Efficiency and evolution of water transport systems in higher plants: a modelling approach. I. The earliest land plants

1994 ◽  
Vol 345 (1312) ◽  
pp. 137-152 ◽  
Keyword(s):  
Hydraulic Conductivity ◽  
Water Transport ◽  
Higher Plants ◽  
Fluid Pressure ◽  
Numerical Approach ◽  
Transport Systems ◽  
Central Position ◽  
Dynamic Permeability ◽  
Apoplastic Pathway ◽  
Transport Problems

The evolution of the stele was studied under the functional aspect of water transport problems by using a numerical approach. The underlying mathematical model describes the behaviour of a fluid-filled porous medium and is based on the coupling of Hooke’s law and Darcy’s law including a dynamic permeability approach which leads to a self-organization of the considered structure according to the resulting fluid- pressure field. Calculations dealing with two problems were performed. The essential demand of a water conducting system for a plant was demonstrated quantitatively. As soon as the plant shows an upright habit, the need for efficient water transport occurring through a highly porous apoplastic pathway becomes evident. In a second approach, the evolution of the protostele was simulated using the concept of dynamic permeability. The simulations of structures with self-regulating hydraulic conductivity yielded two strategies according to the pressure-permeability relationship. Increasing hydraulic conductivity with increasing negative fluid pressure results in peripheral layers of the conducting tissues, whereas the inverse pressure-permeability relationship yields a central position of the conducting tissues. The latter arrangement corresponds to the protostelar construction of early vascular plants.

Efficiency and evolution of water transport systems in higher plants: a modelling approach. II. Stelar evolution

1994 ◽  
Vol 345 (1312) ◽  
pp. 153-162 ◽  
Keyword(s):  
Water Transport ◽  
Higher Plants ◽  
Land Plants ◽  
Transport Systems ◽  
Transport Efficiency ◽  
Hydrodynamic Behaviour ◽  
Water Conduction ◽  
Central Strand ◽  
Early Land ◽  
Modelling Approach

Different stelar arrangements have developed through evolution of land plants. The first stele to appear was a central strand (protostele) consisting of tracheids or hydroid-like cells. In more derived steles (e.g. actinostele, siphonostele), a location of the conducting elements at relatively more peripheral regions of the axis can be observed. It has been shown that the trend in stelar evolution in early land plants from protostele to actinostele or siphonostele has little to do with an increase of the flexural stiffness in the axis. Hence, it is to be expected, that the (early) stelar evolution reflects an optimization process of the water conducting capabilities of the stem. To test this hypothesis, the effectiveness of protostele and siphonostele in water conduction was analysed numerically. The results demonstrate that the hydrodynamic behaviour of a plant axis depends not only on the relative amount of its conducting tissues, but also on the arrangement of the xylem within an axis. A protostele and a siphonostele with identical distance between outer xylem boundary and site of transpiration may, therefore, be identical with regard to water transport efficiency.

Pearl millet (Pennisetum glaucum) contrasting for the transpiration response to vapour pressure deficit also differ in their dependence on the symplastic and apoplastic water transport pathways

2018 ◽  
Vol 45 (7) ◽  
pp. 719 ◽  
Author(s):  
Murugesan Tharanya ◽  
Kaliamoorthy Sivasakthi ◽  
Gloria Barzana ◽  
Jana Kholová ◽  
Thiyagarajan Thirunalasundari ◽  
...  
Keyword(s):  
Hydraulic Conductivity ◽  
Water Transport ◽  
Pearl Millet ◽  
Transpiration Rate ◽  
Vapour Pressure Deficit ◽  
Transport Pathways ◽  
Root Hydraulic Conductivity ◽  
Detached Leaves ◽  
Apoplastic Pathway ◽  
Symplastic Pathway

