N-[2-(4-甲基)嘧啶基]-N′-2-硝基苯磺酰脲的合成、晶体结构、生物活性及其与酵母AHAS的分子对接

合成了磺酰脲化合物N-[2-(4-甲基)嘧啶基]-N′-2-硝基苯磺酰脲,用元素分析、红外、核磁共振氢谱对产物进行了表征,培养并测定了其晶体结构.晶体属三斜晶系,P1空间群,晶胞参数a=0.54159(1)nm,b=1.1533(3)nm,c=1.1857(4)nm,α=83.907(6)°,β=81.048(5)°,γ=77.637(4)°,V=0.7126(4)nm3,Dc=1.572g/cm3,Z=2,F(000)=348,R=0.0659,wR=0.1217.在晶体结构中,杂环上的一个N原子与脲桥上邻近的N原子上的H构成分子内氢键.测定了对酵母AHAS的离体抑制活性,其抑制常数Ki为(2.48±0.35)×10-7mol/L.用分子对接方法,将目标化合物晶体结构对接到靶酶酵母AHAS的活性位点,发现对接完毕目标化合物的构象与复合物晶体中的磺酰脲分子构象接近,并得到了合理的生物活性预测值.该研究为进一步理解磺酰脲类的分子结构、药物活性并设计新的分子提供了帮助和指导.     

The influence of chitin nanocrystals on structural evolution of ultra-high molecular weight polyethylene/chitin nanocrystal fibers in hot-drawing process

Ultra-high molecular weight polyethylene (UHMWPE)/chitin nanocrystal (CNC) fibers were prepared. Compared with the pure UHMWPE fibers, the ultimate tensile strength and Young’s modulus of UHMWPE/CNC fibers are improved by 15.7% and 49.6%, respectively, with the addition of chitin nanocrystals (CNCs) of 1 wt%. The melting temperature (T _m) of UHMWPE/CNC fibers was higher than that of pure UHMWPE fibers. Pure UHMWPE fibers and UHMWPE/CNC fibers were characterized with respect to crystallinity, orientation and kebab structure by wide-angle X-ray diffraction (WAXD), small-angle X-ray scattering (SAXS) and scanning electron microscopy (SEM). It is found that the CNCs act as the shish structure in UHMWPE/CNC fibers and the kebab crystals are grown around the CNCs. There was almost no difference between pure UHMWPE fibers and UHMWPE/CNC fibers in orientation. But the degree of crystallinity of various stages of UHMWPE/CNC fibers was respectively higher than the corresponding stage of pure UHMWPE fibers. Moreover, the addition of 1 wt% CNCs improved the thickness of kebab crystals and accelerated the transformation of kebab to shish.     

射流携带床反应器液体停留时间分布及模拟

对射流携带床液体停留时间分布进行了研究,考察了液体流量、气体流量和气体动量对液体停留时间分布的影响。结果表明,增加液体流量使停留时间分布密度曲线变得高而窄,且平均停留时间变短;气体流量增大使得停留时间出峰略有提前,气体流量大于4L/min时,继续增大气体流量对液体停留时间分布影响较小;当液体流量小于60L/h时,气体动量对液体停留时间的影响较明显,主要表现气体动量越大液体平均停留时间越长。基于实验结果分析及实验中观测的现象,将射流携带床内液体流动结构分为中心区和壁面区进行研究,建立了描述射流携带床内液体停留时间分布的数学模型,模型模拟结果和实验数据吻合良好。     

运动黏度在FLC薄膜-白油固液复合润滑体系中的作用

利用直流等离子体沉积技术制备了含氢类富勒烯碳膜(FLC),在工业级白油润滑条件下考察了FLC薄膜润湿性、摩擦学特性和白油运动黏度对整个固液复合润滑体系的影响。研究结果表明:在5~150 mm~2/s的考察范围内,白油的运动黏度越小,其对FLC薄膜的润湿性越好;随着运动黏度的增大,白油分子量增加且分子链变长,在薄膜表面油膜吸附增强,油膜厚度增加,FLC薄膜摩擦系数逐渐减小,于32 mm~2/s时达到最小值(0.114),随着黏度进一步增大,过高的运动黏度增加了黏性阻力和摩擦阻力,FLC薄膜摩擦系数反而上升;同时,FLC薄膜的磨损率随黏度增大而减小,当黏度超过26 mm~2/s之后,变化幅度趋缓。     

