Mechanical Function Research Articles

Artificial hearing systems based on functional cochlea models

Abstract The cochlea is one of the most complex organs in the human body, exhibiting a complex interplay of characteristics in acoustic, mechanical, electrical, and biological functions. Functional cochlea models are an essential platform for studying hearing mechanics and are crucial for developing next-generation auditory prostheses and artificial hearing systems for sensorineural hearing restoration. Recent advances in additive manufacturing, organ-on-a-chip models, drug delivery platforms, and artificial intelligence have provided valuable insights into how to manufacture artificial cochlea models that more accurately replicate the complex anatomy and physiology of the inner ear. This paper reviews recent advancements in the applications of advanced manufacturing techniques in reproducing the physical, biological, and intelligent functions of the cochlea. It also outlines the current challenges to developing mechanically, electrically, and anatomically accurate functional models of the inner ear. Finally, this review identifies the major requirements and outlook for impactful research in this field going forward. Through interdisciplinary collaboration and innovation, these functional cochlea models are poised to drive significant advancements in hearing treatments, and ultimately enhance the quality of life for individuals with hearing loss.

FKBP4 promotes glycolysis and hepatocellular carcinoma progression via p53/HK2 axis.

FKBP4, a member of the FK506-binding protein (FKBP) family, is a promising target for a variety of disorders, including cancer. However, its underlying molecular mechanism and potential function in hepatocellular carcinoma (HCC) are largely elusive. Therefore, we aimed to investigate the expression status, functional implications and underlying mechanisms of FKBP4 in HCC. Our bioinformatics analysis of TCGA LIHC datasets, ICGC LIRI-JP datasets and GEO datasets results showed FKBP4 was upregulated in HCC tissues. We also confirmed the elevated FKBP4 in clinical HCC samples. Additionally, quantitative RT-PCR results revealed FKBP4 was highly expressed in all five tested HCC cell lines. We also observed a correlation between elevated FKBP4 expression and poor prognosis in HCC patients. Loss of FKBP4 can inhibit the proliferation and migration in HCC cells. Furthermore, we found that silencing FKBP4 suppressed glucose uptake, lactic acid production and18F-FDG uptake compared with the control group. Mechanistically, our funding indicated that FKBP4 participates in glycolysis through p53 mediated HK2 signaling pathway, specially, FKBP4 knockdown promotes the expression and stability of p53 protein rather than affecting the transcription level. Finally, rescue experiments revealed that simultaneous knockdown of both FKBP4 and p53 partially reversed the inhibitory effects on HK2 protein levels and18F-FDG uptake. Our study elucidates a novel role of FKBP4 in promoting HCC development and glycolysis by modulating the p53/HK2 signaling pathway. Given the critical role of aerobic glycolysis in the progression of HCC, targeting FKBP4 may offer a new therapeutic strategy for treating this malignancy.

Kinetic Analysis of Molten Oxide Reduction Using Bottom-Blown Hydrogen Injection

Hydrogen-based smelting reduction has received widespread attention as an important technology for realizing low-carbon development in hydrogen metallurgy. In this study, the thermodynamics of smelting reduction was firstly analyzed by using FactSage 8.1 thermodynamic software, on the basis of which smelting reduction experiments of iron oxides by using bottom-blown hydrogen were carried out. The experiments used oxidized pellets as experimental materials, and the effects of the reduction process were analyzed in terms of the reduction temperature, the reduction time, and the hydrogen flow rate. The experimental results show that under the experimental conditions of a temperature of 1550 °C and a hydrogen flow rate of 0.2 Nm3/h, the reduction rate of iron oxides in the process of reducing iron oxides by hydrogen is significantly faster in the first 10 min than after 10 min. The hydrogen utilization rate reached a maximum of 41.87%, then decreased continuously and finally maintained at about 20%. Using the method of model fitting, it was found that the hydrogen-based molten reduction conformed to the phase boundary reaction model (Gα=1−(1−α)1/2), the corresponding mechanism function is fα=2(1−α)1/2, where α stands for the reduction conversion, and the reaction rate constant k(T) is 2.37 × 10−4 s−1 under the experimental conditions.

