scholarly journals Specifics of Reduction-Oxidation Processes Exposed to a Low--Frequency Acoustic Field

Author(s):  
G.N. Fadeev ◽  
V.S. Boldyrev ◽  
N.A. Bogatov ◽  
A.L. Nikolaev

The investigation concerned the effects of low-frequency vibrations on a system consisting of two biochemically active components: methylene blue dye and ascorbic acid. Each component can be reversibly oxidized and reduced. This system allows us to trace the effect that a low-frequency vibration field has on the reciprocal reduction-oxidation process and detect specific features of this type of exposure. We discovered that reduction-oxidation processes in such systems do not accelerate but slow down when exposed to low frequencies, unlike those in the previously studied clathrate and chelate structures. We observe an inhibition effect concerning the sonochemical process in a low-frequency acoustic field. We performed a qualitative estimation of the effect.

Author(s):  
Sahand Sadeghi ◽  
Suyi Li

This research investigates a quasi-zero stiffness (QZS) property from the pressurized fluidic origami cellular solid, and examines how this QZS property can be harnessed for low-frequency base excitation isolation. The QZS property originates from the nonlinear geometric relations between folding and internal volume change, and it is directly correlated to the design parameters of the constituent Miura-Ori sheets. Two different structures are studied to obtain a design guideline for achieving QZS: one is identical stacked Miura-Ori sheets (ismo) and the other is non-identical stacked Miura-Ori sheets (nismo). Further dynamic analyses based on numerical simulation and harmonic balance method, indicate that the QZS from pressurized fluidic origami can achieve effective base excitation isolation at low frequencies. Results of this study can become the foundation of origami-inspired metamaterials and metastructures with embedded dynamic functionalities.


2019 ◽  
Vol 487 (3) ◽  
pp. 275-278
Author(s):  
G. N. Fadeev ◽  
V. S. Boldyrev ◽  
N. A. Bogatov ◽  
A. L. Nikolaev

The effect of low-frequency oscillations on a system consisting of two biochemically active components: the dye of methylene blue and ascorbic acid is investigated. Each of these components can be reversibly oxidized and reduced. The system is interesting in that it makes it possible to trace the influence of the low-frequency acoustic field on the mutual redox process and to reveal the features of the effect of such oscillations. It was found that, in this system, with the introduction of low-frequency effects, redox processes are not accelerated, but slowed down. There is an effect inhibition of the sound-chemical process in the field of low-frequency acoustic effects. The effect is quantified.


2010 ◽  
Vol 7 (1) ◽  
pp. 139-141 ◽  
Author(s):  
Jakob Christensen-Dalsgaard ◽  
Christian Brandt ◽  
Maria Wilson ◽  
Magnus Wahlberg ◽  
Peter T. Madsen

Lungfishes are the closest living relatives of the tetrapods, and the ear of recent lungfishes resembles the tetrapod ear more than the ear of ray-finned fishes and is therefore of interest for understanding the evolution of hearing in the early tetrapods. The water-to-land transition resulted in major changes in the tetrapod ear associated with the detection of air-borne sound pressure, as evidenced by the late and independent origins of tympanic ears in all of the major tetrapod groups. To investigate lungfish pressure and vibration detection, we measured the sensitivity and frequency responses of five West African lungfish ( Protopterus annectens ) using brainstem potentials evoked by calibrated sound and vibration stimuli in air and water. We find that the lungfish ear has good low-frequency vibration sensitivity, like recent amphibians, but poor sensitivity to air-borne sound. The skull shows measurable vibrations above 100 Hz when stimulated by air-borne sound, but the ear is apparently insensitive at these frequencies, suggesting that the lungfish ear is neither adapted nor pre-adapted for aerial hearing. Thus, if the lungfish ear is a model of the ear of early tetrapods, their auditory sensitivity was limited to very low frequencies on land, mostly mediated by substrate-borne vibrations.


Author(s):  
Dmitry Fedorov ◽  
Andrey Khitrov ◽  
Evgeny Veselkov ◽  
Yuliya Domracheva ◽  
Oksana Kozyreva

The article is devoted to synthesis of the low-frequency vibration exciter for checking of sensors of acceleration. In many areas of the modern equipment sensors of acceleration working in very low range of frequencies are widely used. For checking and graduation of such sensors the vibration exciter capable to provide rectilinear horizontal harmonic oscillations of the calibrated accelerometer in so low range of frequencies are required. Low frequencies of fluctuations cause the necessity of creation of big amplitudes of movements for ensuring the acceptable values of amplitudes of accelerations. The low-frequency electrodynamic vibration exciter with a magnetic suspension of mobile part which is a component of the National Standard of the vibration movement of the Russian Federation is so far created. However, development of the modern equipment demands expansion of frequency ranges to the area of ultralow frequencies. One of requirements shown to the vibration exciter working in the ultralow range of frequencies is increase in amplitude of horizontal movements of a mobile part as with small amplitudes the speed and acceleration of the harmonious law of the movements proportional according to the frequency of fluctuations and a square of this frequency, will have small amplitude values. One of problems of realization of a control system of the electric drive of the vibration exciter consists in that a mobile part possesses indifferent position of balance. The centre of fluctuations of a mobile part is not defined and can be in any point on magnetic conductor length. That fluctuations had the steady centre in an average point of a magnetic conductor without use of a mechanical spring, the drive is supplied with an additional control system of fluctuations, or a so-called electromagnetic spring.


2014 ◽  
Author(s):  
Eric A. Favini ◽  
Jesse H. Spence

Marine insulation and joiner facing out fittings are known to affect the acoustical properties of the surface they cover. Measured results provided in this paper show that these treatments can also have a substantial effect on the vibration response of ship structures at low frequencies (below 100 Hz). The accuracy of finite element models of marine vibration response to machinery and propeller sources can be improved by accounting for these effects. Two objectives are discussed in this paper: 1) quantifying the effect of various insulation and joiner treatments on the vibration response of a typical ship bulkhead based on measured data and 2) developing an efficient and accurate method to integrate these effects into finite element models for the prediction of vibrations on ships and marine structures.


Author(s):  
K. Hama

The lateral line organs of the sea eel consist of canal and pit organs which are different in function. The former is a low frequency vibration detector whereas the latter functions as an ion receptor as well as a mechano receptor.The fine structure of the sensory epithelia of both organs were studied by means of ordinary transmission electron microscope, high voltage electron microscope and of surface scanning electron microscope.The sensory cells of the canal organ are polarized in front-caudal direction and those of the pit organ are polarized in dorso-ventral direction. The sensory epithelia of both organs have thinner surface coats compared to the surrounding ordinary epithelial cells, which have very thick fuzzy coatings on the apical surface.


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