Hydroxamic acids interactions with metals in aqueous and micellar media: a mechanistic study of complexation reactions and metallacrown formation

This thesis is focused on the different aspects of hydroxamic acids coordination, in particular on their ability to give rise to metal complexes of different stoichiometry and geometry. An in depth analysis of the binding mechanisms is carried out with the help of complementary approaches, ranging from classical spectrophotometry to a more peculiar kinetic analysis by fast techniques. Hydroxamic acids have a high binding affinity to a range of transition metal ions, particularly Fe(III), and are ligands ubiquitous in coordination chemistry and chemical biology. They have been widely employed as chelating agents for a long time and studies of their metal complexes still attract great attention. Since the possible biological activity of hydroxamic acids must be correlated with the formation of their metal complexes, interest in these systems has increased extensively over the past decade. Furthermore, hydroxamic acids can be used in extractive metallurgy as flotation agents, because of their ability to form very stable chelates with various metal ions. Hence, studies on hydroxamic acids metal complexes formation and dissociation reactions are object of vast interest, as they conduct to the comprehension of the involved microscopic mechanisms and to the evaluation of their physical and chemical requirements. In this context this thesis focuses on the equilibria and mechanisms involved in this class of complexation reactions mainly in aqueous solution, but also in micellar media. Reactions of some hydroxamic acids with three relevant and common cations in biological, industrial and environmental fields are investigated. In particular, examples of three different modes of coordination of hydroxamic acids with metal ions are reported and analyzed: from mononuclear complexes (Ni(II)) to supramolecular compounds (Cu(II)), passing through a dinuclear complex (Fe(III)). The hydroxamic acids taken into account are salicylhydroxamic acid (SHA), benzohydroxamic acid (BHA) and (S)-α-alaninehydroxamic acid (Alaha). This study is mainly based on a combination of kinetic and thermodynamic methods in order to analyze the investigated systems in different perspectives. In this thesis a new method is developed that enables the evaluation of the separate contributions to the equilibrium and rate parameters in the aqueous and micellar phase (Nickel-SHA system). Furthermore, the formation of a dinuclear complex (M2L) in aqueous solution, formed by the reaction of Fe(III) with SHA, is demonstrated for the first time. Such a complex provides the rationale for the building of supramolecular structures as metallacrowns, whose self-assembly mechanism is also worked out in this thesis work, together with metallacrowns host-guest solution equilibria (Copper-Alaha and Copper-Lanthanum-Alaha systems). Special attention is also paid to the complex speciation of the Fe(III) ion in aqueous solution. In particular, the non negligible contribution of the Fe(III) trimer is proved and its structure is clarified. This thesis, together with putting into light the richness of hydroxamic acids coordination mechanisms, reveals the importance of a complementary approach, based on both kinetics and thermodynamics, for the treatment of complex systems involved in multiple equilibria

The Role of Theory in Empirical L2 Research on Task-Based Language Teaching for Young L2 Learners

This forum will explore the extent to which theory has played a role in empirical research on Task-Based Language Teaching (TBLT) for young L2 learners and highlight opportunities that exist for future research. To begin, the most relevant theoretical entities to TBLT will be introduced. This theoretical background will set the stage for the subsequent section–– a review of three empirical studies on task-based learning with young L2 learners: Newton and Bui (2017), Zhu (2020), and Azkarai and Oliver (2019). Then, the three studies are discussed with regard to the role theory plays. Finally, some trends that come to light through the review of the studies are identified, and arguments are made vis-à-vis the need for more theory-driven, principled approaches to the empirical research on TBLT with children

El Paralelismo entre los cambios demograficos y los medios sociales y su impacto en el activismo en America Latina

