Protective Wax Research Articles

Compatibility analysis between natural rubber/polybutadiene rubber and protective waxes based on experiments and materials studio simulations

AbstractProtective waxes are typically mixtures of paraffin and microcrystalline waxes that retard the aging of unsaturated rubbers and are widely used in rubber products. The wax solubility of rubber products is important for understanding the migration behavior and film formation of waxes and determining the appropriate wax content in rubber compounds. In this article, protective waxes were applied to natural rubber (NR)/polybutadiene rubber (BR) based sidewall rubber and the compatibility between NR and BR and the protective wax dissolution in these rubbers were investigated with a focus on the former investigation through Materials Studio simulations. It was found that the simulation results are strongly correlated with the wax migration test results on compounded and cured rubber at different NR/BR mass ratios. Blends and mesoscopic dynamics simulations yielded good compatibility between NR and BR and favorable blend morphology. By analyzing the solubility parameter, R value, mean square displacement and diffusion coefficient of wax chains with different lengths in the NR/BR matrix, the mechanism and reasons for the wax precipitation variation of protective waxes at varying NR/BR mass ratios were analyzed from a microstructural point of view, which provides strong theoretical support for the design of the molecular structure of protective waxes.

Larvae of Cryptolaemus montrouzieri(Coleoptera: Coccinellidae) Prioritize Secretion of Protective Wax Over Daily Consumption and Growth.

In holometabolous insects, the immature or larval stage is characterized by a high rate of food consumption. The nutrients obtained from which are directed towards the maintenance of metabolism, growth, pupation, and metamorphosis. However, when resources are scarce, the lack thereof can affect the growth rate and compromise the metamorphosis and formation of adults. Do increased energy expenditures yield outcomes similar to those resulting from restricted food intake during the larval stage? We hypothesized that removing the wax layer from the larvae of the ladybird Cryptolaemus montrouzieri Mulsant, 1850 would result in increased energy expenditure, which can compromise both larval growth and adult size. We compared the development time, feeding rate, and adult size of larvae with an intact wax layer, and those with constantly removed wax layers. We found that the production of the wax layer was continuous. Unlike the waxed larvae, the larvae of C. montrouzieri extended their development time in response to energy depletion through wax removal. The total number of mealybugs consumed by waxless larvae was higher than the total number consumed by waxed larvae; however, the daily consumption of waxless larvae was lower than that of waxed larvae. Furthermore, the adults of waxless larvae were smaller than those whose larvae had intact wax layers. This suggests that the cost associated with wax layer secretion is a pivotal factor in larval growth. Removing this layer does not get compensated by increased larval feeding or extended development time.

Inducing a summer brood break increases the efficacy of oxalic acid vaporization for Varroa destructor (Mesostigmata: Varroidae) control in Apis mellifera (Hymenoptera: Apidae) colonies.

The ectoparasitic mite, Varroa destructor (Anderson and Trueman), is the leading cause of western honey bee colony, Apis mellifera (L.), mortality in the United States. Due to mounting evidence of resistance to certain approved miticides, beekeepers are struggling to keep their colonies alive. To date, there are varied but limited approved options for V. destructor control. Vaporized oxalic acid (OA) has proven to be an effective treatment against the dispersal phase of V. destructor but has its limitations since the vapor cannot penetrate the protective wax cap of honey bee pupal cells where V. destructor reproduces. In the Southeastern United States, honey bee colonies often maintain brood throughout the year, limiting the usefulness of OA. Prior studies have shown that even repeated applications of OA while brood is present are ineffective at decreasing mite populations. In the summer of 2021, we studied whether incorporating a forced brood break while vaporizing with OA would be an effective treatment against V. destructor. Ninety experimental colonies were divided into 2 blocks, one with a brood break and the other with no brood break. Within the blocks, each colony was randomly assigned 1 of 3 treatments: no OA, 2 g OA, or 3 g OA. The combination of vaporizing with OA and a forced brood break increased mite mortality by 5× and reduced mite populations significantly. These results give beekeepers in mild climates an additional integrated pest management method for controlling V. destructor during the summer season.

