Sub-surface laser nanostructuring in stratified metal/dielectric media: a versatile platform towards flexible, durable and large-scale plasmonic writing

Laser nanostructuring of pure ultrathin metal layers or ceramic/metal composite thin films has emerged as a promising route for the fabrication of plasmonic patterns with applications in information storage, cryptography, and security tagging. However, the environmental sensitivity of pure Ag layers and the complexity of ceramic/metal composite film growth hinder the implementation of this technology to large-scale production, as well as its combination with flexible substrates. In the present work we investigate an alternative pathway, namely, starting from non-plasmonic multilayer metal/dielectric layers, whose growth is compatible with large scale production such as in-line sputtering and roll-to-roll deposition, which are then transformed into plasmonic templates by single-shot UV-laser annealing (LA). This entirely cold, large-scale process leads to a subsurface nanoconstruction involving plasmonic Ag nanoparticles (NPs) embedded in a hard and inert dielectric matrix on top of both rigid and flexible substrates. The subsurface encapsulation of Ag NPs provides durability and long-term stability, while the cold character of LA suits the use of sensitive flexible substrates. The morphology of the final composite film depends primarily on the nanocrystalline character of the dielectric host and its thermal conductivity. We demonstrate the emergence of a localized surface plasmon resonance, and its tunability depending on the applied fluence and environmental pressure. The results are well explained by theoretical photothermal modeling. Overall, our findings qualify the proposed process as an excellent candidate for versatile, large-scale optical encoding applications. Keywords : Ceramic materials; Composite films; Environmental technology; Film growth; Film preparation; Multilayer films; Multilayers; Nanocrystals; Optical data processing; Plasmons; Silver; Substrates; Surface plasmon resonance; Thin films; Ultrathin films, Laser annealing; Localised surface plasmon resonance; Multi-layer thin film; Nano-structuring; Plasmonics, Nanocomposite film

Laser-matter interactions, phase changes and diffusion phenomena during laser annealing of plasmonic AlN:Ag templates and their applications in optical encoding

Nanocomposite thin films incorporating silver nanoparticles are emerging as photosensitive templates for optical encoding applications. However, a deep understanding of the fundamental physicochemical mechanisms occurring during laser-matter interactions is still lacking. In this work, the photosensitivity of AlN:Ag plasmonic nanocomposites is thoroughly examined and a series of UV laser annealing parameters, such as wavelength, fluence and the number of pulses are investigated. We report and study effects such as the selective crystallization of the AlN matrix, the enlargement of the Ag nanoparticle inclusions by diffusion of laser-heated Ag and the outdiffusion of Ag to the film's surface. Detailed optical calculations contribute to the identification and understanding of the aforementioned physical mechanisms and of their dependency on the laser processing parameters. We are then able to predetermine the plasmonic response of processed AlN:Ag nanocomposites and demonstrate its potential by means of optically encoding an overt or covert cryptographic pattern

Structure and agency in learning: a critical realist theory of the development of capacity to reflect on academic practice

Theories of learning typically downplay the interplay between social structure and student agency. In this article, we adapt a causal hypothesis from realist social theory and draw on wider perspectives from critical realism to account for the development of capacity to engage in reflection on professional practice in academic roles. We thereby offer a theory of professional learning that explores how social and cultural structures and personal emergent powers combine to ensure variation in the emergence of such reflective capacity. The influence of these factors on professional learning is mediated through reflexive deliberation and social interaction, with the exercise of one's personal powers specifically identified as a stratum of social reality. We consider further the role of concerns, intention and attention in professional learning, drawing together issues that are rarely considered within the same theory. We thus offer a comprehensive account of professional learning, showing how a focus on structure and agency increases the explanatory power of learning theory

Reframing professional development through understanding authentic professional learning

Continuing to learn is universally accepted and expected by professionals and other stakeholders across all professions. However, despite changes in response to research findings about how professionals learn, many professional development practices still focus on delivering content rather than enhancing learning. In exploring reasons for the continuation of didactic practices in professional development, this article critiques the usual conceptualization of professional development through a review of recent literature across professions. An alternative conceptualization is proposed, based on philosophical assumptions congruent with evidence about professional learning from seminal educational research of the past two decades. An argument is presented for a shift in discourse and focus from delivering and evaluating professional development programs to understanding and supporting authentic professional learning

Low temperature sputter-deposited ZnO films with enhanced Hall mobility using excimer laser post-processing

We report the low temperature (T  <  70 °C) fabrication of ZnO thin films (~140 nm) with Hall mobility of up to 17.3 cm2 V−1 s−1 making them suitable for thin film transistor (TFT) applications. The films were deposited by rf magnetron sputtering at T  <  70 °C and subsequently laser processed in ambient temperature in order to modify the Hall mobility and carrier concentration. Medium-to-low energy laser radiation densities and a high number of pulses were used to avoid damaging the films. Laser annealing of the films after aging in the lab under 25%–35% relative humidity and at an average illuminance of 120 lux resulted in an overall higher mobility and relatively low carrier concentration in comparison to the non-aged films that were laser processed immediately after deposition. A maximum overall measured Hall mobility of 17.3 cm2 V−1 s−1 at a carrier density of 2.3  ×  1018 cm−3 was measured from a 1 GΩ as deposited and aged film after the laser treatment. We suggest that the aging of non-processed films reduces structural defects mainly at grain boundaries by air species chemisorption, with concomitant increase in thermal conductivity so that laser processing can have an enhancing effect. Such a processing combination can act synergistically and produce suitable active layers for TFT applications with low temperature processing requirements

