The Experts below are selected from a list of 183 Experts worldwide ranked by ideXlab platform
James A Bunce - One of the best experts on this subject based on the ideXlab platform.
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does transpiration control stomatal responses to water Vapour Pressure deficit
Plant Cell and Environment, 1997Co-Authors: James A BunceAbstract:Three types of observations were used to test the hypothesis that the response of stomatal conductance to a change in Vapour Pressure deficit is controlled by whole-leaf transpiration rate or by feedback from leaf water potential. Varying the leaf water potential of a measured leaf by controlling the transpiration rate of other leaves on the plant did not affect the response of stomatal conductance to Vapour Pressure deficit in Glycine max. In three species, stomatal sensitivity to Vapour Pressure deficit was eliminated when measurements were made at near-zero carbon dioxide concentrations, despite the much higher transpiration rates of leaves at low carbon dioxide. In Abutilon theophrasti, increasing Vapour Pressure deficit sometimes resulted in both decreased stomatal conductance and a lower transpiration rate even though the response of assimilation rate to the calculated substomatal carbon dioxide concentration indicated that there was no ‘patchy’ stomatal closure at high Vapour Pressure deficit in this case. These results are not consistent with stomatal closure at high Vapour Pressure deficit caused by increased wholeleaf transpiration rate or by lower leaf water potential. The lack of response of conductance to Vapour Pressure deficit in carbon dioxide-free air suggests that abscisic acid may mediate the response.
A Jorge J Velasquez - One of the best experts on this subject based on the ideXlab platform.
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wagner liquid Vapour Pressure equation constants from a simple methodology
The Journal of Chemical Thermodynamics, 2011Co-Authors: A Luis G Forero, A Jorge J VelasquezAbstract:A methodology to determine the A, B, C, and D constants from the Wagner equation is presented. The constants for 274 pure substances were determined by minimization in the sum of the squares of the relative deviation in liquid Vapour Pressure. For 69 chemical compounds, Vapour Pressures exist over the range from 1 kPa to the critical Pressure and an average absolute deviation in Vapour Pressure of 0.039% was calculated. Using Antoine equation coefficients and initial guesses for a correlation in terms of the acentric factor, Wagner constants were estimated for substances with limited data within the range from (1 to 200) kPa. To validate the proposed methodology, Vapour Pressure predictions from 1 kPa to the critical Pressure were made for 52 substances using Wagner parameters estimated from limited data. A value of 0.27% in average absolute deviation results for those substances. Finally the Waring criterion was applied to check the constants presented in this paper.
L. L. Dijkgraaf - One of the best experts on this subject based on the ideXlab platform.
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The calculation of maxima in Vapour-Pressure curves
Recueil des Travaux Chimiques des Pays-Bas, 2010Co-Authors: A. E. Korvezee, P. Dingemans, L. L. DijkgraafAbstract:A simple approximate relation is derived for the temperature of the maximum occurring in the Vapour-Pressure lines of saturated solutions of a number of non-volatile substances of high melting point in a volatile solvent. The derivation is analogous to that for saturated solutions of one dissolved substance. This formula, although derived only for ideal mixtures, is found to give reasonably satisfactory results for a series of Vapour-Pressure curves determined in this laboratory in non-ideal systems.
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the Vapour Pressure of saturated solutions of sodium nitrate in water
Recueil des Travaux Chimiques des Pays-Bas, 2010Co-Authors: P. Dingemans, L. L. DijkgraafAbstract:The Vapour Pressure of saturated solutions of NaNO3 in water was measured from 10° C to 150° C. From these measurements it is found that the relative Vapour Pressure p/pw plotted as a function of the temperature gives a slightly curved line, as previously obtained for some other saturated salt solutions1 ).
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the Vapour Pressure of aqueous solutions saturated with respect to ammonium nitrate and sodium nitrate
Recueil des Travaux Chimiques des Pays-Bas, 2010Co-Authors: P. Dingemans, L. L. DijkgraafAbstract:The Vapour Pressure of the four-phase equilibrium: water Vapour-saturated solution-solid NH4NO3-solid NaNO3 has been measured from 10° C to the end of this line, i e. the eutectic of the binary system NH4NO3)-NaNO3. We found this eutectic to lie at 121.1 ± 0.1° C and at a composition of 78.2 percents by weight of NH4NO3, and 21.8 percents by weight of NaNO3. The Vapour Pressure line has a maximum at 94.0° C and a Pressure of 82.4 mm Hg. Previously deduced formulae for the calculation of maxima in Vapour Pressure lines and for the calculation of metastable eutectics, are found in this case also to give good agreement with the experimental results.
