Existence of multiplicity harmonic and subharmonic solutions for second‐order quasilinear equation via Poincaré‐Birkhoff twist theorem

In this paper, we investigate the existence and multiplicity of harmonic and subharmonic solutions for second‐order quasilinear equation where , g satisfies the superlinear condition at infinity. We prove that the given equation possesses harmonic and subharmonic solutions by using the phase‐plane analysis methods and a generalized version of the Poincaré‐Birkhoff twist theorem.     

Prenylated Flavonoid Glycosides with PCSK9 mRNA Expression Inhibitory Activity from the Aerial Parts of Epimedium koreanum

Phytochemical investigation on the n-BuOH-soluble fraction of the aerial parts of Epimedium koreanum using the PCSK9 mRNA monitoring assay led to the identification of four previously undescribed acylated flavonoid glycosides and 18 known compounds. The structures of new compounds were elucidated by NMR, MS, and other chemical methods. All isolated compounds were tested for their inhibitory activity against PCSK9 mRNA expression in HepG2 cells. Of the isolates, compounds 6, 7, 10, 15, and 17–22 were found to significantly inhibit PCSK9 mRNA expression. In particular, compound 7 was shown to increase LDLR mRNA expression. Thus, compound 7 may potentially increase LDL uptake and lower cholesterol levels in the blood.     

Water-in-Oil-in-Water Nanoemulsions Containing Temulawak (Curcuma xanthorriza Roxb) and Red Dragon Fruit (Hylocereus polyrhizus) Extracts

Hydrophobic curcumin in temulawak extract and hydrophilic betacyanin in red dragon fruit extract are high-value bioactive compounds with extensive applications in functional food. In this study, these extracts were encapsulated in water-in-oil-in-water (w/o/w) nanoemulsions as a delivery system using a two-step high-energy emulsification method. PGPR and Span 20 were used as lipophilic emulsifiers for the primary w/o emulsion. The most stable w/o/w formulation with the least oil phase separation of 5% v/v consisted of w/o emulsion (15% w/w) and Tween 80 (1.5% w/w) as hydrophilic emulsifier. The formulation was characterized by a 189-nm mean droplet diameter, 0.16 polydispersity index, and –32 mV zeta potential. The freeze–thaw stability may be attributed to the combination of low w/o emulsion content and high Tween 80 concentration in the outer water phase of the w/o/w nanoemulsions used in this study. The IC₅₀ values of the nanoemulsion and the red dragon fruit extract were similar. It means that the higher concentration of curcumin in the nanoemulsions and the lower IC₅₀ value of temulawak extract ensured sufficient antioxidant activities of the w/o/w nanoemulsions.     

一步硫/磷热处理制备空心Co9S8/CoP/C纳米复合材料及其储钠性能研究

低成本、高性能的钠离子电池有望成为代替锂离子电池的下一代核心器件.但是开发出高比容量、高倍率的钠离子电池负极材料依然是瓶颈.本文通过水热/溶剂热法制备了Co基前驱体,然后将其一步硫/磷热处理制得具有空心多孔结构的h-Co₉S₈/CoP/C纳米复合材料.通过X-射线粉末衍射(XRD)、拉曼光谱(Raman)、扫描电镜(SEM)、透射电镜(TEM)和X-射线光电子能谱(XPS)等表征以确定纳米复合物的物相以及形貌特征.当h-Co₉S₈/CoP/C作为钠离子电池负极材料时,该电极材料展示了高的比容量(561 mAh g^-1@0.1 Ag^-1)、较好的循环性能(可逆比容量200 mAh g^-1@2 Ag^-1)和倍率性能.h-Co₉S₈/CoP/C之所以显示出良好的储钠性能,主要得益于其空心多孔结构不仅提供更多的空间缓解钠在反复嵌入和脱出过程造成的体积膨胀效应,而且可以缩短离子/电荷扩散途径以加快反应动力学,此外,Co₉S₈、CoP和C独特的电子结构优势得以共同发挥.     

Theoretical Investigating Mechanisms of Drug-Resistance Generated by Mutation-Induced Changes in Influenza Viruses

Influenza A (A/H\begin{document}$ x $\end{document}N\begin{document}$ y $\end{document}) is a significant public health concern due to its high infectiousness and mortality. Neuraminidase, which interacts with sialic acid (SIA) in host cells, has become an essential target since its highly conserved catalytic center structure, while resistance mutations have already generated. Here, a detailed investigation of the drug resistance mechanism caused by mutations was performed for subtype N9 (A/H7N9). Molecular dynamics simulation and alanine-scanning-interaction-entropy method (ASIE) were used to explore the critical differences between N9 and Zanamivir (ZMR) before and after R294K mutation. The results showed that the mutation caused the hydrogen bond between Arg294 and ZMR to break, then the hydrogen bonding network was disrupted, leading to weakened binding ability and resistance. While in wild type (A/H7N9\begin{document}$ ^{ \rm{WT}} $\end{document}), this hydrogen bond was initially stable. Meanwhile, N9 derived from A/H11N9 was obtained as an R292K mutation. Then the relative binding free energy of N9 with five inhibitors (SIA, DAN, ZMR, G28, and G39) was predicted, basically consistent with experimental values, indicating that the calculated results were reliable by ASIE. In addition, Arg292 and Tyr406 were hot spots in the A/H11N9\begin{document}$ ^{ \rm{WT}} $\end{document}-drugs. However, Lys292 was not observed as a favorable contributing residue in A/H11N9\begin{document}$ ^{ \rm{R292K}} $\end{document}, which may promote resistance. In comparison, Tyr406 remained the hotspot feature when SIA, ZMR, and G28 binding to A/H11N9\begin{document}$ ^{ \rm{R292K}} $\end{document}. Combining the two groups, we speculate that the resistance was mainly caused by the disruption of the hydrogen bonding network and the transformation of hotspots. This study could guide novel drug delivery of drug-resistant mutations in the treatment of A/H\begin{document}$ x $\end{document}N9.     

