Time series model based on global structure of complete genome

A time series model based on the global structure of the complete genome is proposed. Three kinds of length sequences of the complete genome are considered. The correlation dimensions and Hurst exponents of the length sequences are calculated. Using these two exponents, some interesting results related to the problem of classification and evolution relationship of bacteria are obtained.     

光助Fenton试剂氧化降解染料直接耐晒黑G的研究

文章研究了影响Fenton试剂氧化降解持久性有机污染物直接耐晒黑G的因素,如光源的选择、初始pH值、H₂O₂的用量、Fe2+的用量、阳离子交换树脂载体的引入等,通过研究确定了各因素的优化条件。研究结果表明：太阳光照能有效的促进直接耐晒黑G染料的降解脱色,大大缩短反应时间;引入阳离子交换树脂后,可增强Fenton氧化反应的活性,降解效果更好。     

DMSO溶剂中有机化合物pKa的定量构效关系研究

应用物质结构-性质关系(QSPR, quantitative structure-property relationships)方法研究了DMSO溶剂中45个有机化合物的pKa数值与电拓扑状态指数之间的定量关系, 并建立如下模型: pKa＝－1.545×E2＋0.633×E4－0.737×E5＋0.973×E6－4.048×E7－1.456×E8＋0.628×E9＋28.650. R＝0.991, S＝0.828. “逐一剔除”交叉验证的结果证明模型具有良好的稳定性和较强的预测能力. 研究结果表明电拓扑状态指数能够有效地预测有机化合物的pKa值.     

基于表面修饰聚丙烯酸合成超顺磁/荧光纳米复合粒子

在聚丙烯酸修饰的Fe₃O₄纳米粒子表面共价结合罗丹明B, 获得分散性和荧光信号均得到改善的超顺磁/荧光复合纳米材料. 分别用透射电子显微镜(TEM)、傅里叶变换红外光谱仪(FTIR)、热重分析仪、荧光光谱仪、X射线衍射仪(XRD) 和振动样品磁强计(VSM) 对合成的粒子进行了表征. 结果表明, 羧基化的Fe₃O₄纳米粒子和Fe₃O₄-荧光纳米复合材料的粒径基本相同, 为6～10 nm. Fe₃O₄-荧光纳米复合材料的饱和磁化强度为39.2 A•m²/kg, 室温下呈现超顺磁性, 具有较强的荧光信号.     

Weak AC-electric fields promote root growth and ER abundance of root cap cells

AC-electric fields of low strength and low frequency were applied to roots of garden cress (Lepidium sativum L.) growing in aqueous medium. These fields strongly affected the growth, shape and statocyte structure of the roots. A maximum growth-promoting effect was observed with a field frequency of 10 Hz and field strengths of 10⁻³ to 10⁻¹ V cm⁻¹. Growth rates of roots were similar to controls, i.e., roots growing without AC fields, at field strengths of 10⁻⁴ and 1 V cm⁻¹. Ultrastructural analyses of root cap cells showed that an AC-electric field of 10 Hz caused a significant increase in abundance of endoplasmic reticulum (ER) in the statocytes. Both phenomena, growth promotion and ER volume increase, are most likely effected by stimulation of the plasma membrane H⁺-ATPase of the root cells.     

Ultrasound-assisted electrochemical treatment for phenolic wastewater

With the rapid development of industry, especially the rapid rise of the chemical industry, the problem of water pollution is becoming more and more serious. Among them, the discharge of organic pollutants represented by phenolic substances has always been at the forefront. In this paper, ultrasound-assisted electrochemical treatment for phenolic wastewater is investigated. The effects of ultrasonic frequency, current, pH value and the amount of fly ash-loaded titanium TiO₂-Fe³⁺ particles on phenol removal from phenol-containing wastewater are investigated. The experimental results demonstrate that the removal rate of phenol in phenol-containing wastewater is the best when ultrasonic frequency is 45 kHz, power is 200 W, the current is 1.2 A, pH is 5 and the dosage of fly ash-loaded titanium TiO₂-Fe³⁺ particles is 3 g. In addition, microwave-assisted-Fenton reagent treatment for phenol wastewater is investigated. The effects of Fenton reagent dosage, initial pH value, microwave power density and radiation time on phenol degradation rate are investigated. The results show that microwave can accelerate the reaction rate, reduce the number of metal ions, save the process cost and reduce the difficulty of post-treatment. Finally, the research status of phenol wastewater treatment technology at the present stage is reviewed, and the future development direction is discussed.     

Microwave-assisted 6π-electrocyclization in water

The recent development of microwave-assisted aqueous synthesis of polyheterocyclic-fused quinoline-2-thiones through 6π-electrocyclization was highlighted.     

Dynamic behavior of a parasite-host model with general incidence

In this paper, we consider the global dynamics of a microparasite model with more general incidences. For the model with the bilinear incidence, Ebert et al. [D. Ebert, M. Lipsitch, K.L. Mangin, The effect of parasites on host population density and extinction: Experimental epidemiology with Daphnia and six microparasites, American Naturalist 156 (2000) 459-477] observed that parasites can reduce host density, but the extinction of both host population and parasite population occurs only under stochastic perturbations. Hwang and Kuang [T.W. Hwang, Y. Kuang, Deterministic extinction effect of parasites on host populations, J. Math. Biol. 46 (2003) 17-30] studied the model with the standard incidence and found that the host population may be extinct in the absence of random disturbance. We consider more general incidences that characterize transitions from the bilinear incidence to the standard incidence to simulate behavior changes of populations from random mobility in a fixed area to the mobility with a fixed population density. Using the techniques of Xiao and Ruan [D. Xiao, S. Ruan, Global dynamics of a ratio-dependent predator-prey system, J. Math. Biol. 43 (2001) 268-290], it is shown that parasites can drive the host to extinction only by the standard incidence. The complete classifications of dynamical behaviors of the model are obtained by a qualitative analysis.