The energy dissipation mechanism of energetic materials（EMs） is very important for keeping safety. We choose nitrobenzene as a model of EM and employ transient absorption（TA） spectroscopy and time-resolved coheren...The energy dissipation mechanism of energetic materials（EMs） is very important for keeping safety. We choose nitrobenzene as a model of EM and employ transient absorption（TA） spectroscopy and time-resolved coherent anti-stokes Raman scattering（CARS） to clarify its energy dissipation mechanism. The TA data confirms that the excited nitrobenzene spends about 16 ps finishing the twist intramolecular charge transfer from benzene to nitro group, and dissipates its energy through the rapid vibration relaxation in the initial excited state. And then the dynamics of vibrational modes（VMs） in the ground state of nitrobenzene, which are located at 682 cm^-1（v1）, 854 cm^-1（v2）, 1006 cm^-1（v3）, and 1023 cm^-1（v4）,is scanned by CARS. It exhibits that the excess energy of nitrobenzene on the ground state would further dissipate through intramolecular vibrational redistribution based on the vibrational cooling of vi and v2 modes, v1 and v4 modes, and v3 and v4 modes. Moreover, the vibration-vibration coupling depends not only on the energy levels of VMs, but also on the spatial position of chemical bonds relative to the VM.展开更多
The carrier behavior in CuInS_2 thin films at femtosecond and microsecond time scales is discussed in detail. Transient absorption data suggests that the photo-generated carriers relax rapidly accompanied by a change ...The carrier behavior in CuInS_2 thin films at femtosecond and microsecond time scales is discussed in detail. Transient absorption data suggests that the photo-generated carriers relax rapidly accompanied by a change in energy. The photogenerated charge carriers are extracted by a bias electric field E in the nanosecond transient photocurrent system. An applied E improves the efficiency of photon conversion to charge carriers and enhances the velocity of the extracted charge carriers. In addition, there exists a threshold of illumination intensity in the extraction process of charge carriers in the CuInS_2 thin film, above which carrier recombination occurs. The corresponding loss further increases with illumination intensity and the recombination rate is almost independent of E. Our results provide useful insights into the characteristics of carriers in the CuInS_2 thin film and are important for the operation of optoelectronic devices realized with these films.展开更多
The photoluminescence （PL） characteristics of ZnCuInS quantum dots （Q, Ds） with varying ZnS shell thicknesses of O, 0.5, and 1.5 layers are investigated systemically by time-correlated single-photon counting measu...The photoluminescence （PL） characteristics of ZnCuInS quantum dots （Q, Ds） with varying ZnS shell thicknesses of O, 0.5, and 1.5 layers are investigated systemically by time-correlated single-photon counting measurements and temperature-dependent PL measurements. The results show that a ZnS shell thickness of 1.5 layers can effectively improve the PL quantum yield in one order of magnitude by depressing the surface trapping states of the core ZnCuInS QDs at room temperature. However, the PL measurements at the elevated temperature reveal that the core-shell nanocrystals remain temperature-sensitive with respect to their relatively thin shells. The temperature sensitivity of these small-sized single-layered core-shell nanocrystals may find applications as effective thermometers for the in vivo detection of biological reactions within cells.展开更多
The optical properties of three linear conjugated oligomers （F-P, F-P-F, and P-F-P-F-P）, where phenothiazine （P） and fluorene （F） groups arrange alternately, are investigated. With the enhancement of the π-conj...The optical properties of three linear conjugated oligomers （F-P, F-P-F, and P-F-P-F-P）, where phenothiazine （P） and fluorene （F） groups arrange alternately, are investigated. With the enhancement of the π-conjugated system, their absorption and emission bands both gradually red shift, and their two-photon properties are also improved. Meanwhile, their fluorescence dynamic traces are analyzed with continuous rate distribution model, exhibiting that their decay rates gradually accelerate and the rate distribution width become narrower. The quantum chemical calculation offers their molecular structures and transition mechanism, showing that the enhancement of π-conjugated system should be responsible for tile improvement of two-photon properties.展开更多
