This study presents numerical simulations on the vortex-induced vibration (VIV) of twin diamond-shaped cylinders in tandem at a low Reynolds number of 100. The investigation focuses on examining how the mass ratio (m*) affects vibration behavior, with the cylinders maintained at a fixed center-to-center distance of 4B (where B is the cylinder's characteristic length). The analysis employs reduced velocities (Ur) ranging from 3 to 18 and systematically examines three mass ratios (m* = 5, 10, and 20). The results reveal that this specific spacing exclusively produces co-shedding flow patterns, which manifest through five clearly distinguishable flow modes. The dominant vibration occurs in the transverse direction, with the downstream cylinder exhibiting the maximum amplitude. While the lock-in region (Ur approximate to 4-8) for the upstream cylinder shows no dependence on m*, the corresponding region for the downstream cylinder progressively contracts as the m* increases. Regarding frequency characteristics, the upstream cylinder demonstrates single-frequency vibrations at m* = 5 and 10, while the lift force transitions from single- to multi-frequency components within the lock-in region. But for m* = 20, the upstream cylinder's single-frequency vibration is driven by multi-frequency lift. Furthermore, due to vortex interactions caused by the upstream cylinder's wake, the downstream cylinder mostly experiences multifrequency lift forces.

The geometrical structure, electronic properties, and magnetic properties of the materials with different transition metal atoms (Co, Fe, Mn, Cr, Ti and V) co-adsorbed on a monolayer MoSi2P4 substrate have been calculated based on first principles. The density of states of the transition metal co-adsorption system has a clear peak at the Fermi level, indicating the origin of magnetism. All adsorption systems are n-type doped, and charge transfer mainly occurs between TM and adjacent Si and Mo atoms. The Fe(Mo)Mn(Mo) adsorption system has the smallest magnetic moment, which is 5.150 μB, while the V(Si)Ti(Si) adsorption system has the largest magnetic moment, which is 8.56 μB. Fe(Mo)Fe(Mo) and V(Si)Ti(Si) of TM atom adsorption system show positive magnetic anisotropy and in-plane magnetic anisotropy. For other adsorption systems, MAE value is negative, showing vertical magnetic anisotropy. Our studies suggest that the application of Fe and Mn double transition metal atoms to monolayer MoSi2P4 may have potential in spintronics. It can be seen from the figure that charge transfer mainly occurs between TM and adjacent Si and Mo atoms. In all magnetic adsorption systems, the yellow region between V atom and monolayer MoSi2P4 is more obvious and extensive in the adsorption system V(Si)Ti(Si), indicating that the charge transfer amount of V atom in the adsorbed monolayer MoSi2P4 is the largest. The yellow area around the Si atom is the most obvious, indicating that the Si atom gets the most charge.

Hearing is a critical sensory function for humans, and the dynamic behavior of the human ear is influenced by its constitutive relation. In this paper, a finite element model (FEM) of the middle ear with a nonlinear constitutive relation and the inner ear with a viscoelastic constitutive relation was developed based on CT scanning data of the clinical human ear. The frequency-response at the tympanic membrane (TM) and stapes footplate (SF), as well as the amplitude-frequency response and time-domain response curves at different positions of the basilar membrane (BM) were obtained by using the acoustic-solid and fluid-solid coupling dynamic analysis. The results indicated that the previous linear elastic model exhibits an error of 28% relative to experimental data, while the nonlinear-viscoelastic model proposed in this paper demonstrates an error of only 5% relative to experimental data. This model not only better align with the actual biomaterial properties of ear tissue, but also more accurately simulates the mechanical behavior of the human ear during sound perception. The realistic biomaterial model provides a reasonable and accurate numerical simulation platform for studying the biomechanical behavior of the real human ear, laying an applied foundation for related research into hearing damage.

BACKGROUND:With the existing experimental techniques, it is unable to measure the overall structural vibration of the human ear, which is difficult to reflect the relationship between hearing and ear structures. AIMS/OBJECTIVES:The overall biomechanical behaviour of the whole ear structure during sound perception is described. METHODS:Based on CT scanning data and knowledge of ear physiology, a 3D whole ear numerical model was developed that conforms to the actual physiological environment of the human body. RESULTS:The outer ear canal (EC) has an amplifying effect on sound conduction. The middle-lower part of tympanic membrane (TM) is susceptible to damage, which is mainly reflected in the high-tendency of clinically TM perforation phenomenon. Similarly, TM's damage or hypoplasia is also common. Peak amplitude occurs at the center of one-side of the oval window membrane (OWM) and the center of the round window membrane (RWM), respectively, and these areas are prone to disruption and more severely may evolve into perilymph fistulas. The BM's amplitude changes longitudinally along the cochlear helix as frequency increases. CONCLUSIONS AND SIGNIFICANCE:This model reflects the impact of localized structural damage on hearing under the coordinated working of the whole ear (outer, middle and inner ears).

