Hydrogen-abundant ultrahigh molecular weight polyethylene (UHMWPE) is widely used for nuclear shielding purposes, but its low thermal conductivity (lambda) and high flammability pose a potential risk for the safe operation of nuclear units. Herein, a series of UHMWPE-based composites were prepared by loading hybrid flame-retardants consisting of ammonium polyphosphate (APP), dipentaerythritol (DPER), hindered amine flame retardant (Flamestab (R) NOR116), and nano-zirconium phosphate (ZrP). With the addition of 18.88 wt% flame retardant, the material achieves an LOI of 40% which meets the UL-94 V-0 standard. The improved fire resistance performance was also corroborated by cone calorimetry and TGA-FTIR analysis. To further enhance the heat dissipation capability, 5 wt% graphite (Gt) was introduced into the above UHNMWPE-based composite which resulted in a remarkable increase of lambda from 0.74 to 3.73 W/mK while maintaining excellent flame retardancy (LOI=39%, UL-94 V-0). Both Geant4 simulation and 60Co radiation tests demonstrated that thermally conductive and flame retardant UHMWPE-based composites maintained excellent shielding performance. This work offers a facile approach to developing UHMWPE-based shielding materials with integrated flame resistance, high lambda, and nuclear radiation protection that demonstrates promising application in nuclear sectors.

In this study, Eurotium cristatum was used for the solid-state fermentation of Angelica dahurica, and the dynamic changes in metabolites during fermentation were investigated. The results showed that fermentation markedly altered the volatile metabolite profile, increasing the relative abundance of terpenoids while decreasing that of alcohols and aldehydes. In combination with principal component analysis (PCA), 24 key volatile compounds were screened. Liquid chromatography-mass spectrometry (LC-MS)-based untargeted metabolomics identified 892 differential annotated non-volatile metabolites and temporal clustering analysis was further applied to characterize their changes. The results showed metabolic fluctuations occurred during the initiation and early fermentation stages, during which carbohydrates and nucleotides were consumed. Secondary metabolites accumulated in the early and middle fermentation. Lipid compounds overall increased in the early fermentation but declined in the middle and late fermentation. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis identified 12 key metabolic pathways. This work systematically reveals the change pattern of the metabolite composition of A. dahurica driven by E. cristatum solid-state fermentation, providing a scientific basis for quality improvement and mechanistic studies of fermented A. dahurica products.

In the present work, Eurotium cristatum fermentation was applicated in Penthorum chinense Pursh (PCP) leaf tea production, to reduce the bitterness, astringent tastes and pronounced herbaceous flavor of PCP leaves. Based on the results of single-factor experiments and response surface methodology (RSM) according to sensory evaluation, the optimal fermentation conditions were determined as follows: water contents 27%, incubation amount 21%, with 16 days of incubation time. The E. cristatum fermented PCP leaf tea produced in the optimal condition had orange-yellow infusion appearance with abundant E. cristatum colonization, tasting smooth and mellow with harmonious aroma, which achieved the sensory score at 91.60, while the total polyphenols and total flavonoids contents were reduced by 16.95% and 18.70%, respectively. Compared with the unfermented samples, the ratio of bitter and sweet amino acids of fermented PCP leaf tea decreased by 7.16%. The results of HS-SPME-GC-MS showed that the undesirable volatile components (VOCs), including hexanal, trans-2-hexenal, (E,E)-2,4-heptadienal, and 6-methyl-5-hepten-2-one representing grassy, pungent, and irritating odors, remarkably decreased, and the VOCs associated with floral, fruity, and fungal aromas, including acetophenone, linalool, and 2-butanone were newly generated and increased in PCP leave tea after fermentation. In summary, the optimal E. cristatum fermentation was confirmed to significantly improve the sensory quality of PCP leaf tea, especially eliminating the undesirable flavors and tastes, which could be a promising technology applicated in PCP tea process.

