Unsteady Flow Due to Concentric Rotation of Eccentric Rotating Disks

While two parallel disks are initially rotating with the same angular velocity about non-coincident axes, the axes are suddenly made coincident. The development of the flow is examined until the fluid rotates as a rigid body in the steady-state. The velocity field and the shear stress components on the disks are found exactly by a Fourier series solution. Furthermore, a series solution that converges rapidly at small times is obtained with the aid of the Laplace transform technique.     

Updated database and new empirical values for K-shell fluorescence yields

The measured K-shell fluorescence yield values that were reported in the literature from 1994 to 2011 were reviewed and presented in a table form (about 341 new measurements). The Weighted-mean values of experimental data were fitted by the analytical function to deduce new empirical K-shell fluorescence yields for a broad range of elements. The results were compared with the other theoretical, experimental and semi-empirical values reported in the literature. Reasonable agreement was typically obtained between our result and other works.     

Investigation of gas transport and other physical properties in relation to the bromination degree of polymers of intrinsic microporosity

In this work, the synthesis of novel polymers of intrinsic microporosity (PIMs) with different degrees of bromine substitution by a free-radical substitution reaction was performed. The synthesized polymers were thoroughly characterized and their bromination degree was verified via nuclear magnetic resonance. The brominated PIMs were investigated by infrared spectroscopy, X-ray diffraction, and density measurements and correlated with their gas transport properties. It was found that with an increase in the bromination degree, the synthesized PIMs exhibited a significant increase in polymer chain packing density which led to reduced fractional free volume and consequent decrease in gas diffusion and permeability coefficients. The change in permeability coefficients caused an improvement in the CO₂/N₂, CO₂/CH₄, and O₂/N₂ ideal permeability selectivities. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 2752–2761     

Modification of polyisoprene‐block‐poly(vinyl trimethylsilane) block copolymers via hydrosilylation and hydrogenation,and their gas transport properties

Polyisoprene‐block‐poly(vinyl trimethylsilane) (PI‐b‐PVTMS) block copolymers having different isoprene contents are successfully chemically modified and characterized by proton nuclear magnetic resonance spectroscopy (¹H‐NMR), Fourier transform infrared spectroscopy, gel permeation chromatography, and thermogravimetric analysis. Gas transport properties of the initial block copolymers and their derivatives modified via hydrosilylation and hydrogenation are measured. The modified block copolymers show higher permeabilities for O₂ and H₂ than the unmodified block copolymers while maintaining similar O₂/N₂ and H₂/N₂ selectivities. Hydrosilylation and hydrogenation of block copolymers with a low isoprene content result in a permeability increase for O₂ and H₂ of 15 to 40%, respectively. Similarly, for block copolymers with high isoprene contents, increases in permeabilities up to 125% are observed compared to initial PI‐b‐PVTMS. © 2013 Wiley Periodicals, Inc. J Polym Sci Part B: Polym. Phys. 2013 , 51, 1252–1261     

Synthesis of boron carbon nitride layers for the adsorption of hazardous basic dye from aqueous solutions

Research on Chemical Intermediates - Many researchers have investigated the usage of carbonaceous materials as adsorbents. In this study, boron carbon nitride (BCN) was synthesized using boric acid...     

Chemical Effect on K Shell X-ray Fluorescence Parameters and Radiative Auger Ratios of Co, Ni, Cu, and Zn Complexes

对钴、镍、铜、锌元素组成的不同配合物K壳层X射线的产生截面、谱线强度比、俄歇辐射强度比进行了测定,同时研究了化学效应对K壳荧光参数和俄歇辐射强度比的影响,并根据电荷转移过程解释了这些参数的变化. 采用59.5 keV的γ射线²⁴¹Am的环形放射源对样品进行激发. 用分辨率为150eV的Ultra-LEGe探测器在5.9 keV测定样品产生的K壳X射线.     

A comprehensive study for selective removal of Cr(VI) by asymmetric imidazolium bromide salts as environmentally-friendly extractant

The study was to determine selective removal and recovery of Cr(VI) from acidic media by solvent extraction (SX) using asymmetric imidazolium-based room temperature imidazolium bromide salts (ARTILs) as the extractants. The relevant parameters on the extraction and the stripping of Cr(VI) were investigated to identify optimum conditions. The optimum conditions were determined as equilibration time 5 minutes, acid concentration and type 0.5?mol/L H₂SO₄, stirring speed 1200?rpm, extractant concentration and type 0.5?mol/L ARTIL5, phase ratio 2.0 and stripping reagent type, and concentration 2.0?mol/L NH₃. In optimum conditions, decyl substituted ARTIL was best in extraction process about 99.7% of extraction rate, whereas moderately hydrophobic pentyl substituted ARTIL was best in stripping process about 70.0% of stripping rate. Also, the optimized process was found as so selective toward Cr(VI) in the presence of the other metal ions with an environmental-friendly liquid–liquid–based SX method.     

Background correction by wavelength modulation using a microcomputer in atomic emission spectrometry

An Apple IIe microcomputer was employed to correct the background radiation in electrothermal atomization atomic emission spectrometry (ETA-AES). In ETA-AES, black-body radiation from the atomizer as well as any broadband molecular emission should be corrected to obtain an atomic signal alone. A quartz plate run by a G325D galvanometric motor was placed before the exit slit of a 256 mm Littrow monochromator. Improvements by a novel pulsed 3-step square waveform are demonstrated compared with the ordinatry 3-step square waveform. A soft delay was also applied in order to avoid taking data at transition stages of the quartz plate. A line and a continuum source are used to simulate offsetting of the DC component of the signal prior to the ADC. This provides a better utilization of the full dynamic range of the converter.