Growth of large-sized graphene thin-films by liquid precursor-based chemical vapor deposition under atmospheric pressure

Large-sized thin-films composed of single- and few-layered graphene have been synthesized by chemical vapor deposition (CVD) on copper foils under atmospheric pressure using ethanol or pentane as the precursor. Confocal Raman measurements, transmission electron microscopy and scanning tunneling microscopy show that the majority part of the obtained films exhibit hexagonal graphene lattice. Optical microscopy and electrical measurements confirm the continuity of these films. It is also found that the CVD-grown graphene films with ethanol as the precursor exhibit lower defect density, higher electrical conductivity, and higher hall mobility than those grown with pentane as the precursor. This liquid-precursor-based atmospheric pressure CVD synthesis provides a new route for simple, inexpensive and safe growth of graphene thin-films.     

Influence of Vegetable Oils on Micellization of Lutein in a Simulated Digestion Model

Lutein and zeaxanthin are selectively accumulated in the macula of the retina, yet their bioavailability is influenced by various dietary factors. Insights regarding the effects of dietary lipids on lutein micellization that is available for absorption are limited. This study investigated the influence of vegetable oils on the relative efficiency of lutein micellization using in vitro digestion procedure. Lutein dispersed in either olive oil (OO), corn oil (CO), soybean oil (SBO), sunflower oil (SFO), groundnut oil (GNO), rice bran oil (RBO) or palm oil (PO) was subjected to simulated gastric and small intestinal digestion. Results showed that the efficiency of micellization of lutein dispersed in olive oil exceeds the other vegetable oils. The percent lutein micellization was in the order of OO > GNO > RBO > SFO > CO > SBO > PO. In comparison, the values for OO were higher than GNO (11%), RBO (18.3%), SFO (19%), CO (21.7%), SBO (30.5%) and PO (35.2%), respectively. These results suggest that OO rich in oleic acid may favor the incorporation of lutein into micelles at the intestinal level. To conclude, the type of vegetable oil in which carotenoids are dispersed is important to achieve an enhanced bioavailable lutein. The correlation between the micellizable lutein and fatty acid composition of vegetable oils are discussed.     

Determination of Acid Number of Biodiesel and Biodiesel Blends

Due to an increase in the commercial use of biodiesel and biodiesel blends, both ASTM D 6751 and EN 14214 include the acid number (AN) as an important quality parameter. It was found that determination of AN of biodiesel and biodiesel blends using the ASTM D 974 results in large values of repeatability (up to 73.41%) and larger percentage error (up to 42.88%). Therefore, ASTM D 974 has been modified using a lower concentration of base (0.02 M KOH instead of 0.1 M KOH) as well as reducing the amount of toxic titration solvent from 100 mL to only 10 mL. This makes the modified ASTM D 974 as a green analytical method which uses a reduced amount of toxic solvent. This modified method significantly reduced the maximum percentage error from 42.88 to 5.92%. The application of this modified ASTM D 974 for the determination of AN of biodiesel and biodiesel blends was studied. The accuracy of this modified ASTM D 974 for biodiesel (B100) was measured to be within 3.51% over the AN range of 0.313–0.525 mg KOH/g and maximum repeatability was decreased from 8.37 to 2.75% within this AN range which is far below the ASTM D 974 stated repeatability specifications. For B20, B10, B5, B2, and B1, the most accurate values were measured at AN values of 0.177, 0.067, 0.072, 0.126, and 0.096 mg KOH/g, respectively. Excellent linearity values of R ² for calculated and experimentally determined AN were obtained. The difference between the experimental and the calculated AN for all biodiesel and biodiesel blend samples was within ± 0.018 mg KOH/g. This extensive study has demonstrated that this modified ASTM D 974 is a reliable method for the determination of AN and could be used for establishing the specifications of AN for biodiesel and biodiesel blends ranging from B1 to B20 in quality standards.     

Detoxification of Rapeseed Meals by Steam Explosion

Steam explosion was evaluated as a detoxification method for rapeseed meals. A series of two factor experiments were performed with different steam pressures (1.0, 1.2, 1.4, 1.6, 1.8, 2.4, 3.2 and 4.0 MPa) and different treatment times (30, 60, 90, 120, 150 and 180 s). When the steam pressure was increased to 1.6 MPa or higher, 99% glucosinolates could be removed within 180 s. Their toxic breakdown products, including isothiocyanates, oxazolidinethiones and nitriles, were also reduced by 97, 93 and 59%, respectively. A model experiment confirmed that they were taken away by the steam. The effect of steam explosion on amino acids was also investigated. Lysine, arginine, aspartate, cysteine, methionine and tryptophan contents were reduced by 21, 24, 14, 13, 17 and 8%, respectively. Steam explosion is a fast and simple detoxification method, but it negatively affects amino acids.     

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.