This study introduces a three-dimensional (3D) model for investigating the interactions between trabecular bone tissue and bio-resorbable grafts, focusing on their role in bone remodelling processes. Using principles of poroelasticity, the model captures the mechanical behaviour of both bone and graft as porous continua, with their interaction influenced by time-varying mechanical loads and diffusive mechanical stimuli. The stimuli, originating from the strain energy density, propagate through the system, triggering bone formation and graft resorption across distant regions. Numerical simulations reveal the critical impact of load frequency and intensity on remodelling efficiency, with higher values promoting improved bone density and graft integration. This 3D approach provides information on optimizing scaffold design, offering valuable guidance to improve clinical outcomes in bone repair and regeneration procedures.

A two-dimensional (2D) reduced-order generalised continuum model within the framework of the three-dimensional (3D) deformations is deduced from a 3D Cauchy continuum model by imposing a micro-macro kinematical map, which is linear in the direction normal to the corneal surface. This kinematical assumption is plausible as the cornea thickness is much smaller than its diameter. We use the obtained 2D generalised continuum that incorporates a kinematically independent thickness to model the changes of shape induced in corneas: (1) by the changes of cornea mechanical properties whose aetiology can be found in the complex (and not completely understood yet) pathogenic process causing keratoconus, (2) by penetrating keratoplasty, and (3) degeneration of both patient residual corneal tissue and transplanted corneal tissue after transplant. We postulate that growth and regeneration phenomena occurring in the cornea shape it following the “elastic” solutions, which we have calculated. The preliminary obtained predictions seem to promise significant applicative developments and are in good qualitative agreement with experimental results: future investigations will need to improve the presented model by considering explicitly the remodelling phenomena and a more detailed analysis of the evolution of metabolically driven mechanical damage of corneal tissue and its visco-plasticity.

We propose a three-dimensional macroscopic continuum model designed to predict the remodeling phenomenon of bone tissue. In the proposed model, we focus on the evolution of two crucial stiffness parameters: the bulk and shear moduli. These parameters independently adapt to the mechanical demands to which bone tissue is subjected, mainly to withstand hydrostatic and deviatoric deformations. These mechanical stimulations influence the activity of bone cells, leading to changes in bone structure and strength and, in turn, the above-mentioned moduli. The formulation is simplified, serving as an initial step towards a more comprehensive modeling approach. The evolution of these stiffness parameters is proposed based on an energetic argument to describe the functional adaptation process. Numerical experiments, conducted on a cylindrical specimen resembling a femur, demonstrate the feasibility of modeling the bone remodeling process with distinct evolutions for multiple material parameters, in contrast to the conventional approach that permits only one-parameter evolution.

Fibrous metamaterials exhibit remarkable mechanical properties. For their experimental study, additive fabrication is frequently employed. The main problem one faces, when trying to produce by 3D printing a specimen to test, lies in the realization of elements connecting the fibers. This has been achieved using selective laser sintering (SLS) techniques, but appears to be very hard to perform with other printing techniques, like the filament-based one. In this work, we show, within the framework of the particular class of fibrous metamaterials known as pantographic metamaterials, a novel design for connecting hinges specifically optimized for filament-based 3D printing. This has a first fundamental advantage with respect to SLS: filament printing is extremely cheaper and can be accessible nowadays to everybody. Moreover, this hinge design enables faster prototyping, broader customization, and greater reliability in fibrous metamaterial structures.

This work presents a comprehensive theoretical framework for flexoelectric materials by incorporating higher-order strain gradient and polarization gradient effects into the constitutive modeling. Using an extended strain gradient elasticity (SGE) approach, coupled with a generalized Toupin-like variational formulation, we derive governing equations, balance laws, and boundary conditions based on an enriched internal energy density function. Analytical solutions, expressed in terms of modified Bessel functions, provide key insights into the role of higher-order gradients in influencing displacement, polarization, and electric fields. The study highlights the critical impact of size effects on flexoelectric response, revealing that reducing material thickness enhances sensitivity and energy conversion efficiency. Furthermore, numerical simulations validate the theoretical model and demonstrate its applicability in the design of nanoscale flexoelectric sensors and energy harvesters. These findings establish a robust theoretical foundation for optimizing nanoscale electromechanical devices, with potential applications in biomedical sensors, structural health monitoring, and energy-efficient electronics.