Chlorinated paraffins in multimedia during residential interior finishing: Occurrences, behavior, and health risk

Though with bioaccumulation and toxicity, chlorinated paraffins (CPs) are still high produced and widely utilized in various daily necessities for extender plasticization and flame retardation. CPs can be released during the reprocessing processes of finishing materials and distributed in multi-environmental media. Herein, concentrations and compositions of CPs in four representative media including interior finishing materials, PM10, total suspended particulate (TSP), and dust samples collected from eight interior finishing stages were studied. Unexpectedly, CP concentrations in ceramic tiles was found to be high with a mean value of 7.02 × 103 μg g−1, which could be attributed to the presence of CPs in the protective wax coated on ceramic tiles surfaces. Furthermore, the pollution characteristics of short-chain and medium-chain CPs (SCCPs and MCCPs) in those samples were inconsistent. According to the investigation regarding Kdust−TSP and KPM10-TSP, the occurrence and distribution of CPs in indoor atmospheric particles (PM10 and TSP) and dust were highly affected by reprocessing processes (cutting, hot melting, etc.) compared to that in the finishing materials. Moreover, dermal contact was the primary pathway of CP exposure for the occupational population (interior construction workers) for most interior finishing stages, and the interior finishing process is the prime CP exposure period for the occupational groups. As suggested by our assessment, though hardly posing an immediate health risk, CPs exposure still presents unneglected adverse health effects, which calls for adequate personal protections during interior finishing, especially in developing countries.

Decontamination protocols affect the internal microbiota of ticks

Studies on the microbiota of ticks have promoted hypotheses about the combined effects of the bacterial community, its functional contributions to the tick’s physiology or probable competition effects with some tick-borne pathogens. However, knowledge on the origin of the microbiota of newly hatched larvae is missing. This study aimed to elucidate the source(s) of the microbiota in unfed tick larvae, addressing the composition of the “core microbiota” and the best ways to decontaminate eggs for microbiota studies. We applied laboratory degree bleach washes and/or ultraviolet light treatments on engorged Rhipicephalus australis females and/or their eggs. No significant effects of these treatments on the reproductive parameters of females and the hatching rates of eggs were observed. However, the different treatments did show striking effects on the composition of the microbiota. The results indicated that bleach washes disrupted the internal tick microbiota in females, implying that bleach may have entered the tick and subsequently affected the microbiota. Furthermore, the analyses of results demonstrated that the ovary is a main source of tick microbiota, while the contribution of Gené’s organ (a part of the female reproductive system that secretes a protective wax coat onto tick eggs) or the male’s spermatophore requires further investigation. Further studies are needed to identify best practice protocols for the decontamination of ticks for microbiota studies.Graphical

The synergistic effects of rosehip oil and matrine against Icerya aegyptiaca (Douglas) (Hemiptera: Coccoidea) and the underlying mechanisms.

Icerya aegyptiaca (Douglas) is an important agricultural pest that has a protective wax shell. Insecticides generally fail to achieve the desired control of I. aegyptiaca because of difficulties penetrating this wax shell. Plant essential oils are rich in terpenoids and have strong penetrability and expansibility, which can enable the rapid penetration and absorption of insecticides, thereby improving the control effect. Matrine is a botanical insecticide with contact and stomach toxicity, low toxicity toward non-target organisms and is environmentally friendly. In this study, we tested the insecticidal activity of rosehip oil (Ro)/matrine combinations and revealed the synergistic mechanism of Ro and its components with matrine in terms of physiology and biochemistry. Ro/matrine combinations have strong penetrating power, enabling matrine to quickly penetrate the wax shell of I. aegyptiaca and enter the insect body. This improves the insecticidal activity and enhances inhibition of acetylcholinesterase activity. Ro and its main chemical constituents, cineole and (+)-camphor, showed synergistic effects on matrine with synergic ratios of 4.79, 3.49 and 4.21, respectively. Combinations of Ro, cineole and (+)-camphor with matrine have good insecticidal effects on I. aegyptiaca while remaining safe to the environment. These combinations of biological insecticides have excellent development prospects and provide a new reference for the pest management of scale insects. © 2022 Society of Chemical Industry.

