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Effectively understanding the semantics of sophisticated sceneries is a key module in plenty of artificial intelligence (AI) systems. In this article, we optimally fuse multi-channel perceptual visual features for recognizing scenic pictures with complex spatial configurations, focusing on formulating a deep hierarchical model to actively discover human gaze allocation. In detail, to uncover semantically/visually important patches within each scenery, we utilize the BING objectness descriptor to rapidly and accurately localize multi-scale objects or their components. Subsequently, a local-global feature fusion scenario is proposed to dynamically combine the multiple low-level features from multiple scenic patches. To simulate how humans perceiving semantically/visually important scenic patches, we design a robust deep active learning (RDAL) paradigm that sequentially derives gaze shift path (GSP) and hierarchically learns deep GSP features in a unified architecture. Notably, the key advantage of RDAL is the high tolerance of label noise by adding an elaborately-designed sparse penalty. That is, the contaminated and redundant deep GSP features can be implicitly abandoned. Finally, the refined deep GSP features are integrated into a multi-label SVM for recognizing sceneries of different categories. Empirical comparisons showed that: 1) our method performs competitively on six generic scenery set (average accuracy 2%~4.3% higher than the second best performer), and 2) our deep GSP feature is particularly discriminative to our compiled sport educational image set (average accuracy 7.7% higher than the second best performer).

The privacy concern in smart contract applications continues to grow, leading to the proposal of various schemes aimed at developing comprehensive and universally applicable privacy-preserving smart contract (PPSC) schemes. However, the existing research in this area is fragmented and lacks a comprehensive system overview. This paper aims to bridge the existing research gap on PPSC schemes by systematizing previous studies in this field. The primary focus is on two categories: PPSC schemes based on cryptographic tools like zero-knowledge proofs, as well as schemes based on trusted execution environments. In doing so, we aim to provide a condensed summary of the different approaches taken in constructing PPSC schemes. Additionally, we also offer a comparative analysis of these approaches, highlighting the similarities and differences between them. Furthermore, we shed light on the challenges that developers face when designing and implementing PPSC schemes. Finally, we delve into potential future directions for improving and advancing these schemes, discussing possible avenues for further research and development.

As an important part of the terrestrial ecosystem, vegetation dynamics are subject to impacts from both climate change and human activities. Clarifying the driving mechanisms of vegetation variation is of great significance for regional ecological protection and achieving sustainable development goals. Here, net primary productivity (NPP) was used to investigate the spatiotemporal variability of vegetation dynamics from 2000 to 2020 in East Africa, and its correlations with climate factors. Furthermore, we utilized partial derivatives analysis and set up different scenarios to distinguish the relative contributions of climatic and human factors to NPP changes. The results revealed that NPP exhibited a significant increase with 4.16 g C/m2/a from 2000 to 2020 in East Africa, and an upward trend was detected across 71.06% of the study area. The average contributions of precipitation, temperature, and solar radiation to the NPP inter-annual variations in East Africa were 2.02, −1.09, and 0.31 gC⋅m–2⋅a–1, respectively. Precipitation made the greatest positive contribution among all of the climatic factors, while temperature made strong negative contributions. The contributions of climate change and human activities to NPP changes were 1.24 and 2.34 gC⋅m–2⋅a–1, respectively. Moreover, the contribution rate of human activities to NPP increase was larger than that of climate change, while the role of climate change in NPP decrease was larger than that of human activities. The findings of the study can provide new evidence for a deeper understanding of ecosystem stability and carbon cycling in East Africa, as well as a reference for decision-making and scientific support for ecological environmental protection.

The weak interfacial interaction and high sensitivity is a longstanding problem for nitramine explosives. Herein, polyhydroxyethyl acrylate nitrate (PANE) was adopted to passivate three nitramine explosives through a facile and efficient in situ polymerization method. The core-shell structure of the PANE-coated composites was confirmed after detailed morphological and structural characterization. As a result, we find that, the hydrophobic PANE shell improved the adhesion work between the explosives and fluoropolymer (F2314) binder because of the enriched interfacial interactions. Besides, 2% PANE can retard the crystal transformation of CL-20 and HMX explosives by 10.7 °C and 4.3 °C, but does not affect the thermal decomposition behavior. The mechanical sensitivity of PANE-coated composites decreased more significantly than raw explosives and the mixed samples. As a typical example, the impact and friction sensitivity of CL-20@PANE composite with 2.0% shell content is practically halved when compared to raw CL-20 with the characteristicheight (H50) of 32.2 cm and the explosionprobability (P) of 50%. This study offers a simple, effective and universal method for design and preparation of energetic composites with high safety performance.

