Resultados de la amonificación con urea sobre la degradabilidad ruminal de Hemarthria altissima y Cynodon nlemfuensis en bovinos

El objetivo del ensayo fue evaluar el efecto del agregado de urea sobre la degradabilidad de la materia seca en henos de Hemarthria altissima cv bigalta (pasto clavel) y Cynodon nlemfuensis (pasto estrella). Los trabajos se realizaron desde marzo de 2011 a marzo de 2012 en la Estación Experimental Colonia Benítez del Instituto Nacional de Tecnología Agropecuaria-INTA (Chaco, Argentina). Muestras del material de ambos vegetales fueron deshidratadas y luego amonificadas con diferentes porcentajes de urea (0; 2; 4; 6%). Luego, según la técnica de “suspensión in situ”, fueron introducidas en el rumen de cuatro novillos cruza cebú de 3,5 años de edad y 420 kg de peso vivo, a través de una cánula ruminal implantada en el ijar izquierdo. Para la estimación de la cinética de digestión de la materia seca (MS), se utilizó el modelo propuesto por Orskov et al. (1980). La degradabilidad efectiva se calculó de acuerdo a la ecuación de los mismos autores. La cinética de la degradación de H. altissima no arrojó diferencias significativas. En cambio, para C. nlemfuensis se registraron diferencias para la degradabilidad ruminal de MS a tasas del 4% (p=0,01) y 2% (p=0,02), en ambos casos con presentación de efectos cúbico y cuadrático. Se concluye que la degradabilidad ruminal de la MS del heno de H. altissima no sufrió cambios con el agregado de urea, en cambio, se registró mayor degradabilidad en aquéllos henos de C. nlemfuensis que recibieron urea a razón de 20 y 40 g por kg de pasto seco.The objective was to evaluate the effect of adding urea on the degradability of the dry matter in hays Hemarthria altissima cv. bigalta (grass carnation) and Cynodon nlemfuensis (star grass). At the Experimental Station INTA (Colonia Benítez, Chaco, Argentina), between march 2011 and march 2012, samples of plant material were obtained, dehydrated and ammonified with different percentages of urea (0; 2; 4; 6%), according to the technique of “in situ suspension” proposed by Orskov et al. (1980). Aliquot of grass were introduced into the rumen of four steers zebu (3,5 years old, 420 kg liveweight) with rumen cannula in the left flank, also is calculated effective degradability using the equation by the same authors to estimate the kinetics of digestion of dry matter. The kinetics of degradation carnation grass showed no statistical difference. However in star grass, it was observed differences for the degradability rate of 4% (p=0.01) and 2% (p=0.02), presenting a quadratic and cubic effect in both cases.EEA Colonia BenitezFil: Martínez, E.V. Universidad Nacional del Nordeste. Facultad de Ciencias Veterinarias. Cátedra de Nutrición y Alimentación; ArgentinaFil: Slanac, Alcides L. Universidad Nacional del Nordeste. Facultad de Ciencias Veterinarias. Cátedra de Fisiología; ArgentinaFil: Kucseva, Cesar Daniel. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Colonia Benítez; Argentin

Antioxidant activity of alkaloids from Bocconia arborea. A study on six testing methods

El fraccionamiento de la actividad antioxidante dirigida por actividad, junto con el análisis químico, llevaron al aislamiento de tres alcaloides de benzofenantridina del extracto de metanol de la corteza de Bocconia arborea. La identificación se basó en métodos espectroscópicos. Se analizó la actividad antioxidante de los alcaloides aislados 6- acetonildihidroqueleritrina, queleritrina y dihidroqueleritrina en ensayos de tiocianato, la actividad de barrido de los radicales libres, el método de decoloración del b-caroteno y el ensayo de la desoxirribosa. Todos los alcaloides mostraron actividad antioxidante significativa en ácido linoleico y b-caroteno. Además de conceder protección frente a la desoxirribosa, la peroxidación liposómica y los lípidos microsomiales de la peroxidación, también presentaron efectos de barrido en los radicales de 1,1-difenil-2-picrilhidrazil.Antioxidative activity-guided fractionation together with chemical analysis led to the isolation of three benzophenanthridine alkaloids from methanol extract of the bark of Bocconia arborea. Identification was based on spectroscopic methods. The isolated alkaloids 6-acetonyldihydrochelerythrine, chelerythrine and dihydrochelerythrine were tested for antioxidative activity on thiocyanate assays, free radical scavenging activity, b-carotene bleaching method, and deoxyribose assay. All alkaloids exhibited significant antioxidant activities in linoleic acid and b-carotene. Although afforded protection against the damage of deoxyribose, liposome peroxidation and microsomial lipid from peroxidation, also exhibited scavenging effects on the 1,1-diphenyl-2-picrylhydrazyl radicals

