Rutin and Quercetin Decrease Cholesterol in HepG2 Cells but Not Plasma Cholesterol in Hamsters by Oral Administration

Rutin (R) and quercetin (Q) are two widespread dietary flavonoids. Previous studies regarding the plasma cholesterol-lowering activity of R and Q generated inconsistent results. The present study was therefore carried out to investigate the effects of R and Q on cholesterol metabolism in both HepG2 cells and hypercholesterolemia hamsters. Results from HepG2 cell experiments demonstrate that both R and Q decreased cholesterol at doses of 5 and 10 µM. R and Q up-regulated both the mRNA and protein expression of sterol regulatory element binding protein 2 (SREBP2), low-density lipoprotein receptor (LDLR), and liver X receptor alpha (LXRα). The immunofluorescence study revealed that R and Q increased the LDLR expression, while only Q improved LDL-C uptake in HepG2 cells. Results from hypercholesterolemia hamsters fed diets containing R (5.5 g/kg diet) and Q (2.5 g/kg diet) for 8 weeks demonstrate that both R and Q had no effect on plasma total cholesterol. In the liver, only Q reduced cholesterol significantly. The discrepancy between the in vitro and in vivo studies was probably due to a poor bioavailability of flavonoids in the intestine. It was therefore concluded that R and Q were effective in reducing cholesterol in HepG2 cells in vitro, whereas in vivo, the oral administration of the two flavonoids had little effect on plasma cholesterol in hamsters.     

化学系统性思维的背景、应用与特征*

当今地球与社会系统所面临的可持续发展、气候变化、环境退化等全球性挑战问题,用还原主义方法不足以应对,需要化学教育等领域的工作者采用系统性思维方法。梳理了国外学者在应用化学系统性思维理解化学学科系统复杂性、化学学习系统层级性、化学教育系统整合性的研究进展。概述了化学系统性思维具有重视跨学科关联、整体综合思考目标系统问题、强调可持续发展的全球观念等特征。建议加强化学教育内外部系统的协作,注重各学段化学课程与教学的跨学科、系统性,重视学生解决化学问题的认识方式差异。     

Effect of Protective Measures on Eye Exposure to Solar Ultraviolet Radiation

In this study, ocular biologically effective exposure to solar ultraviolet radiation (UVBE) is investigated with six kinds of sun protective measures (spectacle lenses, sunglasses, cap, bonnet, straw hat and under parasol). Ocular UV exposure measurements were performed on manikins during the summer period in Shenyang city (41.64° N, 123.50° E, 66 m a.s.l.), China. The measurements include the ocular UV exposure of an unprotected eye and the ambient UV as a control concurrently. Based on the relative spectral weighting factors of the International Commission on Non‐Ionizing Radiation Protection (ICNIRP), the ocular biologically effective UV is calculated and compared with the 8‐h exposure limits of ICNIRP (30 J m^?2). The UV index (UVI) of the measurement days is 0–8, and the 8‐h (8:00–16:00 China Standard Time, CST) cumulated UVBE of the unprotected eye is 452.0 J m^?2. The 8‐h cumulated UVBE of the eye with spectacle lenses, sunglasses, cap, bonnet, straw hat and under parasol are 364.2, 69.1, 51.4, 49.0, 56.8 and 110.2 J m^?2, respectively. Importantly, it should be noted that the eye could be exposed to risk despite protective measures. The 8‐h cumulated UVBE of the eye with protection is ca 1.6–15.1 times the exposure limit, respectively. As indicated in the present study, during summer months, high exposure to the sun for more than 30 min without eye protection and more than 1 h with eye protection is not advisable. The protection measures could effectively reduce the UVBE reaching the eye, yet there is still a high degree of risk when compared with the ICNIRP 8‐h exposure limits.     

煤矿顶板离层回归分析与稳定性评价

以光纤Bragg光栅位移传感器对淮北朱仙庄煤矿顶板离层监测为实际数据依据,选择最佳的典型函数模型对顶板离层进行非线性回归分析,得出能够反映位移发展趋势的回归曲线。监测结果与回归拟合数据表明:非线性回归分析预测方法不仅可以反映煤矿顶板离层实时变化过程,还能根据其变化趋势进行巷道稳定性判断。     

Porosity‐Controlled Eggshell Membrane as 3D SERS‐Active Substrate

We report on the fabrication of a surface‐enhanced Raman scattering (SERS) platform, comprised of a three‐dimensional (3D) porous eggshell membrane (ESM) scaffold decorated with Ag nanoparticles (NPs). Both native and treated ESM were used, where the treated ESM pore size and fiber crossing density was controlled by timed exposure to hydrogen peroxide (H₂O₂). Ag NPs were synthesized in situ by reduction of silver nitrate with ascorbic acid. Our results demonstrate that H₂O₂‐treated Ag‐ESM provides a more densely packed 3D network of active material, which leads to consistently higher SERS enhancement than untreated Ag‐ESM substrates.     

