Mechanical Compression Research Articles

Chest Compressions Synchronized to Native Cardiac Contractions are More Effective than Unsynchronized Compressions for Improving Coronary Perfusion Pressure in a Novel Pseudo-PEA Swine Model

ABSTRACT OBJECTIVES Pulseless electrical activity (PEA) arrest, which includes pseudo-PEA, is increasingly common and survival remains dismal. We hypothesized that mechanical chest compressions synchronized to native cardiac contractions improve coronary perfusion pressure (CPP) during pseudo-PEA resuscitation. METHODS We developed a model of pseudo-PEA by infusing high dose esmolol intravenously into anaesthetized, intubated, and central arterial and venous catheterized swine to a goal of 45 mm Hg mean arterial blood pressure (MAP). We performed a randomized unblinded repeated crossover trial by administering alternating synchronized and unsynchronized chest compressions for 52 seconds preceded by 8 second breaks consecutively 4 times. We repeated the protocol approximately 4 times with 1 minute breaks. Synchronized compressions were provided 1:1 with native contractions during systole and unsynchronized compressions were provided at 100 beats per minute (BPM). We measured average CPP, MAP, and heartrate (HR) for 5 beats immediately preceding the chest compression onset and for 30 seconds 10 seconds after compression onset. We computed the difference in continuous CPP during compressions compared to the immediately preceding baseline for each interval. We developed a mixed linear model with outcome average CPP during compressions minus baseline, fixed variable compression type, and random variable animal. RESULTS We included 6 animals. Mean baseline HR was 76.0 BPM, MAP 49.9, and CPP 36.2. Chest compressions increased CPP from baseline an average 1.7 mm Hg when unsynchronized and 5.6 mm Hg synchronized. The adjusted difference was 4.0 mm Hg (95% CI 2.4–5.5). CONCLUSIONS Synchronized chest compressions increased CPP 4.0 mm Hg (135%) more than unsynchronized compressions despite a lower compression rate in medication-induced pseudo-PEA. Further refinement and eventual application to patients suffering pseudo-PEA arrest appear warranted.

Liver sinusoidal endothelial cells: Friend or foe in metabolic dysfunction- associated steatotic liver disease/metabolic dysfunction-associated steatohepatitis.

Metabolic dysfunction-associated steatotic liver disease (MASLD) is the predominant liver disease and is becoming the paramount contributor to end-stage liver disease and liver-related deaths. Liver sinusoidal endothelial cells (LSECs) located between the hepatic parenchyma and blood from viscera and gastrointestinal tract are the gatekeepers for the hepatic microenvironment and normal function. In normal physiological conditions, LSECs govern the substance exchange between hepatic parenchyma and blood through dynamic regulation of fenestration and maintain the quiescent state of Kupffer cells (KCs) and hepatic stellate cells. In MASLD, lipotoxicity, insulin resistance, gastrointestinal microbiota dysbiosis, and mechanical compression caused by fat-laden hepatocytes result in LSECs capillarization and dysfunction. The altered LSECs progressively shift from healer to injurer, exacerbating liver inflammation and advancing liver fibrosis. This review focuses on the deteriorative roles of LSECs and related molecular mechanisms involved in MASLD and their contribution to metabolic dysfunction-associated steatohepatitis (MASH) and liver fibrosis development and progression. Furthermore, in this review, we propose that targeting LSECs dysfunction is a prospective therapeutic strategy to restore the physiological function of LSECs and mitigate MASLD progression.

The interplay between compression mechanisms and compaction pressure in relation to the loss of tabletability of dry granulated particles

The interplay between compression mechanisms and compaction pressure in relation to the loss of tabletability of dry granulated particles

Mechanical bionic compression resistant fiber/hydrogel composite artificial heart valve suitable for transcatheter surgery

Mechanical bionic compression resistant fiber/hydrogel composite artificial heart valve suitable for transcatheter surgery

Mechanical chest compression increases intrathoracic hemorrhage complications in patients receiving extracorporeal cardiopulmonary resuscitation

Mechanical chest compression increases intrathoracic hemorrhage complications in patients receiving extracorporeal cardiopulmonary resuscitation

