"Sun Leaves" and "Shade Leaves": Differences in Convective Heat Dissipation

Ecology ◽  
1968 ◽  
Vol 49 (6) ◽  
pp. 1203-1204 ◽  
Author(s):  
Steven Vogel
Keyword(s):  
Convective Heat ◽  
Heat Dissipation ◽  
Shade Leaves ◽  
Sun Leaves

scholarly journals Influence of Ambient Temperature on Radiative and Convective Heat Dissipation Ratio in Polymer Heat Sinks

Polymers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 2286
Author(s):  
Jan Kominek ◽  
Martin Zachar ◽  
Michal Guzej ◽  
Erik Bartuli ◽  
Petr Kotrbacek
Keyword(s):  
Heat Transfer ◽  
Ambient Temperature ◽  
Convective Heat ◽  
Heat Dissipation ◽  
High Surface ◽  
Heat Sinks ◽  
Fourth Power ◽  
Molding Process ◽  
Ambient Temperatures ◽  
University Of Technology

Miniaturization of electronic devices leads to new heat dissipation challenges and traditional cooling methods need to be replaced by new better ones. Polymer heat sinks may, thanks to their unique properties, replace standardly used heat sink materials in certain applications, especially in applications with high ambient temperature. Polymers natively dispose of high surface emissivity in comparison with glossy metals. This high emissivity allows a larger amount of heat to be dissipated to the ambient with the fourth power of its absolute surface temperature. This paper shows the change in radiative and convective heat transfer from polymer heat sinks used in different ambient temperatures. Furthermore, the observed polymer heat sinks have differently oriented graphite filler caused by their molding process differences, therefore their thermal conductivity anisotropies and overall cooling efficiencies also differ. Furthermore, it is also shown that a high radiative heat transfer leads to minimizing these cooling efficiency differences between these polymer heat sinks of the same geometry. The measurements were conducted at HEATLAB, Brno University of Technology.

scholarly journals Seasonal Variation of Tannin and Nutrient in Aegiceras corniculatum Leaves in Zhangjiang Mangrove Ecosystem

2015 ◽  
Vol 9 (1) ◽  
pp. 143-148
Author(s):  
Minshen Huang ◽  
Lihua Zhang ◽  
Shudong Wei ◽  
Qi Zeng ◽  
Haichao Zhou ◽  
...  
Keyword(s):  
Condensed Tannins ◽  
Insect Pests ◽  
Mangrove Ecosystem ◽  
Plant Diseases ◽  
The Sun ◽  
Aegiceras Corniculatum ◽  
Significant Difference ◽  
Sun And Shade ◽  
Shade Leaves ◽  
Sun Leaves

Seasonal dynamics of total phenolics (TP), extractable condensed tannins (ECT), protein-bound condensed tannins (PBCT), fiber-bound condensed tannins (FBCT), total condensed tannins (TCT) and nitrogen contents in sun and shade leaves of Aegiceras corniculatum were studied in the Zhangjiang Estuary, Fujian Province, China. The contents of TP, ECT and TCT in the sun leaves were significantly higher than those in the shade leaves through the season. The N content in sun leaves was higher than that in shade leaves in the autumn, while it was lower in the summer, and there was no significant difference in the winter and spring. With the respect to the P through the year, P content in the sun leaves was different between seasons, with the highest in winter and the lowest in summer. In addition, the TP:N and ECT:N ratios in sun leaves were significantly higher than those in shade leaves except in autumn. High tannin levels and TP:N and ECT:N ratios in the sun leaves not only can reduce oxidative stress, but also improve the ability of resisting plant diseases and insect pests.

scholarly journals Morphological and anatomical aspects of the leaves of Rhizophora mangle L. (Rhizophoraceae) under different lighting conditions / Aspectos morfológicos e anatômicos das folhas de Rhizophora mangle L. (Rhizophoraceae) sob diferentes condições de luz

