Electron Spin Resonance Studies of Mn^2＋ in Freshwater Snail Shells： Pomacea Canaliculata Lamarck and Fossilized Snail Shell

We study paramagnetic Mn^2 ions present in the nowadays shells of univalve freshwater snails of Pomacea canaliculata lamarck (PCL) and the fossilized freshwater snail (FFS), Viviparus. All these shells are abundant in Thailand. The PCL shells were ground into fine powder. A set of seven samples were then separately annealed for 2 h in air atmosphere at different annealing temperatures while the FFS powder was characterized as-received. The PCL shells mainly consist of aragonite and a fraction of calcite. The heat treatments of the PCL powder samples at temperature higher than 450℃ resulted in an irreversible phase transformation from aragonite to calcite. However, it is found that the FFS shell is mainly made of calcite, with a minor fraction of aragonite. The crystal structure of the high-temperature-annealed PCL samples are quite similar to that of FFS, which indicates that the metamorphosis (aragonite→calcite) in the FFS shell had occurred but was not yet completed, although it had remained under the pressure and temperature of the Earth‘s crusts over millions of years. Our detailed ESR spectral analyses of PCL and FFS show that Mn^2 ions enter the Ca^2 sites during a biomineralization process. Simulated ESR parameters of PCL-500 of Mn^2 at a uniaxial site of calcite are reported. It is surprising to And that the ratio of Mn^2 concentration present in FFS to those in PCL shells evaluated from ESR spectra is as much as 10:1.     

用光来操纵活性生物分子

 现在展示在你面前的照片是一个红血球细胞(图1上)以及它被拉伸而变形的情形(图1下)。这是奥斯汀德克萨斯大学的一个研究组进行的研究细胞弹性的实验。他们用激光作工具,利用光进入细胞时产生的对细胞的作用力使细胞拉长,拉伸程度与激光的强度有关。由于细胞被癌病侵害后其弹性会发生改变,用这个办法能够筛选出有病细胞的数量。德克萨斯大学的这个实验也成功地证明了,如果一束激光照到一个完整的生物细胞上,在光进入细胞时对细胞有一个与进入方向相反的作用力,在光射出细胞时对细胞有一个与射出方向相同的作用力。那么这力是怎样产生的呢?其原理实际上并不很深奥。     

非晶态锂离子导体B2O3-0.7Li2O-0.7LiCl-xAl2O3-0.1V2O5的电学性质和电子自旋共振研究

对两种非晶态B₂O₃-0.7Li₂O-0.7LiCl-xAl₂O₃-0.1V₂O₅(x=0.05和0.15),用差热分析、电导率测量、X射线衍射和电子自旋共振进行研究,发现:1)V₂O₅不仅作非晶网络形成剂,而且改变了晶化过程;2)对B₂O₃-Li_{2关键词：}     

NASICON型化合物结构的NMR研究

在水热晶化合成一系列NASICON型化合物的基础上,应用固体高分辨³¹P和²⁹Si MAS NMR,研究了几种NASICON化合物的结构,观察其骨架原子P和Si在结构中的状态及分布,并解释了由于在结构中发生取代作用而引起,Si或P的化学位移的变化.     

折叠萝卜螺生物学初步研究

对采自南昌近郊池塘折叠萝卜螺一种群的生物学进行了初步研究，并就其贝壳的形态和其它种群作了比较，测量了210个折叠萝卜螺的壳高（H），壳宽（W）和体重（T），三者之间的关系可分别表示为：T＝0．0009H^2.632,T=0.0047W^1.8915,W=0.6899H-0.3437,在野外，折叠萝上课累在南昌地区从2－6月都能产卵，其中3－4月达高峰期，在室内3，5，6月为产卵高峰，4月几乎不产卵，折叠萝卜卵的孵化率很高，平均孵化率为95．66％，最高达100％，最低也有89．5％，幼螺的死亡率高达50％以上。     

Evaluation of Coulomb Energy Difference for Light Mirror Nuclei Using Slater—Type Orbitals

Behavior of the Coulomb energy difference for light nuclei is explained in terms of the different values of the average Coulomb interaction between two particles.Coulomb energy difference according to shell model of light mirror nuclei in the Coulomb and exchange integrals in the formula can be explained with exponential-type wavefunctions.In this study,using the one-center expansion of exponential-type wavefunctions in terms of Slater-type orbitals with the same center,we derived formula for Coulomb energy difference of light mirror nuclei.     

146Ce核的八级形变带和准γ带

通过测量²⁵²Cf自发裂变所产生的瞬发γ射线, 对¹⁴⁶Ce核的高自旋结构进行了重新研究, 结果更新了以前报道的能级纲图, 把八级形变集体带扩展到更高的自旋, 并且重新构建了可能的准γ带结构. 此外, 用反射不对称壳模型(RASM)对¹⁴⁶Ce核的八级形变带进行了计算, 低自旋处的计算结果与实验数据符合得很好.     

世界上第一只灯泡的诞生

19世纪初，欧美一些国家大多是用弧光灯来照明的，它是根据弧光放电的原理制成的：把两根炭棒分别接在一组电池的正、负极上，先使两根炭棒接触后，然后再拉开一点距离，这时电流依然能通过炭棒间的空隙，在两棒间产生电弧，从而发出强光，弧光灯虽然可以照明，但要