An experimental investigation on the breakup of surfactant-laden non-Newtonian jets

The combined effect of polymers and soluble surfactants on the dynamics of jet breakup, and especially on satellite drop formation, was experimentally investigated. Xanthan gum and Carbopol^® 934 NF were dissolved in water with Sodium Dodecyl Sulfate as the surfactant. Controlled disturbances were imposed at the laminar jet interface using a piezoelectric vibrating nozzle with breakup dynamics recorded using a high-speed camera. Drop and ligament diameters were measured from the digital images. The focus of the work was investigating how bulk and interfacial properties of the prepared fluids influenced ligament and drop evolution. It was found that if the proper concentration of surfactant (close to the critical micelle concentration, CMC) was selected, and if the flow time scales were large enough, Marangoni interfacial stresses may lead to an increase in satellite drop size as previously reported for breakup simulations of shear-thinning jets covered with insoluble surfactant. It was also experimentally confirmed that the introduction of surfactant contributes to a delay in jet breakup.     

Impulse viscoelastic characterization of wheat flour dough during fermentation

A new technique, named impulse viscoelasticity, was introduced and applied to investigate the rheological properties of dough. Specifically, the effects of mixing and fermentation times on the extensional properties of dough were characterized under small extensional strains of short duration. From the stress and strain responses measured, the tensile storage and loss moduli of dough were obtained as a function of mixing and fermentation times. There were significant changes in the tensile moduli of the dough samples over mixing times and in general high extensional properties were measured for the optimally-mixed dough. Fermentation caused the reduction of both tensile storage/loss moduli with a greater decrease in the storage moduli, clearly showing the loss of elasticity of the fermenting dough. The results showed that the short duration of the applied strain allows the impulse viscoelastic technique to be appropriately used in characterizing the rheology of foods which can vary during processing.     

Biosensors for monitoring the isothermal breakdown kinetics of peanut oil heated at 180 °C. Comparison with results obtained for extra virgin olive oil

The present research was devoted to studying the kinetics of the artificial rancidification of peanut oil (PO) when a sample of this oil was isothermally heated at 180 °C in an air stream. The formation of radical species due to heating was evaluated using a radical index whose value was determined using a biosensor method based on a superoxide dismutase (SOD), while the increasing toxicity was monitored using a suitable toxicity measuring probe based on the Clark electrode and immobilized yeast cells.     

Sensitivity to phase equilibrium data in the simulation of a hydrogen purifying column

The impact of phase equilibrium data on the simulation of a hydrogen purifying column has been evaluated. The analysis was performed in two stages. First, the most sensitive binary system was obtained. Then, it was verified if further experimental data were necessary for a reasonable simulation. The calculations were carried out using both rigorous and short-cut methods.     

Comparison of methods for characterization of complex mixtures

Comparative calculations of several methods of characterization for three multicomponent mixtures that include paraffin, naphthene, and aromatic fractions are shown. Each method requires different experimental information about the mixtures but all use the numerical Gauss-Legendre quadrature. The results show that characterization making direct use of the TPB distillation curve is the most suitable approach for characterizing complex multicomponent mixtures.     

Mercury removal from petrochemical wastes

The precipitation of mercury as mercury-starch-xanthate is studied. The process is studied in terms of optimum mercury-xanthate molar ratio, of influence of flocculation sedimentation times and of interferences (aluminum, iron, silica, chloride, organic substances and suspended solids).The studied reaction is advantageously applied to mercury removal from petrochemical wastes. The optimized process is applied both to a simulated and to a real wastewater, coming from a petrochemical industry (ANIC-Ravenna, Italy).     

Effective bandwidth optimization for noncoherent full-response CPMsystems

The optimization of the baseband pulse shape for full response CPM signals, when a noncoherent lowest complexity receiver is used, is carried out. The effective bandwidth is chosen as the objective of the optimization. In order to obtain the minimum error probability for high signal-to-noise ratio, orthogonal signaling is taken into consideration. A closed form for the optimum pulse shape, the value of the optimum modulation index and of the optimum effective bandwidth is determined. The power spectral density and the fractional out-of-band power have been compared with some phase functions considered in the literature     

The effect of tin on dezincification of archaeological copper alloys

Archaeological objects are a unique source of information for long-term corrosion studies. The present work concerns a hoard of Roman imperial coins, contained in a vase, excavated in the neighbourhoods of Rome. Aim of the research is to explain different conservation conditions by correlating visually perceivable parameters, such as corrosion morphology and extent with compositional information obtained by non-destructive investigations. The best preserved coins were found to have high zinc, low lead and small amounts of tin consistently with what occurs in modern brasses; it was observed that the latter prevents selective corrosion of zinc, otherwise causing heavy surface deterioration.     

Quantitative Determination of Acetaminophen in Pharmaceutical Formulations Using Differential Scanning Calorimetry. Comparison with Spectrophotometric Method

In this paper our previous researches dealing with compatibility, thermoanalytical characterization, the kinetics of thermal degradation of acetaminophen, either pure or contained in some commercial pharmaceutical formulations, have found applications outlets. In a previous investigation the possible interactions between acetaminophen and four excipients contained in the commercial pharmaceutical formulations were tested. As a continuation of this research in the present study an analytical method based on differential scanning calorimetry (DSC) was applied to determine the acetaminophen content of four commercial pharmaceutical formulations. For a fifth drug it was shown that the method is not applicable owing to observed incompatibility with one of the excipients. Finally, the analytical results obtained were compared with those derived from two UV spectrophotometric methods (one, i.e., “direct method,” recommended by the Pharmacopeia and the other based on the first-order derivative UV spectra).