Experimental pressure versus temperature isochoric – isoplethic curves for n-pentane – dimethyl ether, n-pentane – dimethyl ether – polybutadiene and n-pentane – dimethyl ether – polybutadiene– hydrogen at high pressures

Loci of isochoric - isoplethic experimental phase equilibrium data, were determined for the binary mixture dimethyl ether (DME) + n-pentane (C5); the ternary mixture: DME + C5 + polybutadiene (PB); and the quaternary mixture DME + C5 + PB + hydrogen (H2). Binary experiments were performed at varying overall density (ρ) and varying quantity of C5. Ternary experiments were performed at varying ρ and varying relative quantities of each light solvent. In the case of quaternary mixtures, the mass fraction of polymer was kept constant, and the amount of H2 and ρ were varied. The experimental data obtained for binary and ternary mixtures were correlated using the Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT) equation of state (EoS)

Herbicides in the Soil Environment: Linkage between Bioavailability and Microbial Ecology

Modern agriculture relies heavily on herbicides for the control of weeds in crops and pastures to maximize yields and economical benefits to sustain an increasing world population. The introduction of herbicide-resistant traits in several crops, such as glyphosate-resistant soybean, maize and canola, has further increased herbicide consumption worldwide. The environmental fate of herbicides is a matter of recent concern given that only a small fraction of the chemicals reaches the target organisms. While most herbicides are not intentionally applied onto soil, they can enter the soil environment from direct interception of spray by the soil surface during early season or post-harvest applications, from runoff or leaching of the herbicide from vegetation and/or from dead plant material. This chapter will present aspects of the behavior of herbicides in soils, focusing on soil retention and microbial degradation as main factors controlling persistence. The potential impact of herbicides on non-target soil microbes, on their processes and interactions, will be also discussed. The enormous variety of herbicides commercially available today makes it impossible to review all of them. Thus, this work will focus on some of the herbicides most used in the (semiarid) Pampa region of Argentina and worldwide (i.e., glyphosate, 2,4-dichlorophenoxyacetic acid, atrazine, metsulfuron-methyl), based on our own research data. Adsorption to soil is of critical importance for the regulation of herbicide persistence and mobility throughout the environment because sorption processes control the amount of herbicide present in the soil solution. These processes are dependent on several factors related to soil characteristics such as mineral composition, organic matter content, soil solution chemistry and to chemical characteristics of the herbicide. Soil-bound herbicide or residues are temporarily inactivated, which prevents harmful effects on soil biota but also makes them less bio-available for microbial degradation because most microbial species are not able to utilize herbicides in the sorbed state. Herbicide degradation will be discussed both in terms of their use as carbon and nutrient sources. Most isolated herbicide-degrading microorganisms belong to bacterial species, but fungi are also well-known for their capacity to degrade complex substrates, and may be more important than present isolation approaches have suggested. Differential toxicity of herbicides to soil microorganisms may alter community structure, including potential increases in plant or animal pathogens. Herbicides may also cause changes in microbial community function and concomitant impacts on soil health and ecosystem processes.Fil: Zabaloy, Maria Celina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; Argentina. Universidad Nacional del Sur. Departamento de Agronomía; ArgentinaFil: Zanini, Graciela Pilar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; Argentina. Universidad Nacional del Sur. Departamento de Agronomía; ArgentinaFil: Bianchinotti, Maria Virginia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; Argentina. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia; ArgentinaFil: Gomez, Marisa Anahi. Universidad Nacional del Sur. Departamento de Agronomía; ArgentinaFil: Garland, Jay L.. Dynamac Corporation; Estados Unido

Variations in strength-speed-power performance across the season: Do true changes occur in elite rugby players?

