应用间接排序识别盐沼植被的光谱特征:以崇明东滩为例

遥感技术已成为大尺度植被分类的重要手段,而地面植物群落特征与其光谱特征之间的关系是解译遥感影像的关键。该研究选择上海崇明东滩自然保护区的盐沼植物群落为对象,应用ASD地物光谱仪测定其植物群落的光谱反射率,并采用10个小型机载成像光谱仪(CASI)默认植被波段组,应用主分量分析法和相关分析分析了不同群落光谱特征与生态环境因子之间的关系。分析结果表明,间接排序法PCA能够识别盐沼植被中光滩、海三棱 草(Scirpus mariqueter)群落、芦苇(Phragmites australis)群落和互花米草(Spartina alterniflora)等群落的光谱特征,绝大多数盐沼湿地植物群落组成与光谱特征之间有显著的相关,识别效果最好的波段组是736~744 nm、746~753 nm、775~784 nm、815~824 nm和860~870 nm;对光谱反射率影响最大的生态环境因子分别是植物群落的高度和盖度,高程和其它环境因子的影响次之。研究成果可为遥感监测崇明东滩自然保护区内入侵种互花米草的空间分布和扩散规律提供技术支撑,为高光谱遥感影像的影像判读和解译分类以及盐沼湿地植被制图提供科学依据。     

Three decades of listeriology through the prism of technological advances

Decades of breakthroughs resulting from cross feeding of microbiological research and technological innovation have promoted Listeria monocytogenes to the rank of model microorganism to study host–pathogen interactions. The extraordinary capacity of this bacterium to interfere with a vast array of host cellular processes uncovered new concepts in microbiology, cell biology and infection biology. Here, we review technological advances that revealed how bacteria and host interact in space and time at the molecular, cellular, tissue and whole body scales, ultimately revolutionising our understanding of Listeria pathogenesis. With the current bloom of multidisciplinary integrative approaches, Listeria entered a new microbiology era.     

地尔硫卓手性中间体合成进展

地尔硫卓是重要的心血管药物,在其分子结构中含有2个手性中心,可产生4个立体异构体,其中只有（2s,3s）-异构体具有药理活性,因此其立体选择性合成具有很大的挑战性。研究人员采用多种方法合成单一构型的地尔硫卓手性中间体,其中包括化学拆分、化学不对称合成以及化学-酶法合成等方法。对地尔硫卓手性中间体的制备方法进行了综述。     

基于图像几何变换映射的色盲矫正方法

为了提高色盲患者分辨色彩的能力,提出了基于图像几何变换映射的色盲矫正方法。首先根据图像中颜色面两侧的颜色比例对颜色空间各个平面进行相应的几何变换,进而划分不同的颜色映射区域,通过颜色变换,生成色盲患者较易分辨颜色的图像。实验表明,该方法可以改善色盲患者对原本难以区分的颜色的分辨能力,同时计算速度快,有望满足实时处理的需要,性能上优于已有的方法。     

Preparation of (2S, 3R)-methyl-3-phenylglycidate using whole cells of Pseudomonas putida

Preparation of (2S, 3R)-methyl 3-phenylglycidate via enantioselective hydrolysis of racemic phenylglycidate was carried out using whole cells of Pseudomonas putida. Under optimal conditions (2S, 3R)-methyl-3-phenylglycidate could be got with ee value 99 and 48% chemical yield.     

Thermostable red and green light-producing firefly luciferase mutants for bioluminescent reporter applications

Light emission from the North American firefly Photinus pyralis, which emits yellow-green (557-nm) light, is widely believed to be the most efficient bioluminescence system known, making this luciferase an excellent tool for monitoring gene expression. We present studies on the production of a set of thermostable red- and green-emitting luciferase mutants with bioluminescent properties suitable for dual-color reporter assays, biosensor measurements with internal controls, and imaging techniques. Starting with the luciferase variant Ser284Thr, we introduced the mutations Thr214Ala, Ala215Leu, Ile232Ala, Phe295Leu, and Glu354Lys to produce a new red-emitting enzyme with a bioluminescence maximum of 610 nm, narrow emission bandwidth, favorable kinetic properties, and excellent thermostability at 37 degrees C. By adding the same five changes to luciferase mutant Val241Ile/Gly246Ala/Phe250Ser, we produced a protein with an emission maximum of 546 nm, providing a set of thermostable enzymes whose bioluminescence maxima were separated by 64 nm. Model studies established that the luciferases could be detected at the attomole level and six orders of magnitude higher. In microplate luminometer format, mixtures containing 1.0 fmol total luciferase were quantified from measurements of simultaneously emitted red and green light. The results presented here provide evidence that it is feasible to monitor two distinct activities at 37 degrees C with these novel thermostable proteins.     

