Mechanical properties and interface of carbon/metal nanocomposites

The recent discovery of graphene and its associated thermal, electrical, and mechanical properties has motivated further investigation of similar two-dimensional (2D) systems, including all-carbon allotropes of graphene. The high strength and atomistic thickness of such 2D systems make them promising for composite materials. However, there is intrinsic weakness at the interface, typically characterized by noncovalent interactions. Here, we present two nanocomposite studies: mechanical properties of graphdiyne/copper composites and defect engineering of graphene/copper interfaces.One emerging allotrope of graphene is so-called graphdiyne, a one atom-thick carbon network which can be constructed by connecting two adjacent hexagonal rings with uniformly distributed diacetylenic linkages. This allotrope has demonstrated a set of distinguished properties and is considered a promising material, which can meet the increasing requirements to carbon-based nanomaterials. There are a few reports of the mechanical behavior of isolated graphdiyne. However, currently graphdiyne has only successfully been synthesized on copper substrates, and the composite behavior of the material has not been investigated. Here, we combine copper/graphdiyne nanocomposites with varied numbers of layers of graphdiyne sheets, as well as sandwich-structured copper/graphdiyne layers to determine mechanical properties. Using full atomistic molecular dynamics, the elastic stiffness and limit states of these nanocomposite materials are investigated through direct tensile loads. We present theoretical methods to estimate the parameters to mechanically characterize copper/graphdiyne nanocomposites. Second, we present a simple model of graphene/copper, subject to shear stress transfer across the carbon/metal interface. The weak van der Waals interaction governs the strength of the system. To increase the strength of the interface, vacancy defects are introduced into the graphene, to “rough up” the potential landscape and facilitate stress transfer. Although the strength of the graphene is decreased, the stiffness is only marginally affected, and the response of the composite system can be improved. Such defect engineering can potentially be used to enhance the compatibility of carbon/metal nanostructures

Transcontextual model application in the prediction of veteran judo athletes’ life satisfaction

Background and Study Aim: Despite recognised benefits of regular physical activity for health, the percentage of individuals linking with a physical activity practice sufficient to confer health benefits is low. The aim of current work is knowledge about effects of an extension of the motivation trans-contextual model application, specifically in the prediction of life satisfaction by veteran judo athletes. Material and Methods: It was used a sample of 99 Portuguese veteran judo athletes of both genders, aged between 30 and 76 years (M = 42.61 ±9.75), where through questionnaires were measured: basic psychological needs satisfaction, motivation, planned behaviour variables and life satisfaction. Results: The structural equations model showed that autonomy perception positively and significantly predicts autonomous motivation. In its turn it positively and significantly predicts intentions. Conclusions: Life satisfaction is positively and significantly predicted by intentions. Results authorise to emphasise the importance of fostering autonomy, since this will favour autonomous motivation, promoting a higher behavioural control over the practitioners’ intentions, thus generating a higher life satisfaction.info:eu-repo/semantics/publishedVersio

LATIN AMERICAN COMING OF AGE NARRATIVES: A SYMBOLIC AND PHYSOANALITICAL READING

Childhood is a disquieting age subsequent to the inexorable exile from love. After being banned from the only boundless union of love it will ever experience, the child sets upon a relentless journey to invent her/himself. Thus, the child surmounts its first creative challenge by transposing feelings of sorrow and loss; its first self silhouette is forged from the hardships of grief. The child assimilates its loss through symbolization, and in doing so, s/he begins her/his irreversible pursuit of identity and self-definition. This dissertation explores eight Latin American childhood narratives. The child protagonists of these stories reconstruct their world, so as to insert themselves in it. In order to achieve this, they must construct a first identity or façade through which they access their own narratives. The initial chapter focuses on three Andean boys who trial test schoolboy demeanors in and out of the school's enclosure: Timoleón Coloma (Ecuador, 1888) by Carlos Tobar; Gran Señor y Rajadiablos (Chile, 1948) by Eduardo Barrios; Los Ríos Profundos (Perú, 1957) by José María Arguedas. The second chapter explores the paternal home where three girls rehearse appearances and social behaviors: Ifigenia (Venezuela, 1924) by Teresa De la Parra; Balún Canán (México, 1967) by Rosario Castellanos; La Madriguera (Argentina, 1996) by Tununa Mercado. The third and last chapter visits the fictional childhood of two Cuban poets. We witness the dawn of imagery creativity in the poetic identity of two Caribbean boys: Paradiso (Cuba, 1966) by José Lezama Lima and Celestino antes del Alma (Cuba, 1967) by Reinaldo Arenas. Furthermore, each of these initial attempts at cohesive identity thrive in transition, not only because of the nature of their childhood passage but also because of the volatile social and historical landscapes these eight novels depict. After examining the different identity constructions in childhood, the following questions can be answered: with what symbolic resources do Latin American children elaborate their first identities? Who are their role models? What symbolic processes activate when confronted with threatening events? In order to answer these questions this dissertation draws insights from the disciplines of psychoanalysis and symbolic anthropology, especially from the assertions of Jacques Lacan, Melanie Klein, Gilbert Durand and Gastón Bachelard

