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This paper proposed a composite sandwich structure containing multilayer honeycombs, and a multi-objective optimization model containing its load-bearing and wave-absorbing properties, which were correlated with the geometric parameters of the honeycomb, was developed. The critical elastic buckling load was performed as an indicator to characterize the load-bearing capacity, and the bandwidth of the sandwich was employed as an indicator to characterize the wave-absorbing characteristics. This multi-objective optimization model was optimized based on JAYA algorithm and the results showed that the optimized structure had a significant improvement in both load-bearing and wave-absorbing capacities compared to the original structure. [ABSTRACT FROM AUTHOR]

Biological structures optimized through natural selection provide valuable insights for engineering load-bearing components. This paper reviews six key strategies evolved in nature for efficient mechanical load handling: hierarchically structured composites, cellular structures, functional gradients, hard shell–soft core architectures, form follows function, and robust geometric shapes. The paper also discusses recent research that applies these strategies to engineering design, demonstrating their effectiveness in advancing technical solutions. The challenges of translating nature's designs into engineering applications are addressed, with a focus on how advancements in computational methods, particularly artificial intelligence, are accelerating this process. The need for further development in innovative material characterization techniques, efficient modeling approaches for heterogeneous media, multi-criteria structural optimization methods, and advanced manufacturing techniques capable of achieving enhanced control across multiple scales is underscored. By highlighting nature's holistic approach to designing functional components, this paper advocates for adopting a similarly comprehensive methodology in engineering practices to shape the next generation of load-bearing technical components. [ABSTRACT FROM AUTHOR]

Biomimetic hydrogel lubrication coatings with high wettability and low friction show great promise in tissue engineering, wound dressing, drug delivery, and intelligent sensing. Inspired by the hierarchical structure of natural cartilage, a layered hydrogel coating was constructed to functionalize rigid polyetheretherketone (PEEK). The layered hydrogel coating features a structural design comprising a top soft layer and a middle robust layer. The porous structure of the top soft hydrogel layer stores water molecules, providing surface lubrication, while the dense structure of the middle robust hydrogel layer offers load-bearing capacity. These synergistic effects of the gradient hydrogel layer endow the PEEK substrate with an ultra-low coefficient of friction (COF~0.010 at 5 N load), good load-bearing capacity (COF~0.031 at 10 N load), and excellent wear resistance (COF < 0.05 at 5 N load after 20,000 sliding cycles). This study introduces a novel design paradigm for robust hydrogel coatings with exceptional lubricity, displaying the potential application in cartilage replacement materials. [ABSTRACT FROM AUTHOR]

The current research introduces a multilayer functional structure along with its corresponding multi-objective optimization design strategy intended to improve the design efficiency of materials exhibiting remarkable properties in both load-bearing and electromagnetic wave absorption. The composite structure contains several layers of graphite oxide reinforced epoxy resin, each of which has a different thickness and volume fraction of fillers. The proposed strategy employs the volume fraction of fillers and thickness of each layer as the design variables, with the electromagnetic wave absorption bandwidth and bending stiffness of the entire structure serving as objectives. The multi-objective model was derived using the Maxwell-Garnett Model, Halpin-Tsai Model, Transmission Line Theory and Classical Laminate Theory. To efficiently optimize the multilayer structure, the JAYA, an evolutionary algorithm is employed as optimizer. The results indicate that the optimized structure exhibits a considerable increase in electromagnetic wave absorbing capacity and a slight increase in load-bearing performance relative to the original structure, while the total thickness remains constant. In addition, the whole process takes only a few seconds. [ABSTRACT FROM AUTHOR]

Lightweight, load-bearing, and penetration-resistant integrated meta-structures have significant potential in military equipment and defense facilities, as they can effectively reduce weight and improve space utilization compared to traditional load-bearing structures and armors. Based on hybrid sandwich meta-structures the load-deflection curves of the meta-structure and the traditional corrugated sandwich under 3-point bending loads were compared. The protective performance and energy absorption mechanism of the meta-structure under multiple ballistic impacts were experimentally studied. The research results indicate that, the hybrid sandwich meta-structure mainly experiences brittle fracture of ceramic, plastic fracture of face-sheets, and debonding of the adhesive layer under bending loads. Its load-bearing capacity is higher than those of traditional corтиgated sandwiches. Furthermore, the study also reveals that the impact location and the lattice core type influence the multi-impact resistance of the meta-structure, with the honeycomb core demonstrating superior multi impact resistance compared to the corrugated core. The corrugated sandwich lacks longitudinal constraints on the ceramic, while the honeycomb core provides stronger constraints on the ceramic, limiting the area of ceramic damage. As a result, the penetration-resistant performance remains relatively consistent as the number of impacts increases. [ABSTRACT FROM AUTHOR]

