scholarly journals Vibration influence on the O2-dependent processes activity in human erythrocytes

2021 ◽  
Vol 12 (3) ◽  
pp. 452-458
Author(s):  
O. I. Dotsenko ◽  
А. М. Mischenko ◽  
G. V. Taradina

The early signs of vibration effects on the human body are microcirculation and transcapillary metabolism disorders, accompanied by disruption of the supply to and utilization of oxygen in the tissues and organs. However, there are few experimental studies aimed at finding targets of vibration in cells and determining the action mechanism of vibration. In in vitro experiments, human erythrocytes in buffer solution were exposed to low-frequency vibration (frequency range 8–32 Hz, amplitudes 0.5–0.9 mm) for 3 hours. The dynamics of the accumulation of membrane-bound catalase and hemoglobin and the distribution of ligand hemoglobin in the membrane-bound fraction were studied as the indicators of functional activity of cells. The choice of these indicators is justified by the participation of catalase and hemoglobin in O2-dependent cellular reactions as a part of protein complexes. Since pО2 is a trigger of conformational transitions in the hemoglobin molecule, simultaneously with oxygen transport, hemoglobin signals to different metabolic systems about oxygen conditions in the environment. The studies revealed that in the conditions of vibration, the activity of membrane-associated catalase increased by 40–50% in the frequency range of 12–24 Hz (amplitude 0.5 ± 0.04 mm), by 20–30% in the amplitude of 0.9 mm, but after about 100–120 min exposure the enzyme activity decreased even below the control level. There was a dose-dependent accumulation of membrane-bound hemoglobin during exposure to vibration. In the membrane-bound fraction of hemoglobin, oxyhemoglobin had the highest content (60–80%), while the content of methemoglobin varied 5–20%. During vibrations in the frequency range 12–28 Hz, 0.5 mm, we recorded 10–30% increase in oxyhemoglobin. With increase in the vibration amplitude (0.9 mm) in the frequency range of 16–32 Hz, constant content of oxyhemoglobin was noted at the beginning of the experiment, which tended to decrease during the last exposure time. Frequency of 32 Hz caused increase in the deoxyhemoglobin content in the membrane-bound fraction. The content of methemoglobin (metHb) in erythrocytes significantly increased during exposure to the frequency range of 12–24 Hz, with the amplitude of 0.5 mm (1.3–2.4 times). During the exposure to frequencies of 28 and 32 Hz, we observed the transition of methemoglobin to hemichrome. The content of methemoglobin in the cells was lower and decreased at the end of the experiment when the vibration amplitude was 0.9 mm. In these experimental conditions, no increase in hemichrome content in the membrane-bound fraction was recorded. Therefore, the degree of binding of catalase and hemoglobin with the membrane of erythrocytes that were exposed to vibration and the changes in the content of ligand forms in the composition of membrane-bound hemoglobin are dose-dependent. Low-frequency vibration initiates O2-dependent processes in erythrocytes. Targets of such an influence are nanobubbles of dissolved air (babstons), retained on the surface of erythrocytes due to Coulomb interactions, capable of coagulation and increase in size under the action of vibration. At first, the consequences of these processes are increase in oxygen content in the surface of erythrocytes, and then decrease as a result of degassing. Thus, increase in oxygen content on the surface initiates redox reactions, whereas decrease in oxygen content leads to reconstruction of metabolic processes oriented at overcoming hypoxia.

Processes ◽  
2020 ◽  
Vol 8 (11) ◽  
pp. 1336
Author(s):  
Wei Fan ◽  
Hong Lu ◽  
Yongquan Zhang ◽  
Xiangang Su

The dynamic vibration of the gear coupling-rotor system (GCRS) caused by misalignment is an important factor of low frequency vibration and noise radiation of the naval marine. The axial misalignment of gear coupling is inevitable owing to mass eccentricity, and is unconstrained in axial direction at high-speed operation. Therefore, the dynamic model of GCRS is proposed, considering gear-coupling misalignment and contact force in this paper. The whole motion differential equation of GCRS is established based on the finite element method. Moreover, the numerical calculation method of meshing force, considering the uniform distribution load on contact surface, is presented, and the mathematical predictive time–frequency characteristics are analyzed by the Newmark stepwise integral approach. Finally, a reduced-scale application of the propulsion shaft system is utilized to validate the effectiveness of the proposed dynamic model. For the sensibility to low-frequency vibration, the natural frequencies and vibration modes of GCRS are analyzed through the processing and analysis of acceleration signal. The experimental dynamic response and main components of vibration are respectively consistent with mathematical results, which demonstrate the effectiveness of the proposed dynamic model of GCRS with misalignment. Furthermore, it also shows that the proposed finite element analysis and calculation method are suitable for complex shafting, providing a novel thought for dynamic analysis of the propeller–shaft–hull coupled system of marine.


2006 ◽  
Vol 514-516 ◽  
pp. 1379-1384
Author(s):  
Piotr Kurek ◽  
S. Thiemann-Handler ◽  
M. Marzantowicz ◽  
M. Wasiucionek

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.


