利用蒙特卡洛方法计算陶瓷刀具磨损可靠性

在连续切削条件下,陶瓷刀具的失效形式是以磨粒磨损为主的摩损失效,其磨损寿命由材料的断裂韧性、硬度和切削过程的参数决定,利用蒙特卡洛方法分别随机生成断裂韧性与硬度的样本值,利用连续车削试验确定切削过程参数,将得到的样本值与切削参数相结合可计算刀具在相应切削条件下的磨损寿命及其可靠性,计算结果表明：陶瓷刀具的断裂韧对磨损寿命的可靠性影响较为明显,因而可以利用断裂韧性来估算磨损可靠性。     

宇宙核钟

以很长半衰期 ( 4 2× 1 0 9a)的 β-衰变的187Re-187Os核对作为大尺度的宇宙核钟来量度宇宙的年纪 ,是近代天文学与核物理学相结合的又一典范 .这种宇宙时钟是利用裸核187Re与它的衰变子体187Os同位素在共生矿中天然含量的比值来测定时间的 .利用187Re裸核的半衰期通过核物理计算可对中性 187Re的半衰期进行修定.To the great scale of the universe age, 187 Re- 187 Os isotopic pair, which have very long half life, was used as a cosmic nuclear clock of cosmochronometr. It is a typical relationship between modern astronomy and nuclear physics. The neutral isotope abundance ratio of 187 Re over daughter nucleus 187 Os in common growth mineral can be used as the clock to measure the time. After the 75 electrons in all shells of 187 Re were stripped ...     

Understanding Symmetric and Asymmetric DNA Patterns by Water Flow on a Solid Surface

In order to use DNA for making molecular device, specific DNA patterns on a solid surface should be constructed. In this paper, we will show that the random interactions between the DNA segments and the solid surface play an important role in the final symmetric and asymmetric DNA patterns obtained by water flow.     

带荧光基团蒽的正庚醛和正丁醛ReSOrcinarenes母体衍生物的合成研究

合成正庚醛、正丁醛Resorcinarenes母体,经生成酯衍生物后同－9蒽甲醇反应,合成了带荧炮光基团蒽的正庚醛、正丁醛Resorcinarenes母体衍生物,考察了各种因素对产物产率的影响,并给出了产物的IR,^1H NMR,MS及UV谱数据。     

铕(Ⅲ)荧光增敏体系在微乳液中的发光性质和荧光衰减动力学研究

利用稳态和瞬态光谱方法研究了不同铕离子发光体系中各种因素对铕离子发光性质的影响.通过吸收和激发光谱的变化分析了稀土离子Gd³⁺对Eu³⁺增敏机理,并从荧光衰减动力学角度证明了主配体噻吩甲酰三氟丙酮(TTA)、协配体邻啡咯啉(Phen)、稀土离子Gd³⁺和表面活性剂TX-100对铕离子发光的增敏作用.4种发光体系Eu³⁺/Gd³⁺/TTA/Phen/TX-100,Eu³⁺/TTA/Phen/TX-100,Eu³⁺/Gd³⁺/TTA/Phen和Eu³⁺/Gd³⁺/TTA/TX-100中铕离子⁵D₀态的发光寿命依次为980>670>400>260μs,而且存在铕离子⁵D₁到⁵D₀的传能过程.在发光越强的体系中,⁵D₁的衰减越慢,相应地⁵D₀的上升时间也就越长.研究结果表明,在最佳发光体系中既存在分子内的能量转移,又存在分子间的能量传递.     

Depsides from Prunella vulgaris

IntroductionPrunella vulgaris L.(Labiatae) is a traditional Chinese drug and has hypotensive, antibacterial, anti-viral, anti-inflammatory, anti-tumor and hypoglycemic activities. Previously, the isolation and structural identification of a new triterpene saponin and five known compounds from the ethanol extracts of P. vulgaris were reported1. In this paper, we describe the isolation of four depsides and two phenylpropanoids from the same source. Their structures were established as butyl ro…     

铕(Ⅲ)-二苯甲酰甲烷-铵阳离子配合物发光性质及 传能过程的溶剂效应研究

利用瞬态与稳态光谱研究了铕(Ⅲ)-二苯甲酰甲烷-铵阳离子系列新型配合物在乙醇、DMF和环己烷三种极性不同溶剂中的光谱性质,发现不同铵阳离子配合物在同种极性溶剂中的瞬态与稳态光谱性质几乎完全一致,而在非极性溶剂中略有差异。配合物在乙醇和DMF溶剂中荧光呈单指数衰减,在环己烷溶剂中呈双指数衰减。通过计算表明,在乙醇和DMF中,配合物中铕离子^5D~0激发态的能量布局不同。     

Current Reversal Due to Coupling Between Asymmetrical Driving Force and Ratchet Potential

Transport of a Brownian particle moving in a periodic potential is investigated in the presence of an asymmetric unbiased external force. The asymmetry of the external force and the asymmetry of the potential are the two ways of inducing a net current. It is found that the competition of the spatial asymmetry of potential with the temporal asymmetry of the external force leads to the phenomena like current reversal. The competition between the two opposite driving factors is a necessary but not a sufficient condition for current reversals.     

三氟甲烷磺酸催化1-茚酮氧化反应的研究

研究了三氟甲烷磺酸（HOTf）催化氧化1-茚酮的性能,考察了HOTf、H2O2的用量、反应时间、反应温度和溶剂等几个因素对反应的影响,并与用其它几种质子酸的反应结果进行了比较．研究结果表明,以HOTf为催化剂时反应效果最好,0．1g1-茚酮在0．5mL HOTf、0．32mL30％H202和2mL2,2,3,3-四氟-1-丙醇（TFP）体系中,恒温60℃反应4h,转化率可以达到86％,产物邻羟基苯丙酸的选择性达98％．可能的反应机理是：1-茚酮先经过Baeyer-Villiger反应生成二氢香豆素,后者进一步水解得到邻羟基苯丙酸．     

缓冲层ZnPc对有机电致发光器件特性的影响

本文研究了酞菁锌(ZnPc)薄膜的表面形貌及ZnPc薄膜作为缓冲层对有机电致发光器件(OLEDs)光电特性的影响.对比两组样品的AFM图像,ZnPc薄膜相比于ITO薄膜,其表面的岛面积较大,薄膜表面更连续平整,基本上覆盖了ITO膜表面针孔,减少了表面的缺陷.另外,ZnPc薄膜的岛分布均匀有序.使用ZnPc作为缓冲层的器件性能明显好于未使用ZnPc修饰的器件,在7.42V的驱动电压下的最大发光亮度达到1.428kcd/m2,在4.3V电压驱动下时,最大光功率效率为1.411m/W;而未使用缓冲层的器件在8V的驱动电压下达到最大发光亮度达到1.212kcd/m2,在5.5V电压驱动下时,最大光功率效率为0.931m/W.