Background:The dry bulb of Fritillaria thunbergii Miq.is a traditional Chinese medicine,and is the leading product of the geo-authentic crude drugs‘Zhebawei’in Zhejiang Province.Fritillaria thunbergii requires more ...Background:The dry bulb of Fritillaria thunbergii Miq.is a traditional Chinese medicine,and is the leading product of the geo-authentic crude drugs‘Zhebawei’in Zhejiang Province.Fritillaria thunbergii requires more potassium(K)than nitrogen and phosphorus,while the response of F.thunbergii to K has rarely been studied.Objective and Methods:To evaluate the K nutritional status of F.thunbergii,a 2-year field experiment was conducted under six K application rates(0,40,80,120,160,and 200 kg K_(2)O ha−1)with two F.thunbergii cultivars(ZB1,narrow-leaf;ZB2,broad-leaf).Results:The bulbus Fritillariae Thunbergii(BFT)yield increased to a plateau with more than~120 kg K_(2)O ha-1.The BFT quality met the standard of Pharmacopoeia of P.R.China with more than 40.0 kg K_(2)O ha^(-1).Leaf K concentration was significantly correlated with BFT yield,and was more sensitive to K application rate as compared to those of stems and flowers.Potassium application extended the duration of rapid leaf-biomass accumulation and increased the accumulation rate.Two cultivars had similar response patterns to K application,but ZB2 had higher K partial productivity,leaf-biomass,and leaf K concentration than ZB1.Conclusion:108.4-128.0 kg K_(2)O ha^(-1) was the optimal K application range for BFT yield.The potassium nutrition index(KNI)model established based on leaf K concentration has biological significance and can be used for dynamic diagnosis of K nutritional status of F.thunbergii with both accuracy and simplicity.展开更多
Carbon dots(CDs)with solvatochromic emission colors in different solvents have attracted much attention as a new class of luminescent nanomaterial owing to their facile synthesis and low production cost.In this work,w...Carbon dots(CDs)with solvatochromic emission colors in different solvents have attracted much attention as a new class of luminescent nanomaterial owing to their facile synthesis and low production cost.In this work,we prepared two kinds of CDs with solvatochromic emissions:green emission CDs(G-CDs)and multicolor emission CDs(M-CDs).G-CDs synthesized from o-phenylenediamine exhibited weak photoluminescence emission(quantum yield 2.8%-6.1%)and 39 nm solvatochromic shifts(492-531 nm).In contrast,M-CDs prepared from o-phenylenediamine and 4-aminophenol showed 87 nm solvatochromic shift range(505-592 nm)and much higher photoluminescence quantum yield(18.4%-32.5%).The two CDs exhibited different emission,absorption,and photoluminescence lifetime.The origin of solvatochromic shifts and the formation mechanism of CDs were demonstrated by analyzing the structures and compositions of two CDs.High percentages of pyrrolic nitrogen and amino nitrogen make wider solvatochromic shifts and higher quantum yields.The results were well supported by density functional theory calculations.This effective strategy to expand solvatochromic shift range and improve quantum yields could open a new window to prepare satisfied solvatochromic carbon dots.展开更多
The abuse of conventional antibiotics leads to increasing bacterial resistance.Nanozyme is a new kind of ultra-efficient and safe nanomaterial with intrinsic enzyme-like activities,showing remarkable potential as a ne...The abuse of conventional antibiotics leads to increasing bacterial resistance.Nanozyme is a new kind of ultra-efficient and safe nanomaterial with intrinsic enzyme-like activities,showing remarkable potential as a next generation nanobactericide.Graphdiyne(GDY)is a burgeoning two-dimensional(2D)carbon allotrope with intriguing physicochemical properties,holding a great promise as a metal-free nanozyme.In this study,a boron doped GDY nanosheet(B-GDY)was constructed to simulate the performance of peroxidase(POD).By promoting the decomposition of H_(2)O_(2) to produce reactive oxygen species(ROS),the bactericidal efficacies against both Gram-positive and Gram-negative bacteria were substantially enhanced attributed to the extremely high catalytic activity of B-GDY.In-depth density functional theory(DFT)calculations illuminate that doping of boron can introduce more active B-defect sites as well as lower Gibbs free energy during the H_(2)O_(2) decomposition reaction.Notably,B-GDY contributes to significant wound healing and excellent biocompatibility,reducing the biological burden.The design of this nanozyme opens a new avenue for the development of alternative antibiotics.展开更多