LOOKING BENEATH THE TIP OF THE ICEBERG: THE TWO-SIDED NATURE OF CHATBOTS AND THEIR ROLES FOR DIGITAL FEEDBACK EXCHANGE

Enterprises are forecasted to spend more on chatbots than on mobile app development by 2021. Up to today little is known on the roles chatbots play in facilitating feedback exchange. However, digitization and automation put pressure on companies to setup digital work environments that enable reskilling of employees. Therefore, a structured analysis of feedback-related chatbots for Slack was conducted. Our results propose six archetypes that reveal the roles of chatbots in facilitating feedback exchange on performance, culture and ideas. We show that chatbots do not only consist of conversational agents integrated into instant messenger but are tightly linked to complementary front-end systems such as mobile and web apps. Like the upper part of an iceberg, the conversational agent is above water and visible within the chat, whereas many user interactions of feedback-related chatbots are only possible outside of the instant messenger. Further, we extract six design principles for chatbots as digital feedback systems. We do this by analyzing chatbots and linking empirically observed design features to (meta-)requirements derived from explanatory theory on feedback, self-determination and persuasive systems. The results suggest that chatbots benefit the social environment of conversation agents and the richness of the graphical user interface of external applications

Implementación de marketing digital para mejorar el posicionamiento del Restaurante Pollería Chifa Lily & Sholy, Los Olivos, 2021

La presente investigación implementación de Marketing Digital para mejorar el posicionamiento del restaurante Pollería Chifa Lily & Sholy, Los Olivos, 2021, tuvo como objetivo general determinar cómo la implementación de Marketing Digital influyó en el posicionamiento del restaurante Pollería Chifa Lily & Sholy. La investigación fue de tipo aplicada, enfoque cuantitativo, alcance explicativo y diseño pre experimental. La población estuvo compuesta por los clientes del restaurante que se encontraron en el distrito de Los Olivos, la muestra fue de 100 personas y el muestreo fue no probabilístico. La técnica utilizada fue la encuesta y el instrumento fue el cuestionario. Para obtener los resultados se realizó el análisis inferencial para contrastar las hipótesis a través del estadígrafo U de Mann – Whitney. Obteniendo una significancia de 0,000 lo cual es < 0,005. Esto quiere decir, que la implementación de Marketing Digital influyó en el posicionamiento del restaurante Pollería Chifa Lily & Sholy. Se concluyó que, la implementación de Marketing Digital permitió mejorar el posicionamiento del restaurante Pollería Chifa Lily & Sholy

'Unpacking' pathways to lymphoma and myeloma diagnosis : Do experiences align with the Model of Pathways to Treatment? Findings from a UK qualitative study with patients and relatives

