It has been reported that Arabidopsis chloroplast accD transcripts undergo RNA editing and that loss of accD-C794 RNA editing does not affect plant growth under normal conditions.To date,the exact biological role of a...It has been reported that Arabidopsis chloroplast accD transcripts undergo RNA editing and that loss of accD-C794 RNA editing does not affect plant growth under normal conditions.To date,the exact biological role of accD-C794 editing has remained elusive.Here,we reveal an unexpected role for accD-C794 editing in response to heat stress.Loss of accD-C794 editing results in a yellow and dwarf phenotype with decreased chloroplast gene expression under heat stress,and artificial improvement of C794-edited accD gene expression enhances heat tolerance in Arabidopsis.These data suggest that accD-C794 editing confers heat tolerance in planta.We also found that treatment with the product of acetyl coenzyme A carboxylase(ACCase)could allay mutant phenotypic characteristics and showed that a mutation in the CAC3 gene for the a-subunit of ACCase was associated with dwarfism under heat stress.These observations indicate that defective accD-C794 editing may be intrinsic to reduced ACCase activity,thereby contributing to heat sensitivity.ACCase catalyzes the committed step of de novo fatty acid(FA)biosynthesis.FA content analysis revealed that unsaturated oleic(C18:1)and linoleic acids(C18:2)were low in the accD-C794 editing-defective mutant but high in the C794-edited accD-overexpressing plants compared with the wild type.Supplying exogenous C18:1 and C18:2 could rescue the mutant phenotype,suggesting that these FAs play an essential role in tolerance to heat stress.Transmission electron microscopy observations showed that heat stress seriously affected the membrane architecture in accD editing-defective mutants but not in accD-overexpressing plants.These results provide the first evidence that accD-C794 editing regulates FA biosynthesis for maintenance of membrane structural homeostasis under heat stress.展开更多
Europium-doped graphitic carbon nitride was synthesized by an easy method and characterized by X-ray diffraction （XRD）, ultraviolet-visible diffuse reflection spectroscopy （UV-Vis DRS）, Fourier transform infrared ...Europium-doped graphitic carbon nitride was synthesized by an easy method and characterized by X-ray diffraction （XRD）, ultraviolet-visible diffuse reflection spectroscopy （UV-Vis DRS）, Fourier transform infrared spectroscopy （FTIR）, photolu- minescence spectra （PL） and transmission electron microscopy （TEM）. The effect of dopant concentration on the rate of photocata- lytic degradation was investigated through degrading methylene blue aqueous solution. The results indicated that the europium-doped samples all possessed increased photocatalytic activity and the optimal europium content was 0.38 wt.%. Moreover, a possible photo- catalytic mechanism for the europium-doped graphitic carbon nitride was proposed.展开更多
The effect of neodymium stearate （NdSt） synthesized by saponification method on thermal degradation and thermo-oxidative degradation of expoxidized natural rubber with 25 mol.% epoxidation （ENR25） was investigated...The effect of neodymium stearate （NdSt） synthesized by saponification method on thermal degradation and thermo-oxidative degradation of expoxidized natural rubber with 25 mol.% epoxidation （ENR25） was investigated by thermogravimetric analysis （TGA）, and the structure of ENR25 vulcanized with NdSt after thermo-oxidative decomposition was characterized using Fourier transform infared spectroscopy-attenuated total-reflectance （FTIR-ATR）. The thermal degradation kinetic parameters of ENR25 with different loadings of NdSt were determined by Coats-Redfern method. The results showed that the thermal degradation of ENR25 in nitrogen was a one-step reaction regardless of NdSt content, whereas the thermo-oxidative degradation was a multiple-step reaction. The thermal and thermo-oxidative stability of the ENR25 vulcanizates with the addition of NdSt was higher than that of pure ENR25 vulcanizates. The ENR25 vulcanizates with the incorporation of 1 phr （per hundred parts of rubber） NdSt imparted the highest activa- tion energy （E） of thermal and thermo-oxidative degradation. This could be attributed to the many unoccupied orbits in rare earth Nd, which could capture the free radicals and make the epoxide groups stable in the process of thermal and thermo-oxidative degradation for ENR25.展开更多
