An electrochemical sensor based on TiO2/activated carbon nanocomposite modified screen printed electrode and its performance for phenolic compounds detection in water samples

Herein, we reported a titanium oxide (TiO₂) modified activated carbon nanocomposite that showed advantageous characteristics in terms of electro-conductivity, catalytic activity and surface area. The designed nanocomposite was employed to modify the screen printed carbon electrode transducer surface in the construction of an electrochemical sensor. The electrode surface modification was characterised by cyclic voltammetry and impedimetric studies. The modified transducer surface was subsequently used for the detection of four phenolic endocrine disruptors, p-nitrophenol, hydroquinone, catechol and 1-naphtol. Under optimal conditions, TiO₂ modified activated carbon sensor was evaluated by differential pulse voltammetry showing a good linearity with correlation coefficients higher than 0.99. It showed, in parallel, a high sensitivity where the detection limits were 348 ng/L, 110.1 ng/L, 3.3 ng/L and 7.2 µg/L for the respective studied compounds (S/N = 3). Finally, we validated the method with river water samples, and good recovery values were obtained showing the potential application of the reported biosensor.     

Mutagenic, antimutagenic and antioxidant activities of a new class of beta-glucoside hydroxyhydroquinone from Anagallis monelli growing in Tunisia

A new skeleton of an O-heteroside natural substance named zinolol, the first representative of a new class of aminated hydroxyhydroquinone, has been isolated from the whole plant Anagallis monelli. Its structure has been established by one and two dimensional NMR spectroscopic procedures. Antioxidant, mutagenic, antimutagenic activities were realised and positive results were recorded.     

Chains in Critical Fluids and Nanopores

Summary: The conformational behavior of a polymer in a critical binary solvent confined in a porous medium is studied. The size of the polymer in bulk, which is mainly governed by the correlation length of the solvent density fluctuations, depends on the proximity to the critical point of the binary mixture. We find that in contrast to the bulk behavior, the conformational properties of the polymer in a porous medium depends strongly on the pore size. The latter controls the correlation length of the solvent density fluctuations and thus determines the polymer size.     

The interference wave and the bright and dark soliton for two integro-differential equation by using BNNM

Interference wave is an important research target in the field of navigation, electromagnetic and earth science. In this work, the nonlinear property of neural network is used to study the interference wave and the bright and dark soliton solutions. The generalized broken soliton-like equation is derived through the generalized bilinear method. Three neural network models are presented to fit explicit solutions of generalized broken soliton-like equations and Boiti–Leon–Manna–Pempinelli-like equation with 100% accuracy. Interference wave solutions of the generalized broken soliton-like equation and the bright and dark soliton solutions of the Boiti–Leon–Manna–Pempinelli-like equation are obtained with the help of the bilinear neural network method. Interference waves and the bright and dark soliton solutions are shown via three-dimensional plots and density plots.

     

Characterization of acid-base properties of polymers and other materials: relevance to adhesion science and technology

This paper reviews the background to the theory of Lewis acid-base (AB) interactions in adhesion, adsorption, wetting and mixing of polymers and other materials (pigments, fillers, fibres, etc.). These specific materials interactions require the revision of old concepts («polar» interactions) and the development of new analytical techniques and methodologies. Four of the most currently used techniques to characterize AB interactions are described: contact angle measurements, inverse gas chromatography. X-ray photoelectron spectroscopy, and atomic force microscopy.     

A comparative study of the behavior of cyanothioformamide and oxazolidine (thiones or iminothiones) towards some binucleophiles

Reactions of cyanothioformamides ( I ) with o‐phenylenediamines, o‐aminophenol, and anthranilic acids furnished benzimidazole ( II,III ), benzoxazole ( VII ), and quinazoline ( IX ) derivatives, respectively. Oxazolidine (thiones or iminothiones) ( IV ) were reacted with the same binucleophiles to produce quinoxaline ( V ), benzimidazole ( VI ), and quinazoline ( XI ) derivatives. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:291–298, 2002; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/hc.10031     

Chemical composition and antioxidant activity of Borago officinalis L. leaf extract growing in Algeria

The aqueous and hydroalcoholic extracts of borage (Borago officinalis) leaves from Annaba region (Algeria) were preliminary analyzed for their phenolic profile (total phenolics, total flavonoids, total flavonols, total tannins and total anthocyanins). These extracts were evaluated for their antioxidant properties by different methods such as DPPH radical scavenging, test NBT and total antioxidant activity. The two extracts have exhibited a high antiradical capacity. Indeed, the ethanolic extract showed the lower IC50 values and the highest amount of phenolics (94.09 ± 1.72 mg gallic acid/g dry extract). Using LC-MS/MS analysis, it was possible to identify phenolic acids, flavonoids, sterol and for the first time oleuropein was identified in the aqueous extract of the plant. The obtained results have demonstrated that phenolic compounds are the major contributor to the antioxidant activity of plants.