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Stefanie Demming Gena Peterat Andreu Llobera Hannah Schmolke Alexander Bruns Michael Kohlstedt Ala‘aldeen Al-Halhouli Claus-Peter Klages Rainer Krull Stephanus Büttgenbach 《Biomicrofluidics》2012,6(3)
This paper presents a vertically positioned microfluidic system made of poly(dimethylsiloxane) (PDMS) and glass, which can be applied as a microbubble column (μBC) for biotechnological screening in suspension. In this μBC, microbubbles are produced in a cultivation chamber through an integrated nozzle structure. Thus, homogeneous suspension of biomass is achieved in the cultivation chamber without requiring additional mixing elements. Moreover, blockage due to produced carbon dioxide by the microorganisms—a problem predominant in common, horizontally positioned microbioreactors (MBRs)—is avoided, as the gas bubbles are released by buoyancy at the upper part of the microsystem. The patterned PDMS layer is based on an optimized two-lithographic process. Since the naturally hydrophobic PDMS causes problems for the sufficient production of microbubbles, a method based on polyelectrolyte multilayers is applied in order to allow continuous hydrophilization of the already bonded PDMS-glass-system. The μBC comprises various microelements, including stabilization of temperature, control of continuous bubble formation, and two optical configurations for measurement of optical density with two different sensitivities. In addition, the simple and robust application and handling of the μBC is achieved via a custom-made modular plug-in adapter. To validate the scalability from laboratory scale to microscale, and thus to demonstrate the successful application of the μBC as a screening instrument, a batch cultivation of Saccharomyces cerevisiae is performed in the μBC and compared to shake flask cultivation. Monitoring of the biomass growth in the μBC with the integrated online analytics resulted in a specific growth rate of 0.32 h−1, which is almost identical to the one achieved in the shake flask cultivation (0.31 h−1). Therefore, the validity of the μBC as an alternative screening tool compared to other conventional laboratory scale systems in bioprocess development is proven. In addition, vertically positioned microbioreactors show high potential in comparison to conventional screening tools, since they allow for high density of integrated online analytics and therefore minimize time and cost for screening and guarantee improved control and analysis of cultivation parameters. 相似文献
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Gena Nelson Kathleen Hughes Pfannenstiel Rebecca Zumeta Edmonds 《Learning disabilities research & practice》2020,35(1):14-24
Within a multitiered system of support (MTSS), students who struggle to learn mathematics often receive core instruction and supplemental intervention in different settings, with different teachers and different sets of curriculum materials, all of which can result in poor alignment. This curriculum crosswalk describes how three sets of materials commonly used to provide core instruction and intervention differ with regard to mathematics practices and vocabulary. The results indicate that there is little overlap among all three programs for the majority (n = 6) of the mathematics practices, and very little overlap in mathematics vocabulary (ranging from 6.3 to 24 percent). We also provide a set of research-based instructional recommendations intended to help teachers address gaps and improve alignment of core instruction and intervention. 相似文献
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Using a Conceptual Understanding and Procedural Fluency Heuristic to Target Math Interventions with Students in Early Elementary 
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下载免费PDF全文 Matthew K. Burns Christopher Walick Gregory R. Simonson Lauren Dominguez Laura Harelstad Aleksis Kincaid Gena S. Nelson 《Learning disabilities research & practice》2015,30(2):52-60
The study examined the use of a conceptual and procedural framework for identifying math deficits and delivering appropriate interventions. Participants were two first‐grade students and one third‐grade student, who were identified as struggling with the grade‐appropriate content in math. The first‐grade students focused on addition and the third‐grade student focused on multiplication. Each student's conceptual understanding was assessed, and students who lacked conceptual understanding received an intervention that addressed underlying concepts. Students with acceptable understanding of the underlying concepts received an intervention that focused on the procedure. The study used a single‐case, multiple‐baseline design, but the contra‐indicated intervention was administered for the first 2 weeks following baseline, with the prescribed intervention for the final 2 weeks. Each student showed more growth during the prescribed intervention phase when compared to the contra‐indicated phase. 相似文献
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April Luehmann Yang Zhang Heather Boyle Eve Tulbert Gena Merliss Kyle Sullivan 《科学教学研究杂志》2024,61(2):319-357
