Mechanical Aspects Research Articles

Erratum: Feasibility exploration of GSH in the treatment of acute hepatic encephalopathy from the aspects of pharmacokinetics, pharmacodynamics, and mechanism

Erratum: Feasibility exploration of GSH in the treatment of acute hepatic encephalopathy from the aspects of pharmacokinetics, pharmacodynamics, and mechanism

Mechanical Analysis and Function Matrix Projective Synchronization of El-Nino Chaotic System

Abstract This study explores the mechanical aspects of the El Niño system by transforming it into a Kolmogorov type system, characterized by four types of torques known as internal, inertial, dissipation, and external. Five scenarios by varying these torques to identify the factors that lead to chaos and their physical significance are also investigated. The interactions between kinetic, potential, and Hamiltonian energies are analyzed and depicted as how these energies interact with system parameters. The study also emphasizes the benefits of conservative chaos over dissipative chaos. Particularly, it has more applications like secure communications and pseudo-random number generation. The role of force interactions and exchanges, including Casimir energy in the generation of chaos is also identified. The transition from regular to irregular orbits, and then to more chaotic states is investigated through Casimir function. It concludes that all four types of torques are necessary to induce chaos in the El Niño chaotic system. Additionally, function matrix projective synchronization between identical El-Nino chaotic systems has achieved.

Does training improve the action research skills of STEM teachers? Examining the mediating roles of attitude and knowledge

Professional development programs are essential for supporting STEM teachers in improving their teaching practices by creating engaging and effective learning experiences for students. One of the professional development programs referred to is their participation in action research training. However, while there is a growing number professional development program relating to it, there is no substantial amount of reports regarding its impact toward developing teachers' action research attitude, knowledge, and skills. In this regard, this study aims to empirically investigate the influence or impact of training programs on the development of STEM teachers' action research skills, knowledge, and attitude. Driven by Evans' (2014) concept of professionalism and professional development as a guiding framework, a structural model was proposed and validated using a quantitative cross-sectional survey design. There were 214 STEM teachers who participated in an online survey. Results revealed that from five hypotheses proposed in the structural model, four are supported except the causal path between training and action research skills. The paths between training to action research knowledge and attitude are supported as well as the paths between action research knowledge and attitude to skills. This indicates that teachers’ action research knowledge and attitude fully mediate the causal path between training and action research skills. The findings of this study imply that the focus of the training programs should go beyond the mechanical aspects or skills development of teachers but on developing their knowledge and shaping a positive attitude toward action research. Over time, both provide an enabling environment to practice and develop action research skills. The finding also offers a new perspective or guiding framework as to how teacher training programs particularly action research can be evaluated.

Maximal steered coherence in accelerating Unruh–DeWitt detectors

Quantum coherence, a fundamental aspect of quantum mechanics, plays a crucial role in various quantum information tasks. However, preserving coherence under extreme conditions, such as relativistic acceleration, poses significant challenges. In this paper, we investigate the influence of Unruh temperature and energy levels on the evolution of maximal steered coherence (MSC) for different initial states. Our results reveal that MSC is strongly dependent on Unruh temperature, exhibiting behaviors ranging from monotonic decline to non-monotonic recovery, depending on the initial state parameter Δ0. Notably, when Δ0=1, MSC is generated as Unruh temperature increases. Additionally, we observe that higher energy levels help preserve or enhance MSC in the presence of Unruh effects. These findings offer valuable insights into the intricate relationship between relativistic effects and quantum coherence, with potential applications in developing robust quantum technologies for non-inertial environments.

