To investigate how the biofilm three-dimensional(3D) architecture influences in situ pH distribution patterns on the enamel surface. Biofilms were formed on human tooth enamel in the presence of 1% sucrose or 0.5% glu...To investigate how the biofilm three-dimensional(3D) architecture influences in situ pH distribution patterns on the enamel surface. Biofilms were formed on human tooth enamel in the presence of 1% sucrose or 0.5% glucose plus 0.5% fructose. At specific time points, biofilms were exposed to a neutral pH buffer to mimic the buffering of saliva and subsequently pulsed with 1% glucose to induce re-acidification. Simultaneous 3D pH mapping and architecture of intact biofilms was performed using two-photon confocal microscopy. The enamel surface and mineral content characteristics were examined successively via optical profilometry and microradiography analyses. Sucrose-mediated biofilm formation created spatial heterogeneities manifested by complex networks of bacterial clusters(microcolonies). Acidic regions(pH<5.5) were found only in the interior of microcolonies,which impedes rapid neutralization(taking more than 120 min for neutralization). Glucose exposure rapidly re-created the acidic niches, indicating formation of diffusion barriers associated with microcolonies structure. Enamel demineralization(white spots),rougher surface, deeper lesion and more mineral loss appeared to be associated with the localization of these bacterial clusters at the biofilm-enamel interface. Similar 3D architecture was observed in plaque-biofilms formed in vivo in the presence of sucrose. The formation of complex 3D architectures creates spatially heterogeneous acidic microenvironments in close proximity of enamel surface, which might correlate with the localized pattern of the onset of carious lesions(white spot like) on teeth.展开更多
Currently,the renewable energy-driven carbon dioxide reduction reaction(CO_(2)RR)has been identified as a promising carbon neutralization option capable of generating a variety of high-value hydrocarbon products.Impor...Currently,the renewable energy-driven carbon dioxide reduction reaction(CO_(2)RR)has been identified as a promising carbon neutralization option capable of generating a variety of high-value hydrocarbon products.Importantly,high-entropy borides(HEBs),which are similar to high-entropy carbides,have attracted extensive attention because of their outstanding chemical and physical properties,which allow them to be used as potential electrocatalysts,expanding the applications of high-entropy alloy materials.TiCrMnFeMoB is a new class of HEBs derived from Mo_(2)B_(2)MBenes via boro/carbothermal reduction.The electrochemical reduction of nitrate(NO_(3))-integrated CO_(2)to organonitrogen compounds(acetamide and urea)via C-N coupling is attracting increasing attention.This paper outlines a development route and strategy in this area,emphasizing the importance of electrochemical NO_(3)-integrated CO_(2)RR for achieving a carbon-neutral society.C-N coupling proceeds by the interaction between ketene(^(*)CCO)vs.ammonia(NH3)or carbon monoxide(^(*)CO)vs.hydroxylamine(NH_(2)OH)and the K^(+)cation in the acid electrolyte.The^(*)CCO intermediate forms^(*)CC(OH)NH_(2)as a result of the nucleophilic attack by NH3.The K^(+)cation and pH-dependent modulating reaction microenvironments play important roles in the design of high-performance catalysts for C-N bond coupling and C-C bond formation,which is critical for synthesizing valuable C-N chemicals from the CO_(2)RR-integrated NO_(3)reduction reaction(NtrRR).However,this route still faces many challenges in generating crucial intermediates during electrocatalytic C-N coupling.For the first time,we propose a general modeling strategy for K^(+)-induced and pH-dependent microenvironment electroreduction of CO_(2)and NO_(3)to acetamide and urea,respectively,over HEB catalysts under neutral,acidic,and alkaline conditions.Our results identified^(*)CCO and^(*)NH_(2)OH as the key intermediates for acetamide and urea synthesis,respectively,undergoing a nucleophilic reaction.This suggests that C-N coupling can occur via a nucleophilic reaction between^(*)CCO and NH3 to further form acetamide,whereas CO and NH_(2)OH form urea via two C-N coupling steps.This strategy expands the range of products generated from CO_(2)reduction and has been successfully applied to the formation of organonitrogen compounds.展开更多
