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This review investigates the application of acoustic emission (AE) techniques in analyzing the mechanical properties and damage prediction of human bone. AE is a non-invasive and non-destructive evaluation method that captures the elastic waves released during microstructural deformations under stress, providing critical insights into bone behavior and failure mechanisms. By analyzing 57 studies, this review synthesizes findings on AE signal characteristics, experimental configurations, and their correlations with bone’s mechanical parameters such as yield strength, elastic modulus, and micro-damage evolution. This article highlights AE’s potential in early damage detection, differentiation of failure modes, and predictive modeling using stochastic and percolation theories. These models facilitate the prediction of fracture risk and mechanical failure without inducing irreversible damage. This review addresses the strengths and limitations of AE techniques and outlines future directions in biomechanical research.

The mechanical properties of the cerebral bridging veins (CBVs) were studied using advanced microtensile equipment. Detailed high-quality curves were obtained at different strain rates, showing a clearly nonlinear stress–strain response. In addition, the tissue of the CBVs exhibits stress relaxation and a preconditioning effect under cyclic loading, unequivocal indications of viscoelastic behavior. Interestingly, most previous literature that conducts uniaxial tensile tests had not found significant viscoelastic effects in CBVs, but the use of more sensitive tests allowed to observe the viscoelastic effects. For that reason, a careful mathematical analysis is presented, clarifying why in uniaxial tests with moderate strain rates, it is difficult to observe any viscoelastic effect. The analysis provides a theoretical explanation as to why many recent studies that investigated mechanical properties did not find a significant viscoelastic effect, even though in other circumstances, the CBV tissue would clearly exhibit viscoelastic behavior. Finally, this study provides reference values for the usual mechanical properties, as well as calculations of constitutive parameters for nonlinear elastic and viscoelastic models that would allow more accurate numerical simulation of CBVs in Finite Element-based computational models in future works.

BackgroundThe epidemiology of sudden cardiac arrest (SCA) in the Mediterranean area remains unclear. The aim of this study is to determine the incidence, causes and characteristics of SCA in this setting.MethodsA prospective registry of out-of-hospital cardiac arrests from multiple sources of information was carried out in the Tarragona region (western Mediterranean) with a population of 610 865 inhabitants between 2014 and 2017. The attending clinician assessed the cases on-site. SCA was defined as an unexpected out-of-hospital cardiac arrest, with a presumed cardiac cause, occurring within 1 hour of symptom onset or seen in good condition within the last 24 hours. Data were obtained from the emergency medical service, forensic autopsies, hospitals and primary care centres.ResultsA total of 639 SCAs were collected. The incidence was 34.8 (95% CI 32.2 to 37.6) cases per 100 000 person-years. The mean age was 66.9 (SD 15.6) years, and 70.1% were male. 20.5% did not receive a cardiopulmonary resuscitation (CPR) attempt. Investigations for the aetiology of cardiac arrest were conducted in hospitals in 20.3% of cases and through forensic autopsies in 36.4%. Of all SCAs with a presumed cardiac cause, 55.5% had a known cause, of which 85.3% were cardiovascular (69.8% cardiac, 15.5% cardiovascular non-cardiac and 14.6% non-cardiovascular). More cardiac causes were recorded in hospitalised patients than in forensic cases (76.9% vs 66.4%, p=0.042). Coronary heart disease (45.6%) was the main cause, with chronic coronary heart disease (24.5%) being the most frequent type. Cases with a non-cardiac cardiovascular cause presented similar cardiovascular risk factors compared with cases with a cardiac cause. Survival was 10.2%. Chest pain prior to collapse and the use of automatic external defibrillators were associated with survival.ConclusionIn this western Mediterranean region, a low incidence of SCA and a low burden of coronary heart disease were found. A comprehensive, multidisciplinary approach is needed to prevent SCA.

Many previous studies on the mechanical properties of Parasagittal Bridging Veins (PSBVs) found that strain rate had a significant effect on some mechanical properties, but did not extensively study the viscoelastic effects, which are difficult to detect with uniaxial simple tensile tests. In this study, relaxation tests and tests under cyclic loading were performed, and it was found that PSBVs do indeed exhibit clear viscoelastic effects. In addition, a complete viscoelastic model for the PSBVs is proposed and data from relaxation, cyclic load and load-unload tests for triangular loads are used to find reference values that characterize the viscoelastic behavior of the PSBVs. Although such models have been proposed for other types of blood vessels, this is the first study that clearly demonstrates the existence of viscoelastic effects from an experimental point of view and also proposes a specific model to explain the data obtained. Finally, this study provides reference values for the usual viscoelastic properties, which would allow more accurate numerical simulation of PSBVs by means of computational models.

