scholarly journals Air Temperature, Humidity, and Leaf Age Affect Penetration of Urea Through Grapefruit Leaf Cuticles

2001 ◽  
Vol 126 (1) ◽  
pp. 44-50 ◽  
Author(s):  
Vladimir Orbović ◽  
Diann Achor ◽  
Peter Petracek ◽  
James P. Syvertsen
Keyword(s):  
Contact Angle ◽  
Relative Humidity ◽  
Air Temperature ◽  
Leaf Age ◽  
Solution Concentration ◽  
Contact Angles ◽  
Poncirus Trifoliata ◽  
Urea Solution ◽  
Solution Ph ◽  
Cuticle Thickness

Effects of air temperature, relative humidity (RH), and leaf age on penetration of urea through isolated leaf cuticles of `Marsh' grapefruit (Citrus×paradisi Macfad.) trees on `Carrizo' citrange (C. sinensis L. Osbeck × Poncirus trifoliata (L.) Raf. rootstock were examined. Intact cuticles were obtained from adaxial surfaces of `Marsh' grapefruit leaves of various ages. A finite dose diffusion system was used to follow movement of 14C-labeled urea from urea solution droplets across cuticles throughout a 4-day period. Within the first 4 to 6 hours after urea application, the rate of urea penetration increased as temperature increased from 19 to 28 °C, but there was no further increase at 38 °C. Increasing relative humidity increased urea penetration at 28 °C and 38 °C. Cuticle thickness, cuticle weight per area, and the contact angle of urea solution droplets increased as leaves aged. Cuticular permeability to urea decreased as leaf age increased from 3 to 7 weeks, but permeability increased in cuticles from leaves older than 9 weeks. Contact angles decreased with increased urea solution concentration on leaf surfaces that were 6 to 7 weeks old, but solution concentration had no effect on contact angle on cuticles from younger and older leaves. Changing urea solution pH from 8.0 to 4.0 could have an effect on the amount of urea penetrating the cuticle through the loss of urea from breakdown possibly due to hydrolysis. Results from this study define leaf age, environmental conditions, and formulation for maximum uptake of foliar-applied urea.

scholarly journals 506 Air Temperature, Humidity, Leaf Age, and Solution pH Affect Penetration of Urea Through Citrus Leaf Cuticles

HortScience ◽  
2000 ◽  
Vol 35 (3) ◽  
pp. 482A-482
Author(s):  
Vladimir Orbovic ◽  
Diann Achor ◽  
Peter Petracek ◽  
James P. Syvertsen
Keyword(s):  
Contact Angle ◽  
Air Temperature ◽  
Leaf Age ◽  
Solution Concentration ◽  
Contact Angles ◽  
Urea Solution ◽  
Solution Ph ◽  
Drying Time ◽  
Citrus Leaves ◽  
Cuticle Thickness

We examined the effects of air temperature, relative humidity (RH), leaf age, and solution pH on penetration of urea through isolated cuticles of citrus leaves. Intact cuticles were obtained from adaxial surfaces of different aged grapefruit leaves. A finite dose diffusion system was used to follow movement of 14C-labeled-urea from solution droplets across cuticles throughout a 4-day period. The rate of urea penetration increased as temperature increased from 19 °C to 28 °C, but penetration was not further increased at 38 °C. Increasing RH increased droplet drying time and urea penetration at both 28 °C and 38 °C. Cuticle thickness, weight per area, and the contact angle of urea solution droplets increased as leaves aged. Cuticular permeability to urea decreased as leaf age increased from 3 weeks to 7 weeks, but permeability increased in cuticles from leaves older than 9 weeks. Contact angles decreased with increased urea solution concentration on six 7-week-old leaf surfaces, but solution concentration had no effect on contact angle on cuticles from younger and older leaves. Reducing pH of urea solution from pH 8 to pH 4 accelerated the loss of urea from breakdown, possibly due to hydrolysis.