Assessing Repeated Oxalic Acid Vaporization in Honey Bee (Hymenoptera: Apidae) Colonies for Control of the Ectoparasitic Mite Varroa destructor.

The American beekeeping industry continually experiences colony mortality with annual losses as high as 43%. A leading cause of this is the exotic, ectoparasitic mite, Varroa destructor Anderson & Trueman (Mesostigmata: Varroidae). Integrated Pest Management (IPM) options are used to keep mite populations from reaching lethal levels, however, due to resistance and/or the lack of suitable treatment options, novel controls for reducing mites are warranted. Oxalic acid for controlling V. destructor has become a popular treatment regimen among commercial and backyard beekeepers. Applying vaporized oxalic acid inside a honey bee hive is a legal application method in the U.S., and results in the death of exposed mites. However, if mites are in the reproductive stage and therefore under the protective wax capping, oxalic acid is ineffective. One popular method of applying oxalic is vaporizing multiple times over several weeks to try and circumvent the problem of mites hiding in brood cells. By comparing against control colonies, we tested oxalic acid vaporization in colonies treated with seven applications separated by 5 d (35 d total). We tested in apiaries in Georgia and Alabama during 2019 and 2020, totaling 99 colonies. We found that adult honey bees Linnaeus (Hymenoptera: Apidae), and developing brood experienced no adverse impacts from the oxalic vaporization regime. However, we did not find evidence that frequent periodic application of oxalic during brood-rearing periods is capable of bringing V. destructor populations below treatment thresholds.

Determination of morpholine residues in apples by liquid chromatography tandem mass spectrophotometry (LC-MS/MS)

Morpholine is an emulsifier that is normally used as a protective wax coating on the surfaces of fruit and vegetable. In order to keep fruits fresh, extend their shelf-life, against insect and fungal contamination for a long time, morpholine has been widely applied despite of the reported carcinogenic potential in previous studies and export prohibition in many countries. A highly sensitive method has been developed for the determination of this food additive in fruits using ultra-performance liquid chromatography tandem mass spectrophotometry. By using 1 % acetic acid in methanol for extraction and analyzing with binary ammonium formate 20 mM and acetonitrile, the method has been applied successfully to determine morpholine residues in apple samples collected at local markets in Hanoi, Vietnam. The good coefficient correlation was achieved in the linear range of 5 - 300 µg/L (R2 = 0.9998). The low limit of detection (LOD) and limit of quantification (LOQ) were 2 µg/kg and 5 µg/kg, respectively. The recoveries of morpholine were 83 – 108 % over three spike levels 20 - 60 μg/L for apple, peel and pulp matrices. The repeatability (RSDr %) was 1.1 % for apple matrix, 2.36 % for peel and 3.67 % for pulp. The reproducibility values (RSDR %) were 1.49, 3.50 and 4.08 % for apple, peel and pulp, respectively. This method could be further performed in different type of fruit and vegetable comiditities to determine the morpholine content.

