Robust fixed-time attitude stabilization control of flexible spacecraft with actuator uncertainty

Nonlinear Dynamics - A robust fixed-time control framework is presented to stabilize flexible spacecraft’s attitude system with external disturbance, uncertain parameters of inertia, and...     

Necessary and Sufficient Conditions for Weak Quasi Efficiency in Nonsmooth Multiobjective Problems

In this article, a multiobjective problem with a feasible set defined by inequality, equality and set constraints is considered, where the objective and constraint functions are locally Lipschitz. Several constraint qualifications are given and the relations between them are analyzed. We establish Kuhn-Tucker and strong Kuhn-Tucker necessary optimality conditions for (weak) quasi e?ciency in terms of the Clarke subdifferential. By using two new classes of generalized convex functions, su?cient conditions for local (weak) quasi e?cient are also provided. Furthermore, we study the Mond-Weir type dual problem and establish weak, strong and converse duality results.     

Regularity analysis of an individual-based ecosystem simulation

We analyze the results of a large simulation of an evolving ecosystem to evaluate its complexity. In particular, we are interested to know how close to a stochastic or a deterministic behavior our simulation is. Four methods have been used for this analysis: Higuchi fractal dimension, correlation dimension, largest Lyapunov exponent, and P&H method. Besides, we use a surrogate data test to reach a final decision about analysis. As we expect, our results show that there is a deterministic and chaotic behavior in ecosystem simulation.     

A study on the two binding sites of hexokinase on brain mitochondria

Background  

Type I hexokinase (HK-I) constitutes the predominant form of the enzyme in the brain, a major portion of which is associated with the outer mitochondrial membrane involving two sets of binding sites. In addition to the glucose-6-phosphate (G6P)-sensitive site (Type A), the enzyme is bound on a second set of sites (Type B) which are, while insensitive to G6P, totally releasable by use of high concentrations of chaotropic salts such as KSCN. Results obtained on release of HK-I from these "sites" suggested the possibility for the existence of distinct populations of the bound enzyme, differing in susceptibility to release by G6P.     

Nonsmooth multiobjective programming and constraint qualifications

We consider a nonsmooth multiobjective programming problem with inequality and set constraints. By using the notion of convexificator, we extend the Abadie constraint qualification, and derive the strong Kuhn-Tucker necessary optimality conditions. Some other constraint qualifications have been generalized and their interrelations are investigated.     

Interaction between silver nanoparticle and bovine hemoglobin at different temperatures

The binding of silver nanoparticles to bovine hemoglobin (BHb) was studied by fluorescence, UV–Visible, and circular dichroism (CD) spectroscopic techniques at different temperatures of 20, 37, and 42 °C. The absorption spectrum of soret band, in the presence of silver nanoparticle, showed a significant spectral change, which indicated the heme groups of BHb were directly attacked and degraded by silver nanoparticle. The fluorescence data explained that the nanoparticle binding to BHb occurred at a single binding site, which demonstrated a dynamic quenching procedure. Nanoparticles could reduce the fluorescence of tryptophanyl residues of BHb to a lesser extent. Circular dichroism studies demonstrated a conformational change of BHb in the presence of silver nanoparticles. The helicity of BHb was reduced by increasing silver nanoparticle concentration at different temperatures. Thermodynamic analysis of the protein interaction by silver nanoparticles suggested that the binding process is only entropy driven.     

Nonsmooth Multiobjective Problems and Generalized Vector Variational Inequalities Using Quasi-Efficiency

In this paper, a multiobjective problem with a feasible set defined by inequality, equality and set constraints is considered, where the objective and constraint functions are locally Lipschitz. Here, a generalized Stampacchia vector variational inequality is formulated as a tool to characterize quasi- or weak quasi-efficient points. By using two new classes of generalized convexity functions, under suitable constraint qualifications, the equivalence between Kuhn–Tucker vector critical points, solutions to the multiobjective problem and solutions to the generalized Stampacchia vector variational inequality in both weak and strong forms will be proved.     

Antibiotic enhanced dopamine polymerization for engineering antifouling and antimicrobial membranes

In this work,we adopt a new tobramycin(TOB)-dopamine coating system to endow thin film composite membranes with excellent antifouling and antimicrobial properties.Combining the hydrophilic and antibiofouling properties of both TOB and polydopamine,the TOB-dopamine modified membrane exhibits improved antifouling and antimicrobial properties compared with the conventional dopamine modified and unmodified membranes.The TOB-dopamine system has two advantages over the conventional modification with dopamine and tris buffer solution.First,TOB-dopamine modification is more efficient than the conventional dopamine modification due to the accelerating effect of TOB on dopamine polymerization.Second,the TOB-dopamine modified membranes exhibit better hydrophilicity,and enhanced antifouling and antimicrobial properties than the conventional dopamine modified membrane.Beyond engineering membranes,the proposed TOB-dopamine system can also be extended for wider surface hydrophilic and antimicrobial modifications.