scholarly journals Peroxidase activity of erythrocytes hemoglobin under action of low-frequency vibration

2021 ◽  
Vol 15 (4) ◽  
pp. 3-16
Author(s):  
O. I. Dotsenko ◽  
◽  
G. V. Taradina ◽  
А. М. Mischenko ◽  
◽  
...  
Keyword(s):  
Kinetic Parameters ◽  
Peroxidase Activity ◽  
Structural Changes ◽  
Low Frequency ◽  
Oxidation Reactions ◽  
Frequency Range ◽  
Oxidative Potential ◽  
Peroxidase Reaction ◽  
Low Frequency Vibration ◽  
Hemoglobin Molecule

Background. Hemoglobin is a hemoprotein which in the presence of oxidative equivalents, such as H2O2, can act as peroxidase with a very high oxidative potential. Hemoglobin oxidation is accompanied by generation of highly oxidized forms of iron and globin radicals that have high oxidative activity and are toxic to cells. In addition, peroxidase activity may indicate structural changes that occur in the hemoglobin molecule as a result of chemical modification. Materials and Methods. Erythrocyte suspension was subjected to vibration for 3 h within the frequency range from 8 to 32 Hz with amplitudes of 0.5 ± 0.04 and 0.9 ± 0.08 mm. At certain intervals, hemoglobin peroxidase activity was determined together with the content of its ligand forms in the hemolysates of cells. Additionally, experiments were performed to investigate the mechanism and calculate the kinetic parameters of peroxidase reaction. Results and Discussion. Experimental data on low-frequency vibrations effect on erythrocyte hemoglobin peroxidase activity were analyzed. The kinetics of the oxidation reaction of p-phenylenediamine by hemoglobin in erythrocytes was studied. It was found that peroxidase oxidation has a ping-pong mechanism. The kinetic parameters of the peroxidase reaction involving hemoglobin were determined. The change of kinetic parameters after two-hour exposure to the incubation medium and low-frequency vibration was studied. A possible mechanism of action of hemoglobin in oxidation reactions involving H2O2 was proposed. Conclusion. Any effect that initiates the formation of methemoglobin leads to an increase in the peroxidase activity of hemoglobin due to the involvement of the latter in the pseudoperoxidase cycle and the formation of toxic reactive globin radicals. The high content of oxyhemoglobin in the cell, observed under vibrations within the frequency range of 16–32 Hz with an amplitude of 0.9 ± 0.08 mm, can prevent its oxidation and involvement in the pseudoperoxidase cycle.

scholarly journals Stiffness-based Spring Design Optimization using Taguchi Method to reduce Low-Frequency Vibration

2019 ◽  
Vol 5 (2) ◽  
Author(s):  
Ahmad Yusuf Ismail ◽  
Al Munawir ◽  
Noerpamoengkas A
Keyword(s):  
Taguchi Method ◽  
High Frequency ◽  
Vibration Isolation ◽  
Low Frequency ◽  
Stiffness Coefficient ◽  
Frequency Range ◽  
High Noise ◽  
Low Frequency Vibration ◽  
Optimization Variable ◽  
Vibration Transmissibility

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.

scholarly journals Ultrasound assessment of the external occipital protuberance in young adults. Clinical implications

2020 ◽  
Vol 03 (01) ◽  
pp. 045-048
Author(s):  
Adrián Benito Domingo ◽  
Alberto García Godino
Keyword(s):  
Young Adults ◽  
Structural Changes ◽  
Low Frequency ◽  
Reference Value ◽  
Frequency Range ◽  
Upper Trapezius ◽  
Linear Probe ◽  
Ideal Tool ◽  
Ultrasound Assessment ◽  
Normal Reference Value

Abstract Introduction The current lifestyle, related to the indiscriminate use of screens from early ages with sustained postures, can cause structural changes (osteophytes) to the upper trapezius enthesis on the external occipital protuberance. Such findings in the skull are rare and usually asymptomatic, especially in young adults. Therefore, it is important to analyze, evaluate and correlate these findings with the patient's symptoms. Musculoskeletal ultrasound is an ideal tool to enable the evaluation of these structural alterations. Description of the Exam Prone position avoiding cranio-cervical hyperextension. A linear probe is used with a low frequency range (8–10 Mhz) The scan used as a reference is the transverse exam of the bone prominence. Subsequently, this is confirmed with a longitudinal exam, which is used to measure the osteophyte. The normal reference value is <10 mm. Discussion The ultrasound exam described above enables the easily reproducible assessment and measurement of osteophytes and insertional soft tissue at this level to enhance treatment planning.

