Magsat studies over the Indian region

Data collected by Magsat have been extensively used by Indian scientists in studies of the crust beneath India. Results obtained by various workers have been summarized and the reasons for differences in findings have been discussed. It is concluded that methods that work well for higher latitudes do not give the best estimates of crustal field and magnetization in equatorial regions. A better estimate of the crustal component is obtained when the external current contribution is estimated using the symmetry properties of associatedX and Z-fields. Inversion technique that provides stable crustal magnetization in midlatitudes, becomes unstable near the equator. Why such an instability arises and how it can be circumvented are discussed. That the Peninsular shield, the Ganga basin and the Himalayas are three different geotectonic blocks is clearly reflected in the magnetization distribution. A thick magnetic crust under Aravalli, Singhbum and Dharwar suggest these areas to be comparatively stable. In general, seismic, gravity and heat flow data agree characteristically well with the magnetization estimates.     

珊瑚礁岩的磁性初步研究

南沙群岛南永１井珊瑚礁岩的磁性测量结果表明，珊瑚礁岩的磁化率（Ｘ）为负值，属抗磁性物质，但它有较稳定的剩余磁化强度（Ｍｒ），而且它的ＮＲＭ（天然剩余磁化强度）近似对数正态分布，其值大部分分布在（０．８－１．６）×１０（－４）Ａ·ｍ（－１）区间内。进一步研究发现珊瑚在生长过程中，富铁细菌及水介质等可以在珊瑚礁孔隙中留下铁磁性物质；另一方面，珊瑚在生长时也可能吸收铁离子，变成珊瑚礁骨骼的一部分。因此，珊瑚礁岩具有铁磁性，在古地磁场作用下，产生弱剩磁。     

南沙海区沉积物剩余磁化强度与古气候旋回

根据南沙海区NS87-11柱样沉积物Mr(剩余磁化强度)的变化曲线与δ~(18)O(氧同位素)变化曲线平行对比,发现Mr的波峰、波谷与δ~(18)O揭示的古气候变化的波峰、波谷相对应。表明南沙海区沉积物的Mr记录了暖→冷→暖古气候旋回变化的特征,反映了全球性气候变化的波动周期。微体古生物分析结果可以证实这一特征。这预示海洋沉积物的Mr不仅可作为探索古气候变化的重要标志,而且可能成为第四纪磁性地层对比、划分的依据。     

Timing and rate of isothermal decompression in Pan-African granulites from Rundvågshetta, East Antarctica

Geochronological data, combined with field and petrological evidence, constrain the timing and rate of near‐isothermal decompression at granulite facies temperatures in rocks from the Lützow‐Holm Complex of East Antarctica. Granulite facies gneisses from Rundvågshetta in Lützow‐Holm Bay experienced a peak metamorphic temperature of over 900 °C at c. 11 kbar, as evidenced by primary orthopyroxene–sillimanite‐bearing assemblages, and secondary cordierite–sapphirine‐bearing assemblages in metapelites. Peak metamorphic assemblages show strong preferred mineral orientation, interpreted to have developed synchronously with pervasive ductile deformation. Zircon from a syndeformational leucosome has a U–Pb age of 517±9 Ma, which is interpreted as a melt crystallization age. This age provides the best estimate of the time of peak metamorphic conditions. The post‐peak metamorphic history is characterized by near‐isothermal decompression, recorded by mineral textures in a variety of rock compositions. Field and textural relations indicate that decompression post‐dated pervasive ductile deformation. K/Ar and ⁴⁰Ar/³⁹Ar ages from hornblende and biotite represent closure ages during cooling subsequent to decompression, and indicate cooling to temperatures between c. 350 and 300 °C by c. 500 Ma, thus placing a lower time limit on the duration of the high‐temperature isothermal decompression episode. The combination of the zircon age from a syndeformational melt with K/Ar and ⁴⁰Ar/³⁹Ar closure ages indicates that near‐isothermal decompression from c. 11 to c. 4 kbar at granulite facies temperatures, followed by cooling to c. 300 °C, took place within a time interval of 20±10 Myr. Simple one‐dimensional models for exhumation‐controlled cooling indicate that these data require exhumation rates of the order of c. 3 km Myr^?1 for several million years, then cessation of exhumation followed by relatively isobaric cooling during thermal re‐equilibration.     

环介导等温扩增联合横向流动试纸条快速检测扁浒苔(Ulva compressa)的研究

本研究将环介导等温扩增技术(loop-mediated isothermal amplification,LAMP)与横向流动试纸条(lateral flow dipstick,LFD)的可视化检测方法结合,建立了扁浒苔(Ulva compressa)的LAMPLFD快速检测技术。该方法以扁浒苔的内转录间隔区(ITS1-5.8S-ITS2)序列为检测靶标,设计了3对特异性引物(其中,上游内引物由生物素标记)和1条异硫氰酸荧光素标记的探针。结果表明,LAMP最适反应温度为63°C,扩增时间为60 min,从核酸扩增到LFD结果判读需70 min。利用LAMP-LFD可特异性检出扁浒苔,对浒苔、曲浒苔、缘管浒苔和孔石莼等石莼属绿藻以及塔玛亚历山大藻、无纹环沟藻、东海原甲藻、锥状斯克里普藻和赤潮异弯藻等常见微藻的检测结果为阴性。该方法最低可检测到0.1 pg的扁浒苔基因组DNA,是以Uco ITS-F3和Uco ITS-B3为特异性引物的PCR方法的100倍。对实际样品的检测结果表明,LAMP-LFD方法检测扁浒苔与传统的形态学观察的结果一致。因此,该方法可快速、特异地检测出扁浒苔,而且操作简单,仪器设备依赖性低,有潜力成为扁浒苔现场检测的常规技术手段。     

N，N’-双（3-氨丙基）草酰胺合铜非等温热分解动力学研究

采用 TG- DTG- DTA热分析技术研究了 N,N’-双 (3-氨丙基 )草酰胺合胴 ( )配合物在动态空气气氛中的热行为 ;用微分法 (Achar法 )和积分法 (Coats- Redfen法 )协同处理非等温 TG数据 ,通过对比热分解动力学参数 E和 ln A,提出了配合物第一阶段热分解动力学方程 :dα/ dt =Ae- E/ RT (1-α ) 2 及第二阶段热分解动力学方程 :dα/ dt=Ae- E/ RT(1-α) ;并由动力学补偿效应获得了 E和 ln A的数学表达式