Two-component plasma in a gravitational field

In this paper we study a model for the sedimentation equilibrium of a charged colloidal suspension: the two-dimensional two-component plasma in a gravitational field which is exactly solvable at a special value of the reduced inverse temperature Gamma=2. The density profiles are computed. The heavy particles accumulate at the bottom of the cointainer. If the container is high enough, an excess of light counterions form a cloud floating at some altitude.Comment: 17 pages, 3 Encapsulated Postscript figures, LaTeX with the graphicx packag

Consideraciones prácticas sobre la alimentación de bovinos de leche.

Una buena nutrición de la vaca en producción de leche, exige calidad del forraje, que suministre los nutrientes necesarios de acuerdo a los requerimientos del animal. Las necesidades nutricionales del ganado bovino de leche se relacionan directamente con la etapa productiva (mantenimiento, gestación y producción), siendo los nutrientes básicos: proteína, energía, minerales y vitaminas. Además de los forrajes, los alimentos concentrados tienen una función complementaria en la alimentación del ganado de leche, por su elevada digestibilidad y alta concentración de nutrientes. Su empleo debe realizarse en función del rendimiento o determinado nivel de producción. En la nutrición moderna, se buscan nuevas alternativas de alimentación del ganado de leche, teniendo en cuenta que la mayor parte de los costos de producción de un litro de leche, se deben a la alimentació

Onsager-Manning-Oosawa condensation phenomenon and the effect of salt

Making use of results pertaining to Painleve III type equations, we revisit the celebrated Onsager-Manning-Oosawa condensation phenomenon for charged stiff linear polymers, in the mean-field approximation with salt. We obtain analytically the associated critical line charge density, and show that it is severely affected by finite salt effects, whereas previous results focused on the no salt limit. In addition, we obtain explicit expressions for the condensate thickness and the electric potential. The case of asymmetric electrolytes is also briefly addressed.Comment: to appear in Phys. Rev. Let

Double perovskite cathodes for proton-conducting ceramic fuel cells: are they triple mixed ionic electronic conductors?

Published by National Institute for Materials Science in partnership with Taylor & Francis. 18 O and 2 H diffusion has been investigated at a temperature of 300 °C in the double perovskite material PrBaCo 2 O 5+δ (PBCO) in flowing air containing 200 mbar of 2 H 2 16 O. Secondary ion mass spectrometry (SIMS) depth profiling of exchanged ceramics has shown PBCO still retains significant oxygen diffusivity (~1.3 × 10 −11 cm 2 s −1 ) at this temperature and that the presence of water ( 2 H 2 16 O), gives rise to an enhancement of the surface exchange rate over that in pure oxygen by a factor of ~3. The 2 H distribution, as inferred from the 2 H 2 16 O − SIMS signal, shows an apparent depth profile which could be interpreted as 2 H diffusion. However, examination of the 3-D distribution of the signal shows it to be nonhomogeneous and probably related to the presence of hydrated layers in the interior walls of pores and is not due to proton diffusion. This suggests that PBCO acts mainly as an oxygen ion mixed conductor when used in PCFC devices, although the presence of a small amount of protonic conductivity cannot be discounted in these materials

Exact asymptotic expansions for the cylindrical Poisson-Boltzmann equation

The mathematical theory of integrable Painleve/Toda type systems sheds new light on the behavior of solutions to the Poisson-Boltzmann equation for the potential due to a long rod-like macroion. We investigate here the case of symmetric electrolytes together with that of 1:2 and 2:1 salts. Short and large scale features are analyzed, with a particular emphasis on the low salinity regime. Analytical expansions are derived for several quantities relevant for polyelectrolytes theory, such as the Manning radius. In addition, accurate and practical expressions are worked out for the electrostatic potential, which improve upon previous work and cover the full range of radial distances

Efecto del lasalocid sódico al 15% en la ceba de bovinos machos en pastoreo.

Con el fin de observar el uso del Lasalocid Sódico (LS) al 15% en Ia ceba de bovinos en pastoreo, se llevó a cabo este ensayo en una finca del municipio de Cumaral (Meta), situada a una altura de 600 m.s.n.m. y con una temperatura media de 26°C. Se utilizaron 40 bovinos machos cruzados de cebú x criollo, de 30 meses de edad y un peso promedio de 291 kg, distribuidos en dos grupos al azar y mantenidos en pastoreo continuo en una pradera con pasto Brachiaria decumbens y humidicola. El periodo experimental comprendió 119 días y Ia dosificación para el grupo de animales tratados (T2) tue de 200 mg de LS/animal/día. Los animales tratados (12) alcanzaron una ganancia diana de peso promedio de 7.81% a su favor, comparad con el grupo testigo (T1). Los resultados obtenidos permiten sugerir el uso de LS al 15% en Ia ceba de bovinos en pastoreo, como alternativa de importancia económica para Ia industria ganadera.The present work was made to investigate the use of Lasalocid Sodium 15% on the fattening beef cattle on pasture. The experiment was conducted in a farm located in Cumaral town, department of Meta, with 600 m.a.l.s. and 26°C mean temperature. All time the animals were mainteined in an continous pasture on an praire with Brwhi,uii decuinbens and hum/dice/a pasture ground. Forty cattle males brahaman X criollo, 30 months old with 219 kg average weight were used and distribuited in two treatments of twenty animals per treatment. The experimental work had a duration of 119 days and each group of animals treated (T2) recived 200 mg/animal/day of LS 15%. The results of this experiment indicate that the animals treated (T2) obtained a daily average weight of 7.81% more, compared with the control group (T1), and that LS 15% can be used in the fattening of beef cattle on pasture as an alternative for economic importance in the cattle industry.Ganado de doble propósito-Ganaderia doble proposit

