Functional imaging with cellular resolution reveals precise micro-architecture in visual cortex

Neurons in the cerebral cortex are organized into anatomical columns, with ensembles of cells arranged from the surface to the white matter. Within a column, neurons often share functional properties, such as selectivity for stimulus orientation; columns with distinct properties, such as different preferred orientations, tile the cortical surface in orderly patterns. This functional architecture was discovered with the relatively sparse sampling of microelectrode recordings. Optical imaging of membrane voltage or metabolic activity elucidated the overall geometry of functional maps, but is averaged over many cells (resolution >100 microm). Consequently, the purity of functional domains and the precision of the borders between them could not be resolved. Here, we labelled thousands of neurons of the visual cortex with a calcium-sensitive indicator in vivo. We then imaged the activity of neuronal populations at single-cell resolution with two-photon microscopy up to a depth of 400 microm. In rat primary visual cortex, neurons had robust orientation selectivity but there was no discernible local structure; neighbouring neurons often responded to different orientations. In area 18 of cat visual cortex, functional maps were organized at a fine scale. Neurons with opposite preferences for stimulus direction were segregated with extraordinary spatial precision in three dimensions, with columnar borders one to two cells wide. These results indicate that cortical maps can be built with single-cell precision.     

A new type of mutant ofEuglena which produces permanently bleached progeny by darkness

Summary A new type of mutant ofEuglena gracilis strain Z was isolated. In the light-grown culture, it contains 5–20% of bleached cells which have irreversibly lost the ability of chloroplast formation. When once grown in the dark, differing from the case with the wild type, it segregates only bleached cells, probably due to the inability of the replication of proplastids in darkness. Cell multiplication under the inhibition of chlorophyll synthesis or photosynthesis in the light also produces bleached cells.     

含笼型倍半硅氧烷(POSS)的双重敏感性聚合物的合成及其自组装研究

通过两次原子转移自由基聚合(ATRP)制备了含有笼型倍半硅氧烷(POSS)的温度和pH双重敏感的两亲性聚合物POSS-PMEO2MA-b-PDMAEMA,并采用GPC和1H-NMR对引发剂和聚合物的化学结构进行了表征。利用动态光散射(DLS)、荧光光谱仪、透光率测试等手段研究了聚合物在水溶液中的自组装。结果表明,在较低温度下聚合物在水中自组装形成球形胶束,温度高于临界溶解温度(LCST)后,胶束脱水发生聚集,形成更大尺寸的聚集体;调整溶液的p H值为9时,聚合物的浊点温度下降;聚合物胶束的尺寸随着pH值的升高而减小。通过改变温度和pH值都能调控聚合物在水中的自组装形态。     

溴甲酚绿法测定盐酸美金刚缓释胶囊的释放度

建立了一种简便灵敏的用于测定盐酸美金刚缓释胶囊释放度的分析方法。采用溶剂萃取酸性染料比色法来测定盐酸美金刚缓释胶囊的释放度,染色剂选用溴甲酚绿(BCG),萃取剂为氯仿,通过改变水相p H、BCG试液用量、反应时间等条件对比色法的测定条件进行优化。结果显示,当水相p H=4.0、溴甲酚绿试液用量为4 m L时,本方法在0.3~12μg/m L质量浓度范围内具有较高的灵敏度和重复性,标准曲线为A=0.05347ρ+0.09001,r=0.9991(n=6);盐酸美金刚平均回收率为100.13%,相对标准偏差为1.86%(n=9)。     

基于空间像素强度的脑瘤图像检索方法

针对脑瘤图像提出一种基于内容的检索方法. 首先采用图像膨胀算法增强脑瘤图像的感兴趣区域(ROI); 然后基于点的空间像素强度的特征提取方法, 描述脑瘤图像增强后的ROI局部特征; 最后引入聚合特征算法提高图像特征的辨别能力和压缩能力. 实验对比3种脑瘤图象检索方法的结果表明, 该算法可得到较高的检索精确度, 可实现高效、 准确的脑瘤图像检索.     

温度和含水率对银中杨-玉簪落叶与草坪碎屑混料腐解的影响

用室内培养法对银中杨 玉簪落叶与草坪碎屑混料进行好氧腐解, 在不同温度和含水率下分析二者对混料腐解过程中水溶性物质、 可提取腐殖酸、 胡敏酸和胡敏素的碳质量比（WSOC, w_C(HE),w_C(HA),w_C(Hu)）、 胡敏酸（HA）碱溶液E₄/E₆及胡富比（w_C(HA)/w_C(FA)）的影响. 结果表明： 在混料腐解过程 中, 不同温度均可使HA分子结构在培养结束后趋于简单, C(Hu)可被有效矿化; 培养温度越高, w_C(HA)/w_C(FA)的降低程度越大;  在不同含水率下, C(Hu)均可有效矿化分解.