Sugar feeding in triatomines: a new perspective for controlling the transmission of Chagas disease.

Introduction: Triatomines are vectors of Trypanosoma cruzi, the etiological agent of Chagas disease. Currently, there is no vaccine against this disease. Thus, control of the insect vector population is the main strategy available to reduce the number of cases. Triatomines are considered obligate hematophagous, but different alternative feeding behaviors were described, such as haemolymphagy or plant feeding. Methods: To determine the preference for sugar feeding in nymphs and adults of Rhodnius prolixus, the insects were exposed a piece of cotton containing bromophenol blue plus sucrose. In addition, we offered several sugars for different species of triatomines, and tested sugar meals as a route of delivery of insecticides in first-instar nymphs of R. prolixus. The effect of sugar feeding on the physiology of these different species of triatomines was recorded. Results: First instar nymphs ingested sucrose more strongly than other stages, and showed high mortality rates. In different species of triatomines, sucrose induced an ingestion, but engorgement varied according to the species. R. prolixus nymphs showed an indiscriminate intake of various sugars, with very different physiological effects. Furthermore, ingesting different combinations of insecticides + sugar significantly reduced insect survival. Discussion: In summary, we described for the first-time sugar feeding as a widespread behavior in several species of triatomines, and the possibility of the use of toxic sugar baits for the control of these vectors. The knowledge of feeding behavior in these insects can be fundamental for the development of new strategies to control Chagas disease.

Role of Deep Eutectic Solvent Precursors as Hydrotropes: Unveiling Synergism/Antagonism for Enhanced Kraft Lignin Dissolution.

Lignin holds significant potential as a feedstock for generating valuable aromatic compounds, fuels, and functional materials. However, achieving this potential requires the development of effective dissolution methods. Previous works have demonstrated the remarkable capability of hydrotropes to enhance the aqueous solubility of lignin, an amphiphilic macromolecule. Notably, deep eutectic solvents (DESs) have exhibited hydrotropic behavior, significantly increasing the aqueous solubility of hydrophobic solutes, making them attractive options for lignin dissolution. This study aimed at exploring the influence of hydrogen bond acceptors (HBAs) and hydrogen bond donors (HBDs) on the performance of DESs as hydrotropes for lignin dissolution, while possible dissolution mechanisms in different water/DES compositions were discussed. The capacity of six alcohols (glycerol, ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, and 1,6-hexanediol) and cholinium chloride to enhance the solubility of Kraft lignin in aqueous media was investigated. A correlation between solubility enhancement and the alkyl chain length of the alcohol was observed. This was rationalized upon the competition between hydrotrope-hydrotrope and solute-hydrotrope aggregates with the latter being maximized for 1,4-butanediol. Interestingly, the hydrotropic effect of DESs on lignin solubility is well represented by the independent sum of the dissolving contributions from the corresponding HBAs and HBDs in the diluted region. Conversely, in the concentrated region, the solubility of lignin for a certain hydrotrope concentration was always found to be higher for the pure hydrotropes rather than their combined HBA/HBD counterparts.

Solid-liquid equilibria of triacylglycerols and vitamin E mixtures.

Oils and fats are important ingredients for food and pharmaceutical industries. Their main compounds, such as triacylglycerols (TAG), are responsible for determining their physical properties during food storage and consumption. Lipid-rich foods are also sources of minority compounds, which is the case of vitamin E, mainly represented by (±)-α-tocopherol. These compounds can interact with the main lipid molecules in food formulation leading to modification on lipids' physicochemical properties during processes, storage, as well as during digestion, possibly altering their nutritional functionalities, which is the case of vitamin E antioxidant abilities, but also their solubility in the systems. In this case, the study of the phase-behavior between (±)-α-tocopherol and lipid compounds can elucidate these physicochemical changings. Therefore, this work was aimed at determining the solid-liquid equilibrium (SLE) of binary mixtures of TAG (tripalmitin, triolein and tristearin) and (±)-α-tocopherol including the complete description of their phase diagrams. Melting data were evaluated by Differential Scanning Calorimetry, Microscopy, X-Ray Diffraction, and thermodynamic modeling by using Margules, UNIFAC, and COSMO-SAC models. Experimental results showed that systems presented a monotectic-like behavior, with a significant decreasing in TAG melting temperature by the addition of (±)-α-tocopherol. This high affinity and attractive strengths between these molecules were also observed by thermodynamic modeling, whose absolute deviations were below 2 %. Micrographs and X-ray diffraction evidenced the possible formation of solid solutions. Both behaviors are interesting by avoiding phase separation on food in solid and liquid phases, possibly improving the antioxidant role the (±)-α-tocopherol in lipid-base systems.

