原料中正丁烷组分对烷基化装置设计的影响

烷基化装置原料中的正丁烷组分作为烷基化反应的惰性组分,在装置设计中并不是我们重点关注的对象;但其在原料中浓度的高低,会影响烷基化油产品的收率和产品质量,同时对装置分馏部分设计有着较大的影响,通过对原料中正丁烷组分含量的分析,有助于我们在前期设计阶段更准确的估算装置分馏系统的设备规格及装置消耗。     

CdS/TiO_2电极的制备及其光电性能的研究

采用电化学沉积方法制备CdS/TiO2电极并研究其光电催化性能,比较了不同电压、反应物浓度、不同电解质等条件下CdS/TiO2电极所显示的光电性能。另外,将CdS/TiO2与CdS/Ti电极进行光电性能比较,得出了在相同沉积时间下CdS/TiO2电极的光电性能比CdS/Ti电极稳定,产生的光电流略有提高的结论,在多数方面都优于CdS/Ti电极。     

离子筛MnO_2·0.4H_2O的固相法制备及特性研究

以单水氢氧化锂和四氧化三锰为原料,用固相法制备出锂离子筛锰酸锂,改变n(锂)/n(锰)之后,用同样的方法制备出另一物质Li1.33Mn1.67O4,经硝酸洗涤脱锂后制备了锂离子筛MnO2·0.4H2O。测定了酸洗时前驱体的锂洗脱率、锰溶损率,研究了锂离子筛MnO2·0.4H2O的饱和吸附量、稳定性、pH滴定曲线。结果表明,前驱体Li1.33Mn1.67O4经硝酸二次酸洗后,锂洗脱率和锰溶损率分别为62.7%和6.0%。在含0.1 mol/L氢氧化钠和10 mmol/L氯化锂的溶液中,经固相法制备的锂离子筛MnO2·0.4H2O对锂离子的饱和吸附量达到24.6 mg/g,并且具有较好的稳定性,pH滴定曲线表明锂离子筛对锂离子具有很好的选择性。     

The Competitive and Combining Effects of Grain Boundary and Fe/Mo Antisite Defects on the Low‐Field Magnetoresistance in Sr2FeMoO6

Sr₂FeMoO₆ ceramics with different Fe/Mo antisite defect (ASD) concentrations and grain‐boundary (GB) properties were prepared. The competitive and combining effects of GB and Fe/Mo ASD on the transport and magnetoresistance were discussed. The GB properties, that is, intergrain coupling strength, positively related with resistivity value, is extremely sensitive to the total flux of reducing gas, in general, lower total gas flux leads to larger resistivity, thus stronger intergrain coupling strength, and then the contributions of GB effect to low‐field magnetoresistance (LFMR) increase appreciably regardless of the amount of ASD. In detail, when ASD concentration is less than 26%, LFMR is dominantly controlled by the GB effect. However, the suppressed ASD effect on LFMR behavior comes to play when the ASD content is larger than or equal to 26%, where the GB and ASD effects contribute together to the LFMR.     

Coloration and Nonlinear Optical Properties of ZnTe Quantum Dots in ZnO–TeO2–P2O5 Glasses

ZnO–TeO₂–P₂O₅ glasses were prepared by melt‐quenching method. The color of the glass samples changed from colorless to pale red and dark red with increasing TeO₂ content. Coloration mechanism and nonlinear optical properties of ZnO–TeO₂–P₂O₅ glasses have been investigated. Raman spectra and transmission electron microscope measurements indicated the precipitation of ZnTe quantum dots in the glasses and ZnTe quantum dots are the origin of coloration. Z‐scan technique was used to examine the nonlinear optical properties of the glasses. The glass sample with 30 mol% TeO₂ exhibits large third‐order nonlinear optical susceptibility of 10^?11 esu.     

