On the averaged quantum dynamics by white-noise hamiltonians with and without dissipation

Exact results are derived on the averaged dynamics of a class of random quantum-dynamical systems in continuous space. Each member of the class is characterized by a Hamiltonian which is the sum of two parts. While one part is deterministic, time-independent and quadratic, the Weyl-Wigner symbol of the other part is a homogeneous Gaussian random field which is delta correlated in time, but smoothly correlated in position and momentum. The averaged dynamics of the resulting white-noise system is shown to be a monotone mixing increasing quantum-dynamical semigroup. Its generator is computed explicitly. Typically, in the course of time the mean energy of such a system grows linearly to infinity. In the second part of the paper an extended model is studied, which, in addition, accounts for dissipation by coupling the white-noise system linearly to a quantum-mechanical harmonic heat bath. It is demonstrated that, under suitable assumptions on the spectral density of the heat bath, the mean energy then saturates for long times.     

New poly(p‐phenylene vinylene) derivatives with two oxadiazole rings per repeat unit: Synthesis,photophysical properties,electroluminescence, and metal ion recognition

Two new poly(p‐phenylene vinylene) derivatives OX1‐PPV and OX2‐PPV bearing two 1,3,4‐oxadiazole rings per repeat unit and a fully conjugated backbone with solubilizing dodecyloxy side groups were synthesized and investigated. The amorphous conjugated polymers had glass‐transition temperature values of 60–75 °C and emitted intense blue or greenish‐blue light in solution with photoluminescence (PL) emission maxima at 379–492 nm and PL quantum yields of 0.41–0.52. In the solid state they emitted yellowish‐green light with PL emission maxima at 533–555 nm. Cyclic voltammetry showed that both conjugated polymers had reversible reduction and irreversible oxidation, making them n‐type materials. The electron affinity of OX2‐PPV was estimated as 2.85 eV whereas that of OX1‐PPV was 2.75 eV. Yellow electroluminescence (EL) was achieved from single‐layer light‐emitting diodes of OX2‐PPV with an EL emission maximum at 555 nm and a brightness of 70 cd/m². Polymer OX2‐PPV, which was functionalized with 2,6‐bis(1,3,4‐oxadiazole‐2‐yl)pyridine, demonstrated sensitivity to various metal ions as a fluorescence‐mode chemosensor. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2112–2123, 2004     

LED铁路旅客引导系统的分析与设计

LED旅客引导系统,采用一台微机控制多台单片机的类网络控制结构,具有灵活的控制方式;采用LED显示,满足了显示的直观性、美观性、灵活性及耐久性。控制软件还提供了良好的用户界面,使得操作人员操作简单、灵活,便于掌握.     

A stability property of the stochastic heat equation

In this paper we consider continuity properties of a stochastic heat equation of the form ∂u(t,x)/∂t = ∂²u(t,x)/∂x² + f(u(t,x))W_x,t. We prove that the solutions of this equation depend continuously on the function f and give some new estimates for this connection.     

1.315 μm波长附近实际大气高分辨率吸收光谱

 用窄线宽、脉冲可调谐光参量振荡器（OPO）作光源，使用光程长达1 097m的怀特池，采用单探测器分时复用的探测方法，首次在吸收池中精确测量了实际大气中1.315 μm波长附近高分辨率吸收光谱，实验验证了实际大气中水汽是该波段的主要吸收气体；得到了实际大气中吸收分子在氧碘激光波长（7 603.14cm^-11）处的吸收截面为 (1.05±0.09)×10^-24 cm²(标准大气条件下）以及在该波段主要吸收谱线的参数，包括吸收线的位置、线强度、压力加宽半宽度等。利用实测的线参数计算了在氧碘激光波长附近大气分子的吸收截面，发现吸收最小的波长分别位于7 603.31和7 603.93cm^-1，其值约为(8.9±0.8)×10^-25 cm²，比氧碘激光波长处的吸收截面约小15%。     

