Nonlinear Asymptotic Stability of the Lane-Emden Solutions for the Viscous Gaseous Star Problem with Degenerate Density Dependent Viscosities

The nonlinear asymptotic stability of Lane-Emden solutions is proved in this paper for spherically symmetric motions of viscous gaseous stars with the density dependent shear and bulk viscosities which vanish at the vacuum, when the adiabatic exponent \({\gamma}\) lies in the stability regime \({(4/3, 2)}\), by establishing the global-in-time regularity uniformly up to the vacuum boundary for the vacuum free boundary problem of the compressible Navier-Stokes-Poisson systems with spherical symmetry, which ensures the global existence of strong solutions capturing the precise physical behavior that the sound speed is \({C^{{1}/{2}}}\)-Hölder continuous across the vacuum boundary, the large time asymptotic uniform convergence of the evolving vacuum boundary, density and velocity to those of Lane-Emden solutions with detailed convergence rates, and the detailed large time behavior of solutions near the vacuum boundary. Those uniform convergence are of fundamental importance in the study of vacuum free boundary problems which are missing in the previous results for global weak solutions. Moreover, the results obtained in this paper apply to much broader cases of viscosities than those in Fang and Zhang (Arch Ration Mech Anal 191:195–243, 2009) for the theory of weak solutions when the adiabatic exponent \({\gamma}\) lies in the most physically relevant range. Finally, this paper extends the previous local-in-time theory for strong solutions to a global-in-time one.     

Separation behavior of basic compounds on unbonded silicon oxynitride and silica high‐performance liquid chromatography stationary phases with reversed‐phase eluents

Unbonded silicon oxynitride and silica high‐performance liquid chromatography stationary phases have been evaluated and compared for the separation of basic compounds of differing molecular weight, pK_a, and log D using aqueous/organic mobile phases. The influences of percentage of organic modifier, buffer pH, and concentration in the mobile phase on base retention were investigated on unbonded silicon oxynitride and silica phases. The results confirmed that unbonded silicon oxynitride and silica phases demonstrated excellent separation performance for model basic compounds and both the unbonded phases examined possessed a hydrophobic/adsorption and ion‐exchange character. The silicon oxynitride stationary phase exhibited high hydrophilicity compared with silica with a reversed‐phase mobile phase. An ion‐exclusion‐type mechanism becomes predominant for the separation of three aimed bases on the silicon oxynitride column at pH 2.8. Different from silicon oxynitride stationary phase, no obvious change for the retention time of three model bases on silica stationary phase at pH 2.8 can be observed.     

Functionalized anodic aluminum oxide (AAO) membranes for affinity protein separation

An ideal affinity membrane should own well uniformities. However, most existing microporous membranes used as affinity matrices generally have wide pore size distribution and some thickness variation. In this paper, chitosan (CS)–anodic aluminum oxide (AAO) composite membrane with excellent uniformities, such as narrow pore size and porosity distribution, as well as uniform membrane thickness, was fabricated, for the first time. Cu²⁺-attached affinity membrane was obtained by immobilizing Cu²⁺ on the CS–AAO membrane. The contents of CS and Cu²⁺ of affinity membranes were ∼49.7 and 27.15 mg/g membrane, respectively. The Cu²⁺-attached affinity membranes were used to recover a model protein, hemoglobin, from hemoglobin–phosphate solution (batch manner) and from the hemolysate (dynamic manner). The protein adsorption indicated that the adsorption capacity of hemoglobin was ∼17.5 mg/g membrane, and the adsorption isotherm fitted the Freundlich model well. Elution of protein showed desorption ratio was up to 91.2% using 0.5 M imidazole aqueous solution as the desorption agent. The adsorption capacities of all the tested affinity membranes did not significantly change during the repeated adsorption–desorption operations. The result of dynamic experiment showed Cu²⁺-attached affinity membranes can well purify the hemoglobin from the red cell lysate.     

Novel piperidine nitroxide derivatives: Synthesis,electrochemical and antioxidative evaluation

Novel paramagnetic materials ( 3a , 3b , 4a and 4b ) based on heterocyclic dyes ( 2a and 2b ) and one stable nitroxide radical (4‐NH₂‐TEMPO) were synthesized. EI‐MS, elemental analysis and FT‐IR spectral data confirmed the structures of the newly synthesized compounds. In addition, the cyclic voltammetry, the antioxidant activity and reactive oxygen species (ROS) scavenging properties of these compounds are discussed in this paper.     

Double UV polymerisation with variable temperature-controllable selective reflection of polymer-stabilised liquid crystal (PSLC) composites

In this study, a method of preparing wide-band reflection cholesteric liquid crystals (CLCs) films by UV-radical polymerisation in combination with UV-cationic polymerisation is proposed. Because the helical twisting power (HTP) of the chiral dopant decreases with increasing temperature and the polymerisation rate of UV-initiated free radical polymerisation is faster than UV-initiated cationic polymerisation, by adjusting the temperature, broadband reflective films with non-uniform pitch distribution are obtained. The fractured surface of the polymer network of the broadband reflective films is observed by scanning electron microscopy (SEM), which reveals the presence of non-uniform pitch distribution. In addition, the influences of monomer concentration, UV light intensity and UV curing time on the consequent non-uniform pitch distribution have been studied.     

A simple strategy for the synthesis of Zn-IL-SBA-15 by sol–gel and the application in desulfurization

Journal of Sol-Gel Science and Technology - SBA-15 functionalized with both zinc ions and ionic liquids was simply synthesized by sol–gel method. The characterization results of Fourier...     

Low-threshold pure UV electroluminescence from n-ZnO:Al/i-layer/n-GaN heterojunction

Ultraviolet (UV) electroluminescence (EL) of n-ZnO:Al (AZO)/i-layer/n-GaN heterojunctions with different intrinsic layers has been obtained. Rectifying behavior and EL spectra of the heterojunctions are investigated at room temperature. Under positive voltage, a dominant UV emission peak around ～370 nm is observed for both AZO/i-ZnO/n-GaN and AZO/i-MgO/n-GaN heterojunctions. Nevertheless, the UV emission peak intensity of AZO/i-MgO/n-GaN heterojunction is much stronger than that of AZO/i-ZnO/n-GaN heterojunction at the same voltage. The threshold voltage of AZO/i-MgO/n-GaN heterostructured device is as low as 2.3 V. The difference of EL spectra and the emission mechanism in these devices are discussed.     

A metal–organic gel‐based fluorescent chemosensor for selective Al3+ detection

As an important metal element, aluminium has a significant impact on the environment and human health, and thus the detection of Al³⁺ has become the subject of much research. We synthesized a Ni(II)‐based metal–organic gel (Ni‐MOG), which can serve as an Al³⁺ fluorescence sensor with high selectivity and sensitivity, the limit of detection being calculated to be 0.5 μM. In addition, a composite film was further fabricated by hybridization of this Ni‐MOG with poly(vinyl alcohol). The composite film produced a rapid fluorescence response to Al³⁺ solutions at concentrations above 5 × 10^?5 M in 5 min. The Ni‐MOG composite film can also be successfully applied for the sensitive detection of Al³⁺ in real samples of tap water and seawater. The effective detection of Al³⁺ described in this contribution provides a new insight into water quality monitoring and has promising application value.