The water relations of hemlock (Tsuga canadensis). II. The kinetics of water exchange between the symplast and apoplast

1973 ◽  
Vol 51 (8) ◽  
pp. 1481-1489 ◽  
Author(s):  
M. T. Tyree ◽  
J. Dainty
Keyword(s):  
Water Exchange ◽  
Turgor Pressure ◽  
Experimental Studies ◽  
Tsuga Canadensis ◽  
Rate Of Change ◽  
Cell Constant ◽  
Exponential Process ◽  
Pressure Increment ◽  
Pressure Bomb ◽  
Kinetics Of

We present a theoretical analysis of the events that occur while a plant enclosed in a pressure bomb evolves from one equilibrium balancing pressure to another. The initial rate of efflux from any one cell in response to a pressure increment of ΔP equals (ALp)i ΔP, where (ALp)i is the surface area times hydraulic conductivity of the cell's semipermeable membrane(s). If the volume changes and pressure increment are small, the cell will approach equilibrium exponentially. The half time of the exponential process is governed by (ALp)iki, where ki is the cell constant (= the combined rate of change of osmotic and turgor pressure with the volume expressed from the cell). Experimental studies of the kinetics of water exchange between the symplast and apoplast of hemock (Tsuga canadensis) shoots in a pressure bomb reveal that the cells collectively behave as though they fall into three distinct populations which approach equilibrium with different half times.

The water relations of hemlock (Tsuga canadensis). V. The localization of resistances to bulk water flow

1975 ◽  
Vol 53 (10) ◽  
pp. 1078-1084 ◽  
Author(s):  
M. T. Tyree ◽  
C. Caldwell ◽  
J. Dainty
Keyword(s):  
Activation Energy ◽  
Water Flow ◽  
Water Exchange ◽  
Careful Analysis ◽  
Bulk Water ◽  
Exponential Process ◽  
Measurable Amount ◽  
Pressure Bomb ◽  
Overall Resistance ◽  
Kinetics Of

The pressure-bomb technique has been used to measure the kinetics of water exchange while a plant enclosed in a pressure bomb evolves from one equilibrium balance pressure to another. In earlier studies two observations were made. (1) The kinetics of water exchange appeared to be described by an exponential process in which three populations of cells exchange water with apoplast independently of each other. (2) The temperature dependence of the tempo of water exchange yielded an activation energy of 25.9 ± 0.6 × 103 J/mol, which is higher than the activation energy for laminar flow of water in pipes (= 17 × 103 J/mol). These results have been repeated and a more careful analysis has been conducted involving infiltration of air spaces in leaves with water and the selective removal of the leaves. It now appears that the xylem network up to (but not including) the leaves contributes about two thirds of the resistance to water flow in whole shoots 15 to 40 g in fresh weight. Presumably leaves near the cut basal end of the shoot experience a smaller xylem resistance than leaves near the apex. The kinetics of water exchange from water in the air spaces of infiltrated shoots indicates that there is a barrier at the air–water interface of leaves that equals the normal shoot resistance to bulk water flow. The activation energy for water flow through the xylem alone was measured to be about 17 × 103 J/mol. Although the leaves contribute a measurable amount to the overall resistance to water flow, the mathematical description of the system is much more complicated than previously supposed.

The water relations of hemlock (Tsuga canadensis). IV. The dependence of the balance pressure on temperature as measured by the pressure-bomb technique

1974 ◽  
Vol 52 (5) ◽  
pp. 973-978 ◽  
Author(s):  
M. T. Tyree ◽  
J. Dainty ◽  
D. M. Hunter
Keyword(s):  
Temperature Dependence ◽  
Water Potential ◽  
Osmotic Pressure ◽  
Water Relations ◽  
Turgor Pressure ◽  
Tsuga Canadensis ◽  
Constant Volume ◽  
Pressure Bomb

The temperature dependence of the balance pressure is reported for shoots of Tsuga canadensis at constant volume, i.e., when water is neither added to nor removed from the shoot. Since the balance pressure closely equals minus the water potential, the temperature dependence of the balance pressure should reflect the combined temperature dependence of the osmotic and turgor pressures. Both the osmotic and the turgor pressures decline with decreasing temperature; frequently the turgor pressure declines 2 to 3 times more rapidly than the osmotic pressure, causing the balance pressure to rise with decreasing temperature. Only when the turgor pressure is zero (only beyond incipient plasmolysis) does the temperature dependence of the balance pressure closely follow the temperature dependence of the osmotic pressure; this occurs when the balance pressure equals or exceeds 24 bars.

The water relations of hemlock (Tsuga canadensis). III. The temperature dependence of water exchange in a pressure bomb

1973 ◽  
Vol 51 (8) ◽  
pp. 1537-1543 ◽  
Author(s):  
M. T. Tyree ◽  
M. Benis ◽  
J. Dainty
Keyword(s):  
Activation Energy ◽  
Temperature Dependence ◽  
Water Exchange ◽  
Membrane Resistance ◽  
Tsuga Canadensis ◽  
Rate Equations ◽  
Rate Theory ◽  
Water Permeation ◽  
Pressure Bomb ◽  
Extracellular Resistance

The pressure-bomb technique has been used to measure the temperature dependence of water exchange between the apoplast and symplast of hemlock (Tsuga canadensis) shoots. By applying the Arrhenius rate theory, the activation energy for water exchange in the whole shoot equals 25.9 + 0.6 × 103 J per mole. A theory is proposed on the basis of the Arrhenius rate equations which allows us to predict the relative magnitudes of the membrane resistance, Rm, and the extracellular resistance, Rx, to water permeation. On the basis of our calculations, we believe Rm is at least one-quarter of Rx and may even exceed Rx, but more work needs to be done to be sure.

