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Switching Spectroscopy Piezoresponse Force Microscopy (SSPFM) stands out as a powerful method for probing ferroelectric properties within materials subjected to incremental polarization induced by an external electric field. However, the dense data processing linked to this technique is a critical factor influencing the quality of obtained results. Furthermore, meticulous exploration of various artifacts, such as electrostatics, which may considerably influence the signal, is a key factor in obtaining quantitative results. In this paper, we present a global methodology for SSPFM data processing, accessible in open-source with a user-friendly Python application called PySSPFM. A ferroelectric thin film sample of potassium sodium niobate has been probed to illustrate the different aspects of our methodology. Our approach enables the reconstruction of hysteresis nano-loops by determining the PR as a function of applied electric field. These hysteresis loops are then fitted to extract characteristic parameters that serve as measures of the ferroelectric properties of the sample. Various artifact decorrelation methods are employed to enhance measurement accuracy, and additional material properties can be assessed. Performing this procedure on a grid of points across the surface of the sample enables the creation of spatial maps. Furthermore, different techniques have been proposed to facilitate post-treatment analysis, incorporating algorithms for machine learning (K-means), phase separation, and mapping cross correlation, among others. Additionally, PySSPFM enables a more in-depth investigation of the material by studying the nanomechanical properties during poling, through the measurement of the resonance properties of the cantilever–tip–sample surface system. [ABSTRACT FROM AUTHOR]

The research presented in the paper concerns the elastic properties of struvite. The article combines theoretical and experimental research. Experimental studies were carried out on struvite single crystals grown in sodium metasilicate gel by single diffusion. This unique method leads to obtaining crystals of sufficiently large size to conduct, for the first time, experimental measurement of elastic properties of monocrystalline struvite. Using the nanoindentation method, the Ez = 29.1 ± 0.7 GPa value of the component of Young's modulus was determined for a struvite single crystal. In addition, the elastic constants C11, C22, and C33 were determined using micro-Brillouin spectroscopy. Theoretical calculations of the abovementioned properties have been carried out by employing density functional theory methods. Scaling of the theoretical elastic constants leads to obtaining good agreement with the experimental values. Values of the Ex and Ey components of the Young's modulus, not available from the experimental nanoindentation technique, have been determined theoretically as 23 GPa and 27 GPa, respectively. Differences in the values of elastic components and Young's modulus components are related to the layered crystal structure of struvite and directional character of the hydrogen-bonding pattern. [ABSTRACT FROM AUTHOR]

The gap between classical continuity and nanomechanics can be bridged using the concept of nonlocal elasticity. The Voigt viscoelastic model and the generalized dual-phase thermoelastic micropolar framework (DPL) are considered. Also, higher-order time derivatives with a two-phase delay are included in the heat transfer equation to generalize the proposed model. The mechanical and viscoelastic properties of suspensions, colloidal liquids, concretes, etc., can be described by applying the suggested model. As an example of using the proposed model, the effect of the pulsed heat transfer rate on the thermoelastic micropolar half-space was investigated. The analytical formulas for deformation, nonlocal thermal stress, and temperature change were derived after solving the governing equations using the Laplace transform technique. The graphical representation of numerical simulation results has been utilized to illustrate the effects of micropolarity, higher-order phenomena, phase delay, nonlocal index, and viscosity variables on a given distance. In this specific instance, the conclusions drawn from this analysis also incorporated the results of previously conducted research. [ABSTRACT FROM AUTHOR]

The triply periodic minimal surface (TPMS) is being potentially considered in innovative applications, including robotics, biomedical engineering, impact energy absorption, and so on, so that the information on mechanical property and energy absorption of TPMS components under the damage loading is significant to understand, with a considerably reduced cost before being put into use. For the first time, a deep artificial neural network (ANN)-powered prediction method for TPMS lattices, including sheet gyroid, sheet primitive, sheet I-graph-wrapped package curved surface (I-WP) and solid I-WP subjected to damage loading, with an extremely low cost is introduced in this work where a loop with multiple conditions (LMC) inserted to improve its accuracy. It is a low-cost model due to the fact that it only requires a training experimental data set from 9 TPMS samples with relative density ranging from 0.1 to 0.55, subjected to the damage test to train and then generates the mechanical information and energy absorption at almost any point of the relative density (Rd). Impressively, the ANN prediction method can well comprehend and learn from experimental samples, and then accurately provide the information of mechanical behavior of TPMS architectures, including the stress-strain response, Young's modulus, and yield strength at almost any relative density in the range, under the damage load. Specifically, Young's modulus and yield strength obtained from ANN model agree well with that from the experimental damage test data, which does not belong to the training samples, with maximum percent differences found approximately 1%, and 2%, respectively. Surprisingly, ANN approach demonstrates an ability to predict the mechanical response of TPMSs, with thousands of times faster and significantly lower financial cost than that of the experiment. Thus, we move forward, by using the approach, to map 2-dimensionally the energy absorption of lattices with respect to varying relative density and deformation, and plot the energy dissipation density versus the relative density under damage loadings. [ABSTRACT FROM AUTHOR]

The low-temperature properties of amorphous solids are usually explained in terms of atomic-scale tunneling two level systems (TLS). For almost 20 years, individual TLS have been probed in insulating layers of superconducting quantum circuits. Detecting individual TLS in mechanical systems has been proposed but not definitively demonstrated. We describe an optomechanical system that is appropriate for this goal and describe our progress toward achieving it. In particular, we show that the expected coupling between the mechanical mode and a resonant TLS is strong enough for high visibility of a TLS given the linewidth of the mechanical mode. Furthermore, the electronic noise level of our measurement system is low enough, and the anomalous force noise observed in other nanomechanical devices is absent. [ABSTRACT FROM AUTHOR]

The article discusses an experimental procedure which involves impregnating cinnamon extracts into Poly Methyl Methacrylate (PMMA) resin with further purpose of utilizing it for dental prosthesis purposes. At normalized sampling rates and through manual molding using 53μm particle size, samples comprising of 8%, 6%, 4%, 2% and 0% volume fractions were evaluated. Mechanical properties such as hardness, impact strength, and tensile strength were also investigated empirically. The findings demonstrated an increase in hardness, reaching a maximum level of 8% with a value of 86 N/m². Also, impact strength coefficient marked rather a positive effect, with 0.93 KJ/m² being the highest peak noticed at the 6% volume fraction level. The peak value of tensile strength was successfully measured at 4% by volume fraction that gave 52 MPa, while additional ratios of reinforcement had a continuous trend of a decrease. This thorough study uncovers the future promising potential of cinnamon extracts as to the reinforcement of technical properties (mechanical properties), and this contributes to the improvement of modern biomaterials used in Dentistry. [ABSTRACT FROM AUTHOR]

