MEA Pt/C Cathode Catalyst Degradation during Repeated Anode Gas Exchange Cycles: In-Situ XAFS, STEM-EDS and Electrochemical Analysis

2014 ◽  
Vol 64 (3) ◽  
pp. 113-119 ◽  
Author(s):  
G. Samjeske ◽  
K. Higashi ◽  
S. Takao ◽  
K. Nagamatsu ◽  
K. Nagasawa ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Electrochemical Analysis ◽  
Cathode Catalyst ◽  
In Situ Xafs

In-Situ XAFS Study to Monitor the Degradation of an Fe/N/C Cathode Catalyst in PEMFC

2019 ◽  
Vol 92 (8) ◽  
pp. 621-625
Author(s):  
Yuta Nabae ◽  
Shinsuke Nagata ◽  
Keizo Kusaba ◽  
Tsutomu Aoki ◽  
Qiuyi Yuan ◽  
...  
Keyword(s):  
Cathode Catalyst ◽  
In Situ Xafs

Kinetic analysis of Ag particle redispersion into ZSM-5 in the presence of coke using in situ XAFS

2021 ◽  
Author(s):  
Kazumasa Murata ◽  
Junya Ohyama ◽  
Atsushi Satsuma
Keyword(s):  
Fine Structure ◽  
Kinetic Analysis ◽  
X Ray ◽  
Xafs Spectroscopy ◽  
Absorption Fine ◽  
Ag Particles ◽  
In Situ Xafs ◽  
Ag Particle ◽  
X Ray Absorption

In the present study, the redispersion behavior of Ag particles on ZSM-5 in the presence of coke was observed using in situ X-ray absorption fine structure (XAFS) spectroscopy.

scholarly journals Measurement of Gas Exchange on Excised Grapevine Leaves Does Not Differ from In Situ Leaves, and Potentially Shortens Sampling Time

2021 ◽  
Vol 11 (8) ◽  
pp. 3644
Author(s):  
Suraj Kar ◽  
Thayne Montague ◽  
Antonio Villanueva-Morales ◽  
Edward Hellman
Keyword(s):  
Gas Exchange ◽  
Time Window ◽  
Leaf Gas Exchange ◽  
Growth Yield ◽  
Abiotic Stress Response ◽  
Gas Exchange Parameters ◽  
Minute Post ◽  
Exchange Measurement ◽  
Similar Accuracy

Use of leaf gas exchange measurement enhances the characterization of growth, yield, physiology, and abiotic stress response in grapevines. Accuracy of a crop response model depends upon sample size, which is often limited due to the prolonged time needed to complete gas exchange measurement using currently available infra-red gas analyzer systems. In this experiment, we measured mid-day gas exchange of excised and in situ leaves from field grown wine grape (Vitis vinifera) cultivars. Depending upon cultivar, we found measuring gas exchange on excised leaves under a limited time window post excision gives similar accuracy in measurement of gas exchange parameters as in situ leaves. A measurement within a minute post leaf excision can give between 96.4 and 99.5% accuracy compared to pre-excision values. When compared to previous field data, we found the leaf excision technique reduced time between consecutive gas exchange measurements by about a third compared to in situ leaves (57.52 ± 0.39 s and 86.96 ± 0.41 s, for excised and in situ, respectively). Therefore, leaf excision may allow a 50% increase in experimental sampling size. This technique could solve the challenge of insufficient sample numbers, often reported by researchers worldwide while studying grapevine leaf gas exchange using portable gas exchange systems under field conditions.

In Situ XAFS and NMR Study of Rhodium-Catalyzed Dehydrogenation of Dimethylamine Borane

2005 ◽  
Vol 127 (10) ◽  
pp. 3254-3255 ◽  
Author(s):  
Yongsheng Chen ◽  
John L. Fulton ◽  
John C. Linehan ◽  
Tom Autrey
Keyword(s):  
Nmr Study ◽  
In Situ Xafs ◽  
Dimethylamine Borane

Gas exchange in nonperfused dog lungs

1981 ◽  
Vol 51 (5) ◽  
pp. 1261-1267 ◽  
Author(s):  
J. W. Shepard ◽  
V. D. Minh ◽  
G. F. Dolan
Keyword(s):  
Gas Exchange ◽  
Minute Ventilation ◽  
Left Lung ◽  
Co2 Concentration ◽  
Gas Transfer ◽  
O2 Uptake ◽  
Tissue Metabolism ◽  
End Tidal

Gas exchange was studied under conditions of zero perfusion both in situ and in vitro. Six dogs, anesthetized with pentobarbital sodium, underwent surgical interruption of both pulmonary and bronchial circulations to the left lung. Despite the absence of perfusion, O2 uptake for the left lung ranged from 0.76 to 0.98 ml/min, whereas CO2 elimination greatly exceeded O2 uptake ranging from 1.68 to 4.34 ml/min. In addition, CO2 output was observed to vary directly with the level of minute ventilation (VE) and inversely with end-tidal CO2 concentration. To investigate the mechanisms responsible for these findings we studied 20 excised, ventilated, but nonperfused dog lungs to evaluate the relative roles of tissue metabolism and transpleural diffusion to gas exchange. The results obtained with these excised lungs under conditions of varying VE and extrapleural gas concentrations indicate that the high respiratory exchange ratios observed in situ can be explained by the greater rate with which CO2 diffuses through the pleura, and that reduced ventilation decreases total gas transfer by decreasing the transpleural partial pressure driving gradient. Our data further document that the concentration of CO2 in alveolar gas may differ significantly from that present in inspired gas under conditions of ventilation-perfusion ratio equal to infinity, and that tissue metabolism as well as transpleural diffusion contribute to gas exchange in nonperfused lung.

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