Cartilage is well lubricated over a lifetime and this phenomenon is attributed to both of the surface hydration lubrication and the matrix load-bearing capacity. Lubricious hydrogels with a layered structure are designed to mimic cartilage as potential replacements. While many studies have concentrated on improving surface hydration to reduce friction, few have experimentally detected the relationship between load-bearing capacity of hydrogels and their interface friction behavior. In this work, a bilayer hydrogel, serving as a cartilage prototype consisted of a top thick hydrated polymer brush layer and a bottom hydrogel matrix with tunable modulus was designed to investigate this relationship. The coefficient of friction (COF, μ) is defined as the sum of interfacial component (μInt) and deformation/hysteresis component (μHyst). The presence of the top hydration layer effectively dissipates contact stress and reduces the interface interaction (μInt), leading to a stable and low COF. The contribution of mechanical deformation (μHyst) during the sliding shearing process to COF can be significantly reduced by increasing the local mechanical modulus, thereby enhancing the load-bearing capacity. These results show that the strategy of coupling surface hydration layer with a high load-bearing matrix can indeed enhance the lubrication performance of hydrogel cartilage prototypes, and implies a promising routine for designing robust soft matter lubrication system and friction-control devices. [ABSTRACT FROM AUTHOR]

Hydrogel is an ideal material for cartilage repair, but it is difficult for artificial materials to achieve ultra-low friction coefficient of cartilage at present. The amphoteric ion anionic double crosslinked P(AAm-co-AAc-co-SBMA-co-AMPS)/Fe3+hydrogel was synthesized by using the amphoteric monomer [2-(methacryloxy) ethyl] dimethyl-(3-sulfopropyl)(SBMA) and the anionic monomer 2-acrylamido-2-methylpropane sulfonic acid (AMPS). The frictional tests were conducted in water and PBS to evaluate the effects of zwitterionic and anionic groups on the coefficient of friction (CoF). The results show that the physical crosslinking point introduced by SBMA and AMPS can improve the compressive strength of hydrogel, and achieve a low CoF (0.04) in water, In addition, it is observed that CoF further decreases to 0.015 in PBS, and the decrease of CoF is caused by the highly hydrated upper layer of hydrogel produced during PBS soaking.

The rapid development of additive manufacturing (AM) has facilitated the creation of bionic lightweight, energy-absorbing structures, enabling the implementation of more sophisticated internal structural designs. For protective structures, the utilization of artificially controlled deformation patterns can effectively reduce uncertainties arising from random structural damage and enhance deformation stability. This paper proposed a bionic corrugated lightweight honeycomb structure with controllable deformation. The force on the onset state of deformation of the overall structure was investigated, and the possibility of controlled deformation in the homogeneous structure was compared with that in the corrugated structure. The corrugated structures exhibited a second load-bearing capacity wave peak, with the load-bearing capacity reaching 60.7% to 117.29% of the first load-bearing peak. The damage morphology of the corrugated structure still maintained relative integrity. In terms of energy absorption capacity, the corrugated lightweight structure has a much stronger energy absorption capacity than the homogeneous structure due to the second peak of the load carrying capacity. The findings of this study suggested that the combination of geometric customization and longitudinal corrugation through additive manufacturing offers a promising approach for the development of high-performance energy-absorbing structures. [ABSTRACT FROM AUTHOR]

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The interest in novel mechanical metamaterials that offer advanced functionalities and mechanical tunability for highly compatible multifunctional performance in state‐of‐the‐art engineering applications is growing. Here, a novel tunable multifunctional mechanical metamaterial, also known as a metamaterial sandwich panel, which can achieve load‐bearing, energy absorption, and low‐frequency vibration isolation properties simultaneously, is reported. The designed metamaterial sandwich panel is composed of a quasi‐zero stiffness (QZS) lattice core and two kirigami‐style surfaces, which endow the metamaterial sandwich panel with multi‐function performance and tunable properties. As a proof‐of‐concept, the mechanical properties and tunable multifunctional performance of the proposed metamaterial sandwich panel are demonstrated both in simulations and experiments. This work provides a new alternative for designing novel mechanical metamaterials with tunable multifunctional performance and may have potential applications in a variety of engineering applications, such as medical transportation, marine systems, and aerospace applications. [ABSTRACT FROM AUTHOR]

This article will outline a method of building residential homes as Prefabricated, Prefinished Volumetric Construction (PPVC), using AAC panels. These transportable structures are created from solid AAC modules and designed for Residential Homes and Low‐Rise multi‐residential developments. In this transportable system, thick AAC panels are used as the principal construction material and load‐bearing structural element. The AAC modules are factory assembled and fitted out as completed room pods. They are transported to the site where they are lifted directly from the delivery truck and positioned into their final location on steel piers. Engineered AAC floor and ceiling cassettes connect the modular pods together to form a spacious and modern solid AAC home. [ABSTRACT FROM AUTHOR]

New manufacturing recipe of glass waste-based foam glass gravel for special applications in construction was designed, tested, and presented in this paper. The work originality is the use of alumino-silicate materials in the form of waste (fly ash, blast furnace slag, alkaline earth alumino-silicate glass waste) as well as in the natural state (metakaolin) widely available in nature. Especially, in this work it was chosen the use of a waste of alumino-silicate glass recovered from halogen lamps, similar by chemical composition with the other materials adopted to constitute the material mixture. Three variants using a solid (SiC) and liquid (glycerin), respectively, blowing agent were tested, the mixtures being sintered and foamed at temperatures between 850-940 °C. The heating was made by the economic and ecological technique of microwave irradiation. All tested versions led to obtaining cellular gravel types with characteristics suitable for special applications in construction, similar to industrially made foam glass gravel. Being more suitable for load-bearing properties, the variant made with alumino-silicate glass waste and glycerin associated with sodium silicate solution was chosen as the optimal alternative. [ABSTRACT FROM AUTHOR]

