“Arbequina” Olive Oil Composition Is Affected by the Application of Regulated Deficit Irrigation during Pit Hardening Stage

Three new regulated deficit irrigation (RDI) treatments were applied to “Arbequina” olive orchards during pit hardening. Oil quality was determined by measuring analytical parameters for olive oil grading, antioxidant activity, total phenol content, fatty acid profile, volatile compounds profile, and sensory analysis. Oils from RDI were classified as “extra virgin olive oil” and their quality was improved due to their higher antioxidant potential (ABTS⁺ [increased ~75%] and DPPH^˙ [increased ~25%] assays) and phenols (increased ~53%) than control. Concentration of total volatile compounds decreased (~27%) but RDI olive oils showed a more balanced profile (alcohols, aldehydes, and esters). Monounsaturated fatty acid content increased (~5%) and atherogenic and thrombogenic indexes decreased (~8.5%) in RDI olive oil. Regarding sensory analysis, RDI provided more balanced oils with higher fruit aroma than control. Other benefits of RDI olive oil, when compared with oil from full irrigated orchards are reduced use of water and improved functional and sensory quality.     

Margarine-Like Emulsions Prepared with Coconut and Palm Oils: Analysis of Microstructure and Freeze–Thaw Stability by Differential Scanning Calorimetry

The objective was to study the microstructure and freeze–thaw stability of margarine-like emulsions formulated with vegetable fats using differential scanning calorimetry. Emulsions were prepared with 20% w/w dispersed aqueous phase and a continuous lipid phase composed by coconut oil (CO) and/or palm oil (PO) plus polyglycerol polyricinoleate (PGPR) as emulsifier. Mean temperature (T_M) and crystallization enthalpy (ΔH_c) were obtained from the exothermic peaks corresponding to freezing of aqueous phase. Successive cooling–heating–cooling cycles were applied to analyze changes in the exothermic peak. The emulsion prepared with CO (without PO) and 1% w/w PGPR in lipid phase showed higher water droplets size (T_M = −44.8 ± 0.1 °C) and lower quantity of stabilized aqueous phase (ΔH_c = 28.9 ± 1.2 J g⁻¹) prior to application of temperature cycles, while coalescence and (presumably) water transfer processes occurred during the treatment. The use of 2% w/w PGPR was sufficient to accomplish full stabilization of aqueous phase (T_M = −45.9 ± 0.1 °C; ΔH_c = 42.6 ± 0.3 J g⁻¹) before and after the freeze–thaw treatment. The total or partial (50%) substitution of CO by PO in emulsions with 1% w/w PGPR also improved the stability of the system, exhibiting slight microstructural changes. This enhanced stability would be linked to reduced water droplets size because of more rapid crystallization of lipid phase and immobilization of aqueous phase after emulsion preparation. In conclusion, it is possible to obtain margarine-like emulsions prepared with CO and/or PO using relatively low emulsifier concentration and maintaining a desired microstructure after freeze-thawing if the percentage ratio of both fats is controlled.     

Tuning the pH-responsiveness capability of poly(acrylic acid-co-itaconic acid)/NaOH hydrogel: Design,swelling, and rust removal evaluation

The swelling behavior of poly(acrylic acid-co-itaconic acid)/NaOH hydrogel as well as its ability for iron and copper rust removal was studied and established for the first time. Through an experimental design, the influence of the synthesis parameters on hydrogel response was determined. It was found that pH-responsiveness dependence of hydrogel determines its application. In alkaline media, the hydrogel acted as superabsorbent, while in acidic, the most outstanding property was its pickling capability that allowed to clean carbon steel and copper metallic surfaces. Infrared, thermogravimetry, and scanning electron microscopy were performed to determine copolymer formation, thermal properties, and morphology. Metallic crystallographic phases formed during the corrosion processes were determined by X-ray diffractometer. Hydrogel adhesiveness followed by diffusion and dissolution of metal oxides species was identified as the main steps in the rust removal mechanism. This method offers a new, environmentally friendly perspective to eliminate corrosion from metallic surfaces compared with traditional strategies. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48403.     

Black Sand-Based Photocatalyst for Hydrogen Production from EDTA Solutions Under UV–Vis Irradiation

Topics in Catalysis - Black sand from coastal deposits composed by a mixture containing oxides (Fe2O3, TiO2, SiO2, ZrO2, MnO, Al2O3, etc.) and metals (V, Cr, Ni, Sr, Ce, etc.). Both this mineral,...     

Self-foaming diphenolic acid benzoxazine

This work concerns the investigation of porous polybenzoxazines based on the non-toxic renewable diphenolic acid. The approach described relies on the in situ generation of foaming agent (CO₂) during the thermal curing. For this purpose, the previously synthesized benzoxazine monomer from diphenolic acid was thermally polymerized at different temperatures. As the beginning of decarboxylation is about 200 °C, we selected five foaming temperatures (T_f) ranging from 190 to 230 °C. The influence of the foaming temperature on the cellular structure and its dependency on final properties is discussed.     

