Aplicações para as cascas de árvores e para os extractos taninosos: uma revisão

De forma a dar uma contribuição para o desenvolvimento de processos tendentes ao aproveitamento da casca de pinheiro bravo, recurso abundante em Portugal, é apresentada, de uma forma resumida, a importância que os extractos da casca ou do cerne de algumas espécies florestais ricos em taninos têm hoje em dia, assim como as próprias cascas. Inclui-se uma definição do termo taninos e aborda-se a sua química. Discutem-se as suas principais aplicações actuais, sejam as já implantadas a nível industrial, sejam os últimos resultados de investigação, no que diz respeito ao curtimento de peles, aos adesivos para madeira, a produtos farmacêuticos e biocidas, a resinas de troca iónica, a painéis de casca e a combustíveis.In order to give a contribution to the development of processes aiming at making use of maritime pine bark, an abundant resource in Portugal, this paper highlights, in short, the nowadays importance of extracts of the bark or heartwood of some forest species, as well as the barks themselves. It is included a definition of tannins and their chemistry is described. The main applications are discussed, either those already established at the industrial scale or the latest research results: leather tanning, wood adhesives, pharmaceuticals and biocides, ion-exchange resins, bark panels and use as fuel. Pour contribuer au développement des procédés d'utilisation de l'écorce du pin maritime, qui est une ressource abondante au Portugal, on souligne au long de ce texte, en abrégé, l'importance qu'ont aujourd'hui les extraits de l'écorce ou du cerne de quelques espèces forestières riches en tannins, ainsi que des écorces seules. Y est incluse une définition du mot tannins et un abordage de leur chimie. On discute les principales applications actuelles, soit celles qui sont déjà établies au niveau industriel, soit les derniers résultats de la recherche: la tannage du cuir, les adhésifs pour des dérivés du bois, les produits chimiques pharmaceu-tiques ou les biocides, les résines d'échange ionique, les panneaux d'écorce ou les combustibles

Caracterização fenólica de extractos tanínicos de casca de Pinus pinaster

Os Taninos são compostos polifenólicos naturais, divididos normalmente em dois grandes grupos, não relacionados estruturalmente entre si: Taninos Hidrolizáveis e Taninos Condensados (ou Proantocianidinas). A principal característica destes compostos consiste na sua capacidade de complexarem e precipitarem proteínas. Podem igualmente condensar com formaldeído ou mesmo autocondensar, sem a presença de qualquer agente reticulante externo. Desse modo, são potenciais intervenientes na síntese de adesivos sem recurso ao uso de aldeídos. Os taninos condensados são bastante comuns e apresentam teores razoáveis em vários tecidos vegetais de uma variedade considerável de espécies. Estes compostos são polímeros ou oligómeros complexos, de unidades f1avanóides, nomeadamente flavan-3-óis e f1avan-3,4-dióis, que podem ser isolados em quantidades significativas da casca de algumas espécies de árvore, entre as quais, as do género Pinus. Pinus pinaster (ou Pinheiro Marítimo ou Bravo) é a principal espécie florestal em Portugal, e a sua casca é especialmente rica em taninos condensados (procianidinas e, com teores inferiores, prodelfinidinas). Portanto, a casca de Pinus pinaster pode-se constituir como uma fonte viável de compostos polifenólicos naturais, e pode ser utilizada com sucesso na substituição total ou parcial de fenol ou resorcinol em resinas sintéticas convencionais para a indústria de aglomerados de madeira. O objectivo deste trabalho consiste na caracterização dos compostos fenólicos presentes em extractos comerciais de diversas origens e em extractos de Pinheiro obtidos com diferentes tipos de solventes alcalinos através da conjugação de várias técnicas de análise, nomeadamente TLC e colorimetria

Improved extraction of pine bark for wood adhesives

Pine bark tannins must be subjected to sulphonation to have an acceptable solubility in water for the preparation of wood adhesives. In this study, several extraction variables (sodium sulphite and urea concentrations in the extraction white liquor, extraction time, bark/liquor ratio and temperature) were assessed for their effect on extraction yield, and on the phenol, sulphur and ash content of extracts. Temperature had the highest positive effect on extraction yield and on the yield of total phenols in the extract. Sulphur content (i.e., the degree of sulphonation) was influenced mostly by sulphite concentration in white liquor, as was ash content

Recent smell loss is the best predictor of COVID-19 among individuals with recent respiratory symptoms

