Photoluminescent hybrid materials containing carboxymethyl cellulose and lanthanide ions（Eu3＋, Tb3＋）were prepared by a facile method under ambient conditions. Lanthanide ions were covalently grafted to the cellulo...Photoluminescent hybrid materials containing carboxymethyl cellulose and lanthanide ions（Eu3＋, Tb3＋）were prepared by a facile method under ambient conditions. Lanthanide ions were covalently grafted to the cellulose framework through coordination with the carboxylic groups of the cellulose. Hybrid materials were fabricated as hydrogel and aerogel. As shown by SEM and pore parameters, aerogel materials which were obtained by supercritical CO2 drying show hierarchical porous structure. The photoluminescence spectrum of the hybrid materials shows the characteristic red emission of Eu3＋ ion and green emission of Tb3＋. Further luminescent investigations reveal that these hybrid materials can detect Fe3＋ with relative selectivity and high sensitivity, which suggests that the hybrid materials could be a promising luminescent probe for selectively sensing Fe3＋ ion.展开更多
Small populations are at risk of extinction from deterministic and stochastic factors.Less than 250 Asian elephants(Elephas maximus)remain in China,and are distributed in a few isolated areas;yet,population viability ...Small populations are at risk of extinction from deterministic and stochastic factors.Less than 250 Asian elephants(Elephas maximus)remain in China,and are distributed in a few isolated areas;yet,population viability analyses of this endangered population have not been conducted.Here,the current genetic status of the Pu’Er-Mengyang Asian elephant populations in China was analyzed,and the risk of extinction was predicted over the next 500 years.Factors affecting the viability of this population were determined through simulations.The genetic diversity of the population was very low(mean allele number:3.1;expected heterozygosity:0.463),even though a recent population bottleneck was not detected.The effective population size was approximately 24.1 adult elephants.Enough adult breeding individuals exist to maintain population viability.VORTEX simulation model showed that this population would not go extinct in the next 500 years.However,illegal poaching and harvesting could negatively affect population size.A sensitivity analysis showed that the mean stochastic growth rate of the study population is sensitive to sex ratio,number of breeding females,mortality of females of different age classes,carrying capacity,and lethal equivalents.Based on our results,we suggest that action should be taken to alleviate inbreeding and any further loss of genetic diversity,by connecting fragmented elephant habitat or by translocating individual elephants.In addition,human–elephant conflict should be mitigated using various modern approaches,including crop guarding techniques,and by encouraging farmers to switch to crops and income sources not vulnerable to elephant raids.展开更多
基金supported by the National Natural Science Foundation of China (Grant No.52005434)the China Scholarship Council (Grant No.202008320145)+1 种基金the China Postdoctoral Science Foundation (Grant No.2023M733151)the Natural Science Foundation of Jiangsu Province (Grant No.BK20190912).
基金Project supported by the National Natural Science Foundation of China(21161023,21661034)
文摘Photoluminescent hybrid materials containing carboxymethyl cellulose and lanthanide ions（Eu3＋, Tb3＋）were prepared by a facile method under ambient conditions. Lanthanide ions were covalently grafted to the cellulose framework through coordination with the carboxylic groups of the cellulose. Hybrid materials were fabricated as hydrogel and aerogel. As shown by SEM and pore parameters, aerogel materials which were obtained by supercritical CO2 drying show hierarchical porous structure. The photoluminescence spectrum of the hybrid materials shows the characteristic red emission of Eu3＋ ion and green emission of Tb3＋. Further luminescent investigations reveal that these hybrid materials can detect Fe3＋ with relative selectivity and high sensitivity, which suggests that the hybrid materials could be a promising luminescent probe for selectively sensing Fe3＋ ion.
基金the National Nature Science Foundation of China[31570408]。
文摘Small populations are at risk of extinction from deterministic and stochastic factors.Less than 250 Asian elephants(Elephas maximus)remain in China,and are distributed in a few isolated areas;yet,population viability analyses of this endangered population have not been conducted.Here,the current genetic status of the Pu’Er-Mengyang Asian elephant populations in China was analyzed,and the risk of extinction was predicted over the next 500 years.Factors affecting the viability of this population were determined through simulations.The genetic diversity of the population was very low(mean allele number:3.1;expected heterozygosity:0.463),even though a recent population bottleneck was not detected.The effective population size was approximately 24.1 adult elephants.Enough adult breeding individuals exist to maintain population viability.VORTEX simulation model showed that this population would not go extinct in the next 500 years.However,illegal poaching and harvesting could negatively affect population size.A sensitivity analysis showed that the mean stochastic growth rate of the study population is sensitive to sex ratio,number of breeding females,mortality of females of different age classes,carrying capacity,and lethal equivalents.Based on our results,we suggest that action should be taken to alleviate inbreeding and any further loss of genetic diversity,by connecting fragmented elephant habitat or by translocating individual elephants.In addition,human–elephant conflict should be mitigated using various modern approaches,including crop guarding techniques,and by encouraging farmers to switch to crops and income sources not vulnerable to elephant raids.