Rock strength parameters such as uniaxial compressive strength and modulus of elasticity are crucial parameters in designing rock engineering structures. Owing to the importance of the aforementioned parameters, in this paper, image processing technique is coupled with artificial neural network (ANN) method for assessing the uniaxial compressive strength and modulus of elasticity of sandstones. For this reason, 102 core sandstone samples were prepared. Subsequently petrographic analyses and imaging operation for 102 images were performed. Principal component analysis was then conducted for feature reduction purposes. At last, an ANN model, which received its input data from image processing technique, was constructed for assessing the UCS and E of sandstone samples. Overall, the best performance of the network was obtained when 10 hidden nodes were used. The correlation coefficient (R) values of 0.9722 and 0.97062 for UCS and E, respectively, suggest the feasibility of the proposed model. [ABSTRACT FROM AUTHOR]

Straintronics involves the manipulation and regulation of the electronic characteristics of 2D materials through the use of macro‐ and nano‐scale strain engineering. In this study, an atomic force microscope (AFM) coupled with an optical system is used to perform indentation measurements and tip‐enhanced photoluminescence (TEPL), allowing to extract the local optical response of a suspended monolayer membrane of ternary WSSe at various levels of deformation, up to strains of 10%. The photoluminescence signal is modeled considering the deformation, stress distribution, and strain dependence of the WSSe band structure. An additional TEPL signal is observed that exhibits significant variation under strain, with 64 meV per percent of elongation. This peak is linked to the highly strained 2D material lying right underneath the tip. The amplification of the signal and its relation to the excitonic funneling effect are discussed in a more comprehensive model. The diffusion caused by Auger recombination against the radiative excitonic decay will also be compared. TEPL is used to examine and comprehend the local physics of 2D semi‐conducting materials subjected to extreme mechanical strain. Chemical vapor deposition‐fabricated 2D ternaries possess high strain resistance, comparable to the benchmark MoS2, and a high Young's modulus of 273 GPa. [ABSTRACT FROM AUTHOR]

Long-distance transport of a nanoparticle on a solid surface remains a challenge in nanotechnology. Here, we design a nanoscale motor device for continuously transporting a nanoparticle on a beam surface. The device is composed of repeated units of clamped beams on which a harmonic excitation is applied to induce a gradient in atomic density on their surface, and such atomic density consequently creates a driving force on the nanoparticle attached to the device surface. The design requirements that should be satisfied by the device attributes are analytically derived, and the effect of the device attributes on the device transport performance is discussed. In addition, molecular dynamics simulations for a typical device of a graphene sheet transported on a silver beam are conducted to verify the analytical results. The proposed design provides a starting point for continuously transporting a nanoobject on a solid surface and has great potential in various applications such as nanomotors and molecular assembly lines. [ABSTRACT FROM AUTHOR]

Background: The human nail has a three‐layered structure. Although it would be useful to quantitatively evaluate the changes in deformability of the nail due to various surface treatments, few studies have been conducted. Methods: The effects of two types of surface treatment—a chemically acting nail softener and a physically acting nail strengthener—on the deformability of human fingernails were investigated. The Young's modulus of each plate of the nail samples before and after softening treatment was determined by nanoindentation. The Young's modulus of the strengthener was determined by conducting a three‐point bending test on a polyethylene sheet coated with the strengthener. Results: Young's modulus decreased in order from the top plate against the softening treatment time, and the structural elasticity for bending deformation (SEB) of the nail sample, which expresses the deformability against bending deformation independent of its external dimensions, decreased to 60% after 6 h of treatment. The Young's modulus of the nail strengthener was 244.5 MPa, which is less than 10% of the SEB of the nail. When the nail strengthener was applied to the nail surface, the SEB decreased to 73%, whereas the flexural rigidity increased to 117%. Conclusion: Changes in nail deformability caused by various surface treatments for softening and hardening were quantitatively evaluated successfully. [ABSTRACT FROM AUTHOR]

[Display omitted] • 1. AFM-based biophysical measurements are performed on a neural cell. • 2. Exposure to high-dose carbon dots affects cellular mechanics and morphology. • 3. Actin filaments are disorganized in the cells after exposure to high-dose carbon dots. • 4. Biological studies validate the cytotoxic effects disclosed by AFM. • 5. AFM is a powerful biophysical tool for the study of cell-nanomaterials interactions. Understanding the cytotoxicity of fluorescent carbon dots (CDs) is crucial for their applications, and various biochemical assays have been used to study the effects of CDs on cells. Knowledge on the effects of CDs from a biophysical perspective is integral to the recognition of their cytotoxicity, however the related information is very limited. Here, we report that atomic force microscopy (AFM) can be used as an effective tool for studying the effects of CDs on cells from the biophysical perspective. We achieve this by integrating AFM-based nanomechanics with AFM-based imaging. We demonstrate the performance of this method by measuring the influence of CDs on living human neuroblastoma (SH-SY5Y) cells at the single-cell level. We find that high-dose CDs can mechanically induce elevated normalized hysteresis (energy dissipation during the cell deformation) and structurally impair actin skeleton. The nanomechanical change highly correlates with the alteration of actin filaments, indicating that CDs-induced changes in SH-SY5Y cells are revealed in-depth from the AFM-based biophysical aspect. We validate the reliability of the biophysical observations using conventional biological methods including cell viability test, fluorescent microscopy, and western blot assay. Our work contributes new and significant information on the cytotoxicity of CDs from the biophysical perspective. [ABSTRACT FROM AUTHOR]

The unique microstructures of bulk metallic glasses (BMGs) provide them with excellent mechanical, physical, and chemical properties, having important applications in the fields of medical devices, military equipment, aerospace, etc. However, the superb mechanical properties also contribute to poor machinability of the BMGs. Currently, researchers have proposed to improve the machinability by single-point diamond turning, laser-assisted machining and ultrasonic vibration-assisted machining, but their plasticity and viscous flow remain unchanged, thus restraining further enhancement of surface quality. Atmospheric pressure cold plasma jet (APCPJ), which is rich in active particles, can effectively ameliorate material machinability by modulating material properties. In this paper, we propose to use the APCPJ to regulate the properties of BMGs, and carry out nanoindentation, nanoscratching, and micro-milling experiments to investigate the influence mechanisms of APCPJ on the material properties and cutting process. The results demonstrate that after modified by APCPJ, plastic deformability of the BMGs is improved due to the increase of free volume content; meanwhile, the viscous flow is inhibited. The micro-milling experiments indicate that under the conditions of feed rate V f = 500 μm/s, spindle speed n = 30,000 rpm, and cutting depth a p = 5 μm, the improvement effect of APCPJ on the cutting process is relatively optimum. The surface roughness Ra of the Zr-based BMG and Ti-based BMG obtained by APCPJ are respectively 0.076 μm and 0.081 μm, which can be reduced by 37.7 % and 38.2 % compared with dry micro-milling. The cutting forces F z in the direction of cutting depth are also reduced by 30.9 % and 23.3 %, respectively. The APCPJ-assisted micro-milling method proposed in this work may ameliorate the machining quality of BMGs and promote the application of BMGs and APCPJ-assisted machining technology in aerospace and precision machining. [ABSTRACT FROM AUTHOR]

