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This work addresses the use of a sputtering technique for fabricating the top contacts to conventional sandwich-type ITO\phthalocyanine\Al cells. Current-vs-voltage characteristics of these cells measured both in dark and under illumination are compared with those of identical cells, but bearing a thermally evaporated Al cathode. The greatly improved efficiency is revealed in the former case: in particular, the fill factor increased by a factor of three. [ABSTRACT FROM AUTHOR]

A filamentous virus isolated from a sugar-beet plant showing systemic mosaic collected in South Kazakhstan was identified as an isolate of beet mosaic virus (BMV-K). BMV-K was transmitted by the green peach aphid Myzus persicae in a non-persistent manner, and by sap inoculation to 11 out of 19 species from seven families tested. The virus could not be transmitted to Nicotina tabacum, N. debneyi, N. glutinosa and N. clevelandii, either mechanically or with M. persicae. The thermal inactivation point of BMV-K in sugar-beet sap was 55–60 C, dilution end point 1:1000 and longevity in vitro 2 days at 20 C. A purification procedure produced 1.5–3 mg of purified virus from 100 g of infected Stellaria media plants. Purified virus contained a single protein species of molecular weight 34 700 Da. In ELISA tests. BMV-K reacted positively with BMV-specific antisera obtained from Japan. Germany and Portugal. By competitive DAS-ELISA, the virus isolate was shown to be closely serologically related to all the three isolates of BMV, and very distantly related to bean yellow mosaic and soybean mosaic viruses. [ABSTRACT FROM AUTHOR]

A purification procedure, which yielded up to 15—30 mg of beet yellows virus (BYV) per 100 g of infected Tetragonia expansa leaves, has been developed. The procedure included sap clarification with Triton X-100, and two cycles of ultracentrifugation through sucrose cushion, which contained PEG-6000 and NaCl. A specific antiserum was prepared, and BYV infection was successfully detected by the double-antibody sandwich (DAS) ELISA in infected sugar beet leaves and roots diluted up to 1 X 105 and 1 X 104, respectively. The virus concentration was demonstrated to decrease in infected sugar beet roots slowly during 7 months, thus allowing successful diagnosis of planting material in winter storage. BYV presence in Myzus persicae aphids was also reliably detectable using the DAS- ELISA. In a competitive DAS-ELISA test, the Ukraine and the British BYV isolates were found serologically indistinguishable. [ABSTRACT FROM AUTHOR]

A new type of a reference spherical wave source (SWS) based on a single mode optical fiber with a narrowed down up to the submicrometer size exit aperture is proposed. It is intended for the precision point diffraction interferometers as a source of a reference wave. Systematic experimental errors which influence the measurement accuracy of the quality of the wave fronts generated by the SWSs are considered. Experimental data on wave front deformations are given. The combined root-mean-square (rms) wave deformation for a couple of the SWSs measured in a numerical aperture of NA=0.27 reaches the value of rms=0.36 nm that corresponds to rms=0.25 nm of a single SWS or about λ/2500 for the red He–Ne laser. [ABSTRACT FROM AUTHOR]

Inspection of the condition of the foundations of buildings and structures erected and occupied in the cryolithic zone (Noril'sk, Dudinka) has exposed laws governing strength reduction and failure of the concretes placed in the foundations. Recommendations are presented for the failsafe service of buildings and for the protection of foundations from frost damage during reconstruction. [ABSTRACT FROM AUTHOR]

Nanostructured Co films were prepared on the top of a polymethyl methacrylate (PMMA) colloidal crystals by magnetron sputtering. Optical reflectance spectra were studied in the range of near UV, IR, and visible light for p- and s-polarizations. Valleys were observed in the spectra and their positions scaled with the PMMA sphere diameter. Both the surface plasmon resonance and the dipole resonance of single Co nanocaps should be considered to explain the obtained results. Magneto-optic measurements showed the qualitative change of the magnetization curve and the enhancement of magneto-optic rotation at wavelength λ=632 nm in comparison with the control Co film. [ABSTRACT FROM AUTHOR]

The possibility of electrical control of the interlayer exchange interaction in CoFeB/MgO/CoFeB tunnel junctions exhibiting magnetoresistance of ~200% is studied. It is shown that the increase in the applied voltage from 50 mV to 1.25 V leads to a shift of the magnetization curve of the free layer by 10 Oe at a current density of ~103 A/cm2. The discovered effect can be used in the development of energy-efficient random access memory. [ABSTRACT FROM AUTHOR]

We have used magnetic force microscopy (MFM) to investigate noncollinear helical states in multilayer nanomagnets, consisting of a stack of single domain ferromagnetic disks separated by insulating nonmagnetic spacers. The nanomagnets were fabricated from a [Co/Si]×3 multilayer thin film structure by electron beam lithography and ion beam etching. The structural parameters (Co layer and spacer thicknesses) were optimized to obtain a clear spiral signature in the MFM contrast, taking into account the magnetostatic interaction between the layers. MFM contrast corresponding to the helical states with different helicities was observed for the optimized structure with Co layer thicknesses of 16, 11, and 8 nm, and with 3 nm Si spacer thickness. [ABSTRACT FROM AUTHOR]

