The mechanism of lightning that ignites a forest fire and the lightning that occurs above a forest fire are explained at the molecular level. It is based on two phenomena, namely, internal charge separation inside the...The mechanism of lightning that ignites a forest fire and the lightning that occurs above a forest fire are explained at the molecular level. It is based on two phenomena, namely, internal charge separation inside the atmospheric cloud particles and the existence of a layer of positively charged hydrogen atoms sticking out of the surface of the liquid layer of water on the surface of rimers. Strong turbulence-driven collisions of the ice particles and water droplets with the rimers give rise to breakups of the ice particles and water droplets into positively and negatively charged fragments leading to charge separation. Hot weather in a forest contributes to the updraft of hot and humid air, which follows the same physical/chemical processes of normal lightning proposed and explained recently[1]. Lightning would have a high probability of lighting up and burning the dry biological materials in the ground of the forest, leading to a forest (wild) fire. The burning of trees and other plants would release a lot of heat and moisture together with a lot of smoke particles (aerosols) becoming a strong updraft. The condition for creating lightning is again satisfied which would result in further lightning high above the forest wild fire.展开更多
Cloud electrification is one of the oldest unresolved puzzles in the atmospheric sciences. Though many mechanisms for charge separation in clouds have been proposed, a quantitative understanding of their respective co...Cloud electrification is one of the oldest unresolved puzzles in the atmospheric sciences. Though many mechanisms for charge separation in clouds have been proposed, a quantitative understanding of their respective contribution in a given meteorological situation is lacking. Here we suggest and analyze a hitherto little discussed process. A qualitative picture at the molecular level of the charge separation mechanism of lightning in a thundercloud is proposed. It is based on two key physical/chemical natural phenomena, namely, internal charge separation of the atmospheric impurities/aerosols inside an atmospheric water cluster/droplet/ice particle and the existence of liquid water layers on rimers (graupels and hailstones) forming a layer of dipoles with H<sup>+</sup> pointing out from the air-water interface. Charge separation is achieved through strong collisions among ice particles and water droplets with the rimers in the turbulence of the thundercloud. This work would have significant contribution to cloud electrification and lightning formation.展开更多
Photocatalytic CO_(2)reduction reaction(CO_(2)RR)is one of the promising strategies for sustainably producing solar fuels.The precise identification of catalytic sites and the enhancement of photocatalytic CO_(2)conve...Photocatalytic CO_(2)reduction reaction(CO_(2)RR)is one of the promising strategies for sustainably producing solar fuels.The precise identification of catalytic sites and the enhancement of photocatalytic CO_(2)conversion is imperative yet quite challenging.This critical review summarizes recent advances in porous photo-responsive polymers,including covalent organic frameworks(COFs),covalent triazine frameworks(CTFs),and conjugated microporous polymers(CMPs),those can be rationally designed from the molecular level for visible-light-driven photocatalytic CO_(2)reduction.Additionally,special emphasis is placed on how the well-defined active sites on these polymers can influence their properties and photocatalytic performance.The precise regulation and control of microenvironments and electronic properties of metal active centers are crucial for boosting catalytic efficiency and selectivity,as well as for the design of better photocatalysts for CO_(2)reduction.展开更多