Effects of Ambient Air Relative Humidity and Surface Temperature on Water Droplet Spreading Dynamics

2018 ◽  
Author(s):  
M. Jadidi ◽  
M. A. Farzad ◽  
J. Y. Trepanier ◽  
A. Dolatabadi
Keyword(s):  
Contact Angle ◽  
Relative Humidity ◽  
Surface Temperature ◽  
Air Temperature ◽  
Water Droplet ◽  
Superhydrophobic Surface ◽  
High Speed ◽  
Ambient Air ◽  
Dew Point ◽  
Droplet Spreading

Water droplet impact on horizontal glass, aluminum, and superhydrophobic surfaces is experimentally investigated using high speed imaging. Experiments are performed at three different relative humidities (i.e. 10, 20 and 30%) and three surface temperatures (i.e. 20, 2 and −2°C) to ascertain their effects on droplet spreading and recoil behaviors. In this study, the droplet Weber number, Reynolds number, and the ambient air temperature are fixed at 16.2, 1687, and 23°C, respectively. The high-speed images of impact, spreading and recoil of the droplets as well as the temporal variations of droplet spreads are prepared. Results show that the ratio of surface temperature to dew point temperature (which depends on the air temperature and relative humidity) has a significant influence on droplet spreading, recoil, and contact angle. When this ratio is less than one, condensation and frost formation become important. Decreasing the mentioned ratio (it can be done by decreasing the surface temperature or increasing the relative humidity) causes the droplet spreading factor for hydrophilic surfaces to increase significantly. For superhydrophobic surface, decreasing this ratio (within the mentioned range) does not influence the maximum spreading. However, the recoiling phase is slowed down and the droplet detachment time form the superhydrophobic surface is increased noticeably. In addition, the equilibrium contact angle decreases as the mentioned ratio decreases.

scholarly journals Modeling of Virus Survival Time in Respiratory Droplets on Surfaces: A New Rational Approach for Antivirus Strategies

2021 ◽  
Vol 8 ◽  
Author(s):  
N. G. Di Novo ◽  
A. R. Carotenuto ◽  
G. Mensitieri ◽  
M. Fraldi ◽  
N. M. Pugno
Keyword(s):  
Experimental Data ◽  
Contact Angle ◽  
Relative Humidity ◽  
Survival Time ◽  
Salt Concentration ◽  
Saline Water ◽  
Artificial Saliva ◽  
Contact Angles ◽  
Rational Approach ◽  
Minimum Number

The modeling of the viability decay of viruses in sessile droplets is addressed considering a droplet sitting on a smooth surface characterized by a specific contact angle. To investigate, at prescribed temperature, how surface energy of the material and ambient humidity cooperate to determine the virus viability, we propose a model which involves the minimum number of thermodynamically relevant parameters. In particular, by considering a saline water droplet (one salt) as the simplest approximation of real solutions (medium and natural/artificial saliva), the evaporation is described by a first-order time-dependent nonlinear differential equation properly rearranged to obtain the contact angle evolution as the sole unknown function. The analyses were performed for several contact angles and two typical droplet sizes of interest in real situations by assuming constant ambient temperature and relative humidity in the range 0–100%. The results of the simulations, given in terms of time evolution of salt concentration, vapor pressure, and droplet volume, elucidate some previously not yet well-understood dynamics, demonstrating how three main regimes—directly implicated in nontrivial trends of virus viability and to date only highlighted experimentally—can be recognized as the function of relative humidity. By recalling the concept of cumulative dose of salts (CD), to account for the effect of the exposition of viruses to salt concentration on virus viability, we show how the proposed approach could suggest a chart of a virus fate by predicting its survival time at a given temperature as a function of the relative humidity and contact angle. We found a good agreement with experimental data for various enveloped viruses and predicted in particular for the Phi6 virus, a surrogate of coronavirus, the characteristic U-shaped dependence of viability on relative humidity. Given the generality of the model and once experimental data are available that link the vulnerability of a certain virus, such as SARS-CoV-2, to the concentrations of salts or other substances in terms of CD, it is felt that this approach could be employed for antivirus strategies and protocols for the prediction/reduction of human health risks associated with SARS-CoV-2 and other viruses.

scholarly journals Foliar Nitrogen Fertilization of Citrus in Florida

HortScience ◽  
1995 ◽  
Vol 30 (4) ◽  
pp. 773D-773
Author(s):  
B.R. Bondada ◽  
J.P. Syvertsen ◽  
L. Albrigo ◽  
A. Alva ◽  
P. Petracek
Keyword(s):  
Leaf Age ◽  
Contact Angles ◽  
Absorption Efficiency ◽  
Wax Deposition ◽  
Surface Wax ◽  
Young Leaves ◽  
Citrus Production ◽  
Citrus Leaves ◽  
Leaf Wettability ◽  
Cuticle Thickness