Changes in the Endophytic Fungal Community Associated with Pilosocereus royenii (Cactaceae) Infested by the Invasive Hypogeococcus sp. (Hemiptera: Pseudococcidae)

Entire communities of columnar cacti such as Pilosocereus royenii are being devastated by the infestation of the invasive mealybug Hypogeococcus sp. in Puerto Rico. This insect was first described as Hypogeococcus pungens, but later studies suggest it might be a different, undescribed specie of Hypogeococcus. The use of common insecticides results in a limited control strategy because this insect inhabits deformed plant tissue and covers itself with a protective wax. Generally, endophytic fungi provide the host plant with defenses against biotic and abiotic factors through the production of bioactive compounds that increase plant defenses and their ability to attack pathogens. We studied the community of cultivatable endophytic fungi associated with P. royenii to establish its possible role in the survival of cacti infested with Hypogeococcus sp. We assessed fragments of surface-sterilized plant tissue from asymptomatic and cacti infested by Hypogeococcus sp. The rate of fungal infection and relative frequency of fungal morphotypes isolated from plant tissue was calculated as well as the similarity of the fungal community among individuals. Asymptomatic and infested P. royenii individuals presented similar fungal infection rates. Fungal colonies were isolated from asymptomatic P. royenii tissue and from affected individuals, representing a total of 34 fungal morphotypes. Infested individuals harbored an endophytic fungal community with greater similarity to each other compared to the asymptomatic individuals.

THE FORMATION OF SOYBEAN PHYTOCENOSIS AND SEEDS QUALITY DEPENDING ON THE INTENSIFICATION FACTORS

The scale of soybeans cultivation in the world agriculture it takes a leading place among crops due to its valuable biological and economic properties. Soybeans are ahead of all other crops in terms of acreage growth. Today, the varietal spectrum has grown enormously and the gross grain yield of soybeans has increased. However, the realization of the genetic potential of modern varieties remains rather low and the average yield in Ukraine is 1,2-1,9 t/ha. First of all, maintaining and improving the quality of soybean seed is an important task, along with increasing yields. Vegetation of plants in the period of growth and development and their productivity depend in a certain way on the quality of the seed material, namely: germination, purity, sanitary condition, etc. The scientifically sound fertilizer application system combines basic and row fertilizers and fertilization of cultivated plants during the growing season. Foliar nutrition is called leaf uptake and absorption by the plant of nutrients, amino acids and growth regulators that the root system does not supply enough. The essence of such nutrition is that readily available nutrients of fertilizers enter the vegetative organs of the plants, quickly penetrate the protective wax barrier - cuticle, epidermis - and enter the cells of the plant. The permeability of epidermal cells of the multilayered cuticle depends on the concentration of the nutrient solution, the phase of growth and development, the area and nature of the cover of the leaf blade, climatic conditions, the time of feeding, the shape of the nutrient and other factors. The results of studying the influence of foliar fertilizers on the formation of soybean varieties phytocoenosis productivity and their influence on the qualitative indicators of seeds have been covered. The positive role of the foliar fertilizers action in the formation of individual productivity indicators of soybean plants was found. Foliar feeding is a measure of timely provision of balanced, composition and concentration of nutrients in ionic form – the most accessible for absorption by the leaf surface. Thus, the positive role of foliar fertilizers and varietal features of soybean in the formation of yield indicators was established. Thus, the two-time use of the Vuxal Microplant microfertilizer in the budding and green bean phases in the cultivation of Kent soybean variety allows obtaining positive indicators of the chemical composition of the seeds.

Tick Gené’s organ engagement in lipid metabolism revealed by a combined transcriptomic and proteomic approach

Lipids play key roles in arthropod metabolism. In ticks, these biomolecules are transported from fat body to other organs, such as ovary and Gené’s organ. Gené’s organ, an apparatus found exclusively in female ticks, secretes a protective wax coat onto the egg surface, increasing egg viability in the environment due to waterproof, cohesive, and antimicrobial properties. In this work, a combined transcriptomic and proteomic approach shows that Gené’s organ not solely secrets compounds taken up from the hemolymph, but is actively engaged in synthesis, modification, and oxidation of lipids. Gené’s organ was analyzed at two distinct stages: 1) when ticks detach from host by the end of hematophagous phase, and 2) during egg-laying. Data show that Gené’s organ undergoes a maturation process before the onset of oviposition, in preparation for its role during egg-laying. Because it deals with a wax-secreting organ, the study focused on lipid metabolism, examining a full machinery to synthesize, modify, and oxidize fatty acids. Proteins involved in sterol modification, transport, and degradation were also addressed. In addition to highlighting Gené’s organ importance in tick reproductive physiology, the results reveal proteins and pathways crucial to egg wax secretion, and consequently, egg development in the environment. Tools targeting these molecules and pathways would impair egg viability in the environment, and therefore have the potential to be developed into novel tick control methods.

