Comparative compressibility and equation of state of orthorhombic and tetragonal edingtonite

The high-pressure (HP) behaviour of a natural orthorhombic and tetragonal edingtonite from Ice River, Canada, has been investigated using in situ single-crystal X-ray diffraction. The two isothermal equations of state up to 6.74(5) GPa were determined. V₀, K_T0 and K refined with a third-order Birch–Murnaghan equation of state (BM-EoS) are: V₀ = 598.70(7) ų, K_T0 = 59(1) GPa and K=3.9(4) for orthorhombic edingtonite and V₀ = 600.9(2) ų, K_T0 = 59(1) GPa and K=4.2(5) for tetragonal edingtonite. The experiments were conducted with nominally hydrous pressure penetrating transmitting medium. No overhydration effect was observed within the pressure range investigated. At high-pressures the main deformation mechanism is represented by cooperative rotation of the secondary building unit (SBU).Si/Al distribution slightly influences the elastic behaviour of the tetrahedral framework: the SBU bulk moduli are 125(8) GPa and 111(4) GPa for orthorhombic and tetragonal edingtonite, respectively. Extra-framework contents of both zeolites show an interesting behaviour under HP conditions: the split Ba2 site at P >2.85 GPa is completely empty; only the position Ba1 is occupied. Electronic Supplementary Material. Supplementary material to this paper (Observed and calculated structure factors) is available in electronic form at Electronic Supplementary Material Supplementary material is available in the online version of this article at     

肇庆地磁台dIdD矢量磁力仪与GM3相对记录仪的对比分析研究

使用肇庆地磁台2005年dIdD矢量磁力仪与GM3磁通门磁力仪的观测数据,系统地分析了两套仪器分钟值、日均值、基线值的变化趋势。根据均值和方差检验以及基线值的变化趋势,认为两套仪器有相同的观测精度,除了均值有较小的差异外。两套仪器的观测数据无系统偏差,仪器的稳定性和数据的一致性较好。     

佛山市农业内部生产结构调整与城市化的关系

利用佛山市1978~2002年农业经济活动数据,探讨城市化对农业内部生产结构的影响趋势和程度。结果表明,受城市化水平提高的影响,在农业内部各业占农业总产值的比重中下降最快的是种植业,上升最快的是渔业,而其他各业则变化较小;以生产面积为标志的生产规模缩减最快的是稻谷,扩张最快的是蔬菜;生产的地域结构分化明显,城镇边缘地区逐渐成为蔬菜、花卉等农副产品的专业化生产地带。     

2010-07-23陕西中西部大暴雨天气诊断分析

分析结果表明：①山西北部的暴雨云团在850hPa暖切变线南部生成、发展,并在地面切变线附近合并;山西南部的MCC由3个B中尺度对流云团发生、发展、合并形成,β中尺度对流云团在700hPa次天气尺度切变线上触发生成;MCC发展、成熟阶段,α中尺度云团沿925hPa暖切变线东移;减弱阶段,随副高的南压而南压。②副高西进北抬背景下,同一次暴雨过程中,MCC发生在5880gpm边缘弱的斜压环境里,高层则出现在高压北侧的反气旋环流中;一般暴雨云团发生在5840gpm边缘较强的斜压环境里,高层则出现在急流人口区的右侧。③MCC作为大型的中尺度对流系统,不但对低层高温高湿能量的需求比一般暴雨云团更多,而且在垂直方向上,要求湿层、高能舌、暖温结构更深厚。④南部MCC影响区及5880gpm线边缘为负地闪覆盖区,正地闪主要出现在北部一般暴雨云团影响区及5840gpm线附近。一般暴雨云团影响下比MCC影响下,局地闪电开始及闪电峰值的出现较降水的开始及降水峰值的出现有更多的提前量。⑤山西北部暴雨云团出现在气柱水汽总量梯度的大值区及水汽锋上;山西南部MCC则出现在水汽锋的南侧气柱水汽总量的大值区。气柱水汽总量对0811暴雨过程有36h的提前量,对暴雨的落区有很好的指示意义。     

Erosion of particulate inorganic and organic matter in the Gulf of LionÉrosion de la matière particulaire inorganique et organique dans le golfe du Lion

Critical shear stress of erosion and erosion rate of particulate inorganic and organic matter were measured in a flume at three muddy stations. Critical shear stress ranged between 0.022 and $\text{0.038 }\text{N}\text{m}{}^{\mathrm{?2}}$. At the deepest site, annual erosion of particulate organic nitrogen and phosphorus could exceed net deposition fluxes, showing the importance of erosion processes. Erosion may modify total system mineralisation rates by introducing sedimentary particulate organic matter into the water column and thus this process must be taken into account in studies of biogeochemical cycles. To cite this article: E. Schaaff et al., C. R. Geoscience 334 (2002) 1071–1077.     

