Capillary electrophoretic studies on quantum dots and histidine appended peptides self‐assembly

Herein, we designed four peptides appended with different numbers of histidine (His_n‐peptide). We launched a systematic investigation on quantum dots (QDs) and His_n‐peptide self‐assembly in solution using fluorescence coupled CE (CE‐FL). The results indicated that CE‐FL was a powerful method to probe how ligands interaction on the surface of nanoparticles. The self‐assembly of QDs and peptide was determined by the numbers of histidine. We also observed that longer polyhistidine tags (n ≤ 6) could improve the self‐assembly efficiency. Furthermore, the formation and separation of QD‐peptide assembly were also studied by CE‐FL inside a capillary. The total time for the mixing, self‐assembly, separation, and detection was less than 10 min. Our method greatly expands the application of CE‐FL in QDs‐based biolabeling and bioanalysis.     

Periodic solution and its stability of a delayed Beddington‐DeAngelis type predator‐prey system with discontinuous control strategy

This paper investigates the periodic solution of a delayed Beddington‐DeAngelis (BD) type predator‐prey model with discontinuous control strategy. Firstly, the regularity and visibility analysis of the delayed predator‐prey model is carried out by using the principle of differential inclusion. Secondly, the positiveness and boundeness of the solution is discussed by employing the comparison theorem. Based on the boundary conditions of the model and the Mawhin‐like coincidence theorem, it is shown that the solution of the delayed BD system is asymptotically stable in finite time. Furthermore, it is found that there exists at least one periodic solution of the nonautonomous delayed predator‐prey model by using the principle of topological degree and set value mapping. Specially, when the nonautonomous delayed BD system degenerates into an autonomous system, some criteria are obtained to guarantee the convergence behavior of the harvesting solutions for the corresponding autonomous delayed BD system. Finally, numerical examples are given to demonstrate the applicability and effectiveness of main results. It is worthy to point out that the discontinuous control strategy is superior to the continuous harvesting policies adopted in existing literature.     

An improved quasi-zero stiffness isolator with two pairs of oblique springs to increase isolation frequency band

Nonlinear Dynamics - Quasi-zero stiffness (QZS) isolators can achieve superior performance in vibration isolation; however, this superiority is often effective only for an excitation with the small...     

Bifurcations and dynamics of a plant disease system under non-smooth control strategy

Nonlinear Dynamics - Mathematical models and analyses can assist in designing the control strategies to prevent the spread of infectious disease. The present paper investigates the bifurcations and...     

非线性振动系统动力学行为的实验研究

本文综述了非线性振动系统动力学行为的实验研究,详细叙述了机械模型实验,实验数据的分析与处理,并对今后发展趋势作了述评．      

两自由度非线性振动系统主参数激励下的分岔分析

本文给出了参数激励作用下两自由度非线性振动系统,在1:2内共振条件下主参数激励低阶模态的非线性响应.采用多尺度法得到其振幅和相位的调制方程,分析发现平凡解通过树枝分岔产生耦合模态解,采用Melnikov方法研究全局分岔行为,确定了产生Smale马蹄型混沌的参数值.     

Free-standing WS<Subscript>2</Subscript><Emphasis Type="Strikethrough">-</Emphasis>MWCNTs hybrid paper integrated with polyaniline for high-performance flexible supercapacitor

As two-dimensional layered nanomaterials, the tungsten disulfide (WS₂) nanosheets can be used as building blocks of paper-like electrodes for high-performance FSs. However, poor conductivity and mechanical property of WS₂ nanosheets (NSs) paper greatly hinders their capacitance and/or rate performance. To solve these problems, we fabricated the WS₂-multiwalled carbon nanotubes (MWCNTs)/polyaniline (PANI) composite papers based on liquid exfoliation and electrochemical deposition for high-performance flexible supercapacitors. The WS₂-MWCNTs/PANI with conductive PANI chains linked WS₂ NSs and MWCNTs takes the advantages of high-electronic double-layer capacitance originated from the internal surface areas of MWCNTs and effective pseudocapacitance generated by exfoliated WS₂ NSs and PANI. Electrochemical studies showed that the gravimetric-specific capacitance of WS₂-MWCNTs/PANI can reach ~760.1 F/g at a current density of 1 A/g. A symmetric flexible solid-state supercapacitor was also assembled and studied. The WS₂-MWCNTs/PANI-assembled FS device also has an excellent area specific capacitance of 1158.7 mF/cm² at a current density of 0.5 mA/cm² together with a high-capacity retention of ~82.5% after 2000 cycles.     

