Wax Film Research Articles

Effect of a Spreading Adjuvant on Mesotrione Photolysis on Wax Films

There is little information about pesticide photostability on plants, especially when considering the effects of the formulation. We evaluated the photostability of a herbicide, mesotrione, on wax films. These surfaces are good systems to mimic the outer layer of the leaf. Within the range of recommended agricultural rates, pure mesotrione half-life on cuticular wax films was between 100 and 160 min. Formulated, the phototransformation rate was multiplied by a factor of 4.8. We assume that the acceleration is mainly due to the surfactants, agents that allow a better spreading of the active ingredient at the leaf surface. Since mesotrione photolysis is a fast process on wax films, we can assume that this process would be significant in the field after treatment.

Investigation of Automotive Detailing Products by Ellipsometry and Contact Angle Analysis

Within the automotive detailing community, there is much discussion focusing on the application of waxes and sealants to enhance and protect paint, and there are a very large number of commercial products on the market. The general idea behind the application of such products is that a wax or sealant layer or layers can increase gloss and “depth of colour”, provide protection against degradation by ultraviolet rays and also make it easier to keep the paint surface clean by shedding and repulsion of rain water. In this paper, the performance of several commercially-available automotive waxes and sealants is examined. In the absence of any available published work, we have used ellipsometry to determine the thicknesses of applied wax and sealant layers and have quantified the water beading eect by measuring the contact angles of water with the wax films.

Self-healing of voids in the wax coating on plant surfaces

The cuticles of plants provide a multifunctional interface between the plants and their environments. The cuticle, with its associated waxes, is a protective layer that minimizes water loss by transpiration and provides several functions, such as hydrophobicity, light reflection and absorption of harmful radiation. The self-healing of voids in the epicuticular wax layer has been studied in 17 living plants by atomic force microscopy (AFM), and the process of wax film formation is described. Two modes of wax film formation, a concentric layer formation and striped layer formation, were found, and the process of multilayer wax film formation is discussed. A new method for the preparation of small pieces of fresh, water-containing plant specimens for AFM investigations is introduced. The technique allows AFM investigations of several hours duration without significant shrinkage or lateral drift of the specimen. This research shows how plants refill voids in their surface wax layers by wax self-assembly and should be useful for the design of self-healing materials.

Photodegradation of Bentazon, Clopyralid, and Triclopyr on Model Leaves: Importance of a Systematic Evaluation of Pesticide Photostability on Crops

Photolyses of three herbicides, bentazon, clopyralid, and triclopyr, were studied on plant leaves after crop treatment. The experiments were carried out on cuticular wax films, which are good models for leaf surfaces. The pure compounds and their commercial formulations were investigated under simulated solar light. At the recommended agricultural application rates, the three formulated herbicides photolyzed more rapidly on films than on soil or in water. Their photolysis is likely to be an important dissipation path from crops after treatment. The effects induced by the adjuvants in formulations were varied. Adjuvants slowed the photodegradation of bentazon slightly. In Garlon, in which triclopyr and clopyralid are combined, the adjuvants did not affect the photolysis of clopyralid even though they accelerated the rate of photolysis of triclopyr by a factor of 7. The kinetics were also affected by the application rates. This work also underscores the importance of assessing the photoreactivity of active ingredients in conditions similar to those of their application.

Conservação pós-colheita de frutos de pimentão sob diferentes condições de armazenamento e filmes

Este trabalho teve como objetivo avaliar diferentes temperaturas e coberturas na conservação de frutos de pimentão 'Magali-R'. No primeiro experimento, avaliou-se o uso de filme de PVC ou cera, e os frutos foram armazenados a 20ºC e 66%UR, e no segundo experimento associou-se o filme de PVC e cera, com armazenamento a 22°C (67% UR); 12ºC (90% UR) e 5ºC (87% UR). Acompanhou-se a evolução da qualidade dos frutos avaliando-se a massa fresca, a aparência, o aparecimento de podridões e os teores de sólidos solúveis, acidez titulável e ácido ascórbico. A proteção dos pimentões com cera ou filme de PVC foi favorável à manutenção da aparência e da massa fresca, e protegeu-os contra podridões, sem prejuízos aos teores de sólidos solúveis, acidez titulável e ácido ascórbico, com aumento significativo na vida útil para até 33 dias com o armazenamento a 5°C.