Anisotropic thermal conductivity of silicon nitride ceramics containing carbon nanostructures

Silicon nitride (Si₃N₄) composites containing carbon nanotubes (CNTs) or graphene nanoplateles (GNPs) are of great relevance in the electronic and aerospace industries where the search for new materials with enhanced and anisotropic thermal conductivity to work in harsh environments is a strategic guideline. Here we study thermal conduction in Si₃N₄ composites with different amounts of carbon nanostructures. The effects of the nanostructure orientation respect the heat flux, the testing temperature and the α/β Si₃N₄ phase ratio are analyzed. The addition of CNTs and GNPs leads to an anisotropic thermal response, decreasing the through-thickness thermal conductivity of the Si₃N₄ composites and raising the in-plane thermal conductivity, especially for GNPs that enhance it up to twice that of the monolithic Si₃N₄. This effect is related to the preferred orientation of the nanostructures that gives a less resistive network in the in-plane direction and the intrinsic anisotropy of their thermal conductivity.     

Nanoindentation,AFM and tribological properties of thin nc-WC/a-C Coatings

Instrumented indentation, AFM (atomic force microscopy) and tribological studies were performed on PE CVD (Plasma Enhanced Chemical Vapor Deposition) nanocomposite WC–C coatings to investigate the effects of surface roughness on the reliability of nanoindentation data and the possibilities of different AFM modes in nanomechanical testing, which can be used as a feedback to optimize deposition technology from the viewpoint of their mechanical properties. It was confirmed that surface roughness below 30 nm is necessary to keep the scatter of indentation modulus, E_IT, and hardness, H_IT, below 15%. PF QNM (Peak Force Quantitative NanoMechanical) mode was successfully applied for qualitative mapping of the elastic modulus of coatings with the stiffness above 300 GPa. LFM (lateral force microscopy) mode showed only weak contrast and quantitative measurements in both AFM modes require precise calibration. Coefficients of friction of the studied WC–C coatings were below 0.2 at RT, but increased to 0.7–0.8 at 450 °C due to the formation of a transfer film. Optimization of the deposition conditions based on nanoindentation resulted in the increase of E_IT from ～220 GPa to 350 GPa and H_IT from ～17 GPa to ～29 GPa.     

Interaction between laser beam and BaTiO3 powders in selective laser sintering treatments

The research work reported in this paper is an investigation of the behavior of barium titanate powders under selective laser irradiation. Our goal is to determine suitable conditions to sinter the powders and form dense layers usable in some electronic components. On that purpose, compacts of micro/nano BaTiO₃ powder mixes are used for a parametric investigation of the laser scans parameters (power, speed, etc.) with a Nd-YVO₄ laser (23 W). The microstructures obtained after laser treatments are evaluated by XRD, SEM and EDS and compared to a reference specimen manufactured in a conventional way. From this work it can be concluded that a high laser beam power is required to obtain a consolidation of the powder grains and the use of a high scan speed avoids the melting. The scanning speed also influences the final crystallographic state of BaTiO₃. Optimal parameters were founded in order to form a dense and homogeneous tetragonal BaTiO₃ surface.     

Screening of lactic acid bacteria for fermentation of minced wastes of Argentinean hake (Merluccius hubbsi)

Sixteen strains of lactic acid bacteria were evaluated for their capacity of acidification of Merluccius hubbsi fish wastes obtained from a processing factory. Only three lactobacilli (Lactobacillus buchneri B-1837, Lactobacillus arizonensis B-14768 and Lactobacillus plantarum B-4496) were able to reduce the pH value to 4.0 or below when using glucose or sucrose as carbon source. Either with only 25 g l^?1 of glucose or sucrose, L. arizonensis B-14768 reduced the pH to 3.8 ± 0.2 within 24 h of fermentation. The acid tolerance test (pH 3.0 at 37 °C) for the strains presented D_pH3-values of 192, 383 and 767 min for L. buchneri, L. plantarum and L. arizonensis, respectively. However, at a lower pH value (pH 2.0) only L. arizonensis was significantly recovered after 45 min of exposure (D_pH2 68 min). Considering together the acidification capacity, the tolerance to other stresses (heat and bile salts) and the lower optimum temperature for the process, L. arizonensis is described as a suitable strain for M. hubbsi silage; constituting a promissory alternative for fish fermentation at location with temperate or cold climes.     

Microencapsulation of cashew apple (Anacardium occidentale,L.) juice using a new chitosan–commercial bovine whey protein isolate system in spray drying

The aim of this work was to obtain a new stable food product from cashew apple juice encapsulated by spray-drying technique using chitosan–whey protein isolate systems. The materials were evaluated according to their physicochemical stability during storage at different conditions and characterized with respect to their particle size distribution and structure. Encapsulated commercial and natural juices showed homogenous and unimodal particle size distribution with diameters ranging from 0.2 to 5.0 μm and from 0.2 to 40.0 μm, respectively. Both juices demonstrated higher physicochemical stability for vitamin C and color measurements than their respective non-encapsulated juices. X-ray diffractograms evidenced that the powder juices after the 140th day of storage were still in amorphous state. These results indicate that the new product was effective in protecting sensitive compounds present in the food matrix and it was also able to remain stable throughout the study period.