Thermal energy dissipation

The computation of the thermal energy dissipated by a stirrer requires knowledge of the power number (Ne) and of the geometry of the stirrer. Some examples of power numbers for common stirrers are given in Table 2.6. 

Morales F, Abadia A, Abadia J (1998) Photosynthesis, quenching of chlorophyll fluorescence and thermal energy dissipation in iron-deficient sugar beet leaves. Aust J Plant Physiol 25 403-412... 

Light to Thermal Energy Dissipation in Response to Additional Environmental Stresses.253... 

The molecular mechanism of (Z-FA)/pH-dependent thermal energy dissipation remains to be established in vivo. However, based on determinations of the S, energy levels of these molecules (Frank et al., 1994 Phillip et al, 1996) a simple and direct singlet-singlet energy transfer downhill from Chi to zeaxanthin (and possibly antheraxanthin) has now been shown to be energetically feasible (see Chapters 13, Frank and 15, Horton et al.). 

Fig. /.Diurnal characterization of (top panels) incident PFD and the fraction of the xanthophyl I cycle converted to Z+A, (middle panels) energy dissipation activity quantified as nonphotochemical quenching of F , and the efficiency of open PS II units, and (bottom panels) the fractional allocation of excitation energy absorbed in PS II to photochemistry (P) and thermal energy dissipation (D). The area below the dashed I ines in the bottom two panels represents thermal dissipation associated with the inherent inefficiency of energy transfer within the PS II complex, whereas D above the dashed line represents the regulated thermal dissipation dependent upon Z+A. Plants were characterized in Boulder, Colorado in the summer of 1993 (sunflower) or the summer of, 1995 (Euonymus kiautschovicus). The data for sunflower are redrawn from Demmig-Adams and Adams (1996a) and Demmig-Adams et al. (1997), whereas the data for Euonymus kiautschovicus were redrawn from Verhoeven et al. (1998).

D. Increased Conversion to Zeaxanthin + Antheraxanthin (Z+A) and Increased Allocation ofAbsorbedLightto Thermal Energy Dissipation in Response to Additional Environmental Stresses... 

Fig. / P. 1II situ estimates of the rate of photochemistry, the rate of thermal energy dissipation, and the level of energy dissipation activity from the noiipliotocliemical quenching of F, and the levels or activities of Z+A, reduced ascorbate, ascorbate peroxidase (APX), superoxide dismutase (SOD), glutathione reductase (GR), catalase, and a-tocopherol in leaves of Finca major growing under four different PFDs or pumpkin growing under two PFDs in the field in Boulder, Colorado during the summer of 1995. Data from Logan et al.(1998).

Adams WW III and Demmig-Adams B (1995) The xanthophyll cycle and sustained thermal energy dissipation activity in Vinca minor and Euonymus kiautschovicus in winter. Plant Cell Environ 18 117-127... 

However, if the permeabihty ofthe thylakoid membrane for ascorbate restricts the rate of zeaxanthin formation it could have important consequences for thermal energy dissipation. Furthermore, at low lumenal pH in the light, when highest rates of zeaxanthin formation are expected to occur, a greater proportion ofthe lumenal ascorbate... 

Demmig-Adams, B. Adams, W.W. III. (2006). Photoprotection in an Ecological Context the Remarkable Complexity of Thermal Energy Dissipation. New Phytologist, Vol.172, No.l, (October 2006), pp. 11-21. 

Zhu, X.G., Ort, D.R., Whitmarsh, J. Long, S.P. (2004) The Slow Reversibility of PSII Thermal Energy Dissipation on Transfer from High to Low Light May Cause Large Losses in Carbon Gain by Crop Canopies A Theoretical Analysis. Journal of Experimental Botany, Vol.55, No.400, (March 2004), pp. 1167-1175. 

As current density increases (corresponding also to reduced cell voltage), the thermal energy dissipation flux will increase. The first term on the right-hand side of Eq. (5.110) represents Peltier heating. The second term on the right-hand side represents the sum of the activation (kinetic), concentration, ohmic, and crossover contributions to the heat generation. 

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