RESUMO
Polymers are ubiquitously present in our daily life because they can meet a wide range of needs and fields of applications. This success, based on an irresponsible linear consumption of plastics and the access to cheap oil, is creating serious environmental problems. Two lines of actions are needed to cope with them: to adopt a circular consumption of plastics and to produce renewable carbon-neutral monomers. This review analyses the recent advances in the chemocatalytic processes for producing biomass-derived carboxylic acids. These renewable carboxylic acids are involved in the synthesis of relevant general purpose and specialty polyesters and polyamides; some of them are currently derived from oil, while others can become surrogates of petrochemical polymers due to their excellent performance properties. Polyesters and polyamides are very suitable to be depolymerised to other valuable chemicals or to their constituent monomers, what facilitates the circular reutilisation of these monomers. Different types of carboxylic acids have been included in this review: monocarboxylic acids (like glycolic, lactic, hydroxypropanoic, methyl vinyl glycolic, methyl-4-methoxy-2-hydroxybutanoic, 2,5-dihydroxypent-3-enoic, 2,5,6-trihydroxyhex-3-enoic acids, diphenolic, acrylic and δ-amino levulinic acids), dicarboxylic acids (2,5-furandicarboxylic, maleic, succinic, adipic and terephthalic acids) and sugar acids (like gluconic and glucaric acids). The review evaluates the technology status and the advantages and drawbacks of each route in terms of feedstock, reaction pathways, catalysts and economic and environmental evaluation. The prospects and the new research that should be undertaken to overcome the main problems threatening their economic viability or the weaknesses that prevent their commercial implementation have also been underlined.
RESUMO
OBJECTIVE: The pandemic disease by SARS-CoV-2 infection does not have an effective treatment. To prevent the disease, scientists developed vaccines that the clinicians use as an emergency licensed vaccine. The objective of this study was to determine the side effects in personnel vaccinated at the Military Central Hospital of Mexico with the BNT162b2 vaccine. PATIENTS AND METHODS: This study included the subjects who had received both doses of the BNT162b2 vaccine between December 2020 and February 2021. We asked about the side effects after the first and the second vaccine doses. One group had no history of COVID-19, and the second had a history of COVID-19. ANTI-SARS-CoV-2 antibodies were measured by the immunodetection technique in the second group only. RESULTS: We included 946 participants, 62% were women, and 80% were without comorbidities; 680 were included in the first group, and only 266 were in the second group. After the first dose, 77% of the first group and 86% of the second group presented some side effects. After the second dose, 84% of the first group and 89% of the second group showed some side effects. The main side effect was mild pain. All participants (126) were IgG positive, and only 26.9% were IgM positive at 17.5 days (12.8 days, 20.3 days) after the second dose. CONCLUSIONS: There is a positive correlation between side effects after the first dose in patients with a history of previous SARS-CoV-2 infection compared to those who did not. Nevertheless, this correlation is not present after the second dose. The low percentage of IgM could be related to the time interval between vaccination and sample measure.