2021 ◽  
Author(s):  
Ramy Hussein ◽  
Ahmad Sadek ◽  
Mohamed Elbestawi ◽  
Helmi Attia

Abstract In this paper, the tool wear mechanism in low-frequency vibration-assisted drilling (LF-VAD) of carbon fiber reinforced polymer (CFRP)/Ti6Al4V stacks has been proposed using variably machining parameters. Based on the kinematics analysis, the effect of vibration amplitude on the chip formation, uncut chip thickness, chip radian, and axial velocity was presented. Subsequently, the effect of LF-VAD on the cutting temperature, tool wear, delamination, and geometrical accuracy was presented for different vibration amplitude. The LF-VAD with the utilization of minimum quantity lubricant (MQL) resulted in a successful drilling process of 50 holes, with a 63 % reduction of the cutting temperature. For the rake face, LF-VAD reduced the adhered height of Ti6Al4V by 80 % at low cutting speed and reduced the crater depth by 33 % at the high cutting speed. On the other hand, LF-VAD reduced the flank wear land by 53 %. Furthermore, LF-VAD showed a significant enhancement on the CFRP delamination, geometrical accuracy, and burr formation.


Author(s):  
Ahmad Yusuf Ismail ◽  
Al Munawir ◽  
Noerpamoengkas A

Low-frequency vibration has been troublesome for a mechanical system. Despite the measurement difficulties, low-frequency vibration also creates several environmental effects such as high noise level that is harmful to the human body. One of the methods to reduce vibration is tuning the vibration isolation i.e. spring and damping coefficient. However, the latter method is found to be effective only for the mid-high frequency range. Therefore, this paper proposes an optimization of the spring a.k.a. stiffness coefficient in order to reduce the low-frequency vibration. The Taguchi method is used as an optimization tool since it offers simplicity yet powerful for any field of application, particularly in engineering. Two significant parameters in the spring geometry were selected as the optimization variable in the Taguchi method and evaluated using vibration transmissibility concept. The result shows that the Taguchi method has been successfully obtained the optimum value for the spring geometry purposely to reduce the vibration transmissibility.


2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
A. Trochidis ◽  
L. Hadjileontiadis ◽  
K. Zacharias

The vibro-acoustic modulation (VAM) technique is probably the most widely used nonlinear method for crack detection. The VAM method is based on the effect of modulation of high-frequency acoustic waves by a low-frequency vibration. The intensity of the modulation is related to the severity of the damage and has been used so far as a damage index. The damage index simply based on the amplitude of the first side bands in the spectral domain often leads to controversial results about the severity of the damage. In this work, the nonlinear characteristics of the vibro-modulation were systematically investigated by employing time-frequency analysis based on the Zhao-Atlas-Marks (ZAM) distribution. The results of the analysis show that the amplitude of the sideband components is modulated by the low frequency vibration and the modulation amplitude depends on the size of the crack. Based on the obtained results, a new damage index was defined in relation to the strength of the modulation. The new damage index is more sensitive and robust and correlates better with crack size compared to the index based on the amplitude of the sidebands.


2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Hitoshi Kimura ◽  
Akisue Kuramoto ◽  
Yuma Inui ◽  
Norio Inou

In running cars or trains, passengers often feel sleepy. Our study focuses on this physiological phenomenon. If a machine can reproduce this phenomenon, it is feasible to put a person, such as an insomnia patient or an infant, to sleep without any harmful effects. The results of our previous study suggest that low-frequency vibration induces sleep. This report describes a new mechanical bed for inducing sleep and discusses the effects of different vibration conditions. The new bed has two active DOFs in the vertical and horizontal directions to examine the anisotropy of sensation. The bed includes three main parts: a vertical driver unit, a horizontal driver unit, and a unique 2-DOF counterweight system to reduce driving force and noise. With regard to motion accuracy, the maximum motion error in the vertical direction lifting 75 kg load was only 0.06 mm with a 5.0 mm amplitude of a 0.5 Hz sinusoidal wave. The results of excitation experiments with 10 subjects showed a significant difference in sleep latency between the conditions with vibration and without vibration. Furthermore, the average latency with insensible vibration (amplitude = 2.4 mm) was shorter than that with sensible vibration (amplitude = 7.5 mm). These results suggest the ability of appropriate vibration to induce sleep.


