Electrowetting on dielectric driven droplet resonance and mixing enhancement in parallel-plate configuration

This study experimentally verifies that the mixing process in a droplet can be enhanced by driving the droplet at resonant frequencies and at alternating driving frequencies using a parallel-plate electrowetting on dielectric device. The mixing time, which is defined as the time required for reaching the well-mixed state, in a resonant droplet is found to be significantly shorter than that in a non-resonant droplet. Besides, it is also found that a higher driving potential leads to a better mixing effect, especially at resonant frequencies. Furthermore, when a droplet is driven by alternating two driving frequencies, especially two resonant frequencies, the mixing efficiency is found to be significantly enhanced for a specific alternating duration of these two frequencies.     

Resistive pulse sensing of magnetic beads and supraparticle structures using tunable pores

Tunable pores (TPs) have been used for resistive pulse sensing of 1 μm superparamagnetic beads, both dispersed and within a magnetic field. Upon application of this field, magnetic supraparticle structures (SPSs) were observed. Onset of aggregation was most effectively indicated by an increase in the mean event magnitude, with data collected using an automated thresholding method. Simulations enabled discrimination between resistive pulses caused by dimers and individual particles. Distinct but time-correlated peaks were often observed, suggesting that SPSs became separated in pressure-driven flow focused at the pore constriction. The distinct properties of magnetophoretic and pressure-driven transport mechanisms can explain variations in the event rate when particles move through an asymmetric pore in either direction, with or without a magnetic field applied. Use of TPs for resistive pulse sensing holds potential for efficient, versatile analysis and measurement of nano- and microparticles, while magnetic beads and particle aggregation play important roles in many prospective biosensing applications.     

Gravity-oriented microfluidic device for uniform and massive cell spheroid formation

We propose a simple method for forming massive and uniform three-dimensional (3-D) cell spheroids in a multi-level structured microfluidic device by gravitational force. The concept of orienting the device vertically has allowed spheroid formation, long-term perfusion, and retrieval of the cultured spheroids by user-friendly standard pipetting. We have successfully formed, perfused, and retrieved uniform, size-controllable, well-conditioned spheroids of human embryonic kidney 293 cells (HEK 293) in the gravity-oriented microfluidic device. We expect the proposed method will be a useful tool to study in-vitro 3-D cell models for the proliferation, differentiation, and metabolism of embryoid bodies or tumours.     

国产十种乌头的染色体研究

本文描述了我国产毛茛科乌头属的10个种的染色体数目和形态。  根据该属染色体基 数为8(x＝8)，可将这些种归为二倍体、四倍体、六倍体和八倍体种。  10种乌头的染色体在数目、大小、结构上表现出相关性。其中具根状茎而多年生的种多为二倍体，染色体形态较大，第3-7号多为近端着丝点(st)染色体, 具块茎而二年生的种多为多倍体，染色体形态较小，第3-7号多为近中着丝点(sm)染色体。染色体演化方向可能是二倍体→多倍体、大→ 小、st→sm。这进一步证明根状茎种较块茎种原始。根据染色体数目和形态，又可将这些种的染色体分为两类。这进一步支持了目前分类学上的牛扁亚属和乌头亚属的划分。本文还讨论了这些种的有关分类问题。     

Concurrent droplet charging and sorting by electrostatic actuation

This paper presents a droplet-based microfluidic device for concurrent droplet charging and sorting by electrostatic actuation. Water-in-oil droplets can be charged on generation by synchronized electrostatic actuation. Then, simultaneously, the precharged droplets can be electrostatically steered into any designated laminar streamline, thus they can be sorted into one of multiple sorting channels one by one in a controlled fashion. In this paper, we studied the size dependence of the water droplets under various relative flow rates of water and oil. We demonstrated the concurrent charging and sorting of up to 600 droplets∕s by synchronized electrostatic actuation. Finally, we investigated optimized voltages for stable droplet charging and sorting. This is an essential enabling technology for fast, robust, and multiplexed sorting of microdroplets, and for the droplet-based microfluidic systems.     

