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21.
Wannasiri Worakitkanchanakul Tomohiro Imura Tokuma Fukuoka Tomotake Morita Hideki Sakai Masahiko Abe Ratana Rujiravanit Sumaeth Chavadej Hiroyuki Minamikawa Dai Kitamoto 《Colloids and surfaces. B, Biointerfaces》2009,68(2):207-212
Due to the great importance of new therapeutic routes for morphine in pain treatment, several investigations are under development. In this way, the design of a liquid system for the oral administration of morphine would be of great help, especially in patients with difficulties in swallowing (children and elderly people). The systems studied in this work are kollidon® SR microparticles, a biodegradable polymer classically used as excipient in the design of solid dosage forms, as vehicles for morphine. A detailed investigation of the capabilities of the polymer particles to load this drug at their surface is described. Electrophoretic mobility and optical absorbance determinations were used with this aim. The main factors determining the drug incorporation, after incubation of the microparticles in the morphine solutions, were the adsorption time, the type of electrolyte and its concentration, and the drug concentration. The optimum loading conditions were used to perform morphine release evaluations, finding that the release profiles were biphasic since the drug adsorbed was slowly released during 24 h after an initial burst release phase. 相似文献
22.
Thitiporn Suttikul Thammanoon Sreethawong Hidetoshi Sekiguchi Sumaeth Chavadej 《Plasma Chemistry and Plasma Processing》2011,31(2):273-290
In this work, ethylene epoxidation reaction for ethylene oxide production over silver catalysts loaded on two different supports
(silica and alumina particles) in a low-temperature AC dielectric barrier discharge (DBD) reactor was investigated. The DBD
plasma system was operated under the following base conditions: an O2/C2H4 feed molar ratio of 1/4, a total feed flow rate of 50 cm3/min, an electrode gap distance of 0.7 cm, an input frequency of 500 Hz, and an applied voltage of 19 kV. From the results,
the presence of silver catalysts improved the ethylene oxide production performance. The silica support interestingly provided
a higher ethylene oxide selectivity than the alumina support. The optimum Ag loading on the silica support was found to be
20 wt%, exhibiting the highest ethylene oxide selectivity of 30.6%. 相似文献
23.
Nongnuch Rueangjitt Thammanoon Sreethawong Sumaeth Chavadej Hidetoshi Sekiguchi 《Plasma Chemistry and Plasma Processing》2011,31(4):517-534
In this work, a mini-gliding arc discharge reactor was employed for the reforming of methane under ambient temperature and pressure operation. Acetylene and hydrogen were produced dominantly with high selectivities of ~70?C90 and ~75%, respectively. The results showed that both methane conversion and product selectivities depended strongly on various operating parameters, including feed methane concentration, feed flow rate, electrode gap distance, residence time, and the presence of a reforming catalyst (as a function of catalyst distance). The Ni catalyst-loaded porous alumina-silica plate was used to study the catalytic effect on the process performance at various residence times. A considerable enhancement of methane conversion and product yields was achieved in the combined plasma-catalytic system, particularly at a longer residence time. The catalyst distance, or packing position of catalyst plate, was also found to be an important factor affecting the process performance of the combined plasma-catalytic methane reforming. The closer catalyst distance led to the greater methane conversion because of the greater possibility of adsorption?Cdesorption interactions of excited gaseous species on the catalyst surface to enhance subsequent reactions. 相似文献
24.
Thammanoon Sreethawong Thanapoom Suwannabart Sumaeth Chavadej 《Plasma Chemistry and Plasma Processing》2008,28(5):629-642
Ethylene oxide (EO), a valuable chemical feedstock in producing many industrial chemicals, which is industrially produced
by the partial oxidation of ethylene, so-called ethylene epoxidation, has been of great interest in many global research studies.
In this work, the epoxidation of ethylene under a low-temperature dielectric barrier discharge (DBD) was feasibly investigated
to find the best operating conditions. It was experimentally found that the EO yield decreased with increasing O2/C2H4 feed molar ratio, feed flow rate, input frequency, and electrode gap distance, while it increased with increasing applied
voltage up to 19 kV. The highest EO yield of 5.6% was obtained when an input frequency of 500 Hz and an applied voltage of
19 kV were used, with an O2/C2H4 feed molar ratio of 1:1, a feed flow rate of 50 cm3/min, and an electrode gap distance of 10 mm. Under these best conditions, the power consumption was found to be as low as
6.07 × 10−16 Ws/molecule of EO produced. 相似文献
25.
Thitiporn Suttikul Chakrit Tongurai Hidetoshi Sekiguchi Sumaeth Chavadej 《Plasma Chemistry and Plasma Processing》2012,32(6):1169-1188
The effects of separate C2H4/O2 feed and C2H4 feed position on the ethylene epoxidation reaction in an AC cylindrical dielectric barrier discharge reactor were investigated. The highest EO selectivity of 34?% and EO yield of 7.5?%, as well as the lowest power consumption of 1.72?×?10?16 Ws/molecule of EO produced, were obtained at a C2H4 feed position of 0.25, an O2/C2H4 feed molar ratio of 1/4, an applied voltage of 13?kV, an input frequency of 550?Hz, and a total feed flow rate of 75?cm3/min. The results demonstrated, for the first time, that the separate feed of C2H4 and O2 could provide better ethylene epoxidation performance in terms of higher EO selectivity and yield, and lower power consumption, as compared to the mixed feed. All undesired reactions including C2H4 cracking, dehydrogenation, oxidation, and coupling reactions are lowered by the ethylene separate feed because of a decrease in opportunity of ethylene molecules to be activated by generated electrons. 相似文献