Pollutant formation in fuel lean recirculating flows

An opposed reacting jet combustor (ORJ) was tested at a pressure of 1 atmosphere. A premixed propane/air stream was stabilized by a counterflowing jet of the same reactants. The resulting intensely mixed zone of partially reacted combustion products produced stable combustion at equivalence ratios as low as 0.45. Measurements are presented for main stream velocities of 7.74 and 13.6 m/sec with an opposed jet velocity of 96 m/sec, inlet air temperatures from 300 to 600 K, and equivalence ratios from 0.45 to 0.625. Fuel lean premixed combustion was an effective method of achieving low NOx emissions and high combustion efficiencies simultaneously. Under conditions promoting lower flame temperature, NO2 constituted up to 100 percent of the total NOx. At higher temperatures this percentage decreased to a minimum of 50 percent

Demandas institucionales en costos de la ganadería del SO Bonaerense

La cadena bovina integra un campo organizacional conformado por actores que representan una red estructurada de relaciones sociales (Machado-Da-Silva et al., 2010). Allí se canalizan presiones de conformidad para lograr competitividad y legitimidad (Pache & Santos, 2010), que implica la adaptación de la organización a un entorno institucional.Área: Ciencias Agrícolas, Produccion y Salud Anima

FJP: Entre los aportantes y la inversión real

Este artículo intenta responder a tres preguntas: ¿fueron las administradoras buenas agentes de los aportantes? ¿cuánto es realmente la proporción invertida en el sector público? ¿cómo incentivar la financiación de la inversión real? Durante el período septiembre 1994 a julio de 2001 la performance de los FJP corregida por efectos contables superó a los índices testigo de las inversiones locales. A agosto de 2001 el 66% de los FJP se concentraba en deuda del sector público, y solo un 14% en títulos del sector privado doméstico no financiero. Esto no puede ser explicado solo por los compromisos asumidos en el "blindaje", y se atribuye a incentivos regulatorios. El devengamiento de una rentabilidad contable sin volatilidad de títulos públicos en cuenta de inversión alentó su tenencia. Dadas las penalizaciones a las administradoras con menor rentabilidad relativa , se desincentivó la tenencia de títulos privados de escasa negociación por su contabilización a precios que no reflejan los cambios de su riesgo sistémico.

Structural properties in Sr0.61a0.39Nb2O6 in the temperature range 10 K to 500 K investigated by high-resolution neutron powder diffraction and specific heat measurements

We report high-resolution neutron powder diffraction on Sr0.61Ba0.39Nb2O6, SBN61, in the temperature range 15-500 K. The results indicate that the low-temperature anomalies (T<100K) observed in the dielectric dispersion are due to small changes in the incommensurate modulation of the NbO6-octahedra, as no structural phase transition of the average structure was observed. This interpretation is supported by specific heat measurements, which show no latent heat, but a glass-like behavior at low temperatures. Furthermore we find that the structural changes connected with the ferroelectric phase transition at Tc approx. 350K start already at 200K, explaining the anisotropic thermal expansion in the temperature range 200-300K observed in a recent x-ray diffraction study.Comment: Accepted by PRB (2006

Interplay between structure and magnetism in the low-dimensional spin system K(C8H16O4)2CuCl3∗H2OK(C_8H_{16}O_4)_2CuCl_3{*}H_2O

Materials based on a crown ether complex together with magnetic ions, especially Cu(II), can be used to synthesize new low dimesional quantum spin systems. We have prepared the new crown ether complex Di-\mu-chloro-bis(12-crown-4)-aquqdichloro-copper(II)-potassium, $K(C_8H_{16}O_4)_2CuCl_3{*}H_2O$ (1), determined its structure, and analyzed its magnetic properties. Complex (1) has a monoclinic structure and crystallizes in space group $P2_1/n$ with the lattice parameters of $a=9.5976(5)\r{A}$, $b=11.9814\r{A}, c=21.8713\r{A}$ and $\beta=100.945(4)\deg$. The magnetic properties of this compound have been investigated in the temperature range 1.8 K - 300 K. The magnetic susceptibility shows a maximum at 23 K, but no 3-D long range magnetic order down to 1.8 K. The S=1/2 Cu(II) ions form antiferromagnetically coupled dimers with Cu-Cl distances of $2.2554(8)\r{A}$ and $4.683(6)\r{A}$, and a Cu-Cl-Cu angle of $115.12(2)\deg$ with $2J_{dimer}=-2.96meV (-23.78 cm^{-1})$. The influence of $H_2O$ on the Cl-Cu-Cl exchange path is analyzed. Our results show that the values of the singlet-triplet splitting are increasing considering $H_2O$ molecules in the bridging interaction. This is supported by Density functional theory (DFT) calculations of coupling constants with Perdew and Wang (PWC), Perdew, Burke and Ernzenrhof (PBE) and strongly constrained and appropriately normed (SCAN) exchange-correlation function show excellent agreement for the studied compound

Observation of vortex-nucleated magnetization reversal in individual ferromagnetic nanotubes

The reversal of a uniform axial magnetization in a ferromagnetic nanotube (FNT) has been predicted to nucleate and propagate through vortex domains forming at the ends. In dynamic cantilever magnetometry measurements of individual FNTs, we identify the entry of these vortices as a function of applied magnetic field and show that they mark the nucleation of magnetization reversal. We find that the entry field depends sensitively on the angle between the end surface of the FNT and the applied field. Micromagnetic simulations substantiate the experimental results and highlight the importance of the ends in determining the reversal process. The control over end vortex formation enabled by our findings is promising for the production of FNTs with tailored reversal properties.Comment: 20 pages, 13 figure