The marine environment is highly diverse, each living creature fighting to establish and proliferate. Among marine organisms, cyanobacteria are astounding secondary metabolite producers representing a wonderful source of biologically active molecules aimed to communicate, defend from predators, or compete. Studies on these molecules’ origins and activities have been systematic, although much is still to be discovered. Their broad chemical diversity results from integrating peptide and polyketide synthetases and synthases, along with cascades of biosynthetic transformations resulting in new chemical structures. Cyanobacteria are glycolipid, macrolide, peptide, and polyketide producers, and to date, hundreds of these molecules have been isolated and tested. Many of these compounds have demonstrated important bioactivities such as cytotoxicity, antineoplastic, and antiproliferative activity with potential pharmacological uses. Some are currently under clinical investigation. Additionally, conventional chemotherapeutic treatments include drugs with a well-known range of side effects, making anticancer drug research from new sources, such as marine cyanobacteria, necessary. This review is focused on the anticancer bioactivities of metabolites produced by marine cyanobacteria, emphasizing the identification of each variant of the metabolite family, their chemical structures, and the mechanisms of action underlying their biological and pharmacological activities.

The objective of this work was to study the volumetric and transport properties of mixtures made up of biodiesel and diesel, in order to meet the desirable properties of these formulations for their practical applications. The volumetric and transport properties were analyzed for two pseudobinary mixtures constituted of diesel + beef tallow butyl ester biodiesel and diesel + waste cooking oil methyl ester biodiesel in the whole range of composition at 0.078 MPa. The study of butyl ester biodiesel was motivated by the scarcity of these properties’ data for butyl esters and the improvement of some of its physicochemical properties. The biofuels were previously transesterified from waste materials and alcohols, beef tallow with 1-butanol and cooking oil with methanol. Density measurements were performed in a vibrating tube densimeter from 293.15 to 363.15 K; the kinematic viscosity experiments were carried out in Cannon-Fenske viscometers from 293.15 to 343.15 K. The derived thermophysical properties evaluated were the excess molar volume, the partial molar volume, the thermal expansion coefficient, the dynamic viscosity and the viscosity deviation. The excess molar volumes presented positive and negative values. The Redlich–Kister correlation and the theoretical ERAS (Extended Real Association Solution) model were applied for modelling the excess molar volume. Both approaches resulted in good agreement. For viscosity, the McAllister model was implemented and yielded lower deviations for the butyl ester biodiesel.

Methane hydrates were studied in systems containing aqueous dissolved surfactants in oil emulsions with a volume ratio of 40/60. Two commercial surfactants, named synperonic PE/F127 and cetyltrimethylammonium bromide, were evaluated at 0, 350, 700 and 1500 ppm. Experiments were made by applying the cooling–heating path in an isochoric high-pressure cell at different initial pressures of 5.5, 8.0, 10.0 and 12.0 MPa. The obtained parameters were induction time, temperature onset, pressure drop, and dissociation conditions. The results revealed that the dissociation curve for methane in water-in-oil emulsions was not modified by the surfactants. The crystallization (onset) temperature was higher using synperonic PE/F127 in comparison with zero composition, while the opposite occurred with cetyltrimethylammonium bromide. Both surfactants induced a delaying effect on the induction time and a lesser pressure drop.

This study presents the experimental characterization of the volumetric and transport properties of pseudo-binary mixtures of commercial diesel and residual chicken fat methyl ester biodiesel over the temperature range of 293.15–353.15 K at 0.078 MPa. Density measurements were performed using a U-shaped vibrating-tube densimeter; kinematic viscosities were obtained using Cannon–Fenske capillary viscometers. The results show that density decreased with increasing temperature and diesel content. The excess molar volume (V^E) was negative for all mixtures; the strongest volumetric contraction took place at around x₁ ≈ 0.4–0.6. The Redlich–Kister equation and the Prigogine–Flory–Patterson (PFP) model were applied to represent excess molar volumes, with an absolute average deviation (AAD) lower than 14.92%. The thermal expansion coefficient (${\alpha }_P$) and its excess property (${\alpha }_P^E$) further confirmed the existence of non-ideal mixing driven by polar–apolar interactions. The kinematic viscosity ($\nu$) was confirmed to be temperature-dependent and increased with the amount of FAMEs; this effect can be associated with the greater polarity and structural rigidity of esters. The McAllister model also adequately reproduced the dynamic viscosity ($\eta$) with an AAD < 4.2%. Furthermore, an increase in the activation enthalpy (${\Delta H}^{\ne }$) was observed at higher FAME fractions, indicating a high energy demand is required to overcome the internal energy barrier for the initial displacement of the molecules.