Alcohol dehydrogenase 2 is a major hepatic enzyme for human retinol metabolism

The metabolism of all-trans- and 9-cis-retinol/ retinaldehyde has been investigated with focus on the activities of human, mouse and rat alcohol dehydrogenase 2 (ADH2), an intriguing enzyme with apparently different functions in human and rodents. Kinetic constants were determined with an HPLC method and a structural approach was implemented by in silico substrate dockings. For human ADH2, the determined K_m values ranged from 0.05 to 0.3 μM and k_cat values from 2.3 to 17.6 min⁻¹, while the catalytic efficiency for 9-cis-retinol showed the highest value for any substrate. In contrast, poor activities were detected for the rodent enzymes. A mouse ADH2 mutant (ADH2Pro47His) was studied that resembles the human ADH2 setup. This mutation increased the retinoid activity up to 100-fold. The K_m values of human ADH2 are the lowest among all known human retinol dehydrogenases, which clearly support a role in hepatic retinol oxidation at physiological concentrations. Received 12 October 2006; received after revision 6 December 2006; accepted 8 January 2007     

水上交通安全信息处理中的神经网络技术

由于航道信息环境的复杂化 ,使得现代水上交通安全面临着很多严重问题。解决这些问题的出路在于采用先进的信息处理理论和技术 ,而神经网络就是一个最佳的选择。研究分析表明 ,神经网络在水上目标的雷达、红外和声纳检测 ,识别 ,跟踪 ,水上交通安全信息融合 ,船舶避碰决策支持等方面 ,具有良好的应用前景     

红外焦平面阵列非均匀校正算法研究

红外图像的非均匀性已经成为制约红外焦平面阵列成像质量的限制性因素。本文对红外非均匀性的定义和来源进行了深入的探讨,给出了几种非均匀校正算法及其实验结果,最后对各种校正算法的特点进行了归纳总结。     

中国明代弹道学史料的考辨与述评

对明代火器文献进行分析,认为学术界关于“中国古代弹道知识是由西方传来”之说值得商榷．中国弹道学知识的形成有其自身的特点,初步形成了能在一定程度上反映火器命中技术发展规律的弹道理论,在中国火器弹道科学思想史上占有重要地位．     

半连续法制备核壳型苯丙聚合物乳液的研究

实验采用预乳化工艺和半连续种子乳液聚合技术合成了具有核/壳结构的苯丙乳液,粒径分布均匀,性能优越,适用于涂料、粘连剂、油墨等领域。研究了核壳型结构对乳液MFT的影响,讨论了乳化剂用量、引发剂用量、PH值的调节等因素对乳液性能的影响。     

纤维素在ZnCl_2水溶液中的溶解性能及再生结构

比较了不同质量分数的ZnCl2水溶液溶解不同聚合度纤维素的能力,发现:质量分数为65.0%以下的ZnCl2水溶液不能溶解纤维素;当ZnCl2水溶液的质量分数达到或超过65.0%时,未被水分子饱和的Zn2+可与纤维素分子链作用,使纤维素溶解,且65.0%的ZnCl2水溶液的溶解效果最佳;随着纤维素聚合度的增大,其溶解性能下降;经ZnCl2水溶液溶解后的再生纤维素的聚合度下降.广角X-射线衍射(WAXD)分析表明再生纤维素为纤维素Ⅱ结晶变体;傅里叶变换红外光谱(FT-IR)显示ZnCl2水溶液是纤维素的非衍生化溶剂,且再生纤维素分子内的氢键减弱.     

扶沟至西华高速公路路基路面排水设计

根据平原区实际状况,结合扶沟至西华高速公路的实际特点,详细阐述了本条高速公路路基、路面及分隔带排水设计要点及思路,为平原区高速公路排水设计积累了经验.     

公路桥梁桩端后压浆灌注桩技术研究

结合后压浆灌注桩与常规灌注桩静载对比试验,分析了桩端压浆灌注桩作用机理及后压浆对单桩轴向受压承载力容许值增大的贡献.     

Principle and realization method of tunnel deformation detection based on image recognition and data transmission technology

<正>To detect the deformation of the tunnel structure based on image sensor networks is the advanced study and application of spatial sensor technology.For the vertical settlement of metro tunnel caused by internal and external stress after its long period operation,the overall scheme and measuring principle of tunnel deformation detection system is introduced. The image data acquisition and processing of detection target are achieved by the cooperative work of image sensor,ARM embedded system.RS485 communication achieves the data transmission between ARM memory and host computer.The database system in station platform analyses the detection data and obtains the deformation state of tunnel inner wall,which makes it possible to early-warn the tunnel deformation and take preventive measures in time.     

植物RNA病毒寄主因子基因的研究进展

文章综述了植物RNA病毒寄主因子基因的研究进展.