Wetting, adhesion and friction of superhydrophobic and hydrophilic leaves and fabricatedmicro/nanopatterned surfaces

Superhydrophobic surfaces have considerable technological potential for variousapplications due to their extreme water-repellent properties. When two hydrophilic bodiesare brought into contact, any liquid present at the interface forms menisci, which increasesadhesion/friction and the magnitude is dependent upon the contact angle. Certain plantleaves are known to be superhydrophobic in nature due to their roughness and the presenceof a thin wax film on the leaf surface. Various leaf surfaces on the microscale and nanoscalehave been characterized in order to separate out the effects of the microbumps andnanobumps and the wax on the hydrophobicity. The next logical step in realizingsuperhydrophobic surfaces that can be produced is to design surfaces based onunderstanding of the leaves. The effect of micropatterning and nanopatterning on thehydrophobicity was investigated for two different polymers with micropatterns andnanopatterns. Scale dependence on adhesion was also studied using atomic forcemicroscope tips of various radii. Studies on silicon surfaces patterned with pillars of varyingdiameter, height and pitch values and deposited with a hydrophobic coating wereperformed to demonstrate how the contact angles vary with the pitch. The effect ofdroplet size on contact angle was studied by droplet evaporation and a transitioncriterion was developed to predict when air pockets cease to exist. Finally, anenvironmental scanning electron microscope study on the effect of droplet size of about20 µm radius on the contact angle of patterned surfaces is presented. The importance ofhierarchical roughness structure on destabilization of air pockets is discussed.

AFM relative stiffness measurement of the plasticising effect of a non-ionic surfactant on plant leaf wax

An AFM relative stiffness technique was applied to reconstituted Beta vulgaris L. wax films. Consecutive force arrays ( n = 100 ) made on the waxy surface at the same locations showed that there was no relative change in surface elasticity and this information was used as a reference to further experimental measurements. A surfactant solution was subsequently dropped on the waxy surface and the same array of indents was made at the same location as the reference test. The plant wax surface showed a reduction in its surface elasticity properties. The study has demonstrated that the AFM technique could be used to undertake a systematic assessment of the plasticising effects of agrochemicals on native and reconstituted plant wax films.

Understanding mesotrione photochemistry when applied on leaves

Environmental context. Pesticide has greatly contributed to the increased yields and regular production in agriculture; however, its use is nowadays more and more being questioned. Current authorisation procedures are more and more comprehensive (evaluating their environmental fate and impact on ecosystems and on human health) but are not yet fully satisfactory. Here we demonstrate the utility of evaluating the stability of pesticide towards sunlight when applied on crops. Abstract. We developed a methodology to perform laboratory studies that approach field conditions. To demonstrate our methods, we used the herbicide mesotrione. Simulated solar light irradiation experiments were conducted on several cuticular wax films. Adjuvants greatly favoured the rate of mesotrione photolysis. Specifically, the photolytic transformation of formulated mesotrione was 15 times faster than that of pure mesotrione. The morphology and composition of the wax films had a greater effect on the photolysis of formulated mesotrione than of pure mesotrione, which formed aggregates on the waxes. This shows the importance of considering the formulation when studying pesticide photolysis on crops. To corroborate our model, we conducted experiments on detached leaves. The rates of photolysis on leaves and on wax films were of the same order of magnitude. Finally, the mesotrione rate of photolysis on leaves is much higher compared with data from the literature in water and on soils. Photolysis is likely to be a fast dissipation process on crops. The photodegradation of pesticide on crops should be systematically evaluated.