Enhancing fabric TENG performance through optimized compression mechanics in smart IoT carpets, for energy harvesting and movement sensing

Enhancing fabric TENG performance through optimized compression mechanics in smart IoT carpets, for energy harvesting and movement sensing

Reversible atrioventricular block during transcatheter ventricular septal defect closure – a serial case report

Background: The transcatheter ventricular septal defect procedure is a sophisticated intervention that carries potential complications, such as complete heart block. We report two cases of patients who experienced total AV block during transcatheter VSD closure and were successfully treated with steroids and atropine. Case Presentation: Perimembranous VSD was found in a 19-year-old military recruit. A baseline 12-lead EKG showed sinus rhythm and no conduction delays. Echocardiography revealed a 6-9 mm perimembranous VSD. Then the VSD was closed with a VSD Occluder No 10-8. ECG monitor and echocardiography showed a complete atrioventricular block during the procedure. Fortunately, 1mg atropine and 125mg methylprednisolone overcame this. Recurrent atrioventricular block and VSD were not found after the procedure. A 33-year-old male patient was diagnosed with a perimembranous VSD during routine screening. Initial 12-lead electrocardiography was unremarkable, while echocardiographic evaluation revealed a 3-5 mm perimembranous VSD. Transcatheter closure was performed using a VSD Occluder device (No. 10-8). Hemodynamic monitoring and echocardiography demonstrated a complete atrioventricular (AV) block intraoperatively. Pharmacological intervention with 1 mg atropine and 125 mg methylprednisolone resolved the conduction disturbance. Despite this transient complication, the procedure continued with successful device deployment. Post-procedural assessment confirmed complete VSD closure with no residual shunt or persistent AV conduction abnormalities. Conclusions: In the context of transcatheter closure of ventricular septal defects, there exists a risk of atrioventricular block, which can be precipitated by mechanical trauma or compression from the delivery system or device. Ensuring the appropriate sizing of the device is pivotal in minimizing this risk. Continuous heart rhythm monitoring is indispensable during both short-term and long-term follow-up periods. Keywords: Ventricular septal defect, Atrioventricular block, transcatheter device closure, case report

The spatial buildup of nonlinear compression in the cochlea

In the mammalian cochlea, the transduction from vibrations to inner hair cell receptor currents is preceded by a stage of mechanical pre-processing that involves a rapid, strongly nonlinear compression. The mechanisms by which the cochlea realizes this dynamic compression are still poorly understood. Previous work by our group suggested that compression does not occur locally, but is realized by a cascade of weakly nonlinear elements along the cochlear partition. The resulting progressive accumulation of nonlinearity was termed the spatial buildup of compression. Here we studied mechanical compression in the basal turn of the sensitive gerbil cochlea using optical coherence tomography. We recorded vibrations at multiple positions along the length of the cochlear partition. Such longitudinal studies were virtually impossible with previous techniques. Using a tailored two-tone stimulus we quantified the spatial profile of compression. We found that the amount of compression grew gradually in an intensity-dependent fashion along our measurement stretch, as we moved apically toward the place of maximum vibration. This gradual buildup of compression was not mirrored by a gradual reduction beyond the peak. In fact the amount of compression accumulated even beyond the peak. This asymmetric pattern supports the view that mechanical compression is realized in a cascaded, distributed fashion which hinges on the traveling wave nature of cochlear vibrations.

Study of the mechanical compression properties of Rosa sterilis S.D. Shi based on FEM

Understanding the mechanical properties of Rosa sterilis S.D. Shi is important for the design and improvement of related mechanical equipment for planting, picking, processing, and transporting Rosa sterilis S.D. Shi. Compression damage is a common form of mechanical damage in agricultural products, especially during automated mechanical production. Therefore, this study establishes a three-dimensional model of seedless prickly pear fruit based on image processing technology and analyzes the compressive mechanical properties of seedless prickly pear under different directions through experiments combined with finite element method simulation. In both simulation and actual results, the average correlation coefficients were found to be 0.99 and 0.98 for the vertical compression direction and the horizontal compression direction, respectively. The above results show that our finite element compression model can provide a comprehensive understanding of the mechanical properties of Rosa sterilis S.D. Shi fruits under different directional loads. There is significant directional sensitivity in the compression resistance of Rosa sterilis S.D. Shi fruits have horizontal compression resistance greater than vertical compression resistance. The results of this study are of great significance for the development of mechanized automation in the Rosa sterilis S.D. Shi industry and for ensuring the quality of Rosa sterilis S.D. Shi fruits.

