Effects of resistive switching in Au/FeO<Subscript>x</Subscript>/Pt structures

The dynamics of forming and resistive switching in Au/iron oxide/Pt structures based on magnetite (Fe₃O₄) is investigated. It has been revealed that these processes have an electrochemical nature and are accompanied by formation of low-resistance conductive filaments formed by inclusions of magnetite in the matrix of high-resistance maghemite (γ-Fe₂O₃). It has been found that the electric field stimulates reversible redox reactions in iron oxide. The direction and rate of these reactions are determined by the polarity and the amplitude of voltage pulses. The possibility of setting the resistance of the structure by changing the amplitude of the “record” voltage pulses opens prospects for the development of multilevel memory elements.     

Various factors affecting heavy metal ion sorption from aqueous media by sorbent containing cellulose

The specific adsorption of heavy metal ions on hydrophilic monodentate biosorbent sites was studied. The solvation and coordination mechanism of cation distribution in heterophase system was suggested. Bivalent metal cation desorption mechanism affected by monovalent metal salts (NaCl) was represented in the form of cation-cation resolvation on monodentate sorbent sites, involving ion pairs of hydrated cations and counter ions (anions). The metal ion degree of extraction was found to decrease by 20%, when the solution/sorbent module increased from 75 to 1000. Heavy metal ion sorption by polysaccharide sorbent was identified as exothermic process. The estimated values of ΔH and ΔS enabled to consider sorption of metal cations on polysaccharide sorbent as specific reversible adsorption.     

Mechanisms of high-strain-rate deformation and fracture of fine-grained unalloyed uranium upon explosive loading

The study of the microstructure and properties of quasi-statically extruded fine-grained uranium before and after explosive loading has shown that the main mechanism of its high-strain-rate deformation is multiple twinning. The nucleation of spall and shear microdamages upon explosive loading occurs at oxycarbonitride inclusions, just as in the coarse-grained cast metal upon the analogous regime of explosive loading. The absence of an increase in the spall strength of uranium upon a decrease in the initial grain size by a factor of 100–250 is related to the presence of a significant amount of impurities (to 1.5 ± 0.2 vol %) in the material.     

Effect of Pasteurization and Retort Processing on Spectral Characteristics,Morphological, Thermal,Physico‐Mechanical,Barrier and Optical Properties of Nylon‐Based Food Packaging Materials

The effect of pasteurization and retort processing on spectral, morphological, thermal, physico‐mechanical, barrier and optical properties of three different packaging materials viz., PP/N6/PP, PET/N6/cPP and SiO_x‐PET/N6/cPP were studied. These packaging materials were packed with distilled water, which acted as a food simulant. Subsequently, these pouches were subjected to different thermal processing conditions such as pasteurization and retort processing. Both the processing techniques found to have retained the mechanical properties of all packaging materials. Water vapour transmission rate (WVTR) and oxygen transmission rate (OTR) of nylon‐based combinations were increased after processing. Gloss found to decrease invariably irrespective of the material and increases with the severity of the treatment. XRD diffractogram shows changes in crystal structure as a result of thermal processing, and SEM analysis shows the crystal fragmentation. Absorption of water by the amide group of nylon 6 was observed, which could be a reason for the increase in OTR and WVTR. Copyright © 2014 John Wiley & Sons, Ltd.     

Dynamic aging in an Fe–Ni–Al alloy upon megaplastic deformation. Effect of the temperature and deformation rate

The method of Mössbauer spectroscopy has been used to investigate the effect of the temperature and the rate of megaplastic deformation on the processes of dissolution–precipitation of intermetallic compounds in aging austenitic alloy with a composition of Fe–36Ni–9Al. It has been established that, upon deformation in revolving Bridgman anvils, in the temperature range of cryogenic temperatures (liquid nitrogen) up to 573 K, a change occurs in the character of phase transitions from atomic disordering and the dissolution of intermetallic compounds to their additional accelerated precipitation. The factor that affects the kinetics of the processes of dissolution–precipitation of intermetallic compounds in the metallic matrix is dynamic aging. Dynamic aging is activated with an increase in the temperature and a decrease in the deformation rate.     

Peculiarities of Sorption of Copper(II) Ions by Modified Wool Keratin

Protection of Metals and Physical Chemistry of Surfaces - The results of studying the equilibrium and kinetics of Cu2+ ions’ sorption from aqueous solutions by the initial and modified wool...     

Switches of High-power Current Pulses with a Submicrosecond Rise Time on the Basis of Series-connected IGBT Transistors

The results of comparative investigations of assemblies of series-connected IGBT transistors (IRGPS60B120KD) with control circuits that are based on pulse transformers and ADuM21N microcircuits, which have a high insulation strength, are presented. The conditions for efficient switching of high-power current pulses with a submicrosecond rise time are determined. A small switch with an operating voltage of 12 kV that consists of two parallel-connected transistor assemblies is described. It provides switching of microsecond current pulses with an amplitude of 500 A and a rise time of 200 ns at a frequency of 100 Hz under natural cooling. The possibility of scaling the results is shown.     

Effect of ytterbium on the properties of Magnico alloys

Conclusions The addition of 0.3% Yb to an alloy of the Magnico type alloyed with 0.9% Si, 0.5% Nb, and 0.2% Ti increases the maximum magnetic energy to 24 kJ/m³ and reduces the quantity of harmful impurities, which substantially improves the grindability of the alloy.Novocherkassk Scientific-Research Institute of Permanent Magnets. Translated from Metallovedeme i Termicheskaya Obrabotka Metallov, No. 7, pp. 49–50, July, 1976.     

Dramatic Effect of Vibrations on Dynamics of Rotating Hydrodynamic Systems

The results of theoretical and experimental investigation of the average dynamics of inhomogeneous systems in rotating cavity in the presence of oscillating force field are highlighted and analyzed. Average behavior of nonisothermal liquid as well as different multiphase systems (two liquids, liquid and gas, solid in liquid, granular matter in liquid) in quickly rotating horizontal cylinder subjected to vibrations of different direction is described. The specificity of dynamics of all the systems is determined by the Coriolis force which defines not only the average flows but the fluid oscillations also. The resonant excitation of inertial oscillations of liquid results in generation of intensive mean flows. The structure of vibrational streams is essentially determined by the type of inertial waves. So, excitation of an azimuthal wave generates azimuthal streams (outrunning or lagging, depending on frequency of the wave), three-dimensional standing waves (in the systems with deformable interface) generate regular spatial flows of high intensity. Under the resonant conditions the influence of vibrations appears to be very strong, the speed of mean streaming can achieve the values comparable with the speed of rotation of the container.     

Resonator tuning accuracy in an automatic frequency tuning system for a passive hydrogen frequency standard

An automatic tuning system for a cavity in a passive hydrogen frequency standard is considered, which uses the excitation signal with phase modulation. Numerical and experimental tests have shown that the performance of this system is dependent on the extent of spectrum distortion resulting from the signal and asymmetry of the resonance curve in the UHF cavity.