Repair of articular cartilage in rabbit osteochondral defects promoted by extracorporeal shock wave therapy

Shock Waves - This study investigated the stimulative effect of extracorporeal shock wave therapy (ESWT) on the articular cartilage regeneration in the rabbit osteochondral defect model for the...     

基于模拟退火-粒子群算法的卤素灯阵列照度均匀性研究

光照均匀性问题是太阳模拟器照明系统的主要问题。针对目前卤素灯作为光源进行灯阵光照均匀性的阵列设计多采用理论计算的方法,复杂繁琐,不易施行的缺点,将数值优化方法应用于卤素灯阵列结构设计中,与单一的算法不同,模拟退火算法与粒子群算法相结合的方式,突破了单一算法的局限性,得到的结果更加良好,均匀性更佳。通过编程优化灯阵中每个灯的坐标,将最优结果导入光学仿真软件进行照度分析,实验数据显示,3种灯阵下的光照均匀度分别为91%、87%和91%,同等条件下的六边形灯阵的光照均匀度要比圆形的均匀度好,采用最优化方法,可使实验更加简单可行。     

Improved performances on surface‐enhanced Raman scattering based on electrochemically roughened gold substrates modified with SiO2 nanoparticles

In this work, we use electrochemical oxidation–reduction cycles (ORC) methods to prepare surface‐enhanced Raman scattering (SERS)‐active gold substrates modified with SiO₂ nanoparticles to improve the corresponding SERS performances. Based on the modified substrates, the SERS of Rhodamine 6G (R6G) exhibits a higher intensity by 3‐fold of magnitude, as compared with that of R6G adsorbed on a SERS‐active Au substrate without the modification of SiO₂ nanoparticles. Moreover, the SERS enhancement capabilities of the modified and the unmodified Au substrates are seriously destroyed at temperatures higher than 250 and 200 °C, respectively. These results indicate that the modification of SiO₂ nanoparticles can improve the thermal stability of SERS‐active substrates. The aging in SERS intensity is also depressed on this modified Au substrate due to the contribution of SiO₂ nanoparticles to SERS effects. Copyright © 2009 John Wiley & Sons, Ltd.     

O + NH反应在3A’’和1A’’势能面上的量子含时波包动力学研究

对于O + NH反应,在3A’’和1A’’ 势能面（Guadagnini R, Schatz G C, Walch S P. Global potential energy surface for the lowest 1A’, 3A’’, and 1A’’ states of HNO [J]. J. Chem. Phys., 1995,10:774）上,我们运用coupled state or centrifugal sudden (CS)近似和close coupling or Coriolis coupled (CC)方法进行了量子动力学计算。通过比较两种方法得到的总的反应几率,我们发现对于两个势能面上的标题反应,CS近似是失效的。我们还讨论了用CS和CC方法得到的速率常数,并进行了结果比较。     

Charge dynamics of the spin-density-wave state in BaFe<Subscript>2</Subscript>As<Subscript>2</Subscript>

We report on a thorough optical investigation of BaFe₂As₂ over a broad spectral range and as a function of temperature, focusing our attention on its spin-density-wave (SDW) phase transition at T_SDW = 135 K. While BaFe₂As₂ remains metallic at all temperatures, we observe a depletion in the far infrared energy interval of the optical conductivity below T_SDW, ascribed to the formation of a pseudogap-like feature in the excitation spectrum. This is accompanied by the narrowing of the Drude term consistent with the dc transport results and suggestive of suppression of scattering channels in the SDW state. About 20% of the spectral weight in the far infrared energy interval is affected by the SDW phase transition.     

Research on the resolution of micro stereo lithography

Micro stereo lithography is a kind of technology utilizing the solidified effect that photo curable polymer will appear under ultraviolet （UV） laser exposure. It is widely used in three-dimensional （3D） micro fabrication. We get the experimental values of a pair of UV laser curing coefficients, absorption coefficient and critical curing energy, of curable resin by fitting the calculation results of the Gaussian beam theory and experimental curing results. The theoretical relation between the curing unit＇s shape and the exposure features of time and intensity of convergent Gaussian beam is presented. The calculation and experimental results of curing unit under different conditions agree well with each other. This research offers a steady base for further research about the improvement of resolution.     

Propagation of coherently combined flattened laser beam array in turbulent atmosphere

The analytical expression for the propagation of a flattened laser beam array in a turbulent atmosphere is derived based on extended Huygens–Fresnel principle. The influence of beam order and turbulent atmosphere on beam quality is studied. It is revealed that the beam quality of a coherently combined laser beam array with higher order is better than its lower order counterpart when propagating in free-space, weak and medium turbulence (i.e. C_n²<10^?13 m^?2/3). The beam quality of higher order beam arrays degrades faster as the intensity of turbulence gets stronger. In the case of propagating in strong turbulence, the beam order has no influence on coherently combined beam quality.     

Early energy decays in two churches in Hong Kong

Acoustical measurements based on impulse responses have been made in a Protestant and a Catholic church in Hong Kong. Analysis has concentrated on reverberation time, early decay time and C₈₀, the early-to-late ratio, as well as integrated decays. The measured results have been compared with predictions according to two different theoretical room acoustic models: a model for a single diffuse space and one for a set of coupled-rooms. The comparison has shown that treating the churches as a series of coupled spaces is more valid. However the clarity, C₈₀, at different receiver positions was found to be either under- or over-estimated by the classical coupled-room model. Following this observation, a delayed coupled-room model was developed in the hope of achieving more accurate predictions. In this model, the initial condition under the impulse excitation was modified by introducing a time delay for sound propagated from the source to achieve diffuse sound fields in each subspace. The predicted results of the coupled-room model agree well with the measured results.     

Irreversible structural transformation of Si(1 1 4)-2 × 1 induced by subsurface carbon

Using scanning tunneling microscopy (STM), it has been found that the reconstruction of Si(1 1 4) is transformed irreversibly from a 2 × 1 structure composed of dimer (D), rebonded atom (R), and tetramer (T) rows (phase A) to a different kind of 2 × 1 structure composed of D, T, and T rows (phase B) by C incorporation. It has been confirmed by high-resolution synchrotron core-level photoemission spectroscopy (PES) that such an irreversible structural transformation is due to stable subsurface C atoms. They induce anisotropic compressive stress on the surface, which results in insertion of Si dimers to an R row to form a T row.     

贵金属助剂对费-托合成用钴基催化剂的促进作用

贵金属助剂促进的费-托合成用钴基催化剂具有高活性和长链烃(C₅⁺)选择性优越等特点,被广泛应用于由合成气制清洁燃料的合成反应中。 本文重点讨论了贵金属助剂对活性钴物种的结构（还原度、分散度、双金属颗粒或合金的构成）, 钴基催化剂稳定性以及其对费-托合成的反应速率和产物选择性的影响规律。