Phenolic resin (PR) has been widely used in ablative thermal protection systems for aerospace applications, but improving its thermo-oxidative and ablation resistance remains challenging. PR hybrid resin with excellent thermal-oxidative resistance was designed through introducing carborane (CB) into the cross-linked network structure of PR. CB hybrid phenolic resin (CBPR) displayed an impressive heat resistance and carbonization, the initial thermal decomposition temperature (T5 %) and weight residue at 800 degrees C (R800 degrees C) of CBPR0.4 in N2 were 566.3 degrees C and 85.45 %, and those were 494.5 degrees C and 79.74 % in air. It was related to the fact that CB could consume free radicals, inhibit cross-linking network destruction, promote organic-inorganic hybrid structures generation and slow down decomposition rate. Meanwhile, PR hybrid resin possessed outstanding oxyacetylene ablation performance, the linear ablation rate (LAR) and mass ablation rate (MAR) were only 0.0015 mm/s and 0.0375 g/s due to in-situ ceramicization and graphitization during ablation, which were reduced by 98.26 % and 71.88 %. The results of this study would provide some inspirations for the development of high-performance thermally protective materials in the future.

Although the influence of raw material composition on soy sauce koji fermentation is well recognized, the differences in microbial succession and metabolic pathways between whole soybean koji (WSK) and defatted soybean–wheat bran koji (DSK) remain unclear. In this study, a multi-omics approach integrating absolute quantitative PCR and physicochemical analyses was employed to elucidate the mechanisms by which DSK enhances the quality of Deyang Baiwo soy sauce. Compared with WSK, DSK exhibited lower moisture content but higher total acidity, amino nitrogen, and reducing sugar levels, indicating its suitability for high-quality soy sauce production. Volatile analysis revealed greater accumulation of key aroma compounds such as 2-methoxy-4-vinylphenol and 4-vinylguaiacol in DSK, contributing characteristic smoky flavors. At the microbial community level, Aspergillus, Weissella, Enterobacter, and Bacillus were enriched in DSK, promoting the accumulation of flavor and aroma compounds in alignment with industrial koji production objectives. Metabolic pathway analysis indicated that Weissella in DSK was primarily responsible for lactic acid accumulation, whereas Aspergillus dominated early-stage substrate degradation and played a key role in the enrichment of 1-octen-3-ol in WSK. This study provides insights into the “substrate–microbiota–metabolite” regulatory network and offers a theoretical basis for optimizing the use of defatted soybean in traditional soy sauce fermentation.

Polyethylene, due to its high hydrogen content, is widely utilized in nuclear facilities for neutron shielding. However, its inadequate thermal resistance limits its applicability in higher-temperature environments. The construction of carbon-boron (C-B) hybrid cross-linked networks by carborane enhanced the thermal performance of the material. At present, the synthesis methods for carborane derivatives are not sufficiently safe, efficient, and suitable for large-scale production, which restrict their application in resins. In this study, we synthesized 1,2-dichloromethyl-o-carborane (CBCl2), which acted as intermediates to develop ethylene-functionalized carborane derivatives for the first time. This derivative was introduced as a cross-linking agent into PE through cross-linking reactions, resulting in the formation of a C-B hybrid cross-linked network. In situ protection and promotion of graphitization mechanisms significantly improved the thermal stability of the materials. At 800 degrees C, the thermal residue of the materials increased by 21.01 wt % (in nitrogen) and 30.83 wt % (in air). Despite a slight reduction in hydrogen content, there was a substantial increase in boron content, which enhanced the shielding effectiveness against both thermal and fast neutrons. This work expanded and optimized the synthetic pathways for carborane derivatives, improving various properties of polyethylene and thereby ensuring its safety in nuclear facilities.

