交直交型机车的高频谐波混沌分析

针对典型的交直交型动车组CRH2车型,推导出其在正弦脉宽调制下的参数方程,并建立一套新的非线性参数模型.通过混沌原理分析了高次谐波的分形情况,并针对典型的牵引变电站,进行了计算和仿真,依托实际录波的数据验证,证实高频谐波能够导致系统谐振,为混沌分析方法拓展了新的应用.     

Antioxidant Activity of Acanthopanax senticosus Flavonoids in H2O2-Induced RAW 264.7 Cells and DSS-Induced Colitis in Mice

The redox reaction is a normal process of biological metabolism in the body that leads to the production of free radicals. Under conditions such as pathogenic infection, stress, and drug exposure, free radicals can exceed normal levels, causing protein denaturation, DNA damage, and the oxidation of the cell membrane, which, in turn, causes inflammation. Acanthopanax senticosus (A. senticosus) flavonoids are the main bioactive ingredients with antioxidant function. H₂O₂-treated RAW 264.7 cells and DSS-induced colitis in mice were used to evaluate the antioxidant properties of A. senticosus flavonoids. The results show that A. senticosus flavonoids can significantly downregulate the levels of ROS and MDA in H₂O₂-treated RAW 264.7 cells and increase the levels of CAT, SOD, and GPx. A. senticosus flavonoids can also increase the body weights of DSS-induced colitis mice, increase the DAI index, and ameliorate the shortening of the colon. ELISA experiments confirmed that A. senticosus flavonoids could reduce the level of MDA in the mouse serum and increase the levels of SOD, CAT, and GPx. Histopathology showed that the tissue pathological changes in the A. senticosus flavonoid group were significantly lower than those in the DSS group. The Western blot experiments showed that the antioxidant capacity of A. senticosus flavonoids was accomplished through the Nrf2 pathway. In conclusion, A. senticosus flavonoids can relieve oxidative stress in vivo and in vitro and protect cells or tissues from oxidative damage.     

Preparation and Properties of Cyclodextrin Inclusion Complexes of Hyperoside

In order to improve the aqueous solubility and enhance the bioavailability of Hyperoside (Hyp), three inclusion complexes (ICs) of Hyp with 2-hydroxypropyl-β-cyclodextrin (2H-β-CD), β-cyclodextrin (β-CD), and methyl-β-cyclodextrin (M-β-CD) were prepared using the ultrasonic method. The characterization of the inclusion complexes (ICs) was achieved using Fourier-transform infrared spectroscopy (FTIR), scanning electronic microscopy (SEM), X-ray powder diffraction (XRPD), thin-layer chromatography (TLC), and ¹H nuclear magnetic resonance (¹H NMR). The effects of the ICs on the solubility and antioxidant activity of Hyp were investigated. A Job’s plot revealed that the Hyp formed ICs with three kinds of cyclodextrin (CD), all at a 1:1 stoichiometric ratio. The FTIR, SEM, XRPD, TLC, and ¹H NMR results confirmed the formation of inclusion complexes. The water solubility of the IC of Hyp with 2-hydroxypropyl-β-cyclodextrin was enhanced 9-fold compared to the solubility of the original Hyp. The antioxidant activity tests showed that the inclusion complexes had higher antioxidant activities compared to free Hyp in vitro and the H₂O₂–RAW264.7 cell model. Therefore, encapsulation with CDs can not only improve Hyp’s water solubility but can also enhance its biological activity, which provides useful information for the potential application of complexation with Hyp in a clinical context.     

体积排阻色谱法定量检测9种型别人乳头瘤病毒原液中病毒样颗粒

据统计,5％以上的人类癌症由人乳头瘤病毒(HPV)导致.HPV疫苗的使用,尤其是多价HPV疫苗的使用,可有效预防HPV感染和肿瘤的发生.例如,9价HPV疫苗可有效预防90％以上HPV相关癌前病变.人乳头瘤病毒样颗粒(VLP)是HPV疫苗的唯一抗原.VLP由360份衣壳蛋白L1组成.VLP的含量测定对HPV原液和HPV疫...     

