Changes In Elasticity Research Articles

Evaluation of renal elasticity by shear wave elastography in children with Familial Mediterranean Fever.

Familial Mediterranean Fever (FMF) is a genetic disorder that can cause kidney damage. Shear wave elastography (SWE), a non-invasive method, was used to evaluate the decrease in renal tissue elasticity as a predictive parameter for amyloidosis. This study aimed to examine the changes in renal elasticity in patients with FMF using the renal SWE measurement method. The present study included 50 pediatric patients diagnosed with FMF. The median SWE values of both kidneys were compared between the groups. Acute phase reactants were also evaluated. The SWE measurements (for the left kidney p = 0.007, for the right kidney p = 0.06) and proteinuria levels (p < 0.001) of the patient group were found to be higher than those of the control group. No correlation was observed between the disease activity score and the SWE measurements. Erythrocyte sedimentation rate (p < 0.001), C-reactive protein (p < 0.001) and urine protein/creatinine ratio (p < 0.001) were significantly higher in the remission period compared to the control group, whereas estimated glomerular filtration rate was found to be low in the patient group (p < 0.001), which was considered as an indicator that subclinical inflammation continued in the course of the disease. The acute phase reactants were elevated in patients with FMF even in the remission period which indicates that the disease is constantly active and have the potential to cause damage in all organs and tissues. It is thought that this subclinical inflammation may also contribute to increased tissue stiffness, which may serve as a predictor for the development of amyloidosis.

Teaching strategies for resolving gastrointestinal function from the perspective of cell biomechanics

Traditional gastrointestinal function teaching focuses on biochemical and physiological regulation, but fails to explore the effects of mechanical forces on gastrointestinal cell behavior and function, resulting in students’ one-sided understanding of gastrointestinal function. This paper proposes a new teaching strategy by combining cell biomechanics with teaching to help students master the gastrointestinal function mechanism more comprehensively. First, the membrane elasticity of gastrointestinal smooth muscle cells is measured. The elastic modulus is calculated by combining the Hertz model and the applied force is controlled to avoid cell membrane damage. Elasticity change data is obtained. Then, a flexible substrate is used to apply stretching and low frequency to simulate the mechanical force of cells during peristalsis and monitor the fluctuation of calcium ion concentration. Then, the distribution of intercellular cadherin is analyzed, and mechanical force is used to accelerate the permeability of gap junctions and the expression of Connexin43 to promote signal transmission. Finally, a teaching experiment based on cell biomechanics is designed, covering cell culture, mechanical stimulation, quantitative analysis and molecular biology verification, to help students understand how mechanical forces affect gastrointestinal cell behavior and function. The results show that before and after the application of the cell biomechanics teaching strategy, the students’ test scores increase by 16%, and the experimental results are good. Applying biomechanical factors into teaching by combining teaching strategies with cell biomechanics has a positive effect on medical education.

Short- and Mid-Term Results Using a 448 Kilohertz Radiofrequency Stimulation on the Elasticity Plantar Fascia Measured by Quantitative Ultrasound Elastography on Active Healthy Subjects: An Open Controlled Clinical Trial with Three Months of Follow-Up.

Background: This study is an open clinical trial that included 3 months of follow-up. Methods: This study aimed to show the changes that occur in the viscoelastic properties of the PF measured by SEL after the six applications of a 448 kHz capacitive resistive monopolar radiofrequency (CRMR) in active, healthy subjects, immediately before the CRMR intervention (T0), during the two-week CRMR intervention program (T1), after the CRMR intervention program (T2), two weeks after the CRMR intervention program (T3), one month after the CRMR intervention program (T4), and three months after the CRMR intervention program (T5). Results: Our results showed that the effects of CRMR on the plantar fascia elasticity may last up to one month in a healthy population after a 3-week treatment program when compared to controls, specifically following the medial process of the calcaneal tuberosity (points 1 and 2). However, there were no changes when analyzing points 3 and 4. These findings are a first step towards understanding the duration of the CRMR effects in the elastic properties of the tissue and therefore how long the benefit may last. Conclusions: This study showed that changes in the plantar fascia elasticity measured by SEL have been found after a CRMR intervention protocol, similarly to other structures reported in the literature, such as the patellar tendon or supraspinatus tendon.