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the Vapour Pressure of solutions saturated with silver nitrate and with lead nitrate
Recueil des Travaux Chimiques des Pays-Bas, 2010Co-Authors: P. Dingemans, L. L. DijkgraafAbstract:The Vapour Pressure of the four-phase equilibrium solid AgNO3-solid Pb(NO3)2-saturated solution-water Vapour was measured from 10° C to the end point of this four-phase line. This end-point is the eutectic of the binary system AgNO3-Pb (NO3)2. This eutectic was subjected to exact investigation; the eutectic temperature was found to lie at 203.1° C, while the eutectic melt consists of 92.8 percent by weight of AgNO3 and 7.2 percent by weight of Pb (NO3)2. The measured Vapour Pressure line appears to possess 2 stable maxima, namely at 155.8°C and at 163.1° C; the corresponding values of the Vapour Pressure are 824 and 822 mm Hg, respectively. This system exhibits the phenomenon of 2 boiling points at atmospheric Pressure, namely at 140.9° C and at 176.1° C. Neither the presence of 2 stable maxima, nor the occurrence of 2 boiling points (at 1 at) had till now ever been observed in solutions saturated with two salts.
Eric Granryd - One of the best experts on this subject based on the ideXlab platform.
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a simple experimental investigation of saturated Vapour Pressure for hfc134a oil mixtures
International Journal of Refrigeration-revue Internationale Du Froid, 1992Co-Authors: Wei Shao, H Kraft, Eric GranrydAbstract:Abstract A new refrigerant , HFC134a, seems to be the most promising substitute for CFC12. The Vapour Pressure of HFC134a-oil mixtures is one parameter that is important for a proper analysis of the operation of refrigeration systems. This paper presents Vapour Pressure curves for HFC134a and three kinds of representative oil for different oil percentages, and for the temperature range from -20 to +40°C (253.15–313.15 K).
P. Dingemans - One of the best experts on this subject based on the ideXlab platform.
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The Vapour Pressure of saturated solutions of lead nitrate
Recueil des Travaux Chimiques des Pays-Bas, 2013Co-Authors: P. DingemansAbstract:The Vapour Pressure of saturated solutions of lead nitrate in water was measured at temperatures from 10° C to 130° C. This system forms a particularly good example of a rule for saturated salt solutions discovered by Miss Korvezee and Dingemans.1 . The relative Vapour Pressure of the saturated solutions (i. e. the Vapour Pressure of the saturated solution divided by the Vapour Pressure of pure water at the same temperature) is found to be a purely linear function of the temperature.
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The calculation of maxima in Vapour-Pressure curves
Recueil des Travaux Chimiques des Pays-Bas, 2010Co-Authors: A. E. Korvezee, P. Dingemans, L. L. DijkgraafAbstract:A simple approximate relation is derived for the temperature of the maximum occurring in the Vapour-Pressure lines of saturated solutions of a number of non-volatile substances of high melting point in a volatile solvent. The derivation is analogous to that for saturated solutions of one dissolved substance. This formula, although derived only for ideal mixtures, is found to give reasonably satisfactory results for a series of Vapour-Pressure curves determined in this laboratory in non-ideal systems.
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the Vapour Pressure of saturated solutions of sodium nitrate in water
Recueil des Travaux Chimiques des Pays-Bas, 2010Co-Authors: P. Dingemans, L. L. DijkgraafAbstract:The Vapour Pressure of saturated solutions of NaNO3 in water was measured from 10° C to 150° C. From these measurements it is found that the relative Vapour Pressure p/pw plotted as a function of the temperature gives a slightly curved line, as previously obtained for some other saturated salt solutions1 ).
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the Vapour Pressure of aqueous solutions saturated with respect to ammonium nitrate and sodium nitrate
Recueil des Travaux Chimiques des Pays-Bas, 2010Co-Authors: P. Dingemans, L. L. DijkgraafAbstract:The Vapour Pressure of the four-phase equilibrium: water Vapour-saturated solution-solid NH4NO3-solid NaNO3 has been measured from 10° C to the end of this line, i e. the eutectic of the binary system NH4NO3)-NaNO3. We found this eutectic to lie at 121.1 ± 0.1° C and at a composition of 78.2 percents by weight of NH4NO3, and 21.8 percents by weight of NaNO3. The Vapour Pressure line has a maximum at 94.0° C and a Pressure of 82.4 mm Hg. Previously deduced formulae for the calculation of maxima in Vapour Pressure lines and for the calculation of metastable eutectics, are found in this case also to give good agreement with the experimental results.
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the Vapour Pressure of solutions saturated with silver nitrate and with lead nitrate
Recueil des Travaux Chimiques des Pays-Bas, 2010Co-Authors: P. Dingemans, L. L. DijkgraafAbstract:The Vapour Pressure of the four-phase equilibrium solid AgNO3-solid Pb(NO3)2-saturated solution-water Vapour was measured from 10° C to the end point of this four-phase line. This end-point is the eutectic of the binary system AgNO3-Pb (NO3)2. This eutectic was subjected to exact investigation; the eutectic temperature was found to lie at 203.1° C, while the eutectic melt consists of 92.8 percent by weight of AgNO3 and 7.2 percent by weight of Pb (NO3)2. The measured Vapour Pressure line appears to possess 2 stable maxima, namely at 155.8°C and at 163.1° C; the corresponding values of the Vapour Pressure are 824 and 822 mm Hg, respectively. This system exhibits the phenomenon of 2 boiling points at atmospheric Pressure, namely at 140.9° C and at 176.1° C. Neither the presence of 2 stable maxima, nor the occurrence of 2 boiling points (at 1 at) had till now ever been observed in solutions saturated with two salts.
