A novel multifunctional isocyanate curing agent, denoted as TCI, was facilely synthesized via a one-step reaction involving 1,3,5-tris(2-hydroxyethyl)cyanuric acid and hexamethylene diisocyanate. The structural design of TCI incorporates a rigid triazine ring core and three additional urethane linkages, enabling the construction of high-performance crosslinked networks within glycidyl azide polymer (GAP)-based energetic elastomers. By systematically comparing TCI with the commercially available curing agent N100, the structure–property relationships were elucidated through a combination of curing kinetics, spectroscopic characterization, mechanical testing, and thermal analysis. TCI exhibits superior reactivity toward GAP, effectively compensating for the low reactivity of secondary hydroxyl groups. Structural characterization via XRD, SAXS, and FTIR demonstrated that TCI facilitates the formation of dense and stable hydrogen-bonding networks, which reduce the intermolecular chain spacing (0.424 nm for TCI–GAP vs. 0.436 nm for N100–GAP) and optimize the microphase separation behavior of the elastomer networks.Mechanical testing demonstrated that the tensile strength and elongation at break of TCI–GAP reach 1.74 MPa and 297.7%, respectively, representing increases of 95.5% and 163% over N100–GAP (0.85 MPa and 105.8%). Morphological analysis confirmed the presence of uniformly distributed crosslinking junctions and ductile fracture features in TCI–GAP, which are responsible for the improved load-bearing capacity and energy dissipation efficiency. Dynamic hydrogen-bonding interactions were identified as the key mechanism governing the mechanical and thermal performance of TCI-GAP. DMA and LF-NMR results indicated that TCI–GAP possesses higher storage modulus and more restricted segmental motion, leading to excellent thermomechanical stability. The novel TCI curing agent offers a facile and effective approach to simultaneously improve the mechanical strength, toughness, and thermal stability of GAP-based networks, showing great promise for applications in advanced solid propellants and energetic materials.

The thermal decomposition performance of ammonium perchlorate (AP) in solid propellants directly affects the energy output and combustion efficiency of propulsion systems. However, its relatively high decomposition temperature and dispersed exothermic behavior limit its practical application. In this work, a CeO2/Co3O4-based catalyst with a three-dimensionally ordered macroporous (3DOM) structure was constructed and evaluated for the thermal decomposition of AP. Using the template assisted method, 3DOM CeO2/xCo3O4 (3DCe/xCo) catalysts with tunable Co2+/Ce3+ ratios were prepared and their catalytic behaviors toward AP decomposition were systematically investigated. Among them, 3DCe/0.9Co exhibited the best catalytic activity, lowering the high temperature decomposition temperature of AP by about 30% and markedly reducing the activation energy. Structural characterization, UV-vis DRS, VB-XPS, TG-IR, TG-MS, in situ XPS, and DFT calculations indicate that electron transfer from Co3O4 to CeO2 generates a built-in electric field and oxygen vacancies, which promote side-selective adsorption and activation of NH3 and HClO4. The interconnected 3DOM framework also facilitates mass transport and conversion of AP intermediates, and finally merges the two decomposition peaks of AP into a single exothermic peak. This work provides additional insight into the role of interfacial charge transfer and 3DOM CeO2/Co3O4 catalysts for AP thermal decomposition.

Burning rate suppressants are essential for regulating the burning rate of solid propellants. The regulation mechanism of Gemini quaternary ammonium perchlorate salt (GQAPS) on the combustion performance of ternary hydroxyl-terminated polybutadiene (HTPB) propellants was investigated. The propellant's. burning rate was reduced to 5.47 mm s-1 at 7 MPa by adding 1 wt% GQAPS, indicating a superior burning rate inhibition efficiency of GQAPS. By constructing AP/GQAPS composites and analyzing their thermal decomposition properties, it was found adding 1 wt% GQAPS increased the activation energies of ammonium perchlorate (AP) during its low- and high-temperature decomposition stages by 11.86 kJ mol- 1 and 104.17 kJ mol- 1, respectively, and reduced the heat release during AP's high-temperature decomposition by 43.75 J g-1. TG-FTIR analysis showed that the infrared absorption peaks associated with GQAPS decomposition products disappeared. Moreover, the maximum absorption intensity ratio of NO2 to N2O in AP/GQAPS composites decreased by 52.2 % compared to pure AP. These results demonstrated that GQAPS decomposition products competitively consumed reactive oxygen species generated during AP decomposition, thereby altering the oxidation pathway of NH3 and synergistically inhibiting AP decomposition. However, excessive GQAPS diminished the inhibitory effect due to its inherent exothermic decomposition properties.

