Butterfly Valves - How to Estimate Cavitation Level and Related Damage on Existing Locks and at the Laboratory?

The butterfly valves (3.5m diameter) of the new lock of Lanaye (Albert canal Belgium) are submitted to cavitation during the levelling. On site measurements were realised to characterize the cavitation and to optimize the opening law of the valves in order to decrease the intensity and duration of cavitation. For comparison, measurements were realised in an existing lock with similar valves which are also submitted to cavitation but don’t present any associated damages since 1960. The duration of cavitation is more or less the same for both locks, but the cavitation intensity is more important in Lanaye. To check the appearance of eventual damages, annual monitoring of the valves is realised. Some small damages were observed but the link with cavitation is not obvious. In parallel, at the laboratory, the efficiency of aeration provided around the valve is tested for different configurations. The sound and the vibrations due to cavitation are reduced when aeration is provided. Tests realised on a pipe coated with Aluminium indicates that the damages are mainly located downstream of the valve on the upper part of the pipe. These tests confirm that aeration is appropriate to reduce the damages induced by cavitation

Modulation of metallic oxide particle behaviour in a formulation: physicochemical and/or sensory properties of emulsions as a tool to identify particles interactions within the matrix

International audienceParticles of metal oxides such as silica (SiO2), alumina (Al2O3) or titanium dioxide (TiO2) are nowadays widely used in manufactured products. The interest of these solid particles lies in the possibility tovary their size (a few nanometers to several micrometers), their shape, and their state of aggregation, as well as their specific surface. In addition, these metal oxides are good candidates for surface modification (coating with other metal oxides, silanization) to also modulate their surface properties [1-2].Thus, incorporated in a complex medium such as an emulsion, these solid particles, due to their varied physicochemical properties, will be able to interact with all the constituents of the matrix. This represents asubject of great scientific interest, from both applied and fundamental point of view. Depending on its surface properties, the particle can manifest more affinity with the continuous phase, the dispersedone, or can be placed at the interface [3]. In the latter situation, the particle can act as a surfactant and can even replace the molecular surfactants conventionally used.The aim of this study lays on its multiscale approach: from microscopic scale through the investigation of the ingredients interactions (guided by the type of particle used) to macroscopic scale with the characterization of stable, homogeneous and totally emulsified systems (as it was a required condition to provide an adapted system for macroscopic evaluations). Rheological, textural and sensory behavior, as well as emulsion colloid size and size distribution, were used as a tool to identify the role of the particles on the matrix organization.One objective was to find the emulsions optimal formulation process and composition to accomplish the desired requirements for this study.The obtained results clearly showed the importance of the particle properties in emulsion formation and stabilization. Interactions created inside the matrix were governed by the specific surface andthe coating type of the particles. Thus, the modulation of the emulsion can be possible relying on the particle/emulsifier/oil phase interaction and ratio.[1] S. Björkegren, L. Nordstierna, A. Törncrona and A. Palmqvist, Journal of Colloid and Interface Science, 2017, 487, 250.[2] C. Picard, A. Larbot, E. Tronel-Peyroz and R. Berjoan, Solid State Sciences, 2004, 6, 605.[3] B. P. Binks, Current Opinion in Colloid & Interface Science, 2002, 7, 21

Photochemistry and Radical Chemistry under Low Intensity Visible Light Sources: Application to Photopolymerization Reactions:

The search for radical initiators able to work under soft conditions is a great challenge, driven by the fact that the use of safe and cheap light sources is very attractive. In the present paper, a review of some recently reported photoinitiating systems for polymerization under soft conditions is provided. Different approaches based on multi-component systems (e.g., photoredox catalysis) or light harvesting photoinitiators are described and discussed. The chemical mechanisms associated with the production of free radicals usable as initiating species or mediators of cations are reported

Boundary conditions in a two-layer geomorphological model. Application to a hydraulic jump over a mobile bed