In osteoporosis scenario, tissue response to implants is greatly impaired by the deteriorated boneregeneration microenvironment. In the present study, a Mg-containing akermanite (Ak) ceramic wasemployed for the treatm...In osteoporosis scenario, tissue response to implants is greatly impaired by the deteriorated boneregeneration microenvironment. In the present study, a Mg-containing akermanite (Ak) ceramic wasemployed for the treatment of osteoporotic bone defect, based on the hypothesis that both beneficialions (e.g. Mg^2+ ect.) released by the implants and the weak alkaline microenvironment pH (μe-pH) itcreated may play distinct roles in recovering the abnormal bone regeneration by stimulating osteoblasticanabolic effects. The performance of Ak, b-tricalcium phosphate (β-TCP) and Hardystone (Har) in healinga 3 mm bone defect on the ovariectomized (OVX) osteoporotic rat model was evaluated. Our resultsindicated that, there's more new bone formed in Ak group than in β-TCP or Har group at week 9. Theinitial me-pHs of Ak were significantly higher than that of the β-TCP and Blank group, and this weakalkaline condition was maintained till at least 9 weeks post-surgery. Increased osteoblastic activity whichwas indicated by higher osteoid secretion was observed in Ak group at week 4 to week 9. An intermediatelayer which was rich in phosphorus minerals and bound directly to the new forming bone wasdeveloped on the surface of Ak. In a summary, our study demonstrates that Ak exhibits a superior boneregenerative performance under osteoporosis condition, and might be a promising candidate for thetreatment of osteoporotic bone defect and fracture.展开更多
基金supported in part by the National Institute for Dental and Craniofacial Research (NIDCR) grants DE025728 (GH),DE18023 (HK) and DE25220 (HK)
文摘To investigate how the biofilm three-dimensional(3D) architecture influences in situ pH distribution patterns on the enamel surface. Biofilms were formed on human tooth enamel in the presence of 1% sucrose or 0.5% glucose plus 0.5% fructose. At specific time points, biofilms were exposed to a neutral pH buffer to mimic the buffering of saliva and subsequently pulsed with 1% glucose to induce re-acidification. Simultaneous 3D pH mapping and architecture of intact biofilms was performed using two-photon confocal microscopy. The enamel surface and mineral content characteristics were examined successively via optical profilometry and microradiography analyses. Sucrose-mediated biofilm formation created spatial heterogeneities manifested by complex networks of bacterial clusters(microcolonies). Acidic regions(pH<5.5) were found only in the interior of microcolonies,which impedes rapid neutralization(taking more than 120 min for neutralization). Glucose exposure rapidly re-created the acidic niches, indicating formation of diffusion barriers associated with microcolonies structure. Enamel demineralization(white spots),rougher surface, deeper lesion and more mineral loss appeared to be associated with the localization of these bacterial clusters at the biofilm-enamel interface. Similar 3D architecture was observed in plaque-biofilms formed in vivo in the presence of sucrose. The formation of complex 3D architectures creates spatially heterogeneous acidic microenvironments in close proximity of enamel surface, which might correlate with the localized pattern of the onset of carious lesions(white spot like) on teeth.
基金supported by the Xinjiang Vocational&Technical College of Communications with Grant no.2023YFSY0036Financial support comes from the funding from the XinJiang Tianshan Talent Projet with Grant no.2022SNGGNT104 from Li Liusupported by the Department of Science and Technology of Sichuan Province with Grant no.2023YFSY0036 from Yingchun Ding.
