A microfluidic platform for studying the effects of small temperature gradients in an incubator environment     

Sarit K. Das  Seok Chung  Ioannis Zervantonakis  Joseph Atnafu    Roger D. Kamm 《Biomicrofluidics》2008,2(3)

Studies on the effects of variations in temperature and mild temperature gradients on cells, gels, and scaffolds are important from the viewpoint of biological function. Small differences in temperature are known to elicit significant variations in cell behavior and individual protein reactivity. For the study of thermal effects and gradients in vitro, it is important to develop microfluidic platforms which are capable of controlling temperature gradients in an environment which mimics the range of physiological conditions. In the present paper, such a microfluidic thermal gradient system (μTGS) system is proposed which can create and maintain a thermal gradient throughout a cell-seeded gel matrix using the hot and cold water supply integrated in the system in the form of a countercurrent heat exchanger. It is found that a uniform temperature gradient can be created and maintained in the device even inside a high temperature and high humidity environment of an incubator. With the help of a hot and cold circuit controlled from outside the incubator the temperature gradient can be regulated. A numerical simulation of the device demonstrates the thermal feature of the chip. Cell viability and activity under a thermal gradient are examined by placing human breast cancer cells in the device.  相似文献   

Learning from Singapore: the power of paradoxes     

Connie K. Chung 《Asia Pacific Journal of Education》2018,38(2):271-272

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Variable‐Length Computerized Adaptive Testing Using the Higher Order DINA Model          下载免费PDF全文

Chia‐Ling Hsu  Wen‐Chung Wang 《Journal of Educational Measurement》2015,52(2):125-143

Cognitive diagnosis models provide profile information about a set of latent binary attributes, whereas item response models yield a summary report on a latent continuous trait. To utilize the advantages of both models, higher order cognitive diagnosis models were developed in which information about both latent binary attributes and latent continuous traits is available. To facilitate the utility of cognitive diagnosis models, corresponding computerized adaptive testing (CAT) algorithms were developed. Most of them adopt the fixed‐length rule to terminate CAT and are limited to ordinary cognitive diagnosis models. In this study, the higher order deterministic‐input, noisy‐and‐gate (DINA) model was used as an example, and three criteria based on the minimum‐precision termination rule were implemented: one for the latent class, one for the latent trait, and the other for both. The simulation results demonstrated that all of the termination criteria were successful when items were selected according to the Kullback‐Leibler information and the posterior‐weighted Kullback‐Leibler information, and the minimum‐precision rule outperformed the fixed‐length rule with a similar test length in recovering the latent attributes and the latent trait.  相似文献   

The Use of Think-Aloud to Evaluate a Navigation Structure for a Multimedia Health and Wellness Application for Older Adults and Their Caregivers     

Jane Chung  Shomir Chaudhuri  Thai Le  Nai-Ching Chi  Hilaire J. Thompson  George Demiris 《Educational gerontology》2015,41(12):916-929

Despite the increasing use of health information technologies (HITs) for older adults living in the community and their caregivers, few have been rigorously evaluated for usability by the end users. Think-aloud protocols are a relatively easy method for both clinicians and researchers to use with older adults and those therapists that work with them to provide such an evaluation. In the present report, we provide an exemplar using this method in order to evaluate the usability of a health and wellness technology tool designed for older adults and caregivers. In addition, we discuss methodological and practical considerations for others interested in this approach. The methodology described in this study is easy and practical to undertake, and it can be effectively conducted by researchers and clinicians to find usability issues related to HITs for older adults and their caregivers.  相似文献   

International comparison and educational policy learning: looking north to Finland     

Jennifer Chung 《Compare》2015,45(3):475-479

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Improving the dielectric properties of an electrowetting-on-dielectric microfluidic device with a low-pressure chemical vapor deposited Si3N4 dielectric layer     

Hsien-Hua Shen  Lung-Yuan Chung  Da-Jeng Yao 《Biomicrofluidics》2015,9(2)

Dielectric breakdown is a common problem in a digital microfluidic system, which limits its application in chemical or biomedical applications. We propose a new fabrication of an electrowetting-on-dielectric (EWOD) device using Si₃N₄ deposited by low-pressure chemical vapor deposition (LPCVD) as a dielectric layer. This material exhibits a greater relative permittivity, purity, uniformity, and biocompatibility than polymeric films. These properties also increase the breakdown voltage of a dielectric layer and increase the stability of an EWOD system when applied in biomedical research. Medium droplets with mouse embryos were manipulated in this manner. The electrical properties of the Si₃N₄ dielectric layer—breakdown voltage, refractive index, relative permittivity, and variation of contact angle with input voltage—were investigated and compared with a traditional Si₃N₄ dielectric layer deposited as a plasma-enhanced chemical vapor deposition to confirm the potential of LPCVD Si₃N₄ applied as the dielectric layer of an EWOD digital microfluidic system.  相似文献   

Note from the Executive Editor     

Pak Tee Ng 《Educational Research for Policy and Practice》2014,13(1):1-1

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Traceable clonal culture and chemodrug assay of heterogeneous prostate carcinoma PC3 cells in microfluidic single cell array chips     

Jaehoon Chung  Patrick N. Ingram  Tom Bersano-Begey  Euisik Yoon 《Biomicrofluidics》2014,8(6)

Cancer heterogeneity has received considerable attention for its role in tumor initiation and progression, and its implication for diagnostics and therapeutics in the clinic. To facilitate a cellular heterogeneity study in a low cost and highly efficient manner, we present a microfluidic platform that allows traceable clonal culture and characterization. The platform captures single cells into a microwell array and cultures them for clonal expansion, subsequently allowing on-chip characterization of clonal phenotype and response against drug treatments. Using a heterogeneous prostate cancer model, the PC3 cell line, we verified our prototype, identifying three different sub-phenotypes and correlating their clonal drug responsiveness to cell phenotype.  相似文献   

Book Review     

Ng Pak Tee 《Asia Pacific Journal of Education》2004,24(2):225-227

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Cultivating revolutionary successors in the Chinese communes through open‐door education     

Pedro Pak‐Tao Ng 《Cambridge Journal of Education》1979,9(1):23-35

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