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111.
M.S. Liza R. Abdul Rahman B. Mandana S. Jinap A. Rahmat I.S.M. Zaidul A. Hamid 《Food and Bioproducts Processing》2010,88(2-3):319-326
The bioactive flavonoid compounds of Strobilanthes crispus (Pecah Kaca) leaves obtained by using supercritical carbon dioxide (SC-CO2) extraction were investigated and the obtained crude extract yields were compared in order to select the best operation parameters. Since carbon dioxide is a non-polar solvent, ethanol was used as co-solvent to increase the polarity of the fluid. The studied parameters were pressure (100, 150 and 200 bar), temperature (40, 50 and 60 °C) and dynamic extraction time (40, 60 and 80 min). The optimum extraction condition occurred at 200 bar, 50 °C and 60 min. Based on the mean value, pressure had dominant effect on the extraction yield. Apart from the optimum SFE conditions two other conditions namely at minimum (100 bar, 40 °C, 40 min) and maximum (200 bar, 60 °C, 80 min) levels of each studied parameters as control runs were analyzed by HPLC to determine the major bioactive flavonoid compounds from S. crispus. Under the optimum conditions eight flavonoid compounds were identified; they were (+)-catechin, (?)-epicatechin, rutin, myricetin, luteolin, apigenin, naringenin and kaempferol. 相似文献
112.
Liu Lin Yang Chao Zhou Jianzhong Garmestani Hamid Dastan Davoud 《Protection of Metals and Physical Chemistry of Surfaces》2021,57(2):367-373
Protection of Metals and Physical Chemistry of Surfaces - The tribological tests of brass and steel are carried out on an in-situ tribometer. The Stribeck curve illustrates that the roughness and... 相似文献
113.
Muhammad Kashif Md Eaqub Ali Syed M Usman Ali Uda Hashim Sharifah Bee Abd Hamid 《Nanoscale research letters》2013,8(1):68
ZnO nanorods were synthesized using a low-cost sol-gel spin coating technique. The synthesized nanorods were consisted of hexagonal phase having c-axis orientation. SEM images reflected perpendicular ZnO nanorods forming bridging network in some areas. The impact of different hydrogen concentrations on the Pd-sensitized ZnO nanorods was investigated using an impedance spectroscopy (IS). The grain boundary resistance (Rgb) significantly contributed to the sensing properties of hydrogen gas. The boundary resistance was decreased from 11.95 to 3.765 kΩ when the hydrogen concentration was increased from 40 to 360 ppm. IS gain curve showed a gain of 6.5 for 360 ppm of hydrogen at room temperature. Nyquist plot showed reduction in real part of impedance at low frequencies on exposure to different concentrations of hydrogen. Circuit equivalency was investigated by placing capacitors and resistors to identify the conduction mechanism according to complex impedance Nyquist plot. Variations in nanorod resistance and capacitance in response to the introduction of various concentrations of hydrogen gas were obtained from the alternating current impedance spectra. 相似文献
114.
Mustafa Aghazadeh Abbas-Ali Malek Barmi Hamid Mohammad Shiri Sajjad Sedaghat 《Ceramics International》2013,39(2):1045-1055
Ultra-fine nanoparticles, mono-dispersed nanospheres and nanorods of Y(OH)3 and Y2O3 were successfully prepared via electrodeposition from chloride bath at different temperatures of 10, 25, 40 and 80 °C followed by heat-treatments at 600 °C in dry air atmosphere. Thermal behavior of the hydroxide samples was investigated by differential scanning calorimetry (DSC) and thermogravimetric (TG) analysis. The structural and morphological characteristics of the products were determined by X-ray diffraction (XRD), FT-IR, scanning and transmission electron microscopy (SEM and TEM). Effects of bath temperature on the mechanism of base electrogeneration and deposit formation on the cathode surface were proposed and discussed. The results showed that the crystal structure, composition and morphology of the products are mainly affected by the temperature of electrodeposition bath. 相似文献
115.