文摘Currently,the renewable energy-driven carbon dioxide reduction reaction(CO_(2)RR)has been identified as a promising carbon neutralization option capable of generating a variety of high-value hydrocarbon products.Importantly,high-entropy borides(HEBs),which are similar to high-entropy carbides,have attracted extensive attention because of their outstanding chemical and physical properties,which allow them to be used as potential electrocatalysts,expanding the applications of high-entropy alloy materials.TiCrMnFeMoB is a new class of HEBs derived from Mo_(2)B_(2)MBenes via boro/carbothermal reduction.The electrochemical reduction of nitrate(NO_(3))-integrated CO_(2)to organonitrogen compounds(acetamide and urea)via C-N coupling is attracting increasing attention.This paper outlines a development route and strategy in this area,emphasizing the importance of electrochemical NO_(3)-integrated CO_(2)RR for achieving a carbon-neutral society.C-N coupling proceeds by the interaction between ketene(^(*)CCO)vs.ammonia(NH3)or carbon monoxide(^(*)CO)vs.hydroxylamine(NH_(2)OH)and the K^(+)cation in the acid electrolyte.The^(*)CCO intermediate forms^(*)CC(OH)NH_(2)as a result of the nucleophilic attack by NH3.The K^(+)cation and pH-dependent modulating reaction microenvironments play important roles in the design of high-performance catalysts for C-N bond coupling and C-C bond formation,which is critical for synthesizing valuable C-N chemicals from the CO_(2)RR-integrated NO_(3)reduction reaction(NtrRR).However,this route still faces many challenges in generating crucial intermediates during electrocatalytic C-N coupling.For the first time,we propose a general modeling strategy for K^(+)-induced and pH-dependent microenvironment electroreduction of CO_(2)and NO_(3)to acetamide and urea,respectively,over HEB catalysts under neutral,acidic,and alkaline conditions.Our results identified^(*)CCO and^(*)NH_(2)OH as the key intermediates for acetamide and urea synthesis,respectively,undergoing a nucleophilic reaction.This suggests that C-N coupling can occur via a nucleophilic reaction between^(*)CCO and NH3 to further form acetamide,whereas CO and NH_(2)OH form urea via two C-N coupling steps.This strategy expands the range of products generated from CO_(2)reduction and has been successfully applied to the formation of organonitrogen compounds.
基金This work was supported by grants from the National Natural Science Foundation of China(No.51272274,81672227,51372170)Shenzhen Peacock Program(No.110811003586331)Shenzhen Science and Technology Research funding(No.CXZZ 20150401152251209,JSGG20151030140325149,JSGG20150331154931068,CXZZ20140417113430716)and partially from Hong Kong General Research Fund.
文摘In osteoporosis scenario, tissue response to implants is greatly impaired by the deteriorated boneregeneration microenvironment. In the present study, a Mg-containing akermanite (Ak) ceramic wasemployed for the treatment of osteoporotic bone defect, based on the hypothesis that both beneficialions (e.g. Mg^2+ ect.) released by the implants and the weak alkaline microenvironment pH (μe-pH) itcreated may play distinct roles in recovering the abnormal bone regeneration by stimulating osteoblasticanabolic effects. The performance of Ak, b-tricalcium phosphate (β-TCP) and Hardystone (Har) in healinga 3 mm bone defect on the ovariectomized (OVX) osteoporotic rat model was evaluated. Our resultsindicated that, there's more new bone formed in Ak group than in β-TCP or Har group at week 9. Theinitial me-pHs of Ak were significantly higher than that of the β-TCP and Blank group, and this weakalkaline condition was maintained till at least 9 weeks post-surgery. Increased osteoblastic activity whichwas indicated by higher osteoid secretion was observed in Ak group at week 4 to week 9. An intermediatelayer which was rich in phosphorus minerals and bound directly to the new forming bone wasdeveloped on the surface of Ak. In a summary, our study demonstrates that Ak exhibits a superior boneregenerative performance under osteoporosis condition, and might be a promising candidate for thetreatment of osteoporotic bone defect and fracture.