In recent years, metal halide perovskite nanocrystals (NCs) have been favored by manyresearchers due to their unique properties including long carrier diffusion length, highcarrier mobility, tunable emission wavelengt...In recent years, metal halide perovskite nanocrystals (NCs) have been favored by manyresearchers due to their unique properties including long carrier diffusion length, highcarrier mobility, tunable emission wavelength, and narrow full width at half maximum,making them great application potentials in optoelectronic devices. The photoluminescencequantum yields of perovskite NCs are nearly 100%, and the device efficiencyof perovskite NC-based light-emitting diodes (LEDs) has been improvedsignificantly from below 0.1% to over 20%. In addition, perovskite NC-based solarcells and photodetectors have also developed rapidly in recent years. Here, we summarizethe synthesis and the basic optoelectronic properties of metal halide perovskiteNCs and introduce their applications in LEDs, solar cells, and photodetectors.展开更多
Dear Editor,Embryonic stem cells(ESCs)have been assumed to possess immature mitochondria and to favor anaerobic glycolysis over oxidative phosphorylation(OXPHOS)for energy production.This proposition is largely based ...Dear Editor,Embryonic stem cells(ESCs)have been assumed to possess immature mitochondria and to favor anaerobic glycolysis over oxidative phosphorylation(OXPHOS)for energy production.This proposition is largely based on the findings that ESCs possess globular mitochondria with blurred cristae,and the facts that ESCs have higher glycolysis activity and lower mitochondrial respiration capacity than somatic cells(Kondoh et al.,2007;Folmes et al.,2011,2012;Zhang et al.,2012;Xu et al.,2013;Ito and Suda,2014;Gu et al.,2016).However,recent studies have shown that mitochondrial autophagy and mitochondrial dynamics are pivotal for ESC self-renewal and pluripotency(Todd et al.,2010;Liu et al.,2016,2020;Wang et al.,2019;Zhong et al.,2019).These studies have raised a fundamental question:what is the contribution and functional mechanism of mitochondrial respiration in pluripotency regulation?展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.21573094,11274142,11474131,11574112,and 51502109)the National Found for Fostering Talents of Basic Science,China(Grant No.J1103202)+1 种基金the Science Challenging Program(Grant No.JCKY2016212A501)China Scholarship Council(CSC) during a visit of Ning Sui(Grant No.201706175038) to MPIA is also acknowledged
文摘The energy dissipation mechanism of energetic materials（EMs） is very important for keeping safety. We choose nitrobenzene as a model of EM and employ transient absorption（TA） spectroscopy and time-resolved coherent anti-stokes Raman scattering（CARS） to clarify its energy dissipation mechanism. The TA data confirms that the excited nitrobenzene spends about 16 ps finishing the twist intramolecular charge transfer from benzene to nitro group, and dissipates its energy through the rapid vibration relaxation in the initial excited state. And then the dynamics of vibrational modes（VMs） in the ground state of nitrobenzene, which are located at 682 cm^-1（v1）, 854 cm^-1（v2）, 1006 cm^-1（v3）, and 1023 cm^-1（v4）,is scanned by CARS. It exhibits that the excess energy of nitrobenzene on the ground state would further dissipate through intramolecular vibrational redistribution based on the vibrational cooling of vi and v2 modes, v1 and v4 modes, and v3 and v4 modes. Moreover, the vibration-vibration coupling depends not only on the energy levels of VMs, but also on the spatial position of chemical bonds relative to the VM.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.21573094,51502109,11774122,11574112,and 11474131)the National Found for Fostering Talents of Basic Science,China(Grant No.J1103202)the China Scholarship Council(CSC)obtained during the visit of Ning Sui to MPIA(Grant No.201706175038)
文摘The carrier behavior in CuInS_2 thin films at femtosecond and microsecond time scales is discussed in detail. Transient absorption data suggests that the photo-generated carriers relax rapidly accompanied by a change in energy. The photogenerated charge carriers are extracted by a bias electric field E in the nanosecond transient photocurrent system. An applied E improves the efficiency of photon conversion to charge carriers and enhances the velocity of the extracted charge carriers. In addition, there exists a threshold of illumination intensity in the extraction process of charge carriers in the CuInS_2 thin film, above which carrier recombination occurs. The corresponding loss further increases with illumination intensity and the recombination rate is almost independent of E. Our results provide useful insights into the characteristics of carriers in the CuInS_2 thin film and are important for the operation of optoelectronic devices realized with these films.
