The cal-ad analysis of HZSM-5 provides a novel characterization of the donor-acceptor properties of this solid acid showing 0.0415 mmol per g of a strong Brönsted site and 0.53 mmol per g of a weaker site. Of all studies to date, only cal-ad provides a measure of the extent, Ki ; strength, −ΔHi ; and quantity of sites. The relative K values show why gas phase calorimetry, TPD, TGA, DSC, and isopropylamine decomposition do not resolve the two sites found by cal-ad and incorrectly suggest 0.6 mmol g-1 of strong acid sites. Reaction with pyridine gives an enthalpy of 42.1 and 8.6 kcal mol-1, respectively, for the two sites suggesting the latter is a hydrogen bonding site. Other acidity measures average these sites, and their enthalpies contain dispersion as well as donor-acceptor components. Comparison of these results with other cal-ad results suggests HZSM-5 is a strong solid acid but not a super acid. Titrations with 2,6-lutidine and 2,6-di-tert-butylpyridine indicate that the strong Brönsted sites are located in the 5.5 Å channels with no detectable amounts on the exterior surface.

Biopolymers are promising materials as electrolytes with high flexibility, good performance, cost effectiveness, high compatibility with solvents, and film-forming ability. Chitosan (CS) and carboxymethylcellulose (CMC) can form an intermolecular complex, giving rise to hydrogels capable of absorbing ionic solutions. Citric acid (CA) is an effective biological chemical crosslinker that assists the formation of amide and ester bonds between CMC and CS, resulting in a structure with high ionic conductivity and good structural integrity. In this study, a chemical crosslinking strategy is used to synthesize electrolyte hydrogels for zinc–air batteries. The effects of crosslinking are studied on the structural and electrochemical performance of the membranes. The results show an improvement in the ionic conductivity with respect to the homologous electrolyte hydrogel systems reported, with a maximum of 0.19 S∙cm−1 at 30 °C. In addition, the cyclic voltammetry studies showed a current intensity increase at higher CA content, reaching values of 360 mA∙cm−2. Structural characterization suggests a higher thermal stability and a decrease in the degree of crystallinity caused by the polymers’ crosslinking. Finally, these membranes were tested in Zn–air batteries, obtaining power densities of 85 mW∙cm−2. The proposed hydrogels show to be appropriate for energy zinc–air battery applications and present an alternative to support the sustainable energy transition.

The feasibility of predicting concentrations of methanol and methyl tert-butyl ether (MTBE) in gasolines from the mid-infrared absorption spectra was investigated. The C-O bond stretching band region was related to these oxygenated compounds' levels with the aid of multivariate statistics. The sample spectra were taken with the use of a circular internal reflectance (CIRCLE®) cell. With the use of partial least-squares (PLS) regression a model with 18 samples was built and used to predict a set of 10 gasolines with good agreement. Two additional samples prepared with other brands of gasoline were analyzed with the same model and no matrix effects were found.

This research reported a hydrogel loaded with the ethanolic and methanolic extracts of Eupatorium glutinosum Lam. The E. glutinosum extracts were characterized by phytochemical screening, Fourier-transform infrared spectroscopy (FTIR), thin-layer chromatography (TLC), and UV/Vis profile identification. This research also evaluated the pharmacological activity of the extracts using antimicrobial, antioxidant, and anti-inflammatory assays prior to polymeric encapsulation. Results indicate that extracts inhibit the Escherichia colii DH5-α (Gram negative) growth; excellent antioxidant activity was evaluated by the ferric reducing power and total antioxidant activity assays, and extracts showed an anti-hemolytic effect. Moreover, the cotton and microcrystalline cellulose hydrogels demonstrate successful encapsulation based on characterization and kinetics studies such as FTIR, extract release, and swelling degree. Moreover, effective antibacterial activity was registered by the loaded hydrogel. The overall results encourage and show that Eupatorium glutinosum-loaded hydrogel may find a wide range of bandage and wound healing applications in the biomedical area.

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