Mechanical Stress Research Articles

Aortic Valve Stenosis Causes Accumulation of Extracellular Hemoglobin and Systemic Endothelial Dysfunction.

Whether aortic valve stenosis (AS) can adversely affect systemic endothelial function independently of standard modifiable cardiovascular risk factors is unknown. We therefore investigated endothelial and cardiac function in an experimental model of AS mice devoid of standard modifiable cardiovascular risk factors and human cohorts with AS scheduled for transcatheter aortic valve replacement. Endothelial function was determined by flow-mediated dilation using ultrasound. Extracellular hemoglobin (eHb) concentrations and NO consumption were determined in blood plasma of mice and humans by ELISA and chemiluminescence. This was complemented by measurements of aortic blood flow using 4-dimensional flow acquisition by magnetic resonance imaging and computational fluid dynamics simulations. The effects of plasma and red blood cell (RBC) suspensions on vascular function were determined in transfer experiments in a murine vasorelaxation bioassay system. In mice, the induction of AS caused systemic endothelial dysfunction. In the presence of normal systolic left ventricular function and mild hypertrophy, the increase in the transvalvular gradient was associated with elevated eryptosis, increased eHb and plasma NO consumption; eHb sequestration by haptoglobin restored endothelial function. Because the aortic valve orifice area in patients with AS decreased, postvalvular mechanical stress in the central ascending aorta increased. This was associated with elevated eHb, circulating RBC-derived microvesicles, eryptotic cells, lower haptoglobin levels without clinically relevant anemia, and consecutive endothelial dysfunction. Transfer experiments demonstrated that reduction of eHb by treatment with haptoglobin or elimination of fluid dynamic stress by transcatheter aortic valve replacement restored endothelial function. In patients with AS and subclinical RBC fragmentation, the remaining circulating RBCs before and after transcatheter aortic valve replacement exhibited intact membrane function, deformability, and resistance to osmotic and hypoxic stress. AS increases postvalvular swirling blood flow in the central ascending aorta, triggering RBC fragmentation with the accumulation of hemoglobin in the plasma. This increases NO consumption in blood, thereby limiting vascular NO bioavailability. Thus, AS itself promotes systemic endothelial dysfunction independent of other established risk factors. Transcatheter aortic valve replacement is capable of limiting NO scavenging and rescuing endothelial function by realigning postvalvular blood flow to near physiological patterns. URL: https://www.clinicaltrials.gov; Unique identifier: NCT05603520. URL: https://www.clinicaltrials.gov; Unique identifier: NCT01805739.

Entheseal surface (Sharpey's fiber insertion) alterations identify past trauma; bone base robusticity, level of routine activity.

Sharpey's fiber alterations, referred to as entheseal reaction or enthesopathy, have long been considered an indicator of daily activities. Such semantic transformation seems to conflate processes which alter the characteristics of tendonous and ligamentous attachments to bone with the rugosity and extent of their base/footprint. Rather than reflecting normal activities, it is suggested that surface reactions are actually the response to the application of sudden or unconditioned repetitive stresses-analogous to stress fractures. Thus, they are distinct from enlargement of the base/footprint, the bone remodeling process responsible for the robusticity of the area to which the enthesis attaches, which is actually a measure of actual muscle activity. Surface reactions in attachment areas represent injury, be it mechanical stress fracture-equivalents or inflammation-derived. Bone base/footprint is the reaction of the enthesis to stresses of routine physical activities. The character of underlying bone supporting Sharpey's fibers may be augmented by applied stress, but there is neither a physiologic mechanism nor is there evidence for significant addition of Sharpey's fibers beyond ontogeny. Behavior is responsible for the physiologic response of robusticity; spiculation, pathology.