We find ourselves at a time when the need for transformation in science education is aligning with opportunity. Significant science education resources, namely the Next Generation Science Standards (NGSS) and the Ambitious Science Teaching (AST) framework, need an intentional aim of centering social justice for minoritized communities and youth as well as practices to enact it. While NGSS and AST provide concrete guidelines to support deep learning, revisions are needed to explicitly promote social justice. In this study, we sought to understand how a commitment to social justice, operationalized through culturally sustaining pedagogy (Paris, Culturally sustaining pedagogies and our futures. The Educational Forum, 2021; 85, pp. 364–376), might shape the AST framework to promote more critical versions of teaching science for equity. Through a qualitative multi-case study, we observed three preservice teacher teams engaged in planning, teaching, and debriefing a 6-day summer camp in a rural community. Findings showed that teachers shaped the AST sets of practices in ways that sustained local culture and addressed equity aims: anchoring scientific study in phenomena important to community stakeholders; using legitimizing students' stories by both using them to plan the following lessons and as data for scientific argumentation; introducing local community members as scientific experts, ultimately supporting a new sense of pride and advocacy for their community; and supporting students in publicly communicating their developing scientific expertise to community stakeholders. In shaping the AST framework through culturally sustaining pedagogy, teachers made notable investments: developing local networks; learning about local geography, history, and culture; building relationships with students; adapting lessons to incorporate students' ideas; connecting with community stakeholders to build scientific collaborations; and preparing to share their work publicly with the community. Using these findings, we offer a justice-centered ambitious science teaching (JuST) framework that can deliver the benefits of a framework of practices while also engaging in the necessarily more critical elements of equity work. 相似文献
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Despite encouraging findings that show that interventions can improve students’ math understanding, achievement gaps in math often persist or even widen for students who struggle. Practitioners play a significant role in closing these achievement gaps because they have the responsibility to select or design interventions. Practitioners may wish to consider factors that influence intervention effectiveness. This study evaluated numeracy interventions and explored how features of the studies and interventions may have influenced reported effects. Exploratory analyses revealed smaller effects when only distal measures were considered (g = 0.35; SE = 0.05), or when studies reported including more than 30 percent of participants as English learners (g = 0.44; SE = 0.12). Results also indicated variable effects across the same intervention programs. Implications for practitioners related to selecting interventions are discussed. 相似文献
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A large body of research has examined students' conceptions of evolution and their relationships to acceptance of evolution. Proficiency in statistical and probabilistic reasoning has long been considered to be an essential feature of evolutionary reasoning, yet almost no empirical work has explored these putative connections. The RaPro instruments have recently been developed to measure statistical reasoning in the contexts of mathematics (RaProMath) and evolution (RaProEvo). Our study provides additional validation of these instruments using Rasch analysis and quantifies the contribution of statistical reasoning to both understanding and accepting evolution. We recruited a large sample (N = 564) of undergraduate students enrolled in an introductory biology course at a large public research university in the United States. Students completed a suite of published instruments that assessed statistical reasoning, evolutionary understanding, and evolutionary acceptance. Our findings indicate that validity inferences derived from RaPro scores generalized to the new sample, and that proficiency in statistical reasoning explained 28% of the variance in evolutionary knowledge and 19% of the variation in evolutionary acceptance. The inclusion of demographic variables into the model significantly increased the explained variance in acceptance. Notably, the variance in evolution acceptance explained by statistical reasoning was comparable to that of thinking dispositions or evolutionary knowledge reported in the literature. This work provides the first large-scale evidence of the role of statistical reasoning in evolutionary knowledge and acceptance and motivates future work to explore how statistical literacy should be integrated into evolution education efforts. 相似文献
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