Publications

Abstract Mitochondria are cytoplasmic double-membraned organelles that are involved in a myriad of key cellular regulatory processes. The loss of mitochondrial function is related to the pathogenesis of several human diseases. Over the last decades, an increasing number of studies have shown that dietary polyphenols can regulate mitochondrial redox status, and in some cases, prevent or delay disease progression. This paper aims to review the role of four dietary polyphenols - resveratrol, curcumin, epigallocatechin-3-gallate nd quercetin - in molecular pathways regulated by mitochondria and their potential impact on human health. Cumulative evidence showed that the aforementioned polyphenols improve mitochondrial functions in different in vitro and in vivo experiments. The mechanisms underlying the polyphenols' beneficial effects include, among others, the attenuation of oxidative stress, the regulation of mitochondrial metabolism and biogenesis and the modulation of cell-death signaling cascades, among other mitochondrial-independent effects. The understanding of the chemical-biological interactions of dietary polyphenols, namely with mitochondria, may have a huge impact on the treatment of mitochondrial dysfunction-related disorders.

Abstract We report the synthesis of 4-thioferulic acid (TFA), a new ferulic acid (FA) derivative, and highlight the differences between the two compounds concerning rate and mechanism of radical scavenging activity, redox potential, acidity of the phenol/thiophenol moieties, cytotoxicity in differentiated SH-SY5Y cells, and neuroprotection against hydrogen peroxide (H2O2) and tert-butyl hydroperoxide (t-BHP) in the same cellular model.

Abstract A simple, fast, and laboratory efficient doped P carbon nanoparticles synthesis is developed for fingerprint imaging, using 1,3-dihydroxyacetone and di-phosphorous pentoxide. Fluorescence nanoparticles, with an average size of 230 nm were obtained, without additional energy input or external heating. ATR, solid NMR, XPS and fluorescence spectroscopy revealed their surface functionalization; a reaction mechanism is proposed. Fluorescence measurements exhibited a maximum emission band at ca. 495 nm, when excited at 385 nm. The images obtained, on different surfaces such as mobile telephone screen, magnetic band and metallic surface of a credit card and a Euro banknote treated with the obtained nano-powders allows us to record positive matches, confirming that the experimental results illustrate the effectiveness of proposed method.

Abstract We report a study on the energetics and structural properties of gallic (1) and ellagic (2) acids. The experimental values of standard enthalpy of formation in solid state at 298.15 K, Delta H-f(m)0 (cd) of 1 as (-985.0 +/- 2.9 kJ.mol(-1)) and 2 as (-1377.9 +/- 4.7 kJ.mol(-1)) have been determined. The vapour pressure of 1 have been measure by Knudsen effusion methodology and the derived enthalpy of sublimation, Delta H-g(cd)m(0). was combined with the Delta H-f(m)0 (cd) in order to derive its gas-phase enthalpy of formation, Delta(f) H-m(0)(1,g) = -835.7 +/- 4.0 kJ.mol(-1). Quantum chemical calculations, at DFT (M05-2X) and composite ab initio Gn (n = 3, 4) levels of theory, provided the consistency of the experimental results and a plausible estimation of Delta H-f(m)0 (g) of 2 as (-1128.6 +/- 6.4 kJ.mol(-1)), which was deduced from the isodesmic-reactions methodology. (C) 2018 Published by Elsevier Ltd.

Abstract The fate and behaviour of 2-hydroxy-4-methoxyphenyl)-(2-hydroxyphenyl)-methanone, ordinarily known as benzophenone-8 (BP8), in aqueous solution, is thoroughly addressed in this study. The reactions were followed by means of high-performance liquid chromatography coupled with ultraviolet, diode-array detection (HPLC-UV-DAD). Potential by-products of degradation were analysed and determined by liquid chromatography coupled with diode-array detection and mass spectrometry (LC-DAD-MS). BP8 displayed very significant reactivity towards free available chlorine, following a pseudo-first order kinetic profile with rate constant k(obs) = 0.0036 +/- 0.0002 s(-1) and a half-life period of t(1/2) = 194.12 +/- 7.90 s. Disinfection-induced degradation yielded only monochlorinated and dichlorinated disinfection by-products (DBPs). With or without dissolved organic matter (DOM) in solution, the pH and chlorine concentration were the only influential variables on degradation. Photo-induced degradation was assessed by means of exposure to artificial solar radiation. The compound proved to be extremely photo-stable, with a kinetic rate constant of k = 0.00083 +/- 0.00002 min(-1) and a half-life period of t(1/2) = 835.12 +/- 20.12 min. Exposure to artificial solar radiation did not generate any meaningful alterations in the UV spectrum of BP8. There are indications of the possible formation of a photo-isomer, but its extremely low significance and intensity, even after pre-concentration, deemed it negligible.