Performance of Steel Beams reinforced by CFRP Sheets with Fire-Retardant Coating

The objective of this study was to determine the physical, mechanical, and chemical aspects of bonding and priming Fire-Retardant Coatings (FRCs) to steel surfaces before and after fire testing. Carbon Fiber Reinforced Polymers (CFRP) have been used to strengthen steel components. Certain types of polymer systems have demonstrated high fire retardancy without additives, while others require additives to achieve optimum fire resistance. A wide range of compounds are available to enhance the fire retardant properties of these materials, characterized by their chemical nature and behavior (such as halogenated, metal complex, silicon-based, and phosphorus additives) and mode of action (either condensed or gas-phase active systems).This article provides a comprehensive overview of fire retardant additives for CFRP used in various large-scale applications, including the aerospace, automotive, railway, electronics, and civil engineering industries, as well as their fire retardant mechanisms at the microscopic, macroscopic, and nanoscale levels. In addition to fire retardant properties, this study also discusses the effects of additives on other material parameters and coatings, such as glass transition temperature, mechanical performance, and FRP processability. The primary focus is on thermoset systems, with a brief mention of thermoplastics according to the matrix compounds relevant to the FRP market size. Test results show that the direct velocity ultrasonic value varied between 3.016 and 3.618 km/s, giving an estimated compressive strength of 15.974 MPa. The standard deviation was 0.533 km/s with a relative standard deviation of 16.407%.

Steady motions of single spherical microswimmers in non-Newtonian fluids

In biological systems, microswimmers often propel themselves through complex media. However, many aspects of swimming mechanisms in non-Newtonian fluids remain unclear. This study considers the propulsion of two types of single spherical microswimmers (squirmers) in shear-thickening and shear-thinning fluids. The slip-driven squirmer propels faster/slower in shear-thickening/thinning fluids than in Newtonian fluids [C. Datt et al., J. Fluid Mech. 784, R1 (2015)]. In contrast, we discovered that a traction-driven squirmer exhibits the opposite trend, moving slower/faster in shear-thickening/thinning fluids than in Newtonian fluids. In addition, we have shown theoretically that Purcell's scallop theorem does not hold in non-Newtonian fluids when a squirmer with reciprocal surface motions is used. The present findings open up possibilities for the design of new types of microswimmers that can achieve translational motion from a single reciprocal motion in non-Newtonian fluids. Furthermore, we demonstrated that traction-driven squirmers swim faster and more efficiently in shear-thinning fluids than in Newtonian fluids. These findings highlight how the non-Newtonian rheology enhances both swimming speed and efficiency, suggesting further potential for optimizing locomotion performance otherwise impossible in Newtonian fluids.

Improving the Structure of the Electricity Demand Response Aggregator Based on Holonic Approach

A demand response (DR) aggregator is a specialized entity designed to collaborate with electricity producers, facilitating the exchange of energy for numerous stakeholders. This application is a pivotal development within the Russian Energy System as it transitions to a Smart Grid. Its successful operation relies on the advancement and implementation of more efficient strategies to manage emerging energy assets and structures. The holonic approach is a distributed management model used to handle systems characterized by random and dynamic changes. This paper analyzes the specific aspects of the electricity demand management mechanism in Russia, primarily aimed at reducing peak load in the energy system by engaging active consumers who are outside the wholesale market. The DR-Aggregator is considered both a cyber-physical system (CPS) with a cluster structure and a business process. The DR-Aggregator exhibits essential holonic properties, enabling the application of a holonic approach to enhance the efficiency of the DR-Aggregator mechanism. This approach will facilitate greater flexibility in managing the load schedules of individual holon consumers, bolster the reliability of power supply by aligning load schedules among holon consumers within the super-holon cluster, and improve the fault tolerance of the DR-Aggregator structure, providing greater adaptability of demand management services.

Multi-Tenant Architecture: A Comprehensive Framework for Building Scalable SaaS Applications

Multi-tenant architecture has emerged as a fundamental paradigm in modern software development, particularly in Software as a Service (SaaS) applications where multiple organizations share computing resources while maintaining data isolation. This article presents a comprehensive framework for understanding and implementing multi-tenant systems, focusing on essential architectural decisions and design patterns that ensure scalability, security, and resource efficiency. The article examines the evolution from single-tenant to multi-tenant architectures, analyzes various data partitioning strategies, and explores critical aspects of tenant isolation, authentication, and authorization mechanisms. The article addresses key challenges in performance optimization, resource allocation, and security implementation, providing practical insights into database design approaches and caching strategies. Through a structured approach, this article bridges the gap between theoretical concepts and practical implementation, offering developers and architects a foundation for building robust multi-tenant systems. The findings emphasize the importance of balanced architectural decisions that accommodate both technical requirements and business objectives while maintaining system integrity and tenant isolation. This article contributes to the growing body of knowledge in cloud computing and distributed systems, providing practitioners with actionable insights for developing scalable multi-tenant applications.

