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41.
Kara D. Fong Helen K. Bergstrom Bryan D. McCloskey Kranthi K. Mandadapu 《American Institute of Chemical Engineers》2020,66(12):e17091
The theory of transport phenomena in multicomponent electrolyte solutions is presented here through the integration of continuum mechanics, electromagnetism, and nonequilibrium thermodynamics. The governing equations of irreversible thermodynamics, including balance laws, Maxwell's equations, internal entropy production, and linear laws relating the thermodynamic forces and fluxes, are derived. Green–Kubo relations for the transport coefficients connecting electrochemical potential gradients and diffusive fluxes are obtained in terms of the flux–flux time correlations. The relationship between the derived transport coefficients and those of the Stefan–Maxwell and infinitely dilute frameworks are presented, and the connection between the transport matrix and experimentally measurable quantities is described. To exemplify the application of the derived Green–Kubo relations in molecular simulations, the matrix of transport coefficients for lithium and chloride ions in dimethyl sulfoxide is computed using classical molecular dynamics and compared with experimental measurements. 相似文献
42.
Modeling of a membrane reactor system for crude palm oil transesterification. Part II: Transport phenomena 下载免费PDF全文
Pin Pin Oh Mei Fong Chong Harrison Lik Nang Lau Yuen May Choo Junghui Chen 《American Institute of Chemical Engineers》2015,61(6):1981-1996
The mechanistic modeling of biodiesel production process in membrane reactor with the consideration of chemical reaction, phase equilibrium, and ultrafiltration is important for the membrane reactor design. In part II of this work, the chemical and phase equilibrium (CPE) model for crude palm oil transesterification reaction in the membrane reactor developed in part I is extended to an integration of CPE with modified Maxwell–Stefan model, which considers multicomponent mass transport phenomena of concentration polarization and intramembrane. A good fit of simulated permeate fluxes and apparent solute rejection to the experimental data shows that the model has a good prediction capability. Reversible fouling was found to be the major fouling and no pore plugging was observed. Simulation results verified that micelles were retained by the membrane at CPO:MEOH molar ratio of 1:24 and catalyst concentration of 0.5 wt %. However, phase inversion happened when catalyst concentration of 0.05 and 0.1 wt % were used. © 2015 American Institute of Chemical Engineers AIChE J, 61: 1981–1996, 2015 相似文献
43.
Cocoa Butter Substitute (CBS) Produced from Palm Mid-fraction/Palm Kernel Oil/Palm Stearin for Confectionery Fillings 下载免费PDF全文
Nirupam Biswas Yuen Lin Cheow Chin Ping Tan Sivaruby Kanagaratnam Lee Fong Siow 《Journal of the American Oil Chemists' Society》2017,94(2):235-245
This study investigated the physicochemical properties of ternary mixtures of palm mid-fraction (PMF):refined bleached deodorized palm kernel oil (RBDPKO):refined bleached deodorized palm stearin (RBDPS) for cocoa butter substitute (CBS). Fatty acid constituents, triacylglycerol constituents, solid fat contents (SFCs), melting behavior, polymorphism and crystal morphology were determined using gas chromatography (GC), high-performance liquid chromatography (HPLC), differential scanning calorimetry (DSC), pulsed nuclear magnetic resonance (p-NMR), X-ray diffraction (XRD) and polarized light microscopy (PLM), respectively. Eight blends of various ratios of ternary mixtures were investigated based on the previously studied binary fat mixtures. The composition of palmitic (P) and oleic (O), POP, and crystal morphology (size and shape) of the PMF/RBDPKO/RBDPS [14.9/59.6/25.5 (%w/w)] mixture were comparable to cocoa butter (CB), while its melting profile (18.5 and 37 °C), SFC at 20 °C and polymorphism were different from CB. The iso-solid diagrams of the mixture displayed a monotectic effect at 20–25 °C. Therefore, the 14.9/59.6/25.5 PMF/RBDPKO/RBDPS mixture could be used as a CBS in confectionery fillings because of the crystal morphology and monotectic behaviors comparable to those of CB. 相似文献
44.
Lin CL Chen RF Chen JY Chu YC Wang HM Chou HL Chang WC Fong Y Chang WT Wu CY Chiu CC 《International journal of molecular sciences》2012,13(5):6236-6245
Caffeic acid (CA), a natural phenolic compound, is abundant in medicinal plants. CA possesses multiple biological effects such as anti-bacterial and anti-cancer growth. CA was also reported to induce fore stomach and kidney tumors in a mouse model. Here we used two human lung cancer cell lines, A549 and H1299, to clarify the role of CA in cancer cell proliferation. The growth assay showed that CA moderately promoted the proliferation of the lung cancer cells. Furthermore, pre-treatment of CA rescues the proliferation inhibition induced by a sub-IC(50) dose of paclitaxel (PTX), an anticancer drug. Western blot showed that CA up-regulated the pro-survival proteins survivin and Bcl-2, the down-stream targets of NF-κB. This is consistent with the observation that CA induced nuclear translocation of NF-κB p65. Our study suggested that the pro-survival effect of CA on PTX-treated lung cancer cells is mediated through a NF-κB signaling pathway. This may provide mechanistic insights into the chemoresistance of cancer calls. 相似文献
45.