Regulatory Mechanism of Protein Crotonylation and Its Relationship with Cancer

Crotonylation is a recently discovered protein acyl modification that shares many enzymes with acetylation. However, it possesses a distinct regulatory mechanism and biological function due to its unique crotonyl structure. Since the discovery of crotonylation in 2011, numerous crotonylation sites have been identified in both histones and other proteins. In recent studies, crotonylation was found to play a role in various diseases and biological processes. This paper reviews the initial discovery and regulatory mechanisms of crotonylation, including various writer, reader, and eraser proteins. Finally, we emphasize the relationship of dysregulated protein crotonylation with eight common malignancies, including cervical, prostate, liver, and lung cancer, providing new potential therapeutic targets.

Sunflower pith inspired dual-gradient cellular polyurethane architecture with amplified mechanical functions

Artificial cellular materials with various mechanical functions are attracting increasing attentions from aerospace, transportation, and industrialization. However, many artificial cellular materials, despite of the hierarchically ordered structures and even unique performance to some, still lag behind many natural ones in amplification of mechanical functions owing to the limitations in intrinsic mechanical performance and sophisticated structural design. Herein, inspired with lightweight and high strength of sunflower piths, we proposed a dual-gradient structure consisting of pore size gradient and wall thickness gradient to engineer cellular architectures with desirable mechanical performance by harnessing vat photopolymerization 3D printing of double crosslinking networks polyurethane elastomer. The double-gradient cellular polyurethane architecture displays more exceptional capability in load-bearing and energy absorption compared with non– and single gradient structures. Besides, the specific compressive strength and energy absorption of the dual-gradient cellular architectures are 4 times higher than those of traditional mechanical metamaterial structures such as octet-truss lattice, gyroid lattice, and porous structure prepared with the same material. Potential mechanisms such as dual-gradient cellular structures to obtain selective flexural deformation behaviour increasing their energy absorption and dissipation capacity are fully elucidated. As the potential paradigms, we demonstrated the mechanical functions of biomimetic mechanical cellular architectures for efficient impact protection and noise isolation, which offered a promising perspective toward developing soft metamaterials with excellent mechanical functions for potential soft machines and engineering applications.

Anti-plane Yoffe-type crack in flexoelectric material

This work investigates the deformation and polarization fields around a finite anti-plane shear (mode III) crack growing dynamically under steady-state conditions. The leading tip of this finite crack breaks the material while the trailing tip heals it. This fast moving finite crack (referred to as a rupture “pulse” in the geophysics literature) propagates with a constant velocity and with the mechanical and the electrical fields that remain invariant with respect to an observer moving with the crack-tips. This problem belongs to the first type of steady state crack growth problems according to the classification of Freund. The “prototype” problem which refers to an isotropic, body subjected to fracture under tensile loading was first proposed and solved by Yoffe, while finite cracks (or shear pulses) were also analyzed by Freund and by Rice. In the above cases the material was assumed to be linear elastic. Our analysis extends these studies to flexoelectric materials, and it is both theoretical and numerical. It discusses the asymptotic structure of the crack-tip displacement and the polarization fields; it calculates the dynamic energy release rate and presents their dependence on crack-tip velocity. Comparisons are made to the available, classical, elasto-dynamic solutions and to the static case. The influence of the electrical properties of the material on strengthening is also analyzed. Dynamic fracture of flexoelectric materials is of relevance to both the study of earthquake source mechanics and to the analysis of the reliability of micro-electronic devices. This is because both rocks and ceramics are flexoelectric. Indeed, during earthquake rupture processes, dynamic, in-plane shear (Mode-II) and out of plane shear (Mode-III), cracks propagate along faults and exhibit both mechanical and electrical polarization signatures. At an entirely different length scale, flexoelectric ceramics are currently used as sensors and transducers and can experience dynamic shear failure along interfaces when subjected to dynamic loading (e.g. impact.). Failure by dynamic fracture can be detrimental to both their mechanical reliability and electrical functionality.

