94 research outputs found
Photocatalytic, antibacterial and anticancer activity of silver-doped zinc oxide nanoparticles
No full textSilver-doped zinc oxide nanoparticles (Ag-ZnO NPs) were successfully synthesized by the Sol-gel method coated with polyethylene glycol as a stabilizing and capping agent. The UV–Vis spectrophotometer analysis was done to analyze the optical property of the nanoparticles. XRD pattern showed the hexagonal structure of ZnO nanoparticles and the reduction in the intensity of the peaks of Ag-ZnO NPs indicates the incorporation of Ag+ ions in the ZnO lattices. The surface structural properties of the NPs were confirmed by Field Emission Scanning Electron Microscope (FE-SEM), High Resolution Transmission Electron Microscopy (HRTEM) and Selected Area Electron Diffraction (SAED). The elemental composition of nanoparticles was confirmed by EDAX and XRF-Spectroscopy. The functional group of ZnO and Ag nanoparticles were determined by FT-IR spectroscopy. The photocatalytic activity of Ag-ZnO NPs was studied against ponceau and the maximum degradation percentage was observed to be 89% at 140 min. Further, Ag-ZnO NPs unveiled high potent antibacterial activity against the selected bacterial pathogens and it also rendered significant anticancer activity in UVB-induced HaCaT cells. Consequently, the fluorescent microscopic analysis confirmed the increasing Reactive Oxygen Species (ROS) generation and Mitochondrial Membrane Potential (MMP) loss in the HaCaT cells that leads to the apoptosis induction. Hence, the selected combination of nanoparticles has proven to exhibit higher photocatalytic, antibacterial and anticancer activity. In the near future, it could be an efficient tool for eradicating the dye pollution from wastewater and also preferably be utilized in the cosmetics and pharmaceutical industries to prevent skin cancer
Pressure fluctuations in centrifugal compressor diffusers
No full textThe unstable flow phenomenon like rotating stall and surge in centrifugal compressors occur at very low flow rates. These would cause unduly large vibrations in the turbo- machinery components and results in mechanical failure. It is important to detect this phenomenon and avoid it by means of early warning systems. An attempt has been made in this paper to study the pressure fluctuations using high frequency miniature transducers in vane and vaneless diffusers of a centrifugal compressor. The unstable nature of the flow is characterized. The observation from the measurements indicate the pressure fluctuations in the vane diffusers are getting amplified and carried to the exit of the diffuser whereas in the case of vaneless diffuser such a phenomena is not observed. The flow near the leading edge of diffuser plays an important role in diffuser performance. The unsteady pressure fluctuations in the diffuser are characterized in terms of instability parameter at various locations in the diffuser. The location where such an instability parameter is sensitive to the flow coefficient is identified as the diffuser throat. Through this instability parameter it is possible to provide early warning just before compressor goes into stall. (Author
Virtual environments and autism: a developmental psychopathological approach
No full textIndividuals with autism spectrum disorders supposedly have an affinity with ICT, making it an ideally suited media for this population. Virtual environments (VEs) – both two dimensional and immersive – represent a particular kind of ICT that might be of special benefit. Specifically, this paper discusses the importance of psychological theory for VE designed for this population. I describe the contribution that different theories of autism (e.g., theory of mind, executive function, weak central coherence theory) have made and can make, as well as the potential of other non-autism-specific theories (e.g., embodied cognition). These technologies not only illuminate our understanding of autism, but they can also be used to develop new technologies for people without autism. So, as well as being an area of specialism, I argue that VE research in autism has extended – and will go onto – the boundaries of human–computer interaction more generally. This is because autism provides a unique window into human social communication and learning. Further, this field offers a chance for better inclusivity for individuals with autism within a digital society
Luxury as a Driver for New Urban Identities in Milan: Geographies, Spatial Practices, and Open Questions
No full textIn contemporary cities, the role of capital and private investors who finance interventions in the field of urban regeneration has become an increasingly important catalyst for the physical and social impacts of these transformations. This paper aims to point out the role of urban projects developed by luxury companies or stakeholders in consolidated urban regions. Starting by analysing the spatial distribution of luxury firms in Milan and composing a tentative classification system based on a variety of case studies, the author proposes a mental map of spaces shaped, occupied, transformed and infected by the sector within the contemporary metropolis. The resulting network of urban places sprawls out not only across centralized areas, but also in peripheral neighbourhoods, which interact with existing contexts, spatial and economic relationships as well as evident and hidden flows. From this basis, the contribution reflects on a set of luxury-driven practices and their impacts on urban identities. The reflection includes the role played by media technologies in these transformations and in the study of their development. The conclusions then discuss the role of luxury; whether it transforms the physical form of our city (its shape and patterns) or rather influences processes of transformation
Effet signal d'une réduction promotionnelle du prix : concept et expérimentation.
