Optimization of Oil-in-Water Emulsion Stability: Experimental Design, Multiple Light Scattering, and Acoustic Attenuation Spectroscopy

To find an optimal formulation of oil-in-water (O/W) emulsions (o = 0.05), the effect of emulsifier nature and concentration, agitation speed, emulsifying time, storage temperature and their mutual interactions on the properties and behavior of these dispersions is evaluated by means of an experimental design (Nemrodw software). Long-term emulsion stability is monitored by multiple light scattering (Turbiscan ags) and acoustic attenuation spectroscopy (Ultrasizer). After matching surfactant HLB and oil required HLB, a model giving the Sauter diameter as a function of emulsifier concentration, agitation speed and emulsification time is proposed. The highest stability of C12E4-stabilized O/W emulsions is observed with 1% emulsifier

Physical characteristics of Acidic Mining Lake 111

Measurements of physical properties have been conducted in Mining Lake 111 (ML111), located in Lusatia, Germany over the time period 1996- 2002. In the deepest area of the ML111, a monimolimnion was observed, that persisted for the years 1996-1999. It disappeared in 2000 and again formed in 2001. The definition of the main physical properties, such as the temperature compensation for electrical conductivity, in acidic mining lakes required a lake specific approach. The relation between conductivity, temperature and density was determined for the acidic ML111. The variation in dissolved substances affected these relationships such that conductivity varied with temperature even in different layers of the water column and the limitations for a lake wide correlation was evident. Variation in the conductivity of the epilimnion could be verified, and agreed with the estimates of evaporation from the lake surface during summer stratification. Calculations, following the gradient flux method, indicated vertical transport coefficients between 10-7 and 10-6m2/s throughout the hypolimnion. The heat budget indicated that heat was transferred into the lake bed or the ground during spring

Analytical techniques and instrumentation: A compilation

Technical information is presented covering the areas of: (1) analytical instrumentation useful in the analysis of physical phenomena; (2) analytical techniques used to determine the performance of materials; and (3) systems and component analyses for design and quality control

Transport properties of spacetime-filling branes

A model consisting of (d+1)-dimensional gravity coupled to spacetime filling charged branes is used to study the effects of backreaction. The charged black holes arising from this simple model reflect the non-linearity of the gauge field and are thermodynamically stable. By analysing fluctuations of the system we corroborate that at low values of the temperature (or large chemical potential) backreaction effects from the branes are dominant. We also provide a generalisation of the Iqbal and Liu strategy to calculate the DC conductivity, in which a mass term for the gauge field fluctuation is included. This mass term gives the value of the residue of the pole at zero frequency in the imaginary part of the AC conductivity, as well as the running of the DC conductivity with the bulk radius.Comment: 27 pages + appendix, 11 figures. v2: analysis of fluctuations improve

Comparison of theories for acoustic wave propagation in gassy marine sediments

More than three decades ago, Anderson and Hampton [1, 2] (A&H) presented theories for wave propagation in gassy water, saturated sediments and gassy sediments in their two part review, which has been cited by many researchers in the geoacoustics and underwater acoustics areas. They gave an empirical formulation based on the theory of Spitzer [3] for the wave propagation in gassy water by adapting that for a viscoelastic, lossy medium. Following Leighton [4], this paper presents a theory based on non-stationary nonlinear dynamics of spherical gas bubbles and extends that 2007 paper to include liquid compressibility and thermal damping effects. The paper then shows how that nonlinear formulation can be reduced to the linear limit, and derives the expressions for the damping coefficients, the scattering cross section, the speed of sound and the attenuation, and compares these with the A&H theory. The current formulation has certain advantages over A&H theory such as implementing an energy conservation based nonlinear model for the gas pressure inside the bubble, having no sign ambiguity for the speed of sound formula (which is important when estimating the bubble void fraction) and correcting the ambiguity on the expression for scattering cross section, as identified in the recent work of Ainslie and Leighton [5]. Moreover, the theory presented here forms a basis for a nonlinear, time-dependent acoustic estimation model for gas bubble distributions in viscoelastic mediums since it avoids the commonly encountered assumptions on the bubble dynamics such as linearity, steady-state behaviour and monochromaticity

Extremely Low Loss Phonon-Trapping Cryogenic Acoustic Cavities for Future Physical Experiments

Low loss Bulk Acoustic Wave devices are considered from the point of view of the solid state approach as phonon-confining cavities. We demonstrate effective design of such acoustic cavities with phonon-trapping techniques exhibiting extremely high quality factors for trapped longitudinally-polarized phonons of various wavelengths. Quality factors of observed modes exceed 1 billion, with a maximum $Q$-factor of 8 billion and $Q\times f$ product of $1.6\cdot10^{18}$ at liquid helium temperatures. Such high sensitivities allow analysis of intrinsic material losses in resonant phonon systems. Various mechanisms of phonon losses are discussed and estimated