While bilateral fitting of bone conduction hearing devices (BCHDs) enhances spatial hearing, further improvements are constrained by the unresolved effects of crosstalk - an influential factor that disrupts binaural acoustic cues, such as interaural level difference (ILD) and interaural phase differences (IPD), essential for accurate sound localization. This paper introduces a simplified theoretical model to describe the crosstalk phenomenon and predict the cochlear vibrational responses under bilateral bone conduction (BC) based on principles of wave interference and superposition. The model reveals sound lateralization patterns across different ILD and IPD combinations, different from well-established principles governing air conduction (AC) sound localization, including the precedence effect and intensity rule. These predicted patterns are experimentally validated through cadaveric vibration measurements and are further corroborated in psychoacoustic sound lateralization tests conducted on healthy volunteers. The findings suggest that crosstalk induces wave interference in the skull and leads to the superposition of bilateral signals at the cochleae, resulting in these atypical lateralization patterns. This evidence highlights the inherent challenges of sound localization under BC compared to AC, identifying crosstalk-induced wave interference as a primary obstacle to improved spatial hearing for bilateral BCHD users.

Research on the mechanism of sound perception in the cochlea has always been an important challenge for scientists of humans. Therefore, the frequency response of stereocilia in the cochlear different regions and the changes in tip link tension was researched, which may deepen the understanding of the physiological role of stereocilia in relation to their biomechanical behaviours and the frequency encoding mechanism in the auditory system. In this paper, the stereocilia motion is described as a forced vibration structure, and the effect of the lymphatic fluid in the cochlea on the stereocilia is considered, and a stereocilia motion model is established. The tension distribution of the tip link at different frequencies was solved. The correctness of the model was proved by comparing the response frequencies of the tip links at different positions with the Greenwood frequency. An increase in the elastic modulus of stereocilia leads to a non-linear decrease in the tension of the tip link, while an increase in the elastic modulus of the tip link leads to an increase in the tension of the tip link. Reducing the proportion of low and medium stereocilia to high stereocilia helps to improve low frequency resolution. In addition, the height gradient of stereocilia has a significant impact on their frequency response characteristics, and there are significant differences in the resolution and response range of stereocilia in different rows of outer hair cells. There are significant differences in the frequency resolution capability and response range of stereocilia of outer hair cells in different rows.

Objective: Hearing loss is a major public health problem faced all over the world and has now become one of the prevalent chronic diseases among the world's population. Most of the sensorineural hearing loss in the human ear is caused by structural damage and irreversible degeneration of the hair cells(HCs) in the cochlea. However, in current research, the microstructure of the organ of Corti (OC) within the cochlea is mostly ignored, which cannot explore the 3D overall structure of HCs. Methods: In this study, a multi-scale cochlear model containing a spiral OC is developed based on the experimental data of CT scan and light source imaging of the human ear, the clinically relevant lesions of the HCs in the OC are also explored. Results: HC loss affects the hearing by depleting traveling wave energy, whereas HC sclerosis increases the structural burden, and may result in a greater susceptibility to damage of the basilar membrane(BM) structure in different frequency ranges. Both loss and sclerosis may cause a rise in the stress on the remaining HCs, with the region of stress amplitude shifting towards the lesion area, thereby triggering secondary damage to the HC. Conclusion: The loss or sclerosis of HCs can cause varying degree of hearing loss. Significance: This article reveals the impact of HC lesions on the human ear's hearing perception process, providing corresponding theoretical guidance for the treatment of related lesions in clinic sensorineural hearing loss.