Engineering synthetic hydrogels for the repair and augmentation of load-bearing soft tissues with simultaneously high-water content and mechanical strength is a long-standing challenge. Prior formulations to enhance the strength have involved using chemical crosslinkers where residues remain a risk for implantation or complex processes such as freeze-casting and self-assembly, requiring specialised equipment and technical expertise to manufacture reliably. In this study, we report for the first time that the tensile strength of high-water content (>60 wt.%), biocompatible polyvinyl alcohol hydrogels can exceed 1.0 MPa through a combination of facile manufacturing strategies via physical crosslinking, mechanical drawing, post-fabrication freeze drying, and deliberate hierarchical design. It is anticipated that the findings in this paper can also be used in conjunction with other strategies to enhance the mechanical properties of hydrogel platforms in the design and construction of synthetic grafts for load-bearing soft tissues. [ABSTRACT FROM AUTHOR]

The decision about the choice of load-sharing (LS) or load-bearing (LB) osteosynthesis is determined by an interplay of fracture-related and patient-related factors. In some situations a similar fracture in two different patients may be treated successfully by either of these methods. Our aim was to identify preoperative patient-related factors that may assist in deciding which form of osteosynthesis is employed. All adult patients who underwent open reduction and internal fixation of mandibular fractures (excluding condyle) between 1 October 2018 and 1 June 2021 were retrospectively identified. The odds of developing postoperative complications and requiring a return to theatre (RTT) were calculated for each method of fixation together with the following patient factors: smoking, excess alcohol, substance misuse, and severe mental health issues. Of 337 fractures treated using LS principles, 27 (8%) developed complications, of which 20 (6%) required a RTT for repeat osteosynthesis. Of 74 fractures treated using LB principles, seven (10%) developed complications and two (3%) required a RTT for repeat osteosynthesis. The only patient factor that had statistically significant increased odds of a complication requiring RTT was LS osteosynthesis in patients who admitted drinking excess alcohol (OR = 7.83, p = 0.00, 95% CI = 3.13 to 19.60). Complications when treating mandibular fractures are rarely reported in the literature, and lack standardisation in their clinical significance. Figures generally represent overall numbers of patients, whereas the number of individual fractures treated is more accurate. In our study complications occurred in 8% of treated fractures and 10% of patients. The RTT rate was 7% of patients, which compares favourably with a recently stated standard of 10% of patients, as suggested by the Getting it Right First Time (GIRFT) report. [ABSTRACT FROM AUTHOR]

Despite numerous reports on microwave absorbing materials and structures with excellent performance, research on the impact of the carrier of microwave absorbers and their preparation processes on microwave absorption performance still faces challenges. To address this issue, this study combines theoretical analysis, simulation, and experimental validation to compare the differences in microwave absorption performance between 3D printed ABS/CF/MWCNTs materials and traditionally cast paraffin/CF/MWCNTs materials. Furthermore, the study explores the impact of linear and concentric filling patterns in 3D printing processes on the performance of tree-shaped microwave absorbing meta-structures. From a material level perspective, the 3D printed ABS/CF/MWCNTs composite plate with a thickness of 3 mm has an effective absorption bandwidth of 5.16 GHz. Additionally, the bio-inspired tree-shaped structure optimized by the ant colony algorithm achieves an effective absorption bandwidth of up to 11.5 GHz at a thickness of 10.8 mm, with a minimum reflection loss of less than −9 dB across the entire frequency range (2–18 GHz). Moreover, the microwave absorbing meta-structure reinforced with carbon fiber-reinforced plastic laminates exhibits outstanding tensile and bending strength, with an average tensile strength and bending strength reaching 197.7 MPa and 188.6 MPa, respectively. In summary, this study provides valuable insights into the optimization of preparation processes for microwave absorbing materials or structures and offers a scientific basis for the design and application of high-performance microwave absorbing materials. [ABSTRACT FROM AUTHOR]

New manufacturing recipe of glass waste-based foam glass gravel for special applications in construction was designed, tested, and presented in this paper. The work originality is the use of alumino-silicate materials in the form of waste (fly ash, blast furnace slag, alkaline earth alumino-silicate glass waste) as well as in the natural state (metakaolin) widely available in nature. Especially, in this work it was chosen the use of a waste of alumino-silicate glass recovered from halogen lamps, similar by chemical composition with the other materials adopted to constitute the material mixture. Three variants using a solid (SiC) and liquid (glycerin), respectively, blowing agent were tested, the mixtures being sintered and foamed at temperatures between 850-940 ºC. The heating was made by the economic and ecological technique of microwave irradiation. All tested versions led to obtaining cellular gravel types with characteristics suitable for special applications in construction, similar to industrially made foam glass gravel. Being more suitable for load-bearing properties, the variant made with alumino-silicate glass waste and glycerin associated with sodium silicate solution was chosen as the optimal alternative.