The thermal resistance of epoxy resins was limited, which hindered their application in nuclear facilities. Constructing a C-B hybrid crosslinked network using carborane improved the material's thermal properties. In this study, 1, 2-dichloromethyl-o-carborane (CBCl2) was synthesized for the first time, serving as an intermediate to synthesize N-methyl-1,3-propylenediamine-o-carborane (Et-CBNH2) for the first time. This novel approach broadened the synthesis of carborane derivatives. Et-CBNH2, as a curing agent, constructed a C-B hybrid crosslinked network, significantly enhancing the material's thermal resistance through mechanisms such as Oradical capture, protective layer formation, and promotion of graphitization. The material exhibited a 27.36 wt% increase under nitrogen and a 35.47 wt% increase under air in residue at 800 degrees C. The maximum decomposition temperature increased from 550 degrees C to 750 degrees C, with 16.59 % of the protection rate of carbon atom after thermal degradation at 750 degrees C in air. Furthermore, introducing the carborane structure into the networks greatly increased the glass transition temperature (Tg) by 115.58 degrees C. The neutron shielding properties of the material were significantly enhanced due to simultaneous enhancement of H and B atoms, which traditional methods could not achieve. This work expanded and optimized the synthesis pathway of carborane derivatives, imparting multifunctionality to epoxy resin and enhancing its various properties, thereby ensuring the safety of epoxy resin in nuclear facilities.

Shielding materials are important guarantees for the reliable operation of nuclear equipment and essential prerequisites for the safe application of nuclear energy. As an essential and most widely used shielding material, improving the high-temperature mechanical properties of PE-based shielding material is of significant importance for the lightweight and integrated design of nuclear shielding material systems. Here, a simple crosslinking method was proposed to control the crosslinking degree and crystallinity to prepare UHMWPE-based shielding materials with excellent high-temperature mechanical properties and irradiation endurance properties. The enhancement mechanisms of mechanical properties, irradiation endurance properties and shielding properties were revealed. Meanwhile, the gamma-rays and neutrons shielding properties were studied using Geant4. When the crosslinking degree was 20.62 x 10(-3) g/mol and the crystallinity was 12.13%, UHMPE-based shielding material with optimal overall performance was obtained. Compared with the un-crosslinked control sample, the tensile strength and elongation at break at room temperature, 70 and 90 degrees C were 22.3 MPa (48.90% increased) and 8.43% (154.68% increased), 8.65 MPa (105.46% increased) and 6.35% (154.00% increased), 7.48 MPa (128.75% increased) and 6.2% (89.60% increased), respectively. The vicat softening temperature and maximum thermal deformation temperature were enhance 4.20 and 6.56 degrees C when the crosslinking degree was 27.51 x 10(-3) g/mol and the crystallinity is 10.83%. Our work provided a feasible method to increase the upper temperature limit and broaden the application range of PE-based nuclear shielding materials.

Epoxy vitrimers are a novel type of environmentally friendly materials that possess exceptional properties, including self-healing, recyclability, and reprocessability. They offer a solution to the issue of traditional thermosetting epoxy resins, which are not recyclable. However, the incorporation of dynamic bonds typically results in a decrease in mechanical properties. Therefore, achieving a balance between the mechanical properties and dynamic exchange capability is crucial. In this work, a series of epoxy resin systems with various topological network characteristics were prepared by adjusting the proportions of bisphenol A epoxy resin (E51) and polyethylene glycol diglycidyl ether (EGDGE) epoxy resins in combination with a curing agent containing vinylogous urethane (VU) dynamic bonds. Through further study, we found that with the increase of E51 content, the cross-linking density of the network gradually increased, and the flexibility of the macromolecular chains decreased (favorable for enhancing the material's mechanical performance). Simultaneously, the free volume of the network gradually increased, and the tightness of the macromolecular chains decreased (favorable for improving the material's dynamic exchange ability). These two effects combined to make E51-40 exhibit the lowest activation energy for dynamic covalent bond exchange and the lowest topological transition temperature. Compared to E51-0, the tensile strength and glass transition temperature of E51-40 were improved by 22.23 % and 25.30 %, respectively. After remoulding experiment at 140 degrees C for 1h, the material exhibited a high tensile strength recovery of 91.34 %. Therefore, starting from the design of molecular structure, adjusting the network topology is an effective means to balance the mechanical and dynamic exchange properties of epoxy vitrimers. This provides experimental guidance and theoretical insights for designing high-performance epoxy vitrimer materials.