To address the challenges of weak early-stage loosening fault signals and strong environmental noise interference in escalator drive mainframe anchor bolts, which hinder effective fault feature extraction, this paper proposes an improved Residual Convolutional Denoising Autoencoder (RCDAE) for signal denoising in high-intensity noise environments. The model combines DMS (Dynamically Multimodal Synergistic) loss function, the gated residual mechanism, and CNN–Transformer. The experimental results demonstrate that the proposed model achieves an average accuracy of 93.88% under noise intensities ranging from 10 dB to −10 dB, representing a 2.65% improvement over the baseline model without the improved RCDAE (91.23%). At the same time, in order to verify the generalization performance of the model, the CWRU bearing data set is used to conduct experiments under the same conditions. The experimental results show that the accuracy of the proposed model is 1.30% higher than that of the baseline model without improved RCDAE, validating the method’s significant advantages in noise suppression and feature representation. This study provides an effective solution for loosening fault diagnosis of escalator drive mainframe anchor bolts.

In the development of solid propellants, the inherent brittleness and high glass transition temperature (T-g) of poly (dicyclopentadiene) (PDCPD) pose significant challenges for achieving the desired high strength, ductility, and low T-g properties in binders. Poly (dicyclopentadiene) (PDCPD)-based composites using alpha-pinene as a polymeric plasticizer, is synthesized as a novel binder for solid propellants requiring high strength, ductility, and low T-g. Through frontal ring-opening metathesis polymerization (FROMP), PDCPD/alpha-pinene (PDA) blends were fabricated with alpha-pinene (5-50 mol%) acting as a physical plasticizer rather than a comonomer, overcoming its kinetic limitations in copolymerization. The incorporation of alpha-pinene significantly altered material properties, demonstrating an inverse correlation between alpha-pinene content and tensile strength (38.3-0.57 MPa) alongside a positive concentration dependence on elongation at break (91-556 %), while systematically reducing T-g from 160 degrees C to 27-94 degrees C. Dynamic mechanical analysis and tensile testing revealed maintained crosslinking density (12-21 repeat units between crosslinks) despite enhanced ductility, mainly attributed to alpha-pinene's free volume modulation within the polymer network rather than chain scission mechanisms. Rheological and thermal analyses showed alpha-pinene's dual role as an effective FROMP inhibitor, extending resin pot life (6-45 min) through reduced reaction heat release (299-381 W g(-1)) while enabling complete polymerization (>95 % conversion) via controlled frontal propagation. Thermal gravimetric analysis confirmed the composite's stability with three-stage degradation profiles, correlating alpha-pinene volatilization (100-305 degrees C) with theoretical content (2-40 % mass loss) and preserving PDCPD's crosslinked network integrity until structural carbonization (415-600 degrees C). The counterintuitive synergy between retained crosslinking and plasticization effects establishes alpha-pinene-modified PDCPD as a promising candidate for advanced propellant systems requiring tunable thermomechanical properties.

