Currently,simultaneous regulation of external morphology and internal electronic structure for Na_(3)V_(2)(PO_(4))_(3)(NVP)is rarely realized.Herein,complexes of β-cyclodextrin(βCD)and ethylenediaminetetraacetic aci...Currently,simultaneous regulation of external morphology and internal electronic structure for Na_(3)V_(2)(PO_(4))_(3)(NVP)is rarely realized.Herein,complexes of β-cyclodextrin(βCD)and ethylenediaminetetraacetic acid ferric sodium salt(EDTAFeNa)are utilized for the one-step preparation of NVP with spherical morphology as well as Fe substitution.βCD is initially hydrolyzed into glucose,and then carbon microspheres with numerous pores are formed through continuous dehydration and carbonization.The intermediate hydroxymethylfurfural is rich in active functional groups,which are attractive for the V/P-contained raw materials.Accordingly,the nucleation sites for NVP are successfully limited in the spherical framework,possessing a superior surface area of 97.15 g m^(-2).Furthermore,the beneficial Fe in EDTAFeNa enters into the NVP bulk to construct a novel Fe-doped Na_(3)V_(1.95)Fe_(0.05)(PO_(4))_(3)(NVP/β-ISC)material.Fe-substitution induces significant optimizations of electronic structure for NVP,which has been verified by the newly generated abundant oxygen vacancies and extended V-O bond length.Moreover,a multielectron reaction is activated,resulting from the V^(4+)/V^(5+)redox couple.The charge compensation mechanism of NVP/β-ISC is also deeply investigated.Density functional theory(DFT)calculations theoretically elaborate the mechanism of Fe-doping.Consequently,NVP/β-ISC reveals superior sodium storage performance in both half and full cells and even at different extreme conditions(needling,soaking,bending,and freezing).展开更多
Effective lattice oxygen(Olatt)activation at low temperatures has long been a challenge in catalytic oxidation reactions.Traditional thermal catalytic soot combustion,even with Pt/Pd catalysts,is inefficient at exhaus...Effective lattice oxygen(Olatt)activation at low temperatures has long been a challenge in catalytic oxidation reactions.Traditional thermal catalytic soot combustion,even with Pt/Pd catalysts,is inefficient at exhaust temperatures below 200℃,particularly under conditions of frequent idling.Herein,we report an effective strategy utilizing non-thermal plasma(NTP)to activate Olatt in Ce_(1–x)Co_(x)O_(2–δ)catalysts,achieving dramatic enhancement of the soot combustion rate at low temperatures.At 200℃ and 4.3 W(discharge power,P_(dis)),NTP-Ce_(0.8)Co_(0.2)O_(2–δ)achieved 96.9%soot conversion(X_(C)),99.0%CO_(2) selectivity(S(CO_(2)))and a maximum energy conversion efficiency(Emax)of 14.7 g kWh^(–1).Compared with previously reported results,NTP-Ce_(0.8)Co_(0.2)O_(2–δ)exhibits the highest S(CO_(2))and Emax values.Remarkably,even without heating,X_(C),Emax,and S(CO_(2))reached 92.1%,6.1 g kWh–1,and 97.5%,respectively,at 6.3 W(P_(dis)).The results of characterization and theoretical calculation demonstrated that Co dopes into the CeO_(2) crystal lattice and forms an asymmetric Ce–O–Co structure,making oxygen“easy come,easy go”,thereby enabling the rapid combustion of soot over NTP-Ce_(0.8)Co_(0.2)O_(2–δ).This study highlights the great potential of NTP for activating Olatt and provides valuable insights into the design of efficient NTP-adapted catalysts for oxidation reactions.展开更多
Recent studies have revealed the extraordinary performance of zirconium oxide in propane dehydrogenation,which is attributed to the excellent reactivity of the coordinatively unsaturated zirconium sites(Zr_(cus))aroun...Recent studies have revealed the extraordinary performance of zirconium oxide in propane dehydrogenation,which is attributed to the excellent reactivity of the coordinatively unsaturated zirconium sites(Zr_(cus))around the oxygen vacancies.The origin of the enhanced catalytic activity of ZrO_(2)with defective tetrahedral Zr sites was examined by direct comparison with its pristine counterpart in the current study.Electronic-structure analysis revealed that electrons from oxygen removal were localized within vacancies on the defective surface,which directly attacked the C-H bond in propane.The involvement of localized electrons activates the C-H bond via back-donation to the antibonding orbital on the defective surface;conversely,charge is transferred from propane to the pristine surfaces.The barrier for the first C-H bond activation is clearly significantly reduced on the defective surfaces compared to