Articular cartilage (AC), which covers the ends of bones in joints, particularly the knee joints, provides a robust interface to maintain frictionless movement during daily life due to its remarkable lubricating and load-bearing capacities. However, osteoarthritis (OA), characterized by the progressive degradation of AC, compromises the properties of AC and thus leads to frayed and rough interfaces between the bones, which subsequently accelerates the progression of OA. Hydrogels, composed of highly hydrated and interconnected polymer chains, are potential candidates for AC replacement due to their physical and chemical properties being similar to those of AC. In this review, we summarize the recent progress of hydrogel-based synthetic cartilage, or cartilage-like hydrogels, with a particular focus on their lubrication and load-bearing properties. The different formulations, current limitations, and challenges of such hydrogels are also discussed. Moreover, we discuss the future directions of hydrogel-based synthetic cartilage to repair and even regenerate the damaged AC. [ABSTRACT FROM AUTHOR]

Composite slabs with steel deck combine the load-bearing resistance of the steel deck and rebar with the compressive resistance of the concrete (components). Unprotected composite slabs may be exposed to natural fire conditions from below, and steel reduces its load-bearing capacity during the heating stage. In short fire events, with limited deformations, the composite slabs can recover the load-bearing capacity during the cooling stage. This research presents the validation of the numerical model and the development of a parametric study, to evaluate the load-bearing capacity during the fire event. This method includes a time step procedure, based on the average temperature calculation for each component, including the reduction coefficients applied to the design strength of each material. A new proposal is also presented to evaluate the residual load-bearing capacity. In some circumstances, the residual load-bearing can be reduced by more than 20%. The results showed that the highest variation in the load-bearing resistance of composite slabs occurs when the steel temperatures are between 20 and 600 ℃, after this temperature, the steel has already lost most of its mechanical strength. Moreover, it was observed that different heating rates and different cooling rates influence the rate of the reduction and recovery of the load-bearing capacity. It was also noticed that the lowest load-bearing capacity of the composite slabs was reached after the end of the heating phase, showing that the stability of the element during the heating phase does not guarantee fire safety during the cooling phase.

Objective: To document the risk of new-onset symptomatic pelvic organ prolapse (POP) among perimenopausal women and examine whether occupational lifting and/or pushing is a risk factor in the development of POP over a 10-year follow-up window.Study Design: Secondary analysis of prospective, longitudinal data from the Study of Women's Health Across the Nation (SWAN) cohort study.Main Outcome Measures: We analyzed women with current employment at the start of SWAN who were followed annually during mid-life. At baseline, women self-reported the frequency of occupational lifting and pushing, which was classified as Never, Infrequent (less than half the time), or Frequent (half the time or more) occupational lifting and/or pushing. Women were asked about new-onset symptomatic POP from the second to tenth annual follow-up. Modified Poisson regression was used to quantify crude and adjusted risk ratios (RRs) and 95 % confidence intervals (CIs) for POP according to load-bearing categories. Parous women were modelled separately, as initial analyses suggested effect modification by parity status.Results: In our sample of 1590 parous women, 8.2 % reported new-onset symptomatic POP over 10 years of follow-up. Multivariable analysis revealed that Infrequent (aRR 1.51, 95 % CI 1.04-2.20) and Frequent (aRR 2.03, 95 % CI 1.29-3.17) occupational lifting and/or pushing were associated with the development of POP.Conclusion: Frequent occupational lifting and/or pushing significantly increased parous women's risk of developing POP symptoms. This strengthens existing evidence that occupational exposures can be risk factors for POP. Gender-based education and prevention strategies in the workplace and in primary health care are necessary to reduce the burden of this condition for mid-life women. [ABSTRACT FROM AUTHOR]

In the last decades plenty of fire tests with wall constructions consisting of reinforced AAC elements were executed. Many of the test results have been transferred to European and national technical regulations. Also, theoretical methods to design reinforced AAC elements for fire impact are available. These provide temperature curves for the commonly used dry densities and procedures to calculate and rate the influence of fire stress on the functional capacity of the wall systems. In the last years additional fire tests took place to show the fulfilment of special requirements for buildings with high demands regarding fire safety. For example, tests with six hours of firing were performed which is highly above the definitions and solutions given in standards. Xella's R&D Center meanwhile has its own test stand to execute suitability checks for fire walls and is accredited for performing these tests. In the last years the question about how to rate the performance of fire walls on basis of test results came up, especially regarding load bearing walls. This is the result of different definitions in the relevant national and European standards. Possible approaches for solving this topic shall be presented at the AAC conference. [ABSTRACT FROM AUTHOR]

The purpose of this research is to specify the differences between the performance of cross-laminated timber (CLT) and reinforced concrete (RC) walls. The study is done by using the finite element structural analysis and design software, StruSoft FEM-Design, in order to model, analyse and design a reference building located in the city of Gävle in Sweden. The building is firstly modelled, analysed and designed using RC walls and then the RC walls are replaced with CLT walls. In both buildings, other load-bearing elements such as slabs, beams and columns are made of RC while the roof beams are made of glulam. It is found that employing RC has advantages, especially regarding thickness. The results show that the CLT walls require larger dimensions than their RC counterparts. Meanwhile, it is demonstrated that the slabs, beams and columns made of RC in the building having the CLT walls require more reinforcement or larger thickness than the case of walls made of RC. Moreover, the total weight of the building having the CLT walls is 74% of the building having the RC walls. The lower weight of the building having the CLT walls has great advantages such as having lighter foundation and being cost-effective and also beneficial for the environment.

