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1.
Taechapoempol K Sreethawong T Rangsunvigit P Namprohm W Thamprajamchit B Rengpipat S Chavadej S 《Applied biochemistry and biotechnology》2011,164(2):204-219
The three highest hydrolysis-capacity-value isolates of Bacillus subtilis (A 002, M 015, and F 018) obtained from Thai higher termites, Microcerotermes sp., under different isolation conditions (aerobic, anaerobic, and anaerobic/aerobic) were tested for cellulase activities—FPase,
endoglucanase, and β-glucosidase—at 37 °C and pH 7.2 for 24 h. Their tolerance to an ionic liquid, 1-butyl-3-methylimidazolium
chloride ([BMIM]Cl), was also investigated. The results showed that the isolate M 015 provided the highest endoglucanase activity
whereas the highest FPase and β-glucosidase activities were observed for the isolate F 018. The isolate F 018 also showed
the highest tolerance to [BMIM]Cl in the range of 0.1–1.0 vol.%. In contrast, the isolate A 002 exhibited growth retardation
in the presence of 0.5–1.0 vol.% [BMIM]Cl. 相似文献
2.
Sumaeth Chavadej Anothai Tansuwan Thammanoon Sreethawong 《Plasma Chemistry and Plasma Processing》2008,28(5):643-662
In this paper, the epoxidation of ethylene over different catalysts—namely Ag/(low-surface-area, LSA)α-Al2O3, Ag/(high-surface-area, HSA)γ-Al2O3, and Au–Ag/(HSA)γ-Al2O3—in a low-temperature corona discharge system was investigated. In a comparison among the studied catalysts, the Ag/(LSA)α-Al2O3 catalyst was found to offer the highest selectivity for ethylene oxide, as well as the lowest selectivity for carbon dioxide and carbon monoxide. The selectivity for ethylene oxide increased with increasing applied voltage, while the selectivity for ethylene oxide remained unchanged when the frequency was varied in the range of 300–500 Hz. Nevertheless, the selectivity for ethylene oxide decreased with increasing frequency beyond 500 Hz. The optimum Ag loading on (LSA)α-Al2O3 was found to be 12.5 wt.%, at which a maximum ethylene oxide selectivity of 12.9% was obtained at the optimum applied voltage and input frequency of 15 kV and 500 Hz, respectively. Under these optimum conditions, the power consumption was found to be 12.6 × 10?16 W s/molecule of ethylene oxide produced. In addition, a low oxygen-to-ethylene molar ratio and a low feed flow rate were also experimentally found to be beneficial for the ethylene epoxidation. 相似文献
3.
Nongnuch Rueangjitt Chalermrat Akarawitoo Thammanoon Sreethawong Sumaeth Chavadej 《Plasma Chemistry and Plasma Processing》2007,27(5):559-576
The objective of the present work was to study the reforming of simulated natural gas via the nonthermal plasma process with
the focus on the production of hydrogen and higher hydrocarbons. The reforming of simulated natural gas was conducted in an
alternating current (AC) gliding arc reactor under ambient conditions. The feed composition of the simulated natural gas contained
a CH4:C2H6:C3H8:CO2 molar ratio of 70:5:5:20. To investigate the effects of all gaseous hydrocarbons and CO2 present in the natural gas, the plasma reactor was operated with different feed compositions: pure CH4, CH4/He, CH4/C2H6/He, CH4/C2H6/C3H8/He and CH4/C2H6/C3H8/CO2. The results showed that the addition of gas components to the feed strongly influenced the reaction performance and the
plasma stability. In comparisons among all the studied feed systems, both hydrogen and C2 hydrocarbon yields were found to depend on the feed gas composition in the following order: CH4/C2H6/C3H8/CO2 > CH4/C2H6/C3H8/He > CH4/C2H6/He > CH4/He > CH4. The maximum yields of hydrogen and C2 products of approximately 35% and 42%, respectively, were achieved in the CH4/C2H6/C3H8/CO2 feed system. In terms of energy consumption for producing hydrogen, the feed system of the CH4/C2H6/C3H8/CO2 mixture required the lowest input energy, in the range of 3.58 × 10−18–4.14 × 10−18 W s (22.35–25.82 eV) per molecule of produced hydrogen. 相似文献
4.
