Competitive displacement of oil body surface proteins by Tween 80 – Effect on physical stability

A concentrated oil body cream, prepared from maize germ by aqueous extraction, was dispersed in water to obtain a natural 5% o/w emulsion. To improve the emulsion physical stability, the hydrophilic surfactant Tween 80 (polyoxyethylene sorbitan monooleate) was incorporated at levels ranging from 0.25 to 2%, and the increase of the oil body mean diameter and the volume of serum separated from the emulsion system, was followed with storage time. In addition, the amount and composition of oil body surface proteins competitively displaced by the surfactant was studied. The improvement in oil body stability against coalescence and creaming, resulting from Tween addition, is discussed in terms of the development at the oil body surface of an adsorbed film of a mixed nature, made up of surfactant- and phospholipid-rich domains, with the non-displaced surfactant protein molecules, mainly oleosins, remaining embedded in the latter.     

La1−xSrxMyFe1−yO3−δ perovskites as oxygen-carrier materials for chemical-looping reforming

The use of perovskites with the general formula La_1−xSr_xM_yFe_1−yO₃ (M = Ni, Co, Cr, Cu) as oxygen carriers for syngas generation from methane by Chemical Looping Reforming is investigated in the present work. The experimental study concerns the oxidation of a fuel, using the oxygen from a solid oxygen carrier, instead of oxygen from air. Subsequent oxidation of the reduced solid is performed either with gaseous oxygen or with water. In the latter case additional hydrogen is produced, which is very pure and therefore appropriate to be used in fuel cell applications. The performance of the candidate materials is ranked by taking into account the hydrogen and carbon monoxide yields during the fuel oxidation step as well as the amount of oxygen per mole solid (δ) that can be delivered reversibly to the fuel. The effect of the materials composition and of NiO addition is examined. The best performance was obtained with the La_0.7Sr_0.3Cr_0.1Fe_0.9O₃ sample mixed with 5% NiO. The H₂ yield was up to 90%.     

Setting process of lime-based conservation mortars with barium hydroxide

This paper presents the effect of barium hydroxide on the setting mechanism of lime-based conservation mortars, when used as an additive material. The study focuses on the monitoring of the setting process and the identification of the mineral phases formed, which are essential for furthering the study of the durability of barium mixtures against chemical degradation. X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and thermal analysis (DTA-TG) were used to monitor the setting processes of these mixtures and identify new phases formed. The results suggest that barium hydroxide is evenly distributed within the lime and produces a homogeneous binding material, consisting of calcite (CaCO₃), witherite (BaCO₃) and barium-calcium carbonate [BaCa(CO₃)₂]. Finally, it was found that barium carbonate can be directly bonded to calcitic aggregates and therefore increases its chemical compatibility with the binding material.     

Influence of preparation methods on physicochemical and gelation properties of chickpea protein isolates

Two protein isolates were prepared from defatted chickpea seed flour by applying alkaline extraction followed by isoelectric precipitation or ultrafiltration (TpI and TUF, respectively), while another one (TF) was obtained by a combination of protein extraction at a mildly acidic environment and ultrafiltration processes. The isolates differed in composition, with the TpI and TF containing mainly the chickpea globulins and the albumins, respectively, whereas the TUF isolate consisted of both types of proteins with the globulin fraction dominating over the albumins. The differences in protein composition between the isolates as well as the impact of extraction conditions were reflected in their protein solubility, surface hydrophobicity, sulfhydryl group content, thermal properties and the onset of gelation during heating. On the other hand, the protein isolate gelling behavior depended mainly on the method applied for their preparation rather than the protein composition, with the isolates obtained by ultrafiltration exhibiting lower gelling concentrations and gel networks of higher elasticity at protein contents below 12% (w/v).     

Selection of TBM and geotechnical assessment of a microtunnel in a difficult geological environment: a case of a natural gas pipeline beneath an active landslide (Albania)

Bulletin of Engineering Geology and the Environment - This present paper presents an adopted methodology for Micro Tunnel Boring Machine (TBM) selection, based on the results of a...     

The generalized Kuhn model of linear viscoelasticity

We propose a generalization of the Kuhn model of linear viscoelasticity. This generalization, which has four material parameters, is able to provide a near frequency independent response over a wide range of frequencies. It is useful for highly dissipative materials such as asphalt concrete. It is derived by generalizing Lubliner and Panoskaltsis’s modified Kuhn model, but we also show that it is closely related to fractional derivative models. We show that the model admits a rheological approximation, that is, an approximation by classical springs and dashpots. The model and rheological representation are compared to experimental data.