We have developed technology for manufacturing chains of CoFe/Al2O3/NiFe tunnel magnetoresistive (TMR) elements with pinning on the IrMn antiferromagnetic layer. We have studied the dependence of the shape of magnetoresistance curves on the geometric parameters of laterally bounded TMR contacts, as well as on the mutual orientation of the external magnetic field and the axis of unidirectional anisotropy of the pinned CoFe layer. The chain resistance ranges from several tens of kiloohms to hundreds of megaohms depending on the thickness of the tunnel-transparent dielectric layer with a magnetoresistive effect of 10–15%. The developed technology can be used in manufacturing tunneling magnetic field sensors. [ABSTRACT FROM AUTHOR]

The vertical isotopic profile of the ice core of a Messoyakha-1 bulgunniakh (pingo)—was obtained. The pingo is situated at 68°30′32″ N, 79°59′53″ E, in the southern part of the Gydan Peninsula within the Middle Messoyakha swell. No significant variations were registered in the isotopic composition of the pingo ice core: δ18О varied from –14.98 to –16.60‰ and δ2Н varied from –117.9 to –122.8 ‰. This small range of values probably resulted from intense heaving and rather rapid formation of the pingo. Based on the features of the pingo, it can be assumed that initially there was a lake of 0.5 km length and 0.3 km width at this site. Then, the water drained into a nearby river, the lake began to dry out, and the khasyrey (alas), which occupies most of the former lake area, was formed. The pingo itself arose during the freezing of the alas under its gradual drying out. [ABSTRACT FROM AUTHOR]

We experimentally study the interlayer interaction in a magnetic multilayer system ferromagnet/insulator/ferromagnet with different spacer thickness. The sign and the magnitude of the interaction can be deduced from the ferromagnetic resonance (FMR) peak shape rather than the FMR peak shift. The proposed technique allows studying the interlayer interaction using a single sample (without a reference sample for comparison). [ABSTRACT FROM AUTHOR]

This is the first report on investigation of bacteriophages in ancient Arctic ground ice of various genesis and geological age. Electron microscopy revealed phage particles in all ice samples. Tailed bacteriophages were the dominant morphotype. A correlation was found between abundances of intact microbial cells and phage particles. Direct microscopic counts revealed the highest phage abundance melted native samples of ice wedge. Dependence of occurrence and abundance of phage particles on genesis of ground ice was observed. The phages, as an integral component of microbial communities, were found to be preserved in extreme low-temperature conditions of ground ancient ice. [ABSTRACT FROM AUTHOR]

With the help of computed X-ray microtomography with a resolution of 2.75 μm, changes in the microstructure and pore space of aggregates of 3 mm in diameter from the virgin soddy-podzolic soil (Glossic Retisol (Loamic)) in the air-dry, capillary-moistened, and frozen states after five freeze-thaw cycles were studied in a laboratory experiment. The freezing of the samples was performed at their capillary moistening. It was shown that capillary moistening of initially air-dry samples from the humus (AY), eluvial (EL), and illuvial (BT1) horizons at room temperature resulted in the development of the platy, fine vesicular, and angular blocky microstructure, respectively. The total volume of tomographically visible pores >10 μm increased by 1.3, 2.2, and 3.4 times, respectively. After freeze-thaw cycles, frozen aggregates partly preserved the structural arrangement formed during the capillary moistening. At the same time, in the frozen aggregate from the AY horizon, the total tomographic porosity decreased to the initial level of the air-dry soil. In the frozen aggregate from the EL horizon, large vesicular pores were formed, owing to which the total pore volume retained its increased values. The resistance of aggregate shape to the action of freeze-thaw cycles differed. The aggregate from the EL horizon completely lost its original configuration by the end of the experiment. The aggregate from the AY horizon displayed definite features of sagging after five freeze-thaw cycles, whereas the aggregate from the BT1 horizon preserved its original configuration. [ABSTRACT FROM AUTHOR]

We report an experimental study of the optical properties of a two-dimensional square lattice of triangle Co and CoFe nanoparticles with a vortex magnetization distribution. We demonstrate that the intensity of light scattered in the diffraction maxima depends on the vorticity of the particles' magnetization and can be manipulated by applying an external magnetic field. The experimental results can be understood in terms of simple phenomenological consideration. [ABSTRACT FROM AUTHOR]

Magnetic properties of hexagonal lattices of touching magnetic nanocaps fabricated by Co film deposition on a surface of polymethyl methacrylate colloidal crystals was studied as a function of both period ( 120-450 nm) and thickness (30-60 nm). Magnetization configurations and hysteresis loops of the samples were investigated by magneto-optic Kerr effect and magnetic force microscopy. Formation of frustrated hexagonal lattices of magnetic vortices was found in the system. Magnetic coupling of the nanocaps can be tuned by changing the thickness of the deposited magnetic film, leading to change of the magnetization loop. Micromagnetic simulations of hexagonal lattices of touching magnetic dots complement the experimental observations corroborating the influence of the lattice period and the intercap coupling on the possible magnetization configurations in the system. [ABSTRACT FROM AUTHOR]

