an electric field to maximize the frost jumping effect. [ABSTRACT FROM AUTHOR]

Blockchain creates a secure environment on top of strict cryptographic assumptions and rigorous security proofs. It permits on-chain interactions to achieve trustworthy properties such as traceability, transparency, and accountability. However, current blockchain trustworthiness is only confined to on-chain, creating a “trust gap” to the physical, off-chain environment. This is due to the lack of a scheme that can truthfully reflect the physical world in a real-time and consistent manner. Such an absence hinders further blockchain applications in the physical world, especially for the security-sensitive ones. In this paper, we propose a framework to extend blockchain trust from on-chain to off-chain, and take trustworthy vaccine tracing as an example scheme. Our scheme consists of 1) a Trusted Execution Environment (TEE)-enabled trusted environment monitoring system built with the Arm Cortex-M33 microcontroller that continuously senses the inside of a vaccine box through trusted sensors and generates anti-forgery data; and 2) a consistency protocol to upload the environment status data from the TEE system to blockchain in a truthful, real-time consistent, continuous and fault-tolerant fashion. Our security analysis indicates that no adversary can tamper with the vaccine in any way without being captured. We carry out an experiment to record the internal status of a vaccine shipping box during transportation, and the results indicate that the proposed system incurs an average latency of 84 ms in local sensing and processing followed by an average latency of 130 ms to have the sensed data transmitted to and been available in the blockchain. [ABSTRACT FROM AUTHOR]

In order to enhance the application performance of glycidyl azide polymer (GAP) in solid propellant, an energetic copolyurethane binder, (poly[3,3-bis(2,2,2-trifluoro-ethoxymethyl)oxetane] glycol-block-glycidylazide polymer (PBFMO-b-GAP) was synthesized using poly[3,3-bis(2,2,2-trifluoro-ethoxymethyl)oxetane] glycol (PBFMO), which was prepared from cationic polymerization with GAP as the raw material and toluene diisocyanate (TDI) as the coupling agent via a prepolymer process. The molecular structure of copolyurethanes was confirmed by attenuated total reflectance-Fourier transform-infrared spectroscopy (ATR–FTIR), nuclear magnetic resonance spectrometry (NMR), and gel permeation chromatography (GPC). The impact sensitivity, mechanical performance, and thermal behavior of PBFMO-b-GAP were studied by drop weight test, X-ray photoelectron spectroscopic (XPS), tensile test, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and thermal gravimetric analysis (TGA), respectively. The results demonstrated that the introduction of fluoropolymers could evidently reduce the sensitivity of GAP-based polyurethane and enhance its mechanical behavior (the tensile strength up to 5.75 MPa with a breaking elongation of 1660%). Besides, PBFMO-b-GAP exhibited excellent resistance to thermal decomposition up to 200 °C and good compatibility with Al and cyclotetramethylene tetranitramine (HMX). The thermal performance of the PBFMO-b-GAP/Al complex was investigated by a cook-off test, and the results indicated that the complex has specific reaction energy. Therefore, PBFMO-b-GAP may serve as a promising energetic binder for future propellant formulations. [ABSTRACT FROM AUTHOR]

A series of lead-free Rb2ZrCl6:xTe4+ (x = 0%, 0.1%, 0.5%, 1.0%, 2.0%, 3.0%, 5.0%, 10.0%) perovskite materials were synthesized through a hydrothermal method in this work. The substitution of Te4+ for Zr in Rb2ZrCl6 was investigated to examine the effect of Te4+ doping on the spectral properties of Rb2ZrCl6 and its potential applications. The incorporation of Te4+ induced yellow emission of triplet self-trapped emission (STE). Different luminescence wavelengths were regulated by Te4+ concentration and excitation wavelength, and under a low concentration of Te4+ doping (x ≤ 0.1%), different types of host STE emission and Te4+ triplet state emission could be achieved through various excitation energies. These luminescent properties made it suitable for applications in information encryption. When Te4+ was doped at high concentrations (x ≥ 1%), yellow triplet state emission of Te4+ predominated, resulting in intense yellow emission, which stemmed from strong exciton binding energy and intense electron-phonon coupling. In addition, a Rb2ZrCl6:2%Te4+@RTV scintillating film was fabricated and a spatial resolution of 3.7 lp/mm was achieved, demonstrating the potential applications of Rb2ZrCl6:xTe4+ in nondestructive detection and bioimaging. [ABSTRACT FROM AUTHOR]