基金Supported by the National Natural Science Foundation of China under Grant Nos 21573094,11274142,11474131 and 51502109the China Postdoctoral Science Foundation Funded Project under Grant Nos 2011M500927 and 2013T60319
文摘The photoluminescence （PL） characteristics of ZnCuInS quantum dots （Q, Ds） with varying ZnS shell thicknesses of O, 0.5, and 1.5 layers are investigated systemically by time-correlated single-photon counting measurements and temperature-dependent PL measurements. The results show that a ZnS shell thickness of 1.5 layers can effectively improve the PL quantum yield in one order of magnitude by depressing the surface trapping states of the core ZnCuInS QDs at room temperature. However, the PL measurements at the elevated temperature reveal that the core-shell nanocrystals remain temperature-sensitive with respect to their relatively thin shells. The temperature sensitivity of these small-sized single-layered core-shell nanocrystals may find applications as effective thermometers for the in vivo detection of biological reactions within cells.
基金ACKNOWLEDGMENTS This work was supported by the National Natural Science Foundation of China. （No.21103161. No.11274142, No.11304058, No.11274034. and No.11004080） and the China Postdoctoral Science Foundation （No.2011MS00927 and No.2013T60319）.
文摘The optical properties of three linear conjugated oligomers （F-P, F-P-F, and P-F-P-F-P）, where phenothiazine （P） and fluorene （F） groups arrange alternately, are investigated. With the enhancement of the π-conjugated system, their absorption and emission bands both gradually red shift, and their two-photon properties are also improved. Meanwhile, their fluorescence dynamic traces are analyzed with continuous rate distribution model, exhibiting that their decay rates gradually accelerate and the rate distribution width become narrower. The quantum chemical calculation offers their molecular structures and transition mechanism, showing that the enhancement of π-conjugated system should be responsible for tile improvement of two-photon properties.
文摘Background:The dry bulb of Fritillaria thunbergii Miq.is a traditional Chinese medicine,and is the leading product of the geo-authentic crude drugs‘Zhebawei’in Zhejiang Province.Fritillaria thunbergii requires more potassium(K)than nitrogen and phosphorus,while the response of F.thunbergii to K has rarely been studied.Objective and Methods:To evaluate the K nutritional status of F.thunbergii,a 2-year field experiment was conducted under six K application rates(0,40,80,120,160,and 200 kg K_(2)O ha−1)with two F.thunbergii cultivars(ZB1,narrow-leaf;ZB2,broad-leaf).Results:The bulbus Fritillariae Thunbergii(BFT)yield increased to a plateau with more than~120 kg K_(2)O ha-1.The BFT quality met the standard of Pharmacopoeia of P.R.China with more than 40.0 kg K_(2)O ha^(-1).Leaf K concentration was significantly correlated with BFT yield,and was more sensitive to K application rate as compared to those of stems and flowers.Potassium application extended the duration of rapid leaf-biomass accumulation and increased the accumulation rate.Two cultivars had similar response patterns to K application,but ZB2 had higher K partial productivity,leaf-biomass,and leaf K concentration than ZB1.Conclusion:108.4-128.0 kg K_(2)O ha^(-1) was the optimal K application range for BFT yield.The potassium nutrition index(KNI)model established based on leaf K concentration has biological significance and can be used for dynamic diagnosis of K nutritional status of F.thunbergii with both accuracy and simplicity.
基金We appreciate the financial supports from the Board or Regent Supporting Fund(BORSF)Endowed Professorshipthe Lousiana State University Shreveport(LSUS)R&D Funds+1 种基金the Qingdao Municipal Science and Technology Commission(No.16-5-1-86-jch)the Scientific Research Foundation of Qingdao University of Science and Technology(QUST)(No.210/010022914).
文摘Carbon dots(CDs)with solvatochromic emission colors in different solvents have attracted much attention as a new class of luminescent nanomaterial owing to their facile synthesis and low production cost.In this work,we prepared two kinds of CDs with solvatochromic emissions:green emission CDs(G-CDs)and multicolor emission CDs(M-CDs).G-CDs synthesized from o-phenylenediamine exhibited weak photoluminescence emission(quantum yield 2.8%-6.1%)and 39 nm solvatochromic shifts(492-531 nm).In contrast,M-CDs prepared from o-phenylenediamine and 4-aminophenol showed 87 nm solvatochromic shift range(505-592 nm)and much higher photoluminescence quantum yield(18.4%-32.5%).The two CDs exhibited different emission,absorption,and photoluminescence lifetime.The origin of solvatochromic shifts and the formation mechanism of CDs were demonstrated by analyzing the structures and compositions of two CDs.High percentages of pyrrolic nitrogen and amino nitrogen make wider solvatochromic shifts and higher quantum yields.The results were well supported by density functional theory calculations.This effective strategy to expand solvatochromic shift range and improve quantum yields could open a new window to prepare satisfied solvatochromic carbon dots.