As the field of low‐dimensional materials (1D or 2D) grows and more complex and intriguing structures are continuing to be found, there is an emerging need for techniques to characterize the nanoscale mechanical properties of all kinds of 1D/2D materials, in particular in their most practical state: sitting on an underlying substrate. While traditional nanoindentation techniques cannot accurately determine the transverse Young's modulus at the necessary scale without large indentations depths and effects to and from the substrate, herein an atomic‐force‐microscopy‐based modulated nanomechanical measurement technique with Angstrom‐level resolution (MoNI/ÅI) is presented. This technique enables non‐destructive measurements of the out‐of‐plane elasticity of ultra‐thin materials with resolution sufficient to eliminate any contributions from the substrate. This method is used to elucidate the multi‐layer stiffness dependence of graphene deposited via chemical vapor deposition and discover a peak transverse modulus in two‐layer graphene. While MoNI/ÅI has been used toward great findings in the recent past, here all aspects of the implementation of the technique as well as the unique challenges in performing measurements at such small resolutions are encompassed. [ABSTRACT FROM AUTHOR]

In this study, the gas pressure dependence of optical and mechanical characteristics in reactive sputtered SiCO thin films for optical guided‐wave pressure sensors was experimentally investigated. Thin films were fabricated by varying the gas pressure from 0.3 to 1.0 Pa at an oxygen flow ratio of 6%, and the gas pressure dependences was clarified. As the gas pressure increased, the optical bandgap of the SiCO thin film increased, resulting in a transparent SiCO films. On the other hand, the refractive index, young's modulus, and hardness decreased with increasing gas pressure. Combining this dependence with the oxygen inflow ratio dependence of the previous study, the first‐order approximation formula for the gas pressure and oxygen flow rate ratio for various film characteristics was obtained. Based on this equation, trajectories of equal bandgaps and equal young's moduli on the oxygen flow ratio—gas pressure plane were created on the oxygen influx ratio‐gas pressure coordinates, making it easy to fabricate waveguides with desired characteristics. [ABSTRACT FROM AUTHOR]

Despite alkali–silica reaction (ASR) being a major durability problem in concrete, structural features and properties of ASR gels remain poorly understood. Inspired by the success of coarse-grained (CG) simulations in unveiling key features of calcium-silicate-hydrate (C-S-H) gels, we deploy these simulations to model ASR gels. Our goals are (1) to test the suitability of these simulations to capture ASR gels structural features and mechanical properties; and (2) to quantify any alkali-dependency in the response. Effective interactions obtained at the molecular scale for Na-ASR and K-ASR (sodium-ASR and potassium-ASR) products are adopted. Simulation results are consistent with the available data on the structure, elastic, and viscous behavior of ASR gels. The ASR gel mesotexture development and mechanical properties are ion-specific, with Na-ASR showing a more rigid/less viscous behavior overall. Our results demonstrate the suitability of CG simulations to investigate ASR. [ABSTRACT FROM AUTHOR]

The applications of nanoelectromechanical systems integrating simultaneously the mechanical and electrical functionalities at nanoscale have been gotten wider in the last decade. The main objective of this exploration is to analyze the small scale‐dependent nonlinear dynamical feedback of multilayer energy nanoharvesters containing a graded porous passive core coated by piezoelectric facesheets under a sinusoidal impulsive external actuation. For this purpose, the technique of meshless collocation is constructed at the same time the nonlocal stress and strain gradient tensors without any necessary background meshes and integration procedure. It is found that by taking the nonlocal stress tensor into account, the average of extremum points of maximum lateral deflection increases from 8.6375 to 9.6924nm, and from 4.3718 to 4.8952nm for simply supported and clamped multilayer nanoharvesters, respectively. On the contrary, through considering the strain gradient tensor, the average of extremum values of the maximum lateral deflection reduces from 8.6375 to 7.4999nm for the simply supported nanoharvester, and from 4.3718 to 3.8101nm for the clamped one. Highlights: Development a third‐order shear flexible nonlocal strain gradient (NSG)‐based plate‐type nanoharvester modelIncorporating the role of nonlocal stress and strain gradient tensors in nonlinear dynamics of nanoharvestersTime‐histories of achieved voltage of sinusoidal impulsive loaded plate‐type nanoharvestersInfluence of porosity on the NSG‐based nonlinear dynamic performance. [ABSTRACT FROM AUTHOR]

Polymer-derived ceramic (PDC) nanocomposites enable access to a large library of functional properties starting from molecular design and incorporating nanofillers. Tailoring preceramic polymer (PCP) chemistry and nanofiller size and morphology can lead to usage of the nanocomposites in complex shapes and coatings with enhanced thermal and mechanical properties. A rational design of targeted nanocomposites requires an understanding of fundamental structure–property–performance relations. Thus, we tailor our discussions of PCP design and nanofiller integration into single source precursors as well as pyrolytic processing for functionalizing PDCs. We also discuss the promises and limitations of advanced characterization techniques such as 4D transmission electron microscopy and pair distribution functions to enable in situ mapping structural evolution. The feedback loop of in situ monitoring sets the foundation for enabling accelerated materials discovery with artificial intelligence. This perspective assesses the recent progress of PDC nanocomposite research nanocomposites and presents scientific and engineering challenges for synthesis, fabrication, processing, and advanced characterization of PDC nanocomposites for enhanced magnetic, electrical, and energy conversion and storage properties. [ABSTRACT FROM AUTHOR]

This research presents a comprehensive analysis of deep neural network models (DNNs) for the precise prediction of Vickers hardness (HV) in nitrided and carburized M50NiL steel samples, with hardness values spanning from 400 to 1000 HV. By conducting rigorous experimentation and obtaining corresponding nanoindentation data, we evaluated the performance of four distinct neural network architectures: Multilayer Perceptron (MLP), Convolutional Neural Network (CNN), Long Short-Term Memory network (LSTM), and Transformer. Our findings reveal that MLP and LSTM models excel in predictive accuracy and efficiency, with MLP showing exceptional iteration efficiency and predictive precision. The study validates models for broad application in various steel types and confirms nanoindentation as an effective direct measure for HV hardness in thin films and gradient-variable regions. This work contributes a validated and versatile approach to the hardness assessment of thin-film materials and those with intricate microstructures, enhancing material characterization and potential application in advanced material engineering. [ABSTRACT FROM AUTHOR]

The intensive development of nanodevices acting as two-state systems has motivated the search for nanoscale molecular structures whose long-term conformational dynamics are similar to the dynamics of bistable mechanical systems such as Euler arches and Duffing oscillators. Collective synchrony in bistable dynamics of molecular-sized systems has attracted immense attention as a potential pathway to amplify the output signals of molecular nanodevices. Recently, pyridine-furan oligomers of helical shape that are a few nanometers in size and exhibit bistable dynamics similar to a Duffing oscillator have been identified through molecular dynamics simulations. In this article, we present the case of dynamical synchronization of these bistable systems. We show that two pyridine-furan springs connected by a rigid oligomeric bridge spontaneously synchronize vibrations and stochastic resonance enhances the synchronization effect. [ABSTRACT FROM AUTHOR]

