Phaseguide-assisted blood separation microfluidic device for point-of-care applications

We propose a blood separation microfluidic device suitable for point-of-care (POC) applications. By utilizing the high gas permeability of polydimethylsiloxane (PDMS) and phaseguide structures, a simple blood separation device is presented. The device consists of two main parts. A separation chamber with the phaseguide structures, where a sample inlet, a tape-sealed outlet, and a dead-end ring channel are connected, and pneumatic chambers, in which manually operating syringes are plugged. The separation chamber and pneumatic chambers are isolated by a thin PDMS wall. By manually pulling out the plunger of the syringe, a negative pressure is instantaneously generated inside the pneumatic chamber. Due to the gas diffusion from the separation chamber to the neighboring pneumatic chamber through the thin permeable PDMS wall, low pressure can be generated, and then the whole blood at the sample inlets starts to be drawn into the separation chamber and separated through the phaseguide structures. Reversely, after removing the tape at the outlet and manually pushing in the plunger of the syringe, a positive pressure will be created which will cause the air to diffuse back into the ring channel, and therefore allow the separated plasma to be recovered at the outlet on demand. In this paper, we focused on the study of the plasma separation and associated design parameters, such as the PDMS wall thickness, the air permeable overlap area between the separation and pneumatic chambers, and the geometry of the phaseguides. The device required only 2 μl of whole blood but yielding approximately 0.38 μl of separated plasma within 12 min. Without any of the requirements of sophisticated equipment or dilution techniques, we can not only separate the plasma from the whole blood for on-chip analysis but also can push out only the separated plasma to the outlet for off-chip analysis.     

Compositional question answering: A divide and conquer approach

This paper describes how questions can be characterized for question answering (QA) along different facets and focuses on questions that cannot be answered directly but can be divided into simpler ones so that they can be answered directly using existing QA capabilities. Since individual answers are composed to generate the final answer, we call this process as compositional QA. The goal of the proposed QA method is to answer a composite question by dividing it into atomic ones, instead of developing an entirely new method tailored for the new question type. A question is analyzed automatically to determine its class, and its sub-questions are sent to the relevant QA modules. Answers returned from the individual QA modules are composed based on the predetermined plan corresponding to the question type. The experimental results based on 615 questions show that the compositional QA approach outperforms the simple routing method by about 17%. Considering 115 composite questions only, the F-score was almost tripled from the baseline.     

Droplet-based microfluidic washing module for magnetic particle-based assays

In this paper, we propose a continuous flow droplet-based microfluidic platform for magnetic particle-based assays by employing in-droplet washing. The droplet-based washing was implemented by traversing functionalized magnetic particles across a laterally merged droplet from one side (containing sample and reagent) to the other (containing buffer) by an external magnetic field. Consequently, the magnetic particles were extracted to a parallel-synchronized train of washing buffer droplets, and unbound reagents were left in an original train of sample droplets. To realize the droplet-based washing function, the following four procedures were sequentially carried in a droplet-based microfluidic device: parallel synchronization of two trains of droplets by using a ladder-like channel network; lateral electrocoalescence by an electric field; magnetic particle manipulation by a magnetic field; and asymmetrical splitting of merged droplets. For the stable droplet synchronization and electrocoalescence, we optimized droplet generation conditions by varying the flow rate ratio (or droplet size). Image analysis was carried out to determine the fluorescent intensity of reagents before and after the washing step. As a result, the unbound reagents in sample droplets were significantly removed by more than a factor of 25 in the single washing step, while the magnetic particles were successfully extracted into washing buffer droplets. As a proof-of-principle, we demonstrate a magnetic particle-based immunoassay with streptavidin-coated magnetic particles and fluorescently labelled biotin in the proposed continuous flow droplet-based microfluidic platform.     

