Novel photoactive fluorene-based terpolymers incorporating carbazole for photovoltaic application

A series of novel photoactive conjugated terpolymers based on N-alkyl carbazole, 9,9-didecylfluorene, and bis(thienyl)benzothiadiazole were synthesized by the Pd-catalyzed Suzuki polymerization method with various molar ratios of the carbazole derivatives. Electron-deficient benzothiadiazole and electron-rich carbazole moieties were incorporated into the polymer backbone to obtain the broad absorption spectrum and to improve the hole-transporting characteristics, respectively. The polymer solar cell (PSC) was fabricated with a layered structure of ITO/PEDOT: PSS/polymer:C71-PCBM (1:3)/LiF/Al. The best performance of PSC was obtained at P1:C71-PCBM whose reaches a power conversion efficiency (PCE) of 2.62%, with a short circuit current density (J(SC)) of 8.61 mA/cm2, an open circuit voltage (V(OC)) of 0.82 V, and a fill factor (FF) of 0.37 under AM 1.5 G irradiation (100 mW/cm2).     

Preparation of C60(O)n-ZnO nanocomposite under electric furnace and photocatalytic degradation of organic dyes

Zinc oxide (ZnO) nanoparticles were synthesized sonochemically by applying ultrasonic irradiation to a mixed aqueous-alcoholic solution of zinc nitrate with sodium hydroxide at room temperature. The morphology and optical properties of the ZnO nanoparticles were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV-vis spectroscopy. The C60(O)n nanoparticles were synthesized by heating a mixture of C60 and 3-chloroperoxybenzoic acid in a benzene solvent under the reflux system. The heated C60(O)n-ZnO nanocomposite was synthesized in an electric furnace at 700 degrees C for two hours. The heated C60(O)n-ZnO nanocomposite was characterized by XRD, SEM, and TEM, and examined as a catalyst in the photocatalytic degradation of organic dyes by UV-vis spectroscopy. The photocatalytic effect of the heated C60(O)n-ZnO nanocomposite was evaluated by a comparison with that of unheated C60(O)n nanoparticles, heated C60(O)n nanoparticles, and unheated C60(O)n-ZnO in organic dyes, such as methylene blue (MB), methyl orange (MO), and rhodamine B (RhB) under ultraviolet light at 365 nm.     

Catalytic oxidation of benzene with ozone over nanoporous Mn/MCM-48 catalyst

The catalytic oxidation of a representative volatile organic compound, benzene, with ozone at a low temperature was investigated. A nanoporous MCM-48 material with a high specific surface area was used as the support for the catalytic oxidation for the first time. Mn, which has high activity at a low temperature, was used as the metal catalyst. To examine the effect of the Mn precursor, MCM-48 was impregnated with two different Mn precursors: Mn acetate and Mn nitrate. The characteristics of the synthesized catalysts were analyzed by Brunauer Emmett Teller surface area, X-ray diffraction, X-ray photoelectron spectroscopy, and temperature-programmed reduction. MCM-48 impregnated with Mn acetate showed higher catalytic activity than MCM-48 impregnated with Mn nitrate. This result was attributed to the better dispersion within nanoporous MCM-48 and higher oxygen mobility of Mn oxides produced by Mn acetate. The catalytic activity was also shown to depend closely on the ozone concentration.     

Crystal structure of poly(pentamethylene 2,6-naphthalate)

The crystal structure of poly(pentamethylene 2,6-naphthalate) (PPN) was determined by using X-ray diffraction and molecular modeling. The unit cell of PPN was found to be triclinic ( space group) with dimensions of a=0.457 nm, b=0.635 nm, c=2.916 nm, =121.6°, β=90.4°, γ=87.6°, and the calculated crystal density was 1.311 g cm⁻³. The unit cell contains one polymer chain with two repeating units. In the unit cell, the PPN backbone takes gauche/gauche conformation in the middle part of each pentamethylene unit, and two naphthalene rings are in face-to-face arrangement.     