Cubic YAG：Yb3＋, Ho3＋ pure phase nanocrystals were synthesized by using coprecipition nitrate and ammonium hydrogen carbonate as raw materials.After calcining the precipitates at 800 °C, the resultant YAG：Yb3...Cubic YAG：Yb3＋, Ho3＋ pure phase nanocrystals were synthesized by using coprecipition nitrate and ammonium hydrogen carbonate as raw materials.After calcining the precipitates at 800 °C, the resultant YAG：Yb3＋, Ho3＋ nanocrystals were nearly spheric and the particle size was about 40 nm.Intense upconversion spectra were observed on the powder compact pumped by a 980 nm continuous wave diode laser, and green emission centered at 549 nm, red emission centered at 667 nm, and NIR centered at 760 nm were all due to two photons process, which originated from 5S2（5F4）→5I8, 5F5→5I8, and 5S2（5F4）→5I7 transitions, respectively.展开更多
The corrosion resistance and magnetostriction of （Tb0.3Dy0.7）Fe2 alloy were investigated for different nitrogen doses of 5Х 1015, 5Х 1016, 5Х 1017, 1 Х 1018 ions/cm2 and average ion energy of 140 kV. The phase a...The corrosion resistance and magnetostriction of （Tb0.3Dy0.7）Fe2 alloy were investigated for different nitrogen doses of 5Х 1015, 5Х 1016, 5Х 1017, 1 Х 1018 ions/cm2 and average ion energy of 140 kV. The phase and elements concentration in the implanted layer were examined by X-ray diffraction and auger electron spectroscopy, respectively. The aqueous corrosion studies were carried out in 3.5% NaC1 solutions. It was found that corrosion resistance had improved substantially with respect to the untreated substrates. The corrosion resistance was maximum at a dose of 5x1017 ions/cm2, and saturation in corrosion improvement was noticed at a higher dose, 10~ 1017 ions/cm2. In contrast, the results of magnetostriction tests before and after ion implantation showed that the influence of ni- trogen ion implantation on the magnetostrictive properties turned out to be small. Finally, a model was applied to interpret the influ- ence of nitrogen implantation on the magnetostriction in the light of the information provided by the experimental results in this study.展开更多
基金supported by the National Natural Science Foundation of China(91317312 and 31900387)the Natural Science Foundation of Hunan Province(2020JJ4037 and 2021JJ40243).
文摘It has been reported that Arabidopsis chloroplast accD transcripts undergo RNA editing and that loss of accD-C794 RNA editing does not affect plant growth under normal conditions.To date,the exact biological role of accD-C794 editing has remained elusive.Here,we reveal an unexpected role for accD-C794 editing in response to heat stress.Loss of accD-C794 editing results in a yellow and dwarf phenotype with decreased chloroplast gene expression under heat stress,and artificial improvement of C794-edited accD gene expression enhances heat tolerance in Arabidopsis.These data suggest that accD-C794 editing confers heat tolerance in planta.We also found that treatment with the product of acetyl coenzyme A carboxylase(ACCase)could allay mutant phenotypic characteristics and showed that a mutation in the CAC3 gene for the a-subunit of ACCase was associated with dwarfism under heat stress.These observations indicate that defective accD-C794 editing may be intrinsic to reduced ACCase activity,thereby contributing to heat sensitivity.ACCase catalyzes the committed step of de novo fatty acid(FA)biosynthesis.FA content analysis revealed that unsaturated oleic(C18:1)and linoleic acids(C18:2)were low in the accD-C794 editing-defective mutant but high in the C794-edited accD-overexpressing plants compared with the wild type.Supplying exogenous C18:1 and C18:2 could rescue the mutant phenotype,suggesting that these FAs play an essential role in tolerance to heat stress.Transmission electron microscopy observations showed that heat stress seriously affected the membrane architecture in accD editing-defective mutants but not in accD-overexpressing plants.These results provide the first evidence that accD-C794 editing regulates FA biosynthesis for maintenance of membrane structural homeostasis under heat stress.
