Lehigh University

About: Lehigh University is a education organization based out in Bethlehem, Pennsylvania, United States. It is known for research contribution in the topics: Catalysis & Fracture mechanics. The organization has 12684 authors who have published 26550 publications receiving 770061 citations.

Curriculum-Based Measures and Performance on State Assessment and Standardized Tests: Reading and Math Performance in Pennsylvania

Abstract: General outcome measures (GOMs) provide educators with a means to evaluate student progress toward curricular objectives. Curriculum-based measurement (CBM) is one type of GOM that has a long history in the research literature with strong empirical support. With the increased emphasis on instruction linked to state standards and statewide achievement tests, the relationship between CBM and these measures has been called into question. This study examined the relationships between CBM of reading, math computation, and math concepts/applications and the statewide standardized achievement test as well as published norm-referenced achievement tests in two districts in Pennsylvania. Results showed that CBM had moderate to strong correlations with midyear assessments in reading and mathematics and both types of standardized tests across school districts. The data suggest that CBM can be one source of data that could be used to potentially identify those students likely to be successful or fail the statewide ass...

Review: Replacements for Chromium Pretreatments on Aluminum

Abstract: The use of chromium (Cr) as an anticorrosion pretreatment ingredient to protect aluminum (Al) alloys is being restricted because of environmental concerns. Research currently is under way ...

Measuring dynamic cell–material interactions and remodeling during 3D human mesenchymal stem cell migration in hydrogels

Abstract: Biomaterials that mimic aspects of the extracellular matrix by presenting a 3D microenvironment that cells can locally degrade and remodel are finding increased applications as wound-healing matrices, tissue engineering scaffolds, and even substrates for stem cell expansion. In vivo, cells do not simply reside in a static microenvironment, but instead, they dynamically reengineer their surroundings. For example, cells secrete proteases that degrade extracellular components, attach to the matrix through adhesive sites, and can exert traction forces on the local matrix, causing its spatial reorganization. Although biomaterials scaffolds provide initially well-defined microenvironments for 3D culture of cells, less is known about the changes that occur over time, especially local matrix remodeling that can play an integral role in directing cell behavior. Here, we use microrheology as a quantitative tool to characterize dynamic cellular remodeling of peptide-functionalized poly(ethylene glycol) (PEG) hydrogels that degrade in response to cell-secreted matrix metalloproteinases (MMPs). This technique allows measurement of spatial changes in material properties during migration of encapsulated cells and has a sensitivity that identifies regions where cells simply adhere to the matrix, as well as the extent of local cell remodeling of the material through MMP-mediated degradation. Collectively, these microrheological measurements provide insight into microscopic, cellular manipulation of the pericellular region that gives rise to macroscopic tracks created in scaffolds by migrating cells. This quantitative and predictable information should benefit the design of improved biomaterial scaffolds for medically relevant applications.

Efficiency-Droop Suppression by Using Large-Bandgap AlGaInN Thin Barrier Layers in InGaN Quantum-Well Light-Emitting Diodes

Abstract: The electrical and optical characteristics of InGaN quantum-well light-emitting diodes with large-bandgap AlGaInN thin barriers were analyzed with the consideration of carrier transport effect for efficiency droop suppression. The lattice-matched AlGaInN quaternary alloys with different compositions, thicknesses, and positions were employed as thin barrier layers (1-2 nm) surrounding the InGaN QW in LED structures. The increased effective barrier heights of AlGaInN thin barrier led to suppression of carrier leakage as compared to conventional InGaN QW LEDs with GaN barrier only. The current work provides a comprehensive simulation taking into consideration the carrier transport in self-consistent manner, and the finding indicated the use of thin layers of AlGaInN or AlInN barriers as sufficient for suppressing the droop in InGaN-based QW LEDs. The efficiency of InGaN QW LED with the insertion of lattice-matched Al0.82In0.18N thin barrier layers showed the least droop phenomenon at high current density among the investigated LEDs. The thickness study indicated that a thin layer (<; 2 nm) of large-bandgap material in the barrier region was sufficient for efficiency droop suppression.