萘在典型介孔碳上的脱附性能研究

本文基于程序升温脱附(TPD)热重实验对典型多环芳烃,萘,在三种典型介孔碳CMK-3、CMK-5和FDU-15以及传统椰壳活性炭(AC)上的脱附性能进行了研究。采用Kissinger方程预估、Coats-Redfern方程求算、主曲线法校验的组合式热分析方法准确获取了萘在四种吸附剂上的脱附动力学三因子(脱附活化能E_a、指前因子lnA与机理函数)。结果表明,CMK-3、CMK-5和FDU-15对萘的脱附再生性能明显优于椰壳AC,脱附峰值温度排序呈:CMK-5CMK-3≈FDU-15椰壳AC。萘在椰壳AC(E_a=101.5 kJ/mol)上的脱附内扩散阻力最大,CMK-3(E_a=67.0 kJ/mol)居其次,二者均为扩散控速。萘在CMK-5(E_a=58.3 kJ/mol)与FDU-15(Ea=46.5 kJ/mol)上的脱附过程均为反应控速,CMK-5由于微孔较多而E_a较高,但较FDU-15具备更为有序的多类型孔道分布,整体上对萘的脱附性能最佳。     

激光诱导荧光快速直接检测土壤中多环芳烃污染物的可行性研究

提出了快速直接对土壤中多环芳烃污染物进行荧光检测的方法——激光诱导荧光光谱技术,以多环芳烃蒽为研究对象,实验验证了激光诱导荧光光谱技术快速检测土壤中蒽污染物的可行性.采用AvaSpec-2048TEC型热电制冷式光纤光谱仪对土壤中的蒽进行直接测量,研究结果表明:当土壤中蒽浓度在一定范围内(0.000 005～0.001...     

多环芳烃在超临界环己烷中的溶解：分子动力学模拟研究

重油中大量存在的多环芳烃会经过缩合反应会形成稠环芳烃,而溶解扩散的限制会导致稠环芳烃之间的聚合从形成残焦,使得对重油的利用率大大降低,所以多环芳烃热解过程的溶解扩散是重油改质的关键因素之一.因此,基于环己烷对烃类良好的溶解性,本文采用分子动力学模拟的方法研究了多环芳烃及其混合物在超临界环己烷中的溶解行为,结果表明在不同温度与密度下超临界环己烷对于具有NAP均具有良好的溶解性,而温度对于Bghip溶解的影响较小.在多环芳烃混合物的油滴溶解过程中,NAP优先溶解到环己烷相中,而Bghip则集中在粒径减小的油滴中.通过计算体系中多环芳烃的径向分配函数与溶剂化自由能发现环己烷与多环芳烃间之间能相互吸引,环己烷在多环芳烃分子周围形成的溶剂壳能抑制多环芳烃分子间的聚合.温度升高以及密度的将降低会导致多环芳烃的内聚能密度降低,增加了多环芳烃与超临界环己烷之间的相互作用.环己烷密度越小以及温度的升高可以促进多环芳烃或多环芳烃混合物在超临界环己烷中的溶解.     

紫外脉冲激光作用下土壤中多环芳烃的分解与荧光发射特性（英文）

多环芳烃是具有致突变、致癌和致畸作用的一类持久性有机污染物,广泛分布在大气、水、土壤等不同环境介质中。多环芳烃一旦进入土壤便会长期存留于其中,土壤成为环境中多环芳烃的重要储藏库和最终归宿。土壤中的多环芳烃可以通过多种途径进入人体,对人类健康造成威胁。因此,对土壤中多环芳烃的监测十分必要。当前,传统的土壤多环芳烃检测方法过程繁琐、费时,不利于污染场地多环芳烃的大范围快速检测,而基于激光诱导荧光光谱技术的土壤多环芳烃检测法能够快速识别、检测土壤中的有机污染物。多环芳烃类物质具有易挥发,可被紫外光降解等特性,实验中紫外激光能量的选择至关重要,本文利用实验室搭建的266 nm激光诱导荧光系统,以蒽、芘、菲为研究对象,探究不同激光能量下多环芳烃分解和荧光光谱的变化特性。结果表明,当激光的能量密度变化时,荧光中心峰位置未发生偏移,但蒽、芘、菲三种多环芳烃荧光峰处最大强度的相对标准偏差随激光能量密度的下降呈现出先下降后上升的趋势:当能量密度为8.54 mJ·cm~(-2)时,三种物质在10次光谱测量结果的相对标准偏差均为最大,蒽、芘、菲三种物质的荧光峰强度相对标准偏差分别在1.72, 1.00和1.47 mJ·cm~(-2)的能量密度下达到最小值;蒽、芘、菲在100 s时,分解率分别达到59.3%, 69.8%和63.6%,在较高的能量下,蒽、芘、菲三种物质发生了较快的分解,芘相比于其他两种多环芳烃类物质更易发生光降解和热分解等作用,荧光峰强度相对标准偏差也高于蒽与菲;蒽在激光能量密度为1.72 mJ·cm~(-2)时, 10 s时的分解率已经接近于0, 100 s时分解率仅为12.8%,荧光峰强度相对标准偏差达到最低,当激光能量密度降至0.88 mJ·cm~(-2)时,蒽在100 s内的分解几乎可以忽略不计;对于芘而言,当激光能量密度降至1.00 mJ·cm~(-2)以下时,分解作用基本趋于一致, 100 s时分解率在47.3%～47.4%;而对于菲而言,当激光的能量密度低于1.47 mJ·cm~(-2)后,分解率不再随激光能量密度的降低而明显下降,在100 s时的分解率在36.8%～38.6%;在低能量密度土壤中芘与菲下仍发生分解作用。     