用于可视化光治疗的Mn3O4@CuS纳米粒的制备研究

摘要 目的：本研究旨在制备用于肿瘤可视化光治疗的多功能Mn₃O₄@CuS核壳型纳米粒,在磁共振成像的引导下,使用近红外光定点辐照,实现局部光热消融治疗。方法：（1）采用高温热解法制备油胺稳定的Mn₃O₄纳米粒,在其表面构建CuS壳层,并进行聚乙二醇修饰,得到分散于水相中的Mn₃O₄@CuS核壳型纳米粒。（2）通过透射电镜、紫外可见近红外吸收光谱等方法对该纳米粒进行理化性质表征,并研究其体外磁共振成像、光热升温等性能。结果：制备的水相分散的Mn₃O₄@CuS纳米粒,粒径均一且分散性较好,形态为近圆形,粒径为9.30±2.29 nm;紫外可见近红外吸收光谱图表明Mn₃O₄@CuS纳米粒在近红外区有较强吸收,最大吸收峰位于1100~1200 nm范围;磁共振成像分析结果可计算出Mn₃O₄@CuS纳米粒的纵向弛豫率r1为1.662 mM^-1s^-1,表明其具有较好的磁共振增强造影效果;光热升温曲线显示Mn₃O₄@CuS纳米粒可在785 nm近红外激光下升温至73.5 ℃,具备较好的光热治疗潜力。结论：本文成功制备出水相分散的Mn₃O₄@CuS核壳型纳米粒,具有良好的磁共振造影成像性能和光热升温效应,有望应用于磁共振成像引导下的肿瘤可视化光治疗。     

痛觉的脑功能成像研究进展

本文综述了近年来关于痛觉功能性脑成像的研究进展,痛觉的感觉辨别成分似与外侧丘脑、初级和次级躯体感觉区及岛叶皮层有关,而伤害性信息的认知－注意过程则与顶叶后部和前额中皮层有关。扣带回的不同部分调节着痛觉认知和情感的不同方面。文章最后对临床各种疼痛特别是神经源性痛病人的成像研究进行了分析。     

Resolution of N-(2-ethyl-6-methylphenyl) alanine catalyzed by Lipase B from Candida antarctica

A biotransformation process has been developed for the production of (S)-N-(2-ethyl-6-methylphenyl) alanine by enantioselective hydrolysis of racemic methyl ester in the presence of Candida antarctica lipase B (CAL-B). However, the enantioselectivity of CAL-B towards the resolution is not high enough to obtain enantiomerically pure product. In order to improve the enantioselectivity of the enzyme, the effects of surfactants on CAL-B-catalyzed hydrolysis were tested. The results suggest that surfactants can influence the microenvironment of the enzyme, and the addition of Tween-80, in particular, to the reaction medium markedly enhanced the selectivity of CAL-B towards the substrate used, with the enantiomeric ratio (E-value) increasing from 11.3 to 60.1.     

水-有机溶剂介质中固定化不动杆菌细胞催化拆分(RS)-环戊烯酮乙酸酯的研究

不动杆菌CGMCC 0789的海藻酸凝胶包埋固定化细胞可高对映选择性地水解拆分环戊烯酮(简称HMPC)乙酸酯.异丙醇对固定化细胞的活力和对映选择性有显著提高.反应体系中异丙醇浓度为10%(体积分数,全文同)时,固定化细胞的活力最高,为6.22 mmol/(L·min·g)细胞干重,是未添加异丙醇的对照组的150%.此时E值为94±6,是对照组的1.7倍.以光学纯环戊烯酮乙酸酯为底物,对部分纯化的不动杆菌酯酶进行了动力学考察.通过动力学参数推算,10%异丙醇存在时,酯酶的对映选择性(E值)为36.5,是空白的2.3倍.10%异丙醇存在下,固定化细胞仍具有良好的操作稳定性.连续反应10批,固定化细胞的活力保持良好.