Mimicking Mechanics: A Comparison of Meat and Meat Analogs

The texture of meat is one of the most important features to mimic when developing meat analogs. Both protein source and processing method impact the texture of the final product. We can distinguish three types of mechanical tests to quantify the textural differences between meat and meat analogs: puncture type, rheological torsion tests, and classical mechanical tests of tension, compression, and bending. Here, we compile the shear force and stiffness values of whole and comminuted meats and meat analogs from the two most popular tests for meat, the Warner–Bratzler shear test and the double-compression texture profile analysis. Our results suggest that, with the right fine-tuning, today’s meat analogs are well capable of mimicking the mechanics of real meat. While Warner–Bratzler shear tests and texture profile analysis provide valuable information about the tenderness and sensory perception of meat, both tests suffer from a lack of standardization, which limits cross-study comparisons. Here, we provide guidelines to standardize meat testing and report meat stiffness as the single most informative mechanical parameter. Collecting big standardized data and sharing them with the community at large could empower researchers to harness the power of generative artificial intelligence to inform the systematic development of meat analogs with desired mechanical properties and functions, taste, and sensory perception.

Left atrial functional changes associated with repeated catheter ablations for atrial fibrillation.

The impact of repeated atrial fibrillation (AF) ablations on left atrial (LA) mechanical function remains uncertain, with limited long-term follow-up data. This retrospective study involved 108 AF patients who underwent two catheter ablations with cardiac magnetic resonance imaging (MRI) done before and 3 months after each of the ablations from 2010 to 2021. The rate of change in peak longitudinal atrial strain (PLAS) assessed LA function. Additionally, a sub-study of 36 patients who underwent an extra MRI before the second ablation, gave us an additional time segment to evaluate the basis of change in PLAS. In the two-ablation, three MRI sub-study 1, the PLAS percent change rate was similar before and after the first ablation (r11 = -0.9 ± 3.1%/year, p = 0.771). However, the strain change rate from postablation 1 to postablation 2 was significantly worse (r12 = -23.7 ± 4.8%/year, p < 0.001). In the sub-study 2 with four MRIs, all three rates were negative, with reductions from postablation 1 to pre-ablation 2 (r22 = -13.3 ± 2.6%/year, p < 0.001) and from pre-ablation 2 to postablation 2 (r23 = -8.9 ± 3.9%/year, p = 0.028) being significant. The present study suggests that the more ablations performed, the more significant the decrease in the postablation mechanical function of the LA. The natural progression of AF (strain change from postablation 1 to pre-ablation 2) had a greater negative influence on LA mechanical function compared to the second ablation itself suggesting that second ablation in patients with recurrence after first ablation is an effective strategy even from the LA mechanical function aspect.

Syntheses, Structures, and Thermal Decomposition Kinetics of Two Silver/Copper‐Based Coordination Compounds with 1,2,4‐Triazole‐Containing Ligand

AbstractIn this work, two silver/copper‐based coordination compounds {[Ag(tty)]⋅NO3}n (1) and {[Cu2Cl2(tty)2(H2O)2]⋅Cl⋅NO3 ⋅ (H2O)2}n (2) (tty=1,2,4,5‐tetra(1H‐1,2,4‐triazol‐1‐yl))benzen), were synthesized using the different metal salts under the hydrothermal condition. Structural analyses show that compound 1 features tilted L‐shaped 1D Ag chains structure and compound 2 presents a 2D layer with free Cl−, NO3− and water molecules. The experimental results reveal that 1 displays considerably high thermal stability with the thermal decomposition temperature above 337 °C compared to compound 2, which further exemplifies that the framework structures may have a crucial effect on the resultant thermal stability. Additionally, the non‐isothermal kinetics parameters were evaluated at different heating rates by Kissinger's and Ozawa‐Doyle's methods. Importantly, the kinetic triplets (the apparent activation energy (Ea), the preexponential factor (logA) and the mechanism function (ƒ(α)) and the related thermodynamic parameters (the Gibbs energy of activation, ▵G≠, the enthalpy of activation, ▵H≠, and the entropy of activation, ▵S≠) of the thermal decomposition processes are discussed and calculated in detail.