Quality and Metabolomics Analysis of Houttuynia cordata Based on HS-SPME/GC-MS

Houttuynia cordata is a medicinal and edible plant with a wide biological interest. Many parts were discarded due to various modes of consumption, resulting in resource waste. In this study, a comprehensive study was conducted on various edible indicators and medicinal components of Houttuynia cordata to understand its edible and medicinal value. The edible indexes of each root, stem, and leaf were determined, and the metabolites of different parts were investigated using the headspace solid-phase micro-extraction technique (HS-SPME-GC-MS). The differential metabolites were screened by orthogonal partial least squares discriminant analysis (OPLS-DA) and clustering analysis. The results of the study showed that the parts of Houttuynia cordata with high edibility values as a vegetable were mainly the roots and leaves, with the highest vitamin C content in the roots and the highest total flavonoids, soluble sugars, and total protein in the leaves. The nutrient content of all the stems of Houttuynia cordata was lower and significantly different from the roots and leaves (p < 0.05). In addition, 209 metabolites were isolated from Houttuynia cordata, 135 in the roots, 146 in the stems, 158 in the leaves, and 91 shared metabolites. The clustering analysis and OPLS-DA found that the parts of Houttuynia cordata can be mainly divided into above-ground parts (leaves and stems) and underground parts (roots). When comparing the differential metabolites between the above-ground parts and underground parts, it was found that the most important medicinal component of Houttuynia cordata, 2-undecanone, was mainly concentrated in the underground parts. The cluster analysis resulted in 28 metabolites with up-regulation and 17 metabolites with down-regulation in the underground parts. Most of the main components of the underground part have pharmacological effects such as anti-inflammatory, anti-bacterial and antiviral, which are more suitable for drug development. Furthermore, the above-ground part has more spice components and good antioxidant capacity, which is suitable for the extraction of edible flavors. Therefore, by comparing and analyzing the differences between the edible and medicinal uses of different parts of Houttuynia cordata as a medicinal and food plant, good insights can be obtained into food development, pharmaceutical applications, agricultural development, and the hygiene and cosmetic industries. This paper provides a scientific basis for quality control and clinical use.     

Thermodynamic Analysis of Urea Physical Vapour Transport

The vaporisation-condensation scheme of urea has been investigated in the temperature region below the melting point, in order to establish the thermodynamic reactions on which the physical vapour transport (PVT) of urea is based. By making use of both reported data and experimental results of MS, DTA, DTG, and HPLC analysis, it was shown that PVT relevant reactions are basically molecular sublimation and partial decomposition in solid biuret and ammonia. MS analysis of urea crystals and source residues have also shown that no decomposition can be observed in the growing crystals, unless reheated during growth. The temperature dependence of the decomposition pressure has been found to be: log₁₀P_NH3 [torr] = 38 – 13840/T [K]. The use of this relation in diffusive mass transport calculations brought to linear growth rate values not in disagreement with the experimental values found in closed tube PVT grown crystals.     

Direct Catalytic Asymmetric and Regiodivergent N1- and C3-Allenylic Alkylation of Indoles

Herein we report a Pd-catalyzed asymmetric allenylic alkylation strategy for the direct functionalization of 1H-indoles by employing P-chiral BIBOP-type ligands. The regioselectivity (N1/C3) of this process can be switched efficiently. Using Cs₂CO₃ at elevated temperatures in MeCN, N1-alkylated indoles bearing axial chirality with a stereocenter non-adjacent (β) to the nitrogen are produced in good yields with high enantioselectivity and complete N1-regioselectivity regardless of the electronic properties and substitution patterns of diverse indoles. Using K₂CO₃ at room temperature in CH₂Cl₂, chiral C3-alkylated indoles can also be obtained. Notably, we introduce a new class of tri-substituted allenylic electrophiles that proceeded through different pathways from di-substituted allenylic electrophiles.     

Solution Growth and Characterisation of L‐alanine Single Crystals

Single crystals of L‐alanine have been grown from buffered aqueous solutions and characterised as to their optical quality via wavefront distortion analysis, electrooptical response and harmonic generation efficiency. Refraction indices as well as phase matching loci were found in satisfactory agreement with previously published data for crystals grown in non buffered solution. Estimates for the electro‐optical response are reported for the first time. The experimentally observed crystal habit is discussed in terms of morphological importance (M.I.), which was found to be in disagreement with the predictions of crystallographic criteria based on the interplanar distance d_hkl, on the periodic bond chains (PBC) and the attachment energy E_att. This disagreement is tentatively attributed to the presence of impurities and non‐appropriate supersaturation conditions.     

Top-Seeded Solution Growth of Monomethylurea Single Crystals

It was previously reported on the growth of monomethylurea (NMU) single crystals from methanol solution by a mechanical limitation-direction (MLD) technique in which long (100) oriented seeds, capped on their extremities, were employed. The crystals obtained by this technique, in spite of their good structural and optical quality, presented their core region, in which the seed was located, with a higher density of structural defects and henceforth a reduced cross section useful for optical applications. It is here referred to a new, top-seeded growth configuration, devised on the basis of a preliminary PBC analysis for assessing the morphological importance of the crystal faces experimentally observed during crystal growth, which allows to grow NMU crystals in which the defected core region is removed for almost the entire length of the crystal.