Graphene oxide classification and standardization.

There is a need to classify and standardize graphene-related materials giving the growing use of this materials industrially. One of the most used and more difficult to classify is graphene oxide (GO). Inconsistent definitions of GO, closely relating it to graphene, are found in the literature and industrial brochures. Hence, although they have very different physicochemical properties and industrial applications, commonly used classifications of graphene and GO definitions are not substantial. Consequently, the lack of regulation and standardization create trust issues among sellers and buyers that impede industrial development and progress. With that in mind, this study offers a critical assessment of 34 commercially available GOs, characterized using a systematic and reliable protocol for accessing their quality. We establish correlations between GO physicochemical properties and its applications leading to rationale for its classification.

Phytosterols and γ-Oryzanol as Cholesterol Solid Phase Modifiers during Digestion.

Literature reports that ingestion of phytosterols and γ-oryzanol contributes to cholesterol lowering. Despite in vivo observations, thermodynamic phase equilibria could explain phenomena occurring during digestion leading to such effects. To advance the observations made by previous literature, this study was aimed at describing the complete solid-liquid phase equilibrium diagrams of cholesterol + phytosterol and γ-oryzanol systems by DSC, evaluating them by powder X-ray, microscopy, and thermodynamic modeling. Additionally, this study evaluated the phenomena observed by an in vitro digestibility method. Results confirmed the formation of solid solution in the cholesterol + phytosterols system at any concentration and that cholesterol + γ-oryzanol mixtures formed stable liquid crystalline phases with a significant melting temperature depression. The in vitro protocol supported the idea that the same phenomena can occur during digestion in which mechanochemical forces were probably the mechanisms promoting cholesterol solid phase changes in the presence of such phytocompounds. In this case, these changes could alter cholesterol solubility and possibly its absorption in the gastrointestinal lumen.

Solid-liquid equilibrium of free form of oil contaminants (3-MCPD and glycidol) in lipidic systems.

Esters of 3-monochloropropane-1,2-diol (3-MCPD) and glycidol are reported vegetable fats and oils contaminants formed during processing. During digestion, esterified forms are hydrolyzed making the free forms, with high toxicity to human health, possibly available in the digestive system, which could depend, among other factors, on the phase condition stablished in the gastrointestinal tract between contaminants and lipids. Therefore, this work was aimed at evaluating the solid-liquid equilibrium (SLE) of binary and pseudobinary mixtures of fatty acids (palmitic, oleic and stearic), triacylglycerols (tripalmitin, triolein and tristearin) and a partial acylglycerols, with 3-MCPD and glycidol, by differential scanning calorimetry (DSC) and thermodynamic modeling with Margules 2 and 3 suffixes, UNIFAC and ideal models. Melting properties of the contaminants were determined by DSC thermograms, with microstructure micrographs and compared to some predictive group contribution models (GC). 14 complete SLE phase diagrams could be determined. Results showed that the lipid compounds had high affinity with the free contaminants with probably the formation of liquid crystalline structures and/or solid solutions. The Margules 3 suffixes model showed the best fit with the lowest average relative deviations, no higher than 1%, although the parameters probably incorporated the non-ideality promoted by the crystalline phase behavior. The formation of mesophases and/or solid solutions with very high melting temperature probably means a difficulty of separating the contaminants from the lipid matrix in which, on the other hand, could avoid separation process or affect (probably decreasing) their absorption during digestion.

2D Electrolytes: Theory, Modeling, Synthesis, and Characterization.

A class of compounds sharing the properties of 2D materials and electrolytes, namely 2D electrolytes is described theoretically and demonstrated experimentally. 2D electrolytes dissociate in different solvents, such as water, and become electrically charged. The chemical and physical properties of these compounds can be controlled by external factors, such as pH, temperature, electric permittivity of the medium, and ionic concentration. 2D electrolytes, in analogy with polyelectrolytes, present reversible morphological transitions from 2D to 1D, as a function of pH, due to the interplay of the elastic and Coulomb energies. Since these materials show stimuli-responsive behavior to the environmental conditions, 2D electrolytes can be considered as a novel class of smart materials that expand the functionalities of 2D materials and are promising for applications that require stimuli-responsive demeanor, such as drug delivery, artificial muscles, and energy storage.