Medical Relief and Intimate Interaction During the Anti-Japanese War: A Review of Nicole Elizabeth Barnes's Intimate Communities

During the War of Resistance against Japan, Chinese female healthcare workers played a crucial role in the medical and health sectors. In her book Intimate Communities, the author examines various aspects of female healthcare workers' mobilization mechanisms, training systems, relief efforts, and allowances during the wartime period. Throughout this analysis, the author emphasizes the significant role female healthcare workers played in shaping modern Chinese national identity. However, this article argues that the contributions of female healthcare workers during the War of Resistance should not be idealized. Drawing on extensive historical materials and detailed analysis, the article offers new insights into wartime healthcare, providing valuable perspectives for related research.

DFT study on the mechanism and structural aspects of iron(II)-catalyzed condensation of epichlorohydrin and CO2

In this work, the catalytic cycle for the epichlorohydrin/CO2 condensation using the [η5-(C5H5)Fe(CO)(L)]X complexes where L = NH2(CH2)2PPh2 and X = I (1), Br (2), Cl (3), OTf (4) and X = Br and L = NMe2(CH2)2PPh2 (7), NH2(CH2)3PPh2 (8), Py(CH2)PPh2 (9) and Py(PPh2) (10), was studied computationally using density functional theory (DFT) at the ωB97xD/def2-TZVP level of theory. A good correlation between the optimized structures of complexes 1–4 and their respective X-ray diffraction (XRD) structures (used as experimental parameter) was found. Thus, the theoretical model was validated to study all the structures in the present work. The most thermodynamically and kinetically favored path for complexes 1–4 and 8, bearing acid hydrogens, operates outside of the coordination sphere as an ionic pathway where the ionic intermediates are stabilized through hydrogen bonds. Catalyst 2 showed the most favored energy profile among complexes 1–4 at room temperature and at 80 °C, which supports the previously reported experimental results. This first computational approach also explains the catalytic activity of complexes 1, 3 and 4. The most thermodynamically and kinetically favored path for complexes 7, 9, and 10 was the covalent pathway which works in the inner sphere, with a metal-alkoxide and a metal-carbonate as intermediates. Computationally, catalyst 10 was the most active catalyst in the entire study, showing a completely spontaneous energy profile at room temperature, being of great relevance to be investigated experimentally. Finally, the chiral R- and S-[η5-(C5H5)Fe(CO)(H(Me)N(CH2)2PPh2)]Br isomers, computationally built and optimized from complex 2, were found to be highly favored stable isomers, also attractive for experimental research.

Environment aging of lignocellulosic fibers and their composites: Visual, mechanical, and microstructural aspects

The current experimental investigation reports the performance of intra-hybrid woven jute-sisal lignocellulosic fibers, and their polypropylene composites subjected to different aging conditions (distilled water, vegetable oil, and alkali solution) for a prolonged time of 6 months. The effect of different aging mediums on chemical composition of fibers, such as, variation in cellulose and hemicellulose content was analyzed to understand the degradation mechanisms and their structure property relationship established. Significant degradation in mechanical properties was observed with exposure to alkali followed by water mediums due to degradation of fibers and thereby results in poor interfacial characteristics, while sustained durability in terms of mechanical properties was observed with oil-based aging. Highest reduction was observed in tensile strength (11 % and 34 %), flexural strength (16 % and 20 %), tensile modulus (44 % and 58 %), and flexural modulus (51 % and 52 %) after 3-month and 6 months of alkali-aging, respectively as compared to un-aged specimens. Furthermore, the visual appeal of materials was significantly affected due to aging in an alkali solution followed by distilled water, while vegetable oil has not shown any visual degradation.

Research progress of tDCS in the treatment of ADHD.