The in-situ investigation of the nanomechanical features of the polymer graphene nanocomposites has become a challenging and an indispensable task to achieve the required application. Graphene oxide (GO) nanocomposites were prepared at 1.0% weight fraction of GO to reinforce polystyrene (PS) using solution blending approach. The morphology of the resulting nanocomposites was characterized by optical, scanning electron, transmission electron, atomic force, and scattering scanning near-field optical microscopies. These showed a uniform dispersion of graphene oxide nano-sheets in the PS matrix. By adopting Derjaguin–Muller–Toporov (DMT) formula, the nanomechanical properties for the cryogenically fractured surface of the composites were characterized using the traditional atomic force microscopy (AFM), peak-force quantitative nanomechanical mapping (QNM), and tip-force mode functioned with scattering scanning near–field optical microscopy (s-SNOM). Young's modulus of the PS matrix varied around (1–2) GPa as shown by QNM and s-SNOM similar to what was reported in the literature. However, while putative GO nano-sheets were measured to have a higher elastic modulus than the surrounding matrix in Peak-Force QNM experiments, they were significantly below literature values. By using Tip-Force mode related to s-SNOM, the expected values of Young's modulus for GO were recovered. [ABSTRACT FROM AUTHOR]

The printing and manufacturing of anatomical 3D models has gained popularity in complex surgical cases for surgical planning, simulation and training, the evaluation of anatomical relations, medical device testing and patient–professional communication. 3D models provide the haptic feedback that Virtual or Augmented Reality (VR/AR) cannot provide. However, there are many technologies and strategies for the production of 3D models. Therefore, the aim of the present study is to show and compare eight different strategies for the manufacture of surgical planning and training prototypes. The eight strategies for creating complex abdominal oncological anatomical models, based on eight common pediatric oncological cases, were developed using four common technologies (stereolithography (SLA), selectie laser sinterning (SLS), fused filament fabrication (FFF) and material jetting (MJ)) along with indirect and hybrid 3D printing methods. Nine materials were selected for their properties, with the final models assessed for application suitability, production time, viscoelastic mechanical properties (shore hardness and elastic modulus) and cost. The manufacturing and post-processing of each strategy is assessed, with times ranging from 12 h (FFF) to 61 h (hybridization of FFF and SLS), as labor times differ significantly. Cost per model variation is also significant, ranging from EUR 80 (FFF) to EUR 600 (MJ). The main limitation is the mimicry of physiological properties. Viscoelastic properties and the combination of materials, colors and textures are also substantially different according to the strategy and the intended use. It was concluded that MJ is the best overall option, although its use in hospitals is limited due to its cost. Consequently, indirect 3D printing could be a solid and cheaper alternative. [ABSTRACT FROM AUTHOR]

Despite the significant progress in protein‐based materials, creating a tunable protein‐activated hydrogel lens remains an elusive goal. This study leverages the synergistic relationship between protein structural dynamics and polymer hydrogel engineering to introduce a highly transparent protein–polymer actuator. By incorporating bovine serum albumin into polyethyleneglycol diacrylate hydrogels, the authors achieved enhanced light transmittance and conferred actuating capabilities to the hydrogel. Taking advantage of these features, a bilayer protein‐driven hydrogel lens that dynamically modifies its focal length in response to pH changes, mimicking the adaptability of the human lens, is fabricated. The lens demonstrates durability and reproducibility, highlighting its potential for repetitive applications. This integration of protein‐diverse biochemistry, folding nanomechanics, and polymer engineering opens up new avenues for harnessing the wide range of proteins to potentially propel various fields such as diagnostics, lab‐on‐chip, and deep‐tissue bio‐optics, advancing the understanding of incorporating biomaterials in the optical field. [ABSTRACT FROM AUTHOR]

The glycocalyx is a brush-like layer that covers the surfaces of the membranes of most cell types. It consists of a mixture of carbohydrates, mainly glycoproteins and proteoglycans. Due to its structure and sensitivity to environmental conditions, it represents a complicated object to investigate. Here, we review studies of the glycocalyx conducted using scanning probe microscopy approaches. This includes imaging techniques as well as the measurement of nanomechanical properties. The nanomechanics of the glycocalyx is particularly important since it is widely present on the surfaces of mechanosensitive cells such as endothelial cells. An overview of problems with the interpretation of indirect data via the use of analytical models is presented. Special insight is given into changes in glycocalyx properties during pathological processes. The biological background and alternative research methods are briefly covered. [ABSTRACT FROM AUTHOR]

Predicting faulting failure is useful in the optimal concrete pavement design. In this study, artificial neural networks and the random forest method have been used to predict the amount of this failure. The general prediction model was created by inserting 32 available input variables into artificial neural networks. An integer two objectives optimisation problem was designed to select features that significantly affect the faulting. After applying this method, 19 important variables were identified and used to develop two simplified models based on artificial neural networks and the random forest method. It is shown that the simplified model developed by artificial neural networks is the best model to accurately predict the faulting considering the number of input variables. The cumulative number of days when the precipitation is more than 12.7 mm, the elastic modulus of concrete slab, the number of days passed since the pavement was built, base thickness, the cumulative ESALs in the traffic lane, and the annual average number of days when the temperature is more than 32°C were identified as the most important parameters in predicting faulting using the random forest method. A Sensitivity analysis has been then performed on these variables and optimal values were determined. [ABSTRACT FROM AUTHOR]

Material extrusion is a popular additive manufacturing technology due to its low cost, wide market availability, ability to construct complex parts, safety, and cleanliness. However, optimizing the process parameters to obtain the best possible mechanical properties has not been extensively studied. This paper aims to develop ensemble learning-based models to predict the ultimate tensile strength, Young's modulus, and the strain at break of PLA and PLA-CF 3D-printed parts, using printing temperature, printing speed, and layer thickness as process parameters. Additionally, the study investigates the impact of process parameters and material selection on the mechanical properties of the printed parts and uses genetic algorithms for multi-objective optimization according to user specifications. The results indicate that process parameters and material selection significantly influence the mechanical properties of the printed parts. The ensemble learning predictive models yielded an R2 value of 91.75% for ultimate tensile strength, 94.08% for Young's modulus, and 88.54% for strain at break. The genetic algorithm successfully identified optimal parameter values for the desired mechanical properties. For optimal ultimate tensile strength, PLA-CF was used at 222.28 °C, 0.261 mm layer, 40.30 mm/s speed, yielding 41.129 MPa. For Young's modulus: 4423.63 MPa, PLA-CF, 200.01 °C, 0.388 mm layer, 40.38 mm/s. For strain at break: 2.249%, PLA, 200.34 °C, 0.390 mm layer, 45.30 mm/s. Moreover, this work is the first to model the process–structure property relationships for an additive manufacturing process and to use a multi-objective optimization approach for multiple mechanical properties, utilizing ensemble learning-based algorithms and genetic algorithms. [ABSTRACT FROM AUTHOR]

During surface texture micro-indentation processing, the texture around the contact area will form protrusions. The morphology of these protrusions can change the actual contact area of the contact surface and affect the functional surface. To accurately describe the morphology of surface texture protrusions during the micro-indentation process, scaled chi-square functions are proposed to fit and further analyze their morphology. By simulation, the surface protrusion curve is generated by the micro-indenter head in different materials and depths. The scaled chi-square function is used to fit the extracted curves, and the fitted n value is used as an important characteristic parameter of the protrusion morphology. The study shows that the morphology of the protrusions is related to the material's elastic modulus, yield strength, power law hardening exponent, and forming depth. Based on our results, it is convenient to judge the highest position and maximum height of the protrusions. The research findings will aid in the holistic design of micro-indentation surface textures, predicting their morphology, and selecting appropriate processes, while also being relevant for evaluating material performance post-micro-indentation with broad application prospects. [ABSTRACT FROM AUTHOR]