that on the pristine surfaces,which verifies the superior activity of Zr_(cus).Notably,however,the desorption of both propene and hydrogen molecules from Zr_(cus)is more difficult due to strong binding.The calculated turnover frequency(TOF)for propene formation demonstrates that the pristine surfaces exhibit better catalytic performance at lower temperatures,whereas the defective surfaces have a larger TOF at high temperatures.However,the rate-determining step and reaction order on the defective surface differ from those on the pristine surface,which corroborates that the catalysts follow different mechanisms.A further optimization strategy was proposed to address the remaining bottlenecks in propane dehydrogenation on zirconium oxide.展开更多
The conventional cathode processing utilizes a polyvinylidene fluoride/N-methyl-2-pyrrolidone(PVDF/NMP)binder system,which is afflicted by its toxic and mutagenic characteristics,as well as inadequate binding strength...The conventional cathode processing utilizes a polyvinylidene fluoride/N-methyl-2-pyrrolidone(PVDF/NMP)binder system,which is afflicted by its toxic and mutagenic characteristics,as well as inadequate binding strength.Furthermore,the protracted drying rate of NMP results in uneven accumulation and gradient distribution of cathode materials throughout the extended drying process,thereby adversely impacting electron and ion transport as well as the integrity of the interface structure.This study introduces polyethyleneimine(PEI)as an aqueous multifunctional binder,which enhances the adhesion between electrode materials,improves mechanical stability,and reduces material detachment and damage,thereby extending the lifespan of Na_(3)V_(2)(PO_(4))_(3)(NVP).Concurrently,PEI can regulate the particle distribution and structure of electrodes,optimize the porosity and charge transport pathways,and improve the energy density and cycling stability of NVP.Furthermore,PEI exhibits superior thermal stability at elevated temperatures,enhancing the reliability of battery performance in high-temperature environments.Leveraging these advantages,the application of PEI as a binder in this study has the potential to augment the energy density,cycle life,and safety of batteries,thereby offering a novel approach for optimizing sodium-ion batteries(SIBs)and advancing the development of battery technology.展开更多
This study analytically examines the ionization of atoms in strong near-circular laser fields.The classic Keldysh-Rutherford(KR)Coulomb-scattering(CS)model[Phys.Rev.Lett.121123201(2018)]successfully explained the atto...This study analytically examines the ionization of atoms in strong near-circular laser fields.The classic Keldysh-Rutherford(KR)Coulomb-scattering(CS)model[Phys.Rev.Lett.121123201(2018)]successfully explained the attoclock experimental curve for the H atom at lower laser intensities.Here,we develop a semiclassical model that includes the initial conditions related to the quantum properties of tunneling in the KR model at the beginning of the scattering process.This model is able to explain recent attoclock experimental curves over a wider range of laser and atomic parameters.Our results show the importance of system symmetry and quantum effects in attoclock measurements,suggesting the complex role of the Coulomb potential in strong-field ionization.展开更多
In order to maintain the optimal operating temperature of the battery surface and meet the demand for thermal storage technology,battery thermal management system based on phase change materials has attracted increasi...In order to maintain the optimal operating temperature of the battery surface and meet the demand for thermal storage technology,battery thermal management system based on phase change materials has attracted increasing interest.In this work,a kind of core-shell structured microcapsule was synthesized by an in-situ polymerization,where paraffin was used as the core,while methanol was applied to mod-ify the melamine-formaldehyde shell to reduce toxicity and improve thermal stability.Moreover,three different types of heat conductive fillers with the same content of 10 wt.%,i.e.,nano-Al_(2)O_(3),nano-ZnO and carbon nanotubes were added,generating composites.The microcapsules were uniform,and were not affected by the thermal fillers,which were evenly dispersed around.The composite sample with carbon nanotubes(10 wt.%)showed the highest thermal conductivity of 0.50 W/(m K)and latent heat of 139.64 J/g.Furthermore,according to the leakage testing and battery charge/discharge experiments,compared with Al_(2)O_(3)and ZnO,the addition of carbon nanotubes remarkably enhances the heat storage ability as latent heat from 126.98 J/g for the prepared sample with Al_(2)O_(3)and 125.86 J/g for the one with ZnO,then to 139.64 J/g,as well as dissipation performance as a cooling effect by decreasing the sur-face temperature of battery from 2%to 12%of microcapsule,composite sample with carbon nanotubes presents a broad application prospect in battery thermal management system and energy storage field.展开更多