TDCS is one of the most widely used non-invasive neuromodulation techniques, which changes the excitability of local cortical tissue by applying weak continuous direct current to the scalp, effectively improves the attention and concentration of ADHD children, and improves the impulse disorder of patients, but related research is still in its infancy. Based on a review of a large number of existing literatures and an analysis of the pathogenesis and principle of ADHD, this paper summarized the research on tDCS in the treatment of ADHD in recent years from the aspects of treatment mechanism, safety and stimulation parameters, and simply compared the application of tDCS with other non-traumatic neuromodulation techniques in the treatment of ADHD. The future development direction of this technology is further discussed.

Research on innovative design of intelligent wearable products based on human machine engineering and bionics

Designing intelligent wearable products entails integrating human factors, engineering, and bionics to develop ergonomic, efficient and convenient products. Human-machine engineering is a discipline that addresses the integration between the user wearing a particular system and improving the relationship between the user and the system. At the same time, bionics is an approach that aims to mimic biological systems and structures to enhance the performance of a particular product. This research explores the possibility of integrating these specializations to design new and enhanced wearable technology products with improved usability, convenience, and flexibility for practical usage. A detailed analysis of human biomechanics and ergonomic requirements established design parameters to ensure that wearable devices could be seamlessly integrated into daily life without hindering user movement. Bionic principles, such as the flexibility of animal joints and the energy-efficient movements of natural organisms, were applied to optimize the mechanical and structural aspects of the devices. This approach enabled the creation of products that mimic the natural dynamics of the human body, offering improved responsiveness and functionality. Prototypes were developed based on human-centred design principles and evaluated using simulation and testing environments. Wearables such as exoskeletons, bright clothing, and health-monitoring devices were examined for their ability to adapt to various physical conditions and environmental changes. Results demonstrate a significant increase in user comfort, reduction in mechanical strain, and enhanced performance, validating the effectiveness of integrating human-machine engineering and bionics in wearable design.

Rapid dynamic load estimation procedure for lifting propellers in forward flight

AbstractLifting propellers operate at oblique inflow and thus encounter severe dynamic loads during forward flight, impacting structural integrity, fatigue, and vibration. Numerical optimization approaches consider aerodynamic, structural mechanical, and aeroacoustic aspects within preliminary design. To also account for dynamic loads during forward flight, a novel procedure allows their rapid estimation. Based on steady-state simulations combining strip theory and finite beam elements, aerodynamic excitation, damping, and stiffness are defined in the frequency domain. Loads are derived through a linear inflow model and quasi-steady aerodynamics. Damping and stiffness loads are linearized and transferred into matrix form to calculate the frequency response. The computationally expensive need for simulations in the time domain is thus avoided. Applicability extends to both fixed and variable pitch lifting propellers utilized in large multicopters for cargo or passenger transportation. Comparisons to time-marching simulations show good agreement with deviations of approximately 10 %. The analytical derivation yields physical insights to understand and reduce dynamic loads and their magnification due to resonance.

The TOG5 domain of CKAP5 is required to interact with F-actin and promote microtubule advancement in neurons.

Microtubule (MT) and F-actin cytoskeletal crosstalk and organization are important aspects of axon guidance mechanisms, but how associated proteins facilitate this function remains largely unknown. While the MT-associated protein, CKAP5 (XMAP215/ch-TOG), has been best characterized as a MT polymerase, we have recently highlighted a novel role for CKAP5 in facilitating interactions between MT and F-actin in vitro and in embryonic Xenopus laevis neuronal growth cones. However, the mechanism by which it does so is unclear. Here, using in vitro reconstitution assays coupled with TIRF microscopy, we report that the TOG5 domain of CKAP5 is necessary for its ability to bind to and bundle actin filaments, as well as to crosslink MTs and F-actin in vitro. Additionally, we show that this novel MT/F-actin crosslinking function of CKAP5 is possible even in MT polymerase-incompetent mutants of CKAP5 in vivo. Indeed, CKAP5 requires both MT and F-actin binding, but not MT polymerization, to promote MT-F-actin alignment in growth cones and axon outgrowth. Taken together, our findings provide mechanistic insights into how MT populations penetrate the growth cone periphery through CKAP5-facilitated interaction with F-actin during axon outgrowth and guidance. [Media: see text] [Media: see text] [Media: see text].