The low immunogenicity and immune escape are bottlenecks for effective hepatocellular carcinoma (HCC) immunotherapy. We prepared and characterized a dual-target liposome complex, XA5508, by encapsulating the STING agonist cGAMP in liposomes and conjugating an anti-PD-L1 nanobody to the liposome surface. The anti-tumor effect and pharmacological mechanism of XA5508 were investigated using an in situ HCC mouse model. XA5508 can effectively inhibit in situ HCC with the characteristics of tumor-targeted delivery and sustained release of STING agonist cGAMP. The pharmacological mechanism study indicates that XA5508 activates the STING signaling pathway, increases the cytotoxicity of CD8+ T cells, reverses the immunosuppressive tumor microenvironment (TME) represented by M2-type macrophages, and transforms cold tumors into hot tumors. On the other hand, cGAMP induces the upregulation of PD-L1 expression in HCC, enhances the response of anti-PD-L1 nanobody (Nb) and the escape blockade of immune checkpoint PD-1/PD-L1. XA5508 shows remarkable anti-tumor effects of STING agonist and anti-PD-L1 nanobody against HCC, providing an innovative strategy for the development of new drugs for HCC.

The formation of a burning rate gradient in gun propellant by flame-retardant treatment is one of the effective methods to achieve progressive combustion and thus improve the energy utilization efficiency. In order to reveal the effect of octa-(perfluorodecyl)-type polyhedral oligomeric silsesquioxanes (FPS-POSS) on the combustion performance of gun propellants, seven-perforated granular mixed nitrate ester gun propellants containing FPS-POSS of 0, 0.5, 1.0, and 1.5 wt % were prepared by the traditional semisolvent method. The chemical compatibility of FPS-POSS with the gun propellant components, the thermal decomposition properties, and the combustion characteristics of the gun propellants containing FPS-POSS were systematically investigated. The results show that FPS-POSS is well compatible with the components of the mixed nitrate ester gun propellant and does not affect the thermal stability of gun propellant but also reduces the residual weight of the gun propellant after thermal decomposition. Additionally, FPS-POSS can reduce the maximum burning pressure (P m) and burning rate (u) of the system and prolong the burning time (t m) for gun propellants to reach the maximum pressure, and this effect tends to increase with the increase of its content. There are two reasons for this. First, FPS-POSS has a lower chemical energy than energy-rich components such as nitrocellulose and nitroglycerin, and its addition to the gun propellant can affect the burning rate at the energy level. The second is that FPS-POSS not only traps reactive radicals in the gas phase by generating fluorine-containing radicals during combustion but also generates porous carbonaceous layer in the condensed phase to hinder the propagation of flames and gaseous products. It suggests that FPS-POSS is an excellent additive in the low burning rate region of gun propellants. When the content of FPS-POSS was 1.5 wt %, FPS-POSS decreased the P m of the system by 1.83%, increased the tm by 7.57%, and reduced the burning rate by 9.81%. High- and low-temperature experiments showed that FPS-POSS was favorable for reducing the temperature coefficients of gun propellants.

The purpose of this study is to discuss the design of escalator fault prediction and intelligent maintenance system based on machine learning. By using machine learning, fault diagnosis, process monitoring and human action recognition, an innovative escalator fault prediction and intelligent maintenance system is proposed to improve the operation efficiency and safety of escalators. The machine learning method is used to learn the operation data of the escalator through the training model, so as to realize the prediction of the operating state of the escalator and the fault diagnosis. The fault diagnosis method is applied to realize the early detection and diagnosis of the fault by analyzing the running data of the escalator. Process monitoring the operation data of the escalator to realize real-time monitoring of the operation process of the escalator. At last, using the method of human movement recognition, timely judgment provides an effective solution for fault prediction and intelligent maintenance of escalators.

The sea cucumber intestine (SI), a secondary product from sea cucumber processing, contains polysaccharides as one of its active ingredients, and fermentation is an effective method for extracting bioactive substances from food by-products. In this study, to explore the effect of Enterococcus hirae GS22 fermentation on the extraction of SI polysaccharides, the polysaccharides were extracted through the SI with and without Enterococcus hirae GS22 fermentation, and the obtained polysaccharides were designated as SC-PF and SC-P. The extraction yield, the structural characteristics, and the biological functions of the polysaccharides were then evaluated. The results indicated that Enterococcus hirae GS22 could grow well using SI as the substrate and that fermentation could improve the extraction yield of the polysaccharide from 0.48% to 0.63%, decrease the molecular weight (Mw), and change the monosaccharide composition. The diameter of SC-PF was smaller than SC-P, and the absolute value of the zeta potential of SC-PF was found to be lower than SC-P. Fermentation does not change the functional group or the thermal ability of the polysaccharide. SC-PF had better antioxidant ability than SC-P; the DPPH and superoxide anion scavenging ability were 96.3% and 36.5%, respectively. SC-PF also showed nearly 1.3- and 1.1-fold higher inhibition of α-glucosidase and α-amylase as compared to SC-P. The current results showed that E. hirae GS22 fermentation has the potential to extract SI polysaccharides with better prebiotic abilities.