No full textL'effet observé à court terme d'une réduction promotionnelle du prix sur la demande est souvent positif du fait de la valorisation des bénéfices offerts par la promotion et par le simple effet signal engendré par la communication promotionnelle. Lorsque le consommateur effectue une évaluation approfondie de l'offre promotionnelle et qu'il manque d'informations (sur le montant de la réduction ou le prix de base), l'information transmise par la promotion, qui est à la source de l'effet signal, est aussi utilisée pour élaborer le cadre du choix. Un conflit entre la cherté perçue et le signal promotionnel peut donc dévaloriser une offre. Dans ces conditions, nous montrons, par l'analyse des résultats d'une expérimentation sur 320 consommateurs, que le changement du cadre du choix résultant d'une offre promotionnelle conduit à un rejet d'achat plus important d'une marque premium pour un produit de grande consommation. Si ce résultat d'un effet négatif d'une réduction promotionnelle du prix sur la demande à court terme est rarement observé sur les ventes, il doit cependant conduire les managers à anticiper une baisse de l'efficacité promotionnelle lorsque la réduction de prix n'est pas indiquée et à en limiter l'usage pour les marques premium.Signaling effect of a promotional price reduction: concept and experimentation Abstract Sales promotion has often positive effects on short term demand effects due to the benefits provided and to the signaling effect of the communication. If information is missing (regular price, price reduction) when consumers have an extended choice process, the information transmitted by the sales promotion communication is used not only as a signal but also to elaborate the choice frame. Thus conflicting information between the promotional signal and perceived expensiveness can reduce perceived value. Under these conditions the author show, through analysis of experimental data on 320 consumers, that changes due to a promotional price reduction can result in higher rejection for a premium brand in a consumer good market. While decreases in sales volume due to promotional price reductions are not frequently observed, such a possibility means that managers have to anticipate a reduction of their promotional effectiveness when price reduction is not indicated (special offer) and to avoid its use for premium brands. Key words: Sales promotion, price reduction, promotion signal, experiment, Gabor & Granger.Gabor et Granger; Promotion des ventes; Réduction de prix; Effet signal; Expérimentation;
K-core of co-author network (k = 10).
No full text<p>The size of the node denotes the number of papers and the thickness of interconnecting lines (edges) denotes the number of co-authored papers between the authors. Authors having 10 or more co-author links during the study period have been visualized.</p
Regional distribution of woman and man first and last author.
No full textRegional distribution of woman and man first and last author.</p
Reflecting on a tertiary educator’s implementation of a project-based flipped classroom: A repertory grid analysis
No full textGrid-based reflection: This report outlines how the authors used repertory grid findings in their collaborative reflective practice in vocational education in a tertiary setting. Second author (SA), Dileep Rajendran, invited first author (FA), Willfred Greyling, to track his implementation of a project-based flipped classroom in an Information Technology module.
Pedagogy: The course design was based on the following principles associated with project-based flipped classrooms:
• Acknowledge learners’ current and potential skill: The teaching had to be pitched at a level where learners’ current competence would be an adequate stepping stone to elaborate their knowledge and skill through inquiry-based learning .
• Specify classroom participants’ responsibilities in inquiry-based learning: The tutor’s role would be to structure inquiry-based learning projects and learning spaces where learners took optimal responsibility for their learning.
