Flooding tolerance of Carex species. II. Root gas-exchange capacity

Planta ◽  
1998 ◽  
Vol 207 (2) ◽  
pp. 199-206 ◽  
Author(s):  
Petra R. Moog ◽  
Wolfgang Brüggemann
Keyword(s):  
Gas Exchange ◽  
Exchange Capacity ◽  
Flooding Tolerance

scholarly journals Fossil evidence for low gas exchange capacities for Early Cretaceous angiosperm leaves

Paleobiology ◽  
2011 ◽  
Vol 37 (2) ◽  
pp. 195-213 ◽  
Author(s):  
Taylor S. Feild ◽  
Garland R. Upchurch ◽  
David S. Chatelet ◽  
Timothy J. Brodribb ◽  
Kunsiri C. Grubbs ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Early Cretaceous ◽  
Leaf Gas Exchange ◽  
Exchange Capacity ◽  
Basal Angiosperm ◽  
Photosynthetic Gas Exchange ◽  
Angiosperm Evolution ◽  
Early Angiosperm ◽  
Fossil Evidence ◽  
Functional Analyses

The photosynthetic gas exchange capacities of early angiosperms remain enigmatic. Nevertheless, many hypotheses about the causes of early angiosperm success and how angiosperms influenced Mesozoic ecosystem function hinge on understanding the maximum capacity for early angiosperm metabolism. We applied structure-functional analyses of leaf veins and stomatal pore geometry to determine the hydraulic and diffusive gas exchange capacities of Early Cretaceous fossil leaves. All of the late Aptian—early Albian angiosperms measured possessed low vein density and low maximal stomatal pore area, indicating low leaf gas exchange capacities in comparison to modern ecologically dominant angiosperms. Gas exchange capacities for Early Cretaceous angiosperms were equivalent or lower than ferns and gymnosperms. Fossil leaf taxa from Aptian to Paleocene sediments previously identified as putative stem-lineages to Austrobaileyales and Chloranthales had the same gas exchange capacities and possibly leaf water relations of their living relatives. Our results provide fossil evidence for the hypothesis that high leaf gas exchange capacity is a derived feature of later angiosperm evolution. In addition, the leaf gas exchange functions of austrobaileyoid and chloranthoid fossils support the hypothesis that comparative research on the biology of living basal angiosperm lineages reveals genuine signals of Early Cretaceous angiosperm ecophysiology.

Mesh-Based Pneumostasis Contributes to Preserving Gas Exchange Capacity and Promoting Rehabilitation After Lung Resection

2011 ◽  
Vol 167 (2) ◽  
pp. e71-e75 ◽  
Author(s):  
Kazuhiro Ueda ◽  
Toshiki Tanaka ◽  
Masataro Hayashi ◽  
Tao-Sheng Li ◽  
Nobuyuki Tanaka ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Lung Resection ◽  
Exchange Capacity

DETERMINATION OF GAS EXCHANGE CAPACITY OF SOME BREBA FIG CULTIVARS

2008 ◽  
pp. 117-122 ◽  
Author(s):  
H.Z. Can ◽  
K.B. Meyvacı ◽  
B. Balci
Keyword(s):  
Gas Exchange ◽  
Exchange Capacity

scholarly journals Genome downsizing, physiological novelty, and the global dominance of flowering plants

2017 ◽  
Author(s):  
Kevin A. Simonin ◽  
Adam B. Roddy
Keyword(s):  
Gas Exchange ◽  
Exchange Rates ◽  
Cell Size ◽  
Exchange Capacity ◽  
Stomatal Size ◽  
Leaf Physiology ◽  
C4 Species ◽  
Angiosperm Diversification ◽  
Time Period ◽  
Cam Photosynthesis

SummaryDuring the Cretaceous (145-66 Ma), early angiosperms rapidly diversified, eventually outcompeting the ferns and gymnosperms previously dominating most ecosystems. Heightened competitive abilities of angiosperms are often attributed to higher rates of transpiration facilitating faster growth. This hypothesis does not explain how angiosperms were able to develop leaves with smaller, but densely packed stomata and highly branched venation networks needed to support increased gas exchange rates. Although genome duplication and reorganization have likely facilitated angiosperm diversification, here we show that genome downsizing facilitated reductions in cell size necessary to construct leaves with a high density stomata and veins. Rapid genome downsizing during the early Cretaceous allowed angiosperms to push the frontiers of anatomical trait space. In contrast, during the same time period ferns and gymnosperms exhibited no such changes in genome size, stomatal size, or vein density. Further reinforcing the effect of genome downsizing on increased gas exchange rates, we found that species employing water-loss limiting crassulacean acid metabolism (CAM) photosynthesis, have significantly larger genomes than C3 and C4 species. By directly affecting cell size and gas exchange capacity, genome downsizing brought actual primary productivity closer to its maximum potential. These results suggest species with small genomes, exhibiting a larger range of final cell size, can more finely tune their leaf physiology to environmental conditions and inhabit a broader range of habitats.

scholarly journals Аnalysis Catalytic Hydrogen Recombiner Capacity Calculation Taking into Account Conditions Inside Sealed Enclosure of Containment Safety System of Nuclear Power Plants with Water-Water Energetic Reactor

2021 ◽  
Vol 64 (2) ◽  
pp. 178-186
Author(s):  
V. V. Sorokin
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Gas Exchange ◽  
Nuclear Power ◽  
Power Plants ◽  
Reference Conditions ◽  
Exchange Capacity ◽  
Primary Coolant ◽  
Radioactive Substances ◽  
Catalytic Hydrogen