Glycidyl azide polymer (GAP)-based polyurethane is an ideal elastomeric matrix for high-energy, low-smoke, and insensitive solid propellants. As the skeleton structure of GAP propellants, changes in the structure and properties of GAP elastomers during aging lead to the deterioration of propellant performance (especially in relation to mechanical properties), which causes safety risks. A high-temperature-accelerated aging experiment (70 °C) on a GAP elastomer was conducted. The evolution of the microstructure of the GAP elastomer system was analyzed by Fourier-transform infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (NMR), and variations in the macroscopic properties were analyzed by the hardness test and the uniaxial tensile test. The experimental results showed that thermal aging of the GAP elastomer is a coupled process of multiple chemical reactions. The azide groups, urethane groups, and ether bonds were the weak links in the network structure, breaking during the aging process, and the crosslinking density rose and then decreased. Macroscopic properties also showed segmented changes. The aging process was divided into three stages: post-curing (stage one); when the crosslinked network began to break (stage two), and when the crosslinked network was destroyed (stage three). Changes in the microstructure and macroscopic properties were consistent. This work is of great significance for exploring the aging mechanism of GAP propellants and extending their storage life.

Exopolysaccharides (EPSs) secreted by lactic acid bacteria have the potential to enhance human health by showing various biological functions. This study investigated the biological role and antibiofilm properties of EPS715, a new neutral EPS produced by pickled vegetables originating from Lactobacillus plantarum PC715. The results indicate that EPS715 is primarily composed of rhamnose, glucose, and mannose. Its molecular weight (Mw) is 47.87 kDa, containing an α-glucoside linkage and an α-pyranose ring. It showed an amorphous morphology without a triple helix structure. Furthermore, EPS715 showed improved antioxidant activity. Specifically, its scavenging capacity of ABTS+ radicals, DPPH radicals, and the hydroxyl (·OH) reduction capacity at 5 mg/mL was 98.64 ± 2.70%, 97.37 ± 0.79%, and 1.64 ± 0.05%, respectively. Its maximal scavenging capacity was >40%, and the hydroxyl (·OH) radical scavenging ability was dose-dependent. Moreover, the biofilm of various pathogens including S. aureus, B. cereus, S. saprophyticus, Acinetobacter spp., and H. alvei was substantially dispersed and affected by EPS715, with a maximum inhibition rate of 78.17% for H. alvei. The possible mechanism by which EPS715 shows antibiofilm properties against the H. alvei may be attributed to its effects on the auto-aggregation, hydrophilic characteristics, and motility of Hafnia spp. Thus, EPS715 has significant antioxidant and antibiofilm characteristics that may hold substantial potential for applications in food and medicinal products.

In the rapid development of social economy and science and technology, Chinese public transportation and large-scale shopping malls, stations, airports in the construction promotion, start to use escalator in a large number, as a transportation vehicle of the new era construction development, although it has solved the problems of the human flow of the traditional urban construction and development, but also a lot of safety accidents have emerged. According to the practice investigation and research, there are many types of escalator safety accidents at home and abroad, which are reflected in the safety protection device, synchronous safety, brake safety and other aspects, which directly endanger people's life, property and health. Therefore, on the basis of understanding the theoretical research status of escalator technology, and according to the overall design of automatic safety performance detection of escalator, we propose an escalator braking performance test method, and then mainly study the safety and reliability of escalator equipment, in order to provide an effective basis for the construction and development of a new era.