Description of current status of implementation and management of cardiac arrest in China

Variation in the incidence, survival rate and factors associated with survival after cardiac arrest in China is reported. Some studies have tried to fill the knowledge gap regarding the epidemiology of cardiac arrest in China but were unable to identify reasons for the reported differences. Therefore, the purpose of this study was to describe Chinese management of cardiac arrest, particularly from the perspective of compression, ventilation, monitoring, treatment, and extracorporeal cardiopulmonary resuscitation. An online questionnaire with 56 questions was designed about demographic characteristics, management of cardiac arrest, compression, ventilation, treatment and medicine, as well as advanced life support and resuscitation skill training. A total of 814 copies of questionnaire were received from 23 provinces, 4 autonomous regions and 4 municipalities of China. Results were combined with official information on population density. Throughout China, hospitals resuscitate according to the guideline, however, there are still differences varies in implement with regard to chest compression, ventilation, medicine, monitoring, as well as advanced life support and resuscitation skills training because of economical and developmental level from different regions. All the startup of chest compression is manual, whereas mechanical compression instruments are increasingly involved in sequential resuscitation. Most of clinicians rotate during resuscitation every five cycles other than the guideline recommends every 2 min or when they are tired. About half of the participants don’t build the advanced airway rather than use bag valve mask to ventilate, and 75% of the rest use mechanical ventilation whether they succeed to ROSC. Most of rescuers choose endotracheal intubation which is consistent with many other clinical trials results. Various compression feedback devices play increasingly significant roles in assessment of ROSC. More and more regional hospitals have access to ECPR and implement TTM, but still lead to various divergences. Thus, more elaborate clinical trials need to be designed to verify and explore every procedure in the CPR life cycle.

RPM-ETC: A Risk Prediction Model for Elevators Based on Transformer and Self-Temporal Compression Mechanism

Elevators play an indispensable role in modern urban life. Ensuring the safe operation of elevators is crucial due to the severe consequences of malfunctions. Traditional maintenance methods are costly and may not comprehensively capture potential faults. Leveraging deep learning technologies, this study proposes a Risk Prediction Model based on Elevator Transformer and Self-temporal Compression Mechanism (RPM-ETC). By analyzing rich operational data, the model predicts potential faults before significant issues arise. The model utilizes the Transformer architecture to effectively capture temporal relationships and employs a temporal compression mechanism to enhance prediction efficiency. Additionally, it uses Enhanced Positional Encoding to prevent the the loss of temporal information as network depth increases. Based on the obtained performance results, the model achieves an accuracy of 86.3% and a frame-per-second (FPS) rate of 388.7, accurately and rapidly predicting elevator faults. Additionally, this paper provides a comprehensive dataset for elevator operation prediction to facilitate further research.

Physically cross-linked cellulose nanofiber (LCNF/CNF) hydrogels: impact of the composition on mechanical and swelling properties

Lignocellulose nanofibers (LCNFs) are highly regarded for their ability to significantly enhance the rigidity of formed structures. When integrated into cellulose nanofiber (CNF) hydrogels, they hold substantial promise in augmenting mechanical strength, as well as improving adsorption capacity. Herein, the preparation of hydrogels from an aqueous suspension of CNFs and LCNFs extracted from eucalyptus cellulose pulp through a homogenization process is outlined. Suspensions of different concentrations were prepared to assess the influence of lignin and nanofiber content on the properties of the hydrogels. The hydrogels cellulose nanofibers (HCNF) and lignocellulose nanofibers (HLCNF) were formed through a freeze–thaw process, revealing an enhancement in rigidity with increasing nanofiber concentration. DFT (density functional theory) calculations illustrated the cross-linking mechanism between cellulose chains induced by the crystallization of water molecules, thus, corroborating the postulated hydrogel formation mechanism. Microstructural analysis revealed honeycomb-shaped matrices in longitudinal sections, with HLCNF hydrogels presenting less smooth walls. Studies on water adsorption capacity showed rapid swelling in both hydrogels, correlated with the nanofiber content reaching 8750% and 5500% for HLCNF and HCNF, respectively. HLCNF hydrogels exhibited higher adsorption capacity due to the influence of lignin on cross-linking rates. Mechanical compression tests demonstrated exceptional resilience in all hydrogels. Despite having a lower cross-linking density compared to hydrogels made from 2 wt.% cellulose nanofibers, hydrogels composed of 2 wt.% lignocellulose nanofibers exhibited a Young’s modulus of 2.83 kPa. This underscores the superior mechanical properties of lignin-based hydrogels, highlighting the effect of lignin on the hydrogel matrix.