Blood flow restriction Exercise in the perioperative setting to Prevent loss of muscle mass in patients with pancreatic, biliary tract, and liver cancer: study protocol for the PREV-Ex randomized controlled trial

BackgroundPatients diagnosed with pancreatic, biliary tract, and liver cancer often suffer from a progressive loss of muscle mass. Given the considerable functional impairments in these patients, high musculoskeletal weight loads may not be well tolerated by all individuals. The use of blood-flow restricted resistance training (BFR-T) which only requires low training loads may allow for a faster recovery of muscle due to avoidance of high levels of mechanical muscle stress associated with high-load resistance exercise. This study aims to investigate whether BFR-T can prevent or slow down the loss of skeletal muscle mass and enhance the functional capacity and mental health of patients with pancreatic, biliary tract, and liver cancer.MethodsThe PREV-Ex exercise trial is a multicenter two-armed randomized controlled trial. Patients will be randomized to an exercise program consisting of home-based low-load BFR-T during a combined pre- and postoperative period for a total of 6–10 weeks (prehabilitation and rehabilitation), or to a control group. Protein supplementation will be given to both groups to ensure adequate protein intake. The primary outcomes, skeletal muscle thickness and muscle cross-sectional area, will be assessed by ultrasound. Secondary outcomes include the following: (i) muscle catabolism-related and inflammatory bio-markers (molecular characteristics will be assessed from a vastus lateralis biopsy and blood samples will be obtained from a sub-sample of patients); (ii) patient-reported outcome measures (self-reported fatigue, health-related quality of life, and nutritional status will be assessed through validated questionnaires); (iii) physical fitness/performance/activity (validated tests will be used to evaluate physical function, cardiorespiratory fitness and maximal isometric muscle strength. Physical activity and sedentary behavior (assessed using an activity monitor); (iv) clinical outcomes: hospitalization rates and blood status will be recorded from the patients’ medical records; (v) explorative outcomes of patients’ experience of the exercise program which will be evaluated using focus group/individual interviews.DiscussionIt is worthwhile to investigate new strategies that have the potential to counteract the deterioration of skeletal muscle mass, muscle function, strength, and physical function, all of which have debilitating consequences for patients with pancreatic, biliary tract, and liver cancer. The expected findings could improve prognosis, help patients stay independent for longer, and possibly reduce treatment-related costs.Trial registrationClinicalTrials.gov NCT05044065. Registered on September 14, 2021.

Micro-flow cell washing technique combined with single-cell Raman spectroscopy for rapid and automatic antimicrobial susceptibility test of pathogen in urine

Facing the rapid spread of antimicrobial resistance, methods based on single-cell Raman spectroscopy have proven their advances in reducing the turn-around time (TAT) of antimicrobial susceptibility tests (AST). However, the Raman-based methods are still hindered by the prolonged centrifugal cell washing procedure, which may require complex labor operation and induce high mechanical stress, resulting in a pretreatment time of over 1 h as well as a high cell-loss probability. In this study, we developed a micro-flow cell washing device and corresponding Raman-compatible washing chips, which were able to automatically remove the impurities in the samples, retain the bacterial cell and perform Raman spectra acquisition in situ. Results of washing the 5- and 10-μm polymethyl methacrylate (PMMA) microspheres showed that the novel technique achieved a successful removal of 99 % impurity and an 80 % particle retention rate after 6 to 10 cycles of washing. The micro-flow cell washing technique could complete the pretreatment for urine samples in a 96-well plate within 10 min, only taking 15 % of the handling time required by centrifugation. The AST profiles of urine sample spiked with E. coli 25922, E. faecalis 29212, and S. aureus 29213 obtained by the proposed Raman-based approach were found to be 100 % consistent with the results from broth micro-dilution while reducing the TAT to 3 h from several days which is required by the latter. Our study has demonstrated the micro-flow cell washing technique is a reliable, fast and compatible approach to replace centrifuge washing for sample pretreatment of Raman-AST and could be readily applied in clinical scenarios.

Does high-latitude ionospheric electrodynamics exhibit hemispheric mirror symmetry?

