新型功能碳材料的高压截获

高性能功能材料在诸多领域具有广泛的应用前景,是人们一直关注的研究热点。高压可以有效地改变物质的原子间距和成键方式,是获得新型功能材料的重要途径。在碳材料的高压研究中,许多有趣的功能碳材料,如光学透明碳、高强度弹性碳和超硬非晶碳等,已经通过不同的碳前驱体合成。本文简要介绍了作者近年来在低维碳基纳米复合材料高压研究中取得的进展,基于设计的不同低维碳前驱体,高压下截获了具有超硬特性、新型压致共价聚合及发光增强的碳材料。     

Fluorescent macrocyclic chemosensor for Zn(II) detection at alkaline pH values

ABSTRACT

The new macrocyclic ligand L (28,29-dimethoxy-27-oxa-8,11,14,17,25,26-hexaazatetracyclo[22.2.1.1(2,6).1(19,23)]nonacosa-2,4,6(28),19,21,23(29),24,26(1)-octaene) has been synthesised. It contains a tetramine chain and the 2,5-bis(2-methoxy-3-metyl-phenyl)-1,3,4-oxadiazole (PPD-OMe) chromophore, acting as coordinating and sensing units, respectively.

The fluorescent emission of L depends on the pH being highly fluorescent at pH = 2 and not emitting from pH >10. The studies highlighted that L is a PET mediated emitting chemosensor, being the PET effect regulated by the degree of the tetraamine protonation.

L coordinates metal ions (Cu(II), Zn(II) and Cd(II)) in water giving rise to an OFF-ON fluorescent response for the presence of Zn(II) ion thus signalling its presence in the medium. This response is particularly notable at pH = 9 allowing to extend the Zn(II) sensing also in the alkaline pH field.     

Tween 20-stabilized gold nanoparticles combined with adenosine triphosphate-BODIPY conjugates for the fluorescence detection of adenosine with more than 1000-fold selectivity

This study describes the development of a simple, enzyme-free, label-free, sensitive, and selective system for detecting adenosine based on the use of Tween 20-stabilized gold nanoparticles (Tween 20-AuNPs) as an efficient fluorescence quencher for boron dipyrromethene-conjugated adenosine 5′-triphosphate (BODIPY-ATP) and as a recognition element for adenosine. BODIPY-ATP can interact with Tween 20-AuNPs through the coordination between the adenine group of BODIPY-ATP and Au atoms on the NP surface, thereby causing the fluorescence quenching of BODIPY-ATP through the nanometal surface energy transfer (NSET) effect. When adenosine attaches to the NP surface, the attached adenosine exhibits additional electrostatic attraction to BODIPY-ATP. As a result, the presence of adenosine enhances the efficiency of AuNPs in fluorescence quenching of BODIPY-ATP. The AuNP-induced fluorescence quenching of BODIPY-ATP progressively increased with an increase in the concentration of adenosine; the detection limit at a signal-to-noise ratio of 3 for adenosine was determined to be 60 nM. The selectivity of the proposed system was more than 1000-fold for adenosine over any adenosine analogs and other nucleotides. The proposed system combined with a phenylboronic acid-containing column was successfully applied to the determination of adenosine in urine.     

Fabrication and luminescent properties of Eu(BMPPA)3BPy complex and its functionalized silica nanocomposites

Luminescent silica nanocomposites functionalized with a Eu-complex have been prepared and characterized.The europium complex is composed of 2,2'-bipyridyl(BPy) and 2-(4-bromomethyI)-phenylpropionic acid(BMPPA),which contains highly active benzyl bromide substituents and can covalently bind with poly(4-vinylpyridine)(P4VP)-modified silica nanoparticles(nanoSiO_2P4VP) to form nanoSiO_2P4VPEuBPy composites.Microscopic images revealed that the nanoSiO_2P4VPEuBPy composites easily formed aggregates,due to an inter-particle binding caused by the benzyl bromide among the composites.The as-prepared nanocomposites showed the typical emissions of Eu(III) ions at the wavelengths from 580 nm to 750 nm designated to the ~5D_0→~7F_n transitions.Time-resolved fluorescence decay measurements revealed that the emission lifetime was approximately 0.204 ms and 0.576 ms for the nanoSiO_2EuBPy composites,a little shorter than that in the Eu(BMPPA)_3BPy complex.     

