T型微混合器混合特性的浓度分布评价法

提出一种微混合器混合性能的评价方法.在样品盒中注入不同浓度罗丹明B溶液并用体视显微镜观察捕获图像,通过Image J软件读取图像灰度值,建立不同深度下溶液的浓度-灰度值函数关系,运用此关系式将T型微混合器3种不同深度(0.1、 0.2和0.4 mm,质量浓度0.05 %的罗丹明B溶液和去离子水作为配对流体)混合实验中捕获的图像中各像素点上的灰度值转换为浓度值,绘制浓度等高线图及浓度频数分布图,分析各自混合情况,最后引入浓度混合指数概念及计算公式,分析3种深度混合器内不同截面上的混合程度.此方法从定性和定量两方面分析了微尺度下混合腔深度对微混合的影响程度,具有一定的应用价值.     

An Encryption Algorithm for Region of Interest in Medical DICOM Based on One-Dimensional eλ-cos-cot Map

Today, with the rapid development of the Internet, improving image security becomes more and more important. To improve image encryption efficiency, a novel region of interest (ROI) encryption algorithm based on a chaotic system was proposed. First, a new 1D eλ-cos-cot (1D-ECC) with better chaotic performance than the traditional chaotic system is proposed. Second, the chaotic system is used to generate a plaintext-relate keystream based on the label information of a medical image DICOM (Digital Imaging and Communications in Medicine) file, the medical image is segmented using an adaptive threshold, and the segmented region of interest is encrypted. The encryption process is divided into two stages: scrambling and diffusion. In the scrambling stage, helical scanning and index scrambling are combined to scramble. In the diffusion stage, two-dimensional bi-directional diffusion is adopted, that is, the image is bi-directionally diffused row by column to make image security better. The algorithm offers good encryption speed and security performance, according to simulation results and security analysis.     

硝基芳烃对圆腹雅罗鱼毒性的DFT研究

对30种硝基芳烃化合物进行DFT-B3LYP/6-311G**水平全优化计算, 据所得量子化学参数分类建立了硝基苯类和硝基苯胺类化合物对圆腹雅罗鱼急性毒性(－lgEC₅₀)的定量构效关系(QSARs)模型. 结果表明, 硝基苯类化合物的毒性主要由硝基基团的电荷(Q_-NO2)和前线轨道能级差(ΔE)决定; 硝基苯胺类化合物的毒性则由分子最低未占轨道能级(E_LUMO)和ΔE决定. 苯环上取代基的类型、数目和取代位置直接影响到标题化合物的毒性大小, 强吸电子基如硝基会降低Q_-NO2和E_LUMO大小, 使化合物毒性增强, 且邻对位硝基取代的毒性高于间位取代; 相反, 给电子基团氨基的存在则会使化合物的毒性降低. 总之, 硝基是这两类化合物致毒的主要基团, 将硝基包覆或还原为氨基应为此类化合物解毒的重要途径. 最后以1,4-二硝基苯为例, 模拟了其活性亚硝基中间产物与蛋白质中还原性巯基间的反应, 并将其与硝基苯和1,3-硝基苯的反应活化能进行了比较, 讨论了不同取代基数目和位置对分子活性的影响, 结果与QSAR模型分析一致, 进一步验证了硝基芳烃化合物的致毒历程, 研究结果对品优高能炸药的分子设计也有助益.     

MRI相关定量参数在肩峰下撞击综合征诊断中的价值及与肩关节功能、治疗效果的关系

为分析MRI相关定量参数对肩峰下撞击综合征(SIS)的诊断价值,本研究将56例SIS患者设为SIS组,同期56例健康体检者设为对照组,对比了两组对象的一般资料、肩关节功能评分(Constant评分)及MRI相关定量参数水平,探讨了 MRI定量参数与Constant评分、SIS发病相关影响因素、治疗效果的关系及对SIS的...     