Pressure-resistant hulls are critical components in underwater vehicles and submersible systems. Exploring novel materials and structures has been a growing trend to overcome conventional structural limitations and achieve multifunctionality. Mechanical metamaterials with tunable physical properties can offer promise. Therefore, this study focuses on designing and fabricating a pressure-resistant sandwich cylindrical shell using AuxHex zero Poisson's ratio (ZPR) mechanical metamaterials. Structural optimization is employed to develop a lightweight AuxHex ZPR unit cell to withstand deep-sea pressure. Mechanical and acoustic experiments were then conducted on a 3D-printed Titanium alloy specimen, and the rationality of numerical modeling was validated by the experimental results. Load bearing and sound insulation properties of the designed ZPR sandwich cylindrical shell have been numerically analyzed and compared with its geometrically similar positive Poisson's ratio (PPR) and negative Poisson's ratio (NPR) shells. The designed ZPR structure that yields a mass density ratio of 0.569 g/cm³ can withstand hydrostatic pressure at 1000 m depths without strength or buckling damage, while adequate reserve buoyancy can be maintained. The submerged ZPR shell structure can provide superior protection for inner spaces and its average sound transmission loss (STL) is more than 5 dB higher than the PPR and NPR shells. • A lightweight AuxHex ZPR cylindrical sandwich shell is designed and a 3D printed specimen is fabricated and tested. • The designed ZPR shell structure can bear hydrostatic pressure of 1000 m depth with adequate reserve buoyancy. • The ZPR shell structure provides superior protection for inner spaces compared with geometrically-similar PPR and NPR shells. • The ZPR shell structure yields a greater STL than the compared PPR and NPR shells due to its smallest core impedance. [ABSTRACT FROM AUTHOR]

This paper conducts an investigation on ductility and strength of high strength bolted connections for high strength constructional steels. Ductility and strength of different bolted connection types are comprehensively studied and compared. It is found that reduction in material elongation capacity for high strength steels has negligible effect on the ductility of bolted connections. When the net cross‐section failure is prevented, similar ductility is found for the bearing‐type bolted connection with different number of bolts. In addition, the misalignment of bolt hole will not introduce negative effect on ductility and strength of the connection. The load‐displacement curve for the connection with misaligned bolt hole will coincide with the connection without misaligned bolt hole. It is concluded that similar ductility of bearing‐type connection is maintained with increasing steel grade while strength of multi‐bolt connection in high strength steel can still be calculated by summation of each individual bolt. [ABSTRACT FROM AUTHOR]

Greece is divided into three earthquake hazard zones: Zone I, Zone II and Zone III. In the present research work, the same building in the three seismic zones in Greece was modeled, analyzed and dimensioned. Then, the construction cost of its structural body was estimated. The building modeling was performed in SAP2000 using frame elements. The analysis of the building was performed by dynamic spectral analysis methods using the design spectrum EC8. A five-story building with a standard rectangular floor plan per floor was used. The purpose of this research paper is to demonstrate whether the cost of construction of a load-bearing body of a reinforced concrete (R/C) building is influenced by the area of an earthquake hazard through a comparative analytical estimation of construction costs. It was determined if this impact is important and to what extent. Helpful conclusions were drawn in relation to the influence of seismicity on the construction cost of the load-bearing structure of R/C buildings. Furthermore, the probable environmental impact was examined. [ABSTRACT FROM AUTHOR]

Study Design Prospective radiographic comparative study. Purpose To compare and understand the load-bearing properties of each functional spinal unit (FSU) using three commonly assumed, physiological, spinal postures, namely, the flexed (slump sitting), erect (standing) and extended (backward bending) postures. Overview of Literature Sagittal spinal alignment is posture-dependent and influences the load-bearing properties of the spine. The routine placement of intervertebral cages “as anterior as possible” to correct deformity may compromise the load-bearing capabilities of the spine, leading to complications. Methods We recruited young patients with nonspecific low back pain for

Cellular structures are regarded as excellent candidates for lightweight-design, load-bearing, and energy-absorbing applications. In this paper, a novel S-based TPMS hollow isotropic cellular structure is proposed with both superior load-bearing and energy-absorbing performances. The hollow cellular structure is designed with Boolean operation based on the Fischer-Koch (S) implicit triply periodic minimal surfaces (TPMS) with different level parameters. The anisotropy and effective elasticity properties of cellular structures are evaluated with the numerical homogenization method. The finite element method is further conducted to analyze the static mechanical performance of hollow cellular structure considering the size effect. The compression experiments are finally carried out to reveal the compression properties and energy-absorption characteristics. Numerical results of the Zener ratio proved that the S-based hollow cellular structure tends to be isotropic, even better than the sheet-based Gyroid TPMS. Compared with the solid counterpart, the S-based hollow cellular structure has a higher elastic modulus, better load-bearing and energy absorption characteristics. [ABSTRACT FROM AUTHOR]

Studying the motion and load-bearing characteristics of the planetary roller screw mechanism is the basis for the structural design and performance optimisation of the mechanism. The mechanical structures and working principles of different kinds of planetary roller screw mechanisms are summarised. Published papers on kinematic, load-bearing and dynamic models of the planetary roller screw mechanism are reviewed. Based on the slip state in point contacts at the screw–roller and the nut–roller interfaces, the kinematic models are divided into three types. The finite element method and numerical theory are the two main methods used to develop the load-bearing models. Current dynamic models differ mainly concerning whether they take the rotation of the screw into consideration. In this work, each kind of model is presented in detail along with relevant literature. The main conclusions for each type of model are discussed, and an overview of the future evolution of motion and load-bearing characteristics of the planetary roller screw mechanism are given. [ABSTRACT FROM AUTHOR]

