Chitosan-Based Materials for the Removal of Nickel Ions from Aqueous Solutions

Russian Journal of Physical Chemistry A - Sorption of Ni(II) ions from liquid effluents utilizing chemically modified chitosan; (vanillin, polymer I) and (ortho-vanillin, polymer II) is studied...     

Novel synthesis of 3-cyano-2-pyridones derivatives catalyzed by Au–Co/TiO2

Research on Chemical Intermediates - The current work described a new and highly selective method for the synthesis of substituted 3-cyano-2-pyridones scaffolds using gold-cobalt supported on TiO2...     

Tuning the morphological properties of cellulose aerogels: an investigation of salt-mediated preparation

Cellulose - In this study, alkali and alkaline earth metal chlorides with different cationic radii (LiCl, NaCl, and KCl, MgCl2, and CaCl2) were used to gain insight into the behavior of cellulose...     

Polymethylmethacrylate derivatives Eudragit E100 and L100: Interactions and complexation with surfactants

Precipitation or coprecipitation of polyelectrolytes has been largely investigated. However, the precipitation of polyelectrolytes via addition of charged and non‐charged surfactants has not been systematically studied and reported. Consequently, the aim of this work is to investigate the effect of different surfactants (anionic, cationic, non‐charged and zwitterionic) on the precipitation of cationic and anionic polymethylmethacrylate polymers (Eudragit). The surfactants effect has been investigated as a function of their concentration. Special attention has been dedicated to the CMC range and to the colloidal characterization of the formed dispersions. Moreover, the effect of salt (NaCl) and pH was also addressed. It is pointed out that non‐ionic and zwitterionic surfactants do not interact with charged Eudragit E100 and L100. For oppositely charged Eudragit E100/SDS and Eudragit L100/CTAB, precipitation occurs, and the obtained dispersions have been characterized in terms of particle size distribution and zeta potential. It was established that the binding of SDS molecules to Eudragit E100 polymer chains is made through the negative charges of the surfactant heads under the CMC value whereas binding of CTAB to Eudragit L100 chains is made at a CTAB concentration 5 times above its CMC. For Eudragit E100/SDS system, a more acidic medium induces aggregation. A same result was observed for the Eudragit L100/CTAB at a more basic pH. Moreover, it was observed that increasing salt concentration (higher than 100 mM) led to aggregation as generally observed for polycations/anionic surfactant systems.     

A printed SWCNT electrode modified with polycatechol and lysozyme for capacitive detection of α-lactalbumin

The authors describe an electrochemical sensor for the breast cancer marker α-lactalbumin (αLA). It is based on the use of printed single-walled carbon nanotube (SWCNT) electrodes that were modified with polycatechol. Impedance-derived electrochemical capacitance spectroscopy (ECS) is applied for detection at an applied potential of ?0.14 V vs. Ag/AgCl reference electrode. The electrode was prepared in a two-step process. First, a dispersion of SWCNTs was drop-cast onto the surface of a poly(ethylene terephthalate) substrate to act as the working electrode. Next, catechol was electrochemically polymerized on the SWCNTs, prior to the immobilization of lysozyme. The strong interaction between lysozyme and αLA induced changes in the redox capacitance which are detected by ECS. The latter shows the device to be capable of detecting αLA in the 20 to 80 ng·mL^?1 concentration range. The limit of detection is 9.7 ng·mL^?1 at an S/N ratio of 3. The device was used to detect αLA in human blood serum with good recovery results.

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Graphical abstract A sensitive biosensor for αLA was prepared by modifying SWCNT electrode with polycatechol and lysozyme. The electrochemical capacitance spectroscopy was used for the first time to selectively detect αLA in the blood in the range from 20 to 80 ng·mL^?1.

