The Experts below are selected from a list of 2364 Experts worldwide ranked by ideXlab platform
Junbo Hou - One of the best experts on this subject based on the ideXlab platform.
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catalytic hydrogen oxygen reaction assisted the proton exchange membrane fuel cell pemfc startup at Subzero Temperature
Journal of Power Sources, 2008Co-Authors: Shucheng Sun, Junbo Hou, Pingwen Ming, Hongmei Yu, Zhigang Shao, Baolian Yi, Zhongjun HouAbstract:Fuel cells for automobile application need to operate in a wide Temperature range including freezing Temperature. However, the rapid startup of a proton exchange membrane fuel cell (PEMFC) at subfreezing Temperature, e.g., -20 degrees C, is very difficult. A cold-start procedure was developed, which made hydrogen and oxygen react to heat the fuel cell considering that the FC flow channel was the characteristic of microchannel reactor. The effect of hydrogen and oxygen reaction on fuel cell performance at ambient Temperature was also investigated. The electrochemical characterizations such as I-V plot and cyclic voltammetry (CV) were performed. The heat generated rate for either the single cell or the stack was calculated. The results showed that the heat generated rate was proportional to the gas flow rate when H-2 concentration and the active area were constant. The fuel cell Temperature rose rapidly and steadily by controlling gas flow rate. (c) 2007 Elsevier B.V. All rights reserved.
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electrochemical impedance investigation of proton exchange membrane fuel cells experienced Subzero Temperature
Journal of Power Sources, 2007Co-Authors: Junbo Hou, Wei Song, Zhigang ShaoAbstract:Polarization losses of the fuel cells with different residual water amount frozen at Subzero Temperature were investigated by electrochemical impedance spectroscopy (EIS) taking into account the ohmic resistance, charge transfer process, and oxygen mass transport. The potential-dependent impedance before and after eight freeze/thaw cycles suggested that the ohmic resistance did not change, while the change of the charge transfer resistance greatly depended on the residual water amount. Among the four cells, the mass transport resistance of the cell with the largest water amount increased significantly even at the small current density region. According to the thin film-flooded agglomerate model, the interfacial charge transfer process and oxygen mass transport within the agglomerate and through the ionomer thin film in the catalyst layer both contributed to the high frequency impedance arc. From the analysis of the Tafel slopes, the mechanism of the oxygen reduction reaction (ORR) was the same after the cells experienced Subzero Temperature. The agglomerate diffusion changed a little in all cells and the thin film diffusion effect was obvious for the cell with the largest residual water amount. These results indicated that the slower oxygen diffusion within the catalyst layer (CL) was the main contributor for the evident performance loss after eight freeze/thaw cycles.
Atsushi Akane - One of the best experts on this subject based on the ideXlab platform.
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extraction of thiamylal in serum using hydrophilic acetonitrile with Subzero Temperature and salting out methods
Analytical Chemistry, 2004Co-Authors: Manabu Yoshida, Atsushi Akane, Toshimitsu Watabiki, Mayumi Nishikawa, Hitoshi TsuchihashiAbstract:For high-performance liquid chromatography (HPLC) of thiamylal, one of the barbiturates, the drug in serum samples was extracted by two alternative liquid−liquid extraction techniques using hydrophilic acetonitrile as a solvent and Subzero-Temperature and salting-out methods. Acetonitrile was mixed with the sample, separated by cooling at −20 °C or addition of sodium chloride, and injected directly into the HPLC apparatus. In both the methods, thiamylal was extracted effectively in the acetonitrile phase and pH adjustment of the sample was not required. The salting-out extraction method is rapid and would be suitable for quantitation of drugs in many samples. To avoid coextraction of added salt, the Subzero-Temperature extraction method was applied to identification of thiamylal by gas chromatography/mass spectrometry and liquid chromatography−tandem mass spectrometry.
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Subzero-Temperature liquid-liquid extraction of benzodiazepines for high-performance liquid chromatography.
Analytical chemistry, 1999Co-Authors: Manabu Yoshida, Atsushi AkaneAbstract:On the basis of the phenomenon that hydrophilic acetonitrile is separated from the aqueous phase at -20 degrees C, we employed a novel extraction method, "Subzero-Temperature liquid-liquid extraction", to extract benzodiazepines (estazolam and triazolam) from serum or aqueous solution for liquid chromatography. A 1:1 mixture of acetonitrile and the specimen was cooled at -20 degrees C for 20 min to separate the acetonitrile and aqueous phases. The acetonitrile phase was directly injected into a high-performance liquid chromatograph. Recovery rates of the drugs following the first Subzero-Temperature liquid-liquid extraction were 50.3 +/- 0.6-54.0 +/- 0.9%, which were lower than those (73.9 +/- 3.3-80.6 +/- 0.6% and 81.6 +/- 4.7-96.1 +/- 2.6%) of the first conventional liquid-liquid extraction using diethyl ether and solid-phase extraction using a Sep-Pak C18 column, respectively. However, three to four repeated Subzero-Temperature liquid-liquid extractions and conventional liquid-liquid extractions resulted in recovery of almost 100% of the drugs. In the chromatogram of the benzodiazepines recovered from serum by the Subzero-Temperature extraction, no coextracted component interfered with determination of the drugs. Detection limits of the drugs were 0.02-0.08 microgram/mL, and coefficients of variance were 1.14-2.17% suggesting high reproducibility.
