scholarly journals Extracuticular Wax and Contact Angle Measurements on Wheat (Triticum Vulgare L.)

1967 ◽  
Vol 20 (3) ◽  
pp. 509 ◽  
Author(s):  
JH Troughton ◽  
DM Hall
Keyword(s):  
Contact Angle ◽  
Leaf Surface ◽  
Flag Leaf ◽  
Contact Angles ◽  
Abaxial Surface ◽  
Triticum Vulgare ◽  
Angle Measurements ◽  
Abaxial Leaf Surface ◽  
Contact Angle Measurements ◽  
Plant Grown

Extracuticular wax and contact angles on wheat were studied because of their influence on the retention of chemical sprays and on disease resistance. Wax formed extensive deposits on wheat, irrespective of variety, stage of growth, or part of the plant, and these deposits overlaid or projected from the cuticle as platelets and rodlets. Platelets covered the adaxial and abaxial leaf surfaces of seedlings and some mature plants, while a net of rodlets covered the ear, culm, sheath, and flag leaf abaxial surface. Rods were occasionally present on the abaxial surface of mature vegetative leaves. Wax influenced the advancing contact angle of water droplets on wheat. Contact angles were all high, i.e. greater than 130� and generally about 150�. The contact angle on the adaxial leaf surface was higher than on the abaxial leaf surface, except on glasshouse-grown reproductive plants, where there was no difference between the two sides. Seedlings had higher contact angles than mature plants, but there was no trend in contact angle with tissue age within a leaf or within a mature plant. The contact angle on the flag leaf of glasshouse-grown reproductive Aotea plants was 24� higher than on a similar plant grown in the field.

scholarly journals The Leaf Wettability of Various Potato Cultivars

Plants ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 504
Author(s):  
Ewa Papierowska ◽  
Jan Szatyłowicz ◽  
Stanisław Samborski ◽  
Joanna Szewińska ◽  
Elżbieta Różańska
Keyword(s):  
Contact Angle ◽  
Sessile Drop ◽  
Leaf Surface ◽  
Solanum Tuberosum L ◽  
Fungal Disease ◽  
Potato Cultivars ◽  
Potato Leaf ◽  
Angle Measurements ◽  
Contact Angle Measurements ◽  
Leaf Wettability

Leaf wettability has an impact on a plant’s ability to retain water on its leaf surface, which in turn has many environmental consequences. In the case of the potato leaf (Solanum tuberosum L.), water on the leaf surface may contribute to the development of a fungal disease. If fungal disease is caused, this may reduce the size of potato harvests, which contribute significantly to meeting global food demand. The aim of this study was to assess the leaf wettability of five potato cultivars (i.e., Bryza, Lady Claire, Rudawa, Russet Burbank, Sweet Caroline) in the context of its direct and indirect impact on potato yield. Leaf wettability was assessed on the basis of contact angle measurements using a sessile drop method with an optical goniometer. For Bryza and Rudawa cultivars, which showed, respectively, the highest and the lowest contact angle values, light microscopy as well as scanning electron microscopy analyses were performed. The results of the contact angle measurements and microscopic image analyses of the potato leaf surfaces indicated that the level of wettability was closely related to the type of trichomes on the leaf and their density. Therefore, higher resistance of the Rudawa cultivar to biotic stress conditions could be the result of the presence of two glandular trichome types (VI and VII), which produce and secrete metabolites containing various sticky and/or toxic chemicals that may poison or repel herbivores.

Empirical Formulae in Correlating Droplet Shape and Contact Angle

2016 ◽  
Vol 69 (4) ◽  
pp. 431 ◽  
Author(s):  
Ten It Wong ◽  
Hao Wang ◽  
Fuke Wang ◽  
Sau Leng Sin ◽  
Cheng Gen Quan ◽  
...  
Keyword(s):  
Contact Angle ◽  
Empirical Formula ◽  
Contact Angles ◽  
Shape Deformation ◽  
Direct Identification ◽  
Simple Method ◽  
Droplet Shape ◽  
Spherical Dome ◽  
Angle Measurements ◽  
Contact Angle Measurements

In contact angle measurements, direct identification of the contact angles from images taken from a goniometer suffers from errors caused by optical scatterings. Contact angles can be more accurately identified by the height and width of the droplet. Spherical dome is a simple model used to correlate the contact angles to the droplet shape; however, it features intrinsic errors caused by gravity-induced shape deformation. This paper demonstrates a simple method of obtaining an empirical formula, determined from experiments, to correct the gravity-induced error in the spherical dome model for contact angle calculations. A series of contact angles, heights, and surface contact widths are simultaneously collected for a large amount of samples, and the contact angles are also calculated using the spherical dome model. The experimental data are compared with those obtained from the spherical dome model to acquire an empirical formula for contact angles. Compared with the spherical dome model, the empirical formula can reduce the average errors of the contact angle from –16.3 % to 0.18 %. Furthermore, the same method can be used to correct the gravity errors in the spherical dome for the volume (calculated by height and width), height (calculated by contact angle and volume), and width (calculated by contact angle and volume), and the spherical dome errors can be reduced from –20.9 %, 24.6 %, and –4.8 % to 2 %, –0.13 %, and –0.6 %, respectively. Our method is generic and applicable for all kinds of solvent and substrates, and the derived empirical formulae can be directly used for water droplets on any substrate.