Biophysics of ACL injuries

Anterior Cruciate Ligament (ACL) injuries rank among the most prevalent and severe types of injuries, significantly impacting both athletes and non-athletes alike. These injuries not only result in immediate physical impairment, such as intense pain, substantial swelling, and a marked loss of mobility, but also carry long-term health consequences that can alter a person’s quality of life. Chronic pain, persistent instability, and an increased risk of developing osteoarthritis are among the lasting effects that can follow an ACL injury. An in-depth understanding of the biophysics behind ACL injuries is paramount for devising effective prevention and treatment protocols. Biophysics, which combines principles from physics with biological systems, provides crucial insights into the mechanical and structural integrity of the ACL and its susceptibility to injury under various conditions. This systematic review aims to collate and synthesize the current knowledge surrounding the biophysical mechanisms that underlie ACL injuries. The review encompasses a range of factors, including the biomechanical forces that place stress on the ligament, anatomical structures that may predispose individuals to injury, and physiological conditions that affect ligament health and resilience. Each of these factors plays a crucial role in the incidence and severity of ACL injuries. Biomechanical forces, for example, can involve sudden changes in direction or impact during physical activity, leading to excessive stress on the ACL. Anatomical factors might include variations in bone structure or ligament alignment that inherently increase the risk of injury. Additionally, physiological conditions such as muscle strength, flexibility, and overall ligament health can influence the likelihood and extent of an ACL injury. The findings of this review underscore the necessity of adopting integrated approaches in both injury prevention and rehabilitation. Such approaches must consider the multifaceted nature of ACL injuries, involving not only mechanical and anatomical aspects but also physiological and possibly even genetic factors. By emphasizing a multi-faceted understanding, interventions can be more effectively tailored to address the complex interplay of elements that contribute to ACL injuries. This holistic approach can lead to better outcomes for those at risk of or recovering from ACL injuries, enhancing the efficacy of prevention strategies and rehabilitation protocols.

Assessing the Effect of Toothpastes on Enamel Surface Roughness Using a Custom-Designed and Fabricated Toothbrush Simulator Device for Evaluation.

The primary objective of this study is to emphasize the importance of maintaining optimal oral health through regular toothbrushing practices. To achieve this objective, a custom-designed electromechanical toothbrush simulator device was developed. This innovative tool enables researchers to investigate the impact of abrasive-based whitening toothpastes on enamel surface roughness compared to brushing without toothpaste. The device design is composed of multiple systems, including mechanical, motorization, and toothpaste irrigation components. The device incorporates various components, including mechanical, motorization, and toothpaste irrigation systems. Specifically, the mechanical aspect comprises fabricated metal parts, 3D printed elements, and a load cell for measuring brushing force. The motorization section integrates a microcontroller and a stepper motor, allowing for the adjustment of brushing cycles and speed. Furthermore, the toothpaste irrigation system employs a pump with adjustable speed, along with a toothpaste canister and a waste receptacle. By providing a controlled environment for evaluating the effects of different toothpaste formulations on enamel integrity, this simulator device contributes significantly to advancements in oral care research and product development.

Mechanical performance and co2 footprint analysis: recycled aggregate polypropylene geopolymer concrete compared with conventional concrete

Abstract Geopolymer concrete (GPC) has gained significant awareness in recent years as an eco-friendly alternative to conventional concrete due to its lower CO2 emissions and utilization of industrial waste materials. The cementitious material fly ash (FA), GGBS, silica fume (SF) with incorporation of polypropylene fiber (PF), recycled aggregates (RA) further promote the strength properties of geopolymer concrete, particularly in terms of ductility and crack resistance. Exploratory tests been conducted to assess the effects of various parameters including activator type, curing conditions, fiber content, and aggregate characteristics on the mechanical behaviour and CO2 emissions of geopolymer concrete (GPC). The mechanical performance aspects like as compressive strength(45.7Mpa), flexural strength(4.78Mpa), and split tensile strength(4.12Mpa) were attain by optimum mix design GPC-FG where cement substituted with ratio of FA:GGBS:SF - 40:50:10 and compressive strength(50.4Mpa), flexural strength(5.51Mpa) and split tensile strength(4.99Mpa) were attain by optimum mix design of Polypropylene based GPC-FGP where cement substituted with ratio of FA:GGBS:SF:PF - 40:49:10:1. The optimal mix design GPC-FG and GPC-FGP are compared there is raise in compressive strength of 9.325%, flexural strength of 13.241%,split tensile strength 17.434% of GPC-FGP, along with CO2 of polypropylene fiber-based geopolymer concrete with recycled aggregates as shown 60.01% reduction of CO2 when compared with traditional concrete. The results demonstrate the potential of geopolymer concrete to achieve comparable or superior mechanical performance while significantly reducing CO2 emissions compared to conventional concrete. This research adds to sustainable construction knowledge by showcasing geopolymer concrete’s environmental benefits, mechanical strength, and potential applications in the industry and infrastructure development.