Xiaoying Zheng - One of the best experts on this subject based on the ideXlab platform.
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water induced strong protection against acute exposure to low Subzero Temperature of adult aedes albopictus
PLOS Neglected Tropical Diseases, 2019Co-Authors: Meichun Zhang, Dongjing Zhang, Qiang Sun, Yali Fan, Xiaoying ZhengAbstract:As an important vector of dengue and Zika, Aedes albopictus has been the fastest spreading invasive mosquitoes in the world over the last 3-4 decades. Cold tolerance is important for survival and expansion of insects. Ae. albopictus adults are generally considered to be cold-intolerant that cannot survive at Subzero Temperature. However, we found that Ae. albopictus could survive for several hours' exposure to -9 to -19 oC so long as it was exposed with water. Median lethal time (LT50) of Ae. albopictus exposed to -15 and -19 oC with water increased by more than 100 times compared to those exposed to the same Subzero Temperature without water. This phenomenon also existed in adult Aedes aegypti and Culex quinquefasciatus. Ae. albopictus female adults which exposed to low Subzero Temperature at -9 oC with water had similar longevity and reproductive capacity to those of females without cold exposure. Cold exposure after a blood meal also have no detrimental impact on survival capacity of female adult Ae. albopictus compared with those cold exposed without a blood meal. Moreover, our results showed that rapid cold hardening (RCH) was induced in Ae. albopictus during exposing to low Subzero Temperature with water. Both the RCH and the relative high Subzero Temperature of water immediate after cold exposure might provide this strong protection against low Subzero Temperature. The molecular basis of water-induced protection for Ae. albopictus might refer to the increased glycerol during cold exposure, as well as the increased glucose and hsp70 during recovery from cold exposure. Our results suggested that the water-induced strong protection against acute decrease of air Temperature for adult mosquitoes might be important for the survival and rapid expansion of Ae. albopictus.
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Survival of adult female Ae. albopictus after exposure to different Subzero Temperature.
2019Co-Authors: Meichun Zhang, Dongjing Zhang, Qiang Sun, Yali Fan, Xiaoying ZhengAbstract:Adult female Ae. albopictus were transferred from room Temperature to different Subzero Temperature with (A) or without water (B). Adult mosquitoes were removed (at 1-h interval for mosquitoes exposing with water or at 1- or 5-min interval for mosquitoes exposing without water) from Subzero Temperature and recovered under normal rearing condition until 100% mortality were reached. N = 3 groups of 20 adult mosquitoes for each data point.
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The change of water Temperature after transferring from room Temperature to different low Subzero Temperature.
2019Co-Authors: Meichun Zhang, Dongjing Zhang, Qiang Sun, Yali Fan, Xiaoying ZhengAbstract:The Temperatures of water were monitored by a mini-thermometer at 5-min interval. The mini-thermometer with ice was removed from Subzero Temperature at 12h after exposure and the ice was naturally melted.
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Survival of adult mosquitoes after exposure to low Subzero Temperature.
2019Co-Authors: Meichun Zhang, Dongjing Zhang, Qiang Sun, Yali Fan, Xiaoying ZhengAbstract:Adult male Ae. albopictus (A) and female Ae. aegypti and Cx. quinquefasciatus (B) were transferred from room Temperature to -15 oC with (right of A and B) or without water (left of A and B). Adult mosquitoes were removed (at 1-h interval for mosquitoes exposing with water or at 1- or 2-min interval for mosquitoes exposing without water) from Subzero Temperature and recovered under normal rearing condition until 100% mortality were reached. N = 3 groups of 20 adult mosquitoes for each data point.
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Survival of adult female Ae. albopictus after exposure to high Subzero Temperature without water.
2019Co-Authors: Meichun Zhang, Dongjing Zhang, Qiang Sun, Yali Fan, Xiaoying ZhengAbstract:Adult female Ae. albopictus were transferred from room Temperature to different high Subzero Temperatures without water. Adult mosquitoes were removed at 10-min interval from Subzero Temperature and recovered under normal rearing condition until 100% mortality were reached. N = 3 groups of 20 adult mosquitoes for each data point.
Zhigang Shao - One of the best experts on this subject based on the ideXlab platform.