Localizing safety systems are provided to contain radioactive substances in an accident and attenuate ionizing radiation at a modern nuclear power plant. Together with radioactive substances, hydrogen is also retained, which is formed during the decomposition of the primary coolant. The accumulation of hydrogen in the presence of oxygen from the atmosphere in the accident localization zone carries the danger of the formation of flammable and explosive concentrations of these components. Nuclear power plant (NPP) deigns with water-water energetic reactor (WWER) provides for a hydrogen removal system including passive catalytic hydrogen recombiners. The device capacity  is confirmed experimentally under reference conditions (lean air-hydrogen mixture, pressure and temperature close to normal, no interference with gas exchange). Capacity is an important safety parameter. In the event of an accident, conditions inside the ealed enclosure of the localizing system of NPP with WWER can  differ from the reference  ones and affect the capacity.  On the basis of calculations, the operation of recombiners with lack of  oxygen  and with hindered  gas exchange has been investigated in the paper. The decrease in capacity with lack of oxygen reaches 50 %, which is mainly  caused by an increase in underburning. Compared to the reference conditions, the effect is more pronounced in the event of an accident – 60–70 %. The hindered gas exchange is modeled by a decrease in the height of recombiner traction channel. This case can be reduced to the placement of the device in cramped conditions and the effect of the atmosphere speed inside the enclosure. Regardless of the hydrogen concentration, the operating characteristic of the device remains linear, with a two-fold decrease in height leads to a decrease in capacity by 20 %. The results can be used to substantiate the safety of NPPs with WWER and to review on the safety subtantiation of power units.

Effect of Subzero-Balanced Ultrafiltration on Lung Gas Exchange Capacity after Cardiopulmonary Bypass in Adult Patients with Heart Valve Disease

2011 ◽  
Vol 14 (1) ◽  
pp. 22 ◽  
Author(s):  
Tao Zhang ◽  
Sheng-li Jiang ◽  
Chang-qing Gao ◽  
Jin Luo ◽  
Lan Ma ◽  
...  
Keyword(s):  
Cardiac Surgery ◽  
Cardiopulmonary Bypass ◽  
Gas Exchange ◽  
Heart Valve ◽  
Exchange Capacity ◽  
Adult Patients ◽  
Heart Valve Disease ◽  
Arterial Oxygen ◽  
Control Group ◽  
Study Group

Objectives: This study was conducted to evaluate the effect of a new ultrafiltration techniquethe subzerobalanced ultrafiltration (SBUF)on lung gas exchange capacity after cardiopulmonary bypass (CPB) in adult patients with heart valve disease.Background: Attenuation of lung gas exchange capacity is one of the most common manifestations of an inflammatory response after CPB.Methods: Ninety-four patients who required CPB for cardiac surgery were randomized into 2 groups according to whether they received SBUF. Gas exchange capacity expressed as the oxygen index (OI), the respiratory index (RI), and the alveolar-arterial oxygen pressure difference (P(A-a)O2) were measured after intubation (T1), at the termination of CPB (T2), on admission to the intensive care unit (ICU) (T3), at postoperative hour 6 (T4), and at postoperative hour 12 (T5).Results: There were no significant differences in gas exchange capacity between the 2 groups at T1, T4, and T5. CPB produced significant changes in OI, RI, and P(A-a)O2 in the control group, whereas these changes were not significantly different in the study group. The OI in the study group was significantly higher at T2, and RI and P(A-a)O2 were significantly lower at T2 and T3. In the study group, the intubation time was shorter, and the transfusion volume within 24 hours postoperatively was less. The 2 groups were comparable with respect to the incidence of respiratory complications, length of stay in the ICU, duration of hospital stay, need for infusions of inotropic agents, and drainage volumes within 24 hours postoperatively.Conclusions: SBUF during CPB can produce an immediate improvement in lung gas exchange capacity, which may effectively minimize pulmonary dysfunction in adult patients undergoing cardiac surgery.

Conducting airway gas exchange: diffusion-related differences in inert gas elimination

1992 ◽  
Vol 72 (4) ◽  
pp. 1581-1588 ◽  
Author(s):  
E. R. Swenson ◽  
H. T. Robertson ◽  
N. L. Polissar ◽  
M. E. Middaugh ◽  
M. P. Hlastala
Keyword(s):  
Gas Exchange ◽  
Exchange Capacity ◽  
Inert Gases ◽  
Inert Gas ◽  
Diffusion Resistance ◽  
Molecular Weights ◽  
Conducting Airway ◽  
Group 2 ◽  
Airway Gas Exchange ◽  
Group 1

We studied CO2 and inert gas elimination in the isolated in situ trachea as a model of conducting airway gas exchange. Six inert gases with various solubilities and molecular weights (MW) were infused into the left atria of six pentobarbital-anesthetized dogs (group 1). The unidirectionally ventilated trachea behaved as a high ventilation-perfusion unit (ratio = 60) with no appreciable dead space. Excretion of higher-MW gases appeared to be depressed, suggesting a MW dependence to inert gas exchange. This was further explored in another six dogs (group 2) with three gases of nearly equal solubility but widely divergent MWs (acetylene, 26; Freon-22, 86.5; isoflurane, 184.5). Isoflurane and Freon-22 excretions were depressed 47 and 30%, respectively, relative to acetylene. In a theoretical model of airway gas exchange, neither a tissue nor a gas phase diffusion resistance predicted our results better than the standard equation for steady-state alveolar inert gas elimination. However, addition of a simple ln (MW) term reduced the remaining residual sum of squares by 40% in group 1 and by 83% in group 2. Despite this significant MW influence on tracheal gas exchange, we calculate that the quantitative gas exchange capacity of the conducting airways in total can account for less than or equal to 16% of any MW-dependent differences observed in pulmonary inert gas elimination.

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