It is usually accepted in geophysics (and in civil engineering) that linear models can be used for describing an earthquake and the consequent seismic waves’ propagation. However, the large deformation experienced by the soil in these situations suggests that this paradigm requires more critical consideration. In fact, we claim that, in the vicinity of some discontinuities (that are common in all the geophysical applications of continuum models), the corresponding strain concentrations make the hypothesis of small deformation to be inadequate. In this paper, we verify the inappropriateness of the linear paradigm in a simple but reasonable case, with a view to a future application of this study to the effects of the 2009 L’Aquila earthquake. To this aim, we start with an analysis which is restricted to a two-dimensional body (i) with an inhomogeneity that resembles the Aterno River Valley, central Italy and (ii) with a non-linearity that is the most simple one, choosing the strain energy to be quadratic in the non-linear measures of deformation. More precisely, we consider a 2D piecewise homogeneous domain and a material that is viscoelastic isotropic and geometrically non-linear. We apply, to the bottom of such a domain, a seismic excitation and calculate the differences in the response between the linear and the geometrically non-linear cases. Using a suitably designed numerical model, we prove that, as conjectured, these differences not only originate near the pre-defined geometrical discontinuities but also propagate throughout the rest of the domain. Moreover, we find numerical predictions of the frequency ratios and ground acceleration time dependence and amplitude that produce, in the case of non-linear models, predictions which are closer to experimental evidence than those obtained using the corresponding linear model.

Objective: To evaluate transperineal laser ablation (TPLA) with Echolaser® (Echolaser® TPLA, Elesta S.p.A., Calenzano, Italy) as a treatment for benign prostatic hyperplasia (BPH) and prostate cancer (PCa) using the Delphi consensus method. Methods: Italian and international experts on BPH and PCa participated in a collaborative consensus project. During two rounds, they expressed their opinions on Echolaser® TPLA for the treatment of BPH and PCa answering online questionnaires on indications, methodology, and potential complications of this technology. Level of agreement or disagreement to reach consensus was set at 75%. If the consensus was not achieved, questions were modified after each round. A final round was performed during an online meeting, in which results were discussed and finalized. Results: Thirty-two out of forty invited experts participated and consensus was reached on all topics. Agreement was achieved on recommending Echolaser® TPLA as a treatment of BPH in patients with ample range of prostate volume, from <40 mL (80%) to >80 mL (80%), comorbidities (100%), antiplatelet or anticoagulant treatment (96%), indwelling catheter (77%), and strong will of preserving ejaculatory function (100%). Majority of respondents agreed that Echolaser® TPLA is a potential option for the treatment of localized PCa (78%) and recommended it for low-risk PCa (90%). During the final round, experts concluded that it can be used for intermediate-risk PCa and it should be proposed as an effective alternative to radical prostatectomy for patients with strong will of avoiding urinary incontinence and sexual dysfunction. Almost all participants agreed that the transperineal approach of this organ-sparing technique is safer than transrectal and transurethral approaches typical of other techniques (97% of agreement among experts). Pre-procedural assessment, technical aspects, post-procedural catheterization, pharmacological therapy, and expected outcomes were discussed, leading to statements and recommendations. Conclusion: Echolaser® TPLA is a safe and effective procedure that treats BPH and localized PCa with satisfactory functional and sexual outcomes.

