秦皇岛地区雨滴谱仪和雷达探测的反射率因子差异分析研究

利用布设在秦皇岛市抚宁地区的OTT Parsivel激光雨滴谱仪和卢龙地区S波段天气雷达,对2017—2019年4—9月共23次降水过程进行了观测,并分析了基于雨滴谱参数(滴谱粒子数N(D)和粒子直径大小D₀)计算的雷达反射率因子Z_D和雷达探测的雷达反射率因子Z_R的差异Z_C。结果表明,N(D)主要集中在130～530个范围内,Z_C标准差随着N(D)的增大而逐渐减少;D₀主要集中在0.8～1.6 mm范围内,Z_C标准值在D₀<1.2 mm范围内随着D₀的增大而逐渐减少,D₀在1.2～1.6 mm范围内趋于稳定;Z_D主要集中在15～40 dBZ范围内,Z_C标准差在15～35 dBZ范围内随着Z_D值增大而减小。     

基于航空重磁资料对大杨树盆地南部及周边岩浆岩分布规律的认识

基于区域地质-地球物理综合研究, 利用最新实测的航空重磁综合测量数据, 结合野外踏勘与物性测量结果, 采用化极、向上延拓、垂向导数等场源分离或异常提取技术, 研究了大杨树盆地南部及周边不同类型岩浆岩的重磁异常响应, 圈定了其空间分布范围, 揭示了区域岩浆岩发育特征、分布规律及其控制因素。研究表明, 研究区不同类型的岩浆岩具有迥然不同的航磁异常特征; 本次采用的突出局部重磁异常的地球物理方法可以有效识别酸性、中酸性、中基性等岩浆岩; 本次系统圈定了具有地质意义的岩浆岩百余处, 多数岩浆岩沿北东向与北西向断裂及其两侧分布, 尤以断裂交汇部位最为发育, 说明断裂对岩浆活动具有明显的控制作用; 航空重磁揭示研究区发育较大规模的隐伏中基性火山岩, 为区域基础地质研究和火山岩盆地油气藏资源评价提供了重要的地质-地球物理依据。     

Properties of Klebsiella phage P13 and associated exopolysaccharide depolymerase

The bacteriophage P13 that infects Klebsiella serotype K13 contains a heat-stable depolymerase capable of effective degradation of exopolysaccharide(EPS) produced by this microorganism. In this study, the titer of phage P13, initially 2.0 × 107 pfu mL-1, was found increasing 20 min after infection and reached 5.0 × 109 pfu mL-1 in 60 min. Accordingly, the enzyme activity of depolymerase approached the maximum 60 min after infection. Treatment at 70℃ for 30 min inactivated all the phage, but retained over 90% of the depolymerase activity. Addition of acetone into the crude phage lysate led to precipitation of the protein, with a marked increase in bacterial EPS degradation activity and a rapid drop in the titer of phage. After partial purification by acetone precipitation and ultrafiltration centrifugation, the enzyme was separated from the phage particles, showing two components with enzyme activity on Q-Sepharose Fast Flow. The soluble enzyme had an optimum degradation activity at 60℃ and pH 6.5. Transmission electron microscopy demonstrated that the phage P13 particles were spherical with a diameter of 50 nm and a short stumpy tail. It was a double-strand DNA virus consisting of a nucleic acid molecule of 45976 bp. This work provides an efficient purification operation including thermal treatment and ultrafiltration centrifugation, to dissociate depolymerase from phage particles. The characterization of phage P13 and associated EPS depolymerase is beneficial for further application of this enzyme.     

中国第四次北极科学考察期间北极点附近海冰和融池的航空遥感观测

An aerial photography has been used to provide validation data on sea ice near the North Pole where most polar orbiting satellites cannot cover. This kind of data can also be used as a supplement for missing data and for reducing the uncertainty of data interpolation. The aerial photos are analyzed near the North Pole collected during the Chinese national arctic research expedition in the summer of 2010(CHINARE2010). The result shows that the average fraction of open water increases from the ice camp at approximately 87°N to the North Pole, resulting in the decrease in the sea ice. The average sea ice concentration is only 62.0% for the two flights(16 and 19 August 2010). The average albedo(0.42) estimated from the area ratios among snow-covered ice,melt pond and water is slightly lower than the 0.49 of HOTRAX 2005. The data on 19 August 2010 shows that the albedo decreases from the ice camp at approximately 87°N to the North Pole, primarily due to the decrease in the fraction of snow-covered ice and the increase in fractions of melt-pond and open-water. The ice concentration from the aerial photos and AMSR-E(The Advanced Microwave Scanning Radiometer-Earth Observing System) images at 87.0°–87.5°N exhibits similar spatial patterns, although the AMSR-E concentration is approximately 18.0%(on average) higher than aerial photos. This can be attributed to the 6.25 km resolution of AMSR-E, which cannot separate melt ponds/submerged ice from ice and cannot detect the small leads between floes. Thus, the aerial photos would play an important role in providing high-resolution independent estimates of the ice concentration and the fraction of melt pond cover to validate and/or supplement space-borne remote sensing products near the North Pole.     

