Origin of negative magnetoresistance in polycrystalline SnO 2 films

International audienceRecently observed quantum corrections to the conductivity of SnO 2 films suggest the existence of extended states and thus raise the question about the presence and mechanism of a metal-insulator transition. We present a comparative analysis of negative magnetoresistance, observed in fields up to 52 T on SnO 2 polycrystalline films, performed in the frame of both hopping conduction model and quantum corrections to the conductivity model, with the purpose to establish the ranges of agreement between these models and the obtained data. Our results suggest that the observed negative magnetoresistance of SnO 2 films is due to corrections stemming from the weak localization and electron-electron interaction

Application of docking methodologies to modeled proteins

Protein docking is essential for structural characterization of protein interactions. Besides providing the structure of protein complexes, modeling of proteins and their complexes is important for understanding the fundamental principles and specific aspects of protein interactions. The accuracy of protein modeling, in general, is still less than that of the experimental approaches. Thus, it is important to investigate the applicability of docking techniques to modeled proteins. We present new comprehensive benchmark sets of protein models for the development and validation of protein docking, as well as a systematic assessment of free and template‐based docking techniques on these sets. As opposed to previous studies, the benchmark sets reflect the real case modeling/docking scenario where the accuracy of the models is assessed by the modeling procedure, without reference to the native structure (which would be unknown in practical applications). We also expanded the analysis to include docking of protein pairs where proteins have different structural accuracy. The results show that, in general, the template‐based docking is less sensitive to the structural inaccuracies of the models than the free docking. The near‐native docking poses generated by the template‐based approach, typically, also have higher ranks than those produces by the free docking (although the free docking is indispensable in modeling the multiplicity of protein interactions in a crowded cellular environment). The results show that docking techniques are applicable to protein models in a broad range of modeling accuracy. The study provides clear guidelines for practical applications of docking to protein models

Specific of measurements and magnetoresistance data analysis in pulsed magnetic fields

lnvestigations of condensed matter properties in high magnetic fields are of great importance as they give information on the behavior of materials put in extremal condictions, and thus, саn verify prospective theoretical models which are often formulated with reference to limit cases or make predictions for the later. Such investigations, nevertheless, are very difficult to сапу out due to various specific problems which require solutions in every particular case: pulsed magnetic fields often cause effects related to experimental stuff rather than to а studied system. These effects саn overwhelm the responses which reveal phenomena taking place in the sample under study. In this paper as an example of high pulsed magnetic fields, magnetoresistance measurements and data analysis we present results obtained on SnO2 nanogranular thin films

Specific of measurements and magnetoresistance data analysis in pulsed magnetic fields

lnvestigations of condensed matter properties in high magnetic fields are of great importance as they give information on the behavior of materials put in extremal condictions, and thus, саn verify prospective theoretical models which are often formulated with reference to limit cases or make predictions for the later. Such investigations, nevertheless, are very difficult to сапу out due to various specific problems which require solutions in every particular case: pulsed magnetic fields often cause effects related to experimental stuff rather than to а studied system. These effects саn overwhelm the responses which reveal phenomena taking place in the sample under study. In this paper as an example of high pulsed magnetic fields, magnetoresistance measurements and data analysis we present results obtained on SnO2 nanogranular thin films

Electric properties of Ni-nanoparticles arrays

In this paper we present electrical properties of the Ni nanoparticles arrays in the temperature range 4,2–300 K. The temperature dependence of the conductance of the samples in the low temperature range was found to follow model taking into account weak localization and electron-electron interaction effects for 2D disordered systems. As temperature increases crossover to the behavior typical for 3D weak localization phenomena was observed due to decreasing of inelastic scattering length with the temperature rising

Charge transport mechanisms in the arrays of multi-walled carbon nanotubes

Electronic and magnetotransport properties of carbon nanotubes have attracted much attention due to they importance in verification of existing theories of modern condenced matter physics and number of possible applications. Single-walled carbon nanotubes (SWCNTs) have unique structure and show metallic or semiconducting properties in dependence of their diameter and chirality. Multi-walled carbon nanotubes (MWCNTs) are more complicated systems. They consist of a several shells of different diameter and chirality. Due to weak coupling between the shells the conductivity in a bulkcontacted MWCNTs is defined mostly by the outermost shells. For possibility of commercial manufacturing of carbon nanotubes based sensors and devices the development of fabrication methods of carbon nanotube arrays is of great importance. The intertubes barriers and defects play an essential role in the electrical transport properties of the carbon nanotube arrays. Therefore different charge transport mechanisms can be observed in the arrays of nanotubes: metallic conductivity, variable range hopping (VRH), weak localization (WL), fluctuation induced tunneling. Combination of various mechanisms is possible as well. Different types of moфhology of carbon nanotubes arrays are proposed: bundles, networks, fibers, mats etc. We present here magnetotransport properties of the thing layers of MWCNTs

Electric properties of Ni-nanoparticles arrays

In this paper we present electrical properties of the Ni nanoparticles arrays in the temperature range 4,2–300 K. The temperature dependence of the conductance of the samples in the low temperature range was found to follow model taking into account weak localization and electron-electron interaction effects for 2D disordered systems. As temperature increases crossover to the behavior typical for 3D weak localization phenomena was observed due to decreasing of inelastic scattering length with the temperature rising

Charge transport mechanisms in the arrays of multi-walled carbon nanotubes

Electronic and magnetotransport properties of carbon nanotubes have attracted much attention due to they importance in verification of existing theories of modern condenced matter physics and number of possible applications. Single-walled carbon nanotubes (SWCNTs) have unique structure and show metallic or semiconducting properties in dependence of their diameter and chirality. Multi-walled carbon nanotubes (MWCNTs) are more complicated systems. They consist of a several shells of different diameter and chirality. Due to weak coupling between the shells the conductivity in a bulkcontacted MWCNTs is defined mostly by the outermost shells. For possibility of commercial manufacturing of carbon nanotubes based sensors and devices the development of fabrication methods of carbon nanotube arrays is of great importance. The intertubes barriers and defects play an essential role in the electrical transport properties of the carbon nanotube arrays. Therefore different charge transport mechanisms can be observed in the arrays of nanotubes: metallic conductivity, variable range hopping (VRH), weak localization (WL), fluctuation induced tunneling. Combination of various mechanisms is possible as well. Different types of moфhology of carbon nanotubes arrays are proposed: bundles, networks, fibers, mats etc. We present here magnetotransport properties of the thing layers of MWCNTs