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.     

Size-dependent trajectories of DNA macromolecules due to insulative dielectrophoresis in submicrometer-deep fluidic channels

In this paper, we demonstrate for the first time that insulative dielectrophoresis can induce size-dependent trajectories of DNA macromolecules. We experimentally use λ (48.5 kbp) and T4GT7 (165.6 kbp) DNA molecules flowing continuously around a sharp corner inside fluidic channels with a depth of 0.4 μm. Numerical simulation of the electrokinetic force distribution inside the channels is in qualitative agreement with our experimentally observed trajectories. We discuss a possible physical mechanism for the DNA polarization and dielectrophoresis inside confining channels, based on the observed dielectrophoresis responses due to different DNA sizes and various electric fields applied between the inlet and the outlet. The proposed physical mechanism indicates that further extensive investigations, both theoretically and experimentally, would be very useful to better elucidate the forces involved at DNA dielectrophoresis. When applied for size-based sorting of DNA molecules, our sorting method offers two major advantages compared to earlier attempts with insulative dielectrophoresis: Its continuous operation allows for high-throughput analysis, and it only requires electric field strengths as low as ∼10 V∕cm.     

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 de/politicization of pronouns: implications of the No Big Deal Campaign for gender-expansive educational policy and practice

ABSTRACT

Accommodating non-binary transgender people, many of whom use gender-neutral pronouns, poses a unique challenge to schools and universities, even in contexts with legal protections for transgender rights. This article explores a recent Canadian controversy around gender-neutral pronouns, and assembles a theoretical framework to analyze the argument that legal protection for transgender peoples’ pronouns poses a threat to ‘free speech.’ The framework bridges queer theory, affect theory and Deleuzo-Guattarian assemblage theory to propose a threshold between ‘extra’ and ‘excessive’ effort to accommodate social difference in everyday life. Free speech objections produce some peoples’ pronouns as requiring ‘excessive’ effort. This extra/excessive framework was exemplified by a recent Canadian social media campaign that sought to produce transgender peoples’ pronouns as requiring merely ‘extra’ effort, which entails de-politicizing pronouns. Community responses to the campaign carry significant implications for gender-expansive educational policy and practice.     

Self-concept of students in higher education: are there differences by faculty and gender?

Many studies examine student self-concept during compulsory schooling but few have explored the self-concept of students in higher educational settings. The current study examined self-concept by faculty and gender among higher education students in New Zealand. Participants were 929 undergraduate students from a large New Zealand university. The results showed some differences in verbal and maths self-concept by faculty. Generally, students in faculties teaching subjects more reliant on maths skills had higher maths self-concept than those in faculties where facility in verbal skills was important. The opposite results were found for verbal self-concept. No overall gender differences were found for general, academic, verbal and maths self-concept although a statistically significant difference was found for problem-solving self-concept. This finding suggests students’ choice of faculty may be based on perceptions of their skills and capabilities in the various fields, irrespective of gender.     

Leadership of older adults’ service learning in Taiwan: a qualitative study

ABSTRACT

In Taiwan, there are service learning programs organized by older adult educational institutions that are held in high esteem. Director leadership plays a key role in the effectiveness of such institutions, and the leadership experiences of such directors in guiding service learning are worth exploring. This study conducted a qualitative approach and selected directors from eight Active Aging Learning Centers (AALCs) who achieved outstanding leadership effectiveness to take part in one-on-one and in-depth semi-structured interviews. The results indicated that: 1. Directors infused the entire service learning process with inspirational motivation by adopting through individualized consideration as a starting point. 2. When directors led the preparation process for service learning, they focused on inducing intellectual stimulation among the older adult learners, such that they felt empowered and capable of providing community services. 3. During the community service phase, directors practiced a form of leadership characterized by idealized influence to encourage, accompany, and support the elderly while they engaged in service learning. 4. The dilemma faced by directors was dissatisfaction with the leadership. Directors responded by reminding them of their original service learning intention and downplaying issues, which made the service learning group undergo a positive transformation. 5. The results of directors’ leadership had a positive effect on the community as it led to more dynamism and more people participating in community service.