脑胶质瘤磁共振弥散张量成像定量参数与VEGF、MMP-9表达的相关性

本研究旨在分析脑胶质瘤患者的磁共振弥散张量成像(DTI)参数与病变组织血管内皮生长因子(VEGF)和基质金属蛋白酶-9(MMP-9)表达的相关性,以及DTI参数对脑胶质瘤进行分级诊断的价值。根据病理分级将102例脑胶质瘤患者分为低级别组(47例)和高级别组(55例),均行MRI和DTI检查,定量测定表观弥散系数(ADC)、各向异性分数(FA)、相对ADC(rADC)、相对FA(rFA)值及相对轴向扩散系数(rAD)值;用免疫组化法检测VEGF和MMP-9表达情况。结果显示,高级别组患者的rADC、ADC、rAD、FA、rFA均低于低级别组(P<0.05);高级别组患者的VEGF和MMP-9阳性表达均高于低级别组(P<0.05)。rADC、ADC、rAD、FA、rFA与VEGF和MMP-9表达均呈负相关(P<0.05);rADC、ADC、rAD、FA、rFA对脑胶质瘤分级诊断的AUC均具有一定诊断价值(P<0.05)。本研究结果提示DTI定量参数与脑胶质瘤VEGF和MMP-9表达具有相关性,且有助于脑胶质瘤的分级诊断。     

质子水合结构的振动态密度分析

使用基于多态经验价键模型的分子动力学模拟, 对水溶液中质子的水合结构及其在质子传递过程中的动力学过程进行了研究. 在价键模型的方法下, 质子的水合结构主要以H₉O₄⁺(Eigen)以及过渡态的H₅O₂⁺(Zundel)结构形态存在, 且在这两种结构中以Eigen的形态表现明显. 通过对质子传递过程中不同水合结构的态密度频谱分析, 发现一个在2000~3000 cm^-1范围内的明显连续的宽吸收谱带, 主要归因于Eigen结构的贡献, 这些特征峰的出现与水合氢离子第一溶剂化层内的强氢键作用密切相关. 对于Zundel的结构, 在1760 cm^-1处出现一个较为明显的肩峰, 归属为质子传递模式的特征振动. 通过对质子水合结构态密度频谱的分析, 可望增强对于稀酸溶液红外光谱中的连续宽吸收带以及质子传递的微观动力学过程的理解.     

中空碳纳米球的制备及VOCs吸附性能

首先, 在碱性条件下, 不使用表面活性剂, 采用St?ber小球法以正硅酸四乙酯(TEOS)和正硅酸四丙酯(TPOS)为硅源, 生成初级氧化硅球形颗粒; 然后, 使酚醛树脂(间苯二酚和甲醛)与球形氧化硅的羟基共缩合形成酚醛树脂-氧化硅复合材料; 最后, 经高温碳化和酸蚀获得了空心碳纳米球(HCNSs). 通过调节TEOS/TPOS的摩尔比获得了一系列具有良好的单分散性且粒径、 壁厚可调节的HCNSs, 其粒径和壁厚分别在280~430 nm和15~63 nm的范围内. 仅以TPOS为硅源时合成的HCNS-0/4具有较大的粒径(426 nm)和壁厚(63 nm)、 较高的比表面积(1216 m²/g)和孔容(0.508 cm³/g), 并且具有较大的挥发性有机化合物(VOCs)吸附性能, 其正己烷、 甲苯和油气的静态吸附容量分别为2.02, 1.42和0.926 g/g, 正己烷和甲苯的动态吸附容量分别为2.01 g/g和1.37 g/g, 均远高于商业化活性炭.     

非平衡溶剂化新理论在有机染料电子光谱中的应用

总结了非平衡溶剂化新理论和在量子化学软件Q-Chem中基于含时密度泛函理论(TD-DFT)实现溶剂效应下计算电子吸收和发射光谱的数值解方法.采用该方法计算了染料敏化太阳能电池(DSSCs)中三苯胺型有机染料■在真空和乙腈溶剂中的电子结构与光谱性质,研究发现,π共轭桥上碳碳双键的个数和溶剂效应会促进光电转换.     

高通量虚拟筛选CDK2/Cyclin A2靶点抑制剂

CDK2/Cyclin A2复合蛋白的异常表达与乳腺癌、 口腔癌、 食管鳞状细胞癌的发生密切相关. CDK2/ Cyclin A2复合蛋白的活性位点不同于CDK2单体. 至今临床上尚无靶向此复合蛋白的药物分子. 针对CDK2/Cyclin A2复合蛋白, 以实验报道的10个抑制剂分子构建药效团模型, 通过药物体外药代动力学（ADME）、 Docking、 聚类分析、 毒性预测, 从DrugBank, ChEMBL和TCM@Taiwan 3个数据库约90万组数据中进行高通量虚拟筛选, 进一步进行MD模拟、 MM/PBSA结合自由能计算、 能量分解和平均非共价作用(aNCI)分析, 筛选出3个抑制效果优于阳性实验药Roscovitine的先导分子: DrugBank-2004, DrugBank-583和ChEMBL-7122. 与CDK2蛋白相比, CDK2/Cyclin A2复合蛋白结合位点空间变大, 先导分子与Lys33, Asp86, Lys129和Asp145残基之间的排斥作用有所降低, 导致结合自由能更大.