Ni/Si O_2 and bimetallic Ni_xGa/SiO_2 catalysts with different Ni/Ga atomic ratios(x = 10～2) were investigated for the selective hydrogenation of acetylene.It was found that Ni_xGa/SiO_2 showed higher selectivity to ...Ni/Si O_2 and bimetallic Ni_xGa/SiO_2 catalysts with different Ni/Ga atomic ratios(x = 10～2) were investigated for the selective hydrogenation of acetylene.It was found that Ni_xGa/SiO_2 showed higher selectivity to ethylene than Ni/Si O_2.This is attributed to the formation Ni-Ga alloy and Ni3 Ga intermetallic compound(IMC) where there was a charge transfer from Ga to Ni,which is favorable for reducing the adsorption strength and amount of ethylene on Ni atoms.As a result,the over-hydrogenation,the C–C bond hydrogenolysis and the polymerization were suppressed,and subsequently the selectivity to ethylene was enhanced.With the decrease of Ni/Ga atomic ratio,the activity and stability of the Ni_xGa/SiO_2 catalysts increased first and then decreased,while the ethylene selectivity tended to increase.Ni_5 Ga/SiO_2 exhibited the best performance.Under the conditions of 180 °C,0.1 MPa,and a reactant(1.0 vol% acetylene,5.0 vol% H_2 and 94 vol% N_2) with the space velocity of 36,000 m L h^(-1) g^(-1),the acetylene conversion maintained at 100% on Ni_5 Ga/SiO_2 during 120 h time on stream and the selectivity to ethylene was 75%～81%after reaction for 68 h.It was also found that the formation of Ni-Ga alloy and Ni_3 Ga IMC suppressed the incorporation of carbon to form NiCx,subsequently enhancing the catalyst stability.Additionally,with increasing the Ga content,the catalyst acid amount and strength tended to increase,which promoted the polymerization and carbon deposition and so the catalyst deactivation.展开更多
We study high-order harmonic generation(HHG)from multi-center asymmetric linear molecules numerically and analytically.Our simulations show that odd and even HHG spectra of the asymmetric multi-center system respond d...We study high-order harmonic generation(HHG)from multi-center asymmetric linear molecules numerically and analytically.Our simulations show that odd and even HHG spectra of the asymmetric multi-center system respond differently to the change of the molecular structure.Specifically,when the internuclear distances between these nuclei of the molecule have a small change,the odd spectra usually do not change basically,but the even spectra differ remarkably.Based on this phenomenon,a simple procedure is proposed to probe the positions of these nuclei with odd–even HHG.Our results shed light on attosecond probing of the structure of multi-center molecules using HHG.展开更多
Base editors of the Cas9 system have been widely used for precise nucleotide substitution in crops. In this study, Cas12a was applied to construct plant cytosine base editors(CBEs). The main elements of Cas12aCBEs wer...Base editors of the Cas9 system have been widely used for precise nucleotide substitution in crops. In this study, Cas12a was applied to construct plant cytosine base editors(CBEs). The main elements of Cas12aCBEs were engineered and their efficiency was evaluated in stably transformed rice cells. An optimized ttCas12a-hyA3Bctd editor, consisting of a LbCas12a variant carrying catalytic inactive D832A and temperature-tolerance D156R double mutations, a truncated human APOBEC3B deaminase, a human RAD51 single-stranded DNA-binding domain, and double copies of UGI, outperformed other Cas12aCBEs in base editing efficiency. In T0transgenic rice plants, ttCas12a-hyA3Bctd edited an average of42.01% and a maximum of 68.75% of lines at six genomic targets. A-to-G conversions were generated in rice by an adenine base editor with a similar architecture to the optimized CBE. Our results provide preliminary evidence for the feasibility of robust and efficient plant Cas12a base editing systems, which could be useful for precise crop breeding.展开更多
