Confinement-deconfinement interplay in quantum phases of doped Mott insulators

In the t-J model, the electron fractionalization is dictated by the phase string effect. We find that in the underdoped regime, the antiferromagnetic and superconducting phases are dual: in the former, holons are confined while spinons are deconfined, and vice?versa in the latter. These two phases are separated by a novel phase, the so-called Bose-insulating phase, where both holons and spinons are deconfined. A pair of Wilson loops was found to constitute a complete set of order parameters determining this zero-temperature phase diagram. The quantum phase transitions between these phases are suggested to be of non-Landau-Ginzburg-Wilson type.     

基于全变分正则化的高能闪光照相消模糊图像重建算法

 针对高能闪光照相投影图像消模糊难度大的问题,提出了一种基于全变分正则化的消模糊图像重建算法,该算法根据闪光照相的成像特点,将客体的纵向截面作为一个整体来进行建模,并在重建方程中考虑了模糊因素,然后采用全变分范数作为正则项,构建了用于消模糊图像重建的展平泛函,将消模糊图像重建问题转化为能量泛函极小化问题,通过固定点迭代算法求解图像重建问题的最小化解。数值模拟结果表明：该算法由于考虑了闪光照相成像时的图像模糊因素,在重建时能够较好地消除模糊对重建结果的影响,在抑制噪声的同时能较好地保持图像的边缘信息,有利于提高重建图像的质量。     

低电感大电流长寿命同轴型电容器

 介绍了一种应用于高功率脉冲源的低电感、高通流能力、长寿命的同轴型电容器。通过理论计算,综合考虑电容器的工作电压、电感、通流能力、与开关的连接方式等,确定了电容器的芯子结构、绝缘子结构及电极结构。通过设计实验线路,测试了电容器的电压、电感、通流能力、寿命等参数。实验结果表明：电容器电容量1.5 μF,工作电压100 kV,工作电流250 kA,峰值电流大于300 kA,电容器电感小于20 nH,储能密度205 J/L,工作寿命大于6 000次。     

三电极气体开关自陡化技术及应用

 根据Trigatron的触发要求设计了脉冲变压器型驱动源、三电极气体开关。在多种驱动模式下对三电极开关的自陡化参数进行统计分析,选择最优的自陡化工作模式。通过研究自陡化工作模式,优化了三电极开关工作极性、工作电场、紫外辐照强度和辐照时间。试验结果表明：增加陡化环节后,Trigatron的击穿概率有了明显提高,击穿时刻延迟和抖动明显降低,扩大了Trigatron稳定工作的欠压比范围。     

ICF中子发射时间诊断

 对ICF中子发射时间的诊断技术进行了研究,研制了基于快闪烁体和微通道板式光电倍增管的中子发射时间探测器。在某大型激光原型装置上进行了中子发射时间的实验测量,成功获得多发实验的中子发射时间与打靶激光脉冲的时间及中子发射时间之间的关系。实验结果表明：中子发射时间探测器对DT中子和DD中子都能够响应,中子产额测量下限达到10⁷,时间测量不确定度小于20 ps;CH烧蚀层越厚,中子发射时间越长。     

医用生物材料的低温保存研究

生物材料的低温保存一般都要经历降温过程、低温储存过程及复温过程,其中降温过程中对生物细胞的影响最大.每一种生物细胞都有自己合适的降温速率,如能满足其这种降温速率,细胞所受到的低温损伤最小,则生物细胞的复活率最高.文中介绍程序控制变速降温装置的主要结构及几种典型生物体的降温过程.最后,对器官的低温保存进行分析讨论.     

宽光谱膜厚监控系统中光谱实时测量技术研究

 在宽光谱膜厚监控系统中,利用光栅光谱仪分光,线阵CCD接收,完成光谱的一次性快速扫描来控制膜层厚度,达到实时监控的要求。而系统光谱扫描的准确性,直接影响膜厚实时监控的有效性。为了得到准确的光谱信息,首先确定CCD像素和光波波长的对应关系,基于特征谱线的离散关系,采用最小二乘拟合法建立了光谱标定函数,经实验,标定波长均方根误差为0.037 nm;对于CCD实时输出的光谱监控信号,利用小波阈值优化算法抑制信号中的随机噪声,保留了光谱信号的细节成分,峰值误差的最大值为1.0%,峰位误差的最大值为0.3%,满足了监控中光谱分辨率的要求。     

Synthesis of water-dispersible photoluminescent silicon nanoparticles and their use in biological fluorescent imaging

Water-dispersible silicon nanoparticles (Si-NPs) are desirable for applications in biological techniques. A simplified method to synthesize such particles is reported here. The resulting Si-NPs are water-dispersible and luminescent. Under the excitation of UV light, the Si-NPs emit strong red light with a peak maximum at 606 nm and a quantum yield of 6%. They are highly stable, and remain so over several weeks. Fourier Transform Infrared (FTIR) spectroscopy shows a visible Si–CH₂ scissoring vibration mode. Furthermore, the surface chemical bondings were confirmed by X-ray photoelectron spectroscopy (XPS). In the Si2p and C1s core levels, Si–C components are observed. The diameters of the synthesized Si-NPS as measured by atomic force microscope (AFM) are approximately 5 nm. Furthermore, the nanoparticles can be taken up by cultured cells. Fluorescence images of Si-NPs within MCF-7 human breast cancer cells show they are distributed throughout the cell tissue.     

Some duct flows of a fractional Maxwell fluid

The aim of this paper is to establish the analytical solutions corresponding to two types of unsteady flows of fractional Maxwell fluid in a duct of rectangular cross-section. The fractional calculus approach is used in solving the problems. With the help of the methods of separation of variables and Laplace transforms, the expressions for the velocity field and the volume flux are presented under series forms in terms of the generalized G functions. Similar solutions for Newtonian and ordinary Maxwell fluids, performing the same motions, are also obtained as the limiting cases of our solutions. Furthermore, the influence of pertinent parameters on the flows is delineated and appropriate conclusions are drawn.     

A wire microcalorimetric study of catalytic ignition of methane–air mixtures over palladium oxide

Catalytic ignition and heat release of methane oxidation over a Pd wire covered with a 1–2 μm PdO surface layer were investigated by wire microcalorimetry over the temperature range of 600–770 K and pressure range of 0.5–4 atm. Ignition temperatures and heat release rates for different methane concentrations (1–4 vol.% in dry air) were determined, showing that the ignition temperatures decrease with increasing the methane concentration and increasing ambient pressure. At total pressure of 1 atm and 2% methane concentration, the global activation energy for the catalytic reaction is 21.5 ± 0.9 kcal/mol and 14.3 ± 0.2 kcal/mol in the temperature ranges of 600–670 K and 670–770 K, respectively. The reaction order for methane is 0.9 ± 0.1 over the temperature range of 630–770 K.