局部对称Lorentz空间中的类空超曲面

研究了局部对称Lorentz空间中具有常平均曲率或常数量曲率的类空超曲面.利用丘成桐的广义极大值原理和自伴随算子得到了两个重要的内蕴刚性定理,其分别推广了欧阳崇祯和刘新民的主要结果.     

基于碳量子点的绿色合成及生物成像研究进展EI北大核心CSCD

碳量子点(CQDs)作为碳纳米材料家族成员之一,因其原材料广、成本低廉、较高的光致发光性能和良好的生物相容性,在研究和应用领域都受到了广泛的关注,是应用于生物成像的理想材料。CQDs的绿色合成是指采用环保型或无毒型原料,通过绿色合成方法,如炭化法、微波法、水热法等,合成具有荧光性能的无毒碳量子点,与传统的化学氧化、激光烧蚀、热解处理等方法相比,更加绿色环保、经济,其应用已成为研究热点。本文对碳量子点材料特性、绿色合成过程机理、绿色合成原料来源、合成方法,及其在癌细胞、微生物细胞等细胞成像方面的应用进行了综述,探讨了绿色合成CQDs的利弊问题,并提出了今后该研究领域面临的机遇与挑战。     

S~n中子流形的Moebius特性

研究Sn中不舍脐点且Moebius形式为零的子流形的Moebius特性．首先得到子流形的Moebius标准数量曲率与截面曲率的一个关系定理,然后分别利用迹为零的Blaschke张量、Moebius标准数量曲率、截面曲率所满足的某种内蕴关系刻画了驴中子流形的Moebius特性．     

Transition Dipole Moment Measurements of Ultracold Photoassociated ~(85)Rb~(133)Cs Molecules by Depletion Spectroscopy

The transition dipole moments(TDMs) of ultracold85 Rb133 Cs molecules between the lowest vibrational ground level, (X~1Σ~+( v= 0, J= 1), and the two excited rovibrational levels, 2~3Π_0+(v′= 10, J′= 2) and 2~1Π_1(v′= 22,J′= 2), are measured using depletion spectroscopy. The ground-state85 Rb133 Cs molecules are formed from cold mixed component atoms via the 2~3Π_0-( v= 11, J= 0) short-range level, then detected by time-of-flight mass spectrum. A home-made external-cavity diode laser is used as the depletion laser to couple the ground level and the two excited levels. Based on the depletion spectroscopy, the corresponding TDMs are then derived to be 3.5(2)×10~(-3)eα_α and 1.6(1)×10~(-2)eα_α, respectively, where 0)(60 represents the atomic unit of electric dipole moment. The enhance of TDM with nearly a factor of 5 for the 21Π1(v′= 22, J′= 2) excited level means that it has stronger coupling with the ground level. It is meaningful to find more levels with much more strong coupling strength by the represented depletion spectroscopy to realize direct stimulated Raman adiabatic passage transfer from scattering atomic states to deeply molecular states.