2016 ◽  
Vol 12 (2) ◽  
pp. 74
Author(s):  
Camilla Reis Augusto da Silva ◽  
Marcelo Dos Santos Silva ◽  
Léa Maria Dos Santos Lopes Ferreira ◽  
Kelly Regina Batista Leite ◽  
Lazaro Benedito da Silva
Keyword(s):  
Stomatal Density ◽  
Rhizophora Mangle ◽  
Palisade Parenchyma ◽  
Abaxial Epidermis ◽  
Lighting Conditions ◽  
Ocular Micrometer ◽  
Significant Difference ◽  
Sun And Shade ◽  
Shade Leaves ◽  
Sun Leaves

The basis of differentiation between sun and shade leaves is related to different light intensities. In order to understand the adaptability of the leaves of Rhizophora mangle L., associated with different lighting conditions, leaves were collected from the upper peripheral six individuals (sun leaves) and the lower region of the same internal (shade leaves). The variables analyzed leaf thickness, palisade parenchyma, adaxial and abaxial epidermis, adaxial and abaxial cuticle, stomatal density and index. Measurements were made ??on microscope equipped with ocular micrometer. Sun leaves were lower and with more xeromorphic characteristics, such as increased thickness of the cuticle and the adaxial and abaxial epidermis. The palisade parenchyma and limbus showed up thicker than shade leaves, with no significant difference between the cuticle of the abaxial surface. It was also observed a higher frequency of stomata per mm², an average of 70/mm², while shade leaves showed 47/mm², with no differences between length and width. Differences between the sun leaves and shade leaves indicate adaptive capacity of this species to remain active at different light conditions.

scholarly journals Carbon gain optimization in five broadleaf deciduous trees in response to light variation within the crown: correlations among morphological, anatomical and physiological leaf traits

2015 ◽  
Vol 74 (1) ◽  
pp. 71-94 ◽  
Author(s):  
Rosangela Catoni ◽  
Loretta Gratani ◽  
Francesco Sartori ◽  
Laura Varone ◽  
Mirko U. Granata
Keyword(s):  
Phenotypic Plasticity ◽  
Deciduous Forest ◽  
Light Variation ◽  
Stress Factors ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Carbon Gain ◽  
Deciduous Species ◽  
Shade Leaves ◽  
Sun Leaves

AbstractLeaf trait variations in five deciduous species (Quercus robur, Corylus avellana, Populus alba, Acer campestre, Robinia pseudoacacia) growing in an old broadleaf deciduous forest in response to light variation within the tree crown was analyzed. Net photosynthetic rate (PN), leaf respiration rate (R) and the photosynthetic nitrogen use efficiency were, on average, more than 100% higher in sun than in shade leaves. A. campestre and C. avellana sun leaves had the highest specific leaf area (SLA, 156.0 ± 17.9 cm2 g-1) and the lowest total leaf thickness (L, 101.9 ± 8.8 μm) underlining their shade-tolerance. Among the shade-intolerant species (Q. robur, P. alba and R. pseudoacacia), Q. robur had the lowest SLA and the highest L in sun leaves (130.6 ± 10.0 cm2 g-1 and 160.8 ± 9.6 μm, respectively) since shade-intolerant species typically have thicker leaves. The higher PN decrease in respect to R decrease from sun to shade leaves attested the higher sensitivity of PN than R to light variations within the crown. This determined a 69% lower R/PN in sun than in shade leaves. This result is further attested by the significant correlation between PN and the relative photosynthetic photon flux density. The shade-tolerant species have a 76% higher R/PN ratio than the shade-intolerant ones. The measured leaf phenotypic plasticity (PI = 0.35) was in the range of broadleaf deciduous species. Plasticity is a key trait useful to quantify plant response to environmental stimuli. It is defined as the ability of a genotype to produce different phenotypes depending on the environment. Among the considered species, Q. robur showed the highest PI (0.39) and P. alba the lowest (0.29). Knowledge on phenotypic plasticity is important in making hypotheses about the dynamics of the studied forest in consideration of environmental stress factors, including invasive species competition and global climate change.

