A search for H i in some peculiar faint dwarf galaxies

We present a deep Giant Metrewave Radio Telescope (GMRT) search for H  i 21-cm emission from three dwarf galaxies, viz. POX 186, SC 24 and KKR 25. Based, in part, on previous single-dish H  i observations, these galaxies have been classified as a blue compact dwarf (BCD), a dwarf irregular and a transition galaxy, respectively. However, in conflict with previous single-dish detections, we do not detect H  i in SC 24 or KKR 25. We suggest that the previous single-dish measurements were probably confused with the local Galactic emission. In the case of POX 186, we confirm the previous non-detection of H  i but with substantially improved limits on its H  i mass. Our derived upper limits on the H  i mass of SC 24 and KKR 25 are similar to the typical H  i mass limit for dwarf spheroidal (dSph) galaxies, whereas in the case of POX 186, we find that its gas content is somewhat smaller than is typical of BCD galaxies.     

Sephadex G-25用于YML-1脱盐条件优化

凝胶过滤(或称分子筛)层析是一种由限制分子通过多孔基质,按分子大小分离混合分子的技术[1]。凝胶过滤方法常用于生物样品脱盐,其操作简便易行,脱盐效果可靠[2]。由于可通过紫外和电导检测器监控整个层析过程、产品的纯度和回收率,又可连续自动进样和收集样品,自动化程度高,容易放大[3],所以,自上世纪60年代初始,随着层析介质技术的发展,Sephadex G-25系列凝胶过滤介质常用于实验室乃至工业规模的脱盐、小分子物质去除及缓冲液的置换。一般实验室脱盐常用透析方法,但其耗费时间长、缓冲液消耗量大,又易损失宝贵样品。笔者采用凝胶过滤法研…     

Geochemical characteristics of deposits from the 2011 Tohoku‐oki tsunami at Hasunuma,Kujukuri coastal plain,Japan

We examined the geochemical characteristics and temporal changes of deposits associated with the 2011 Tohoku‐oki tsunami. Stable carbon isotope ratios, biomarkers, and water‐leachable ions were measured in a sandy tsunami deposit and associated soils sampled at Hasunuma, Kujukuri coastal plain, Japan, in 2011 and 2014. At this site, the 2011 tsunami formed a 10–30 cm ‐thick layer of very fine to medium sand. The tsunami deposit was organic‐poor, and no samples contained any detectable biomarkers of either terrigenous or marine origin. In the underlying soil, we identified hydrocarbons and sterols derived from terrestrial plants, but detected no biomarkers of marine origin. In the samples collected in 2011, concentrations of tsunami‐derived water‐leachable ions were highest in the soil immediately beneath the tsunami deposit and then decreased gradually with depth. Because of its finer texture and higher organic content, the soil has a higher water‐holding capacity than the sandy tsunami deposit. This distribution suggests that ions derived from the tsunami quickly penetrated the sand layer and became concentrated in the underlying soil. In the samples collected in 2014, concentrations of water‐leachable ions were very low in both soil and sand. We attribute the decrease in ion concentrations to post‐tsunami rainfall, seepage, and seasonal changes in groundwater level. Although water‐leachable ions derived from seawater were concentrated in the soil beneath the tsunami deposit following the tsunami inundation, they were not retained for more than a few years. To elucidate the behavior of geochemical characteristics associated with tsunamis, further research on organic‐rich muddy deposits (muddy tsunami deposits and soils beneath sandy tsunami deposits) as well as sandy tsunami deposits is required.     

烃源岩中C19~C29甾烷系列和25 降藿烷系列的检出及其地质意义

沉积有机质中通常可检测到C21（孕甾烷）、C22（升孕甾烷）和C27~C29甾烷,但C19、C20和C23~C26甾烷并不常见。在三塘湖盆地芦草沟组黑色页岩中检出了完整的C19~C29甾烷系列和25 降藿烷系列。如此完整且丰度较高的此类化合物,尚无文献报道。这一新的资料可能蕴含着丰富的油气地球化学信息。初步认为这2个系列的化合物指示:其古环境为干旱和咸化水体环境;有机质以藻类和浮游生物等低等水生生物来源为主,在沉积初期遭受强烈的生物降解作用;原始有机质与细菌降解的产物共存,成为生烃先质。     

塔里木盆地北部隆起原油混合作用半定量评价

塔里木盆地北部隆起油气类型非常复杂，多期充注和储层内的混合作用极为普遍，早期充注原油遭受过生物降解作用的强烈改造，油质非常重，烃类含量和组成发生很大变化，表现为正烷烃和类异戊二烯烃完全消失，甾烷和藿烷被严重破坏，形成大量25－降藿烷，三芳甾相对富集。后期充注的正常原油油质较轻，正烷烃和类异戊二烯烃完整分布，25－降藿烷和三芳甾含量极低。两期充注原油在储层内不同的混合程度造成原油物性和分子组成复杂多变，其变化受控于混合比。根据混合油中正烷烃和25－降藿烷的绝对含量以及三芳甾的相对含量，对油藏内两期充注油的贡献进行了半定量计算，结果表明塔河油田4号构造早期充注的残留油与新近充注的正常油含量相当，塔河3号构造除沙47原油中含20％左右的早期充注油外，基本属晚期充注的产物；哈得逊油田早期充注的残留油含量在5％－15％之间，表明该油田的形成期很晚；乡3井原油中早期充注的残留油约占1／4，羊屋2井主要是晚期充注的贡献。     

X.25分组交换网主要设备的简明配置

介绍了X.25分组交换网建设过程中主要设备的具体配置及关键设备参数的具体设置.     

X.25气象信息网络的应用和维护

结合工作实践,对X.25气象信息网络的建设应用和安装维护进行了探讨,并分析了2例疑难问题的诊断过程和解决办法.     

X．25气象信息网络的应用和维护

结合工作实践，对X．25气象信息网络的建设应用和安装维护进行了探讨，并分析了2例疑难问题的诊断过程和解决办法。     

夏季对流和环流10-25天季内变化-5西太平洋暖池热力状况的关系

主要讨论了西太平洋暖池热力状况年际变化相联系的10－25天季内振荡的特征。在西太平洋暖池处于“暖”夏季和“冷”夏季两种状态时，10－25天季内振荡呈现出明显差异，在所讨论的亚洲－太平洋大部分区域，“暖”夏季时对流活动的10－25天季内变化和“冷”夏季时对流活动的10－25天季内变化表现出显的反相关关系，表明对流活动的年际变化与季内变化的相互作用。当西太平洋暖池上空对流活动的10－25天季内振荡处于最强和最弱阶段时，低层大气表现为Gill型环流响应，即气旋式（反气旋式）环流出现在最强（最弱）对流活动的西北，这种对流和环流关系在西太平洋暖池出于“暖”夏季和“冷”夏季两种状态时均成立。而当西太平洋暖池上空对流活动的10－25天季内振荡处于除此以外其他阶段时，就看不到Gill型环流响应。