Analysis of Quality Intima-Media Thickness and Quantitative Artery Stiffness technologies on non-alcoholic fatty liver disease: a study on carotid artery structure, elasticity, and influential factors in patients.

In recent years, there have been numerous studies using Quality Intima-Media Thickness (QIMT) and Quantitative Arterial Stiffness (QAS) technology to evaluate various related factors and disease-induced changes in carotid artery (CA) elasticity. However, there is still a lack of research on the relationship between non-alcoholic fatty liver disease (NAFLD) and various indicators related to the CA. This study aimed to investigate the clinical significance of using QIMT and QAS techniques for comprehensive evaluation of CA intima-media thickness (IMT) and elasticity changes in NAFLD patients, and to analyze various factors influencing these variables. In this cross-sectional study, a total of 196 healthy adults and 285 NAFLD patients were selected from June 2021 and October 2021 in the First Affiliated Hospital of Zhejiang University School of Medicine. Body mass index (BMI), blood pressure, and triglyceride levels were collected. CA IMT and pulse wave velocity (PWV) were measured using QIMT and QAS techniques. Multiple linear regression analysis was employed to explore the relationship between parameters measured using QIMT and QAS techniques and NAFLD, while controlling for covariates, to assess the measurement effects of QIMT and QAS techniques on arterial structure and elasticity in NAFLD patients. A total of 233 males and 248 females were included in this study, with 178 males (62.46%) and 107 females (37.54%) being diagnosed with NAFLD. Gender, age, systolic blood pressure (SBP), and uric acid (UA) all are related to CA IMT (estimated value -0.031 to 0.008, P<0.0001-P=0.0450). The presence of NAFLD was not significantly related to IMT, but primarily influenced vascular elasticity indicators α, β, PWV, augmentation index (Aix), distensibility coefficient (DC), and compliance coefficient (CC). Age, SBP, diastolic blood pressure (DBP), high-density lipoprotein (HDL), and UA were all related to vascular elasticity coefficient β (estimated value -0.05 to 1.03, P<0.0001-P=0.0451); SBP and UA had a relationship with PWV (estimated value -0.001 to 0.405, P<0.0001-P=0.0027); gender, age, SBP, DBP, and UA all influenced Aix (estimated value -0.17 to 0.65, P<0.0001-P=0.0072). Ultrasound radiofrequency (RF) signal QIMT and QAS techniques can reflect changes in CA structure and elasticity function in NAFLD patients, which can be more widely applied and promoted in the changes of CA structure and elastic function in NAFLD patients.

Krill oil supplementation improves transepidermal water loss, hydration and elasticity of the skin in healthy adults: Results from two randomized, double-blind, placebo-controlled, dose-finding pilot studies.

Dietary marine omega-3 fatty acids and phospholipids have individually shown favorable effects on skin barrier function. Krill oil offers a combination of omega-3 in phospholipid form which might enhance the efficacy in supporting skin health. The aim was to investigate the impact of two different doses of krill oil on skin transepidermal water loss (TEWL) in healthy adults. Secondary outcomes were skin hydration, elasticity and the omega-3 index. Two randomized, double-blind, placebo-controlled, pilot studies were conducted in healthy adults with a baseline TEWL of >10 and ≤24.9 g/m2/h. In study 1, 51 participants consumed 1 g of krill oil or placebo daily. In study 2, 50 participants consumed 2 g of krill oil or placebo daily. The outcomes were assessed at baseline, 6 and 12 weeks. The krill oil supplemented groups significantly increased their omega-3 index versus placebo in both studies. Furthermore, the krill oil groups in both studies showed statistically significant beneficial reductions in TEWL (from 14.47 ± 3.65 to 13.83 ± 3.78 in study 1 and from 14.25 ± 3.21 to 13.02 ± 2.76 in study 2) and increases in hydration and elasticity when compared to placebo. There were significant linear relationships between changes in the omega-3 index and changes in TEWL, hydration and elasticity in both studies. Daily oral supplementation with 1 and 2 g of krill oil showed significant and dose-dependent improvements in skin TEWL, hydration, and elasticity compared to placebo that correlated with changes in the omega-3 index.

