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81.
To reduce the crystallization rate of polyoxymethylene (POM) to meet the requirement of thick-walled and large-sized articles production, and maintain high crystallinity as well as obtain refined crystalline grains to ensure the strength and stiffness simultaneously, thermoplastic phenolic resin (PF) and multiwalled carbon nanotubes (MWCNTs) were used as crystal growth inhibitor and nucleating agent, respectively, and their effects on the crystallization of POM were studied in details. The results showed that PF is an effective inhibitor and MWCNTs exhibits excellent nucleation effect on POM. Based on the obtained results, their synergistic influences on the crystallization process of POM were investigated. It is found that the objective of decreasing the crystallization rate while maintaining high crystallinity and forming fine crystalline grains can be realized. The 97/3/1 wt% POM/PF/MWCNTs, compared with those of neat POM, The T c shifts by 3.3°C to a lower temperature, the crystallization enthalpy increases by 16.1 J/g and the full width at half-maximum widens by 48.5%. The modulation effect of PF and MWCNTs on the crystallization is closely related to the PF content and dispersion, the distribution and dispersion of MWCNTs in the PF and POM phases.  相似文献   
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Marsdenia tenacissima, or Tongguanteng in Chinese, is a traditional Chinese herb and has a broad application in clinical practice for its pharmacological effects of treating asthma, pneumonia, tonsillitis, pharyngitis tumors, etc. However, few studies have reported the screening of the active components of this medicine for tumor therapy. In this work, a two‐dimensional analytical system was developed to screen antagonists of epidermal growth factor receptor (EGFR) from M. tenacissima. A fraction was retained on the EGFR cell membrane chromatography (CMC) column, separated and identified as tenacissoside G (TG), tenacissoside H (TH) and tenacissoside I (TI) by two‐dimensional HPLC–IT–TOF–MS. Molecular docking and 3‐(4,5‐dimethyl‐2‐thiazolyl)‐2,5‐diphenyl‐2‐H‐tetrazolium bromide (MTT) assay were carried out to assess the activity of TS (including TG, TH and TI). Molecular docking results showed that the binding mode of TS on EGFR is similar to that of gefitinib. The MTT assay demonstrated that gefitinib and TS (especially TI) could inhibit the growth of EGFR highly expressed cell lines in a dose‐dependent manner in the range of 5–50 μmol/L. In conclusion, the two‐dimensional EGFR/CMC–HPLC–IT–TOF–MS system could be a useful approach in drug discovery from traditional Chinese medicines for searching for potential antitumor candidates.  相似文献   
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Multistrain diseases, which are infected through individual contacts, pose severe public health threat nowadays. In this paper, we build competitive and mutative two‐strain edge‐based compartmental models using probability generation function (PGF) and pair approximation (PA). Both of them are ordinary differential equations. Their basic reproduction numbers and final size formulas are explicitly derived. We show that the formula gives a unique positive final epidemic size when the reproduction number is larger than unity. We further consider competitive and mutative multistrain diseases spreading models and compute their basic reproduction numbers. We perform numerical simulations that show some dynamical properties of the competitive and mutative two‐strain models.  相似文献   
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随加工工艺趋于复杂化和极端化,基于热力学驱动力和动力学能垒相对独立的枝晶生长理论已无法精确描述多种机制共同作用的非平衡凝固过程,大大限制了该理论与工业应用的结合。首先,本文综述基于热-动力学相对独立的枝晶生长理论的发展,分析其内涵的本征热-动力学相关性,并集成于以双辊薄带连铸技术为背景的基于热-动力学相关性的枝晶生长模型。其次,定量证明了热力学驱动力和动力学能垒的相关性,通过选择不同的驱动力-能垒组合,试图在双辊薄带连铸技术中实现合金设计和工艺优化。最后,通过分析现有模型的不足,对进一步枝晶生长模型的发展以及与工艺的结合进行展望。  相似文献   
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Novel heterogeneous tungsten species in mesoporous silica SBA‐16 catalysts based on ship‐in‐a‐bottle methodology are originally reported for oxidizing cyclopentene (CPE) to glutaric acid (GAC) using hydrogen peroxide (H2O2). For all W‐SBA‐16 catalysts, isolated tungsten species and octahedrally coordinated tungsten oxide species are observed while WO3 crystallites are detected for the W‐SBA‐16 catalysts with Si/ W = 5, 10, and 20. The specific surface areas and the corresponding total pore volumes decrease significantly as increasing amounts of tungsten incorporated into the pores of SBA‐16. Using tungsten‐substituted mesoporous SBA‐16 heterogeneous catalysts, high yield of GAC (55%) is achieved with low tungsten loading (for Si/W = 30, ~13 wt%) for oxidation of CPE. The W‐SBA‐16 catalysts with Si/W = 30 can be reused five times without dramatic deactivation. In fact, low catalytic activity provided by bulk WO3 implies that the highly distributed tungsten species in SBA‐16 and the steric confinement effect of SBA‐16 are key elements for the outstanding catalytic performance.  相似文献   
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