En la segunda mitad del siglo XX, los avances sociales, especialmente en los ámbitos tecnológicos y médicos, cambiaron la manera en que viven los seres humanos. Los sectores demográficos empezaron a experimentar grandes transformaciones debido a la reducción de la tasa de mortalidad infantil y el crecimiento de la expectativa de vida (Saad 240). Como consecuencia, ha emergido una nueva época de vida, que se llama la edad de adulta emergente, que es caracterizada por la exploración y construcción de la identidad y creencias personales (Smith y Snell 6). Las nuevas estructuras sociales alrededor del mundo han requerido que los gobiernos provean los recursos y servicios que necesitan todos sus ciudadanos, aunque las poblaciones han aumentado continuamente y por eso, han demandado más provisiones. Cuando los sistemas gubernamentales no pueden sustentar esta magnitud de gente y la nueva manera de vivir, los ciudadanos se ponen insatisfechos y responden con marchas, manifestaciones y campañas–o en otras palabras, el activismo (“Juventud ” 33). Al mismo tiempo que cambiaron las estructuras sociales nacionales, el mundo afrontó la llegada de la Internet y luego una multitud de tecnologías virtuales ( The History 1). Como resultado, las nuevas generaciones, particularmente la generación milenio, han crecido con la tecnología, que se ha convertido en una parte esencial de la vida moderna. Por eso, los milenios que han afrontado injusticias sociales han utilizado diferentes medios tecnológicos, específicamente los medios sociales, para ayudarles a planificar y organizar sus movimientos sociales

Attractor States in Second Language Development

Identifying changing patterns of stability and variability is crucial when examining second language development (SLD) from a complex dynamic systems theory (CDST) perspective (Larsen-Freeman, 2020). By studying attractor states, or recurrent patterns of stability, light can be shed on the underlying dynamics of a complex dynamic system (van Geert & Verspoor, 2015). In the context of SLD, attractor states can be observed in individuals’ linguistic behaviors, as well as learners’ interactions with others (Hiver, 2014; van Geert & Verspoor, 2015). As such, attractor states have been cited in recent SLD literature (e.g., Amerstorfer, 2020; Evans & Larsen-Freeman, 2020; Syed et al., 2021; Gillies & Roger, 2022). The conceptual unpacking of attractor states can therefore be invaluable for SLD scholars seeking to enter the realm of CDST. Accordingly, serving as a stepping stone for those looking to foray into the CDST paradigm, this forum piece offers a definition of attractor state, identifies and describes different types of attractor states, clarifies some possible misconceptions about attractor states, and provides a few examples of attractor states in SLD

Health Information Discrepancies Between Internet Media and Scientific Papers Reporting on Omega-3 Supplement Research: Comparative Analysis

BACKGROUND: Dietary supplements are the most used complementary and alternative health modality in the United States, and omega-3 supplements continue to be the most popularly used nonvitamin or nonmineral supplements by adults. Users of dietary supplements report that they obtain health guidance from internet media resources, but there is question as to whether or not these resources provide the necessary evidence to guide health decisions. Current evidence suggests that there is a mistranslation occurring somewhere between researchers and the media. OBJECTIVE: The aim of this study was to conduct a comparative cross-sectional analysis to identify areas of discordance created when science is translated from the laboratory to Web-based news media. METHODS: A Google news search provided our convenience sample of 40 omega-3 supplement-based media reports stratified by the years 2009 to 2012. Media reports (n=17) were compared with the corresponding scientific papers for content. Report and scientific paper content were extracted using commonly accepted reporting guideline domains, and domains were then compared for detecting underlying omissions or mistranslations in reporting. Mean scores for all of the scientific papers and media reports were assessed for each domain. RESULTS: Scientific papers (n=14) generally maintained a mean close to complete for each reporting domain. The only domain where there was not a significant difference between media and scientific reporting match was within the objectives domain (chi(2)1= 0.8, P=.36). Media reports (n=17) more frequently reported potential caveats and warnings for consumers with a mean domain for caveat reporting of 0.88, with possible scores falling between 0 and 1. CONCLUSIONS: There are inherent differences in the intended audience, structure, and goals in scientific and media communications. These differences should be explored further, and consumers should be made aware of them. Additional considerations for balanced reporting and reader accessibility are also necessary to take into account and are explored further in this analysis

Presentación del Servicio de Salud Mental del Hospital Sor María Ludovica

El proyecto de trabajo del Servicio de Salud Mental se enmarca y encuentra sus límites en la concepción actual de la Salud Mental, concebida como un proceso determinado y atravesado por los componentes históricos, socioeconómicos, culturales, biológicos y psicológicos. El Servicio de Salud Mental fue fundado en 1957. A poco de su fundación se constituyó en un centro de referencia para la asistencia, docencia e investigación. En 1970 se creó la residencia de Psiquiatría, y en 1986 la residencia de Psicología. A partir del año 2007, se lo denomina “Servicio de Salud Mental”. Dicho Servicio se inserta en un hospital interzonal de agudos, especializado en pediatría, destinado al tercer nivel de atención y orientado a la alta complejidad. Este cuenta con la única Guardia de la especialidad en toda la Provincia de Buenos Aires y recibe derivaciones y consultas de diversas localidades de la provincia

