Photoinitiated Free Radical Polymerization Using Benzoxazines as Hydrogen Donors

Summary: Free radical polymerization of methyl methacrylate (MMA) is initiated upon irradiation at λ > 350 nm in CH₂Cl₂ that contains benzoxazine (P‐a) and one of the following photosensitizers: benzophenone (BP), thioxanthone (TX), 2‐chlorothioxanthone (CTX), 2‐isopropyl thioxanthone (ITX), and camphorquinone (CQ). The postulated mechanism is based on the intermolecular reaction of the excited photosensitizer with the tertiary amino moiety of the ground state P‐a and a subsequent hydrogen abstraction reaction. The resulting aminoalkyl radicals initiate the polymerization. The incorporation of P‐a groups into polymers is demonstrated by spectroscopic methods. The possibility of deep curing using the described photoinitiating system followed by the thermal ring opening of the incorporated P‐a groups is also demonstrated.

Schematic of the photoinitiated free radical polymerization using benzoxazines as hydrogen donors.     

Difluoroalkylamines from high temperature vapor phase reactions of nitrogen trifluoride with alkanes, ethers and benzene

At temperatures around 400 °C, nitrogen trifluoride (NF₃) readily reacts with alkanes and benzene as well as ethers. In all cases, products were N,N-difluoroamines. This is in contrast to difluoroamination of benzylic substrates where the initial N,N-difluoroamines underwent eliminations or rearrangements and were not isolated. Cyclic and acyclic alkanes generated N,N-difluoroaminoalkanes. Benzene substituted on the ring to form N,N-difluoroaniline. Ethers reacted to generate α-N,N-difluoroamino ethers. Little direct fluorination was observed.     

多孔氧化铝薄膜的纳米结构和光谱特性研究

利用阳极氧化的方法制备出几种表面结构和尺度不同的多孔氧化铝薄膜,用原子力显微镜扫描获得了这些薄膜表面的纳米结构图像,并采用光谱仪测定了它们的反射光谱。实验表明,平均孔径为26和39 nm的多孔氧化铝薄膜表面具有独特的反射光谱,在500至1 000 nm波长范围内呈周期性地密集峰—谷分布,峰—谷的密集度或数量取决于薄膜表面纳米结构的尺度。讨论了纳米结构尺度与反射光谱之间的相互关系,并给出了适当的解释。     

两种反射膜系的激光热力损伤特性

 在驻波场理论基础上,用表面和界面强吸收理论模型,计算出了激光辐照下两种不同反射膜系中温度场的“多峰”分布特性,分析了激光对薄膜的热力损伤特性、主要破坏模式和阈值条件。结果表明,光学薄膜对激光能量的吸收,主要由驻波场分布及膜层的消光系数决定;膜系表面的杂质吸附层和界面吸收层是膜系的主要能量沉积区,从而在这些界面形成温度场的“多峰”分布,界面因此成为最容易受激光损伤的部分。导致光学薄膜激光损伤的主要模式为膜层熔融和脱落两种。如果膜层中含有杂质,则容易诱导杂质处膜层剥落破坏。     

Feature tracking for projection registration in laboratory-scale reflective tomography laser radar imaging

In range-resolved reflective tomography laser radar imaging system, for accurate image reconstruction, all projections must be aligned to the center of target rotation. Due to the unknown location of the axis of rotation and random target translation, the center of target rotation in each projection cannot be measured accurately and images reconstructed based on range-resolved projections without registration would be dislocated. Here, we apply a feature tracking method to align projections data for tomographic reconstruction in laboratory-scale laser radar imaging. The target was placed on a spin table with an unknown and fixed axis, and the oscillatory motion of the target translation was simulated by a second order inertia filter to accord with the real satellites vibrations. The experimental simulation results demonstrate the effectiveness of this method to improve images reconstruction equality. The application of this method to actual radar imaging in remote distance was discussed and the differences were compared with the lab setups.     

近红外传感器在汽车改造技术中的应用研究

利用反射式近红外传感器及语音录放组件,研究了汽车倒车防撞语音提示器。当汽车倒车时,只要距车身后尾一定的距离内有人或物体存在,就会有一部分红外光信号经人或物体反射回来,被与发射管同排安装的光敏接收管收到并转换成同频率的电信号后,由模块内部电路进行放大、解调、整形、比较处理后,在输出端输出控制信号,控制语音录放组件工作,告诉司机车后有人、车后有物体。由于近红外线传感器、语音录放组件均为一体化结构,成本低、接线简单、抗震能力强、测量准确、工作稳定可靠,适合在汽车上安装使用。     

ICF瞄准定位系统的设计

将"神光Ⅱ"装置的原瞄准定位系统改为全反射式,可以用各波长的三倍频激光打靶.本文介绍一个双球面的反射系统的光学设计和测试结果.     

星对星激光雷达反射层析成像技术探讨

以星对星激光雷达成像为应用背景,提出了一种基于啁啾脉冲信号的反射层析成像处理方法,该方法通过激光雷达多角度回波非相干累积实现高分辨率的图像重构;分析了星对星反射层析成像的实现条件,包括成像分辨率、工作模式及成像时间.研究结果表明,采用本文所提出的成像方法,通过同轨道面的伴星探测方式可以满足激光雷达反射层析成像多角度探测的要求,在观测角度范围大于60°时能够得到0.1 m目标分辨率,角度范围越大,分辨率越高,且成像时间与卫星轨道半径和两星距离有关.实验验证了该方法的有效性和星对星反射层析成像的可行性.     

Vlasov辐射器反射特性研究

 利用矩量法导出Vlasov辐射器端口处各种模式模系数（振幅）的计算方法，并利用此方法通过数值计算研究了斜切形Vlasov辐射器的反射特性，得到了辐射器端口反射系数和斜切角度及直径波长比之间的关系。结果表明斜切形辐射器具有很小的反射系数，并从反射特性上为辐射器结构参数的选择提供了依据。     

硝基芴酮与脂肪胺的光化夺氢反应的ESR研究

本文用自旋捕捉技术与ESR方法研究了五种硝基芴酮与五种不同的伯、仲、叔脂肪胺的光化夺氢反应中的活泼自由基。结果表明,当胺中有N上氢和α—C上氢时,优先形成N—中心自由基:仅当无N上氢时,才形成C—中心自由基。