Nongnuch Rueangjitt Thammanoon Sreethawong Sumaeth Chavadej 《Plasma Chemistry and Plasma Processing》2008,28(1):49-67
In this research, the reforming of simulated natural gas containing a high CO2 content under AC non-thermal gliding arc discharge with partial oxidation was conducted at ambient temperature and atmospheric
pressure, with specific regards to the concept of the direct utilization of natural gas. This work aimed at investigating
the effects of applied voltage and input frequency, as well as the effect of adding oxygen on the reaction performance and
discharge stability in the reforming of the simulated natural gas having a CH4:C2H6:C3H8:CO2 molar ratio of 70:5:5:20. The results showed marked increases in both CH4 conversion and product yield with increasing applied voltage and decreasing input frequency. The selectivities for H2, C2H6, C2H4, C4H10, and CO were observed to be enhanced at a higher applied voltage and at a lower frequency, whereas the selectivity for C2H2 showed an opposite trend. The use of oxygen was found to provide a great enhancement of the plasma reforming of the simulated
natural gas. For the combined plasma and partial oxidation in the reforming of CO2-containing natural gas, air was found to be superior to pure oxygen in terms of reactant conversions, product selectivities,
and specific energy consumption. The optimum conditions were found to be a hydrocarbons-to-oxygen feed molar ratio of 2/1
using air as an oxygen source, an applied voltage of 17.5 kV, and a frequency of 300 Hz, in providing the highest CH4 conversion and synthesis gas selectivity, as well as extremely low specific energy consumption. The energy consumption was
as low as 2.73 × 10−18 W s (17.02 eV) per molecule of converted reactant and 2.49 × 10−18 W s (16.60 eV) per molecule of produced hydrogen. 相似文献
5.
Nongnuch Rueangjitt Wariya Jittiang Krittiya Pornmai Jintana Chamnanmanoontham Thammanoon Sreethawong Sumaeth Chavadej 《Plasma Chemistry and Plasma Processing》2009,29(6):433-453
The effect of stage number of multistage AC gliding arc discharge reactors on the process performance of the combined reforming
and partial oxidation of simulated CO2-containing natural gas having a CH4:C2H6:C3H8:CO2 molar ratio of 70:5:5:20 was investigated. For the experiments with partial oxidation, either pure oxygen or air was used
as the oxygen source with a fixed hydrocarbon-to-oxygen molar ratio of 2/1. Without partial oxidation at a constant feed flow
rate, all conversions of hydrocarbons, except CO2, greatly increased with increasing number of stages from 1 to 3; but beyond 3 stages, the reactant conversions remained almost
unchanged. However, for a constant residence time, only C3H8 conversion gradually increased, whereas the conversions of the other reactants remained almost unchanged. The addition of
oxygen was found to significantly enhance the process performance of natural gas reforming. The utilization of air as an oxygen
source showed a superior process performance to pure oxygen in terms of reactant conversion and desired product selectivity.
The optimum energy consumption of 12.05 × 1024 eV per mole of reactants converted and 9.65 × 1024 eV per mole of hydrogen produced was obtained using air as an oxygen source and 3 stages of plasma reactors at a constant
residence time of 4.38 s. 相似文献
6.
Surakerk Onsuratoom Ratana Rujiravanit Thammanoon Sreethawong Seiichi Tokura Sumaeth Chavadej 《Plasma Chemistry and Plasma Processing》2010,30(1):191-206
In this work, the hydrophilic improvement of a woven PET surface was accomplished by a plasma technique. The woven PET surface
was plasma-treated by dielectric barrier discharge (DBD) under various operating conditions (electrode gap distance, plasma
treatment time, input voltage, and input frequency) and various gaseous environments (air, O2, N2, and Ar) in order to improve its hydrophilicity. It was experimentally found that a decrease in electrode gap distance and
an increase in input voltage increased the electric field strength, leading to higher hydrophilicity of the PET surface characterized
by wickability and contact angle measurements. In comparisons among the studied environmental gases, air gave the highest
hydrophilicity, being comparable to O2, while Ar and N2 gave lower hydrophilicity of the woven PET surface. The optimum conditions for a maximum hydrophilicity of the PET surface
were an electrode gap distance of 4 mm, a plasma treatment time of 10 s, an output voltage of 15 kV, and a frequency of 350 Hz
under air environment. After the plasma treatment under the obtained optimum conditions, the woven PET was loaded with Ag
particles using a AgNO3 aqueous solution in order to obtain the antimicrobial property. The plasma-treated woven PET loaded with Ag particles exhibited
good antimicrobial activity against both E. coli (gram-negative bacteria) and S. aureus (gram-positive bacteria). 相似文献
7.
