线虫fat-1基因密码子优化设计

本研究旨在优化线虫fat-1基因,使其在牛肌肉组织中高效表达,为进一步生产fat-1转基因肉牛提供目的基因。试验在不改变fat-1基因编码氨基酸序列的基础上,参考了11个牛肌肉蛋白相关基因的密码子使用频率,对fat-1基因进行了密码子优化。结果发现,共改变了65个碱基,涉及65个密码子、7个氨基酸,约占fat-1基因总碱基数的5.38%,G+C含量从45.08%上升到50.04%,且分布均匀利于基因的表达。结构预测结果显示,该优化后的基因能够在牛肌肉中高效表达。     

军曹鱼MHC-Ⅱα基因全长cDNA的克隆及其组织表达分析

本研究根据其他鱼类MHC-Ⅱα基因的保守序列设计兼并引物,运用同源克隆和末端快速扩增方法扩增了军曹鱼MHC-Ⅱα基因的全长cDNA序列,并对cDNA及其氨基酸序列进行了分析,比较了军曹鱼和其他物种的MHC-Ⅱα氨基酸序列的差异,分析了军曹鱼MHC-Ⅱα基因的组织分布及经LPS刺激后头肾组织中MHC-Ⅱα基因的表达变化。结果表明,军曹鱼MHC-Ⅱα cDNA全长998 bp,包括53 bp的5′末端非编码区（5′UTR）、234 bp的3′末端非编码区（3′UTR）及711 bp的开放阅读框（ORF）,编码236个氮基酸,其蛋白质分子质量约为25.94 ku,等电点为4.39;军曹鱼MHC-Ⅱα蛋白质序列具有一些重要的特征,包括前导肽、α1、α2、CP/TM/CYT区和保守的半胱氨酸等;军曹鱼MHC-Ⅱα与鼠、人及其它鱼类的氨基酸同源性在25.0%～69.5%之间。Real-time PCR检测结果显示,MHC-Ⅱα基因在正常军曹鱼组织中均有表达,但其表达量在各种组织中存在差异,其中较强表达于头肾、鳃,中等程度表达于脾脏、肠,在心脏、脑、肌肉中表达较弱;经LPS刺激后,头肾中MHC-Ⅱα基因表达下调。     

畜禽基因组选择的研究进展

基因组选择（genomic selection,GS）是继标记辅助选择（marker-assisted selection,MAS）之后发展起来的新一代畜禽遗传评估的新方法。近年来,不少学者从各方面对GS在畜禽育种中的运用进行了研究,结果发现,与其他方法相比,GS优势明显,是当前畜禽遗传育种领域的研究热点。作者系统地阐述了GS估计染色体片段效应的方法及其准确性比较,详细介绍了影响GS准确性的因素、GS的经济效益,以及世界各国学者研究GS在实际育种中的应用情况,最后简述了中国畜禽育种开展GS策略所面临的挑战及其展望。     

Torsion behavior of Steel encased Concrete Composite Beams

In order to study torsion behavior of steel encased concrete composite beams, experiments were carried out with eight specimens. The destruction shape, working mechanism and the crack development and distribution were analyzed under pure torsion and combine torsion conditions. And also the relationships were investigated between torque and torsion ratio, load and strain, bending moment and deflection and load crack. On the basis of elasticity plastic theory, the formulas of cracking torsion were presented for pure torsion and combined torsion of combined beam. And with spatial truss model of variable angle, formulas for ultimate torsion strength of pure torsion and combined torsion were put forward. The predicted results were in good agreement with measured ones. The proposed formulas provided basis for evaluating safety and stability of the structural.     

