Tranchage et prolongement des courants positifs fermés

Sans résumé Re?u le 11 octobre 1995 / Version revisée re?ue le 20 fevrier 1996     

First and Second Order Convex Sweeping Processes in Reflexive Smooth Banach Spaces

In this paper we establish new characterizations of the normal cone of closed convex sets in reflexive smooth Banach spaces and then we use those results to prove the existence of solutions for first order convex sweeping processes and their variants in reflexive smooth Banach spaces. The case of second order convex sweeping processes is also studied.     

Deprotometalation-Iodolysis and Direct Iodination of 1-Arylated 7-Azaindoles: Reactivity Studies and Molecule Properties

Five protocols were first compared for the copper-catalyzed C-N bond formation between 7-azaindole and aryl/heteroaryl iodides/bromides. The 1-arylated 7-azaindoles thus obtained were subjected to deprotometalation-iodolysis sequences using lithium 2,2,6,6-tetramethylpiperidide as the base and the corresponding zinc diamide as an in situ trap. The reactivity of the substrate was discussed in light of the calculated atomic charges and the pK_a values. The behavior of the 1-arylated 7-azaindoles in direct iodination was then studied, and the results explained by considering the HOMO orbital coefficients and the atomic charges. Finally, some of the iodides generated, generally original, were involved in the N-arylation of indole. While crystallographic data were collected for fifteen of the synthesized compounds, biological properties (antimicrobial, antifungal and antioxidant activity) were evaluated for others.     

On a solvable system of p difference equations of higher order

Periodica Mathematica Hungarica - In this paper we present the well-defined solution of the following system of higher-order rational difference equations: $$\begin{aligned}...     

State Dependent Sweeping Process in p-Uniformly Smooth and q-Uniformly Convex Banach Spaces

We prove the existence of solutions for the state depending convex sweeping processes in p-uniformly smooth and q-uniformly convex Banach spaces via new recent results on proximal analysis in reflexive smooth Banach spaces.     

Photocatalytic Degradation of Oxytetracycline in Aqueous Solutions with TiO2 in Suspension and Prediction by Artificial Neural Networks

In this study, the photocatalytic degradation of oxytetracycline (OTC) in aqueous solutions has been studied under different conditions such as initial pollutant concentrations, amount of catalyst, and pH of the solution. Experimental results showed that photocatalysis was clearly the predominant process in the pollutant degradation, since OTC adsorption on the catalyst and photolysis are negligible. The optimal TiO₂ concentration for OTC degradation was found to be 1.0 g/L. The apparent rate constant decreased, and the initial degradation rate increased with increasing initial OTC concentration with the other parameters kept unchanged. Subsequently, data obtained from photocatalytic degradation were used for training the artificial neural networks (ANN). The Levenberg–Marquardt algorithm, log sigmoid function in the hidden layer, and the linear activation function in the output layer were used. The optimized ANN structure was four neurons at the input layer, eighteen neurons at the hidden layer, and one neuron at the output layer. The application of 18 hidden neurons allowed to obtain the best values for R² and the mean squared error, 0.99751 and 7.504e–04, respectively, showing the relevance of the training, and hence the network can be used for final prediction of photocatalytic degradation of OTC with suspended TiO₂.     

Validation of gravimetry for high-accuracy analysis of uranium

Journal of Radioanalytical and Nuclear Chemistry - Gravimetry after calcination is an assay method for determining the quantity of a given element from the mass measurement. This method, adapted...     

Chemical variability of essential oils in natural populations of Cupressus dupreziana

Essential oils extracted from dried leaves of Cupressus dupreziana A. Camus, an endemic species in the Tassili n'Ajjer (Central Sahara of Algeria), were analyzed by gas chomatography coupled to mass spectrometry (GC-MS). Analyses were carried out on 164 trees of 26 natural populations in order to determine the intra-specific variability. Thirty-two terpenoids were identified, the major ones being alpha-pinene (11.5-44.2), delta3-carene (5.7-31.7) and germacrene-D (15.7-54.1). The terpenoid markers used made it possible to determine the individual patterns of chemotypic variability. This variability confirmed that genetic factors were not responsible for the decrease in the number of this species, the main reason probably being the Tassili n'Ajjer desertification.     

Thin‐layer chromatography‐bioautographic method for the detection of arginase inhibitors

Arginase represents a promising therapeutic target for various pathologies including inflammatory, cardiovascular, and parasitic diseases or cancers. In the current work, we report, for the first time, about the development of a thin‐layer chromatography‐based bioautography which can be used to rapidly detect arginase inhibitors in complex matrices such as plant extracts. The assay is based on the detection of urea produced by arginase using the coloring reagent α‐isonitrosopropiophenone, resulting in the formation of a pink background on thin‐layer chromatography plates. The assay conditions were optimized in order to provide sufficient contrast between the pink colored thin‐layer chromatography plate and the clearer zones generated by the presence of arginase inhibitors. Different parameters were tested, such as incubation time and temperature, atmospheric conditions, as well as substrate and enzyme concentrations. This technique makes it possible to detect 0.1 μg of a known arginase inhibitor, N^ω‐hydroxy‐nor‐Arginine, after it has been spotted, either pure or mixed with a Myrtus communis methanolic fruit extract, and the plate has been developed in an appropriate solvent. The newly developed method was used to reveal the presence of an inhibitor in hempseed cakes (Cannabis sativa L.).     

Multistep deposition of Cu2Si(S,Se)3 and Cu2ZnSiSe4high band gap absorber materials for thin film solar cells

Cu₂ZnSi(S,Se)₄ and Cu₂Si(S,Se)₃ are potential materials to obtain cost effective high band gap absorbers for tandem thin film solar cell devices. A method to synthesize Cu₂SiS₃, Cu₂SiSe₃and Cu₂ZnSiSe₄thin film absorbers is proposed. This method is based on a multistep process, using sequential deposition and annealing processes. X‐ray diffraction analysis performed on the final thin films have confirmed the presence of the Cu₂Si(S,Se)₃ and Cu₂ZnSiSe₄phases. Scanning electron microscopy images revealed the formation of polycrystalline layers with grains size up to 1 µm. The band gap of the ternary Cu₂SiSe₃ and Cu₂SiS₃, and quaternary Cu₂ZnSiSe₄ based thin films as determined from optical and photoluminescence measurements are found to be close to their theoretical values. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)