吸附法处理水体中溶解性有机物的研究进展

综述了溶解性有机物(DOM)的性质、危害以及各种吸附剂在DOM去除中的研究现状.总结和介绍了吸附法处理DOM的主要机理和作用孔径,并对树脂吸附法处理DOM的研究提出了一些建议和展望.     

噻吩基卟啉衍生物的单光子和双光子吸收性质的理论研究

本文理论上研究了两个系列的噻吩基卟啉衍生物,这种衍生物在可见光区具有大的双光子吸收截面。用密度泛函理论和ZINDO-SOS方法,计算了分子的几何构型、电子结构,单光子和双光子吸收性质。结果显示噻吩单元的数目影响分子的单光子和双光子吸收性质。具有两个或三个噻吩基团的噻吩基卟啉衍生物在较大范围内具有可用于实际应用中的双光子吸收响应,这一性质有利于这类分子在光限幅中的应用。插入乙炔基有利于扩大共轭范围,增加分子的双光子吸收截面。同时,乙炔基团的加入导致了单光子和双光子波长的红移。从高透明性和相对大的非线性光学响应考虑,噻吩基卟啉衍生物是一类有应用前景的双光子吸收材料。     

Enzymatically active colloidal crystal arrays

We report the construction of three-dimensional (3D) colloidal crystal arrays (CCA) and hollow colloidal crystal arrays (HCCA) derived from the self-assembly of polyelectrolytes (PE)-coated polystyrene (PS) particles and their use as models of high surface area systems to immobilize peroxidase (POD). POD molecules could infiltrate into the deep layers of CCA and HCCA through their interconnected pores and strongly adsorbed at the PE shell of the colloidal particles. And the total enzyme loading amount and bioactivities increased linearly with the thickness of the CCA till ca. 10 mum. Compared with flat substrates with the same geometrical area, CCA and HCCA exhibit much higher enzyme loading abilities (approximately 43 and 53 times respectively) and the resulting bioactivities (approximately 35 and 41 times respectively) due to their inherently higher surface area and 3D interconnected porous structures. In addition, HCCA could load approximately 30% more POD than CCA because some POD molecules could infiltrate into the interior of the hollow capsule under salt condition.     

The permanence and global attractivity of a Kolmogorov system with feedback controls

In this paper, we study the permanence and global asymptotic behavior for a Kolmogorov system with feedback controls. By means of lower and upper averages of a function, the average conditions for permanence, global attractivity and extinction of this system are established respectively. The corresponding results given by Chen in [F. Chen, The permanence and global attractivity of Lotka–Volterra competition system with feedback controls, Nonlinear Anal. 7 (2006) 133–143] and Zhao in [J.D. Zhao, J.F. Jiang, A.C. Lazer, The permanence and global attractivity in a nonautonomous Lotka–Volterra system, Nonlinear Anal. Real World Appl. 5 (2004) 265–276] are extended and improved.     

弹性半空间地基上圆形基础板的位移场和应力场

针对弹性半空间地基上圆形基础底板的弯曲问题,根据地基土壤的受力特性和已有实验研究成果,假设圆形基础底板底部与地基土壤之间是由竖向集中荷载引起的接触应力分布形式,采用板的弯曲理论和通过数值积分及最小二乘法拟合的方法,推导出完全满足边界条件的弹性半空间地基上圆形基础底板上部受集中力作用、下部受幂函数形式连续分布荷载作用时的位移场、径向和环向应力场的表达式。尽管圆形基础板属于中厚度板,但是该表达式的计算精度和可靠性得到了有限元分析软件ANSYS验证。     

Some new insights into the Liu system

The present work is devoted to giving new insights into the Liu chaotic system. The local dynamical entities, such as the number of equilibria, the stability of hyperbolic equilibria, and the stability of the nonhyperbolic equilibrium obtained by using the center manifold theorem, the pitchfork bifurcation, the degenerate pitchfork bifurcation, and Hopf bifurcations, are all analyzed when the parameters are varied in the space of parameters. All the closed orbits of the system are also proven rigorously to be nonplanar but only to be curves in space. Moreover, the existence of singularly degenerate heteroclinic cycles for a suitable choice of the parameters is investigated.     

General Hosford yield functions of orthorhombic materials

Although the Hosford yield function is more suitable for describing both the yielding and the plastic deformation of orthorhombic materials than the Hill quadratic yield function, the Hosford yield function suffers from the restriction that the loading has to be coaxial with the orthotropy of the materials. To relax this restriction, herein we present a new general Hosford yield function for the orthorhombic materials. The new general Hosford yield function is suitable to any stress state of the orthorhombic materials. When η = 2, the new general Hosford yield function becomes the Hill quadratic yield function. The new general Hosford yield function is more general than the general Hosford yield function of Huang and Man (Int J Plast 41:97–123, 2013), which covers only weakly-textured sheets of cubic metals. Two examples show that the new general Horsford yield function with suitable η value gives much better fits than those of the Hill quadratic yield function (η = 2).     

球磨处理对碳纳米管吸附苯胺的影响

探讨了机械球磨处理后碳纳米管的微观结构变化,并研究了球磨时间对其吸附苯胺的影响.实验结果表明,通过机械球磨可获得大量不同长度的开口碳纳米管,且球磨时间越长,碳纳米管的长度越短,开口程度越明显.球磨处理后碳纳米管中堆积孔孔径明显变小,管内孔孔径基本保持不变.处理后的碳纳米管与处理前相比,其对苯胺的吸附量显著增加,管内发生的毛细凝聚在吸附中起到了重要的作用.     

室温MnO_x上O_3氧化脱除空气中甲醛

采用氧化还原法制备了MnOx催化剂,X射线衍射结果表明其主要为无定形结构.在甲醛和臭氧浓度分别为137和642mg/m3,相对湿度为56%(25oC),GHSV为2×105h-1条件下,MnOx催化剂上O3可将甲醛全部氧化为CO2,反应150min内甲醛转化率和CO2选择性一直保持在～100%.另外,当臭氧与甲醛的摩尔比约为2:3,即显著低于化学计量比时,CO2选择性仍可达～100%.采用傅里叶变换红外光谱仪在线分析了甲醛氧化反应产物,未检测到任何副产物,从而确认了MnOx催化剂上O3对甲醛的完全氧化.     

Amperometric hydrogen peroxide biosensor based on a glassy carbon electrode modified with polythionine and gold nanoparticles

We report on a novel hydrogen peroxide biosensor that was fabricated by the layer-by-layer deposition method. Thionine was first deposited on a glassy carbon electrode by two-step electropolymerization to form a positively charged surface. The negatively charged gold nanoparticles and positively charged horseradish peroxidase were then immobilized onto the electrode via electrostatic adsorption. The sequential deposition process was characterized using electrochemical impedance spectroscopy by monitoring the impedance change of the electrode surface during the construction process. The electrochemical behaviour of the modified electrode and its response to hydrogen peroxide were studied by cyclic voltammetry. The effects of the experimental variables on the amperometric determination of H₂O₂ such as solution pH and applied potential were investigated for optimum analytical performance. Under the optimized conditions, the biosensor exhibited linear response to H₂O₂ in the concentration ranges from 0.20 to 1.6?mM and 1.6 to 4.0?mM, with a detection limit of 0.067?mM (at an S/N of 3). In addition, the stability and reproducibility of this biosensor was also evaluated and gave satisfactory results.