Academic literature on the topic 'Acid-basic neutralization capacity'

ABSTRACT Neutralizing antibodies (NAbs) against severe acute respiratory syndrome (SARS) coronavirus (SARS-CoV) spike (S) glycoprotein confer protection to animals experimentally infected with the pathogenic virus. We and others previously demonstrated that a major mechanism for neutralizing SARS-CoV was through blocking the interaction between the S glycoprotein and the cellular receptor angiotensin-converting enzyme 2 (ACE2). In this study, we used in vivo electroporation DNA immunization and a pseudovirus-based assay to functionally evaluate immunogenicity and viral entry. We characterized the neutralization and viral entry determinants within the ACE2-binding domain of the S glycoprotein. The deletion of a positively charged region SΔ(422-463) abolished the capacity of the S glycoprotein to induce NAbs in mice vaccinated by in vivo DNA electroporation. Moreover, the SΔ(422-463) pseudovirus was unable to infect HEK293T-ACE2 cells. To determine the specific residues that contribute to related phenotypes, we replaced eight basic amino acids with alanine. We found that a single amino acid substitution (R441A) in the full-length S DNA vaccine failed to induce NAbs and abolished viral entry when pseudoviruses were generated. However, another substitution (R453A) abolished viral entry while retaining the capacity for inducing NAbs. The difference between R441A and R453A suggests that the determinants for immunogenicity and viral entry may not be identical. Our findings provide direct evidence that these basic residues are essential for immunogenicity of the major neutralizing domain and for viral entry. Our data have implications for the rational design of vaccine and antiviral agents as well as for understanding viral tropism.

Abstract Aims/hypothesis Pohang Tertiary mudstone presents the issue of acid rock drainage. This study analyzed the capacity of a mixed slag (70% steel slag + 30% blast furnace slag) to neutralize Pohang Tertiary mudstone’s acid rock drainage. Methods Element analysis, acid neutralization capacity (ANC) test, and net acid generation (NAG) test were conducted on Pohang Tertiary mudstone samples and the mixed slag. The XRF analysis and the XRD analysis on the mixed slag were conducted to measure the CaO content, which indicates the potential of the mixed slag as an acid-neutralizing agent. Results According to the analysis results on the Pohang Tertiary mudstone samples, the total sulfur content was high, which indicates a high risk of acid rock drainage generation. Although there were slight deviations between the samples, overall, the mudstone exhibited a high acid rock drainage generation capacity. The XRF analysis of mixed slag results showed high amounts of CaO content. From the XRD analysis graph, it was clear that a high proportion of minerals with Ca- compounds consisting of basic substances were present. The neutralization capacity of the mixed slag on Pohang Tertiary mudstone was determined by the relationship between maximum potential acidity (MPA) and acid neutralization capacity (ANC). For instance, the mixed slag of 4.5% effectively neutralizes a sulfur content of 1%.

Abstract Aims/hypothesis Pohang Tertiary mudstone presents the issue of acid rock drainage. This study analyzed the capacity of a mixed slag (70% steel slag + 30% blast furnace slag) to neutralize Pohang Tertiary mudstone’s acid rock drainage. Methods Element analysis, acid neutralization capacity (ANC) test, and net acid generation (NAG) test were conducted on Pohang Tertiary mudstone samples and the mixed slag. The XRF analysis and the XRD analysis on the mixed slag were conducted to measure the CaO content, which indicates the potential of the mixed slag as an acid-neutralizing agent. Results According to the analysis results on the Pohang Tertiary mudstone samples, the total sulfur content was high, which indicates a high risk of acid rock drainage generation. Although there were slight deviations between the samples, overall, the mudstone exhibited a high acid rock drainage generation capacity. The XRF analysis of mixed slag results showed high amounts of CaO content. From the XRD analysis graph, it was clear that a high proportion of minerals with Ca- compounds consisting of basic substances were present. The neutralization capacity of the mixed slag on Pohang Tertiary mudstone was determined by the relationship between maximum potential acidity (MPA) and acid neutralization capacity (ANC). For instance, the mixed slag of 4.5% effectively neutralizes a sulfur content of 1%.

