Worcester Polytechnic Institute

About: Worcester Polytechnic Institute is a education organization based out in Worcester, Massachusetts, United States. It is known for research contribution in the topics: Computer science & Population. The organization has 6270 authors who have published 12704 publications receiving 332081 citations. The organization is also known as: WPI.

The specific heat and effective thermal conductivity of composites containing single-wall and multi-wall carbon nanotubes.

Abstract: We present a study of the specific heat and effective thermal conductivity in anisotropic and randomly oriented multi-wall carbon nanotube (MWCNT) and randomly oriented single-wall carbon nanotube (SWCNT) composites from 300 to 400 K Measurements on randomly oriented MWCNTs and SWCNTs were made by depositing a thin film of CNTs within a calorimetric cell Anisotropic measurements were made on MWCNTs grown inside the highly ordered, densely packed nanochannels of anodic aluminum oxide The specific heat of randomly oriented MWCNTs and SWCNTs showed similar behavior to the specific heat of bulk graphite powder However, the specific heat of aligned MWCNTs is smaller and has weaker temperature dependence than that of the bulk above room temperature The effective thermal conductivity of randomly oriented MWCNTs and SWCNTs is similar to that of powder graphite, exhibiting a maximum value near 364 K indicating the onset of phonon-phonon scattering The effective thermal conductivity of the anisotropic MWCNTs increased smoothly with increasing temperature and is indicative of the one-dimensional nature of the heat flow

Aptamer-Based Au Nanoparticles-Enhanced Surface Plasmon Resonance Detection of Small Molecules

Abstract: Small molecules are difficult to detect by conventional SPR technique directly because the changes in the refractive index resulting from the binding processes of small biomolecules are often small. In order to extend the application of SPR biosensor in detecting a small molecule, we combine the advantage of aptamer technique with the amplifying effect of Au nanoparticles to design a sensitive SPR sensor for detecting small molecules. The principle of this sensor is based on surface inhibition detection. The aptamer is first immobilized on SPR gold film with its ss-DNA structure. The aptamer possessing this structure can be hybridized with Au nanoparticles-tagged complementary ss-DNA and result in a large change of SPR signal. However, the aptamer will change its structure from ss-DNA to tertiary structure after adenosine is added to the SPR cell. The aptamer possessing tertiary structure could not hybridize with Au nanoparticles-tagged complementary ss-DNA. Thus, the change of SPR signal resulted in the ...

Spatial Joins Using R-trees: Breadth-First Traversal with Global Optimizations

Abstract: R-tree based spatial join is useful because of both its superior performance and the wide spread implementation of R-trees. We present a new R-tree join method called BFRJ (Breadth-First R-tree Join). BFRJ synchronously traverses both R-trees in breadthfirst order while processing join computation one level at a time. At each level, BFRJ creates an intermediate join index and deploys global optimization strategies (ordering, memory management, buffer management) to improve the join computation at the next level. We also present an experimental evaluation of the proposed optimizations as well as a performance comparison between BFRJ and the state-of-the-art approach. Our experimental results indicate that BFRJ with global optimizations can outperform the competitor by a significant margin (up to 50%). This work was supportedin part by the University of Michigan ITS Research Center of Excellence grant (DTFH61-93-X0001i’-Sub) sponsored by the U.S. Dept. of Transportation and by the Michigan Dept. of Transportation. This work was performed while the authors were at the University of Michigan. Permission to copy without fee all OT part of this material is granted provided that the copies are not made OT distributed for direct commercial advantage, the VLDB copyright notice and the title of the publication and its date appear, and notice is given that copying is by permission of the Very Large Data Base Endowment. To copy otherwise, OT to republish, requires a fee and/or special permission from the Endowment. Proceedings of the 23rd VLDB Conference Athens, Greece, 1997

Dense Perovskite, La1-xA′xFe1-yCoyO3-δ (A′= Ba, Sr, Ca), Membrane Synthesis, Applications, and Characterization

Abstract: La1-xA′xFe0.8Co0.2O3-δ (A′= Ca, Sr, Ba) perovskite powders were synthesized to attain the desired properties of high O2 flux and stability under reducing conditions. Steady-state oxygen permeation rates for La1-xA′xFe0.8-Co0.2O3-δ perovskite membranes in nonreacting experiments with air on one side and helium on the other side of the membrane were in the order A′x= Ba0.8 > Ba0.6 > Ca0.6 > Sr0.6. Partial oxidation of methane to syngas (CO + H2) was performed in a dense La0.2Ba0.8Fe0.8Co0.2O3-δ membrane reactor at 850°C in which oxygen was separated from air and simultaneously fed into the methane stream. The reducing atmosphere affected the membrane reaction-side surface while barium enrichment occurred on the air-side surface. Oxygen continuously transported from the air side appeared to stabilize the membrane interior, and the reactor was operated for up to 850 h.