In the rapid development of social economy, people's quality of life is getting higher and higher, elevator as one of the essential means of transportation in daily life, how to ensure the safety and stability of elevator equipment operation, has become the main issue of research and discussion. Since the sensors in the elevator can collect a large amount of data information, which can provide effective basis for the study of the operating state of the elevator equipment, scientific researchers propose to use big data technology to optimize the elevator safety detection and management, build a sound management system and monitoring methods, and solve the elevator safety failures and abnormal situations as soon as possible. In this paper, on the basis of understanding the research status of elevator safety detection management, according to the theory of big data technology, put forward the elevator safety detection management system with big data as the core, and combined with practical cases for verification and analysis. The final results show that the application of big data technology in elevator safety detection management is very important.

An aromatic copolyester liquid crystal polymer (LCP) was introduced into carbon-fiber-reinforced polyamide–polyurethane (CF/PA-PU) composites through melt blending to improve the tribological properties of the composites. The effects of LCP on the mechanical, processing, and thermal properties of CF/PA-PU composites were compared to those of commonly-used graphite (Gr). The results showed that at 5 wt.% LCP content, the coefficient of friction (COF) was decreased by 16.06%, and the wear rate by 32.22% in the LCP/CF/PA-PU composite compared to the CF/PA-PU composite. Furthermore, using LCP instead of Gr showed significantly improved mechanical properties and reduced processing viscosity. The tensile strength of 5%LCP/CF/PA-PU composite could reach 99.08 MPa, while the equilibrium torque was reduced, being 26.85% higher and 18.37% lower than those of CF/PA-PU composite, respectively. The thermal stability of LCP/CF/PA-PU composites was also enhanced. The addition of 5 wt.% LCP to CF/PA-PU composite increased the initial decomposition temperature by 14.19% compared to CF/PA-PU. In sharp contrast, the addition of Gr increased equilibrium torque and actual processing temperature leading to processing difficulties and instability. This approach offers a novel strategy for tribological applications and tackles the problem of high viscosity in CF/PA-PU composites.

《高分子物理》是高分子材料专业的一门专业基础课程,在学生思维能力提升、专业知识掌握、实践水平提高等方面都发挥着重要的作用.互联网时代下,应充分发挥线上教学的优势,并遵从"以学生为主、产出导向"的OBE教学理念,实现线上教学与线下教学的紧密结合,构建基于MOOC的《高分子物理》线上线下混合教学模式.本文以"高分子的分子运动"为例,系统阐述由"课前自学-线下教学-课后复习巩固"三个阶段组成的线上线下混合教学模式,并以教学目标达成度、学生问卷调查等分析了学习效果,结果表明,混合教学模式可提高学生的学习兴趣,提升学生的学习动力,教学效果优良.

Covalent functionalization of black phosphorus nanosheets (PNs) exhibit relatively stability, but one unpaired electron still retains in the phosphorus atom, rendering unsaturated coordination state and hampering the passivation effect. Azide functionalization achieves the five-coordinate bonding of phosphorus atoms, making PNs completely passivated. But a molecule with an azide group is extremely dangerous owing to explosive and corrosive nature. Herein, insensitive glycidyl azide polymer, GAP, was the first used for covalent azide functionalization of PNs to generate GAP-PN of P=N bond with the best stability. The structure of GAP-PN was comprehensively confirmed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), the atomic force microscopy (AFM), Raman spectra, solid-state 31P nuclear magnetic resonance spectroscopy (31P NMR), x-ray photoelectron spectroscopy (XPS) and the elemental analysis. The average statistical size and the thickness of GAP-PN is 2.46 ± 1.51um and10.4 nm.The stabilization mechanism was explored via XPS, and the mechanism was attributed to the chemical modification of the surface of PNs with P=N bond formation, which inhibits the formation of PxOy. The stability properties of GAP-PN were evaluated by XPS and the UV/Vis spectroscopic. The experimental results show that the degradation ratio of GAP-PN decreased from 54.9 to 8.8% of PNs after 60 days. In addition, compared with PNs, the peak temperature corresponding to exothermic phase(TP) of GAP-PN decrease by 44.6 °C and heat released during the decomposition for GAP-PN is up to is 3154.9 J/g, which is 6.09 times higher than that of PNs. This work provides a novel strategy for the stability study of PNs, which is supposed to possess significant potential in the nanocomposite energetic materials applications field.