A series of core-expanded naphthalene diimides（NDI-DTYM） and thiophene-based derivatives（1a-c）were designed and synthesized to investigate the relationship between molecular structures and the highest occupied mol...A series of core-expanded naphthalene diimides（NDI-DTYM） and thiophene-based derivatives（1a-c）were designed and synthesized to investigate the relationship between molecular structures and the highest occupied molecular orbital（HOMO） energy levels but has little impact on the lowest unoccupied molecular orbital（LUMO） energy levels.The results demonstrated that increasing the number of thiophene units can gradually elevate the HOMO energy levels but had little impact on the LUMO energy levels.The n-channel organic field-effect transistors（OFETs） based on 1b and 1c have demonstrated that these almost unchanged LUMO energy levels are proper to transport electrons.展开更多
Nanomedicine has made great progress in the targeted therapy of cancer. Here, we established a novel drug-mate strategy by studying the formulation of nanodrugs at the molecular level. In the drug-mate combination, th...Nanomedicine has made great progress in the targeted therapy of cancer. Here, we established a novel drug-mate strategy by studying the formulation of nanodrugs at the molecular level. In the drug-mate combination, the drug is a hydrophobic drug that is poorly soluble in water, and the mate is an amphiphilic small molecule (SMA) that has both hydrophilic and lipophilic properties. We proposed that the hydrophobic drug could co-assemble with a suitable SMA on a nanoscale without additive agents. The proof-ofconcept methodology and results were presented to support our hypothesis. We selected five hydrophobic drugs and more than ten amphiphilic small molecules to construct a library. Through molecular dynamic simulation and quantum chemistry computation,we speculated that the formation of nanoassemblies was related to the binding energy of the drug-mate, and the drug-mate interaction must overcome drug-drug interaction.Furthermore, the obtained SF/VECOONa nanoassemblieswas selected as a model, which had an ultra-high drug loading content (46%), improved pharmacokinetics, increased bioavailability, and enhanced therapeutic efficacy. In summary, the drug-mate strategy is an essential resource to design exact SMA for many hydrophobic drugs and provides a reference for the design of a carrier-free drug delivery system.展开更多
滨海湿地生态系统是重要的生态系统之一,对环境变化响应敏感。海平面变化会直接影响滨海湿地的物质来源,进而影响湿地生态系统演化。然而,由于可靠地质记录的相对稀缺,长时间尺度海平面变化对滨海湿地生态系统的影响尚未全面澄清。本文...滨海湿地生态系统是重要的生态系统之一,对环境变化响应敏感。海平面变化会直接影响滨海湿地的物质来源,进而影响湿地生态系统演化。然而,由于可靠地质记录的相对稀缺,长时间尺度海平面变化对滨海湿地生态系统的影响尚未全面澄清。本文旨在从沉积物有机分子组成视角探讨末次盛冰期(约22000 a BP)以来渤海西岸海平面变化对滨海湿地生态系统演化的影响。本文基于超高分辨率傅里叶变换离子回旋共振质谱(FT-ICR MS)技术分析了渤海西岸沉积物有机分子组成,结果表明末次盛冰期沉积物内源脂肪族化合物占比较高,在海平面较现代海平面平均低约130 m,在渤海西岸滨海湿地不发育情境下该区可能存在局部水系并发育湖沼环境。进入全新世,海平面快速上升,本文岩心的两个海相地层记录了约7100~6900 a BP和约6000~5650 a BP两次海侵事件;约5650 a BP以后,海平面相对稳定但缓慢下降,海岸线逐渐后退,形成了6道古海岸线和6期潟湖洼地。本研究表明滨海沉积物有机质CHO组分对海平面变化引起的环境变迁响应灵敏,有机质H/C和O/C的变化趋势指示滨海湿地在约8050~4850 a BP经历了陆相—海相—陆相的环境转变。其中约8050 a BP和约4850 a BP较高的O/C和较低的H/C表明这两个时期渤海西岸可能发育潟湖洼地,有机质主要来自陆生、半水生植物及土壤微生物活动;约5700 a BP内源脂肪族化合物占比明显较高,表明滨海湿地转变为海洋环境,有机质主要来源转变为水生藻类和浮游生物。约1350 a BP内源有机组分占比15.68%,显著高于约8050 a BP和约4850 a BP,表明湿地生态演化可能受到较强人类活动的干扰。本文的研究结果为认识海平面变化对滨海湿地生态系统演化的影响提供了新的视角和证据。展开更多
The potential energy curve of the CD（X2∏） radical is obtained using the coupled-cluster singles-doublesapproximate-triples [CCSD（T）] theory in combination with the correlation-consistent quintuple basis set augme...The potential energy curve of the CD（X2∏） radical is obtained using the coupled-cluster singles-doublesapproximate-triples [CCSD（T）] theory in combination with the correlation-consistent quintuple basis set augmented with diffuse functions, aug-cc-pV5Z. The potential energy curve is fitted to the Murrell-Sorbie function, which is used to determine the spectroscopic parameters. The obtained Do, De, Re, ωe, ωeXe, αe and Be values are 3.4971 eV, 3.6261 eV, 0.11197 nm, 2097.661 cm^-1, 34.6963 cm^-1, 0.2083 cm^-1 and 7.7962 cm^-1, respectively, which conform almost perfectly to the available measurements. With the potential obtained at the UCCSD（T）/aug-cc-pV5Z level of theory, a total of 24 vibrational states have been predicted