MALDI MS Sample Preparation by Using Paraffin Wax Film: Systematic Study and Application for Peptide Analysis

Recently developed sample preparation techniques employing hydrophobic sample support have improved the detection sensitivity and mass spectral quality of matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS). These methods concentrate the samples on target by minimizing the sample area via the solvent repellent effect of the target surface. In the current study, we employed the use of paraffin wax film (Parafilm M) for improved MALDI MS analysis of low-abundance peptide mixtures, including neuronal tissue releasate and protein tryptic digests. This thin film was found to strongly repel polar solvents including water, methanol, and acetonitrile, which enabled the application of a wide range of sample preparation protocols that involved the use of various organic solvents. A "nanoliter-volume deposition" technique employing a capillary column has been used to produce tiny ( approximately 400 microm) matrix spots of 2,5-dihydroxybenzoic acid on the film. By systematically optimizing the sample volume, solvent composition, and film treatment, the Parafilm M substrate in combination with the nanoliter-volume matrix deposition method allowed dilute sample to be concentrated on the film for MALDI MS analysis. Peptide mixtures with nanomolar concentrations have been detected by MALDI time-of-flight and MALDI Fourier transform ion cyclotron resonance mass spectrometers. Overall, the use of Parafilm M enabled improved sensitivity and spectral quality for the analysis of complex peptide mixtures.

Fabricating superhydrophobic surfaces by molecular accumulation of polysiloxane on the wool textile finishing

In the present study, a novel and simple method of obtaining superhydrophobic surface through the migration of organic siloxane segments in the acrylate side chains to the outmost layer and forming the nano-protuberance on the micro-roughness wool fabrics was described. The chemical compositions and morphologies of the untreated/treated fabrics were characterized by the scanning electron microscopy and X-ray photoelectric energy spectroscopy. Meanwhile, the surface hydrophobicity was evaluated by the static contact angle measurement. The scanning electron microscopy photographs showed that the fiber surfaces of the treated fabrics were obviously granulated, and a wax film covered on the fibers could be observed. X-ray photoelectron spectroscopy analyses and static contact angle measurement further testified that the component of the wax was almost siloxane and that the surfaces of the treated fabrics had superhydrophobic property. The above results indicated that this method could be extended to prepare superhydrophobic surfaces by migrating the low-surface-energy matter and fabricating the nanoscale roughness on the micro-roughness material surfaces.

Removal of Organic Wax and Particles on Silicon after Batch type Polishing by Ozonated DI Water

To manufacture the wafer used for device chip, several polishing and cleaning process are required. In this study, new concept cleaning process was developed with ozonated DI water (DIO3) to achieve low COO (cost of ownership). Ozone concentration of 55 ppm is used to remove the wax film and particles. A commercial dewaxer was combined with DIO3 to reduce dewaxing time and SC-1 steps. DIO3 rinse resulted in less than 50Aå of wax thickness while DI water rinse did thicker than 300 Aå. Replacing DI rinse with DIO3 rinse resulted in lower contact angle and completely hydrophilic surface. Optical images of surfaces treated with DIO3 showed thinner wax layer which indicates no further cleaning steps required. Particle removal efficiency improved further by combining SC-1 cleaning step with DIO3 rinsing process.

Studies on polymers and composites from lignin and fiber derived from sugar cane

AbstractSugarcane fiber (i.e. bagasse) lignin has a larger fraction of aromatics unsubstitution in the ortho position than hardwood or softwood lignin and hence has the greater ability to be derivatized. Furthermore, organosolv lignin has a higher purity than sulfonated and kraft lignins. This work examines the purification of organosolv lignin derived from bagasse and the physico‐chemical properties of the lignin and lignin‐phenol formaldehyde (PF) resin coatings, and composites.The wetability tests have shown that lignin and lignin‐PF resin films are effective water barrier coatings, though the contact angles of lignin‐PF resin films were considerably less than the wax films. The overall mechanical properties (i.e. peak stress, peak strain and modulus) of the bagasse fiber composites were lower than the values obtained with the composites without the inclusion of bagasse fiber. Copyright © 2007 John Wiley & Sons, Ltd.

Infrared Spectroscopic Analysis of Chrysene and1.2-Benzanthracence in Wax films

Chrysene and 1.2-benzanthracene are successfully doped in a solid waxfilm and their vibrational spectra in 2000–400 cm−1 arediscussed. The harmonic frequencies and relative intensities of both themolecules observed in the film are compared with theoretical valuescalculated by the density functional theory (DFT) model as well as withthe previous experimental data. The effects on spectra due to change ofmatrix and some additional bands observed in the wax film are alsoreported. Excellent agreement in the spectral positions and strengthsbetween the experiments and DFT values are found.

