在所建议传统离散颗粒模型基础上引入了多尺度分级模型,定义了不同尺度的基本颗粒和颗粒簇模拟颗粒破碎现象.在统计断裂力学W e ibu ll分布公式基础上利用名义应力给出了多尺度分级模型意义下颗粒破碎概率;结合颗粒簇的解簇模型建议了...在所建议传统离散颗粒模型基础上引入了多尺度分级模型,定义了不同尺度的基本颗粒和颗粒簇模拟颗粒破碎现象.在统计断裂力学W e ibu ll分布公式基础上利用名义应力给出了多尺度分级模型意义下颗粒破碎概率;结合颗粒簇的解簇模型建议了一个可模拟颗粒破碎的多尺度分级离散颗粒模型.数值例题初步显示了所建议模型模拟颗粒破碎现象的有效性.并利用所提出的名义有效应变和名义体积应变显示了颗粒破碎过程对颗粒材料结构物变形的影响.展开更多
Oxygen-poor vanadium oxide clusters, V2On＋ （n=l, 2）, V3On＋ （n=l, 2, 3）, and V4O3＋, were produced by laser vaporization and were mass-selected and photodissociated with 532 and 266 nm photons. The geometric stru...Oxygen-poor vanadium oxide clusters, V2On＋ （n=l, 2）, V3On＋ （n=l, 2, 3）, and V4O3＋, were produced by laser vaporization and were mass-selected and photodissociated with 532 and 266 nm photons. The geometric structures and possible dissociation channels of these clusters were determined based on the comparison of density functional calculations and pho- todissociation experiments. The experiments show that the dissociation of V2O＋, V2O2＋, and V3O3＋ mainly occurs by loss of VO, while the dissociation of V3O＋ and V4O3＋ mainly occurs by loss of V atom. For the dissociation of V3O2＋, the VO loss channel is slightly dominant compared to the V loss channel. The combination of experimental results and theoretical calculations suggests that the V loss channels of V3O＋ and V4O3＋ are single photon processes at both 532 and 266 nm. The VO loss channels of V2O2＋ and V3O3＋ are multiple-photon processes at both 532 and 266 nm.展开更多
We investigated the hydrolysis of TiⅣ along with naturally abundant AlⅢ ions and reported the formation of a stable and semiconducting nanocluster. Interestingly, this compound exhibits an unusual odd-membered ring ...We investigated the hydrolysis of TiⅣ along with naturally abundant AlⅢ ions and reported the formation of a stable and semiconducting nanocluster. Interestingly, this compound exhibits an unusual odd-membered ring structure and also represents the largest Al-containing polyoxotitanium cluster(PTC) observed thus far. The presence of a shell of organic ligands as well as the incorporation of hetero-AlⅢ ions endowed the nanocluster with high air, thermal, and pH stabilities. The present compound exhibited a record photocatalytic hydrogen evolution of 402.88 μmol g–1 h–1 among PTC materials. This work not only paves the way towards stable PTC materials but also provides new insights into the design of novel photocatalysts.展开更多
The naphthalene decomposition in a corona radical shower discharge (CRS) was investigated, with attention paid to the influences of voltage and initial naphthalene density. The OH emission spectra were investigated so...The naphthalene decomposition in a corona radical shower discharge (CRS) was investigated, with attention paid to the influences of voltage and initial naphthalene density. The OH emission spectra were investigated so as to know the naphthalene decomposing process. The by-products were analyzed and a decomposing theory in discharge was proposed. The results showed that higher voltage and relative humidity were effective on decomposition. The initial concentration affected the decomposing efficiency of naphthalene. When the initial naphthalene density was 17 mg/m3, the decomposition rate was found to be 70% under 14 kV. The main by-products were carbon dioxide and water. However, a small amount of carbonic oxide, 1,2-ethanediol and acetaldehyde were found due to the incomplete oxidization.展开更多
The authors derive a formula for the volume of a compact domain in a symmetric space from normal sections through a special submanifold in the symmetric space.This formula generalizes the volume of classical domains a...The authors derive a formula for the volume of a compact domain in a symmetric space from normal sections through a special submanifold in the symmetric space.This formula generalizes the volume of classical domains as tubes or domains given as motions along the submanifold.Finally,some stereological considerations regarding this formula are provided.展开更多
Clean Pt nanoclusters with a diameter of1.0-2.4 nm,supported on reduced graphene oxide（rGO）nanosheets,were successfully synthesized by simple in situ thermolysis of a Pt-carbonyl complex.The supported Pt nanocluster...Clean Pt nanoclusters with a diameter of1.0-2.4 nm,supported on reduced graphene oxide（rGO）nanosheets,were successfully synthesized by simple in situ thermolysis of a Pt-carbonyl complex.The supported Pt nanoclusters are in an electron-deficient state because of the electron transfer between the nanoclusters and the rGO sheets.The as-prepared Pt-1 nm/rGO shows high catalytic activity for the 100%selective hydrogenation of nitrobenzene,with the turnover frequency（TOF） reaching 975.4 h^（-1）at 25℃ and 1 atm.This number is higher than the previously reported value for the heterogeneously catalyzed hydrogenation of nitrobenzene.The proposed process follows a direct hydrogenation mechanism,as is revealed by the analyses of the intermediate products.This work presents a facile and effective synthetic approach for achieving highly efficient nanocatalysts,and can be extended to obtain other metal catalysts with ultra-small sizes and excellent performance.展开更多
文摘在所建议传统离散颗粒模型基础上引入了多尺度分级模型,定义了不同尺度的基本颗粒和颗粒簇模拟颗粒破碎现象.在统计断裂力学W e ibu ll分布公式基础上利用名义应力给出了多尺度分级模型意义下颗粒破碎概率;结合颗粒簇的解簇模型建议了一个可模拟颗粒破碎的多尺度分级离散颗粒模型.数值例题初步显示了所建议模型模拟颗粒破碎现象的有效性.并利用所提出的名义有效应变和名义体积应变显示了颗粒破碎过程对颗粒材料结构物变形的影响.
