电感耦合等离子体质谱法测定岩石样品中的锆铌铪钽两种预处理方法的比较

研究了微波消解酸溶和过氧化钠碱熔两种测定岩石样品中锆、铌、铪、钽前处理方法,利用电感耦合等离子体质谱法进行测定。对所选用不同种类的岩石国家标准物质样品进行了条件实验,结果表明:采用过氧化钠碱熔法处理岩石样品后,锆、铌、铪、钽的测量值准确度高,且相对标准偏差(RSD,n=10)小于6%,该方法更适用于岩石样品中锆、铌、铪、钽的测定。     

Quantitative evaluation of the biostratigraphic distribution of acanthomorphic acritarchs in the Ediacaran Doushantuo Formation in the Yangtze Gorges area, South China

Doushantuo acanthomorphic acritarchs are large morphologically complex organic-walled microfossils broadly constrained between the 635 Ma Nantuo glaciation and the 551 Ma Miaohe Biota. They are potential biostratigraphic tools for subdivision and correlation of the Ediacaran System in South China. However, major variations in sedimentary facies and stratigraphic thickness present challenges in understanding the spatial and temporal distribution of these acritarchs. Further, the distribution of acritarchs in the Doushantuo Formation is associated with the presence of early diagenetic chert and phosphate, implying a certain degree of preservational bias and/or environmental control. The purpose of this paper is to document the stratigraphic distribution of Doushantuo acritarchs and to quantitatively evaluate their biostratigraphic significance and possible taphonomic–environmental biases, based on high-resolution paleontological data from six sections over 100 km in the Yangtze Gorges area, South China.A total of 1082 acritarch fossils were recorded from 84 chert horizons in the six sections of the study area. These chert horizons are not uniformly distributed throughout the Doushantuo Formation, thus the presence/absence of early diagenetic chert does play a role in controlling the distribution of acritarchs. The sampled chert horizons can be grouped into two stratigraphic intervals in the lower and upper Doushantuo Formation, respectively, based on regional stratigraphic correlation. Quantitative analysis shows that the two intervals are distinct taxonomically and largely independent of taphonomic or facies controls. Thus, the two intervals can be regarded as assemblage biozones. The lower biozone (biozone 1) is numerically dominated by Tianzhushania spinosa (n = 587; 68.3%) and Meghystrichosphaeridium magnificum (n = 74; 8.6%), whereas the upper biozone (biozone 2) is dominated by Ericiasphaera rigida (n = 104; 47.1%) and Tianzhushania spinosa (n = 34; 14.1%). The three most common genera, Meghystrichosphaeridium, Tianzhushania, and Ericiasphaera, have been identified in all sections. Correspondence analysis (CA), detrended correspondence analysis (DCA), discriminant analysis (DA), and pairwise comparisons of samples (Spearman rank coefficient and Jaccard–Chao index), all consistently support biostratigraphic zonations. Thus, the distribution of the Doushantuo acanthomorphs is primarily controlled by biostratigraphic position of samples, with facies and taphonomic differences playing a secondary role. Our case study suggests that acanthomorphic acritarchs can offer a viable tool for regional correlation of the Ediacaran System.     

New approaches for archaeal genome-guided cultivation

Archaea, one of the three domains of life along with Bacteria and Eukarya, contains ancient life forms such as methanogen that are observed today on Earth, and one lineage Asgard archaea is also considered the closest ancestor of Eukarya.Recently, with the development of interdisciplinary studies from Earth and Life sciences, archaeal organisms are considered to play pivotal roles in geochemical cycling in nature. However, our understanding of the attributes, origin and evolution, geochemical and ecological functions of Archaea is hampered by the scarcity of archaeal isolates, which has represented a challenge to researchers for the last 40 years. Cultivation-independent sequencing and phylogenomic analyses have demonstrated a considerable diversity of Archaea with more than 20 novel phyla. However, only four archaeal phyla have cultured representatives, leaving large gaps in our knowledge of the metabolic capabilities and ecological functions of the majority of archaeal strains identified exclusively by DNA sequencing. In this review, we summarize the discovery and development of archaeal research, highlight the knowledge gap between uncultured and cultured archaeal microbes, and call on the importance of devoting greater research efforts to archaeal cultivation. Finally, we outlined new ideas and strategic approaches, namely,(1)genome-based methods,(2) microbial network information-based methods,(3) genome-scale model-guided methods, and(4)machine learning methods, to enable the cultivation of uncultivated archaeal microbes using accumulated high-throughput sequencing data.     