Effect of surface waxes on the persistence of chlorpyrifos-methyl in apples, strawberries and grapefruits

The effects of the cuticle and epicuticular waxes of grapefruit, strawberry and apple on the photodegradation and penetration of chlorpyrifos-methyl were studied. Photodegradation experiments were conducted by exposing the insecticide to the light of a xenon lamp in the presence of a film of wax extracted from the fruit surface. The half-life of chlorpyrifos-methyl irradiated in absence of waxes was 9.6 min. The half-lives of pesticide irradiated in the presence of wax extracts of apple, grapefruit and strawberry were 83, 34 and 26 min, respectively. In penetration studies, fruit with and without wax layers were treated with an aqueous suspension of pesticide. The penetration of the pesticide from the cuticle to the pulp was measured after 24 h. Samples without wax contained a higher total amount of insecticide than those with wax. No pesticide was detected in samples of apple and grapefruit pulp. Residues were detected in all fractions of strawberry. The waxes and cuticle appear to have some effect on the photodegradation and penetration of chlorpyrifos-methyl in fruit samples.

POSTHARVEST TREATMENTS FOR EXTENDING MARKET LIFE OF FRESH HORSERADISH

Horseradish (Armoracia rusticana) has one of the highest rates of postharvest weight loss among all vegetable crops. Postharvest studies were conducted to identify improved methods of extending the market life of fresh horseradish roots. Postharvest treatments included submerging or coating thoroughly washed and dried roots in chlorine (150 ppm), hydrogen dioxide (Storox), 2,6-dichloro-4-nitroaniline (Botran), carnauba-based wax, shellac-based wax, paraffin wax, and polyolefin shrink film (75–100 micron thickness). Two treatments, shrink wrapping and paraffin waxing, were superior in reducing postharvest weight loss and extending horseradish root market life. Roots from the non-paraffin waxed and nonshrink-wrapped treatments lost an average of 20% weight after only 4 days of ambient temperature storage. This resulted in significant root shriveling and unacceptable market appearance. Roots from the shrink wrapped treatments lost an average of 1% weight after 4 days of ambient temperature storage, while paraffin waxed roots lost about 3% weight. It is important to thoroughly dry the roots before shrink wrapping, to avoid moisture condensation on the inner surface of the film and subsequent microbial growth. All of the shrink-wrapped roots and paraffin waxed roots were marketable after 14 days of ambient storage, and no surface mold was detected. Less than 3% weight loss occurred after 14 days of ambient storage in all shrink-wrapped roots, while paraffin-waxed roots lost about 9% weight. Weight loss in the unwrapped roots from the other postharvest treatments ranged from an unacceptably high 44% to 48% after 14 days.

Micro- and nanoscale characterization of hydrophobic and hydrophilic leaf surfaces

Superhydrophobic surfaces as well as low adhesion and friction are desirable for variousindustrial applications. Certain plant leaves are known to be hydrophobic in nature due totheir roughness and the presence of a thin wax film on the surface of the leaf. The purposeof this study is to fully characterize the leaf surfaces on the micro- and nanoscale whileseparating out the effects of the micro- and the nanobumps of hydrophobic leaves on thehydrophobicity. Hydrophilic leaves were also studied to better understand therole of wax and roughness. Furthermore, the adhesion and friction properties ofhydrophobic and hydrophilic leaves were studied. Using an optical profiler andan atomic/friction force microscope (AFM/FFM), measurements were made tofully characterize the leaf surfaces. It is shown that the nanobumps play a moreimportant role than the microbumps in the hydrophobic nature as well as frictionof the leaf. This study will be useful in developing superhydrophobic surfaces.