Objective: Shenfu Injection (SFI) derived from Shenfu decoction, has been widely used for treating heart failure in China. This meta-analysis aimed to assess the effect of SFI as an adjuvant therapy on quality of life in patients with chronic heart failure (CHF). Methods: A systematic literature search was conducted in CKNI, VIP, Wanfang, Sinomed, Cochrane Library, PubMed, and Embase database until March 16, 2023. Randomized controlled trials (RCTs) evaluating the effect of SFI plus conventional therapy versus conventional therapy alone for treating CHF were included. Outcome measures were quality of life defineded by the Minnesota Living with Heart Failure questionnaire (MLHFQ), left ventricular ejection fraction (LVEF), 6-min walking distance, and blood brain natriuretic peptide (BNP)/N-terminal pro-brain natriuretic peptide (NT-proBNP) level. Results: Thirteen RCTs enrolling 1042 CHF patients were included. SFI plus conventional therapy significantly reduced the total MLHFQ score (mean difference [MD] −8.69 points; 95% confidence intervals [CI] −13.46 to −3.91) compared with the conventional therapy alone. Moreover, adjuvant treatment with SFI significantly improved the 6-min walking distance (MD 65.42 m; 95% CI 44.23 to 86.62), LVEF (MD 3.89; 95% CI 1.03 to 6.75), and blood level of BNP/NT-proBNP (SMD -1.73; 95% CI -2.43 to −1.03). Conclusions: Adjuvant treatment with SFI can achieve additional benefits in improving quality of life and exercise tolerance in patients with CHF. These beneficial effects of SFI may correlate with its improving cardiac function. However, our findings should be interpreted with presence of significant heterogeneity and suboptimal quality of the analyzed trials.

In the realm of pathogen detection, isothermal amplification technology has emerged as a swift, precise, and sensitive alternative to conventional PCR. This paper explores the fundamental principles of recombinase polymerase amplification (RPA) and recombinase-aid amplification (RAA) and reviews the current status of integrating the CRISPR-Cas system with RPA/RAA techniques. Furthermore, this paper explores the confluence of isothermal amplification and CRISPR-Cas technology, providing a comprehensive review and enhancements of existing combined methodologies such as SHERLOCK and DETECTR. We investigate the practical applications of RPA/RAA in conjunction with CRISPR-Cas for pathogen detection, highlighting how this integrated approach significantly advances both research and clinical implementation in the field. This paper aims to provide readers with a concise understanding of the fusion of RPA/RAA and CRISPR-Cas technology, offering insights into their clinical utility, ongoing enhancements, and the promising prospects of this integrated approach in pathogen detection.

Nitrate ester binders are a unique class of energetic binders containing nitrate ester (-ONO2) pendant groups attached to the polymeric backbones, which have been extensively employed in solid propellant formulations to improve overall energy output and oxygen balance. Both polymerization of nitrate ester monomers and chemical modification of inert polymers are commonly used methods for constructing such binders. Poly(glycidyl nitrate) [PGN] and poly(3-nitratomethyl-3-methyloxetane) [PNIMMO] are well-investigated nitrate ester pre-polyethers formed by cationic ring-opening polymerization (CROP) from nitrate ester monomers, and their synthesis, properties, chemical modification and applications in solid propellants are discussed in detail. It is worth noting that PGN and PNIMMO as soft blocks can further generate energetic thermoplastic elastomers (TPEs) by polyurethane addition polymerization, which have emerged as potential energetic binder candidates for thermoplastic propellants and melt-cast explosives. Therefore, the recent advances of PGN-based TPEs and PNIMMO-based TPEs are subsequently presented. Finally, the synthesis, properties and applications in propellants of several nitrate ester-modified polymers such as cellulose-based nitrates, nitrated hydroxyl‑terminated polybutadiene (NHTPB) and polyvinyl nitrate (PVN), obtained by direct/indirect nitration of inert polymers, are briefly described.