Dark septate endophytes (DSEs) usually colonize plant roots, especially in stress environments. However, their relationship with plants ranges from beneficial to harmful and has remained largely uncharacterized. In the present study, 14 DSE species grouped into 11 genera were isolated from the roots of a desert plant, Artemisia ordosica, which is widely distributed in northwest China. Three dominant DSE species—Paraphoma chrysanthemicola (Pc), Alternaria chartarum (Ac), and Acrocalymma vagum (Av)—were selected and tested for their resistance to drought in vitro. Furthermore, we characterized the responses of A. ordosica under drought conditions in relation to the presence of these DSEs following inoculation. The results showed that all three strains grew well under in vitro drought stress, and the biomass of Ac and Av was significantly higher than that of the unstressed control. The effects of DSE inoculation on the growth of A. ordosica under drought stress varied according to the different DSE species but were generally beneficial. Under drought stress, Av and Pc promoted plant growth, antioxidant enzyme activity, and root development of the hosts. The Ac strain conferred obvious positive effects on the antioxidant enzyme activity of the hosts. In general, Av and Pc demonstrated better application potential for improving the drought resistance of A. ordosica. [ABSTRACT FROM AUTHOR]

• The interaction of oxygen and cerium-free ions in molten 3LiCl-2KCl eutectic K was studied. • Stable states of cerium compounds and the mechanism of interaction have been established. • The solubility constants and principal thermodynamic data of CeOCl and Ce 2 O 3 were calculated. • The Pourbaix diagram was drawn and the characteristics of the stable cerium species were summarized. The interaction of oxygen and cerium-free ions in molten 3LiCl-2KCl eutectic in the temperature range of (723–823) K was studied by the method of potentiometric titration using YZME electrodes. Stable states of cerium compounds in the Ce–O system and the mechanism of interaction of Ce3+ with O2− ions have been established. The solubility constants of cerium oxychloride and oxide compounds at different temperatures were determined. Principal thermodynamic data of CeOCl and Ce 2 O 3 were calculated. The Pourbaix (potential-pO2−) diagram was drawn and summarizes the properties of stable cerium species in the melt. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel energetic acrylate-terminated oligomer was designed and prepared. • A new 3D-printed gun propellant with higher energy was fabricated by SLA. • The suitability of this new material and its composites on SLA was demonstrated. Propellants are the main energy source in the internal ballistic process. The use of 3D printing has promised to produce propellants with complex geometries. However, due to the degraded energy properties of propellants using an inert binder, there is a critical need to develop a printable energetic resin. In this paper, a novel energetic acrylate-terminated poly–3–nitratomethyl–3–methyloxetane (APNIMMO) oligomer was prepared and characterized. The performance of a new composite propellant composed of APNIMMO and CL-20 (Hexanitrohexaazaisowurtzitane Dodecane) was also demonstrated. The new energetic printable resin and its composites are suitable for stereolithography (SLA) 3D printing, offering not only an improved thermodynamic energy, but also a substantially improved burn rate. Compared with the inert binder, the energetic binder offers the possibility to improve the thermodynamic energy by 15% and the burn rate at 100 MPa by 480% for 3D printed propellants. [ABSTRACT FROM AUTHOR]