Sintering Behavior and Dielectric Properties of Ultra‐Low Temperature Fired Silver Molybdate Ceramics

Ag₂MoO₄ ceramic was prepared by using the solid‐state reaction method, which could be sintered at 450°C for 2 h, having a relative permittivity of 8.08, a Qf value of 17 000 GHz, and a temperature coefficient of resonance frequency about ?133 ppm/°C. Ag₂MoO₄ ceramic was chemically compatible with silver but reacted seriously with aluminum to form (Ag_0.5Al_0.5)MoO₄ during the sintering. The fitting of infrared spectra and the Shannon's additive rule were employed to study intrinsic dielectric behaviors of the ceramics at microwave region. Ionic displacive polarization and the electronic polarization contributed almost equally to the dielectric permittivity of the ceramic at microwave region. The Ag₂MoO₄ ceramics could be a good candidate for ultra‐low temperature co‐fired microwave devices.     

Time‐series and extended Karhunen–Loève analysis of turbulent drag reduction in polymer solutions

Direct numerical simulations and statistical analysis techniques are used to study the drag‐reducing effect of polymer additives on turbulent channel flow in minimal domains. Additionally, a new formulation of Karhunen–Loève decomposition for viscoelastic flows is introduced, allowing the dominant features of the polymer stress fields to be characterized. In minimal channels, there are intervals of “active” and “hibernating” turbulence that display very different structural and energetic characteristics; the present work illustrates how the statistics of these intervals evolve over the entire range of drag reduction (DR) levels. The effect of viscoelasticity on minimal channel turbulence is twofold: first, it strongly suppresses the active turbulent dynamics that predominate in Newtonian flow and second, at sufficiently high Weissenberg number it stabilizes the dynamics of hibernating turbulence, allowing it to predominate in the maximum drag reduction regime. In this regime, the stress fluctuations become delocalized from the wall region, encompassing the entire flow domain. © 2014 American Institute of Chemical Engineers AIChE J, 60: 1460–1475, 2014     

Gradient and weather resistant hybrid super‐hydrophobic coating based on fluorinated epoxy resin

A weather resistant super‐hydrophobic coating that can offer good substrate adhesion and yet to be easily processed at large scale can be of practical use in emerging fields of self‐cleaning and anti‐icing paint, combing all these properties together remains challenging task. Here we describe a composite coating composed of a fluorinated epoxy resin emulsion with embedded in situ surface‐modified dual‐scale nano‐silica, which displayed durable super‐hydrophobicity and excellent adhesive strength. The as‐prepared coating possesses water contact angle of 158.6 ± 1°, sliding angle around 3.8 ± 0.2° which remain stable even under acidic/alkaline, heat/cool, and accelerated aging treatment. The results demonstrate that surface roughness had a micron‐ and nanometer scale distribution with increased particle loading beyond 40 wt %. Through quantitative comparison of surface Attenuated Total Reflection (ATR) with bulk FT‐IR transmission spectra, a gradient coating with surface enrichment of hydrophobic groups was determined. The air‐side fluorinated polysiloxane‐rich layer endows coating with weather‐resistance and ultra‐hydrophobicity while bottom epoxy resin layer enhances substrate adhesion. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40955.     

Biocompatible electrospun tactic poly(methyl methacrylate) blend fibers

Uniform and beads free fibers of pristine syndiotactic PMMA (s-PMMA), isotactic PMMA (i-PMMA), and their blends in the ratio of s:i = 3:1, 1:1 and 1:3 were successfully prepared using the electrospinning technique. The tactic PMMA blend fibers showed unique thermal stability and glass transition temperatures compared to their pristine counterparts. An interesting endotherm peak was observed for the s:i = 1:3 electrospun fibers, which might indicate a complex formation between the two tactic PMMAs. Systematic surface functionalities study by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) revealed the interactions between these two tactic PMMAs. Biocompatibility of tactic PMMA and their blend fibers was first time comparably investigated using HeLa as the model mammalian cell line; an intriguing observance was first revealed that the blend fibers showed better biocompatibility than both pristine ones, though the behind mechanism is not well understood yet.