Foliar applications of urea nitrogen (N) is a relatively new practice in Florida citrus production resulting from applied research and changes in citrus fertilizer management philosophy. The present study investigated the effect of leaf age and surface morphology on leaf wettability as measured by contact angles, and absorption efficiency of foliar-applied N. Young leaves (0.25 and 1 month) were more efficient than old leaves in the absorption of foliar-applied N. Contact angles of water, urea-, and triazone-N solutions were low in the young leaves. The adaxial surfaces had lower contact angles than abaxial surfaces in each leaf age group. Inefficient N absorption and large contact angles in old leaves (3 and 6 months) were related to surface wax deposition and cuticle thickness, which increased with leaf age. 15N- and 14C-labeled urea are being used to determine precisely how the cuticle and wax affect foliar N absorption in citrus leaves.

scholarly journals Detrended Multiple Cross-Correlation Coefficient applied to solar radiation, air temperature and relative humidity

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Andrea de Almeida Brito ◽  
Heráclio Alves de Araújo ◽  
Gilney Figueira Zebende
Keyword(s):  
Relative Humidity ◽  
Solar Radiation ◽  
Solar Energy ◽  
Correlation Coefficient ◽  
Air Temperature ◽  
Cross Correlation ◽  
Global Solar Radiation ◽  
Meteorological Variables ◽  
Hourly Data ◽  
Cross Correlations

AbstractDue to the importance of generating energy sustainably, with the Sun being a large solar power plant for the Earth, we study the cross-correlations between the main meteorological variables (global solar radiation, air temperature, and relative air humidity) from a global cross-correlation perspective to efficiently capture solar energy. This is done initially between pairs of these variables, with the Detrended Cross-Correlation Coefficient, ρDCCA, and subsequently with the recently developed Multiple Detrended Cross-Correlation Coefficient, $${\boldsymbol{DM}}{{\boldsymbol{C}}}_{{\bf{x}}}^{{\bf{2}}}$$DMCx2. We use the hourly data from three meteorological stations of the Brazilian Institute of Meteorology located in the state of Bahia (Brazil). Initially, with the original data, we set up a color map for each variable to show the time dynamics. After, ρDCCA was calculated, thus obtaining a positive value between the global solar radiation and air temperature, and a negative value between the global solar radiation and air relative humidity, for all time scales. Finally, for the first time, was applied $${\boldsymbol{DM}}{{\boldsymbol{C}}}_{{\bf{x}}}^{{\bf{2}}}$$DMCx2 to analyze cross-correlations between three meteorological variables at the same time. On taking the global radiation as the dependent variable, and assuming that $${\boldsymbol{DM}}{{\boldsymbol{C}}}_{{\bf{x}}}^{{\bf{2}}}={\bf{1}}$$DMCx2=1 (which varies from 0 to 1) is the ideal value for the capture of solar energy, our analysis finds some patterns (differences) involving these meteorological stations with a high intensity of annual solar radiation.

scholarly journals Effects of trees, gardens, and nature trails on heat index and child health: design and methods of the Green Schoolyards Project

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Kevin Lanza ◽  
Melody Alcazar ◽  
Deanna M. Hoelscher ◽  
Harold W. Kohl
Keyword(s):  
Physical Activity ◽  
United States ◽  
Relative Humidity ◽  
Air Temperature ◽  
The United States ◽  
Heat Index ◽  
Activity Levels ◽  
Natural Setting ◽  
Physical Activity Levels ◽  
Nature Trails

