A criterion for reduction of variables in the Willmore-Chen variational problem and its applications

We exhibit a criterion for a reduction of variables for Willmore-Chen submanifolds in conformal classes associated with generalized Kaluza-Klein metrics on flat principal fibre bundles. Our method relates the variational problem of Willmore-Chen with an elasticity functional defined for closed curves in the base space. The main ideas involve the extrinsic conformal invariance of the Willmore-Chen functional, the large symmetry group of generalized Kaluza-Klein metrics and the principle of symmetric criticality. We also obtain interesting families of elasticae in both lens spaces and surfaces of revolution (Riemannian and Lorentzian). We give applications to the construction of explicit examples of isolated Willmore-Chen submanifolds, discrete families of Willmore-Chen submanifolds and foliations whose leaves are Willmore-Chen submanifolds.

     

物理学的现状和未来(英文)

列举了物理学中100多个未解决的问题 ,阐明物理学中长期悬而未决的难题正是新物理学将要诞生的信号 ,人类探索物理学基本规律的努力总是值得的.Listing more than one hundred unanswered questions the present author claims that 1) the long standing puzzles in physics may be the signals of new physics; 2) the effort of searching for the basic natural laws of physics is always highly worthwhile.     

太阳极区矢量磁场研究 *

1997年4月12日 ,利用怀柔太阳观测站视频磁象仪的“深积分”观测模式 ,系统地测量了处于太阳活动极小年的极区矢量磁场 .研究发现 :极区磁场的方向偏离太阳表面的法线方向约40 .2°± 3.2° ;较强的磁元通常具有较小的偏离 ;在高于南纬5 0°的极冠区 ,总磁通量密度及净磁通量密度分别为7.8× 1 0 ^-4 T和 - 3.4× 1 0 ^-4T ;相应的总、净磁通量分别为 5 .5× 1 0 ¹⁴ Wb和 - 2 .5× 1 0 ¹⁴ Wb ;属于太阳大尺度磁场的这部分净磁通量 ,与在离太阳一个天文单位处测到的行星际磁场 (IMF)的量级是大致相等的 .     

PtSi超薄膜厚度的一种检测方法研究

介绍了采用角分辨X-射线光电子解谱(angle resolved X-ray photoelectric spectrum(ARXPS))测试薄膜不同角度光电子能谱强度,计算电子平均自由程,从而计算出PtSi超薄膜厚度的方法,并给出其透射电子显微镜(TEM)晶格象验证结果.实验表明该方法简单易行,适用于其他超薄膜厚度的测量 关键词： PtSi超薄膜 小角度X射线电子能谱 TEM晶格象     

聚DL-乳酸的合成及其热性能研究

以辛酸亚锡为催化剂催化丙交酯开环聚合DL-乳酸(PDLLA)。研究了影响PDLLA分子量的因素包括丙交酯单体的纯度、催化剂的浓度、反应温度、反应时间及真空度等。用DSC,TGA分析了不同分子量PDLLA的警警化转变和热失重。结果表明,PDLLA是热不稳定聚合物,残留的单体、催化剂及低聚物是影响PDLLA热稳定性的因素,除去其中残留的单体、催化剂及低聚物可以提高PDLLA的热稳定性。     

多足化合物的分子内激基缔合物形成及pH对其荧光的影响

研究了含萘脲基多足化合物溶液的稳态和瞬态光物理行为.由于分子内不同足间脲基的相互作用干扰了萘基的π-π叠合,使分子内萘基的激基缔合物生成受到影响.实验表明:由于三足化合物存在着给电子叔胺基团,因此当萘基被激发时、可因分子内的光诱导电子转移而导致荧光猝灭.正因如此,在三足化合物归一化后的稳态光谱中激基缔合物的发光强度很弱.用皮秒级单光子记数技术测得该化合物的瞬态荧光为三指数衰变过程.其中最长寿命的物种,即属于生成激基缔合物后再分解为萘激发态的部分仅占总量的4%,与稳态的结果相一致.工作表明对这类可用作荧光化学敏感器的三足化合物,如利用其激基缔合物的强度变化为其识别外来物种的敏感部位并不适合.相反,如引入的外来物种能影响化合物的分子内光诱导电子转移,进而影响萘基的发光强度,则是一较好的判别外来物种是否已进入主体的标志.     

Ultrafast spectroscopy studies on the mechanism of electron transfer and energy conversion in the isolated pseudo ginseng, water hyacinth and spinach chloroplasts

The spectroscopy characteristics and the fluorescence lifetime for the chloroplasts isolated from the pseudo ginseng, water hyacinth and spinach plant leaves have been studied by absorption spectra, low temperature steady-state fluorescence spectroscopy and single photon counting measurement under the same conditions and by the same methods. The similarity of the absorption spectra for the chloroplasts at room temperature suggests that different plants can efficiently absorb light of the same wavelength. The fluorescence decays in PS II measured at the natural QA state for the chloroplasts have been fitted by a three-exponential kinetic model. The three fluorescence lifetimes are 30, 274 and 805 ps for the pseudo ginseng chloroplast; 138, 521 and 1494 ps for the water hyacinth chloroplast; 197, 465 and 1459 ps for the spinach chloroplast, respectively. The slow lifetime fluorescence component is assigned to a collection of associated light harvesting Chl a/b proteins, the fast lifetime component to the react     

聚硅氧烷固载NADH模型物的设计合成及应用

设计合成了一类新型的高分子还原试剂聚硅氧烷固载烟酰胺辅酶(NADH)模型化合物4.该还原剂可以在温和条件下有效地还原活化烯烃,而且自身具有很好的循环再生性,是优良的绿色还原剂.     

Obstacle Effects on One-Dimensional Translocation of ATPase

We apply a general random walk model to the study of the ATPase's one-dimensional translocation along obstacle biological environment, and show the effects of random obstacles on the ATPase translocation along single-stranded DNA. We find that the obstacle environment can reduce the lifetime of ATPase lattice-bound state which results in the inhibition of ATPase activity. We also carry out the ranges of rate constant of ATPase unidirectional translocation and bidirectional translocation. Our results are consistent with the experiments and relevant theoretical consideration, and can be used to explain some physiological phenomena.     

Noise Effects on Oscillator Network of Transcription Regulators

Based on the model describing the regulation of the P_RM operator region of λ phage proposed by Jeff Hasty et al., we study the noise effects on the oscillator network. We find that the additive noise cannot change the period and the amplitude of the relaxation oscillator, but in the multiplicative case, the period of the relaxation oscillator increases to a constant value with the increase of the strength of noise, and the amplitude of the relaxation oscillator also shows increases with the increase of the strength of noise. This novel results suggest that an external multiplicative noise source could be used to control gene expression.