Surface characterization and adhesion and friction properties of hydrophobic leaf surfaces

Super-hydrophobic surfaces as well as low adhesion and friction are desirable for various industrial applications. Certain plant leaves are known to be hydrophobic in nature. These leaves are hydrophobic due to the presence of microbumps and a thin wax film on the surface of the leaf. The purpose of this study is to fully characterize the leaf surface and to separate out the effects of the microbumps and the wax on the hydrophobicity. Furthermore, the adhesion and friction properties of the leaves, with and without wax, are studied. Using an optical profiler and an atomic/friction force microscope (AFM/FFM), measurements on the hydrophobic leaves, both with and without wax, were made to fully characterize the leaf surface. Using a model that predicts contact angle as a function of roughness, the roughness factor for the hydrophobic leaves has been calculated, which is used to calculate the contact angle for a flat leaf surface. It is shown that both the microbumps and the wax play an equally important role in the hydrophobic nature as well as adhesion and friction of the leaf. This study will be useful in developing super-hydrophobic surfaces.

Phototransformation of the Herbicide Sulcotrione on Maize Cuticular Wax

Vegetation plays a key role in environmental cycling and the fate of many organic pollutants. This is especially the case for pesticides because plant leaves are their first reaction environment after application. It is commonly accepted that photochemical reactions of pollutants on plants predominantly take place in the cuticular wax coating of the leaves. Thus, we used films made of either cuticular wax extracted from maize or carnauba gray wax as a model support. Under simulated sunlight irradiation, sulcotrione (a new class of triketone herbicides) sorbed on cuticular wax films was photolyzed and mainly underwent an intramolecular cyclization. The photoproduct is a chromone derivative which was isolated and fully characterized. It is reported for the first time as a sulcotrione degradation product. The photoreactivity of formulated sulcotrione at the surface of cuticular waxes was investigated too. It photodegraded more rapidly than nonformulated sulcotrione. This study also shows that the rate of sulcotrione photolysis was much faster than the rate of penetration into the wax; photolysis should be, thus, a relevant process in real conditions.

Tribo-Characteristics of Stainless Steel Sheets in Iterative Processes of Sheet Metal Forming

The present authors have developed a tribo-simulator for the long-term iterative processes of sheet metal forming. A sheet metal blank wrapped around a mandrel with a rubber sheet can be deformed by the steel ball as a tool to make spiral grooves on the metal sheet, and the frictional force, normal pressure, and temperature on the steel ball can be measured. The tribo-simulator could realize a total sliding length of 7.2 m and an iterative number of 40 under the sliding speed of about 300–800 mm/s. Friction coefficients and temperature can be measured during all the iterative processes. Some tribological tests of different sheets of stainless steel lubricated with various kinds of mineral oil with different viscosities and a solid wax film coating-type lubricant were carried out. As a result, the variation in friction coefficient changed significantly depending on the lubricants and sheets used. The friction coefficient and temperature increment increased markedly after certain iterative processes with galling when using lower-viscosity mineral oil and no lubricant. On the other hand, the friction coefficient and the temperature increment showed approximately low constant values without galling when using the highest-viscosity mineral oil and the solid wax lubricant. The friction coefficient and the temperature increment were approximately constant without galling when using medium-viscosity mineral oil with some extreme-pressure additives. Two different sheets of stainless steel SUS 304 (Japan Industrial Standard) showed different tribological characteristics in spite of the fact that they were the same type of austenite stainless steel.

Surface Composition of Myrmecophilic Plants: Cuticular Wax and Glandular Trichomes on Leaves of Macaranga tanarius

Primary plant surfaces, covered with cuticles consisting of cutin and waxes, are important substrates for interaction with insects. The composition of leaf surfaces of the myrmecophilic plant Macaranga tanarius was studied. The prenylated flavanone nymphaeol-C was identified in surface extracts and was localized exclusively in glandular trichomes on the abaxial leaf side. The epidermal pavement cells surrounding these trichomes were covered with a smooth film of epicuticular wax from which few small wax crystals protruded. The epicuticular wax amounted to approximately 8 microg cm(-2), corresponding to 85% of the wax load on the adaxial as well as the abaxial leaf sides. The epicuticular wax mixtures from both leaf surfaces contained more than 70% primary alcohols, 14% fatty acids, 2% aldehydes, and traces of alkyl acetates, with chain lengths ranging from C(20) to C(38). In contrast, the intracuticular wax layer was largely dominated by triterpenoid alcohols alpha-amyrin, beta-amyrin, and lupeol. Consequently, these characteristic compounds are not available for direct contact with insects on the plant surface.