for the first time when J = 0 by solving the radial Schrodinger equation of nuclear motion. The complete vibrational levels, the classical turning points, the inertial rotation constants and centrifugal distortion constants are reproduced from the CD（X2∏） potential when J = 0, and are in excellent agreement with the available measurements. The total and the various partial-wave cross sections are calculated for the elastic collisions between the ground-state C and D atoms at energies from 1.0×10^-11 to 1.0 × 10^-4 a.u. when the two atoms approach each other along the CD（X2∏） potential energy curve. Only one shape resonance is found in the total elastic cross sections, and the resonant energy is 8.36×10^-6 a.u. The results show that the shape of the total elastic cross section is mainly dominated by the s partial wave at very low temperatures. Because of the weak shape resonances coming from higher partial waves, most of them are passed into oblivion by the strong total elastic cross sections.展开更多
In scanning tunneling microscopy-induced luminescence(STML),the photon count is measured to reflect single-molecule properties,e.g.,the first molecular excited state.The energy of the first excited state is typically ...In scanning tunneling microscopy-induced luminescence(STML),the photon count is measured to reflect single-molecule properties,e.g.,the first molecular excited state.The energy of the first excited state is typically shown by a rise of the photon count as a function of the bias voltage between the tip and the substrate.It remains a challenge to determine the precise rise position of the current due to possible experimental noise.In this work,we propose an alternating current version of STML to resolve the fine structures in the photon count measurement.The measured photon count and the current at the long-time limit show a sinusoidal oscillation.The zero-frequency component of the current shows knee points at the precise voltage as the fraction of the detuning between the molecular gap and the DC component of the bias voltage.We propose to measure the energy level with discontinuity of the first derivative of such a zero-frequency component.The current method will extend the application of STML in terms of measuring molecular properties.展开更多
The potential energy curve of the C12 （X1∑g＋） is investigated by the highly accurate valence internally contracted multireference configuration interaction （MRCI） approach in combination with the largest correla...The potential energy curve of the C12 （X1∑g＋） is investigated by the highly accurate valence internally contracted multireference configuration interaction （MRCI） approach in combination with the largest correlation-consistent basis set, aug-cc-pV6Z, in the valence range. The theoretical spectroscopic parameters and the molecular constants of three isotopes, 35Cl2, 35Cl37Cl and 37Cl2, are studied. For the 35Cl2（X1∑g＋）, the values of Do, De, Re, We, we）we, ae and Be are obtained to be 2.3921 eV, 2.4264 eV, 0.19939 nm, 555.13 cm-1, 2.6772 cm-1, 0.001481 cm-1 and 0.24225 cm-1, respectively. For the 356137Cl（X1∑g＋）, the values of Do, De, Re, We, WeXe, ae and Be are calculated to be 2.3918 eV, 2.4257 eV, 0.19939 nm, 547.68 cm-1, 2.6234 cm-1, 0.00140 cm^1 and 0.23572 cm-1, respectively. And for the 37Cl2（X1∑g＋）, the values of Do, De, Re, We, WeXe, ae and Be are obtained to be 2.3923 eV, 2.4257 eV, 0.19939 nm, 540.06 cm-1, 2.5556 cm-1, 0.00139 cm-1 and 0.22919 cm-1, respectively. These spectroscopic results are in good agreement with the available experimental data. With the potential of Cl2 molecule determined at the MRCI/aug-cc-pV6Z level of theory, the total of 59 vibrational states is predicted for each isotope when the rotational quantum number J equals zero （J = 0）. The theoretical vibrational levels, classical turning points, inertial rotation and centrifugal distortion constants are determined when J = 0, which are in excellent accordance with the available experimental findings.展开更多
