Surface contributions to the XPS spectra of nanostructured NiO deposited on HOPG

In this work we present an in situ X-ray photoelectron spectroscopy (XPS) study of the growth of NiO on highly ordered pyrolitic graphite (HOPG). The XPS spectra were measured as a function of the equivalent NiO coverage. Also, ex-situ atomic force microscopy (AFM) images were taken for some of these stages in order to follow the morphology of the NiO deposits. For low coverages the lineshapes of the Ni 2p spectra differ strongly from those of bulk NiO. This has been related to the large surface contribution. The O 1s XPS spectra also show a surface related structure which follows the same trend observed in the Ni 2p spectra.     

Chemoproteomic Approach to Explore the Target Profile of GPCR ligands: Application to 5‐HT1A and 5‐HT6 Receptors

Determination of the targets of a compound remains an essential aspect in drug discovery. A complete understanding of all binding interactions is critical to recognize in advance both therapeutic effects and undesired consequences. However, the complete polypharmacology of many drugs currently in clinical development is still unknown, especially in the case of G protein‐coupled receptor (GPCR) ligands. In this work we have developed a chemoproteomic platform based on the use of chemical probes to explore the target profile of a compound in biological systems. As proof of concept, this methodology has been applied to selected ligands of the therapeutically relevant serotonin 5‐HT_1A and 5‐HT₆ receptors, and we have identified and validated some of their off‐targets. This approach could be extended to other drugs of interest to study the targeted proteome in disease‐relevant systems.     

Photoelectronic characterization of n-type silicon wafers using photocarrier radiometry

Photocarrier radiometry (PCR) was used to characterize four n-type silicon wafers with different resistivity values in the 1-20 Ω cm range. Simulations of the PCR signal have been performed to study the influence of the recombination lifetime and front surface recombination velocity on them; besides, the transport parameters (carrier recombination lifetime, diffusion coefficient, and frontal surface recombination) of the wafers were obtained by means of a fitting procedure. The PCR images that are related to the lifetime are presented, and the first photoelectronic images of a porous silicon sample are obtained.     

Noticeable Quantities of Functional Compounds and Antioxidant Activities Remain after Cooking of Colored Fleshed Potatoes Native from Southern Chile

The effect of cooking on the concentrations of phenolic compounds and antioxidant activities in 33 colored-fleshed potatoes genotypes was evaluated. The phenolic profiles, concentrations, and antioxidant activity were evaluated with a liquid chromatography diode array detector coupled to a mass spectrometer with an electrospray ionization interface (HPLC-DAD-ESI-MS/MS). Eleven anthocyanins were detected; in the case of red-fleshed genotypes, these were mainly acyl-glycosides derivatives of pelargonidin, whereas, in purple-fleshed genotypes, acyl-glycosides derivatives of petunidin were the most important. In the case of the purple-fleshed genotypes, the most important compound was petunidin-3-coumaroylrutinoside-5-glucoside. Concentrations of total anthocyanins varied between 1.21 g kg⁻¹ in fresh and 1.05 g kg⁻¹ in cooked potato and the decreases due to cooking ranged between 3% and 59%. The genotypes that showed the highest levels of total phenols also presented the highest levels of antioxidant activity. These results are of relevance because they suggest anthocyanins are important contributors to the antioxidant activity of these potato genotypes, which is significant even after the drastic process of cooking.     

Hydrogen Bonding Enhances the Electrochemical Hydrogenation of Benzaldehyde in the Aqueous Phase

The hydrogenation of benzaldehyde to benzyl alcohol on carbon‐supported metals in water, enabled by an external potential, is markedly promoted by polarization of the functional groups. The presence of polar co‐adsorbates, such as substituted phenols, enhances the hydrogenation rate of the aldehyde by two effects, that is, polarizing the carbonyl group and increasing the probability of forming a transition state for H addition. These two effects enable a hydrogenation route, in which phenol acts as a conduit for proton addition, with a higher rate than the direct proton transfer from hydronium ions. The fast hydrogenation enabled by the presence of phenol and applied potential overcompensates for the decrease in coverage of benzaldehyde caused by competitive adsorption. A higher acid strength of the co‐adsorbate increases the intensity of interactions and the rates of selective carbonyl reduction.     

The HNO donor ability of hydroxamic acids upon oxidation with cyanoferrates(III)

The hydroxamic acids (RC(O)NHOH, HA) exhibit diverse biological activity, including hypotensive properties associated with formation of nitroxyl (HNO) or nitric oxide (NO). Oxidation of two HAs, benzohydroxamic and acetohydroxamic acids (BHA, AHA) by [Fe(CN)₅NH₃]^2? or [Fe(CN)₆]^3? was analyzed by spectroscopic, mass spectrometric techniques, and flow EPR measurements. Mixing BHA with both Fe(III) reactants at pH 11 allowed detecting the hydroxamate radical, (C₆H₅)C(O)NO˙^?, as a one-electron oxidation product, as well as N₂O as a final product. Successive UV–vis spectra of mixtures containing [Fe(CN)₅NH₃]^2? (though not [Fe(CN)₆]^3?) at pH 11 and 7 revealed an intermediate acylnitroso-complex, [Fe(CN)₅NOC(O)(C₆H₅)]^3? (λ_max, 465 nm, very stable at pH 7), formed through ligand interchange in the initially formed reduction product, [Fe(CN)₅NH₃]^3?, and characterized by FTIR spectra through the stretching vibrations ν_(CN), ν_(CO), and ν_(NO). Free acylnitroso derivatives, formed by alternative reaction paths of the hydroxamate radicals, hydrolyze forming RC(O)OH and HNO, postulated as precursor of N₂O. Minor quantities of NO are formed only with an excess of oxidant. The intermediacy of HNO was confirmed through its identification as [Fe(CN)₅(HNO)]^3? (λ_max, 445 nm) as a result of hydrolysis of [Fe(CN)₅(NOC(O)(C₆H₅)]^3? at pH 11. The results demonstrate that hydroxamic acids behave predominantly as HNO donors.     

Effects of the ionization in the tautomerism of uracil: A reaction electronic flux perspective

The one‐step tautomerization processes of uracil and its radical cation and radical anion have been investigated in the light of the reaction force and reaction electronic flux (REF) formalisms. The relative energies of the different tautomers as well as the corresponding tautomerization barriers have been obtained through the use of the G4 high‐level ab initio method and by means of B3LYP/6‐311+G(3df,2p)//B3LYP/6‐311+G(d, p) calculations. Systematically, the enol radical cations are more stable in relative terms than the neutral, due to the higher ionization energy of the diketo forms with respect to the enolic ones. Conversely, the enol radical anions, with the only exception of the 2‐keto‐N1 anion, are found to be less stable than the neutral. The effects of the ionization are also sizable on the tautomerization barriers although this effect also depends on the particular tautomerization process. The reaction force analysis shows that all reactions are mainly activated through structural rearrangements that initiate the electronic activity. This electronic activity is monitored along the reaction coordinate through the REF that obeys a delicate balance between the acid and basic character of the atoms involved in the hydrogen transfer. © 2015 Wiley Periodicals, Inc.