白光发光二极管的制备技术及主要特性

利用发射波长为470nm的蓝光发光二极管作为基础光源，通过荧光粉转换方法制备白光发光二极管，荧光粉主要采用稀土激活的铝酸盐Y3Al5Ol2：Ce3 (YAG)。在工作电流为15mA条件下，所研制的白光LED的法向光强为2890mcd；色坐标为x=0.29，y=0．33；显色指数为77；流明效率为14．9lm／w。研究制备了不同色温的白光LED，色温范围从2700～8000K，研究了色温与色坐标之间的对应关系。并且与国外同类产品进行比较。部分指标已经超过了国外同类产品水平。     

Optical and electrochemical properties of copoly(aryl ether)s consisting of alternate 2,5‐distyrylbenzene and electron‐transporting oxadiazole or triazole derivatives

New copoly(aryl ether) P1 consisting of alternate electron‐transporting 2‐(3‐(trifluoromethyl)phenyl)‐5‐(4‐(5‐(3‐(trifluoromethyl)phenyl)‐1,3,4‐oxadiazol‐2‐yl)‐2,5‐bis(hexyloxy)phenyl)‐1,3,4‐oxadiazole and hole‐transporting 2,5‐distyrylbenzene (DSB) was synthesized via nucleophilic substitution polymerization. We investigated the optical and electrochemical properties of alternate copoly(aryl ether)s P1 – P6 , which contain the same hole‐transporting DSB segments, but with different electron transporting segments. The effect of trifluoromethyl groups in electron transporting segments is also discussed. Referencing to the spectra of their model compounds M1 – M4 , the emissions of P1 – P3 are dominated exclusively by the hole‐transporting fluorophores with longer emissive wavelength about 452–453 nm via efficient excitation energy transfer. Furthermore, P1 – P3 also exhibit unique variations in energy transfer in acidic media and solvatochromism in organic solvents. The highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels of P1 – P4 , estimated from electrochemical data, are ?5.12, ?5.15, ?5.18, ?5.00 eV and ?2.93, ?3.39, ?3.49, ?2.76 eV, respectively. The electron and hole affinity of P1 – P6 can be enhanced simultaneously by introducing isolated hole‐ and electron‐transporting segments in backbone. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5083–5096, 2005     

金属有机化学气相沉积外延技术生长GaN基半导体发光二极管和激光二极管(Ⅰ)

文章评论性地介绍了金属有机化学气相外延技术（MOCVD）生长氮化物半导体GaN和InGaN以及激子局域化效应、量子束缚斯塔克效应对它们的光学性能的影响，详细比较了这两种效应对GaN基半导体发光二极管和激光二极管特性的影响，特别是量子束缚斯塔克效应以显著不同的方式影响着发光二极管和激光二极管的性能；文章还讨论了在A面蓝宝石衬底上生长GaN的情况．     

Analytical devices based on light-emitting diodes – a review of the state-of-the-art

A general overview of the development of the uses of light-emitting diodes in analytical instrumentation is given. Fundamental aspects of light-emitting diodes, as far as relevant for this usage, are covered in the first part. The measurement of light intensity is also discussed, as this is an essential part of any device based on light-emitting diodes as well. In the second part, applications are discussed, which cover liquid and gas-phase absorbance measurements, flow-through detectors for chromatography and capillary electrophoresis, sensors, as well as some less often reported methods such as photoacoustic spectroscopy.     

基于愈创木酚荧光减量准确测定过氧化物酶活性的新方法

利用H2O2/过氧化物酶(POD)/愈创木酚(GA)反应体系的产物(470 nm)吸光度去定量POD活性是目前常用方法之一,但产物不稳定且对比色皿有吸附现象是该反应的主要缺点之一。为了解决此问题,本研究利用GA的荧光特性建立了一种能准确测定POD活性的方法。用辣根过氧化物酶( HRP)作为测试样品得到了以下优化条件：0.5 mmol/L GA,0.5 mmol/L H2O2,0.05 mol/L PBS缓冲液(pH 6.0),反应温度20℃,样品耗量20μL;本方法的线性范围为500~60000 U/L(r=0.9993),RSD≤2.4%(n=11),检出限为385 U/L。在优化条件下,用白萝卜提取液作为测试样品,用本方法((9714依132) U/L)与比色法((9926依352) U/L)和循环催化流动分析法((9608依456) U/L)进行了对比,结果表明,3种方法相互一致性很好。