Theoretical study on cushioning isolation of cushioning materials under high impact environment

Abstract When a guided projectile is fired, the high pressure generated by the gunpowder gas in the chamber produces a high impact accelerationtion of tens of thousands of g in the projectile, which makes the components of the projectile withstand a huge instantaneous, high-energy, strong impact load. This type of load environment results in the deformation and failure of the internal mechanical components and damage to all type of electronic components, leading to the failure of the entire guidance system. Selecting the correct cushioning material to store or dissipate the impact energy so that the peak value of the impact is reduced to within the range of the component is an effective technical approach. In this study, a mechanical analysis of the high-impact environment inside a certain type of artillery was conducted, the axial impact load variation curve of the projectile was drawn, and a buffer isolation mathematical model of the buffer material was established. This study obtains a visualization interface using Python to solve the problem intelligently. By changing the mass of the mass block, the equivalent stiffness and equivalent damping value of the buffer material in the program script, researchers can use the model to draw the displacement, velocity and acceleration curves of the two mass blocks simultaneously, and obtain the buffering efficiency and maximum elastic compression of the buffer material. When the equivalent damping is the same, this study obtains the buffering efficiency curve and the maximum elastic compression curve changing with the stiffness through the model. The results show that in the range of elastic deformation, the buffering efficiency is proportional to the length of the buffering material but inversely proportional to its equivalent stiffness. The mathematical model provides technical support for the pre-design development and selection of cushioning materials in high-impact environments.

Viscoelastic Behavior of Cellular Biomaterials Based on Octet-Truss and Tetrahedron Topologies.

Cellular biomaterials offer unique properties for diverse biomedical applications. However, their complex viscoelastic behavior requires careful consideration for design optimization. This study explores the effective viscoelastic response of two promising unit cell designs (tetrahedron-based and octet-truss) suitable for high porosity and strong mechanics. The asymptotic homogenization (AH) method was employed to determine effective longitudinal and shear moduli, as well as Poisson's ratio, across various relative densities. Finite element simulations (ABAQUS) validated the AH results, demonstrating good agreement (<10% discrepancies). Additionally, analytical models and compression tests on 3D-printed lattice structures supported the theoretical predictions. The study revealed a strong correlation between relative density and the effective modulus of both designs. Notably, the tetrahedron-based design exhibited superior modulus, making it favorable for high loading levels, particularly when used as a high-density configuration. Both designs demonstrated minimal time-dependent elastic modulus changes and a near-constant Poisson's ratio (0.34-0.349 for octet-truss, 0.316-0.326 for tetrahedron) across a 5-50% relative density range. While minimal, time-dependent modulus reduction needs to be considered in longer-term simulations (t>107 s). This study provides valuable insights into the viscoelastic behavior of these unit cells using the homogenization method, with potential applications in various biomedical fields.

Research on the Correlation Between Skin Elasticity Evaluation Parameters and Age

This study aims to explore the impact of aging on skin elasticity, a key biomechanical property that diminishes over time, using the Cutometer to assess viscoelastic parameters. Methods: Researchers analyzed 22 viscoelastic parameters from the facial skin of 60 women aged 18 to 70. Key Results: The findings indicate that relaxation phase parameters, particularly biological elasticity (R7), exhibited the strongest negative correlation with age (r = −0.62), signifying a notable decline in biological elasticity as women age. In contrast, maximum deformation during the first cycle (R0) and the total area under the upper curve after 10 cycles of deformation (F4) also showed significant negative correlations with age (r = −0.47, r = −0.48), suggesting that younger skin typically presents higher values. These correlations raise questions regarding practical applications, as the presence of moisturizers and emollients may alter the stratum corneum’s properties, thus impacting these measurements. Additionally, the ratio of delayed deformation to instantaneous deformation (R6) demonstrated a positive correlation with age (r = 0.49), indicating its potential as a marker for skin aging. Conclusions: This study highlights the critical role of relaxation phase parameters in accurately reflecting skin elasticity changes associated with aging. The results offer valuable insights for evaluating cosmetic efficacy, reinforcing the need for a nuanced understanding of how various parameters interact. These findings contribute to the ongoing development of more effective anti-aging treatments and products.

