Theoretical description of metabolism using queueing theory

A theoretical description of the process of metabolism has been developed on the basis of the Pachinkomodel (seeNicholson andWilson in Nat Rev Drug Discov 2:668–676, 2003) and the queueing theory. The suggested approach relies on the probabilistic nature of the metabolic events and the Poisson distribution of the incoming flowof substratemolecules.The main focus of thework is an output flowofmetabolites or the effectiveness of metabolism process. Two simplest models have been analyzed: short- and long-living complexes of the source molecules with a metabolizing point (Hole) without queuing. It has been concluded that the approach based on queueing theory enables a very broad range of metabolic events to be described theoretically from a single probabilistic point of vie

Double Entropic Stochastic Resonance

We demonstrate the appearance of a purely entropic stochastic resonance (ESR) occurring in a geometrically confined system, where the irregular boundaries cause entropic barriers. The interplay between a periodic input signal, a constant bias and intrinsic thermal noise leads to a resonant ESR-phenomenon in which feeble signals become amplified. This new phenomenon is characterized by the presence of two peaks in the spectral amplification at corresponding optimal values of the noise strength. The main peak is associated with the manifest stochastic resonance synchronization mechanism involving the inter-well noise-activated dynamics while a second peak relates to a regime of optimal sensitivity for intra-well dynamics. The nature of ESR, occurring when the origin of the barrier is entropic rather than energetic, offers new perspectives for novel investigations and potential applications. ESR by itself presents yet another case where one constructively can harvest noise in driven nonequilibrium systems.Comment: 6 pages, 7 figures ; Europhys. Lett., in press (2009

Antibacterial properties of PMMA functionalized with CuFe2O4/Cu2O/CuO nanoparticles

We have prepared a composite thin coating by incorporation of CuFe2O4/Cu2O/CuO nanoparticles in polymethyl methacrylate (PMMA) matrix by using the solution casting method. The electrical explosion of two twisted wires (EETW) was used to obtain multicomponent CuFe2O4/Cu2O/CuO nanoparticles with an average particle size of 20–70 nm. The microscopic studies showed that the nanoparticles in the composite coatings are evenly distributed. However, nanoparticles are strongly agglomerated as the powder concentration in the coating increases to 5 wt.% and 10 wt.%, as the size of particle agglomerates increases to 50 and 100 µm, respectively. Therefore, nanoparticles were pre-treated with ultrasound when introduced into the PMMA matrix. The thermal stability of the composite coating does not change with the introduction of CuFe2O4/Cu2O/CuO nanoparticles in the amount of 5 wt.%. The inclusion of nanoparticles in the PMMA matrix significantly enhances its antibacterial activity. The addition of 5 wt.% nanoparticles inhibited the growth of E. coli by 100% and the growth of MRSA by 99.94% compared to pure PMMA already after 3 h of exposure of bacteria on the surface of the composites. This research provides an easy-to-manufacture and cost-efficient method for producing a uFe2O4/Cu2O/CuO/PMMA composite coating with a broad application as an antibacterial material

Dimerization energetics of DNA minor groove binders

The energy analysis of a dimerization in aqueous solutions of seven biologically active lexitropsins, which are different by structure, was carried out with the use of the molecular simulation method. The main stabilization of dimers was shown to take place owing to hydrophobic and intermolecular van der Waals interactions. The latter are mainly associated with energyfavorable contacts between the aromatic rings of molecules and their peptide groups. Despite the significant dipole moments of the molecules concerned, the electrostatic interactions are relatively weak and destabilize the complexes because of the unfavorable relative arrangement of molecular dipoles. Entropic factors and the dehydration were shown to also hinder the dimerizatio

Complex of C₆₀ fullerene with doxorubicin as a promising agent in antitumor therapy

The main aim of this work was to evaluate the effect of doxorubicin in complex with C₆₀ fullerene (C₆₀ + Dox) on the growth and metastasis of Lewis lung carcinoma in mice and to perform a primary screening of the potential mechanisms of C₆₀ + Dox complex actio

Complex of C₆₀ fullerene with doxorubicin as a promising agent in antitumor therapy

The main aim of this work was to evaluate the effect of doxorubicin in complex with C₆₀ fullerene (C₆₀ + Dox) on the growth and metastasis of Lewis lung carcinoma in mice and to perform a primary screening of the potential mechanisms of C₆₀ + Dox complex actio

Study of Thermal Stability of Li-ion Batteries

В настоящее время вейпинг создает новую субкультуру. Употребление электронных сигарет связано с риском их самовоспламенения и взрыва. На примере Li-ионных батарей марки «Орбита» определены их температуры разложения и самовоспламенения.Currently, vaping creates a new subculture. The use of electronic cigarettes is associated with the risk of self-ignition and explosion. On the example of Li-ion batteries of the “Orbit” brand, their decomposition and auto-ignition temperatures are determined

Energy fluctuations in a biharmonically driven nonlinear system

We study the fluctuations of work done and dissipated heat of a Brownian particle in a symmetric double well system. The system is driven by two periodic input signals that rock the potential simultaneously. Confinement in one preferred well can be achieved by modulating the relative phase between the drives. We show that in the presence of pumping the stochastic resonance signal is enhanced when analyzed in terms of the average work done on the system per cycle. This is in contrast to the case when pumping is achieved by applying an external static bias, which degrades resonance. We analyze the nature of work and heat fluctuations and show that the steady state fluctuation theorem holds in this system.Comment: 13 pages, 14 figures, revised manuscrip