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( Xinji Tian ),( Qianqian Li ),( Xingwang Li ),( Hui Zhang ),( Khaled Rabie ),( Charles Casimiro Cavalcante ) 한국인터넷정보학회 2019 KSII Transactions on Internet and Information Syst Vol.13 No.11
In this paper, we consider a two-way relay non-orthogonal multiple access (TWR-NOMA) system with residual hardware impairments (RHIs) and channel estimation errors (CEEs), where two group users exchange their information via the decode-and-forward (DF) relay by using NOMA protocol. To evaluate the performance of the considered system, exact analytical expressions for the outage probability of the two groups users are derived in closed-form. Moreover, the asymptotic outage behavior in the high signal-to-noise ratio (SNR) regime is examined and the diversity order is derived and discussed. Numerical simulation results verify the accuracy of theoretical analyses, and show that: i) RHIs and CEEs have a deleterious effects on the outage probabilities; ii) CEEs have significant effects on the performance of the near user; iii) Due to the RHIs, CEEs, inter-group interference and intra-group interference, there exists error floors for the outage probability.
Raquel Viveiros,Francisco M. Dias,Luisa B. Maia,William Heggie,Teresa Casimiro 한국공업화학회 2017 Journal of Industrial and Engineering Chemistry Vol.54 No.-
In this work, Molecular Imprinted Polymers (MIPs)-layered silica beads which have affinity for a model pharmaceutical impurity, acetamide (ACET) were developed using supercritical carbon dioxide (scCO2) technology. Silica beads were first functionalized using two different green strategies, grafting to (MPS/ EtOH in scCO2) and grafting from (plasma technology). These core beads were then used as seed particles in the synthesis, in scCO2 of a MIP layer. Dynamic binding tests were performed in order to evaluate the affinity of the resulting silica core – MIP shell beads to ACET and the efficiency of its removal from an active pharmaceutical ingredient – Beclomomethasone dipropionate (API) crude mixture. ACET was preferentially retained over analogue molecules, benzamide (BENZ) and pivalamide (PIV). The core–shell MIP beads were packed in a SPE column (396.5 mg in a 3 mL SPE tube) and evaluated as a potential gravity-driven purification device, enabling the removal of 100% of ACET whilst losing only 0.37% of API from a model mixture solution—10 mL of ACET and API (0.25 mg mL1 + 3.5 mg mL1).
Antonio Montes,Chandrasekar Chinnarasu,Clara Pereyra,Lourdes Casas,María Teresa Fernández-Ponce,Casimiro Mantell,Sangma Pattabhi,Enrique Martínez de la Ossa 한국화학공학회 2016 Korean Journal of Chemical Engineering Vol.33 No.2
Various extracts from olive leaves have been precipitated by a supercritical antisolvent (SAS) process to evaluate the possibility of producing polyphenol fine particles with controlled size and size distribution. Olive leaves were initially extracted with subcritical fluids using mixtures of CO2+ethanol at 10% and 50%, by pressurized liquid extraction (PLE) with water, ethanol and a hydroalcoholic mixture (50 : 50) (v/v), and also by conventional ethanol extraction (CE). PLE gave the extract with the highest yield and the best antioxidant activity. SAS precipitation was unsuccessful for the extracts obtained with pressurized water and with the hydroalcoholic mixture (50 : 50) (v/v). The SAS precipitates with the smallest particle sizes were produced from extracts obtained with subcritical fluids. The SAS precipitates obtained after the conventional ethanol extraction of olive leaves showed the best antioxidant activity.
Use of supercritical methanol/carbon dioxide mixtures for biodiesel production
María Belén García-Jarana,Jezabel Sánchez-Oneto,Juan Ramón Portela,Lourdes Casas,Casimiro Mantell,Enrique Martínez de la Ossa 한국화학공학회 2016 Korean Journal of Chemical Engineering Vol.33 No.8
The use of supercritical conditions for the production of biodiesel from both vegetables oils and waste-oils may be of great industrial interest because it can be carried out without those catalysts necessary in the conventional transesterification process, therefore avoiding a complex separation between the product and the catalyst. However, the use of supercritical alcohol requires higher operating temperatures and pressures. In this work, CO2 was added to the reaction mixture in order to reduce the operating conditions (temperature, pressure and molar ratio of alcohol to vegetable oil). The novelty of using CO2 may have two advantages: a possible combination of supercritical CO2 extraction of the oil and its subsequent transesterification reaction without CO2 depressurization, and a reduction of the supercritical temperature and pressure of the mixture. The effects of temperature (280-350 oC), pressure (140-280 bar), methanol- to-oil molar ratio (20-30), CO2-to-methanol molar ratio (0.05-0.2) and residence time (0-45minutes) on the yield of methyl esters (biodiesel) were studied in a batch reactor, obtaining in all cases a relatively low increase in the yield when CO2 was present in the medium. The yields of biodiesel were tested with three vegetable oils used as model compounds (palm, sunflower and borage), obtaining similar results.