琼东南盆地梅山组海底扇成因演化特征与勘探建议

梅山组海底扇作为中央峡谷水道之外最引人注目的大型储集体,是琼东南盆地尤其是深水区常规碎屑岩领域下一步最为重要的勘探对象。总结了琼东南盆地各凹陷钻井资料所揭示的梅山组海底扇差异分布现象,通过研究区大陆架发育特征、陆架坡折带发育特征,结合物源供给与优势海流方向,首次从宏观格局解释了琼东南盆地中央坳陷带不同凹陷海底扇发育地质背景的差异及成因,提出乐东凹陷梅山组大型海底扇主物源来自东北方向海南隆起。通过细化中中新世大海退内部次级海平面旋回特征,首次建立了本区梅山组层序充填与海平面旋回的精确对应关系,从层序成因角度厘清了梅山组各期次海底扇发育演化特征与凹陷级别的有利储层展布特征,并据此提出相应的勘探建议,指出乐东凹陷梅山组中—晚期海底扇储层风险低,是梅山组海底扇领域突破的首选区带;陵水凹陷早期海底扇圈闭有效性较好,是梅山组海底扇大规模成藏的有利勘探方向。该研究为梅山组海底扇领域的勘探部署提供了新思路。     

轨道站点周边建成环境对残疾人出行行为的影响研究——以武汉市189个轨道站点为例

残疾人流动性是衡量社会公平发展的重要方面。由于特殊的身体和社会经济状况,残疾人出行行为具有更为独特的特征,也更易受建成环境影响。论文基于武汉市轨道交通智能刷卡数据,整合多源空间大数据,探索武汉市残疾人轨道交通出行时空特征,并利用地理加权回归(GWR)模型进一步探究轨道交通站点周边建成环境对轨道交通残疾人客流量影响的空间异质性。研究发现：① 地铁出行的残疾人中有29.7%具有通勤出行的特征,出行频率工作日高于休息日,且均呈现早晚错峰出行的趋势;② 15~30 min即大约5~10 km的中短距离出行最多,活动范围集中于三环线以内的主城区,且以同区出行活动最为频繁,跨江出行较少;③ 在大部分的研究范围内,公交站点密度、路网密度、大型公园密度和站点开通时间对站点残疾人客流量均具有正向影响;④ 换乘站的日均残疾人客流量明显高于非换乘站;⑤ 与以往研究结论不同的是,土地利用混合度、站点无障碍设施对站点残疾人客流量的影响并不显著。研究可为“残疾人友好型”的轨道交通站点建成环境优化和新站点土地利用布局提供数据支撑,增强城市公共服务人本化。     

国际冰雪旅游的研究进展及启示

冰雪是一种自然现象,也是一种宝贵的旅游资源,已经衍生为全球旅游业中的重要业态。冰雪旅游在欧美发达国家兴起和发展,后逐渐扩展到全球,一直以来备受学界和业界关注。本研究以Web of Science为数据库,对相关文献进行系统整理和阅读,以定性和定量相结合的方式对国际冰雪旅游研究的研究分布、研究热点、研究趋势和主要议题进行深入剖析,以期为后续研究提供借鉴和参考。研究发现：(1) 1988年以来国际冰雪旅游相关文献数量持续攀升,研究者和机构主要集中在欧美冰雪产业发达的国家,但中国正在快速崛起。(2)国际冰雪旅游研究热点呈现一定的阶段性,初始阶段侧重于探讨“滑雪伤害”,后随着全球气候变暖趋势明显,使得“气候变化”相关主题成为关注热点且延续至今,近些年冰雪旅游产业可持续发展、冰雪旅游产品供给、冰雪赛事等一批视角创新、尺度微观的研究涌现。(3)国际冰雪旅游研究主要围绕“自然影响”“游客体验”和“产业发展”3个话题展开。最后,本研究分析了国际冰雪旅游研究对中国的启示,从研究尺度、研究视角、研究方法和研究价值等方面指出中国冰雪旅游研究的方向。     

