Young's Modulus Research Articles

First-principles study of Y, Ca microalloyed Mg-Zn alloy

This article investigates the complex effects of Y and Ca alloying on the G.P. zones ( parallel to {0001}Mg)and G.P.1 zones ( parallel to {2-1-10}Mg) in Mg-Zn alloys, as well as their corresponding changes in thermal stability, electronic structure, and mechanical properties, using first-principles calculations. The addition of Y significantly enhances the thermal stability of both the G.P. and G.P.1 zones, whereas the effect of Ca is more limited, mainly enhancing the thermal stability of the one-atomic layer G.P. zones, but possibly decreasing the thermal stability in other areas. In the combined alloying of Y and Ca, the cooperative effect optimizes the thermal stability of the one-atomic layer and half-atomic layer G.P.1 zones, but reduces the thermal stability of other G.P. zones. Through studying the local density of states and the atomic radial distribution function, it is revealed that the higher stability of the half-atomic layer G.P. zones compared to the one-atomic layer G.P. zones is due to more Mg-Zn and Mg-Mg bonds, whereas the one-atomic layer G.P.1 zones exhibits higher stability because of shorter and more stable Zn-Zn, Mg-Zn, and Zn-Mg bonds. The electronic structure analysis shows that Y mainly appears in the alloy in the form of electron localization, readily forming ionic bonds with Mg and Zn, which is a key reason for its effective alloying results. In contrast, Ca, as well as the alloying of Y and Ca, do not form effective bonds on the energy levels from -8eV to -5eV, explaining their weaker alloying effects. Additionally, the study of mechanical properties indicates that the G.P. zones of pure Zn, due to its significant difference in shear modulus from the magnesium matrix, is not easily strengthened by dislocation shearing and thus mainly strengthened through the Orowan mechanism. The addition of Y significantly increases the strength and hardness of the one-atomic layer G.P. zones, but decreases the ductility. The addition of Ca changes the anisotropy of the Young's modulus of the one-atomic layer G.P. zones, while the combined effect of Y and Ca greatly alters the anisotropy of the shear modulus of this phase. These findings provide important theoretical guidance and insights for the design and application of Mg-Zn alloys.

Effects of aging on the tensile strength and surface condition of orthodontic aligners: a comparative study of five models.

The objective of this study is to determine the effect of aging on tensile strength and surface condition of orthodontic aligners on days 0, 1, 5, 7, 10, and 14. The total sample of 80 aligners included five brands (Accusmile®, Angel®, GRAPHY®, Invisalign® and Suresmile®) were placed in a thermocycler to imitate the temperature variations of the oral cavity and accelerate aging for 50, 250, 350, 500, and 700 cycles. The mechanical tensile properties (Young's modulus E, yield strength YS, maximum elastic stress MES, Ultimate Tensile Strength UTS, and maximum stress MS) were measured by Universal Testing Machine at a rate of 5 mm of deformation per minute for 4 minutes. Microscopic observations were made under a voltage of 10 kV at magnifications times 50, 250, 500, 1000, and 2500 after cleaning with ethanol and ultrasound then metallization with gold. YS and MES of Angel® aligners are statistically reduced after five days of aging (P = .003). Aligners from the most rigid to the most flexible are (decreasing E): Accusmile® > GRAPHY® > Suresmile® > Invisalign® > Angel®. Surface conditions also deteriorated with aging (appearance of scratches, porosity, cracks, etc.). GRAPHY® aligners are more heterogeneous and weaker than others. In vitro study. Mechanical properties of Accusmile®, GRAPHY®, Invisalign®, and Suresmile® were not affected by aging. YS and MES were reduced from day 5 for Angel® aligners. Surface conditions are also altered by aging.

