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A general optimization approach for contact-separation triboelectric nanogenerator
No full textTriboelectric nanogenerator (TENG) is a kind of mechanical energy harvesters based on triboelectric effect. Its output performance strongly depends on the structural design, material properties, circuit status, and mechanical loading process. In this work, we develop a new theoretical method for analysing the contact-separation mode TENG devices with dimensionless formulations which are based on the V-Q-x relationship with the TENG being treated as a parallel-plate capacitor. The correctness and accuracy of the proposed method and model are verified and validated via a series of experimental results. With the proposed method, the scaling laws between the performance and structure, material properties, circuit status and mechanical loading are established, and the output performance of the devices can be predicted with all the parameters being considered simultaneously. The developed model and formulas offer good guidance for structural design and optimization strategies for TENG devices, which could lead to the fast development of high performance of TENGs through accurate numerical analysis at low cost.
Validation of the scaling laws for dimensionless maximum voltage of contact mode triboelectric nanogenerator (TENG). The theoretical predictions based on the proposed dimensionless formulars agree very well with the experimental measurements despite that the latter are achieved with different device structures, mechanical loadings and circuit conditions. This demonstrates that the established scaling law reveals the underlying general correlation between the physical properties of the device and its output performance, which may provide robust guidelines for optimization strategies of contact mode TENG. [Display omitted]
•An optimization method based on multi-parameter analysis is proposed for TENG.•A scaling law is established between the output performance and device parameters.•All parameters could be designed simultaneously to enhance the output performance
Surface‐Acoustic‐Wave‐Based Lab‐on‐Chip for Rapid Transport of Cryoprotectants across Cell Membrane for Cryopreservation with Significantly Improved Cell Viability
No full textCryopreservation is essential to effectively extend the shelf life of delicate biomaterials while maintaining proper levels of cell functions. Cryopreservation requires a cryoprotective agent (CPA) to suppress intracellular ice formation during freezing, but it must be removed prior to clinical use due to its toxicity. Conventional multistep CPA loading and unloading approaches are time consuming, often creating osmotic shocks and causing mechanical injuries for biological samples. An efficient surface‐acoustic‐wave‐ (SAW‐) based lab‐on‐a‐chip (LoC) for fast loading and removal of CPAs is presented here. With the SAW‐based multistep CPA loading/removal approach, high concentration (3 m) CPA can be successfully loaded and removed in less than 1 min. Results show that the technique causes the least harm to umbilical cord matrix mesenchymal stem cells as compared to conventional method, and an average of 24% higher cell recovery rate is achieved, while preserving the integrity and morphology of the cells. This device is the first of its kind to combine high loading/unloading efficiency, high cell viability, and high throughput into one LoC device, offering not only a more efficient and safer route for CPA loading and removal from cells, but also paving the way for other cryopreservation‐dependent applications.
Cryopreservation is essential to extend the shelf life and functions of cells. In this article, a surface‐acoustic‐wave‐ (SAW‐) based lab‐on‐a‐chip for ultrafast loading and removal of cryoprotective agent (CPA) from cells is presented, which achieves CPA loading/unloading in about 1 min with about 24% higher cell viability than the traditional method
Flexible dual-mode surface acoustic wave strain sensor based on crystalline LiNbO3 thin film
No full textThis work presents the development of flexible dual-mode surface acoustic wave (SAW) sensor based on single crystalline thin film lithium niobate (TF-LN). Numerical modeling is conducted to investigate the SAW propagation and the effects on strain sensitivity. The dependence of strain sensitivity on angles between the applied strain and SAW propagation direction is analyzed numerically and experimentally, showing that the maximum strain sensitivity is at 45° rather than longitudinal direction. 128° Y-cut TF-LN (~50 µm), obtained by micromachining technique, is utilized as the piezoelectric substrate to fabricate the SAW strain sensors with dual-mode, namely Rayleigh mode and thickness shear mode. The sensor has excellent flexibility and demonstrates remarkable capability for an ultra-wide range strain measurement up to ±3000 . Temperature effects on resonant frequency and strain sensitivity are investigated in the range of 25 °C-100 °C, and similar temperature characteristics are observed for the dual modes. A method of beat frequency between the dual modes is introduced which is able to eliminate the temperature effect on strain sensing, an on-chip temperature influence removing capability. All the results clearly show that this sensor exhibits great potential for applications in flexible electronics and microsystems