Preliminary study on analysis and removal of wax from a Carrara marble statue

This preliminary study has mainly focused on the wax identification by nuclear magnetic resonance (NMR) and removal. Wax is used for many purposes in the field of art as protective coatings on wooden, stone or metal objects. From the comparison of the spectra H NMR and in particular with the correspondence of the resonance peaks of the samples taken from the statue and beeswax and paraffin, we can conclude that the wax applied on the statue surface is beeswax. From our data, it can be concluded that, to remove the beeswax, from any stone support, the more effective solvent is the mixture of cyclohexane/ethyl acetate. The removal percentages ranged from 19 to 99%. Lower percentages of removal have been observed in the case of yellow marble, probably because of its high porosity. We can affirm that, this solvent mixture can be employed in real art objects using cotton swabs to remove protective wax.

New trends in art conservation, the use of lasers to clean as well as generate an augmented reality representation of an iconic public monument in bronze: The Alma Mater

The 3.66 m tall and over nine-ton outdoor bronze sculpture of Alma Mater, created by Lorado Taft in 1929, is an iconic symbol of the University of Illinois at Urbana-Champaign. The conservation treatment of the sculpture came with some unexpected surprises, such as the discovery of failing internal ferrous nuts and bolts which needed to be replaced. The treatment involved removing the sculpture from its granite base, dismantling major elements of the sculpture and replacing the ferrous bolts with silicon bronze bolts, laser cleaning the surface with 1064 nm Q-switch scanning lasers, application of patina, applying a protective microcrystalline wax coating, and reinstallation of the sculpture. Analysis was performed with microscopy, X-radiography, and scanning electron microscopy. The conservation treatment involved cutting edge laser technology to remove corrosion from the surface, while structured light three-dimensional (3D) scanning and digital modeling techniques were used to create a new form of public interaction with the sculpture by 3D scanning the sculpture and creating a life like 3D digital model to create an augmented reality Alma Mater sculpture to temporarily take the place of the missing monument. Augmented reality is a technology which overlays a digital representation in registration with the real world giving the viewer an experience of interacting with the digital object as though it was actually present at that location in the real world. It is a longstanding tradition for students to have their picture taken with the sculpture during graduation, and thanks to this innovative use of technology, they were able to get their picture taken with a sculpture that was digitally, but not physically, present. In addition to receiving information and media related to the conservation treatment while it was taking place, the University of Illinois community and the class of 2013 was able to experience the augmented reality monument generated over the original base. This project demonstrates how augmented reality works of art can be used to replace the experience of actual objects that are removed from public view for conservation treatments.

Effect of wax degrading bacteria on life cycle of the pink hibiscus mealybug, Maconellicoccus hirsutus (Green) (Hemiptera: Pseudococcidae)

The pink mealybug Maconellicoccus hirsutus (Green) (Hemiptera: Pseudococcidae) is a polyphagous insect pest with protective wax covering. Bacterial isolates originating from M. hirsutus cadavers were screened for their wax degrading effects and the three most potent wax degrading isolates were identified to be Serratia marcescens, Pseudomonas aeruginosa and Bacillus subtilis by 16S rRNA gene sequencing. Bacteria degrading M. hirsutus wax reduced female longevity, offspring production as well as weight and wax content of emerging adults. Treatment with S. marcescens was the most effective in reducing wax content, fecundity and honeydew production. Analysis of honeydew produced by M. hirsutus after each microbial treatment revealed reduction in amino acids, proteins, and reducing sugars concentration compared to controls. Most negative effect on reducing sugars was observed in the B. subtilis treatment suggesting disequilibrium in mealybug metabolism. S. marcescens and P. aeruginosa treatments showed significantly lower content of wax as compared to control suggesting utilization of wax as carbon source by these microorganisms. This study suggests that the use of each of three bacterial isolates reduces wax content of mealybug and might be useful in devising mealybug control strategies.