Background. Designing a high strength all-ceramic fixed partial denture with favorable esthetics can be challenging for clinicians; this study aimed to evaluate the effect of connector size and design on the fracture resistance of monolithic zirconia fixed dental prostheses. Methods. Two groups of twenty 3-unit monolithic zirconia (Sirona inCoris TZI, Sirona Dental Systems GmbH) bridges, extending from the mandibular first premolar to the first molar with different connector sizes (9 mm2 and 12 mm2 ), were divided into two subgroups with different connector designs (round and sharp). The specimens were subjected to the three-point bending test to obtain the fracture-bearing load. The results were reported using descriptive statistics (mean ± standard deviation). Mann-Whitney U test was used to compare the fracture load in two types of designs for each connector size and two connector size types for each connector design. The significance level was considered at P

Engineering synthetic hydrogels for the repair and augmentation of load-bearing soft tissues with simultaneously high-water content and mechanical strength is a long-standing challenge. Prior formulations to enhance the strength have involved using chemical crosslinkers where residues remain a risk for implantation or complex processes such as freeze-casting and self-assembly, requiring specialised equipment and technical expertise to manufacture reliably. In this study, we report for the first time that the tensile strength of high-water content (>60 wt.%), biocompatible polyvinyl alcohol hydrogels can exceed 1.0 MPa through a combination of facile manufacturing strategies via physical crosslinking, mechanical drawing, post-fabrication freeze drying, and deliberate hierarchical design. It is anticipated that the findings in this paper can also be used in conjunction with other strategies to enhance the mechanical properties of hydrogel platforms in the design and construction of synthetic grafts for load-bearing soft tissues.

Rose prickles are small-scale, plant-based anchoring tools of multifunctional biomechanical roles, combining physical defense against herbivores and growth support on surrounding objects. By employing multiscale structural observations, nanomechanical characterizations, and finite-element simulations, we unveil that the dog rose ( Rosa canina Linnaeus) prickle incorporates structural-mechanical modifications at different length scales, resulting in macroscopic stress-locking effects that provide the prickle extreme damage-resistant capabilities and secure its functional form against catastrophic failures. These functional design strategies, unique to plant-based biomechanical tools, may promote futuristic micro-engineered anchoring platforms for micro-robotics locomotion, biomedical microinjection, and micromechanical systems., (© The Author(s) 2024. Published by Oxford University Press on behalf of National Academy of Sciences.)

Composite slabs with steel deck combine the load-bearing resistance of the steel deck and rebar with the compressive resistance of the concrete (components). Unprotected composite slabs may be exposed to natural fire conditions from below, and steel reduces its load-bearing capacity during the heating stage. In short fire events, with limited deformations, the composite slabs can recover the load-bearing capacity during the cooling stage. This research presents the validation of the numerical model and the development of a parametric study, to evaluate the load-bearing capacity during the fire event. This method includes a time step procedure, based on the average temperature calculation for each component, including the reduction coefficients applied to the design strength of each material. A new proposal is also presented to evaluate the residual loadbearing capacity. In some circumstances, the residual load-bearing can be reduced by more than 20%. The results showed that the highest variation in the load-bearing resistance of composite slabs occurs when the steel temperatures are between 20 and 600°C, after this temperature, the steel has already lost most of its mechanical strength. Moreover, it was observed that different heating rates and different cooling rates influence the rate of the reduction and recovery of the load-bearing capacity. It was also noticed that the lowest load-bearing capacity of the composite slabs was reached after the end of the heating phase, showing that the stability of the element during the heating phase does not guarantee fire safety during the cooling phase. [ABSTRACT FROM AUTHOR]

Hydrogels as one kind of soft materials with a typical three-dimensional (3D) hydrophilic network have been getting great attention in the field of biolubrication. However, traditional hydrogels commonly show poor tribology performance under high-load conditions because of their poor mechanical strength and toughness. Herein, pure chemical-crosslinking hydrogels mixed with different types of the micron-scale fibers can meet the requirements of strength and toughness for biolubrication materials, meanwhile the corresponding tribology performance improves significantly. In a typical case, three kinds of reinforcement matrix including needle-punched fibers, alginate fibers, and cottons are separately combined with Poly(n-vinyl pyrrolidone)-poly(2-hydroxyethyl methacrylate (PVP-PHEMA) hydrogels to prepare fibers reinforced composite hydrogels. The experimental results show that the mechanical properties of fibers reinforced composite hydrogels improve greatly comparable with pure PVP-PHEMA hydrogels. Among three kinds of fibers reinforced composite hydrogel, the as-prepared composite hydrogels reinforced with needle-punched fibers possess the best strength, modulus, and anti-tearing properties. Friction tests indicate that the fibers reinforced composite hydrogels demonstrate stable water-lubrication performance comparable with pure PVP-PHEMA hydrogels. Besides, the hydrogel-spunlace fiber samples show the best load-bearing and anti-wear capacities. The improved tribology performance of the composite hydrogels is highly related to mechanical property and the interaction between the fibers and hydrogel network. Finally, spunlace fibers reinforced hydrogel materials with high load-bearing and low friction properties are expected to be used as novel biomimetic lubrication materials. [ABSTRACT FROM AUTHOR]