Seemingly baseless discrimination

We show that rational profit maximizing firms can find it optimal to wage discriminate against females even though females and males are identical in all respects. Specifically, we argue that a pay gap can emerge naturally as discrimination against females, in the first place, can endogenously affect the elasticity of labor supply and can make the supply of labor of males less elastic and the supply of labor of females more elastic. Furthermore, we note that once this endogenous change in elasticity emerges it in fact makes discrimination optimal and allows discrimination to materialize in equilibrium. Moreover, we show that discrimination against females is detrimental to the overall welfare and in addition it negatively affects wages of males. Consequently, we argue that an equal pay mandate would benefit both genders as in our model there is no tension between females and males, but there is an endogenous extraction of surplus from workers by employers. The key mechanism described in the paper extends naturally to the product markets and can serve as rationalization of the prevalent pink-tax.

Technical note: Effects of chemical, radiational, and thermal treatment of bone tissue on material stiffness and anisotropy.

We evaluated the effects of four treatments for pathogen inactivation in bone tissue (ethanol storage, formalin fixation, gamma irradiation, and heat treatment via autoclave) on stiffness and anisotropy values in bone samples. Cortical bone samples from the humerus of 14 bovine specimens were subjected to Knoop microindentation analysis in longitudinal and transverse planes of section and four indenter orientations within each section. From each specimen, individual samples were assigned to one of five treatment conditions: 50% ethanol-saline solution, formalin immersion, gamma irradiation, autoclave, and buffered saline (controls). Each sample was microindented 100 times and the resultant stiffness data were analyzed by a resampled factorial analysis of variance. First- and second-order interactions as well as main effects of indenter orientation, treatment, and specimen were significant for both transverse and longitudinal sections, with the sole exception that indenter orientation-treatment interaction was nonsignificant for longitudinal sections. Interaction plots reveal that thermal (autoclave) and irradiation treatments depress stiffness values the most, while patterns of indentation stiffness at different orientations are relatively unaffected. Patterns of anisotropy are relatively unaffected by preservative treatments, but elastic modulus changes are consistent and unambiguous. Formalin and ethanol treatments are most comparable to controls and represent the best preservative media for mechanical testing. These options, however, are likely to be the least effective for ensuring the inactivation or sterilization of potentially contaminated samples.

Empirical insights into India's energy demand: unveiling elasticity dynamics for strategic policy initiatives.

Policymakers and stakeholders can use insights from price elasticity and income elasticities of energy demand to devise targeted interventions that promote energy efficiency, reduce reliance on fossil fuels, and drive the transition to more sustainable and resilient energy systems. This study seeks to examine how changes in income elasticity and price elasticity affect energy consumption over time using the ARDL model and a time-varying parameter technique, state-space Kalman filter. The study's findings reveal that energy prices have a negative and significant impact on energy consumption, whereas GDP per capita and population growth have apositive and significant impact on energy consumption in both the short and long run. The findings underline the importance of economic growth and increasing population in driving growing energy demand in India, which is consistent with the country's energy-intensive development aspirations. The time-varying analysis shows that the price elasticity of energy consumption follows a U-shaped pattern across time. However, from the onset of the new millennium decade, the elasticity of energy consumption with regard to its price has continually decreased, reaching - 0.54 by 2020. Furthermore, the findings imply that the income elasticity of India's energy demand has stabilized around unity, indicating that the country is currently near the middle of the energy intensity-GDP inverted-U trajectory. Given these evolving elasticities, policymakers should take a flexible and forward-thinking strategy to achieve optimal energy consumption levels.

Metallic Metamaterials with Auxetic Properties: Re-Entrant Structures

The present article is an exploration of metamaterial structures exhibiting auxetic properties. The study shows the effect of three geometric parameters of re-entrant auxetic cells, namely, the internal initial cell angle (θ0), the strut length ratio h/l, and the degree of opening of the unit cells expressed by the change in the Δθ angle, on the value of the Poisson’s ratio. It combines theoretical insights into physical re-entrant auxetic structures with the demonstration of structures that can be subjected to cyclic loading without being damaged. The experimental section features the results of the compression tests of a symmetrical structure made up of four re-entrant cells and tensile tests of a flat mesh structure of size 4 × 4. In the mesh structure, a modification was applied to the re-entrant cells, creating arched strut connections. It was shown that the value of the maximum load for such structures depends on the bending angle and the length of the inclined strut. The mesh structure was created using torsion springs. Its cyclic tension for different amplitudes yielded Poisson’s ratio values in the range of −1.4 to −1.7. These modifications have enabled stable, elastic, and failure-free cyclical changes of the structure’s dimensions under load.

