Lower Energy α Elastic Scattering on ^20Ne and Anomaly of α＋^20Ne Scattering System

The α+²⁰Ne elastic scattering angular distributions at lower incident energies of Eα= 12.7--31.1 MeV have been analyzed by using the α-folding potential based on the α+¹⁶O structure model of the ²⁰Ne nucleus. The α-folding potential with a standard Woods-Saxon type imaginary part, can reasonably describe experimental cross sections and the anomalous large angle scattering (ALAS) features. The anomaly of the α+²⁰Ne scattering system is further confirmed in the lower incident energy region.     

Phasing of lysozyme using one－wavelength anomalous scattering of sulphur atoms through the combination of direct methods and density modification

A new method of combining one-wavelength anomalous scattering (OAS) phasing and density modification has been described, in which the improved phases from density modification axe re-introduced into OAS phasing. In this way, the phases could be improved iteratively until convergence. The OAS phasing method is based on the previously established sign-probability formula, which breaks the phase ambiguity in the OAS phasing. The implementation of this method has been available in CCP4 as OASIS. This method, although based on direct-methods, could also incorporate known phases and figures of merit into its sign-probability formula. In the implementation of OASIS, the known phases axe from the positions of the anomalous scatters. In the current method, the known phases are from the density modification. The current method was tested on phasing a lysozyme crystal using anomalous scattering of sulphur atoms with diffraction data collected on an in-house x-ray source. The resulting map was well connected for the backbone atoms and clearly traceable, with an average map correlation coefficient of 0.6622 for the backbone atoms.     

由透射波的摇摆曲线求GaAs中Ga的反常散射因数

利用同步辐射光，在对称Ｌａｕｅ情况下，于Ｇａ的Ｋ吸收限附近，测定了ＧａＡｓ（２００）的衍射波和透射波的摇摆曲线．通过测定的透射波的摇摆曲线和Ｘ射线衍射动力学理论的相应计算结果的定量比较，求得ＧａＡｓ中的Ｇａ原子在其Ｋ吸收限附近的反常散射因数 关键词：     

晶体衍射分析方法

<正>在自然界中,同样是化学元素碳,石墨漆黑而柔软,金刚石却剔透而坚硬。同样是化学元素磷,白磷剧毒而易燃,红磷却无毒而且更加稳定(图1)。这是由于他们微观上的原子排列方式不同而造成宏观上化学和物理性质的差异。同为胰岛素,人胰岛素和牛、猪的胰岛素其氨基酸组成有着明显的差异,但是却执行相同的生物化学功能(图2)。这是由于他们有共同的结构特征。大量的科学事实表明,物质的宏观性     

同步辐射中的蛋白质结构和功能研究

<正>20世纪后半叶发展最迅速的一个学科是结构生物学,这是一门通过蛋白质结构来诠释蛋白质功能的学科,DNA双螺旋结构和血红蛋白以及肌红蛋白的结构的确定标志着这个学科的建立。蛋白质是生命活动主要的执行者,只有形成了正确的结构,蛋白质才能具有正确的功能。因此蛋白质的结构研究,不仅可以让我们得以深入了解生物体内诸多生命过程的细节,更有助于重大疾病的预防和治疗、新型高效药物和疫苗