分类: 生物学 >> 动物学 提交时间: 2021-04-02 合作期刊: 《古脊椎动物学报》
摘要: Here we report a Hipparion fauna locality discovered in between two basalt layers near Hanjiaying Village, Jining District, Wulanchabu City, Nei Mongol. K-Ar isotopic dating of the lower and upper level of the basalt constrains the age of the fauna from 7.2 to 6.8 Ma. Compared with classical Hipparion fauna from northern China, the Hanjiaying fauna is closer to those from Baode of Shanxi, Siziwang Banner of Nei Mongol and the Linxia Basin of Gansu. It is similar to the Loc. 43, 44 and 49 from Baode by faunal composition, confirming their age to be ~7.0 Ma rather than 5.5 Ma. The high similarity with the fossils from Wulanhua, Siziwang Banner, Nei Mongol, verified the age of Wulanhua fauna at about 7 Ma. Compared with faunas from the Linxia Basin, Gansu, it is more similar to those from the upper part of the Liushu Formation, especially the Yangjiashan fauna. Based on the faunal composition and their tooth morphology, the Hanjiaying fauna could be included in the “Gazella dorcadoides” fauna, which is supposed to be at the west paleobiome in northern China during the Late Miocene.
分类: 化学 >> 物理化学 提交时间: 2017-11-05 合作期刊: 《结构化学》
摘要: A homochrial manganese(III) complex (1) derived from chiral salen ligand (1R,2R)-(-)-1,2-diphenylethane-1,2-diamine-N,N΄-bicarboxyl-salicylidene) has been synthesized through solvothermal procedure and characterized by IR, elemental analysis, TGA, circular dichroism (CD), powder and single-crystal X-ray crystallography. It crystallizes in orthorhombic, space group P212121 with a = 9.108(3), b = 16.431(5), c = 26.531(6) Å, V = 3970.4(19) Å3, Z = 4, Dc = 1.248 g/cm3, F(000) = 1568, Mr = 745.73, μ = 0.383 mm-1, the final GOOF = 0.957, R = 0.0631 and wR = 0.1079 for 13250 observed reflections with I > 2σ(I). The coordination polymer 1 possesses a 1D infinite zigzag chain architecture constructed by the dicarboxyl-functionalized metallosalen ligand (Mn-salen), and the polymeric chains are further assembled into a 3D supramolecular network structure via strong intermolecular hydrogen bonding interactions between adjacent zigzag chains. As a heterogeneous catalyst, 1 was used as an efficient heterogeneous catalyst for the asymmetric olefin epoxidation.
分类: 化学 >> 物理化学 提交时间: 2017-11-05 合作期刊: 《结构化学》
摘要: A novel indium-based chiral metal organic-framework 1 {In2L(μ2-O)(H2O)3}n was synthesized from C2-symmetric 1,1΄-biphenol-based ligand H4L and structurally characterized by single-crystal and powder X-ray diffraction, Fourier-transform infrared spectra (FTIR), solid-state circular dichroism (CD) and thermal gravimetric analysis (TGA). 1 crystallizes in monoclinic space group P21 with a = 10.1861(5), b = 18.5632(9), c = 16.5153(8) Å, V = 3077.1(3) Å3, Z = 2, Mr = 944.29 g/mol, Dc = 1.019 g/cm3, F(000) = 944, GOOF = 0.932, the final R = 0.0577 and wR = 0.1091 for 22090 observed reflections with I > 2σ(I). Each In2 cluster in 1 is linked by four ligands and each ligand is coordinated to four In2 clusters to generate a 3D network. Additionally, the photoluminescence of 1 and H4L were also investigated.
分类: 化学 >> 物理化学 提交时间: 2017-11-05 合作期刊: 《结构化学》
摘要: Two metal-organic frameworks [(Zn0.5L)·(H2O)]n (1) and [(Ni0.5L)·(H2O)]n (2) constructed by the 3-formyl-4-(pyridin-4-yl) benzoic acid ligand (HL) were synthesized and characterized by single-crystal X-ray diffraction. 1 crystallizes in orthorhombic space group Pnna with a = 16.6152(8), b = 12.6825(6), c = 15.3908(8) Å, V = 3243.2(3) Å3, Z = 4, Mr = 511.12, Dc = 1.047 g/cm3, F(000) = 1048, μ = 1.144 mm-1, GOOF = 1.061, the final R = 0.0471 and wR = 0.1262 for 12168 observed reflections with I > 2σ(I). 2 is isostructural to 1, which also crystallizes in orthorhombic space group Pnna with a = 16.6152(8), b = 12.6825(6), c = 15.3908(8) Å, V = 3243.2(3) Å3, Z = 4, Mr = 511.12, Dc = 1.047 g/cm3, F(000) = 1048, μ = 1.144 mm-1, GOOF = 1.061, the final R = 0.0471 and wR = 0.1262 for 12168 observed reflections with I > 2σ(I). Additionally, thermogravimetric analysis, FT-IR spectroscopy and powder X-ray diffraction were discussed.
分类: 物理学 >> 核物理学 提交时间: 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要: A simulation approach is developed to obtain the linear energy transfer (LET) spectrum of all secondary ions and predict single event upset (SEU) occurrence induced by neutron in memory devices. Neutron reaction channels, secondary ion species and energy ranges, and LET calculation method are introduced respectively. Experimental results of neutron induced SEU effects on static random access memory (SRAM) and programmable read only memory (EEPROM) are presented to confirm the validity of the simulation results.
分类: 核科学技术 >> 核探测技术与核电子学 提交时间: 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要: A digital three-detector positron lifetime spectrometer was developed. It consists of a DRS4 waveform digitizing board and three LaBr3 scintillation detectors coupled to XP2020Q photomultiplier tubes. DRS4 waveform digitizing allows data sampling at up to 5 GSPS with high amplitude resolution, with good time scale linearity and stability. In the triple-coincidence, the new system could reach a 195 ps time resolution, which is better than the conventional analog apparatus with the same detectors. This spectrometer can be applied to the other scintillation timing measurements with picoseconds accuracy.
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-05-02
摘要: A new facile scalable method has been developed to synthesize silicon oxycarbide (SiOC)/carbon nanohybrids using difunctional dental methacrylate monomers as solvent and carbon source and the silane coupling agent as the precursor for SiOC. The content (from 100% to 40% by mass) and structure (ratio of disor- dered carbon over ordered carbon) of the free carbon matrix have been systematically tuned by varying the mass ratio of methacryloxy- propyltrimethoxysilane (MPTMS) over the total mass of the resin monomers from 0.0 to 6.0. Compared to the bare carbon anode, the introduction of MPTMS significantly improves the electrochemical performance as a lithium-ion battery anode. The initial and cycled discharge/charge capacities of the SiOC/C nanohybrid anodes reach maximum with the MPTMS ratio of 0.50, which displays very good rate performance as well. Detailed structures and electrochemical performance as lithium-ion battery anodes have been systematically investigated. The structure−property correlation and corresponding mechanism have been discussed.