Assessing the Elasticity of the Flexor Pronator Muscles After Throwing Using Ultrasound Shear Wave Elastography.

The medial ulnar collateral ligament (UCL) of the elbow joint is the primary restraint to valgus stress during the throwing motion. The flexor pronator muscles (FPMs) also stabilize the elbow joint against valgus forces; however, assessment of FPM stiffness in baseball players has been limited. To use ultrasound shear wave elastography (USWE) to evaluate the change in tissue elasticity of the FPMs due to pitching. Descriptive laboratory study. Included were 14 healthy male amateur baseball players (mean age, 28.0 ± 2.6 years) who had played intermediate-level high school or college baseball. The tissue elasticity of the flexor digitorum superficialis (FDS) in the superficial layer of the FPMs and the flexor digitorum profundus (FDP) in the deep layer of the FPMs were measured using USWE before, immediately after, and 24 hours after a throwing session of 100 pitches. The intra- and interrater reliability of the measurements were evaluated using the Pearson correlation coefficient and intraclass correlation coefficient (ICC). The elasticity of each muscle was analyzed using repeated-measures analysis of variance followed by post hoc analysis. Reliability of the USWE measurements was good to excellent (intrarater ICCs, 0.78-0.94; interrater ICCs, 0.85-0.96). The mean tissue elasticity values before, immediately after, and 24 hours after pitching were 22.3 ± 4.4, 41.0 ± 13.8, and 38.3 ± 11.2 kPa, respectively, for the FDS and 27.1 ± 5.8, 48.0 ± 22.3, and 29.6 ± 11.5 kPa, respectively, for the FDP. For both the FDS and FDP, elasticity was significantly higher immediately after pitching than before pitching (P < .001 and P = .0027, respectively). While the elasticity of the FDS at 24 hours after pitching remained significantly higher compared with before pitching (P = .0011), the elasticity of the FDP at 24 hours decreased to the same level as before pitching (P = .91). Results using USWE indicated that the elasticity of the FDS did not decrease 24 hours after pitching and remained significantly higher than before pitching, suggesting that it may not be fully functioning as a dynamic stabilizer during this period. Pitching in such a condition may result in greater stress on the UCL and increase the risk of UCL injury.

Fava Bean Protein Nanofibrils Modulate Cell Membrane Interfaces for Biomolecular Interactions as Unveiled by Atomic Force Microscopy.

Functional amyloids (protein nanofibrils, PNF) synthesized from plant sources exhibit unique physicochemical and nanomechanical properties that could improve food texture. While environmental factors affecting PNFs are well-known, scientific evidence on how cells (focus on the oral cavity) respond to them under physiological conditions is lacking. Self-assembled PNFs synthesized from fava bean whole protein isolate show a strong pH- and solvent-dependent morphology and elasticity modification measured by atomic force microscopy (AFM). After incubation of PNFs with an oral mechanosensitive model cell line at pH 7.3, difference in cell-surface roughness without significant changes in the overall cell elasticity were measured. The role of cell membrane composition on supported lipid bilayers was also tested, showing an increase in membrane elasticity with increasing fibril concentration and the possible impact of annular phospholipids in binding. Genetic responses of membrane proteins involved in texture and fat perception were detected at the mRNA level by RT-qPCR assay and both mechano- and chemosensing proteins displayed responses highlighting an interface dependent interaction. The outcomes of this study provide a basis for understanding the changing physicochemical properties of PNFs and their effect on flavor perception by altering mouthfeel and fat properties. This knowledge is important in the development of plant-based texture enhancers for sensory-appealing foods that require consumer acceptance and further promote healthy diets.

In Vivo Imaging and Evaluation of CornealBiomechanics After Corneal Transplantation by Optical CoherenceElastography.