Derivatives of isatin in aqueous solution. I. Kinetics of ring opening of Isatin-5-sulfonate

1981 ◽  
Vol 34 (2) ◽  
pp. 365 ◽  
Author(s):  
H Stunzi
Keyword(s):  
Ring Opening ◽  
Rate Of Change ◽  
Spectroscopic Methods ◽  
Ph Values ◽  
Buffer Region ◽  
Pka Value ◽  
Back Titration ◽  
Kinetics Of ◽  
Derivatives Of ◽  
Sulfonate Anion

The reactions of isatin-5-sulfonate anion (si-) which cause a hysteresis in pH titrations were studied by pH-metric and n.m.r, spectroscopic methods. Rapid alkalimetric titrations [I 0.15 M (KNO3),37�] gave the pKa value corresponding to the addition of OH- to si- [pKa(ring) 9.55]. The slow ring opening to the sulfonatoisatate dianion (sia2-) led to a drift of the pH values towards an equilibrium buffer region. Its pKa, value [pKa(eq) 3.44] corresponds to the reaction si-+H2O ↔ sia 2-+H+ Rapid back-titration gave the pKa value of the ring-opened species Hsia- [pKa(open) c. 1.3]. The rate law for the ring opening d[sia]/dt=k2 [siOH](OH)+k1*[si] was obtained from the rate of change of pH. N-Methylisatin-5-sulfonate behaves analogously.

Simulating of Phytoplankton Development in the Rybinsk Reservoir

2015 ◽  
pp. 32-40
Author(s):  
Keyword(s):  
Water Exchange ◽  
Rybinsk Reservoir ◽  
Vegetation Period ◽  
Diatom Algae ◽  
Algae Biomass ◽  
Internal Water ◽  
Kinetics Of ◽  
The Rybinsk Reservoir

A model of phytoplankton development within a reservoir including the description of kinetics of its interactions in the ecosystem and internal water exchange of the reservoir has been presented. The carried out calculations of changes of the cyanobacteria and diatom algae biomass in the Rybinsk Reservoir in the vegetation period have shown their satisfactory convergence with the fi eld observations data.

Kinetics of hypso anhydrites dissolution in water. Experimental studies

2019 ◽  
pp. 93-96
Author(s):  
A. L. Lebedev ◽  
I. V. Avilina
Keyword(s):  
Experimental Data ◽  
Experimental Study ◽  
Riccati Equation ◽  
Balance Equation ◽  
Experimental Studies ◽  
Common Ion ◽  
The Common ◽  
Common Ion Effect ◽  
Kinetics Of Dissolution ◽  
Kinetics Of

Experimental study of kinetics of dissolution of hypso anhydrites at 25 ᵒC made it possible to formulate model of the process in the form of a balance equation for the kinetics of dissolution of gypsum, anhydrite (first and second orders, respectively) and kinetics of precipitation of gypsum (second order). The processing of the experimental data were carried out on the basis of the solution of the Riccati equation. When taking into account the common-ion effect on the solubility of gypsum and anhydrite, the calculated values turned out to be more comparable with the experimental ones.

Kinetics study of spreading processes of epoxy binders on carbon cloth surface with metal coating

2021 ◽  
Vol 0 (3) ◽  
pp. 34-38
Author(s):  
D.E. Grechushkina ◽  
◽  
V.A. Nelyub ◽  
Keyword(s):  
Considerable Increase ◽  
Experimental Studies ◽  
Copper Coating ◽  
Metal Coating ◽  
Carbon Cloth ◽  
Kinetics Study ◽  
Carbon Tape ◽  
Epoxy Binders ◽  
Kinetics Of ◽  
Spreading Processes

The results of experimental studies of kinetics of spreading processes of epoxy binders on the surface of a carbon (cloth) tape depending on a reinforcement pattern are presented. A copper coating of 100 nm thickness was deposited on reinforced materials by magnetron sputtering. It has been found out that a metal coating on the surface of a carbon tape and cloth leads to a considerable increase in the rate of spreading processes only for the laying-out pattern 0°, when binder movement in capillaries is provided. The deposition of a copper coating on the surface of the carbon tape and cloth has considerably the bigger influence on kinetics of the spreading processes, increasing it by 35%.

Cooling of Fruit with Arbitrary Shape: Simulation Using Galerkin-Based Integral Method

2017 ◽  
Vol 10 ◽  
pp. 1-15
Author(s):  
P. Morais Pessôa ◽  
A.G. Barbosa de Lima ◽  
R. Swarnakar ◽  
J.P. Gomes ◽  
W.M.P. Barbosa de Lima
Keyword(s):  
Integral Method ◽  
Arbitrary Shape ◽  
Heat Conduction Equation ◽  
Low Cost ◽  
Experimental Studies ◽  
Volume Ratio ◽  
Transient Heat Conduction ◽  
Cooling Time ◽  
Time Required ◽  
Kinetics Of

Cooling has been used for the preservation of fresh produce such as fruit and vegetables due to its low cost and high effectiveness in maintaining the product quality. Recently, several researchers have conducted theoretical and experimental studies for obtaining the kinetics of cooling and cooling time for fruits with different geometries. Present work, therefore, aims to simulate the cooling of fruits with particular reference to banana, orange, strawberry and Tahiti lemon. The transient heat conduction equation and its analytical solution using Galerkin based integral method are presented. It has been found that the strawberry has lower dimensionless cooling time compared with time required to cool other fruits, which is due to its higher surface area/volume ratio value. In orange and lemon the temperature distribution was found to be homogeneous in the angular direction, while in banana and strawberry it was two-dimensional due to shape of the fruits.

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