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Inertial microfluidics is an emerging class of technologies developed to separate circulating tumor cells (CTCs). However, defining design parameters and flow conditions for optimal operation remains nondeterministic due to incomplete understanding of the mechanics, which has led to challenges in designing efficient systems. Here, we perform a parametric study of the inertial focusing effects observed in low aspect ratio curvilinear microchannels and utilize the results to demonstrate the isolation of CTCs with high purity. First, we systematically vary parameters including the channel height, width, and radius of curvature over a wide range of flow velocities to analyze its effect on size dependent differential focusing and migration behaviors of binary (10 μm and 20 μm) particles. Second, we use these results to identify optimal flow regimes to achieve maximum separation in various channel configurations and establish design guidelines to readily provide information for developing spiral channels tailored to potentially arbitrary flow conditions that yield a desired equilibrium position for optimal size based CTC separation. Finally, we describe a fully integrated, sheath-less cascaded spiral microfluidic device to continuously isolate CTCs. Human breast cancer epithelial cells were successfully extracted from leukocytes, achieving 86.76% recovery, 97.91% depletion rate, and sustaining high viability upon collection to demonstrate the versatility of the device. Importantly, this device was designed without the cumbersome trail-and-error optimization process that has hindered the development of designing such inertial microfluidic systems. 相似文献
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In the current information environment, libraries need to leverage on the latest digital technologies as well as the traditional paper technologies towards building practical digital libraries and electronic information systems. Digital libraries built exclusively out of nascent electronic publications such as e-journals, e-books, e-reference works (Web-based training programs, computer-based training programs, etc.), digital scholarly works (monographs, etc. in the public domain) and digitized documents conforming to standard digital formats are proving to be an uphill and unfinished task. Perhaps this could be the major reason why the start-success-finish ratio of most of the digital library initiatives, particularly initiated by isolated/individual libraries, is still left at alarmingly low numbers. We find the motivational and emotional bonding among the stakeholders melting down eventually as the digital library development process gets fired up. There are a host of problems the enthusiastic library fraternity face in their digital library development endeavours starting from copyright issues, technology complexities, infrastructure threats, diverse publication types, multiplicity of digital object formats and above all the publishers’ stringent policies and monopolies. It is therefore essential that the libraries adopt necessary strategies towards developing digital libraries from the lessons learnt. The monolithic and all-in-one-container approach is no longer feasible and no more advocated. It is imperative on the part of the information professional to have a componentized and a multi-system approach to knowledge technologies and information management. Seamless aggregation and meticulous integration of diverse datastreams, embracing the print as well as the electronic information, is the most appropriate strategy to be adopted and applied. This paper shares Indian Institute of Management Kozhikode's experience in creating a state-of-art digital library information system by seamlessly integrating and aggregating the print as well as the diverse and distributed digital content penetrating into its knowledge domain. The paper highlights significant features of IIMK's digital information system—the content aggregation and the content integration strategies we adopted for designing a scholarship Web portal and developing a digital library using the ‘Greenstone’ open source digital library software. The paper also highlights the role of libraries in promoting open access by setting up scholarly institutional repositories (IR). In summary, today's digital library information system is to be seen from a much wider and more holistic perspective, and provided with a much broadened meaning to hold and put together all the print, digital and electronic information available and accessible to the library. 相似文献
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