直肠癌及直肠正常组织的IR和1H及31P NMR谱研究

对12例直肠组织的红外光谱图进行了测定,并对6例直肠癌变及正常组织的固体1H和31P NMR谱与另外6例直肠癌变及正常组织的液体1H和31P-NMR谱进行研究.结果表明,(1)直肠癌变和正常组织的红外光谱中存在明显差异.(2)在固体1H和31P NMR谱中,1H NMR谱上癌组织的脂肪酸与水相关的特征峰面积的比值I(5+6+7)/I(1+2+3+4)明显变低,依据I(5+6+7)/I(1+2+3+4)比值可区分癌变与正常组织.31P NMR谱上,癌变组织的最强峰的化学位移明显向高场偏移.(3)在液体1H和31P NMR谱中,1H NMR谱上癌组织中3.20处峰强较正常组织高,表明与癌变密切相关的胆碱类化合物包括游离的胆碱、磷酸胆碱及甘油磷酸胆碱等的量增大.31P NMR谱上,癌变组织的强度最大峰的化学位移分别为1.18,1.26,1.29,1.37,正常组织的化学位移为1.70和2.18,癌变组织的强度最大峰的化学位移明显向高场偏移.通过癌变与正常组织代谢物1H NMR谱峰强度和1P NMR谱峰化学位移的差异,可以区分直肠癌变和正常组织,核磁共振1H和31P NMR谱技术可能发展成为一种诊断直肠癌的新方法.     

垂直结构多色量子点LED(QD-LED)最新进展

量子点LED以胶体量子点为发光层,通过调节作为发光层量子点的尺寸可以制作出覆盖可见(380-780nm)以及近红外光谱的量子点LED(QD-LED),而且量子点LED器件发出的光谱范围很窄,其光谱半高宽可达30nm。简述了当今国内外关于QD-LED器件结构的研究成果以及器件的制作工艺,介绍了目前课题组最新的一些相关成果。重点阐述了目前已经得到验证的几种量子点器件结构,分析了其存在的优缺点,这些结论对进一步改进QD-LED的结构以及使其可以更有利于商业化提供了参考。     

颗粒有序堆积多孔介质对流换热实验研究

本文采用"瞬态单吹反问题研究方法"对颗粒有序堆积多孔介质内的强制对流换热进行了实验研究。详细研究了颗粒堆积方式变化对多孔介质内对流换热的影响,并对均匀与非均匀颗粒堆积多孔介质内的对流换热特性进行了对比分析。研究表明:通过对颗粒进行合理有序堆积,可以使相应多孔介质内的压降显著降低,其综合换热效率明显提高;通过拟合获得了颗粒有序堆积多孔介质内的宏观流动换热实验关联式,其形式与传统经验公式(Ergun公式和Wakao公式)一致,但部分模型参数值远低于传统经验公式。     

哈斯勒合金Ni45Co5Mn37In13的磁场诱导马氏体相变和反磁热效应研究

通过结构和磁性测量,对Ni45Co5Mn37In13多晶样品的马氏体相变性质进行了系统研究,发现Co原子的间隙掺杂能够提高三元合金奥氏体相与马氏体相之间的磁化强度差异(ΔM).以此为基础,结合基本热力学理论,总结了计算驱动完整马氏体相变所对应临界磁场在热力学上的一般表达式,并结合Ni45Co5Mn37In13的实验结果对该表达式进行了基本讨论,充分证明了磁场诱导马氏体相变不仅与该类合金两相之间的ΔM有关,而且还依赖于合金在相变过程的温度跨度与热滞后.此外,计算了Ni45Co5Mn37In13合金在磁场诱导马氏体相变过程中的反磁热效应.结果表明,该合金的饱和等温熵变约为27J/kg K.而且保持在一个非常宽的温度跨度内,以至于样品在50kOe磁场改变下的磁制冷量已经达到了约340J/kg.     

