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Liquid filling in microfluidic channels is a complex process that depends on a variety of geometric, operating, and material parameters such as microchannel geometry, flow velocity∕pressure, liquid surface tension, and contact angle of channel surface. Accurate analysis of the filling process can provide key insights into the filling time, air bubble trapping, and dead zone formation, and help evaluate trade-offs among the various design parameters and lead to optimal chip design. However, efficient modeling of liquid filling in complex microfluidic networks continues to be a significant challenge. High-fidelity computational methods, such as the volume of fluid method, are prohibitively expensive from a computational standpoint. Analytical models, on the other hand, are primarily applicable to idealized geometries and, hence, are unable to accurately capture chip level behavior of complex microfluidic systems. This paper presents a parametrized dynamic model for the system-level analysis of liquid filling in three-dimensional (3D) microfluidic networks. In our approach, a complex microfluidic network is deconstructed into a set of commonly used components, such as reservoirs, microchannels, and junctions. The components are then assembled according to their spatial layout and operating rationale to achieve a rapid system-level model. A dynamic model based on the transient momentum equation is developed to track the liquid front in the microchannels. The principle of mass conservation at the junction is used to link the fluidic parameters in the microchannels emanating from the junction. Assembly of these component models yields a set of differential and algebraic equations, which upon integration provides temporal information of the liquid filling process, particularly liquid front propagation (i.e., the arrival time). The models are used to simulate the transient liquid filling process in a variety of microfluidic constructs and in a multiplexer, representing a complex microfluidic network. The accuracy (relative error less than 7%) and orders-of-magnitude speedup (30 000X–4 000 000X) of our system-level models are verified by comparison against 3D high-fidelity numerical studies. Our findings clearly establish the utility of our models and simulation methodology for fast, reliable analysis of liquid filling to guide the design optimization of complex microfluidic networks. 相似文献
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Oliver and Soundararajan have recently discovered an unexpected bias in the distribution of prime numbers. Interestingly, the authors embarked on this research after hearing about a counter-intuitive result obtained upon comparison of two elementary coin tossing experiments. This article describes these experiments and presents both numerical and analytical methods for exploring the source of inspiration for their research. Elaboration of such key motivations or themes provides a way of bringing the excitement of recent mathematical discoveries to the undergraduate classroom. 相似文献
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Effect of oral administration of 2 ml per day of suspension (in water) of alcoholic extract of whole fruit of Trichosanthes dioica (2%) (=100 g fresh wt.=7 g dry wt.=1/15 g of alcoholic extract) with the help of catheter alongwith basal diet for four weeks have been studied in the normal albino rabbits. It was observed that this extract lowered the blood sugar, total cholesterol, low density lipoprotein cholesterol and triglyceride levels, and increased the high density lipoprotein cholesterol, phospholipid and faecal sterol levels. Such effects are manifested from the very first week of feeding and are statistically significant. 相似文献
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Few will disagree that teleteaching or teaching using computers and telecommunications technology is becoming increasingly popular among educators. There is much more uncertainty, however, about whether technology is as effective a mode of teaching as its proponents claim. This hesitation in endorsing technology is undoubtedly a result of the inconclusive results of teaching experiments using technology with out an adequate pedagogical base. This paper proposes guidelines for the effective use of technology. These may help the educator to avoid frustrating and stultifying practices that may prejudice the educator and student against using a rich educational resource. While the golden rule urges a two-way constructivist approach to teaching, the ten commandments draw the educator's attention to issues of access, hardware and software selection, learner and teacher preparedness for technology, and human factors in the use of technology 相似文献
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Laxmi Prasad Pant 《The Journal of Agricultural Education and Extension》2013,19(3):205-230
Abstract Purpose: The fields of competence development and capacity development remain isolated in the scholarship of learning and innovation despite the contemporary focus on innovation systems thinking in agricultural and rural development. This article aims to address whether and how crossing the conventional boundaries of these two fields provide new directions for developing learning and innovation competence in international development. Design/methodology/approach: Using mixed methods research, this article assesses work environments for experiential learning and innovation, and investigates effective ways of enhancing core competence in agricultural research, education, extension and entrepreneurship. Findings: Findings suggest that while the focus on input and output indicators are relevant for technological innovation competence development, outcome indicators, such as measures of changes in cognitive, affective and psychomotor domains of learning and innovation, would better serve the purpose of developing organisational and institutional learning and innovation competence. Practical implications: This research concludes that crossing the conventional boundaries of competence development and capacity development serves as a way to renew the role of education within the innovation systems thinking. However, such an attempt to enhance human capabilities and functionings through education should integrate theory-based, competence-based and experiential learning components as a coherent whole. Originality/value: This article demonstrates the value of crossing the conventional boundaries of the two seemingly unrelated fields—competence development through education and capacity development through extension—to provide new directions to operationalise innovation systems thinking in agricultural education and extension. 相似文献
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ABSTRACTThis research reports for the first time the inclusion of Oryza sativa straw, root, and husk as a vegetal additive in the fifth century CE decorative mud plaster of the Buddhist cave of Bezeklik. The investigation is based on the morphological, anatomical, and silica bodies study of the vegetal additives accomplished through a light microscope, stereomicroscope, Fourier-transform infrared spectrophotometer, and scanning electron microscope from the isolated fragments of the painted plaster, transported to India in the nineteenth century and presently housed in National Museum, New Delhi. Studies indicate that loamy sand soil sourced locally for the earthen plaster was mixed with paddy straw in the proportion of 25–30% by volume for cohesion and strength. The excess of sand and absence of clay-size particles in plaster is, however, causing disaggregation of the grains due to lack of cohesion. As locally available materials are preferably used for any plaster works, this study also raises the question – was ancient Bezeklik, now a desert of Northwest China, once a rice-growing area in addition to the crops of Triticum aestivum (wheat), Setaria italica (Foxtail millet), and Hordeum vulgare (barley) reported by many researchers, based on hypothetical environment recreation. This study will help prepare a compatible plaster for the restoration of fragile-painted plaster fragments. 相似文献
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Namdev S. Togre Priyanka S. Bhoj Vishal K. Khatri Aditya Tarnekar Kalyan Goswami Moreshwar R. Shende M. V. R. Reddy 《Indian journal of clinical biochemistry : IJCB》2018,33(3):282-289
Helminthic infections lead to the release of various molecules which play an important role in modulation of the host immune system. Such filarial proteins with immunomodulatory potential can be used for therapeutic purpose in inflammatory and immune mediated diseases. In the present study, we have explored the prophylactic effect of filarial SXP–RAL family protein of Wuchereria bancrofti i.e. rWbL2 protein in DSS induced inflammatory ulcerative colitis in a mouse model. Prior treatment of rWbL2, followed by induction of colitis, showed significantly reduced disease severity as indicated by the decreased disease manifestations and improved macroscopic and microscopic inflammation. This preventive effect was found to be associated with increased release of anti-inflammatory cytokine IL-10 and decreased release of proinflammatory cytokines IFN-γ, TNF-α, IL-6 and IL-17 by the splenocytes of treated mice. From this study, it can be envisaged that pretreatment with filarial protein, rWbL2, can prevent the establishment of ulcerative colitis in BALB/c mice. The underlying immunological mechanism may involve the up-regulation of Th2 immune response with down-regulation of Th1 response. 相似文献