甲醛功能化聚乙烯亚胺-罗丹明B酰肼比率及可视化荧光测定Cr(Ⅵ)

在微波辅助条件下,合成了具有蓝色荧光特性的甲醛功能化的聚乙烯亚胺(FPEI).在硫酸介质中,FPEI表面质子化的氨基通过静电作用吸附Cr(Ⅵ),致使FPEI 480 nm处的荧光强度逐渐降低.同时,罗丹明B酰肼(RBH)被Cr(Ⅵ)氧化生成强荧光发射的罗丹明B,体系的吸光度在250~600 nm范围显著增强,覆盖了FPEI的激发和发射光谱,由此产生的内滤效应导致FPEI的荧光进一步降低.罗丹明B 580 nm处荧光强度和FPEI 480 nm处荧光强度的比值(F_(580)/F_(480))与Cr(VI)的浓度呈良好的线性关系,在紫外灯照射下体系的荧光由蓝色逐渐变为橙黄色,由此建立了一种新型的比率及可视化荧光测定六价铬的新方法.在最优条件下,比率荧光测定的线性范围为0.1~3.6μmol/L,检出限(3σ)为12 nmol/L,可视化荧光检测的线性范围为0.4~2.8μmol/L.该方法简单、快速,灵敏度及选择性好,用于实际样品测定的回收率为90%~109%.     

基于柱[5]芳烃聚合物水凝胶的制备及对百草枯的可视化检测

合成了单功能化的柱[5]芳烃单烯体,然后将其与丙烯酰胺(AAM)、交联剂N,N'-亚甲基双丙烯酰胺(MBA)和引发剂偶氮二异丁腈(AIBN)在70 oC下反应12 h后形成含有大环主体柱[5]芳烃的高分子聚合物,将此聚合物分别浸泡于DMSO、水中各1周,并每天更换新鲜的溶剂,最后通过此聚合物的红外光谱图证实成功制备了含有柱[5]芳烃的聚合物水凝胶.利用紫外吸收光谱测试表征了水凝胶对百草枯的吸收作用.将该水凝胶浸入浓度从小到大的百草枯溶液中,发现水凝胶颜色由浅黄色变为棕红色,这是由于水凝胶中的柱[5]芳烃与N,N'-二甲基-4,4'-联吡啶客体分子之间主客体作用形成了含有准轮烷结构的超分子聚合物所致.     

Incrementing visual cryptography using random grids

Visual cryptography (VC) is an image-based secret protection mechanism in which the decoding process is conducted by inspecting the stacked shares with the unaided eye. In traditional VC schemes, the content of an image is usually processed as a single secret, which limits the whole image to unique secret property. Recently, Wang ( IEEE SPL, 16(2009) 659-663) proposed an n-level region incrementing VC scheme which has the ability of incremental revealing of the secrets on an image; however, the pixel expansion of the generated shares increases rapidly in the proposed scheme as n grows. In this paper, we propose an incrementing VC scheme using random grids. The method has the same incremental revealing effect to the secrets on an image, and the size of each share is the same as that of the original image without any expansion. The smaller size of shares makes their further processing such as storage and/or printing out more efficient.     

A novel algorithm based on visual saliency attention for localization and segmentation in rapidly-stained leukocyte images

In this paper, we propose a fast hierarchical framework of leukocyte localization and segmentation in rapidly-stained leukocyte images (RSLI) with complex backgrounds and varying illumination. The proposed framework contains two main steps. First, a nucleus saliency model based on average absolute difference is built, which locates each leukocyte precisely while effectively removes dyeing impurities and erythrocyte fragments. Secondly, two different schemes are presented for segmenting the nuclei and cytoplasm respectively. As for nuclei segmentation, to solve the overlap problem between leukocytes, we extract the nucleus lobes first and further group them. The lobes extraction is realized by the histogram-based contrast map and watershed segmentation, taking into account the saliency and similarity of nucleus color. Meanwhile, as for cytoplasm segmentation, to extract the blurry contour of the cytoplasm under instable illumination, we propose a cytoplasm enhancement based on tri-modal histogram specification, which specifically improves the contrast of cytoplasm while maintaining others. Then, the contour of cytoplasm is quickly obtained by extraction based on parameter-controlled adaptive attention window. Furthermore, the contour is corrected by concave points matching in order to solve the overlap between leukocytes and impurities. The experiments show the effectiveness of the proposed nucleus saliency model, which achieves average localization accuracy with F1-measure greater than 95%. In addition, the comparison of single leukocyte segmentation accuracy and running time has demonstrated that the proposed segmentation scheme outperforms the former approaches in RSLI.     