VLBI is a differential technique observing at multiple frequencies. Thus, it can independently provide ionospheric delays. GNSS can supply precise ionospheric delays as well, often with comparable or even better spatial coverage. In this presentation, we compare the VLBI differential ionosphere from two sites with multiple VLBI antennas with the co-located GNSS ionospheric calibrations. In S/X VLBI, a linear combination of X-band and S-band delays is used to provide a calibrated group delay measurement that is free of ionospheric effects to first order. In contrast, the VGOS system is designed to provide group delay and ionospheric delay through a simultaneous fit to measurements in 4 frequency bands distributed over a wide frequency range. The CONT17 VGOS data have been calibrated in terms of ionosphere in advance and thus directly provide TEC for each observation. In this work we compare the extracted ionospheric delays from dual-frequency observations of GNSS with the ones from dual-frequency S/X VLBI and from co-located VGOS stations in the CONT17 experiment to better understand how well VLBI can contribute to the study of the ionosphere. Since both source structure and ionosphere effects on geodetic VLBI data analysis are dispersive, in the future we will introduce an optimal match for VLBI and GNSS and compare ionospheric delays obtained from different radio sources to help to improve the modeled structure effect. [ABSTRACT FROM AUTHOR]

An azide terminated ethylene oxide‐tetrahydrofuran copolymer with urethane segments (ATUPET) as a novel binder pre‐polymer, has been prepared through ethylene oxide‐tetrahydrofuran random copolymer (PET) end‐capping modification via one‐pot method. The structure characterization of the modifier has been analyzed by FTIR, 1H NMR, 13C NMR and GPC. In comparison with PET, ATUPET has a slightly higher viscosity because it has additional hydrogen bonding interaction generated by the urethane in ATUPET. Triazole cross‐linked elastomers based on ATUPET with various functional molar ratios were prepared using tripropargylamine as a curing agent and cross‐linker. Mechanical properties indicate that the modulus E and tensile strength σb exhibit a parabolic dependence with the increase in R. At around the stoichiometric ratio, the modulus E and tensile strength σb reach a maximum and the elongation at break exhibit an acceptable value at the same time. Swelling tests demonstrate that the apparent cross‐linking densities (N0) have a maximum value at the stoichiometric ratio. Thermal analysis shows that the ATUPET prepolymer and its polytriazoles elastomers exhibit a satisfactory stability. The results demonstrated that ATUPET might be a promising polymeric binder for future propellant formulations especially in the field of isocyanate‐free curing technology. [ABSTRACT FROM AUTHOR]

Abstract In order to carry out an ex-post assessment of the completed Building Energy Efficiency Special Planning, a comprehensive ex-post assessment methodology is established. The methodology sets out the ex-post assessment criteria from three dimensions and 27 indexes, and apply the Fuzzy Synthetic Evaluation Method to build the ex-post assessment model. Applying the methodology, this research assesses the effectiveness of the Building Energy Efficiency Special Planning in Beijing during the "12th Five-Year Plan" period. The results show that it is generally effective in terms of realizing the main planning targets, reaching the desired development level of Building Energy Efficiency and ensuring the facilitating mechanisms to be in place. To be specific, substantial increase of the proportion of energy efficient buildings and considerable effects of energy saving and carbon emission reduction have been achieved, whilst the electricity consumption per unit area in small and median-sized commercial buildings being increased. The research further identifies the main barriers to the implementation of building energy efficiency program includes high electricity consumption of large-scale commercial buildings, insufficient data information, slow uptake of modern information technology, lack of market participation and lack of wider social recognition. Based on the assessment result and subsequent analysis, commensurate policy recommendations were proposed. This research was the first attempt examining the implementation effects of BEE Special Planning in Beijing. Highlights • We set out the ex-post assessment criteria from three dimensions. • Establish the ex-post assessment framework from target layer, criteria layer and index layer, and 27 indexes are identified. • Establish the ex-post assessment model by applying the FSEM. • The indicators' evaluation standards are the important factors affecting the ex-post assessment result. • Identify the main barriers to BEE implementation in Beijing and propose policy recommendations. [ABSTRACT FROM AUTHOR]