基金This work was supported by the National Natural Science Foundation of China （No.20933008）. The theoretical calculations were conducted on the ScGrid and Deepcomp7000 of the Supercomputing Center, Com- puter Network Information Center of Chinese Academy of Sciences. We thank Dr. Xun-lei Ding and Dr. Yan-xia Zhao for valuable discussion.
文摘Oxygen-poor vanadium oxide clusters, V2On＋ （n=l, 2）, V3On＋ （n=l, 2, 3）, and V4O3＋, were produced by laser vaporization and were mass-selected and photodissociated with 532 and 266 nm photons. The geometric structures and possible dissociation channels of these clusters were determined based on the comparison of density functional calculations and pho- todissociation experiments. The experiments show that the dissociation of V2O＋, V2O2＋, and V3O3＋ mainly occurs by loss of VO, while the dissociation of V3O＋ and V4O3＋ mainly occurs by loss of V atom. For the dissociation of V3O2＋, the VO loss channel is slightly dominant compared to the V loss channel. The combination of experimental results and theoretical calculations suggests that the V loss channels of V3O＋ and V4O3＋ are single photon processes at both 532 and 266 nm. The VO loss channels of V2O2＋ and V3O3＋ are multiple-photon processes at both 532 and 266 nm.
文摘We investigated the hydrolysis of TiⅣ along with naturally abundant AlⅢ ions and reported the formation of a stable and semiconducting nanocluster. Interestingly, this compound exhibits an unusual odd-membered ring structure and also represents the largest Al-containing polyoxotitanium cluster(PTC) observed thus far. The presence of a shell of organic ligands as well as the incorporation of hetero-AlⅢ ions endowed the nanocluster with high air, thermal, and pH stabilities. The present compound exhibited a record photocatalytic hydrogen evolution of 402.88 μmol g–1 h–1 among PTC materials. This work not only paves the way towards stable PTC materials but also provides new insights into the design of novel photocatalysts.
基金Project supported by the National Basic Research Program (973) of China (No.2006CB200303)the Chinese-Slovak Scientific and Technological Cooperation Program (No.2010DFA92020)the China Postdoctoral Science Foundation (No.20100471698)
文摘The naphthalene decomposition in a corona radical shower discharge (CRS) was investigated, with attention paid to the influences of voltage and initial naphthalene density. The OH emission spectra were investigated so as to know the naphthalene decomposing process. The by-products were analyzed and a decomposing theory in discharge was proposed. The results showed that higher voltage and relative humidity were effective on decomposition. The initial concentration affected the decomposing efficiency of naphthalene. When the initial naphthalene density was 17 mg/m3, the decomposition rate was found to be 70% under 14 kV. The main by-products were carbon dioxide and water. However, a small amount of carbonic oxide, 1,2-ethanediol and acetaldehyde were found due to the incomplete oxidization.
基金Project supported by the Spanish Ministry of Science and Technology Grants MTM2005-O8689-G02-02 and MTM 2004-06015-C02-01.
文摘The authors derive a formula for the volume of a compact domain in a symmetric space from normal sections through a special submanifold in the symmetric space.This formula generalizes the volume of classical domains as tubes or domains given as motions along the submanifold.Finally,some stereological considerations regarding this formula are provided.
基金supported by the National Natural Science Foundation of China(51402362 and 21471160)Shandong Provincial Natural Science Foundation,China(ZR2014EMQ012 and ZR2016BM12)+1 种基金the Fundamental Research Funds for the Central Universities(15CX08010A,16CX05016 and 16CX05014A)start-up fund from Tianjin University of Technology
文摘Clean Pt nanoclusters with a diameter of1.0-2.4 nm,supported on reduced graphene oxide（rGO）nanosheets,were successfully synthesized by simple in situ thermolysis of a Pt-carbonyl complex.The supported Pt nanoclusters are in an electron-deficient state because of the electron transfer between the nanoclusters and the rGO sheets.The as-prepared Pt-1 nm/rGO shows high catalytic activity for the 100%selective hydrogenation of nitrobenzene,with the turnover frequency（TOF） reaching 975.4 h^（-1）at 25℃ and 1 atm.This number is higher than the previously reported value for the heterogeneously catalyzed hydrogenation of nitrobenzene.The proposed process follows a direct hydrogenation mechanism,as is revealed by the analyses of the intermediate products.This work presents a facile and effective synthetic approach for achieving highly efficient nanocatalysts,and can be extended to obtain other metal catalysts with ultra-small sizes and excellent performance.
