69,678 research outputs found
Laminate comprising fibers embedded in cured amine terminated bis-imide
Amine terminated bisaspartimides are prepared by a Michael type reaction of an aromatic bismaleimide and an aromatic diamine in an aprotic solvent. These bisaspartimides are thermally polymerized to yield tough, resinous polymers crosslinked through -NH- groups. Such polymers are useful in applications requiring materials with resistance to change at elevated temperatures
Maleimido substituted aromatic cyclotriphosphazenes
4-Aminophenoxy cyclotriphosphazenes are reacted with maleic anhydride to produce maleamic acids which are converted to the maleimides. The maleimides are polymerized. By selection of starting materials (e.g., hexakis amino or trisaminophenoxy-trisphenoxy-cyclo-triphosphazenes), selection of molar proportions of reactants, use of mixtures of anhydrides and use of dianhydrides as bridging groups a variety of maleimides and polymers are produced. The polymers have high limiting oxygen indices, high char yields and other useful heat and fire resistant properties making them useful as, for example, impregnants of fabrics
Toolboxes and handing students a hammer: The effects of cueing and instruction on getting students to think critically
Developing critical thinking skills is a common goal of an undergraduate
physics curriculum. How do students make sense of evidence and what do they do
with it? In this study, we evaluated students' critical thinking behaviors
through their written notebooks in an introductory physics laboratory course.
We compared student behaviors in the Structured Quantitative Inquiry Labs
(SQILabs) curriculum to a control group and evaluated the fragility of these
behaviors through procedural cueing. We found that the SQILabs were generally
effective at improving the quality of students' reasoning about data and making
decisions from data. These improvements in reasoning and sensemaking were
thwarted, however, by a procedural cue. We describe these changes in behavior
through the lens of epistemological frames and task orientation, invoked by the
instructional moves
Amine terminated bisaspartimide polymer
Novel amine terminated bisaspartimides are prepared by a Michael-type reaction of an aromatic bismalteimide and an aromatic diamine in an aprotic solvent. These bisaspartimides are thermally polymerized to yield tough, resinous polymers cross-lined through -NH- groups. Such polymers are useful in applications requiring materials with resistance to change at elevated temperatures, e.g., as lightweight laminates with graphite cloth, molding material prepregs, adhesives and insulating material
3-Dimensional simulation of multistage depressed collectors on microcomputers.
A three-dimensional (3-D) package for simulation of asymmetric and crossed-field multistage depressed collectors for microwave tubes has been developed. This package is based upon the 3-D finite-difference code KOBRA3-INP. The main features of the package are a user-friendly input interface, postprocessors for collector analysis and calculation of secondary electron trajectories, and versatile output graphics. Both PC and. mainframe versions of the package have been developed. The results of simple benchmark tests and those of simulation and analysis of asymmetric and crossed-field collectors including the effects of secondary electrons are presented. It is found that the asymmetric hyperbolic electric field collector shows very low backstreaming. It is shown that the representation of trajectories in energy space gives a better insight into the behavior of individual trajectories than plotting in coordinate-space. The package will be useful for designing novel types of depressed collector
Distilling Quantum Entanglement via Mode-Matched Filtering
We propose a new avenue towards distillation of quantum entanglement that is
implemented by directly passing the entangled qubits through a mode-matched
filter. This approach can be applied to a common class of entanglement
impurities appearing in photonic systems where the impurities inherently occupy
different spatiotemporal modes than the entangled qubits. As a specific
application, we show that our method can be used to significantly purify the
telecom-band entanglement generated via the Kerr nonlinearity in single-mode
fibers where a substantial amount of Raman-scattering noise is concomitantly
produced.Comment: 6 pages, 2 figures, to appear in Phys. Rev.
Targeting of anionic membrane species by lanthanide(III) complexes: towards improved MRI contrast agents for apoptosis
No abstract available
Mechanism of margination in confined flows of blood and other multicomponent suspensions
Flowing blood displays a phenomenon called margination, in which leukocytes
and platelets are preferentially found near blood vessel walls, while
erythrocytes are depleted from these regions. Here margination is investigated
using direct hydrodynamic simulations of a binary suspension of stiff (s) and
floppy (f) capsules, as well as a stochastic model that incorporates the key
particle transport mechanisms in suspensions -- wall-induced hydrodynamic
migration and shear-induced pair collisions. The stochastic model allows the
relative importance of these two mechanisms to be directly evaluated and
thereby indicates that margination, at least in the dilute case, is largely due
to the differential dynamics of homogeneous (e.g. s-s) and heterogeneous (s-f)
collisionsComment: 5 Pages, 4 figure
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