Evaluation of antioxidant activity of the polysaccharides extracted from Lycium barbarum fruits in vitro

Polysaccharides, one of the most important functional constituent in Lycium barbarum fruits, a famous Chinese medicinal herb, are isolated with boiling water decoction. Analysis shows that its carbohydrate content is up to 97.54% mainly composed of d-rhamnose, d-xylose, d-arabinose, d-fucose, d-glucose, and d-galactosc. In the present study, the antioxidant activity of the polysaccharides extracted from L. barbarum fruits was evaluated by six established in vitro methods, namely superoxide radical () scavenging activity, reducing power, β-carotene-linoleate model, inhibition of mice erythrocyte hemolysis mediated by peroxyl free radicals, 1,1-diphenyl-2 picrylhydrazyl (DPPH⁻) radical-scavenging and metal chelating activity. The polysaccharides showed notable inhibitory activity in the β-carotene-linoleate model system in a concentration-dependent manner. Furthermore, it exhibited a moderate concentration-dependent inhibition of the DPPH⁻ radical. The multiple antioxidant activity of the polysaccharides was evident as it showed significant reducing power, superoxide scavenging ability, inhibition of mice erythrocyte hemolysis mediated by peroxyl free radicals and also ferrous ion chelating potency. The data obtained in the in vitro models clearly establish the antioxidant potency of the polysaccharides extracted from L. barbarum fruits.     

偶氮胭脂红G共振光散射法测定羟自由基的研究及应用

基于Fenton反应产生的·OH对偶氮胭脂红G(AG)的褪色反应,使偶氮胭脂红G在434 nm处共振散射光强度降低,采用偶氮胭脂红G为指示剂,在优化测定条件后,建立了一个共振光散射法测定Fenton反应所产生的·OH的新方法,并用所建立的新方法研究了一些常见抗氧化剂对·OH清除的量效关系,验证了方法的可行性.在此基础上,用该方法研究了一些茶叶水提取液的抗氧化能力,结果表明,所有茶叶提取液均具有一定清除·OH的能力.在所研究的几种茶叶中,以普洱茶清除·OH的能力最强.     

光度法研究中草药提取物对·OH的清除作用

用水和乙醇对5种清热类草药(金银花、柴胡、连翘、大青叶、板蓝根)和5种理气类草药(陈皮、佛手、桔实、沉香、木香)进行了超声提取,采用Fenton反应模型测定了各提取物对·OH的清除能力,并与维生素C作参照,计算出各个中草药提取液的IC50,比较了各自的清除率大小。结果表明:不同草药的·OH的清除能力不同;5种清热类草药提取液的·OH清除率最强的是板蓝根醇提取物;5种理气类草药中·OH清除率最强的是佛手的水提液和沉香的醇提取物。     

Estimates for the Hill operator, II

Consider the Hill operator Ty=-y^″+q(t)y in L²(R), where the real potential q is 1-periodic and q,q^′∈L²(0,1). The spectrum of T consists of spectral bands separated by gaps γ_n,n?1 with length |γ_n|?0. We obtain two-sided estimates of the gap lengths ∑n²|γ_n|² in terms of . Moreover, we obtain the similar two-sided estimates for spectral data (the height of the corresponding slit on the quasimomentum domain, action variables for the KdV equation and so on). In order prove this result we use the analysis of a conformal mapping corresponding to quasimomentum of the Hill operator. That makes it possible to reformulate the problems for the differential operator as the problems of the conformal mapping theory. Then the proof is based on the analysis of the conformal mapping, the embedding theorems and the identities. Furthermore, we obtain the similar two-sided estimates for potentials which have p?2 derivatives.     

Constituents from Aerial Parts of Bidens ceruna L. and Their DPPH Radical Scavenging Activity

A new chalcone glycoside,butein-4-methoxyl-4'-O-(6-O-acetyl)-β-D-glucopyranoside(2),along with seven known compounds,namely,quercitrin(1),luteolin-7-O-β-D-glucopyranoside(3),butein-4'-O-β-D-glucopyra-noside(4),butein-4-methoxyl-4'-O-β-D-glucopyranoside(5),butin-7-O-β-D-glucopyranoside(6),isoquercitrin(7),and sulfurein(8) was isolated from aerial parts of Bidens ceruna L. Their structures were elucidated on the basis of spectroscopic studies. Compounds 1―8 were tested for their DPPH radical scavenging activi...     

