亲水单分散聚合物基质阳离子色谱柱的制备及其应用

以自制5.0 μm单分散大孔亲水交联聚甲基丙烯酸环氧丙酯微球为基质,合成一种新型弱酸性阳离子色谱填料.选用甲烷磺酸作淋洗液,在流速为1.0 mL/min时,对6种无机阳离子(Li+, Na+, NH+4, K+, Mg2+, Ca2+)和有机胺进行了良好分离.考察了淋洗液种类、浓度以及流速对6种无机阳离子分离的影响,选择了合适的色谱分离条件.测得6种离子在一定浓度范围内具有良好的线性关系和低的检出限.将其用于决明茶中阳离子的分析,4种离子在20 min内完全分离,各离子标准加入回收率在96%～107%之间.此色谱柱的分离效果与Dionex IonPacCS12A商品柱接近,但分析时间缩短了44 min.     

Information flow between stock markets: A Koopman decomposition approach

Stock markets in the world are linked by complicated and dynamical relationships into a temporal network.Extensive works have provided us with rich findings from the topological properties and their evolutionary trajectories,but the underlying dynamical mechanism is still not in order.In the present work,we proposed a technical scheme to reveal the dynamical law from the temporal network.The index records for the global stock markets form a multivariate time series.One separates the series into segments and calculates the information flows between the markets,resulting in a temporal market network representing the state and its evolution.Then the technique of the Koopman decomposition operator is adopted to find the law stored in the information flows.The results show that the stock market system has a high flexibility,i.e.,it jumps easily between different states.The information flows mainly from high to low volatility stock markets.And the dynamical process of information flow is composed of many dynamic modes distribute homogenously in a wide range of periods from one month to several ten years,but there exist only nine modes dominating the macroscopic patterns.     

Synchronizability of Highly Clustered Scale-Free Networks

We consider the effect of clustering coefficient on the synchronizability of coupled oscillators located on scale-free networks. The analytic result for the value of clustering coefficient aiming at a highly clustered scale-free network model, the Holme-Kim model is obtained, and the relationship between network synchronizability and clustering coefficient is reported. The simulation results strongly suggest that the more clustered the network, the poorer the synchronizability.     

基于离子交换-电导检测法对酿酒葡萄中有机酸含量进行分析

建立了离子色谱法测定酿酒葡萄中乳酸、丙酸、苹果酸、酒石酸、草酸、柠檬酸、琥珀酸和抗坏血酸的方法。样品经提取、脱色、过滤后以自动淋洗液发生器生成的1.5~30 mmol/L KOH为淋洗液洗脱,抑制电导检测器检测。考察了共存非测定离子及相邻离子间的干扰,结果表明非测定无机离子对测定无干扰。8种有机酸在一定浓度范围内与其峰面积呈良好的线性关系,检出限为0.064~0.25 mg/L,加标回收率为89.5%~96.2%。该方法用于宁夏贺兰山东麓酿酒葡萄中8种有机酸分析,8种有机酸均被检出,以苹果酸和酒石酸含量最高,柠檬酸次之,其它酸含量均较低。酿酒葡萄为典型的酒石酸型水果。     

酸蒸馏-离子色谱法测定枸杞中二氧化硫的残留量

<正>枸杞是宁夏的名片,也是我国传统名贵中药材。随着人们保健意识和食品安全意识的增强,食用者在享用枸杞的营养成分时,对其安全问题关注度越来越高,特别是农药残留、硫磺熏蒸等安全问题。长期或过量食用硫磺熏蒸的枸杞可对肠胃和肝脏造成     

Row–column visibility graph approach to two-dimensional landscapes

A new concept, called the row–column visibility graph, is proposed to map two-dimensional landscapes to complex networks. A cluster coverage is introduced to describe the extensive property of node clusters on a Euclidean lattice. Graphs mapped from fractals generated with the probability redistribution model behave scale-free. They have pattern-induced hierarchical organizations and comparatively much more extensive structures. The scale-free exponent has a negative correlation with the Hurst exponent, however, there is no deterministic relation between them. Graphs for fractals generated with the midpoint displacement model are exponential networks. When the Hurst exponent is large enough(e.g., H >0.5), the degree distribution decays much more slowly, the average coverage becomes significant large, and the initially hierarchical structure at H < 0.5 is destroyed completely. Hence, the row–column visibility graph can be used to detect the pattern-related new characteristics of two-dimensional landscapes.     

Empirical Study on the Volatility of the Hang-Seng Index

We study the statistical properties of volatility of price fluctuation for the Hang-Seng index in the Hong Kong stock market, they are measured by locally averaging over a time window T, the absolute value of price change over a short time interval Δt. The data include minute-by-minute records of the Hang-Seng index from 3 January 1994 to 28 May 1997. We find that the cumulative distribution of the volatility is consistent with the asymptotic power-law behaviour, characterized by the power exponent μ= 2.12 ± 0.04, different from that found in the previous studies as μ≈3. The volatility distribution remains the same asymptotic power-law behaviour for the time scales from T = 10 rain to T - 80 rain. Furthermore, we investigate the volatility correlations by using the power spectrum analysis and detrended fluctuation analysis. Both the methods show a long-range power-law decay with the exponent α=0.636±0.002.     

Scaling Behaviour and Memory in Heart Rate of Healthy Human

We investigate a set of complex heart rate time series from healthy human in different behaviour states with the detrended fluctuation analysis and diffusion entropy （DE） method. It is proposed that the scaling properties are influenced by behaviour states. The memory detected by DE exhibits an approximately same pattern after a detrending procedure. Both of them demonstrate the long-range strong correlations in heart rate. These findings may be helpful to understand the underlying dynamical evolution process in the heart rate control system, as well as to model the cardiac dynamic process.     

溴酸钾氧化吡口罗红G催化动力学光度法测定痕量NO-2

研究了在磷酸介质中亚硝酸根催化溴酸钾氧化吡口罗红Ｇ而使其褪色，建立了催化动力学光度法测定痕量亚硝酸根的新方法，测定范围为０．２～２０μｇ／ｍＬ，检出限为０．２ｎｇ／ｍＬ，用于食品和水样中的亚硝酸根测定获得满意结果     

H+反应对土壤重金属分级提取形态分析的影响

探讨了普遍存在于重金属分级提取形态分析体系中的H+浓度的影响因素,分析了H+反应与提取剂的选择性、金属离子的重分配现象的关系,以及H+浓度对分级提取法数据结果的影响,并对分级提取方法作了进一步的改进.研究表明提取剂pH、提取体系、土壤理化性质及土壤/溶液比是影响H+反应的主要因素;H+反应可降低提取剂选择性,减弱金属离子的重分配能力,影响分析结果的有效性,且对于不同的重金属离子、不同的提取体系,H+反应所造成的影响不同.