The cilia of the outer hair cells (OHCs) are the key microstructures involved in cochlear acoustic function, and their interactions with lymph in the cochlea involve complex, highly nonlinear, coupled motion and energy conversions, including macroscopic fluid-solid coupling. Recent optical measurements have shown that the frequency selectivity of the cochlea at high sound levels is entirely mechanical and is determined by the interactions of the hair bundles with the surrounding fluid. In this paper, an analytical mathematical model of the spiral cochlea containing macro- and micromeasurements was developed to investigate how the phonosensitive function of OHCs' motions is influenced by the macrostructural and microstructural fluid-solid coupling in the spiral cochlea. The results showed that the macrostructural and microstructural fluid-solid coupling exerted the radial forces of OHCs through the flow field, deflecting the cilia and generating frequency-selective properties of the microstructures. This finding showed that microstructural frequency selectivity arises from the radial motions of stereocilia hair bundles and enhances the hearing of sound signals at specific frequencies. It also implied that the macrostructural and microstructural fluid-solid couplings influence the OHCs' radial forces and that this is a key factor in the excitation of ion channels that enables their activity in helping the brain to detect sound.

The roles and mechanisms of A-kinase anchoring protein 1 (AKAP1) in vascular smooth muscle cell (VSMC) phenotypic modulation and neointima formation are currently unknown. AKAP1 is a mitochondrial PKA-anchored protein and maintains mitochondrial homeostasis. This study aimed to investigate how AKAP1/PKA signaling plays a protective role in inhibiting VSMC phenotypic transformation and neointima formation by regulating mitochondrial fission. The results showed that both PDGF-BB treatment and balloon injury reduced the transcription, expression, and mitochondrial anchoring of AKAP1. In vitro, the overexpression of AKAP1 significantly inhibited PDGF-BB mediated VSMC proliferation and migration, whereas AKAP1 knockdown further aggravated VSMC phenotypic transformation. Additionally, in the balloon injury model in vivo, AKAP1 overexpression reduced neointima formation, the muscle fiber area ratio, and rat VSMC proliferation and migration. Furthermore, PDGF-BB and balloon injury inhibited Drp1 phosphorylation at Ser637 and promoted Drp1 activity and mitochondrial midzone fission; AKAP1 overexpression reversed these effects. AKAP1 overexpression also inhibited the distribution of mitochondria at the plasma membrane and the reduction of PKARIIβ expression induced by PDGF-BB, as evidenced by an increase in mitochondria-plasma membrane distance as well as PKARIIβ protein levels. Moreover, the PKA agonist promoted Drp1 phosphorylation (Ser637) and inhibited PDGF-BB-mediated mitochondrial fission, cell proliferation, and migration. The PKA antagonist reversed the increase in Drp1 phosphorylation (Ser637) and the decline in mitochondrial midzone fission and VSMC phenotypic transformation caused by AKAP1 overexpression. The results of this study reveal that AKAP1 protects VSMCs against phenotypic modulation by improving Drp1 phosphorylation at Ser637 through PKA and inhibiting mitochondrial fission, thereby preventing neointima formation.

Sound vibrations generate electrical signals called cochlear potentials, which can reflect cochlear stereocilia movement and outer hair cells (OHC) mechanical activity. However, because the cochlear structure is delicate and complex, it is difficult for existing measurement techniques to pinpoint the origin of potentials. This limitation in measurement capability makes it difficult to fully understand the contribution of stereocilia and transduction channels to cochlear potentials. In view of this, firstly, this article obtains the stereocilia movement generated by basilar membrane (BM) vibration based on the positional relationship between the various structures of the organ Corti. Secondly, Kirchhoff’s law is used to establish an electric field model of the cochlear cavity, and the stereocilia movement is embedded in the electric field by combining the gated spring model. Finally, a force-electric coupling mathematical model of the cochlea is established. The results indicated that the resistance variation between different cavities in the cochlea leads to a sharp tuning curve. As the displacement of the BM increased, the longitudinal potential along the cochlea continued to move toward the base. The decrease in stereocilia stiffness reduced the deflection angle, thereby reducing the transduction current and lymphatic potential.