文摘The mechanism of lightning that ignites a forest fire and the lightning that occurs above a forest fire are explained at the molecular level. It is based on two phenomena, namely, internal charge separation inside the atmospheric cloud particles and the existence of a layer of positively charged hydrogen atoms sticking out of the surface of the liquid layer of water on the surface of rimers. Strong turbulence-driven collisions of the ice particles and water droplets with the rimers give rise to breakups of the ice particles and water droplets into positively and negatively charged fragments leading to charge separation. Hot weather in a forest contributes to the updraft of hot and humid air, which follows the same physical/chemical processes of normal lightning proposed and explained recently[1]. Lightning would have a high probability of lighting up and burning the dry biological materials in the ground of the forest, leading to a forest (wild) fire. The burning of trees and other plants would release a lot of heat and moisture together with a lot of smoke particles (aerosols) becoming a strong updraft. The condition for creating lightning is again satisfied which would result in further lightning high above the forest wild fire.
文摘Cloud electrification is one of the oldest unresolved puzzles in the atmospheric sciences. Though many mechanisms for charge separation in clouds have been proposed, a quantitative understanding of their respective contribution in a given meteorological situation is lacking. Here we suggest and analyze a hitherto little discussed process. A qualitative picture at the molecular level of the charge separation mechanism of lightning in a thundercloud is proposed. It is based on two key physical/chemical natural phenomena, namely, internal charge separation of the atmospheric impurities/aerosols inside an atmospheric water cluster/droplet/ice particle and the existence of liquid water layers on rimers (graupels and hailstones) forming a layer of dipoles with H<sup>+</sup> pointing out from the air-water interface. Charge separation is achieved through strong collisions among ice particles and water droplets with the rimers in the turbulence of the thundercloud. This work would have significant contribution to cloud electrification and lightning formation.
基金National Natural Science Foundation of China(No.22005154)for financial support。
文摘Photocatalytic CO_(2)reduction reaction(CO_(2)RR)is one of the promising strategies for sustainably producing solar fuels.The precise identification of catalytic sites and the enhancement of photocatalytic CO_(2)conversion is imperative yet quite challenging.This critical review summarizes recent advances in porous photo-responsive polymers,including covalent organic frameworks(COFs),covalent triazine frameworks(CTFs),and conjugated microporous polymers(CMPs),those can be rationally designed from the molecular level for visible-light-driven photocatalytic CO_(2)reduction.Additionally,special emphasis is placed on how the well-defined active sites on these polymers can influence their properties and photocatalytic performance.The precise regulation and control of microenvironments and electronic properties of metal active centers are crucial for boosting catalytic efficiency and selectivity,as well as for the design of better photocatalysts for CO_(2)reduction.
基金supported financially by the National Natural Science Foundation of China (Nos. 21302212 and 21522209)the ‘‘Strategic Priority Research Program’’ (No. XDB12010100)
文摘A series of core-expanded naphthalene diimides（NDI-DTYM） and thiophene-based derivatives（1a-c）were designed and synthesized to investigate the relationship between molecular structures and the highest occupied molecular orbital（HOMO） energy levels but has little impact on the lowest unoccupied molecular orbital（LUMO） energy levels.The results demonstrated that increasing the number of thiophene units can gradually elevate the HOMO energy levels but had little impact on the LUMO energy levels.The n-channel organic field-effect transistors（OFETs） based on 1b and 1c have demonstrated that these almost unchanged LUMO energy levels are proper to transport electrons.