Low-Hysteresis and Tough Ionogels via Low-Energy-Dissipating Cross-Linking.

Low-hysteresis merits can help polymeric gel materials survive from consecutive loading cycles and promote life span in many burgeoning areas. However, it is a big challenge to design low-hysteresis and tough polymeric gel materials, especially for ionogels. This can be attributed to the fact that higher viscosities of ionic liquids (ILs) would increase chain friction of polymeric gels and eventually dissipate large amounts of energy under deformation. Herein, a chemical design of ionogels is proposed to achieve low-hysteresis characteristics in both mechanical and electric aspects via hierarchical aggregates formed by supramolecular self-assembly of quadruple H-bonds in a soft IL-rich polymeric matrix. These self-assembled nanoaggregates not only can greatly reinforce the polymeric matrix and enhance resilience, but also exhibit low-energy-dissipating features under stress conditions, simultaneously benefiting for low-hysteresis properties. These aggregates can also promote toughness and subsequent anti-fatigue properties in response to external cyclic mechanical stimuli. More importantly, these ionogels are presented as a model system to elucidate the underlying mechanism of the low hysteresis and fatigue resistance. Based on these findings, it is further demonstrated that the supramolecular low-hysteresis strategy is universal.

Impact of dorsal closing wedge calcaneal osteotomy on hindfoot alignment and biomechanics of patients with insertional achilles tendinopathy; A weightbearing CT-based simulation study

PurposeDorsal closing wedge calcaneal osteotomy (DCWCO) is purported to enhance both the biological and mechanical aspects of insertional Achilles tendinopathy (IAT) by altering its insertional anatomy. The biomechanical impacts of shifting the Achilles insertion, however, are not fully understood. This study aimed to analyze the effect of DCWCO on hindfoot alignment and gastrocnemius-soleus (G-S) power. MethodsSix weightbearing ankle CTs of patients diagnosed with IAT were segmented and standardized planes were used to conduct DCWCOs with six variations, resulting in a total of 42-foot models including the 6 preoperative original model. Two distinct representations of plantar osteotomy starting points were defined. One was 1 cm anterior to plantar calcaneal tubercle (posterior osteotomy) and the other was 2 cm anterior (anterior osteotomy). The osteotomies were extended to 1 cm anterior of posterosuperior calcaneal tuberosity with 6-, 10-, or 14-mm dorsal wedges. Pre-defined Achilles insertion points were used to create computational Achilles tendon models. Multiple automated measurements were performed to calculate the change in foot alignment and biomechanics. ResultsBoth anterior and posterior osteotomy locations resulted in decreased lateral talocalcaneal and calcaneal pitch angles, more substantially so with the anterior osteotomy (p = 0.028). Distance change between Achilles and Haglund was much greater with posterior osteotomy using 6- and 10-mm wedges as compared to the anterior alternative (p = 0.028). Anterior osteotomy caused a significant decrease in the Böhler angle (p < 0.001). The subtalar joint orientation was observed to change up to 3.8° in anterior osteotomy and the decrease in G-S power was found to be a maximum of 2–3 %. ConclusionA posteriorly placed starting point can provide more Achilles decompression while an anteriorly placed starting point can affect foot alignment more significantly. DCWCO can change the subtalar joint orientation predisposing the joint to increased loads. Decrease in G-S power was low and will presumably not have clinical impact.