新型稀土抗菌剂与DNA作用机理的光谱学研究

采用紫外光谱,荧光光谱研究了6种新型的具有抗菌活性的稀土-异亮氨酸-邻菲咯啉三元配合物[RE(Ile)<,3>PhenCl<,3>·4H<,2>O,RE=La、Eu、Sm、Nd、Y,Yb]与小牛胸腺(CT-DNA)的作用机理,研究表明,三元配合物与CT-DNA的作用方式为嵌入作用.这一研究结果为稀土配合物在农牧业作为动...     

光诱导约束刻蚀体系中的TiO_2纳米管阵列光电极上Cu的沉积及抑制

光诱导约束刻蚀可作为一种无应力的化学平坦化方法用于Cu的抛光。我们发现在光诱导约束刻蚀工件Cu的过程中,工具表面的TiO_2纳米管上可能出现Cu沉积。通过扫描电子显微镜及其能谱,X射线光电子能谱等方法分析其沉积形貌和成分组成,探究在工具-工件之间的微纳尺度液层中Cu光催化还原沉积的机制,并在模拟液中研究Cu沉积对刻蚀体系的影响。探究引入搅拌、加入络合剂对TiO_2纳米管表面Cu的沉积的抑制,并考察抑制措施对于工件Cu刻蚀的影响。结果表明Cu沉积会增强TiO_2纳米管光电极的光催化性能,但随着沉积量的增加,增强机制会发生变化;在尝试抑制Cu沉积时也发现改善传质以抑制Cu沉积的同时也会带来工件Cu的刻蚀增强;采用添加络合剂结合改善传质的方法有望在抑制Cu沉积的同时提高平坦化效果。所以抑制方法和条件的选择需兼顾对工具-工件之间微纳液层中的多个化学和传质过程的影响。这些研究对于进一步优化光诱导约束刻蚀体系及其在化学平坦化中的应用有重要的指导意义。     

Approximate reasoning and finite state machines to the detection of actions in video sequences

In this paper a novel approach for recognizing actions in video sequences is presented, where the information obtained from the segmentation and tracking algorithms is used as input data. First of all, the fuzzification of input data is done and this process allows to successfully manage the uncertainty inherent to the information obtained from low-level and medium-level vision tasks, to unify the information obtained from different vision algorithms into a homogeneous representation and to aggregate the characteristics of the analyzed scenario and the objects in motion. Another contribution is the novelty of representing actions by means of an automaton and the generation of input symbols for the finite automaton depending on the comparison process between objects and actions, i.e., the main reasoning process is based on the operation of automata with capability to manage fuzzy representations of all video data. The experiments on several real traffic video sequences demonstrate encouraging results, especially when no training algorithms to obtain predefined actions to be identified are required.     

一类非自治p-Laplace系统的同宿轨道

利用临界点理论的极小化原理讨论一类非自治p-L ap lace系统d/(dt)(q(t)p-2q(t))-l(t)q(t)p-2q(t)+▽W(t,q(t))=0非平凡同宿轨道的存在性,其中,p>1,t∈R,q∈Rn,l:R→(0,+∞),W(t,q(t))=a(t)q(t)γ且a(t):R→R+是一非负连续函数,1<γ相似文献   

树状聚酰胺-胺桥联受阻酚类抗氧化剂的合成及清除DPPH·活性研究

以系列1.0、2.0代树状聚酰胺-胺(PAMAM)为桥联基,3-(3,5-二叔丁基-4-羟基苯基)丙酰氯为抗氧化基团,通过酰胺化缩合反应合成了系列树状桥联受阻酚类抗氧化剂。红外光谱和核磁共振氢谱证实了系列树状聚酰胺-胺桥联受阻酚类抗氧化剂的化学结构。采用EPR技术研究系列树状聚酰胺-胺桥联受阻酚类抗氧化剂清除DPPH·的能力,结果表明,系列树状聚酰胺-胺桥联受阻酚类抗氧化剂具有良好清除DPPH·活性,且随着清除时间的延长、桥联基长度和代数的增加,其清除活性增强。