EXAFS study on the local atomic strucures around iron in glycosylated haemoglobin

Samples with 5.1%9.8% and 15.3% HbA1c were extracted from normal subjects and patients with slight and serious diabetes respectively.Extended x-ray absorption fine structure spectra of Fe K absorption were collected at the EXAFS experimental station of the Beijing Synchrotron Radiation Facility.The step-by-step fluorescent mode was employed with a count time of 10s per point.Several independent scans were averageed to eliminate the statistical nosie.Reference backscattering amplitudes and phaseshifts were calculated using the curve wave theory (FEFF code) of EXAFS.Apart from the nitrogen neighbors around the central iron atom,oxygen neighbours are also found.The Fe-Nbond length increases by about 0.02A for the sample with 15.3% HbAlc Compared with the others,but the Fe-Obond length is almost unchanged.With increasing of HbAlc concentration,the content of Hb increases and the content of HbO2 decreases.This demonstrates that the glycosylation of haemoglobin will decrease its ability to carry oxygen.     

Atomic and Electronic Structures of Zr Atomic Chains

The atomic, binding and electronic structures of very thin Zr chains are studied by the first-principles density functional method. The present calculations reveal that zirconium can form planar chains in zigzag, dimer and ladder structures. The zigzag geometry has two minima. The most stable geometry is the zigzag one with a unitcell rather close to equilateral triangles with four nearest neighbours. The other stable zigzag structure has awide bond angle and allows for two nearest neighbours. An intermediary structure has the ladder geometry andis formed by two strands. The dimer structure is also found to be more stable than the truly linear chain. Allthese planar geometries are more favourable energetically than the linear chain. We also show that by going fromZr bulk to a Zr chain, the characters of bonding do not change significantly.     

碳原子离子光电离截面的相对论多极计算

基于Dirac-slater自洽场方法,本文计算了C元素各价离子从低能到高能的光电离截面,考察了多极效应、相对论效应在不同能区对光电离截面的影响,并研究了光电离截面随光子能量、电离度、不同壳层变化的规律.通过各种理论计算结果的比较,分析了Kramers公式的适用性.计算中为了提高计算精度,我们采用了Grasp2程序包输出的束缚态波函数替换自洽场的波函数.     

Quantum Interference Between Decay Channels of a Three-Level Atom Placed Between Two Parallel Plates

We investigate the generation of quantum interference induced by spontaneous emission from two transitions of a V-type three-level atom embedded between two parallel plates (one or both the plates have infinite permeability, i.e.μ→∞). The result shows that, due to the anisotropy of vacuum, quantum interference still exists although the two dipole matrix elements of the atom are orthogonal to each other. When the atom is located very close to one of the plates, the quantum interference effect is particularly prominent. The strength of quantum interference displays oscillating behaviour with the position of the atom. With the increase of the distance between the plates, the oscillation becomes dense.     

低温区观测汞原子高激发态

低温区观测汞原子高激发态詹可雷，王绪志（安徽淮南矿业学院２３２００１）汞原子处于激发态时，有两套能级结构，一套单一态，一套三重态．对ｓｐ组态，６ｐ电子可处在４种状态。６１Ｐ１态的能级为６．７ｅＶ，６３Ｐ２．１．０态的能级分别为５．４６ｅＶ，４．８９ｅ...     

基于席夫碱配体和两种苯甲酸盐构筑的两例Dy4配合物的合成、结构及单分子磁体性质

使用Dy(NO₃)₃·6H₂O与席夫碱配体2-(((2-羟基-3-甲氧基苄基)亚氨基)甲基)-4-甲氧基苯酚(H₂L)和2个辅助配体PhCO₂H和2-NO₂-PhCO₂H在乙醇中反应,得到2例Dy₄配合物[Dy₄(L)₄(PhCO₂)₂(NO₃)₂(EtOH)₂](1)和[Dy₄(L)₄(2-NO₂-PhCO₂)₂(NO₃)₂(EtOH)₂](2)。单晶X射线衍射解析表明配合物1和2均由Dy₂基本单元构建,形成中心对称的四核线性链状结构。配合物1和2中Dy₂单元中的一个Dy(Ⅲ)离子呈现七配位几何构型,另一个Dy(Ⅲ)离子呈现八配位几何构型。2例配合物均为单分子磁体,其能垒分别为110和108 K。通过理论计算对1和2的磁性能进行了分析。     

“显性反思性”的科学本质教学*——以“原子结构”发展史为例

科学本质作为国际科学教育的重要目标,受到越来越多的关注。但在实践中,教师缺少对科学本质的内涵和具体方面的深度理解,同时缺少有效的科学本质教学的相关指导。本文探讨了基础教育阶段科学本质的8个方面的具体内涵,阐明了科学本质的有效教学的特征,并以“原子结构”为例,为教师开展科学本质教学提供范例。     

自旋多重度对钛三聚体原子结构的影响

基于密度泛函理论，获得了钛三聚体在不同自旋多重度下的原子结构，并计算了对应的振动频率.发现自旋多重度对钛三聚体的原子结构有重要的影响，特别是对键长和振动频率.考虑自旋多重度后，钛三聚体的基态结构为自旋七重态. 关键词： 钛三聚体 自旋多重度 原子结构