白菜种子萌发的热抑制现象及其与细胞壁降解酶的关系

为了探讨白菜种子萌发热抑制的机制,以新收获的白菜种子为材料,研究了种子萌发对不同温度的响应,后熟、冷层积和植物激素处理对种子萌发的作用,以及种子萌发和不同处理与细胞壁降解酶之间的关系。结果表明,当萌发温度≥20℃时,种子的萌发率显著降低,热抑制的种子不表现次生休眠。后熟、层积和GA3处理能有效地降低种子萌发的热抑制;相反,ABA处理则增强种子萌发的热抑制。种子萌发过程中内切–β–甘露聚糖酶、β–甘露糖苷酶和α–半乳糖苷酶的活性增加。与新收获的种子相比,后熟、层积和GA3处理增加上述3种酶的活性;ABA处理增加内切–β–甘露聚糖酶的活性,但不影响β–甘露糖苷酶和α–半乳糖苷酶的活性。在不同温度下吸胀48 h的种子的内切–β–甘露聚糖酶和α–半乳糖苷酶的活性变化与随后种子的萌发没有直接关系。说明新收获的白菜种子具有明显的萌发热抑制,这种特性能被后熟、层积和GA3处理以增强细胞壁降解酶活性的方式有效地解除

THE INTER-ANNUAL DRIFT AND DRIVEN FORCE OF ULVA PROLIFERA BLOOM IN THE SOUTHERN YELLOW SEA

Using the environmental satellite (HJ-1A/1B) CCD and MODIS images, we analyzed the drift of inter-annual trajectories of Ulva prolifera in the South Yellow Sea from 2011 to 2017. The effects of sea surface wind (SSW) and sea surface temperature (SST) on the growth and drift trajectories were studied using QuickSCAT sea wind data and ESRL (NOAA Earth System Research Laboratory) SST data. The results show that in the past seven years, the earliest occurrence of U. prolifera bloom noticed by remote-sensing was in May near Yancheng, Jiangsu. In general, U. prolifera bloom drifted south to north from northern Jiangsu to the southern part of the Shandong Peninsula. The most distant U. prolifera bloom was centered 115km east off Qingdao on June 21, 2015, and the least distant one was 9.6km off Qingdao on July 11, 2012. The central position of the bloom varied considerably, and the overall route of the drift agreed well with the wind direction at sea surface. SST was the key environmental factor for the bloom outbreak. The monthly SST increase in May-August in the southern Yellow Sea predestinated the on-and-off of the algal bloom

基于CDEM的采空区稳定性及临界顶板厚度分析

地下隐伏采空区易导致地表塌陷等问题发生,采空区的顶板稳定性关乎到露天开采的安全,确定采空区临界顶板厚度对采空区安全评价具有重要意义。采空区临界顶板厚度的影响因素复杂,与采空区的几何参数及岩体物理力学参数等多种因素相关。通过量纲分析建立无量纲表达式,得到影响临界顶板厚度的无量纲参数。在此基础上,借助CDEM数值计算方法建立数值模型并进行计算分析。建立了二维采空区数值模型,通过改变采空区的几何参数及岩体物理力学参数,计算采空区顶板的安全系数,研究以上因素对采空区稳定性的影响规律,识别影响顶板安全系数的主要影响因素。建立了采空区二维模型和三维模型的计算模型,得到了无量纲表达式中无量纲临界高度与无量纲强度间的关系,采用指数函数进行拟合得到响应的关系表达式。研究表明:弹性模量、泊松比对临界顶板厚度影响不大,采空区高度对临界顶板厚度无影响;黏聚力对采空区安全系数影响最大,采空区跨度、岩体内摩擦角、岩体密度次之;采空区无量纲高度与无量纲强度之间存在指数衰减关系

2008年-2012年山东半岛海域浒苔时空分布特征研究/Research on the Characteristics of Ulva .Proli f era in Shandong Peninsula During 2008-2012 Based on MODIS Data[J]

浒苔是我国近海一种新型的海洋生态灾害，自2008年以来，每年5-8月份在黄海海域周期性暴发与消亡，给沿海地区造成不同的环境影响和经济损失。基于2008年-2012年五年的M ODIS数据，计算了山东半岛海域长时间序列NDVI ，利用阈值分割法提取浒苔信息，并进一步获得爆发的时间、面积、相对聚集密度、影响范围及浒苔漂浮路径。结果表明：2008年以来各年浒苔最早发生在5月中旬至6月上旬，6月中旬至7上旬进入爆发期，浒苔面积、影响范围及浒苔密度达到最大值，其相对聚集密度峰值一般早于或晚于爆发期一个生长阶段，最终于7月下旬或8月上旬进入消亡期，平均持续时间约为71天。浒苔漂浮路径整体为从东南外海逐渐开始向西北近海海域靠近。从浒苔面积、影响范围、相对聚集密度等多项指标综合看，2008年和2009年两年浒苔爆发较为严重

JUNO Sensitivity on Proton Decay p→νˉK+p\to \bar\nu K^+ Searches

The Jiangmen Underground Neutrino Observatory (JUNO) is a large liquid scintillator detector designed to explore many topics in fundamental physics. In this paper, the potential on searching for proton decay in $p\to \bar\nu K^+$ mode with JUNO is investigated.The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification. Moreover, the excellent energy resolution of JUNO permits to suppress the sizable background caused by other delayed signals. Based on these advantages, the detection efficiency for the proton decay via $p\to \bar\nu K^+$ is 36.9% with a background level of 0.2 events after 10 years of data taking. The estimated sensitivity based on 200 kton-years exposure is $9.6 \times 10^{33}$ years, competitive with the current best limits on the proton lifetime in this channel

JUNO sensitivity on proton decay p → ν K + searches*

The Jiangmen Underground Neutrino Observatory (JUNO) is a large liquid scintillator detector designed to explore many topics in fundamental physics. In this study, the potential of searching for proton decay in the $p\to \bar{\nu} K^+$ mode with JUNO is investigated. The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification. Moreover, the excellent energy resolution of JUNO permits suppression of the sizable background caused by other delayed signals. Based on these advantages, the detection efficiency for the proton decay via $p\to \bar{\nu} K^+$ is 36.9% ± 4.9% with a background level of $0.2\pm 0.05({\rm syst})\pm$$0.2({\rm stat})$ events after 10 years of data collection. The estimated sensitivity based on 200 kton-years of exposure is $9.6 \times 10^{33}$ years, which is competitive with the current best limits on the proton lifetime in this channel and complements the use of different detection technologies