24,970 research outputs found
Development of quality assurance methods for epoxy graphite prepreg
Quality assurance methods for graphite epoxy/prepregs were developed. Liquid chromatography, differential scanning calorimetry, and gel permeation chromatography were investigated. These methods were applied to a second prepreg system. The resin matrix formulation was correlated with mechanical properties. Dynamic mechanical analysis and fracture toughness methods were investigated. The chromatography and calorimetry techniques were all successfully developed as quality assurance methods for graphite epoxy prepregs. The liquid chromatography method was the most sensitive to changes in resin formulation. The were also successfully applied to the second prepreg system
Length control of microtubules by depolymerizing motor proteins
In many intracellular processes, the length distribution of microtubules is
controlled by depolymerizing motor proteins. Experiments have shown that,
following non-specific binding to the surface of a microtubule, depolymerizers
are transported to the microtubule tip(s) by diffusion or directed walk and,
then, depolymerize the microtubule from the tip(s) after accumulating there. We
develop a quantitative model to study the depolymerizing action of such a
generic motor protein, and its possible effects on the length distribution of
microtubules. We show that, when the motor protein concentration in solution
exceeds a critical value, a steady state is reached where the length
distribution is, in general, non-monotonic with a single peak. However, for
highly processive motors and large motor densities, this distribution
effectively becomes an exponential decay. Our findings suggest that such motor
proteins may be selectively used by the cell to ensure precise control of MT
lengths. The model is also used to analyze experimental observations of
motor-induced depolymerization.Comment: Added section with figures and significantly expanded text, current
version to appear in Europhys. Let
Characterization methodology for PMR-15
Characterization of model compounds, monomers, resin solutions and cure cycles of PMR-15 polyimide are performed. Successful separation of various reaction products is also accomplished by liquid chromatography. The PMR-15 cure analysis is performed by fourier transform spectroscopy and gas chromatograph - mass spectrometry. Characterization receiving inspection tests for Quality Control are recommended
Attracted Diffusion-Limited Aggregation
In this paper, we present results of extensive Monte Carlo simulations of
diffusion-limited aggregation (DLA) with a seed placed on an attractive plane
as a simple model in connection with the electrical double layers. We compute
the fractal dimension of the aggregated patterns as a function of the
attraction strength \alpha. For the patterns grown in both two and three
dimensions, the fractal dimension shows a significant dependence on the
attraction strength for small values of \alpha, and approaches to that of the
ordinary two-dimensional (2D) DLA in the limit of large \alpha. For
non-attracting case with \alpha=1, our results in three dimensions reproduce
the patterns of 3D ordinary DLA, while in two dimensions our model leads to
formation of a compact cluster with dimension two. For intermediate \alpha, the
3D clusters have quasi-2D structure with a fractal dimension very close to that
of the ordinary 2D-DLA. This allows one to control morphology of a growing
cluster by tuning a single external parameter \alpha.Comment: 6 pages, 6 figures, to appear in Phys. Rev. E (2012
New light on the ‘Drummer of Tedworth’: conflicting narratives of witchcraft in Restoration England
This paper presents a definitive text of hitherto little-known early documents concerning ‘The Drummer of Tedworth’, a poltergeist case that occurred in 1662-3 and became famous not least due to its promotion by Joseph Glanvill in his demonological work, Saducismus Triumphatus. On the basis of these and other sources, it is shown how responses to the events at Tedworth evolved from anxious piety on the part of their victim, John Mompesson, to confident apologetic by Glanvill, before they were further affected by the emergence of articulate scepticism about the case
A crop wild relative global portal. Meeting the information challenge for CWR in situ conservation
Raising Tc in charge density wave superconductor ZrTe3 by Ni intercalation
We report discovery of bulk superconductivity in Ni0.05ZrTe3 at Tc = 3.1 K,
obtained through Ni intercalation. Superconductivity coexists with charge
density wave (CDW) state with TCDW = 41 K. When compared to parent material
ZrTe3, filamentary superconducting transition is substantially increased
whereas TCDW was suppressed. The analysis of superconducting state indicates
that Ni0.05ZrTe3 is an intermediately coupled superconductor.Comment: 5 pages, 5 figure
Parsimonious Kernel Fisher Discrimination
By applying recent results in optimization transfer, a new algorithm for kernel Fisher Discriminant Analysis is provided that makes use of a non-smooth penalty on the coefficients to provide a parsimonious solution. The algorithm is simple, easily programmed and is shown to perform as well as or better than a number of leading machine learning algorithms on a substantial benchmark. It is then applied to a set of extreme small-sample-size problems in virtual screening where it is found to be less accurate than a currently leading approach but is still comparable in a number of cases
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