Sensitive fluorimetric method for the determination of aniline by using tetra-substituted amino aluminium phthalocyanine

This is the first report of the determination of aniline with tetra-substituted amino aluminium phthalocyanine (TAAlPc) by a fluorimetric method. In KBr-HCl solution, nitrite ion diazotizes TAAlPc, thus, the fluorescence of TAAlPc is dramatically quenched. However, there is less quenching in the presence of aniline and the recovery in fluorescence intensity is linear with the concentration of aniline. Based on this, a novel method has been developed for the determination of aniline in aqueous solutions. Under the optimal conditions, the calibration graph for aniline is from 5 to 300 ng ml⁻¹ with a 3σ limit of detection of 1.8 ng ml⁻¹. The relative standard deviation for nine replicate measurements of 100 ng ml⁻¹ aniline is 1.7%. The method was applied to the analysis of water samples with satisfactory results.     

Folic acid-based supramolecules for enhanced stability in potassium ion batteries

Organics present significant prospects as environmentally friendly and sustainable electrode materials for potassium ion batteries(PIBs) because of their abundant, recyclable and highly customizable characteristics. However, small molecular organics are easily solubilized in organic electrolytes, resulting in a low capacity and poor stability. Herein, the folic acid-based supermolecules(SM-FAs) are successfully prepared by a hydrothermal assisted self-assembly strategy. Due to multi-locus hydrog...     

Bifurcation and chaos of Tessiet type food chain chemostat with periodically varying substrate

In this paper, we introduce and study a model of Tessiet type food chain chemostat with periodically varying substrate. We investigate the subsystem with substrate and prey and study the stability of the periodic solutions, which are the boundary periodic solutions of the system. The stability analysis of the boundary periodic solution yields an invasion threshold. By use of standard techniques of bifurcation theory, we prove that above this threshold there are periodic oscillations in substrate, prey and predator. Furthermore, we numerically simulate a model with sinusoidal dilution rate, by comparing bifurcation diagrams with different bifurcation parameters, we can see that the periodic system shows two kinds of bifurcations, whose are period-doubling and period-halving.     

A voltammetric sensor for simultaneous determination of lead,cadmium and zinc on an activated carbon fiber rod

A simple, low cost and sensitive voltammetric sensor was developed for the simultaneous detection of Pb²⁺, Cd²⁺, and Zn²⁺ based on a disposable carbon fiber rod (CFR). The important factors to enhance the sensing property were creation of a clean surface by dealing with CFR at a high potential and electrochemical deposition of Bi film to improve the accumulation of heavy metal ions.     

Cyclopiane-type diterpenes from the deep-sea-derived fungus Penicillium commune MCCC 3A00940

Three new cyclopiane diterpenes (1–3) and one rare spirocyclolide (5) were isolated from the deep-sea-derived fungus Penicillium commune MCCC 3A00940, along with 11 known compounds. The planar structures of the new compounds were determined by extensive analysis of their NMR and HRESIMS spectra, and the absolute configurations were established on the basis of specific rotation data in association with calculated ECD spectra. Four of the cyclopiane diterpenes (1–4), with a rigid 6/5/5/5 fused tetracyclic ring framework, are rarely found in Nature. Notably, conidiogenone J (1) is the first naturally occurring enantiomer of the cyclopiane diterpenes. Additionally, penijanthine B (6) and 3-hydroxy-5-methoxystilbene (14) exhibited moderate antiallergic effects with IC₅₀ values of 30 and 33?μM, respectively.     

A note on the critical ideals of a cycle

Critical ideals of a graph G which are the determinantal ideals of its generalized Laplacian matrix were first introduced by Corrales and Valencia as a generalization of the critical group. Then it was shown that critical ideals are also closely related to other properties of the graph, such as the clique number and the zero forcing number. In this note, we give a simple proof of Theorem 4.13 proved in [7], which gives a Gröbner basis of the first nontrivial critical ideal of a cycle. After that as applications we determine explicit expressions for the characteristic ideals of a cycle and the critical groups of a family of thick wheels.     

Global Dynamics of a Diffusive Leslie-Gower Predator-prey Model with Fear Effect

A diffusive Leslie-Gower predator-prey model with fear effect is considered in this paper. For the kinetic system, we show that the unique positive equilibrium is globally asymptotically stable. Moreover, we find that high levels of fear could decrease the population densities of both prey and predator in a long time. For the diffusive model, we obtain the similar results under certain conditions.     