土壤湿度对多环芳烃荧光特性的影响

荧光光谱技术已被用于检测土壤中多环芳烃。但土壤湿度对多环芳烃的荧光强度产生很强的干扰,这对于荧光光谱技术的土壤多环芳烃快速实时检测技术的发展无疑是一种挑战。为了研究土壤湿度对多环芳烃荧光特性的影响,分别配置了八个不同湿度(含水量5%～40%,间隔5%)的菲土壤样品。采用美国PE公司的LS-55荧光分光光度计对不同湿度含量的菲土壤样品进行了检测,得到不同湿度含量下的一维动态荧光谱,以土壤湿度为外扰,研究了其二维相关荧光光谱特性,发现菲土在386,408和432 nm处荧光强度随着土壤中湿度的增大而增强,而333 nm处瑞利散射光强度却在减小,提出通过建立菲荧光强度、瑞利散射光强度与土壤湿度之间的关系,有可能实现土壤湿度对菲荧光强度影响的校正。同时,也研究了土壤湿度对定量分析菲浓度标准曲线的影响,指出土壤湿度极大影响着精准定量分析菲浓度标准曲线的建立。     

煤中氯对多环芳烃生成的影响研究

本文在管式炉上研究了煤中氯对多环芳烃生成的影响,测定了煤中氯含量不同时多环芳烃生成量的变化,并分析了在不同气氛下不同含氯量的煤燃烧时多环芳烃与二(?)英生成的相互关系.实验结果表明,在空气中燃烧及氮气气氛热解条件下,随着氯含量的增加,多环芳烃呈减少趋势;氯代反应是导致多环芳烃生成量减少的一个主要原因.     

加速溶剂萃取凝胶色谱净化气相色谱-质谱联用测定土壤中多环芳烃

土壤样品经过加速溶剂萃取仪与凝胶色谱净化浓缩提纯处理后,用气相色谱-质谱联用仪测定土壤中多环芳烃。     

煤燃烧过程中铜对多环芳烃生成的影响

研究了两种燃烧方式煤燃烧过程中金属铜的添加对多环芳烃生成的影响。结果表明:随着铜煤质量比的增加,管式炉煤燃烧多环芳烃生成浓度是减少的;流化床煤燃烧多环芳烃生成浓度是增加的,但要小于管式炉条件下两个数量级。多环芳烃生成毒性分布类似于多环芳烃生成浓度分布。而单个多环芳烃生成有着较大区别,同燃烧方式、存在状态、铜的含量等有较大关系。在燃烧温度下,铜的添加主要对高环物质的催化作用较为明显。     

普通咖啡机也能用于复杂化学分析

正化学分析经常需要大量时间和贵重设备,更不要说那些刺激性的溶剂了。但是现在咖啡机就可以轻松完成这些分析。研究者利用现成的台式咖啡机,快速而廉价地从污染土壤样本中提取称为多环芳烃(polycyclic aromatic hydrocarbons,PAHs)的致癌污染物。首先,他们将装有5克多环芳烃污染土壤的胶囊放入咖啡机。然后不是用水,而是将50毫升的水和乙腈溶剂(图中瓶内液体)的混合物在正常温度和压力下灌入土壤样本,这一过程用了11秒,而一些其他方法则需要30分钟甚至更长时间。最后,他们     

菲及腐殖酸混合液荧光法定量分析研究

多环芳烃作为普遍关注的优先监测污染物,在水环境中其含量很低,易受共存物腐殖酸的干扰。由于多环芳烃与腐殖酸的光谱重叠严重,很难用常规方法快速的定量检测。菲(PHE)作为多环芳烃中的模式化合物,对菲和腐殖酸(HA)的荧光光谱特性进行了研究,分析了腐殖酸共存下对菲定量检测的影响。采用平行因子算法分析混合液的三维荧光光谱,在激发波长为240～360 nm(5 nm为间隔)、发射波长为 260～575 nm(5 nm为间隔)下对该体系进行了分辨研究,并对菲和腐殖酸进行荧光光谱测量。实验结果表明,此方法可用于有干扰共存下多环芳烃化合物的直接快速定量检测。     