Left fascicular pacing is not inferior to left bundle branch pacing in preserving ventricular mechanical synchrony and cardiac function

Abstract Background Left bundle branch pacing (LBBP) has emerged as a more physiological alternative to right ventricular pacing.However, capturing the pre-divisional LBB is not easy to accomplish. This study investigates if left fascicular pacing(LFP), defined as the capture of one of the LBB fascicles, could achieve comparable left ventricular (LV) mechanical synchronicity and cardiac function compared to LBBP. Methods Thirty-one patients with pacing indication for bradycardia were retrospectively collected: LBBP was successfully performed in 13 patients and 18 achieved LFP. All patients underwent echocardiography before and after implantation and at one-year follow-up. Left ventricular (LV) volumes, ejection fraction (EF) and global longitudinal strain (GLS) were measured. The lateral-septal (LW-SW) work difference was used as a measure of mechanical dyssynchrony. Septal flash, apical rocking and septal strain patterns were also assessed. Results Although LW-SW work difference were significantly higher in the LBBP groups than that in the LFP group at baseline(272±269 mmHg*% vs 25±279mmHg*%,p=0.02), a similar increase in LW-SW work difference was observed during follow-up(199±342 mmHg*% vs 371±384mmHg*%,p=0.21). In addition, both LFP and LBBP induced septal flash or apical rocking in some patients, and resulted in subtle changes in strain patterns, which were not significantly different between groups. At one year follow-up, LV ejection fraction (EF) remained almost unchanged in both LBBP and LFP patients(ΔLVEF: 1.1+3.1% vs -0.3±4.8%,p=0.35) , and global longitudinal strain (GLS) was slightly and equally decreased in LFP compared to LBBP (ΔLVGLS: -1.6±2.3% vs -1.2±2.7%,p=0.69). Conclusion LFP and LBBP did not differ in mechanical dyssynchrony or LV remodelling.

Left ventricular absolute myocardial work measured by cardiovascular magnetic resonance: a proof-of-concept

Abstract Background Myocardial Work Index (MWI) is a load-independent and non-invasive method for assessing cardiac systolic function [1]. However, MWI does not directly measure absolute myocardial work (AMW), since it does not consider the effect of variations in left ventricular (LV) wall thickness and regional wall curvature. Therefore, a direct comparison of MWI results may be difficult. Cardiovascular magnetic resonance (CMR) is the gold standard for assessing the LV geometry and therefore can be used to directly measure the AMW by calculating the area of the stress-strain curve. Purpose This study aims to measure and compare CMR-based AMW in three groups with different work profiles: healthy subjects, patients with ST-elevation myocardial infarction (STEMI), and patients with severe aortic valve stenosis (AS). Additionally, it aims to compare AMW with strain to provide additional insights into remodelling. Methods A total of 78 participants were included in our study; 38 healthy subjects from the CENS study [2], 19 STEMI patients 3-7 days post-PCI from the ASSAIL study [3], and 21 patients with AS scheduled for operation. Collected data were not adjusted for age or sex. Stress was estimated using Laplace’s equation [4]. Intra-ventricular pressure was calculated from brachial cuff pressure as previously described [5]. Mid-ventricular circumferential strain was calculated using CMR-based tissue phase mapping [4]. AMW was calculated both as Myocardial Work per unit endocardial Surface (MWS, in J/m^2) and per unit Mass (MWM, in mJ/g), both serving as measurements of global circumferential systolic function. Results Mean circumferential strain did not differ significantly between the AS and the healthy groups (p=0.37), but it was significantly lower in the STEMI group compared to the healthy group (p&amp;lt;0.001). MWS was significantly higher in the AS group (p&amp;lt;0.001) and lower in the STEMI group (p&amp;lt;0.001) compared the healthy group. This suggests that each unit of endocardial surface in the myocardium performed, on average, more work in the AS group and less work in the STEMI group relative to the healthy group. MWM was not significantly different between the AS and the healthy group (p=0.74), while in the STEMI group, it was significantly lower (p=0.001) than in healthy subjects. Conclusion Our results indicate that in patients with AS, the myocardium did more work per unit surface, while each gram of the myocardium did the same amount of work. This is likely due to concentric hypertrophy and the increase of afterload. In contrast, in patients with STEMI, the myocardium did, on average, less work per unit surface and per mass. This is expected due to the direct loss of mechanical function in the infarcted myocardium. Our results indicate that AMW enhances traditional strain analysis, improves myocardial function evaluation, and may provide deeper insight into myocardial remodeling in diverse cardiac conditions.