Petrogenesis and Tectonic Implications of Jurassic Granites in the Xingcheng Area, Northeastern North China Craton

New integrated geochemical studies are reported for Jurassic granites of the Xingcheng area in the northeastern North China Craton. U–Pb zircon data indicate that the Huashan and Taili monzogranites were emplaced during the Early (189 ± 2 Ma) and Late (155 ± 1 Ma) Jurassic, respectively. They are typical of high-K calc-alkaline series rocks and I-type granites, according to our whole-rock geochemical researches. Both Early and Late Jurassic monzogranites show adakitic rock characteristics because of their high Sr contents (221–347 ppm) and Sr/Y ratios (28.7–37.5), and low Y contents (7.83–14.7 ppm). The Early Jurassic monzogranite samples have an (87Sr/86Sr)i ratio of 0.7046, εNd(t) values of ?11.62 to ?11.51, and εHf(t) values of ?13.6 to ?6.4, whereas the Late Jurassic monzogranites have higher (87Sr/86Sr)i ratios of 0.7069–0.7071 and lower εNd(t) (?20.65 to ?20.46) and εHf(t) (?27.6 to ?20.0) values. We suggest that the Early Jurassic adakitic rocks were derived from partial melting of thickened lower crust contaminated with mantle-derived materials, related to subduction of the Paleo-Pacific Plate. The Late Jurassic adakitic rocks were derived from partial melting of thickened lower crust in an extensional tectonic setting associated with an active continental margin.     

鄂尔多斯西缘北段大型陆缘逆冲推覆体系

鄂尔多斯西缘北段是一个自中生代末以来形成的、结晶基底和早古生代大陆边缘沉积盖层同时卷入的巨型陆缘逆冲推覆构造体系。根据区域地层发育、变形岩石属性、冲断层几何学以及它们与联冲断层的关系,大体上可以分为不同形成阶段的3个冲断层构造组合,包括9个次级构造单元(B1—B7,BN,BS)。受冲断层运动自西向东的一致推进,整体呈现一个局部被近东西走向联冲断层切错、向东凸出的弧形:前端为陆缘褶皱冲断带;中部表现为一系列"原地"或"异地"推覆体和冲断席,发育低角度滑脱层和双冲构造;后部又被最晚期的冲断体叠置。侏罗-白垩纪为逆冲推覆构造的主要发展阶段,经历了3期主要的冲断层作用。第Ⅰ期发生在侏罗纪末,沿阿拉善—华北两类不同性质结晶基底之间的主滑脱面发生大规模冲断层作用,形成桌子山—岗德尔山褶皱冲断带。第Ⅱ期冲断层作用的持续位移,形成了具有上、下两个构造层的石嘴山—尖山大型异地推覆体,主滑脱面为石炭纪煤系地层,其中发育典型的双冲构造。新生代(距今65Ma)以来,印度—欧亚板块挤压碰撞和青藏高原早期向北推挤,加剧了鄂尔多斯西缘逆冲推覆构造的进一步发育,第Ⅲ期冲断层作用在东部陆缘褶皱冲断带形成了苏海图反冲构造的同时,在西部将异地推覆体下部的奥陶系再次推至地表。第Ⅰ期和第Ⅱ期冲断层作用累计位移幅度可能达到60~80km,第Ⅲ期冲断层作用的位移幅度为8km。相邻冲断席之间位移矢量的差异,通过近东西走向的联冲断层得到了调整。     

中国东部的爆发性海岸气旋

针对2016年5月2—3日的一次北上黄渤海的爆发性江淮气旋过程,利用常规观测资料和NCEP再分析资料对其极端性的成因进行诊断分析,并与历史同期2015年5月11—12日过程进行了对比。结果表明：（1）统计表明,2016年5月2—3日爆发性江淮气旋维持时间、强度、变压、气压梯度及形成时间、移速等都突破了1951年以来5月上旬历史同期极值。（2）高低空急流辐散辐合耦合,锋区作用下次级环流范围扩大、强度加强,途经海面减少了气旋移动所需要的能量消耗,额外得到了促使气旋爆发的感热、辐射、潜热能量,促发地面江淮气旋爆发性极端发展。