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
Keyword(s):  
Oxygen Content ◽  
Vibration Amplitude ◽  
Low Frequency ◽  
Human Erythrocytes ◽  
Frequency Range ◽  
Time Frequency ◽  
Low Frequency Vibration ◽  
Membrane Bound ◽  
Dose Dependent ◽  
Dependent Processes

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.

scholarly journals Influence of Radiation on the Dielectric Properties of XLPE Based Insulation Systems

2010 ◽  
Vol 61 (4) ◽  
pp. 229-234 ◽  
Author(s):  
Vladimír Ďurman ◽  
Jaroslav Lelák
Keyword(s):  
Dielectric Properties ◽  
Structural Changes ◽  
Low Frequency ◽  
Absorbed Dose ◽  
Frequency Range ◽  
Impedance Measurements ◽  
Motion Data ◽  
Dielectric Data ◽  
Insulation Systems ◽  
The Cross

Influence of Radiation on the Dielectric Properties of XLPE Based Insulation SystemsThe paper discusses the possibilities of acquiring and processing the dielectric data in the range of very low frequency (VLF) and also design and construction of an impedance analyzer for measurements in this frequency range. The impedance measurements in the VLF range were used for investigation of the influence of radiation on the cross-linked polyethylene cable dielectric. An expressive β-type relaxation process was found in this type of cable. Most of the dielectric response parameters of the process depend significantly on the absorbed dose of radiation. The analysis of the process parameters showed that the most probable reason of the structural changes in cross-linked polyethylene was additional cross-linking. The results also proved that the impedance measurements in the VLF range could be effectively used in practice for estimation of the absorbed dose in the cross-linked polyethylene cables stressed by radiation.t data only. In order to identify or classify motion, data processing in real time is needed.

Modal Analysis of Bandgap Formation for Vibration Attenuation in Locally Resonant Finite Beams

2016 ◽  
Author(s):  
Christopher Sugino ◽  
Stephen Leadenham ◽  
Massimo Ruzzene ◽  
Alper Erturk
Keyword(s):  
Boundary Conditions ◽  
Modal Analysis ◽  
Low Frequency ◽  
Optimal Number ◽  
Frequency Range ◽  
Design Guideline ◽  
Arbitrary Boundary ◽  
Low Frequency Vibration ◽  
Vibration Attenuation ◽  
Unit Cells

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.

A novel metal-matrix phononic crystal with a low-frequency, broad and complete, locally-resonant band gap

2018 ◽  
Vol 32 (19) ◽  
pp. 1850221 ◽  
Author(s):  
Suobin Li ◽  
Yihua Dou ◽  
Tianning Chen ◽  
Zhiguo Wan ◽  
Zhengrong Guan
Keyword(s):  
Band Gap ◽  
Metal Matrix ◽  
Steel Plate ◽  
Phononic Crystal ◽  
Low Frequency ◽  
Crystal Plate ◽  
Band Gaps ◽  
Frequency Range ◽  
Low Frequency Vibration ◽  
Out Of Plane

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.