Measurements of the Contact Angles for Various Fluids Which Are Widely Used in the Oilfields to Improve Oil Recovery

2018 ◽  
Author(s):  
M. Elsharafi ◽  
K. Vidal ◽  
R. Thomas
Keyword(s):  
Surface Tension ◽  
Contact Angle ◽  
Interfacial Tension ◽  
Oil Recovery ◽  
Dynamic Contact Angle ◽  
Dynamic Contact ◽  
Contact Angles ◽  
Rock Face ◽  
Angle Measurements ◽  
Contact Angle Measurements

Contact angle measurements are important to determine surface and interfacial tension between solids and fluids. A ‘water-wet’ condition on the rock face is necessary in order to extract oil. In this research, the objectives are to determine the wettability (water-wet or oil-wet), analyze how different brine concentrations will affect the wettability, and study the effect of the temperature on the dynamic contact angle measurements. This will be carried out by using the Cahn Dynamic Contact Angle. Analyzer DCA 315 to measure the contact angle between different fluids such as surfactant, alkaline, and mineral oil. This instrument is also used to measure the surface properties such as surface tension, contact angle, and interfacial tension of solid and liquid samples by using the Wilhelmy technique. The work used different surfactant and oil mixed with different alkaline concentrations. Varying alkaline concentrations from 20ml to 1ml were used, whilst keeping the surfactant concentration constant at 50ml.. It was observed that contact angle measurements and surface tension increase with increased alkaline concentrations. Therefore, we can deduce that they are directly proportional. We noticed that changing certain values on the software affected our results. It was found that after calculating the density and inputting it into the CAHN software, more accurate readings for the surface tension were obtained. We anticipate that the surfactant and alkaline can change the surface tension of the solid surface. In our research, surfactant is desirable as it maintains a high surface tension even when alkaline percentage is increased.

Degradation of Hydrophobic Surface Coatings Under Water Exposure

2018 ◽  
Author(s):  
Matthew A. Trapuzzano ◽  
Rasim Guldiken ◽  
Andrés Tejada-Martínez ◽  
Nathan B. Crane
Keyword(s):  
Contact Angle ◽  
Material Selection ◽  
Contact Angle Hysteresis ◽  
Hydrophobic Surface ◽  
Contact Angles ◽  
Water Exposure ◽  
Angle Measurements ◽  
Degradation Rates ◽  
Contact Angle Measurements ◽  
Receding Contact

Many important processes depend on the wetting of liquids on surfaces. Wetting is commonly controlled through material selection, coatings, and/or surface texture, however these means are sensitive to environmental conditions. Some “hydrophobic” fluoropolymer coatings are sensitive to extended water exposure as evidenced by declining contact angles and increasing contact angle hysteresis. Understanding degradation of these coatings is critical to processes that employ them. To accomplish this, contact angle measurements were taken before, during, and after slides coated with FluoroSyl 3750 or Cytop were submerged in water, or vibrated while covered in water. Both methods demonstrated similar changes in advancing contact angle though vibration increased degradation rates significantly. However, it does not simply accelerate the process as different trends are apparent in receding contact angles. The FluoroSyl 3750 showed no clear degradation under either condition. Surface profilometry did not detect any surface morphology differences that might cause contact angle change.

Mechanisms of Resistance to Glyphosate in a Ryegrass (Lolium Multiflorum) Biotype from Chile

Weed Science ◽  
2007 ◽  
Vol 55 (5) ◽  
pp. 435-440 ◽  
Author(s):  
Paola Michitte ◽  
Rafael De Prado ◽  
Nelson Espinoza ◽  
Juan Pedro Ruiz-Santaella ◽  
Christian Gauvrit
Keyword(s):  
Leaf Surface ◽  
Lolium Multiflorum ◽  
Glyphosate Resistance ◽  
Contact Angles ◽  
Italian Ryegrass ◽  
Foliar Uptake ◽  
Mechanisms Of Resistance ◽  
Abaxial Surface ◽  
Abaxial Leaf Surface ◽  
Target Enzyme

Glyphosate behavior was examined in Italian ryegrass plants from Chile that were sensitive (S) and resistant (R) to this herbicide. In order to explain the resistance to glyphosate, contact angles, spray retention, foliar uptake, herbicide translocation, and target enzyme activity were studied. Contact angles of glyphosate solutions at a field concentration were 40° to 45° on the abaxial surface of R leaves as compared to 70° on S. Glyphosate spray retention by R plants was 35% lower than by S plants. Glyphosate uptake by the abaxial leaf surface of R plants was about 40% lower than that of S plants. In addition, in the R plants more glyphosate migrated to the tip of the treated leaves. The target enzyme in R and S plants was sensitive to the herbicide. Based on these and previous results, it is concluded that resistance in this Italian ryegrass biotype results from lower spray retention, lower foliar uptake from the abaxial leaf surface, and altered translocation pattern. The decreases in spray retention and foliar uptake constitute new mechanisms of glyphosate resistance.