The one-dimensional numerical model presented in the present paper divides the flow in two fully coupled layers, a water layer and a water-sediment transport layer. Initially, this model was used to depict dam-break flows, which do not require a specific treatment of boundary conditions. The aim of the present research is to extend the model to fluvial flows requiring an appropriate boundary condition treatment. This treatment commonly relies on characteristics. However, in the frame of a two-layer model with five equations, those characteristics are not obvious to determine. This paper shows, how to extend numerically the common eigenstructure analysis to address the problem. Examples are presented and the boundary conditions treatment is illustrated on the particular case of a hydraulic jump over a mobile bed. Results of the numerical model including the adequate boundary conditions are favourably compared to experimental results

Characterisation of spreading and penetration of ingredients used in cosmetic emulsions

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Impact of emollients on the spreading properties of cosmetic products: A combined sensory and instrumental characterization

International audienceThis study deals with the impact of emollients on the spreading properties of cosmetic products using a combined sensory-instrumental approach. To that purpose, three esters and one silicone were selected and incorporated separately into an oil phase. Different cosmetic o/w emulsions were then prepared with these different oil phases. Both of them were analyzed by instrumental techniques and in vivo sensory analyses. A significant effect of the emollient used was established in emulsions and in oil phases as well. Concerning emulsions, results reveal a clear correlation between in vivo spreading evaluation and friction coefficient parameters measured by texture analyzer, despite a fairly low correlation coefficient (Pearson coefficient = −0.78). Concerning oil phases, characterization of spreading was done by monitoring the contact angle relaxation of a drop of solution after deposition on a flat PMMA surface whereas sensory procedure was based on spontaneous spreading of oil phases onto the skin. Finally, good correlations between in vivo sensory analysis and instrumental measurements of both oils and emulsions were found, thus promising the possible development of predictive tools to evaluate spreadability

Spreading behavior of cosmetic emulsions Impact of the oil phase

International audienceBackground Emollients are an important ingredient in personal care products, they are currently prescribed in skin disorders like eczema, which affects up to 30% of children in developed countries. Methods The aim of the study was to investigate the impact of two emollients (stearic acid and isohexadecane) and their mixtures in the spreadability and frictional effect on films obtained from oil-in-water emulsions. Rheological, textural, sensory and tribological analysis were performed on human skin and artificial substrates. Results The emollients ratio influences the spreading behavior of emulsions more isohexadecane in the oil phase easier to spread the product on the skin. Moreover, significant correlations were obtained for the spreading behavior obtained by textural measurements on artificial substrates and sensory analysis (Pearson coefficient = −0.871). The results obtained by frictiometer showed different developments over time after product application the friction values increase with the stearic acid concentration in emulsion. Discussion This study showed the importance to consider the emollient properties when one emollient is used in the emulsion, but especially their interactions, when several emollients are used, to better understand and anticipate their behavior. First, spreading was governed by the consistency of the emulsion, particularly impacted by the emollients ratio. But then, in a long-time spreading, when the emulsion broke down and residual film was formed, a particular interaction with skin influenced the spreadability. It appears that not only the physical state of the emollient but also its chemical nature, physical state, polarity, temperature might explain these phenomena. © 2018 Elsevier Lt

Cosmetics and personal care products

International audienceCosmetic and personal care products are complex mixtures intended to be applied to the external parts of the human body. In the long list of ingredients are included polymers which are either natural or synthetic. This chapter presents the main natural polymers used in cosmetics which are mainly polysaccharides and proteins obtained from vegetable, animal and biotechnology origins. The use of artificial polymers is discussed through the example of cellulose derivatives which are widely used for their physicochemical properties and cosmetic benefits. Natural polymers in cosmetics play many distinct roles; they can be chosen either to improve the stability of colloidal systems, to control the rheological properties from manufacturing to end-user or to achieve the sensory expectation and efficiency of the product during application. Natural polymers are thus multifunctional ingredients used in many different commodities sometimes alone, but more often in combination with synthetic polymers as illustrated through different examples including hair care, skin care or toothpaste products. Natural polymers own a growing place in the cosmetic field and this can be attributed to the ever increasing desire for ʼnaturality’. Their applicability in this field is further enhanced by their processibility and the multiple options possible to control properties through their chemical modifications. © Springer International Publishing Switzerland 2016

Innover en formulation cosmétique : outils de prédiction des propriétés tactiles

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