Behavior of unbonded flexible risers subject to axial tension

Owing to nonlinear contact problems with slip and friction, a lot of limiting assumptions are made when developing analytical models to simulate the behavior of an unbonded flexible riser. Meanwhile, in order to avoid convergence problems and excessive calculating time associated with running the detailed finite element （FE） model of an unbonded flexible riser, interlocked carcass and zeta layers with complicated cross section shapes are replaced by simple geometrical shapes （e.g. hollow cylindrical shell） with equivalent orthotropic materials. But the simplified model does not imply the stresses equivalence of these two layers. To solve these problems, based on ABAQUS/Explicit, a numerical method that is suitable for the detailed FE model is proposed. In consideration of interaction among all component layers, the axial stiffness of an eight-layer unbonded flexible riser subjected to axial tension is predicted. Compared with analytical and experimental results, it is shown that the proposed numerical method not only has high accuracy but also can substantially reduce the calculating time. In addition, the impact of the lay angle of helical tendons on axial stiffness is discussed.     

壳聚糖聚乳酸羟基乙酸纳米粒子作为抗瘤药物载体的研究

研究采用乳化溶剂挥发技术和共价交联技术,合成了壳聚糖聚乳酸羟基乙酸(壳聚糖PLGA)的3种纳米载体:空白的PLGA NPs、表面修饰的C-NPs和自组装的G-NPs。利用人乳腺癌细胞MCF-7细胞作为模型细胞,抗肿瘤药物阿霉素为载药,通过荧光显微镜观察了肿瘤细胞对FITC标记的纳米载体的体外摄取情况,并进行了定量测定。用MTT法测定了包载药物阿霉素后纳米粒子对肿瘤细胞生长的抑制率,分析了不同纳米粒子作为抗肿瘤药物载体的靶向性和载药抑制性。研究结果表明,在低浓度条件下(25~400μg/mL),MCF-7细胞对C-NPs和G-NPs的吞噬具有时间依赖性和浓度依赖性。载药纳米粒子(DOX-PLGA NPs,DOX-C-NPs和DOX-G-NPs)和游离药物(DOX)对细胞生长的抑制率也具有时间依赖性和浓度依赖性,在低药物浓度下(1~4μg/mL)孵育12h后,载药纳米粒子基本呈现出高于游离药物的细胞生长抑制率,而当药物浓度从8μg/mL增加到16μg/mL后,游离阿霉素显现出更高的细胞生长抑制率,C-NPs和G-NPs均表现出高于PLGA NPs的细胞生长抑制率。壳聚糖修饰的2种纳米粒子C-NPs和G-NPs具有良好的细胞靶向性和低浓度药物抑制率,是一种良好的抗肿瘤药物载体。     

Mineralogical study of surface sediments in the western Arctic Ocean and their implications for material sources

Mineralogical analysis was performed on bulk sediments of 79 surface samples using X-ray diffraction. The analytical results, combined with data on ocean currents and the regional geological background, were used to investigate the mineral sources. Mineral assemblages in sediments and their distribution in the study area indicate that the material sources are complex. （1） Feldspar is abundant in the sediments of the middle Chukchi Sea near the Bering Strait, originating from sediments in the Anadyr River carried by the Anadyr Current. Sediments deposited on the western side of the Chukchi Sea are rich in feldspar. Compared with other areas, sediments in this region are rich in hornblende transported from volcanic and sedimentary rocks in Siberia by the Anadyr Stream and the Siberian Coastal Current. Sediments in the eastern Chukchi Sea are rich in quartz sourced from sediments of the Yukon and Kuskokwim rivers carried by the Alaska Coastal Current. Sediments in the northern Chukchi Sea are rich in quartz and carbonates from the Mackenzie River sediments. （2） Sediments of the southern and central Canada Basin contain little calcite and dolomite, mainly due to the small impact of the Beaufort Gyre carrying carbonates from the Canadian Arctic Islands. Compared with other areas, the mica content in the region is high, implying that the Laptev Sea is the main sediment source for the southern and central Canada Basin. In the other deep sea areas, calcite and dolomite levels are high caused by the input of large amounts of sediment carried by the Beaufort Gyre from the Canadian Arctic Islands （Banks and Victoria）. The Siberian Laptev Sea also provides small amounts of sediment for this region. Furthermore, the Atlantic mid-water contributes some fine-grained material to the entire deep western Arctic Ocean.     

永城市日月湖省级矿山公园申报顺利通过专家评审

正4月30日,在河南省国土资源厅组织的省级矿山公园评审会上,永城市申报的日月湖省级矿山公园顺利通过专家评审。评审会上,与会领导和评审专家在认真观看专题片、听取项目编制人员的汇报和提问讨论后,认为永城市日月湖省级矿山公园申报材料内容翔实,符合相关文件要求,通过对矿山公园各项指标的综合打分,永城市日月湖省级矿山公园顺利通过专家评审。永城市日月湖省级矿山公园位于永城市东城区、西城区和产业集聚区三者结合部,是一座以展示采煤塌陷区地质环境治理为主,融合湿地水体景观,兼具城市建设发展和旅游服务的综合型矿山公     

加强国土资源专业档案统一管理的建议

国土资源档案是指国土资源管理部门及所属单位在各项专业工作中直接形成的、具有保存价值的各种文字材料、图纸、图表、计算材料、声像等原始记录。随着我国社会主义市场经济的发展和社会的进步,国土资源档案已经在我国经济建设中占据着重要的地位。     

新课改初中学生英语阅读能力的培养

阅读是英语学习中四项基本技能之一,英语教师应充分发挥教材的优势,培养学生的阅读兴趣,开发阅读潜能,训练阅读技巧,提高阅读水平,促进语言综合运用能力的提高。     

国土资源部办公厅关于调整国土资源部矿业权（非油气矿产）申请审批相关文件报送方式的函

各省、自治区、直辖市国土资源主管部门：为规范国土资源部与省级国土资源主管部门间矿业权申请审批相关文件报送方式,提高管理效率,现函告如下：一、自2014年9月1日起,省级国土资源主管部门及其相关处室出具的,以部矿产开发管理司（简称部开发司）为主送单位且与部发证矿业权审批直接相关的文件材料,均通过“国土资源主干网”（http：／／10．255．4．100：8080）上的“国土资源部远程申报系统”直接传输至部政务大厅,不再由矿业权申请人携带纸质件。     

煤矿开采覆岩移动规律的相似模拟研究

以淮南某煤矿1811（1）工作面为研究对象,利用相似材料模拟试验,分析受采动影响的上覆岩层的移动变形规律。结果表明,受采动影响的上覆岩层依次发育成冒落带、裂隙带、弯曲带。通过对下沉、倾斜、曲率、水平移动、水平变形五个参数的动态曲线分析,总结上覆岩层的力学状态。     

海洋微塑料研究挑战与展望

海洋微塑料污染是全球共同面对的重要环境问题之一。过去10 a,海洋微塑料研究发展迅速,但也暴露出一些亟待解决的关键科学问题,包括突破小粒径微塑料和纳米塑料的检测技术瓶颈、建立标准化的微纳塑料分析检测方法、优化海洋微塑料输运模型以及完善生态风险评估方案等。本文简要概述了近海、大洋和极地微塑料污染的现状,总结了海洋微塑料研究在样品采集和检测分析方面存在的挑战、在海洋微塑料存量估算和海洋微塑料输运模拟及生态风险评估方面存在的不足等,并展望了海洋微塑料未来研究方向,旨在为海洋微塑料常规监测、科学研究、风险评估和治理管控等方面提供借鉴和参考。