Different Types of Periodic Activities in a Calcium Oscillation Model

Abstract: In this paper, a model proposed by Marhl et al. is considered to investigate the effect of several parameters on the calcium bursting oscillation behavior. Different types of bursting are presented. Fast-slow burster analysis and first return map are used to explain the mechanism of the four types of bursting. The results are instructive for understanding the role of these parameters played in complex dynamics in the Marhl-Haberichter calcium oscillation model

Isopiestic measurements of water activities and thermodynamic modeling for CuCl2-MCl2-H2O (M = Mg, Ca) ternary system at t=298.15 K

Water activities of the CuCl2-MCl2-H2O (M= Mg, Ca) ternary systems and their sub-binary systems have been measured by the isopiestic method at 298.15K. The maximum concentrations of the CuCl2-H2O, MgCl2-H2O and CaCl2-H2O binary systems are 5.28 mohkg(-1), 5.25 mohkg -1 and 6.61 mol.kg(-1), respectively. The concentrations of mixture solution rang from 0.91 mol.kg(-1) to 5.69 mol.kg(-1) for CuCl2-MgCl2-H2O system, and 1.29 mol.kg(-1) to 6.87 mol,kg(-1) for CuCl2-CaCl2-H2O system. The measured water activities of the sub-binary systems are consistent with the experimental results reported in literature. The measured equal water activities in the ternary systems strongly deviate from the Zdanovskii-Stokes-Robinson (ZSR) lines. The Pitzer model, Pitzer-Simonson-Clegg (PSC) model and Reaction model were selected to correlate and predict the water activity obtained in this work and the solubility reported in literature for the CuCl2-MCl2-H2O (M = Mg, Ca) ternary systems at 298.15 K. It was found that, the Pitzer model and PSC model cannot consistently represent these thermodynamic properties, with the binary and mixing parameters that already reported or fitted in this work. However, the Reaction model, representing the different competition association ability of common-anions and water molecules with different cations, can successfully predictethe water activity and solubility isotherms in these ternary systems at 298.15 K with binary parameters only. Applying the Reaction model, some examples of the Cu-bearing species distribution as a function of MgCl2 (CaCl2) molalities are given and used to account for how the structure variation of a electrolyte solution influences its macroproperties. (C) 2020 Elsevier B.V. All rights reserved

Different Types of Periodic Activities in a Calcium Oscillation Model

In this paper, a model proposed by Marhl et al. is considered to investigate the effect of several parameters on the calcium bursting oscillation behavior. Different types of bursting are presented. Fast-slow burster analysis and first return map are used to explain the mechanism of the four types of bursting. The results are instructive for understanding the role of these parameters played in complex dynamics in the Marhl-Haberichter calcium oscillation model

Local kernel nonparametric discriminant analysis for adaptive extraction of complex structures

The linear discriminant analysis (LDA) is one of popular means for linear feature extraction. It usually performs well when the global data structure is consistent with the local data structure. Other frequently-used approaches of feature extraction usually require linear, independence, or large sample condition. However, in real world applications, these assumptions are not always satisfied or cannot be tested. In this paper, we introduce an adaptive method, local kernel nonparametric discriminant analysis (LKNDA), which integrates conventional discriminant analysis with nonparametric statistics. LKNDA is adept in identifying both complex nonlinear structures and the ad hoc rule. Six simulation cases demonstrate that LKNDA have both parametric and nonparametric algorithm advantages and higher classification accuracy. Quartic unilateral kernel function may provide better robustness of prediction than other functions. LKNDA gives an alternative solution for discriminant cases of complex nonlinear feature extraction or unknown feature extraction. At last, the application of LKNDA in the complex feature extraction of financial market activities is proposed

Extraction of rubidium ion from brine solutions by dicyclohexano-18-crown-6 / ionic liquid system

Separation among rubidium and potassium ions from salt lake brines remains challenging. In this work, a typical room temperature ionic liquid 1-ethyl-3-metyhlimidazaolium bis(trifluoromethylsulfonyl)imide ([C2mim+][NTf2-]) was used as diluent and synergistic extractant, dicyclohexano-18-crown-6 (DCH18C6) was used as extractant to extract rubidium ions from brine solutions which contain high concentrations of potassium ions was investigated. Under the optimal conditions, the single extraction efficiency of rubidium ions was up 93.63%. The thermodynamic parameters of the rubidium ion extraction were obtained. Based on the slope analysis method, the extracted species in the organic phase were ascertained as 1:1 complex. UV-visible has been performed to investigate the ion concentration of ionic liquid before and after the interaction of metal ions and ligands. Rubidium ions in [Rb · DCH18C6]+ complex were stripped by 2.5 mol · L–1 NH4NO3. The extraction system offers high efficiency, simplicity and environmentally friendly application prospect to separate rubidium from brine solutions

Tis, tis, tis wel mooi weer...

This paper is concerned with the problem of exponential stability for a class of stochastic neural networks with Markovian switching and mode-dependent interval time-varying delays. A novel Lyapunov-Krasovskii functional is introduced with the idea of delay-partitioning, and a new exponential stability criterion is derived based on the new functional and free-weighting matrix method. This new criterion proves to be less conservative than the most existing results. Numerical examples are presented to illustrate the effectiveness of the proposed method

Multidisciplinary Optimization and Analysis of Stratospheric Airships Powered by Solar Arrays

Stratospheric airships have much potential in military and commercial applications. Design, analysis and optimization of stratospheric airships involves complex trade-off of different disciplines, and hence a multidisciplinary approach is essential. This paper describes a methodology coupling several disciplines and involving seven design variables to obtain the optimal design of a stratospheric airship powered by solar arrays. A numerical method is established to calculate the output power of the solar array in the optimization process. The optimal solutions are obtained using hybrid algorithms. The methodology can obtain the optimal envelope shape, solar array layout and other general configurations of subsystems. Results show that the methodology was able to achieve a solution with a 19.2% reduction in airship volume compared to the value being part of an arbitrary initial set of airship parameters. In addition, a comparative study is carried out to highlight the importance of considerations of solar array layouts and array circumferential location. Furthermore, detailed sensitivity analysis shows that operating parameters of latitudes, heading angles and average resisting wind speeds have significant effects on the airship design and solar array layouts

Isopiestic Measurements on Aqueous Solutions of Heavy Metal Sulfates: MSO₄ + H₂O (M = Mn, Co, Ni, Cu, Zn). 2. <i>T</i> = 373.15 K

The water activities of the systems MSO₄ + H₂O (M = Mn, Co, Ni, Cu, Zn) are essential data needed for simulating the hydrometallurgical process of these metals. In our previous work (J. Chem. Eng. Data, 2014, 59, 97–102), the experimental data of water activity for these binary systems have been reported at 323.15 K. As one part of this series of work, the experimental data of water activity for these systems are reported at 373.15 K. The reliability of the apparatus at 373.15 K was verified by measuring and comparing the water activities of the two reference systems, CaCl₂ + H₂O and LiCl + H₂O. The results showed that the maximal relative deviation of the water activities between the reference systems was 0.054%. The water activities for the concerned five systems were found to be approximately the same at a certain salt molality below 1 M. The water activities of these systems decrease at a certain salt molality more than 1 M in the following sequence: <i>a</i>_MnSO₄ > <i>a</i>_CuSO₄(∼<i>a</i>_ZnSO₄) > <i>a</i>_CoSO₄(∼<i>a</i>_NiSO₄). Furthermore, the experiment data obtained in this work were compared with the model values reported in the literature