Accelerated Synthesis of Graphene Oxide from Graphene.

Graphene oxide (GO) is an oxygenated functionalized form of graphene that has received considerable attention because of its unique physical and chemical properties that are suitable for a large number of industrial applications. Herein, GO is rapidly obtained directly from the oxidation of graphene using an environmentally friendly modified Hummers method. As the starting material consists of graphene flakes, intercalant agents are not needed and the oxidation reaction is enhanced, leading to orders of magnitude reduction in the reaction time compared to the conventional methods of graphite oxidation. With a superior surface area, the graphene flakes are quickly and more homogeneously oxidized since the flakes are exposed at the same extension to the chemical agents, excluding the necessity of sonication to separate the stacked layers of graphite. This strategy shows an alternative approach to quickly producing GO with different degrees of oxidation that can be potentially used in distinct areas ranging from biomedical to energy storage applications.

The Degree of Oxidation of Graphene Oxide.

We show that the degree of oxidation of graphene oxide (GO) can be obtained by using a combination of state-of-the-art ab initio computational modeling and X-ray photoemission spectroscopy (XPS). We show that the shift of the XPS C1s peak relative to pristine graphene, ΔEC1s, can be described with high accuracy by ΔEC1s=A(cO-cl)2+E0, where c0 is the oxygen concentration, A=52.3 eV, cl=0.122, and E0=1.22 eV. Our results demonstrate a precise determination of the oxygen content of GO samples.

Two-dimensional adaptive membranes with programmable water and ionic channels.

Membranes are ubiquitous in nature with primary functions that include adaptive filtering and selective transport of chemical/molecular species. Being critical to cellular functions, they are also fundamental in many areas of science and technology. Of particular importance are the adaptive and programmable membranes that can change their permeability or selectivity depending on the environment. Here, we explore implementation of such biological functions in artificial membranes and demonstrate two-dimensional self-assembled heterostructures of graphene oxide and polyamine macromolecules, forming a network of ionic channels that exhibit regulated permeability of water and monovalent ions. This permeability can be tuned by a change of pH or the presence of certain ions. Unlike traditional membranes, the regulation mechanism reported here relies on specific interactions between the membranes' internal components and ions. This allows fabrication of membranes with programmable, predetermined permeability and selectivity, governed by the choice of components, their conformation and their charging state.

Screening effect of CVD graphene on the surface free energy of substrates.

The wettability of graphene has been a topic under constant discussion in the literature since 2012. In this work we measured the contact angle (CA) of six different types of substrates (glass, quartz, Si3N4, Si/SiO2, sapphire and Si) with varying dielectric constants and surface roughnesses in order to calculate the surface free energy of graphene films to evaluate how the wetting properties of graphene-coated substrates are changed according to the underlying substrate. We used a residual-free transfer process to remove the high-quality graphene (CVD-Gr) grown onto copper foil. Afterwards, we performed an inert thermal treatment (Ar, at 300 °C for 30 minutes) to remove airborne contaminants from the graphene surface and evaluate the roughness of substrates by atomic force microscopy, the advancing and receding contact angles of two liquids (water and ethylene glycol), hysteresis, and surface free energy (polar and dispersive components) calculations. The presence of high-quality monolayer graphene (free of any air contaminants, polymer residues, etc.) led to a common wettability behaviour for all coated surfaces, regardless of the nature of the underlying substrate. This result can be understood in terms of the screening of van der Waals and dipole interactions by the electrons in graphene.

Mononuclear Phagocyte Activation Is Associated With the Immunopathology of Psoriasis.

Psoriasis is a chronic, inflammatory disease affecting the skin and joints. The pathogenesis of this disease is associated with genetic, environmental and immunological factors, especially unbalanced T cell activation and improper keratinocyte differentiation. Psoriatic lesion infiltrate is composed of monocytes and T cells, and most studies have focused on the participation of T cells in the pathogenesis of this disease. Here we investigated the contribution of mononuclear phagocytes in the immunopathology observed in psoriatic patients. Significant increases in the levels of TNF, IL-1ß, CXCL9, as well as the soluble forms of CD14 and CD163, were observed within the lesions of psoriatic patients compared to skin biopsies obtained from healthy individuals. Moreover, we found an association between the levels of CCL2, a monocyte attractant chemokine, and disease severity. In conclusion, our findings suggest a potential role for mononuclear phagocytes in the pathogenesis of psoriasis.