BACKGROUND:Rehabilitation of endodontically treated teeth with large coronal destruction is still a clinical challenge. No established guidelines specify where a conventional crown with fiber-reinforced composite (FRC) post-and-resin core or an endocrown (EC) is indicated and which material or pulpal extension should be used. OBJECTIVE:To provide evidence for restoring severely damaged maxillary first molar (MFM) by comparing the fracture and debonding resistance after being restored with the ceramic EC and the conventional zirconia crown and FRC post-and-resin core. METHOD:Models of a MFM with a mesial-occlusal-distal-palatal defect with different restoration strategies were created: C-FRC -- conventional crown with FRC post, EC-Zr-3/4/5 - zirconia EC with 3-/4-/5-mm pulpal extension, EC-Li-3/4/5 - lithium disilicate EC with 3-/4-/5-mm pulpal extension. Two loading conditions were applied: vertical loading - a 400-N force along the tooth's long axis; lateral loading - a 225-N force at a 45-degree angle buccally to the tooth's long axis. Three-dimensional finite element analysis and Weibull analysis were conducted for the above seven models. RESULTS:The C-FRC group obtained the lowest maximal Mohr-Coulomb stress ratio (MσMC ratio) in the residual tooth structure under both loadings (0.2646 and 0.2815, respectively). The lowest MσMC ratio in the cement was in the EC-Li-5 group under both loadings (0.07660 and 0.3177, respectively). The lowest maximal shear stress at the adhesive interface was in the EC-Li-3 group under both loadings (5.700 MPa and 20.48 MPa, respectively). CONCLUSIONS:The conventional crown with FRC post-and-resin core is still suitable for restoring a MFM with a mesial-occlusal-distal-palatal defect. Lithium disilicate EC with 3-mm pulpal extension may be a choice for the MFM where conventional restoration is not applicable.

The complex fluid–solid coupling movement of macro–micro structures and lymphatic fluid in the cochlea plays a crucial role in the mechanism of sound perception in the human ear. However, previous studies have primarily focused on the macrostructure and overlooked the microstructure of the Organ of Corti (OC). In reality, the microstructure of the OC can regulate the vibration of the basilar membrane, which is important for sound perception. To address this, a three-dimensional spiral passive cochlear model containing a complete OC that conforms to the real physiology of the human ear was developed, but the significant amplification of its motion by the action of outer hair cells (OHC) in the living cochlea was not considered. The fluid–solid coupling calculations were conducted on this model, specifically examining the mechanical response of the OC microstructure and the pressure changes in the lymphatic fluid. The results showed that the lower stiffness structure in the OC has a lower stress level, which contributes to the realization of sound perception. As the frequencies increases, the region of peak stress and displacement in the OHC moves from the apex to the base of the cochlea, reflecting frequency-selective characteristics. The tunnel of the OC amplifies pressure waves at specific locations, enabling more accurate frequency recognition. Furthermore, the presence of the OC not only causes significant radial differences in lymphatic fluid pressure in the scala vestibule, but also enhances internal cochlear vibration, playing an undeniable regulatory role in the sound perception.Kindly check and verify edit made in article title.We have checked and verified the editing in the article title.

So far, explaining the mechanism on active phonosensitive amplification in the cochlea is a major and difficult medical question. Among them, one of the key problems is that the motion pattern of the organ of Corti (OC) is still unknown. To this end, a multi-scale cochlear model including a three-dimensional spiral OC was established based on CT data and light source imaging experimental data, which complete combined the macroscopic and microscopic structure. On the basis of verifying the reliability of the model, acoustic-solid coupling calculation and modal analysis were performed on the model, and the vibration modes of basilar membrane (BM) and structures of the OC at different characteristic frequencies were discussed. The results show that tectorial membrane (TM) exhibits completely different vibration modes from BM at low frequencies, while the two movements gradually synchronize as the frequency increases. The amplitude position of OC's motion moves laterally with increasing frequency from Deiters' cells to Hensen's cells and then back to Deiters' cells. The OC exhibits longitudinal vibrations following BM when BM's displacement is large, while it manifests more as lateral movement of Deiters' cells when BM's displacement is small. This model can well simulate the motion process of BM and OC in the lymphatic fluid, which provides theoretical support and a numerical simulation computational platform to explore the interaction between macroscopic and microscopic tissue structures of the overall cochlea.

Due to ethical issues and the very fine and complex structure of the cochlea, it is difficult to directly perform experimental measurement on the human cochlea. Therefore, the finite element method has become an effective and replaceable new research means. Accurate numerical analysis on human ear using finite element method can provide better understanding of sound transmission and can be used to assess the influence of diseases on hearing and to treat hearing loss. In this research, a three-dimensional (3D) finite element model (FEM) of the human ear of cochlea was presented to investigate the destruction of basilar membrane (BM), round window (RW) sclerosis and perilymph fistula, the key structures of the cochlea, and analyze the effects of these abnormal pathological states in the cochlea on cochlear hearing, resulting in the changes in cochlear sense structure biomechanical behavior and quantitative prediction of the degree and harm of the disorder to the decline of human hearing. Therefore, this paper can deepen reader's understanding of the cochlear biomechanical mechanism and provide a theoretical foundation for clinical otology.

