Optofluidic microvalve-on-a-chip with a surface plasmon-enhanced fiber optic microheater     

Hyun-Tae Kim  Hyungdae Bae  Zhijian Zhang  Abisola Kusimo  Miao Yu 《Biomicrofluidics》2014,8(5)

We present an optofluidic microvalve utilizing an embedded, surface plasmon-enhanced fiber optic microheater. The fiber optic microheater is formed by depositing a titanium thin film on the roughened end-face of a silica optical fiber that serves as a waveguide to deliver laser light to the titanium film. The nanoscale roughness at the titanium-silica interface enables strong light absorption enhancement in the titanium film through excitation of localized surface plasmons as well as facilitates bubble nucleation. Our experimental results show that due to the unique design of the fiber optic heater, the threshold laser power required to generate a bubble is greatly reduced and the bubble growth rate is significantly increased. By using the microvalve, stable vapor bubble generation in the microchannel is demonstrated, which does not require complex optical focusing and alignment. The generated vapor bubble is shown to successfully block a liquid flow channel with a size of 125 μm × 125 μm and a flow rate of ∼10 μl/min at ∼120 mW laser power.  相似文献   

Examination of the role of transient receptor potential vanilloid type 4 in endothelial responses to shear forces     

Sara Baratchi  Francisco J. Tovar-Lopez  Khashayar Khoshmanesh  Megan S. Grace  William Darby  Juhura Almazi  Arnan Mitchell  Peter McIntyre 《Biomicrofluidics》2014,8(4)

Shear stress is the major mechanical force applied on vascular endothelial cells by blood flow, and is a crucial factor in normal vascular physiology and in the development of some vascular pathologies. The exact mechanisms of cellular mechano-transduction in mammalian cells and tissues have not yet been elucidated, but it is known that mechanically sensitive receptors and ion channels play a crucial role. This paper describes the use of a novel and efficient microfluidic device to study mechanically-sensitive receptors and ion channels in vitro, which has three independent channels from which recordings can be made and has a small surface area such that fewer cells are required than for conventional flow chambers. The contoured channels of the device enabled examination of a range of shear stresses in one field of view, which is not possible with parallel plate flow chambers and other previously used devices, where one level of flow-induced shear stress is produced per fixed flow-rate. We exposed bovine aortic endothelial cells to different levels of shear stress, and measured the resulting change in intracellular calcium levels ([Ca²⁺]_i) using the fluorescent calcium sensitive dye Fluo-4AM. Shear stress caused an elevation of [Ca²⁺]_i that was proportional to the level of shear experienced. The response was temperature dependant such that at lower temperatures more shear stress was required to elicit a given level of calcium signal and the magnitude of influx was reduced. We demonstrated that shear stress-induced elevations in [Ca²⁺]_i are largely due to calcium influx through the transient receptor potential vanilloid type 4 ion channel.  相似文献   

Report: The entebbe mathematics project     

Grace Alele Williams 《International Review of Education/Internationale Zeitschrift für Erziehungswissenschaft/Revue internationale l'éducation》1971,17(2):210-214

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A Review of: “Care at the Close of Life: Evidence and Experience. McPhee,Stephen.”     

Grace Gmeindl 《Medical reference services quarterly》2013,32(2):208-209

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Depoliticising Politics: Readings of Theresa Hak Kyung Cha's Dictée     

Hyo Kim 《Changing English: An International Journal of English Teaching》2008,15(4):467-475

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Expert systems: They’re here now     

Kim E. Ruyle 《TechTrends》1989,34(1):41-43

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Reappraisals of the Academy Movement     

Kim Tolley  Nancy Beadie 《History of education quarterly》2001,41(2):216-224

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The Rise of the Academies: Continuity or Change?     

Kim Tolley 《History of education quarterly》2001,41(2):225-239

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Universities and the humanities,then and now     

SunHee Kim Gertz 《Journal of Further & Higher Education》2017,41(6):844-856

Over the centuries, universities have functioned as gatekeepers and treasurers of received knowledge, while concomitantly furthering innovative contributions to society. Yet, when cultivating research ‘silos’, universities encourage scholars to explore in seeming isolation. Out of such tensions, universities have supported, and will continue to pursue, different kinds of, and approaches to, furthering knowledge and creativity. In the past, the humanities had been central to this mission. More recently, however, the efficient and global acceleration of consumer-oriented ‘knowledge production and consumption’ seems to form a critical factor upsetting the centrality of the humanities in university cultures. In this context, exploring the academic communities of the late middle ages proves to be a useful exercise. Forged in strong relationships with ecclesiastical and secular powers, mediaeval universities nonetheless share critical concerns with today’s academic institutions; thus, they too were constrained by the need to attract and exact excellence, to navigate relationships with their immediate environs, and to train professionals, who could ensure continuity in academic communities, the church, and the imperial courts. In other words, mediaeval universities also experienced polarising tensions that reveal consonances between then and now and that can gloss today’s acceleration driving the consumer model of knowledge production and consumption, while also encouraging scholars to form more explicit links to external constituencies.  相似文献   

Vygotsky’s sociocultural theory in the context of globalization     

Simon Marginson  Thi Kim Anh Dang 《Asia Pacific Journal of Education》2017,37(1):116-129

The article reviews the social-educational theorization of the early Soviet psychologist L. S. Vygotsky (1896–1934) in the light of the impact of communicative globalization in educational practice. Vygotsky proposed four “genetic domains” for investigating higher cognitive processes: the phylogenetic (humans undergoing natural evolution), the cultural-historical (social activity of humans), the ontogenetic (individual lifespan), and the microgenetic (immediate events). Vygotskian sociocultural theory is widely used in educational research, especially Vygotsky’s notion of mediated development via tools and signs. Since Vygotsky, communicative globalization has transformed educational potentials. Nevertheless, provided adjustments are made to Vygotsky’s genetic method to incorporate time-space compression, the mutual presence of the genetic domains, and the glonacal heuristic, Vygotskian theory continues to be useful in socially-situated investigations of educational development and transformation, and opens another way into the global, for example investigation of the role of global mediation in learning.  相似文献