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catalytic hydrogen oxygen reaction assisted the proton exchange membrane fuel cell pemfc startup at Subzero Temperature
Journal of Power Sources, 2008Co-Authors: Shucheng Sun, Junbo Hou, Pingwen Ming, Hongmei Yu, Zhigang Shao, Baolian Yi, Zhongjun HouAbstract:Fuel cells for automobile application need to operate in a wide Temperature range including freezing Temperature. However, the rapid startup of a proton exchange membrane fuel cell (PEMFC) at subfreezing Temperature, e.g., -20 degrees C, is very difficult. A cold-start procedure was developed, which made hydrogen and oxygen react to heat the fuel cell considering that the FC flow channel was the characteristic of microchannel reactor. The effect of hydrogen and oxygen reaction on fuel cell performance at ambient Temperature was also investigated. The electrochemical characterizations such as I-V plot and cyclic voltammetry (CV) were performed. The heat generated rate for either the single cell or the stack was calculated. The results showed that the heat generated rate was proportional to the gas flow rate when H-2 concentration and the active area were constant. The fuel cell Temperature rose rapidly and steadily by controlling gas flow rate. (c) 2007 Elsevier B.V. All rights reserved.
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electrochemical impedance investigation of proton exchange membrane fuel cells experienced Subzero Temperature
Journal of Power Sources, 2007Co-Authors: Junbo Hou, Wei Song, Zhigang ShaoAbstract:Polarization losses of the fuel cells with different residual water amount frozen at Subzero Temperature were investigated by electrochemical impedance spectroscopy (EIS) taking into account the ohmic resistance, charge transfer process, and oxygen mass transport. The potential-dependent impedance before and after eight freeze/thaw cycles suggested that the ohmic resistance did not change, while the change of the charge transfer resistance greatly depended on the residual water amount. Among the four cells, the mass transport resistance of the cell with the largest water amount increased significantly even at the small current density region. According to the thin film-flooded agglomerate model, the interfacial charge transfer process and oxygen mass transport within the agglomerate and through the ionomer thin film in the catalyst layer both contributed to the high frequency impedance arc. From the analysis of the Tafel slopes, the mechanism of the oxygen reduction reaction (ORR) was the same after the cells experienced Subzero Temperature. The agglomerate diffusion changed a little in all cells and the thin film diffusion effect was obvious for the cell with the largest residual water amount. These results indicated that the slower oxygen diffusion within the catalyst layer (CL) was the main contributor for the evident performance loss after eight freeze/thaw cycles.
Manabu Yoshida - One of the best experts on this subject based on the ideXlab platform.
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extraction of thiamylal in serum using hydrophilic acetonitrile with Subzero Temperature and salting out methods
Analytical Chemistry, 2004Co-Authors: Manabu Yoshida, Atsushi Akane, Toshimitsu Watabiki, Mayumi Nishikawa, Hitoshi TsuchihashiAbstract:For high-performance liquid chromatography (HPLC) of thiamylal, one of the barbiturates, the drug in serum samples was extracted by two alternative liquid−liquid extraction techniques using hydrophilic acetonitrile as a solvent and Subzero-Temperature and salting-out methods. Acetonitrile was mixed with the sample, separated by cooling at −20 °C or addition of sodium chloride, and injected directly into the HPLC apparatus. In both the methods, thiamylal was extracted effectively in the acetonitrile phase and pH adjustment of the sample was not required. The salting-out extraction method is rapid and would be suitable for quantitation of drugs in many samples. To avoid coextraction of added salt, the Subzero-Temperature extraction method was applied to identification of thiamylal by gas chromatography/mass spectrometry and liquid chromatography−tandem mass spectrometry.
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Subzero-Temperature liquid-liquid extraction of benzodiazepines for high-performance liquid chromatography.
Analytical chemistry, 1999Co-Authors: Manabu Yoshida, Atsushi AkaneAbstract:On the basis of the phenomenon that hydrophilic acetonitrile is separated from the aqueous phase at -20 degrees C, we employed a novel extraction method, "Subzero-Temperature liquid-liquid extraction", to extract benzodiazepines (estazolam and triazolam) from serum or aqueous solution for liquid chromatography. A 1:1 mixture of acetonitrile and the specimen was cooled at -20 degrees C for 20 min to separate the acetonitrile and aqueous phases. The acetonitrile phase was directly injected into a high-performance liquid chromatograph. Recovery rates of the drugs following the first Subzero-Temperature liquid-liquid extraction were 50.3 +/- 0.6-54.0 +/- 0.9%, which were lower than those (73.9 +/- 3.3-80.6 +/- 0.6% and 81.6 +/- 4.7-96.1 +/- 2.6%) of the first conventional liquid-liquid extraction using diethyl ether and solid-phase extraction using a Sep-Pak C18 column, respectively. However, three to four repeated Subzero-Temperature liquid-liquid extractions and conventional liquid-liquid extractions resulted in recovery of almost 100% of the drugs. In the chromatogram of the benzodiazepines recovered from serum by the Subzero-Temperature extraction, no coextracted component interfered with determination of the drugs. Detection limits of the drugs were 0.02-0.08 microgram/mL, and coefficients of variance were 1.14-2.17% suggesting high reproducibility.