Due to the tiny and delicate structure of the cochlea, the auditory system is the most sensitive to explosion impact damage. After being damaged by the explosion impact wave, it usually causes long-term deafness, tinnitus, and other symptoms. To better understand the influence of impact load on the cochlea and basilar membrane (BM), a three-dimensional (3D) fluid-solid coupling finite element model was developed. This model accurately reflects the actual spatial spiral shape of the human cochlea, as well as the lymph environment and biological materials. Based on verifying the reliability of the model, the curve of impact load-amplitude response was obtained, and damage of impact load on the cochlea and the key macrostructure-BM was analyzed. The results indicate that impact wave at middle frequency has widest influence on the cochlea. Furthermore, impact loading causes tears in the BM and destroys the cochlear frequency selectivity.

In order to explore the hearing loss resulting from exposure to continuous or intermittent loud noise. A three-dimensional liquid-solid coupling finite element model of spiral cochlea was established. The reliability of the model was verified, and the stress and amplitude of the basilar membrane of the pivotal structure in cochlea were analyzed. The results show that under the action of the same high-pressure sound, the preferential fatigue area of the cochlear high-frequency area mainly causes fatigue in the cochlear. The safer area is a sound pressure level below 70 dB, while one above 90 dB accelerates damage to the ear.

Monopile offshore wind turbine (OWT) accounts for more than 65% of all OWT types. Monopile OWT is a soil-pile-tower system and can be divided into three stages: the stage embedded in the soil, the stage submerged in the seawater and the stage exposed to the air. Based on the improved Tajimi formulation and dynamic principle, this paper establishes a three-stage monopile OWT model to predict the dynamic response of the structure. The displacement of the tower under different wind velocities is obtained. The solution is compared with the Finite Element Method (FEM) result to verify its correctness. The influences of different parameters on the structure are discussed. The results indicate that the structure natural frequency is sensitive to the tower length and nacelle-rotor mass. The increasing seawater depth due to scour effect can significantly decrease the foundation stiffness. The influence of axial force and wave load on the foundation stiffness is also investigated. The tower diameter and tower wall thickness are found of vital importance to the tower displacement.

减少冲刷坑深度是桥梁设计与维护中常面临的一个重要问题.为了进一步探明促淤网格的安装位置等对桩墩局部冲刷坑促淤修复效果的影响,通过水槽试验研究促淤修复率随促淤网格安装位置、网孔大小等要素的变化特征.结果表明:促淤修复率受来流强度的影响不大,受网格的相对安装位置影响很大;为提高促淤网格的稳定性和促淤修复效果,促淤网格应安装在沙波波谷以下尽可能高的位置,以获得尽可能大的促淤容量,增大网格的促淤深度;网格的相对网孔孔径越小,网格安装位置对冲刷坑促淤修复效果的影响越显著.最后,提出了促淤网格防护下的最终促淤深度计算公式,为今后促淤网格的工程应用提供参考.

Explaining the mechanism of the cochlear active phonosensitive amplification has been a major problem in medicine. The basilar membrane (BM) is the key infrastructure. In 1960, Nobel Laureate von Békésy first discovered BM’s traveling wave motion. Since that time, BM’s models only have considered the traveling wave but not the biological activity. Therefore, a new model considering changes of BM’s stiffness in space and time is established based on the immersed boundary method to describe its biological activity. It not only reproduces the results of traveling wave motion but also explains the mechanization on the generation of traveling wave. An important discovery is that changes of BM’s stiffness in space and time will cause the unstable global resonance, which will induce amplification of sounds in cochlea. An important inference is that biological activity shall be included in the application of mechanical principles to the analysis of life, which is the essential difference between biomechanics and general mechanics.

Some experiments can't be realized because the cochlea's Corti is the most delicate and complex sensory organ. In this paper, some typical and special behavioral characteristics in the process of sensation were found in medical clinic. Based on the interdisciplinary principles of medicine, physics and biology, a real numerical simulation model of Corti is established. On the basis of verifying the correctness of the model, the mechanism corresponding to these typical and special behavior characteristics in the process of sensation is explored through simulation calculation and analysis. This study provides theoretical and applied basis for people to better understand the sound sensing mechanism, and provides a numerical simulation platform for further analyzing Corti's sensing mechanism and good clinical application.