The Innovative Optical and Wireless Network (IOWN) will transform the information carriers not only in the transmission lines but also in the internal circuits of computers from electrical signals to optical signals. The key to achieving this is an optical transistor, which can be fabricated using photonic crystals that can confine and control the light within devices. A completely different approach to device technology, i.e., using acoustic waves (elastic waves) in the gigahertz frequency range, has also been extensively studied. As a fundamental research topic, nanomechanics is being researched to enable low-power information processing and ultra-sensitive signal detection by controlling the propagation of acoustic waves in the nanoscale domain. One of the techniques studied in nanomechanics is the use of a nanoscale artificial structure called phononic crystal, which confines and controls the acoustic waves in a device. We interviewed Hiroshi Yamaguchi, an NTT Fellow at NTT Basic Research Laboratories, who is engaged in research on nanomechanics, about the current status and future prospects of his research, changes in the circumstances surrounding the basic research, and his thoughts on how researchers should conduct their research with those changes in mind. [ABSTRACT FROM AUTHOR]

Instrumented indentation is a versatile method of extracting hyper-elastic material parameters, particularly useful for applications where stress-strain data are difficult to be in-situ measured. Because the analytical force-displacement relation is still unavailable for the indentation of hyper-elastic materials, identifying hyper-elastic parameters often requires an iterative optimization strategy that fits finite element simulations with experimental data. However, the optimization strategy is burdened by heavy computation and its prediction accuracy is greatly influenced by the choice of optimization algorithm. To address these challenges in this study, a bidirectional long short-term memory (BLSTM) neural network is presented that directly predicts hyper-elastic material parameters from indentation load-displacement data, focusing on Mooney-Rivlin hyper-elasticity as an example. To improve the predication accuracy, the condition numbers for the inverse identification of the hyper-elastic parameters are investigated. And, a normalization procedure is proposed to treat the input data, which can guarantee the BLSTM network is well-conditioned. During evaluation, the trained BLSTM network significantly outperforms the iterative optimization strategy using a genetic algorithm. Furthermore, the effect of the normalization procedure is demonstrated. [ABSTRACT FROM AUTHOR]

It is well established that UV radiation can inactivate bacteria by destroying DNA in the cell envelope, and maintaining the integrity of the cellular membrane. However, how UV radiation changes the surface properties and thus affects bacterial adhesion remain elusive. In this study, single‐cell force spectroscopy is employed to examine the surface nanomechanics of Pseudomonas aeruginosa under UV exposure. It shows that P. aeruginosa became stiffer after UV radiation, and its adhesion to silicon surface decreases with rupture length increasing. Nanospring signatures in the retraction force curve become less with lower spring constant but more plateau signatures with higher rupture length appear. These facts indicate the unfolding of the α‐helices of the pili. Besides, the worm‐like chain force curves with higher contour length indicate the structural degradation of transmembrane proteins or surface macromolecules obstruction. Accordingly, the bacterial adhesion decreases after UV radiation. [ABSTRACT FROM AUTHOR]

This study employs molecular dynamics simulations to explore nanoscale friction behaviour as a function of varying loading and sliding speeds on a developed top-layer articular cartilage contact interface atomistic model. To investigate nanotribological behaviour, sliding speed variations on the normal force, friction force, non-bonded interaction energy and interface temperature is obtained at the inter-cartilage interface. Analysis conducted at high velocity in a simplified tissue-like hydrated environment revealed ice-like dynamic smooth sliding behaviour of protein chains when cartilage interfaces are even 3.8 Å apart. With an increase in velocity, the coefficient of friction (COF) increases significantly in a hydrated environment. Additionally, at lower loads, the effect of sliding velocity is more pronounced than at higher loads. However, results show that articular cartilage adapts to higher load and speed sliding conditions exhibiting lower friction (COF-0.03–1.17) by means of interfacial water rearrangements and protein side-chain non-bonded interactions reducing heavy shear deformation. This is attributed to an alteration in the load-bearing and friction mechanism owing to water rearrangement and adsorption at nanoconfined biointerfaces. This study provides mechanistic insights into friction mechanisms at the cartilage interface which could lead to wear-like conditions under physiological sliding contact conditions, thereby facilitating the design of better implants. [ABSTRACT FROM AUTHOR]

The thermal quality factor of micro/nano-resonators, which regulates the energy dissipation through the connection of the mechanical and thermal behaviour, is greatly influenced by the static pre-stress and thermal lag times. To raise the thermal quality factor, a novel analytical model in this study that considers a static pre-stress in a micro-resonator has been constructed based on the dual-phase-lag heat conduction model. On the thermal quality factor, the impacts of length scale, static pre-stress, and thermal lag times have been discussed. According to the model, adjusting the static pre-stress might result in a considerable improvement in terms of the dimensionless thermal quality factor. Moreover, the beam's length scale and thermal lag times have significant effects on the thermal quality factor of the resonators. [ABSTRACT FROM AUTHOR]

Cholesteatoma can lead to progressive destruction of the auditory ossicles along with conductive hearing loss but precise data on the microstructural, cellular, and compositional aspects of affected ossicles are not available. Here, we obtained incus specimens from patients who had cholesteatoma with conductive hearing loss. Incudes were evaluated by micro-computed tomography, histomorphometry on undecalcified sections, quantitative backscattered electron imaging, and nanoindentation. Results were compared with two control groups taken from patients with chronic otitis media as well as from skeletally intact donors at autopsy. The porosity of incus specimens was higher in cholesteatoma than in chronic otitis media, along with a higher osteoclast surface per bone surface. Histomorphometric assessment revealed higher osteoid levels and osteocyte numbers in cholesteatoma incudes. Incudes affected by cholesteatoma also showed lower matrix mineralization compared with specimens from healthy controls and chronic otitis media. Furthermore, the modulus-to-hardness ratio was higher in cholesteatoma specimens compared with controls. Taken together, we demonstrated increased porosity along with increased osteoclast indices, impaired matrix mineralization, and altered biomechanical properties as distinct features of the incus in cholesteatoma. Based on our findings, a possible impact of impaired bone quality on conductive hearing loss should be further explored. [ABSTRACT FROM AUTHOR]

Soft bioelectronic interfaces constitute a paradigm shift for biomedical devices. High‐resolution monitoring and stimulation of physiological processes in vivo are becoming possible with minimally invasive devices operated without inflicting tissue damage or discomfort over prolonged timescales. However, the development and commercialization of such interfaces still must address significant challenges. Biological tissue is subjected to continuous motion and the related device deformations can easily trigger fracture or delamination of the device components, putting long‐term durability of soft implants at risk. In this review, an overview of experimental techniques for testing mechanical properties and failure mechanisms of soft bioelectronic devices at the nanoscale while the deformation takes place (in situ) is provided. Through the tensile test, bending test, nanoindentation, and micropillar compression test, precise measurements of the mechanical properties of individual building blocks and the interfaces themselves can be obtained. Such parameters are crucial to design, model, and optimize the device's performance. Then, recent examples of how this information guides design and optimization of soft bioelectronic interfaces and devices for healthcare, robotics, and human–machine interfaces is provided. Last of all, future research that is needed to fully achieve long‐term soft bioelectronic interfaces for integration with the human body is discussed. [ABSTRACT FROM AUTHOR]

