Kinetic study of silica gels by a new rheological ultrasonic investigation

Ehssein, Chighali; Serfaty, Sylvia; Griesmar, Pascal; Huerou, J.-Y. Le; Martinez, L.; Caplain, Emmanuel; Wilkie-Chancellier, Nicolas; Gindre, M.; Gouédard, G.; Figuiere, P.

doi:10.1016/j.ultras.2006.05.035

Cited by 24 publications

(13 citation statements)

References 16 publications

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“…Z load = R + j X is representative of these changes. The variation of the electrical response can then accurately extract G, using the following expression [32]. …”

Section: B Tsm Biosensor For Skin Characterizationmentioning

confidence: 99%

Ex vivo TSM online monitoring of skin dehydration

Besse¹,

Serfaty²,

Huerou³

et al. 2015

2015 Conference on Cosmetic Measurements and Testing (COMET)

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This study presents a new online skin investigation technique for tracking products-to-skin mechanical effects. Ex vivo abdominal skin explants from plastic surgery and kept alive are used for this study. Considering the skin as a complex fluid made of membrane and fiber structures immersed in liquid, its mechanical response of a bulk thickness shear wave excitation (i.e. stress-strain analysis) involves both a viscous component associated with energy dissipation and an elastic component associated with energy storage. A tight monitoring of these two components from the response of a TSM sensor (based on an AT cut quartz resonator at 5 MHz) in contact to the dermis of the ex vivo explant give us access to the complex dynamic shear moduli (G' and G") evolution of the skin; The appropriate mechanical model describing the sensor response vs. shear waves/matrix interactions allows investigating the impact of the product (or treatment) to the viscoelastic properties of the skin. The complex study of the TSM response in time domain permits a control a) of the dehydration evolution at 37°C due to interpenetrated intercellular lipid membranes matrix including the first step of permeation process from dermis to SC; b) the impact on the kinetics of the permeation process by a product applied at the SC surface. This information includes the structure and properties evolution of the collagen and elastic fibers and the proteoglycans located in the skin. A comparison of mechanical results with other techniques in the literature confirms the validity of the model. These preliminary results show that our TSM technique can be an appreciable new way for ex vivo skin investigation for test and optimization of new cosmetic products.

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“…Z load = R + j X is representative of these changes. The variation of the electrical response can then accurately extract G, using the following expression [32]. …”

Section: B Tsm Biosensor For Skin Characterizationmentioning

confidence: 99%

Ex vivo TSM online monitoring of skin dehydration

Besse¹,

Serfaty²,

Huerou³

et al. 2015

2015 Conference on Cosmetic Measurements and Testing (COMET)

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“…Acoustic wave sensors have already shown to be able to detect blood coagulation [17] and reversible thermal gelation of hydroxypropyl methylcellulose [18]. Although the potential of acoustic sensors to follow milk coagulation is known for some time [8,10], and they have been used to study casein micelles interaction after acidification in yoghurt production [19], applications are still scarce. In this paper, a piezoelectric quartz crystal was used to follow cow, ewe and goat milk coagulation since the very early stages, by monitoring the series frequency and the equivalent circuit resistance.…”

Section: Introductionmentioning

confidence: 99%

Using acoustic wave sensors to follow milk coagulation and to separate the cheeses according to the milk origin

Pais

Verı́ssimo

Oliveira

et al. 2015

Sensors and Actuators B: Chemical

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Optimum coagulation temperature and cutting time are usually empirically defined. The use of inexpensive acoustic wave sensors to monitor milk coagulation allows monitoring the process in real time, since its early stages. Besides, data are collected with minimum disturbance, which is an advantage over other methodologies, namely rheology. Coagulation of milk was followed by measuring both the frequency and equivalent circuit resistance of a piezoelectric quartz crystal. Three types of milk, ewe, goat and cow, were coagulated using different rennets at three different temperatures. Maximum observed coagulation rate, either with plant or animal rennet, increased with temperature both for ewe and goat milk. Maximum coagulation rate was higher with plant rennet than with animal rennet at 25 o C and 32 o C, while the opposite was found at 50 o C. The time needed to attain maximum coagulation rate was always smaller with ewe´s milk than with goat's milk, and maximum coagulation rate was higher with the former. Cow's milk was much more difficult to coagulate and needed twice the rennet quantity used for ewe and goat milk. Cheese obtained with the mentioned types of milk and different rennets shows different flavours, usually perceived by experts and connoisseurs, and that an electronic nose built in our laboratory was also able to distinguish. One sensor was enough to separate cheeses made from cow, ewe and goat milk. Besides, the addition of a second sensor allowed to separate the cheeses by rennet among the ones produced with the same milk.

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“…In the first part of this paper the investigation of the optimal reactants and conditions of compatibility between organic and inorganic polymerization is presented. To optimize the process, a monitoring of mesoscopic viscoelastic properties is performed using an ultrasonic technique developed in our laboratory. , The kinetic formation of the hybrid gel is presented for different TMOS/NIPAM (tetramethoxysilane) ratios. The different characteristics of synthesized gels are discussed.…”

Section: Introductionmentioning

confidence: 99%

One-Shot Synthesis of a Poly(N-isopropylacrylamide)/Silica Hybrid Gel

et al. 2009

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Class I hybrid poly(N-isopropylacrylamide)/silica hydrogels, PNIPAM/SiO2, were prepared by a new one shot synthesis. In this approach, the free-radical polymerization of vinyl groups of N-isopropylacrylamide (NIPAM) and the hydrolysis-condensation of alkoxy groups of tetramethoxysilane (TMOS) are performed concomitantly using sodium persulfate and 3-(dimethylamino)-propionitrile, a well-known couple to initiate the organic polymerization. The cross-linker is N,N-methylenebisacrylamide. The kinetic study of mechanical properties from the sol-to-gel state for different ratios of TMOS/NIPAM was investigated by rheological ultrasonic measurements. The thermoresponse of hybrid materials was investigated by differential scanning calorimetry and the measurements showed that hybrid gels present a lower critical solution temperature, which is similar with one of single organic hydrogel.

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Kinetic study of silica gels by a new rheological ultrasonic investigation

Cited by 24 publications

References 16 publications

Ex vivo TSM online monitoring of skin dehydration

Ex vivo TSM online monitoring of skin dehydration

Using acoustic wave sensors to follow milk coagulation and to separate the cheeses according to the milk origin

One-Shot Synthesis of a Poly(N-isopropylacrylamide)/Silica Hybrid Gel

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