Mangrove Photosynthesis: Response to High-Irradiance Stress

1988 ◽  
Vol 15 (2) ◽  
pp. 43 ◽  
Author(s):  
O Bjorkman ◽  
B Demmig ◽  
TJ Andrews
Keyword(s):  
Energy Dissipation ◽  
Photosystem Ii ◽  
Energy Conversion ◽  
O2 Evolution ◽  
Photon Yield ◽  
Mangrove Species ◽  
Reaction Centres ◽  
Fluorescence Characteristics ◽  
Shade Leaves ◽  
Sun Leaves

Efficiencies of photosynthetic energy conversion were determined in sun and shade leaves of several mangrove species, growing in an open intertidal habitat in North Queensland, by measuring the maximum photon yield of O2 evolution and 77K chlorophyll fluorescence characteristics. Preliminary meas- urements confirmed that mangrove leaves have low water potentials, low stomatal conductances and low light-saturated CO2 exchange rates. Mangrove sun leaves therefore received a very large excess of excitation energy. Mangrove shade leaves had as high a photon yield of O2 evolution as non-mangrove leaves and their fluorescence characteristics were normal, showing that the energy conversion efficiency was unaffected by the high salinity. Mangrove sun leaves had markedly depressed photon yields and fluorescence was severely quenched showing that the efficiency of the photochemistry of photosystem II was reduced. The efficiency of energy conversion decreased with an increased radiation receipt. No such depression was detected in sun leaves of non-mangrove species growing in adjacent non-saline sites. Shading of man- grove sun leaves resulted in an increase in the efficiency of energy conversion but, in most species, more than 1 week was required for these leaves to reach the efficiency of shade leaves. Leaves exposed to direct sunlight had somewhat higher efficiencies in mangrove plants cultivated in 10% seawater as compared with full-strength seawater but the salinity of the culture solution had little effect on the increase in the efficiency upon shading. Field and laboratory fluorescence measurements indicated that the reduced efficiency of energy conversion in mangrove sun leaves resulted from a large increase in the rate constant for radiationless energy dissipation in the antenna chlorophyll rather than from damage to the photosystem II reaction centres. We propose that this increase in radiationless energy dissipation serves to protect the reaction centres against damage by excessive excitation.

Sun-shade patterns of leaf carotenoid composition in 86 species of neotropical forest plants

2009 ◽  
Vol 36 (1) ◽  
pp. 20 ◽  
Author(s):  
Shizue Matsubara ◽  
G. Heinrich Krause ◽  
Jorge Aranda ◽  
Aurelio Virgo ◽  
Kim G. Beisel ◽  
...  
Keyword(s):  
Woody Species ◽  
Carotenoid Biosynthesis ◽  
Dry Mass ◽  
Daily Basis ◽  
High Irradiance ◽  
Strong Light ◽  
Neotropical Forest ◽  
Forest Plants ◽  
Shade Leaves ◽  
Sun Leaves

A survey of photosynthetic pigments, including 86 species from 64 families, was conducted for leaves of neotropical vascular plants to study sun-shade patterns in carotenoid biosynthesis and occurrence of α-carotene (α-Car) and lutein epoxide (Lx). Under low light, leaves invested less in structural components and more in light harvesting, as manifested by low leaf dry mass per area (LMA) and enhanced mass-based accumulation of chlorophyll (Chl) and carotenoids, especially lutein and neoxanthin. Under high irradiance, LMA was greater and β-carotene (β-Car) and violaxanthin-cycle pool increased on a leaf area or Chl basis. The majority of plants contained α-Car in leaves, but the α- to β-Car ratio was always low in the sun, suggesting preference for β-Car in strong light. Shade and sun leaves had similar β,ε-carotenoid contents per unit Chl, whereas sun leaves had more β,β-carotenoids than shade leaves. Accumulation of Lx in leaves was found to be widely distributed among taxa: >5 mmol mol Chl−1 in 20% of all species examined and >10 mmol mol Chl−1 in 10% of woody species. In Virola elongata (Benth.) Warb, having substantial Lx in both leaf types, the Lx cycle was operating on a daily basis although Lx restoration in the dark was delayed compared with violaxanthin restoration.

scholarly journals Are sun- and shade-type anatomy required for the acclimation of Neoregelia cruenta?

