The electronic state and potential data of U2 molecules are performed by first principle calculations with B3LYP hybrid exchange-correlation functional, the valence electrons of U atom are treated with the （5s4p3d4f...The electronic state and potential data of U2 molecules are performed by first principle calculations with B3LYP hybrid exchange-correlation functional, the valence electrons of U atom are treated with the （5s4p3d4f）/[3s3p2d2f] contraction basis sets, and the cores are approximated with the relativistic effective core potential. The results show that the ground electronic state is x^9∑g＋. The pair potential data are fitted with a Murrell-Sorbie analytical potential function. The U-U embedded atom method （EAM） interatomic potential is determined based on the generalized gradient approximation calculation within the framework of the density functional theory using Perdew-Burke-Ernzerhof exchange-correlation functional at the spin-polarized level. The physical properties, such as the cohesive energy, the lattice constant, the bulk modulus, the shear modulus, the sc/fec relative energy, the hep/fce rela- tive energy, the shear modulus and the monovacaney formation energy are used to evaluate the EAM potential parameters. The U-U pair potential determined by the first principle calculations is in agreement with that defined by the EAM potential parameters. The EAM calculated formation energy of the monovacancy in the fee structure is also found to be in close agreement with DFT calculation.展开更多
The aim of the study was to characterize humus system of natural and artificial products. Humus systems from leonardite, lignite biotransformed with Trichoderma sp. （Plantagra）, plant materials after pyrolisis （cha...The aim of the study was to characterize humus system of natural and artificial products. Humus systems from leonardite, lignite biotransformed with Trichoderma sp. （Plantagra）, plant materials after pyrolisis （charcoal） and composts are compared. Humus systems are characterized by Kononova-Belchikova＇s method, and heavy metals content was measured by atomic absorption spectroscopy （AAS）. Humic acids from the International Humic Substances Society （IHSS） collection are the standards for humus substances quality of compared products. Data obtained for leonardite indicate that the studied substances from factory, Izmir, Turkey contain humic acids over 94%. Compared to the standard, heavy metals content in these materials demonstrate high amounts. Organic carbon content in the composts is very low compared to the leonardite materials and IHSS collection, where the heavy metals content is lower. Biotransformed lignite is characterized with lower content of organic carbon, but humic acids are with high degree of humification. Results obtained show that the fourth studied humus systems may be used in agriculture on base of the high humic acids content. It is recommended to measure heavy metals content before applying the materials in agriculture.展开更多
The bioavailability of five divalent cationic heavy metals （Pb, Cd, Cu, Zn and Ni） in 10 superficial sediment samples from Baihua Lake was assessed based on the molar ratio of simultaneously extracted metals （SEMs...The bioavailability of five divalent cationic heavy metals （Pb, Cd, Cu, Zn and Ni） in 10 superficial sediment samples from Baihua Lake was assessed based on the molar ratio of simultaneously extracted metals （SEMs） to acid volatile sulfide （AVS）. Atomic absorption spectrometry （AAS） and X-ray powder diffraction （XRD） were used to determine the heavy metal concentrations and examine the mineralogy of the crystalline phases, respectively. The AVS loadings in sediments from Baihua Lake ranged from 64.30 to 350.08 ~rnol/g （dry weight）. The corresponding SEM levels for the sampling sites varied from 1.770 to 14.660 vrnol/g. The molar ratio of SEMs to AVS ranged from 0.014 to 0.084 with a mean value of 0.034. The XRD analysis also confirmed the presence of some metal sulfides in sediments from Baihua Lake. The SEMs/AVS ratios for all sampling sites were significantly lower than 1.0, indicating that AVS in the sediments was sufficient to bind the five heavy metals; thus, these heavy metals are currently not significantly bioavailable to benthic organisms. Comparing the SEMs results to published guideline values for metal toxicity to benthic organisms in sediments, however, suggests that Zn and Ni pose a risk at some sampling locations in Baihua Lake.展开更多