基于MOS的广西北部湾沿海秋冬极大风速精细化预报

采用北部湾北部沿海6个自动站实况资料和欧洲中心细网格数值预报产品,根据模式输出统计法(MOS),对广西北部湾地区2012年—2016冬半年(9月到次年2月)日极大风速建立站点秋冬季不同预报时效的多元线性回归方程,并用2017冬半年的数据进行TS检验评分.结果表明,秋冬季日极大风速和代表引导气流的500hPa蒙古槽、代表...     

深度学习遥感图像标注系统研究

随着深度学习的发展,遥感影像处理技术也从传统机器学习算法向深度学习转变,然而,用于遥感图像的训练数据集却十分稀少,且数据标注困难。本文将GIS技术与图像标注技术相结合,基于Flask Web框架设计一个可用于海量遥感数据的标注系统。该系统可用于海量遥感数据的数据框标注、数据类别标注,以及目标关键点标注,同时能将标注数据导出为深度学习训练最常用的COCO数据集和VOC2007两种格式。     

考虑卸荷变形模量的坑底回弹变形计算方法

针对基坑开挖卸荷导致坑底土体回弹变形问题,考虑开挖卸荷过程中土体弹性模量随着卸荷应力路径变化的特征,推导在卸荷应力路径作用下土体变形模量的计算公式,考虑基坑的开挖为地表以下基坑开挖面处应力的变化,基于Mindlin应力解计算矩形基坑开挖卸荷引起的坑底土体附加应力,采用分层总和法计算基坑开挖引起的坑底土体的回弹变形,结合已有文献中的工程实例,采用该方法计算开挖引起的坑底隆起变形,并与实际监测数据对比分析表明,该方法能够有效预测基坑开挖引起的坑底隆起变形,能够作为基坑开挖坑底隆起变形的一种有效预测方法。     

海藻中类胡萝卜素的提取及含量测定

许多研究已经表明，类胡萝卜素是分布最广泛、最重要的一类光辅助合成色素。类胡萝卜素具有多种生物学功能：作为化学保护剂可抵抗由植物自身叶绿素的光敏氧化作用引起的有害作用，给人体补充β-胡萝卜素可有效降低心血管疾病和癌症的发生概率，高摄入富含类胡萝卜素的饮食和降低白内障发生的危险之间有重要联系(Bendich，1993)。海藻中含有丰富的类胡萝卜素，从结构类型说，通常可以分为三类：胡萝卜素、叶黄素和类胡萝卜素酸。海藻中还含有多种特有的类胡萝卜素，如褐藻黄素、甲藻黄素、硅藻黄素等。直到目前为止，海藻中类胡萝卜素的组成与生理学功能尚没有明确的结论，因而对我国丰富的海藻资源中的类胡萝卜素进行较为系统和全面的化学及生物活性研究已成为摆在我们面前的一个重要课题。本研究选取我国青岛海滨三类大型经济海藻——红、绿、褐藻中资源量丰富的代表性种类作为实验材料，较系统地测定了其中类胡萝卜素的含量，并运用经典的柱层析法对各类胡萝卜素组分进行了分离，通过薄层分析和可见光谱扫描对各分离组分进行了定性、定量分析。     

褐藻多酚合成的模拟研究

褐藻多酚是间苯三酚的聚合物,结构复杂,有关生物合成途径方面的研究报道甚少。近年发现,褐藻多酚具有多种生物活性和医药价值(Ragan & Glombitza,1986),因此，研究褐藻多酚的人工合成不仅可模似研究褐藻多酚的生物合成过程,而且为寻找替代自然资源打下了基础。 作者在实验中观察到配制的间苯三酚溶液放置一段时间后会逐渐发黄,因此认为间苯三酚在放置过程中发生了氧化聚合,并对此作了进一步研究。     

2017年浙江临安MS4.2地震前后香泉地震台水氡异常特征分析

1 研究背景 已有研究表明,在中强及以上地震前,在震中距一定范围内分布的氡测点通常会出现氡异常,表明氡测项映震效果较好(廖丽霞,2008;孙凤霞等,2016).虽然诸多地震预报研究涉及水氡测项映震前兆机理分析及方法探索,但对于水氡动态变化异常分析及判断,尚缺少有效实例.因此,本文就2017年4月12日浙江临安MS 4.2地震前安徽香泉地震台水氡测值异常变化进行探讨,以期准确捕捉前兆异常信息,提升地震分析预报能力.     

洱海沉积物中有机质和DNA的分布特征

测定了洱海沉积物中有机碳、氮,提取了沉积物中的DNA。有机碳氮呈现相同的变化趋势降解主要发生在表层10cm;7cm前后氧化-还原条件变化,微生物电子受体改变,所以有机质的降解方式不同,出现不同的特征。利用分子生物学和地球化学相结合的方法,能更全面的认识和理解早期成岩过程。