Exploring graphene oxide in environmentally altered graphite: a link between chemistry and archaeology.
Notice bibliographique
Résumé
Graphene oxide (GO) has drawn a great deal of attention, in a laboratory setting, due to its ability to stay suspended in water more easily for solution processing of graphene. In an outdoor setting, it is possible that GO is formed as graphite degrades over time in charred carbon-rich materials such as archaeological charcoal. This GO could be used as a valuable source for radiocarbon dating because its carbon would have the same age as the graphitic carbon that is traditionally extracted for dating. Before radiocarbon dating, graphitic samples are cleaned using a series of strong acid and base treatments to remove contaminants. However, this cleaning procedure can break down some graphite-based samples, leaving no graphite for ¹⁴C dating. In those situations, we suspect that GO is cleaned away along with the unwanted contaminants. Our studies are the first to consider whether GO exists in archaeological charcoal and if it can be separated effectively from carbon-containing contaminants. These findings will be particularly useful for chemists and environmental scientists who work with natural sources of graphite in which oxidized graphenic materials may be present. Here, we show that a mixture of oxidized graphenic material with different degrees of oxidation, and fluorescent carbon-based materials, can be present in archaeological charcoal. We also develop a straightforward protocol that separates a simple test case of a lab-prepared mixture of these components. Our results help to explain why a significant amount of archaeological charcoal is sometimes lost during aqueous cleaning treatments at different pH values. The fluorescent carbon-based materials described above could originate from either the original graphite (in the form of highly oxidized pieces, called oxidative debris (OD)) or from contaminants (such as humic acid (HA)). The fluorescent materials stay suspended in alkaline aqueous solutions. Although UV-Vis data of base-treated archaeological charcoal shows evidence of oxidized carbon, it is not informative enough to study a mixture of oxidized graphite, OD, and HA. Therefore, we monitor UV absorption at specific wavelengths as a function of retention time using size exclusion chromatography (SEC). Our results demonstrate that distinguishing oxidized graphite, OD, and HA from each other is very challenging. Based on SEC results, we identify materials in archaeological charcoal that have similar UV excitation responses and similar retention time (size) to a common HA standard, as well as other components with similar UV excitation responses at longer retention times (smaller sizes).
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,001 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,001 | 0,001 |
| Méta-épidémiologie (sens large) | 0,001 | 0,000 |
| Bibliométrie | 0,001 | 0,001 |
| Études des sciences et des technologies | 0,001 | 0,001 |
| Communication savante | 0,000 | 0,001 |
| Science ouverte | 0,001 | 0,001 |
| Intégrité de la recherche | 0,000 | 0,001 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».