Accurately calculating the labels of each high-resolution image is an unavoidable technique in remote sensing. In this article, we propose a novel image assortment model that personate each aerial image by optimally encoding a gaze shifting path (GSP). At the same time, wrong semantic model can get absent with it. More specifically, for each aerial image, we reference visually/semantically noticeable representational rogue interiors. To encode their analysis attributes, we mean a small graph comprise of spatially conterminous motivational wall, and extract GSPs on it by active literature algorithm rules. GSP can accurately capture humans perception over many aerial image areas when the notice senses are placed in each image. Subsequently, a double deep learning framework is proposed to intelligently exploit the semantics of these GSPs, with three attributes: label noises reduction, visual manner-unchanging semantics, and adaptive data chart updates are seamlessly integrated. The proposed framework can iteratively solved, with each graphlet re-form into a base. Finally, the GSP-compliant summaries in each aerial have shown the quantized vectors for visual understanding. To qualitatively and quantitatively assess how GSP affects information aerial image classification, we notice that the phantom copy of our progress classification is more accurate than its competitors, and the GSPs propagated by Alzheimer's patients are discriminative from those produced by typical observers, making the classification competitive.

Abstract Background Prostate cancer (PCa) is one of the most diagnosed cancers in the world. PCa inevitably progresses to castration-resistant prostate cancer (CRPC) after androgen deprivation therapy treatment, and castration-resistant state means a shorter survival time than other causes. Here we aimed to define castration-dependent and -independent diver genes and molecular pathways in CRPC which are responsible for such lethal metastatic events. Methods By employing digital gene expression (DGE) profiling, the alterations of the epididymal gene expression profile in the mature and bilateral castrated rat were explored. Then we detect and characterize the castration-dependent and -independent genes and pathways with two data set of CPRC-associated gene expression profiles publicly available on the NCBI. Results We identified 1,632 up-regulated and 816 down-regulated genes in rat’s epididymis after bilateral castration. Differential expression analysis of CRPC samples compared with the primary PCa samples was also done. In contrast to castration, we identified 97 up-regulated genes and 128 down-regulated genes that changed in both GEO dataset and DGE profile, and 120 up-regulated genes and 136 down-regulated genes changed only in CRPC, considered as CRPC-specific genes independent of castration. CRPC-specific DEGs were mainly enriched in cell proliferation, while CRPC-castration genes were associated with prostate gland development. NUSAP1 and NCAPG were identified as key genes, which might be promising biomarkers of the diagnosis and prognosis of CRPC. Conclusion Our study will provide insights into gene regulation of CRPC dependent or independent of castration and will improve understandings of CRPC development and progression.

Metaverse has rekindled human beings’ desire to further break space-time barriers by fusing the virtual and real worlds. However, security and privacy threats hinder us from building a utopia. A metaverse embraces various techniques, while at the same time inheriting their pitfalls and thus exposing large attack surfaces. Blockchain, proposed in 2008, was regarded as a key building block of metaverses. it enables transparent and trusted computing environments using tamper-resistant decentralized ledgers. Currently, blockchain supports Decentralized Finance (DeFi) and Non-fungible Tokens (NFT) for metaverses. However, the power of a blockchain has not been sufficiently exploited. In this article, we propose a novel trustless architecture of blockchain-enabled metaverse, aiming to provide efficient resource integration and allocation by consolidating hardware and software components. To realize our design objectives, we provide an On-Demand Trusted Computing Environment (OTCE) technique based on local trust evaluation. Specifically, the architecture adopts a hypergraph to represent a metaverse, in which each hyperedge links a group of users with certain relationship. Then the trust level of each user group can be evaluated based on graph analytics techniques. Based on the trust value, each group can determine its security plan on demand, free from interference by irrelevant nodes. Besides, OTCEs enable large-scale and flexible application environments (sandboxes) while preserving a strong security guarantee.

ObjectiveTo investigate the epidemiology and influencing factors of social participation ability of rural older adults in China.MethodsFrom March to April 2021, 3450 older adults in poverty aged 60 and above registered in Jishishan County (J County) were selected by cluster sampling for a cross-sectional questionnaire survey and their social participation ability was assessed using the Ability Assessment of older adults (MZ/T039-2013). The results were statistically analyzed and an ordered multi-category logistic regression analysis was used to analyze the effect of influencing factors on the social participation ability of rural older adults.Results3,346 questionnaires were collected, with an effective recovery rate of 96.99%. Out of all the participants, 1,355 (40.5%) of the 3,346 cases had intact social participation ability, while 1,991 (59.5%) had different degrees of loss of social participation ability, of which 1,393 (41.14%) were mildly impaired, 419 (12.5%) were moderately impaired and 179 (5.3%) were severely impaired. Age, educational level, religious belief, living status, whether suffering from dementia and the occurrence of accidents in recent 30 days were influencing factors on the social participation ability (p < 0.05).ConclusionThe rate of impaired social participation ability among older adults was >50% and age, educational level, religious beliefs, living status, whether suffering from dementia, and the occurrence of accidents in recent 30 days (such as falls, choking, loss) were significant factors influencing the ability of social participation of rural older adults.

