Oxidation of enones to α′-acetoxyenones using manganese triacetate

The oxidation of α,β-unsaturated ketones with manganese (III) triacetate in benzene furnishes α'-acetoxyenones in good yields.     

多尺度B样条小波边缘检测算子

基于B样条理论提出了一类新的多尺度小波变换,通过其零交叉或模极值能有效地表示和检测信号或图象的边缘,对任意n次B样条,导出了相应的分解和重建的快速算法,对应的用于分解和重建的滤波器的时域和频域响应也被精确地给出.从时频局部化的角度对不同次数的B样条作了分析,认为3次B样条小波在边缘提取等实际应用中是渐近最优的,结果也为B样条小波在立体视觉匹配、滤噪等方面的进一步应用提供了基础.     

Hyperfine magnetic field measurements in Heusler alloys Ni2MnGa,Pd2MnSn,and Ru2FeSn

Hmf values are reported for Fe-57 in Ni₂MnGa, and for Cd-111, Fe-57, and Sn-119 in Pd₂MnSn and Ru₂FeSn.     

NH3+自由基离子的电子自旋共振

本文研究了俘获于掺杂VO⁺⁺离子的(NH₄)₂Zn(SO₄)₂·6H₂O单晶中NH₃⁺自由基离子的ESR.从实验上分别测出π电子自由基NH₃⁺的¹⁴N和¹⁵N核超精细分裂.结果表明,氮核超精细偶合张量具有近似于圆柱形对称。对于¹⁵N来说,A₁₁=44.8,A₂₂=19.3,A₃₃=17.8高斯.对于¹⁴N来说,A₁₁=31.1,A₂₂=12.5,A₃₃=11.8高斯.在室温下,NH₃⁺自由基绕A₁₁方向作圆锥体运动.文中最后讨论了NH₃⁺自由基离子的可能生成机理。     

Magnetic properties of quasicrystals: Effects of disorder on Fe magnetic moment formation

Aluminum-based icosahedral quasicrystals display a wide variety of magnetic behaviors, which result from the presence of chromium, manganese, or iron. The formation of localized Fe magnetic moments in these materials is discussed in the context of the intrinsic disorder present in these structures as well as structural disorder caused by processing conditions.     

Hyperfine field distributions in ferromagnetic quasicrystals

Recent magnetisation measurements indicated the presence of ferromagnetism in Al−Cu−Mn−Ge quasicrystals with T_c∼535K. In this paper we report the room temperature Mossbauer and X-ray measurements of a series of ferromagnetic AlCuMnFeGe alloys.     

An57Fe Mössbauer effect study of the highT c superconductor GdBa2Cu3O7−y

Split source⁵⁷Fe Mössbauer effect spectroscopy has been performed between 4 K and 295 K on the superconducting perovskite GdBa₂Cu₃O_7?y. No evidence is seen for magnetic splitting at low temperatures as reported in some split absorder⁵⁷Fe Mössbauer experiments on this material. There is evidence for phonon mode softening, as observed for¹¹⁹Sn Mössbauer spectra of some other highT _c superconductors.     

Mössbauer studies of57Co-doped layered perovskites

Mössbauer spectra of⁵⁷Co-doped polycrystalline or single-crystal samples of layered perovskites La₂Mo₄ (M=Cu, Co, Ni) and R₂CuO₄ (R=Nd, Eu, Gd) were recorded at room temperature and below. Of the samples studied, only La₂CuO₄ shows a widely separated doublet at room temperature and a single clearly resolved sextet well belowT _N.