二维点缺陷三角晶格光子晶体的微腔结构

通过平面波展开法对二维点缺陷三角晶格光子晶体的微腔结构进行研究,计算得出其色散图以及缺陷模分布.结果表明:缺陷模波长与微腔谐振波长基本吻合.利用FDTD模拟谐振波长波段的电磁波在光子晶体中传播的动态演化过程,并计算出局域模的空间分布图.最后在有规律地改变缺陷周围介质柱半径的情况下实现谐振中心波长的可调性.     

Sub-nanosecond silicon-on-insulator optical micro-ring switch with low crosstalk

<正>We demonstrate a sub-nanosecond electro-optical switch with low crosstalk in a silicon-on-insulator(SOI) dual-coupled micro-ring embedded with p-i-n diodes.A crosstalk of -23 dB is obtained in the 20-μm-radius micro-ring with the well-designing asymmetric dual-coupling structure.By optimizations of the doping profiles and the fabrication processes,the sub-nanosecond switch-on/off time of400 ps is finally realized under an electrical pre-emphasized driving signal.This compact and fast-response micro-ring switch,which can be fabricated by complementary metal oxide semiconductor(CMOS) compatible technologies,have enormous potential in optical interconnects of multicore networks-on-chip.     

Fluorescence lifetime imaging of molecular rotors to map microviscosity in cells

Fluorescence liftime imaging （FLIM） of modified hydrophobic bodipy dyes that act as fluorescent molecular rotors shows that the fluorescence lifetime of these probes is a function of the microviscosity of their environment. Incubating cells with these dyes, we find a punctate and continuous distribution of the dye in cells. The viscosity value obtained in what appears to be endocytotic vesicles in living cells is around 100 times higher than that of water and of cellular cytoplasm.Time-resolved fluorescence anisotropy measurements also yield rotational correlation times consistent with large microviscosity values. In this way, we successfully develop a practical and versatile approach to map the microviscosity in cells based on imaging fluorescent molecular rotors.     

真空短间隙微弧级联效应观测

利用0.5 mm间隙微通道板成像器观测了微弧放电的斑点级联效应.实验发现,微弧阴极斑点的运动轨迹呈多类型的折线轨迹,斑点间隙在200—300 μm,首发射阴极斑点的放电强度比次级斑点高一个量级以上,而且次级斑点之间的放电强度相对稳定,次级斑点在放电阴极表面无融蚀现象.实验表明,次级斑点产生机制与首发射存在较强的依赖关系.     

理想微裂纹系统演化的特征

本文以微裂纹数密度分布函数描述理想微裂纹系统,考察其演化的一般特征,对微裂纹的扩展过程采用了确定论的模型,发现,在一定条件下,微裂纹数密度的演化可出现饱和现象,本文用几个例子具体显示了理想微裂纹系统的统计行为,并与实验观察结果进行了初步比较。     

微通道内红细胞流动与变形的可视化研究

微循环条件下,红细胞的尺寸与血管相近,血液不能视为均质流体,其流动表现出较强的颗粒性,红细胞流变特性对血液流动有较大影响。本文使用高倍显微镜对微流控芯片矩形截面微通道内红细胞的流动和变形特性进行可视化观察研究,并使用高速CCD相机拍摄和捕捉了红细胞在微通道内的流动和变形过程。通过观察不同浓度、粘度和速度下红细胞的聚集性、变形性以及常见的运动形态,发现红细胞在低粘度、低速流动条件下表现为两面凹圆盘形,沿流动方向运动过程总是伴随着翻转与旋转;在高粘度、高速运动条件下,红细胞表现为扁平椭圆形、呈坦克履带式(TTM)前进。     

B→K0^＊（1430）η（＇） decays in the pQCD approach

Based on the assumption of two-quark structure of the scalar meson K0^＊（1430）, we calculate the CP-averaged branching ratios for B→K0^＊（1430）η（＇） decays in the framework of the perturbative QCD （pQCD） approach here. We perform the evaluations in two scenarios for the scalar meson spectrum. We find that： （a） the pQCD predictions for Br（B→K0^＊（1430）η（＇）） which are about 10^-5 10^-6, basically agree with the data within large theoretical uncertainty; （b） the agreement between the pQCD predictions and the data in Scenario Ⅰ is better than that in Scenario Ⅱ, which can be tested by the forthcoming LHC experiments; （c） the annihilation contributions play an important role for these considered decays.     

Study of scalar meson a0（980） from B → a0（980）π decays

In this paper, we calculate the branching ratios and the direct CP-violating asymmetries for decays B^0 → a0^0（980）π^0, a0^＋ （980）π^-, a0^-（980）π^＋ and B^- → a0^0 （980）π^-, a0^- （980）π^0 by employing the perturbative QCD （pQCD） factorization approach at the leading order. We found that （a） the pQCD predictions for the branching ratios are around （0.4-2.8） × 10^-6, consistent with currently available experimental upper limits; （b） the CP asymmetries of B^0→ a0^0（980）π^0 and B^- → a0^- （980）π^0 decays can be large, about （70-80）% for α= 100°.     

B→（J/ψ,η_c）K decays in the perturbative QCD approach

In this paper,we calculated the B →（J/ψ,ηc） K decays in the perturbative QCD（pQCD） factorization approach with the inclusion of the partial next-to-leading order（NLO） contributions. With the inclusion of the significant enhancement from the NLO vertex corrections,the NLO pQCD predictions for the branching ratios agree with the data within 2σ errors：Br（B0 → J/ψK0） = 5.2-＋32..58×10-4,Br（B＋ → J/ψK＋） = 5.6-＋32..79×10-4,Br（B0 →ηcK0） = 5.5-＋22..30 × 10-4,Br（B＋ →ηcK＋） = 5.9-＋22..51 × 10-4.     

Recent results from LEPS

Photoproduction of baryons with strangeness,such as the Σ（1385）,Λ（1520） and possibly the Θ ＋,are described from measurements at the LEPS/SPring-8 facility in Japan.Linearly polarized photons in the energy range of 1.5–2.4 GeV,along with the forward-angle kinematics at LEPS,provide unique data to learn about these baryons,which are non-perturbative solutions of QCD.