基金supported by the National Natural Science Foundation of China(Nos.31800800,21790052,and 21501106)Natural Science Foundation of Shandong Province China(Nos.ZR2019BC101 and ZR2020MB026).
文摘The abuse of conventional antibiotics leads to increasing bacterial resistance.Nanozyme is a new kind of ultra-efficient and safe nanomaterial with intrinsic enzyme-like activities,showing remarkable potential as a next generation nanobactericide.Graphdiyne(GDY)is a burgeoning two-dimensional(2D)carbon allotrope with intriguing physicochemical properties,holding a great promise as a metal-free nanozyme.In this study,a boron doped GDY nanosheet(B-GDY)was constructed to simulate the performance of peroxidase(POD).By promoting the decomposition of H_(2)O_(2) to produce reactive oxygen species(ROS),the bactericidal efficacies against both Gram-positive and Gram-negative bacteria were substantially enhanced attributed to the extremely high catalytic activity of B-GDY.In-depth density functional theory(DFT)calculations illuminate that doping of boron can introduce more active B-defect sites as well as lower Gibbs free energy during the H_(2)O_(2) decomposition reaction.Notably,B-GDY contributes to significant wound healing and excellent biocompatibility,reducing the biological burden.The design of this nanozyme opens a new avenue for the development of alternative antibiotics.
基金The authors gratefully acknowledge financial supports from the Natural Science Foundation of China(61722504,61675086,and 51772123)the National Key Research and Development Program of China(2017YFB0403601)+1 种基金Science and Technology Development Program of Jilin Province,China(20190101016JH)the Special Project of the Province-University Co-constructing Program of Jilin University(SXGJXX2017-3).
文摘In recent years, metal halide perovskite nanocrystals (NCs) have been favored by manyresearchers due to their unique properties including long carrier diffusion length, highcarrier mobility, tunable emission wavelength, and narrow full width at half maximum,making them great application potentials in optoelectronic devices. The photoluminescencequantum yields of perovskite NCs are nearly 100%, and the device efficiencyof perovskite NC-based light-emitting diodes (LEDs) has been improvedsignificantly from below 0.1% to over 20%. In addition, perovskite NC-based solarcells and photodetectors have also developed rapidly in recent years. Here, we summarizethe synthesis and the basic optoelectronic properties of metal halide perovskiteNCs and introduce their applications in LEDs, solar cells, and photodetectors.
基金We thank Dr Masaru Okabe at Osaka University Japan for providing the B6D2-Tg(CAG/Su9-DsRed2,Acr3-EGFP)RBGS002Osb mice(mito-red)the National Institute for Basic Biology Japan for providing the B6.Cg-Tg(CAG-GFP/LC3)53Nmz/NmzRbrc mice.+3 种基金the National Key R&D Program of China 2018YFA0108402the Strategic Priority Research Program of the Chinese Academy of Sciences XDA16030302the Strategic Collaborative Research Program of the Ferring Institute of Reproductive Medicine Grant No.33,and the National Natural Science Foundation of China Program(31720103907,31570995,31621004),to T.Z.and(31400831)to J.C.The raw data FASTQ files for the RNA sequencing data are deposited in NCBI GEO,GEO:GSE140712(Fig.1D,1E and S4)and ScienceDB,China National Standard GB/T 7714-2015(Fig.S8A,S8F and S8G)The metabolomic data files are deposited in ScienceDB,China National Standard GB/T 7714-2015.
文摘Dear Editor,Embryonic stem cells(ESCs)have been assumed to possess immature mitochondria and to favor anaerobic glycolysis over oxidative phosphorylation(OXPHOS)for energy production.This proposition is largely based on the findings that ESCs possess globular mitochondria with blurred cristae,and the facts that ESCs have higher glycolysis activity and lower mitochondrial respiration capacity than somatic cells(Kondoh et al.,2007;Folmes et al.,2011,2012;Zhang et al.,2012;Xu et al.,2013;Ito and Suda,2014;Gu et al.,2016).However,recent studies have shown that mitochondrial autophagy and mitochondrial dynamics are pivotal for ESC self-renewal and pluripotency(Todd et al.,2010;Liu et al.,2016,2020;Wang et al.,2019;Zhong et al.,2019).These studies have raised a fundamental question:what is the contribution and functional mechanism of mitochondrial respiration in pluripotency regulation?
