Four winter wheat (Triticum aestivum L.) varieties ('JD 8', 'Jing 411','Centurk' and 'Tam 202') were used to study the effect of heat stress on photosynthetic characteristics of flag le...Four winter wheat (Triticum aestivum L.) varieties ('JD 8', 'Jing 411','Centurk' and 'Tam 202') were used to study the effect of heat stress on photosynthetic characteristics of flag leaf blade, nag leaf sheath, peduncle, glume, lemma and awn during grain-filling stage. The results showed that heat acclimation during grain-filling stage increased thermotolerance of wheat with significant differences among different green organs. During heat stress, the decreases of the efficiency of primary light energy conversion (F-v/F-m) of PS II and pigment (chlorophyll and carotenoid) content were much slower in peduncle, flag leaf sheath and glume than in nag leaf blade, lemma and ann; and the percentage of decrease in net photosynthetic rate (P-n) of ear was lower than that of the nag leaf blade. The measured photosynthetic parameters (F-v/F-m, P-n and pigment content) of 'JD 8', a relatively heat tolerant variety, declined more slowly than those of the other three varieties during the whole heat stress period.展开更多
Semiconductor oxides are widely used to achieve photocatalytic removal of NOx(NO and NO2) species. These materials also exhibit enhanced oxidation ability in thermally assisted photocatalysis;however, many of them ten...Semiconductor oxides are widely used to achieve photocatalytic removal of NOx(NO and NO2) species. These materials also exhibit enhanced oxidation ability in thermally assisted photocatalysis;however, many of them tend to be deactivated at high relative humidity(RH) levels. In the case of the benchmark P25 TiO2 photocatalyst, we observe a significant decrease in non-NO2 selectivity from 95.02% to 58.33% when RH increases from 20% to 80%. Interestingly, the porous TiO2(B) microspheres synthesized in this work exhibit 99% selectivity at 20% RH;the selectivity remains as high as 96.18% at 80% RH. The high humidity tolerance of the TiO2(B) sample can be ascribed to its strong water desorption capacity and easy O2 adsorption at elevated temperatures, which reflects the fact that the superoxide radical is the main active species for the deep oxidation of NOx. This work may inspire the design of efficient photothermal catalysts with application in NOx removal in hot and humid environments.展开更多
With the development and rising of antimicrobial resistance,rapid and effective killings of bacteria are urgently needed,especially for antibiotic-resistant bacteria and bacterial biofilms that are usually hard to be ...With the development and rising of antimicrobial resistance,rapid and effective killings of bacteria are urgently needed,especially for antibiotic-resistant bacteria and bacterial biofilms that are usually hard to be treated with conventional antibiotics.Here,a rapid and broad-spectrum antibacterial strategy is demonstrated through photothermal ablation with MXene and light.Ti3C2 MXenes,when combined with 808 nm light,show significant antibacterial effects in just 20 min.The antibacterial strategy is effective to 15 bacterial species tested,including methicillin-resistant Staphylococcus aureus(MRSA)and vancomycin-resistant Enterococci(VRE).In addition,the rapid antibacterial strategy works for MRSA biofilms,by damaging the structures as well as killing bacteria in biofilms.Furthermore,the investigation of the antibacterial mechanisms shows that Ti3C2 with light kills bacteria mainly physically through inserting/contact and photothermal effect.This work broadens the potential applications of MXene and provides a way to eradicate bacteria and biofilms physically,without the likelihood of resistance development.展开更多
文摘Four winter wheat (Triticum aestivum L.) varieties ('JD 8', 'Jing 411','Centurk' and 'Tam 202') were used to study the effect of heat stress on photosynthetic characteristics of flag leaf blade, nag leaf sheath, peduncle, glume, lemma and awn during grain-filling stage. The results showed that heat acclimation during grain-filling stage increased thermotolerance of wheat with significant differences among different green organs. During heat stress, the decreases of the efficiency of primary light energy conversion (F-v/F-m) of PS II and pigment (chlorophyll and carotenoid) content were much slower in peduncle, flag leaf sheath and glume than in nag leaf blade, lemma and ann; and the percentage of decrease in net photosynthetic rate (P-n) of ear was lower than that of the nag leaf blade. The measured photosynthetic parameters (F-v/F-m, P-n and pigment content) of 'JD 8', a relatively heat tolerant variety, declined more slowly than those of the other three varieties during the whole heat stress period.
文摘Semiconductor oxides are widely used to achieve photocatalytic removal of NOx(NO and NO2) species. These materials also exhibit enhanced oxidation ability in thermally assisted photocatalysis;however, many of them tend to be deactivated at high relative humidity(RH) levels. In the case of the benchmark P25 TiO2 photocatalyst, we observe a significant decrease in non-NO2 selectivity from 95.02% to 58.33% when RH increases from 20% to 80%. Interestingly, the porous TiO2(B) microspheres synthesized in this work exhibit 99% selectivity at 20% RH;the selectivity remains as high as 96.18% at 80% RH. The high humidity tolerance of the TiO2(B) sample can be ascribed to its strong water desorption capacity and easy O2 adsorption at elevated temperatures, which reflects the fact that the superoxide radical is the main active species for the deep oxidation of NOx. This work may inspire the design of efficient photothermal catalysts with application in NOx removal in hot and humid environments.
基金the National Natural Science Foundation of China(81901790 and 21803006)the Natural Science Foundation of Beijing(7204274)+1 种基金the Fundamental Research Funds for the Central Universitiesthe Interdisciplinary Medicine Seed Fund of Peking University(BMU2017MX015)。
文摘With the development and rising of antimicrobial resistance,rapid and effective killings of bacteria are urgently needed,especially for antibiotic-resistant bacteria and bacterial biofilms that are usually hard to be treated with conventional antibiotics.Here,a rapid and broad-spectrum antibacterial strategy is demonstrated through photothermal ablation with MXene and light.Ti3C2 MXenes,when combined with 808 nm light,show significant antibacterial effects in just 20 min.The antibacterial strategy is effective to 15 bacterial species tested,including methicillin-resistant Staphylococcus aureus(MRSA)and vancomycin-resistant Enterococci(VRE).In addition,the rapid antibacterial strategy works for MRSA biofilms,by damaging the structures as well as killing bacteria in biofilms.Furthermore,the investigation of the antibacterial mechanisms shows that Ti3C2 with light kills bacteria mainly physically through inserting/contact and photothermal effect.This work broadens the potential applications of MXene and provides a way to eradicate bacteria and biofilms physically,without the likelihood of resistance development.