Echocardiographic associates of impaired sleep quality in patients with anxiety and depression

Abstract Objective Sleep health, mental health and cardiovascular health are multidimensional constructs that are strongly associated with each other. Anxiety and depression are the most common psychiatric diseases in the community and frequently comorbid in routine clinical practice. This study sought to investigate whether there is an association between sleep quality and echocardiographic parameters in patients with anxiety and/or depression. Methods The clinical and instrumental find­ings of consecutive patients diagnosed with either of anxiety disorders and/or depressive disorders and underwent cardiac examination in our tertiary center on the same day were retrospectively reviewed. The diagnosis was made by a psychiatrist according to the criteria listed in the fifth edition of The Diagnostic and Statistical Manual of Mental Disorders. Afterwards, Hospital Anxiety and Depression Scale (HADS) and Pittsburgh Sleep Quality Index (PSQI) were applied to patients to assess symptom severity and sleep quality, respectively. Subsequent to psychiatric examination, the patients underwent echocardiographic examination that includes two-dimensional conventional echocardiography, tissue doppler imaging (TDI) echocardiography, atrial conduction times, and left atrium (LA) volumes and functions. Results The final study population consisted of 167 patients and divided into two groups according to their PSQI score: PSQI&amp;lt;5 (normal sleep quality) (n=32) and PSQI≥5 (impaired sleep quality) (n=135). Aortic diameter, left ventricular (LV) end-systolic diameter, LV end-diastolic and -systolic volume, LV stroke volume and LV stroke volume index, LV outflow tract velocity–time integral (LVOT-VTI), and LA conduit volume calculations were significantly lower in patients with impaired sleep quality compared to patients with normal sleep quality. The other echocardiographic parameters including LV systolic functions, doppler and TDI echocardiography indices, atrial conduction times, atrial mechanical functions including LA function index (LAFI) were similar among groups. Correlation analysis yielded a negative, weak but statistically significant correlation between LAFI and PSQI score (r=-0.17, p=.030) (Figure 1A). Left intra-AEMD positively and significantly correlated with PSQI score at a weak level (r=0.16, p=.043) (Figure 1B). Aortic diameter, LV stroke volume index, LVOT-VTI and conduit volume were determined as echocardiographic parameters significantly associated with impaired sleep quality in univariate analysis. Among these parameters, only conduit volume remained as significant and independent associate of impaired sleep quality in multivariate logistic regression analysis (Odds ratio:0.91, 95% Confidence interval:0.85-0.98, p=.018) (Table 1). Conclusion There is an independent association between LA conduit volume and impaired sleep quality in patients suffering from anxiety and/or depressive disorders.Figure 1Table 1

Comparison of left atrial and left atrial appendage mechanics in patients with ischaemic strokes of different aetiologies