Genotypic differences in transpiration rate responses to high vapour pressure deficit (VPD) was earlier reported. Here we tested the hypothesis that this limitation could relate to different degrees of dependence on the apoplastic (spaces between cells), and symplastic water transport pathways (through cells via aquaporin-facilitated transport), which are known to have different hydraulic conductivities. The low transpiration rate (Tr) genotype PRLT 2/89/33 either restricted its transpiration under high VPD, or was more sensitive to VPD than H77/833-2, when grown hydroponically or in soil. The slope of the transpiration response to an ascending series of VPD was lower in whole plants than in de-rooted shoots. In addition, the transpiration response of detached leaves to moderately high VPD (2.67 kPa), normalised against leaves exposed to constant VPD (1.27 kPa), was similar in low and high Tr genotypes. This suggested that roots hydraulics were a substantial limitation to water flow in pearl millet, especially under high VPD. The dependence on the apoplastic and symplastic water transport pathways was investigated by assessing the transpiration response of plants treated with inhibitors specific to the AQP-mediated symplastic pathway (AgNO3 and H2O2) and to the apoplastic pathway (precipitates of Cu(Fe(CN)6) or Cu(CuFe(CN)6)). When CuSO4 alone was used, Cu ions caused an inhibition of transpiration in both genotypes and more so in H77/833-2. The transpiration of high Tr H77/833-2 was decreased more by AQP inhibitors under low VPD (1.8 kPa) than in PRLT 2/89/33, whereas under high VPD (4.2 kPa), the transpiration of PRLT 2/89/33 was decreased more by AQP inhibitors than in H77/833-2. The transpiration rate of detached leaves from H77/833-2 when treated with AgNO3 decreased more than in PRLT 2/89/33. Although the root hydraulic conductivity of both genotypes was similar, it decreased more upon the application of a symplastic inhibitor in H77/833-2. The transpiration of low Tr PRLT 2/89/33 was decreased more by apoplastic inhibitors under both low and high VPD. Then the hydraulic conductivity decreased more upon the application of an apoplastic inhibitor in PRLT 2/89/33. In conclusion, both pathways contributed to water transport, and their contribution varied with environmental conditions and genotypes. Roots were a main source of hydraulic limitation in these genotypes of pearl millet, although a leaf limitation was not excluded. The similarity between genotypes in root hydraulic conductivity under normal conditions also suggests changes in this conductivity upon changes in the evaporative demand. The low Tr genotype depended more on the apoplastic pathway for water transport, whereas the high Tr genotype depended on both pathway, may be by ‘tuning-up’ the symplastic pathway under high transpiration demand, very likely via the involvement of aquaporins.

scholarly journals Sustainable Transport in the Danube Region

2021 ◽  
Vol 13 (12) ◽  
pp. 6797
Author(s):  
Peter Mako ◽  
Andrej Dávid ◽  
Patrik Böhm ◽  
Sorin Savu
Keyword(s):  
Water Transport ◽  
Fossil Fuels ◽  
Environmentally Friendly ◽  
Road Transport ◽  
Transport Systems ◽  
Main Question ◽  
Inland Water ◽  
Danube Region ◽  
Inland Water Transport

Sustainability of transport systems is a key issue in transport. The main question is whether high levels of road and railway transport in areas along navigable waterways is an effective solution for this issue. The Danube waterway is an example. Generally, it is not observed that traffic performance is not as high as on the Rhine. This paper deals with the revelation of the available capacity of this waterway based on approximation functions and their comparison with real transport performances. This methodology points to the level of use of waterways. The connection of this model with the production of fossil fuels creates a basis for a case study. The case study in this paper offers a possibility for a sustainable and environmentally friendly transition from road transport to inland water transport on the example of specific transport routes. The main contribution of this paper is a presentation of the application of sustainable models of use transport capacity to increase the share of environmentally friendly and sustainable inland water transport. The conclusion based on the case study and materials is that the available capacity of inland water transport on the Danube could support the transition of traffic performances to sustainable and environmentally friendly means of transport.

Bicarbonate Transport Systems in the Intestine of the Seawater EEL

1990 ◽  
Vol 150 (1) ◽  
pp. 381-394 ◽  
Author(s):  
MASAAKI ANDO ◽  
M. V. SUBRAMANYAM
Keyword(s):  
Latent Period ◽  
Water Transport ◽  
Basolateral Membrane ◽  
Transport Systems ◽  
Bicarbonate Transport ◽  
Ph Stat ◽  
Stat Method

Utilizing a pH-stat method, the rates of mucosal and serosal alkalinization were measured separately in the seawater eel intestine. These two rates were dependent on contralateral HCO3− concentration and were inhibited by contralateral application of DIDS, an inhibitor of HCO3− transport, indicating that the mucosal and serosal alkalinization are due to HCO3− secretion and absorption, respectively. The mucosal alkalinization was enhanced after inhibiting Na+/K+/Cl− cotransport by treatment with bumetanide, furosemide or Ba2+, with a latent period of more than lOmin, suggesting that HCO3− absorption from mucosa to serosa depends on Na+/K+/Cl− cotransport. The serosal alkalinization caused by HCO3− absorption was completely abolished after mucosal application of bumetanide. After pretreatment with bumetanide, mucosal omission of Cl− halved the enhanced rate of mucosal alkalinization, and Na+ omission had no effect on it; this indicates that the exit of HCO3− into the lumen depends on luminal Cl−, i.e. on the existence of the usual C1−/HCO3− exchange on the brushborder membrane. When serosal Na+ was removed under the same conditions, mucosal alkalinization was reduced, indicating that HCO3− entry from the serosal fluid depends on Na+. Serosal omission of Cl− did not reduce mucosal alkalinization. In addition, serosal alkalinization was enhanced by serosal removal of Na+ but not of Cl−. These results suggest that there is a Na+/HCO3− cotransport on the basolateral membrane. A possible model for HCO3− transport systems in the seawater eel intestine is proposed, and a possible role for these transport systems is discussed in relation to Na+, Cl− and water transport.