The identification of potentially slow-growing pigs at birth, using both external and internal traits, would enable the early implementation of targeted management and feeding strategies to optimize herd management and improve production efficiency. Twenty-four piglets from six hyperprolific sows were classified into four categories based on birth body weight (BW), body mass index (BMI), and crow-to-rump length (CRL): severe intrauterine growth restriction (sIUGR), low birth weight (LBW), moderate birth weight (MBW), and high birth weight (HBW). Organ weights, computed tomography (CT) measurements, bending tests to assess tibial mechanical and geometric properties, and tibial mineral content analysis were performed to evaluate organ and skeletal physiological characteristics. Severe IUGR piglets exhibited higher brain-to-organ ratios and relative brain weights, which decreased linearly across categories. High birth BW piglets demonstrated 70% more bone volume and a greater proportion of high-density bones than sIUGR piglets, along with the largest cortical area and thickness in tibia measurements. On the other hand, sIUGR showed higher maximum stress, stiffness values, and manganese content in their tibiae compared to other categories. These findings reveal that piglets with varying degrees of IUGR prioritize brain development, exhibit asymmetrical organ growth, and experience impaired ossification and longitudinal bone growth. This study underscores the need to incorporate complementary birth indicators to refine the classification of newborn piglets with different degrees of restriction.

Worldwide, the ocurrence of acute subdural hematomas (ASDHs) in road traffic crashes is a major public health problem. ASDHs are usually produced by loss of structural integrity of one of the cerebral bridging veins (CBVs) linking the parasagittal sinus to the brain. Therefore, to assess the risk of ASDH it is important to know the mechanical conditions to which the CBVs are subjected during a potentially traumatic event (such as a traffic accident or a fall from height). Recently, new studies on CBVs have been published allowing much more accurate prediction of the likelihood of mechanical failure of CBVs. These new data can be used to propose new damage metrics, which make more accurate predictions about the probability of occurrence of ASDH in road crashes. This would allow a better assessement of the effects of passive safety countermeasures and, consequently, to improve vehicle restraint systems. Currently, some widely used damage metrics are based on partially obsolete data and measurements of the mechanical behavior of CBVs that have not been confirmed by subsequent studies. This paper proposes a revision of some existing metrics and constructs a new metric based on more accurate recent data on the mechanical failure of human CBVs.

Objective. We aim to characterize the viscoelastic behavior of Polyether-Block-Amide (PEBA 90A), provide reference values for the parameters of a constitutive model for the simulation of mechanical behaviors, and paying attention to the influence of the manufacturing conditions. Methods. Uniaxial relaxation tests of filaments of PEBA were used to determine the values of the parameters of a Prony series for a Quasi-Linear Visco-Elastic (QLVE) model. Additional, fast cyclic loading tests were used to corroborate the adequacy of the model under different test criteria in a second test situation. Results. The QLVE model predicts the results of the relaxation tests very accurately. In addition, the behavior inferred from this model fits very well with the measurements of fast cyclic loading tests. The viscoelastic behavior of PEBA under small strain polymer fits very well to a six-parameter QLVE model.

The identification of potentially slow-growing pigs at birth, using both external and internal traits, would enable the early implementation of targeted management and feeding strategies to optimize herd management and improve production efficiency. Twenty-four piglets from six hyperprolific sows were classified into four categories based on birth body weight (BW), body mass index (BMI), and crow-to-rump length (CRL): severe intrauterine growth restriction (sIUGR), low birth weight (LBW), moderate birth weight (MBW), and high birth weight (HBW). Organ weights, computed tomography (CT) measurements, bending tests to assess tibial mechanical and geometric properties, and tibial mineral content analysis were performed to evaluate organ and skeletal physiological characteristics. Severe IUGR piglets exhibited higher brain-to-organ ratios and relative brain weights, which decreased linearly across categories. High birth BW piglets demonstrated 70% more bone volume and a greater proportion of high-density bones than sIUGR piglets, along with the largest cortical area and thickness in tibia measurements. On the other hand, sIUGR showed higher maximum stress, stiffness values, and manganese content in their tibiae compared to other categories. These findings reveal that piglets with varying degrees of IUGR prioritize brain development, exhibit asymmetrical organ growth, and experience impaired ossification and longitudinal bone growth. This study underscores the need to incorporate complementary birth indicators to refine the classification of newborn piglets with different degrees of restriction.

This paper aims to find the key process parameters for machining different parts of an automobile gearbox, commissioned by a company that needs to replace with the MQL lubrication system their current machining process based on cutting fluids. It particularly focuses on the definition of appropriate cutting parameters for machining under the MQL condition through a statistical method of Design of Experiments (DOE). Using a combination of recommended parameters, significant improvements in the surface roughness of different machined parts are shown. Production costs are also reduced by decreasing expenses on lubricants and by optimizing the cycle time reached under the new cutting conditions, what would help the implementing company to increase its profits and adapt to a modern sustainability-demanding production industry.

This paper aims to find the key process parameters for machining different parts of an automobile gearbox, commissioned by a company that needs to replace with the MQL lubrication system their current machining process based on cutting fluids. It particularly focuses on the definition of appropriate cutting parameters for machining under the MQL condition through a statistical method of Design of Experiments (DOE). Using a combination of recommended parameters, significant improvements in the surface roughness of different machined parts are shown. Production costs are also reduced by decreasing expenses on lubricants and by optimizing the cycle time reached under the new cutting conditions, what would help the implementing company to increase its profits and adapt to a modern sustainability-demanding production industry.