An empirical correlation between spray dispersion and spray tip penetration from an edge detection of visualized images under the flow condition of a solid body rotating swirl

In this study, spray tip penetration and dispersion in high-pressure environment were simulated experimentally with an emphasis on the swirl effect. A rotating constant volume chamber was designed in order to generate a swirl that could be varied continuously with a flow field that closely resembled the solid-body rotation. An emulsified fuel was injected into the chamber and the developing process of fuel spray was observed. The effect of swirl on the spray dispersion was analyzed by measuring the dispersion area as a function of the spray tip penetration and the time after the start of the injection. The effect of swirl on the spray dispersion was quantified through getting a relationship between the swirl and the dispersion. The experimental results of the spray dispersion with time after the fuel injection process began showed similar characteristics to those of the spray tip penetration with time after the start of the fuel injection. The spray dispersion characteristics while varying the spray tip penetration were also investigated. The results showed that the spray dispersion depends linearly on the spray tip penetration, when it is small. As the spray tip penetrates into longer distance, the dispersion depends on the spray tip penetration to the power of 1.6.     

FAE装置参数对燃料抛撒与爆炸威力影响的实验研究

 采用高速运动分析系统对FAE实验装置爆炸抛撒过程进行观测,描述了燃料抛撒过程的不同阶段,实验研究了比药量、长径比、壳体材质等装置参数对燃料抛撒与爆炸威力的影响。结果表明,燃料抛撒过程可分为射流形成与扩散运动阶段、燃料两向膨胀运动阶段和气液融合运动阶段。不同阶段对应不同的流体动力学特征,对云团形成的贡献不同。在实验装置总体优化条件下,适当增大比药量可提高云团覆盖面积与体积;在实验范围内长径比不是影响云团状态的显著因素,但长径比较大时可使燃料抛撒均匀性更好;采用钢质壳体时云雾抛撒状态明显优于铝质壳体。实验证明,采用碳钢壳体、比药量3%左右、长径比为3~5且装置参数良好匹配时,可获得理想的云团状态和高威力爆炸波毁伤效应。     

Analysis of broadband third harmonic generation with non-collinear angular dispersion in KDP crystals

A new scheme with non-collinear sum frequency generation (SFG) process of broadband third harmonic generation (THG) with two KDP crystals (one doubler and one mixer) using angular dispersion was proposed. The principle of broadband harmonic generation with non-collinear angular dispersion was presented. The comparison between the schemes of non-collinear and collinear SFG process was performed. The effects of the angular dispersion on the conversion efficiency, the pulse shape and the spectrum of the third harmonic field were discussed. The results show that, if proper angular dispersion is added to the fundamental and the second harmonic field outside the mixing KDP crystal, respectively, the broadband third harmonic conversion efficiency can be improved significantly. However, the difficulty of this scheme arises due to the requirement of two gratings with different angular dispersion outside the mixer. With the new scheme, it can be simpler that only one grating is needed to realize the broadband phase matching in the non-collinear SFG process. Although the fundamental and the second harmonic field inside the mixing crystal are non-collinear except the center wavelength, a blazing grating with proper angular dispersion for the fundamental field (twice as that for second harmonic field) can yield the well compensation for phase mismatching in the SFG process. Consequently, the conversion efficiency and the characteristics of the third harmonic field for the broadband third harmonic generation can be improved significantly.     

超高速发射实验模型的数值计算

 采用三阶精度PPM（Parabolic Piecewise Method）方法和VOF（Volume of Fluid）相结合,运用Lagrange-Remapping算法,编制了多介质流体高精度欧拉计算程序MFPPM,可以对多介质复杂流场进行数值计算。对程序计算精度进行了测试,并应用于超高速发射实验模型数值计算,对Sandia实验室不带会聚作用的实验模型进行了一维计算以及带会聚作用的实验模型进行二维计算并与其实验结果和CTH计算结果进行对比,其中一维计算最大相对误差1%,二维计算相对误差4.7%,在此基础上对超高速发射设计模型进行了初步计算。     

Real‐time monitoring of active ingredient dispersion in a pharmaceutical aqueous suspension using Raman spectroscopy

