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The breakthrough in electronics and information technology is anticipated by the development of emerging memory and logic devices, artificial neural networks and brain-inspired systems on the basis of memristive nano-materials represented, in a particular case, by a simple 'metal-insulator-metal' (MIM) thin-film structure. The present article is focused on the comparative analysis of MIM devices based on oxides with dominating ionic (ZrOx, HfOx) and covalent (SiOx, GeOx) bonding of various composition and geometry deposited by magnetron sputtering. The studied memristive devices demonstrate reproducible change in their resistance (resistive switching - RS) originated from the formation and rupture of conductive pathways (filaments) in oxide films due to the electric-field-driven migration of oxygen vacancies and/or mobile oxygen ions. It is shown that, for both ionic and covalent oxides under study, the RS behaviour depends only weakly on the oxide film composition and thickness, device geometry (down to a device size of about 20x20 mu m(2)). The devices under study are found to be tolerant to ion irradiation that reproduces the effect of extreme fluences of high-energy protons and fast neutrons. This common behaviour of RS is explained by the localized nature of the redox processes in a nanoscale switching oxide volume. Adaptive (synaptic) change of resistive states of memristive devices is demonstrated under the action of single or repeated electrical pulses, as well as in a simple model of coupled (synchronized) neuron-like generators. It is concluded that the noise-induced phenomena cannot be neglected in the consideration of a memristive device as a nonlinear system. The dynamic response of a memristive device to periodic signals of complex waveform can be predicted and tailored from the viewpoint of stochastic resonance concept. (C) 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinhei

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The Au containing nanocomposites were synthesized by UV irradiation followed by the thermal treatment of chitosan oligomer solutions doped by HAuCl 4 . The size of the formed gold nanoparti cles depends on the concentration of the dopant, which is proved by UV-Vis absorption spectrosco py and small angle X ray scattering (SAXS). The antioxidant activity of the gold nanoparticles with respect to hydroxy radicals significantly depends on the specific surface of the particles, which was found using the secondary radical spin trapping technique. The change in the • OH radical concen tration was monitored by the intensity of the ESR signal of the adduct of the spin trap (α phenyl N tert butylnitrone) with the Me • radicals formed in the reaction of • OH with DMSO.It is known 1 that gold nanoparticles exhibit high cata lytic activity in some oxidation reactions, such as low temperature CO oxidation, whereas gold as a compact metal is chemically inactive because of both the size effect and the character of interaction of the metal nano particles and support accompanied by the charge transfer between them. A change in the magnetic properties of metals in the nanosized state is of special interest. Previ ously 2 the superparamagnetic behavior of the palladium and gold nanoparticles incorporated into the polymer matrix of polyvinylpyrrolidone has been revealed, al though palladium is weakly paramagnetic and gold in the block state is a typical diamagnetic. Ferromagnetism (ferromagnetic spin polarization) of the gold nanoparticles was experimentally confirmed. 3 Similar changes in the pro perties of the metal on going to the nanosized state can be due to the dependence of the electronic structure on the particle size. The theoretical substantiation of the specif ic features of the electron states of the Au nanoparticles and the calculations proving the dependences of the Fermi energy on the particle size have been presented earlier. 4,5The interaction of the gold nanoparticles and the Au 3 and Au 13 clusters with organic radicals in alkanethiol hybrid systems was theoretically simulated. 4 Some pub lications concern the antioxidation effect of the gold nano particles stabilized by solutions of high molecular weight chitosan 6 and dendrimers 7 with respect to hydroxy radi cals. However, when studying these nanocomposites, a possible decrease in the hydroxy radical concentration due to intense chitosan destruction by hydrogen peroxide via the radical mechanism was ignored. 8,9 To exclude this effect, oligosaccharide of chitosan was used instead of the high molecular weight chitosan itself to stabilize the nanoparticles. Our preliminary experiments showed that the oligomer used underwent no changes under the experimental conditions.The purpose of this work is the ESR spectral study of the antioxidant properties of the gold nanoparticles in oligochitosan solutions depending on the particle size. ExperimentalThe gold nanocomposites were obtained in aqueous solutions of the chitosan oligomer doped by chloroauric acid (HAuCl 4 ) w...