This study aimed to determine, through the use of a highly sensitive statistical tool, whether real changes in performance were present; and compare the rates of meaningful variations in strength, speed, and power parameters at different time-points during the competitive season in national team rugby players. Thirty-two players were assessed 5 times across the season using the following tests: squat jump and countermovement jump tests; 30-m sprint velocity; and one-repetition maximum (1RM) in the half-squat and bench-press exercises. A repeated-measures analysis of variance was conducted to test for differences between successive time-points. Individual coefficients of variation values were used to set target scores for post-measurements and examine whether changes in performance parameters were greater than the natural test variance, thus providing an indication of whether “true changes” occurred. No significant changes were detected in the vertical jump height, 1RM measures, and sprint velocity and momentum throughout the 11-month period (P \u3e 0.05). True changes occurred much more frequently for strength-power measures than for sprint velocity and momentum. Elite rugby union players did not exhibit significant variations in neuromuscular performance across the competitive period, when a group-based analysis was conducted. However, at the individual level, “true changes” in strength-power-(but not in speed-) related qualities were consistently observed over the competitive season

Process Simulation of Impurity Impacts on CO2 Fluids Flowing in Pipelines

YesCaptured carbon dioxide flowing in pipelines is impure. The impurities contained in the carbon dioxide fluid impact on the properties of the fluid. The impact of each impurity has not been adequately studied and fully understood. In this study, binary mixtures containing carbon dioxide and one impurity, at the maximum permitted concentration, flowing in pipelines are studied to understand their impact on pipeline performance. A hypothetical 70 km uninsulated pipeline is assumed and simulated using Aspen HYSYS (v.10) and gPROMS (v.5.1.1). The mass flow rate is 2,200,600 kg/h; the internal and external diameters are 0.711 m and 0.785 m. 15 MPa and 9 MPa were assumed as inlet and minimum pressures and 33 oC as the inlet temperature, to ensure that the fluid remain in the dense (subcritical or supercritical) phase. Each binary fluid is studied at the maximum allowable concentration and deviations from pure carbon dioxide at the same conditions is determined. These deviations were graded to rank the impurities in order of the degree of impact on each parameter. All impurities had at least one negative impact on carbon dioxide fluid flow. Nitrogen with the highest concentration (10-mol %) had the worst impact on pressure loss (in horizontal pipeline), density, and critical pressure. Hydrogen sulphide (with 1.5-mol %) had the least impact, hardly changing the thermodynamic properties of pure carbon dioxide

Saturated vapor pressure through a modified Lennard-Jones equation of state

A study was carried out to address the need to compute Lennard-Jones (LJ) densities as a function of temperature and pressure, in wide ranges of temperature and pressure, for further use in LJ-based viscosity computations. A high-quality LJ-EOS was chosen. Some of the compounds used include n-undecane, n-decane, ethane, methane, sulfur dioxide, propylene, m-xylene, ethyl acetate, isopropanol, and chloroform. An extrapolation scheme that makes possible calculate LJ densities or pressures at lower temperatures was proposed. The original LJ-EOS coupled to the extrapolation schemes was called EXT-LJ-EOS. It was possible to obtain a very good description of the pure compound vapor pressure curve for substances of diverse nature utilizing the EXT-LJ-EOS. However, all the options studied produced violations to the requirement which states that different pressure versus density isotherms should not intersect each other. Violations occurred only at relatively high reduced pressures. The constraint studied was a type of restriction (restriction (32)). It should be inspected in a wide enough temperature-density range whenever a temperature dependence is imposed on an EOS, regardless the nature of the EOS. Compliance with restriction (32) for pure compounds did not guarantee compliance for mixtures when using temperature dependent interaction parameters or temperature-dependent mixture covolume parameters. Restriction (32) could be embedded into constrained optimization computer programs used to fit pure compound or mixture parameters from experimental data. With such programs, restriction (32) should be evaluated at the conditions f the experimental data and within a wide-range temperature-density grid. Any proposed EOS temperature dependence could potentially violate constraint (32). A better representation of vapor pressures had a good compact on the LJ based prediction of viscosities.Fil: Machado, J. M. V.. Universidad de Porto; PortugalFil: Zabaloy, Marcelo Santiago. Universidad de Porto; Portugal. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Macedo, E. A.. Universidad de Porto; Portuga