The key technology and method of RV Reducer digital design by using C# language and SolidWorks secondary development technology are introduced. Through in-depth study of the parameterization process of the RV reducer， the digitization process from the input of the overall target parameters to the specific parameters of the parts is realized. A CAD system platform for RV reducer parameter optimization design is developed， and combined with the database， the management of part parameters is realized.

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.

Industrial wastewater contains diverse toxic dyes and drugs, which pollute the environment and poison creatures. Utilizing photocatalysts has been accepted to be an effective method to degrade water pollutions using solar light. Crystalline bismuth ferrite (Bi2Fe4O9) with a band gap of 1.9–2.0 eV is expected to be one of the most promising candidates for photocatalysts in the visible light region. Amorphous graphene is also a promising candidate as a photocatalyst owing to its excellent electronic and optical properties. Herein, a composite of Bi2Fe4O9/graphene aerogels (GAs) was prepared with a two-step hydrothermal method. The prepared Bi2Fe4O9 powders were confirmed to be successfully doped into GAs and evenly dispersed between graphene sheets. The Bi2Fe4O9/GA composite was utilized to perform photodegradation for organic dyes and antibiotic drugs under visible light irradiation, yielding efficiencies of 90.22%, 92.3%, 71.8% and 78.58% within 330 min for methyl orange, methylene blue, Rhodamine B and tetracycline hydrochloride, respectively. Such distinct photocatalytic activities overwhelmed the pure Bi2Fe4O9 powders of 14.10%, 22.19%, 13.98% and 48.08%, respectively. Additionally, the composite produced a degradation rate constant of 0.00623 min−1 for methylene blue, which is significantly faster than that of 0.00073 min−1 obtained by the pure powder. These results provide an innovative strategy for designing 3D visible-light-responsive photocatalysts combined with graphene aerogel for water purification.

Potassium chloride crystals are good conductors in the UV to mid-infrared broadband and can be widely used as materials for high-power CO2 lasers. However, the most important use of potassium chloride crystals has been overlooked; their stable chemistry and wide electrochemical window allow them to form molten eutectic salts with other chlorides for the dry reprocessing of spent fuel. The aim of this work is to investigate the electrochemical properties of the actinide substitute cerium metal on liquid indium media in order to provide basic data for further realization of lanthanides (Ln)/actinides (An) separation. In this paper, we investigated the electrochemical behavior of 3LiCl-2KCl-CeCl3 melt at liquid metal media indium (In) electrode using various transient electrochemical analysis methods, such as cyclic voltammetry, square wave voltammetry and open circuit potential technique. The quasi-equilibrium potentials of Ce3+ at different temperatures on the liquid metal In electrode were determined. On the redox process, the reaction kinetics of the oxidation–reduction process in the 3LiCl-2KCl-CeCl3 system is studied. It was determined that the reduction of Ce3+ at the liquid metal In electrode is an irreversible single-step process with three electron transfers. The relationship between the diffusion coefficient and the reduction process of Ce3+ ions on liquid metal indium electrodes at different temperatures was determined. The expression for the diffusion coefficient and temperature of Ce3+ at the liquid metal indium electrode is: lnD = 1.43 − 7974.69/T.