Abstract. Ionospheric electrodynamics is a problem of mechanical stress balance mediated by electromagnetic forces. Joule heating (the total rate of frictional heating of thermospheric gases and ionospheric plasma) and ionospheric Hall and Pedersen conductances comprise three of the most basic descriptors of this problem. More than half a century after identification of their central role in ionospheric electrodynamics, several important questions about these quantities, including the degree to which they exhibit hemispheric symmetry under reversal of the sign of dipole tilt and the sign of the y component of the interplanetary magnetic field (so-called “mirror symmetry”), remain unanswered. While global estimates of these key parameters can be obtained by combining existing empirical models, one often encounters some frustrating sources of uncertainty: the measurements from which such models are derived, usually magnetic field and electric field or ion drift measurements, are typically measured separately and do not necessarily align. The models to be combined moreover often use different input parameters, different assumptions about hemispheric symmetry, and/or different coordinate systems. We eliminate these sources of uncertainty in model predictions of electromagnetic work J⋅E (in general not equal to Joule heating ηJ2) and ionospheric conductances by combining two new empirical models of the high-latitude ionospheric electric potential and ionospheric currents that are derived in a mutually consistent fashion: these models do not assume any form of symmetry between the two hemispheres; are based on Apex magnetic coordinates (denoted Apex), spherical harmonics, and the same model input parameters; and are derived exclusively from convection and magnetic field measurements made by the Swarm and CHAMP satellites. The model source code is open source and publicly available. Comparison of high-latitude distributions of electromagnetic work in each hemisphere as functions of dipole tilt and interplanetary magnetic field clock angle indicates that the typical assumption of mirror symmetry is largely justified. Model predictions of ionospheric Hall and Pedersen conductances exhibit a degree of symmetry, but clearly asymmetric responses to dipole tilt and solar wind driving conditions are also identified. The distinction between electromagnetic work and Joule heating allows us to identify where and under what conditions the assumption that the neutral wind corotates with the Earth is not likely to be physically consistent with predicted Hall and Pedersen conductances.

Simulation of Mechanical Stresses in BaTiO3 Multilayer Ceramic Capacitors during Desoldering in the Rework of Electronic Assemblies Using a Framework of Computational Fluid Dynamics and Thermomechanical Models.

Multilayer ceramic capacitors (MLCCs) are critical components when thermal processes such as reflow desoldering are used during rework of electronic assemblies. The capacitor's ferroelectric BaTiO3 body is very brittle. Therefore, thermomechanical stresses can cause crack formation and create conductive paths that may short the capacitor. In order to assess the thermally induced mechanical stresses onto an MLCC during reflow desoldering, simulations were carried out, which make use of a framework of computational fluid dynamics and thermomechanical models within the ANSYS software package. In the first step, CFD simulations were conducted to calculate the transient temperature field in the surrounding of the MLCC component, which was then used as an input for FEM simulations to compute the arising mechanical stresses inside the MLCC. The results of the simulations show that the major contribution to mechanical stresses within the MLCC component comes from the mismatch in thermal expansion between the printed circuit board and the MLCC. The temperature gradients along the MLCC component are rather small and account only for moderate internal stresses within the brittle BaTiO3 body.

Acoustic Characterization of Integrated Circuits During Operation

Abstract Power electronics are widely serving as core components of propulsion systems in electric vertical takeoff and landing (VTOL) aircraft. Nevertheless, affected by the Paschen effect, the breakdown voltage of these electronics during flight is significantly lower than that on the ground, which could deteriorate system stability, or even cause aircraft faults or crashes, increasing safety risks for the public. As such, condition monitoring of power electronics has become critical for the safe operation of eVTOL. To achieve non-intrusive monitoring, acoustic emissions (AE) sensors have gained traction with their prominent resistance to electromagnetic interference and high temperatures. However, existing studies yield conflicting results regarding whether an increase in loading voltage impacts the internal mechanical stress of electronics. To address this issue, we present this work to probe the existence and the pattern of a relationship between load voltage and stress wave, since the change of mechanical stress could generate acoustic waves that can be acquired by AE sensors. In this study, an AE sensor was applied onto an oscillator placed upon an epoxy substrate to characterize the acoustic waves emitted from the device under various input loads. In the experiment, we observed a unique AE signal pattern characterized by two distinct components that consistently intersect at a specific frequency. The time required to establish such intersections progressively lengthens as the load voltage increases. Through time-domain and frequency-domain analyses of the unique AE signals under different load voltages, it was discovered that certain features of the unique AE signals have an approximately linear relationship with the load voltage.