快反系统中平面反射镜的轻量化设计

根据快速控制反射镜系统(快反系统)对平面反射镜的设计要求,对快反镜的轻量化结构进行了优化设计。选择比刚度大、热变形系数小的碳化硅为镜坯材料,采用背部开槽式结构减重,背部3点式支撑,对不同筋宽和镜面厚度等多种轻量化方案进行了有限元分析。结果表明:筋宽越大,镜体刚度越好,但筋宽增大到一定程度时,反射镜刚度的改善程度减缓;镜面越厚,镜体内应力、自重变形越大。结合反射镜设计要求和有限元分析结果,加工制备了筋宽为4 mm,镜面厚度为4 mm的碳化硅反射镜,镜体轻量化率达55%。实测反射镜的面形精度,其RMS值不超过λ/30,与分析结果相符,满足系统的使用要求。     

Synthesis of broadband and flat parametric gain by idler loss in optical fiber

Besides dispersion engineering, idler-band distributed fiber loss provides a new synthesis freedom to flatten and broaden the gain spectrum for a fiber-optic parametric amplifier. This interesting phenomenon is based on the fact that the power balance between signal and idler is broken by idler loss, which changes the power conversion process in four-wave-mixing. The pump-to-signal conversion efficiency is kept unchanged in spite of the loss.     

Improving histogram-based image contrast enhancement using gray-level information histogram with application to X-ray images

Many applications of histogram-based techniques for the purposes of image enhancement are well known. However, these techniques often fail to produce satisfactory results for a broad variety of low-contrast images (e.g., X-ray images). In this paper, we propose a new form of histogram for image contrast enhancement. The input image is first divided into several equal-sized regions according to the intensities of gradients, their corresponding statistical values of gray levels are then modified respectively, and finally the processed histogram for the whole image is obtained by the summation of all the weighted values of regions. The fundamental characteristic of this new form of histogram is that the amplitudes of its components can objectively reflect the contribution of the gray levels to the representation of image information. Accordingly, this new histogram is called gray-level information histogram. The performance of many histogram-based enhancement techniques might be improved dramatically using the proposed histogram. Testing on the X-ray images validates the effectiveness of the new histogram.     

Femtosecond laser-induced microstructure in Foturan glass

We report on the microstructure formation in Foturan glass, induced by 1~kHz, 120 femtosecond laser irradiation. It is found that the line-shaped filamentation, not void array tends to be formed in this glass. This is different from our previous experimental results in fused silica and BK7 glasses. A possible mechanism Ag$^+$ captures the free electrons generated by laser, is proposed to explain the observed phenomena.     

有限气相反应速率条件下MFF模型应用方法的研究

本文使用CO相对燃烧速率的概念和通用的有效影响参数转化方程,将带有气相反应速率无穷快假设的移动火焰锋面(MFF)模型成功地扩展应用到有限气相反应速率条件的计算中。对于多组不同有限气相反应速率、以及不同粒径的碳粒燃烧计算,MFF模型扩展应用的预报结果都与严格连续膜模型符合较好,碳粒着火温度的预报也更为准确。     

Millimeter-Wave Spectra of the CO Dimer: Three New States and Further Evidence of Distinct Isomers

The millimeter-wave spectrum of the normal isotope of the CO dimer, (¹²C¹⁶O)₂, has been systematically surveyed in the regions 75-105 and 131-174 GHz, with additional measurements covering the entire 60-176 GHz range. By combining these results and using the technique of combination differences based on previously known energy levels, 14 new rotational levels have been assigned and precisely (≈0.1 MHz) located. They belong to 3 completely new states, 1 with A⁺ symmetry and 2 with A⁻ symmetry. The position of the lowest energy A⁻ state results in a new and lower value for the effective tunneling splitting of the CO dimer, 3.73 cm⁻¹. The observation of dramatically different intensities for different bands supports the concept of two isomeric forms for (CO)₂, the ground state having a larger intermolecular separation (≈4.4 Å) with most likely a C-bonded configuration, and the low-lying (0.88 cm⁻¹) excited state having a smaller separation (≈4.0 Å) and an O-bonded geometry.