Magnetic M<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>O<Subscript><Emphasis Type="Italic">y</Emphasis></Subscript>@N-C as heterogeneous catalysts for the catalytic oxidation of aniline solution with sulfate radicals

Metal nanoparticles have been combined with magnet metal–organic frameworks (MOFs) to afford new materials that demonstrate an efficient catalytic degradation, high stability, and excellent reusability in areas of catalysis because of their exceptionally high surface areas and structural diversity. Magnetic M _x O _y @N-C (M = Fe, Co, Mn) nanocrystals were formed on nitrogen-doped carbon surface by using 8-hydroxyquinoline as a C/N precursor. The Co@N-C, MnO@N-C, and Fe/Fe₂O₃@N-C catalysts were characterized by X-ray diffraction (XRD), Raman, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), N₂ adsorption/desorption, and X-ray photoelectron spectroscopy (XPS). The catalytic performances of catalysts were thoroughly investigated in the oxidation of aniline solution based on sulfate radicals (SO₄ ^?.) toward Fenton-like reaction. Magnetic M _x O _y @N-C exhibits an unexpectedly high catalytic activity in the degradation of aniline in water. A high magnetic M _x O _y @N-C catalytic activity was observed after the evaluation by aniline degradation in water. Aniline degradation was found to follow the first-order kinetics, and as a result, various metals significantly affected the structures and performances of the catalysts, and their catalytic activity followed the order of Co > Mn > Fe. The nanoparticles displayed good magnetic separation under the magnetic field.

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Colorimetric sensor array–smartphone–remote server coupling system for rapid detection of saccharides in beverages

A kind of “colorimetric sensor array–smartphone–remote server” coupling system was constructed for rapid on-site testing of saccharides. First, the binding capacity between saccharides and boric acid compounds (boric acid, phenylboronic acid and 3-nitrophenylboronic acid) was studied. The binding capacity of 3-nitrophenylboronic acid was found to be the highest, followed by phenylboronic acid and boric acid. Then a small-scale colorimetric sensor array (2 × 2) of pH indicator based on affinity interaction between 3-nitrophenylboronic acid and saccharides was developed to detect 19 kinds of saccharides. A camera phone was used to acquire the array images before and after reaction, then the self-developed color discrimination software in smartphone was applied to process pictures in order to obtain the color difference image and data of analytes. The color difference data were analyzed by several methods, including principal component analysis, hierarchical cluster analysis and linear discriminant analysis. The analysis results showed that the sensor array (2 × 2) established in this paper has great discriminative capability for 19 kinds of saccharides, and the classification accuracy is as high as 100%. Nineteen different quantitative models of saccharides that showed high accuracy and precision were established based on partial least-square method. Finally, the smartphone was connected to a remote server on which the qualitative analysis and quantitative analysis models for analytes had been established. The color difference data obtained by the smartphone were uploaded to the remote server for the qualitative analysis and quantitative analysis of saccharides. The effectiveness of the “colorimetric sensor array–smartphone–remote server” coupling system in rapid on-site detection of saccharides was further verified by the spike and recovery experiments. The qualitative analysis results showed that this coupling system could distinguish all of the analytes without a mistake, and the quantitative analysis results showed that the predicted values for saccharides were close to the real values.     

In‐capillary self‐assembly study of quantum dots and protein using fluorescence coupled capillary electrophoresis

As a vast number of novel materials in particular inorganic nanoparticles have been invented and introduced to all aspects of life, public concerns about how they might affect our ecosystem and human life continue to arise. Such incertitude roots at a fundamental question of how inorganic nanoparticles self‐assemble with biomolecules in solution. Various techniques have been developed to probe the interaction between particles and biomolecules, but very few if any can provide advantages of both rapid and convenient. Herein, we report a systematic investigation on quantum dots (QDs) and protein self‐assembly inside a capillary. QDs and protein were injected to a capillary one after another. They were mixed inside the capillary when a high voltage was applied. Online separation and detection were then achieved. This new method can also be used to study the self‐assembly kinetics of QDs and protein using the Hill equation, the K_D value for the self‐assembly of QDs and protein was calculated to be 8.8 μM. The obtained results were compared with the previous out of‐capillary method and confirmed the effectiveness of the present method.