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"Palacios, Jesús"
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Revisiting the Electrochemical Reduction Mechanism of Nitrosobenzene in Acetonitrile. Concomitant Reactions and Voltammetric Simulation
The electrochemical reduction mechanism of nitrosobenzene in acetonitrile was reconsidered in this work. The commonly accepted mechanism assumes that the nitrosobenzene radical anion dimerize to yield a dianion, which decompose into azoxybenzene as the reduction product. Even though this proposal is consistent with preparative experiments, it does not reproduce fully the experimental voltammetric behaviour when it is simulated. Also, It does not explain why the apparent electron number is different in the time scale of cyclic voltammetry and preparative electrolysis. To understand these discrepancies, it was proposed the intervention of reactions consuming part of the starting nitrosobenzene, which allowed to reconsider the role of alternative chemical reactions like that occurring between the anion of phenylhydroxylamine with nitrosobenzene and the hydroxyl ion with nitrosobenzene. In this framework, these concomitant reactions were additionally included in the mechanism to simulate the voltammetric behaviour at different scan rates. Thermodynamic and kinetic parameters of the extended mechanism are reported. Since in the hydroxyl ion is either product or reactive in some reaction steps, the global mechanism was deemed to occurs as a kind of loop. The electrochemical reduction of nitrosobenzene in acetonitrile yield a radical anion which dimerize and is next protonated by traces of water to yield azoxybenzene as final product. The proper simulation of the experimental voltammograms required the introduction of concomitant reactions in which deprotonated phenylhydroxylamine and hydroxide ions are involved. The overall mechanism involves loops where nitrosobenzene is consumed.
Journal Article
Hydrogen Bonding and Proton Transfer Processes during the Electrochemical Reduction of Nitrosobenzene in Acetonitrile
Nitrosobenzene (PhNO) is the central intermediary during the electrochemical reduction of nitrobenzene in the presence of strong and moderately strong proton donors. Its reduction affords phenylhydroxylamine (PhNHOH) as product through a global mechanism involving the exchange of two electrons and two protons. During the analysis from weak to strong proton donors (acetic to trichloroacetic acids), the hydrogen bonding association with nitrosobenzene changes the reduction pathway from stepwise to concerted. The carboxylate ions that are released during the proton transfer steps associate with the phenylhydroxylamine and make its oxidation also concerted. These processes are studied by cyclic voltammetry, and the experimental voltammograms are simulated in the framework of a full mechanism in which the reduction steps as well as those of oxidation are considered. Information about the reliability of the association complexes involved in different steps is obtained from electronic structure calculations. The mechanism of reduction of nitrosobenzene (PhNO) in presence of carboxylic acids (RCOOH) as proton donors, in acetonitrile, is analyzed using voltametric simulation. The formation of association complexes PhNO(RCOOH) induces concerted proton electron transfer reaction in a square scheme of reduction. The phenylhydroxylamine complex PhNHOH(RCOO−)n follows also a CPET oxidation. Both complexes are essential to reproduce the experimental voltammograms.
Journal Article
Semicontinuous Microemulsion Polymerization of Polymeric Nanoparticles of Poly(cyanoacrylates) and Poly(caprolactone)
Polymeric nanoparticles based on poly(ethyl cyanoacrylate) (PECA) and poly(ε-caprolactone) (PCL) were synthesized via semicontinuous microemulsion polymerization for potential biomedical applications. A systematic evaluation of four surfactants (Tween 80, Alkonat L70, Genapol LRO, and Brij-20) was carried out to determine their effects on micelle formation and particle size. Brij-20 enabled the formation of nanoparticles under 100 nm, with optimal conditions identified at 4% surfactant concentration and pH 1.75. The polymerization process included acid-catalyzed ring-opening of ε-caprolactone, followed by the semicontinuous addition of ethyl-2-cyanoacrylate under an inert atmosphere. Copolymerization was confirmed through FT-IR spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, and differential scanning calorimetry, revealing a glass transition temperature (Tg) of 110.9 °C, indicating PECA as the dominant phase. Thermogravimetric analysis showed two decomposition events corresponding to each polymer. Transmission electron microscope analysis revealed nanoparticles averaging 51.74 nm in diameter. These findings demonstrate the feasibility of producing PECA-PCL nanoparticles with controlled size and composition, suitable for drug delivery and other biomedical uses.
Journal Article
Treatment and Healing of Leishmaniasis in a Wolf in Semi-Captivity Regime from an Educational Center of Zamora Province (Spain)
Leishmaniasis in wild canids is a vector-borne disease caused in Europe by the protozoan parasite Leishmania infantum. To date, there is limited information on clinical signs and laboratory abnormalities in wolves due to leishmaniasis. The current clinical case report described a female Iberian wolf (Canis lupus signatus) housed in semi-captivity conditions at the Centro del Lobo Ibérico “Félix Rodríguez de la Fuente”, in Robledo de Sanabria, Zamora (Spain), with an interdigital ulcerous wound at the right forepaw, hyper-gammaglobulinemia, and abnormal liver blood parameters. Definitive serodiagnosis of leishmaniasis was established using antileishmanial serum antibodies and PCR analysis of different biological samples. A gold-standard anti-L. infantum treatment protocol consisting in subcutaneous meglumine antimoniate and oral allopurinol combination was installed. However, the presence of pain at the site of injection due to meglumine antimoniate administration forced its substitution by oral miltefosine. A progressive reduction of the levels of anti-L. infantum serum antibodies and the concentrations of gamma-globulin fraction was detected after antileishmanial treatment as well as a decline of liver GPT. To our knowledge, this is the first case of leishmaniasis diagnosed in a wolf housed in semi-captivity conditions, with the condition subsequently treated and successfully cured.