Contact angles and hysteresis, with some reference to flotation research

1977 ◽  
Vol 30 (1) ◽  
pp. 205 ◽  
Author(s):  
IW Wark
Keyword(s):  
Surface Roughness ◽  
Contact Angle ◽  
Gas Phase ◽  
Water Vapour ◽  
Relative Motion ◽  
Solid Surface ◽  
Contact Angles ◽  
Russian School ◽  
Angle Measurements ◽  
Contact Angle Measurements

A technique used in flotation research for contact angle measurements is recommended for wider use. The effect of one aspect of surface roughness on the relative motion of fluid/solid systems is discussed. The function of the water vapour present in the gas phase adjacent to the line of triple contact is examined. A claim of the Russian school of surface chemists is questioned, namely, that a discrete film of water on the solid surface invariably dominates both hysteresis and contact angle.

Surface Dipoles Influence the Wettability of Terminally Fluorinated Organic Films

1998 ◽  
Vol 546 ◽  
Author(s):  
Ramon Colorado ◽  
Michael Graupe ◽  
Mitsuru Takenaga ◽  
Thomas Koini ◽  
T. Randall Lee
Keyword(s):  
Contact Angle ◽  
Organic Thin Films ◽  
Dipole Interaction ◽  
Contact Angles ◽  
Aprotic Solvents ◽  
Angle Measurements ◽  
Infrared Reflection ◽  
Contact Angle Measurements ◽  
Assembled Monolayers ◽  
High Degree

AbstractThe correlation of differences in the wettabilities of partially fluorinated self-assembled monolayers (SAMs) to changes in the chemical structure and composition of the films was explored by contact angle goniometry and polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS). SAMs of simple alkanethiols (CH3(CH2)nSH with n = 9-15) and their CF3-terminated analogs (CF3(CH2)nSH with n = 9-15) were prepared by adsorption from solution onto evaporated gold. Advancing contact angles of hexadecane were measured on both the terminally fluorinated surfaces and the hydrocarbon surfaces. These data were compared to those obtained using a series of polar aprotic contacting liquids. As expected, the contact angles of hexadecane were higher on the CF3-terminated SAMs than on the CH3-terminated SAMs. The contact angles of the polar aprotic solvents, however, were measurably lower on the CF3- terminated SAMs than on the CH3-terminated SAMs. These observations were rationalized on the basis that the introduction of the CF3 terminal groups yields oriented surface dipoles that interact with the dipoles of the polar contacting liquids. Further support for this model was provided by the observation of an inverse parity (“odd-even”) effect in the wettabilities of the polar aprotic solvents on the CF3-terminated surfaces. Analysis by PM-IRRAS revealed that both types of films consist of predominately trans-extended alkyl chains with relatively few gauche defects in a densely packed arrangement. The high degree of order is consistent with the detection of the parity effect, where small changes in the orientation of the tail groups can be sensed by contact angle measurements only in highly ordered organic thin films. The significance of the dipole-oriented dipole interaction in describing interfacial wettabilities is discussed.

Contact Angle Measurements of Wetting In Pristine and Ion Implanted High Modulus Benzene Derived Graphite Fibers

1984 ◽  
Vol 40 ◽  
Author(s):  
O. C. de Hodgins ◽  
M. S. Dresselhaus ◽  
D. Uhlmann
Keyword(s):  
Contact Angle ◽  
Carbon Fibers ◽  
Structural Disorder ◽  
Contact Angles ◽  
X Ray Diffraction ◽  
Three Solutions ◽  
X Ray ◽  
Angle Measurements ◽  
Contact Angle Measurements ◽  
Graphite Fibers

AbstractMeasurements are reported of the contact angles of benzene-derived carbon fibers with de-ionized water, aminopropyltriethoxy silane and du Pont 5878 polyimide solutions. Both pristine fibers and fibers implanted with 5×1012 cm-2 and 1×1015 cm-2 fluences of 31p ions were investigated. Such implantation was observed to decrease the contact angle in all three solutions. The ion implantation had no significant effect on tensile strength, but did result in increased structural disorder (as reflected in the width of the main wide angle X-ray diffraction peak) and increased surface roughness. The increased disorder and roughness are believed to be principally responsible for the observed change in wetting angle.

Sign in / Sign up

Export Citation Format

Share Document