scholarly journals Cellulose δ18O is an index of leaf-to-air vapor pressure difference (VPD) in tropical plants

2011 ◽  
Vol 108 (5) ◽  
pp. 1981-1986 ◽  
Author(s):  
Ansgar Kahmen ◽  
Dirk Sachse ◽  
Stefan K. Arndt ◽  
Kevin P. Tu ◽  
Heraldo Farrington ◽  
...  
Keyword(s):  
Vapor Pressure ◽  
Pressure Difference ◽  
Tropical Plants ◽  
Vapor Pressure Difference

Setting Realistic Design Indoor Conditions for Residential Buildings by Vapor Pressure Difference

2009 ◽  
Vol 6 (9) ◽  
pp. 102052 ◽  
Author(s):  
Patrick Roppel ◽  
Mark Lawton ◽  
William C. Brown ◽  
Phalguni Mukhopadhyaya ◽  
Mavinkal K. Kumaran ◽  
...  
Keyword(s):  
Vapor Pressure ◽  
Pressure Difference ◽  
Residential Buildings ◽  
Vapor Pressure Difference ◽  
Indoor Conditions

Photosynthesis in an open field for exotic versus native vines of the southeastern United States

1989 ◽  
Vol 67 (2) ◽  
pp. 443-446 ◽  
Author(s):  
Gregory A. Carter ◽  
Alan H. Teramura ◽  
Irwin N. Forseth
Keyword(s):  
Vapor Pressure ◽  
Pressure Difference ◽  
Native Species ◽  
Leaf Gas Exchange ◽  
Water Vapor Pressure ◽  
High Irradiance ◽  
Pueraria Lobata ◽  
Vapor Pressure Difference ◽  
High Vapor ◽  
Parthenocissus Quinquefolia

The potential importance of leaf gas exchange to the prolific growth characteristics of the exotic vines Pueraria lobata and Lonicera japonica versus the native vines Rhus radicans, Parthenocissus quinquefolia, Vitis vulpina, and Clematis virginiana was evaluated. Under high irradiance and low leaf-air water vapor pressure difference, photosynthesis was similar (23 – 27 μmol∙m−2∙s−1) among species with the exception of R. radicans (16 μmol∙m−2∙s−1). Conductance and transpiration were greater in Pueraria lobata than in the other species. When the leaf-air vapor pressure difference was high (4.0 kPa) photosynthesis in the exotic vines decreased more than in several of the native species. Photosynthesis in L. japonica and Parthenocissus quinquefolia, and to a lesser extent in Pueraria lobata, was reduced by high vapor pressure differences even though internal CO2 partial pressures remained relatively high, suggesting a nonstomatal reduction of photosynthetic capacity. Thus, the highly prolific growth typical of the exotic vines may not be attributable to greater steady-state photosynthesis.

Osmosis: Characteristics of Liquid at an Interface

2006 ◽  
Author(s):  
Larry D. Howlett
Keyword(s):  
Kinetic Energy ◽  
Kinetic Theory ◽  
Vapor Pressure ◽  
Pressure Difference ◽  
Total Kinetic Energy ◽  
Universal Model ◽  
Vapor Pressure Difference ◽  
Water Ice ◽  
Speed Distribution

Many explanations for the movement of water across a membrane have been presented. One idea proposes that osmosis is the movement of water in response to a vapor pressure difference. It is difficult to accept this model for osmosis without a good understanding of the existence of a vapor in a liquid. We propose a model for a vapor in a liquid. The model is based upon the kinetic theory of gas and Maxwell's predicted speed distribution. Since vapor pressure and total kinetic energy are both expressions of the energy of a gas, we compare the model to published values of vapor pressure for water, ice, and several other liquids. Based upon this limited comparison, it appears that this model may be a universal model for the continuous existence of a vapor in a liquid or a solid.

Photosynthesis and transpiration in large forest-grown Douglas-fir: diurnal variation

1981 ◽  
Vol 59 (3) ◽  
pp. 349-356 ◽  
Author(s):  
Jerry W. Leverenz
Keyword(s):  
Stomatal Conductance ◽  
Vapor Pressure ◽  
Diurnal Variation ◽  
Pressure Difference ◽  
Intercellular Space ◽  
Net Photosynthesis ◽  
Douglas Fir ◽  
Leaf Temperature ◽  
Photon Flux ◽  
Vapor Pressure Difference

Net photosynthesis, transpiration, and stomatal conductance of terminal shoots of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) were measured using an open gas exchange system. Correlations between these physiological parameters and environmental variables on an overcast day, a cool partly sunny day, and a day of high temperature and leaf–air vapor pressure difference are presented. Diurnal variation in shoot water potential and intercellular space CO2 concentration had little effect on the physiological parameters. Leaf–air vapor pressure difference and (or) leaf temperature had considerable influence on days of high temperatures. Net photosynthetic rate was strongly correlated with photon flux density on completely overcast days.Stomatal conductance exerted little control on diurnal variation of net photosynthetic rates on overcast days because stomatal conductance saturated at lower photon flux densities than net photosynthesis. When net photosynthesis was light saturated parallel responses of stomatal and residual conductances to vapor pressure difference and (or) leaf temperature occurred. Intercellular space CO2 concentration remained fairly constant when net photosynthesis was light saturated.

scholarly journals Experimental Study on the Heat Transfer Performance of Pump-Assisted Capillary Phase-Change Loop

