准相位匹配PPKTP晶体连续倍频13 mW绿光输出

采用高压脉冲电场极化,通过电光效应实时监控、倍频通光二维监控等手段的应用,制备出周期为9μm、长为8 mm、宽为3 mm、厚为1 mm的周期极化KTiOPO4晶体(PPKTP);倍频通光实验中,当波长1064 nm的基频光功率为1 W时,得到了功率为13.5 mW的532 nm连续倍频绿光输出,单通倍频转换效率为1.35%,归一化转换效率为1.69%/(W.cm),接近理论最大值。     

Targeting Upconversion Nanoprobes for Magnetic Resonance Imaging of Early Colon Cancer

Colon cancer (CC) is one of the most common intestinal malignancies and is difficult to detect in its early stage by magnetic resonance imaging (MRI) with currently used contrast agents (CAs). The development of targeted CAs contributes to the early diagnosis of CC and thereby enables early intervention and timely therapy. Considering the outstanding performance of upconversion nanoprobes (UCNPs) in high‐performance MR and fluorescence imaging, a new type of nanoprobes with considerably enhanced imaging performance is developed herein. Carcinoembryonic antigen (CEA) antibody is conjugated onto the surface of UCNPs to achieve the targeted imaging of early CC tumors, which overexpress CEA. Both toxicity tests and histological/hematological examinations demonstrate the excellent biocompatibility of these CC‐targeting nanoprobes, which possess great potential for clinical application in the early diagnosis of CC.     

基于中智犹豫模糊语言优先QUALIFLEX方法的绿色供应商选择

针对绿色供应商选择过程中,评价指标数量明显超过可供选择的供应商数量且指标之间存在优序关系等特点,提出了基于中智犹豫模糊语言优先QUAL-IFLEX方法的绿色供应商选择方法.首先,利用中智犹豫模糊语言表征评价信息和评价权重;其次,构造优先矩阵对指标权重做精确化处理,考虑到决策者对指标的要求和指标之间的优序关系,对指标权重...     

近自然彩色图像融合算法及其实时处理系统的发展

在军事和生产领域,特别是在极其恶劣的可视条件下,图像融合技术越来越强调融合效果显示的"近自然"感觉,以及人类视觉感知的要求。从彩色图像融合算法的发展概况出发,着重介绍了两种具有代表性的基于视觉特性的近自然彩色图像融合方法,并特别阐述了课题组近期开展的相关算法研究成果。总结了国内外实时彩色图像融合系统的发展现状,概括了课题组已具备的硬件实验基础,综合分析了实时彩色图像融合技术的若干关键技术,如多源图像特征分析、实时图像配准、融合图像后处理等。针对实时图像融合技术的应用状况,提出图像融合系统未来的发展趋势。     

一种双正则项全变差高光谱图像去噪算法

受传感器特性影响,高光谱图像中的噪声在各个维度都有体现。噪声的存在降低了高光谱图像中信息的有效性,在进行地物分类前必须采用适当的算法对噪声予以去除。文章针对高光谱图像的噪声特性,提出了一种基于全变差的高光谱图像去噪算法。该算法将经典二维图像全变差去噪模型推广至三维形式,提出了采用双正则项及相应的调整参数的目标函数,在三维空间中完成新目标函数的离散化,并采用基于优化-最小化算法的迭代方法对目标函数进行优化与求解。对星载Hyperion成像光谱仪数据的实验表明,适当的设置调整参数,该方法可很好地提高高光谱图像的各波段信噪比、平滑光谱曲线并保留细节特征,其去噪效果优于经典的MNF去噪算法及Savitzky-Golay滤波方法。     

Fabrication of flower-shaped Bi2O3 superstructure by a facile template-free process

A novel flower-shaped Bi₂O₃ superstructure has been successfully synthesized by calcination of the precursor, which was prepared via a citric acid assisted hydrothermal process. The precursor and Bi₂O₃ were characterized with respect to morphology, crystal structure and elemental chemical state by field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). It was shown that both the precursor and Bi₂O₃ flower-shaped superstructure were constructed of numerous nanosheets while the nanosheets consisted of a great deal of nanoparticles. Furthermore, key factors for the formation of the superstructures have been proposed; a mechanism for the growth of the superstructure has been presented based on the FESEM investigation of different growth stages.     

One-step solution synthesis of Fe2O3 nanoparticles at low temperature

A new synthesis method of α-Fe₂O₃ nanoparticles was developed, in which the ferrous and ferric salts as well as polyaniline acted as the precursor and dispersant, respectively. From the investigation of X-ray diffraction and FT-IR spectra, the α-Fe₂O₃ nanoparticles can be directly prepared by the co-precipitation method without high-temperature calcining. Transmission electron microscope (TEM) and scanning electron microscope (SEM) observation revealed that the α-Fe₂O₃ nanoparticles had average diameters ranging from 30.0 to 75.0 nm. Compared with previous methods, this present method shows an easy processing and can be applied on the large-scale produce of α-Fe₂O₃ nanoparticles in one step.     

电热原子吸收光谱法中原子化过程动力学研究的最新进展

本文评述了1994－2000年年间电热原子吸收光谱法中原子化过程动力学研究的最新进展,内容包括升温原子化过程动力学参数测定方法、等温原子化过程动力学参数测定方法、动力学参数测定方法的比较、双先导物升温原子化过程的动力学模型、考虑原子蒸气再沉积过程的升温原子化过程的动力学模型以及原子化器表面、基体改进剂及干扰物对分析物原子化过程的影响。引用文献31篇。     

高压合成立方氮化硼用的新触媒材料的研究

 本文研究了合成立方氮化硼用新触媒材料Mg₃B₂N₄及Ca₃B₂N₄的制备方法，并对它们的稳定性及其催化作用进行了讨论。氮化硼原料的结晶状态及合成温度、合成时间、气流量等对新触媒的合成有着重要的影响。本文还在高温高压下利用新触媒进行了立方氮化硼的合成实验，结果表明，与碱土金属触媒相比新触媒具有合成压力低、转化率高、合成温度和压力范围宽、产物杂志含量低、破碎强度高等优点，是一种应用前景很大的触媒材料。     

一个关于图是分数(k,n)-临界的邻域并条件

设G是一个图,以及k是满足1≤k的整数.一个图G在删除任意n个顶点后的子图均含有分数k-因子,则称G是一个分数(k,n)-临界图.给出了图是一个分数(k,n)-临界图的一个邻域并条件,并且该条件是最佳的.