BACKGROUND: Recent findings on emergency department (ED) patient experience surveys and concerns for the low response rates challenge the quality and reliability of the survey reports. We assessed the consistency of a...BACKGROUND: Recent findings on emergency department (ED) patient experience surveys and concerns for the low response rates challenge the quality and reliability of the survey reports. We assessed the consistency of an ED patient experience survey report and identifi ed the effects of patient demographics on ED patient experiences. METHODS: We conducted a prospective, cross-sectional study at a university-based ED from July to December 2017. We obtained ED patient experience scores from an institutional version (IS) survey and the Press Ganey Associates-distributed survey (PGA). We compared top box scores from the two reports using frequency analysis and performed multivariable logistic regressions to identify associations between IS patient demographics and scores. RESULTS: We obtained 289 PGA and 234 IS responses. The IS reported signifi cant, higher top box scores in doctor-specifi c patient questions compared to PGA (all four P-values < 0.01). Female, Christian and White patients were more likely to give top box scores (OR 3.07, OR 2.22 and OR 2.41, P-value < 0.05, respectively). CONCLUSION: We found significant differences in ED patient experience scores between the IS and PGA surveys. We recommend that healthcare providers consider patient demographic variables when interpreting ED experience score reports. Multiple survey techniques and distribution methods may be adopted to best capture ED patient experiences.展开更多
To measure and control the electron motion in atoms and molecules by the strong laser field on the attosecond time scale is one of the research frontiers of atomic and molecular photophysics. It involves many new phen...To measure and control the electron motion in atoms and molecules by the strong laser field on the attosecond time scale is one of the research frontiers of atomic and molecular photophysics. It involves many new phenomena and processes and raises a series of questions of concepts, theories, and methods. Recent studies show that the Coulomb potential can cause the ionization time lag(about 100 attoseconds) between instants of the field maximum and the ionization-rate maximum. This lag can be understood as the response time of the electronic wave function to the strong-field-induced ionization event. It has a profound influence on the subsequent ultrafast dynamics of the ionized electron and can significantly change the time–frequency properties of electron trajectory(an important theoretical tool for attosecond measurement). Here, the research progress of response time and its implications on attosecond measurement are briefly introduced.展开更多
基金financially supported by the Key Research and Development(R&D)Projects of Shanxi Province(202202040201005)the Graduate Innovation Project of Shanxi Province(No.2024SJ261)。
文摘Currently,simultaneous regulation of external morphology and internal electronic structure for Na_(3)V_(2)(PO_(4))_(3)(NVP)is rarely realized.Herein,complexes of β-cyclodextrin(βCD)and ethylenediaminetetraacetic acid ferric sodium salt(EDTAFeNa)are utilized for the one-step preparation of NVP with spherical morphology as well as Fe substitution.βCD is initially hydrolyzed into glucose,and then carbon microspheres with numerous pores are formed through continuous dehydration and carbonization.The intermediate hydroxymethylfurfural is rich in active functional groups,which are attractive for the V/P-contained raw materials.Accordingly,the nucleation sites for NVP are successfully limited in the spherical framework,possessing a superior surface area of 97.15 g m^(-2).Furthermore,the beneficial Fe in EDTAFeNa enters into the NVP bulk to construct a novel Fe-doped Na_(3)V_(1.95)Fe_(0.05)(PO_(4))_(3)(NVP/β-ISC)material.Fe-substitution induces significant optimizations of electronic structure for NVP,which has been verified by the newly generated abundant oxygen vacancies and extended V-O bond length.Moreover,a multielectron reaction is activated,resulting from the V^(4+)/V^(5+)redox couple.The charge compensation mechanism of NVP/β-ISC is also deeply investigated.Density functional theory(DFT)calculations theoretically elaborate the mechanism of Fe-doping.Consequently,NVP/β-ISC reveals superior sodium storage performance in both half and full cells and even at different extreme conditions(needling,soaking,bending,and freezing).