As an essential rubber mixing equipment in continuous production, an internal mixer should have a long service life while operating at high intensity. Studies show that at these severe operating conditions, end face wear of the internal mixer is inevitable. It is worth noting that the end face is an important part of the closed mixing chamber. The head of the rotor shaft is inserted into the copper ring of the sealing plate, the sealing plate and the mixing chamber are pressed together by bolts. There is a gap between the rotors and the mixing chamber. During the mixing process, the mixed rubber in the mixing chamber is in direct contact with the end face, the end face metal is frictional and abraded. Wear of the end face may result in a gap between the mixing chamber and the end face, leading to material leakage. As the leakage intensifies, the gap between the end face and the mixing chamber further increases, thereby forming negative feedback. This phenomenon not only affects the chemical composition of the rubber but also reduces the mixing efficiency and decreases the performance of the rubber compound. The end surface material is cobalt chromium molybdenum tungsten alloy. The alloy model is Stellite 6B. In the present study, the influence of different amounts of CF on the friction and wear of the end face is analyzed from the chemical composition perspective. Moreover, the ratio of corrosion wear to abrasive wear is calculated. The obtained results show that as the amount of CF in the compound increases, the proportion of the corrosive wear of the compound to the metal increases, while the proportion of abrasive wear decreases. The highest proportion of corrosive wear and the lowest amount of metal wear can be achieved for the CF amount of 9 phr. As the CF content in the composition increases, the ratio of the corrosive wear of the rubber compound to metal decreases, while the proportion of abrasive wear and the total amount of wear to metal increases. • Studies show that at these severe operating conditions, end seal wear of the internal mixer is inevitable. • This study analyzed the effect of different additions of CF on the friction and wear of the end seal. • The highest proportion of corrosive wear and the lowest amount of metal wear can be achieved for the CF amount of 9 phr. [ABSTRACT FROM AUTHOR]

Weak interfacial interactions remain a bottleneck for composite materials due to their weakened performance and restricted applications. The development of core–shell engineering shed light on the preparation of compact and intact composites with improved interfacial interactions. This review addresses how core–shell engineering has been applied to energetic materials, with emphasis upon how micro-energetic materials, the most widely used particles in the military field, can be generated in a rational way. The preparation methods of core–shell structured explosives (CSEs) developed in the past few decades are summarized herein. Case studies on polymer-, explosive- and novel materials-based CSEs are presented in terms of their compositions and physical properties (e.g., thermal stability, mechanical properties and sensitivity). The mechanisms behind the dramatic and divergent properties of CSEs are also clarified. A glimpse of the future in this area is given to show the potential for CSEs and some suggestions regarding the future research directions are proposed. [ABSTRACT FROM AUTHOR]

Africa has been undergoing a rapid urbanization process, which is critical to the achievement of the 11th Sustainable Development Goal (SDG11). Using population density data from LandScan, we proposed a population density-based thresholding method to generate urban land and urban population data in Africa from 2001 to 2019, which were further applied to detect the spatiotemporal characteristics of Africa's urbanization. The results showed that urban land and urban population have both grown rapidly in Africa, which increased by about 5.92% and 4.91%, respectively. The top three countries with the most intense urbanization process in Africa are Nigeria, the Democratic Republic of the Congo, and Ethiopia. The coupling relationship index of urban land expansion and population growth was 0.76 in Africa during 2001–2019. Meanwhile, the total proportion of uncoordinated development types at the provincial level was getting higher, which indicated an uncoordinated relationship between urban land expansion and population growth in Africa. Cropland, grassland, rural land, and forests were the most land-use types occupied by urban expansion. The proportion of cropland, grassland, and forests occupied was getting higher and higher from 2001 to 2019. The extensive urban land use may have an impact on the environmental and economic benefits brought by urbanization, which needs further research. [ABSTRACT FROM AUTHOR]