Release monitoring of single cells on a microfluidic device coupled with fluorescence microscopy and electrochemistry

A method for monitoring the biological exocytotic phenomena on a microfluidic system was proposed. A microfluidic device coupled with functionalities of fluorescence imaging and amperometric detection has been developed to enable the real-time monitoring of the exocytotic events. Exocytotic release of single SH-SY5Y neuroblastoma cells was studied. By staining the cells located on integrated microelectrodes with naphthalene-2,3-dicarboxaldehyde, punctuate fluorescence consistent with localization of neurotransmitters stored in vesicles was obtained. The stimulated exocytotic release was successfully observed at the surface of SH-SY5Y cells without refitting the commercial inverted fluorescence microscope. Spatially and temporally resolved exocytotic events from single cells on a microfluidic device were visualized in real time using fluorescence microscopy and were amperometrically recorded by the electrochemical system simultaneously. This coupled technique is simple and is hoped to provide new insights into the mechanisms responsible for the kinetics of exocytosis.     

Mixing enhancement in microfluidic channel with a constriction under periodic electro-osmotic flow

We present a new approach to enhance mixing in T-type micromixers by introducing a constriction in the microchannel under periodic electro-osmotic flow. Two sinusoidal ac electric fields with 180° phase difference and similar dc bias are applied at the two inlets. The out of phase ac electric field induces oscillation of fluid interface at the junction of the two inlet channels and the constriction. Due to the constriction introduced at the junction, fluids from these two inlets form alternative plugs at the constricted channel. These plugs of fluids radiate downstream from the constriction into the large channel and form alternate thin crescent-shaped layers of fluids. These crescent-shaped layers of fluids increase tremendously the contact surface area between the two streams of fluid and thus enhance significantly the mixing efficiency. Experimental results and mixing mechanism analysis show that amplitude and frequency of the ac electric field and the length of the constriction govern the mixing efficiency.     

Problem-based learning and the development of metacognition

This study samples first year undergraduates from two programmes at a Hong Kong University (N = 66). One programme uses an entirely problem-based approach to learning and teaching, whilst the other uses more traditional methods. Using the Learning and Study Strategies Inventory (LASSI) as a measure of student perceptions of their thinking, or metacognition it explores differences in metacognitive development between each group of students between the beginning and end of their first year in each programme. The paper argues that, in addition to the formal learning context, everyday challenges emerging from the additional new social contexts provided by problem-based curricula provide fertile environments for the development of metacognition because whilst the highest ‘meta-level’ of cognition is usually not implicated when we receive an outside task and when the task solution is known, the meta-level does tend to be consulted when things go wrong or when the situation is new. In other words, when we are faced with finding solutions to a problem whether posed by the teacher as part of a problem-based curriculum or a new social environment, we are more likely to develop generic, as well as subject specific skills.     

Issues of cultural appropriateness and pedagogical efficacy: exploring peer review in a second language writing class

This paper reports on a study designed to investigate (a) whether peer review is an effective pedagogical activity with adult Chinese students in the teaching of second language (L2) academic writing and (b) how factors such as perceptions of the influence of peer reviewers’ L2 proficiency, previous experience with peer review, feedback preferences, and culturally-based beliefs and practices relate to the effectiveness of the pedagogical activity. Participants were 20 English-as-an-L2 learners from China who were enrolled in an academic writing class for postgraduate students at a Singaporean university. Data included first drafts of an academic writing assignment, written peer comments, revised drafts of the assignment, responses to a questionnaire, and interviews. Quantitative analyses of the peer comments and revisions to the drafts show that significant improvement in the revised drafts was linked to peer feedback. Further statistical analyses indicate that the learner variables of interest did not affect the effectiveness of the peer review activity. In addition, qualitative analyses of the questionnaire data and the interviews reveal a general acceptance of peer review as a socioculturally appropriate pedagogical activity for Chinese students. The results of the study are interpreted with an understanding of its limitations, and directions for further research are also discussed.     