文摘Effective lattice oxygen(Olatt)activation at low temperatures has long been a challenge in catalytic oxidation reactions.Traditional thermal catalytic soot combustion,even with Pt/Pd catalysts,is inefficient at exhaust temperatures below 200℃,particularly under conditions of frequent idling.Herein,we report an effective strategy utilizing non-thermal plasma(NTP)to activate Olatt in Ce_(1–x)Co_(x)O_(2–δ)catalysts,achieving dramatic enhancement of the soot combustion rate at low temperatures.At 200℃ and 4.3 W(discharge power,P_(dis)),NTP-Ce_(0.8)Co_(0.2)O_(2–δ)achieved 96.9%soot conversion(X_(C)),99.0%CO_(2) selectivity(S(CO_(2)))and a maximum energy conversion efficiency(Emax)of 14.7 g kWh^(–1).Compared with previously reported results,NTP-Ce_(0.8)Co_(0.2)O_(2–δ)exhibits the highest S(CO_(2))and Emax values.Remarkably,even without heating,X_(C),Emax,and S(CO_(2))reached 92.1%,6.1 g kWh–1,and 97.5%,respectively,at 6.3 W(P_(dis)).The results of characterization and theoretical calculation demonstrated that Co dopes into the CeO_(2) crystal lattice and forms an asymmetric Ce–O–Co structure,making oxygen“easy come,easy go”,thereby enabling the rapid combustion of soot over NTP-Ce_(0.8)Co_(0.2)O_(2–δ).This study highlights the great potential of NTP for activating Olatt and provides valuable insights into the design of efficient NTP-adapted catalysts for oxidation reactions.
文摘Recent studies have revealed the extraordinary performance of zirconium oxide in propane dehydrogenation,which is attributed to the excellent reactivity of the coordinatively unsaturated zirconium sites(Zr_(cus))around the oxygen vacancies.The origin of the enhanced catalytic activity of ZrO_(2)with defective tetrahedral Zr sites was examined by direct comparison with its pristine counterpart in the current study.Electronic-structure analysis revealed that electrons from oxygen removal were localized within vacancies on the defective surface,which directly attacked the C-H bond in propane.The involvement of localized electrons activates the C-H bond via back-donation to the antibonding orbital on the defective surface;conversely,charge is transferred from propane to the pristine surfaces.The barrier for the first C-H bond activation is clearly significantly reduced on the defective surfaces compared to that on the pristine surfaces,which verifies the superior activity of Zr_(cus).Notably,however,the desorption of both propene and hydrogen molecules from Zr_(cus)is more difficult due to strong binding.The calculated turnover frequency(TOF)for propene formation demonstrates that the pristine surfaces exhibit better catalytic performance at lower temperatures,whereas the defective surfaces have a larger TOF at high temperatures.However,the rate-determining step and reaction order on the defective surface differ from those on the pristine surface,which corroborates that the catalysts follow different mechanisms.A further optimization strategy was proposed to address the remaining bottlenecks in propane dehydrogenation on zirconium oxide.