A microelectromechanical system is created that has the form of a cantilever-fitted microbar with a cross-sectional area of several square micrometers. The system is formed by applying epitaxial AlGaAs layers on the GaAs(001) surface and selective chemical etching of the AlAs layer lying under the bar. Two micro-cantilevers that are made on the same GaAs(001) wafer and directed along the [110] and [1 $$ \bar 1 $$0] orthogonal diagonal axes are studied. The static and dynamic characteristics of the systems are studied by white light optical interferometry. The deflection of the bars as a function of the applied voltage is measured in the static mode. An opposite shift of orthogonal microcantilevers on which the same voltage is applied is considered as direct evidence of the efficiency of a piezoeffect-based microengine. The calculated parameters of the micro-electromechanical system, the sensitivity and eigenfrequency, are in good agreement with the measurements. [ABSTRACT FROM AUTHOR]

Thin films of a granular ferromagnet (GF) based on phase-separating cobalt-copper solid solution have been obtained and their magnetic properties have been studied. It is established that the use of such GF films as sublayers provides a significant increase in the coercivity of thin cobalt films. Based on the GF cobalt-copper sublayers, multilayer structures with different magnetization reversal fields of component layers have been manufactured. [ABSTRACT FROM AUTHOR]

The effect of a system of ferromagnetic particles on the field-dependent critical current of a Josephson junction is experimentally studied for junctions of different geometries. For edge junctions, the effect of commensurability between the periodic magnetic field of the particles and the Josephson vortex lattice is observed. The effect manifests itself in additional maxima of the field-dependent critical current. For overlap junctions, giant (greater than sixfold) variations of the maximum critical current are observed depending on the magnetic state of the particles. The changes in the “Fraunhofer” pattern of the overlaped Josephson junctions are attributed to the formation of Abrikosov vortices due to the effect of uniformly magnetized particles. The effects revealed in the experiments can be used to analyze the inhomogeneous magnetic field of a system of submicron particles and to control the transport properties of Josephson junctions. © 2004 MAIK “Nauka/Interperiodica”. [ABSTRACT FROM AUTHOR]

For very high rate and resolution time-resolved experiments at next generation pulsed spallation neutron sources like ESS large-area hybrid low-pressure micro-strip gas chamber detectors are being developed. Due to their thin composite converter foil and exponential gas multiplication commencing at the converter surfaces the detectors are free of parallax, and according to detailed modeling the very high transverse and longitudinal localization accuracies in the conversion and gas multiplication processes allow position and time resolutions of ∼100 μm and <10 ns FWHM for thermal neutrons, respectively, the latter limited by the transit time through the converter. In the European R&D project TECHNI for this detector an advanced delay line readout technology with multi-event readout was developed as an economical solution for the majority of applications, which, however, limits the position resolution and rate capability to <0.3 mm and 1–2 Mcps, respectively. Therefore, in the successor project DETNI a dedicated ASIC family is being developed for achieving position resolutions of ∼100 μm FWHM and counting rates of ∼108 cps. This will open up novel applications based on time-of-flight (TOF) and single-event detection with very high dynamic range, replacing integrating CCD and image plate detectors, e.g. in radiography/tomography, TOF Laue diffraction, single crystal diffraction and focusing low-Q SANS. In this conference report new results concerning the technical realization of this detector system are reported in conjunction with a brief summary of the detector principle and with reference to earlier results. [Copyright &y& Elsevier]

We measured the critical current of the bilayer Nb/Co in the applied magnetic field. When the magnetic field was tilted to the axis which was perpendicular to the plane of the bilayer we observed a large difference in critical currents flowing in opposite directions. We found that the largest critical current of the bilayer exceeded the critical current of the superconductor without Co layer in a wide range of the tilted magnetic fields. The theory which takes into account the surface barrier effect for vortex entry and magnetic field of the magnetic layer gave a quantitative explanation of our experimental results. [ABSTRACT FROM AUTHOR]

A chain of Co nanoparticles was formed along a GaMnAs microbridge by electron beam lithography. The magnetic state of the particles was manipulated by a magnetic force microscope probe. It was found that resistance of the microbridge depended on the state of the particles and was different for the particles in the single-domain and vortex states. The resistance exhibited steplike behavior in an external magnetic field. This behavior was the result of the effect of the inhomogeneous stray fields of the particles on the microbridge resistance. The observed phenomenon can be used as an alternative way to control GaMnAs transport properties. [ABSTRACT FROM AUTHOR]

Edge-type Josephson junctions with a silicon nitride spacer possessing small capacitance have been fabricated at the butt-joint of two superconducting niobium films. The main results of experimental investigation of the electrical properties of these structures are presented. © 2004 MAIK “Nauka / Interperiodica”. [ABSTRACT FROM AUTHOR]