Search results for "conductivity"

Nanoindentation and photoluminescence characterization of ZnO thin films and single crystals

2010

In this work an optical and micromechanical properties of ZnO films deposited on glass by simple method based on the mechanoactivated oxidation have been investigated and compared with those of bulk ZnO single crystal and commercial ZnO films. Results showed that investigated ZnO films have stable high adhesion with glass and can form grained structure with hardness 8–10 GPa or whiskers nanostructure with high hardness 18–20 GPa. Young’s modulus is in range from 80 to 120 GPa. Optical properties of obtained ZnO films with whiskers structure are typical for transparent high quality ZnO single crystal. These coatings also exhibit a photo-electric response which reflects on the change in resis…

Mapping of local conductivity variations on fragile nanopillar arrays by scanning conductive torsion mode microscopy.

2010

A gentle method that combines torsion mode topography imaging with conductive scanning force microscopy is presented. By applying an electrical bias voltage between tip and sample surface, changes in the local sample conductivity can be mapped. The topography and local conductivity variations on fragile free-standing nanopillar arrays were investigated. These samples were fabricated by an anodized aluminum oxide template process using a thermally cross-linked triphenylamine-derivate semicondcutor. The nanoscale characterization method is shown to be nondestructive. Individual nanopillars were clearly resolved in topography and current images that were recorded simultaneously. Local current−…

Controlling electrical percolation in multicomponent carbon nanotube dispersions

2011

Carbon nanotube reinforced polymeric composites can have favourable electrical properties, which make them useful for applications such as flat-panel displays and photovoltaic devices. However, using aqueous dispersions to fabricate composites with specific physical properties requires that the processing of the nanotube dispersion be understood and controlled while in the liquid phase. Here, using a combination of experiment and theory, we study the electrical percolation of carbon nanotubes introduced into a polymer matrix, and show that the percolation threshold can be substantially lowered by adding small quantities of a conductive polymer latex. Mixing colloidal particles of different …

Effects of iontophoretic 5-hydroxytryptamine on the unitary discharge frequency of caudate nucleus neurons in the rat

1980

AbstractSummaryMicroiontophoretic application of 5-hydroxytryptamine (5-HT) on rat caudate nucleus neurons has both facilitatory and inhibitory effects on the discharge frequency of the neurons; in many cases 5-HT has a two-phase action. An analysis was made of the behaviour of facilitatory and inhibitory responses in time considering the mean firing rate variations during and after 5-HT iontophoretic release. Six types of responses have been described : A : short lasting excitation, B : long lasting excitation, C : short lasting inhibition, D : delayed-onset inhibition, E : inhibition followed by excitation, F : excitation followed by inhibition. Also no topographic localization could be m…

Model predictions of the ionic mechanisms underlying the beating and bursting pacemaker characteristics of molluscan neurons

1976

The general properties of the excitable membrane on molluscan pacemaker neurons can be described on the basis of a fair amount of experimental evidence available in the literature. The neuronal membrane exhibits under voltage clamp an initial inward current carried by both Na+ and Ca2+ ions, the time- and voltage-dependent characteristics of which are similar to that of other excitable structures. The conductance mechanism for the two ion species and the transport kinetics appear to be closely similar. The time course and amplitude of the delayed outward current carried by K+ ions shows a marked dependence on the membrane potential. Characteristic for the molluscan neurons is the existence …

TCNQ radical salts containing magnetic complexes: Different interaction modes of TCNQ with Copper tetraazamacrocycles

1997

Abstract This work is devoted to the study of compounds [M(N 4 )](TCNQ) n , where N 4 = saturated or unsaturated tetraazamacrocycles, TCNQ= 7,7,8,8-tetracyanoquinodimethane, n= 2, 3. The metal is coordinated to two TCNQ groups only when there is coordinative unsaturation on it. When n= 2 all the TCNQ units are radical anions and no charge delocalization is observed. In the compounds with n= 3 only 2 3 of the TCNQ are negatively charged and a greater charge delocalization is possible. This delocalization only appears when none of the TCNQ's are coordinated to the metal and it is reflected in the higher conductivity values obtained in the solid state.

Label-free histamine detection with nanofluidic diodes through metal ion displacement mechanism

2017

[EN] We design and characterize a nanofluidic device for the label-free specific detection of histamine neurotransmitter based on a metal ion displacement mechanism. The sensor consists of an asymmetric polymer nanopore fabricated via ion track-etching technique. The nanopore sensor surface having metal-nitrilotriacetic (NTA-Ni2+) chelates is obtained by covalent coupling of native carboxylic acid groups with N-alpha,N-alpha-bis(carboxymethyl)-L-lysine (BCML), followed by exposure to Ni2+ ion solution. The BCML immobilization and subsequent Ni2+ ion complexation with NTA moieties change the surface charge concentration, which has a significant impact on the current-voltage (I-V) curve after…

Moisture absorption, thermal conductivity and noise mitigation of clay based plasters: The influence of mineralogical and textural characteristics

2016

Abstract Three pre-mixed clay based plasters successfully employed in green building practices in several European countries (Spain, France, Germany, and United Kingdom), mainly used for interior wall coating and finishing, were tested in this paper. Their compositional and textural characteristics as well as plastic behaviour were investigated through a multi-analytical approach in a previous paper. A natural earth (Terra Rossa red soil sampled in north-western Sicily), theoretically appropriate for the production of earthen plaster, was also subjected to the same analytical routine and compared with the three commercially available products. Humidity control capacity by the determination …

HEAT FLUX IN SUPERFLUID TRANSITION AND IN TURBULENT HELIUM COUNTERFLOW

57Co emission studies of cupric oxide

1990

Results on the incorporation, valence and spin states of Fe(Co) in CuO (with reference to similar studies on high temperature superconductors) and coupling of the Fe(Co) moment to the Cu magnetism in CuO are presented. Freshly prepared57Co: CuO shows two quadrupole doublets D1 and D2 withQ.S. of 2.49 and 1.52,I.S. of 0.35 and 0.70 mm/s and relative abundance of 74% and 26%, respectively at room temperature, the abundance being dependent on time in a sample exposed to ambient conditions and reaching 38 to 62% fifteen months after preparation. Below,TN=2251K, a typical combined magnetic-quadrupole interaction pattern is observed with a single saturation magnetic hfs of 25.6 T, central shift o…