This study aimed to thoroughly investigate the shear resistance and movement dynamics of dry granular flow by utilizing a discrete element method (DEM) approach. Its focus was on exploring the effects of varying interparticle friction coefficients and slope angles on these processes. A DEM model was developed, integrating critical input parameters such as interparticle friction coefficients and slope angles, to bridge the gap between macro- and mesoscale parameters. The model leveraged complex network theory and the concept of granular temperature to capture the intricate interactions occurring at the mesoscale level. The simulation outcomes, obtained through the use of this model, revealed that shear forces induced particle rearrangement, modifying contact network properties, and disrupting the formation of stable force chains. Furthermore, an innovative macroscopic friction coefficient, tied to granular temperature and mesoscale parameters, was introduced to effectively simulate the movement of dry granular flow. This research provides valuable insights into the dynamic mechanisms underlying dry granular flow by considering the intricate interplay between macro- and mesoscales, utilizing complex network-based parameters, and incorporating granular temperature.

Epoxy resin has gained significant attention in aviation equipment, coatings and electronic packaging materials due to its exceptional processability, adhesion and mechanical properties. However, its thermal resistance property and glass transition temperature (Tg) were relatively lower than cyanate resin (CE), polyimides (PI) and phenolic resins (PF), which largely restricts its application range. In this work, we had developed a new structural heat-and-shielding integrated epoxy resin via the design of carboranes-epoxy network. Benefiting from the structure of carborane, the thermal residual weight of the obtained epoxy reached 64.57 %, with a carbon atom protection rate of 45.47 % in air atmosphere at 800 degrees C, showing better thermal resistance property than most CE, PI and PF. And the Tg of the new epoxy was not observed within the tested temperature range (50-250 degrees C). Additionally, the introduction of carborane structures enhances the neutron shielding performance of the material (38.46 % enhanced). The reinforcement mechanisms of these above properties are systematically investigated. It's excepted that our work could provide some ideas to prepare structural -functional integrated epoxy and promote the development of carborane related materials.

The polymer materials in nuclear facilities are exposed to high temperatures, radiation, and high loads. Their excellent heat resistance, radiation resistance, and shielding properties are important for the safe operation of nuclear facilities. In this study, 1,2-bis(hydroxymethyl)carborane (CBOH) was first synthesized in large quantities through water extraction and then introduced into an epoxy resin cross-linked network. The incorporation of a carborane structure significantly improved the heat resistance of epoxy. Under air atmosphere, the T-5% (the temperature at 5 wt % degradation), T-10% (the temperature at 10 wt % degradation), and char yield at 800 degree celsius of the materials were 315.67 degree celsius (16.51 degrees C increased), 326.29 degree celsius (12.96 degree celsius increased), and 33.22% (33.22% increased), respectively. The maximum decomposition temperature of the material increased from 550 to 750 degree celsius, and 7.05 wt % of the carbon constituent was protected after thermal degradation at 800 degree celsius. The glass transition temperature (T-g) of the materials greatly increased up to over 300 degree celsius after introducing the carborane structure into the networks. The radiation resistance of the material was enhanced due to the in situ capture of oxygen radicals by the carborane structure. Moreover, the incorporation of carborane structure also increased the content of H and B in materials, improving their neutron-shielding capability. This work confers multifunctionality to epoxy resin and enhances its various properties, ensuring the safety of epoxy resin in nuclear facilities.

To investigate the effect of natural spices on the shelf life quality of roasted peanut kernels, peanut kernels treated with aqueous extracts of turmeric, fennel, and peppercorns were subjected to accelerated oxidation using the Schaal oven method and were analyzed for acidity, peroxide, malondialdehyde, chroma colourimetry, textural composition, moisture content, water activity, and flavour sensory indexes during the period of storage in the oven, combined with the kinetics and the Arrhenius equation, the shelf life prediction model was completed at 20~63 ℃, validated and applied. The results showed that compared with the control group, the turmeric, fennel and peppercorn aqueous extract treatment groups could effectively inhibit the hydrolysis of oil and fatty acid oxidation, inhibit the increase of peroxide value and malondialdehyde, maintain the chromaticity and texture of peanuts better, and improve the flavour score of roasted peanuts. There was no significant difference between the moisture content of the spices groups and the control group; the water activity was less than 0.60, Aspergillus flavus struggled to thrive. The relative error of the resulting shelf life model was not more than 8.93%, which was used to quickly predict the shelf life of roasted peanuts stored at 20~63 ℃. When the storage temperature was 25 ℃, the shelf life was 170.6 days for turmeric-flavored peanuts, 150.5 days for fennel-flavored peanuts, 169.4 days for pepper-flavored peanuts, and 97.7 days for the control group.Therefore, adding turmeric, fennel, and pepper can maintain the quality of the roasted peanuts and prolong their shelf life.

