Chitosan and cyanoguanidine-crosslinked chitosan coated glass beads and its application in fixed bed adsorption

Abstract

The aim of this work was to coat glass beads with chitosan and cyanoguanidine-crosslinked chitosan and, afterward, to verify the potential of the coated beads as adsorbent for the FD&C Red 40 dye in fixed bed column. The coating was realized in eight experimental conditions, varying the technique (dip coating or casting) and the coating solution composition (different proportions of chitosan, cyanoguanidine, glycerol, sorbitol, sodium alginate, NaOH and CaCl₂). The beads coated in the eight experimental conditions were then applied to adsorb FD&C Red 40 in a fixed bed column, from aqueous solutions at pH 3.0 and 6.0. The breakthrough curves were fitted according to Thomas and Yoon-Nelson dynamic models. The coating was dependent of the solution composition. The casting technique presented coating percentage values of 92%, while the dip coating technique presented only 43%. The breakthrough curves revealed that the use of glass beads coated with cyanoguanidine-crosslinked chitosan had good performance, attaining adsorption capacity values higher than 80?mg g^?1. Thomas and Yoon-Nelson models were able to predict the breakthrough curves in all conditions.     

Isotherms,kinetics, and thermodynamic studies for adsorption of pigments and oxidation products in oil bleaching from catfish waste

Abstract

The aim of this work was to study the bleaching of oil extracted from the heads of the catfish by thermomechanical process through equilibrium, kinetics, and thermodynamics adsorption studies. The condition for the bleaching step was with 1% (w/w) adsorbent composed of 95% activated earth and 5% activated carbon (w/w). The pseudo-first order and pseudo-second order models were the most appropriate to represent the adsorption kinetics. The temperature of 80?°C increased the adsorption capacity of the two adsorbates, and the activation energies values were of 47.47 and 44.82?kJ mol^?1, respectively, for the adsorption of carotenoids and peroxides. The Langmuir model was the most appropriate to describe the bleaching equilibrium curves. The thermodynamic parameters revealed that the processes were endothermic, favorable, and spontaneous and the interaction between adsorbent and adsorbate was physical.     

Biosorption of chromium (VI) from aqueous solution by seed powder of prickly pear (Opuntia ficus indica L.) fruits

ABSTRACT

The solid residue of the cold press oil extraction from prickly pear (Opuntia ficus indica L.) fruit seeds was evaluated as a low-cost biosorbent for biosorption of Cr(VI) from aqueous solutions. Batch experiments were conducted as a function of initial pH, contact time, biosorbent dose, initial Cr(VI) concentration, and temperature. Biosorption was highly pH-dependent and found to be maximum at pH 1.0. Langmuir and Freundlich equations fitted very well with experimental data. The maximum monolayer adsorption capacity was 19.61 mg/g at 298 K and pH 1.0. Biosorption kinetics was controlled by the pseudo-second-order model. Thermodynamic parameters indicated that biosorption of Cr(VI) was a spontaneous, favorable and endothermic process. The activation energy was found to be 40.68 kJ.mol^?1.     

Gastric Adenocarcinomas and Signet-Ring Cell Carcinoma: Unraveling Gastric Cancer Complexity through Microbiome Analysis—Deepening Heterogeneity for a Personalized Therapy

Gastric cancer (GC) is the fifth most prevalent cancer worldwide and the third leading cause of global cancer mortality. With the advances of the omic studies, a heterogeneous GC landscape has been revealed, with significant molecular diversity. Given the multifaceted nature of GC, identification of different patient subsets with prognostic and/or predictive outcomes is a key aspect to allow tailoring of specific treatments. Recently, the involvement of the microbiota in gastric carcinogenesis has been described. To deepen this aspect, we compared microbiota composition in signet-ring cell carcinoma (SRCC) and adenocarcinoma (ADC), two distinct GC subtypes. To this purpose, 10 ADC and 10 SRCC and their paired non-tumor (PNT) counterparts were evaluated for microbiota composition through 16S rRNA analysis. Weighted and unweighted UniFrac and Bray–Curtis dissimilarity showed significant community-level separation between ADC and SRCC. Through the LEfSe (linear discriminant analysis coupled with effect size) tool, we identified potential microbial biomarkers associated with GC subtypes. In particular, SRCCs were significantly enriched in the phyla Fusobacteria, Bacteroidetes, Patescibacteria, whereas in the ADC type, Proteobacteria and Acidobacteria phyla were found. Overall, our data add new insights into GC heterogeneity and may contribute to deepening the GC classification.     

Electrodeposition of lead dioxide on Fe electrode: application to the degradation of Indigo Carmine dye

Journal of Applied Electrochemistry - The modification of an iron electrode was carried out according to the following two steps. In a first step, a cathodic reduction is performed to form a film...     

Decision‐making in multi‐agency groups at simulated major incident emergencies: In situ analysis of adherence to UK doctrine

When major incident emergencies occur in the UK (e.g., a terrorist attack), senior representatives convene from local emergency services, civil resource organizations, health agencies, and government. These groups make decisions that minimize the societal and economic impacts of major incidents. Their adherence to UK doctrine was assessed using video footage of 18 groups responding to a major incident in a simulation suite, and six groups responding to a large‐scale exercise. There were marked between‐group differences in the sequencing of decision‐making activities, and limited consideration of alternative courses of action. These results provide an impetus for future policy, guidance, and training to address (a) between‐group inconsistency in decision processes and (b) the lack of consideration of alternative courses of action.     

Learning with elaborative interrogations and the impact of learners' emotional states

Self‐generated learning (SGL) activities are characterized as an active learning strategy that functions as a support for deeper comprehension. However, the question arises which factors could be essential to fully exploit the effectiveness of SGL activities. One possible factor may be the emotional state of learners during learning. Because different emotional states are associated with different styles of information processing, in turn, they may support learning with SGL activities. Consequently, this study addresses learning with a type of SGL activities, answering elaborative interrogations, and the impact of learners' emotional states. German students (N = 123) were assigned to one of four conditions, resulting from a 2 × 2 design with instructional material (elaborative interrogations vs. no elaborative interrogations) and emotional state (positive vs. negative) as independent variables. Results showed that learners learning with elaborative interrogations experienced the instructional material as more difficult than without elaborative interrogations. Learning with them led to a better transfer learning outcome of concepts that had to be generated by interrogations (not for concepts that were already readable in the text) and had no effect for retention. Unexpectedly, neither an influence of the learners' emotional state nor an interaction of both independent variables could be shown.     

Likelihood-based tests for a class of misspecified finite mixture models for ordinal categorical data

TEST - The main purpose of this paper is to apply likelihood-based hypothesis testing procedures to a class of latent variable models for ordinal responses that allow for uncertain answers (Colombi...