Electrodeposited cobalt coatings have been considered a suitable replacement for hard chromium coatings due to their promising properties. In this research, electrochemical methods through the direct current technique have been applied to synthesize a novel Co–P–ZrO 2 –CeO 2 nanocomposite coating. The addition of different phosphorous contents as a determinant of the crystalline or amorphous structure was investigated using X-ray diffraction (XRD). The needle-like or cauliflower morphologies and related elemental compositions were surveyed by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS), respectively. The XRD, microhardness, wear, and corrosion resistance tests were conducted on heat-treated samples. The results illustrate that heat treatment significantly increases the microhardness of the amorphous nanocomposite layer (up to 1323 HV 0.1). Additionally, it causes the best wear behavior for the nanocrystalline Co–P–ZrO 2 –CeO 2 (0.2), while leading to a lower wear resistance for the amorphous coatings (0.65). Furthermore, applying heat treatment diminishes the corrosion behavior of the coating. Tafel polarization and electrochemical impedance spectroscopy (EIS) tests reveal that the best corrosion resistance has been achieved for an amorphous nanocomposite coating 11929 Ω cm2. These findings demonstrate that this coating has desirable properties for industrial applications. [ABSTRACT FROM AUTHOR]

Polymers find widespread applications in various industries, such as civil engineering, aerospace, and industrial machinery, contributing to vibration control, dampening, and insulation. To accurately design products that are able to predict their dynamic behavior in the virtual environment, it is essential to understand and reproduce their viscoelastic properties via material physical modeling. While Dynamic Mechanical Analysis (DMA) has traditionally been used, innovative non-destructive techniques are emerging for characterizing components and monitoring their performance without deconstructing them. In this context, the Time–Temperature Superposition Principle (TTSP) represents a powerful empirical procedure to extend a polymer's viscoelastic behavior across a wider frequency range. This study focuses on replicating an indentation test on viscoelastic materials using the non-destructive Viscoelasticity Evaluation System evolved (VESevo) tool. The primary objective is to derive a unique temperature–frequency relationship, referred to as a "shift law", using characteristic curves from this non-invasive approach. Encouragingly, modifying the device setup enabled us to replicate, virtually, three tests under identical initial conditions but with varying indentation frequencies. This highlights the tool's ability to conduct material testing across a range of frequencies. These findings set the stage for our upcoming experiment campaign, aiming to create an innovative shift algorithm from at least three distinct master curves at specific frequencies, offering a significant breakthrough in non-destructive polymer characterization with broad industrial potential. [ABSTRACT FROM AUTHOR]

In this study, our objective is to investigate the anisotropic deformation behavior and the indentation size effect (ISE) of monocrystalline barium fluoride (BaF2) using nanoindentation experiments with a diamond Berkovich indenter. BaF2 is known for its anisotropy, which results in significant variations in its mechanical properties. This anisotropy poses challenges in achieving high processing quality in ultra-precision machining. Through our experiments, we observed numerous pop-in events in the load–displacement curves, indicating the occurrence of plastic deformation in BaF2 crystals, specifically in the (100), (110), and (111) orientations; these pop-in events were observed as the indentation depth increased to 56.9 nm, 58.2 nm, and 57.8 nm, respectively. The hardness–displacement and elastic modulus–displacement curves were obtained from the tests exhibiting the ISE. The nanoindentation hardness of BaF2 is found to be highly dependent on its crystallographic orientation. Similarly, for BaF2 in the (100) orientation, the range is from 2.43 ± 0.74 and 1.24 ± 0.12 GPa. For BaF2 in the (110) orientation, the values range from 2.15 ± 0.66 to 1.18 ± 0.15 GPa. For BaF2 in the (111) orientation, the values range from 2.12 ± 0.53 GPa to 1.19 ± 0.12 GPa. These results highlight the significant influence of crystallographic orientation on the mechanical properties of BaF2. To better understand the ISE, we employed several models including Meyer's law, the Nix–Gao model, the proportional specimen resistance (PSR) model, and the modified PSR (mPSR) model, and compared them with our experimental results. Among these models, the mPSR model demonstrated the best level of correlation ( R 2 > 0.9999 ) with the experimental measurements, providing a reliable description of the ISE observed in BaF2. Our reports provide valuable insights into the anisotropic mechanical characteristics of BaF2 materials and serve as a theoretical guide for the ultra-precision machining of BaF2. [ABSTRACT FROM AUTHOR]

Morphological characterization of fabricated MXene (M-X) Polymeric nanocomposites (M-X@PNC) is critically imperative for in depth appraisal of surface-topographical and compositional evaluation of M-X@PNC. The garnered properties of M-X@PNC are function of the degree of nanoparticulate distribution and embedment within the polymeric matrices and their overall effectiveness at improving the nanocomposites properties, vis-a-viz mechanical, heat dissipation as well as heat deflection properties along with potential applications. Inherently interacting functional entities within M-X@PNC architecture are basis for garnered properties including flammability, chemical, thermal, electrical conductivity and so on, which directly affect potential applications. Thus, this paper elucidates the influence of morphology and architecture on M-X@polymeric nanoarchitectures properties and applications. Graphical Abstract [ABSTRACT FROM AUTHOR]

Graphyne is a material that has unique mechanical properties, but little is known about how these properties change when the material has holes. In this work, the effect of hole geometry, considering circular, triangle, and rhombus hole configurations, on the mechanical nonlinear response of γ-graphyne structures is studied. Graphyne, graphdiyne, graphyne-3, and graphyne-4 structures are under investigation. An efficient nonlinear finite element analysis (FEA) method is adequately implemented under large deformations for this purpose. The study varied the size and shape of the holes to understand how these changes affect the nanostructure's mechanical response. The results indicate that the hole geometry significantly impacts the mechanical nonlinear response of γ-graphyne structures. The holes' size and shape affect the structures' elastic behavior, deformation, and strength. The findings can be used to optimize the design of γ-graphyne structures for specific mechanical applications. The study highlights the importance of considering the hole geometries in the design and fabrication of these materials. [ABSTRACT FROM AUTHOR]

