Digital polarograph-impedancemeters for frequency range of 10-3-10-5 Hz

S. P. Novitskii; I. I. Burenkov; V. I. Kenzin; R. Yu. Beck

doi:10.1135/cccc19831123

Digital polarograph-impedancemeters for frequency range of 10-3-10-5 Hz

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19831123 ◽

1983 ◽

Vol 48 (4) ◽

pp. 1123-1128

Author(s):

S. P. Novitskii ◽

I. I. Burenkov ◽

V. I. Kenzin ◽

R. Yu. Beck

Keyword(s):

Kinetics And Mechanism ◽

Frequency Range ◽

Principal Function ◽

Technical Parameters ◽

Electrode Processes ◽

Analytical Applications

Design, principal function and technical parameters of two polarograph-impendancemeters are given. The instruments are suitable both for analytical applications and for investigation of the kinetics and mechanism of electrode processes.

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Effect of Oxygen Content on Impedance Spectra of PtRh Electrodes for NOX Sensing Applications

Materials Science Forum ◽

10.4028/www.scientific.net/msf.514-516.1379 ◽

2006 ◽

Vol 514-516 ◽

pp. 1379-1384

Author(s):

Piotr Kurek ◽

S. Thiemann-Handler ◽

M. Marzantowicz ◽

M. Wasiucionek

Keyword(s):

Oxygen Content ◽

Redox Reactions ◽

Low Frequency ◽

Impedance Spectra ◽

Frequency Range ◽

Road Transportation ◽

Electrode Processes ◽

Sensing Applications ◽

Increasing Demand ◽

Effect Of Oxygen

Growing awareness of dangers related to NOX emission by industry and road transportation has resulted in increasing demand for sensors detecting NOX. An important class of these sensors use Pt-based electrodes applied on yttria-stabilized zirconia (YSZ) substrates. Performance of such sensors depends on redox reactions occurring at electrodes in the tested atmospheres. Impedance spectra and j-U curves of PtRh electrodes were measured in a 3-electrode mode, using Pt metal pads as counter and reference electrodes. The data were collected in a 10mHz- 100kHz frequency range at temperatures from 450 to 750°C. Each series of measurements was carried out in a gas mixture with different oxygen content ranging from 0 to 21 vol%. It was found out that the low-frequency part of the impedance spectra (characterizing electrode processes) was sensitive to the oxygen content in the gas mixtures.

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Density-based discrimination of protein and RNA in the ribosome

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100122721 ◽

1992 ◽

Vol 50 (1) ◽

pp. 464-465

Author(s):

Joachim Frank

Keyword(s):

Transfer Function ◽

Spatial Frequency ◽

Three Dimensional ◽

Wiener Filter ◽

Dark Field Image ◽

Dark Field ◽

Frequency Range ◽

Bright Field ◽

Contrast Transfer Function ◽

Pass Filter

Cryo-electron microscopy combined with single-particle reconstruction techniques has allowed us to form a three-dimensional image of the Escherichia coli ribosome.In the interior, we observe strong density variations which may be attributed to the difference in scattering density between ribosomal RNA (rRNA) and protein. This identification can only be tentative, and lacks quantitation at this stage, because of the nature of image formation by bright field phase contrast. Apart from limiting the resolution, the contrast transfer function acts as a high-pass filter which produces edge enhancement effects that can explain at least part of the observed variations. As a step toward a more quantitative analysis, it is necessary to correct the transfer function in the low-spatial-frequency range. Unfortunately, it is in that range where Fourier components unrelated to elastic bright-field imaging are found, and a Wiener-filter type restoration would lead to incorrect results. Depending upon the thickness of the ice layer, a varying contribution to the Fourier components in the low-spatial-frequency range originates from an “inelastic dark field” image. The only prospect to obtain quantitatively interpretable images (i.e., which would allow discrimination between rRNA and protein by application of a density threshold set to the average RNA scattering density may therefore lie in the use of energy-filtering microscopes.

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Evaluation of Special Hearing Aids for Deaf Children

Journal of Speech and Hearing Disorders ◽

10.1044/jshd.3604.527 ◽

1971 ◽

Vol 36 (4) ◽

pp. 527-537 ◽

Cited By ~ 1

Author(s):

Norman P. Erber

Keyword(s):

Hearing Aids ◽

High Frequency ◽

Hearing Aid ◽

Low Frequency ◽

Acoustic Stimulation ◽

Deaf Children ◽

Frequency Range ◽

Frequency Limit ◽

Unpublished Studies ◽

Published Research

Two types of special hearing aid have been developed recently to improve the reception of speech by profoundly deaf children. In a different way, each special system provides greater low-frequency acoustic stimulation to deaf ears than does a conventional hearing aid. One of the devices extends the low-frequency limit of amplification; the other shifts high-frequency energy to a lower frequency range. In general, previous evaluations of these special hearing aids have obtained inconsistent or inconclusive results. This paper reviews most of the published research on the use of special hearing aids by deaf children, summarizes several unpublished studies, and suggests a set of guidelines for future evaluations of special and conventional amplification systems.

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