Inhibitory Effect of Ethanolic Extract of Propolis on Corrosion of Ferritic Stainless Steel in Chloride Media

This work evaluates the inhibitory effect of ethanolic extract of propolis (EEP) on the corrosion of AISI 409 stainless steel (SS) in chloride media. Additions of 100, 200, and 500 μL of EEP in an aqueous sodium chloride solution were performed. The inhibitory effect on the SS was evaluated using electrochemical impedance spectroscopy (EIS) measurements up to 720 hours in immersion. EEP additions of 200 μL and 500 μL increased the polarization resistance of the SS. After 720 hours of immersion, the highest impedance was identified for the SS in solution with 500 μL of EEP. The maximum inhibition efficiency observed for addition of 500 μL of EEP in solution was 98.1 %, after 360 h of immersion. This work is licensed under a Creative Commons Attribution 4.0 International License

TiO2 Sol-gel Coating as a Transducer Substrate for Impedimetric Immunosensors

Given the importance of the transducer elements in the performance of sensors for various applications, as well as the growing search for devices that are capable of providing the response in shorter time, in this work, titanium dioxide was examined as a candidate for application in an electrochemical biosensor. A TiO2 coating deposited by sol-gel method on a silicon wafer was obtained with an anatase crystalline structure, as an n-type semiconductor with donor density equal to 2.954 · 1017 cm–3. Its surface was functionalized to be tested as a biosensor to detect snake venom of the Bothrops genera, and each step of the functionalization was investigated using Electrochemical Impedance Spectroscopy (EIS) and Cyclic voltammetry. Despite being less sensitive than the reference method ELISA, the TiO2-based biosensor was also capable of detecting the analyte of interest at 20 μg mL–1, revealing an increase in its leakage resistance and phase shift after incubation in this solution. Furthermore, the total time for carrying out the biodetection with the TiO2-coated device (41.24 ± 0.05 min) was estimated to be approximately 80 % shorter than that required by the labelled standard assay, which indicates that TiO2 is a promising electrochemical transducer for biosensing applications. This work is licensed under a Creative Commons Attribution 4.0 International License

Safety and immunomodulatory effects of three probiotic strains isolated from the feces of breast-fed infants in healthy adults: SETOPROB study

We previously described the isolation and characterization of three probiotic strains from the feces of exclusively breast-fed newborn infants: Lactobacillus paracasei CNCM I-4034, Bifidobacterium breve CNCM I-4035 and Lactobacillus rhamnosus CNCM I-4036. These strains were shown to adhere to intestinal mucus in vitro, to be sensitive to antibiotics and to resist biliary salts and low pH. In the present study, a multicenter, randomized, double-blind, placebo-controlled trial with 100 healthy volunteers in three Spanish cities was carried out to evaluate the tolerance, safety, gut colonization and immunomodulatory effects of these three probiotics. Volunteers underwent a 15-day washout period, after which they were randomly divided into 5 groups that received daily a placebo, a capsule containing one of the 3 strains or a capsule containing a mixture of two strains for 30 days. The intervention was followed by another 15-day washout period. Patients did not consume fermented milk for the entire duration of the study. Gastrointestinal symptoms, defecation frequency and stool consistency were not altered by probiotic intake. No relevant changes in blood and serum, as well as no adverse events occurred during or after treatment. Probiotic administration slightly modified bacterial populations in the volunteers’ feces. Intestinal persistence occurred in volunteers who received L. rhamnosus CNCM I-4036. Administration of B. breve CNCM I-4035 resulted in a significant increase in fecal secretory IgA content. IL-4 and IL-10 increased, whereas IL-12 decreased in the serum of volunteers treated with any of the three strains. These results demonstrate that the consumption of these three bacterial strains was safe and exerted varying degrees of immunomodulatory effects.Part of the research currently in progress in the authors' laboratory is funded by the company Hero Spain, S. A. through the grant #3582 managed by the Fundacion General Empresa-Universidad de Granada

Electrochemical impedance spectroscopy studies for chemically prepared poly(o-methoxyaniline) doped with functionalized acids

Poly(o-methoxyaniline) was prepared by the chemical oxidation of the monomer with ammonium peroxydisulfate in the presence of the following acids: hydrochloric, p-toluenesulfonic, dodecylbenzenosulfonic and dodecylsulfuric. The polymers obtained are soluble in dimethylformamide and this enabled the preparation of films by casting. The electrochemical behavior of the polymers prepared by chemical synthesis is very similar to polyaniline prepared by electrochemical methods. Impedance spectroscopy measurements indicated that the acid affects mainly the potential range where the charge transfer resistance is lower. The diffusion coefficients obtained by impedance spectroscopy are higher for poly(o-methoxyaniline) doped with chloridric and p-toluene sulfonic acids than for those doped with dodecylbenzenosulfonic and dodecylsulfuric acids. (C) 1997 Elsevier Science Ltd.434179545746