基金supported by the National Natural Science Foundation of China (grant numbers:81974498)Natural Science Foundation of Shandong Province (grant numbers:ZR2019BH079)。
文摘Nanomedicine has made great progress in the targeted therapy of cancer. Here, we established a novel drug-mate strategy by studying the formulation of nanodrugs at the molecular level. In the drug-mate combination, the drug is a hydrophobic drug that is poorly soluble in water, and the mate is an amphiphilic small molecule (SMA) that has both hydrophilic and lipophilic properties. We proposed that the hydrophobic drug could co-assemble with a suitable SMA on a nanoscale without additive agents. The proof-ofconcept methodology and results were presented to support our hypothesis. We selected five hydrophobic drugs and more than ten amphiphilic small molecules to construct a library. Through molecular dynamic simulation and quantum chemistry computation,we speculated that the formation of nanoassemblies was related to the binding energy of the drug-mate, and the drug-mate interaction must overcome drug-drug interaction.Furthermore, the obtained SF/VECOONa nanoassemblieswas selected as a model, which had an ultra-high drug loading content (46%), improved pharmacokinetics, increased bioavailability, and enhanced therapeutic efficacy. In summary, the drug-mate strategy is an essential resource to design exact SMA for many hydrophobic drugs and provides a reference for the design of a carrier-free drug delivery system.
文摘滨海湿地生态系统是重要的生态系统之一,对环境变化响应敏感。海平面变化会直接影响滨海湿地的物质来源,进而影响湿地生态系统演化。然而,由于可靠地质记录的相对稀缺,长时间尺度海平面变化对滨海湿地生态系统的影响尚未全面澄清。本文旨在从沉积物有机分子组成视角探讨末次盛冰期(约22000 a BP)以来渤海西岸海平面变化对滨海湿地生态系统演化的影响。本文基于超高分辨率傅里叶变换离子回旋共振质谱(FT-ICR MS)技术分析了渤海西岸沉积物有机分子组成,结果表明末次盛冰期沉积物内源脂肪族化合物占比较高,在海平面较现代海平面平均低约130 m,在渤海西岸滨海湿地不发育情境下该区可能存在局部水系并发育湖沼环境。进入全新世,海平面快速上升,本文岩心的两个海相地层记录了约7100~6900 a BP和约6000~5650 a BP两次海侵事件;约5650 a BP以后,海平面相对稳定但缓慢下降,海岸线逐渐后退,形成了6道古海岸线和6期潟湖洼地。本研究表明滨海沉积物有机质CHO组分对海平面变化引起的环境变迁响应灵敏,有机质H/C和O/C的变化趋势指示滨海湿地在约8050~4850 a BP经历了陆相—海相—陆相的环境转变。其中约8050 a BP和约4850 a BP较高的O/C和较低的H/C表明这两个时期渤海西岸可能发育潟湖洼地,有机质主要来自陆生、半水生植物及土壤微生物活动;约5700 a BP内源脂肪族化合物占比明显较高,表明滨海湿地转变为海洋环境,有机质主要来源转变为水生藻类和浮游生物。约1350 a BP内源有机组分占比15.68%,显著高于约8050 a BP和约4850 a BP,表明湿地生态演化可能受到较强人类活动的干扰。本文的研究结果为认识海平面变化对滨海湿地生态系统演化的影响提供了新的视角和证据。
基金supported by the Program for Science and Technology Innovation Talents in Universities of Henan Province,China (Grant No 2008HASTIT008)the National Natural Science Foundation of China (Grant Nos 60777012,10874064 and 10574039)
文摘The potential energy curve of the CD（X2∏） radical is obtained using the coupled-cluster singles-doublesapproximate-triples [CCSD（T）] theory in combination with the correlation-consistent quintuple basis set augmented with diffuse functions, aug-cc-pV5Z. The potential energy curve is fitted to the Murrell-Sorbie function, which is used to determine the spectroscopic parameters. The obtained Do, De, Re, ωe, ωeXe, αe and Be values are 3.4971 eV, 3.6261 eV, 0.11197 nm, 2097.661 cm^-1, 34.6963 cm^-1, 0.2083 cm^-1 and 7.7962 cm^-1, respectively, which conform almost perfectly to the available measurements. With the potential obtained at the UCCSD（T）/aug-cc-pV5Z level of theory, a total of 24 vibrational states have been predicted for the first time when J = 0 by solving the radial Schrodinger equation of nuclear motion. The complete vibrational levels, the classical turning points, the inertial rotation constants and centrifugal distortion constants are reproduced from the CD（X2∏） potential when J = 0, and are in excellent agreement with the available measurements. The total and the various partial-wave cross sections are calculated for the elastic collisions between the ground-state C and D atoms at energies from 1.0×10^-11 to 1.0 × 10^-4 a.u. when the two atoms approach each other along the CD（X2∏） potential energy curve. Only one shape resonance is found in the total elastic cross sections, and the resonant energy is 8.36×10^-6 a.u. The results show that the shape of the total elastic cross section is mainly dominated by the s partial wave at very low temperatures. Because of the weak shape resonances coming from higher partial waves, most of them are passed into oblivion by the strong total elastic cross sections.