Assessment of ergonomically designed handle shapes for low-frequency vibration responses

2018 ◽  
Vol 233 (8) ◽  
pp. 1564-1573 ◽  
Author(s):  
B Jain AR Tony ◽  
MS Alphin
Keyword(s):  
Low Frequency ◽  
Human Hand ◽  
Frequency Range ◽  
Large Magnitude ◽  
Low Frequency Vibration ◽  
Hand Tool ◽  
Vibration Transmissibility ◽  
Vibration Responses ◽  
Subjective Measurements ◽  
The Mean

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.

scholarly journals Methods for Measuring the Dynamic Stiffness of Resilient Rail Fastenings for Low Frequency Vibration Isolation of Railways, Their Problems and Possible Solutions

2005 ◽  
Vol 24 (2) ◽  
pp. 107-115 ◽  
Author(s):  
Chris Morison ◽  
Anbin Wang ◽  
Oliver Bewes
Keyword(s):  
Vibration Isolation ◽  
Dynamic Stiffness ◽  
Low Frequency ◽  
Inertial Force ◽  
Transport Systems ◽  
Frequency Range ◽  
Low Frequency Vibration ◽  
Urban Rail ◽  
Low Stiffness ◽  
European Standards

Low frequency ground or structure-borne sound and vibration emission from urban rail transport systems can be greatly reduced by reducing the stiffness of the rail fastening. Estimates and models of the efficacy of such systems require accurate measurements of their dynamic stiffness over the frequency range of interest, and European Standards make recommendations for such measurements. This paper describes these methods and their shortcomings when applied to modern complete assemblies with low stiffness, one problem of which is the contribution of inertial forces at frequencies approaching and above the natural resonance of the system. This paper suggests a method for correcting for this inertial force, and tests this correction with the driving point method of dynamic stiffness measurement when applied to the Pandrol VANGUARD resilient rail fastening. The preliminary tests effectively triple the frequency range of valid measurements, a result which could be improved when applied to stiffer systems or with further improvements to the test equipment.

scholarly journals Design of Hydraulic Bushing and Vehicle Testing for Reducing the Judder Vibration

2018 ◽  
Vol 167 ◽  
pp. 02012
Author(s):  
Youngman Kim ◽  
Sangjin Jeong ◽  
Van-Quyet Nguyen ◽  
Kwangsuck Boo ◽  
Heungseob Kim
Keyword(s):  
Low Frequency ◽  
The Body ◽  
Lumped Parameter Model ◽  
Design Parameters ◽  
Loss Angle ◽  
Frequency Range ◽  
Cross Sectional ◽  
Front Suspension ◽  
Low Frequency Vibration ◽  
Vehicle Test

Generally, judder vibration is a low-frequency vibration phenomenon caused by a braking force imbalance that occurs when a vehicle is lightly decelerated within a range of 0.1 to 0.2g at a speed of 120 to 60 km/h. This comes from the change in the brake disk thickness (DTV), which is mainly caused by the side run-out (SRO) and thermal deformation. The adoption of hydro-bushing in the low arm G bushings of the vehicle front suspension has been done in order to provide great damping in a particular frequency range (<20Hz) in order to prevent this judder vibration from being transmitted to the body. The hydro bushing was formulated using a lumped parameter model. The fluid passage between the two chambers was modelled as a nonlinear element such as an orifice, and its important parameters (resistance, compliance) were measured using a simplified experimental setup. The main design parameters are the ratio of the cross-sectional area of the chamber to the fluid passage, the length of the fluid passage, etc., and their optimal design is such that the loss angle is greater than 45 ° in the target frequency range of 10 to 20 Hz. The hydro bushing designed for reducing the judder vibration was prepared for the actual vehicle application test and applied to the actual vehicle test. In this study, the proposed hydro bushing was applied to the G bushing of the low arm of the front suspension system of the vehicle. The loss angle of the manufactured hydro bushing was measured using acceleration signals before and after passing through the bushing. The actual vehicle test was performed on the noise dynamometer for the performance analysis of the judder vibration reduction.

A Study on the Fine Structure of the Lateral Line Organ of the Sea Eel

1973 ◽  
Vol 31 ◽  
pp. 648-649
Author(s):  
K. Hama
Keyword(s):  
Fine Structure ◽  
Electron Microscope ◽  
Lateral Line ◽  
Low Frequency ◽  
Sensory Cells ◽  
Apical Surface ◽  
Voltage Electron ◽  
Sensory Epithelia ◽  
Low Frequency Vibration ◽  
Transmission Electron

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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