In a preregistered, cross-sectional study we investigated whether olfactory loss is a reliable predictor of COVID-19 using a crowdsourced questionnaire in 23 languages to assess symptoms in individuals self-reporting recent respiratory illness. We quantified changes in chemosensory abilities during the course of the respiratory illness using 0-100 visual analog scales (VAS) for participants reporting a positive (C19+; n=4148) or negative (C19-; n=546) COVID-19 laboratory test outcome. Logistic regression models identified univariate and multivariate predictors of COVID-19 status and post-COVID-19 olfactory recovery. Both C19+ and C19- groups exhibited smell loss, but it was significantly larger in C19+ participants (mean±SD, C19+: -82.5±27.2 points; C19-: -59.8±37.7). Smell loss during illness was the best predictor of COVID-19 in both univariate and multivariate models (ROC AUC=0.72). Additional variables provide negligible model improvement. VAS ratings of smell loss were more predictive than binary chemosensory yes/no-questions or other cardinal symptoms (e.g., fever). Olfactory recovery within 40 days of respiratory symptom onset was reported for ~50% of participants and was best predicted by time since respiratory symptom onset. We find that quantified smell loss is the best predictor of COVID-19 amongst those with symptoms of respiratory illness. To aid clinicians and contact tracers in identifying individuals with a high likelihood of having COVID-19, we propose a novel 0-10 scale to screen for recent olfactory loss, the ODoR-19. We find that numeric ratings ≤2 indicate high odds of symptomatic COVID-19 (4<10). Once independently validated, this tool could be deployed when viral lab tests are impractical or unavailable

More than smell - COVID-19 is associated with severe impairment of smell, taste, and chemesthesis

Recent anecdotal and scientific reports have provided evidence of a link between COVID-19 and chemosensory impairments such as anosmia. However, these reports have downplayed or failed to distinguish potential effects on taste, ignored chemesthesis, generally lacked quantitative measurements, were mostly restricted to data from single countries. Here, we report the development, implementation and initial results of a multi-lingual, international questionnaire to assess self-reported quantity and quality of perception in three distinct chemosensory modalities (smell, taste, and chemesthesis) before and during COVID-19. In the first 11 days after questionnaire launch, 4039 participants (2913 women, 1118 men, 8 other, ages 19-79) reported a COVID-19 diagnosis either via laboratory tests or clinical assessment. Importantly, smell, taste and chemesthetic function were each significantly reduced compared to their status before the disease. Difference scores (maximum possible change+/-100) revealed a mean reduction of smell (-79.7+/- 28.7, mean+/- SD), taste (-69.0+/- 32.6), and chemesthetic (-37.3+/- 36.2) function during COVID-19. Qualitative changes in olfactory ability (parosmia and phantosmia) were relatively rare and correlated with smell loss. Importantly, perceived nasal obstruction did not account for smell loss. Furthermore, chemosensory impairments were similar between participants in the laboratory test and clinical assessment groups. These results show that COVID-19-associated chemosensory impairment is not limited to smell, but also affects taste and chemesthesis. The multimodal impact of COVID-19 and lack of perceived nasal obstruction suggest that SARS-CoV-2 infection may disrupt sensory-neural mechanisms.Additional co-authors: Veronica Pereda-Loth, Shannon B Olsson, Richard C Gerkin, Paloma Rohlfs Domínguez, Javier Albayay, Michael C. Farruggia, Surabhi Bhutani, Alexander W Fjaeldstad, Ritesh Kumar, Anna Menini, Moustafa Bensafi, Mari Sandell, Iordanis Konstantinidis, Antonella Di Pizio, Federica Genovese, Lina Öztürk, Thierry Thomas-Danguin, Johannes Frasnelli, Sanne Boesveldt, Özlem Saatci, Luis R. Saraiva, Cailu Lin, Jérôme Golebiowski, Liang-Dar Hwang, Mehmet Hakan Ozdener, Maria Dolors Guàrdia, Christophe Laudamiel, Marina Ritchie, Jan Havlícek, Denis Pierron, Eugeni Roura, Marta Navarro, Alissa A. Nolden, Juyun Lim, KL Whitcroft, Lauren R. Colquitt, Camille Ferdenzi, Evelyn V. Brindha, Aytug Altundag, Alberto Macchi, Alexia Nunez-Parra, Zara M. Patel, Sébastien Fiorucci, Carl M. Philpott, Barry C. Smith, Johan N Lundström, Carla Mucignat, Jane K. Parker, Mirjam van den Brink, Michael Schmuker, Florian Ph.S Fischmeister, Thomas Heinbockel, Vonnie D.C. Shields, Farhoud Faraji, Enrique Enrique Santamaría, William E.A. Fredborg, Gabriella Morini, Jonas K. Olofsson, Maryam Jalessi, Noam Karni, Anna D'Errico, Rafieh Alizadeh, Robert Pellegrino, Pablo Meyer, Caroline Huart, Ben Chen, Graciela M. Soler, Mohammed K. Alwashahi, Olagunju Abdulrahman, Antje Welge-Lüssen, Pamela Dalton, Jessica Freiherr, Carol H. Yan, Jasper H. B. de Groot, Vera V. Voznessenskaya, Hadar Klein, Jingguo Chen, Masako Okamoto, Elizabeth A. Sell, Preet Bano Singh, Julie Walsh-Messinger, Nicholas S. Archer, Sachiko Koyama, Vincent Deary, Hüseyin Yanik, Samet Albayrak, Lenka Martinec Novákov, Ilja Croijmans, Patricia Portillo Mazal, Shima T. Moein, Eitan Margulis, Coralie Mignot, Sajidxa Mariño, Dejan Georgiev, Pavan K. Kaushik, Bettina Malnic, Hong Wang, Shima Seyed-Allaei, Nur Yoluk, Sara Razzaghi, Jeb M. Justice, Diego Restrepo, Julien W Hsieh, Danielle R. Reed, Thomas Hummel, Steven D Munger, John E Haye