Variable-Length Coding with Zero and Non-Zero Privacy Leakage

A private compression design problem is studied, where an encoder observes useful data Y, wishes to compress them using variable-length code, and communicates them through an unsecured channel. Since Y are correlated with the private attribute X, the encoder uses a private compression mechanism to design an encoded message C and sends it over the channel. An adversary is assumed to have access to the output of the encoder, i.e., C, and tries to estimate X. Furthermore, it is assumed that both encoder and decoder have access to a shared secret key W. In this work, the design goal is to encode message C with the minimum possible average length that satisfies certain privacy constraints. We consider two scenarios: 1. zero privacy leakage, i.e., perfect privacy (secrecy); 2. non-zero privacy leakage, i.e., non-perfect privacy constraint. Considering the perfect privacy scenario, we first study two different privacy mechanism design problems and find upper bounds on the entropy of the optimizers by solving a linear program. We use the obtained optimizers to design C. In the two cases, we strengthen the existing bounds: 1. |X|≥|Y|; 2. The realization of (X,Y) follows a specific joint distribution. In particular, considering the second case, we use two-part construction coding to achieve the upper bounds. Furthermore, in a numerical example, we study the obtained bounds and show that they can improve existing results. Finally, we strengthen the obtained bounds using the minimum entropy coupling concept and a greedy entropy-based algorithm. Considering the non-perfect privacy scenario, we find upper and lower bounds on the average length of the encoded message using different privacy metrics and study them in special cases. For achievability, we use two-part construction coding and extended versions of the functional representation lemma. Lastly, in an example, we show that the bounds can be asymptotically tight.

Effect of Zirconium Silicate Reinforcement on Aluminum 7075; Mechanical Properties, Thermomechanical Analysis and Vibrational Behavior

Aluminum 7075 alloys are widely utilized in aerospace, transportation, and marine industries due to their high strength and low density. However, further research is needed to understand their mechanical, thermomechanical, and vibrational behaviors when reinforced. This study focuses on the development of Al 7075 composites reinforced with zirconium silicate (ZrSiO4), processed via sand stir casting. The mechanical properties, including tensile, compression, and impact strength, as well as thermomechanical and vibrational behaviors, were thoroughly investigated. A planetary ball mill was used to mix ZrSiO4 with a wettability agent, and the results indicated that the addition of ZrSiO4 with the wettability agent significantly enhanced the mechanical properties. Fourier Transform Infrared Spectroscopy (FTIR) was employed to identify the compounds formed after adding the reinforcement and wettability agent. Scanning Electron Microscope (SEM) images and Energy-dispersive X-ray (EDX) analysis revealed a uniform distribution of the particles within the matrix. The tensile, compression, and impact strengths increased by 20%, 21%, and 19%, respectively, with the addition of 8 wt% ZrSiO4; however, strain decreased. Additionally, heat treatment further enhanced the mechanical properties of the composites. The thermomechanical properties showed improvement even at elevated temperatures, and the damping factor was enhanced with the addition of ZrSiO4. The elemental composition of the reinforced composites was analyzed using EDX, confirming the presence of the reinforcement. This research highlights the potential of Al 7075-ZrSiO4 composites for improved performance in various applications.

