The protection of classical or significant reference stratigraphic sections of the nation’s valuable geoheritage has become a priority by the Chinese government and national stratigraphic commission.The process for t...The protection of classical or significant reference stratigraphic sections of the nation’s valuable geoheritage has become a priority by the Chinese government and national stratigraphic commission.The process for the protection and documentation of stratigraphic sections includes:(1)marked tablets showing the standardized bed,member and formation divisions and,where applicable,standardized meter intervals for future investigations;(2)a monument or other on-site interpretive information;and(3)field guides for different audiences summarizing its importance with maps and detailed descriptions.In particular,the ten Global Stratotype Sections and Points(GSSPs)established in southern China are well preserved and managed;and some are now within tourist-friendly educational national geoparks.We suggest that other national stratigraphic commissions might incorporate some of the experiences from China’s current efforts to preserve and standardize important reference sections for Earth history research.展开更多
Paper documents experience severe acidification and embrittlement.Nanocellulose is an excellent reinforcement material for paper documents owing to its compatibility and excellent mechanical strength.However,little re...Paper documents experience severe acidification and embrittlement.Nanocellulose is an excellent reinforcement material for paper documents owing to its compatibility and excellent mechanical strength.However,little research has been conducted on the aging resistance of nanocellulose-reinforced paper.In this study,six types of nanocelluloses were used to reinforce aged paper.The reinforcement and anti-aging performances were evaluated,and the anti-aging mechanism was further clarified.Nanocellulose with a high degree of polymerization can better enhance aged paper,and non-chemical nanocellulose also shows better anti-aging performance,such as nanocellulose prepared by mechanical or biological methods.However,nanocellulose prepared using chemical methods exhibits poor reinforcement and anti-aging performance.This is because it has a small particle size that is not beneficial for physical crosslinking with paper fibers.More importantly,the introduction of acidic or oxidizing groups on nanocellulose accelerates the acid hydrolysis and oxidation rate of paper fibers,especially nanocellulose prepared by 2,2,6,6-tetramethylpiperidine-1-oxyl oxidation,which should not be used to protect paper documents.展开更多
文摘The protection of classical or significant reference stratigraphic sections of the nation’s valuable geoheritage has become a priority by the Chinese government and national stratigraphic commission.The process for the protection and documentation of stratigraphic sections includes:(1)marked tablets showing the standardized bed,member and formation divisions and,where applicable,standardized meter intervals for future investigations;(2)a monument or other on-site interpretive information;and(3)field guides for different audiences summarizing its importance with maps and detailed descriptions.In particular,the ten Global Stratotype Sections and Points(GSSPs)established in southern China are well preserved and managed;and some are now within tourist-friendly educational national geoparks.We suggest that other national stratigraphic commissions might incorporate some of the experiences from China’s current efforts to preserve and standardize important reference sections for Earth history research.
基金supported by the Fundamental Research Funds for the Central Universities of South China University of Technology(SCUT),China(No.2022ZYGXZR106)Science and Technology Plan Special Project of Guangzhou,China(No.GZDD201808).
文摘Paper documents experience severe acidification and embrittlement.Nanocellulose is an excellent reinforcement material for paper documents owing to its compatibility and excellent mechanical strength.However,little research has been conducted on the aging resistance of nanocellulose-reinforced paper.In this study,six types of nanocelluloses were used to reinforce aged paper.The reinforcement and anti-aging performances were evaluated,and the anti-aging mechanism was further clarified.Nanocellulose with a high degree of polymerization can better enhance aged paper,and non-chemical nanocellulose also shows better anti-aging performance,such as nanocellulose prepared by mechanical or biological methods.However,nanocellulose prepared using chemical methods exhibits poor reinforcement and anti-aging performance.This is because it has a small particle size that is not beneficial for physical crosslinking with paper fibers.More importantly,the introduction of acidic or oxidizing groups on nanocellulose accelerates the acid hydrolysis and oxidation rate of paper fibers,especially nanocellulose prepared by 2,2,6,6-tetramethylpiperidine-1-oxyl oxidation,which should not be used to protect paper documents.