• Design and enact learning that develops learner autonomy: The target would be to promote learner autonomy and their ability to reason and act in the IT networking field.
Observer interests: The observer’s interests include classroom observations as third-party accounts of interactively accomplished learning, and repertory grid use as a means to assist educators in exploring their pedagogical thinking and doing.
Eliciting pedagogical constructs, grid design and application: Following two classroom observations and reflective dialogues on both observations, we agreed to elicit SA’s constructs for a repertory grid (see Appendix A). Following the difference method (Fransella, Bell and Bannister, 2004), we used 10 elements to elicit 10 constructs. After crafting the formulations until SA felt they best represented his meaning-making lenses, we used a 7-point rating scale in our grid design, and followed guide-lines for scale conversion, pole reversals, and reverse scoring (Fransella, et al., 2004) to enhance the validity of our process.
Complex interactions among an educator’s pedagogical constructs: Our purpose was to unpack SA’s pedagogical meaning-making at a level beyond discrete lists of bipolar constructs: we intended to show a deeper level of analysis, namely, that educators’ constructs do not function in isolation, rather, they form complex patterns within the individual’s meaning-making. To explore these patterns, we performed principal components analysis (PCA) and cluster analysis (CA) on SA’s ratings which yielded two components and a dendrogram. These, together with the correlations among constructs, became prompts for making sense of the varying levels of association among SA’s constructs.
Triangulation: Following Viney and Nagy (2012), we triangulated our collaborative account of the repertory grid findings against two classroom observations and informal input from participating students. The observations highlighted how SA implemented the principles and practices of a project-based flipped classroom, specifically the principles referred to above. We also elicited informal input from the participating learners. A selection of comments is included.
Findings: We found that
• the tutor’s role remained significant as a designer of learning experiences and a guide to learners to develop problem-solving strategies. These strategies avoided transmission-based exchanges; rather, they consistently ensured learner engagement and learner-centred practice.
• In project-based flipped classrooms, the tutor has a significant role, designing tasks, re-defining both his own and learners’ roles, as well as retaining an inquiry-based approach when barriers occur in the learning.
Conclusions: We concluded that our grid use
• allowed both authors to reflect on SA’s implementation of a project-based flipped classroom, capturing an account of SA’s thinking and doing associated with his teaching practices (classroom observations).
• gained in meaningfulness when we triangulated these findings against student perceptions which showed that although they found the learner-centred role and the tutor’s deliberately limited project information (step-by-step outlines) challenging, they understood the purpose and the approach.
• exposed the tip of the iceberg: much more could be extracted from the grid, especially when the grid was transposed and elements analysed.
• identified an agenda for continued reflection, for example, how to manage the ratio of teacher mediation and learner-centred activity; and the deliberateness of tutor strategies to enact learner-centred approaches
Design of an Energy-Efficient Interface Circuit for a MEMS-based Capacitive Pressure Sensor
No full textThis thesis presents an incremental ?? capacitance-to-digital converter (CDC) that serves as an interface circuit for a MEMS-based pressure sensor. The thesis presents a systematic analysis of the CDC and compares different CDC architectures. A novel non-linear CDC is also proposed and analysed. Energy-efficiency of the CDC is improved by implementation of various design techniques like double sampling, system-level chopping and a novel inverter-based OTA. The CDC has been designed in such a way that it can operate with either an on-chip or external pressure sensor. The CDC can be tuned to compensate for a wide range of baseline capacitance. The CDC operates over a pressure range of 0-1.3 bar and achieves a pressure resolution of 1e?5 bar (equivalent to a resolution of 16 bits). The CDC is implemented in NXP 0.16?m 1P6M technology. The circuit design and layout of the CDC are presented. The CDC consumes 2.33?A from a 1.2V supply resulting in an energy consumption of only 2.01nJ, a significant improvement over the state-of-the-art.Microelectronics & Computer EngineeringElectrical Engineering, Mathematics and Computer Scienc
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