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.     

Convergence analysis of a balancing domain decomposition method for solving a class of indefinite linear systems

A variant of balancing domain decomposition method by constraints (BDDC) is proposed for solving a class of indefinite systems of linear equations of the form (K?σ²M)u=f, which arise from solving eigenvalue problems when an inverse shifted method is used and also from the finite element discretization of Helmholtz equations. Here, both K and M are symmetric positive definite. The proposed BDDC method is closely related to the previous dual–primal finite element tearing and interconnecting method (FETI‐DP) for solving this type of problems (Appl. Numer. Math. 2005; 54 :150–166), where a coarse level problem containing certain free‐space solutions of the inherent homogeneous partial differential equation is used in the algorithm to accelerate the convergence. Under the condition that the diameters of the subdomains are small enough, the convergence rate of the proposed algorithm is established, which depends polylogarithmically on the dimension of the individual subdomain problems and which improves with a decrease of the subdomain diameters. These results are supported by numerical experiments of solving a two‐dimensional problem. Copyright © 2009 John Wiley & Sons, Ltd.     

溅射功率对脉冲磁控溅射沉积Cu2O薄膜结构和光学性能的影响

利用脉冲磁控溅射制备技术,采用单质金属铜靶作为溅射靶,在氧气(O2)和氩气(Ar)的混合气氛下,在石英玻璃衬底上制备了Cu2O薄膜.研究了溅射功率对脉冲反应磁控溅射沉积法在室温下对生长Cu2O薄膜结构、表面形貌及光学性能的影响.结果表明,在O2、Ar流量比(O2/Ar)为30∶80的气氛条件下,在60～90 W的溅射功率范围内可获得＜ 111＞取向的Cu2O薄膜;薄膜的表面粗糙度的均方根值随溅射功率的增加而增大;薄膜的光谱吸收范围为300 ～670 nm,不同溅射功率下制备的薄膜均在430 nm附近出现明显的带边吸收,其光学带隙(Eg)在2.15～2.53 eV之间变化.     

新型核壳结构纳米催化剂的三效催化活性及热稳定性

从Pd纳米粒子出发制备了具有核壳结构的新型纳米Pd@SiO₂/Ce_0.4Zr_0.6O₂三效催化剂及作为参比的Pd/Ce_0.4Zr_0.6O₂催化剂, 采用X射线衍射、 透射电子显微镜、 氢气程序升温还原和氮气低温吸附-脱附等技术对催化剂的物化性质进行了表征, 研究了Pd@SiO₂/Ce_0.4Zr_0.6O₂和Pd/Ce_0.4Zr_0.6O₂催化剂的三效反应催化活性和热稳定性. 结果表明, SiO₂壳层可以抑制Pd粒子的团聚, 同时还能抑制Pd物种的再分散, 减少Pd的流失. 具有核壳结构的纳米Pd@SiO₂/Ce_0.4Zr_0.6O₂催化剂具有更好的三效催化活性和更高的热稳定性.     

Size and shape effects on magnetic properties of Ni nanoparticles

Pure Ni nanoparticles ranging in size from 24 to 200 nm are prepared via thermal decomposition of nickel acetylacetonate in oleylamine. The as-prepared Ni particles change from spherical to dendritic or starlike with increasing precursor concentration. The particles are stable because the organic coating occurs in situ. Magnetic measurement reveals that all the Ni nanoparticles are ferromagnetic and show ferromagnetic–paramagnetic transitions at their Curie points. The saturation magnetization M_s is size-dependent, with a maximum value of 52.01 and 82.31 emu/g at room temperature and 5 K, respectively. The coercivity decreases at first and then increases with increasing particle size, which is attributed to the competition between size effect and shape anisotropy. The Curie temperature T_c is 593, 612, 622, 626 and 627 K for the 24, 50, 96, 165 and 200 nm Ni nanoparticles, respectively. A theoretical model is proposed to explain the size-dependence of Ni nanoparticle Curie temperature.     

