渐变摇摆场拉曼自由电子激光实验

采用渐变摇摆场技术进行了拉曼型自由电子激光实验,获得了最大辐射功率31MW、波长8～10.4mm的微波辐射输出,电子能量转换效率达9.68％。实验表明,对强流低能(0.45MeV)电子束拉曼自由电子激光器,渐变摇摆场比恒定摇摆场的自由电子激光器能量转换效率高2.6倍。     

有优先权的光突发交换中光缓存的性能分析

分析了配置有限数量光纤时延线(FDLs)和优先权机制的光突发交换(pOBS)网络性能,建立了pOBS的网络模型和排队模型;并以模型为基础,比较了各级别数据包的排队等延时与FDLs单位、负荷强度比例的关系;比较了有和无FDLs时,包丢失率与FDLs单位、FDLs深度、系统负荷强度以及波长数的关系.研究发现;高优先级数据包的平均延时远小于其它数据包,负荷强度越大平均延时也越大,高优先级数据包的比例越大则低优先级数据包的延时越大且丢失率越高,加入有限数量和适当深度的FDLs、减小FDLs最小单位、增加波长数都能减小数据包的平均排队延时和丢失率.     

SERS免疫层析技术在快速检测领域的研究进展

免疫层析技术具有快速、成本低廉、操作简便、可视化分析等优势,已广泛应用于食品安全、环境监测及临床诊断等领域。基于颜色深浅进行结果判读的传统免疫层析技术,存在检测灵敏度低、难以实现定量分析等问题。表面增强拉曼散射(SERS)与免疫层析联合的技术提供了一个强大的分析平台,能够实现对分析物的多重、超灵敏及定量检测。本文从检测原理及类型、标签筛选、分析策略设计等方面简述了SERS免疫层析快速检测技术,归纳了其在致病菌、病毒、农兽药残留、真菌毒素等危害物检测方面的最新研究进展,并且对SERS免疫层析技术的研究方向与发展前景进行了分析和展望。     

改性埃洛石材料的制备及其对亚甲基蓝吸附行为的研究

使用硅烷偶联剂KH550改性埃洛石纳米管获得改性材料HNTs-APTS,并对其吸附亚甲基蓝的行为进行研究。利用傅立叶变换红外光谱仪(FTIR)、X-衍射仪(XRD)对改性前后的埃洛石进行表征。考察了吸附时间和温度对吸附过程的影响,并采用Lagrange准二级动力学方程、Langmuir等温线方程及Freundlich等温线方程对实验数据进行拟合。结果表明,KH550成功负载到埃洛石表面;改性后材料的吸附能力大大提高。改性埃洛石对亚甲基蓝的吸附约在60 min达平衡,最大吸附容量为21.66 mg/g。其吸附过程符合准二级动力学方程,热力学较好地符合Langmuir等温线方程,且吸附过程为自发吸热,升高温度有利于吸附的进行。改性材料可重复再生6次,具有良好的再生性能,可在工业处理亚甲基蓝废水中使用。     

纸基显色分析法测定白酒中硫离子的含量*——推荐一个分析化学综合设计性实验

介绍一个由科研成果转化的分析化学综合设计性实验--纸基显色分析法测定白酒中硫离子的含量。硫离子与作为过氧化物模拟酶的四磺基酞菁铁(Fe(Ⅲ)TSPc)在酞菁环平面的轴向位置与中心铁原子配位,能进一步促进过氧链的断裂及高活性中间体高价铁氧正离子自由基的生成,导致3,3′,5,5′-四甲基联苯胺(TMB)氧化产物在纸基上显色加深。利用颜色强度与硫离子含量的关系,可实现对硫离子简单、快速、实时、可靠的检测。本实验综合运用化学、光学、计算机软件等技术,对实验室硬件要求低,易于推广,且实验操作难度适中,内容新颖,综合性强,有利于培养学生实验知识灵活运用的能力。     