Conglomerate rock interface debonding characteristics and damage evolution based on cohesive phase-field method

Rock failure often occurs due to uneven mechanical strength and discontinuous strain at the interface. However, due to the complex interaction mechanism between different phases of conglomerate, it is necessary to improve the crack growth model at the conglomerates' interface. In view of the physical structure and mechanical properties of conglomerate materials, this paper innovatively adopts the cohesive phase field model to study the material deformation and crack growth of conglomerate materials. Different from the traditional phase field model, this model characterises the real structure of the interface by adding an interface phase field, which is used to simulate the debonding of the interface during crack propagation and damage evolution. The regularization of the phase field is carried out to ensure the smoothness of the interface. The transition state of the interface region is determined by the element and the additional phase field. The energy equation is coupled with the crack propagation process using the crack surface density function. The evolution of the damaged phase field and displacement field is driven by the principle of energy minimization. The innovative assumption is that there is a virtual crack at the crack tip, and the interface related elements show a certain cohesive softening form during the damage evolution, which is the main way to realize the particularity of interface mechanics. By controlling the crack dispersion state and stiffness degradation of the material, several ideal softening models are innovatively assumed according to the cohesive force change law to satisfy the mechanical properties and stress function constraints. When cutting blocks n=2.5×104, the errors of the linear model, exponential model, and compound inverse model are 1.76%, 7.48%, and 5.19%, respectively. The results of the exponential model agree well with the stress strength (the error is 2%) and interface crack kinking angle (68.89°). The simulation results indicate that the deformation process of the conglomerate can be divided into three stages: elastic deformation stage, crack propagation stage, and stable load stage. The tensile strength of conglomerate is positively correlated with interface's fracture toughness and proportion of gravel area, respectively.

Mechanics of surface deformations in rigid bodies

Studying surface deformations in solids is crucial for advancing science and technology, informing material development, structural design and process enhancement. The purpose of study is to review and analyse the mechanics of surface deformations in rigid bodies in order to identify their features and develop new methods for describing and predicting such deformations. The study analysed theoretical models and experimental approaches to study surface deformation; among the methods used, the analytical method, classification method and synthesis method should be noted. In the study, the following parameters and aspects related to surface deformation in rigid bodies were investigated: material response to plastic deformation, mechanical properties, surface deformation characteristics, extent of deformation and behaviour under small deformations. The study investigates the impact of plastic deformation on the crystal structure of materials, focusing on grain boundary structure, dislocation motion and stacking faults. The main results of the study are the identification of the relationship between mechanical stress and surface deformation in rigid bodies. It was found that high mechanical stress leads to a change in the crystal structure of the material on the surface, which, in turn, affects its mechanical properties. Also, the results of the study are the establishment of relationships between the parameters of materials and the amount of surface deformation, as well as the identification of physical laws governing this process.

Creating and evaluating a novel small diameter PCL/PU vascular graft for finger reconstruction: A comprehensive analysis of structural, mechanical, in vitro, and in vivo assessments

This study addresses vascular repair challenges during digital replantation by developing an electrospun nanofibrous scaffold using PCL and PU for small-diameter vascular grafts (<2 mm). Structural validation employed diverse techniques such as FE-SEM, DSC, and FTIR analysis, while mechanical properties like stress and strain were rigorously evaluated. Functionality was assessed through in vitro assays and in vivo experiments, including subcutaneous implantation in rats and femoral artery insertion in rabbits. The scaffold demonstrated favorable mechanical properties and enhanced cell attachment, with minimal lumen fibrosis and good blood compatibility observed. Post-implantation in rabbits showed well-established blood flow and signs of tissue formation, suggesting potential for regenerative medicine. In conclusion, the PU85/PCL15 scaffold exhibited promising outcomes, highlighting its potential in microvascular tissue engineering Level of evidenceLevel V

Dynamic Multi‐Physics Behaviors and Performance Loss of Cylindrical Batteries Upon Low‐Velocity Impact Loading

In challenging operational environments, Lithium‐ion batteries (LIBs) inevitably experience mechanical stresses, including impacts and extrusion, which can lead to battery damage, failure, and even the occurrence of fire and explosion incidents. Consequently, it is imperative to investigate the safety performance of LIBs under mechanical loads. This study is grounded in a more realistic coupling scenario consisting of electrochemical cycling and low‐velocity impact. We systematically and experimentally uncovered the mechanical, electrochemical, and thermal responses, damage behavior, and corresponding mechanisms under various conditions. Our study demonstrates that higher impact energy results in increased structural stiffness, maximum temperature, and maximum voltage drop. Furthermore, heightened impact energy significantly influences the electrical resistance parameters within the internal resistance. We also examined the effects of State of Charge (SOC) and C‐rates. The methodology and experimental findings will offer insights for enhancing the safety design, conducting risk assessments, and enabling the cascading utilization of energy storage systems based on LIBs.