Effect of boron doping on the irradiation resistance of iron phosphate glass: Insights from mechanical properties and chemical stability

We investigated the ion-irradiation effects of iron phosphate glasses (IPGs) with composition of 40Fe2O3‒60P2O5 (mol%) and 10B2O3‒36Fe2O3‒54P2O5 (mol%), respectively, and explored the effect of boron doping on the mechanical properties and the chemical stability. Mono-ion irradiation (5-MeV Xe20+) and sequential irradiation scenario (5-MeV Xe20++ 250-keV H+) were performed with different doses. As the Xe-dose increased, both the hardness and the Young's modulus decreased until converging to saturation, and then the hardness tended to recover. The variations in mechanical properties and water contact angle of the 10B2O3‒36Fe2O3‒54P2O5 were more significant than those of the 40Fe2O3‒60P2O5, indicating inferior irradiation resistance. The hardness recovery was also observed in H-ion irradiation whose energy deposition is predominated by electronic interaction, while the boron doping weakened this phenomenon. Our study contributes to understanding the long-term behavior of IPG during the underground disposal of high-level waste, and provides fundamental data to optimize the design of IPG formulations.

A holistic approach of stability using material parameters of manipulators

The demand for a comprehensive method to assess stability using manipulator material parameters is high. Various material parameters, such as the Young modulus, which represents stiffness, damping, and deflection, influence the material of the robot manipulator. The correlation between robot stability and these characteristics remains unclear, as prior studies have not yet examined the collective impact of these parameters on robot manipulators. This work considers two sophisticated manipulators, namely ABB and FANUC. The main objective of this research is to construct a stability model that considers the material properties of stiffness, damping, and deflection to assess the manipulator’s stability level, which may be categorized as low, medium, or high. Furthermore, the presented stability model examines and employs numerous modified and conventional formulas for material properties to determine the level of stability. The findings show that stiffness significantly influences the stability of robot manipulators, a relationship that applies to all the examined manipulators. We also emphasize that the choice of manipulator materials significantly impacts stability maintenance. These findings are expected to enhance the design and advancement of novel robot manipulators within the industry.

Mechanical properties and deformation mechanism of defected NiCrCoFeMn alloys

This study provides new insights into the mechanical properties and deformation behavior of single-crystal NiCrCoFeMn high entropy alloys (HEAs) containing circular and block defects, using molecular dynamics (MD) simulations. It explores the effects of varying defect sizes, substrate temperatures, and strain rates on the material’s response under uniaxial tension. The results reveal that mechanical properties such as yield stress and Young's modulus decrease as defect size increases. Specifically, the stress concentration factor (SCF) increases as the radius of circular defects expands from 15 to 30Å, and initially rises with block defects up to 35.36×35.36Ų, but decreases as their size increases. The deformation mechanism starts with local strain nucleating around the circular defect and at the corners of the block defect, underscoring the significant role of defect shapes in initiating deformation across all samples. During uniaxial tension, phase transformations occur, resulting in the formation of stacking faults (SF), twinning (T), and partial dislocations (PD). Additionally, higher strain rates markedly boost the development of HCP, BCC, and amorphous structures. Dislocations initially form around defect shapes and extend towards free surfaces as strain escalates. Predominant dislocations during deformation include Shockley partial and Stair-rod dislocations. The total dislocation length increases with smaller defect sizes and higher strain rates, while it decreases at elevated temperatures due to enhanced atomic mobility, which facilitates dislocation movement and annihilation.

Reinforcing chitosan film with a natural nanofiller “Zein-methyl cellulose loaded curcumin” for improving its physicochemical properties and wound healing activity

