Mapping the Polar Lipidome of Macroalgae using LC-MS-Based Approaches for Add-Value Applications

Marine macroalgae are emerging as sustainable and healthy food, and a source of lipids with nutritional and bioactive properties. Nonetheless, the lipidome of macroalgae is little explored compared to other photosynthetic organisms. Most of the literature is devoted to the analysis of fatty acid (FA) from macroalgae, because of they are a source of long-chain omega-3 and omega-6 polyunsaturated FA, which can be used as an alternative to fish oil. However, FA occurs mostly esterified in other lipids, such as polar lipids, that still overlooked. The data published on the study of polar lipids (phospholipids, glycolipids, betaine lipids) pinpoint their remarkable characteristics and bioactive properties which mainly remain unexplored. The lipidome of macroalgae seems to be species-specific, while some lipid classes appear to be characteristic of phyla. Lipidome plasticity of macroalgae is verified to change under abiotic and biotic factors which may modulate the functionality and add-value of the biomass. This biochemical plasticity represents an advantage to obtain ingredients for target applications and niche of markets. This review provides an overview on macroalgae lipidome characterization, addressing analysis workflow based on liquid chromatography coupled to mass spectrometry, and discussing the bioactive properties and biotechnological applications of macroalga lipids. Practical Applications: The current state of the art on marine macroalgae lipidomics is reviewed, including the lipid characterization using modern liquid chromatography-mass spectrometry, the distribution of polar lipids by macroalgae species and phylum, their bioactive properties, and potential biotechnological applications. In a time of increasing awareness of sustainably produced marine resources, the lipids from macroalgae are still underexplored. This review provides information for smart valorization of macroalgae as source of add-value lipids contributing to the development of blue bioeconomy.     

Controlling properties of ceramic formulations for porcelain robocasting

Porcelain pastes (PlotPastes) were formulated to be used on an additive manufacturing (AM) process (material extrusion) process, primarily robocasting (R3D) technique. The material morphological and thermal characteristics were evaluated by scanning electron microscopy (SEM), differential thermal analysis (DTA) and thermogravimetric analysis (TGA). The rheology and the electrical potential of the ceramic particles were also studied to select and adequate the porcelain paste properties to the R3D AM technique. It was found that shifting the pH values to acidic, the surface charge of the particles changes and increases the pastes viscosity due to agglomeration effects. This behaviour was exploited to optimize the paste rheological behaviour which resulted in the optimum pH at 1.94 (PlotPaste 5). This paste was used in the study of R3D operating parameters. It was found that small variations in pressure and speed affects the dimensional accuracy of the printed models. The results showed the disruptive potential of porcelain R3D in the production of customized ceramic products.     

FLASH sintering of porcelain stoneware: Effect of composition modifications

In this work, we have exploited FLASH sintering as an alternative sintering process in the production of porcelain stoneware. FLASH sintering of porcelain stoneware occurred at temperatures ∼ 1020 °C, for 500 V cm^-1, 2 mA mm^-2 in 30 s. These conditions are significantly less severe than those typically applied in its conventional sintering, 1150–1250 °C for 1 h. Despite the reduction of time and sintering temperature, FLASH sintered samples exhibit heterogeneous microstructure and elemental distribution, with localized glassy phase formed on the positive pole. By decreasing the feldspar content, less localized glassy phase and more uniform microstructures were obtained, being of relevance the highest density and microstructure uniformity attained in the composition without feldspar. These results extend the FLASH sintering applicability and illustrate its importance for the development of alternative sintering technologies in traditional ceramic industry, that in addition may benefit from the reduction of feldspar in the porcelain stoneware production.     

Ultrafast high-temperature sintering of gadolinia-doped ceria

Ultrafast high-temperature sintering (UHS) is a rapidly growing research area of material science and engineering. Herein we present UHS of gadolinia-doped ceria (GDC) powders in single and multi-step approaches. The sintered ceramics were characterized from a physical and electrochemical point of view. When the power is applied gradually during the multistep UHS process crack-free GDC ceramics can be obtained with 95 % bulk density using commercial powder. Oxalate converted GDC powder gave 86 % bulk density with the same multistep sintering process. Additionally, it is shown that multistep UHS is also suitable for multilayer co-sintering necessary for solid oxide fuel cells (SOFC), as demonstrated by the production of dense GDC electrolyte in tight contact with porous electrodes.     

Ceramics/metals joining under the influence of electric field: A review

Joining ceramics with ceramics and/or metals is of immense importance to widen the application horizons of ceramics and metals. Solid-state joining is restrained by the high joining temperature and long joining time, both of which can be reduced by liquid-state joining. However, the operating temperature of different ceramic-based components is low because of the low melting temperature of the filler. In order to rapidly join ceramic-based materials at low temperatures, various joining techniques utilizing the effect of an electric field (E-field) have been developed. These methods are generally classified into four categories, i.e., spark plasma sintering joining, low E-field assisted joining, anodic bonding and flash joining, according to the value of applied E-field and the types of materials to be joined, resulting in different joining mechanisms and joint performances. These methods are reviewed from the viewpoint of material types that can be joined and mechanisms.     

