scholarly journals Terrestrial biosphere models may overestimate Arctic CO 2 assimilation if they do not account for decreased quantum yield and convexity at low temperature

2019 ◽  
Vol 223 (1) ◽  
pp. 167-179 ◽  
Author(s):  
Alistair Rogers ◽  
Shawn P. Serbin ◽  
Kim S. Ely ◽  
Stan D. Wullschleger
Keyword(s):  
Quantum Yield ◽  
Low Temperature ◽  
Terrestrial Biosphere

Chilling Injury in Mature Leaves of Rice. II. Varietal Differences in the Response to Interactions Between Low Temperature and Light Measured by Chlorophyll Fluorescence at 77k and the Quantum Yield of Photosynthesis

1989 ◽  
Vol 16 (4) ◽  
pp. 339 ◽  
Author(s):  
LK Huang ◽  
CB Osmond ◽  
I Terashima
Keyword(s):  
Chlorophyll Fluorescence ◽  
Quantum Yield ◽  
Low Temperature ◽  
Chilling Injury ◽  
Bright Light ◽  
Co2 Exchange ◽  
Fluorescence Properties ◽  
Screening Programs ◽  
Detached Leaves

Characteristics of photosynthetic CO2 exchange and 77K chlorophyll fluorescence in attached and detached leaves of rice were used to examine differences between five varieties exposed to a combination of bright light and low temperature. Preliminary studies established that attached leaves of varieties did not differ in the light dependence of photosynthesis at CO2 saturation or fluorescence properties when grown in full sunlight and measured under comparable conditions. All varieties showed a depression in maximum photosynthetic rate, but not in quantum yield or chlorophyll fluorescence when examined in the late afternoon after a period of active photosynthesis in air at 25°C. Attached leaves of all varieties showed depression of the maximum rate of photosynthesis and of quantum yield as well as an increase in Fo and a decrease in Fv/Fm of chlorophyll fluorescence at 77K following horizontal exposure to bright light in air at 25°. Similar results were obtained with detached leaves exposed to bright light while floating on water at 25°C. The rate of photosynthetic CO2 fixation in air as a function of temperature was examined in attached leaves of two representative varieties, Japonica-like cv. Hungarian- 1, and Indica-derived cv. IR-8. The former was capable to rates of photosynthesis at 10°C which were twice those of the latter, although the rates at 25°C were similar in both varieties. When detached leaves of five varieties of rice were floated on water at 10°C while exposed to 700 �mol photons m-2 s-1 of white light, consistent differences in the response of quantum yield, light and CO2 saturated O2 evolion and 77K fluorescence properties were found. Exposure to bright light at low temperature exaggerated the effects of bright light on these parameters, and larger effects were found in the Indica-derived varieties than in Japonica-like cv. Hungarian-1. These treatments at 10°C did not influence the extent of increase in Fo, but led to a greater decline in Fv/Fm of 77K chlorophyll fluorescence compared with treatments at 25°C. Varieties in which there was a larger decline in Fv/Fm showed slower recovery of variable fluorescence in the dark at 25°C, and especially at 10°C. These responses to in vitro treatments seem capable of distinguishing varieties such as cvv. Hungarian-1 and Er Bai Ai, which are believed to be more chilling tolerant by other criteria, from chilling sensitive varieties such as Gui Chao-2 and IR-8. Even though there is potential for application of these methods in screening programs, there is little evidence that the lesions in primary photosynthetic processes indicated by these methods are significant determinants of photosynthesis under field conditions.

scholarly journals Highly sensitive and precise optical temperature sensors based on new luminescent Tb3+/Eu3+ tetrakis complexes with imidazolic counterions

2020 ◽  
Vol 1 (6) ◽  
pp. 1988-1995
Author(s):  
Lucca B. Guimarães ◽  
Alexandre M. P. Botas ◽  
Maria C. F. C. Felinto ◽  
Rute A. S. Ferreira ◽  
Luis D. Carlos ◽  
...  
Keyword(s):  
Quantum Yield ◽  
Low Temperature ◽  
Temperature Sensors ◽  
Highly Sensitive ◽  
High Emission ◽  
Yield Values ◽  
Emission Quantum Yield

Precise optical temperature sensors based on luminescent Tb3+:Eu3+ tetrakis complexes with imidazolic counterions with high emission quantum yield values and low temperature uncertainty.