Postoperative corneal biomechanical evaluation is of great significance in clinical monitoring and management since corneal transplantation is one of the main methods to improve visual function. In this paper, we propose an OCE system based on a small ultrasound transducer to realize the in vivo detection of postoperative corneal elasticity in different directions. It was first validated and analyzed by different agar, and then the elasticity changes in normal cornea and post-transplant corneal implants and implant beds were further investigated. Compared with normal corneas, the shear wave velocity of the postoperative cornea decreased from 7.42 ± 1.71 m/s to 4.95 ± 0.35 m/s. Meanwhile, the shear wave velocity of the corneal implant bed was lower than that of the implanted sheet. Therefore, this study reports the first biomechanical measurement of corneal grafts based on the OCE technique, which might provide a potential tool for the postoperative evaluation of clinical patients.

Metal surface crack depth laser acoustic emission detection method based on multivariate feature adaptive extraction and cross-modal interaction fusion

Surface crack depth detection of metal structures is of great significance to ensure the safe of equipment. However, the commonly used detection methods currently suffer from sensitivity and imaging dimension limitations, which make it difficult to ensure accuracy and feature extraction. To this end, a laser acoustic emission crack depth detection method that combines modal decomposition and deep learning is proposed. The new method is more sensitive to elastic wave changes that detect the depth of microscopic cracks and shows higher accuracy than traditional detection methods. At the same time, frequency-adaptive feature mode decomposition of multivariate signals and color multimodal feature fusion are used to solve the difficulty of time–frequency domain feature mining in current research. The crack depth detection network CDDNet is constructed using an attention-based fusion backbone, a novel cross-modal interaction fusion, and a hierarchical information fusion strategy. Its transfer learning achieves a crack detection accuracy level of 0.05 mm and outperforms other models in terms of accuracy, reaching 93.6 %. This paper shows that the proposed transfer learning laser acoustic emission technology and supporting data processing methods can effectively establish a connection between the experimental and simulation datasets, solving the current challenges of crack depth detection in terms of micro-precision and data processing.

How do sectoral elasticities affect the transmission of monetary shocks?

PurposeThe presence of heterogeneity in price stickiness has been previously shown to be the main determinant of the real effects of nominal shocks. The paper presents theoretical results that highlight the significance of labor mobility and intratemporal elasticity of substitution across sectors.Design/methodology/approachThis paper explores output dynamics in a closed economy, relying on a New Keynesian model that accounts for heterogeneity in price stickiness across sectors.FindingsThe key finding from the analytical results is that changes in labor mobility and intratemporal elasticity of substitution across sectors have an equivalent impact on sectoral output when accounting for differences in price stickiness. The model is then calibrated for the US economy using data from the manufacturing and services sectors, providing validation for the analytical results.Originality/valueConventional models often assume either immediate labor reallocation across sectors following shocks or no labor mobility at all. Additionally, these models assume either strong complementarity in consumption or some degree of substitutability. This paper demonstrates the crucial role that labor reallocation and the elasticity of substitution across goods across sectors play in generating well-known economic outcomes.

Shear wave elastography to evaluate the effect of serum uric acid levels on carotid artery elasticity in patients with high-normal blood pressure

Background: Populations with normal high blood pressure often already have elevated blood uric acid levels and a higher chance of developing atherosclerosis, which accelerates the process of cardiovascular disease. The risk of atherosclerosis increases with thickening of the carotid artery intima-media, and changes in carotid artery elasticity precede intima-media changes, so early monitoring of carotid artery elasticity is of great significance in the prevention of cardiovascular disease. Using shear wave elastography (SWE) to evaluate the effect of serum uric acid (SUA) levels on carotid artery elasticity in patients with high-normal blood pressure (BP). Methods: One hundred and fifteen patients with high-normal BP were selected, and then divided into tertiles according to the SUA levels. The left carotid intima-media thickness (IMT), peak systolic velocity (PSV) and diameter of common carotid artery were measured by two-dimensional ultrasound and Doppler flow imaging. Longitudinal elasticity of the left anterior carotid wall was measured by SWE, including the mean values of the minimum elastic modulus (MEmin), maximum elastic modulus (MEmax) and mean elastic modulus (MEmean). Results: IMT, MEmean, MEmin and MEmax were obviously higher in the 3rd tertile (all P &lt; 0.05), while there were no obviously different between the 1st tertile and 2nd tertile. Pearson correlation analysis showed positive correlations between SUA and SWE-related parameters, while there was no correlation with IMT. Multiple linear regression analysis found that age, systolic BP, and SUA levels were independently associated with SWE-related parameters. Conclusion: SWE will be more helpful than IMT in monitoring the effect of blood uric acid levels on carotid artery elasticity in patients with high-normal BP.

