Automatic detection of colloidal particles based on a shape regularized integrated active contour model

Manual segmentation of single colloidal particle in suspension encounters a bottleneck when a number of defocused particles simultaneously exist in an image. In this paper, we describe an image processing algorithm for extracting individual particle from digitized microscope images of colloidal suspensions. We propose a particle detection and location solution using a shape regularized integrated active contour model (ACM). Compared with existing methods where active contour models are not applied well to deal with multiple objects in complicated background, the proposed approach can automatically identify and locate multiple particles by combining characteristics of the particles such as shape, boundary and region. A regularization term is defined by prior information of specific shape, which is able to drive the shape of evolving curve toward the shape prior gradually. To locate the centers of the particles, the Hough transform is applied. Experimental results using polystyrene beads as sample particles reveal that the method has high efficiency and ability to deal with colloidal particles.     

制备腈菌唑分子印迹聚合物前功能单体选择研究

为制备腈菌唑(M)分子印迹聚合物,建立了选择合适的功能单体以及功能单体添加量的方法。利用紫外光谱法研究α-甲基丙烯酸(MAA)、丙烯酰胺(AM)与M作用形式、作用强度、最佳浓度比和形成的结合位点数。结果表明,M与两种功能单体都会形成氢键;M的三唑环共轭双键的π电子吸收能量跃迁到π*共轭反键轨道,氢键的形成会使π→π*的吸收带发生迁移,最大吸收波长随着体系功能单体浓度增加而发生红移。M与两种功能单体最佳浓度配比分别为:M∶MAA=1∶4和M∶AM=1∶2。M与两种功能单体都具有结合能力,且结合力较强。采用AM为功能单体合成的分子印迹聚合物对M具有更好的稳定性和特异识别能力。     

On redundant weighted voting systems with components having stochastic arrangement increasing lifetimes

As one generalization of the k-out-of-n structure, the weighted voting system has been paid much attention during the past two decades. This paper has a further study on active redundancies allocation to weighted voting reliability systems of components having LWSAI lifetimes. For redundancies with SAI lifetimes, allocating a more reliable redundancy to a weaker and more heavily weighted component is found to produce a more reliable system in the sense of having higher reliability. Also, in the context of redundancies with identically distributed lifetimes, we show that allocating more redundancies to a weaker and more heavily weighted component produces a more reliable system. Some numerical examples are presented to illustrate the main results as well.     

Advances in self-crosslinking of acrylic emulsion: what we know and what we would like to know

This review covers various strategies that enable self-crosslinking of acrylic emulsion, and gives a detailed idea of different one component (1K) crosslinking systems along with their reaction mechanisms, film properties and applications. The review is categorized into four main parts: (i) self-condensation of N-methylol functionality (ii) reaction of keto-hydrazide or acetoacetoxy-diamine functional group (iii) self-condensation of organofunctional silanes (iv) metal complex (salts, chelates) reaction with backbone functional group such as acetoacetoxy group or carboxylic group (v) UV curable functional monomers. These crosslinking reactions are low-temperature curable and offers excellent film properties than the conventional two-pack (2K) cross-linking emulsion system. This crosslinking system has good potential application in water-based coatings. Various examples are portrayed, along with a discussion of their advantages, drawbacks and limitations.     

Fluorescence Microscopy and Flow Cytofluorometry of Reactive Oxygen Species

Abstract

The effects of reactive oxygen species on cell function and health have driven the development of numerous detection methodologies to assess oxidative stress. In this article, we review the detection of reactive oxygen species by fluorescence microscopy and flow cytofluorometry over the last seven years. Emphasis is placed on the variety of sample matrices analyzed and the diverse biomedical questions and oxidative stress mediated diseases that benefit from the information provided by these fluorescence-based analytical techniques.     

An improved Balz-Schiemann reaction enabled by ionic liquids and continuous processing

A Balz-Schiemann reaction was developed to convert 2-cyano-5-aminopyridine to 2-cyano-5-fluoropyridine. The use of an ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate, BMIMBF₄) as a solvent was found to be critical in achieving high assay yields and high selectivity for the fluorination vs. protonation. A process was developed to recycle and reuse the ionic liquid enabling its cost-effective use as a solvent. Finally, the optimal conditions were demonstrated under as a continuous process to address process safety risks associated with diazonium intermediates and the product was used to access a key intermediate in the synthesis of β-amyloid cleaving enzyme 1 inhibitor, verubecestat.     

Trans-limonene dioxide,a promising bio-based epoxy monomer

Vast quantities of the natural terpene (R)-limonene can be collected from food waste. Epoxidation of its two double bonds provides limonene dioxide (LDO), a difunctional epoxy monomer. However, LDO is a mixture of four isomers, two of which (trans-LDO) are actually difunctional while the others (cis-LDO) have one epoxide group which is significantly less reactive, as revealed by Fourier transformed infrared spectroscopic analysis of formulations cross-linked with polyethylene imine. These results are also confirmed when preparing epoxy formulations using respectively cis or trans isomers. From DFT calculations, the reactivity of each epoxide group of LDO has been assessed in model reactions with primary and secondary amines, in the presence of amine or alcohol hydrogen-bond donors. The kinetics of cross-linking has also been probed by differential scanning calorimetry. As measured by dynamic mechanical analysis, the resulting epoxy resins based on trans isomers have a storage modulus of ca 1GPa at room temperature and a glass transition temperature (T_g) of 70°C. These results demonstrate that trans LDO is a promising bio-based epoxy monomer, which could be used as an alternative to petroleum-based epoxy monomers.     

Active,self-motile,and driven emulsions

In this review, we focus on recent experiments involving transport and other dynamical aspects of emulsified droplets under nonequilibrium conditions. We include both active emulsions, where individual droplets develop self-propulsion or self-sustained motion at the expense of local energy sources, and driven emulsions, where droplets are activated through the local transduction of an external source. A common theme in the reported scenarios is the use of hybrid colloidal systems, where emulsions and liquid crystals are interfaced, providing with a rich scenario that features phenomena and mechanisms not found in traditional emulsions.     

Cyclopropanation of active methylene compounds with β-alkoxycarbonyl vinylsulfonium salts

An efficient synthesis of β-alkoxycarbonyl vinylsulfonium salts had been developed. Their reaction with indene-1,3-diones and other active methylene compounds provided cyclopropane carboxylates in good yields. A tentative reaction mechanism was proposed.     

Active control of elastic wave propagation in nonlinear phononic crystals consisting of diatomic lattice chain

This work studies the active control effects on nonlinear phononic crystals by the piezoelectric spring model. Both negative and positive proportional control actions are considered. Based on the Lindstedt–Poincaré method, the approximate solution is derived and the stop band properties are presented. Numerical calculations show that the structural stiffness and negative proportional control of the piezoelectric spring can create a new stop band which is under the acoustic branch. But the positive proportional case has a different influence because of a critical wave number appearing. Moreover, the optic branch can be uplifted by the elastic wave amplitude. Different from the soft nonlinear characteristic, the hard nonlinear property can increase the stop band width.