An integrated microfluidic chip for immunocapture,preconcentration and separation of β-amyloid peptides

We present an integrated microfluidic chip for detection of β-amyloid (Aβ) peptides. Aβ peptides are major biomarkers for the diagnosis of Alzheimer''s disease (AD) in its early stages. This microfluidic device consists of three main parts: (1) An immunocapture microcolumn based on self-assembled magnetic beads coated with antibodies specific to Aβ peptides, (2) a nano-porous membrane made of photopolymerized hydrogel for preconcentration, and (3) a microchip electrophoresis (MCE) channel with fluorescent detection. Sub-milliliter sample volume is either mixed off-chip with antibody coated magnetic beads and injected into the device or is injected into an already self-assembled column of magnetic beads in the microchannel. The captured peptides on the beads are then electrokinetically eluted and re-concentrated onto the nano-membrane in a few nano-liters. By integrating the nano-membrane, total assay time was reduced and also off-chip re-concentration or buffer exchange steps were not needed. Finally, the concentrated peptides in the chip are separated by electrophoresis in a polymer-based matrix. The device was applied to the capture and MCE analysis of differently truncated peptides Aβ (1–37, 1–39, 1–40, and 1–42) and was able to detect as low as 25 ng of synthetic Aβ peptides spiked in undiluted cerebrospinal fluid (CSF). The device was also tested with CSF samples from healthy donors. CSF samples were fluorescently labelled and pre-mixed with the magnetic beads and injected into the device. The results indicated that Aβ1-40, an important biomarker for distinguishing patients with frontotemporal lobe dementia from controls and AD patients, was detectable. Although the sensitivity of this device is not yet enough to detect all Aβ subtypes in CSF, this is the first report on an integrated or semi-integrated device for capturing and analyzing of differently truncated Aβ peptides. The method is less demanding and faster than the conventional Western blotting method currently used for research.     

Do financial constraints hold back innovation and growth?: Evidence on the role of public policy

This paper provides evidence that capital-market imperfections hold back innovation and growth, and that public policy can complement capital markets. We deliver the evidence by studying the effects of government funding on the behavior of SMEs in Finland. By adapting the methodology recently proposed by Rajan and Zingales [Rajan, R.G., Zingales, L., 1998. Financial dependence and growth. American Economic Review 88, pp. 559-587] to firm-level data, we show that government funding disproportionately helps firms from industries that are dependent on external finance. We demonstrate that the result is economically significant and robust to a variety of tests.     

From Margin to Center: Participating in Village Pedagogy at Historically Black Colleges and Universities

Are Historically Black Colleges and Universities (HBCUs) necessary in the twenty-first century so-called ??post-racial?? US American context? This question is raised loudly and frequently given the contemporary social climate and economic considerations. In this article, the author offers a response to and critique of this question and surveys histories, missions, and academic and social environments of the HBCUs. He contends that HBCUs offer alternate higher education experiences for Black educators and students who find themselves on the margins of the US American academic center. Demonstrating the parallels of HBCU settings to villages, the author illustrates how these HBCU village contexts contribute to pedagogy. Ultimately, he appeals to HBCU stakeholders to intentionally and consistently promote ??village?? environments to cultivate the academic and social sensibilities of its constituents.     

Qualitative Quantitative and Experimental Concept Possession, Criteria for Identifying Conceptual Change in Science Education

Students sometimes misunderstand or misinterpret scientific content because of persistent misconceptions that need to be overcome by science education—a learning process typically called conceptual change. The acquisition of scientific content matter thus requires a transformation of the initial knowledge-state of a common-sense picture of the world to an outcome state of a scientific conception articulated with scientific concepts, which the learner did not possess prior to learning. This paper introduces a taxonomy based on the idea that multiple operational criteria are needed to evaluate conceptual change into scientific concepts. Three sets of criteria—qualitative, quantitative and experimental—are identified, and their interrelations in the process of conceptual change are explored.