On the conformal mappings in the unit disk fixing arbitrarily many boundary points

In this paper, we give a method of constructing conformal mappings defined in the unit disk which can fix arbitrarily many points on the unit circle.     

Polyvinylidene fluoride/polystyrene hybrid fibers with high ionic conductivity and enhanced mechanical strength as lithium-ion battery separators

Journal of Solid State Electrochemistry - Ionic conductivity is an important separator parameter influencing the cycle life and rate capability of lithium-ion batteries (LIBs). To improve the ionic...     

Preliminary study on aerosol particle addition calibration method for on-line quantitative analysis of airborne radioactive particles with ICP-MS

An ambient aerosol concentration enrichment system coupled with ICP-MS for real-time monitoring of airborne radioactive particles is now under development. ICP-MS is very sensitive to sample introduction conditions, so it is necessary to develop an easy-use calibration method for on-line quantitative analysis in field application. In this paper, a calibration method using standard solution instead of monodisperse particles was established and validated preliminarily. First of all, four parameters for the method were determined experimentally, including: uptake flow rate and nebulisation efficiency of the Microconcentric nebuliser, nebulisation/transport efficiency of Aridus Desolvating Sample Introduction System, and Relative Sensitivity Factor between ¹⁵⁹?Tb and ¹⁷⁴?Yb. Then, monodisperse terbium nitrate particles were generated by a commercial Vibrating Orifice Aerosol Generator. Continuous aerosols of ytterbium nitrate droplets were nebulised from standard solution. They were mixed together, desolvated through the membrane dryer and introduced into ICP-MS for on-line analysis of terbium nitrate particles. The air sampled from nuclear environment was also introduced into ICP-MS to investigate the effect of flow rate on instrument responses. Finally, atom numbers of ¹⁵⁹?Tb in discrete terbium nitrate particles were determined using the calibration method and compared to the calculated value. Results show that when air flow rate increase from 10?mL?min^?1 to 100?mL?min^?1, the ratio of ¹⁵⁹?Tb ion count to ¹⁷⁴?Yb ion intensity keeps constant although instrument sensitivity decreases by a factor of 25. The relative standard deviation of ¹⁵⁹?Tb atom number measured is better than 18%. The discrepancy with the calculated value could be attributed to the over-estimation of atom number in the particles generated by VOAG because there was some liquid leakage in the VOAG.     

Breakdown-quenching characteristics and mechanisms for silicon photomultipliers

Some deviant breakdown-quenching characteristics of silicon photomultipliers are demonstrated and their physical mechanisms are explored. “Twice breakdown” phenomenon, “flat-topped” avalanche pulses and the determination method of the real breakdown voltage of the detector are analyzed. These characteristics are explained by the integration model in terms of avalanche threshold current based on the Haitz's equivalent circuit model. The reasoning results show that the maximum over-voltage for a normal operating silicon photomultiplier equals the product of the avalanche threshold current and the quenching resistor of the avalanche photo-diode (APD) pixel, approximately. Moreover, the model and results can be extended to other small avalanche junctions with quenching resistor.     

Crucial factors affecting the physicochemical properties of sol–gel produced Fe3O4@SiO2–NH2 core–shell nanomaterials

Multifunctional nanomaterials with task-specific physicochemical properties, especially core?Cshell nanostructures with Fe₃O₄ core and NH₂-functional shells (Fe₃O₄@SiO₂?CNH₂), have been extensively investigated as high-performance adsorbents, catalysts and catalyst supports; and in most cases the controllable sol?Cgel technique is the choice for fabrication of this kind of widely applied materials. Herein, we demonstrated that mono-dispersed and spherical Fe₃O₄@SiO₂?CNH₂ nanomaterials with magnetic response core, NH₂-functional shell structure can be facilely prepared by co-condensation of TEOS with APTMS using a versatile sol?Cgel process. It was shown that the proper usage of APTMS and appropriate pre-hydrolysis time of TEOS were crucial and key steps for formation of highly uniform and desirable amino loading Fe₃O₄@SiO₂?CNH₂ materials. The TEOS pre-hydrolysis and the critical time (around 90?min) before the addition of APTMS prove to be vital for uniform structure evolution, while the appropriate concentration of APTMS (~2.28?mmol?L^?1 in our system) leads to well-dispersed materials with relatively high loading of amino functionality. The as-prepared Fe₃O₄@SiO₂?CNH₂ magnetic nanoparticles prepared under optimum conditions possessing superparamagnetic behavior, uniform core?Cshell structure (~200?nm in diameter), relatively large BET surface area (~138?m²/g) and high incorporation of amino-functionality (~2.90?wt?%).     

Cuso4‐amine redox‐initiated radical polymerization of methyl methacrylate mediated by a CuCl2 complex: Homogeneous reverse ATRP

Kinetic results of CuSO₄/2,2'‐bipyridine(bPy)‐amine redox initiated radical polymerization of methyl methacrylate (MMA) at 70 to 90 °C in dimethylsulfoxide suggest that such initiation is characteristic of a slow rate and a low initiator efficiency, but tertiary amines exhibit a relatively higher rate. UV‐Vis spectroscopy confirms the alpha‐amino functionality of PMMA chains. CuCl₂/bPy successfully mediates the redox‐initiated radical polymerization of MMA with aliphatic tertiary amines in a fashion of slow‐initiated reverse atom transfer radical polymerization (ATRP), i.e. both the initiator efficiency of aliphatic tertiary amines and the average molecular weight of PMMA increase gradually, while the molecular weight distribution remains narrow but become broader with the conversions. As the PMMA chains contain alpha amino and omega C‐Cl moieties, UV‐induced benzophenone‐initiated radical polymerization and Cu^ICl/bPy‐catalyzed ATRP initiated from PMMA lead to block copolymers from terminal functionalities. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2562‐2578