A CASE REPORT: EARLOBE RECONSTRUCTION ON CONGENITAL AURICULAR LOBE DEFECT USING Z-PLASTY

Highlights: Congenital ear defects typically result from growth failures during the fifth to ninth weeks of gestation or from mechanical stress during this period. Auricular lobuloplasty using the Z-plasty flap technique effectively addresses earlobe defects, resulting in optimal aesthetic outcomes with no keloid formation, minimal scarring, and no complications. Abstract: Introduction: Earlobe defects, often due to embryonal growth failure or injury, can affect aesthetics and social interactions despite not impacting hearing. Earlobe defect can be formed either from birth as congenital defect or secondary manifestation of other causes such as tumor and external factor such as earring usage or trauma. This study aimed to address these issues by performing auricular lobuloplasty using a Z-plasty flap technique. The procedure, crucial for protecting the auditory canal and facilitating eyeglass use, was successful in achieving the desired aesthetic outcome. Data on microtia prevalence, particularly in Indonesia, highlights the need for such reconstructive surgeries. Case Illustration: A 9-year-old boy underwent auricular lobuloplasty to correct a cleft earlobe deformity, which caused social discomfort. The surgery, performed under general anesthesia, utilized a Z-plasty technique to lengthen and reorient the scar. Postoperative care included wound dressing changes and oral pain medication. After two weeks, satisfactory results were observed with no reported complications. Discussion: The study on congenital ear deformities focuses on Z-plasty for earlobe reconstruction, detailing classifications, surgical techniques, and case results. The surgery was successful with minimal scarring and no keloid formation. Using Weerda's classification, the technique showed minimal scarring and no keloid formation. The approach, emphasizing proper skin envelope and alignment with Langer lines, offers effective aesthetic restoration, making it a valuable reference for future earlobe reconstruction cases. Conclusion: Utilizing Z-plasty for earlobe defect reconstruction aids in improving the earlobe's appearance with minimal to no complications.

Myocardial Bridge and Atherosclerosis, an Intimal Relationship.

This review investigates the relationship between myocardial bridges (MBs), intimal thickening in coronary arteries, and Atherosclerotic cardiovascular disease. It focuses on the role of mechanical forces, such as circumferential strain, in arterial wall remodeling and aims to clarify how MBs affect coronary artery pathology. MBs have been identified as influential in modulating coronary artery intimal thickness, demonstrating a protective effect against thickening within the MB segment and an increase in thickness proximal to the MB. This is attributed to changes in mechanical stress and hemodynamics. Research involving arterial hypertension models and vein graft disease has underscored the importance of circumferential strain in vascular remodeling and intimal hyperplasia. Understanding the complex dynamics between MBs, mechanical strain, and vascular remodeling is crucial for advancing our knowledge of coronary artery disease mechanisms. This could lead to improved management strategies for cardiovascular diseases, highlighting the need for further research into MB-related vascular changes.

Analysis of fluid-structure interaction in diaphragm plug valves for filling electrolyte in lithium-ion battery cells

In this paper, the stress and the local liquid residue of the diaphragm plug valve were simulated. Simulation of the diaphragm plug valve opening process was performed by using a bidirectional fluid-structure interaction based on dynamic mesh technique. The pressure and velocity distribution of the internal flow were obtained with boundary conditions for the fluid–structure interaction during the opening process. The finite element method was used to compare the equivalent stress with FSI method. The results indicate that mechanical tensile stress plays a prominent role in determining the equivalent stress of the diaphragm, with the highest stress concentration occurring in the root region. The electrolyte flow in the valve tends to be stable when reaching an opening degree of 56.6 %. Crystallization accumulation will occur due to the existence of vortices in the flow field around the diaphragm which affects the fluidity of the fluid, this area needs to be focused on.

