WDM系统中ASE噪声的二阶色散效应

讨论了采用小信号分析法研究脉冲波在色散、非线性光纤中的传输时,放大的自发辐射(ASE)噪声作为功率调制项加入脉冲波的传输方程后所产生的效应.ASE噪声不仅被互相位调制不稳定增益所放大,还受二阶色散成分的影响.其传输函数为COS(1/2β2dzω2),这一函数不能通过色散补偿来消除,会削弱ASE噪声的影响.鉴于此,ASE...     

Solvent-vapour treatment induced performance enhancement of amplified spontaneous emission based on poly[2-methoxy-5-(2’-ethyl-hexyloxy)-1,4-phenylene vinylene]

In this work,performance enhancements of amplified spontaneous emission(ASE) from poly[2-methoxy-5-(2éthyl-hexyloxy)-1,4-phenylene vinylene](MEH-PPV) have been achieved via solvent vapour treatment.Correlations between the morphology of the film and the optical performance of polymer-based ASE are investigated.The active layers are characterised by atomic force microscopy and optical absorption.The results show that the solvent-vapour treatment can induce the MEH-PPV self-organisation into an ordered structure with a smooth surface,leading to enhanced optical gain.Thus the solvent-vapour treatment is a good method for improving the optical properties of the MEH-PPV.     

A novel hybrid mode of sample injection to enhance CZE sensitivity for simultaneous determination of a pyridine-triphenylborane anti-fouling agent and its degradation products

We developed a novel hybrid sample injection mode (HSIM) that presents the combination of electrokinetic injection and vacuum injection to enhance detection sensitivity in CZE. Samples were introduced using both vacuum and electrokinetic injections simultaneously, with a water plug injected into the capillary prior to sample introduction (i.e. similarly to field-amplified sample injection, FASI). Using a sample mixture containing an anti-fouling agent applied to ship hulls, pyridine-triphenylborane and its degradation products (diphenylborinic acid, phenylboronic acid, and phenol) dissolved in ACN, the length of water plug, time, and voltage for sample introduction were optimized. The signal intensity (peak height) was found to be up to a 30-fold increased using HSIM by applying 4 kV for 4 s at the inlet end of the capillary as the cathode with supplementary vacuum in comparison with only vacuum injection for 4 s. The LODs (at a S/N of 3) for pyridine-triphenylborane, diphenylborinic acid, phenylboronic acid, and phenol were 0.88, 1.0, 21, and 23 μg/L, respectively. At the level of 0.04 mg/L, the RSDs (n=4, intra-day) for the above analytes were in the ranges of 1.9-11, 4.3-9.2, and 0.34-0.66% for peak area, peak height, and migration time, respectively. The HSIM is a simple and promising procedure useful for enhancing the sensitivity for both low-and high-mobility ions in CZE.     

微乳液毛细管电动色谱-场放大富集法灵敏分析尿液中的9种麻醉剂类药物

建立了一种微乳液毛细管电动色谱(MEEKC)-场放大富集(FASI)分析尿液中多种麻醉剂(吗啡、可待因、纳洛酮、海洛因、蒂巴因、可卡因、哌替啶、芬太尼、美沙酮)的方法。考察了微乳液组成、分离电压等因素的影响,得到的最佳微乳液组成(质量分数)为0.6%十二烷基硫酸钠、1.2%正丁醇、0.6%乙酸乙酯和97.6% 10 mmol/L硼砂缓冲液(pH 9.5);分离电压为25 kV。在上述微乳体系中,9种化合物在15 min内得到了基线分离。采用场放大在线富集技术提高了分析灵敏度,检出限(S/N=3)低至0.3 μg/L。模拟尿样样品中9种麻醉剂的加标回收率介于79.4%～119.9%之间,日内相对标准偏差小于5.5%。将该方法应用于美沙酮大鼠体外代谢样品的测定,结果令人满意。     

Genetic Diversity Caused by Environmental Stress in Natural Populations of Niupidujuan as Revealed by RAPD Technique

Multiplex environmental factors are generally expected to have significant effects on genetic diversity of plant populations.In this study,randomly amplified polymorphic DNA(RAPD) technique was used to reveal the genetic diversity in the same species of four populations collected from Niupidujuan(Rhododendron chrysanthum) at different altitudes,an endangered species,endemic to Northeast China.Initially,twenty informative and reproducible primers were chosen for final RAPD analysis.A total of 152 clear bands...     

分子构型对有机半导体分子TPD,DDB和NPB激射性能的影响

N,N′-二苯基-N,N′-二（3-甲苯基）-1,1′-联苯-4,4′-二胺（TPD）分子已证明能够在掺杂和非掺杂平面波导结构中产生受激发射,然而对于该分子激射特性的机理却很模糊.为了得到其激射特性的微观解释,我们通过实验和量化理论研究TPD分子的吸收、光致发光、受激发射以及与TPD分子结构类似的两个分子：1,4-二（二苯胺基）联苯（DDB）和N,N′-二苯基-N,N′-二（1-萘基）-1,1′-联苯-4,4′-二胺（NPB）.我们发现,DDB分子具有与TPD分子相似的自发辐射放大（ASE）特性,然而NPB分子却没有ASE特性,尽管其斯托克斯位移较大,约0.754eV.量子化学计算分析中,我们利用密度泛函理论（DFT）和弗朗克-康登（Franck-Condon）原理研究分子在电子基态和激发态的分子构型以及电子基态的振动能级.理论分析表明,对于TPD和DDB分子,一些苯环中的较强高频拉伸模式（1199～1664cm-1）对PL谱中的第一振动带（0-1跃迁）有显著贡献,该振动带有利于形成激光的四能级系统.而对于NPB分子,相对大的萘基基团取代了TPD和DDB分子外围的甲基与苯环,会产生一些较强的分子低频振动模式（11～689cm-1）,这些低频振动模式则会破坏激光四能级系统.研究结果有助于深刻理解有机分子的激射特性,为新型激射材料的设计和应用提供了理论基础.     