ABSTRACT Terminal phospholipid groups contribute considerably to the excellent comprehensive properties of NR, but their aggregation behaviors and influence on polyisoprene properties during storage and use have not yet been revealed at the molecular level. To begin to address these phenomena, two sequentially different polyisoprene copolymers were suspended with phosphorylcholine groups to disclose their influence on phase separation, network dynamics, mechanical properties, and crystallization differences. Phosphorylcholine groups attached to polymer chains can form aggregates that increase the storage modulus of rubbers, and this process is accelerated at elevated temperatures due to faster chain movement. In addition, phosphorylcholine groups act as crosslinking points in unvulcanized and vulcanized rubbers and increase mechanical properties by promoting strain-induced crystallization (SIC). By contrast, the polymers with pendant hydroxyl groups present sequence-dependent SIC properties that are ascribed to their non-aggregation nature.

A small amount of terminal polar phase endows natural rubber (NR) with excellent comprehensive properties superior to those of synthetic isoprene rubber. In this work, the comprehensive properties of synthetic rubber were remarkably improved by introducing a stable terminal nanoconfinement structure by combining terminal hydroxyl groups and pentapeptide molecules noncovalently into the same phases. The results show that the stable terminal phases hardly affect the free chain motion but enhance the entanglement. Under cyclic loading, the terminal polar phases undergo hierarchically structural changes such as reversible dissociation of the weak bonds, phase deformation, and crystalline reorganization, all of which dissipate the stress and are beneficial for high strength and extensibility. At the same time, synthetic rubbers demonstrate much superior fatigue resistance and lower hysteresis relative to NR and maintain comparable dimensional stability. This strategy suggests that the comprehensive properties of elastomers can be regulated and upgraded by facile terminal noncovalent interactions.

Complex network analysis methods can be applied to analyze the structural evolution of granular materials during loading and establish the relationships of mechanical parameters of these materials between micro/meso and macro scales.This articles mainly reviews our research results in recent years on the structural evolution of granular materials and the relationship between microscopic parameters and macroscopic mechanical properties using complex network methods.Firstly,the basic concepts of complex networks(average degree,clustering coefficient,average path length,and force chain)are introduced.Then,the microstructural evolution of granular materials under biaxial conditions and the network contact parameter changes during the initiation and sliding of soil slopes are analyzed.Furthermore,the microstructure evolution of granular materials considering particle shape,intermediate principal stress coefficient,and complex loading paths is discussed.Finally,the mesoscopic structural parameters of the contact network are associated with the macroscopic mechanical properties,and relationships between the state parameters and average degree,the microscopic structural parameters and soil dynamic strength,the average degree as well as shortest path length and yield function of the modified Cam clay model,and the average degree and the ground vertical pressure are established.The parameters in the unified hardening model are modified based on the maximum flow model.