Comparación de la prevalencia de la patología infecciosa en una clínica privada y un hospital público de la ciudad de La Plata

Las enfermedades infecciosas siguen siendo una causa importante de mortalidad y morbilidad y han empeorado las condiciones de vida de muchos millones de personas en el mundo. Más de 1,4 millones de personas alrededor del mundo están padeciendo infecciones adquiridas en establecimientos de salud. En el mundo desarrollado, se estima que entre el 5 y el 10% de los pacientes admitidos en modernos hospitales contraen una o más infecciones. En los países en desarrollo, el riesgo de infecciones asociadas a la atención sanitaria es entre 2 y 20 veces más elevado que en los países desarrollados. Las infecciones intrahospitalarias (IIH) constituyen un problema médico y de salud pública cada vez más importante representando la sexta causa de muerte en los EE.UU. y la quinta causa de muerte en Argentina de acuerdo a datos del INDEC publicados en el 2004. Las IIH habitualmente aparecen en enfermos sometidos a cirugías o a procedimientos invasivos; las infecciones del tracto respiratorio inferior (TRI) y la septicemia son las infecciones más graves, mientras que las infecciones del tracto urinario son las más frecuentes.Facultad de Ciencias Médica

Can Mindfulness Address Maladaptive Eating Behaviors? Why Traditional Diet Plans Fail and How New Mechanistic Insights May Lead to Novel Interventions

Emotional and other maladaptive eating behaviors develop in response to a diversity of triggers, from psychological stress to the endless external cues in our modern food environment. While the standard approach to food- and weight-related concerns has been weight-loss through dietary restriction, these interventions have produced little long-term benefit, and may be counterproductive. A growing understanding of the behavioral and neurobiological mechanisms that underpin habit formation may explain why this approach has largely failed, and pave the way for a new generation of non-pharmacologic interventions. Here, we first review how modern food environments interact with human biology to promote reward-related eating through associative learning, i.e., operant conditioning. We also review how operant conditioning (positive and negative reinforcement) cultivates habit-based reward-related eating, and how current diet paradigms may not directly target such eating. Further, we describe how mindfulness training that targets reward-based learning may constitute an appropriate intervention to rewire the learning process around eating. We conclude with examples that illustrate how teaching patients to tap into and act on intrinsic (e.g., enjoying healthy eating, not overeating, and self-compassion) rather than extrinsic reward mechanisms (e.g., weighing oneself), is a promising new direction in improving individuals\u27 relationship with food

Comics and reading literacy: for a teaching practice of the sequential art

Is it possible to use comics at school in order to further students’ reading literacy? In this article the authors try to reply to this question applying the principles of the sequential art. Moving from the robust consensus of educational value of images in textbooks, the proposal of a mediation realized using multimodal texts, like comics, represents an alternative and valid solution to traditional teaching reading paths. After a literature review, an analysis of implications and main criticalities on using comics at school is presented. These passages are functional to explore new didactic scenarios where images and written texts can be used to promote the development of the reading literacy as an interactive and social activity. Fumetti e competenza di lettura: per una didattica dell’arte sequenzialeÈ possibile utilizzare il fumetto a scuola per la promozione della competenza di lettura? Il presente articolo prova a rispondere a questa domanda ricorrendo ai principi dell’arte sequenziale. A fronte del riconoscimento, ormai consolidato, del valore educativo delle immagini nei libri, la proposta di una mediazione realizzata attraverso testi multimodali, quali quelli del fumetto, si pone come un’alternativa didattica ai tradizionali percorsi di insegnamento-apprendimento della lettura. Alla rassegna sul fumetto è affiancata così una disamina delle implicazioni e delle criticità correlate al suo uso a scuola: passaggi funzionali all’esplorazione dei possibili scenari di una didattica che, puntando su immagini e parola scritta, consenta di promuovere l’acquisizione e lo sviluppo della competenza di lettura intesa come attività sociale e interattiva