Two new aromadendrane sesquiterpenes from Verticillium psalliotae

The chemical constituents of the fungus Verticillium psalliotae were studied. Two new aromadendrane sesquiterpenes inonotin M (1) and inonotin N (2) were isolated from the EtOAc extract of the fungal culture broth. The structures of compounds were elucidated mainly by HRESIMS experiments, and 1D, 2D-NMR spectroscopy analysis.     

Contrast Adaptation Decreases Complexity in Retinal Ganglion Cell Spike Train

The difference in temporal structures of retinal ganglion cell spike trains between spontaneous activity and firing activity after contrast adaptation is investigated. The Lempel-Ziv complexity analysis reveals that the complexity of the neural spike train decreases after contrast adaptation. This implies that the behaviour of the neuron becomes ordered, which may carry relevant information about the external stimulus. Thus, during the neuron activity after contrast adaptation, external information could be encoded in forms of some certain patterns in the temporal structure of spike train that is significantly different, compared to that of the spike train during spontaneous activity, although the firing rates in spontaneous activity and firing activity after contrast adaptation are sometime similar.     

第一性原理研究Fe掺杂SnO2材料的光电性质

采用基于第一性原理的线性缀加平面波(FP-LAPW)方法,研究Fe掺杂SnO₂材料电子结构和光学性质,包括电子态密度、能带结构、介电函数和其他一些光学图谱. 研究结果表明,掺Fe后材料均属于直接跃迁半导体,且呈现半金属性;随掺杂浓度增加,费米能级进入价带,带隙逐渐减小,Fe原子之间耦合作用增强;通过掺杂能够在一定程度上改变成键性质,使其具有金属键性质. 光学谱线(吸收谱、消光系数等)与介电函数虚部谱线相对应,均发生蓝移,各峰值与电子跃迁吸收有关,从理论上指出光学性质和电子结构的内在联系. 关键词： 能带结构 态密度 光学性质 介电函数     

第一性原理研究In,N共掺杂SnO2材料的光电性质

采用全电势线性缀加平面波(FP-LAPW)的方法,基于密度泛函理论第一性原理结合广义梯度近似(GGA),运用Wien2k软件计算了In, N两种元素共掺杂SnO₂材料的电子态密度和光学性质. 研究表明,共掺杂结构在自旋向下和向上两方向上都出现细的局域能级,两者态密度分布不对称;带隙内自旋向下方向上产生局域能级,共掺化合物表现出半金属性;能带结构显示两种共掺杂化合物仍为直接禁带半导体,价带顶随着N浓度的增加发生向低能方向移动,带隙明显增宽;共掺下的介电函数虚部主介电峰只在8.58 eV 关键词： 电子结构 态密度 能带结构 光学性质     

Four-State Model for Three-Branch Molecule＇s Two-Photon Absorption Properties

We present a four-state model for calculating the two-photon absorption of multi-branched molecules by using the time-depended function method, The numerical results indicate that the two-photon absorption cross section has a strong enhancement for three-branch molecules compared to two-branch structures, The maximal two-photon-absorption cross section is 2.358 × 10^-47 cm^4s/photon, At the same time, the charge-transfer process for the charge-transfer states is visualized in order to explain mechanism about the maximal TPA cross section.     

N掺杂SnO2材料光电性质的第一性原理研究

采用全电势线性缀加平面波(full potential linearized augmented plane wave method,简记为FP-LAPW)方法,基于密度泛函理论第一性原理计算分析N掺杂SnO₂材料,研究了在N替代O原子和N替代Sn原子情况下的电子态密度、电荷密度分布以及光学性质.研究表明N掺杂替代Sn较之N掺杂替代O原子的带隙要宽,都宽于SnO₂的本征带隙,且两种情况下N分别处于负氧化态和正氧化态,其介电函数谱也与带隙对应发生蓝移,从理论上指出     

The electronic and magnetic properties with intrinsic defects in ZnO nanosheets: First-principles prediction

Using full-potential linearized augmented plane wave (FLAPW) method, we investigated the effects of intrinsic vacancies on electronic and magnetic properties in graphene-like ZnO nanosheets. The results show that the oxygen vacancy (V_O) has no influence on magnetism in ZnO nanosheet, whereas the Zn vacancy (V_Zn) lead to spin polarization of the nanostructures with a total magnetic moment of 2.0μ_B due to O-2p and Zn-3d hybridization. When the distance of two V_Zn defects increases to 6.499 Å, the system shows an intriguing half-metallic character with 100% spin-polarized carriers due to O(2p)–Zn(3d)–O(2p) coupling chain between two V_Zn defects.     

Electronic structures and magnetic properties in SmCo7-xMx

The electronic structures and magnetic properties of SmCo7 xMx (M=Ti, Si, Zr, Hf, Cu, B, Ag, Ga, Mn) compounds are investigated by using a spin-polarized MS-X.α method. The results show that the long-range ferromagnetic order is determined by a stronger 3d-5d interaction, rather than the traditional RKKY interaction, and the effects of doping element M on 3d-5d coupling are negligible in Sm-Co-based compounds. The nonmagnetic dopant Si atoms have a larger effect on the moments of 2e site although they preferably occupy the Co 3g sites, which results in the stronger uniaxial anisotropy of this compound. Analysis of the formation energies indicates that 5d-element doped compounds are more stable than other dopants, and furthermore, they have a higher Curie temperature above room temperature, which will be in favor of their potential application as high-temperature permanent magnets.     

云南美登木内生真菌Phomopsis sp. Lz42的化学成分

从云南美登木内生真菌Phomopsis species Lz42的琼脂平板发酵物中分离得到2个倍半萜和5个麦角甾醇类化合物(1~7), 其中化合物1和2为新化合物. 应用波谱技术确定其结构为4-Deacetyl-10-oxo-dihydrobotrydial(1)和麦角甾-6,22-二烯-5α,8α-环二氧-3-甲酸酯(2).