攀枝花地区水土流失动态变化研究

选择攀枝花市部分地区的Landsat-5 TM(1988年)和Landsat-7 ETM (1999年)遥感数据,通过遥感图像信息挖掘,提取植被覆盖度、沟谷分布、土地利用现状及土壤成土母质等信息,结合地形数据等水土流失因子;利用地理信息系统强大的空间分析功能,获取水土流失信息进行统计分析,对研究区水土流失的强度等级以及动态变化进行分析评价.研究表明,水土流失变化主要发生于植被覆盖不良的荒地和坡耕地上,其中坡耕地水土流失变得最严重,大部分为强度及强度以上级别水土流失区.从地貌上看,水土流失变化主要发生在低山、丘陵地区,这些地区人类活动频繁,植被破坏严重,大量开垦耕地,有利于水土流失发生.从岩类上看,半胶结砂岩、粘土岩岩组和紫红色泥岩、砂岩、页岩岩组分布区,由于多开垦为耕地,抗蚀能力弱,且多未实施保水保土措施,因此是水土流失严重的地区.     

A PPARγ-FGF1 axis is required for adaptive adipose remodelling and metabolic homeostasis

Although feast and famine cycles illustrate that remodelling of adipose tissue in response to fluctuations in nutrient availability is essential for maintaining metabolic homeostasis, the underlying mechanisms remain poorly understood. Here we identify fibroblast growth factor 1 (FGF1) as a critical transducer in this process in mice, and link its regulation to the nuclear receptor PPARγ (peroxisome proliferator activated receptor γ), which is the adipocyte master regulator and the target of the thiazolidinedione class of insulin sensitizing drugs. FGF1 is the prototype of the 22-member FGF family of proteins and has been implicated in a range of physiological processes, including development, wound healing and cardiovascular changes. Surprisingly, FGF1 knockout mice display no significant phenotype under standard laboratory conditions. We show that FGF1 is highly induced in adipose tissue in response to a high-fat diet and that mice lacking FGF1 develop an aggressive diabetic phenotype coupled to aberrant adipose expansion when challenged with a high-fat diet. Further analysis of adipose depots in FGF1-deficient mice revealed multiple histopathologies in the vasculature network, an accentuated inflammatory response, aberrant adipocyte size distribution and ectopic expression of pancreatic lipases. On withdrawal of the high-fat diet, this inflamed adipose tissue fails to properly resolve, resulting in extensive fat necrosis. In terms of mechanisms, we show that adipose induction of FGF1 in the fed state is regulated by PPARγ acting through an evolutionarily conserved promoter proximal PPAR response element within the FGF1 gene. The discovery of a phenotype for the FGF1 knockout mouse establishes the PPARγ–FGF1 axis as critical for maintaining metabolic homeostasis and insulin sensitization.     

Observation of robust edge superconductivity in Fe(Se,Te) under strong magnetic perturbation

The iron-chalcogenide high temperature superconductor Fe(Se,Te) (FST) has been reported to exhibit complex magnetic ordering and nontrivial band topology which ...     

矩形通道内航空煤油流动换热数值研究

针对先进动力装置利用航空煤油实现再生冷却的现实需求,建立了矩形冷却通道流/固/热耦合的三维数值模型,分析了入口质量流量、压力、热流密度等工况条件对矩形通道内航空煤油流动传热特性参数的影响。结果表明：增大质量流量和减小热流密度都会提升航空煤油的换热能力;在一定压力范围内,压力对航空煤油换热的影响不明显,但随着压力的增加,煤油的换热能力变差;由于传热恶化的发生,上述工况对压力损失和摩擦阻力的影响较为复杂。     

用Newton-Raphson法求解复合材料多层板壳大挠度非线性问题

本文在文献［１］的基础上,对复合材料多层板壳大挠度非线性问题建立了适合用Ｎｅｗｔｏｎ－Ｒａｐｈｓｏｎ法求解的关系式。文中分析了四边简支的复合材料多层矩形扁壳,与小挠度线性理论解析解及ＡＤＩＮＡ非线性解进行了对比。结果表明,载荷较大发生大挠度时,本文的大挠度非线性解和ＡＤＩＮＡ非线性解非常接近,和小挠度解析解有较大差别     