Abstract Background Left atrial (LA) and left atrial appendage (LAA) mechanical dysfunction account for an increase in cardioembolic stroke risk in atrial fibrillation (AF), and more recently in individuals in sinus rhythm (SR). However, the exact contribution of LA and LAA to the pathogenesis of thromboembolic events is not fully understood. Here, we aimed to assess the alterations of LA and LAA mechanics in different stroke subtypes. Methods We recruited three groups of participants: patients with paroxysmal or persistent AF with a history of stroke (AF-stroke, n=69,respectively), individuals in SR with no history of AF but with acute ischaemic stroke(non-AF stroke,n=46); individuals with no history of AF or stroke(control group,n=17). Patients with AF were further categorized into sinus rhythm group (AF-stroke-SR,n=24) and AF rhythm group(AF-stroke-AF, n=45) according to the rhythm at the time of echocardiography. Using speckle-tracking echocardiography, global longitudinal strain (GLS) and mechanical dispersion (MD) of LA and LAA were measured in all patients. Mechanical dispersion was defined as the standard deviation of the time to peak of the regional strain corrected by R-R interval. Results Patients with AF-stroke demonstrated prominently impaired LA and LAA mechanics(LA GLS: 20±6%(AF-stroke-SR),11±4%(AF-stroke-AF); LA MD: 9±3%,11±3%; LAA GLS: 15±3%,11±4% ; LAA MD: 11±4%,12±3% ,respectively) compare with those with non-AF stroke and controls (LA GLS:35±8%, 41±11%;LA MD,6±2%, 4±2%; LAA GLS:21±5%, 23±7%; LAA MD:8±4%, 7±3%,respectively) (all p&amp;lt;0.01). Interestingly, LA and LAA mechanical function was not significantly different between patients with non-AF strokes and the control group. In multivariable analysis, only AF-strokes were independently associated with LA and LAA GLS after adjusting for age and comorbidities (both P&amp;lt;0.01). Conclusions Mechanical dysfunction of LA and LAA might play a greater role in pathogenesis of strokes related to AF rather than non-AF strokes.

Muscle‐Inspired Robust Anisotropic Cellulose Conductive Hydrogel for Multidirectional Strain Sensors and Implantable Bioelectronics

AbstractIntegrating superior mechanical performance, anisotropic conductivity, and biocompatibility into conductive hydrogels as all‐in‐one human‐machine interaction device remains challenging. Herein, by mimicking the anisotropic structures of human muscles, a robust anisotropic conductive hydrogel is developed by initially aligning polyvinyl alcohol with polypyrrole decorated cellulose nanofibrils to form an anisotropically oriented polymer networks, followed by post‐crosslinking with tannic acid (TA). Introducing TA into hydrogel network permanently secures its hierarchically anisotropic structure through multiple hydrogen bonds, thus endowing the hydrogel with exceptional mechanical properties (tensile strength of 11.41 MPa, toughness of 12.44 MJ m−3), anisotropic adhesive property, and direction‐dependent conductivity. With these attributes, a hydrogel strain sensor with excellent multidirectional sensitivity is developed, enabling stable monitoring of multi‐degrees of freedom joint movements in the human body and facilitating the control of a multiaxial virtual robot manipulator. Moreover, the in vitro/vivo tests demonstrate exceptional biocompatibility and anti‐biofouling properties of the as‐prepared hydrogel sensor, maintaining stable electronic response signals for over 14 days after successful implantation into the Achilles tendon of mice. Overall, this study presents a promising approach for designing conductive hydrogels with superior mechanical properties and anisotropic functionality for emerging applications in both in vitro and in vivo human‐machine interface materials.