2007 ◽  
Vol 102 (3) ◽  
pp. 1057-1064 ◽  
Author(s):  
Maya David ◽  
Michael Hirsch ◽  
Jacob Karin ◽  
Eran Toledo ◽  
Solange Akselrod

In this study we present a noninvasive method that enables the investigation of the fetal heart rate (FHR) fluctuations. The objective was to design a quantitative measurement to assess the fetal autonomic nervous system and to investigate its development as a function of the gestational age. Our Medical Physics group has developed a complex algorithm for online beat-to-beat detection of the fetal ECG (FECG), extracted from the maternal abdominal ECG signal. We used our previously acquired FECG data, which includes noninvasive recordings of 200 maternal abdominal ECG signals. From these, we chose 35 cases of healthy pregnancies that we divided into three groups according to gestational age: Group 1, 23 ± 2 wk; Group 2, 32 ± 1 wk; and Group 3, 39 ± 1 wk. The FHR variability was analyzed by a time-frequency decomposition based on a continuous wavelet transform. We showed that, independent of the gestational age, most of the FHR power is concentrated in the very-low-frequency range (0.02–0.08 Hz) and in the low-frequency range (0.08–0.2 Hz). In addition, there is power in the high-frequency range that correlates with the frequency range of fetal respiratory motion (0.4–1.7 Hz). In the intermediate-frequency range (0.2–0.4 Hz), the power is significantly smaller. The changes in the average power spectrum in relation to gestation time were carefully and quantitatively examined. The results imply that there is a neural organization during the last trimester of the pregnancy, and the sympathovagal balance is reduced with the gestational age.


Author(s):  
Christopher Sugino ◽  
Stephen Leadenham ◽  
Massimo Ruzzene ◽  
Alper Erturk

Metamaterials made from locally resonating arrays can exhibit attenuation bandgaps at wavelengths much longer than the lattice size, enabling low-frequency vibration attenuation. For an effective use of such locally resonant metamaterial concepts, it is required to bridge the gap between the dispersion characteristics and modal behavior of the host structure with its resonators. To this end, we develop a novel argument for bandgap formation in finite-length beams, relying on modal analysis and the assumption of infinitely many resonators. This assumption is analogous to the wave assumption of an infinitely long beam composed of unit cells, but gives additional analytical insight into the bandgap, and yields a simple formula for the frequency range of the bandgap. We present a design guideline to place the bandgap for a finite beam with arbitrary boundary conditions in a desired frequency range that depends only on the total mass ratio and natural frequency of the resonators. For a beam with a finite number of resonators and specified boundary conditions, we suggest a method for choosing the optimal number of resonators. We validate the model with both finite-element simulations and a simple experiment, and draw conclusions.


2018 ◽  
Vol 32 (19) ◽  
pp. 1850221 ◽  
Author(s):  
Suobin Li ◽  
Yihua Dou ◽  
Tianning Chen ◽  
Zhiguo Wan ◽  
Zhengrong Guan

In this paper, a novel metal-matrix phononic crystal with a low-frequency, broad and complete, locally-resonant band gap, which includes the in-plane and out-of-plane band gaps, is investigated numerically. The proposed structure consists of double-sided single “hard” cylinder stubs, which are deposited on a two-dimensional locally-resonant phononic-crystal plate that consists of an array of rubber fillers embedded in a steel plate. Our results indicate that both the out-of-plane band gap and the in-plane band gap increase after introducing single “hard” cylinder stubs. More specifically, the out-of-plane band gap is increased by the out-of-plane analogous-rigid mode, while the in-plane band gap is increased by the in-plane analogous-rigid mode. The out-of-plane and the in-plane analogous-rigid mode are formed after introduction of the single “hard” cylinder stub. As a result, a broad, complete locally-resonant band gap in the low frequency is obtained due to the broad in-plane and out-of-plane band gaps overlapping. Compared to the classical double-sided stubbed metal-matrix phononic-crystal plate, the absolute bandwidth of the complete band gap is increased by a factor of 4.76 in the proposed structure. Furthermore, the effect of simple “hard” stubs on complete band gaps is investigated. The results show that the location of the complete band gaps can be modulated using a low frequency, and the bandwidth can be extended to a larger frequency range using different “hard” stubs. The new structure provides an effective way for metal-matrix phononic crystals to obtain broad and complete locally-resonant band gaps in the low-frequency range, which has many applications for low-frequency vibration reduction.


Author(s):  
B Jain AR Tony ◽  
MS Alphin

Hand-operated tool handles transmit a large magnitude of vibration to the hand-arm system during low-frequency operations. Therefore, the precise design of a hand tool is very important to overcome musculoskeletal disorders, hand-arm vibration, etc. This study was aimed at developing optimal tool handles with an increased contact area and to overcome the contact pressure, which causes discomfort and pain. Six different human hand-based optimal handles (handles B to G) and one optimal cylindrical handle (handle A) were designed and fabricated using 3D printing technology, in order to assess the effect of low-frequency vibrations. The effect of handle shapes was evaluated with objective and subjective measurements using 15 subjects. Objective measurements were performed to assess the vibration transmissibility by experimental study at the frequency range of 0–100 Hz, and subjective measurements were performed to rate the handles based on comfort descriptors and overall comfort of the handles. Root mean square vibration accelerations were recorded at the wrist, elbow, and shoulder of each subject and at the base of the handle fixture to evaluate the vibration transmissibility for each handle. The mean vibration transmissibility was found to be minimum for handle B and was rated to be more comfortable by the subjects. The results indicated that all the human hand-based handles transmit less vibration and were rated to be more comfortable than the optimal cylindrical handle.


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