Electrical Conductivity at Surfaces of Silica Nanoparticles with Adsorbed Water at Various Relative Humidities

Conjugates comprising a semiconducting dye (Thiophene-diketopyrrolopyrrole, TDPP-dye) attached to a self-assembling peptide (HEFISTAH) assemble into long nanofibers. Well-ordered Langmuir-Blodgett films of these materials can be prepared. Networks of these nanofibres can be deposited to bridge electrodes. Although similar systems have been proposed as organic semiconductors, in this case, no electronic conductivity was observed. Instead, the fibres behaved as ionic (probably proton) conductors as a consequence of adsorbed water. A strong dependence of electrical conductivity on relative humidity and fibre network density was demonstrated. The system of nanofibers bridging gold electrodes behaved as an electrolytic cell, with oxygen reduction as a limiting electrode reaction.

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Electrical conductivity of silica gel in the presence of adsorbed water

The Journal of Physical Chemistry ◽

10.1021/j100856a051 ◽

1968 ◽

Vol 72 (10) ◽

pp. 3662-3668 ◽

Cited By ~ 320

Author(s):

James Hunter Anderson ◽

George A. Parks

Keyword(s):

Electrical Conductivity ◽

Silica Gel ◽

Adsorbed Water

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Features of frequency dependence of electrical conductivity and dielectric properties in lignins from conifers and deciduous trees

Holzforschung ◽

10.1515/hf-2019-0149 ◽

2020 ◽

Vol 74 (12) ◽

pp. 1113-1122

Author(s):

Sergey Khviyuzov ◽

Konstantin Bogolitsyn ◽

Aleksandr Volkov ◽

Gennadiy Koposov ◽

Maria Gusakova

Keyword(s):

Electrical Conductivity ◽

Dielectric Properties ◽

Electric Field ◽

High Frequency ◽

Low Frequency ◽

Adsorbed Water ◽

Deciduous Trees ◽

Hydroxyl Groups ◽

Electrophysical Properties ◽

Functional Nature

AbstractLignins are among the most common plant polymers and demonstrate pronounced electrical conductivity properties due to their conjugated polymolecular aromatic structure and polyfunctional nature. Electrical conductivity and dielectric properties of lignins from conifers and deciduous trees in the range of electric field frequencies from 10−2 to 107 Hz were investigated by means of dielectric spectroscopy. Characteristic parameters of static and high frequency electrical conductivity were calculated. To study the influence of the lignins functional nature on their electrophysical properties, the study determined three types of relaxators (separate charges or charge systems in the structure of a substance changing their position in space when exposed to an external alternating electric field) in the structure of the lignin macromolecule. Low-frequency relaxators are associated with oscillations of methoxyl groups. Mid-frequency relaxators correspond predominantly to phenolic hydroxyl groups and to hydroxyl groups of adsorbed water. High-frequency relaxators correspond to the hopping of π-electrons along the chain of conjugated bonds of a benzene ring. Differences in the structure and functional nature of lignins from conifers and deciduous trees cause different contributions of low-frequency relaxators. As a result, these features form differences in the electrophysical properties of lignins from conifers and deciduous trees.

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Investigation of electrical conductivity of PAN nanofibers containing silica nanoparticles produced by electrospinning method

Materials Today Proceedings ◽

10.1016/j.matpr.2019.06.683 ◽

2019 ◽

Vol 18 ◽

pp. 1927-1935

Author(s):

Olivier Mukongo Mpukuta ◽

Kevser Dincer ◽

Mehmet Okan Erdal

Keyword(s):

Electrical Conductivity ◽

Silica Nanoparticles ◽

Electrospinning Method

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The Effect of the Gaseous Environment on the Electrical Conductivity of Multi-Walled Carbon Nanotube Films over a Wide Temperature Range

Materials ◽

10.3390/ma13030510 ◽

2020 ◽

Vol 13 (3) ◽

pp. 510

Author(s):