The paper focuses on the effect of damage on the bone remodeling process. This is a crucial, although complex, aspect. A one-dimensional continuous deformable body is employed to model living bone tissue. The model incorporates the bone functional adaptation through an evolution law for an effective elastic modulus driven by mechanical feedback via a mechano-transduction diffusive signal. This type of information transduction, i.e., diffusion, is essential for the model to take into account remodeling in the case of minor injury or pathology-affected regions where there is no signal production. In addition, the model is able to also take into account potential tissue damage that may evolve over time according to a suitable evolution law. To illustrate the capability of the model to describe the mentioned complex coupled phenomena, numerical tests have been performed encompassing high external loads causing the onset of damage and cyclic loading for healing. The numerical simulations carried out via finite-element analyses yield insights into the mechanisms of bone remodeling, with the final goal of aiding clinical decisions and implant designs for bone health and repair. Overall, a key aspect of the paper is to highlight the feasibility of modeling the evolution in bone elasticity arising from the combined effect of damage and remodeling.

Various nonlinear planar beam models are presented and discussed using a variational approach. Particular attention is paid to the introduction of the strain energy functional and the determination of suitable strain measures and kinematic descriptors. Shear deformability or non-deformability is emphasized as a qualifier between the different models. Some attention is also given to the case where the beam cross-section is deformable. Problems of dynamics and dissipation are mentioned to complete the discussion.

The present study proposes a mathematical model elucidating some aspects of the bio-mechanical stimulus involved in bone remodelling, which, in our assumptions, acts as a diffusive signalling agent for bones. The proposed mathematical model aims to scrutinize the behaviour of bone tissues and their evolution over time by better understanding the mechanisms of bone remodelling and offering new theoretical tools for developing more effective and efficient treatment strategies for bone defects, trauma, or diseases. The bone remodelling process involves adapting bone mechanical properties in response to dynamic loads. This adaptation is achieved through the diffusive stimulus created by these loads. The result is a functional adaptation of the bone, wherein it acquires the mechanical properties required to withstand the loads to which it is subjected. This phenomenon has significant implications for the study of bone physiology and biomechanics. As such, it is a topic of great interest to researchers and practitioners in the fields of orthopaedics, sports medicine, and related disciplines. In this contribution, the mechanical behaviour is modelled through a generalized three-dimensional deformable continuum that also takes into account the porous nature of the bone tissue with a nonlinear constitutive law. Since we have focused the study on the model of the stimulus and its interplay with the evolution of the tissue, an isotropic material symmetry is adopted to simplify the problem. This formulation is promising because it permits the bone tissue to evolve depending on the time variability of the external mechanical loads, even if the source of the stimulus is assumed to be the strain energy density. The proposed model exhibits great potential, and its scope extends to several other applications, including the integration of anisotropic material symmetry and damage. Further research in this area can unlock new possibilities and enable the development of more advanced models with these new features. We plan future investigations to focus on these areas to exploit the full potential of this model entirely.

Background The proportion of health-related searches on the internet is continuously growing. ChatGPT, a natural language processing (NLP) tool created by OpenAI, has been gaining increasing user attention and can potentially be used as a source for obtaining information related to health concerns. This study aims to analyze the quality and appropriateness of ChatGPT’s responses to Urology case studies compared to those of a urologist. Methods Data from 100 patient case studies, comprising patient demographics, medical history, and urologic complaints, were sequentially inputted into ChatGPT, one by one. A question was posed to determine the most likely diagnosis, suggested examinations, and treatment options. The responses generated by ChatGPT were then compared to those provided by a board-certified urologist who was blinded to ChatGPT’s responses and graded on a 5-point Likert scale based on accuracy, comprehensiveness, and clarity as criterias for appropriateness. The quality of information was graded based on the section 2 of the DISCERN tool and readability assessments were performed using the Flesch Reading Ease (FRE) and Flesch-Kincaid Reading Grade Level (FKGL) formulas. Results 52% of all responses were deemed appropriate. ChatGPT provided more appropriate responses for non-oncology conditions (58.5%) compared to oncology (52.6%) and emergency urology cases (11.1%) ( p = 0.03). The median score of the DISCERN tool was 15 (IQR = 5.3) corresponding to a quality score of poor. The ChatGPT responses demonstrated a college graduate reading level, as indicated by the median FRE score of 18 (IQR = 21) and the median FKGL score of 15.8 (IQR = 3). Conclusions ChatGPT serves as an interactive tool for providing medical information online, offering the possibility of enhancing health outcomes and patient satisfaction. Nevertheless, the insufficient appropriateness and poor quality of the responses on Urology cases emphasizes the importance of thorough evaluation and use of NLP-generated outputs when addressing health-related concerns.