水中藻毒素降解的影响因素及其净水工艺控制

藻毒素污染已成为普遍关注的水质问题，在水环境中，藻毒素的迁移转化受光照、温度、有机物、溶解氧、水生生物等因素的共同影响。单元净水工艺（混凝、沉淀、砂滤、氯化等）和常规组合工艺对藻毒素的去除率较低，常规工艺＋活性炭过滤、臭氧＋常规工艺的去除率可达100％，不破坏藻细胞而能够大量降低其数量的预处理＋臭氧＋常规工艺＋ 性炭工艺应能够取得最佳的解毒效果。     

New data regarding acritarch biostratigraphy from the Early-Middle Cambrian Kaili Formation in Chuandong, Guizhou Province, China

Previous studies have evaluated acritarchs from the Balang and Pingzhai sections of the Early-Middle Cambrian Kaili Formation in east Guizhou, China. The results of these studies suggest that the acritarchs in these sections have potential biostratigraphic significance. More recently, 34 samples collected from 83m lower part of the Lower-Middle cambrian Kaili Formation in the Jianshan section of Chuandong, Guizhou Province were prepared for palynological analysis. Analysis of these samples revealed a distinct change in the acritarch assemblages at the bed, which was approximately 46m above the bottom of the Kaili Formation. These findings suggest a boundary represented by an important alteration of the ecological environment. In addition, the position of the acritarch biostratigraphic change is somewhat higher than the boundary between Cambrian Series 2 and Series 3 based on trilobites found in the same section. This indicates that the distinct change in acritarch assemblages is similar to the change in trilobite assemblages that occurs around the boundary between Cambrian Series 2 and Series 3. Therefore, acritarch biostratigraphy can provide data that can be used to define the base of Cambrian Series 3 in this region, and possibly worldwide.     

建基面强度对拱坝应力、变形的影响

建基面是传递拱坝和基岩相互作用的纽带,它的强度直接影响基岩对坝体的约束,从而影响坝体的应力和变形,用非线性有限单元法,以设计中的某高拱为例,分析建基面强度对坝体应力和变形的影响,结果表明建基面强度对坝体应力的影响仅限于建基面附近的局部范围,对最大主拉应力的影响要大于对最大主压应力的影响,建基面强度的降低不会无限地增大坝体的应力数值;建基面强度对坝顶位移的影响较小,但对坝底位移（尤其是顺河向相对位移）的影响较大,当建基面强度较低时,坝底顺河向相对位移随建基面强度的降低而增大。     

旋挖成孔方式下螺纹状围岩粗糙度量化分析

嵌岩桩是大跨径桥梁工程中常用的一种基础形式。由于钻孔工具等因素,桩-岩界面上会形成系列起伏的三维粗糙体,其对桩基承载性能至关重要。因此准确量化实际三维桩-岩粗糙体的粗糙度特征,是建立基于界面粗糙度的桩基承载力设计方法首先需要解决的问题。为此,依托于马鞍山长江大桥深嵌岩桩基工程,在现场钻取含三维粗糙体的砂岩试样,利用三维激光扫描重塑桩-岩界面数字化模型,对其粗糙度特征值,面积扩展率S、相对平均起伏度Rs和桩-岩界面平均倾斜角θ 等进行量化分析;而后构建桩-岩界面试样开展3组界面剪切试验和3组界面抗压试样以计算试样的JRC3D值,并基于试验结果验证已有JRC3D经验计算方法对桩-岩界面的适用性。结果表明:（1）实际桩-岩界面既有规则的螺纹状凹槽,也有起伏较低的相对平整面,而非室内试验中规则粗糙体或不规则孔洞;（2）实际桩-岩界面粗糙度远大于岩体结构面和室内规则粗糙体,面积扩展率、相对平均起伏度和界面平均倾斜角均明显较大;（3）桩-岩界面JRC3D均值为26.15,大于岩体结构面（标准轮廓线上限值20）和室内规则粗糙体,可近似采用公式7估算。研究成果可为建立基于界面粗糙度的深嵌岩桩设计方法提供科学依据。     

5′—硝基水杨基荧光酮—N—氯化十六烷基吡啶分光光度法测定微量铜

详细研究了 5′-硝基水杨基荧光酮 -CPC与铜形成三元络合物的显色反应条件和光度性质 ,结果表明 :在 p H6.55的缓冲溶液中 ,铜与试剂形成三元络合物 ,其最大波长在 563 nm,表观摩尔吸光系数为 1 .3 6× 1 0 5L· m ol-1· cm-1,铜含量在 0～ 7μg/2 5ml范围内符合比耳定律 ,本法通过巯基棉分离 ,测定了环境水样中铜的含量 ,结果较好