Sodium sulfate crystallisation monitoring using IR Thermography

In this work, the evaporation of sodium sulfate droplets with different concentrations and at different temperatures were studied using infrared thermography (IRT). IRT allows to detect the evaporation evolution, the crystal growth and for the first time, to observe in vivo the heat release related to sodium sulfate crystallisation. A detailed study revealed that dendritic Thenardite III crystals appeared at the edge of all the crystallised droplets, though they showed a fast increase of temperature related to crystallisation only when a hydrated phase crystallised also from the droplet. The observation of the heat of crystallisation is thus directly related to the supersaturation of the droplet and consequently to temperature. In addition, IRT detection is circumscribed by the location of crystallisation. The heat can be observed and measured only when the crystallisation occurs in the interface solution – air

Non-destructive testing of works of art by stimulated by infrared thermography: PPT interest

Short abstract Within the framework of the cultural heritage conservation, stimulated infrared thermography has already demonstrated its efficiency. However, sometimes, the different colors of the paint layer can lead to artifacts of detection. In this work, we show theoretically and experimentally that the combination of a PPT analysis and of the stimulated infrared thermography allows a significant reduction of this disturbing optical effect

Stimulated infrared thermography applied to the local thermal characterization of fresco

Abstract In this work, we present a new method for estimating the local thermal diffusivity of fresco. This method uses a temporal analysis of the thermal response of a work of art submitted to a local laser excitation. First, we present the principle of the estimation method. Then, we show theoretically with the help of numerical simulations, the feasibility of the method. Finally, we show experimentally, that the method allows a good estimation of the thermal diffusivity of an academic plaster sample and of an academic fresco

Local thermal characterization of metal sample by stimulated infra-red thermography

In this paper, we consider the possibilities of the stimulated infra-red thermography for local metallic sample thermal characterization. At first we introduce the measurement principle, which is based on the local measurement of the thermal diffusivity parameter. Then, using simulations, we demonstrate the feasibility of the method. We then present the experimental device implemented for the study. Finally, we show that this approach allows a good estimation of the thermal diffusivity of a metal sample

Duvaut : Contribution to the local thermophysical characterization of murals paintings of the inheritance by stimulated infra-red thermography, proc of QIRT

Abstract The object of this work is to approach the possibilities of stimulated infrared thermography for in situ measurement of thermal diffusivity of mural paintings of the inheritance. We present first the principle of the method. We show then the feasibility of the measurement, using theoretical simulations. Finally, we show that the method allows a good estimation of the thermal diffusivity of a partial copy of the "Saint Christophe" of the Campana collection in the Louvre

Wavelet subspace decomposition of thermal infrared images for defect detection in artworks

International audienc

Phenolic compounds from an Algerian medicinal plant (: Pallenis spinosa): Simulated gastrointestinal digestion, characterization, and biological and enzymatic activities

Pallenis spinosa is a medicinal plant which is used in folk medicine as curative or preventive remedies for various diseases. Individual phenolic compounds from the methanolic extracts of its flowers, leaves and stem were determined by the high performance liquid chromatography method (HPLC) and total phenolic contents (TPC) were evaluated by Folin-Ciocalteu assay. The stability and bioactivity (antioxidant activity, micellar cholesterol solubility, α-amylase, and angiotensin converting enzymes (ACE) inhibitory effects) of these extracts in the gastrointestinal environment was determined before and after their protection in hydroxypropylmethylcellulose (HPMC) capsules. HPLC analysis revealed the presence of thirteen phenolic compounds with nine flavonoids and four phenolic acids. Except for kaempferol, the twelve other compounds have not been previously detected in the aerial part of the studied plant. Quantification of phenolics by HPLC and Folin Ciocalteu methods revealed that the highest TPC was detected in the flower extracts (104.31 ± 0.80 and 145.73 ± 0.48 mg EGA per g of extract, respectively). Leaf extracts displayed the best antioxidant capacity against the two tested radicals DPPH and ABTS (IC50 = 1.24 ± 0.03 and 0.94 ± 0.02 mg mL-1, respectively), FRAP assay (IC50 = 0.50 ± 0.02 mg mL-1), α-amylase inhibitory (IC50 = 1.25 ± 0.00 mg mL-1) and angiotensin activity with an inhibitory percent of 30.10 ± 0.12%. The best activity shown by stem extracts was against micellar cholesterol solubility (67.57 ± 0.00%). A strong decrease in TPC and their bioactivity was observed after the gastrointestinal digestion (GID) in non encapsulated extracts. These results showed that P. spinosa is a good source of phenolic compounds and GID affects significantly their composition, content and bioactivity