Articular cartilage (AC), which covers the ends of bones in joints, particularly the knee joints, provides a robust interface to maintain frictionless movement during daily life due to its remarkable lubricating and load-bearing capacities. However, osteoarthritis (OA), characterized by the progressive degradation of AC, compromises the properties of AC and thus leads to frayed and rough interfaces between the bones, which subsequently accelerates the progression of OA. Hydrogels, composed of highly hydrated and interconnected polymer chains, are potential candidates for AC replacement due to their physical and chemical properties being similar to those of AC. In this review, we summarize the recent progress of hydrogel-based synthetic cartilage, or cartilage-like hydrogels, with a particular focus on their lubrication and load-bearing properties. The different formulations, current limitations, and challenges of such hydrogels are also discussed. Moreover, we discuss the future directions of hydrogel-based synthetic cartilage to repair and even regenerate the damaged AC.

This study was conducted to identify whether team-wide or positional differences exist in simple or choice reactivity of collegiate soccer athletes when completed under various loads. Much research exists surrounding the assessment of reaction time in the general population, but given variations in training, little insight exists surrounding how unique and elite populations may differ based upon performance demands and task translatability to training. Reactive performance was assessed using the Dynavision D2 in 24 female soccer players (19.73 ± 1.05 years old) from a team within a power five conference of the National Collegiate Athletic Association. Evaluated loads included two conditions of simple reactivity (no additional load and with a concurrent lower body motor task) and three conditions of choice reactivity (no additional load, with a concurrent lower body motor task, and prolonged durations). Paired t-tests and ANOVAs were used to identify differences in task performance based upon load and positional group. No significant load-based or positional differences existed in measured simple reaction times. Performances in choice reaction tasks across the team were found to be slower when completed across extended durations (p < 0.0001) and faster when completed concurrent with an added balance task (p = 0.0108), as compared to performance under normal conditions. By assessment of positional differences, goalkeepers tended to be slower than other positions in reactivity during choice tasks, despite no differences existing in simple task performance. Given the unique population utilized herein, measured reactivity in different tasks suggests a strong relation to the training demands of soccer, as well as those of goalkeepers as compared to field positions. Findings suggest that sport and positional demands may be substantial contributors to population- and individual-based reactivity performance.

The importance of hydrogels in tissue engineering cannot be overemphasized due to their resemblance to the native extracellular matrix. However, natural hydrogels with satisfactory biocompatibility exhibit poor mechanical behavior, which hampers their application in stress-bearing soft tissue engineering. Here, we describe the fabrication of a double methacrylated gelatin bioink covalently linked to graphene oxide (GO) via a zero-length crosslinker, digitally light-processed (DLP) printable into 3D complex structures with high fidelity. The resultant natural hydrogel (GelGOMA) exhibits a conductivity of 15.0 S m -1 as a result of the delocalization of the π -orbital from the covalently linked GO. Furthermore, the hydrogel shows a compressive strength of 1.6 MPa, and a 2.0 mm thick GelGOMA can withstand a 1.0 kg ms -1 momentum. The printability and mechanical strengths of GelGOMAs were demonstrated by printing a fish heart with a functional fluid pumping mechanism and tricuspid valves. Its biocompatibility, electroconductivity, and physiological relevance enhanced the proliferation and differentiation of myoblasts and neuroblasts and the contraction of human-induced pluripotent stem cell-derived cardiomyocytes. GelGOMA demonstrates the potential for the tissue engineering of functional hearts and wearable electronic devices., (© 2024 IOP Publishing Ltd. All rights, including for text and data mining, AI training, and similar technologies, are reserved.)

Studying the motion and load-bearing characteristics of the planetary roller screw mechanism is the basis for the structural design and performance optimisation of the mechanism. The mechanical structures and working principles of different kinds of planetary roller screw mechanisms are summarised. Published papers on kinematic, load-bearing and dynamic models of the planetary roller screw mechanism are reviewed. Based on the slip state in point contacts at the screw–roller and the nut–roller interfaces, the kinematic models are divided into three types. The finite element method and numerical theory are the two main methods used to develop the load-bearing models. Current dynamic models differ mainly concerning whether they take the rotation of the screw into consideration. In this work, each kind of model is presented in detail along with relevant literature. The main conclusions for each type of model are discussed, and an overview of the future evolution of motion and load-bearing characteristics of the planetary roller screw mechanism are given.

Background. Designing a high strength all-ceramic fixed partial denture with favorable esthetics can be challenging for clinicians; this study aimed to evaluate the effect of connector size and design on the fracture resistance of monolithic zirconia fixed dental prostheses. Methods. Two groups of twenty 3-unit monolithic zirconia (Sirona inCoris TZI, Sirona Dental Systems GmbH) bridges, extending from the mandibular first premolar to the first molar with different connector sizes (9 mm2 and 12 mm2), were divided into two subgroups with different connector designs (round and sharp). The specimens were subjected to the three-point bending test to obtain the fracture-bearing load. The results were reported using descriptive statistics (mean ± standard deviation). Mann-Whitney U test was used to compare the fracture load in two types of designs for each connector size and two connector size types for each connector design. The significance level was considered at P < 0.05. Results. The minimum failure load was related to the group with a 9-mm2 connector size and a sharp embrasure design (1054.4±133.89 N), and the highest mean value belonged to the group with 12-mm2 connector size and rounded embrasure design (1599.8±167.09 N). Mann-Whitney U test indicated a significant difference between the mean failure load of the rounded and sharp embrasure designs in the 9-mm2 connector size (P = 0.007). However, the difference was insignificant in the 12-mm2 connector size (P = 0.075). Conclusion. Sharp embrasure design is not recommended for high-stress areas with restricted occlusogingival height. A 9-mm2 connector size for 3-unit monolithic zirconia fixed dental prosthesis (FDP), which is recommended by the manufacturer, should be used more cautiously. [ABSTRACT FROM AUTHOR]

