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21.
Miguel Fernández Reinaldo Marín Fulgencio Proverbio Delia I. Chiarello Fernando Ruette 《International journal of quantum chemistry》2017,117(21)
The role of magnesium sulfate as an inhibitor of lipid peroxidation has been poorly understood, although this salt has been intensively used in a wide range of diseases related to lipid peroxidation, for example, preeclampsia. Classical molecular dynamics (MD) simulations of a lipid bilayer in the presence of ?OH radicals and MgSO4 were performed to study their effects on membrane properties. Additionally, quantum chemistry (QC) calculations for MgSO4, ?OH, MgSO4?OH, [MgSO4(H2O)4], and [MgSO4(H2O)4?OH] were performed to analyze the interactions between ?OH…Mg. The MD results showed that the Mg salt is hydrated, forming a contact ion pair (CIP) that is adsorbed on the membrane surface close to phosphate groups. Comparisons of MD calculations for Mg? O distances indicate good agreement with theoretical QC and experimental studies. MD results also reveal that MgSO4 increases the thickness and the compressibility modulus of the membrane, indicating that it is less compressible. In contrast, DFT calculations show important ?OH…Mg? SO4 interactions in hydrated systems that inhibit the radical action by resonance in the group (smearing the spin density). These results, together with the reported experimental findings of ?OH high mobility in water and fast water exchange in Mg+2, may explain the MgSO4 protective effect against lipid peroxidation on cellular membranes. 相似文献
22.
Selli E Chiarello GL Quartarone E Mustarelli P Rossetti I Forni L 《Chemical communications (Cambridge, England)》2007,(47):5022-5024
A two-compartment Plexiglas cell has been set up and tested for separate hydrogen and oxygen production from photocatalytic water splitting on a thin TiO2 layer deposited by magnetron sputtering on a flat Ti electrode inserted between the two cell compartments. 相似文献
23.
High-resolution electron energy loss spectroscopy has been used to investigate the adsorption and co-adsorption of oxygen and CO on the Pt(3)Ni(111) surface. For the sake of comparison, similar measurements have also been performed on the Pt(111) surface. We find that CO adsorbs at the same manner on both surfaces. By contrast, significant differences between the two surfaces exist concerning the adsorption of O and the co-adsorption of O with CO. 相似文献
24.
Surface Extended Energy Loss Fine Structures (SEELFS) have been detected above the K-edge of oxygen adsorbed on an Al sample. This is the first evidence that the local geometry of adsorbates on metal surfaces can be investigated with the electron energy loss technique in the reflection mode. This experimental technique is highly surface sensitive and accurate bond lengths can be obtained. The oxidation model implied by our results for the OAl system is in agreement with data in the literature. 相似文献
25.
26.
Antonio Politano Dr. Raffaele G. Agostino Prof. Vincenzo Formoso Dr. Gennaro Chiarello Prof. 《Chemphyschem》2008,9(8):1189-1194
The coadsorption of Na with CO and O on Ni(111) is studied by high‐resolution electron energy loss spectroscopy. Experimental evidence for a very short‐range interaction between Na and coadsorbates is reported, in contrast with recent theoretical predictions overestimating nonlocal alkali‐induced effects. Loss spectra show distinct features, as a consequence of different local [CO]:[Na] and [O]:[Na] stoichiometries. 相似文献
27.
Politano A Formoso V Agostino RG Colavita E Chiarello G 《The Journal of chemical physics》2008,128(7):074703
The interaction of oxygen with alkalis (Na, K) on Ni(111) was studied by high-resolution electron energy loss spectroscopy. Loss measurements revealed for the first time a softening of the O-Ni bond and, simultaneously, a strengthening of the alkali-Ni bond in the alkali+O coadsorbed phase, in perfect agreement with recent theoretical calculations. The weakening of the O-Ni bond was ascribed to the alkali-induced filling of the O 2p(z) antibonding orbitals. Different physical mechanisms were discussed for explaining the strengthening of the alkali-substrate bond whenever alkalis are coadsorbed with O adatoms. 相似文献
28.
Geller AM Stedile FC Peralba Mdo C Pizzolato TM Dos Santos JH 《Journal of colloid and interface science》2005,288(1):45-54
Silica (350 m(2) g(-1)) was chemically modified with Cp2ZrCl2 and (nBuCp)2ZrCl2 by grafting. Hybrid silica bearing surface indene groups was synthesized by the sol-gel method, followed by metallation with ZrCl(4)2THF. The resulting phases were characterized by Rutherford backscattering spectrometry (RBS), 13C and 29Si magic angle spin nuclear magnetic resonance, X-ray photoelectron spectroscopy, and diffuse reflectance infrared Fourier transform spectroscopy. According to RBS measurements, metal content was 0.2- to 0.3-wt% Zr/SiO2 for the grafted systems and 4.5-wt% Zr/SiO2 for the phase prepared by the sol-gel method. The solid phases were evaluated for the adsorption/preconcentration of lindane and heptachlor epoxide from aqueous solution. For comparative reasons, the commercial LC-18 phase was also evaluated. Analyte concentration was monitored by gas chromatography electron capture detection. For the grafted phases, the coordination sphere around the metal center seems not to influence the adsorption/desorption properties of these phases vis-a-vis the studied analytes. In the case of the phases prepared by the sol-gel method, recovery results were comparable to those observed for LC-18. Experiments using ZrO2 and ZrO2/SiO2 phases led to lower recovery results. 相似文献
29.
Marilda Chiarello 《Analytical letters》2018,51(16):2561-2574
Food contamination by pesticide residues, which may cause serious human health problems, is an ongoing challenge. Safer organically grown food is therefore needed. However, best practices are not always followed for farming organic foods, necessitating analytical testing. To this end, this report describes an analytical method for the evaluation of 82 pesticides by high-performance liquid chromatography–high-resolution mass spectrometry in organically grown carrots. The method was validated in terms of linearity, precision, and limits of detection and quantification that ranged from 0.3 to 5 and 5–40?µg?kg?1, respectively. From the 82 pesticides evaluated in this multiresidue method, three were detected in real samples, with bendiocarb detected at the highest concentration (199.11?µg?kg?1), which was above the maximum residue limit. Chlorpyriphos (43.20?µg?kg?1) and amitraz (11.22?µg?kg?1) were also detected. Measurement of contaminants in organic foods should be a standard practice, which would contribute to improved food safety. It is observed that even organic foods can be contaminated by pesticides, intentionally or unintentionally, perhaps by cross-contamination. Pesticides in organic foods are a public health problem because consumers expect organic foods to be free of pesticide contamination, but this is not necessarily the case. 相似文献
30.