2013 ◽  
Vol 85 (2) ◽  
pp. 561-574 ◽  
Author(s):  
FERNANDA REINERT ◽  
MARCOS V. LEAL-COSTA ◽  
NICIA E. JUNQUEIRA ◽  
ELIANA S. TAVARES
Keyword(s):  
Growth Conditions ◽  
Sand Ridge ◽  
Light Levels ◽  
The Family ◽  
Sun And Shade ◽  
Shade Leaves ◽  
Sun Leaves ◽  
First Time ◽  
Tank Bromeliads ◽  
Shade Plants

Sun and shade plants are often discriminated by a number of sun- and shade-type anatomies. Nonetheless, we propose that among tank-bromeliads, changes in rosette architecture satisfy the requirements for coping with contrasting light levels. The tank-bromeliad Neoregelia cruenta naturally colonises sub-habitats ranging from full exposure to direct sunlight, to shaded environments in sand ridge plains. We quantified anatomical and morphological traits of leaves and rosettes of N. cruenta grown under sun and shade conditions. Cells with undulated lateral walls within the water parenchyma are for the first time described for the family. Under high light, leaf blades were wider, shorter, and yellowish. The rosette diameter of sun plants was less than half that of shade plants. Sun leaves overlapped with neighbouring leaves for most of their length, forming a cylindrical rosette where water accumulates. Shade leaves only overlapped in the centre of the rosette. Most anatomical traits were similar under both growth conditions. Stomata were absent from the base of sun leaves, which is probably explained by limited gas exchange at the base of the tight sun-type rosette. Data suggest that the ability of N. cruenta to acclimate to sun and shade is better explained by changes in rosette architecture than by leaf anatomy.

Microchannel Optimization for Heat Dissipation From a Solid Substrate

2008 ◽  
Author(s):  
C. B. Sobhan ◽  
P. S. Anoop ◽  
Kuriyan Arimboor ◽  
Thomas Abraham ◽  
G. P. Peterson
Keyword(s):  
Heat Transfer ◽  
Numerical Model ◽  
Thermal Resistance ◽  
Computational Model ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Heat Dissipation ◽  
Three Dimensional ◽  
Solid Substrate ◽  
Nusselt Numbers

A computational model was developed to analyze and optimize the convective heat transfer for water flowing through rectangular microchannels fabricated in a silicon substrate. A baseline case was analyzed by solving the nondimensional governing equations. Using a quasi three-dimensional computational model, the velocity and temperature distributions were obtained and the numerical results were then used to determine the overall dimensionless thermal resistance for the convective heat transfer from the substrate to the fluid. To validate the numerical model, the average Nusselt numbers as determined by the numerical model were compared with experimental results available in the literature, for channels with comparable hydraulic diameters. The procedure for arriving at an optimum geometric configuration and arrangement of microchannels on the substrate, subject to given design constraints, so that the thermal resistance is at a minimum, is described and demonstrated using the computational model.

The Oak Leaf: Connecting Geometry and Biology

1999 ◽  
Vol 92 (4) ◽  
pp. 294-298
Author(s):  
Judy Snyder
Keyword(s):  
Photosynthetic Activity ◽  
Outer Part ◽  
Oak Tree ◽  
And Mathematics ◽  
Shade Leaves ◽  
Sun Leaves

An activity that involves using geometry, statistics, and computers to interpret data about the leaves of a tree. Specifically, students determined the comparative area, weight, and photosynthetic activity of leaves for leaves growing on the outer part of an oak tree, that is, sun leaves, and those found on the inner part of the tree, or shade leaves. The students were involved in actual research, and mathematics was an integral part of their research.

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