Functional properties of La1–xBaxFeO3–δ as symmetrical electrodes for protonic ceramic electrochemical cells

To create highly efficient solid oxide fuel cells with a symmetrical configuration, it is necessary to develop suitable functional materials whose properties under oxidizing and reducing conditions will satisfy simultaneously the requirements for both fuel and oxygen electrodes. In the present work, the La_1–xBa_xFeO_3–δ (x = 0.4, 0.5, 0.6) materials were obtained and investigated as symmetrical electrodes for proton-conducting electrochemical cells based on a BaCe_0.7Zr_0.1Y_0.1Yb_0.1O_3–δ electrolyte. For the first time, the La_1–xBa_xFeO_3–δ materials were comprehensively investigated in terms of electrical conductivity, thermomechanical and electrochemical properties in both oxidizing and reducing atmospheres. It is found experimentally that La_0.6Ba_0.4FeO_3–δ demonstrates the highest electrical conductivity, lowest polarization resistances and acceptable thermal expansion behavior, which allows these materials to be used as oxygen electrodes. However, for the successful utilization of the La_1–xBa_xFeO_3–δ as the symmetrical electrodes, their transport properties under reducing atmospheres need to be improved.     

Functional properties of transparent ZnO thin films synthetized by using spray pyrolysis for environmental and biomedical applications

Spray pyrolysis is a promising method for producing thin, transparent films on glass substrates. ZnO thin films synthesized by this method exhibit high crystallinity, adhesion and chemical resistance. They also possess the ability to degrade water pollutants and exhibit antibacterial properties under UV light. The crystalline structure of these films has been studied using grazing X-ray diffraction (GIXRD), atomic force microscopy (AFM) and scanning electron microscopy (SEM), while transmission electron microscopy (TEM) has been used to investigate their composition and purity. Other techniques such as X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and ultraviolet–visible spectroscopy were also employed. ICP-OES was used to evaluate photocatalyst leaching. These transparent thin films have exceptional optical properties, with a transmittance of 95%. The photocatalytic degradation of 4-Nitrophenol (4-NP) by ZnO thin films showed a degradation rate of 94% in 270 min with a kinetic constant value of 3.1 × 10⁻³ mM/min. The films are also highly durable and reusable, exhibiting superior performance compared to other ZnO photocatalysts. The bactericidal activity of these transparent films was also evaluated, with a value of 60.6% being obtained using Escherichia coli after irradiating the films with UV light for 3 h.     

Synthesis,processing and characterization of a bioactive glass composition for bone regeneration

This paper reports on the experimental evaluation of a novel melt-quenched glass belonging to the CaO–MgO–SiO₂–P₂O₅–Na₂O–CaF₂ system as potential material for biomedical applications in bone regeneration. The glass composition has been designed in the primary crystallisation field of pseudo-wollastonite in CaO–MgO–SiO₂ ternary phase diagram. The rise of pH upon immersion in SBF solution was slower for the novel glass in comparison to 45S5 Bioglass^®. Nevertheless, both glasses exhibited similar behaviour in early formation of crystalline apatite demonstrating their osteoinductive features. The in vivo investigations in rabbits demonstrated good compatibility between the glass and surrounding tissue along the whole implantation period with negligible adverse reactions. The clinical evaluation of glass has been conducted in accordance with the ethical guidelines and regulations.     

A comparative study between Cr(VI)-containing and Cr-free films for coil coating systems

In this work, the protection conferred by Cr(VI)-containing and Cr-free pre-treatments and primers used in hot dip galvanized steel (HDG) coated systems were studied. The EIS results showed a differentiated behaviour for the specimens with Cr(VI) compared to the chromium-free ones. The samples with Cr(VI), both in the pre-treatment and in the primer, presented a better corrosion performance when compared to the Cr-free ones.

Moreover, it can be said that the pre-treated and primed samples without Cr(VI) presented lower resistive properties and higher delamination fractions throughout the immersion time. The amount of Cr in the primer also influenced the coating resistance for shorter periods of immersion, but for long periods the passivating effect of Cr seems to be determinant.

When topcoat was applied, i.e. for a complete system, the Cr-free specimens performed better than the Cr(VI)-containing ones, perhaps due to a better adhesion of the topcoat to the primer in the former case. This leads to the conclusion that there is a risk in assessing the behaviour of a paint scheme on the basis of the individual behaviour of each layer.     

Generalized natural boundary conditions for fractional variational problems in terms of the Caputo derivative

This paper presents the necessary and sufficient optimality conditions for problems of the fractional calculus of variations with a Lagrangian depending on the free end-points. The fractional derivatives are defined in the sense of Caputo.