基金financially supported by the National Natural Science Foundation of China(12202410,51906238 and 52202051)Key Research and Development(R&D)Projects of Shanxi Province(202202040201005)+7 种基金Natural Science Foundation of Shanxi Province(202303021211145)Project funded by China Postdoctoral Science Foundation(2023T160734 and 2023M733935)Natural Science Foundation of Hunan Province(2023JJ40726)supported by the Research Project Supported by Shanxi Scholarship Council of China(2022-139)Fund Program for the Scientific Activities of Selected Returned Overseas Professionals in Shanxi Province(20220012)Changsha Municipal Natural Science Foundation(kq2208277)Opening Foundation of Key Laboratory in North University of China(DXMBJJ2023-03)Graduate Innovation Project of Shanxi Province(2023SJ230)。
文摘The conventional cathode processing utilizes a polyvinylidene fluoride/N-methyl-2-pyrrolidone(PVDF/NMP)binder system,which is afflicted by its toxic and mutagenic characteristics,as well as inadequate binding strength.Furthermore,the protracted drying rate of NMP results in uneven accumulation and gradient distribution of cathode materials throughout the extended drying process,thereby adversely impacting electron and ion transport as well as the integrity of the interface structure.This study introduces polyethyleneimine(PEI)as an aqueous multifunctional binder,which enhances the adhesion between electrode materials,improves mechanical stability,and reduces material detachment and damage,thereby extending the lifespan of Na_(3)V_(2)(PO_(4))_(3)(NVP).Concurrently,PEI can regulate the particle distribution and structure of electrodes,optimize the porosity and charge transport pathways,and improve the energy density and cycling stability of NVP.Furthermore,PEI exhibits superior thermal stability at elevated temperatures,enhancing the reliability of battery performance in high-temperature environments.Leveraging these advantages,the application of PEI as a binder in this study has the potential to augment the energy density,cycle life,and safety of batteries,thereby offering a novel approach for optimizing sodium-ion batteries(SIBs)and advancing the development of battery technology.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12174239,12347165,and 12404330)Shaanxi Fundamental Science Research Project for Mathematics and Physics(Grant No.23JSY022)+2 种基金Natural Science Basic Research Program of Shaanxi(Grant No.2022JM-015)Hebei Natural Science Foundation(Grant No.A2022205002)Science and Technology Project of Hebei Education Department(Grant No.QN2022143)。
文摘This study analytically examines the ionization of atoms in strong near-circular laser fields.The classic Keldysh-Rutherford(KR)Coulomb-scattering(CS)model[Phys.Rev.Lett.121123201(2018)]successfully explained the attoclock experimental curve for the H atom at lower laser intensities.Here,we develop a semiclassical model that includes the initial conditions related to the quantum properties of tunneling in the KR model at the beginning of the scattering process.This model is able to explain recent attoclock experimental curves over a wider range of laser and atomic parameters.Our results show the importance of system symmetry and quantum effects in attoclock measurements,suggesting the complex role of the Coulomb potential in strong-field ionization.
基金supported by the National Natural Science Foundation of China(Nos.12202410 and 51906238)the China Postdoctoral Science Foundation(No.2023M733935)+4 种基金the Natural Science Foundation of Hunan Province(No.2023JJ40726)the Research Project Supported by the Shanxi Scholarship Council of China(No.2022-139)the Natural Science Foundation of Shanxi Province(Nos.20210302123017 and 2023recipient Changcheng Liu)the Fund Program for the Scientific Activities of Selected Returned Overseas Professionals in Shanxi Province(No.20220012)the Changsha Municipal Natural Science Foundation(No.kq2208277).
