低碳城市的空间形态探索——以恩施市为例

城市空间形态研究的价值在于它在城市动态变化的过程中适当安排新的结构元素的能力,评价规划工作的优劣在某种意义上是指得到规划许可的城市发展的结果。因此,城市空间形态的研究对辅助与充实城市总体规划实践具有重要意义。低碳城市空间形态研究,可以对连片发展的城市形态、带形城市以及组团城市形态各自在减少碳排放方面进行评估,从而得出理想的城市空间形态。     

基于变分法的光子超导波基态分析

利用一般的电磁辐射与晶格振动的相互作用模型，研究了强光场与晶格振动的非线性相互作用导致光子对形成这一基本问题，导出了光子．光子有效相互作用。然后利用变分法求得了超导波态系统的基态能量表达式，并讨论了光子对的形成条件。     

钛合金整体叶盘叶型精密振动电解加工实验研究

针对钛合金整体叶盘叶栅通道狭窄、叶片型面复杂、扭转角度大等特点,采用片状电极对叶片型面进行双面同步精密振动电解加工。分析了电解加工参数对叶片加工精度和表面质量的影响,通过正交试验确定了合理的工艺参数,实现了整体叶盘的叶片叶身型面、根部R角及叶间流道的一次电解成形,型面误差为-0.023~0.040 mm,表面粗糙度为Ra0.53μm,达到了设计要求。对电解加工叶片型面试件的组织形貌进行扫描电镜观察,未发现晶间腐蚀和选择性腐蚀造成的点蚀现象。     

溶组织梭状芽孢杆菌胶原蛋白酶的研究进展

胶原蛋白是哺乳动物体内含量最丰富的蛋白质之一,因具有特殊的三股螺旋结构而不易被普通蛋白酶水解。胶原蛋白酶可在生理条件下特异性识别切割胶原蛋白,在医药、食品等工业领域应用广泛,其中以源自溶组织梭状芽孢杆菌的胶原蛋白酶研究较多。本文主要对来自溶组织梭状芽孢杆菌的胶原蛋白酶（collagenase,Col）G和ColH的结构特征、水解机理、生产现状和实际应用等方面进行概括总结,以期为胶原蛋白酶的进一步发展和利用提供理论参考依据。     

整体叶盘电解旋转套料加工实验研究

为了提高整体叶盘的加工效率、降低加工成本,开展了整体叶盘扭曲叶片电解预加工实验研究。通过分析叶型结构及对电极片内孔尺寸进行理论计算,设计了整体式加工阴极,并针对TC17钛合金材料开展了加工实验。结果表明:采用整体式加工阴极的电解加工方法能一次性去除大部分金属,实现整体叶盘大扭曲叶片的小余量一次性成形加工,叶型单边最小余量为2 mm。     

Chromosomal Engineering of Escherichia coli for Efficient Production of Coenzyme Q10

The plasmid-expression system is routinely plagued by potential plasmid instability. Chromosomal in-tegration is one powerful approach to overcome the problem. Herein we report a plasmid-free hyper-producer E. coli strain for coenzyme Q10 production. A series of integration expression vectors, pxKC3T5b and pxKT5b, were constructed for chemically inducible chromosomal evolution （multiple copy integration） and replicon-free and markerless chromosomal integration （single copy integration）, respectively. A coenzyme Q10 hyper-producer Es-cherichia coli TBW20134 was constructed by applying chemically inducible chromosomal evolution, replicon-free and markerless chromosomal integration as well as deletion of menaquinone biosynthetic pathway. The engineered E. coli TBW20134 produced 10.7 mg per gram of dry cell mass （DCM） of coenzyme Q10 when supplemented with 0.075 g·L^-1 of 4-hydroxy benzoic acid;this yield is unprecedented in E. coli and close to that of the commercial producer Agrobacterium tumefaciens. With this strain, the coenzyme Q10 production capacity was very stable after 30 sequential transfers and no antibiotics were required during the fermentation process. The strategy presented may be useful as a general approach for construction of stable production strains synthesizing natural products where various copy numbers for different genes are concerned.     