Removal of zinc ions in wastewater by electrodialysis

To obtain useful data for treatment of the wastewater discharged from zinc electroplating processes, we investigated the effects of operating parameters, such as the initial concentration of dilute solution, the flow velocity and the applied voltage, on removal rate of Zn²⁺ in the model solutions using an electrodialysis system. Zinc ions in the solutions were effectively removed by the electrodialyzer with CMX cation exchange membranes and AMX anion exchange membranes. The initial concentration of dilute solution, the flow velocity and the applied voltage strongly affected the performance of the electrodialysis system. As the initial concentration of dilute solution, the flow velocity and the applied voltage were increased, the removal ratio was increased. The energy consumption was increased as the initial concentration of dilute solution and the applied voltage were increased, whereas the effect of the flow velocity on the energy consumption was negligible.     

Solid circulation characteristics in an internally circulating fluidized bed with orifice-type draft tube

Effects of superficial gas velocities to a draft tube, to an annulus section and particle size on the solid circulation rate (G,) have been determined in an internally circulating fluidized bed (0.28 m I.D. × 2m high) with an orifice type draft tube. The solid circulation rate from the draft tube to an annulus section increases with increasing gas velocities to the draft tube(U _d ) and annulus section (U_a) and consequent increase in pressure drop across the orifice (ΔP_or). However, the values ofG _s decrease by 7–21% with increasing particle size from 86 to 288 μm. The pressure drop across the orifice increases with increasingU _d andU _a . However, ΔP_or decreases by 5–23% with increasing particle size. To predictG _s in an internally circulating fluidized bed, a correlation is proposed as a function of ΔP_or This paper is dedicated to Professor Dong Sup Doh on the occasion of his retirement Korea University.     

Kinetics of cellobiose decomposition under subcritical and supercritical water in continuous flow system

The effects of reaction temperature, pressure and residence time were investigated with a flow apparatus. Cellobiose decomposition kinetics and products in suband supercritical water were examined at temperatures from 320 to 420 °C at pressures from 25 to 40 MPa, and at residence times within 3 sec. Cellobiose was found to decompose via hydrolysis and pyrolysis. The yield of desired hydrolysis product, glucose, was the maximum value of 36.8% at 320 °C, 35 MPa, but the amount of 5-(hydroxymethyl)furfural (HMF), fermentation inhibitor increased too because residence time increased in the subcritical region owing to decrease of reaction rate. Meanwhile, though the yield of glucose is low in the supercritical region, the yield of HMF decreased compared with the subcritical region; and at the minimum yield of HMF (380 °C, 25 MPa), the yield of glucose was 21.4%. The decomposition of cellobiose followed first-order kinetics and the activation energy for the decomposition of cellobiose was 51.05 kJ/mol at 40MPa.     

Recovery of magnetic ionic liquid [bmim]FeCl<Subscript>4</Subscript> using electromagnet

Recovery of 1-butyl-3-methylimidazolium tetrachloroferrate ([bmim]FeCl₄) from its mixture with water was investigated. The [bmim]FeCl₄ rich phase in the mixture forming two-phase was successfully separated, while homogeneous mixtures could not be separated. However, the concentration of the homogeneous mixture varied as a function of the magnetic field strength. Therefore, a combination of magnetic field and conventional methods to recover magnetic ILs from reaction mixtures will be very useful and have great potential.     

基于直角叉树切割网格的复杂外形N-S方程数值模拟

对于粘性绕流的数值模拟，在直角叉树切割网格的基础上，结合三角形非结构网格和矩形结构化网格，利用其各自的优势和特点，提出了一种生成混合染交网格的思路和方法，在物面附近生成了适合粘性流计算的大长宽比矩形网格，地远场分布直角叉树切割网格，快速离散计算空间。对于复杂的多体问题，采用三角形网格来连接 各体网格，并运用网格合并的方法，保证了各网格之间的光滑过渡过连接，提高了网格的质量，针对复杂多段翼型绕流问题，在上述网格基础上，采用B－L代数湍流模型和中心有限体积法，完成了Navier-Stokes方程（N－S方程）的数值模拟，计算结果表明，网格生成和流场计算都是正确的。     

Effect of additive on synthesis of MnZn ferrite nanocrystal by hydrothermal crystallization

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