基金the National Natural Science Foundation of China(NSFC)(Grant No.11875049)the NSAF(Grant Nos.U1730449 and U1930403)the National Basic Research Program of China(Grant No.2016YFA0301201).
文摘In scanning tunneling microscopy-induced luminescence(STML),the photon count is measured to reflect single-molecule properties,e.g.,the first molecular excited state.The energy of the first excited state is typically shown by a rise of the photon count as a function of the bias voltage between the tip and the substrate.It remains a challenge to determine the precise rise position of the current due to possible experimental noise.In this work,we propose an alternating current version of STML to resolve the fine structures in the photon count measurement.The measured photon count and the current at the long-time limit show a sinusoidal oscillation.The zero-frequency component of the current shows knee points at the precise voltage as the fraction of the detuning between the molecular gap and the DC component of the bias voltage.We propose to measure the energy level with discontinuity of the first derivative of such a zero-frequency component.The current method will extend the application of STML in terms of measuring molecular properties.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 10874064 and 60777012)the Program for Science and Technology Innovation Talents in Universities of Henan Province of China (Grant No. 2008HASTIT008)the Natural Science Foundation of Educational Bureau of Henan Province of China (Grant No. 2010B140013)
文摘The potential energy curve of the C12 （X1∑g＋） is investigated by the highly accurate valence internally contracted multireference configuration interaction （MRCI） approach in combination with the largest correlation-consistent basis set, aug-cc-pV6Z, in the valence range. The theoretical spectroscopic parameters and the molecular constants of three isotopes, 35Cl2, 35Cl37Cl and 37Cl2, are studied. For the 35Cl2（X1∑g＋）, the values of Do, De, Re, We, we）we, ae and Be are obtained to be 2.3921 eV, 2.4264 eV, 0.19939 nm, 555.13 cm-1, 2.6772 cm-1, 0.001481 cm-1 and 0.24225 cm-1, respectively. For the 356137Cl（X1∑g＋）, the values of Do, De, Re, We, WeXe, ae and Be are calculated to be 2.3918 eV, 2.4257 eV, 0.19939 nm, 547.68 cm-1, 2.6234 cm-1, 0.00140 cm^1 and 0.23572 cm-1, respectively. And for the 37Cl2（X1∑g＋）, the values of Do, De, Re, We, WeXe, ae and Be are obtained to be 2.3923 eV, 2.4257 eV, 0.19939 nm, 540.06 cm-1, 2.5556 cm-1, 0.00139 cm-1 and 0.22919 cm-1, respectively. These spectroscopic results are in good agreement with the available experimental data. With the potential of Cl2 molecule determined at the MRCI/aug-cc-pV6Z level of theory, the total of 59 vibrational states is predicted for each isotope when the rotational quantum number J equals zero （J = 0）. The theoretical vibrational levels, classical turning points, inertial rotation and centrifugal distortion constants are determined when J = 0, which are in excellent accordance with the available experimental findings.