Ultimate Bearing Capacity Analysis of High Strength Single Angle Compression Member Eccentrically at One End

To analyze mechanical behavior of Q460 high strength single angle steel struts with an eccentric load at one end in transmission towers, experimental analysis and theoretical calculation were carried out to study the overall stability and local buckling of members. Spherical hinge bearing and double knife edge bearing were applied at axial end of specimens. Influence of some factors on bearing capacity of compression members with eccentricities at both ends was analyzed, such as the end supporting conditions and residual stresses. It was shown that whether spherical hinge bearing or double knife edge bearing was used at axial end, the mechanical behavior can be accurately presented and the residual stresses affected the ultimate load carrying capacity by about 5％ or less. Compared with different methods, such as experiment method、finite element method, method in the Guide for American Design of Latticed Steel Transmission Structure（ASCE101997）and method in Chinese Technical Regulation of Design for Tower and Pole Structure of Overhead Transmission Line (DL/T51542002), it was found that the calculated strength of high strength steel member by standard calculation method in DL/T51542000 was over conservative. According to the research results, the revised formulas of ASCE were proposed with dividing actual material strength by the resistance coefficient of rR=1.111. Therefore, the experimental results can provide reference for designing high strength Q460 single angle steel members compressed eccentrically at one end.     

A Land Use Model for Urban Rail Station Area Planning Based on TOD Strategy

Transit oriented development (TOD) presents a sustainable urban development strategy by creating an efficient integration of land use and public transit. A TOD planning model for the land use of urban rail station area was explored by means of a multiple objective mathematical programming model. Three objectives were considered: encouraging transit system volume, promoting livable communities, and balancing land use. The model can easily be solved by transforming it into a linear multi programming problem. The Xujiahui rail rapid transit station area in Shanghai is chosen as case study to illustrate the model application and planning results. The result indicates that the model would be efficient in practice.     

Experimental Analysis of Construction Time Space Effect for Large Span and Flat Multi Arch Tunnel

For the large span and flat, together with the interaction effect of construction and disturbance of surrounding rock, the mechanical of large span and flat multi arch tunnel is very complicated, and the time space effect is different from that of two lane multi arch tunnel or separated tunnel. Adopting the “CTSSSRH”, the 3 D dynamic process of the tunnel construction was simulated. Analyzing the rule of surrounding rock displacement and stress with excavation, the time space effect of large span and flat multi arch tunnel was proposed.     

Safety Assessment of Circular Arches Tunnel Evacuation on Surrounding Geotechnical Environment

Based on the stochastic medium theory, influence on the surrounding rock and soil by tunnel excavation was studied. formula for predicting movement and deformation of rock and soil mass caused by tunnelling were deduced. And especially for the tunnel with circular arch section, half analytic solution for this problem was put forward. Furthermore, a program was developed to compute the movement and deformation of the rock and soil mass resulted from excavation. The deformation failure criterion of stochastic medium for estimating the surroundings safety was provided and was applied in an engineering example, which proved that the results of the research were reasonable and significant for the tunnel safety construction.     

A Highly Activated Mineral Admixture Slurry Consisting of a Wet discharged Fly ash and Carbide Lime Composite

To recycle wet discharged fly ash and carbide lime effectively, a highly activated mineral admixture slurry consisting of both these components was investigated. The preparation technology of mineral admixture slurry made from a composite of wet discharged fly ash and carbide lime and the strengths, hydration products change (XRD, SEM) of cement paste made by the slurry were studied. The results indicate that the optimal proportion between wet discharged fly ash and carbide lime (solid content) is 75:25 in the process of wet milling preparation. The alkaline environment provided by carbide lime with high Ca(OH)2content and cement hydration accelerated by modified agents can promote early activation of fly ash, and accelerate its secondary hydration reaction.     

Damage Evolution and Acoustic Emission Character of Coalrock under Unloading Condition

The damage failure mechanisms of coalrock under unloading condition during deep mining is different from those under traditional loading condition, starting from the unloading condition position to study the dynamic disaster of coalrock has become a new direction in the disaster study. The rock mechanics electrohydraulic servo test system (MTS815) and acoustic emission system (8CHS PCI 2) are used to study the coalrock deformation damage and acoustic emission (AE) characteristics. The results show that the failure of coalrock under unloading condition exhibits strong brittleness and happens in sudden and is mostly of tensile shear failure type. The evolution curve of cumulative ring down count of acoustic emission can better reflect the coalrock unloading damage evolution process, and the whole unloading failure process can be divided into three stages: the stage of damage weakening, damage stably development stage and the stage of accelerated damage development. During the mining process the confining pressure of the coalrock is unloaded, the coalrock rapidly arrives at the third stage of the whole unloading failure process, and the damage is accumulated rapidly and the fracture failure of coalrok occurred suddenly, then follows the coalrock dynamic disaster.