Sreethawong T Chavadej S Ngamsinlapasathian S Yoshikawa S 《Journal of colloid and interface science》2006,300(1):219-224
A simple route of combined sol-gel process with surfactant-assisted templating technique was successfully employed for the first time to synthesize nanocrystalline mesoporous Dy(2)O(3) with narrow monomodal pore size distribution under mild conditions. The nanocrystalline Dy(2)O(3) with monomodal mesoporous characteristic was ultimately achieved by controlling the hydrolysis and condensation steps of dysprosium n-butoxide modified with acetylacetone in the presence of laurylamine hydrochloride surfactant aqueous solution. The synthesized material was methodically characterized by thermogravimetry and differential thermal analysis (TG-DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), selected-area electron diffraction (SAED), N(2) adsorption-desorption, Brunauer-Emmett-Teller (BET) surface area analysis, and Barrett-Joyner-Halenda (BJH) pore size distribution analysis. The particle size of the synthesized Dy(2)O(3) in nanosized range obtained from the SEM and HRTEM micrographs was in good accordance with the crystallite size estimated from the XRD result. The N(2) adsorption-desorption result exhibited hysteresis pattern with single loop, indicating the existence of monomodal mesopore. The extremely narrow pore size distribution with mean pore diameter in the mesopore region of the synthesized Dy(2)O(3) was also confirmed by the BJH result. 相似文献
8.
9.
Pannee Sophonvachiraporn Ratana Rujiravanit Thammanoon Sreethawong Seiichi Tokura Sumaeth Chavadej 《Plasma Chemistry and Plasma Processing》2011,31(1):233-249
In this work, a woven PET with an antimicrobial activity was prepared by depositing chitosan on its surface. Firstly, the
hydrophilic property of the PET surface was achieved by a plasma treatment using dielectric barrier discharge (DBD). The hydrophilic
property of the PET surface was characterized by wickability and contact angle measurements. The XPS analysis revealed an
increment of oxygen-containing polar groups, such as C–O and O–C=O, on the PET surface after the plasma treatment, resulting
in an enhanced hydrophilic property. The plasma-treated PET specimen was further deposited with chitosan by immersing in a
chitosan acetate aqueous solution. The effects of temperature, chitosan concentration, and number of rinses on the amount
of deposited chitosan on the PET surface were investigated. The disappearance of the above-mentioned polar groups from the
PET surface was clearly observed after the chitosan deposition, indicating the involvement of these functional groups in interacting
with the chitosan. The chitosan-deposited plasma-treated woven PET possessed an exceptionally high antimicrobial activity
against both E. coli (gram-negative bacteria) and S. aureus (gram-positive bacteria). 相似文献
10.
Thammanoon Sreethawong Natthaworanan Permsin Thitiporn Suttikul Sumaeth Chavadej 《Plasma Chemistry and Plasma Processing》2010,30(4):503-524
In this work, the epoxidation of ethylene under a cylindrical dielectric barrier discharge (DBD) reactor and a parallel DBD
reactor was comparatively studied. The effects of important operating parameters—feed O2/C2H4 molar ratio, applied voltage, input frequency, and residence time—were investigated on the reaction performance in terms
of reactant conversions, product selectivities, product yields, and power consumptions per molecule of ethylene converted
and per molecule of ethylene oxide produced. The optimum conditions obtained from the operating parameter investigation were
used for a comparative performance evaluation of both DBD reactor systems. It was found that under the optimum conditions
of each system, the cylindrical DBD system exhibited superior epoxidation performance for ethylene oxide production compared
to the parallel DBD system, indicating that the electrode geometry (electrode edge length-to-electrode surface area ratio)
plays a significant role in the ethylene epoxidation. 相似文献