Enhancement of light-emitting efficiency using combined plasmonic Ag grating and dielectric grating

Based on the analysis of the near-field evanescent wave in total internal reflection, the flip-chip light-emitting diode (LED) structure was proposed by placing a plasmonic Ag grating and a perforated sapphire grating in the substrate. The finite difference time domain (FDTD) method has been applied to study the spectral properties of the hybrid structure and the enhancement factor of light extraction efficiency of the LED model. From the computation examples, the effects of structure parameters on the extraction enhancement have been investigated. The results indicate that the plasmonic grating can enhance the near-field evanescent wave and couple it to propagation wave in the specific wavelength bands, which leads to the photons emitting out of the LED chip with high extraction efficiency. Due to the combined gratings used, the enhancement factor of the light extraction efficiency can reach approximately 4 times at a relatively longer wavelength.     

Copper‐catalyzed asymmetric 1,4‐conjugate addition of dialkylzinc to enones

Asymmetric 1,4‐conjugation addition of dialkylzinc (diethylzinc and dimethylzinc) to cyclic enones, chalcone and nitroalkenes was achieved by a 25 mol% (R)‐6,6′‐Br₂‐BINOL( 1f ), 25 mol% CuSPh and 100 mol% dicyclohexylmethylamin(Cy₂NMe) catalyst system. The Cu(I) catalyst system enables the cyclic enone, chalcone and nitroalkene generality with high enantioselectivity (up to 84% ee) and isolated yield (up to 94%) under mild reaction conditions. Copyright © 2010 John Wiley & Sons, Ltd.     

旋流扩散燃烧中旋流数对热NO生成的影响

本文对旋流扩散燃烧进行了数值模拟，研究旋流数对热ＮＯ生成的影响，其中对湍流采用Ｒｅｙｎｏｌｄｓ应力方程模型，对燃烧采用ＥＢＵ－Ａｒｒｈｅｎｉｕｓ模型，对热ＮＯ生成采用设定ＰＤＦ的模型。预报了不同旋流数下轴向和切向的平均和脉动速度、温度和ＮＯ浓度，指出随着旋流数的增大，计算得到的出口平均ＮＯ浓度首先升高然后下降。这一趋势和本文作者最近的实验结果的趋势一致．随着旋流数的增大，湍流脉动首先下阵然后升高，而进口附近的温度上升，二者综合效果造成上述趋势、因此在实际燃烧器中，完全靠改变族流数来控制ＮＯ生成是不现实的。应该采取其他方法来降低ＮＯ的生成。     

Palladium-catalyzed cross-coupling of benzylzinc reagents with 2-bromo-3,3,3-trifluoropropene

α-Trifluoromethyl alkenes can be used as peptide isosteres, moreover, the pre-installed vinyl group make it possible that transformation to diverse fluorine-containing unities. However, the cross-coupling of benzyl group with α-trifluoromethyl alkenes has yet to be developed. In this report, we describe a general method for the cross-coupling of benzylzinc reagents with 2-bromo-3,3,3-trifluoropropene (BTP) to afford diverse α-trifluoromethylalkene derivatives by using Pd(TFA)₂ as catalyst. This method takes advantage of cheap industrial available fluorine building blocks and easily prepared benzylzinc reagents to generate α-trifluoromethylalkene derivatives, which features with mild reaction conditions, wide substrate scope and feasibility of product transformations.     

Modular amino acid amide chiral ligands for enantioselective addition of diethylzinc to aromatic aldehydes

Enantioselective addition of diethylzinc to a series of aromatic aldehydes was developed using a modular amino acid amide chiral ligand (2S)‐3‐phenyl‐N‐((R)‐1‐phenyl‐ethyl)‐2‐(tosylamino)propanamide without using titanium complex. The catalytic system employing 10 mol% of 1g was found to promote the addition of diethylzinc (ZnEt₂) to a wide range of aromatic aldehydes with electron‐donating and electron‐withdrawing substituents, giving up to 82% ee of the corresponding secondary alcohol under mild conditions. Copyright © 2011 John Wiley & Sons, Ltd.     

Compact laser system for atom interferometry

We describe an optical bench in which we lock the relative frequencies or phases of a set of three lasers in order to use them in a cold atom interferometry experiment. As a new feature, the same two lasers serve alternately to cool atoms and to realize the atomic interferometer. This requires a fast change of the optical frequencies over a few GHz. The number of required independent laser sources is then only three, which enables the construction of the whole laser system on a single transportable optical bench. Recent results obtained with this optical setup are also presented. PACS 32.80.Pj; 42.50.Vk; 39.20.+q     

类锂离子2s2p2p^2S三激发态的能量和宽度

采用马鞍点变分方法和复数转动技术，计算了类锂离子２ｓ２ｐ２ｐ２Ｓ三激发共振态的能量，并运用截断变分方法得到能量改进量，以及计算了相对论效应、质量极化效应，从而获得了高精度的能量计算值。还计算了该系统的Ａｕｇｅｒ宽度，位移和辐射跃迁率。