Auxin-mediated stress relaxation in pericycle and endoderm remodeling drives lateral root initiation

Plant development relies on the precise coordination of cell growth, which is influenced by the mechanical constraints imposed by rigid cell walls. The hormone auxin plays a crucial role in regulating this growth by altering the mechanical properties of cell walls. During the postembryonic formation of lateral roots, pericycle cells deep within the main root are triggered by auxin to resume growth and divide to form a new root. This growth involves a complex interplay between auxin, growth, and the resolution of mechanical conflicts with the overlying endodermis. However, the exact mechanisms by which this coordination is achieved are still unknown. Here, we propose a model that integrates tissue mechanics and auxin transport, revealing a connection between the auxin-induced relaxation of mechanical stress in the pericycle and auxin signaling in the endodermis. We show that the endodermis initially limits the growth of pericycle cells, resulting in a modest initial expansion. However, the associated stress relaxation is sufficient to redirect auxin to the overlying endodermis, which then actively accommodates the growth, allowing for the subsequent development of the lateral root. Our model uncovers that increased pericycle turgor and decreased endodermal resistance license expansion of the pericycle and how the topology of the endodermis influences the formation of the new root. These findings highlight the interconnected relationship between mechanics and auxin flow during lateral root initiation, emphasizing the vital role of the endodermis in shaping root development through mechanotransduction and auxin signaling.

Effect of a low‐mineralized thermal spring water on skin barrier mechanical properties using atomic force microscopy

AbstractThe mineral content of thermal spring water (TSW) applied to the skin surface can directly influence the skin barrier. Indeed, our previous study showed that Avène TSW (ATSW), a low mineral content thermal spring water, protects the stratum corneum from dehydration compared to a mineral‐rich TSW (MR‐TSW) and maintains skin surface ultrastructure. While many TSWs have been recognized to have beneficial effects on skin, little is known about their localized and specific effects on skin barrier biomechanics at the nanometric scale. The aim of this study was to compare the effects of ATSW with a reference, MR‐TSW, on the biomechanical barrier properties of the skin under homeostasis conditions using atomic force microscopy (AFM). AFM was used to obtain a precise nanomechanical mapping of the skin surface after three applications of both TSW. This provides specific information on the skin topographical profile and elasticity. The topographic profile of skin samples showed a specific compaction of the skin layers after application of MR‐TSW, characterized by an increase of the total number of external skin layers, compared to non‐treated samples. By contrast, ATSW did not modify the skin topographic profile. High‐resolution force/volume acquisitions to capture the elastic modulus showed that it was directly correlated with skin rigidity. The elastic modulus strongly and significantly increased after MR‐TSW application compared to non‐treated skin. By contrast, applications of ATSW did not increase elastic modulus. These data demonstrate that applications of MR‐TSW significantly modified skin barrier properties by increasing skin surface layer compaction and skin rigidity. By contrast, ATSW did not modify the topographical profile of skin explants nor induce mechanical stress at the level of the stratum corneum, indicating it does not disrupt the biophysical properties linked to skin surface integrity.

Analysis of mechanical stresses in silicone rubber joint tubes using a hyper-elastic model

A 2D model of a silicone rubber joint tube is proposed to calculate mechanical pressure. An analysis of radial and circumferential stresses within a joint tube based on a hyper-elastic model, employing finite element method is presented. This paper shows that assuming a constant elastic modulus for rubber leads to miscalculation of stresses within the joint tube. In addition, restricting the expansion ratio without considering the material’s elasticity could elevate the possibility of introducing high circumferential stress. Depending on the elastic modulus and expansion ratio, these circumferential stresses may approach 50% of the material’s tensile strength however, none of the simulated materials showed any critical values. A rigid semiconducting deflector could potentially generate significant circumferential stress, especially at the deflector-joint insulation interface, posing an increased risk if the material is relatively weak. Achieving the required pressure with stiffer materials necessitates a lower expansion ratio, while softer materials demand higher expansion ratios to accomplish the necessary pressure levels.