2021 ◽  
Vol 11 (22) ◽  
pp. 10954
Author(s):  
Xiaoping Yang ◽  
Gaoxiang Wang ◽  
Cancan Zhang ◽  
Jie Liu ◽  
Jinjia Wei
Keyword(s):  
Thin Film ◽  
Heat Transfer ◽  
Vapor Pressure ◽  
Pressure Difference ◽  
Heat Dissipation ◽  
Vapor Pressure Difference ◽  
Thin Film Evaporation ◽  
Film Evaporation ◽  
Start Up ◽  
Liquid Vapor

To overcome the two-phase flow instability of traditional boiling heat dissipation technologies, a porous wick was used for liquid-vapor isolation, achieving efficient and stable boiling heat dissipation. A pump-assisted capillary phase-change loop with methanol as the working medium was established to study the effect of liquid-vapor pressure difference and heating power on its start-up and steady-state characteristics. The results indicated that the evaporator undergoes four heat transfer modes, including flooded, partially flooded, thin-film evaporation, and overheating. The thin-film evaporation mode was the most efficient with the shortest start-up period. In addition, heat transfer modes were determined by the liquid-vapor pressure difference and power. The heat transfer coefficient significantly improved and the thermal resistance was reduced by increasing liquid-vapor pressure as long as it did not exceed 8 kPa. However, when the liquid-vapor pressure exceeded 8 kPa, its influence on the heat transfer coefficient weakened. In addition, a two-dimensional heat transfer mode distribution diagram concerning both liquid-vapor pressure difference and power was drawn after a large number of experiments. During an engineering application, the liquid-vapor pressure difference can be controlled to maintain efficient thin-film evaporation in order to achieve the optimum heat dissipation effect.

scholarly journals Raf-like kinases and receptor-like (pseudo)kinase GHR1 are required for stomatal vapor pressure difference response

2021 ◽  
Vol 118 (47) ◽  
pp. e2107280118
Author(s):  
Po-Kai Hsu ◽  
Yohei Takahashi ◽  
Ebe Merilo ◽  
Alex Costa ◽  
Li Zhang ◽  
...  
Keyword(s):  
Signal Transduction ◽  
Osmotic Stress ◽  
Vapor Pressure ◽  
Guard Cell ◽  
Pressure Difference ◽  
Stomatal Closure ◽  
Signal Transduction Pathway ◽  
Anion Channel ◽  
Vapor Pressure Difference ◽  
Raf Kinase

Stomatal pores close rapidly in response to low-air-humidity-induced leaf-to-air vapor pressure difference (VPD) increases, thereby reducing excessive water loss. The hydroactive signal-transduction mechanisms mediating high VPD–induced stomatal closure remain largely unknown. The kinetics of stomatal high-VPD responses were investigated by using time-resolved gas-exchange analyses of higher-order mutants in guard-cell signal-transduction branches. We show that the slow-type anion channel SLAC1 plays a relatively more substantial role than the rapid-type anion channel ALMT12/QUAC1 in stomatal VPD signaling. VPD-induced stomatal closure is not affected in mpk12/mpk4GC double mutants that completely disrupt stomatal CO2 signaling, indicating that VPD signaling is independent of the early CO2 signal-transduction pathway. Calcium imaging shows that osmotic stress causes cytoplasmic Ca2+ transients in guard cells. Nevertheless, osca1-2/1.3/2.2/2.3/3.1 Ca2+-permeable channel quintuple, osca1.3/1.7-channel double, cngc5/6-channel double, cngc20-channel single, cngc19/20crispr-channel double, glr3.2/3.3-channel double, cpk-kinase quintuple, cbl1/4/5/8/9 quintuple, and cbl2/3rf double mutants showed wild-type-like stomatal VPD responses. A B3-family Raf-like mitogen-activated protein (MAP)-kinase kinase kinase, M3Kδ5/RAF6, activates the OST1/SnRK2.6 kinase in plant cells. Interestingly, B3 Raf-kinase m3kδ5 and m3kδ1/δ5/δ6/δ7 (raf3/6/5/4) quadruple mutants, but not a 14-gene raf-kinase mutant including osmotic stress-linked B4-family Raf-kinases, exhibited slowed high-VPD responses, suggesting that B3-family Raf-kinases play an important role in stomatal VPD signaling. Moreover, high VPD–induced stomatal closure was impaired in receptor-like pseudokinase GUARD CELL HYDROGEN PEROXIDE-RESISTANT1 (GHR1) mutant alleles. Notably, the classical transient “wrong-way” VPD response was absent in ghr1 mutant alleles. These findings reveal genes and signaling mechanisms in the elusive high VPD–induced stomatal closing response pathway.

scholarly journals THE DETERMINATION OF MOLECULAR WEIGHT

1955 ◽  
Vol 33 (5) ◽  
pp. 755-762 ◽  
Author(s):  
A. F. Sirianni ◽  
I. E. Puddington
Keyword(s):  
Molecular Weight ◽  
Vapor Pressure ◽  
Organic Compounds ◽  
Chemical Stability ◽  
Pressure Difference ◽  
Molecular Weight Range ◽  
Vapor Pressure Difference ◽  
Static Measurement ◽  
Molecular Weights

The molecular weights of organic compounds of known constitution have been determined with satisfactory accuracy, using milligram quantities of materials, by a static measurement of the vapor pressure difference between pure solvents and solutions of the compounds. The method may be used over a considerable temperature range. The suitability of solvents is governed by their chemical stability and vapor pressure. Results obtained using compounds in the molecular weight range of 600–1000 are reported.

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