Journal Article
Adoption-Related Gains, Losses and Difficulties: The Adopted Child’s Perspective
Adoption provides stability, loving care, security, and family interactions for children that have been separated from their birth parents. It also entails many challenges and difficulties, especially for adoptees in middle childhood, since feelings of loss can be particularly strong at this developmental stage. Aiming to use empirical evidence to improve adoption-related policies and practices, this study focused on the adoption-related gains, losses and difficulties, poorly explored in adoption research. One-hundred and two children aged 8–10, who were adopted from care at different ages, were interviewed using the Children’s Interview about Adoption. Data collected on gains, losses and difficulties were analyzed using content analysis. Results showed that adopted children identified four main gains inherent to the experience of being adopted. The most frequent gains were related to being part of a family and experiencing family life. Adoptees identified losses related to their pre-adoption life, particularly birth family loss (parents and siblings), and previous relationships loss (especially school peers). Most adoptees reported facing family and social relationships difficulties in their post-adoption life, such as communicating openly about adoption with the adoptive parents and peers. Findings showed that children’s adaptation to adoption is complex, ambivalent and individually experienced. Adopted children need parents and professionals to help them elaborate and make sense of their life story. Important implications for practice and research with adoptees, adoptive parents, adoption professionals/practitioners and school staff were drawn from data.
Journal Article
Adopted Children's Social Competence: The Interplay Between Past and Present Influences
Objective: To explore potential postadoption moderators of the link between preadoption experiences and adoptees' social competence. Background: In the context of the limited and inconsistent knowledge about adopted children's social competence, our hypotheses concern the interplay between preadoption parental neglect and adoptive parents' emotion socialization practices. Method: With adopters as informants, the social competence of 97 Portuguese school-age children was evaluated in terms of social skills and competing problem behaviors, using the Social Skills Improvement System-Rating Scale. Children's preadoption experiences (using a sociodemographic questionnaire) and parental emotion socialization (evaluated by the Coping with Children's Negative Emotions Scale) were also assessed. Results: Time since adoption and unsupportive adoptive parents' responses moderated the relationship between preadoption parental neglect and adoptees' social skills. Unsupportive adoptive parents' responses exacerbated the effects of preadoption neglect. This moderation was stronger with longer postadoption time. Conclusion: Added to preadoption parental neglect, unsupportive adoptive parenting accentuates the risks for adoptees' social competence. Implications: Adoptive parents should be informed that socialization practices concerning children's negative emotions are associated with adopted children's social competence.
Journal Article
I. CHILDREN IN INSTITUTIONAL CARE: DELAYED DEVELOPMENT AND RESILIENCE
Children exposed to institutional care often suffer from \"structural neglect\" which may include minimum physical resources, unfavorable and unstable staffing patterns, and socially emotionally inadequate caregiver-child interactions. This chapter is devoted to the analysis of the ill effects of early institutional experiences on resident children's development. Delays in the important areas of physical, hormonal, cognitive, and emotional development are discussed. The evidence for and against the existence of a distinctive set of co-occurring developmental problems in institutionalized children is weighed and found to not yet convincingly demonstrate a \"postinstitutional syndrome.\" Finally, shared and nonshared features of the institutional environment and specific genetic, temperamental, and physical characteristics of the individual child are examined that might make a crucial difference in whether early institutional rearing leaves irreversible scars.
Journal Article
Relationship between sense of coherence and diabetes mellitus: a systematic review.(ARTICLE texto en ingles)
The aim was to synthesize the best scientifc evidence on the effect of sense of coherence in disease development, treatment, and biomedical metabolic control indicators, as well as the complications involved for people at risk of developing diabetes and for diabetics. The systematic review method was implemented. Search and selection efforts of two independent reviewers on Scopus, Web of Science, PubMed, Ebsco, Science Direct, and manuals databases, available until 2017, in Spanish and English, of the population aged 18 and over. From a total of 154 studies, 20 articles were included in the systematic review. Over half of the studies used the SOC-13 version to verify the sense of coherence and the most frequent indicator of metabolic control was glycated hemoglobin. In addition to this, 14 of the 20 studies found a statistically signifcant relationship between sense of coherence and diabetes. It is concluded that the sense of coherence has a strong correlation with diabetes in the different phases of the disease and is related to the reduction of risk for the development of the disease, a reduction of glycated hemoglobin values, and the appearance of diabetes mellitus-related complications.
Journal Article