A steroidal molecule present in the egg wax of the tick Rhipicephalus (Boophilus) microplus inhibits bacterial biofilms

The cattle tick Rhipicephalus (Boophilus) microplus lays eggs in the soil near the roots of grass, or in similar highly moist environments that are prone to biofilm formation. Tick eggs have a protective wax coating that may be a source of nutrients for microorganisms. However, as the eggs remain viable and show no visible signs of microbial colonization, we hypothesized that the coating might have anti-biofilm properties. We show here that the coating inhibits biofilm formation by both Gram-negative and Gram-positive bacteria, though by different mechanisms. We have identified the anti-biofilm molecule as N-(3-sulfooxy-25-cholest-5-en-26-oyl)-L-isoleucine (boophiline), and we show that it inhibits the expression of fliC (flagellin) and cdrA (biofilm scaffold), whose products are necessary for biofilm formation in Pseudomonas aeruginosa. Boophiline is a novel biofilm inhibitor being also effective against Staphylococcus epidermidis biofilm. In our study we show evidences of the boophiline mode of action in the protection of arthropod eggs against biofilm colonization.

Entomopathogenic fungi as potential control agents against the Brazilian ground pearl Eurhizococcus brasiliensis (Hemiptera: Margarodidae)

The Brazilian ground pearl Eurhizococcus brasiliensis is the most prevalent insect pest of grapes in Brazil. The natural occurrence and biological activity of entomopathogenic fungi (EF) against this pest are poorly known. In this study, we evaluate the presence of E. brasiliensis-associated EF in soil and the virulence of a ground pearl-derived strain of Isaria fumosorosea against cysts under laboratory conditions. EF were not identified on cysts in an initial survey performed in a grape-producing area in southern Brazil. However, 6% of mobile females that had emerged from cysts were infected by Metarhizium brunneum, which was the first report of this insect pathogen on ground pearls in Brazil. Cysts without the protective wax layer were inoculated with I. fumosorosea conidia suspension by immersion. The symptoms and the signs of the disease were described. Infected cysts had a yellow-ochre color and “hard-boiled egg” consistency when broken, in contrast to the intense bright yellow color and “raw egg” consistency of living cysts. Vegetative fungal cells were present inside symptomatic cysts, and later, outside conidiation was visible. The LC25 for the cysts protected with the wax layer and also inoculated by immersion was 1.31 x 107 conidia·mL-1. However, the presence of fungal structures was not observed on symptomatic individuals. Considering the motionlessness of cysts and the absence of disease signs for mortality assessment, the symptoms described may be helpful for further studies on E. brasiliensis control using I. fumosorosea.

Effectiveness of isopropyl myristate/cyclomethicone D5 solution of removing cuticular hydrocarbons from human head lice (Pediculus humanus capitis)