Mechanical metamaterials consist of specially engineered features designed to tailor and enhance the mechanical properties of their constituent materials. In this context, 2D pantographic fabrics have gained attention for their unique deformation behavior, providing remarkable resilience and damage tolerance. This study explores micro-metric metamaterials with 3D pantographic motifs, aiming to transfer these properties to small scales. 3D micro-metric structures were designed using 2D pantographic fabrics arranged in multiple layers, each featuring unit cells with quasi-perfect pivots. Relatively large specimens of 3D micro-metric pantographs, measuring 158 m x 250 m x 450 m, were fabricated in various configurations using two-photon polymerization. These specimens were mechanically characterized through in-situ scanning electron microscopy microindentation under conditions of cyclic deformation. Structural failures were subsequently assessed via helium-ion microscopy. The 3D micro-metric pantographs exhibited complex mechanical properties, some aligning with those of 2D pantographic fabrics, while new properties, such as a dissipative response and softening, were identified. Nonetheless, the 3D micro-metric pantographs demonstrated great resilience against deformation and enhanced resistance to undesired out-of-plane motions, indicating their potential for novel applications in advanced engineering fields. Additionally, the findings can potentially lead to optimizing and enriching theoretical models describing the mechanical behavior of pantographic metamaterials.

A variational model has been developed to investigate the coupled thermo-mechanical response of a three-dimensional continuum. The linear Partial Differential Equations (PDEs) of this problem are already well-known in the literature. However, in this paper, we avoid the use of the second principle of thermodynamics, basing the formulation only on a proper definition (i) of kinematic descriptors (the displacement and the entropic displacement), (ii) of the action functional (with kinetic, internal and external energy functions) and (iii) of the Rayleigh dissipation function. Thus, a Hamilton–Rayleigh variational principle is formulated, and the cited PDEs have been derived with a set of proper Boundary Conditions (BCs). Besides, the Lagrangian variational perspective has been expanded to analyze linear irreversible processes by generalizing Biot’s formulation, namely, including thermal inertia in the kinetic energy definition. Specifically, this implies Cattaneo’s law for heat conduction, and the well-known Lord–Shulman model for thermo-elastic anisotropic bodies is then deduced. The developed variational framework is ideal for the perspective of analyzing the thermo-mechanical problems with micromorphic and/or higher-order gradient continuum models, where the deduction of a coherent system of PDEs and BCs is, on the one hand, not straightforward and, on the other hand, natural within the presented variational deduction.

This paper provides a thorough investigation of a heat conduction problem that pertains to tolerance modelling in layered materials made up of multiple components. These media are functionally graded materials and thus have varying properties that affect their effectiveness. The proposed equations explain the conduction of heat in layered composites. The formulation involves partial differential equations, which utilise smooth and slowly varying functions. Notably, an extension of the unified tolerance modelling procedure is presented generalising existing models for two-component step-wise functionally graded materials (FGMs). This extension allows for the analysis of specific issues related to heat conduction in multi-component stratified composites with a transversal gradation of effective properties. This is the most important novelty achievement of the present paper because it will contribute to advancing knowledge and allows researchers, engineers, and practitioners to use the method in a broader context, addressing a more extensive set of real-world situations not limited to the number of component materials.