Wide transmittance range is an essential factor for the design of infrared optical materials.Traditionally,the designs of mid-far infrared crystals have focused on oxygenfree systems of chalcogenides and pnictides.Nev...Wide transmittance range is an essential factor for the design of infrared optical materials.Traditionally,the designs of mid-far infrared crystals have focused on oxygenfree systems of chalcogenides and pnictides.Nevertheless,the introduction of elements with large atomic numbers,such as the lone-pair cation Pb^(2+) and halogen anion I^(-),based on the oxyhalides,can broaden the infrared transmittance range.Thus,two new polymorphs of Pb(Ⅱ)-containing oxyhalides,Pb_(14)O_(8)I_(12)(α-POI)and Pb_(7)O_(4)I_(6)(β-POI),are successfully synthesized via the high-temperature solution method.Interestingly,they crystallize in the same space group,P1,and present unprecedented[O_(8)Pb_(14)]clusters from the perspective of oxocentered[OPb_(4)]basic units.Remarkably,POI exhibits a quite wide transparent range(0.47-16.0μm),which enlightens the oxyhalides with prominent infrared optical properties.Additionally,the first principles calculations show that they have large birefringence(0.139 and 0.108 for α-and β-POI at 1064 nm,respectively),which makes POI promising infrared optical materials.展开更多
By using the coupled duster method and the numerical density matrix renormalization group method, we investigate the properties of the quantum plateau state in an alternating Heisenberg spin chain. In the absence of a...By using the coupled duster method and the numerical density matrix renormalization group method, we investigate the properties of the quantum plateau state in an alternating Heisenberg spin chain. In the absence of a magnetic field, the results obtained from the coupled cluster method and density matrix renormalization group method both show that the ground state of the aiternating chain is a gapped dimerized state when the parameter a exceeds a critical point ac. The value of the critical points can be determined precisely by a detailed investigation of the behavior of the spin gap. The system therefore possesses an m = 0 plateau state in the presence of a magnetic field When a 〉 ac. In addition to the m = 0 plateau state, the results of density matrix renormaiization group indicate that there is an m = 1/4 plateau state that occurs between two critical fields in the alternating chain if a 〉 1. The mechanism for the m = 1/4 plateau state and the critical behavior of the magnetization as one approaches this plateau state are also discussed.展开更多
文摘The electronic state and potential data of U2 molecules are performed by first principle calculations with B3LYP hybrid exchange-correlation functional, the valence electrons of U atom are treated with the （5s4p3d4f）/[3s3p2d2f] contraction basis sets, and the cores are approximated with the relativistic effective core potential. The results show that the ground electronic state is x^9∑g＋. The pair potential data are fitted with a Murrell-Sorbie analytical potential function. The U-U embedded atom method （EAM） interatomic potential is determined based on the generalized gradient approximation calculation within the framework of the density functional theory using Perdew-Burke-Ernzerhof exchange-correlation functional at the spin-polarized level. The physical properties, such as the cohesive energy, the lattice constant, the bulk modulus, the shear modulus, the sc/fec relative energy, the hep/fce rela- tive energy, the shear modulus and the monovacaney formation energy are used to evaluate the EAM potential parameters. The U-U pair potential determined by the first principle calculations is in agreement with that defined by the EAM potential parameters. The EAM calculated formation energy of the monovacancy in the fee structure is also found to be in close agreement with DFT calculation.
文摘The aim of the study was to characterize humus system of natural and artificial products. Humus systems from leonardite, lignite biotransformed with Trichoderma sp. （Plantagra）, plant materials after pyrolisis （charcoal） and composts are compared. Humus systems are characterized by Kononova-Belchikova＇s method, and heavy metals content was measured by atomic absorption spectroscopy （AAS）. Humic acids from the International Humic Substances Society （IHSS） collection are the standards for humus substances quality of compared products. Data obtained for leonardite indicate that the studied substances from factory, Izmir, Turkey contain humic acids over 94%. Compared to the standard, heavy metals content in these materials demonstrate high amounts. Organic carbon content in the composts is very low compared to the leonardite materials and IHSS collection, where the heavy metals content is lower. Biotransformed lignite is characterized with lower content of organic carbon, but humic acids are with high degree of humification. Results obtained show that the fourth studied humus systems may be used in agriculture on base of the high humic acids content. It is recommended to measure heavy metals content before applying the materials in agriculture.
