6,467 research outputs found
Influence of Feeding Enzymatically Hydrolyzed Yeast Cell Wall on Growth Performance and Digestive Function of Feedlot Cattle during Periods of Elevated Ambient Temperature.
In experiment 1, eighty crossbred steers (239±15 kg) were used in a 229-d experiment to evaluate the effects of increasing levels of enzymatically hydrolyzed yeast (EHY) cell wall in diets on growth performance feedlot cattle during periods of elevated ambient temperature. Treatments consisted of steam-flaked corn-based diets supplemented to provide 0, 1, 2, or 3 g EHY/hd/d. There were no effects on growth performance during the initial 139-d period. However, from d 139 to harvest, when 24-h temperature humidity index averaged 80, EHY increased dry matter intake (DMI) (linear effect, p<0.01) and average daily gain (ADG) (linear effect, p = 0.01). There were no treatment effects (p>0.10) on carcass characteristics. In experiment 2, four Holstein steers (292±5 kg) with cannulas in the rumen and proximal duodenum were used in a 4×4 Latin Square design experiment to evaluate treatments effects on characteristics of ruminal and total tract digestion in steers. There were no treatment effects (p>0.10) on ruminal pH, total volatile fatty acid, molar proportions of acetate, butyrate, or estimated methane production. Supplemental EHY decreased ruminal molar proportion of acetate (p = 0.08), increased molar proportion of propionate (p = 0.09), and decreased acetate:propionate molar ratio (p = 0.07) and estimated ruminal methane production (p = 0.09). It is concluded that supplemental EHY may enhance DMI and ADG of feedlot steers during periods of high ambient temperature. Supplemental EHY may also enhance ruminal fiber digestion and decrease ruminal acetate:propionate molar ratios in feedlot steers fed steam-flaked corn-based finishing diets
Electrical conductivity of metal (hydr)oxide–activated carbon composites under compression. A comparison study
[EN]From a granular commercial activated carbon (AC) and six metal (hydr)oxide precursors, including
Al(NO3)3, Fe(NO3)3, SnCl2, TiO2, Na2WO4 and Zn(NO3)2, a broadly varied series of metal (hydr)oxideeAC
composites were prepared by wet impregnation and subsequent oven-drying at 120 C. Here, the
electrical conductivity of the resulting products was studied under moderate compression. The influence
of the applied pressure, sample volume, mechanical work, and density of the hybrid materials was
thoroughly investigated. The dc electrical conductivity of the compressed samples was measured at room
temperature by the four-probe method. Compaction assays show that the mechanical properties of the
composites are largely determined by the carbon matrix. Both the decrease in volume and the increase in
density under compression were very small and only significant at pressures lower than 100 kPa for AC
and most composites. By contrast, the bulk electrical conductivity of the hybrid materials was strongly
influenced by the nature, content and intrinsic conductivity of the supported metal phases, which act as
insulating thin layers thereby hindering the effective electron transport between AC cores of neighbouring
sample particles in contact under compression. Conductivity values for the composites were
lower than for the raw AC, all of them falling in the range of typical semiconductor materials. The
patterns of variation of the electrical conductivity with pressure and mechanical work were slightly
similar, thus suggesting the predominance of the pressure effects rather than the volume one
Observing the onset of outflow collimation in a massive protostar
The current paradigm of star formation through accretion disks, and
magnetohydrodynamically driven gas ejections, predicts the development of
collimated outflows, rather than expansion without any preferential direction.
We present radio continuum observations of the massive protostar W75N(B)-VLA 2,
showing that it is a thermal, collimated ionized wind and that it has evolved
in 18 years from a compact source into an elongated one. This is consistent
with the evolution of the associated expanding water-vapor maser shell, which
changed from a nearly circular morphology, tracing an almost isotropic outflow,
to an elliptical one outlining collimated motions. We model this behavior in
terms of an episodic, short-lived, originally isotropic, ionized wind whose
morphology evolves as it moves within a toroidal density stratification.Comment: See also Supplementary Materials
(SupMat_carrasco-gonzalez_etal_astroph.pdf) within the source file
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