Search results for "mixture"

Mapping Ash CaCO3, pH, and Extractable Elements Using Principal Component Analysis

2017

Abstract Ash cover in fire-affected areas is an important factor in the reduction of soil erosion and increased availability of soil nutrients. Thus it is important to understand the spatial distribution of ash and its capacity for soil protection and to provide nutrients to the underlying soil. In this work, we aimed to map ash CaCO3, pH, and select extractable elements using a principal component analysis (PCA). Four days after a medium to severe wildfire, we established a grid in a 9 ×27 m area on a west facing slope and took ash samples every 3 m for a total of 40 sampling points. The PCA carried out retained five different factors. Factor 1 had high positive loadings for ash with elect…

Anti-Arrhenian behaviour of conductivity in octanoic acid–bis(2-ethylhexyl)amine systems: a physico-chemical study

2015

Pure surfactant liquids and their binary mixtures, owing to the amphiphilic nature of the molecules involved, can exhibit nano-segregation and peculiar transport properties. The structural and dynamic properties of octanoic acid (OA)–bis(2-ethylhexyl)amine (BEEA) liquid mixtures at various compositions have been studied by Wide Angle X-ray Scattering (WAXS), 1H-NMR and broadband dielectric spectroscopy as a function of temperature. It was found that the self-assembly occurs via proton exchange between the OA COOH group and the BEEA NH one; such self-assembled local structures are affected anisotropically by a temperature increase so that the thermal dilatation is more marked in a direction …

Non-ideal mixing behavior in dibutyl phosphate-propylamine binary liquids: Dielectric and nuclear magnetic resonance investigations

2021

Abstract Owing to the amphiphilic nature of their constituent molecules, binary mixtures of pure liquid surfactants are usually characterized by enhanced nano-segregation and thus can exhibit interesting transport properties and complex macroscopic behavior. In this ambit it was recently shown by Turco Liveri et al. (J. Mol. Liq. 263 (2018) 274–281) at room temperature that mixtures of short aliphatic chains compounds, such as dibutyl phosphate (DBP) and n-propylamine (PA) liquids, due to their ability to allow for phosphate-to-amine proton transfer, display ionic liquid–like behavior with composition-dependent enhanced conductivity, viscosity, and magnetically-induced birefringence. To und…

Ti-Al Membranes for Microfiltration

2016

Porous membranes made of Ti – 48 at. % Al intermetallic compound was obtained by elemental powder synthesis. These disks can be used as microfiltration membranes due to their low pores size and interconnected porosity. During this study titanium (purity 99.5%) and aluminum (purity 99 %) with low particle size range were mixed in corresponding ratios. The powder mixture was pressed at 500 MPa and the samples were heat treated in two stages. In the first step is the forming of Al3Ti compound by a solid state reaction at a temperature of 640 °C, slightly below the melting point of aluminum. In the second step the Ti-Al compound was formed at the temperature of 1300 °C and the sintering the por…

MoSi2 Formation Mechanisms during a Spark Plasma Synthesis from Mechanically Activated Powder Mixture

2010

2016

Despite hundreds of cationic bis-cyclometalated iridium(III) complexes having been explored as emitters for light-emitting electrochemical cells (LEECs), uniformly their composition has been in the form of a racemic mixture of Λ and Δ enantiomers. The investigation of LEECs using enantiopure iridium(III) emitters, however, remains unprecedented. Herein, we report the preparation, the crystal structures, and the optoelectronic properties of two families of cyclometalated iridium(III) complexes of the form of [(C^N)2Ir(dtBubpy)]PF6 (where dtBubpy is 4,4′-di-tert-butyl-2,2′-bipyridine) in both their racemic and enantiopure configurations. LEEC devices using Λ and Δ enantiomers as well as the r…

Humidity effects on gravitational settling and Brownian diffusion of atmospheric aerosol particles

1977

The dependency on relative humidity of the settling velocity of aerosol particles in stagnant air and of the diffusion coefficient due to Brownian motion of aerosol particles was computed for six aerosol types and different particles sizes in dry state. The computations are based (1) on mean bulk densities of dry aerosol particles obtained from measurements or from the knowledge of the chemical composition of the particles, (2) on micro-balance measurements of the water uptake per unit mass of dry aerosol substance versus water activity at thermodynamic equilibrium, and (3) on measurements of the equilibrium water activity of aqueous sea salt solutions. The results show a significant depend…

Research on the electrostatic properties of liquid dielectric mixtures

2007

Abstract This paper presents research results, which confirm the possibility of influencing the electrostatic charge tendency (ECT) of selected mixtures of purely insulating liquids. Tests were performed in a spinning disk system, where the factors influencing the value of the electrification current consisted of variable composition of the toluene–cyclohexane mixture, rotational speed, and a disk diameter. Liquid hydrocarbon mixtures displayed changes in ECT as well as classic insulation parameters such as resistivity and relative permittivity for concentration changes of the admixtures. These results can be used to assist the search for inhibitors of ECT and of aging processes in insulati…

Linear and nonlinear fractional hereditary constitutive laws of asphalt mixtures

2016

The aim of this paper is to propose a fractional viscoelastic and viscoplastic model of asphalt mixtures using experimental data of several tests such as creep and creep recovery performed at different temperatures and at different stress levels. From a best fitting procedure it is shown that both the creep one and recovery curve follow a power law model. It is shown that the suitable model for asphalt mixtures is a dashpot and a fractional element arranged in series. The proposed model is also available outside of the linear domain but in this case the parameters of the model depend on the stress level.

Statics and dynamics of colloid-polymer mixtures near their critical point of phase separation: A computer simulation study of a continuous Asakura–O…

2008

We propose a new coarse-grained model for the description of liquid-vapor phase separation of colloid-polymer mixtures. The hard-sphere repulsion between colloids and between colloids and polymers, which is used in the well-known Asakura-Oosawa (AO) model, is replaced by Weeks-Chandler-Anderson potentials. Similarly, a soft potential of height comparable to thermal energy is used for the polymer-polymer interaction, rather than treating polymers as ideal gas particles. It is shown by grand-canonical Monte Carlo simulations that this model leads to a coexistence curve that almost coincides with that of the AO model and the Ising critical behavior of static quantities is reproduced. Then the …