Abstract Background Latinx children in the United States are at high risk for nature-deficit disorder, heat-related illness, and physical inactivity. We developed the Green Schoolyards Project to investigate how green features—trees, gardens, and nature trails—in school parks impact heat index (i.e., air temperature and relative humidity) within parks, and physical activity levels and socioemotional well-being of these children. Herein, we present novel methods for a) observing children’s interaction with green features and b) measuring heat index and children’s behaviors in a natural setting, and a selection of baseline results. Methods During two September weeks (high temperature) and one November week (moderate temperature) in 2019, we examined three joint-use elementary school parks in Central Texas, United States, serving predominantly low-income Latinx families. To develop thermal profiles for each park, we installed 10 air temperature/relative humidity sensors per park, selecting sites based on land cover, land use, and even spatial coverage. We measured green features within a geographic information system. In a cross-sectional study, we used an adapted version of System for Observing Play and Recreation in Communities (SOPARC) to assess children’s physical activity levels and interactions with green features. In a cohort study, we equipped 30 3rd and 30 4th grade students per school during recess with accelerometers and Global Positioning System devices, and surveyed these students regarding their connection to nature. Baseline analyses included inverse distance weighting for thermal profiles and summing observed counts of children interacting with trees. Results In September 2019, average daily heat index ranged 2.0 °F among park sites, and maximum daily heat index ranged from 103.4 °F (air temperature = 33.8 °C; relative humidity = 55.2%) under tree canopy to 114.1 °F (air temperature = 37.9 °C; relative humidity = 45.2%) on an unshaded playground. 10.8% more girls and 25.4% more boys interacted with trees in September than in November. Conclusions We found extreme heat conditions at select sites within parks, and children positioning themselves under trees during periods of high heat index. These methods can be used by public health researchers and practitioners to inform the redesign of greenspaces in the face of climate change and health inequities.

scholarly journals Influence of moisture content on the contact angle and surface tension measured on birch wood surfaces

2021 ◽  
Author(s):  
Rami Benkreif ◽  
Fatima Zohra Brahmia ◽  
Csilla Csiha
Keyword(s):  
Surface Tension ◽  
Contact Angle ◽  
Moisture Content ◽  
Solid Wood ◽  
Contact Angles ◽  
Surface Moisture ◽  
Wood Coatings ◽  
The Relationship ◽  
Wood Surfaces

AbstractSurface tension of solid wood surfaces affects the wettability and thus the adhesion of various adhesives and wood coatings. By measuring the contact angle of the wood, the surface tension can be calculated based on the Young-Dupré equation. Several publications have reported on contact angle measured with different test liquids, under different conditions. Results can only be compared if the test conditions are similar. While the roles of the drop volume, image shooting time etc., are widely recognized, the role of the wood surface moisture content (MC) is not evaluated in detail. In this study, the effect of wood moisture content on contact angle values, measured with distilled water and diiodomethane, on sanded birch (Betula pendula) surfaces was investigated, in order to find the relationship between them. With increasing MC from approximately 6% to 30%, increasing contact angle (decreasing surface tension) values were measured according to a logarithmic function. The function makes possible the calculation of contact angles that correspond to different MCs.

scholarly journals Biomimetic Approach for the Elaboration of Highly Hydrophobic Surfaces: Study of the Links between Morphology and Wettability

Biomimetics ◽  
2021 ◽  
Vol 6 (2) ◽  
pp. 38
Author(s):  
Quentin Legrand ◽  
Stephane Benayoun ◽  
Stephane Valette
Keyword(s):  
Contact Angle ◽  
Ginkgo Biloba ◽  
Contact Angle Hysteresis ◽  
Contact Angles ◽  
Textured Surfaces ◽  
Replication Process ◽  
Wetting Behavior ◽  
Static Contact ◽  
Biomimetic Approach ◽  
Highly Hydrophobic

This investigation of morphology-wetting links was performed using a biomimetic approach. Three natural leaves’ surfaces were studied: two bamboo varieties and Ginkgo Biloba. Multiscale surface topographies were analyzed by SEM observations, FFT, and Gaussian filtering. A PDMS replicating protocol of natural surfaces was proposed in order to study the purely morphological contribution to wetting. High static contact angles, close to 135∘, were measured on PDMS replicated surfaces. Compared to flat PDMS, the increase in static contact angle due to purely morphological contribution was around 20∘. Such an increase in contact angle was obtained despite loss of the nanometric scale during the replication process. Moreover, a significant decrease of the hysteresis contact angle was measured on PDMS replicas. The value of the contact angle hysteresis moved from 40∘ for flat PDMS to less than 10∘ for textured replicated surfaces. The wetting behavior of multiscale textured surfaces was then studied in the frame of the Wenzel and Cassie–Baxter models. Whereas the classical laws made it possible to describe the wetting behavior of the ginkgo biloba replications, a hierarchical model was developed to depict the wetting behavior of both bamboo species.

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