Preliminary research on Megalake Jilantai-Hetao in the arid areas of China during the Late Quaternary

We identified geomorphological, sedimentary and biological evidence of high lake levels around the current Jilantai Salt Lake through field investigations and through analyses of regional remote sensing images. There are four groups of shorelines at elevations of around 1060, 1050, 1044 and 1035 m a.s.l., being 37, 27, 21 and 12 m above the current salt lake surface, respectively. Littoral deposits of sand and gravels are found at elevations between 1070 and 1080 m a.s.l., 47 to 57 m higher than the current salt lake surface, although palaeoshoreline landforms are only preserved at several sites. At Herimuxini, on the northern margin of the Ulan Buh Desert, typical lacustrine sediments and sand-gravel littoral deposits also occur at elevations of 1080 m a.s.I, and below. A 11-km-long typical spit extends eastward from this shoreline gradually reducing in elevation from 1050 to 1035 m a.s.I. In some sand-gravel quarries along the southern bank of the Yellow River on its Great Bend, such as those located near the Hydrological Gauge Station and Shilazhao Town, shoreline features were identified. Littoral deposits overlying the alluvial-diluvial layers occur in a sand quarry near Balagong in Hangjin County. There are also beachrock and littoral deposits preserved on the cut-and-built terraces at several sites along the southern piedmont of Langshan-Yinshan Mountains. In addition, a profile revealing subaqueous delta sediments was identified near Wuhai, where the Yellow River enters the basin. Typical lake sediments also exist at the Togtoh Platform on the eastern end of the Hetao Plain. Aquatic Mollusk shells are common in the littoral deposits, including several species of Corbicula, Radix lagotis, R. xauricularia and Gyraulus convexiusculus. Ostracode shells can also be identified in finer sediments. Typical ver- tical prograding sequences are evident in outcrops where lacustrine sediments were well preserved. Wave-rolled cobbles and beachrock are very commonly preserved on the top of profiles in the embankments at     

一种新硫色满酮衍生物诱导人乳腺癌MCF-7细胞凋亡

初步研究了新合成的(顺)-3-(氯代亚甲基)-5-甲基-硫色满-4-酮(3-chloromethylene-5-fluoro-thiochroman-4-one,CMTK)对人乳腺癌MCF-7细胞增殖和凋亡的影响,分别用不同浓度的CMTK对细胞进行干预,采用改良的MTT法测定CMTK抑制细胞增殖的能力,台盼蓝染色法计数活细胞数,绘制生长曲线,流式细胞术检测细胞对细胞周期的影响,同时采用流式细胞术及TUNEL染色法(terminal dexynucleotidyl transferase(TdT)-mediated dUTP nick end labelling)检测CMTK诱导凋亡,活性检测法测定细胞中人半胱氨酸蛋白酶8(caspase-8)和人半胱氨酸蛋白酶9(caspase-9)的活性,ELISA法测人死亡受体3(deathreceptor3,DR3)、人肿瘤坏死因子受体1(tumor necrosis factor receptor1,TNFR1)、人肿瘤坏死因子-α(tumor necrosis factor-α,TNF-α)、人半胱氨酸蛋白酶3(caspase-3)的蛋白表达情况.结果表明,CMTK可明显抑制MCF-7细胞增殖,与顺铂(cisplatin,CDDP)相比,其抗肿瘤活性更明显,IC50为14.24±0.12molL1;生长曲线进一步说明CMTK抑制细胞增殖,其抑制作用呈时间-剂量依赖性;流式细胞仪检测分析显示,加药12和24h后可将细胞阻滞于G0/G1期(**P<0.05);TUNEL法和流式细胞仪分析CMTK可诱导凋亡的结果基本一致;与药物作用后,caspase-8和caspase-9的活性增高,并呈浓度剂量依赖性;ELISA法检测DR3蛋白量和TNF-细胞因子的量无变化,TNFR1和caspase-3的蛋白量显著增高,CMTK诱导肿瘤细胞凋亡的机制可能是:不仅可以通过死亡受体TNFR1介导凋亡途径,激活caspase-8;还可以通过线粒体凋亡途径,激活caspase-9;最终激活caspase-3凋亡通路.本研究为深入研究CMTK诱导肿瘤细胞凋亡的机制提供了依据.     

Visualization of coherent structures in a supersonic flat-plate boundary layer

Flow in a flat-plate zero-pressure-gradient boundary layer at Mach 3 was visualized via nanoparticle-based planar laser scattering (NPLS). Coherent structures such as an individual hairpin vortex and hairpin packet were identified in the streamwise-wall-normal plane on the basis of the now accepted hairpin model. Λ-shaped vortices were found in a staggered pattern in the stream-wise-spanwise plane, which indicated H-type transition in the present experiments. This is the direct evidence (in the form of flow...     

抗战时期西安工商业的繁荣及其原因浅析

近代以来，陕西因僻处西北内陆，交通不便，经济十分落后。但自1934年底陇海铁路通车西安后，西安工商业发展速度逐渐加快。尤其是全面抗战爆发后，随着华北、华南地区相继沦陷，陕西成为抗战的后方，沦陷区工厂、难民沿着陇海铁路大量涌入西安，使西安工商业在抗战时期迅速发展，成为西北地区最大的近代工商业城市。     

低密度二氧化硅气凝胶微观结构与隔热性能表征

以正硅酸乙酯为原料,采用溶胶-凝胶法及超临界流体干燥技术制备了密度为11kg/m³的低密度二氧化硅气凝胶块体材料,并与密度为25kg/m³和38kg/m³的二氧化硅气凝胶块体材料进行性能对比。采用扫描电子显微镜（SEM）、透射电子显微镜（TEM）、BET等检测方法对样品的微观结构进行表征,对比了不同密度低密度气凝胶的微观结构,并测试了不同温度下的导热系数。结果表明：相比于密度更大的气凝胶材料,11kg/m³低密度气凝胶具有更为纤细的骨架结构和更大的孔洞尺寸,以及较小的比表面积,室温条件下具有最大的导热系数;在气凝胶密度小于40kg/m³的范围内,呈现出密度越小,导热系数越大的规律。