For decades, the preparation of polyisoprene rubber that can match the comprehensive properties of natural rubber (NR) has been pursued. While sacrificial bonds have been used to promote the strength and toughness of rubbers, little is known about their effects on fatigue resistance, which is important in dynamic environments. Herein, terminal block and randomly functionalized polyisoprene rubbers tethered with di-alanine, tri-alanine and tetra-alanine were prepared. The results showed that the flow activation energy, aggregates ordering and energy dissipation of the hydrogen-bonded aggregates increase with the elongation of oligopeptide length (XA, X=2, 3, 4), therefore resulting in enhanced mechanical strength and toughness of corresponding samples. Comparably, the tear strengths are barely affected by oligopeptide lengths in block samples, but promoted from dipeptide to tetrapeptide in random samples, probably due to the well dispersed oligopeptide aggregates. Most importantly, it is found that the tight binding aggregates of oligopeptides are critical for the excellent fatigue resistance, which is absent in polyisoprene and natural rubber. The loose aggregates dissociate and recombine repeatedly under cyclic loading and the tight aggregates keep the network integrated and robust. Interestingly, the largest hysteresis of PIP-4A-V with the longest oligopeptide length give the lowest heat generation, which is contrary to the traditional sacrificial bonds. Overall, the oligopeptide aggregates have repeatable energy dissipation properties and cycle life comparable to or even surpassing those of the linked proteins in NR, resulting in similar tensile strength, fracture toughness, and better fatigue resistance relative to NR. This deep insight on the role of oligopeptide aggregates is very useful for the engineering rubbers served in dynamic environments.

Objective: To explore the changes of the total flavonoids, free amino acids and quercetin extraction amount with the brewing time and temperature during the brewing process of Penthorum chinense Pursh （PCP） leaf tea and fit the extraction kinetics equation of the three and calculate the kinetics parameters. Methods: The total flavonoids, free amino acids and quercetin were determined by ultraviolet spectrophotometry and high performance liquid chromatography （HPLC）. The second-order kinetic model and Arrhenius formula were used to fit the kinetics and calculate the kinetic parameters. Results: The leaching amount of total flavonoids and quercetin increased with the increase of the temperature and the brewing time in the range of 60~100 ℃ for 60 min. When brewing for 60 min at 60~90 ℃, the free amino acids had the same leaching law. When the temperature rised to 100 ℃, the heat loss of free amino acids was large after brewing for 20 min. The second-order kinetic model could fit the leaching amount of the three substances well with the high correlation coefficient. Linear relationship between temperature and second-order rate constant k was good. The activation energies of total flavonoids, free amino acids and quercetin were 16 628.201, 23 415.139 and 14 975.396 J/mol. Conclusion: The extraction amount of total flavonoids, free amino acids and quercetin in PCP leaf tea changed significantly with the brewing time and temperature, and the extraction amount of the three was in line with the second-order kinetic model in the range of 60~90 ℃, which can be used to predict the extraction amount.

以赶黄草茶为原料,借助高效液相色谱(high performance liquid chromatography,HPLC)法和模糊数学法,研究冲泡温度、冲泡时间、茶添加量对茶汤槲皮素浸出量和感官品质的影响,并以模糊数学感官评价结果为响应值优化冲泡条件.结果显示,冲泡时间、冲泡温度增加,槲皮素、游离氨基酸浸出量随之增加.随着茶添加量增加,槲皮素浸出量先增加后减小,茶添加量为4.0g时单克茶叶槲皮素浸出量最大;游离氨基酸浸出量持续减小,茶添加量为1.0g时,单克茶叶游离氨基酸浸出量最大.3个因素对感官品质的影响大小为冲泡时间＞茶添加量＞冲泡温度.最优冲泡条件为冲泡时间5.6 min,冲泡温度80℃,茶添加量2.8 g,感官评分预测值8.677,实际感官评分8.64,与预测值接近.模型R2=0.990 0,拟合程度高.

In order to analyze the meso-structure of debris flow, the debris flow model with different inter-particle friction coefficients and slope angles is established here by the CFD–DEM coupled approach. The simulated results demonstrate that the drag forces caused by the inflow velocity of the fluid will drive the shallow particles to be unstable initially, and gradually disturb the deep particles. This perturbation changes the properties of the contact network, preventing it from forming stable force chains. In this process, the number of particles with a low coordination number in the network gradually increases, and it is easier to form contacts between particles with a high coordination number. Based on the evolving rule of the correlation of the degree/coordination number, we propose a criterion in terms of the correlation for the initiation of debris flow. Eventually the SIS model (susceptible-infected-susceptible epidemic model) is used to establish the movement equation of debris flow, which is beneficial to build the bridge between macro and micro parameters.