Effect of lasalocid sodium 15% on the performance of fattening beef cattle

Con el fin de observar el uso del Lasalocid Sódico (LS) al 15% en la ceba de bovinos en pastoreo, se llevó a cabo este ensayo en una finca del municipio de Cumaral (Meta), situada a una altura de 600 m.s.n.m. y con una temperatura media de 26°C. Se utilizaron 40 bovinos machos cruzados de cebú x criollo, de 30 meses de edad y un peso promedio de 291 kg, distribuidos en dos grupos al azar y mantenidos en pastoreo continuo en una pradera con pasto Brachiaria decumbens y humidicola. El período experimental comprendió 119 días y la dosificación para el grupo de animales tratados fue de 200 mg de LS/animal/día. Los animales tratados alcanzaron una ganancia diaria de peso promedio de 7.81% a su favor, comparado con el grupo testigo. Los resultados obtenidos permiten sugerir el uso de LS al 15% en la ceba de bovinos en pasatoreo, como alternativa de importancia económica para la industria ganadera.The present work was made to investigate the use of Lasalocid Sodium 15% on the fattening beef cattle on pasture. The experiment was conducted in a farm located in Cumaral town, department of Meta, with 600 m.a.l.s. and 26°C mean temperature. All time the animals were mainteined in an continous pasture on an praire with Brwhi,uii decuinbens and hum/dice/a pasture ground. Forty cattle males brahaman X criollo, 30 months old with 219 kg average weight were used and distribuited in two treatments of twenty animals per treatment. The experimental work had a duration of 119 days and each group of animals treated (T2) recived 200 mg/animal/day of LS 15%. The results of this experiment indicate that the animals treated (T2) obtained a daily average weight of 7.81% more, compared with the control group (T1), and that LS 15% can be used in the fattening of beef cattle on pasture as an alternative for economic importance in the cattle industry.Ganado de doble propósito-Ganaderia doble proposit

A Generalization of the Stillinger-Lovett Sum Rules for the Two-Dimensional Jellium

In the equilibrium statistical mechanics of classical Coulomb fluids, the long-range tail of the Coulomb potential gives rise to the Stillinger-Lovett sum rules for the charge correlation functions. For the jellium model of mobile particles of charge $q$ immersed in a neutralizing background, the fixing of one of the $q$-charges induces a screening cloud of the charge density whose zeroth and second moments are determined just by the Stillinger-Lovett sum rules. In this paper, we generalize these sum rules to the screening cloud induced around a pointlike guest charge $Z q$ immersed in the bulk interior of the 2D jellium with the coupling constant $\Gamma=\beta q^2$ ($\beta$ is the inverse temperature), in the whole region of the thermodynamic stability of the guest charge $Z>-2/\Gamma$. The derivation is based on a mapping technique of the 2D jellium at the coupling $\Gamma$ = (even positive integer) onto a discrete 1D anticommuting-field theory; we assume that the final results remain valid for all real values of $\Gamma$ corresponding to the fluid regime. The generalized sum rules reproduce for arbitrary coupling $\Gamma$ the standard Z=1 and the trivial Z=0 results. They are also checked in the Debye-H\"uckel limit $\Gamma\to 0$ and at the free-fermion point $\Gamma=2$. The generalized second-moment sum rule provides some exact information about possible sign oscillations of the induced charge density in space.Comment: 16 page

Collective modes and correlations in one-component plasmas

The static and time-dependent potential and surface charge correlations in a plasma with a boundary are computed for different shapes of the boundary. The case of a spheroidal or spherical one-component plasma is studied in detail because experimental results are available for such systems. Also, since there is some knowlegde both experimental and theoretical about the electrostatic collective modes of these plasmas, the time-dependent correlations are computed using a method involving these modes.Comment: 20 pages, plain TeX, submitted to Phys. Rev.

Optimization of MIL-178(Fe) and Pebax® 3533 loading in mixed matrix membranes for CO2 capture

Global warming is considered as a consequence of extensive use of fossil fuels. Post combustion CO2 capture is an interesting and alternative solution where mixed matrix membranes (MMMs) can be an exciting candidate. This research focuses on the optimization of MMM composition consisting of Pebax® 3533 as the polymer matrix and porous coordination polymer (PCP) MIL-178(Fe) as a filler for gas separation application. MIL-178(Fe) characterized with SEM, TEM and TGA were applied to compare bare polymer and MMM. Optimum composition of the MMM obtained was 5 wt.% MIL-178(Fe) in Pebax® 3533. Average thickness of the optimized dense MMM was 116 ± 8 µm. Such MMM showed CO2 permeability and CO2/N2 selectivity of 312 ± 5 Barrer and 25.0 ± 0.5, respectively, 12% and 25% improved regarding the bare membrane. Additionally, optimum MMM was applied for CO2/CH4 separation and successfully compared in terms of improved CO2 permeability and CO2/CH4 selectivity