First-principles calculations to investigate thermodynamic, mechanical and electronic properties of Penta-C72 carbon under pressure effect

The current work explores the mechanical characteristics, band structure modifications, elastic constant changes, and anisotropy of the carbon allotrope Penta-C72 at high pressure. First-principles simulations were used to analyse the structural features, stability, electronic, mechanical, and thermodynamic properties of Penta-C72, a metastable sp3 -bonded structure made up of carbon pentagons joined by bridge-like connections. The structural and dynamical stability of Penta-C72 under high pressure is confirmed using formation energy, phonon band maps, and thermodynamic properties. Besides, Born's mechanical stability criterion is fulfilled based on the elastic constants of Penta-C72, indicating its mechanical stability. Also, the anisotropic mechanical behaviour is shown by the material. Using the Reuss, Voigt, and Hill approximations, the elastic moduli under high pressure were computed, including bulk modulus (K), shear modulus (G), and Young's modulus (E). Besides, Penta-C72 exhibits a rise in anisotropy and moduli with increasing pressure. This investigation explores the changes in the band gap upon variation in the pressure. It is observed that there is a transition from semiconducting to metallic property above 10 GPa. Beyond 10 GPa, the material exhibits metallic behaviour. The study emphasizes that Penta-C72’s exceptional mechanical stability, directional anisotropy, and customisable electronic characteristics make it a strong contender for various engineering applications.

Transpulmonary Pressure as a Predictor of Successful Lung Recruitment: Reanalysis of a Multicenter International Randomized Clinical Trial.

Recruitment maneuvers are used in patients with ARDS to enhance oxygenation and lung mechanics. Heterogeneous lung and chest-wall mechanics lead to unpredictable transpulmonary pressures and could impact recruitment maneuver success. Tailoring care based on individualized transpulmonary pressure might optimize recruitment, preventing overdistention. This study aimed to identify the optimal transpulmonary pressure for effective recruitment and to explore its association with baseline characteristics. We performed post hoc analysis on the Esophageal Pressure Guided Ventilation (EpVent2) trial. We estimated the dose-response relationship between end-recruitment end-inspiratory transpulmonary pressure and the change in lung elastance after a recruitment maneuver by using logistic regression weighted by a generalized propensity score. A positive change in lung elastance was indicative of overdistention. We examined how patient characteristics, disease severity markers, and respiratory parameters predict transpulmonary pressure by using multivariate linear regression models and dominance analyses. Of 121 subjects, 43.8% had a positive change in lung elastance. Subjects with a positive change in lung elastance had a mean ± SD transpulmonary pressure of 15.1 ± 4.9 cm H2O, compared with 13.9 ± 3.9 cm H2O in those with a negative change in lung elastance. Higher transpulmonary pressure was associated with increased probability of a positive change in lung elastance (adjusted odds ratio 1.35 per 1 cm H2O of transpulmonary pressure, 95% CI 1.13-1.61; P = .001), which indicated an S-shaped dose-response curve, with overdistention probability > 50% at transpulmonary pressure values > 18.3 cm H2O. The volume of recruitment was transpulmonary pressure-dependent (P < .001; R2 = 0.49) and inversely related to a change in lung elastance after adjusting for baseline lung elastance (P < .001; R2= 0.43). Negative correlations were observed between transpulmonary pressure and body mass index, PEEP, Sequential Organ Failure Assessment score, and PaO2 /FIO2 , whereas baseline lung elastance showed a positive correlation. The body mass index emerged as the dominant negative predictor of transpulmonary pressure (ranking 1; contribution to R2 = 0.08), whereas pre-recruitment elastance was the sole positive predictor (contribution to R2 = 0.06). Higher end-recruitment transpulmonary pressure increases the volume of recruitment but raises the risk of overdistention, providing the rationale for transpulmonary pressure to be used as a clinical target. Predictors, for example, body mass index, could guide recruitment maneuver individualization to balance adequate volume gain with overdistention.