     

Synthesis,design of experiments and optimization of heterogeneous Fenton-like degradation of tartrazine by MgFe2O4 nano-catalyst

In this work, magnesium ferrites nanoparticles (MgFe₂O₄ NPs) were successfully fabricated by sol-gel auto-combustion (SGAC) method and were used in heterogeneous Fenton-like degradation of tartrazine. The obtained products were characterized using XRD, FTIR, SEM and EDX. XRD studies confirmed that the synthesized MgFe₂O₄ NPs had a cubic spinel structure. The average crystallite size was evaluated using the Debyee Scherrer formula and found to be in the range 16.18–28.55 nm. In FTIR spectra, two primary absorption bands at 571 cm^?1 and 415 cm^?1 were observed. The spinel ferrites are characterized by these bands and the EDX confirms the presence of the desired elements Mg, Fe, and O. The influences of operating parameters were examined using the Box Behnken statistical design (BD), including magnesium ferrite dosage (0.04–0.12 g/L), tartrazine concentration (30–50 mg/L) and H₂O₂ concentration (3.53–7.06 mM). Using analysis of variance, a significant quadratic model was created. Optimum conditions were magnesium ferrite dosage of 0.092 g/L, tartrazine concentration of 30.21 mg/L and H₂O₂ concentration of 6.66 mM, respectively. The predicted degradation efficiency within the optimum conditions as established by the suggested model was 98.4%. Confirmatory tests were carried out and the degradation efficiency of 98.9% was observed, which was in good agreement with the model's prediction. After five recuperation and reapplications, the catalyst's degradation efficiency remains stable. These findings indicate that a heterogeneous Fenton-like process utilizing MgFe₂O₄ is effective in advanced wastewater treatment.     

Synthesis,characterization and antioxidant,antibacterial activity Zn2+, Cu2+, Ni2+ and Co2+, complexes of ligand [2-(thiophen-2-yl)-1-(thiophen-2-ylmethyl)-1H-benzo[d]imidazole]

New metal complexes of (Zn(II), Co(II), Ni(II) and Cu(II)) based on the ligand 2-(thiophen-2-yl)-1-(thiophen-2-ylmethyl)-1H-benzo[d]imidazole] were synthesized, whose structures were determined with the different spectroscopic techniques ¹H NMR,¹³C NMR, FT-IR, UV–Visible and by mass spectrometry. The thermal analysis was performed by TG-DTA. The antioxidant activity of the ligand and its complexes was evaluated by DPPH (2,2-diphenyl-1-picrylhydrazyl) method, in comparison with the synthetic antioxidant, ascorbic acid. The results obtained showed that the antioxidant activity of the ligand and its complexes is moderate and that the copper complex has a high activity that exceeds that of ascorbic acid. Antimicrobial activity of the ligand and its metal complexes was studied against two Gram-positive bacteria: Bacillus subtilis ILP1428B, Staphylococcus aureus CIP543154 and two Gram-negative bacteria: Pseudomonas aeruginosa ATCC27653, Escherichia coli CIP5412 (American Type Culture Collection)the activity data show that the metal complexes are more potent than the free ligand.     

Averaging and periodic solutions in the plane and parametrically excited pendulum

We first approximate the solutions of the nonautonomous oscillating suspension point pendulum equation by the solutions of a second order autonomous differential equation. Using the strict monotonicity of the periodic solutions of the approximating equation, we prove the existence of a large number of subharmonic periodic solutions of the plane pendulum when its point of suspension is excited parametrically.     

Continuum modeling for the modulated vibration modes of large repetitive structuresModèle continu pour les modes de vibrations modulés des longues structures répétitives

By homogenization theory, one can predict the vibrations of long repetitive structures in the low frequency range. Beyond this range, many modes have a modulated shape. Based on a multiple scale analysis, a continuum model is presented, that is able to account for this class of modes. This model involves a real coefficient that can be computed from the finite element resolution of problems defined on a few basic cells. An application in 2D elasticity is presented. To cite this article: E.M. Daya et al., C. R. Mecanique 330 (2002) 333–338.