As bionic lubricating material, hydrogel could not have both lubrication performance and mechanical strength. The sparse cross-linked network hinders the practical application of hydrogel in places where long service life and high load capacity are required. Here we proposed a method of combining dual networks with nano-enhancement to prepare high-strength lubricating Polyvinyl alcohol/polyacrylic acid/Graphene oxide (PVA/PAA/GO) hydrogel by annealing treatment. increasing the network density of the hydrogel enhances the mechanical properties and reduces the permeability. Hydration lubrication, excellent mechanical properties and synovial fluid pressurization enable the hydrogel to maintain outstanding lubrication under high contact pressure after 500,000 cycles. The wear-reducing and wear-resistant properties of hydrogel indicate excellent tribological properties, and the hydrogel expected to become replacement material for artificial joints. [Display omitted] [ABSTRACT FROM AUTHOR]

This study aimed to investigate the effects of walking in a hot and humid environment while wearing a combat suit with a load on physiological responses among the Malaysian Military Reserve Officer Training Unit (ROTU) female cadets. Eight healthy female ROTU cadets (age: 21.3 ± 1.0 years old; height: 156.3 ± 4.9 cm; weight: 55.6 ± 7.5 kg) participated in this randomised, crossover trial. They walked for 1 h on a treadmill at 3 km.h-1 while carrying either 8.2 kg load (WL) or without load (WOL) in a room maintained at 30°C and 70% relative humidity. Heart rate, rate of perceived exertion (RPE), and tympanic temperature were recorded at regular intervals during the trials. Nude body weight was recorded before and after the walk to determine body weight loss and sweat rate. Urine samples were also collected before and after the walk to determine urine specific gravity of the participants. There was a significant main effect of time and interaction for heart rate (p < 0.001) during the experimental trials. Tympanic temperature was significantly higher at 60th min in WL trial (p < 0.05) compared to the WOL trial. Similarly, RPE was found to be significantly higher in WL trial (p < 0.01) compared to the WOL trial. However, the percentage of body weight loss and sweat rate was significantly different between trials (p < 0.05). Wearing a combat suit with a load showed significantly increased metabolic demands compared to wearing combat suit alone during prolonged walking in a hot and humid environment. [ABSTRACT FROM AUTHOR]

Despite its regenerative ability, long and segmental bone defect repair remains a significant orthopedic challenge. Conventional tissue engineering efforts induce bone formation through intramembranous ossification (IO) which limits vascular formation and leads to poor bone regeneration. To overcome this challenge, a novel hybrid matrix comprised of a load-bearing polymer template and a gel phase is designed and assessed for bone regeneration. Our previous studies developed a synthetic ECM, hyaluronan (HA)–fibrin (FB), that is able to mimic cartilage-mediated bone formation in vitro. In this study, the well-characterized HA–FB hydrogel is combined with a biodegradable polymer template to form a hybrid matrix. In vitro evaluation of the matrix showed cartilage template formation, cell recruitment and recruited cell osteogenesis, essential stages in endochondral ossification. A transgenic reporter-mouse critical-defect model was used to evaluate the bone healing potential of the hybrid matrix in vivo. The results demonstrated host cell recruitment into the hybrid matrix that led to new bone formation and subsequent remodeling of the mineralization. Overall, the study developed and evaluated a novel load-bearing graft system for bone regeneration via endochondral ossification. [ABSTRACT FROM AUTHOR]

With over 500,000 bone grafting procedures performed annually in the United States, the advancement of bone regeneration technology is at the forefront of medical research. Many tissue‐engineered approaches have been explored to develop a viable synthetic bone graft substitute, but a major challenge is achieving a load‐bearing graft that appropriately mimics the mechanical properties of native bone. In this study, sintered hydroxyapatite (HAp) was used to structurally reinforce a scaffold and yield mechanical properties comparable to native bone. HAp was packed into a cylindrical framework and processed under varying conditions to maximize its mechanical properties. The resulting HAp columns were further tested in a 6‐week degradation study to determine their physical and mechanical response. The cellular response of sintered HAp was determined using a murine preosteoblast cell line, MC3T3‐E1. Cell viability and morphology were studied over a one‐week period and MC3T3‐E1 differentiation was determined by measuring the alkaline phosphatase levels. Finite element analysis was used to determine the columns' geometric configuration and arrangement within our previously developed composite bone scaffold. It was determined that incorporating four cylindrical HAp columns, fabricated under 44 MPa of pressure and sintered at 1200°C for 5 hr, led to load‐bearing properties that match the yield strength of native whole bone. These preliminary results indicate that the incorporation of a mechanically enhanced HAp structural support system is a promising step toward developing one of the first load‐bearing bone scaffolds that can also support cell proliferation and osteogenic differentiation. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 732–741, 2019. [ABSTRACT FROM AUTHOR]