基金Supported by the National Natural Science Foundation of China(No.20967003)the Project of the Government of Guiyang City(No.[2010]5-2)
文摘The bioavailability of five divalent cationic heavy metals （Pb, Cd, Cu, Zn and Ni） in 10 superficial sediment samples from Baihua Lake was assessed based on the molar ratio of simultaneously extracted metals （SEMs） to acid volatile sulfide （AVS）. Atomic absorption spectrometry （AAS） and X-ray powder diffraction （XRD） were used to determine the heavy metal concentrations and examine the mineralogy of the crystalline phases, respectively. The AVS loadings in sediments from Baihua Lake ranged from 64.30 to 350.08 ~rnol/g （dry weight）. The corresponding SEM levels for the sampling sites varied from 1.770 to 14.660 vrnol/g. The molar ratio of SEMs to AVS ranged from 0.014 to 0.084 with a mean value of 0.034. The XRD analysis also confirmed the presence of some metal sulfides in sediments from Baihua Lake. The SEMs/AVS ratios for all sampling sites were significantly lower than 1.0, indicating that AVS in the sediments was sufficient to bind the five heavy metals; thus, these heavy metals are currently not significantly bioavailable to benthic organisms. Comparing the SEMs results to published guideline values for metal toxicity to benthic organisms in sediments, however, suggests that Zn and Ni pose a risk at some sampling locations in Baihua Lake.
基金supported by the Youth Innovation Promotion Association of Chinese Academy of Sciences(CAS)(2020429)the National Natural Science Foundation of China(22122509,52002398 and 11774414)+3 种基金the West Light Foundation of the CAS(2019-YDYLTD-002)the International Partnership Program of CAS(1A1365KYSB20200008)the Instrument Developing Project of CAS(GJJSTD20200007)the Science and Technology Service Network Initiative of CAS(KFJ-STS-QYZD-130)。
文摘Wide transmittance range is an essential factor for the design of infrared optical materials.Traditionally,the designs of mid-far infrared crystals have focused on oxygenfree systems of chalcogenides and pnictides.Nevertheless,the introduction of elements with large atomic numbers,such as the lone-pair cation Pb^(2+) and halogen anion I^(-),based on the oxyhalides,can broaden the infrared transmittance range.Thus,two new polymorphs of Pb(Ⅱ)-containing oxyhalides,Pb_(14)O_(8)I_(12)(α-POI)and Pb_(7)O_(4)I_(6)(β-POI),are successfully synthesized via the high-temperature solution method.Interestingly,they crystallize in the same space group,P1,and present unprecedented[O_(8)Pb_(14)]clusters from the perspective of oxocentered[OPb_(4)]basic units.Remarkably,POI exhibits a quite wide transparent range(0.47-16.0μm),which enlightens the oxyhalides with prominent infrared optical properties.Additionally,the first principles calculations show that they have large birefringence(0.139 and 0.108 for α-and β-POI at 1064 nm,respectively),which makes POI promising infrared optical materials.
基金Supported by the National Natural Science Foundation of China under Grant Nos.10804053 and 61203147the Natural Science Foundation of Jiangsu Province under Grant No.BK20131428+2 种基金the Natural Science Foundation of the Jiangsu Higher Education Institutions under Grant No.13KJD140003the Scientific Research Foundation of Nanjing University of Posts and Telecommunications under Grant No.NY211008Qing Lan Project of Jiangsu Province
文摘By using the coupled duster method and the numerical density matrix renormalization group method, we investigate the properties of the quantum plateau state in an alternating Heisenberg spin chain. In the absence of a magnetic field, the results obtained from the coupled cluster method and density matrix renormalization group method both show that the ground state of the aiternating chain is a gapped dimerized state when the parameter a exceeds a critical point ac. The value of the critical points can be determined precisely by a detailed investigation of the behavior of the spin gap. The system therefore possesses an m = 0 plateau state in the presence of a magnetic field When a 〉 ac. In addition to the m = 0 plateau state, the results of density matrix renormaiization group indicate that there is an m = 1/4 plateau state that occurs between two critical fields in the alternating chain if a 〉 1. The mechanism for the m = 1/4 plateau state and the critical behavior of the magnetization as one approaches this plateau state are also discussed.