Towards an ethical ecology of international service learning

International Service-Learning (ISL) is a pedagogical activity that seeks to blend student learning with community engagement overseas and the development of a more just society. ISL programmes have grown as educational institutions and non-governmental organisations have sought to achieve the goal of developing ‘global citizens’. However, Service Learning (SL) in general and International Service-Learning (ISL) in particular remain deeply under theorised. These educational initiatives provide policy makers with a practical response to their quest for a ‘Big Society’and present alluring pedagogical approaches for Universities as they react to reforms in Higher Education and seek to enhance both the student learning experience and graduate employability. After outlining the development of ISL in policy and practice, this paper draws on the rich tradition of ISL at one British university to argue that ISL is a form of engagement that has the potential to be ethical in character although we identify a number of factors that militate against this. Our contention is that ISL which promotes rationaland instrumental learning represents a deficit model and we therefore conceptualise ISL here as a transformative learning experience that evinces distinctly aesthetic and even spiritual dimensions. Upon this theoretical groundwork we lay the foundations for conceptualizing ISL in ways that ensure its ethical integrity

Transformative learning as pedagogy for the health professions : a scoping review

Context Transformative learning (TL) has been described as learning that challenges established perspectives, leading to new ways of being in the world. As a learning theory it has resonated with educators globally, including those in the health professions. Described as a complex metatheory, TL has evolved over time, eliciting divergent interpretations of the construct. This scoping review provides a comprehensive synthesis of how TL is currently represented in the health professions education literature, including how it influences curricular activities, to inform its future application in the field. Methods Arksey and O'Malley's six‐step framework was adopted to review the period from 2006 to May 2018. A total of 10 bibliographic databases were searched, generating 1532 potential studies. After several rounds of review, first of abstracts and then of full texts, 99 studies were mapped by two independent reviewers onto the internally developed data extraction sheet. Descriptive information about included studies was aggregated. Discursive data were subjected to content analysis. Results A mix of conceptual and empirical research papers, which used a range of qualitative methodologies, were included. Studies from the USA, the UK and Australia were most prevalent. Insights relating to how opportunities for TL were created, how it manifests and influences behaviour, as well as how it is experienced, demonstrated much congruency. Conceptions of TL were seen to be clustered around the work of key theorists. Conclusions The training of health professionals often takes place in unfamiliar settings where students are encouraged to be active participants in providing care. This increases the opportunity for exposure to learning experiences that are potentially transformative, allowing for a pedagogy of uncertainty that acknowledges the complexity of the world we live in and questions what we believe we know about it. TL provides educators in the health professions with a theoretical lens through which they can view such student learning

Achieving Education for Sustainable Development (ESD) in Early Childhood Education Through Critical Reflection in Transformative Learning

The central role of education in creating a more sustainable future has been already recognized by educators and policy-makers alike. This chapter argues that this can only be truly achieved through the efforts of teachers in implementing an “education of a different kind,” a general educational shift that seeks to encompass a converging transformation of the priorities and mindsets of education professionals. In this regard, the professional preparation of teachers, as the leading actors in shaping children’s learning processes, and their continuous professional development are vital considerations for Education for Sustainable Development (ESD) to be successfully achieved. Linking transformative learning and ESD has emerged as a distinct and useful pedagogy because they both support the process of critically examining habits of mind, then revising these habits and acting upon the revised point of view. This study aims to describe and evaluate the potential of transformative learning in innovating mainstream education toward sustainability by focusing on the role of critical reflection in a capacity building research project realized in Turkey. The data was gathered from 24 early childhood educators using a mixed-method research design involving learning diaries, a learning activities survey, and follow-up interviews. This chapter identified content, context, and application method of the in-service training as factors that have contributed to the reflective practices of the participants. In addition, presenting the implications regarding the individual differences in how learners engage in critical reflection practices, this research offers a framework for a content- and process-based approach derived from Mezirow’s conception of critical reflection

Learning is Like a Lava Lamp: The Student Journey to Critical Thinking

This paper explores the ways in which a university Foundation Degree programme supports undergraduate early years students to develop critical thinking, mindfulness and self-actualisation through their lived personal and professional experiences. It considers the impact of this on graduates employed within the Early Years sector. Findings inform future design of a University Foundation Degree programme situated within Early Childhood Education and Care (ECEC). As undergraduates, students engage in higher-level learning aligned to their practice within the workplace. An interpretive Participatory Qualitative Research methodology is used to gather the views of 6 alumni who completed their studies in 2014. They participated in the research freely within ethical parameters approved by a university ethics committee. Findings revealed that the development of critical thinking is empowered by having a personal or professional impetus, which in the case of Early Years is the child as being at the heart of values based practice. This, with the inclusion of mindfulness, drives students to a sustainable deeper layer of thinking to achieve self-actualisation. Through the acquisition of critical thinking students have been subsequently able to take up positions of authority within the early years workforce