振动电解加工脉冲参数对TC17钛合金成形质量的影响研究

通过振动电解加工TC17钛合金浅孔,研究了振动电解加工脉冲参数对浅孔中心凸台成形精度及凸台顶部非加工面杂散腐蚀的影响,并利用ANSYS软件进行加工区域电场分析。结果表明:TC17钛合金非加工表面易受杂散腐蚀,在电流密度约10 A/cm2时会发生点蚀;脉冲宽度是影响TC17钛合金电解加工精度和质量的主要参数,随着脉宽减小,凸台底部直径更接近电极内孔直径,凸台锥度显著降低,同时非加工面杂散腐蚀明显减弱,而单纯增大脉间宽度效果并不明显。     

数字音频水印技术的仿真研究

数字水印的基本功能是将产权、产品的标识码以及购买者的信息等嵌入到数字媒体中。用小波变换的方法对数字音频的水印的嵌入和提取做了仿真研究,仿真结果表明该方法是可行的。     

多策略代谢工程大肠杆菌高效生产辅酶Q10

Escherichia coli BW25113 was metabolically engineered for CoQ10 production by replacing ispB with ddsA from Gluconobacter suboxydans. Effects of precursor balance and reduced nicotinamide-adenine dinucleotide phosphate (NADPH) availability on CoQ10 production in E. Coli were investigated. The knockout of pykFA along with pck overexpression could maintain a balance between glyceraldehyde 3-phosphate and pyruvate, increasingCoQ10 production. Replacement of native NAD-dependent gapA with NADP-dependent gapC from Clostridium acetobutylicum, together with the overexpression of gapC, could increase NADPH availability and then enhanced CoQ10 production. Three effects, overcxpressions of various genes in CoQ biosynthesis and central metabolism,different vectors and culture conditions on CoQ10 production in E. Coli, were all investigated. The investigation of different vectors indicated that low copy number vector may be more beneficial for CoQ10 production in E. Coli.The recombinant E. Coli (AispB::ddsA, ApykFA and ΔgapA::gapC), harboring the two plasmids encoding pck, dxs,idi and ubiCA genes under the control of PT5 on pQE30, ispA, ddsA from Gluconobacter suboxydans and gapC from Clostridium acetobutylicum under the control of PBAD on pBAD33, could produce CoQ10 up to 3.24 mg.g-1 dry cell mass simply by changing medium from M9YG to SOB with phosphate salt and initial culture pH from 7.0 to 5.5. The yield is unprecedented and 1.33 times of the highest production so far in E. Coli.     

多策略代谢工程大肠杆菌高效生产辅酶Q10

Escherichia coli BW25113 was metabolically engineered for CoQ10 production by replacing ispB with ddsA from Gluconobacter suboxydans.Effects of precursor balance and reduced nicotinamide-adenine dinucleotide phosphate (NADPH) availability on CoQ10 production in E.coli were investigated.The knockout of pykFA along with pck overexpression could maintain a balance between glyceraldehyde 3-phosphate and pyruvate,increasing CoQ10 production.Replacement of native NAD-dependent gapA with NADP-dependent gapC from Clostridium acetobutylicum,together with the overexpression of gapC,could increase NADPH availability and then enhanced CoQ10 production.Three effects,overexpressions of various genes in CoQ biosynthesis and central metabolism,different vectors and culture conditions on CoQ10 production in E.coli,were all investigated.The investigation of different vectors indicated that low copy number vector may be more beneficial for CoQ10 production in E.coli.The recombinant E.coli (△ispB::ddsA,△pykFA and △gapA::gapC),harboring the two plasmids encoding pck,dxs,idi and ubiCA genes under the control of PT5 on pQE30,ispA,ddsA from Gluconobacter suboxydans and gapC from Clostridium acetobutylicum under the control of PBAD on pBAD33,could produce CoQ10 up to 3.24 mg·g-1 dry cell mass simply by changing medium from M9YG to SOB with phosphate salt and initial culture pH from 7.0 to 5.5.The yield is unprecedented and 1.33 times of the highest production so far in E.coli.