Quantitative NMR (qNMR) for pharmaceutical analysis: The pioneering work of George Hanna at the US FDA

In the last two decades, quantitative NMR (qNMR) has become increasingly important for the analysis of pharmaceuticals, chemicals, and natural products including dietary supplements. For the purpose of quality control and chemical standardization of a large variety of pharmaceutical, chemical, and medicinal products, qNMR has proven to be a valuable orthogonal quantification method and a compelling alternative to chromatographic techniques. This work reviews a fundamental component of the early development of qNMR, reflected in the pioneering work of the late George M. Hanna during the years between 1984 and 2006 at the US Food and Drug Administration (FDA). Because Hanna performed the majority of his groundbreaking work on a 90‐MHz instrument, his legacy output connects with recent progress in low‐field benchtop NMR instrumentation. Hanna gradually established the utility of qNMR for the routine quality control analyses practiced in pharmaceutical and related operations well ahead of his peers. His work has the potential to inspire new developments in qNMR applied to small molecules of biomedical importance.     

交通事故的时空热点分析

针对目前交通事故分析中时空维度分离的不足,以H市2013―2015年的交通事故数据为研究对象,根据自组织神经网络、平行坐标系、时空颜色矩阵和时空网络核密度估计、热点分析法,分别从行政区划以及道路网络上进行交通事故的时空特征分析,从宏观和微观角度揭示交通事故的时空热点区域。结果表明,整体来说,在空间上,H市交通事故热点区域4个街道高于8个镇,呈明显的“两带一中心”分布,即硖许线与101省道形成的带状区域和市政府所在的行政中心区域;时间上,早、晚高峰时段最为严重,夜晚较为轻微,呈明显的区域特征分布,即工业办公区热点出现在早高峰时段,生活住宅区热点出现在晚高峰时段,商业消费区热点出现在夜晚时段。     

概念图在化学教学中应用的中外研究对比——基于CiteSpace的知识图谱可视化分析

以CiteSpace为工具,对2009-2018年10年间概念图在化学教学中应用的中外研究文献进行可视化的对比分析.研究表明:与国外研究相比,在应用范围上,国内缺少概念图在大学化学教学中应用的相关研究;在研究内容上,国内学者应加强概念图培养学生高阶思维能力及创造力的研究;从评估方式看,国内较少采用定性和定量相结合的评估...     

Comparison of benzothiazole-based dyes for sensitive DNA detection

For efficient and quantitative DNA detection, fluorescence staining is the most often explored approach, which relies on non-covalent binding of dyes with double stranded DNA (dsDNA). Ethidium bromide (EB) is the most classic DNA stain, but suffers from its high carcinogenicity. A series of less toxic alternatives were developed, many of which contain the core structure of the benzothiazole ring. However, the relationship between the structure and the DNA detection performance was not illustrated. Herein, five benzothiazole dyes, namely thiazole orange, SYBR Green I, PicoGreen, SYBR Safe, and thioflavine-T, were compared for DNA detection through direct fluorescence and gel electrophoresis, with particular focus on the structure-performance relationship. It turned out that SYBR Green I is currently the best choice for DNA detection. The results in this work may be useful for future DNA-staining dye developments.     

X射线荧光光谱分析

评述了我国在2000年7月-2002年6月间X射线荧光光谱，包括粒子激发的X射线光谱的发展和应用，内容包括仪器研制、激发源、探测器、软件、仪器改造、仪器维护和维修、样品制备技术、分析方法研究和应用。     

联用色谱数据的双窗口因子分析

利用组分光谱的特征信息,发展了一种能直接对联用色谱重叠峰中组分进行定性定量分析的新方法──双窗口因子分析（dualwindowfactoranalysis,DWPA）。该法可从多组分重叠峰中定性目标组分,且在未经其它组分的分辨下可直接对目标组分的光谱、色谱进行分辨。因此更适应于联用色谱对复杂体系中待测组分的定性定量分析。用该法成功地对4组分重叠峰进行了分析,实验结果令人满意。