文摘In order to maintain the optimal operating temperature of the battery surface and meet the demand for thermal storage technology,battery thermal management system based on phase change materials has attracted increasing interest.In this work,a kind of core-shell structured microcapsule was synthesized by an in-situ polymerization,where paraffin was used as the core,while methanol was applied to mod-ify the melamine-formaldehyde shell to reduce toxicity and improve thermal stability.Moreover,three different types of heat conductive fillers with the same content of 10 wt.%,i.e.,nano-Al_(2)O_(3),nano-ZnO and carbon nanotubes were added,generating composites.The microcapsules were uniform,and were not affected by the thermal fillers,which were evenly dispersed around.The composite sample with carbon nanotubes(10 wt.%)showed the highest thermal conductivity of 0.50 W/(m K)and latent heat of 139.64 J/g.Furthermore,according to the leakage testing and battery charge/discharge experiments,compared with Al_(2)O_(3)and ZnO,the addition of carbon nanotubes remarkably enhances the heat storage ability as latent heat from 126.98 J/g for the prepared sample with Al_(2)O_(3)and 125.86 J/g for the one with ZnO,then to 139.64 J/g,as well as dissipation performance as a cooling effect by decreasing the sur-face temperature of battery from 2%to 12%of microcapsule,composite sample with carbon nanotubes presents a broad application prospect in battery thermal management system and energy storage field.
基金supported by the National Natural Science Foundation of China (21576193)
文摘Ni/Si O_2 and bimetallic Ni_xGa/SiO_2 catalysts with different Ni/Ga atomic ratios(x = 10～2) were investigated for the selective hydrogenation of acetylene.It was found that Ni_xGa/SiO_2 showed higher selectivity to ethylene than Ni/Si O_2.This is attributed to the formation Ni-Ga alloy and Ni3 Ga intermetallic compound(IMC) where there was a charge transfer from Ga to Ni,which is favorable for reducing the adsorption strength and amount of ethylene on Ni atoms.As a result,the over-hydrogenation,the C–C bond hydrogenolysis and the polymerization were suppressed,and subsequently the selectivity to ethylene was enhanced.With the decrease of Ni/Ga atomic ratio,the activity and stability of the Ni_xGa/SiO_2 catalysts increased first and then decreased,while the ethylene selectivity tended to increase.Ni_5 Ga/SiO_2 exhibited the best performance.Under the conditions of 180 °C,0.1 MPa,and a reactant(1.0 vol% acetylene,5.0 vol% H_2 and 94 vol% N_2) with the space velocity of 36,000 m L h^(-1) g^(-1),the acetylene conversion maintained at 100% on Ni_5 Ga/SiO_2 during 120 h time on stream and the selectivity to ethylene was 75%～81%after reaction for 68 h.It was also found that the formation of Ni-Ga alloy and Ni_3 Ga IMC suppressed the incorporation of carbon to form NiCx,subsequently enhancing the catalyst stability.Additionally,with increasing the Ga content,the catalyst acid amount and strength tended to increase,which promoted the polymerization and carbon deposition and so the catalyst deactivation.
基金Project supported by the National Natural Science Foundation of China(Grants No.91750111)the Youth Foundation of Hebei Province Education Department,China(Grant No.QN2017028)+2 种基金the Fundamental Research Funds for Hebei GEO University,China(Grant No.BQ2017047)the Natural Science Foundation of Hebei Province,China(Grant No.A2015205161)the Fundamental Research Funds for the Central Universities,China(Grant No.SNNU.GK201801009)
文摘We study high-order harmonic generation(HHG)from multi-center asymmetric linear molecules numerically and analytically.Our simulations show that odd and even HHG spectra of the asymmetric multi-center system respond differently to the change of the molecular structure.Specifically,when the internuclear distances between these nuclei of the molecule have a small change,the odd spectra usually do not change basically,but the even spectra differ remarkably.Based on this phenomenon,a simple procedure is proposed to probe the positions of these nuclei with odd–even HHG.Our results shed light on attosecond probing of the structure of multi-center molecules using HHG.
