半制备高效液相色谱分离纯化芦荟素和异芦荟素

通过硅胶柱层析与半制备高效液相色谱从芦荟汁中分离纯化出芦荟素(98.79%)和异芦荟素(97.66%),UV、IR、MS、1H NMR鉴定化学结构.该方法分离条件简单,分离效果好,目标产物纯度与收率较高.     

A new class of quantum states generated by m-fold application of Bogoliubov＇s transformation

By applying higher powers of the Bogoliubov transformation operator b^{\dagger }=ν^*a+μ^*a^{\dagger } to the two-photon coherent states (or minimum uncertainty squeezed states) we construct a new type of quantum state which we call the generalized excited two-photon coherent states. Analytic expressions for the quantum statistical properties are derived, and through numerical computation the phase space quasi-probability distributions are found. These states can exhibit highly nonclassical behaviour depending on the degree of excitation m and other parameters. For particular values of two parameters λ and ρ, these generalized states reduce to other classes of coherent states formerly reported. Our theory thus presents a much broader approach to these types of quantum states.