Microfluidic fabrication of polymeric core-shell microspheres for controlled release applications

We report a facile and robust microfluidic method to fabricate polymeric core-shell microspheres as delivery vehicles for biomedical applications. The characteristics of core-shell microspheres can be precisely and easily tuned by manipulating the microfluidic double emulsion templates. The addition of a shell can significantly improve the versatility as well as functionality of these microspheres as delivery vehicles. We demonstrate that the nature of the shell material plays an important role in the properties of the core-shell delivery vehicles. The release kinetics is significantly influenced by the material of the shell and other characteristics such as the thickness. For example, by adding a poly(lactic-co-glycolic acid) (PLGA) shell to an alginate core, the encapsulation efficiency is enhanced and undesired leakage of hydrophilic actives is prevented. By contrast, adding an alginate shell to PLGA core can lead to a reduction of the initial release rate, thus extending the release period of hydrophobic actives. Microfluidic fabrication enables the generation of precisely controlled core-shell microspheres with a narrow size distribution, which enables the investigation of the relationship between the release kinetics of these microspheres and their characteristics. The approach of using core-shell particles as delivery vehicles creates new opportunities to customize the release kinetics of active ingredients.     

Effect of shoe wearing time and midsole hardness on ground reaction forces,ankle stability and perceived comfort in basketball landing

ABSTRACT

This study examined the effect of wearing time on comfort perception and landing biomechanics of basketball shoes with different midsole hardness. Fifteen basketball players performed drop landing and layup first step while wearing shoes of different wearing time (new, 2-, 4-, 6- and 8-week) and hardness (soft, medium and hard). Two-way ANOVA with repeated measures was performed on GRF, ankle kinematic and comfort perception variables. Increased wearing time was associated with poorer force attenuation and comfort perception during landing activities (p < 0.05). The new shoes had significantly smaller forefoot (2- and 4-week) and rearfoot peak GRF impacts (all time conditions) in drop landing and smaller rearfoot peak GRF impact (6- and 8-week) in layup; shoes with 4-week of wearing time had significantly better perceptions of forefoot cushioning, forefoot stability, rearfoot cushioning, rearfoot stability and overall comfort than the new shoes (p < 0.05). Compared with hard shoes, the soft shoes had better rearfoot cushioning but poorer forefoot cushioning (p < 0.05). Shoe hardness and wearing time would play an influential role in GRF and comfort perception, but not in ankle kinematics. Although shoe cushioning performance would decrease even after a short wearing period, the best comfort perception was found at 4-week wearing time.     

Learning through discussions

Students studying a third‐year e‐commerce subject experienced face‐to‐face and online discussions as an important part of their learning experience. The quality of the students' experiences of learning through those discussions is investigated in this study. This study uses qualitative approaches to investigate the variation in the students' understanding of what they were learning through discussions, and how they went about engaging in them. Quantitative analyses are used to investigate how the students' experience related to their performance. Key outcomes of the study include that the quality of the students' experience of learning through discussions is positively related to their performance and that face‐to‐face and online discussions have qualitatively different benefits for learning.     

Predicting Suicide Risks Among Outpatient Adolescents Using the Family Environment Scale: Implications for Practice and Research

This study was designed to identify characteristics of family functioning that relate to suicide potential in an outpatient adolescent population. Participants included 51 adolescents between the ages of 14 and 18 who were involved in outpatient counselling. The Family Environment Scale and the Suicide Probability Scale were used to assess adolescents’ perception of family social climate and degree of suicide risk respectively. Results revealed significant correlations between suicide risk and family systems characterized by heightened conflict and lower levels of cohesion, independence, and organization. A stepwise multiple regression analysis suggested that organization (related to clarity and structure in family activities and responsibilities) was the strongest predictor of suicide risk. Implications for research and practice are considered.     

Investigating relationships between features of learning designs and student learning outcomes

This article reports a study of eLearning in 21 courses in Hong Kong universities that had a blended design of face-to-face classes combined with online learning. The main focus of the study was to examine possible relationships between features of online learning designs and student learning outcomes. Data-collection strategies included expert reviews of the learning designs, student surveys of perceptions of the web environment and their own learning outcomes, and a SOLO (structure of observed learning outcomes) analysis of assessment evidence of student learning outcomes. The findings of this correlational study indicate mild relationships between features of learning design and student perceptions of their learning outcomes. Both the provision of learning resources and the engagement of students in online communication relate to aspects of learning (acquisition of knowledge and skills, and enhancement of learning motivation). Also, the relationship was stronger when eLearning strategies were more extensively used. However, no relationship was found between learning design and the student performance in assessment tasks, possibly because of the limited assessment data that was examined.