用3-巯基丙酸修饰的CdTe量子点作为荧光探针对镉离子的荧光光度测定

对水热合成CdTe量子点的方法加以改进,并合成了用3-巯基丙酸(MPA)修饰的CdTe量子点(MPA-CdTe QD′s)。该量子点具有荧光特性,激发、发射波长分别为320,558nm。试验了17种常见金属离子对此量子点荧光强度的影响,结果发现只有Cd(Ⅱ)离子对其荧光有增强作用;Hg(Ⅱ)、Cu(Ⅱ)、Ag(Ⅰ)则对其荧光有猝灭作用,加入适量抗坏血酸和碘化钾可消除这3种金属离子的荧光猝灭作用。试验在pH 6的缓冲介质中,以20μL MPA-CdTe QD′s作为荧光探针,加入不同浓度的Cd(Ⅱ)离子并在反应6min后,体系的荧光增强程度与Cd(Ⅱ)离子浓度在5.0×10-7~3.9×10-5 mol·L-1范围内呈线性关系,检出限(3s/k)为4.8×10-7 mol·L-1。     

以1-酮-2-(对二甲氨基苯亚甲基)-四氢萘与β-环糊精的包合物为荧光探针测定牛血清白蛋白

基于一种分子内电荷转移(ICT)化合物,1-酮-2-(对二甲氨基苯亚甲基)-四氢萘(KDTN)与β环糊精(β-CD)所生成的包合物和牛血清白蛋白(BSA)形成三元超分子体系产生的荧光,且其荧光强度与BSA的质量浓度在3.31~662mg·L-1范围内呈线性关系,检出限(3S/N)为1.6mg·L-1,提出了以KDTN与β-CD包合物为新的荧光探针的荧光光谱法测定BSA含量。该反应体系的荧光发射峰位于540nm,测定在pH 9.18的B-R缓冲介质中进行。用标准加入法进行回收试验,测得平均回收率为99.4%,测定值的相对标准偏差(n=11)为2.2%。     

纤连蛋白在石墨烯修饰二氧化钛表面吸附的计算机模拟

采用全原子分子动力学模拟方法研究了纤连蛋白(FN)在金红石表面、23%石墨烯覆盖率的金红石表面、92%石墨烯覆盖率的金红石表面、石墨表面的吸附行为.模拟结果表明:FN在金红石表面吸附不稳定.通过石墨烯修饰二氧化钛表面可降低金红石表面的亲水性;当表面含有石墨烯层时,FN都将稳定地吸附在表面上.在23%石墨烯覆盖率的金红石表面上,FN的特异性识别位点朝向溶液而有利于整合素识别.DSSP分析结果显示在40 ns的分子动力学模拟过程中,FN的七个β-折叠结构在所有体系中均没有发生太大变化.由于有石墨烯层存在,表面附近水分子层密度减小.FN的表面吸附能随着表面石墨烯覆盖率的增加而增大.石墨烯修饰能加强二氧化钛表面对蛋白质的吸附.本工作可以为移植体修饰生物材料设计与开发提供参考.     

Metal–Sulfur Linkages Achieved by Organic Tethering of Ruthenium Nanocrystals for Enhanced Electrochemical Nitrogen Reduction

Inspired by the metal–sulfur (M-S) linkages in the nitrogenase enzyme, here we show a surface modification strategy to modulate the electronic structure and improve the N₂ availability on a catalytic surface, which suppresses the hydrogen evolution reaction (HER) and improves the rate of NH₃ production. Ruthenium nanocrystals anchored on reduced graphene oxide (Ru/rGO) are modified with different aliphatic thiols to achieve M-S linkages. A high faradaic efficiency (11 %) with an improved NH₃ yield (50 μg h⁻¹ mg⁻¹) is achieved at −0.1 V vs. RHE in acidic conditions by using dodecanethiol. DFT calculations reveal intermediate N₂ adsorption and desorption of the product is achieved by electronic structure modification along with the suppression of the HER by surface modification. The modified catalyst shows excellent stability and recyclability for NH₃ production, as confirmed by rigorous control experiments including ¹⁵N isotope labeling experiments.