Surface crystallization of ionic liquid crystals.

The evidence for surface crystallization in ionic liquids is scarce. The existing reports seem to be contradictory as for its driving forces, since in the two compounds investigated in the literature, the contribution of coloumbic and van der Waals forces is very different. In this work 1-dodecyl-3-methylimidazolium tetrafluoroborate was studied and its surface crystallization characterized by surface tension, ellipsometry and optical microscopy. The results obtained seem to reconcile previous observations, and it was further shown, using the same techniques, that this phenomenon is prevalent in other ionic liquids. MD simulation results illustrate the different possibilities of organization, providing reasonable models to rationalize the experimental observations.

Phase equilibrium and physical properties of biobased ionic liquid mixtures.

Protic ionic liquid crystals (PILCs) obtained from natural sources are promising compounds due to their peculiar properties and sustainable appeal. However, obtaining PILCs with higher thermal and mechanical stabilities for product and process design is in demand and studies on such approaches using this new IL generation are still scarce. In this context, this work discloses an alternative way for tuning the physicochemical properties of ILCs by mixing PILs. New binary mixtures of PILs derived from fatty acids and 2-hydroxy ethylamines have been synthesized here and investigated through the characterization of the solid-solid-[liquid crystal]-liquid thermodynamic equilibrium and their rheological and critical micellar concentration profiles. The mixtures presented a marked nonideal melting profile with the formation of solid solutions. This work revealed an improvement of the PILCs' properties based on a significant increase in the ILC temperature domain and the obtainment of more stable mesophases at high temperatures when compared to pure PILs. In addition, mixtures of PILs also showed significant changes in their non-Newtonian and viscosity profile up to 100 s-1, as well as mechanical stability over a wide temperature range. The enhancement of the physicochemical properties of PILs here disclosed by such an approach leads to more new possibilities of their industrial application at high temperatures.

Phase Behavior and Physical Properties of New Biobased Ionic Liquid Crystals.

Protic ionic liquids (PILs) have emerged as promising compounds and attracted the interest of the industry and the academy community, due to their easy preparation and unique properties. In the context of green chemistry, the use of biocompounds, such as fatty acids, for their synthesis could disclose a possible alternative way to produce ILs with a low or nontoxic effect and, consequently, expanding their applicability in biobased processes or in the development of bioproducts. This work addressed efforts to a better comprehension of the complex solid-[liquid crystal]-liquid thermodynamic equilibrium of 20 new PILs synthesized by using fatty acids commonly found in vegetable oils, as well as their rheological profile and self-assembling ability. The work revealed that their phase equilibrium and physical properties are significantly impacted by the structure of the ions used for their synthesis. The use of unsaturated fatty acids and bis(2-hydroxyethyl)ammonium for the synthesis of these biobased ILs led to a drastic decreasing of their melting temperatures. Also, the longest alkyl chain fatty acids promoted higher self-assembling and more stable mesophases. Besides their sustainable appeal, the marked high viscosity, non-Newtonian profile, and very low critical micellar concentration values of the PIL crystals here disclosed make them interesting renewable compounds with potential applications as emulsifiers, stabilizers, thickeners, or biolubricants.

The Crystal-T algorithm: a new approach to calculate the SLE of lipidic mixtures presenting solid solutions.

Lipidic mixtures present a particular phase change profile highly affected by their unique crystalline structure. However, classical solid-liquid equilibrium (SLE) thermodynamic modeling approaches, which assume the solid phase to be a pure component, sometimes fail in the correct description of the phase behavior. In addition, their inability increases with the complexity of the system. To overcome some of these problems, this study describes a new procedure to depict the SLE of fatty binary mixtures presenting solid solutions, namely the "Crystal-T algorithm". Considering the non-ideality of both liquid and solid phases, this algorithm is aimed at the determination of the temperature in which the first and last crystal of the mixture melts. The evaluation is focused on experimental data measured and reported in this work for systems composed of triacylglycerols and fatty alcohols. The liquidus and solidus lines of the SLE phase diagrams were described by using excess Gibbs energy based equations, and the group contribution UNIFAC model for the calculation of the activity coefficients of both liquid and solid phases. Very low deviations of theoretical and experimental data evidenced the strength of the algorithm, contributing to the enlargement of the scope of the SLE modeling.