Studies on network images of drainage channels in sea spray icing by MR Microscopy

海喷结冰排水通道的磁共振显微镜网络图像研究

基本信息

批准号：
16310122
负责人：
OZEKI TOSHIHIRO
金额：
$ 10.05万
依托单位：
Hokkaido University of Education
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2006
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-16310122/
关键词：
Sea spray icing Natural disaster Crystal growth Imaging Magnetic Resonance Imaging MIR 核磁気共鳴海水飛沫着氷ブライン 3次元構造排水路船体着氷

项目摘要

Sea-spray ice accretion is a major problem for the operation of lighthouses in northern harbors. Brine pockets trapped in spray-ice matrices during wet growth are one of the structural features of sea-spray icing, and brine drainage control, one of the physical properties of spray ice. We have developed a compact NMR imaging system set up in a cold room to maintain the sample at a constant temperature.The system consists of a permanent magnet, a gradient coil set, and an RF probe installed in -5 °C cold room. A compact MRI console was set up at room temperature beside the cold room. The permanent magnet is a yokeless magnet with the following specifications: field strength= 1.04 T, gap width= 60 mm, homogeneity= 15.3 ppm over 30 mm DSV at 25 °C, and weight= 300 kg. The RF coil is a 30-mm-diameter ten-turn solenoid.We obtained sea-spray icing samples from the ice accretion on a lighthouse on the west coast of Hokkaido, Japan. Because the brine in the spray ice had drained out, using a suction pump, we filled the air gaps in the drainage channels with dodecane (C_<12>H_<26>). The signal from dodecane doped with iron acetylacetonate (C_<15>H_<21>O_6Fe) was sufficient to detect the location of the drainage channels.A three-dimensional driven equilibrium spin-echo (3D-DESE) sequence (repetition time (TR)/echo time (TE) = 200 ms/8 ms, image matrix= 256^3, voxel size=(123 μm)^3, total imaging time= 16 h, NEX= 4) was used for 3D high-resolution imaging. Since the NMR signal from the ice was negligible compared with that from dodecane, the drainage channels appeared as bright regions.

海喷冰积聚是北部港口灯塔运行的主要问题。在湿生长期间，被困在喷雾冰材料中的盐水袋是海洋涂层的结构特征之一，以及盐水排水控制，这是喷雾冰的物理特性之一。我们已经开发了一个紧凑的NMR成像系统，在寒冷的房间中设置为以恒定温度保持样品。该系统由一个永久磁铁，梯度线圈集和安装在-5°C冷藏室中的RF探针组成。在寒冷室旁边的室温下设置了一个紧凑的MRI控制台。永久磁铁是具有以下规格的无YOKENTENT磁铁：磁场强度= 1.04 T，间隙宽度= 60 mm，同质性= 15.3 ppm在25°C下30 mm DSV，重量= 300 kg。 RF线圈是直径为30毫米的十圈螺线管。我们从日本北海道西海岸的一座灯塔上的冰片中获得了海洋涂层样品。由于喷雾冰中的盐水已经排出，因此使用抽吸泵，我们用十二烷（C_ <12> H__ <26>）填充了排水通道中的气隙。来自十二烷的信号用乙酰乙酸铁掺杂（C_ <15> H__ <21> O_6FE）足以检测排水通道的位置。三维驱动平衡自旋 - 回声（3D-DESE）序列（3D-DESE）序列（重复时间（重复）时间（tr）/echo时间（TR）/ECHO时间（TE）= 200 ms/8 ms/8 ms Mats = 256 μm）^3，总成像时间= 16 h，nex = 4）用于3D高分辨率成像。由于与十二烷相比，来自冰的NMR信号可以忽略不计，因此排水通道似乎是明亮的区域。