Métodos de extracção de taninos e de preparação de adesivos para derivados de madeira: uma revisão

Com o objectivo de contribuir para a utilização e valorização do resíduo abundante que é a casca de pinheiro bravo em Portugal, são revistos vários métodos de extracção de casca ou de cerne de algumas espécies florestais para a obtenção de extractos taninosos, com especial destaque para a casca de pinheiro. Discute-se a utilização desses extractos na preparação de adesivos para madeira ou derivados de madeira, nas vertentes de resinas só com extracto, com extracto e resina sintética, resinas de cura a frio e como captadores de formaldeído. With the objective of increasing the use and value of maritime pine bark in Portugal, which is an abundant residue, this paper reviews several methods for the extraction of tannin-rich extracts from the bark or heartwood of some forest species, with an emphasis on pine bark. The utilisations of such extracts are discussed as applied to the preparation of adhesives for wood and wood-derivatives, including resins based solely on these extracts, with extract and synthetic resin, with cold set resins and as formaldehyde scavengers. Pour contribuer à l'utilisation et à la valorisation d'un résidu abondant au Portugal qu'est l'écorce de pin maritime, on revoit dans ce texte quelques méthodes d'extraction de l'écorce ou du cerne de quelques espèces forestières pour obtenir des extraits riches en tannins, en insistant sur l'écorce du pin. On discute l'utilisation de ces extraits dans la préparation des adhésifs pour le bois ou dérivés du bois, dans le cas des résines préparées seulement avec extrait, avec extrait et résine synthétique, résines de cure à froid ou comme captateur de formaldéhyde

Recent Smell Loss Is the Best Predictor of COVID-19 Among Individuals With Recent Respiratory Symptoms

In a preregistered, cross-sectional study, we investigated whether olfactory loss is a reliable predictor of COVID-19 using a crowdsourced questionnaire in 23 languages to assess symptoms in individuals self-reporting recent respiratory illness. We quantified changes in chemosensory abilities during the course of the respiratory illness using 0–100 visual analog scales (VAS) for participants reporting a positive (C19+; n = 4148) or negative (C19−; n = 546) COVID-19 laboratory test outcome. Logistic regression models identified univariate and multivariate predictors of COVID-19 status and post-COVID-19 olfactory recovery. Both C19+ and C19− groups exhibited smell loss, but it was significantly larger in C19+ participants (mean ± SD, C19+: −82.5 ± 27.2 points; C19−: −59.8 ± 37.7). Smell loss during illness was the best predictor of COVID-19 in both univariate and multivariate models (ROC AUC = 0.72). Additional variables provide negligible model improvement. VAS ratings of smell loss were more predictive than binary chemosensory yes/no-questions or other cardinal symptoms (e.g., fever). Olfactory recovery within 40 days of respiratory symptom onset was reported for ~50% of participants and was best predicted by time since respiratory symptom onset. We find that quantified smell loss is the best predictor of COVID-19 amongst those with symptoms of respiratory illness. To aid clinicians and contact tracers in identifying individuals with a high likelihood of having COVID-19, we propose a novel 0–10 scale to screen for recent olfactory loss, the ODoR-19. We find that numeric ratings ≤2 indicate high odds of symptomatic COVID-19 (4 < OR < 10). Once independently validated, this tool could be deployed when viral lab tests are impractical or unavailable.info:eu-repo/semantics/acceptedVersio