用三比特海森堡XXZ自旋环实现量子隐形传态

论文主要研究磁场和Dzyaloshinskii-Moriya(DM)相互作用对以三比特海森堡XXZ自旋链为量子信道进行隐形传态的影响。通过平均保真度的解析表达式分析了不同参数对量子隐形传态的影响,我们发现各向同性参数和各向异性参数对隐形传态起积极的作用,但是磁场和DM相互作用参数却表现出消极的作用。此外,这个模型中只有FM中的平均保真度可以超过经典最大值。     

Induction of somatic hypermutation in immunoglobulin genes is dependent on DNA polymerase iota

Somatic hypermutation of immunoglobulin genes is a unique, targeted, adaptive process. While B cells are engaged in germinal centres in T-dependent responses, single base substitutions are introduced in the expressed Vh/Vl genes to allow the selection of mutants with a higher affinity for the immunizing antigen. Almost every possible DNA transaction has been proposed to explain this process, but each of these models includes an error-prone DNA synthesis step that introduces the mutations. The Y family of DNA polymerases--pol eta, pol iota, pol kappa and rev1--are specialized for copying DNA lesions and have high rates of error when copying a normal DNA template. By performing gene inactivation in a Burkitt's lymphoma cell line inducible for hypermutation, we show here that somatic hypermutation is dependent on DNA polymerase iota.     

Mutations in ENPP1 are associated with 'idiopathic' infantile arterial calcification

Idiopathic infantile arterial calcification (IIAC; OMIM 208000) is characterized by calcification of the internal elastic lamina of muscular arteries and stenosis due to myointimal proliferation. We analyzed affected individuals from 11 unrelated kindreds and found that IIAC was associated with mutations that inactivated ecto-nucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1). This cell surface enzyme generates inorganic pyrophosphate (PP(i)), a solute that regulates cell differentiation and serves as an essential physiologic inhibitor of calcification.     

炭化对聚丙烯腈/酚醛基炭/炭复合材料结构和力学性能影响

由湿法叠涂制得的聚丙烯腈(PA N )/酚醛基碳/碳(C/C )复合材料在高性能结构材料领域具有应用潜力.为了了解炭化步骤对聚丙烯腈/酚醛基碳/碳复合材料结构和力学性能的影响 ,进行了层间断裂韧性(模式Ⅱ)测试.由于结构特征与裂纹形成机理的相互关系对C/C-SiC复合材料的制备很重要 ,采用阿基米德方法、扫描电子显微镜(SEM )和三点弯曲试验对复合材料的结构进行表征.实验结果显示 ,碳/碳(C/C)试件的层间断裂韧性为碳纤维增强酚醛塑料(CFRP)试件的59.7%.     

含过量Fe和Si的铸态Al–Cu合金的拉伸性能和热裂敏感性

This study was undertaken to investigate the tensile properties and hot tearing susceptibility of cast Al–Cu alloys containing excess Fe (up to 1.5wt%) and Si (up to 2.5wt%). According to the results, the optimum tensile properties and hot tearing resistance were achieved at Fe/Si mass ratio of 1, where the α-Fe phase was the dominant Fe compound. Increasing the Fe/Si mass ratio above unity increased the amounts of detrimental β-CuFe platelets in the microstructure, deteriorating the tensile properties and hot tearing resistance. Decreasing the mass ratio below unity increased the size and fraction of Si needles and micropores in the microstructure, also impairing the tensile properties and hot tearing resistance. The investigation of hot-torn surfaces revealed that the β-CuFe platelets disrupted the tear healing phenomenon by blocking interdendritic feeding channels, while the α-Fe intermetallics improved the hot tearing resistivity due to their compact morphology and high melting point.