洁净核能源技术和D-Li强中子源的应用设想

在讨论国际科学界普遍关注的加速器驱动核动力装置技术,及其在未来洁净核能源开发和利用核嬗变方法处理核废料等方面的应用意义和可行性的同时,从我国的实际出发,提出了立足国内,利用中能（４０ＭｅＶ）、强流（２×１２５ｍＡ）质子加速器作Ｄ－Ｌｉ超强中子源,开展零功率加速器驱动核裂变装置技术的原理性研究和核嬗变、聚变材料、抗核加固及核物理研究,以及生产放射性同位素的初步设想. The accelerator driven nuclear power technology, as one of the most important scientific projects in the world, is evaluated. Some of its applications on transmuting nuclear waste, producing fission energy and doing scientific researches are also discussed. A proposal of using high intensity D Li fast neutron source as driven source of a zero power accelerator driven fission facility is outlined for the principle research and multi application purposes based on the present scientific...     

各向异性作用下合金定向凝固界面稳定性的渐近分析

采用渐近分析方法对考虑了界面能各向异性的单相二元合金平界面定向凝固过程进行了线性稳定性分析，得到了特定条件下的零级、一级渐近解，并通过对长波段渐近解的讨论得出了适用于整个波段的色散关系.分析表明零级渐近解等效于成分过冷理论，而一级渐近解则与M-S稳定性理论一致.在稳定状态控制参数(抽拉速度和温度梯度)的选择图中，界面能各向异性增大了不稳定区域，且在高速和高温度梯度时的影响更强.     

嘌呤衍生物在葫芦［6］脲单轮烷键合固定相上的色谱行为

在反相和正相色谱模式下,研究了几种嘌呤衍生物在葫芦［6］脲单轮烷键合硅胶固定相上的高效液相色谱行为,并在反相模式下与ODS固定相进行了比较,考察了流动相中甲醇含量、流动相pH值和离子强度对嘌呤化合物保留的影响。研究结果表明:在反相模式下,嘌呤化合物与葫芦［6］脲单轮烷键合相之间存在多种相互作用,除疏水作用外,分离过程中还存在与ODS不同的色谱分离机制。在正相条件下,多作用力的色谱分离机制同样存在。葫芦［6］脲单轮烷键合相与溶质之间存在疏水、氢键、π-π和偶极-偶极等多种作用力,协同作用提高了固定相对嘌呤化合物的分离选择性。     

iR降近于零的长光程薄层光谱电化学池的设计

ｉＲ降近于零的长光程薄层光谱电化学池的设计庞代文，王宗礼，张敏（武汉大学化学系，４３００７２）光谱电化学方法是光谱方法与电化学方法的有机结合，已成为将电化学研究层次提高到分子水平的强有力的手段。实现此方法的前提是先设计出简单方便的电化学接口，即光谱电...     

二苯基二氯硅烷与双酚-A的缩聚反应动力学

研究了二苯基二氯硅烷与双酚-A在等克分子比条件下的缩聚反应动力学。采用熔融缩聚时反应速率规律性复杂,结果无法处理;而用萘、二苯醚、苯乙酮等溶剂稀释至一定程度后,前期反应动力学呈现二级反应规律。当温度相同时,溶剂极性越大,反应速率越快;在一定温度范围内反应速率常数的对数与绝对温度的倒数标绘呈线性关系,获得在萘、二苯醚、苯乙酮中缩聚反应的活化能分别为:17.1千卡/克分子,24.8千卡/克分子,10.3千卡/克分子。Lewis碱及其盐对此反应有显著的催化效应。验证了缩聚反应过程中体系极性改变时,反应速率即发生对应的变化,阐明了熔融缩聚反应速率不稳定的原因。提出了反应系按S_N2机理进行。     

Transition to Film Boiling in Microgravity： Influence of Subcooling

The transition process to film pool boiling in microgravity is studied experimentally aboard the Chinese recoverable satellite S J-8. A quasi-steady heating method is adopted, in which the heating voltage is controlled to increase exponentially with time. Small, primary bubbles are formed and slid on the surface, which coalesce with each other to form a large coalesced bubble. Two ways are observed for the transition from nucleate to film boiling at different subcoolings. At high subcooling, the coalesced bubble with a smooth surface grows slowly. It is then difficult for the coalesced bubble to cover the whole heater surface, resulting in a special region of transition boiling in which nucleate boiling and local dry areas can coexist. In contrast, strong oscillation of the coalesced bubble surface at low subcooling may cause rewetting of local dry areas and activation of more nucleate sites, resulting in an abrupt transition to film boiling.