Mechanical, thermal, and microstructure analysis of 3D printed polyolefin elastomer-acrylonitrile butadiene styrene blends for tunable mechanical properties

Fused Deposition Modeling (FDM) has emerged as a cost-effective and user-friendly technique that has garnered significant attention in recent years. However, challenges persist when printing soft materials using FDM technology. This study proposes a solution by blending a soft polyolefin elastomer (POE) with a stiffer material, acrylonitrile butadiene styrene (ABS). A comprehensive experimental investigation utilizing a direct pellet printing method was conducted to 3D print POE-ABS blends in various ratios (10%, 30%, and 50% ABS content). The study encompassed material preparation, 3D printing, SEM (Scanning Electron Microscopy) analysis, Dynamic Mechanical Thermal Analysis (DMTA), uniaxial tensile testing, and compression testing to assess the mechanical properties and energy absorption capabilities of the 3D printed blends. The results of the DMTA showed that the blends with a higher amount of ABS have a larger area under the Tan δ curve, indicating their ability to absorb more energy. The SEM images revealed that as the proportion of ABS increases, the gaps between layers and beads become smaller. The mechanical properties of the pure printed POE, such as its elongation at break and tensile strength, were 2138% and 2.83 MPa, respectively. However, as the ABS content increased, the samples exhibited more rigid behavior, with a final transition to 50/50 ratio resulting in 9.4 MPa tensile strength and 160% elongation at break. The energy absorption test demonstrated that the sample with 30% ABS content has the highest energy absorption capability among all the tested samples. This research underscores the potential of blending soft and stiff materials to tailor properties for additive manufacturing applications, emphasizing the significance of material composition in achieving desired mechanical performance, printability, and functionality in printed objects.

Mechanical Viability and Functionality Assessment of a New Sutureless Endoluminal Microvascular Device: A Preliminary In Vivo Rabbit Study.

Our group has developed a new nitinol endoluminal self-expandable device for microvascular anastomosis. It attaches to each vessel ending with opposite directed microspikes and reaches complete expansion at body temperature, using the nitinol shape memory capacity. The main purpose of this first in vivo trial is to evaluate the mechanical viability of the device and its immediate and early functionality. A recuperation study with seven New Zealand White rabbits was designed. A 1.96 mm outer diameter prototype of the new device was placed on the right femoral artery of each rabbit. Each anastomosis was reassessed on the seventh postoperative day to reevaluate the device function. The average anastomosis time with the new device was 18 min and 45 seg (±0.3 seg). It could be easily placed in all the cases with an average of 1.14 (1) complementary stitches needed to achieve a sealed anastomosis. Patency test was positive for all the cases on the immediate assessment. On the 1 week revision surgery, patency test was negative for the seven rabbits due to blood clot formation inside the device. The new device that we have developed is simple to use and shows correct immediate functionality. On the early assessment, the presence of a foreign body in the endoluminal space caused blood clot formation. We speculate that a heparin eluting version of the device could avoid thrombosis formation. We consider that the results obtained can be valuable for other endoluminal sutureless devices.

Design and Implementation of a Computer-Controlled Hybrid Oscillatory Ventilator.

During mechanical ventilation, lung function and gas exchange in structurally heterogeneous lungs may be improved when volume oscillations at the airway opening are applied at multiple frequencies simultaneously, a technique referred to as multifrequency oscillatory ventilation (MFOV). This is in contrast to conventional high-frequency oscillatory ventilation (HFOV), for which oscillatory volumes are applied at a single frequency. In the present study, as a means of fully realizing the potential of MFOV, we designed and tested a computer-controlled hybrid oscillatory ventilator capable of generating the flows, tidal volumes, and airway pressures required for MFOV, HFOV, conventional mechanical ventilation (CMV), as well as oscillometric measurements of respiratory impedance. The device employs an iterative spectral feedback controller to generate a wide range of oscillatory waveforms. The performance of the device meets that of commercial mechanical ventilators in volume-controlled mode. Oscillatory modes of ventilation also meet design specifications in a mechanical test lung, over frequencies from 4 to 20 Hz and mean airway pressure from 5 to 30 cmH2O. In proof-of-concept experiments, the oscillatory ventilator maintained adequate gas exchange in a porcine model of acute lung injury, using combinations of conventional and oscillatory ventilation modalities. In summary, our novel device is capable of generating a wide range of conventional and oscillatory ventilation waveforms with potential to enhance gas exchange, while simultaneously providing less injurious ventilation.

