Rapid and effective adsorption of lead ions on fine poly(phenylenediamine) microparticles

Fine microparticles of poly(p-phenylenediamine) (PpPD) and poly(m-phenylenediamine) (PmPD) were directly synthesized by a facile oxidative precipitation polymerization and their strong ability to adsorb lead ions from aqueous solution was examined. It was found that the degree of adsorption of the lead ions depends on the pH, concentration, and temperature of the lead ion solution, as well as the contact time and microparticle dose. The adsorption data fit the Langmuir isotherm and the process obeyed pseudo-second-order kinetics. According to the Langmuir equation, the maximum adsorption capacities of lead ions onto PpPD and PmPD microparticles at 30 degrees C are 253.2 and 242.7 mg g(-1), respectively. The highest adsorptivity of lead ions is up to 99.8 %. The adsorption is very rapid with a loading half-time of only 2 min as well as initial adsorption rates of 95.24 and 83.06 mg g(-1) min(-1) on PpPD and PmPD particles, respectively. A series of batch experiment results showed that the PpPD microparticles possess an even stronger capability to adsorb lead ions than the PmPD microparticles, but the PmPD microparticles, with a more-quinoid-like structure, show a stronger dependence of lead-ion adsorption on the pH and temperature of the lead-ion solution. A possible adsorption mechanism through complexation between Pb(2+) ions and ==N-- groups on the macromolecular chains has been proposed. The powerful lead-ion adsorption on the microparticles makes them promising adsorbents for wastewater cleanup.     

On the Harris Recurrence of Iterated Random Lipschitz Functions and Related Convergence Rate Results

A result by Elton⁽⁶⁾ states that an iterated function system

Template polymerization of multiacrylate

By reacting poly (2-hydroxyethyl methacrylate) with acryloyl chloride, multiacrylate connected through a covalent bond with polymethacrylate chain (template) has been obtained. The free-radical polymerization of multiacrylate in dilute dioxane solutions at 75°C and 85°C was examined by IR spectrophotometry and the distribution of molecular weights of the resultant products was evaluated by gel permeation chromatography. The findings show that under selected conditions the polymerization proceeds along ordered acrylic double bonds on the template and results in a ladder-type polymer. At a temperature of 85°C, in addition to the intramolecular cyclopolymerization, intermolecular reactions proceed to a minor extent. © 1994 John Wiley & Sons, Inc.     

SPECTRUM OF THE MICROMASER INJECTED WITH Λ-TYPE THREE-LEVEL ATOMS

The spectrum of the micromaser injected with Λ-type three-level atoms is studied. The spectrum has a Lorentzian lineshape and its central frequency has a shift. The effects of various parameters (for example, the atomic center-of-mass velocity, the cavity-length, the one-photon detuning, the ratio of the atomic injection rate to the cavity decay rate and the number of thermal photons) on the linewidth and the frequency shift are examined. The spectrum shows very different features in different velocity regimes, i.e., in the fast-atom regime, in the intermediate-velocity-atom regime, and in the slow-atom regime.     

Excitation spectrum of Hubbard model with infinite electron repulsion on strip‐type triangular lattices

The estimations of the stability region of the lattice ferromagnetic ground state in the space of model parameters are found. For the triangular lattice strip formed by L segments with the total number of electrons N=L+1 we derived the effective Hamiltonians describing the low‐energy states of the strips and obtained the analytical estimations for above stability region. The possibility of the magnetic transition with the jump of the ground‐state spin between minimal and maximal values has also been shown. For the strip with N=L and an alternating value of the one‐site potential energy, we have obtained the exact relation between electron parameters, which provides the ferromagnetic character of the lattice ground state. © 2001 John Wiley & Sons, Inc. Int J Quant Chem 81: 253–259, 2001     

三能级级联型介质的正常色散与反常色散

建议利用三能级级联型介质实现从正常色散到反常色散的变换.在级联型介质中,两个偶极跃迁分别与两个不同的相干场耦合.探测场或者与上跃迁耦合,或者与下跃迁耦合.利用谐振展开方法把介质密度矩阵元方程组转换成在定态条件下系数不依赖时间的方程组,然后用逆矩阵求解,并用此解求得介质的吸收与色散谱.结果表明,对于每一种情形,在同一频率区域系统既能呈现正常色散,也能呈现反常色散.通过改变耦合到探测跃迁的驱动场强度,可以实现从正常色散到反常色散的转换.级联系统与Λ和V系统之间呈现两个差别.第一,如果利用Λ和V系统的两个跃迁同时与探测场耦合获得色散转换,则需要利用近简并能级,而本方案利用缀饰态获得等价的近简并能级,其间距由相应驱动场强度进行控制.第二,如果利用Λ和V系统的单个跃迁耦合探测场建立色散转换,当退耦合态起主要作用时,系统不能产生色散转换,而级联系统不涉及退耦合态.     

通过四个纠缠态粒子来实现未知的三个纠缠态粒子的量子几率隐形传输

提出一种分别利用四个三态粒子的最大纠缠态和非最大纠缠态作为量子通道来传输一未知的三个三态粒子纠缠态的方案.首先考察量子通道是最大纠缠态的情况,然后进一步考察量子通道是非最大纠缠态的情况,同时发现在后者情况时,通过引进一个辅助粒子,并构造一幺正变换矩阵,即可以一定的几率完成该三态粒子纠缠态的隐形传输.     

Synthesis and characterization of a helical step‐ladder polyarylene

A helical step‐ladder polyarylene incorporating chiral (R)‐2,2′‐dioctoxy‐1,1′‐binaphthyl units was synthesized for the first time. The first step involved the preparation of a precursor poly(arylene ketone) via a palladium‐mediated Suzuki‐type cross‐coupling reaction with the aid of microwave heating. Two polymer‐analog reaction steps, the reduction of the keto groups to tertiary alcohol functionalities and subsequent intramolecular Friedel–Crafts cyclization, gave a step‐ladder polymer ( 6 ) in good yields with reasonable mean average molecular weights greater than 13,000. The regioselective cyclization pattern in the α position of the naphthalene core was confirmed by a comparison of the NMR data of the polymer with those of the corresponding model ladder oligomers, 12 and 13 , and also a single‐crystal structure of 13 . The optical spectra of the oligomers and polymers indicated that there was little electronic interaction across the binaphthyl units. The circular dichroism spectrum of 6 exhibited a strong bisignate Cotton effect in the π–π* absorption region of the planar chromophores, which reflected the strong exciton coupling within the helical polymer chain. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5533–5545, 2006     

An Analytical Solution to the Model for Single Three-Level Trapped Ion Driven by External Fields

The interaction of a single three-level trapped ion with two laser beams has been studied theoretically. With application of two successive unitary transformations, an analytical solution to this quantum system has been obtained.