2,941 research outputs found
MEASUREMENT OF DYNAMIC SURFACE TENSION IN BUBBLING SYSTEMS
The static and dynamic surface tension was measured for aqueous solutions of eleven surface-active agents for the purpose of studying the effect of surface tension upon boiling heat transfer. The surfactants were chosen from the Tween, Aerosol, and Hyonic series. Dynamic surface tension, at T = 90 deg C, was investigated by observing the volume and frequency for air bubbles forming from a submerged orifice. Static surface tension, at T = 100 deg C, was measured using a duNouy tensiometer. In all cases, the dynamic surface tension for solutions of these surface active agents was less than the value for pure water, greater than the static value for the same concentration, and was a smoothly decreasing function of concentration. (auth
Calidad de carne en broilers alimentados con dietas a base de maíz o arroz integral suplementados cona-tocoferol y Selenio orgánico.
Neutrino oscillations in the Sun probe long-range leptonic forces
Lepton number charges might be the source of long range forces. If one
accepts that neutrinos produced in the Sun do indeed oscillate while crossing
the interior of the Sun, then the shift in the phase of the neutrino
wavefunction caused by an hypothetical potential associated to the leptonic
charge of the electrons in the Sun could affect the oscillation pattern beyond
what is actually observed. We show that a "fine structure" constant
in excess of is incompatible with present
observational data. This bound is not valid for forces whose range is shorter
than the size of the Sun.Comment: 6 pages, no figures. References adde
Polarization properties and dispersion relations for spiral resonances of a dielectric rod
Dielectric microcavities based on cylindrical and deformed cylindrical shapes
have been employed as resonators for microlasers. Such systems support spiral
resonances with finite momentum along the cylinder axis. For such modes the
boundary conditions do not separate and simple TM and TE polarization states do
not exist. We formulate a theory for the dispersion relations and polarization
properties of such resonances for an infinite dielectric rod of arbitrary
cross-section and then solve for these quantities for the case of a circular
cross-section (cylinder). Useful analytic formulas are obtained using the
eikonal (Einstein-Brillouin-Keller) method which are shown to be excellent
approximations to the exact results from the wave equation. The major finding
is that the polarization of the radiation emitted into the far-field is linear
up to a polarization critical angle (PCA) at which it changes to elliptical.
The PCA always lies between the Brewster and total-internal-reflection angles
for the dielectric, as is shown by an analysis based on the Jones matrices of
the spiraling rays.Comment: submitted to JOSA
The different molecular structure and glycerol-to-fatty acid ratio of palm oils affect their nutritive value in broiler chicken diets
The aim of this study is to assess how the fat molecular structure and its glycerol-to-fatty acid ratio (G : FA) affect the fatty acid (FA) apparent absorption of palm oils in broiler chickens. The experimental diets were the result of a basal diet supplemented with 6% of different palm oils. Native palm oil (N), rich in triacylglycerols, was the positive control (T1), and acid palm oil (A), rich in free FA, was the negative control (T2). In order to improve the nutritive value of A, two different nutritional strategies were performed. The first strategy was achieved by adding increasing amounts of free glycerol (G) (4% (T3), 8% (T4) and 16% (T5)) to A, and the second one by adding increasing amounts of mono- (MAG) and diacylglycerols (DAG), coming from re-esterified palm oil (E) (40% (T6), 70% (T7), and 100% (T8)) to A. As a result, eight dietary treatments were formulated with a G : FA ratio ranging from 0.04 to 0.67. These treatments were randomly assigned to 192 one-day-old female broiler chickens (Ross 308), distributed in 48 cages. The results showed how, by keeping the G : FA ratio constant (0.33 mol/mol), the diet with a high MAG and DAG content (T7) achieved higher saturated FA apparent absorption values than did the diet with a high triacylglycerol content (T1) and this, in turn, more than did the diet with a high free FA content (T4). The behavior of oils with high or low G : FA ratio was dependent on whether G was in a free state or esterified as part of acylglycerol molecules. Thus, increasing amounts of G to A did not enhance the total FA apparent absorption, but rather quite the opposite, even impairing the absorption of mono- and polyunsaturated FA. However, increasing amounts of E (rich in MAG and DAG) to A (rich in FFA) did enhance total FA apparent absorption, primarily due to the increased absorption of saturated FA. In conclusion, the greater the G : FA ratio of a palm oil, the greater the absorption of total FA, as long as G is esterified as part of acylglycerol molecules. Thus, the re-esterification process for obtaining E makes sense in order to give added value to A, achieving even greater digestibility values than does its corresponding N
Aquilegia, Vol. 27 No. 2, March-June 2003: Newsletter of the Colorado Native Plant Society
https://epublications.regis.edu/aquilegia/1097/thumbnail.jp
Aquilegia, Vol. 27 No. 1, January-February 2003: Newsletter of the Colorado Native Plant Society
https://epublications.regis.edu/aquilegia/1096/thumbnail.jp
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