查看更多>>摘要：This study investigates the long-term performance of laboratory dam concrete in different curing envi-ronments over ten years and the microstructure of 17-year-old laboratory concrete and actual concrete cores drilled from the Three Gorges Dam.The mechanical properties of the laboratory dam concrete,whether cured in natural or standard environments,continued to improve over time.Furthermore,the laboratory dam concrete exhibited good resistance to diffusion and a refined microstructure after 17 years.However,curing and long-term exposure to the local natural environment reduced the frost resis-tance.Microstructural analyses of the laboratory concrete samples demonstrated that moderate-heat cement and fine fly ash(FA)particles were almost fully hydrated to form compact microstructures con-sisting of large quantities of homogeneous calcium(alumino)silicate hydrate(C-(A)-S-H)gels and a few crystals.No obvious interfacial transition zones were observed in the microstructure owing to the long-term pozzolanic reaction.This dense and homogenous microstructure was the crucial reason for the excellent long-term performance of the dam concrete.A high FA volume also played a significant role in the microstructural densification and performance growth of dam concrete at a later age.The concrete drilled from the dam surface exhibited a loose microstructure with higher microporosity,indicating that concrete directly exposed to the actual service environment suffered degradation caused by water and wind attacks.In this study,both macro-performance and microstructural analyses revealed that the application of moderate-heat cement and FA resulted in a dense and homogenous microstructure,which ensured the excellent long-term performance of concrete from the Three Gorges Dam after 17 years.Long-term exposure to an actual service environment may lead to microstructural degradation of the concrete surface.Therefore,the retained long-term dam concrete samples need to be further researched to better understand its microstructural evolution and development of its properties.
查看更多>>摘要：CO2 is one of the most important greenhouse gases(GHGs)in the earth's atmosphere.Since the industrial era,anthropogenic activities have emitted excessive quantities of GHGs into the atmosphere,resulting in climate warming since the 1950s and leading to an increased frequency of extreme weather and climate events.In 2020,China committed to striving for carbon neutrality by 2060.This commitment and China's consequent actions will result in significant changes in global and regional anthropogenic carbon emis-sions and therefore require timely,comprehensive,and objective monitoring and verification support(MVS)systems.The MVS approach relies on the top-down assimilation and inversion of atmospheric CO2 concentrations,as recommended by the Intergovernmental Panel on Climate Change(IPCC)Inventory Guidelines in 2019.However,the regional high-resolution assimilation and inversion method is still in its initial stage of development.Here,we have constructed an inverse system for carbon sources and sinks at the kilometer level by coupling proper orthogonal decomposition(POD)with four-dimensional variational(4DVar)data assimilation based on the weather research and forecasting-green-house gas(WRF-GHG)model.Our China Carbon Monitoring and Verification Support at the Regional level(CCMVS-R)system can continuously assimilate information on atmospheric CO2 and other related infor-mation and realize the inversion of regional and local anthropogenic carbon emissions and natural ter-restrial ecosystem carbon exchange.Atmospheric CO2 data were collected from six ground-based monitoring sites in Shanxi Province,China to verify the inversion effect of regional anthropogenic carbon emissions by setting ideal and real experiments using a two-layer nesting method(at 27 and 9 km).The uncertainty of the simulated atmospheric CO2 decreased significantly,with a root-mean-square error of CO2 concentration values between the ideal value and the simulated after assimilation was close to 0.The total anthropogenic carbon emissions in Shanxi Province in 2019 from the assimilated inversions were approximately 28.6％(17％-38％)higher than the mean of five emission inventories using the bottom-up method,showing that the top-down CCMVS-R system can obtain more comprehensive information on anthropogenic carbon emissions.
查看更多>>摘要：Copper is a microelement with important physiological functions in the body.However,the excess cop-per ion(Cu2+)may cause severe health problems,such as hair cell apoptosis and the resultant hearing loss.Therefore,the assay of Cu2+is important.We integrate ionic imprinting technology(IIT)and struc-turally colored hydrogel beads to prepare chitosan-based ionically imprinted hydrogel beads(IIHBs)as a low-cost and high-specificity platform for Cu2+detection.The IIHBs have a macroporous microstructure,uniform size,vivid structural color,and magnetic responsiveness.When incubated in solution,IIHBs rec-ognize Cu2+and exhibit a reflective peak change,thereby achieving label-free detection.In addition,bene-fiting from the IIT,the IIHBs display good specificity and selectivity and have an imprinting factor of 19.14 at 100 μmol·L-1.These features indicated that the developed IIHBs are promising candidates for Cu2+detection,particularly for the prevention of hearing loss.
查看更多>>摘要：Skeletal muscle has a robust regeneration ability that is impaired by severe injury,disease,and aging,resulting in a decline in skeletal muscle function.Therefore,improving skeletal muscle regeneration is a key challenge in treating skeletal muscle-related disorders.Owing to their significant role in tissue regeneration,implantation of M2 macrophages(M2Mo)has great potential for improving skeletal muscle regeneration.Here,we present a short-wave infrared(SWIR)fluorescence imaging technique to obtain more in vivo information for an in-depth evaluation of the skeletal muscle regeneration effect after M2Mo transplantation.SWIR fluorescence imaging was employed to track implanted M2Mo in the injured skeletal muscle of mouse models.It is found that the implanted M2Me accumulated at the injury site for two weeks.Then,SWIR fluorescence imaging of blood vessels showed that M2Mø implantation could improve the relative perfusion ratio on day 5(1.09±0.09 vs 0.85±0.05;p=0.01)and day 9(1.38±0.16 vs 0.95±0.03;p=0.01)post-injury,as well as augment the degree of skeletal muscle regen-eration on day 13 post-injury.Finally,multiple linear regression analyses determined that post-injury time and relative perfusion ratio could be used as predictive indicators to evaluate skeletal muscle regen-eration.These results provide more in vivo details about M2Mo in skeletal muscle regeneration and con-firm that M2Mø could promote angiogenesis and improve the degree of skeletal muscle repair,which will guide the research and development of M2Mo implantation to improve skeletal muscle regeneration.
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