Carbon fiber reinforced polyether ether ketone (PEEK/CF) composites feature diverse advantages and have been applied in various fields. However, the high melt viscosity of PEEK leads to their poor processing performance and affects their practical applications. Here a liquid crystal polymer (LCP) was introduced into a PEEK/CF system as a new strategy to address the aforementioned issues. Bearing aromatic rings on the main chains, LCP can strongly interact with PEEK by pi-pi interaction, which alters the crystallization behaviour and facilitates processing of PEEK/CF, eventually improving its mechanical performance. As a result, a high crystallinity (37.37%), a decreased equilibrium torque (8.902 Nm), and a high tensile strength (230.97 MPa) are realized with 5 wt% LCP. The current approach offers a new solution to simultaneously promote processing and mechanical performance of PEEK/CF and other polymer-based composites.

Recently, graphitic carbon nitride (g-C3N4) has attracted considerable attention due to its attractive features including excellent electrochemical performance, suitable band gap, nontoxicity, and high mechanical and thermal stability. Such unique advantages endow it with promising applications in batteries, photocatalysts, photodegradation, and so on. In particular, it has been applied to catalyze the thermal decomposition of ammonium perchlorate (AP) and has shown excellent performance. In this review, the structure, preparation methods and exfoliation strategies of g-C3N4 are comprehensively introduced. Furthermore, the enhanced catalytic mechanism for the thermal decomposition of AP is discussed in detail, and a future research direction is also proposed.

The thermal oxidation etching assisted g-C3N4 nanosheets/CuO was prepared through a facile co-precipitation strategy. In this work, the structure, morphology, and composition of g-C3N4 (UCN, prepared by urea), g-C3N4 nanosheets (TCN, prepared by thermal oxidation etching of UCN), g-C3N4/CuO (UCN/CuO), g-C3N4 nanosheets/CuO (TCN/CuO) were characterized via X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). Furthermore, the catalytic effect of the obtained samples on the thermal decomposition of ammonium perchlorate (AP) was examined by thermal gravimetric analysis (TGA). As a result, in the case of 5 wt% TCN/CuO, the high decomposition temperature of AP decreased by 120.6 degrees C, which is much lower than that of UCN, TCN, CuO and UCN/CuO. In addition, the exothermic heat released from the decomposition of AP increased from 430.64 J g(-1) to 2856.08 J g(-1). This evident catalytic activity may be related to the synergistic effect of CuO and TCN. This work provides a novel strategy for the construction of composite catalyst for the thermal decomposition of AP, which is supposed to possess significant potential in the solid propellant field.

A series of self-matting waterborne polyurethanes (WPUs) were successfully prepared by introducing hydrophilic units into both soft and hard segments. By employing a polycaprolactone polyol containing carboxylate groups within the polymer chains to provide hydrophilicity directly, the matting performance of WPU films was greatly improved. The chemical structures of the WPU resins were confirmed by FTIR spectroscopy, and the morphology of WPU films was observed by SEM. The parameters of WPU preparation were investigated in detail. It was found that the surface gloss of WPU films as well as the particle sizes of WPU dispersions were closely associated with the content of hydrophilic units. As the content of carboxylates or sulfonates increased, the particle sizes of WPU decreased, while the gloss increased gradually. When the particle sizes of dispersions were greater than 3 μm, the gloss of WPU films coated on a leather surface was lower than 1. The results of TG showed that, the initial decomposition temperatures of WPU films were higher than 280 °C, which indicated these films also had good thermal stability. The prepared self-matting WPU coatings would have potential application prospects in the field of leather finishing.