Specific Degradation of the Mucin Domain of Lubricin in Synovial Fluid Impairs Cartilage Lubrication.

Progressive cartilage degradation, synovial inflammation, and joint lubrication dysfunction are key markers of osteoarthritis. The composition of synovial fluid (SF) is altered in OA, with changes to both hyaluronic acid and lubricin, the primary lubricating molecules in SF. Lubricin's distinct bottlebrush mucin domain has been speculated to contribute to its lubricating ability, but the relationship between its structure and mechanical function in SF is not well understood. Here, we demonstrate the application of a novel mucinase (StcE) to selectively degrade lubricin's mucin domain in SF to measure its impact on joint lubrication and friction. Notably, StcE effectively degraded the lubricating ability of SF in a dose-dependent manner starting at nanogram concentrations (1-3.2 ng/mL). Further, the highest StcE doses effectively degraded lubrication to levels on par with trypsin, suggesting that cleavage at the mucin domain of lubricin is sufficient to completely inhibit the lubrication mechanism of the collective protein component in SF. These findings demonstrate the value of mucin-specific experimental approaches to characterize the lubricating properties of SF and reveal key trends in joint lubrication that help us better understand cartilage function in lubrication-deficient joints.

Multi-Gradient Bone-Like Nanocomposites Induced by Strain Distribution.

The heterogeneity of bones is elegantly adapted to the local strain environment, which is critical for maintaining mechanical functions. Such an adaptation enables the strong correlation between strain distributions and multiple gradients, underlying a promising pathway for creating complex gradient structures. However, this potential remains largely unexplored for the synthesis of functional gradient materials. In this work, heterogeneous bone-like nanocomposites with complex structural and compositional gradients comparable to bones are synthesized by inducing strain distributions within the polymer matrix containing amorphous calcium phosphate (ACP). Uniaxial stretching of composite films exerts the highest strain in the center, which ceases gradually toward the sides, resulting in the gradual decrease of polymer alignment and crystallinity. Simultaneously, the center with high orientation traps most ACP during stretching due to the nanoconfinement effect, which in turn promotes the formation of aligned nanofibrous structures. The sides experiencing the least strain have the smallest amounts of ACP, characteristic of porous architectures. Further crystallization of ACP produces oriented apatite nanorods in the center with a larger crystalline/amorphous ratio than the sides because of template-induced crystallization. The combination of structural and compositional gradients leads to gradient mechanical properties, and the gradient span and magnitude correlate nicely with strain distributions. Accompanying bone-like mechanical gradients, the center is less adhesive and self-healable than the sides, which allows a better recovery after a complete cutting. Our work may represent a general strategy for the synthesis of biomimetic materials with complex gradients thanks to the ubiquitous presence of strain distributions in load-bearing structures.

In-depth exploration of waste printed circuit boards pyrolysis: Real-time products characteristics, kinetics parameter optimization and reaction mechanism

Pyrolysis is a promising technology for recycling waste printed circuit boards (WPCBs). This study delves into a real-time examination of the volatiles emitted from WPCBs during pyrolysis using thermogravimetric analysis coupled with Fourier transform infrared spectroscopy/mass spectrometry (TG-FTIR/MS), offering an in-depth analysis of the entire pyrolysis mechanism. An optimized kinetic model for printed circuit board (PCB) pyrolysis is developed by the shuffled complex evolution (SCE) algorithm. Results indicate that the main pyrolysis products are phenol and alkyl-substituted phenols, along with hydrogen bromide (HBr) and bromophenols. Bromides exhibit an earlier onset and peak temperature compared to phenolic products. The pyrolysis process can be divided into two stages: initial depolymerization of the resin body into macromonomers, followed by prevalent alkyl removal, homolytic reactions, and isomerization. The apparent activation energy (E) is 155.32 kJ/mol, the pre-exponential factor (ln(A)) is 29.77 min−1, and the kinetic mechanism function is described by (1‐α)2.02. This study provides crucial knowledge to advance the technology of WPCBs pyrolysis.