Reflection on the education policy orientation in post-May 31 reform in Korea

For the last 70 years, since the establishment of the Republic of Korea, Korean education has achieved universal expansion of educational opportunity from elementary to secondary to higher education. Planning, centralized policy making, top-down implementation, and administrative control had been the standards of the first few decades of Korean education. The so-called May 31 education reform implemented in 1995 made a turning point for these approaches to education policy and administration by highlighting autonomy, openness, diversity, accountability, consumer centeredness, market control, and governance for quality education. However, these government-driven education reform initiatives have resulted in limiting the expected outcomes. In this paper, the authors call for a new approach to education policy and administration and propose supporting school innovation, empowering an internal accountability system in governance. The authors also suggest a search for normative values for democratic communitarianism as a new philosophical foundation of education policy framework, beyond instrumental values of education.     

The emerging landscape of school-based professional learning communities in South Korean schools

Abstract

Over the last decade, school-based professional learning communities (PLCs) have emerged as a key feature of the education system in South Korea. To understand this relatively new phenomenon in the context of South Korea, we provide a review of research on school-based PLCs in South Korea and an empirical analysis of the Teaching and Learning International Survey (TALIS) 2008 with a focus on school-based PLCs. Based on our findings from the literature review and analysis of the TALIS, we aim to provide a fuller picture of the emerging landscape of school-based PLCs in South Korean schools. In so doing, we focus on what constitutes school-based PLCs in South Korean schools and how they are similar to and/or different from their counterparts in other countries. Implications for policy, practice, and research are discussed.     

The impact of a professional development model on middle school science teachers' efficacy and implementation of inquiry

This study investigated a professional development model designed to improve teachers' inquiry teaching efficacy as well as the quality of their inquiry instruction through engaging teachers in practice-teaching and reflection sessions. The programme began with a two-week summer Institute focused on both inquiry pedagogy and science content and continued with academic year support for participants' inquiry implementation. An inquiry teaching efficacy instrument was administered 3 times to 25 teacher participants to gauge changes in their personal self-efficacy and outcome expectancy across 5 essential features of classroom inquiry. To examine actual practices, pre/post classroom observations of the teachers' inquiry enactments were evaluated using a quality of inquiry observation protocol. Following the summer Institute, teachers had statistically significant increases in their self-efficacy for teaching inquiry in four of the five essential features and increases in one of the five essential features for outcome expectancy. Teachers' quality of inquiry teaching also increased after the professional development programme. We discuss implications of this PD model for moving teachers towards implementation of new instructional techniques as well as the influence of a supportive school community on teachers’ efficacy with inquiry instruction.     

Understanding silence: an investigation of the processes of silencing in parent–teacher conferences with Somali diaspora parents in Danish public schools

This article questions the dominant understanding that immigrant and refugee parents in parent–teacher conferences are silent because they come from a culture where one does not question the authority of the teacher. Instead, it is argued that they become silent through certain interactional processes. Building on material from an explorative case study of the home–school relations of Somali diaspora families in Danish public schools, the article argues that while these parents have many opinions about their children’s education that they wish to convey, there are institutional and interactional processes in the parent–teacher conference that systematically silence their voices. The understanding of culture as a stable structure that persons are situated within in a top-down manner is thus challenged, arguing that dynamic here-and-now interactions unfolding in a specific practice result in persons becoming, rather than being, silent.     

Teacher collaborative learning through the lesson study: identifying pathways for instructional success in a Singapore high school

Research shows teacher collaborative learning to be a powerful vehicle to mobilise teacher instructional change and pedagogical practices, and to improve student achievement. For such undertakings to have positive impact, understanding the visible features of collaborative structures may not be sufficient to ensure sustainable practice. Instead, there is a need to identify underlying pathways that provide for successful instructional improvement. The purpose of this qualitative study is to obtain deeper insights into teacher outcomes arising from this practice and to identify aspects of the lesson study structure and processes that afford such opportunities. Three subject groups consisting of ten teachers from a Singapore high school participated in this study. Implications on staff development programs will be discussed in the light of these findings.