Dawid Janas ◽

Krzysztof K. Koziol

Keyword(s):

Electrical Conductivity ◽

Carbon Nanotube ◽

Electrical Properties ◽

Electrical Resistance ◽

Elevated Temperatures ◽

Practical Importance ◽

Adsorbed Water ◽

Hydrogen Atmosphere ◽

Reduced Pressure ◽

Multi Walled Carbon Nanotube

The surrounding gas atmosphere can have a significant influence on the electrical properties of multi-walled carbon nanotube (CNT) ensembles. In this study, we subjected CNT films to various gaseous environments or vacuum to observe how such factors alter the electrical resistance of networks at high temperatures. We showed that the removal of adsorbed water and other contaminants from the surface under reduced pressure significantly affects the electrical conductivity of the material. We also demonstrated that exposing the CNT films to the hydrogen atmosphere (as compared to a selection of gases of inert and oxidizing character) at elevated temperatures results in a notable reduction of electrical resistance. We believe that the observed sensitivity of the electrical properties of the CNT films to hydrogen or vacuum at elevated temperatures could be of practical importance.

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Removing Substrate Background in TEM Microanalysis

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100052857 ◽

1974 ◽

Vol 32 ◽

pp. 568-569

Author(s):

John C. Russ ◽

Nicholas C. Barbi

Keyword(s):

Electrical Conductivity ◽

Rapid Growth ◽

Organic Film ◽

Absolute Concentration ◽

Background Signal ◽

X Ray ◽

Elemental Concentrations ◽

Transmission Electron ◽

Electron Microscopes ◽

The Continuum

The rapid growth of interest in attaching energy-dispersive x-ray analysis systems to transmission electron microscopes has centered largely on microanalysis of biological specimens. These are frequently either embedded in plastic or supported by an organic film, which is of great importance as regards stability under the beam since it provides thermal and electrical conductivity from the specimen to the grid.Unfortunately, the supporting medium also produces continuum x-radiation or Bremsstrahlung, which is added to the x-ray spectrum from the sample. It is not difficult to separate the characteristic peaks from the elements in the specimen from the total continuum background, but sometimes it is also necessary to separate the continuum due to the sample from that due to the support. For instance, it is possible to compute relative elemental concentrations in the sample, without standards, based on the relative net characteristic elemental intensities without regard to background; but to calculate absolute concentration, it is necessary to use the background signal itself as a measure of the total excited specimen mass.

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Macromolecular structures of biological specimens are not obscured by controlled osmium impregnation

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100076639 ◽

1983 ◽

Vol 41 ◽

pp. 606-607

Author(s):

Klaus-Ruediger Peters ◽

Samuel A. Green

Keyword(s):

Thin Films ◽

Electrical Conductivity ◽

Critical Point ◽

Metal Films ◽

High Magnification ◽

Osmium Impregnation ◽

Instrumental Resolution ◽

20 Nm ◽

Continuous Metal

High magnification imaging of macromolecules on metal coated biological specimens is limited only by wet preparation procedures since recently obtained instrumental resolution allows visualization of topographic structures as smal l as 1-2 nm. Details of such dimensions may be visualized if continuous metal films with a thickness of 2 nm or less are applied. Such thin films give sufficient contrast in TEM as well as in SEM (SE-I image mode). The requisite increase in electrical conductivity for SEM of biological specimens is achieved through the use of ligand mediated wet osmiuum impregnation of the specimen before critical point (CP) drying. A commonly used ligand is thiocarbohvdrazide (TCH), first introduced to TEM for en block staining of lipids and glvcomacromolecules with osmium black. Now TCH is also used for SEM. However, after ligand mediated osinification nonspecific osmium black precipitates were often found obscuring surface details with large diffuse aggregates or with dense particular deposits, 2-20 nm in size. Thus, only low magnification work was considered possible after TCH appl ication.

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