Stokes Diagnostis of 2D MHD-simulated Solar Magnetogranulation

We study the properties of solar magnetic fields on scales less than the spatial resolution of solar telescopes. A synthetic infrared spectropolarimetric diagnostics based on a 2D MHD simulation of magnetoconvection is used for this. We analyze two time sequences of snapshots that likely represent two regions of the network fields with their immediate surrounding on the solar surface with the unsigned magnetic flux density of 300 and 140 G. In the first region we find from probability density functions of the magnetic field strength that the most probable field strength at logtau_5=0 is equal to 250 G. Weak fields (B < 500 G) occupy about 70% of the surface, while stronger fields (B 1000 G) occupy only 9.7% of the surface. The magnetic flux is -28 G and its imbalance is -0.04. In the second region, these parameters are correspondingly equal to 150 G, 93.3 %, 0.3 %, -40 G, and -0.10. We estimate the distribution of line-of-sight velocities on the surface of log tau_5=-1. The mean velocity is equal to 0.4 km/s in the first simulated region. The averaged velocity in the granules is -1.2 km/s and in the intergranules is 2.5 km/s. In the second region, the corresponding values of the mean velocities are equal to 0, -1.8, 1.5 km/s. In addition we analyze the asymmetry of synthetic Stokes-V profiles of the Fe I 1564.8 nm line. The mean values of the amplitude and area asymmetry do not exceed 1%. The spatially smoothed amplitude asymmetry is increased to 10% while the area asymmetry is only slightly varied.Comment: 24 pages, 12 figure

Origin of inverse Rashba-Edelstein effect detected at the Cu/Bi interface using lateral spin valves

The spin transport and spin-to-charge current conversion properties of bismuth are investigated using permalloy/copper/bismuth (Py/Cu/Bi) lateral spin valve structures. The spin current is strongly absorbed at the surface of Bi, leading to ultrashort spin-diffusion lengths. A spin-to-charge current conversion is measured, which is attributed to the inverse Rashba-Edelstein effect at the Cu/Bi interface. The spin-current-induced charge current is found to change direction with increasing temperature. A theoretical analysis relates this behavior to the complex spin structure and dispersion of the surface states at the Fermi energy. The understanding of this phenomenon opens novel possibilities to exploit spin-orbit coupling to create, manipulate, and detect spin currents in two-dimensional systems

The inclusive 56Fe(nu_e,e-)56Co cross section

We study the 56Fe(nu_e,e^-)56Co cross section for the KARMEN neutrino spectrum. The Gamow-Teller contribution to the cross section is calculated within the shell model, while the forbidden transitions are evaluated within the continuum random phase approximation. We find a total cross section of 2.73 x 10^-40 cm^2, in agreement with the data.Comment: 4 pages, 1 figure. Replaced due to new improved calculation

Solar Intranetwork Magnetic Elements: bipolar flux appearance

The current study aims to quantify characteristic features of bipolar flux appearance of solar intranetwork (IN) magnetic elements. To attack such a problem, we use the Narrow-band Filter Imager (NFI) magnetograms from the Solar Optical Telescope (SOT) on board \emph{Hinode}; these data are from quiet and an enhanced network areas. Cluster emergence of mixed polarities and IN ephemeral regions (ERs) are the most conspicuous forms of bipolar flux appearance within the network. Each of the clusters is characterized by a few well-developed ERs that are partially or fully co-aligned in magnetic axis orientation. On average, the sampled IN ERs have total maximum unsigned flux of several 10^{17} Mx, separation of 3-4 arcsec, and a lifetime of 10-15 minutes. The smallest IN ERs have a maximum unsigned flux of several 10^{16} Mx, separations less than 1 arcsec, and lifetimes as short as 5 minutes. Most IN ERs exhibit a rotation of their magnetic axis of more than 10 degrees during flux emergence. Peculiar flux appearance, e.g., bipole shrinkage followed by growth or the reverse, is not unusual. A few examples show repeated shrinkage-growth or growth-shrinkage, like magnetic floats in the dynamic photosphere. The observed bipolar behavior seems to carry rich information on magneto-convection in the sub-photospheric layer.Comment: 26 pages, 14 figure

Small-scale solar magnetic fields

As we resolve ever smaller structures in the solar atmosphere, it has become clear that magnetism is an important component of those small structures. Small-scale magnetism holds the key to many poorly understood facets of solar magnetism on all scales, such as the existence of a local dynamo, chromospheric heating, and flux emergence, to name a few. Here, we review our knowledge of small-scale photospheric fields, with particular emphasis on quiet-sun field, and discuss the implications of several results obtained recently using new instruments, as well as future prospects in this field of research.Comment: 43 pages, 18 figure

SPINOR: Visible and Infrared Spectro-Polarimetry at the National Solar Observatory

SPINOR is a new spectro-polarimeter that will serve as a facility instrument for the Dunn Solar Telescope at the National Solar Observatory. This instrument is capable of achromatic polarimetry over a very broad range of wavelengths, from 430 up to 1600 nm, allowing for the simultaneous observation of several visible and infrared spectral regions with full Stokes polarimetry. Another key feature of the design is its flexibility to observe virtually any combination of spectral lines, limited only by practical considerations (e.g., the number of detectors available, space on the optical bench, etc).Comment: To appear in Solar Physics. Note: Figures are low resolution versions due to file size limitation