In a typical aqueous nasal suspension manufacturing process, the homogeneity of the active pharmaceutical ingredient (API) dispersion in a premix vessel is determined merely by visual observation. In this study, to better demonstrate in‐process control, Raman spectroscopy was developed as a process analytical tool (PAT) to monitor the real‐time API dispersion homogeneity in the active premix process. The end‐point variations of the API dispersion as a function of the surfactant type, surfactant concentration, and agitation speed were evaluated by dispersive Raman spectroscopy in combination with multivariate analysis for both lab‐scale and pilot‐scale batches. The optimal surfactant concentration and type were determined to be 0.2% surfactant A for the active dispersion based on a quantitative end‐point comparison. In addition, a chemometric model was developed successfully for the real‐time prediction of API concentration in the active premix, with a root mean squared error of prediction (RMSEP) of 5.4%. In conclusion, Raman spectroscopy has proven to be a viable PAT tool to qualitatively and quantitatively assess the active premix homogeneity in an aqueous nasal suspension manufacturing process. In the future, this method can potentially be used in the commercial manufacturing process for in‐process control of the dispersion homogeneity of the suspension. Copyright © 2011 John Wiley & Sons, Ltd.     

Study on the Mechanism of the Formation and Evolution of Phase Structure in PP/PcBR Blends

Phase dispersion theory was proposed to study the dynamic process of polymer blending with the help of mineral processing theory. Two constants, dispersion coefficient n and process coefficient b, were calculated for the early dispersion stage to describe the varying velocity of the dispersed phase dimension. In this dispersion theory, the phase dimension of binary blends of polypropylene with poly(cis‐butadiene) rubber linearly increased with blending time in the early stage on a double logarithmic scale, which suggested that phase dispersion theory was applicable to the study of polymer blending dynamics. In this study, the influence of the processing conditions, that is, composition, temperature, and shear rate, on the two constants of n and b was also studied. The results showed that n and b decreased with increasing dispersed phase, and reached a minimum when the shear rate was 60 rpm. The dispersion coefficient n first decreased with increasing temperature, reached a minimum when the temperature was 200°C, and then increased with a further increase in temperature, but there was no apparent influence of temperature on the process coefficient b. The coinfluence of blending temperature and shear rate on the dispersion coefficient n showed that the smaller the content of the dispersed phase, the more sensitive the decreasing rate of phase dimension was to the temperature and shear rate.     

Ultrasonic dispersion of inorganic nanoparticles in epoxy resin

The incorporation of nanoscale fillers into a polymer can lead to a considerable improvement of mechanical properties, i.e. stiffness and toughness of a material can be enhanced simultaneously by the insertion of nanofillers. Thereby, the crucial difference between conventional microscale fillers and nanofillers is the high specific surface of the latter. In order that this surface can interact with the matrix material a good dispersion, i.e. a good separation and a homogeneous distribution of the nanoparticles into the polymer, is required. In the present study ultrasonic waves generated by an ultrasonic horn were used to disperse titanium dioxide nanoparticles into epoxy resin. The process parameters, e.g. the ultrasonic amplitude, the dispersion time and the material’s volume, were varied systematically with the aim of achieving an optimum dispersion process. A dispersion model for bead mills was adapted to the ultrasonic process and compared to a second dispersion model in order to find an adequate mathematical expression to correlate the ultrasonic process parameters to the particle sizes in the material and to allow predictions for further experiments.     

剩余三阶色散对相位共轭偏振孤子的影响及其补偿

光学相位共轭中剩余三阶色散不利于共轭孤子的稳定传输,导致孤子脉冲具有更大的时间抖动.本文提出在传输线末采用具有正三阶色散的色散位移光纤补偿光学相位共轭中的剩余正三阶色散.数值结果证明了其可行性.同时也分析其补偿的物理机制.     

Short-term reversible changes in the dielectric dispersion of a barium titanate single crystal

An effect of spontaneous fluctuation of the dispersion frequency was detected during investigations of the dielectric dispersion of a BaTiO₃ single crystal while measuring under the electric field only. A decrease in the dispersion frequency by three orders of magnitude and its subsequent return to the previous value was observed. A possible mechanism of this phenomenon is suggested, which involves the dynamics of the screening process.     

金属互连电迁移噪声的相关维数研究

针对金属铝互连中噪声信号随电迁移过程变化规律及其所反映的内部失效机理问题，提出将相关维数用于对电迁移噪声时间序列的分析.通过对互连电迁移噪声实验数据的相关维数计算，发现随着电迁移的进行，金属铝互连噪声由随机性成分占主导变为确定性成分占主导，反映出噪声由随机信号转变为混沌动力学信号.应用散射理论解释上述现象，在金属互连电迁移中，空位扩散阶段噪声主要产生机制是空位随机散射；在空位聚集到空洞成核这一过程中，噪声产生机制逐渐从随机散射转变到弹道混沌腔输运机制为主.通过与传统表征参量的对比，证明相关维数可用于预测金 关键词： 电迁移 噪声 相关维数 混沌