Solder Defect Assessment Method for Power Electronic Devices Based on Mechanical Stress Wave Signals

The health of a power electronic device is closely related to the mechanical stress waves released at the moment when the device is turned on and off. Research has shown the potential of mechanical stress waves in power electronic device health monitoring. However, the correlation between power device defect severity and mechanical stress wave signal characteristics has not been fully established and an effective evaluation method is currently lacking. This article uses finite element simulation methods to explore the impact of void defects in the chip solder and base plate solder of insulated gate bipolar transistor (IGBT) devices on mechanical stress wave signals. By analyzing the mechanical stress wave curves of cavity defects of multiple sizes, a method for assessing the health status of power devices based on principal component analysis (PCA) is proposed. By calculating the projection of the mechanical stress wave signal on the principal component, the characteristic quantity representing the severity of the defect is obtained. Simulation results indicate that for chip soldering defects, as the severity of defects increases, the feature values gradually decrease. Therefore, this method exhibits good evaluation performance for defects throughout the entire lifecycle. In the case of plate solder defects, this approach can effectively identify mid-to-late-stage defects in devices and can also be utilized for reliability prediction before device failure.

Correlations of Corneal Endothelial Morphology and Corneal Thickness With Anterior Segment Parameters in Healthy Individuals.

The purpose of this study was to investigate the associations between central corneal endothelial cell density (ECD), endothelial morphology, and corneal thickness (central corneal thickness) with the anterior chamber depth, corneal volume (CV), white-to-white (WTW) distance, mean anterior chamber angle (CAmean), and gender in healthy individuals. This observational study included 136 healthy volunteers. The ECD, coefficient of variation of cell area, and hexagonal cell appearance ratio (%Hex) were measured by means of specular microscopy. The central corneal thickness, anterior chamber depth, CV, WTW distance, and the angle width of 12 points were taken by the Pentacam HR Scheimpflug anterior segment imaging. The arithmetical mean of the 12 points was considered as the CAmean. We used mixed effect linear regression model for the statistical analysis of the data. ECD was positively correlated with CV ( P = 0.028), while after adjusting for age, it was negatively correlated with age ( P < 0.001). Coefficient of variation of cell area was positively correlated with CAmean ( P = 0.036), while after adjusting for age, it was positively correlated with age ( P < 0.001) and CAmean ( P = 0.005). Hex was negatively correlated with WTW ( P = 0.023) and CAmean ( P = 0.025), and after adjusting for age, this correlation remained the same ( P = 0.029 when correlated with WTW and P = 0.035 with CAmean). There were significant changes in the morphology of the corneal endothelial cells in eyes with wider anterior chamber angle. Greater pleomorphism and polymegethism of the corneal endothelium was observed in healthy patients with wider CAmean. Deepening of the anterior chamber as myopia progresses could render the corneal endothelium more fragile and susceptible to mechanical stress, which is an area worthy of further study.

Galerkin-FEM approach for dynamic recovering of the plate profile in electrostatic MEMS with fringing field

PurposeBased on previous results of the existence, uniqueness, and regularity conditions for a continuous dynamic model for a parallel-plate electrostatic micro-electron-mechanical-systems with the fringing field, the purpose of this paper concerns a Galerkin-FEM procedure for deformable element deflection recovery. The deflection profiles are reconstructed by assigning the dielectric properties of the moving element. Furthermore, the device’s use conditions and the deformable element’s mechanical stresses are presented and discussed.Design/methodology/approachThe Galerkin-FEM approach is based on weighted residuals, where the integrals appearing in the solution equation have been solved using the Crank–Nicolson algorithm.FindingsBased on the connection between the fringing field and the electrostatic force, the proposed approach reconstructs the deflection of the deformable element, satisfying the conditions of existence, uniqueness and regularity. The influence of the electromechanical properties of the deformable plate on the method has also been considered and evaluated.Research limitations/implicationsThe developed analytical model focused on a rectangular geometry.Practical implicationsThe device studied is suitable for industrial and biomedical applications.Originality/valueThis paper proposed numerical approach characterized by low CPU time enables the creation of virtual prototypes that can be analyzed with significant cost reduction and increased productivity.