Rui Feng Hamid A. Al-Megren Zhanquan Zhang Mohammed C. Al-Kinany Zifeng Yan Zhongdong Zhang Xionghou Gao 《Journal of Porous Materials》2014,21(6):947-956
Interest in reducing SO2 emission from the fluid catalytic cracking (FCC) crude oil has been encouraging the development of new materials to achieve such goal. The nanostructured Mg–Al spinel (MgAl2O4) was prepared by co-precipitation and post hydrothermal treatment in the presence of glucose and followed by elimination of the organic components by calcination at 700 °C for 3 h. Physical and chemical properties were characterized by XRD, N2 sorption, TG, FTIR, SEM, and TEM methods. Mesoporous nanostructured MgAl2O4 with a high surface area of 324 m2 g?1 were obtained. The organic components contributed to the development of mesoporosity, functioning as a soft template. SO2 adsorption tests showed that the nanostructured MgAl2O4 had a 51.58 % increase of SO2 sorption capacity than MgAl2O4 prepared without glucose. These results showed that the nanostructured MgAl2O4 is a promising candidate as catalyst for flue gas desulfurization in FCC process. Three kinetic models were also applied to analyze the SO2 adsorption kinetics; the pseudo-second order kinetic model fit well with a correlation coefficient (R2) of 0.991 for nanostructured MgAl2O4. 相似文献
116.
SPEEK/cSMM membrane for simultaneous electricity generation and wastewater treatment in microbial fuel cell 下载免费PDF全文
117.
118.
A comparative study on thermomechanical and rheological characteristics of graphite/polypropylene nanocomposites: Highlighting the role of mixing 下载免费PDF全文
The thermomechanical and rheological properties of various graphite/long‐chain branched polypropylene (PP) nanocomposites prepared by different mixing methods have been addressed in the current work. To improve the degree of dispersion of graphite throughout the PP domains, solid‐state milling was carried out and followed by low‐temperature melt processing in the range of melting point and the crystallization temperature of PP. As a result, the well‐dispersed graphite/PP nanocomposites revealed a higher degree of plastic deformation and energy to break in the tensile test; moreover, interestingly, nanocomposites based on branched PP showed a lower zero shear viscosity and lower isothermal crystallization rate. It was speculated that the unexpected decrease in zero shear viscosity arose from the disentanglement of the long‐chain branches in particular, when an exfoliated morphology existed within the PP matrix. J. VINYL ADDIT. TECHNOL., 21:12–17, 2015. © 2014 Society of Plastics Engineers 相似文献
119.
Hamid Pourtaghi-Zahed Gholam Hossein Zohuri Saeid Ahmadjo 《Journal of Polymer Research》2014,21(3):1-10
The microstructure of rubber-like ethylene-propylene copolymer (MN4) produced by a mixed nickel-based system (MN) containing catalysts of dibromo[N,N′-bis(2,6-diisopropylphenyl)-2,3-butanediimine]nickel(II) n1 and dibromo[N,N′-(phenanthrene-9,10-diylidene)bis(2,6-diisopropylaniline)]nickel(II) n2 was determined by 13C NMR technique. Sequences distribution of ethylene (E), propylene (P), EP, inverted propylene and uninterrupted methylene and also methylene number-average sequence lengths for the copolymer (MN4) were estimated. The results obtained from the MN4 EP copolymer were compared with reported copolymers which had been synthesized using constrained geometry catalyst (CGC) and vanadium-based Ziegler-Natta catalyst. The results demonstrated that the MN4 EP copolymer had fewer alternating comonomer sequences than ethylene-propylene elastomers obtained by CGC and vanadium-based (V) catalysts. A large number of the inversion structures (66 %) and high mole percent of sequences containing a long branch (3.2 mol%) were also observed in unique microstructure of the copolymer (MN4). 相似文献
120.
Noshin Omar Hamid Gualous Justin Salminen Grietus Mulder Ahmadou Samba Yousef Firouz Mohamed Abdel Monem Peter Van den Bossche Joeri Van Mierlo 《Journal of Applied Electrochemistry》2014,44(4):509-522
This paper represents an assessment of the main ageing phenomena in electrical double-layer capacitors (EDLCs). In this study the cycle life of the EDLC cells with a rated capacitance of 1,600 F has been investigated at different ambient temperatures and current rates. From the experimental results we can observe that the impact of the high ambient temperature is significant on the cycle life of the cells. Moreover, the results also show the negative impact of the current rate. The internal resistance tests showed that the increase of the resistance is much higher than the decrease of the capacitance. Thus, the ageing of the EDLC during cycling was clearly non-linear. Further the EIS measurements indicated the higher increase of the imaginary part of the impedance at low frequencies during cycling, which indicates the capacitance fade. 相似文献