Influence of particle composition on thorium scavenging in the marginal China seas

Thorium-234 and particle composition (organic matter, biogenic silica, carbonate and lithogenic component) were examined in the East China Sea (ECS) and the northern South China Sea (NSCS) in order to constrain the particle types scavenging thorium isotopes. Good positive correlations between particulate organic matter (POM) or carbonate and thorium-234 in suspended particulate matter (SPM) indicates that POM and carbonate are efficient to scavenge thorium-234. No relationship between biogenic silica and thorium-234 suggests that geochemical behavior of thorium-234 may be not influenced by biogenic silica. A simple model was used to evaluate the affinity of thorium-234 to different particle components. The results show that POM is the most efficient scavenger for thorium-234 in the ECS and the NSCS, followed by carbonate. The authors'' results lend support to the utility of thorium-234 as a proxy of POC and carbonate in the upper layer. However, the strong dependence of thorium scavenging on particle composition challenges thorium-230 as a constant flux proxy.     

南海细菌胞外多聚物的神经保护活性筛选

本文采取传统的醇沉水溶的工艺提取了深海细菌的胞外聚合物(extracellularpolymericsubstance,EPS),使用过氧化氢作为损伤剂建立SH-SY5Y人神经母细胞瘤体外氧化损伤模型。在安全剂量下评价EPS的体外神经保护活性,确定16种活性良好(细胞活力>90%)的EPS。16种EPS的成分分析结果如下:1)16种EPS的分子量分布呈三段式,分别为>200 kDa, 10～200 kDa和<10 kDa; 2)16种EPS单糖组成中除甘露糖、葡萄糖外,还有稀有单糖氨基葡萄糖、鼠李糖、葡萄糖醛酸、氨基半乳糖、半乳糖、岩藻糖; 3)EPS的总糖含量为14.06%～21.40%,蛋白含量为10.66%～31.05%,硫酸基含量为2.91%～26.53%。通过对相应菌株进行16SrDNA全序列分析并与GenBank比对,完成了活性菌株的鉴定,通过MEGA7.0和Figtree构建系统进化树。鉴定结果表明,16株深海细菌归属于3门8科9属16种,分布在三个门类:厚壁菌门(Firmicutes, 9/16),变形菌门(Proteobacteria, 6/16)和...     

CT诊断纵隔巨大节细胞神经瘤案例分析

节细胞神经瘤（GN）又称神经节细胞瘤，是一种极为罕见（1/100 000）、生长缓慢的良性肿瘤，术前诊断有赖于影像学检查，有时难以确诊。CT临床普及率高，在纵隔病变的检出、诊断中广泛应用，现就本院诊治的1例纵隔巨大GN的CT表现进行总结分析并复习相关文献，提高该疾病CT诊断水平。