Orthodontic tooth movement is the fundamental phenomenon underlying the treatment of dental malocclusions. For orthodontic treatment to be efficient and effective, the amount of force applied to the teeth for every kind of movement should be appropriately dosed, because it is associated with the risk of side effects and the treatment time. However, our knowledge of the complex cascade of events that transforms a mechanical stimulus into an ordinated bone remodeling is incomplete. Predictive theoretical numerical models could be of invaluable help in understanding the bone response to orthodontic loading and in studying the effects of complex orthodontic force systems. However, either short-term or evolutive predictive models showed a large heterogeneity of material properties and governing equations. The present review provides an outline of the physical and biochemical basis of orthodontic tooth movement with a focus around the periodontal ligament interface. The use of a standardized method for designing predictive models is advocated, and perspectives for future studies are presented.

Multilayer pantographic metamaterials, in short, pantographic blocks, have shown peculiar mechanical behavior, especially when their constitutive hinges are revolving (i.e., perfect) joints. The pantographic block, which is the subject of the present paper, has been printed using a Powder Bed Fusion technology and its hinges may be modeled as perfect ones. In the reported in situ 3-point flexural test, the predictions obtained by second gradient models for its mechanical response are shown to be experimentally consistent thanks to measurements via Digital Volume Correlation. The deformation applied by the upper central support is almost entirely shielded by the pantographic block, namely, the specimen barely crosses through the reference bottom plane defined by the lower lateral supports, even when subjected to very large deformations. The mathematical model employed herein captures this observation in terms of a nonlinear ‘arching’ effect activated in the beams of the pantographic structure, provided elastic locking is introduced to prevent pantographic zero-energy modes.

Thin films usually exhibit instabilities and yield intricate wrinkles when two clamped ends are twisted. Here, we explore the wrinkling behavior and pitch-fork bifurcation of twisted thin films experimentally and theoretically. To quantitatively predict the post-buckling evolution of twist-induced wrinkling morphology, we develop a refined finite-strain plate model derived from 3D field equations and then solve it by using the finite element method with COMSOL. We examine the effects of aspect ratios and pre-tension on the wrinkling profile. We reveal three distinguished wrinkling evolution regimes depending on the aspect ratios of thin films as the twisting angle increases: (a) wrinkles initially occur at both free ends of the film and then develop toward the center; (b) wrinkles appear at the center and then develop toward both free ends; (c) wrinkles emerge at the center and are localized therein. The increase of film thickness and pre-stretch can strengthen the film stiffness and thus increase the critical twisting threshold, resulting in the prevention of wrinkle formation. Understanding the morphological pattern evolution of twisted films may guide rational designs of wrinkle-tunable membrane surfaces and structures.

We outline the scientific objectives, the experimental layout, and the collaborations envisaged for the GINGER (Gyroscopes in general relativity) project. The GINGER project brings together different scientific disciplines aiming at building an array of ring laser gyroscopes (RLGs), exploiting the Sagnac effect, to measure continuously, with sensitivity better than pico-rad/s, large bandwidth (ca. 1 kHz), and high dynamic range, the absolute angular rotation rate of Earth. We address the feasibility of the apparatus with respect to the ambitious specifications above, as well as prove how such an apparatus, which will be able to detect strong earthquakes, very weak geodetic signals, as well as general relativity effects like Lense-Thirring and de Sitter, will help scientific advancements in theoretical physics, geophysics, and geodesy, among other scientific fields.

In this paper, we aim to explore the mechanical potentialities of a material made of an orthogonal net of fibers arranged in logarithmic spirals. Therefore, an annular plate described with a second-gradient model is envisaged to evaluate the behavior of such material in a nonlinear elastic regime when large displacements and deformations occur. Several mechanical tests are performed numerically under the finite element method approximation obtained directly with a weak formulation based on the elastic energy that it is assumed to be predictive for this kind of network system of fibers. Plots reporting the mechanical characteristics in all the considered tests are provided to illustrate the overall mechanical behavior of the evaluated system.