scholarly journals Quick energy assessment of irrigation water transport systems

2019 ◽  
Vol 188 ◽  
pp. 96-105
Author(s):  
Enrique Cabrera ◽  
Roberto del Teso ◽  
Elena Gómez ◽  
Elvira Estruch-Juan ◽  
Javier Soriano
Keyword(s):  
Water Transport ◽  
Irrigation Water ◽  
Transport Systems ◽  
Energy Assessment

scholarly journals A Novel Numerical Model for Fluid Flow in 3D Fractured Porous Media Based on an Equivalent Matrix-Fracture Network

Geofluids ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-13 ◽  
Author(s):  
Chi Yao ◽  
Chen He ◽  
Jianhua Yang ◽  
Qinghui Jiang ◽  
Jinsong Huang ◽  
...  
Keyword(s):  
Porous Media ◽  
Fluid Flow ◽  
Hydraulic Conductivity ◽  
Fractured Rock ◽  
Fracture Network ◽  
Numerical Approach ◽  
Porous Matrix ◽  
Fractured Porous Media ◽  
Hydraulic Aperture ◽  
Matrix Fracture

An original 3D numerical approach for fluid flow in fractured porous media is proposed. The whole research domain is discretized by the Delaunay tetrahedron based on the concept of node saturation. Tetrahedral blocks are impermeable, and fluid only flows through the interconnected interfaces between blocks. Fractures and the porous matrix are replaced by the triangular interface network, which is the so-called equivalent matrix-fracture network (EMFN). In this way, the three-dimensional seepage problem becomes a two-dimensional problem. The finite element method is used to solve the steady-state flow problem. The big finding is that the ratio of the macroconductivity of the whole interface network to the local conductivity of an interface is linearly related to the cubic root of the number of nodes used for mesh generation. A formula is presented to describe this relationship. With this formula, we can make sure that the EMFN produces the same macroscopic hydraulic conductivity as the intact rock. The approach is applied in a series of numerical tests to demonstrate its efficiency. Effects of the hydraulic aperture of fracture and connectivity of the fracture network on the effective hydraulic conductivity of fractured rock masses are systematically investigated.

Description and Validation of a Finite Element Model of Backflow During Infusion Into a Brain Tissue Phantom

2012 ◽  
Vol 8 (1) ◽  
Author(s):  
José J. García ◽  
Ana Belly Molano ◽  
Joshua H. Smith
Keyword(s):  
Finite Element ◽  
Hydraulic Conductivity ◽  
Finite Element Model ◽  
Brain Tissue ◽  
Nonlinear Boundary ◽  
Fluid Pressure ◽  
Element Model ◽  
Analytical Models ◽  
External Boundary ◽  
Forward Flow

An axisymmetric biphasic finite element model is proposed to simulate the backflow that develops around the external boundary of the catheter during flow-controlled infusions. The model includes both material and geometric nonlinearities and special treatments for the nonlinear boundary conditions used to represent the forward flow from the catheter tip and the axial backflow that occurs in the annular gap that develops as the porous medium detaches from the catheter. Specifically, a layer of elements with high hydraulic conductivity and low Young’s modulus was used to represent the nonlinear boundary condition for the forward flow, and another layer of elements with axial hydraulic conductivity consistent with Poiseuille flow was used to represent the backflow. Validation of the model was performed by modifying the elastic properties of the latter layer to fit published experimental values for the backflow length and maximum fluid pressure obtained during infusions into agarose gels undertaken with a 0.98-mm-radius catheter. Next, the finite element model predictions showed good agreement with independent experimental data obtained for 0.5-mm-radius and 0.33-mm-radius catheters. Compared to analytical models developed by others, this finite element model predicts a smaller backflow length, a larger fluid pressure, and a substantially larger percentage of forward flow. This latter difference can be explained by the important axial flow in the tissue that is not considered in the analytical models. These results may provide valuable guidelines to optimize protocols during future clinical studies. The model can be extended to describe infusions in brain tissue and in patient-specific geometries.

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