Abstract This paper reports thermodynamic properties of phase transitions of 2,4,6-trichloro and 2,4,6-tribromo anisoles and of 2,4,6-tribromophenol. The vapor pressures of both crystalline and liquid phases (including supercooled liquid) of the three compounds were measured, respectively, in the temperature ranges T = (297.1 to 368.3) K, T = (330.7 to 391.7) K, and T = (336.5 to 401.7) K, using a static method based on capacitance diaphragm manometers. Moreover, the sublimation vapor pressures of 2,4,6-tribromophenol were also measured in the temperature interval (307.2 to 329.2) K, using a Knudsen mass-loss effusion technique. The standard molar enthalpies, entropies, and Gibbs energies of sublimation and of vaporization, at reference temperatures, were derived from the experimental results as well as the (p,T) values of the triple point of each compound. The temperatures and molar enthalpies of fusion of the three benzene derivatives were determined using differential scanning calorimetry and were compared with the values derived indirectly from the vapor pressure measurements. The thermodynamic results were discussed together with the available literature data for 2,4,6-trichlorophenol. To help rationalize the phase behavior of these substances, the crystallographic structure of 2,4,6-tribromophenol was determined by single crystal X-ray diffraction.

Abstract The Ho3+/Yb3+ doped Gd2O3 phosphor was synthesized via the hydrothermal process. Co-doping of Ca2+ and Zn2+ ions caused a change in the particle morphology and aggregation of the Ho3+/Yb3+: Gd2O3 phosphor. The structural characterization of these particles was performed using X-ray diffraction analysis, Fourier transforms infrared spectroscopy and scanning electron microscopy. The 980 nm excitation assisted upconversion luminescence and 449 run excitation assisted downshifting luminescence of these phosphor particles were compared through the incorporation of Ca2+ and Zn2+ co-dopants. The co-dopants concentration was varied at 0, 5, 10, 15 and 20 mol %. The change in upconversion/downshifting luminescence under the influence of the optimized molar concentration of these co-dopants was studied and explained based on structural variations in the present phosphor material. The paramagnetic behavior of these particles was characterized and compared to search possible applications of these particles in the biomedical field. The samples were studied comparatively for temperature sensing.

Abstract This work aims to provide reliable heat capacities for ethylene glycol and selected oligo(ethylene glycol)s (diethylene glycol, triethylene glycol, tetraethylene glycol, pentaethylene glycol, and hexaethylene glycol), which are industrially important chemicals produced on a large scale. Besides, new data extend the database needed for a better understanding of complex behavior of compounds capable of forming hydrogen bonds. Isobaric heat capacities of ethylene glycols were measured with a Tian-Calvet-type calorimeter in the temperature range of 260 to 358 K. The phase behavior was investigated with a heat-flux differential scanning calorimeter. A simple additive estimation method for liquid heat capacity of oligo(ethylene glycol)s was developed and tested through comparison with newly measured liquid heat capacities of polyethylene glycols 400 and 600.

Abstract The selective fluorescence sensing of fructose was achieved by fluorescence quenching of the emission of hydrothermal-synthesized carbon quantum dots prepared by 3-hydroxyphenylboronic acid. Quantification of fructose was possible in aqueous solutions with pH of 9 (Limit of Detection L-OD and Limit of Quantification L-OQ of 2.04 and 6.12mM), by quenching of the emission at 376nm and excitation similar to 380nm with a linearity range of 0-150mM. A Stern-Volmer constant (K-SV) of 2.11x10(-2)mM(-1) was obtained, while a fluorescent quantum yield of 31% was calculated. The sensitivity of this assay towards fructose was confirmed by comparison with other sugars (such as glucose, sucrose and lactose). Finally, the validity of the proposed assays was further demonstrated by performing recovery assays in different matrixes.

Abstract Oxidative treatment of Multi-Walled Carbon Nanotubes (MWCNT's) was done by chemical functionalization by using the mixture acid, which is a mixture of sulfuric acid (H2SO4) and nitric acid (HNO3). Functionalization was governed by four parameters namely mixture acid concentration, temperature(T), time of heating(t) and the amount of MWCNTs used. After functionalization, functionalized MWCNT's were then diluted in dimethylformamide (DMF) to analyse the percentage of soluble MWCNT's. Also, by increasing the time of functionalization, it was observed that overall yield decreases but the percentage of functionalized product inside the yield quantity remains the same. Material characterization was also carried out at several steps to validate this theory. Chemical functionalization of MWCNT's is generally significant for the manufacturing of polymerbased nanocomposites. Oxidative treatment enhances the dispersion and interfacial bonding within the epoxy matrix. In this research work, a bio-based epoxy resin was selected for the manufacturing of nanocomposite samples with various concentrations of pristine and functionalized MWCNTs. Mechanical and electrical characterization was finally carried out to increase the knowledge on the interaction of MWCNT's with the selected green epoxy matrix system and their influence on the original properties of the resin. (C) 2019 The Authors. Published by Elsevier B.V.