Time asymptotic behaviour for unbounded linear operator arising in growing cell populations

This paper is concerned with the spectral analysis of a class of unbounded, linear operators, originally proposed by M. Rotenberg (J. Theor. Biol. 96 (1982) 495; J. Theor. Biol. 103 (1983) 181). After a detailed spectral analysis it is shown that the associated Cauchy problem is governed by a C⁰-semigroup. Next, we discuss the irreducibility of the transport semigroup. In particular, we show that the transport semigroup is irreducible if the boundary operator is strictly positive. Finally, a spectral decomposition of the solutions into an asymptotic term and a transient one which will be estimated for smooth initial data is given.     

On a generalization of the Schauder and Krasnosel'skii fixed points theorems on Dunford–Pettis spaces and applications

In this paper, we give a generalization of the Schauder and Krasnosel'skii fixed point theorems in Dunford–Pettis spaces. Both of these theorems can be used to resolve some open problems posed by Jeribi (Nonlinear Anal.: Real World Appl. 2002; 3 :85–105); and Latrach (J. Math. Phys. 1996; 37 :1336–1348). Further, we applied our work to prove some existence results for a source problem with general boundary conditions in L₁ spaces. Copyright © 2005 John Wiley & Sons, Ltd.     

Investigation of controlled release properties and anticancer effect of folic acid conjugated magnetic core–shell nanoparticles as a dual responsive drug delivery system on A-549 and A-431 cancer cell lines

Research on Chemical Intermediates - Epirubicin loaded on magnetite-coated calcium ferrite conjugated folic acid (Fe3O4@CaFe2O4-FA@EPI) was synthesized and characterized using various techniques...     

Mobility modeling and analytical solution for spatial traffic distribution in wireless multimedia networks

In this paper, we propose a general mobility model suitable for wireless multimedia networks. Our model is based on splitting a region into subregions. Furthermore, we make an analogy between subregions as well as their inter-connections with a multi-class Jackson queueing network comprising of infinite-server nodes. The main attribute of such a network is due to its product-form stationary distribution. Using this model, we are able to obtain a closed analytical form for the spatial traffic distribution corresponding to a specific number of network-connected users with different classes of service and mobility in a typical region. Also, we show the flexibility obtained by the proposed mobility model in representing some general distributions such as sum-of-hyper-exponentials (SOHYP), hyper-Erlang and Cox which were previously suggested to model mobility-related statistical parameters, e.g., cell dwell time and channel holding time. Finally, we apply the proposed model to a few mobility scenarios and obtain the resultant active user's location density.     

Synthesis,Characterization, X‐ray Structures,and Solution Studies of Nickel(II) Complexes of an Aza‐Crown Macrocycle with a Hydroxyl Pendant‐Armed

The 18‐membered mixed‐donor macrocycle 6,7,8,9,10,11,12,13,20,21‐decahydro‐5H, 19H‐dibenzo[b,m][1,15,5,8,11]dioxatriazacyclooctadecin‐20‐ol ( L ), which contains N₃O₃ donor set, was synthesized. Also two nickel(II) complexes of L have been synthesized and characterized by X‐ray crystallography, FT‐IR, UV‐Vis absorption spectroscopy and elemental analysis. The structure of complexes shows an unexpected anion dependence. Reaction of Ni(ClO₄)₂·6H₂O with L afforded [Ni L ](ClO₄)₂·CH₂Cl₂ complex in which L uses all donor atoms and acts as a hexadentate ligand so forming a mononuclear nickel(II) complex in distorted octahedral geometry. Contrasting with this, when NiCl₂·6H₂0 is used, the product complex [{Ni L Cl}₂(μ‐Cl)₂] is dimeric and consists of two Ni L Cl units bridged by two chloride ions. The coordination geometry of each nickel atom is a distorted octahedral. In this complex L is exo‐coordinated via only three nitrogen atoms to a nickel ion, which is bound to two cis bridging chloride and one non‐bridging chloride too. Also complexing properties of L towards Ni(ClO₄)₂·6H₂O and NiCl₂·6H₂0 have been determined by UV‐Vis titration in methanol. The computer treatment of the data confirmed the 1:1 metal to ligand stoichiometry for two complexes in solution and gave reliable values for corresponding stability constants (logK = 3.00 ± 0.02 with Ni(ClO₄)₂·6H₂O and logK = 3.29 ± 0.06 with NiCl₂·6H₂0).     

Effect of temperature on the electrophysical properties of Si–polymer composite varistors

A low voltage Si–polymer composite varistor was prepared at a temperature of 130 °C and a pressure of 60 MPa and its current–voltage characteristic was studied. Also, temperature dependence of current–voltage characteristic was investigated in the temperature range of 25–100 °C. It was found that any increase in ambient temperature lowers breakdown voltage as well as nonlinearity coefficient. Each sample has hysteresis which decreases through increase in temperature. Annealing effect on leakage current, breakdown voltage and nonlinear coefficient was both investigated and analyzed using SEM micrographs and XRD patterns.     

Hybrid macromolecular antioxidants based on hydrophilic polymers and sterically hindered phenols

A novel class of biologically active substances was created. These are hybrid macromolecular antioxidants (HMAO) based on hydrophilic polymers with chemically grafted sterically hindered phenols with different structural parameters. The antiradical activities of HMAO were assessed in reactions with 2,2-diphenyl-1-picrylhydrazyl and the corresponding sodium sulfonate in various solvents. The mechanism that explains the substantially enhanced activities of HMAO in water was proposed. The state of HMAO in solutions was studied by viscosimetry and photon correlation spectroscopy. HMAO were assayed in biological models. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 751–760, April, 2007.     

Eigenwaves of a shielded two-side asymmetric strip line

We analyze the eitenwaves of a shielded two-side asymmetric strip line (STASL) by the method of almost complete operator inversion. Using this waveguide structure as an example, we developed an algorithm for reducing the order of systems of integral equations describing transmission lines with cross sections invariant with respect to rotation by 180°. Volga State Academy of Telecommunications and Information Science, Samara, Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 42, No. 10, pp. 950–957, October, 1999.     

Integrable and chaotic motions of four vortices

Conclusive numerical evidence of chaos in the four-vortex problem is presented using the method of Poincaré sections. The problem is formally reduced to a two degrees of freedom hamiltonian. The advection of a passive marker by three vortices displays chaos.