基金funded by the National Natural Science Foundation of China (U19A2022 and 32000284)the Natural Science Foundation of Anhui Province (2208085Y11, 2108085Y07,2008085QC101, and 2008085MC71)+2 种基金the University Synergy Innovation Program of Anhui Province (GXXT-2021-056)Open Research Fund Program of Anhui Province Key Laboratory of Rice Genetics and Breeding (SDKF-2021-01 and SDKF-2022-04)Natural Science Research Project for Anhui Universities(KJ2021A0196)。
文摘Base editors of the Cas9 system have been widely used for precise nucleotide substitution in crops. In this study, Cas12a was applied to construct plant cytosine base editors(CBEs). The main elements of Cas12aCBEs were engineered and their efficiency was evaluated in stably transformed rice cells. An optimized ttCas12a-hyA3Bctd editor, consisting of a LbCas12a variant carrying catalytic inactive D832A and temperature-tolerance D156R double mutations, a truncated human APOBEC3B deaminase, a human RAD51 single-stranded DNA-binding domain, and double copies of UGI, outperformed other Cas12aCBEs in base editing efficiency. In T0transgenic rice plants, ttCas12a-hyA3Bctd edited an average of42.01% and a maximum of 68.75% of lines at six genomic targets. A-to-G conversions were generated in rice by an adenine base editor with a similar architecture to the optimized CBE. Our results provide preliminary evidence for the feasibility of robust and efficient plant Cas12a base editing systems, which could be useful for precise crop breeding.
基金supported by the Undergraduate Research Opportunities Program Faculty Advisory Board at the University of California,Irvinepartially by the National Center for Advancing Translational Sciences,National Institutes of Health(NIH),through the Biostatistics,Epidemiology and Research Design Unit [grant number:UL1 TR001414]
文摘BACKGROUND: Recent findings on emergency department (ED) patient experience surveys and concerns for the low response rates challenge the quality and reliability of the survey reports. We assessed the consistency of an ED patient experience survey report and identifi ed the effects of patient demographics on ED patient experiences. METHODS: We conducted a prospective, cross-sectional study at a university-based ED from July to December 2017. We obtained ED patient experience scores from an institutional version (IS) survey and the Press Ganey Associates-distributed survey (PGA). We compared top box scores from the two reports using frequency analysis and performed multivariable logistic regressions to identify associations between IS patient demographics and scores. RESULTS: We obtained 289 PGA and 234 IS responses. The IS reported signifi cant, higher top box scores in doctor-specifi c patient questions compared to PGA (all four P-values < 0.01). Female, Christian and White patients were more likely to give top box scores (OR 3.07, OR 2.22 and OR 2.41, P-value < 0.05, respectively). CONCLUSION: We found significant differences in ED patient experience scores between the IS and PGA surveys. We recommend that healthcare providers consider patient demographic variables when interpreting ED experience score reports. Multiple survey techniques and distribution methods may be adopted to best capture ED patient experiences.
基金Project supported by the National Natural Science Foundation of China(Grant No.91750111)the National Key Research and Development Program of China(Grant No.2018YFB0504400)。
文摘To measure and control the electron motion in atoms and molecules by the strong laser field on the attosecond time scale is one of the research frontiers of atomic and molecular photophysics. It involves many new phenomena and processes and raises a series of questions of concepts, theories, and methods. Recent studies show that the Coulomb potential can cause the ionization time lag(about 100 attoseconds) between instants of the field maximum and the ionization-rate maximum. This lag can be understood as the response time of the electronic wave function to the strong-field-induced ionization event. It has a profound influence on the subsequent ultrafast dynamics of the ionized electron and can significantly change the time–frequency properties of electron trajectory(an important theoretical tool for attosecond measurement). Here, the research progress of response time and its implications on attosecond measurement are briefly introduced.