基金supported by National Natural Science Foundation of China(20801023)the Fundamental Research Funds for the Central Universities(51208024)
文摘Europium-doped graphitic carbon nitride was synthesized by an easy method and characterized by X-ray diffraction （XRD）, ultraviolet-visible diffuse reflection spectroscopy （UV-Vis DRS）, Fourier transform infrared spectroscopy （FTIR）, photolu- minescence spectra （PL） and transmission electron microscopy （TEM）. The effect of dopant concentration on the rate of photocata- lytic degradation was investigated through degrading methylene blue aqueous solution. The results indicated that the europium-doped samples all possessed increased photocatalytic activity and the optimal europium content was 0.38 wt.%. Moreover, a possible photo- catalytic mechanism for the europium-doped graphitic carbon nitride was proposed.
基金supported by National Program on Key Basic Research Project of China(973Program,2010CB635109)Ministry of Science and Technology R&D Research Institutes(2008EG134285)supported by the Fundamental Research Funds for Rubber Research Institute,CATAS(1630022013021,1630022012013)
文摘The effect of neodymium stearate （NdSt） synthesized by saponification method on thermal degradation and thermo-oxidative degradation of expoxidized natural rubber with 25 mol.% epoxidation （ENR25） was investigated by thermogravimetric analysis （TGA）, and the structure of ENR25 vulcanized with NdSt after thermo-oxidative decomposition was characterized using Fourier transform infared spectroscopy-attenuated total-reflectance （FTIR-ATR）. The thermal degradation kinetic parameters of ENR25 with different loadings of NdSt were determined by Coats-Redfern method. The results showed that the thermal degradation of ENR25 in nitrogen was a one-step reaction regardless of NdSt content, whereas the thermo-oxidative degradation was a multiple-step reaction. The thermal and thermo-oxidative stability of the ENR25 vulcanizates with the addition of NdSt was higher than that of pure ENR25 vulcanizates. The ENR25 vulcanizates with the incorporation of 1 phr （per hundred parts of rubber） NdSt imparted the highest activa- tion energy （E） of thermal and thermo-oxidative degradation. This could be attributed to the many unoccupied orbits in rare earth Nd, which could capture the free radicals and make the epoxide groups stable in the process of thermal and thermo-oxidative degradation for ENR25.
基金supported by the National Natural Science Foundation of China (50372075)Shanghai Light-Tech Project (036105021)Singapore AStar SERC (052 101 0039)
文摘Cubic YAG：Yb3＋, Ho3＋ pure phase nanocrystals were synthesized by using coprecipition nitrate and ammonium hydrogen carbonate as raw materials.After calcining the precipitates at 800 °C, the resultant YAG：Yb3＋, Ho3＋ nanocrystals were nearly spheric and the particle size was about 40 nm.Intense upconversion spectra were observed on the powder compact pumped by a 980 nm continuous wave diode laser, and green emission centered at 549 nm, red emission centered at 667 nm, and NIR centered at 760 nm were all due to two photons process, which originated from 5S2（5F4）→5I8, 5F5→5I8, and 5S2（5F4）→5I7 transitions, respectively.
基金supported by the National High Technology Research and Development Program of China(863 program,2011AA03A404)the National Natural Science Foundation of China(50801006)
文摘The corrosion resistance and magnetostriction of （Tb0.3Dy0.7）Fe2 alloy were investigated for different nitrogen doses of 5Х 1015, 5Х 1016, 5Х 1017, 1 Х 1018 ions/cm2 and average ion energy of 140 kV. The phase and elements concentration in the implanted layer were examined by X-ray diffraction and auger electron spectroscopy, respectively. The aqueous corrosion studies were carried out in 3.5% NaC1 solutions. It was found that corrosion resistance had improved substantially with respect to the untreated substrates. The corrosion resistance was maximum at a dose of 5x1017 ions/cm2, and saturation in corrosion improvement was noticed at a higher dose, 10~ 1017 ions/cm2. In contrast, the results of magnetostriction tests before and after ion implantation showed that the influence of ni- trogen ion implantation on the magnetostrictive properties turned out to be small. Finally, a model was applied to interpret the influ- ence of nitrogen implantation on the magnetostriction in the light of the information provided by the experimental results in this study.