Pump pulse characteristics of quasi-continuous-wave diode-side-pumped Nd:YAG laser

The influence of pumping laser pulse on the property of quasi-continuous-wave (QCW) diode-side-pumped Nd:YAG laser is investigated theoretically and experimentally. Under remaining a fixed duty cycle, the average output power increases, and the corresponding thermal focal length shorten with the increase of the pump pulse duration, which attributes to the decrease of the ratio of pulse buildup time to the pulse duration. At a pump power of 146 W, the laser output power changes from 65.1 W to 81.2 W when the pulse duration is adjusted from 150 μ s to 1000 μ s, confirming a significant enhancement of 24.7%. A laser rate equation model incorporating the amplified spontaneous emission is also utilized and numerically solved, and the simulated results agree well with the experimental data.     

Improvement in the sensitivity of microfluidic ELISA through field amplified stacking of the enzyme reaction product

In this article, we demonstrate a novel approach to enhancing the sensitivity of enzyme-linked immunosorbent assays (ELISA) through pre-concentration of the enzyme reaction product (resorufin/4-methylumbelliferone) in free solution. The reported pre-concentration was accomplished by transporting the resorufin/4-methylumbelliferone molecules produced in the ELISA process towards a high ionic-strength buffer stream in a microfluidic channel while applying a voltage drop across this merging region. A sharp change in the electric field around the junction of the two liquid streams was observed to abruptly slow down the negatively charged resorufin/4-methylumbelliferone species leading to the reported pre-concentration effect based on the field amplified stacking (FAS) technique. It has been shown that the resulting enhancement in the detectability of the enzyme reaction product significantly improves the signal-to-noise ratio in the system thereby reducing the smallest detectable analyte concentration in the ELISA method. Applying the above-described approach, we were able to detect mouse anti-BSA and human TNF-α at concentrations nearly 60-fold smaller than that possible on commercial microwell plates. For the human TNF-α sample, this improvement in assay sensitivity corresponded to a limit of detection (LOD) of 0.102 pg mL⁻¹ using the FAS based microfluidic ELISA method as compared to 7.03 pg mL⁻¹ obtained with the traditional microwell plate based approach. Moreover, because our ELISAs were performed in micrometer sized channels, they required sample volumes about two orders of magnitude smaller than that consumed in the latter case (1 μL versus 100 μL).     

Analyte zone sharpening in pressurized capillary electrochromatography based on electrophoretic migration under a heterogeneous field

Significant peak width reductions, or peak height enhancements, of angiotensins were observed when a high voltage was applied to hydrophilic interaction pressurized capillary electrochromatography using gradient elution with mobile phases containing perchloric acid. The investigation using a contactless conductivity detector revealed that perchloric acid was adsorbed on the surface of the stationary phase, when the acetonitrile content in the mobile phase was high, and released from the stationary phase by increasing the water content during a gradient procedure. The released perchloric acid formed a highly concentrated zone moving from the column inlet to the outlet. The electrochromatographic behavior of the analytes, primarily electrophoretic migration, was changed in this zone. As a consequence of the significant variation in migration velocity of the analytes, the sample band width was reduced similar fashion to on‐capillary concentration in capillary electrophoresis. Using this result, the reduction of band width and enhancement in separation efficiency was demonstrated in reversed‐phase pressurized electrochromatography, in which the conductivity of the mobile phase was significantly altered using a step gradient. The resolution between benzoic acid and 1‐naphthalene sulfonic acid was successfully improved from 2.7 to 4.3 by using the band width reduction method based on field‐amplified stacking.     

Chemically Amplified Resist Based on Dendritic Molecular Glass for Electron Beam Lithography

A novel dendritic molecular glass(MG) containing adamantane core(AD-15) was synthesized and characterized. It exhibits good solubility in common organic solvents and a stable amorphous state at room temperature, which contributes to forming films with different thicknesses by spin-coating. The thermal analysis of AD-15 indicates that no apparent glass transition temperature(T_g) is observed before the thermal decomposition temperature(T_d=160 ℃). The good thermal resistance suggests that it can satisfy the lithographic process and is a candidate for photoresist materials. The patterning properties of AD-15 resist were evaluated by electron beam lithography(EBL). By optimizing the lithographic process parameters, AD-15 resist can achieve 40 nm half-pitch patterns with a line-edge roughness of 4.0 nm. The contrast and sensitivity of AD-15 resist were 1.9 and 67 μC/cm², respectively. Compared with the commercial PMMA(950k) electron beam resist, the sensitivity of AD-15 resist increases by 6 times. This study provides a new example of molecular glass resist with high resolution and sensitivity for EBL.