华东500kV电网谐波问题初探 总被引:1,自引:0,他引:1
针对华东500kV电网电压谐波率较大的现状,分析了谐波源主要来自500kV变压器和高压电抗器。这些谐波源的谐波电流数值并不大,但由于500kV电网自身阻抗可能使谐波分量起了放大作用,本文对此作了分析探讨。本文还就谐波电压的测量方法、减小测量附加误差、谐波电压限值和控制对策作了叙述。 相似文献
46.
A series of silicon(IV) phthalocyanines with two axial isopropylidene-protected galactose moieties and one, two, or eight chloro group(s) on the periphery of the macrocycle have been synthesised and spectroscopically characterised. The photophysical properties and in vitro photodynamic activities of these compounds have been studied and compared with those of the nonchlorinated analogue. All the compounds, with the exception of the octachlorinated counterpart which has a limited solubility, are essentially nonaggregated in N,N-dimethylformamide. The fluorescence quantum yield decreases and the singlet oxygen quantum yield increases as the number of chloro substituent increases, which is in accord with the heavy-atom effect. The non-, mono-, and dichlorinated phthalocyanines formulated with Cremophor EL are all photodynamically active against HT29 human colon adenocarcinoma and HepG2 human hepatocarcinoma cells with IC(50) values ranging from 0.03 to 1.05 microM. The photocytotoxicity as well as the efficiency to generate intracellular reactive oxygen species decrease along this series because of the increase in aggregation tendency upon chloro substitution. The nonchlorinated analogue exhibits the highest potency and can target the lysosomes of HT29 cells, whereas the monochlorinated counterpart is not localised in the lysosomes. 相似文献
47.
介绍了重力式,衡重式挡土墙计算,设计CAD系统,该系统的应用,使土木工程中的挡土墙设计了多方案比较,科学优化,安全高效,计算,设计至出图可连续作业的自动化过程。 相似文献
48.
Phuong-Anh Ngoc Doan Tzyi-Horng Tan Lee Fong Siow Beng Ti Tey Eng Seng Chan Teck-Kim Tang Nur Azwani Abdul Karim Eng-Tong Phuah Yee-Ying Lee 《Journal of the American Oil Chemists' Society》2021,98(6):609-620
Palm fatty acid distillate (PFAD) is a rich source of vitamin E. As compared to other vegetable oil, PFAD has higher tocotrienol (70–80%) over tocopherol content, which makes it a valuable source for vitamin E extraction. Current vitamin E extraction methods are not sustainable due to the intensive usage of chemical and high operational cost. Hence, the present study investigated for the first time using dry fractionation process as a green and economical pretreatment method for separating solid fraction (stearin) and liquid fraction (olein) in order to concentrate vitamin E from PFAD in olein fraction. We examined the dry fractionation conditions: crystallization ending temperature (36–44 °C), cooling rate (0.3 and 1.5°C min−1), stirring speed (20–125 rpm), and holding time (0–60 min) on the composition of unsaturated and saturated fatty acids as well as vitamin E content in liquid fraction (olein) and solid fraction (stearin) using gas chromatography and high performance liquid chromatography, respectively. In most of these conditions, vitamin E was ultimately higher in olein fraction as compared to stearin fraction, which is correlated with the high degree of unsaturation. Under a cooling rate of 0.3°C min−1, 90 rpm stirring speed, and ending crystallization of 38 °C, the highest vitamin E rich olein fraction was attained with 1479 ± 10.51 ppm in 50 g olein fraction as compared to 1366 ± 7.94 ppm in 500 g of unfractionated PFAD. 相似文献
49.
The solar-thermal refrigeration systems, covering the solar absorption refrigeration system (SAbRS) and the solar adsorption refrigeration system (SAdRS), were designed for typical office in the subtropical Hong Kong. The approach of simulation-optimization was adopted in order to determine the optimal design parameters for SAbRS and SAdRS against the conventional design practice. For simulation, dynamic model of each system was refined on the TRNSYS platform. For optimization, the objective was to minimize the annual primary energy consumption of SAbRS or SAdRS in response to the changing loading and climatic conditions throughout a year. This is a constrained optimization problem since the upper limit of comfort temperature was stipulated, such that the minimization of system energy would not sacrifice the indoor thermal comfort. Due to the complex, multidimensional and constrained nature of the dynamic simulation models, the differential evolution (DE), which has been proven effective in evolutionary computation (EC), was used for optimization purpose. Through the simulation-optimization run, the optimized designs of SAbRS and SAdRS were determined, and their corresponding primary energy consumptions could be 12.2% and 7.1% less than those based on the general design practice. The results provide useful guidelines for the equipment design of SAbRS and SAdRS. 相似文献
50.