OBJECTIVES: To explore alignment of experiences before lymphoma and myeloma diagnosis with the appraisal, help seeking and diagnostic intervals in the Model of Pathways to Treatment (MPT). DESIGN: A qualitative study using in-depth semistructured interviews with patients and relatives. Interviews were transcribed verbatim, anonymised and analysed using qualitative description. SETTING: A UK population-based haematological malignancy patient cohort. PARTICIPANTS: Fifty-five patients (35 lymphoma, 20 myeloma: diagnosed 2014-2016) and 28 relatives participated, within around a year of the patient's diagnosis. Patients were selected from those in the cohort who had returned a questionnaire about their symptoms and help seeking, and consented to contact for further research. Sampling was purposive, to achieve maximum variation in age, sex and time to diagnosis. RESULTS: Participants described time from symptom onset to diagnosis as ranging from several weeks to years. Pathways largely aligned with MPT components and help seeking could lead to the rapid investigations and identification of abnormalities. However, symptoms could be vague and/or inadvertently interpreted as other conditions, which if perpetuated, could cause diagnostic delay. The latter was associated with chaotic pathways, with activities rarely occurring only once or in a linear sequence. Rather, intermittent or ongoing processes were described, moving forward and backwards through intervals. This is 'unpacked' within five themes: (1) appraisal and reappraisal; (2) patient-initiated self-management/treatment; (3) initial help seeking; (4) re-presentation; and (5) patient-initiated actions, decisions and emotions during re-presentation. Within these themes, various healthcare professionals were consulted, often many times, as symptoms persisted/progressed. Input from family/friends was described as substantial, as was the extent to which information seeking occurred. CONCLUSION: Lymphoma and myeloma pathways align with the MPT, but do not fully capture the repetition and complexity described by participants. Time to diagnosis was often prolonged, despite the best efforts of patients, relatives and healthcare professionals. The impact of National Health Service England's Multi-diagnostic Disciplinary Centres on time to haematological cancer diagnosis remains to be seen

Oxygen control of nif gene expression in Klebsiella pneumoniae depends on NifL reduction at the cytoplasmic membrane by electrons derived from the reduced quinone pool

In Klebsiella pneumoniae, the flavoprotein, NifL regulates NifA mediated transcriptional activation of the N 2 -fixation (nif) genes in response to molecular O 2 and ammonium. We investigated the influence of membrane-bound oxidoreductases on nif-regulation by biochemical analysis of purified NifL and by monitoring NifA-mediated expression of nifH¢-¢lacZ reporter fusions in different mutant backgrounds. NifL-bound FAD-cofactor was reduced by NADH only in the presence of a redox-mediator or inside-out vesicles derived from anaerobically grown K. pneumoniae cells, indicating that in vivo NifL is reduced by electrons derived from membrane-bound oxidoreductases of the anaerobic respiratory chain. This mechanism is further supported by three lines of evidence: First, K. pneumoniae strains carrying null mutations of fdnG or nuoCD showed significantly reduced nif-induction under derepressing conditions, indicating that NifL inhibition of NifA was not relieved in the absence of formate dehydrogenase-N or NADH:ubiquinone oxidoreductase. The same effect was observed in a heterologous Escherichia coli system carrying a ndh null allele (coding for NADH dehydrogenaseII). Second, studying nif-induction in K. pneumoniae revealed that during anaerobic growth in glycerol, under nitrogen-limitation, the presence of the terminal electron acceptor nitrate resulted in a significant decrease of nif-induction. The final line of evidence is that reduced quinone derivatives, dimethylnaphthoquinol and menadiol, are able to transfer electrons to the FAD-moiety of purified NifL. On the basis of these data, we postulate that under anaerobic and nitrogen-limited conditions, NifL inhibition of NifA activity is relieved by reduction of the FAD-cofactor by electrons derived from the reduced quinone pool, generated by anaerobic respiration, that favours membrane association of NifL. We further hypothesize that the quinol/quinone ratio is important for providing the signal to NifL

Locating vaccine uptake and public participation in Ukraine:An exploratory qualitative study on attitudes and barriers to early childhood vaccination

A growing body of literature on vaccine hesitancy considers context and the intersecting factors affecting vaccine uptake. This study attempts to add focus to the conversation of vaccines in Ukraine by exploring how vaccines are perceived and how local stakeholders envision solutions to the problems surrounding vaccine uptake. Twenty-five in-depth interviews were carried out among parents of children under 6 years of age as well as health practitioners and other experts in Ukraine. Results were presented to stakeholders during a dialogue session to discuss the implications for policy recommendations. The Roma parents interviewed faced structural barriers to vaccine access, while other groups received vaccine information from others in their communities, such as family members or religious organisations. Mistrust of the health system and lack of access to reliable information preceded many doubts parents expressed surrounding vaccines. Stakeholders agreed that better, more targeted communication strategies are needed, as well as increased engagement with and training of medical practitioners. Qualitative methods allowed for a deeper, more nuanced understanding of the factors contributing to low vaccine uptake, of which vaccine hesitancy is only one part. The vulnerability-informed approach used may have broader applications for community engagement and responding to infectious diseases and crises.</p