Background: In this study, we determined the acid neutralizing capacity (ANC) of Mg/Al-Hydrotalcite-like compounds. The MgAl-hydrotalcites were synthesized by co-precipitation method at room temperature using Mg/Al molar ratios 2 and 3. The synthesized bioactive nanomaterials were characterized by various physico-chemical techniques such as TG/dTG, DRX, FT-IR spectroscopy, BET/BHJ and MEB/EDX. The antacid activity assay was done by converting both synthesized samples into liquids, 1 g of which was added to 50 ml of deionized water at 37°C under vigorous agitation. The acid neutralizing capacity (ANC) was evaluated with 0.1N HCl. The pH was constantly measured using a pH meter and values were recorded every minute up to 35 min. In order to improve the neutralizing power of the samples, we performed on the MgAl-HT3 synthesized an exchange of chlorides by carbonates. The exchanged Mg/Al-Hydrotalcite (MgAl-HTE) shows a high acid neutralization capacity (up to 13.5 mEq/g). Objective: To synthesize an MgAl-hydrotalcite-like compounds and evaluation of their acid neutralizing capacity and thus can be good candidates for pharmaceutical applications as antacid drugs. Methods: Preparation of MgAl-hydrotalcite-like compounds by coprecipitation methods - Characterization of samples by physico-chemical techniques such as TG/dTG, DRX, FT-IR spectroscopy, BET/BHJ and MEB/EDX. - Evaluation of acid neutralizing capacity by titration procedure (Dose-titration) . Results: This protocol describes the preparation of MgAlhydrotalcite-like using the classical coprecipitation method. The synthesized samples were characterized by various physicochemical techniques such as TG/dTG, DRX, FT-IR spectroscopy, BET/BHJ and MEB/EDX. The as-synthetized samples were used for the evaluation of their acid-neutralizing capacity (ANC). Further, an exchanged MgAl-Hydrotalcite with carbonate was described for the purpose to increases the acid-neutralizing capacity. Conclusion: In summary, this study describes a simple synthesis of MgAl-Hydrotalcites compounds by a co-precipitation method at constant pH around 10, with a ratio Mg/Al = 3 and 2 (referred to as MgAl-HT3 and MgAl-HT2). An exchange of the chlorides (not eliminated by washing) by the carbonates was carried out on hydrotalcite with a ratio Mg/Al = 3 and the solid obtained was named MgAl-HT3E. The materials MgAl-HT2, MgAl-HT3 and MgAl-TH3E were used to evaluate their antacid activity. To this end, a study was conducted to determine the acid neutralizing capacity (ANC). As a result, the MgAl-HT3E was able to increase acid neutralizing capacity and maintaining an ideal pH. These results could be interesting to prepare novel antacid drugs (due to the low cost of synthesized materials) essentially the hydrotalcite of Mg/Al ratio equal to 3 because of its relatively slow kinetics of releasing basic species and therefore of its beneficial action as an antacid.

Les sédiments urbains et résidus minier sont deux sources de pollution potentielle pour l’environnement et plus particulièrement les eaux de surfaces ou les eaux souterraines. L’altération chimique de ces interfaces solides par contact avec une source d’acidité ou d’alcalinité via l’air ou l’eau, est susceptible de se traduire par une dissolution des phases minérales et organiques et d’induire une mobilisation des éléments majeurs et traces métalliques. Ces mécanismes sont encore mal décrits et modélisés pour ce type de matrices très complexes. Cette thèse étudie donc le potentiel de mobilisation des éléments majeurs et traces métalliques de diverses interfaces carbonaté ou non carbonaté (pour l’étude du drainage minier acide et neutre contaminé). En supplément, des interfaces minérales pures ont été utilisées pour simuler en laboratoire des assemblages de phases et identifier les mécanismes croisés impliqués dans le drainage minier acide et neutre contaminé. Toutes ces matrices ont été soumises à des tests de capacité de neutralisation acido-basique (mise en contact avec une source de protons ou d’alcalinité), avec le suivi du pH (pouvoir tampon), de la conductivité et de la mobilisation élémentaire (majeurs et éléments traces métalliques). Les données expérimentales ont été modélisées avec le logiciel de spéciation géochimique PHREEQC. La combinaison des volets d’expérimentation et de modélisation, qui a très rarement été développé sur des interfaces solides aussi complexes, a permis l’identification (i) des réactions de dissolution des phases constitutives des interfaces polluées avec les réactions de sorption impliquées dans la mobilisation de leurs éléments majeurs et traces métalliques, (ii) de la spéciation des éléments majeurs et traces métalliques dans ces interfaces et dans les solutions en équilibre avec les phases solides. Ce travail de thèse permet donc d’aboutir à une méthodologie robuste, précise et réplicable permettant une caractérisation fine de la spéciation en phase liquide et solide des polluants métalliques dans les interfaces contaminées. Cette méthodologie constitue une base cruciale pour comprendre et prédire l’évolution des matières solides contaminées (sédiments urbains et déchets miniers) en fonction des différents modes de gestion : dépollution, valorisation et recyclage<br>Urban sediments and mine tailings constitute two potential sources of pollution for the environment, especially surface water or groundwater. The chemical alteration of these solid matrices by contact with a source of acidity or alkalinity via air or water is likely to result in the dissolution of the mineral and organic phases and to induce the mobilization of majors and trace elements. These mechanisms are still poorly described and modeled for this type of very complex matrices. This thesis investigates potential for the mobilization of major and trace metals elements of various contaminated complex matrices, including an urban infiltration basin sediment and two carbonated and non-carbonated mining waste (for the study of contaminated acid mining drainage and contaminated neutral drainage). Besides, pure minerals were used to simulate phase mixture at the laboratory and identify the crossed mechanisms involved in contaminated acid and neutral mine drainage. All these matrices were subjected to acid-base neutralization capacity tests (solids put into contact with a source of protons or alkalinity), with monitoring of the pH (buffer capacity), the conductivity and the elemental release (major and trace metal elements). Experimental data were modeled with the PHREEQC geochemical speciation software. The combination of experimental and modeling approaches, which had very rarely been developed on such complex solid matrices, allowed the identification of (i) the dissolution reactions of the constitutive phases of the polluted matrices with the sorption reactions involved in the mobilization of their major and trace metal elements, (ii) the speciation of the major and trace metal elements in these matrices and in solution in equilibrium with the solid phases. This thesis, therefore, leads to a robust, precise and replicable methodology allowing a fine characterization of liquid and solid phase speciation of metallic pollutants in contaminated matrices. This methodology constitutes a crucial basis for understanding and predicting the evolution of contaminated solids (urban sediments and mining waste) according to different management methods: decontamination, recovery, and recycling