大鼠肾脏汞结合金属硫蛋白的联用技术表征研究

通过凝胶色谱(SEC)及反相液相色谱(RPC)分别与电感耦合等离子体质谱(ICP-MS)和电喷雾电离质谱(ESI-MS)联用的技术，对灌喂HgCl₂大鼠的肾组织中诱导的多金属结合金属硫蛋白(MT)的结构进行表征分析。通过SEC-ICP-MS曲线上的金属信号及紫外检测的MT光谱吸收特征，可确认组织提取液中MT在色谱曲线上的位置。与对照组相比，灌喂HgCl₂大鼠肾中Hg-MT的诱导量显著增加，与此同时，Cu-MT在染毒组的诱导量也相应增加，说明MT在染汞大鼠肾脏中起着对汞的解毒和对铜的调节作用。MT样品提取物经葡聚糖凝胶(G-75)柱分离纯化并用透析法脱盐后，用细内径反相色谱柱分离，进行梯度洗脱，并与ESI-MS联用，可获得总离子流色谱图及与色谱峰对应的质谱图，通过对质谱信号的解析及参考脱金属MT构型的有关报道，对汞诱导大鼠肾组织MT的不同亚型和次亚型分子结构进行推断。结果证明，在灌喂HgCl₂大鼠的肾组织中存在着一系列汞结合的MT形态。     

Improving effect of oleic acid-mediated sodium caseinate-based encapsulation in an ultrasound field on the thermal stability and bioaccessibility of quercetin

The simultaneous improvement of quercetin (QUE) processing stability and bioavailability has always presented a technical challenge during food processing. This study constructed a water-soluble carrier consisting of oleic acid (OA) and sodium caseinate (NaCas) in an ultrasonic field and investigated the effect of its encapsulation on improving the thermal stability and bioaccessibility of QUE. The results showed that the OA and NaCas generated uniform, stable water-soluble particles with a poly dispersity index (PDI) below 0.3 and an absolute value of Zeta potential above 30 mV in optimized conditions (a protein concentration of 4 mg/mL, ultrasonic power of 300 W, and ultrasonic time of 5 min). OA-NaCas mass ratio of 1:40, 1:15, 1:8, and 1:4 was selected for QUE loading to compare its encapsulation effect at different mass ratios. Compared with the NaCas without OA, the QUE embedding rate reached 95 % at OA-NaCas mass ratios of 1:15 and 1:8. In addition, the transmission electron microscopy (TEM) images confirmed that QUE was embedded in OA-NaCas particles, forming regular, spherical OA-NaCas-QUE particles at mass ratios or 1:15 and 1:8. Next, when heated at 80 °C for 120 min, the OA-NaCas (OA:NaCas, 1:15, 1:8, and W/W) particles significantly improved the QUE retention rate. The simulated in vitro gastrointestinal digestion experiments showed that the QUE bioaccessibility increased from 25 % to more than 60 % when it was encapsulated in OA-NaCas (OA:NaCas, 1:15, 1:8, and W/W) particles. These results indicated that the OA-NaCas complex was suitable as a hydrophilic delivery carrier of fat-soluble polyphenols.     

Numerical techniques for simulating a fractional mathematical model of epidermal wound healing

A number of mathematical models investigating certain aspects of the complicated process of wound healing are reported in the literature in recent years. However, effective numerical methods and supporting error analysis for the fractional equations which describe the process of wound healing are still limited. In this paper, we consider the numerical simulation of a fractional mathematical model of epidermal wound healing (FMM-EWH), which is based on the coupled advection-diffusion equations for cell and chemical concentration in a polar coordinate system. The space fractional derivatives are defined in the Left and Right Riemann-Liouville sense. Fractional orders in the advection and diffusion terms belong to the intervals (0,1) or (1,2], respectively. Some numerical techniques will be used. Firstly, the coupled advection-diffusion equations are decoupled to a single space fractional advection-diffusion equation in a polar coordinate system. Secondly, we propose a new implicit difference method for simulating this equation by using the equivalent of Riemann-Liouville and Grünwald-Letnikov fractional derivative definitions. Thirdly, its stability and convergence are discussed, respectively. Finally, some numerical results are given to demonstrate the theoretical analysis.