A cell's mechanical properties have been linked to cancer development, motility and metastasis and are therefore an attractive target as a universal, reliable cancer marker. For example, it has been widely published that cancer cells show a lower Young's modulus than their non-cancerous counterparts. Furthermore, the effect of anti-cancer drugs on cellular mechanics may offer a new insight into secondary mechanisms of action and drug efficiency. Scanning ion conductance microscopy (SICM) offers a nanoscale resolution, non-contact method of nanomechanical data acquisition. In this study, we used SICM to measure the nanomechanical properties of melanoma cell lines from different stages with increasing metastatic ability. Young's modulus changes following treatment with the anti-cancer drugs paclitaxel, cisplatin and dacarbazine were also measured, offering a novel perspective through the use of continuous scan mode SICM. We found that Young's modulus was inversely correlated to metastatic ability in melanoma cell lines from radial growth, vertical growth and metastatic phases. However, Young's modulus was found to be highly variable between cells and cell lines. For example, the highly metastatic cell line A375M was found to have a significantly higher Young's modulus, and this was attributed to a higher level of F-actin. Furthermore, our data following nanomechanical changes after 24 hour anti-cancer drug treatment showed that paclitaxel and cisplatin treatment significantly increased Young's modulus, attributed to an increase in microtubules. Treatment with dacarbazine saw a decrease in Young's modulus with a significantly lower F-actin corrected total cell fluorescence. Our data offer a new perspective on nanomechanical changes following drug treatment, which may be an overlooked effect. This work also highlights variations in cell nanomechanical properties between previous studies, cancer cell lines and cancer types and questions the usefulness of using nanomechanics as a diagnostic or prognostic tool. [ABSTRACT FROM AUTHOR]

Single Point Incremental Forming process is subjected to the complex state of stresses that lead to plastic deformation instabilities during the process. Apart from formability and deformation analyses, the characterization and prediction of damage and or fracture in SPIF is of utmost importance. Prediction of fracture in SPIF by continuum-based models is satisfactory for low triaxiality conditions. However, fracture prediction under high stress triaxiality conditions i.e., under biaxial stresses in SPIF still needs attention. For this purpose, an accurate identification and characterization of damage model parameters is of utmost importance as the prediction accuracy of damage model majorly depends on it. In this work, a modified microhardness-based approach to damage parameter characterization is presented for predicting ductile fracture under biaxial stresses in SPIF. Strategy has been proposed to evaluate damage parameter (D) for Lemaitre continuum damage models by evaluating micro-hardness in the through-thickness direction of the fractured SPIF samples. Additionally, a methodology is proposed to evaluate hypothetical hardness by precisely obtaining the plastic stress–strain characteristics of the AA1050 H14 material subjected to biaxial straining. Prior to indentation test, in SPIF, Digital Image Correlation (DIC) technique is utilized to evaluate true plastic strain and thickness strain values. The values of damage parameter obtained from conventional as well as revised approaches are used to simulate fracture in SPIF by incorporating Lemaitre damage model as a user subroutine (VUMAT) in Abaqus software. Experimentally obtained maximum plastic strain and wall thickness are compared to simulated maximum plastic strains subjected to conventional and revised methodology. [ABSTRACT FROM AUTHOR]

The widely overlapping physicochemical properties of lipoproteins (LPs) and extracellular vesicles (EVs) represents one of the main obstacles for the isolation and characterization of these pervasive biogenic lipid nanoparticles. We herein present the application of an atomic force microscopy (AFM)‐based quantitative morphometry assay to the rapid nanomechanical screening of mixed LPs and EVs samples. The method can determine the diameter and the mechanical stiffness of hundreds of individual nanometric objects within few hours. The obtained diameters are in quantitative accord with those measured via cryo‐electron microscopy (cryo‐EM); the assignment of specific nanomechanical readout to each object enables the simultaneous discrimination of co‐isolated EVs and LPs even if they have overlapping size distributions. EVs and all classes of LPs are shown to be characterised by specific combinations of diameter and stiffness, thus making it possible to estimate their relative abundance in EV/LP mixed samples in terms of stoichiometric ratio, surface area and volume. As a side finding, we show how the mechanical behaviour of specific LP classes is correlated to distinctive structural features revealed by cryo‐EM. The described approach is label‐free, single‐step and relatively quick to perform. Importantly, it can be used to analyse samples which prove very challenging to assess with several established techniques due to ensemble‐averaging, low sensibility to small particles, or both, thus providing a very useful tool for quickly assessing the purity of EV/LP isolates including plasma‐ and serum‐derived preparations. [ABSTRACT FROM AUTHOR]

In recent years, the two-dimensional (2D) orthorhombic SiP2 flake has been peeled off successfully by micromechanical exfoliation and it exhibits an excellent performance in photodetection. In this paper, we investigated the mechanical properties and the origin of its anisotropy in an orthorhombic SiP2 monolayer through first-principles calculations, which can provide a theoretical basis for utilizing and tailoring the physical properties of a 2D orthorhombic SiP2 in the future. We found that the Young's modulus is up to 113.36 N/m along the a direction, while the smallest value is only 17.46 N/m in the b direction. The in-plane anisotropic ratio is calculated as 6.49, while a similar anisotropic ratio (~6.55) can also be observed in Poisson's ratio. Meanwhile, the in-plane anisotropic ratio for the fracture stress of the orthorhombic SiP2 monolayer is up to 9.2. These in-plane anisotropic ratios are much larger than in black phosphorus, ReS2, and biphenylene. To explain the origin of strong in-plane anisotropy, the interatomic force constants were obtained using the finite-displacement method. It was found that the maximum of interatomic force constant along the a direction is 5.79 times of that in the b direction, which should be considered as the main origin of the in-plane anisotropy in the orthorhombic SiP2 monolayer. In addition, we also found some negative Poisson's ratios in certain specific orientations, allowing the orthorhombic SiP2 monolayer to be applied in next-generation nanomechanics and nanoelectronics. [ABSTRACT FROM AUTHOR]

Neurodegenerative disorders (NDDs) are complex, multifactorial disorders with significant social and economic impact in today's society. NDDs are predicted to become the second-most common cause of death in the next few decades due to an increase in life expectancy but also to a lack of early diagnosis and mainly symptomatic treatment. Despite recent advances in diagnostic and therapeutic methods, there are yet no reliable biomarkers identifying the complex pathways contributing to these pathologies. The development of new approaches for early diagnosis and new therapies, together with the identification of non-invasive and more cost-effective diagnostic biomarkers, is one of the main trends in NDD biomedical research. Here we summarize data on peripheral biomarkers, biofluids (cerebrospinal fluid and blood plasma), and peripheral blood cells (platelets (PLTs) and red blood cells (RBCs)), reported so far for the three most common NDDs—Alzheimer's disease (AD), Parkinson's disease (PD), and amyotrophic lateral sclerosis (ALS). PLTs and RBCs, beyond their primary physiological functions, are increasingly recognized as valuable sources of biomarkers for NDDs. Special attention is given to the morphological and nanomechanical signatures of PLTs and RBCs as biophysical markers for the three pathologies. Modifications of the surface nanostructure and morphometric and nanomechanical signatures of PLTs and RBCs from patients with AD, PD, and ALS have been revealed by atomic force microscopy (AFM). AFM is currently experiencing rapid and widespread adoption in biomedicine and clinical medicine, in particular for early diagnostics of various medical conditions. AFM is a unique instrument without an analog, allowing the generation of three-dimensional cell images with extremely high spatial resolution at near-atomic scale, which are complemented by insights into the mechanical properties of cells and subcellular structures. Data demonstrate that AFM can distinguish between the three pathologies and the normal, healthy state. The specific PLT and RBC signatures can serve as biomarkers in combination with the currently used diagnostic tools. We highlight the strong correlation of the morphological and nanomechanical signatures between RBCs and PLTs in PD, ALS, and AD. [ABSTRACT FROM AUTHOR]

