Search results for "Wax"
showing 10 items of 107 documents
Preliminary study on analysis and removal of wax from a Carrara marble statue
2015
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 remova…
The effect of macromolecular architecture of ethylene copolymers with multi-alkenylsilsesquioxane on morphological, rheological and dynamic mechanica…
2021
Abstract The influence of the degree and the way of incorporation of multi-alkenylsilsesquioxane into the polymer chain on morphological, rheological and dynamic mechanical parameters were determined. It was found that POSS incorporated into the polymer chain was located outside the crystalline structure of lamella in amorphous phase. The incorporation of POSS-6-2 as a pendant group resulted in significant increase of separation of macromolecules. The key factor in rheological and dynamic mechanical behavior of copolymers turned out to be the way of POSS incorporation into the polymer chain. The incorporation of POSS into the polymer chain as a pendant group resulted in decreased relaxation…
Chemical and physical modification of hemp fibres by steam explosion technology
2013
In current research attempt has been made to analyse hemp fibres treated with steam explosion (SE) technology. Disintegration of hemp fibres separated from non-retted, dew-retted and dried stems of hemp ('Purini')[1] by alkali treatment and steam explosion (SE) were investigated. An average intensive SE in combination with the hydro-thermal and alkali after-treatment allows decreasing the diameter of hemp fibres and reduce the concentration of non-celluloses components, among them hemicelluloses, lignin, pectin, waxes and water [1;2].
Beeswax cleaning by solvent extraction of pesticides
2018
We set out to test if the methodology used to clean sheep wool wax (Lanolin) from pesticides could be used to clean beeswax as well. We first made an aggregate sample of brood comb wax from three different US beekeepers. Sub-samples of these aggregate wax samples were analyzed for pesticide contamination. The remaining wax, was then dissolved into hexane solution and run through four N, N-Dimethylformamide (DMF) washes. During these extractions, the pesticides partitioned into the DMF, and so were removed from the beeswax. Following the solvent extractions, the beeswax was tested again for pesticides. An average of 95% of the pesticide contamination was removed by the chemical wash procedur…
Perception oro-sensorielle des lipides alimentaires et obésité
2016
International audience; The gustation is a dynamic system able to rapid physiological adaptations in response to on-going environmental changes that characterize our feed (rhythm, quality, quantity). Based on the modulation of taste sensitivity thresholds, this homeostatic system contributes to build the feeding behavior by driving the food choices. Therefore, a dysfunction of this regulatory system might impact on dietary habits and thus, ultimately, on health. Consistent with this assumption, recent data report that a diet-induced obesity is associated both with a dysfunction of the oral fat detection system and a preferential consumption of fat-rich diets in rats and mice. In humans, a s…
Role of Surface Chemistry in the Superhydrophobicity of the Springtail Orchesella cincta (Insecta:Collembola)
2020
Collembola are ancient arthropods living in soil with extensive exposure to dirt, bacteria, and fungi. To protect from the harsh environmental conditions and to retain a layer of air for breathing when submerged in water, they have evolved a superhydrophobic, liquid-repelling cuticle surface. The nonfouling and self-cleaning properties of springtail cuticle make it an interesting target of biomimetic materials design. Recent research has mainly focused on the intricate microstructures at the cuticle surface. Here we study the role of the cuticle chemistry for the Collembola species Orchesella cincta (Collembola, Entomobryidae). O. cincta uses a relatively simple cuticle structure with prima…
Adhesion enhancement of cribellate capture threads by epicuticular waxes of the insect prey sheds new light on spider web evolution
2017
To survive, web-building spiders rely on their capture threads to restrain prey. Many species use special adhesives for this task, and again the majority of those species cover their threads with viscoelastic glue droplets. Cribellate spiders, by contrast, use a wool of nanofibres as adhesive. Previous studies hypothesized that prey is restrained by van der Waals' forces and entrapment in the nanofibres. A large discrepancy when comparing the adhesive force on artificial surfaces versus prey implied that the real mechanism was still elusive. We observed that insect prey's epicuticular waxes infiltrate the wool of nanofibres, probably induced by capillary forces. The fibre-reinforced composi…
Online Solid-Phase Extraction LC-MS/MS: A Rapid and Valid Method for the Determination of Perfluorinated Compounds at Sub ng·L-1Level in Natural Water
2018
In this research paper, we report a method able to detect perfluorinated compound at pg·L−1 levels in superficial and underground water samples. An online solid phase extraction HPLC-MS/MS method was developed for the analysis of 12 perfluoroalkyl acids (PFASs). The method is based on injection of 5000 µL of water sample in SPE online WAX column followed by chromatography separation and mass spectrometry determination. SPE online elution was performed by water + 0.05% NH4OH and methanol + 0.05% NH4OH, while separation of target compounds was achieved within 10 min by Gemini chromatographic column operating from 1 to 12 pH range and using a mixture of water-methanol + 0.05% NH4OH. Sub ng·L−1…
The implication of omega-3 polyunsaturated fatty acids in retinal physiology
2007
International audience; Neuronal tissues such as the retina and the brain are characterized by their high content in phospholipids. In the retina, phospholipids can account for until 80% of total lipids and are mainly composed by species belonging to phosphatidyl-choline and phosphatidyl-ethanolamine sub-classes. Within fatty acids esterified on retinal phospholipids, omega-3 PUFAs are major components since docosahexaenoic acid (DHA) can represent until 50% of total fatty acids in the photoreceptor outer segments.For long time, DHA is known to play a major role in membrane function and subsequently in visual processes by affecting permeability, fluidity, thickness and the activation of mem…
Testing Soil Encasing Materials for Measuring Hydraulic Conductivity of a Sandy-Loam Soil by the Cube Methods
2008
The Cube Method (CM) and the Modified Cube Method (MCM) were developed for measuring vertical (K v ) and horizontal (K h ) saturated hydraulic conductivity of a single soil sample. By these methods, a cube of soil is carved out in situ and a suitable material is applied to enclose the cube in a tightly fitting casing before moving the sample to the laboratory. Problems may be associated with the use of gypsum, originally used to encase soil. The suitability of molten wax and expandable polyurethane foam to encase a soil cube was tested for a sandy-loam soil. Wax-treated samples yielded lower conductivity results than untreated samples by a maximum factor of 3.7. The observed discrepancies w…