1,592 research outputs found
Separator for alkaline batteries
Separator compositions have been tested as components of three-plate silver-zinc oxide cells in a standard cycling test. Six materials meet imposed requirements, giving cycling performance superior to cellophane
Dyes Containing Long-Chained Aliphatic Radicals
The investigation of the synthesis and properties of compounds containing long-chained aliphatic radicals has been extended to the preparation of several azo dyes, coupling products of ß-naphthol with the appropriately substituted aromatic diazonium chlorides. The dyes prepared include those from a series of three p-alkoxyanilines, ROC6H4NH2, where R is n-C12H25-, n-C14H29-, and n-C16H33-, all deep red in color; and two brighter red compounds from p-( N-alkylsulfonamido )-anilines, H2 NC6H4S02NHR, where R is n-C12H25- and n-C18H37-. These compounds are crystalline solids, soluble in the usual organic solvents and in fats and oils. The melting points of the compounds are such that they might serve as derivatives for the corresponding anilines. The compounds prepared and their melting points are: 1- (p-dodecoxyphenylazo )-2-naphthol, m. 80-82°; 1-(p-tetradecoxyphenylazo )-2-naphthol, m. 81.5-83°; 1-(p-hexadecoxyphenylazo )-2-naphthol, m. 82-84°; 1-[p-(N-dodecylsulfonamido )-phenylazo ]-2-naphthol, m. 163-164 ° ; and 1- [p-( N-octadecylsul fonamido) - phenylazo ]-2-naphthol, m. 158-159.5°
Kentucky Annual Economic Report 2020
This report is one of the important ways that the Center for Business and Economic Research fulfills its mission to examine various aspects of the Kentucky economy. The analysis and data presented here cover a variety of topics that range from an economic forecast for Kentucky in 2020 to a broad presentation of factors affecting the economy
The Economic Impacts of Land Use Policies in Lexington, Kentucky
Every five years, Lexington-Fayette Urban County Government’s Planning Commission adopts a comprehensive plan detailing goals and objectives that guide the city’s land use planning. Maintaining the city’s urban service area and preserving its rural and agricultural areas are integral parts of this plan. Within the urban service area, land is zoned to permit various types of urban uses such as residential, commercial, and industrial use. Land outside the urban service area is subject to several land use policies designed to preserve the rural characteristics of these areas. This report examines the effects of Lexington’s land use policies and specifically its urban service area
Magnetic field-induced spectroscopy of forbidden optical transitions with application to lattice-based optical atomic clocks
We develop a method of spectroscopy that uses a weak static magnetic field to
enable direct optical excitation of forbidden electric-dipole transitions that
are otherwise prohibitively weak. The power of this scheme is demonstrated
using the important application of optical atomic clocks based on neutral atoms
confined to an optical lattice. The simple experimental implementation of this
method -- a single clock laser combined with a DC magnetic field-- relaxes
stringent requirements in current lattice-based clocks (e.g., magnetic field
shielding and light polarization), and could therefore expedite the realization
of the extraordinary performance level predicted for these clocks. We estimate
that a clock using alkaline earth-like atoms such as Yb could achieve a
fractional frequency uncertainty of well below 10^-17 for the metrologically
preferred even isotopes
Measuring kinetic coefficients by molecular dynamics simulation of zone melting
Molecular dynamics simulations are performed to measure the kinetic
coefficient at the solid-liquid interface in pure gold. Results are obtained
for the (111), (100) and (110) orientations. Both Au(100) and Au(110) are in
reasonable agreement with the law proposed for collision-limited growth. For
Au(111), stacking fault domains form, as first reported by Burke, Broughton and
Gilmer [J. Chem. Phys. {\bf 89}, 1030 (1988)]. The consequence on the kinetics
of this interface is dramatic: the measured kinetic coefficient is three times
smaller than that predicted by collision-limited growth. Finally,
crystallization and melting are found to be always asymmetrical but here again
the effect is much more pronounced for the (111) orientation.Comment: 8 pages, 9 figures (for fig. 8 : [email protected]). Accepted for
publication in Phys. Rev.
Observation and absolute frequency measurements of the 1S0 - 3P0 optical clock transition in ytterbium
We report the direct excitation of the highly forbidden (6s^2) 1S0 - (6s6p)
3P0 optical transition in two odd isotopes of ytterbium. As the excitation
laser frequency is scanned, absorption is detected by monitoring the depletion
from an atomic cloud at ~70 uK in a magneto-optical trap. The measured
frequency in 171Yb (F=1/2) is 518,295,836,593.2 +/- 4.4 kHz. The measured
frequency in 173Yb (F=5/2) is 518,294,576,850.0 +/- 4.4 kHz. Measurements are
made with a femtosecond-laser frequency comb calibrated by the NIST cesium
fountain clock and represent nearly a million-fold reduction in uncertainty.
The natural linewidth of these J=0 to J=0 transitions is calculated to be ~10
mHz, making them well-suited to support a new generation of optical atomic
clocks based on confinement in an optical lattice.Comment: 4 pages, 3 figure
Randomized Comparison of Two Techniques for Titrating Power During Radiofrequency Ablation of Accessory Pathways
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75733/1/j.1540-8167.1996.tb00592.x.pd
Width of Sunspot Generating Zone and Reconstruction of Butterfly Diagram
Based on the extended Greenwich-NOAA/USAF catalogue of sunspot groups it is
demonstrated that the parameters describing the latitudinal width of the
sunspot generating zone (SGZ) are closely related to the current level of solar
activity, and the growth of the activity leads to the expansion of SGZ. The
ratio of the sunspot number to the width of SGZ shows saturation at a certain
level of the sunspot number, and above this level the increase of the activity
takes place mostly due to the expansion of SGZ. It is shown that the mean
latitudes of sunspots can be reconstructed from the amplitudes of solar
activity. Using the obtained relations and the group sunspot numbers by Hoyt
and Schatten (1998), the latitude distribution of sunspot groups ("the Maunder
butterfly diagram") for the 18th and the first half of the 19th centuries is
reconstructed and compared with historical sunspot observations.Comment: 16 pages, 11 figures; accepted by Solar Physics; the final
publication will be available at www.springerlink.co
Analysis of Strong-Coupling Parameters for Superfluid 3He
Superfluid He experiments show strong deviation from the weak-coupling
limit of the Ginzburg-Landau theory, and this discrepancy grows with increasing
pressure. Strong-coupling contributions to the quasiparticle interactions are
known to account for this effect and they are manifest in the five
-coefficients of the fourth order Ginzburg-Landau free energy terms. The
Ginzburg-Landau free energy also has a coefficient to include magnetic
field coupling to the order parameter. From NMR susceptibility experiments, we
find the deviation of from its weak-coupling value to be negligible at
all pressures. New results for the pressure dependence of four different
combinations of -coefficients, _{345}, _{12},
_{245}, and _{5} are calculated and comparison is made with
theory.Comment: 6 pages, 2 figures, 1 table. Manuscript prepared for QFS200
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