Glacial diamictite may provide important information on paleoenvironment and average composition of the upper continental crust(UCC).In this study,we report sedimentary facies,petrological and geochemical characterist...Glacial diamictite may provide important information on paleoenvironment and average composition of the upper continental crust(UCC).In this study,we report sedimentary facies,petrological and geochemical characteristics of Neoproterozoic diamictite from a profile of the Luoquan Formation on the southern margin of the North China Block(NCB).Upwards the sampling profile,lithostratigraphic strata vary from massive diamictite with poorly sorted carbonate gravels to laminated diamictite with small gravels of terrestrial detrital materials.Along the profile,CaO-MgO-LOI-Sr values decrease with the increase of SiO_(2)-Al2O_(3)-K2O contents.All these petrological and geochemical variations indicate a change from lodgement till deposition in the proximal of ice sheet to ice-rafting deposition in glacial-marine environment with less dolomite to supply their source.Together with previous studies on diamictite from other outcrops on the NCB,the deposition of Luoquan diamictite reflects that the glaciation on the NCB vanished and the ice-rafting effect weakened with glacial transgression process.In addition,significant co-variations of various elements with La and Al2O_(3)confirm the significant conservation of most analyzed elements during the sedimentary processes to produce diamictite.展开更多
The limitations of native collagen,such as thermal stability and solubility in physiological environments,can be improved by applying bioconjugation and synthetic chemistry techniques.However,the exquisite control of ...The limitations of native collagen,such as thermal stability and solubility in physiological environments,can be improved by applying bioconjugation and synthetic chemistry techniques.However,the exquisite control of the modification site of collagen remains a challenge.In this work,pH-responsive poly(acrylic acid)(PAA)with dif-ferent chain lengths was attached to the N-terminal α-amino groups of succinylated collagen using a site-specific modification strategy.Additionally,the structure,thermal stability,and pH sensitivity of succinylated collagen were explored.The modification rate of amino groups in the succinylated collagen-PAA bioconjugate(SPSC-PAA)was eval-uated by the 2,4,6-trinitrobenzene sulfonic acid assay.The impact of N-terminal modification of PAA and its chain length on the thermal stability of collagen was explored by CD and DSC.These techniques revealed that the ther-mal stability of SPSC-Col is pH-responsive and closely related to the chain length of grafted PAA.The pH sensitivity of SPSC-PAA was further explored by rheology and turbidity.Subsquently,the critical pH and isoelectric point of SPSC-PAAs were also examined by turbidity and isoelectric point titration,respectively.This work provides a new insight into the N-terminal modification of collagen on its properties.展开更多
基金supported by the National Natural Science Foundation of China (Mos.41776069 and 41572047 to Yuanyuan Xiao)Strategic Priority Research Program of the Chinese Academy of Sciences (No.XDB42020302)+1 种基金the Taishan Scholar Program of Shandong (No.ts201712075)Aoshan Scholar Program of the Pilot National Laboratory for Marine Science and Technology (Qingdao) to Weidong Sun。
文摘Glacial diamictite may provide important information on paleoenvironment and average composition of the upper continental crust(UCC).In this study,we report sedimentary facies,petrological and geochemical characteristics of Neoproterozoic diamictite from a profile of the Luoquan Formation on the southern margin of the North China Block(NCB).Upwards the sampling profile,lithostratigraphic strata vary from massive diamictite with poorly sorted carbonate gravels to laminated diamictite with small gravels of terrestrial detrital materials.Along the profile,CaO-MgO-LOI-Sr values decrease with the increase of SiO_(2)-Al2O_(3)-K2O contents.All these petrological and geochemical variations indicate a change from lodgement till deposition in the proximal of ice sheet to ice-rafting deposition in glacial-marine environment with less dolomite to supply their source.Together with previous studies on diamictite from other outcrops on the NCB,the deposition of Luoquan diamictite reflects that the glaciation on the NCB vanished and the ice-rafting effect weakened with glacial transgression process.In addition,significant co-variations of various elements with La and Al2O_(3)confirm the significant conservation of most analyzed elements during the sedimentary processes to produce diamictite.
基金supported by the National Natural Science Foundation of China(Nos.22378320,22178277,21706201)Knowledge Innovation Program of Wuhan-Basi Research,China(No.2023020201010148)Appli cation Foundation Frontier Project of Wuhan Science and Technology Bureau,China(No.2019020701011478).
文摘The limitations of native collagen,such as thermal stability and solubility in physiological environments,can be improved by applying bioconjugation and synthetic chemistry techniques.However,the exquisite control of the modification site of collagen remains a challenge.In this work,pH-responsive poly(acrylic acid)(PAA)with dif-ferent chain lengths was attached to the N-terminal α-amino groups of succinylated collagen using a site-specific modification strategy.Additionally,the structure,thermal stability,and pH sensitivity of succinylated collagen were explored.The modification rate of amino groups in the succinylated collagen-PAA bioconjugate(SPSC-PAA)was eval-uated by the 2,4,6-trinitrobenzene sulfonic acid assay.The impact of N-terminal modification of PAA and its chain length on the thermal stability of collagen was explored by CD and DSC.These techniques revealed that the ther-mal stability of SPSC-Col is pH-responsive and closely related to the chain length of grafted PAA.The pH sensitivity of SPSC-PAA was further explored by rheology and turbidity.Subsquently,the critical pH and isoelectric point of SPSC-PAAs were also examined by turbidity and isoelectric point titration,respectively.This work provides a new insight into the N-terminal modification of collagen on its properties.