BackgroundIn the treatment of human head lice infestation, healthcare providers are increasingly concerned about lice becoming resistant to existing pesticide treatments. Traditional pesticides, used to control these pests, have a neurological mechanism of action. This publication describes a topical solution with a non-traditional mechanism of action, based on physical disruption of the wax layer that covers the cuticle of the louse exoskeleton. This topical solution has been shown clinically to cure 82% of patients with only a 10-minute treatment time, repeated once after 7 days. All insects, including human head lice, have a wax-covered exoskeleton. This wax, composed of hydrocarbons, provides the insect with protection against water loss and is therefore critical to its survival. When the protective wax is disrupted, water loss becomes uncontrollable and irreversible, leading to dehydration and death. A specific pattern of hydrocarbons has been found in all of the head louse cuticular wax studied. Iso-octane effectively removes these hydrocarbons from human head lice’s cuticular wax.MethodsA method of head louse cuticle wax extraction and analysis by gas chromatography was developed. Human head lice (Pediculus humanus capitis) were collected from infested patients and subjected to any of three extraction solvents comprising either the test product or one of two solvents introduced as controls. A gas chromatograph equipped with a flame ionization detector (GC/FID) was used to determine the presence of hydrocarbons in the three head lice extracts.ResultsIn the study reported herein, the test product isopropyl myristate/cyclomethicone D5 (IPM/D5) was shown to perform comparably with iso-octane, effectively extracting the target hydrocarbons from the cuticular wax that coats the human head louse exoskeleton.ConclusionsDisruption of the integrity of the insect cuticle by removal of specific hydrocarbons found in the cuticular wax appears to offer a mechanism for killing lice without the likelihood of encountering genetic resistance.

Composition differences between epicuticular and intracuticular wax substructures: How do plants seal their epidermal surfaces?

The protective wax coating on plant surfaces has long been considered to be non-uniform in composition at a subcellular scale. In recent years, direct evidence has started to accumulate showing quantitative compositional differences between the epicuticular wax (i.e. wax exterior to cutin that can be mechanically peeled off) and intracuticular wax (i.e. wax residing within the mechanically resistant layer of cutin) layers in particular. This review provides a first synthesis of the results acquired for all the species investigated to date in order to assign chemical information directly to cuticle substructures, together with an overview of the methods used and a discussion of possible mechanisms and biological functions. The development of methods to probe the wax for z-direction heterogeneity began with differential solvent extractions. Further research employing mechanical wax removal by adhesives permitted the separation and analysis of the epicuticular and intracuticular wax. In wild-type plants, the intracuticular (1-30 μg cm(-2)) plus the epicuticular wax (5-30 μg cm(-2)) combined to a total of 8-40 μg cm(-2). Cyclic wax constituents, such as triterpenoids and alkylresorcinols, preferentially or entirely accumulate within the intracuticular layer. Within the very-long-chain aliphatic wax components, primary alcohols tend to accumulate to higher percentages in the intracuticular wax layer, while free fatty acids and alkanes in many cases accumulate in the epicuticular layer. Compounds with different chain lengths are typically distributed evenly between the layers. The mechanism causing the fractionation remains to be elucidated but it seems plausible that it involves, at least in part, spontaneous partitioning due to the physico-chemical properties of the wax compounds and interactions with the intracuticular polymers. The arrangement of compounds probably directly influences cuticular functions.

Production of a protective wax of improved quality from petroleum feedstock

A procedure is proposed for the production of a protective wax, the essence of which consists in dewaxing of the reffinate of lube-oil distillate with a boiling range of from 450-490 to 520°C using solvents of acetone:methyl tri-butyl ether mixtures (with additives), acetone:/methyl ethyl ketone:toluol mixtures, etc. The procedure in question ensures a reduction in the net cost of the protective wax and improvement in its in-service properties.

Production of uniform and thick enriched isotopic Te targets by means of the HIVIPP method

Thick enriched isotopic 130Te targets are required to search for high-spin isomers in 142Pr using fusion reactions in 130Te produced in a low-energy 17N radioactive ion (RI) beam (∼5 MeV) at RCNP, Osaka University. For this investigation, we have successfully prepared self-supporting 130Te targets of more than 4 mg/cm 2 in thickness with 22 mm diameter and with-and-without backing-support using the HIVIPP method with a protective wax coating. The deposition yield and the thickness uniformity of the Te targets were compared with Te targets of like thickness and size made by vacuum deposition from a flat boat source and a crucible source with a collimator.