Highly selective stir bar coated with dummy molecularly imprinted polymers for trace analysis of bisphenol A in milk

A water compatible molecularly imprinted polymers (MIPs) coated stir bar for bisphenol A(BPA) was prepared with 3,3',5,5'-tetrabromobisphenol A as the dummy template molecule in this study. The dummy molecularly imprinted polymers coated stir bar (DMIPs-SB) showed better selectivity than the bars coated with polydimethylsiloxane or non-imprinted polymers when used to extract BPA and its three analogues. The saturated adsorption amount of the DMIPs coating was 3.0 times over that of the non-imprinted polymers coating. To achieve the optimum extraction performance, several parameters, including extraction and desorption time, pH value, adsorption temperature and stirring speed were investigated. The high-performance liquid chromatography combined with the DMIPs-SB was employed in the analysis of BPA in aqueous solution. The linear range of BPA concentration in aqueous medium was 0.0228-2.28 ng/mL with correlation coefficient of 0.9994 and the detection limit was about 6.84 × 10(-3) ng/mL based on three times ratio of signal to noise. This method was directly applied to the determination of trace BPA in milk with satisfactory results.     

Dummy molecularly imprinted polymers as the coating of stir bar for sorptive extraction of bisphenol A in tap water

A unique stir bar coated with dummy molecularly imprinted polymers for bisphenol A was prepared by sol-gel technique. The scanning electron microscopic image of the coating presented a homogeneous surface with a thickness of about 57 ± 2.5 μm. The Fourier transform infrared spectrum of the coating proved the incorporating of dummy molecularly imprinted polymers with the sol-gel network. When used to extract bisphenol A from aqueous solution containing bisphenol A and its three analogs (4-tert-butylphenol, 4,4'-dihydroxybiphenyl, and 3,3',5,5'-tetrabromo-bisphenol A). Dummy molecularly imprinted polymers-coated stir bar showed better selectivity than the bars coated with polydimethylsiloxane or non-imprinted polymers. The extraction conditions including stirring speed, pH, and extraction time were optimized. After back extraction with methanol, the extracts were analyzed by high-performance liquid chromatography-fluorescence detection. The linear range was 0.0228-0.456 ng/mL with correlation coefficient of 0.9994 and the detection limit was about 5.70 × 10(-3) ng/mL based on three times ratio of signal-to-noise. The method was applied to the determination of trace bisphenol A in tap water.     

Soluble and Green‐light‐emitting Oligo(9‐fluorenylideneacetic acid): Electrosynthesis and Characterization

A novel semiconducting oligo(9‐fluorenylideneacetic acid) (OFYA) with good redox activity and stability was successfully electrosynthesized by direct anodic oxidation of 9‐fluorenylideneacetic acid (FYA) in CH₂Cl₂ containing boron trifluoride diethyl etherate (BFEE) as the supporting electrolyte. The as‐formed OFYA film was readily soluble in dimethyl sulfoxide and tetrahydrofuran, and partly soluble in water, alcohol, acetonitrile and acetone. FT‐IR and ¹H NMR spectra, together with computational results proved that FYA was probably polymerized through the coupling at C(2) and C(7) positions. Further, OFYA was a typical green light‐emitter with maximal emission at 555 nm and its fluorescence quantum yield was distinctly improved in comparison with that of the monomer. The oligomer was also studied by UV‐vis spectroscopy, MALDL‐TOF mass spectrometry, and thermal analysis, respectively.     

Construction of graphdiyne nanowires with high-conductivity and mobility

GDNWs (graphdiyne nanowires) have successfully been constructed which exhibit a very high quality defect-free surface using the VLS growth process. Measurement of electrical properties showed that the GDNWs produced are excellent semiconductors with a conductivity of 1.9 × 10(3) S m(-1) and a mobility of 7.1 × 10(2) cm(2) V(-1) s(-1) at room temperature. The results have confirmed that GDNW is indeed a promising and key novel material in electronic and photoelectric fields for both fundamental and potentially practical applications.     

A random map implementation of implicit filters

Implicit particle filters for data assimilation generate high-probability samples by representing each particle location as a separate function of a common reference variable. This representation requires that a certain underdetermined equation be solved for each particle and at each time an observation becomes available. We present a new implementation of implicit filters in which we find the solution of the equation via a random map. As examples, we assimilate data for a stochastically driven Lorenz system with sparse observations and for a stochastic Kuramoto–Sivashinsky equation with observations that are sparse in both space and time.