To evaluate the applicability of desert dark septate endophytes (DSEs) in crop cultivation, Alternaria alternata (Fr.) Keissl. (Aa), Paraphoma pye Moslemi & P.W.J. Taylor (Pp), and Paraphoma radicina (McAlpine) Morgan-Jones & J.F. White (Pr) were inoculated into nonhost wheat growing under three water conditions. The plants’ biomass, vegetative growth, and physiological parameters were investigated. At harvest, all DSE strains were effective colonizers under all treatments. These DSEs generally positively affected wheat growth but varied among different DSE species, and this promoting effect was more obvious under drought conditions. Under mild drought (MD) treatments, Aa and Pr increased the leaf number and plant height of hosts. Pr showed a significant beneficial influence on the wheat’s total biomass under all treatments, while Aa and Pp showed benefits only under the well-watered or MD treatment. The response mechanisms of DSE-inoculated wheat under stress may be due to the enhanced photosynthetic efficiency and antioxidant system. Generally, Pr had a stronger beneficial effect. The improved growth and fitness of the inoculated hosts under drought stress may reduce their water supply requirements during seedling growth. We speculate that inoculating wheat with this strain could be a promising approach for water-saving cultivation in arid environments.

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.

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.

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.

Research on regional residential buildings is an important means of exploring the natural climatic adaptability of buildings and the sustainable development of culture. It is also an important path of sustainable social development. However, current research methods for architectural space find it difficult to clarify the internal and external relations of space, and the function of architectural space to adapt to the regional climate and cultural heritage is difficult to quantitatively analyze and measure. This study constructs a new research method of architectural interiors/exteriors, takes the traditional residential buildings in Wu-style architecture in the Jinhua area as a case study, summarizes the types and characteristics of the interiors/exteriors of Wu-style architecture, and reveals the spatial construction rules of the internal and external types realizing environmental sustainability and traditional residences. The results show that: (1) the architecture of the Wu style has five typical types of interior/exterior, and the regional representation of its interior/exterior is affected by both the human and the natural environment; (2) influenced by traditional Confucian culture, the architecture of the Wu style shows a central axial secondary buckling type and an enclosed type of interior/exterior form, which has the value of the times to coordinate the relationship between people in today’s society; (3) in terms of ventilation, daylighting, and heat dissipation, Wu-style buildings flexibly use the slender gray space form and wide cornice for the internal and external space transition, which effectively improves the ecological efficiency of the buildings’ ventilation, lighting, heat dissipation, etc., and has important reference value for the development and utilization of traditional buildings and the architectural design of new dwellings. At present, this new research method for the internal and external spaces of buildings still has considerable potential and needs to be deepened and improved through further research.

In the present paper, we establish two Erdélyi-type integrals for Saran’s hypergeometric function FK, 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.

Recently, a novel gray image encryption scheme was proposed based on 2D Henon-Sine map (2D-HSM) and DNA approach. In the original scheme, the image pixels are substituted and diffused by the DNA approach and then permutated by a 2D-HSM key sequence. The structure of the encryption scheme is equivalent to substitution-diffusion-permutation. However, it is found that the attacker can recover the encrypted image by using the chosen plaintext attack without the secret keys. First, the equivalent key matrix used for permutation of the encryption scheme can be obtained, and the effects of diffusion can also be eliminated by the proposed method. Then, the mapping matrix between the input plaintext image and the intermediate image encrypted by the DNA approach is obtained. Both theoretical analysis and the experimental results show that the encrypted images using the original scheme can be cracked successfully. The attack complexity of our scheme is O(18), which greatly reduces the number of attacks compared with the traditional method. In addition, our approach will help to improve the security of image-encryption schemes based on permutation-diffusion-scrambling structures.

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.

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.

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.

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.

Africa has been experiencing a rapid urbanization process, which may lead to an increase in unsustainable land use and urban poverty. Assessing the spatiotemporal characteristics of urbanization dynamics is especially important and needed for the sustainable development of Africa. Satellite-based nighttime light (NTL) data are widely used to monitor the dynamics of urban growth from global to local scales. In this study, urban growth patterns across Africa were analyzed and discussed using stable nighttime light datasets obtained from DMSP/OLS (the Defense Meteorological Satellite Program’s Operational Line-scan System) spanning from 1992 to 2013. We partitioned the nighttime lighting areas into three types (low, medium, and high) using thresholds derived from the Brightness Gradient (BG) method. Our results indicated that built-up areas in Africa have increased rapidly, particularly those areas with low nighttime lighting types. Countries with higher urbanization levels in Africa, like South Africa, Algeria, Egypt, Nigeria, and Libya, were leading the brightening trend. The distribution of nighttime lighting types was consistent with the characteristics of urban development, with high nighttime lighting types showed up at the urban center, whereas medium and low nighttime lighting types appeared in the urban-rural transition zone and rural areas respectively. The impacts of these findings on the future of African cities will be further proposed.