Small valley bottom deposits in the sandy districts of the Sarthe basin (France): climatic and/or human origin?

The study of the small valley bottom deposits in a sandy district where several recent erosional events have occurred makes it possible to distinguish deposits, which are caused by climatic oscillations from those induced by both climate and human activities. The coarse alluvium with flints, which reached the main valleys prior to the Subboreal, was transported by greater flows than those which resulted from later human-induced flood discharges, where flints were not evacuated from the small valleys. Radiocarbon dates of peat set those deposits in the Iron Age, in the transition from Antiquity to the Medieval period, at the end of the “optimum climatique de l'an Mil” and during the Little Ice Age. At the present time, human-induced flood discharges reach again the main valleys.     

中国和外国铁路网发展模式的比较研究

本文从宏观角度出发，开展中国与印度、美国、前苏联、德国铁路网发展模式的比较研究，对五国铁路网发展的背景条件、合理长度、路网组成、若干重要干线的建设、重大技术的推广、铁路建设的分区、资金和进度等问题进行了系统和深入的分析。在综述外国铁路网发展的有益经验和深刻教训的基础上，对我国铁路网发展提出了若干建议，为国家有关领导机构制订中长期铁路网发展规划提供重要参考意见。     

资源优化配置与区域发展：以陕西省为例

陕西省资源丰富,科技力量雄厚,但经济发展水平不高,近年在全国的经济地位有所下降,形成一种奇怪的经济现象,即陕西现象。本文在概括、总结这种现象主要特征的基础上,深入剖析了其深层次的原因,即资源发,利用效率低下,扭转陕西现象的出路在于优化资源配置与科技进步并举,只有这样,陕西才能以最小的改革成本获取最大的改革收益。     

小黄鱼(Larimichthys polyactis)线粒体基因组结构与特征

采用长片段扩增策略,获得鲈形目石首鱼科黄鱼属小黄鱼的线粒体基因组全序列。组装分析结果表明,其长度为16470bp,H链碱基组成呈明显反G偏倚,G含量仅为16%。13个蛋白质基因起始密码子均为ATG。COI基因的终止密码子为AGA,ND1和ND3基因为TAG,COII、ND4和Cytb基因为不完全终止密码子T,其余7个基因都是完整的TAA。在小黄鱼mtDNA中发现2个特殊发夹结构,一个是轻链复制起始区(OL)的发夹环,位于tRNA簇,环区T含量仅为9%,而G含量达45%,这与哺乳动物和爪蟾该区域富含T有所不同。另一个假定发夹结构位于ATP6基因末端,这种二级结构可能与准确转录有关。该mtDNA控制区长度为799bp,5′端含有9个连续TA串联重复和2个5′-ATGTA---TACAT-3′重复,与已报道的鱼类扩展终止相关序列模式恰恰相反;中央控制区仅识别出CSB-E结构;保守序列区含有CSB-1,2,3,其中CSB-2具有高度保守性。对小黄鱼和大黄鱼的mtDNA比较进化研究,根据分子钟假说,估计二者线粒体基因组的进化分歧时间为4.8百万年前。     

Late quaternary alluvial stratigraphy of a low-order tributary in central Texas, USA and its response to climate and sediment supply

A paleomegafauna site from central Amazonia with exceptional preservation of mastodons and ground sloths allows for the first time a precise age control based on ¹⁴C analysis, which, together with sedimentological and δ¹³C isotope data, provided the basis to discuss habitat evolution within the context of climate change during the past 15,000 yr. The fossil-bearing deposits, trapped within a depression in the Paleozoic basement, record three episodes of sedimentation formed on floodplains, with an intermediate unit recording a catastrophic deposition through debris flows, probably favored during fast floodings. The integrated approach presented herein supports a change in humidity in central Amazonia through the past 15,000 yr, with a shift from drier to arboreal savanna at 11,340 (±50) ¹⁴C yr B.P. and then to a dense forest like we see today at 4620 (±60) ¹⁴C yr B.P.