Single‐Atom Gold Catalysis in the Context of Developments in Parahydrogen‐Induced Polarization

A highly isolated monoatomic gold catalyst, with single gold atoms dispersed on multiwalled carbon nanotubes (MWCNTs), has been synthesized, characterized, and tested in heterogeneous hydrogenation of 1,3‐butadiene and 1‐butyne with parahydrogen to maximize the polarization level and the contribution of the pairwise hydrogen addition route. The Au/MWCNTs catalyst was found to be active and efficient in pairwise hydrogen addition and the estimated contributions from the pairwise hydrogen addition route are at least an order of magnitude higher than those for supported metal nanoparticle catalysts. Therefore, the use of the highly isolated monoatomic catalysts is very promising for production of hyperpolarized fluids that can be used for the significant enhancement of NMR signals. A mechanism of 1,3‐butadiene hydrogenation with parahydrogen over the highly isolated monoatomic Au/MWCNTs catalyst is also proposed.     

Determination of cobalt ion based on polyethyleneimine modified silver nanoclustersEI北大核心CSCD

PolyethyleneiminePEImodified silver nanoclustersAg NCswere synthesized through chemical reduction method by using PEI as stabilizerAgNO3 as silve source and ascorbic acid as reducing agentand it was applied to the detection of cobalt ions. It was found that the fluorescence of the silver nanoclusters was quenched by Co2+ for the aggregation of PEI-Ag NCs caused by the coordination between cobalt ion and amino group on polyethyleneimine. Under the optimized experimental conditionsthe fluorescence quenching degree of PEI-Ag NCs was piecewise linear with the concentration of cobalt ion in the range of 8.30×10-7-4.17×10-4 mol/L and the detection limit was 0.41 μµmol/L. © 2022, Youke Publishing Co.,Ltd. All rights reserved.     

基于Retinex理论与概率非局部均值的红外图像增强方法

针对传统红外图像增强算法中细节模糊及过度增强的问题,提出了一种基于Retinex理论与概率非局部均值相结合的红外图像增强方法.首先通过单尺度Retinex方法调整图像中过暗与过亮部分的灰度级;然后利用概率非局部均值对图像进行分解处理得到基本层与细节层,对基本层采用直方图均衡化拉伸对比度,对细节层采用非线性函数进行增强;最后,将不同层次的结果融合得到对比度与细节增强的红外图像.用该方法对多组不同场景的红外图像进行仿真实验,并将其与多种增强方法进行主、客观对比分析,结果表明所提方法在红外图像的细节及对比度增强方面都获得了更好的效果.     

Bio-safety assessment of carbon quantum dots,N-doped and folic acid modified carbon quantum dots: A systemic comparison

The carbon quantum dots(CQDs) and their functionalized materials are promising in biomedical field because of their unique properties;meanwhile,a growing concern has been raised about the potential toxicity of these modified materials in biosystem.In this study,we synthesized original CQDs and two common functionalized CQDs including N-doped CQDs(NCQDs) and folic acid-modified CQDs(FACQDs),and compared the toxicity and biocompatibility with each other in vitro and in vivo.L929,C6 and normal cell MDCK were selected to detect the adverse reaction of these materials in vitro.No acute toxicity or obvious changes were noted from in vitro cytotoxicity studies with the dose of these CQD materials increasing to a high concentration at 1 mg/mL.Among these materials,the FA-CQDs show a much lower toxicity.Moreover,in vivo toxicity studies were performed on the nude mice for 15 days.The experimental animals in 10 or 15 mg/kg groups were similar with animals treated by phosphate buffer solution(PBS) after 15 days.The results of the multifa rious biochemical parameters also suggest that the functionalized products of CQDs do not influence the biological indicators at feasible concentration.Our findings in vitro and in vivo through toxicity tests demonstrate that CQDs and their modified materials are safe for future biological applications.     

基于色彩衰减补偿和Retinex的水下图像增强

针对水下图像存在的色偏、雾状模糊、低曝光和非均匀光照问题, 提出一种基于色彩衰减补偿和Retinex的水下图像增强算法. 首先, 为校正水下图像的色偏, 利用水体对不同波长光线衰减不一致的特性自适应地补偿其R、G、B通道. 然后, 使用基于多尺度导向滤波的Retinex去除雾状模糊, 增强对比度. 最后, 根据水下图像和自然图像的直方图分布特征对其进行归一化处理, 从而在保存图像主要信息的前提下增强其纹理和曝光. 实验结果表明, 该算法不但具有较优的视觉感知效果, 而且具有较高的图像质量评价分数. 该算法具有较强的适应性, 有助于计算机视觉算法在水下的应用.