IONIC EXCHANGES IN DODECYLBENZENESULFONATE-DOPED POLYPYRROLE .2. ELECTROCHEMICAL QUARTZ-CRYSTAL MICROBALANCE STUDY

Cyclic voltammetry and electrochemical quartz crystal microbalance techniques were combined to study the ionic exchange process in polypyrrole doped with the anionic surfactant, dodecylbenzenesulfonate. A quantitative analysis of the results indicates a doping degree of 20% after dectropolymerization. Studies performed in monomer-free solutions show that both anions and cations of the electrolytes play an important role in the redox process. Quantitative calculations also take into account the transfer of neutral species like solvent molecules.72328328

Thermal, Mechanical And Electrochemical Behaviour Of Poly(vinyl Chloride)/ Polypyrrole Blends (pvc/ppy)

The conductivity, thermal, mechanical and electrochemical properties of poly(vinyl chloride)/polypyrrole blends are described in this paper. These blends were prepared by oxidative chemical polymerization of pyrrole, in the vapour phase, in PVC films impregnated with FeCl3. They were characterized by attenuated total reflectance FT i.r. spectra, differential scanning calorimetry and dynamic-mechanical analysis. Infrared reflectance spectra suggested that the polymerization occurs preferentially on the matrix surface producing sandwich-type structures. The mechanical, thermal and conducting behaviour showed a dependence on (1) initial concentration of FeCl3 in the matrix and (2) exposition time to pyrrole vapour. By cyclic voltammetry we observe that blends synthesized by oxidative chemical polymerization show electrochemical properties similar to blends prepared by electrochemical methods. Their conductivity varies from 10-4 to 10-1 S cm-1. Dynamic-mechanical analysis results suggest a certain degree of miscibility among the polymeric components of the blend. Copyright © 1996 Elsevier Science Ltd.372351655170Diaz, A.F., Kanazawa, K.K., (1979) J. Chem. Soc., Chem. Commun., p. 635Peres, R.C.D., Pernaut, J.M., De Paoli, M.-A., (1991) J. Polym. Sci.: Part A: Polym. Chem., 29, p. 225De Paoli, M.-A., Waltman, R.J., Diaz, A.F., Bargon, J., (1985) J. Polym. Sci. Polym. Chem. Ed., 23, p. 1687Bi, X., Pei, Q., (1987) Synth. Met., 22, p. 145Chen, Y., Qian, R., Li, G., Li, Y., (1991) Polym. Commun., 32, p. 189Zinger, B., Kijel, D., (1991) Synth. Met., 41-43, p. 1013Wang, H.L., Toppare, L., Fernandez, J.E., (1990) Macromolecules, 23, p. 1053Pron, A., Zagorska, M., Fabianovski, W., Raynor, J.B., Lefrant, S., (1987) Polym. Commun., 28, p. 193Ueno, T., Arntz, H.-D., Flesch, S., Bargon, J., (1988) J. Macromol. Sci.-chem., A25, p. 1557Kang, T.J., Miyata, S., Miyaki, T., (1993) Polym. Bull., 31, p. 593Nakata, M., Kise, H., (1993) Polym. J., 25, p. 91Olmedo, L., Hourquebie, P., Jousse, F., (1993) Adv. Mater., 5, p. 373Ferreira, C.A., Aeiyach, S., Delamar, M., Lacaze, P.C., (1990) J. Electroanal. Chem., 284, p. 351Niwa, O., Kakuchi, M., Tamamura, T., (1987) Macromolecules, 20, p. 749Quintas, M.C., Mano, V., Felisberti, M.I., De Paoli, M.-A., (1992) Proc. Simposio Iberoamericano de Polimeros, p. 141. , VigoMano, V., Felisberti, M.I., De Paoli, M.-A., Macromolecules, , submittedNiwa, O., Kakuchi, M., Tamamura, T., (1987) Polym. J., 19, p. 1293Mano, V., Felisberti, M.I., De Paoli, M.-A., (1993) Proc. 2° Congresso Brasileiro de Polimeros, p. 578. , São PauloAbrantes, L.M., Mesquita, J.C., Kalaji, M., Peter, L.M., (1991) J. Electroanal. Chem., 307, p. 275Diaz, A., (1981) Chem. Scripta, 17, p. 145Uosaki, K., Okazaki, K., Kita, H., (1990) J. Polym. Sci, Polym. Chem. Ed., 28, p. 399Diaz, A.F., Bargon, J., (1986) Handbook of Conducting Polymers, 1, p. 81. , Ed. T. A. Skothein, Marcel Dekker, New Yor