Quantitative ultrasound brain imaging with multiscale deconvolutional waveform inversion

High-resolution images of human brain are critical for monitoring the neurological conditions in a portable and safe manner. Sound speed mapping of brain tissues provides unique information for such a purpose. In addition, it is particularly important for building digital human acoustic models, which form a reference for future ultrasound research. Conventional ultrasound modalities can hardly image the human brain at high spatial resolution inside the skull due to the strong impedance contrast between hard tissue and soft tissue. We carry out numerical experiments to demonstrate that the time-domain waveform inversion technique, originating from the geophysics community, is promising to deliver quantitative images of human brains within the skull at a sub-millimeter level by using ultra-sound signals. The successful implementation of such an approach to brain imaging requires the following items: signals of sub-megahertz frequencies transmitting across the inside of skull, an accurate numerical wave equation solver simulating the wave propagation, and well-designed inversion schemes to reconstruct the physical parameters of targeted model based on the optimization theory. Here we propose an innovative modality of multiscale deconvolutional waveform inversion that improves ultrasound imaging resolution, by evaluating the similarity between synthetic data and observed data through using limited length Wiener filter. We implement the proposed approach to iteratively update the parametric models of the human brain. The quantitative imaging method paves the way for building the accurate acoustic brain model to diagnose associated diseases, in a potentially more portable, more dynamic and safer way than magnetic resonance imaging and x-ray computed tomography.     

四配位铂磷光发射体结构与光物理性质关系的理论研究

定量理解光物理过程对于开发新型高效发射极至关重要. 优化提升二价铂配合物磷光量子效率是提升基于金属铂有机发光二极管发光效率的关键. 本文借助密度泛函理论计算, 探讨了一类平面四齿配位二价铂配合物磷光辐射的微观机制, 包括自旋轨道耦合积分、 辐射寿命、 速率常数、 跃迁偶极矩和隙间蹿跃通道. 综合研究发现, 沿着N→Pt方向推电子, 可有效屏蔽非辐射跃迁过程, 从而提升磷光发射效率. 本文将为高效发射器的分子工程学设计提供必要的指导.     

氢氧爆轰波在激波管中的成长机制研究

 针对气相爆轰波成长机制研究,采用压力传感器和高速摄影技术,测试了氢氧混合气体在点火后的火焰波、前驱冲击波以及爆轰波的成长变化过程,计算了冲击波过程参数和气体状态参数,分析了火焰加速机制。实验结果表明,APX-RS型高速摄影系统可用于拍摄气相爆轰波的成长历程;氢氧爆轰波的产生是由于湍流火焰和冲击波的相互正反馈作用,导致反应区内多处发生局部爆炸,爆炸波与冲击波相互耦合,最终成长为定常爆轰波。     

Oxidation of 2,2＇-Dihydroxy-3,3＇-di-tert-buty-5,5＇-dimethoxyl-biphenyl to 3,3＇-Di-tert-butylbiphenyl-2,5,2＇,5＇-diquinone with Copper（Ⅱ）Chloride as Catalyst：Synthesis,Structure and Spectral Properties of Diquinone

Use of free air as oxidant and copper(II)chloride as catalyst,3,3'-di-tert-butylbi-phenyl-2,5,2',5'-diquinone(BBDQ)was prepared via catalytic oxidation of 2,2'-dihydroxy-3,3'-di-tert-butyl-5,5'-dimethoxy-biphenyl(di-BHA).The yield of reaction attained 95% and the selectivity for BBDQ was 100%.The single-crystal X-ray diffraction analysis reveals that the dihedral angle between two rings(benzene rings for di-BHA and quinone rings for BBDQ)changes from 89.8 to 45.3o,indicating the steric hindrance effects of methyl disappear in the oxidation process.The crystal structures of di-BHA and BBDQ are further confirmed by their spectral characterizations.The probable mechanism for this oxidation process is also discussed.