竹重组材微晶结构的X射线衍射分析

运用X射线衍射分析(XRD)的检测手段,对冷压热固化与热压法两种生产模式的竹重组材试样进行分析,结果表明竹材纤维素是以微晶结构为基础的无定型结构,仅在衍射角2θ为22.5°附近出现较突出的晶体衍射峰,在衍射角16.7°、35°附近出现对应强度较弱的晶体衍射峰。冷压热固化与热压过程中,竹材纤维素结晶区主体结构未见明显变化,但相对结晶度有不同程度下降,对竹重组材的物理力学性能有所影响。     

Lathyrane diterpenes from Euphorbia prolifera and their inhibitory activities on LPS-induced NO production

A new lathyrane diterpene (1), an unreported spectroscopic data lathyrane diterpenene (2), and two known analaogues (3 and 4) have been isolated from Euphorbia prolifera. Their structures were elucidated as (12E,2S,3S,4R,5R,6S,9S,11S,15R)-3-butyryloxy-5,15-diacetoxy-6,17-epoxylathyra- 12-en-14-one (1), (12E,2S,3S,4R,5R,6S,9S,11S,15R)-3-propionyloxy-5,15-diacetoxy-6,17- epoxylathyra-12-en-14-one (2), (12E,2S,3S,4R,5R,6S,9S,11S,15R)-3-benzoyloxy-5,15-diacetoxy -6,17-epoxylathyra-12-en-14-one (3), and 15-O-acetyl-17-hydroxyjolkinol (4) by spectroscopic methods (IR, ESIMS, HR-ESIMS, NMR, and X-ray crystallography). The inhibitory activities on LPS-induced NO production of these diterpenes were evaluated and compounds 1, 3 and 4 showed inhibitory effects.     

Papillomavirus-induced dermatofibroma in cattle following tuberculin testing

Papillomavirus was identified in two fibromatous dermal nodules which were representative of those present in the caudal fold skin of the tail in 25 of 145 beef cattle tuberculin tested 3 months earlier. Bovine warts were endemic on the property and it is hypothesised that the papilloma virus was introduced intradermally by a virus-contaminated tuberculin syringe. At palpation, the well-circumscribed hard nodular lesions were atypical of the diffuse caudal fold swelling usually present in reactions to tuberculin. Provided tuberculin testing officers are aware of the risk of fibroma and papilloma induction by transmission of papillomavirus, and they are careful to prevent equipment coming into contact with warts at time of inoculation, this source of inaccuracv mav be avoided.     

A morphological approach to understanding preferential flow using image analysis with dye tracers and X-ray Computed Tomography

A key problem facing soil physics and hydropedology at present is some of the standard theories of water flow in soils do not fully reflect the processes at the pore scale, and thus, cannot be adequately used for prediction. As such, examination of soil structure is vital for hydropedologists. Realisation that solutes move preferentially through soil into groundwaters has meant research in this area has increased in importance. This paper describes a multi-scale approach to analyse transport mechanisms using visualisation techniques. Chloride and Brilliant Blue tracers were applied to undisturbed soil cores to examine the physical and morphological properties associated with preferential flow in a range of soil types. Following collection of serial digital images, it was possible to examine and quantify the nature of active water flow mechanisms in terms of both dye-stained pathways and spatial distribution of dye concentration, using image analysis. Preferential flow linked to water potential and soil structural discontinuity was observed in all but the coarsest textured soil which conformed to uniform flow theory. A high level of variability in flow patterns was noted between the soil types. Such information as to how a soil dynamically re-wets is key for hydropedologists involved in applications such as pollution modelling. This is especially significant when considering a wetting mechanism, such as preferential flow, that cannot be adequately described by conventional soil physics.     

X射线吸收精细结构光谱在土壤中的应用

由于X射线吸收精细结构(X-ray absorption fine structure,XAFS)可以原位探测吸收原子的2~3个邻近配位壳层,获得目标元素的电子结构信息和化学结构信息,所以XAFS已成为微观领域最重要的结构分析工具,丰富了我们对元素的重要化学性质和反应过程的认识。本文简述了XAFS的基本原理,探讨了样品制备、测试及数据分析等过程需关注的问题,重点综述了应用XAFS研究土壤重金属和营养元素的形态、土壤固-液界面的反应过程和机理,并指出其应用的局限性和未来发展的前景,旨在推动我国XAFS在土壤科学中的应用。由于土壤中界面反应的复杂性,XAFS应结合其他结构分析技术,结构分析技术应结合宏观数据和计算机模拟,土壤学应与其他学科交叉、融合,只有这样,才有可能在时间和空间尺度上阐明土壤组分在环境界面上的复杂反应过程和机理。     

盐胁迫下臭椿和银杏叶片细胞离子区域化研究(英文)

对盆栽银杏和臭椿苗木经 10 0mmol·L- 1和 2 0 0mmol·L- 1NaCl胁迫处理后 ,采用透射电镜X 射线能谱微区分析技术 ,对叶片表皮层、栅栏组织和海绵组织细胞不同部位Na+ 、K+ 、Cl- 含量与分布进行了测定 .结果表明 :在NaCl胁迫下 ,臭椿和银杏叶片各组织细胞的细胞壁、细胞质和液泡中Na+ 、Cl- 含量上升 ,K+ 含量下降 ,Na/K比上升 .银杏Na+ 主要积累在液泡中 ;臭椿Na+ 在 10 0mmol·L- 1NaCl胁迫下 ,液泡区隔化 ,2 0 0mmol·L- 1NaCl胁迫下 ,细胞质Na+ 含量高于液泡 .银杏在10 0mmol·L- 1NaCl胁迫下 ,Cl- 在液泡区隔化 ,2 0 0mmol·L- 1NaCl胁迫下 ,Cl- 未被液泡区隔化 ;臭椿在NaCl胁迫下 ,细胞大量吸收Cl- 的同时液泡未对Cl- 区隔化 .NaCl胁迫下 ,银杏对Na+ 的吸收大于对Cl- 吸收 ,而臭椿对Cl- 的吸收大于Na+ 的吸收     

X射线图像技术对红毛丹内部品质的检测

研究了利用X射线图像处理及模式识别方法检测红毛丹内部品质——可食率、可溶性固形物含量。首先用阈值分割法去除红毛丹背景,然后用模糊C均值聚类方法来分割果肉区域。红毛丹可食率以分割出的果肉区域像素个数与整个果实区域像素个数之比来表征,实验结果表明,误判率小于10％。红毛丹可溶性固形物含量的X射线图像检测采用纹理特征描述的方法,利用直方图矩特征和支持向量机回归方法预测红毛丹可溶性固形物含量的相关系数最高可达87．2％。