Microstructure evolution and bonding mechanism of hot compression bonding joint of reduced activation ferritic/martensitic steel

Microstructure evolution and bonding mechanism of hot compression bonding joint of reduced activation ferritic/martensitic steel

Robust underwater object tracking with image enhancement and two-step feature compression

Developing a robust algorithm for underwater object tracking (UOT) is crucial to support the sustainable development and utilization of marine resources. In addition to open-air tracking challenges, the visual object tracking (VOT) task presents further difficulties in underwater environments due to visual distortions, color cast issues, and low-visibility conditions. To address these challenges, this study introduces a novel underwater target tracking framework based on correlation filter (CF) with image enhancement and a two-step feature compression mechanism. Underwater image enhancement mitigates the impact of visual distortions and color cast issues on target appearance modeling, while the two-step feature compression strategy addresses low-visibility conditions by compressing redundant features and combining multiple compressed features based on the peak-to-sidelobe ratio (PSR) indicator for accurate target localization. The excellent performance of the proposed method is demonstrated through evaluation on two public UOT datasets.

Polyunsaturated fatty acids suppress PIEZO ion channel mechanotransduction in articular chondrocytes.

Osteoarthritis (OA) is characterized by articular cartilage degeneration, leading to pain and loss of joint function. Recent studies have demonstrated that omega-3 (ω3) polyunsaturated fatty acid (PUFA) supplementation can decrease injury-induced OA progression in mice fed a high-fat diet. Furthermore, PUFAs have been shown to influence the mechanical properties of chondrocyte membranes, suggesting that alterations in mechanosensitive ion channel signaling could contribute to the mechanism by which ω3 PUFAs decreased OA pathogenesis. Here, we hypothesized that PUFAs may alter mechanical signaling through PIEZO1 (activated by changes in membrane tension) and TRPV4 (activated by physiologic mechano-osmotic signals), as these mechanosensitive cation channels have been shown to influence OA progression. Our results demonstrated that PUFAs reduced chondrocyte sensitivity to single-cell mechanical compression and to pharmacologic agonists of PIEZO1 and TRPV4, with ω3 PUFAs having the most significant effects overall. We also found that supplementation with ω6 PUFA linoleic acid (LA) altered the biophysical properties of chondrocytes, as evidenced by increased intracellular lipid droplet formation and more rapid membrane rupture in response to hypo-osmotic shock, suggesting that LA increases chondrocyte membrane susceptibility to damage. Our findings underscore the differential impacts of specific PUFAs on chondrocyte signaling and membrane properties and provide important considerations in the development of nutritional interventions to prevent or treat OA.

Cardiac strangulation by epicardial pacing wires in adults.

Like children, adult patients with active or abandoned epicardial pacing leads are also at risk of developing life-threatening cardiac ischemia due to mechanical compression of the coronary arteries. As this complication is amenable to surgical removal, these patients require periodic evaluation for myocardial ischemia even if they are asymptomatic.

Comparison of Traditional Bougie Versus Kiwi-D Grip Bougie Technique During Mechanical Chest Compressions: A Randomized Crossover Manikin Trial

Comparison of Traditional Bougie Versus Kiwi-D Grip Bougie Technique During Mechanical Chest Compressions: A Randomized Crossover Manikin Trial

Evaluating the Performance Characteristics of Pressure Monitoring Systems.

Measuring interface pressure is currently used in a variety of settings, e.g., automotive or clinical, to evaluate pressure distribution at support surface interfaces. Commercial pressure sensing arrays are employed to monitor and visualise these pressure distributions to aid mattress or cushion selection by assessing their ability to redistribute the pressure magnitudes over vulnerable areas, e.g., the buttock. These technologies vary in configurations and measurement principles, with manufacturers supplying calibration and specifications. This study evaluated the performance of six commercial pressure sensing arrays, which differed in sensor type, configuration, and spatial resolution. Each system was subjected to mechanical compression loading on a standard cushion using a dual hemispherical 'buttock shaped' standard indenter. Pressure parameters were estimated, e.g., contact area, peak pressure index, from the sensing arrays and a comparison between measured and predicted pressure values was performed. The results showed that both contact area and pressures are influenced by the spatial resolution, with higher values associated with systems with the highest resolution. A high variability between systems was observed in the measured pressure, with sensor type driving difference between the observed and the predicted pressures. Further research is needed to establish standards and performance analysis of these technologies.