21,710 research outputs found
Inclusion Polymerization and Doping in Zeolite Channels. Polyaniline
Aniline has been polymerized in the three-dimensional channel system of zeolite Y. The monomer was diffused into zeolites with different levels of acidity from hexane solution. Subsequent admission of peroxydisulfate or iodate from aqueous solution yielded the intrazeolite polymers, as demonstrated by FT-IR, electronic absorption data and recovery of the included polymer. With S2O82-, the intrazeolite products are a function of the proton content of the zeolite. Polymer is only formed when a sufficient supply of protons is present in the zeolite host. When neutral iodate solution is used, no polymer is formed in NaY and acid zeolites, but at low pH aniline polymerizes in all zeolites. The open pore system of the zeolite host can be accessed by base such that the intrazeolite protonated polymer is transformed into the corresponding neutral polymer.
The polymer chains encapsulated in zeolite hosts represent a new class of low- dimensional electronic materials
Implications and Considerations Concerning the Status, Habitat and Distribution of the Least Brook Lamprey, Lampetra aepyptera (Abbott) (Pisces: Petromyzontidae) in Arkansas
Mandibular Attachment Device Effects on African American Veterans with Heart Failure
Heart failure is a growing epidemic that affects people nationwide and is disproportionate to African Americans. The purpose of this quantitative repeated measures study was to determine whether mandibular attachment device (MAD) therapy impacts symptoms of heart failure in African American male veterans diagnosed with obstructive sleep apnea (OSA). The oxidative stress theory was applied in this study to assess whether MAD therapy received from Veterans Affairs (VA) dental clinics impacted heart failure symptoms, after controlling for patient body mass index (BMI) levels and smoking status. Research questions examined whether MAD had a significant effect on symptoms of heart failure in male African American veterans with OSA and whether BMI and smoking caused a moderating effect on MAD therapy treating efficacy on symptoms of heart failure. Secondary data from the VA was captured through the VA informatics and computing infrastructure. Data obtained from 29 records were analyzed using the statistical package for the social sciences. The repeated measures multivariate analysis of variance and the repeated measures multivariate analysis of covariance were used to assess the magnitude of change in heart failure symptoms (ejection fraction, systolic blood pressure, diastolic blood pressure, oxygen saturation, brain natriuretic peptide, n-terminal pro-brain natriuretic peptide, and troponins levels) while controlling for the 2 covariates. Results showed a positive mean change in systolic blood pressure while using the MAD and a negative moderated effect after controlling for BMI at 4-months on oxygen saturation. This study will aid positive social change by providing new data that can be used by the public health field towards an alternative treatment
Unknotting numbers and triple point cancelling numbers of torus-covering knots
It is known that any surface knot can be transformed to an unknotted surface
knot or a surface knot which has a diagram with no triple points by a finite
number of 1-handle additions. The minimum number of such 1-handles is called
the unknotting number or the triple point cancelling number, respectively. In
this paper, we give upper bounds and lower bounds of unknotting numbers and
triple point cancelling numbers of torus-covering knots, which are surface
knots in the form of coverings over the standard torus . Upper bounds are
given by using -charts on presenting torus-covering knots, and lower
bounds are given by using quandle colorings and quandle cocycle invariants.Comment: 26 pages, 14 figures, added Corollary 1.7, to appear in J. Knot
Theory Ramification
Strings in gravity with torsion
A theory of gravitation in 4D is presented with strings used in the material
action in spacetime. It is shown that the string naturally gives rise to
torsion. It is also shown that the equation of motion a string follows from the
Bianchi identity, gives the identical result as the Noether conservation laws,
and follows a geodesic only in the lowest order approximation. In addition, the
conservation laws show that strings naturally have spin, which arises not from
their motion but from their one dimensional structure.Comment: 16 page
Bose-Einstein Condensation of Magnons in Cs2CuCl4
We report on results of specific heat measurements on single crystals of the
frustrated quasi-2D spin-1/2 antiferromagnet Cs_2CuCl_4 (T_N=0.595 K) in
external magnetic fields B30 mK. Decreasing B from
high fields leads to the closure of the field-induced gap in the magnon
spectrum at a critical field B_c = 8.51 T and a magnetic phase transition is
clearly seen below B_c. In the vicinity to B_c, the phase transition boundary
is well described by the power-law T_c(B)\propto (B_c-B)^{1/\phi} with the
measured critical exponent \phi\simeq 1.5. These findings are interpreted as a
Bose-Einstein condensation of magnons.Comment: 5 pages, 4 figures, experiment and theor
New magnetic phase in metallic V_{2-y}O_3 close to the metal insulator transition
We have observed two spin density wave (SDW) phases in hole doped metallic
V_{2-y}O_3, one evolves from the other as a function of doping, pressure or
temperature. They differ in their response to an external magnetic field, which
can also induce a transition between them. The phase boundary between these two
states in the temperature-, doping-, and pressure-dependent phase diagram has
been determined by magnetization and magnetotransport measurements. One phase
exists at high doping level and has already been described in the literature.
The second phase is found in a small parameter range close to the boundary to
the antiferromagnetic insulating phase (AFI). The quantum phase transitions
between these states as a function of pressure and doping and the respective
metamagnetic behavior observed in these phases are discussed in the light of
structurally induced changes of the band structure.Comment: REVTeX, 8 pages, 12 EPS figures, submitted to PR
Northern JHK Standard Stars for Array Detectors
We report J, H and K photometry of 86 stars in 40 fields in the northern
hemisphere. The fields are smaller than or comparable to a 4x4 arcmin
field-of-view, and are roughly uniformly distributed over the sky, making them
suitable for a homogeneous broadband calibration network for near-infrared
panoramic detectors. K magnitudes range from 8.5 to 14, and J-K colors from
-0.1 to 1.2. The photometry is derived from a total of 3899 reduced images;
each star has been measured, on average, 26.0 times per filter on 5.5 nights.
Typical errors on the photometry are about 0.012.Comment: 10 pages including 3 figures, one separate figure on four pages. The
finding chart of the AS-30 field and a few coordinates have been corrected.
GIF finding charts can also be found at
http://www.arcetri.astro.it/~hunt/std.htm
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