20,705 research outputs found
Rugged pressed disk electrode has low contact potential
Pressed-disk electrode with low contact potential monitors physiological processes. It consists of silver and silver chloride combined with bentonitic clay. The clay affords a surface that permits use over extended periods without contact deterioration
Pressed disc type sensing electrodes with ion- screening means Patent
Characteristics of pressed disc electrode for biological measurement
Towards the Distributed Burning Regime in Turbulent Premixed Flames
Three-dimensional numerical simulations of canonical statistically-steady
statistically-planar turbulent flames have been used in an attempt to produce
distributed burning in lean methane and hydrogen flames. Dilatation across the
flame means that extremely large Karlovitz numbers are required; even at the
extreme levels of turbulence studied (up to a Karlovitz number of 8767)
distributed burning was only achieved in the hydrogen case. In this case,
turbulence was found to broaden the reaction zone visually by around an order
of magnitude, and thermodiffusive effects (typically present for lean hydrogen
flames) were not observed. In the preheat zone, the species compositions differ
considerably from those of one-dimensional flames based a number of different
transport models (mixture-averaged, unity Lewis number, and a turbulent eddy
viscosity model). The behaviour is a characteristic of turbulence dominating
non-unity Lewis number species transport, and the distinct limit is again
attributed to dilatation and its effect on the turbulence. Peak local reaction
rates are found to be lower in the distributed case than in the lower Karlovitz
cases but higher than in the laminar flame, which is attributed to effects that
arise from the modified fuel-temperature distribution that results from
turbulent mixing dominating low Lewis number thermodiffusive effects. Finally,
approaches to achieve distributed burning at realisable conditions are
discussed; factors that increase the likelihood of realising distributed
burning are higher pressure, lower equivalence ratio, higher Lewis number, and
lower reactant temperature
Extensions of Johnson's and Morita's homomorphisms that map to finitely generated abelian groups
We extend each higher Johnson homomorphism to a crossed homomorphism from the
automorphism group of a finite-rank free group to a finite-rank abelian group.
We also extend each Morita homomorphism to a crossed homomorphism from the
mapping class group of once-bounded surface to a finite-rank abelian group.
This improves on the author's previous results [Algebr. Geom. Topol. 7
(2007):1297-1326]. To prove the first result, we express the higher Johnson
homomorphisms as coboundary maps in group cohomology. Our methods involve the
topology of nilpotent homogeneous spaces and lattices in nilpotent Lie
algebras. In particular, we develop a notion of the "polynomial straightening"
of a singular homology chain in a nilpotent homogeneous space.Comment: 34 page
The communications technology satellite and the associated ground terminals for experiments
General spacecraft operational characteristics of the Communications Technology Satellite are discussed with particular emphasis on communication system parameters. Associated used ground terminals are reviewed. Wideband communications are also discussed
Synthesis and Electrochemiluminescence of Thiophene Substituted Benzosiloles
There has been increasing interest in the synthesis of siloles over the past 20 years due to their applications as chemoselective sensors and light emitting diodes. The standard synthesis of siloles involves a one-pot reductive cyclization followed by Negishi cross-coupling, which was modified by the Pagenkopf group to allow the synthesis of dissymmetric siloles. This modified synthesis allows siloles to be tuned to improve their fluorescent properties via varying substituents on the silole. This culminated in the synthesis of a series of 2,5-bis(thiophene)siloles with bulky silyl substituents that displayed excellent electrochemiluminescent properties.
In the past decade there has been a large push for effective synthetic methods for making benzosiloles. The synthetic method developed by the Chatani group is particularly interesting because of the large variety of benzosiloles that could be synthesized in high yields. Combining the Chatani benzosilole synthesis with the Pagenkopf group’s knowledge in tuning siloles should result in new benzosilole chromophores that might have applications as biosensors or in solar cells.
This work describes the synthesis of benzosiloles containing oligothiophenes substituted at the C2 and C3 positions. Benzosiloles are formed in a cycloaddition reaction from 2-silylphenylborates and thiophene-acetylenes with a rhodium catalyst. In total seven benzosiloles were synthesized including those with electron donating and electron withdrawing groups. Their ECL properties were then tested to discover that both highly conjugated bis(2,3-terthiophene)benzosilole and 6-cyano-bis(2,3-terthiophene)benzosilole displayed the best ECL properties of those synthesized
Correlations in Nuclear Matter
We analyze the nuclear matter correlation properties in terms of the pair
correlation function. To this aim we systematically compare the results for the
variational method in the Lowest Order Constrained Variational (LOCV)
approximation and for the Bruekner-Hartree-Fock (BHF) scheme. A formal link
between the Jastrow correlation factor of LOCV and the Defect Function (DF) of
BHF is established and it is shown under which conditions and approximations
the two approaches are equivalent. From the numerical comparison it turns out
that the two correlation functions are quite close, which indicates in
particular that the DF is approximately local and momentum independent. The
Equations of State (EOS) of Nuclear Matter in the two approaches are also
compared. It is found that once the three-body forces (TBF) are introduced the
two EOS are fairly close, while the agreement between the correlation functions
holds with or without TBF.Comment: 11 figure
Multiplexable Kinetic Inductance Detectors
We are starting to investigate a novel multiplexable readout method that can be applied to a large class of superconducting pair-breaking detectors. This readout method is completely different from those currently used with STJ and TES detectors, and in principle could deliver large pixel counts, high sensitivity, and Fano-limited spectral resolution. The readout is based on the fact that the kinetic surface inductance L_s of a superconductor is a function of the density of quasiparticles n, even at temperatures far below T_c. An efficient way to measure changes in the kinetic inductance is to monitor the transmission phase of a resonant circuit. By working at microwave frequencies and using thin films, the kinetic inductance can be a significant part of the total inductance L, and the volume of the inductor can be made quite small, on the order of 1 µm^3. As is done with other superconducting detectors, trapping could be used to concentrate the quasiparticles into the small volume of the inductor. However, the most intriguing aspect of the concept is that passive frequency multiplexing could be used to read out ~10^3 detectors with a single HEMT amplifier
Benchmark ultra-cool dwarfs in widely separated binary systems
Ultra-cool dwarfs as wide companions to subgiants, giants, white dwarfs and
main sequence stars can be very good benchmark objects, for which we can infer
physical properties with minimal reference to theoretical models, through
association with the primary stars. We have searched for benchmark ultra-cool
dwarfs in widely separated binary systems using SDSS, UKIDSS, and 2MASS. We
then estimate spectral types using SDSS spectroscopy and multi-band colors,
place constraints on distance, and perform proper motions calculations for all
candidates which have sufficient epoch baseline coverage. Analysis of the
proper motion and distance constraints show that eight of our ultra-cool dwarfs
are members of widely separated binary systems. Another L3.5 dwarf, SDSS 0832,
is shown to be a companion to the bright K3 giant Eta Cancri. Such primaries
can provide age and metallicity constraints for any companion objects, yielding
excellent benchmark objects. This is the first wide ultra-cool dwarf + giant
binary system identified.Comment: 4 pages, 3 figures, conference, "New Technologies for Probing the
Diversity of Brown Dwarfs and Exoplanets", oral tal
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