Clogging by sieving in microchannels: Application to the detection of contaminants in colloidal suspensions

We report on a microfluidic method that allows measurement of a small concentration of large contaminants in suspensions of solid micrometer-scale particles. To perform the measurement, we flow the colloidal suspension through a series of constrictions, i.e. a microchannel of varying cross-section. We show and quantify the role of large contaminants in the formation of clogs at a constriction and the growth of the resulting filter cake. By measuring the time interval between two clogging events in an array of parallel microchannels, we are able to estimate the concentration of contaminants whose size is selected by the geometry of the microfluidic device. This technique for characterizing colloidal suspensions offers a versatile and rapid tool to explore the role of contaminants on the properties of the suspensions

Self-Assembly of Polyhedral Hybrid Colloidal Particles

We have developed a new method to produce hybrid particles with polyhedral shapes in very high yield (liter quantities at up to 70% purity) using a combination of emulsion polymerization and inorganic surface chemistry. The procedure has been generalized to create complex geometries, including hybrid line segments, triangles, tetrahedra, octahedra, and more. The optical properties of these particles are tailored for studying their dynamics and self-assembly. For example, we produce systems that consist of index-matched spheres allowing us to define the position of each elementary particle in three-dimensional space. We present some preliminary studies on the self-assembly of these complex shaped systems based on electron and optical microscopy.Engineering and Applied SciencesPhysic

Decay properties of the heavy-light mesons

We study the decay properties of a heavy-light meson. We reformulate the decay amplitudes for the heavy-light systems and find a new way to calculate decay rates. Applying this formulation, we find a new sum rule for the radiative decays of one heavy-light meson into another, $H_1\to H_2+\gamma$ with various combinations of $H_i$.Comment: an invited talk at "New Frontiers in QCD 2010" held at Kyot

Influence of the initial chemical conditions on the rational design of silica particles

The influence of the water content in the initial composition on the size of silica particles produced using the Stöber process is well known. We have shown that there are three morphological regimes defined by compositional boundaries. At low water levels (below stoichiometric ratio of water:tetraethoxysilane), very high surface area and aggregated structures are formed; at high water content (>40 wt%) similar structures are also seen. Between these two boundary conditions, discrete particles are formed whose size are dictated by the water content. Within the compositional regime that enables the classical Stöber silica, the structural evolution shows a more rapid attainment of final particle size than the rate of formation of silica supporting the monomer addition hypothesis. The clearer understanding of the role of the initial composition on the output of this synthesis method will be of considerable use for the establishment of reliable reproducible silica production for future industrial adoption

Nociceptive Sensory Neurons Drive Interleukin-23 Mediated Psoriasiform Skin Inflammation

The skin has a dual function as a barrier and a sensory interface between the body and the environment. To protect against invading pathogens, the skin harbors specialized immune cells, including dermal dendritic cells (DDCs) and interleukin (IL)-17 producing γδ T cells (γδT17), whose aberrant activation by IL-23 can provoke psoriasis-like inflammation1–4. The skin is also innervated by a meshwork of peripheral nerves consisting of relatively sparse autonomic and abundant sensory fibers. Interactions between the autonomic nervous system and immune cells in lymphoid organs are known to contribute to systemic immunity, but how peripheral nerves regulate cutaneous immune responses remains unclear5,6. Here, we have exposed the skin of mice to imiquimod (IMQ), which induces IL-23 dependent psoriasis-like inflammation7,8. We show that a subset of sensory neurons expressing the ion channels TRPV1 and NaV1.8 is essential to drive this inflammatory response. Imaging of intact skin revealed that a large fraction of DDCs, the principal source of IL-23, is in close contact with these nociceptors. Upon selective pharmacological or genetic ablation of nociceptors9–11, DDCs failed to produce IL-23 in IMQ exposed skin. Consequently, the local production of IL-23 dependent inflammatory cytokines by dermal γδT17 cells and the subsequent recruitment of inflammatory cells to the skin were dramatically reduced. Intradermal injection of IL-23 bypassed the requirement for nociceptor communication with DDCs and restored the inflammatory response12. These findings indicate that TRPV1+NaV1.8+ nociceptors, by interacting with DDCs, regulate the IL-23/IL-17 pathway and control cutaneous immune responses

Alien Registration- Perro, Breton E. (Portland, Cumberland County)

https://digitalmaine.com/alien_docs/23087/thumbnail.jp

How Elementary Teachers Determine Meaningful Homework Assignments

A self-study at a local elementary school revealed that homework assignments appeared to be at lower levels of Bloom’s taxonomy, and students were inadequately prepared for summative assessments that required the application and critical thinking levels of Bloom’s taxonomy. Formative assessment data, ideally, drives teachers’ instructional decisions in the classroom. The purpose of this qualitative case study was to better understand the formative assessment processes that drive instructional decision making. The conceptual framework by Chappuis and influenced by Black and Wiliam includes the strategic process for successful formative assessment teaching and learning. The research questions explored the use of homework as a formative assessment in classrooms. In this intrinsic case study, data collection included face to face interviews with 10 general education Grade 3-5 teachers in 2 different schools within the same, a 2- week document analysis of homework assigned in language arts and mathematics, and a focus group of participants. The data were analyzed with open coding followed by axial coding to determine themes. Member checking and triangulation were used to ensure validity and accuracy. The themes that emerged from the coded data identified ineffective teacher use of feedback, self-assessment, and learning targets—essential practices of the formative assessment process. Improving the formative assessment process for teaching and learning may encourage positive social change through promoting teacher selfefficacy and collaboration through a professional development paired with a professional learning community. This study may also lead teachers to change their formative assessment processes and provide guided instruction that enhances student learning outcomes