Optimization of Oil Oxidation by Response Surface Methodology and the Application of this Model to Evaluate Antioxidants

The oxidative stability of oils is a complex process influenced by several factors, making the evaluation of antioxidant effects of new compounds difficult. Thus, the objective of this study was to apply a factorial design to obtain the combination of factors that maximizes the formation of oil oxidation products, and use this model to evaluate the antioxidant activity of different compounds. Temperature, Fe²⁺ and ascorbyl palmitate were evaluated in two full-factorial designs (2³ and 3²). The validated optimized oxidation model was obtained by adding 1.47 mmol/L of Fe²⁺ and 1.54 mmol/L of ascorbyl palmitate to flaxseed oil stripped of tocopherol kept at 40 °C for 8 days. Antioxidant activities of six compounds were evaluated using this model. All antioxidant samples were statistically different (p < 0.001) at 200 ppm concentration, indicating the efficiency of the optimized model to evaluate the antioxidant action of natural and synthetic compounds.     

Epoxidizable Fatty Amide–Phenol Conjugates

This paper reports the synthesis of a series of novel compounds where carboxylic acids have been linked to a phenol through amidomethyl units. For instance, one, two, or three fatty acids have been selectively appended to the phenol in yields above 75%. The fatty acid used was oleic acid, which was subsequently epoxidized. Other functional groups, such as amino acids, can be incorporated in these compounds. Examples of monomers that are suitable for polymerization were also prepared: one acrylamide, one styrene derivative, and two types of AB₂ diamino acids, all of which contain oleic units that are sites for epoxidation and crosslinking. Fatty acid aryl ethers were prepared using hydroxy fatty acids. These molecules are intended to serve as augmented analogues of epoxidized vegetable oil. Their amide groups should lead to intermolecular aggregation through hydrogen bonding, and the option to covalently include other functional groups may permit tuning of the macroscopic materials properties of films, coatings, or solids constructed from them.     

Influence of Soft Cocoa Butter Equivalents on Color and Other Physical Attributes of Chocolate

The physical characteristics and color of chocolate depend on the physical properties and crystallization behavior of the fat phase. In this study, the fat phase of chocolate samples contains cocoa butter from Ghana and soft cocoa butter equivalent (CBE). The laboratory-made chocolate samples were tempered at three different precrystallization temperatures (25, 27 and 29 °C), using three different concentrations of CBE (3, 5 and 7%), calculated as percentage of the chocolate. Physical characteristics of chocolate, namely thermoreographic parameters and solid fat content (SFC), were measured. The color of the chocolate was determined instrumentally, before and after thermo-cycle testing at 32/20 °C. It was found that CBE changed the melting properties of chocolate produced with cocoa butter from Ghana, which is of moderate hardness. It was determined that the optimum precrystallization temperature for chocolate mass with addition of CBE in the given conditions of measurement was 27 °C, the temperature that resulted in the best fat bloom resistance.     

Valorization of Beef Tallow by Lipase-Catalyzed Interesterification with High Oleic Sunflower Oil

Although beef tallow (BT) has been considered a hard low-trans fat convenient to be used in several bakery applications, it has some undesirable characteristics like fatty acid composition, crystallization behavior, graininess formation and poor plastic range. This work studied the modification of BT by blending at different percentages with high oleic sunflower oil (HOSFO) followed by the enzyme-catalyzed interesterification of the blends. The reduction in the solid fat content achieved by the simple blending was enhanced by the interesterification process, as a result of the increase in the concentration of the diunsaturated monosaturated type triacylglycerols. Interesterification strongly impacted too on the crystallization behavior of the blends, since products showed more homogeneous and regular crystals than the starting mixture. Results show that lipase catalyzed interesterification of BT with HOSFO offers a useful tool for the design of fats with adjustable physicochemical properties, improved with respect to that of the starting fats.     

Non-plasma ignition of lead styphnate by a semiconductor bridge and its comparison with plasma ignition

The process of non-plasma ignition of lead styphnate by a silicon-based semiconductor bridge is studied. Discharge characteristics with plasma and non-plasma ignition are analyzed. It is demonstrated that non-plasma ignition is characterized by a low energy and can be applied in cases with fine-grain energy materials.     

Studies on jet formation and penetration for a double-layer shaped charge

An analysis for liner collapsing and jet/slug formation of a double-layer shaped charge (DLSC) is presented. Variations of the collapse angle, collapse velocity, and jet velocity of the DLSC are discussed. Numerical simulations based on the Lee-Tarver model are performed to have an insight into the jet formation. Ballistic tests are conducted using a conical (60°) metal liner 56 mm in diameter to have a contrast with an ordinary shaped charge jet. It is shown that the collapse angle and velocity are both increased by the convergent detonation wave in the DLSC. The jet velocity, kinetic energy, and ballistic capability are significantly increased by using the DLSC, and the DLSC is an efficient way to improve shaped charge performance.     

Tests of experimental breathing filters

Comprehensive tests of experimental bacterial and viral heat and moisture exchanging breathing filters were performed using filter cartridges of domestic non-fabric materials from various production methods based on chemical fibers on a stand that enabled the specific loss of moisture from the humidifying loop of the breathing filters to be determined according to the requirements of ISO 9360–1:2000 (E). Results from tests of the specific moisture loss from the humidifying loop for the experimental breathing filters and analogous filters from foreign companies were compared.     

Some properties of modified polyacrylonitrile fibres

Fibre-forming copolymers of acrylonitrile and a monomeric quaternary ammonium salt, β-methacryloylhydroxyethyl-(N-dimethyl,methylene)ammonium iodide, were obtained by wet spinning and their physicomechanical and structural properties were investigated. It was found that the modified fibres have a set of valuable properties in comparison to the industrial fibre Nitron.     

Determination of conditions for depositing crystalline calcium chloride hydrate on the heat and moisture exchanging layer of breathing filters

The moisture content and hygroscopicity of viscose fiber and filter material of the heat-exchanging layer of a breathing filter were determined as a function of the mass fraction of calcium chloride, drying temperature, and the calcium chloride soaking method in order to define these parameters.     

Deposition of titanium on SiC fibres from chloride melts

The present study examined the feasibility of producing titanium matrix composites based on a molten salt fibre coating process. It is demonstrated that sufficiently thick and coherent titanium coatings can be deposited on SiC fibres in LiCl–KCl–TiCl₂ at 700 K. One important aspect of the study was the behaviour of the substrate during electrolysis. Therefore, additional features related to carbon-coated SiC fibres and carbonaceous substrates in general are outlined. The morphologies and microstructures of electrolytically coated SiC fibres were investigated by scanning electron microscopy and compared to fibres coated by a physical vapour deposition technique. The cause and relevance of the growth failures that were observed in this study are also discussed.