受激发射损耗荧光显微镜的模型设计及参量优化

受激发射损耗荧光显微镜利用荧光饱和和激发态荧光受激损耗的非线性关系,通过限制损耗区域,可突破远场光学显微术的衍射极限分辨力并实现三维成像。基于对粒子速率方程组的修正,建立了描述荧光团各能级粒子数概率时间特性的模型,并定义了时间平均损耗效率判据。采用高斯函数模拟两束入射激光脉冲通过对模型的数值计算,模拟了激发脉冲的SIED激光脉冲的光强、脉冲宽度以及两束光的延迟时间等参量与损耗效率之间的关系,并获得了各参量的最佳值,优化了损耗效率,为提高系统分辨力提供了有效的途径。     

正弦变化的振幅型光瞳滤波器

光瞳滤波器作为实现超分辨的基本元件之一,它的设计以及制作都非常重要。设计了一种正弦变化的振幅型光瞳滤波器,可以通过调节少量的参量实现各种不同的超分辨模式。选择正弦函数的周期以及光瞳中心点透过率变化两个参量来实现对最终超分辨效果的调节。数值计算结果表明：在整个人射光瞳上的透过率瞳函数分布具有0．5～2个正弦振幅周期时,较为合适。小于0．5个周期将不会有任何超分辨效果,大于2个周期超分辨效果反而变差。数值计算中还注意到,当周期数为整数时,斯特雷尔比将保持0．25不变。对正弦变化振幅型光瞳滤波器的计算结果,显示了其特殊的性质,对实际中制作正弦变化振幅型光瞳滤波器有一定的指导作用。     

Simultaneous determination of endocrine-disrupting phenols and steroid estrogens in sediment by gas chromatography-mass spectrometry

A simple and effective method has been developed to simultaneously determine endocrine-disrupting phenolic xenoestrogens and steroid estrogens in sediment by using ultra-sonicated extraction in combination with silica gel fractionation, derivatization with pentafluropropionic anhydride, and gas chromatography-mass spectrometry (GC-MS) in selected ion monitoring mode (SIM). Satisfactory recoveries have been obtained for phenolic xenoestrogens and steroid estrogens. The method enables the determination of targets at concentrations of lower nanogram-per-gram in sediments. The method has been successfully applied to the sediments collected from Pearl River Estuary (PRE), South China Sea, China. Nonylphenol and bisphenol-A (BPA) were detected in the range from 204.2 to 664.5 ng/g and 0.6 to 4.0 ng/g, respectively. None of the estrogens were found in the sediment samples.     

钕、铽(Ⅲ)硝酸盐、水杨醛乙二胺双席夫碱、二甲亚砜三元配合物的NMR研究

用NMR的方法研究了新型稀土配合物:钕、铽(Ⅲ)硝酸盐与N,N-二亚水杨基乙二胺双席夫碱、二甲亚砜三元配合物的结构,并利用二维质子NOE谱和异核多量子相关谱完全归属了它们的质子和¹³C信号.     

基于混沌自适应粒子群人工神经网络的气体在聚合物中的溶解模型

为提高溶解预测模型的效率和关联度, 建立基于混沌理论、自适应粒子群优化(PSO)算法和反向传播(BP)算法的混沌自适应PSO-BP神经网络模型, 并对二氧化碳(CO₂)在聚苯乙烯(PS)和聚丙烯(PP)中、氮气(N₂)在PS中的溶解度进行预测试验. 模型选用压力和温度作为输入参数, 使用试探法确定隐含层结点个数为8, 输出为预测的溶解度. 模型融合混沌理论、自适应PSO和BP算法各自的优势, 提高了训练速度和预测精度. 结果表明, 混沌自适应PSO-BP神经网络有很好的预测能力, 预测值与实验值相当吻合, 通过与传统BP神经网络和PSO-BP神经网络的比较可知, 其预测精度和相关性均明显较优, 预测平均绝对误差(AAD), 标准偏差(SD)和平方相关系数(R²)分别为0.0058, 0.0198和0.9914.     

5H-3-oxa-Octafluoropentanesulfonyl fluoride: a novel and efficient condensing agent for esterification, amidation and anhydridization

The use of 5H-3-oxa-octafluoropentanesulfonyl fluoride (HCF₂CF₂OCF₂CF₂SO₂F) as a novel and efficient condensing reagent for esterification of carboxylic acids with alcohols and amidation of carboxylic acids with amines in the presence of 1,3-diazabicyclo[5.4.0]-undec-7-ene (DBU) is reported. HCF₂CF₂OCF₂CF₂SO₂F cannot serve as a condensing agent for anhydridization of carboxylic acids, however, HCF₂CF₂OCF₂CF₂SO₂F/(CH₃)₃SiCN system can mediate anhydridization of some aromatic carboxylic acids.     

Fractional amplitude of low-frequency fluctuation changes in functional dyspepsia: A resting-state fMRI study

Recently, there is an increasing interest in the study of the role of brain dysfunction in the pathogenesis of symptoms of functional dyspepsia (FD). More specifically, abnormal brain activities in patients with FD during the resting state have been proven by several positron emission tomography (PET) studies. Resting-state functional magnetic resonance imaging (fMRI) is also a valuable tool in investigating spontaneous brain activity abnormalities in pathological conditions. In the present study, we examined the amplitude of low-frequency fluctuations (ALFF) and fractional (f)ALFF changes in patients with FD by using fMRI. Twenty-nine patients with FD and sixteen healthy controls participated in this study. Between-group differences in ALFF/fALFF were examined using a permutation-based nonparametric test after accounting for the gender and age effects. The results revealed a significant between-group difference in fALFF but not in ALFF in multiple brain regions including the right insula, brainstem and cerebellum. Seed-based resting-state functional connectivity analysis revealed that FD patients have increased correlations between the right cerebellum and multiple brain regions including the bilateral brainstem, bilateral cerebellum, bilateral thalamus, left para-/hippocampus, left pallidum and left putamen. Furthermore, fLAFF values in the right insula were positively correlated with the severity of the disease. These findings have provided further evidence of spontaneous brain activity abnormalities in FD patients which might contribute to our understanding of the pathophysiology of the disease.     

Real-time monitoring of laser welding of galvanized high strength steel in lap joint configuration

Two different cases regarding the zinc coating at the lap joint faying surface are selected for studying the influence of zinc vapor on the keyhole dynamics of the weld pool and the final welding quality. One case has the zinc coating fully removed at the faying surface; while the other case retains the zinc coating on the faying surface. It is found that removal of the zinc coating at the faying surface produces a significantly better weld quality as exemplified by a lack of spatters whereas intense spatters are present when the zinc coating is present at the faying surface. Spectroscopy is used to detect the optical spectra emitted from a laser generated plasma plume during the laser welding of galvanized high strength DP980 steel in a lap-joint configuration. A correlation between the electron temperature and defects within the weld bead is identified by using the Boltzmann plot method. The laser weld pool keyhole dynamic behavior affected by a high-pressure zinc vapor generated at the faying surface of galvanized steel lap-joint is monitored in real-time by a high speed charge-coupled device (CCD) camera assisted with a green laser as an illumination source.     

钕、铽(Ⅲ)硝酸盐、水杨醛乙二胺双席夫碱、二甲亚砜三元配合物的NMR研究

用NMR的方法研究了新型稀土配合物：钕、铽（Ⅲ）硝酸盐与N，N-二亚水杨基乙二胺双席夫碱、二甲亚砜三元配合物的结构，并利用二维质子NOE谱和异核多量子相关谱完全归属了它们的质子和13C信号．