Students as Partners in Redesigning and Delivery of the Curriculum
No full textStudent-Staff Partnership (SSP) encapsulates the pedagogy of teaching and learning in various settings through student-staff reciprocal partnership practices in the Higher Education (HE)sector. The application of SSP for successful redesigning and delivery of the curriculum can be traced across various disciplines in a number of pedagogical contexts. This paper narrates a case study of how educators can partner with first year undergraduate students to redesign and deliver an existing module curriculum through co-creation of e-learning materials for teaching and learning. It also exemplifies how readily accessible digital applications can be used in order to develop students’ digital literacy skills and promote inquiry based learning in the process.An action research project was undertaken to assess the benefits of including specific digital applications in the curriculum in order to promote learners’ digital literacy skills. The impact of SSP as an approach for curriculum redesign, delivery and as a facilitator of research and inquiry skills in undergraduate students was also evaluated in the process through the co-creation of e-learning materials. A focus group was conducted to capture participants’ responses and thematic content analysis was undertaken for data analysis. Findings suggests, using digital applications for co-creation of e-learning materials improved learners’ confidence in embracing and using digital applications for learning, communication and dissemination of evidence based information through the process of inquiry and research based learning. Additionally, students found SSP effective as an approach for redesigning the curriculum since it provides a platform to capture students’ expectations of the use of relevant digital applications in the delivery of the curriculum to facilitate learners’ digital literacy skills development processes. Furthermore, through this project a large database of co-created e-learning materials were generated which were integrated into the module for blended learning and future re-purpose in the delivery of the curriculum
Book Reviews
No full textExist to Resist, by Matthew Smith (2017) Bristol: Mattko, 224 pp., ISBN: 978-0-99578-320-1 h/bk, £50
Vox 80–83, Garry O’Neill (ed.) (2019) Dublin: Hi Tone Books, 416 pp., ISBN 978-0-95694-936-3, p/bk, €40
Peepshow, Samantha Bennett (2018) New York: Bloomsbury Academic, 203 pp., ISBN 978-5-0132-186-3, p/bk, £12.99
Burning Down the Haus: Punk Rock, Revolution and the Fall of the Berlin Wall, Tim Mohr (2018) Chapel Hill, NC: Algonquin Books, 363 pp., ISBN 978-1-61620-843-1, h/bk, £28.0
Positive psychology for depression: a critical review
No full textBackground Positive psychology has become a popular approach to psychology. Aim To evaluate the approach of positive psychology in dealing with depression and the strength of empirical research in the area. Method A comprehensive search was conducted using the search engines and databases: Scopus, Google Scholar, PsycARTICLES and ProQuest Central. Results were then screened. Results The ten reviewed studies indicate that the positive psychology approach is effective in treating depression and reducing symptoms. However, issues to be addressed include the need to integrate it with other approaches and how long it takes. Discussion The review highlights the effectiveness of positive psychology approaches and summarises the positives and negatives of the empirical research presented. Conclusion Positive psychology has clear, effective treatment methods that present benefits for the individual. However, the methods of treatment may be more time consuming and need more commitment from the individual than more traditional methods
Design and characterisation of bicomponent polyamide 6 fibres with specific locations of each flame retardant component for enhanced flame retardancy
No full textBicomponent filaments of polyamide 6 (PA6) were produced with core/sheath geometries containing aluminium diethyl phosphinate (AlPi), and/or a montmorillonite nanoclay located individually or together in the sheath or core. A characterisation protocol based on thermogravimetric analysis (TGA) under both flowing air and nitrogen and pyrolysis combustion flow calorimetry (PCFC) enabled the effects of AlPi, clay and atmospheric oxygen to be assessed on PA6 thermal degradation. Knitted fabrics were assessed for flammability by vertical strip testing, which demonstrated that the relative location of the clay and flame retardant has a significant effect on burning behaviour. Correlation of the TGA/DTG, PCFC and burning sample results were discussed in terms of the effects of the roles of atmospheric oxygen and flame retardant components on the thermal degradation of PA6, especially when located in the sheath
Answer the Question : Voice training, habitus and political intervention
No full textVoice training, in the right context, can be a tool of political intervention and a tool of resistance to social, cultural and economic structures. Voice training can be repurposed from a practice of individual pedagogy and personal transformation (both for professional and personal reasons) to an instrument of social and political purpose