THE MERCURY PHOTOSENSITIZED DECOMPOSITION OF ETHANE: III. THE REACTION IN THE PRESENCE OF ADDED DEUTERIUM

1938 ◽  
Vol 16b (9) ◽  
pp. 314-318 ◽  
Author(s):  
E. W. R. Steacie ◽  
W. A. Alexander ◽  
N. W. F. Phillips
Keyword(s):  
Quantum Yield ◽  
Low Temperature ◽  
Fractional Distillation ◽  
Deuterium Content ◽  
Methyl Radicals ◽  
Rapid Exchange ◽  
Ethyl Radicals

The mercury photosensitized reactions of ethane-deuterium mixtures have been investigated. The products of the reaction were separated by low-temperature fractional distillation, and the deuterium content of each was determined. It was found that the methane produced was highly deuterized, while the residual ethane was only slightly deuterized. Propane and butane were also considerably deuterized. It is concluded:(a) That rapid exchange of methyl radicals and deuterium atoms occurs, as previously suggested by Morikawa, Benedict, and Taylor;(b) That ethyl radicals are rapidly exchanged in a similar way;(c) That the reactions[Formula: see text]and[Formula: see text]do not occur to any great extent, and hence the low quantum yield of the reaction cannot be ascribed to re-formation of ethane.

THE PHOTOLYSIS OF KETENE AT LOW TEMPERATURES

1957 ◽  
Vol 35 (10) ◽  
pp. 1137-1138 ◽  
Author(s):  
W. G. Paterson ◽  
H. Gesser
Keyword(s):  
Carbon Monoxide ◽  
Quantum Yield ◽  
Low Temperature ◽  
Low Temperatures ◽  
Photochemical Decomposition

The photochemical decomposition of ketene at 2700 Å has been investigated at −78 °C. The quantum yield of carbon monoxide is two, indicating that the recombination of methylene radicals does not occur at this low temperature.

Changes in the Photophysical Properties with Heavy Atoms and the Effects of Modulus for 4-Phenylphenol in Solid-Matrix Luminescence

1992 ◽  
Vol 46 (6) ◽  
pp. 988-993 ◽  
Author(s):  
Barbara B. Purdy ◽  
Robert J. Hurtubise
Keyword(s):  
Quantum Yield ◽  
Low Temperature ◽  
Young’S Modulus ◽  
Filter Paper ◽  
Room Temperature ◽  
Heavy Atom ◽  
Heavy Atom Effect ◽  
Phosphorescence Quantum Yield ◽  
Atom Effect ◽  
Fluorescence And Phosphorescence

Fluorescence and phosphorescence quantum yields and fluorescence and phosphorescence lifetimes were obtained for 4-phenylphenol adsorbed on filter paper with either NaCl, NaBr, or Nal at 296 and 93 K. From these data several photophysical parameters were calculated and compared. In general, the photophysical data showed that the heavy-atom effect was operative, with NaI showing the greatest effect. However, NaBr at 93 K showed both the heavy-atom effect and another effect which was particular to NaBr. For 4-phenylphenol with NaI, very little increase occurred for the phosphorescence quantum yield from 296 to 93 K, which indicated that almost maximum phosphorescence quantum yield was achieved at room temperature for 4-phenylphenol with NaI present. The increase in phosphorescence lifetime for 4-phenylphenol from room temperature to low temperature was shown to be related to the increase in the Young's modulus of filter paper as the temperature was lowered. Calculated phosphorescence lifetimes at room temperature and at low temperature with equations that included Young's modulus values agreed very well with experimental lifetime values.

Sign in / Sign up

Export Citation Format

Share Document