We analyze wave equation for spatially one-dimensional continuum with constitutive equation of non-local type. The deformation is described by a specially selected strain measure with general fractional derivative of the Riesz type. The form of constitutive equation is assumed to be in strain-driven type, often used in nano-mechanics. The resulting equations are solved in the space of tempered distributions by using the Fourier and Laplace transforms. The properties of the solution are examined and compared with the classical case. [ABSTRACT FROM AUTHOR]

Background: Running with the appropriate intensity may produce a positive influence on the mechanical properties of cortical bone structure. However, few studies have discussed the effects of different running intensities on the mechanical properties at different levels, especially at the micro-level, because the micromechanical parameters are difficult to measure experimentally. Methods: An approach that combines finite element analysis and experimental data was proposed to predict a micromechanical parameter in the rat femoral cortical bone structure, namely, the micro-level failure strain. Based on the previous three-point bending experimental information, fracture simulations were performed on the femur finite element models to predict their failure process under the same bending load, and the micro-level failure strains in tension and compression of these models were back-calculated by fitting the experimental load–displacement curves. Then, the effects of different running intensities on the micro-level failure strain of rat femoral cortical bone structure were investigated. Results: The micro-level failure strains of the cortical bone structures expressed statistical variations under different running intensities, which indicated that different mechanical stimuli of running had significant influences on the micromechanical properties. The greatest failure strain occurred in the cortical bone structure under low-intensity running, and the lowest failure strain occurred in the structure under high-intensity running. Conclusions: Moderate and low-intensity running were effective in enhancing the micromechanical properties, whereas high-intensity running led to the weakening of the micromechanical properties of cortical bone. Based on these, the changing trends in the micromechanical properties were exhibited, and the effects of different running intensities on the fracture performance of rat cortical bone structures could be discussed in combination with the known mechanical parameters at the macro- and nano-levels, which provided the theoretical basis for reducing fracture incidence through running exercise. [ABSTRACT FROM AUTHOR]

The material performance simulation software JMatPro was used to simulate and calculate equilibrium phase structure and properties of a mixture formed by mixing different proportions of Norem02 alloy and F304 stainless steel. The results show that in the range of 500-1300 °C, equilibrium phases of the mixture include Austenite and Ferrite, and the carbides include M2(C,N), M6C, M7C3 and M23C6. As the content of F304 in the mixture increases, the phase transition temperature A1 of the mixture decreases, and A3 first decreases and then increases; in the equilibrium phase, the content of Austenite and Ferrite increases, and the content of carbide decreases until the carbides M7C3 and M6C gradually disappear. Density, coefficient of linear expansion, thermal conductivity, Young's modulus, Poisson's ratio and specific heat capacity of different mixture materials vary with temperature in a complex manner. Strength and hardness of the mixture formed when the content of F304 is 20 % is the highest. The finer the grain size of the mixture, the higher the strength and hardness of the material. Comparing standard physical property data of F304 stainless steel at room temperature with the simulation calculation results, it is found that the error is small, which verifies the accuracy of the simulation calculation results. [ABSTRACT FROM AUTHOR]

Micro‐arc oxidation (MAO) is a surface treatment technology that enhances the surface properties of valves by creating a ceramic oxide layer on the metal surface. The goal of this study is to investigate the influence of current density on the properties of aluminum coatings during preparation and to improve the tribological properties of MAO/PTFE self‐lubricating films on the coating surface. The characterization of the coating was performed using X‐ray photoelectron spectroscopy, X‐ray diffraction, Raman spectra, and energy dispersive spectroscopy. The roughness, hardness, and elastic modulus of the coatings were tested using atomic force microscopy and nanoindentation. Tribological experiments were conducted to evaluate the tribological properties of the coatings. The experimental results show that the friction coefficient (COF), roughness, hardness, and elastic modulus of the MAO coating increase with the increase of current density. Additionally, the friction coefficient of the MAO composite coating significantly decreases after the addition of polytetrafluoroethylene (PTFE), improving the service life and application range of the metal coating. These findings are expected to promote the development of valve metal in various application fields. [ABSTRACT FROM AUTHOR]

In this Letter, the structural, mechanical, electronic, and transport properties of two-dimensional (2D) ternary Janus Si 2 X Y (X / Y = S, Se, Te) monolayers are studied based on the calculations using first-principles density functional theory. All three structures are found as direct semiconductors with moderated bandgap energies and good stabilities for experimental synthesis. The transport properties are also examined by calculating the carrier mobilities. We find that the carrier mobilities of all three monolayers are anisotropic not only between the electrons and holes but also between the two transport directions. The Si2SSe monolayer exhibited the highest electron mobility of 897.66 cm2 V−1 s−1 in the x axis. Amazingly, our calculations reveal that the Si 2 X Y monolayers are auxetic materials with negative Poisson's ratio along both x and y axes. Particularly, the Si2SSe has the largest negative Poisson's ratio value of –0.131 in the x direction. These obtained results open more prospects for advanced applications of these materials in electronics, optoelectronics, and nanomechanics. [ABSTRACT FROM AUTHOR]

This study investigated a new colloidal ink, containing Laponite® nanoclay as additive, to develop ZrO 2 -based ceramic prototypes by Direct Ink Writing (DIW). The ink developed contained 31 vol% 3Y-TZP as solid load and 69% v/v of gel containing 7.5% (w/w) Laponite®, polyethylene glycol (PEG), and dibutyl phthalate. The rheologyical behavior of this ceramic ink was analyzed and its extrudability was optimized. The samples were DIW 3D-printed at a speed of 10 mm/s with nozzle diameter of 0.41 mm. After drying for 24 h, the zirconia samples underwent debinding and were pre-sintered at 1100 °C under a heating rate of 1 °C/min. After pre-sintering, the samples were sintered at 1550 °C for 2 h. Subsequently, the sintered samples were characterized by Scanning Electron Microscopy and X-ray diffractometry. Fracture toughness was measured by Vickers indentation, whereas nano-hardness and Young's modulus were assessed by dynamic Vickers nanoindentation (250–1960 mN loads). A relative density of 89.3 ± 0.5% was found. The following crystalline phases were observed: monoclinic-ZrO 2 (34%), tetragonal-ZrO 2 (31%), and cubic-ZrO 2 (35%). This behavior is probably due to the segregation of Y+3 between the zirconia grains, favored by the presence of Laponite® nanoclay during the sintering process. The microstructure of the prototypes showed two distinct populations of ZrO 2 grains with average particle sizes of 1 μm (monoclinic and tetragonal phases) and >5 μm (cubic phase). Vickers hardness (HV 1000gF) was 952 ± 40 HV and fracture toughness was 4.6 ± 1.1 MPa m1/2. A Young's modulus of ∼200 GPa and hardness values of 1837.9 and 1943.3 HV were found for loads of 250 and 1960 mN, respectively. [ABSTRACT FROM AUTHOR]