用Visual Foxpro 6.0实现文件批量重命名

目前,Visual Foxpro 6.0关系数据库系统的应用广泛。文中结合工作实际,运用Visual FoxPro 6.0的宏代换功能,解决了普通高等学校在网上招生录取工作结束之后,按照表中的相应字段,将被录取新生的电子照片文件名由其考生号批量重命名为学号的问题。     

三菱PLC与上位机串行通信的实现

为了实现对现场生产过程进行监控,PLC串行通信技术在工业生产中正得到越来越广泛的应用,介绍了三菱FX2N系列PLC与上位机进行通信的主要原理,阐述在Visual Basic 6.0环境下上位机与三菱FX2N PLC串行通信的具体实现方法。具体介绍了与上位机通信的硬件连接,三菱FX2N PLC的通信协议及VB中的MSCOMM控件,对通信实现过程中的主要程序进行简单分析。     

Oracle存储过程应用实例

Oracle允许将PL／SQL语言编写的存储过程作为数据库对象存储在教据库中，存储过程通过语法分析，将第一次执行编译的SQL语句存储在高速缓冲存储器中．下次使用只需从高速缓冲区中调用已编译的代码，加速了SOL语句的执行。提高了应用系统性能。以某GPS车辆监拉系统为例。给出了Visual C＋＋开发平台下利用ADO链接数据库并调用数据库存储过程的具体过程。     

Functional magnetic resonance imaging of awake monkeys: some approaches for improving imaging quality

Functional magnetic resonance imaging (fMRI) at high magnetic field strength can suffer from serious degradation of image quality because of motion and physiological noise, as well as spatial distortions and signal losses due to susceptibility effects. Overcoming such limitations is essential for sensitive detection and reliable interpretation of fMRI data. These issues are particularly problematic in studies of awake animals. As part of our initial efforts to study functional brain activations in awake, behaving monkeys using fMRI at 4.7 T, we have developed acquisition and analysis procedures to improve image quality with encouraging results.We evaluated the influence of two main variables on image quality. First, we show how important the level of behavioral training is for obtaining good data stability and high temporal signal-to-noise ratios. In initial sessions, our typical scan session lasted 1.5 h, partitioned into short (<10 min) runs. During reward periods and breaks between runs, the monkey exhibited movements resulting in considerable image misregistrations. After a few months of extensive behavioral training, we were able to increase the length of individual runs and the total length of each session. The monkey learned to wait until the end of a block for fluid reward, resulting in longer periods of continuous acquisition. Each additional 60 training sessions extended the duration of each session by 60 min, culminating, after about 140 training sessions, in sessions that last about 4 h. As a result, the average translational movement decreased from over 500 μm to less than 80 μm, a displacement close to that observed in anesthetized monkeys scanned in a 7-T horizontal scanner.Another major source of distortion at high fields arises from susceptibility variations. To reduce such artifacts, we used segmented gradient-echo echo-planar imaging (EPI) sequences. Increasing the number of segments significantly decreased susceptibility artifacts and image distortion. Comparisons of images from functional runs using four segments with those using a single-shot EPI sequence revealed a roughly twofold improvement in functional signal-to-noise-ratio and 50% decrease in distortion. These methods enabled reliable detection of neural activation and permitted blood-oxygenation-level-dependent-based mapping of early visual areas in monkeys using a volume coil.In summary, both extensive behavioral training of monkeys and application of segmented gradient-echo EPI sequence improved signal-to-noise ratio and image quality. Understanding the effects these factors have is important for the application of high field imaging methods to the detection of submillimeter functional structures in the awake monkey brain.     

Perceptual watermarking using a new Just-Noticeable-Difference model

In this paper, a new watermarking scheme based on Human Visual System (HVS) modeling is proposed. The approach consists in building computational models which take into account the most common properties of the HVS that can be exploited for watermarking. Two schemes for embedding and controlling the transparency of the watermark are presented, namely the implicit and the explicit schemes. Both schemes are designed in the framework of the pyramidal decomposition which has been shown to be a powerful tool for analyzing image through a multi-scale representation. For the first approach, a multi-scale visibility map is used to optimize the watermark embedding process. The second approach makes use of HVS properties in an explicit and more sophisticated manner that consists in tuning the watermark strength just beneath the visual detection threshold. A new JND (Just-Noticeable-Difference) model for determining this threshold is then proposed and evaluated. The obtained results provide a strong support for this new JND model.     

基于随机网格的视觉多秘密共享方案

为了提高视觉秘密共享(VSS)的恢复效果,该文提出一种基于随机网格的视觉多秘密共享方案。通过使用一种基于圆柱面的随机网格阈值多秘密图像共享方案,使得用户一次可以共享多个秘密图像;部分份额图像受到篡改仍然可以恢复秘密图像,具有较好的鲁棒性;同时份额的数量和最后恢复图像的视觉质量成正相关。仿真结果表明所提出的多秘密视觉共享方案在恢复像素正确率方面是原有的单秘密视觉共享方案2 倍多,即在增加了多个秘密图像的同时,提高了恢复的正确率。