The effect of site quality on repurchase intention in Internet shopping through mediating variables: The case of university students in South Korea

We performed a study to determine the influence that site quality has on repurchase intention of Internet shopping through customer satisfaction, customer trust, and customer commitment. Appropriate measures were developed and tested on 230 university students of Gyeongnam province in South Korea with a cross-sectional questionnaire survey. The results of the empirical analysis confirmed that site quality can be conceptualized as a composite of six dimensions of shopping convenience, site design, information usefulness, transaction security, payment system, and customer communication. Second, site quality positively affected customer satisfaction and customer trust, but did not affect customer commitment and repurchase intention. Third, site quality can affect repurchase intention by enhancing or attenuating customer satisfaction, customer trust, and customer commitment in online transaction situation. The mediating effect of customer satisfaction, customer trust, and customer commitment between site quality and repurchase intention is identified. Fourth, site quality indirectly affected customer commitment through customer satisfaction. Customer satisfaction indirectly affected repurchase intention through customer trust and customer commitment. Thus, it is found that site quality can be a very important factor to enhance repurchase intention in the customer perspective.     

Cultural Differences of Social Network Influence on Romantic Relationships: A Comparison of the United States and South Korea

This study examined the association between social network support and relationship quality of romantic partners among American and Korean college students. As predicted, findings indicated that Americans involve their family and friends more in their romantic relationships and, accordingly, get more support from them for their relationships than Koreans do. However, the results did not support the hypothesis that Koreans would perceive social network support as more important for their romantic relationships. Instead, network importance negatively mediated the effects of social network on relationship quality only for Americans. The positive associations between network support and relationship quality were not differential between the two samples. Implications for culture and close relationships are discussed.     

Development of the Educational and Career Interest Scale in Science, Technology, and Mathematics for High School Students

The Educational and Career Interest scale, a self-report instrument measuring high school students’ educational and career interest in STEM, was developed and validated in two studies conducted during 2010 and 2011. Study 1 included data from 92 high school students, in which exploratory factor analysis (EFA) was conducted with an initial item pool of 20 items. EFA identified three factors: educational and career interest in science, educational and career interest in technology, and educational and career interest in mathematics. Study 2 utilized data from 658 students to revisit the three-factor model using confirmative factor analysis. The two studies provide strong evidence that the scale is both valid and reliable.     

Playing at School: An Inquiry Approach to Using an Experiential Play Lab in an Early Childhood Teacher Education Course

Play is considered an important activity of the early childhood years. Research supports the contribution of play to children’s development, learning, and well-being. In spite of this, time for play is being pushed out in many early childhood programs by greater time allotted to formal instruction in narrow academic skills to be tested eventually by standardized tests. As a result, current preservice teachers are likely to see fewer examples of appropriate time and support for play in their field placements in early childhood settings. The purpose of this study was to document and analyze what happens when an experiential play lab is implemented in an early childhood teacher education program. This qualitative study includes multiple forms of data collection, including two forms of reflective writings and group discussions. After the workshop, preservice teachers made a greater number of references to play in their defense of developmentally appropriate practice, and the nature of their references to play increased in their focus on play process and on teacher roles in children’s play, as compared to prior to the lab. The results of this study of an experiential play intervention support its potential as a means of probing, documenting, and enriching students’ understanding of the importance of providing for and supporting play in classrooms for young children.     

How can we assess and evaluate the competitive advantage of a country’s human resource development system?

The purpose of this study was to develop an index to assess and evaluate the competitive advantage of a country’s human resource development system. Based on an extensive literature review, a theoretical model of a human resource development system at the national level (named National Human Resource Development: NHRD) was constructed. The model consists of four factors—supply conditions, demand conditions, environment, and supporting systems—and NHRD system competitiveness was measured by the cumulative sum of a country’s achievement in each of these four factors. The four factors were divided into 10 sub-categories, and 45 indicators were selected based on criteria such as relevance, international comparability, reliability, timeliness, and accessibility. Finally, by using the Analytic Hierarchy Process, the individual weights of the 45 indicators were calculated. In addition, the relationships between the NHRD competitiveness scores of OECD member countries and other relevant variables, including GDP per capita and the scores from other national competitiveness studies, were analyzed to examine the validity of the index.