Selecting the appropriate biomaterials for fabricating a wound dressing is an essential issue for accelerating the process of wound healing. The biopolymer “chitosan” attracted attention owing to its non-toxicity, biocompatibility, and biodegradability. However, chitosan showed poor mechanical, antioxidant and antibacterial properties. These limitations can be encountered by its conjugation with a nanofiller reinforcing and improving the film properties. The proposed nanofiller, derived from zein-methylcellulose loaded curcumin (ZeinMCNPs) was incorporated with different concentrations into a chitosan matrix (Ch) forming Ch/ZeinMCNPs1-3 films. Ch/ZeinMCNPs3 film showed a significant improvement in tensile strength, elongation at break% and Young's modulus over Ch film. Notably, the antibacterial and antioxidant activities of the Ch/ZeinMCNP1-3 films signified enhancement over chitosan. In wound rat model, wound healing contraction reached 96% and 98% for Ch/ZeinMCNPs2,3 opposite to 79% for Ch film. In Ch/ZeinMCNPs2,3 treated wounds, H&E tissues sections revealed a reduction in inflammation, an enhancement in re-epithelization and neovascularization. Furthermore, Ch/ZeinMCNPs2,3 films boosted more collagen deposition as shown in MTC sections. Ch/ZeinMCNPs2,3 significantly increased SOD level (at day 7 and14) with a decrease in MDA level. Overall, the present study declares Ch/ZeinMCNPs nanocomposite film as a multifunctional wound dressing category covering the necessitates required for accelerating wound healing process safely.

Performance and Hydration Mechanism of Fly Ash Coal-Based Solid Waste Backfill Material Affected by Multiple Factors

Masses of coal-based solid waste like fly ash are emitted during coal combustion, with low utilization rate. Preparing fly ash into backfill material can not only improve waste utilization efficiency, but also repair the cracks in mining areas. In this research, the performance and hydration mechanism of fly ash coal-based solid waste backfill material were investigated through slurry performance experiment, mechanical strength test and microstructure analysis. Besides, the grouting effect of the backfill material was verified by grouting experiment. The research demonstrated that the increase of fly ash to cement ratio (from 0.5 to 1.5) improved the fluidity, viscosity and bleeding rate of the slurry, but prolonged the setting time. The adjustability of backfill material was good, and the compressive strength of specimen reached its highest value of 27.1 Mpa through changing multiple factors. The grouting effect of fine-grained macadam was better than that of coarse-grained macadam. The compressive strength and Young's modulus of the backfill material specimens containing 0.5-1cm macadam were 12.2% and 17.4% higher, respectively, than those with 1-2cm macadam. The primary hydration product of backfill material was gel, which structural elements were Si, Al and Ca. As the curing age increased, the distribution of the three elements became denser, and more gel was formed, corresponding to the changes in the compressive strength of the backfill material. The research offers material source and selection basis for backfilling cracks in mining areas and enhances utilization efficiency of coal-based solid waste.

Triaxial test on load-bear capacity of the vibro-compaction coral sand foundation in the South China Sea

Vibro-compaction is the main improvement method for hydraulic reclamation coral sand sites. Currently, the load-bearing characteristics of coral sand composite foundation reinforced by vibro-compaction have not been clarified. This paper investigates strength characteristics of coral sand composite samples (core and shell) by artificially preparing radial variable-density coral sand composite samples and performing consolidated drained triaxial tests under different area replacement rates, core-shell density ratios, and confining pressures. The results of the study show that the contribution of the core gradually increases with the increasing area replacement rate. The peak strength and peak friction angle of samples also increase gradually, but the growth tendency gradually slows down. The stress concentration coefficient of sample core is variable and follows a development pattern of first increasing and then decreasing. The secant Young's modulus of composite samples increases in a power function type with the increase of area replacement rate. The particle breakage of samples is mainly the rupture and abrasion of the 0.5-1 mm and 0.1-0.25 mm particle groups that serve as fillers. The research results can provide technical support for coral reef engineering construction.

Impact of Antioxidants on Mechanical Properties and ROS levels of Neuronal Cells Exposed to β-amyloid peptide.

This study aims to investigate the potential role of antioxidants in oxidative stress and its consequent impact on the mechanical properties of neuronal cells, particularly the stress induced by amyloid-beta (1-42) (Aβ42) aggregates. A key aspect of our research involved using scanning ion-conductance microscopy (SICM) to assess the mechanical properties (Young's modulus) of neuronal cells under oxidative stress. Reactive oxygen species (ROS) level was measured in single-cell using the electrochemical method by low-invasive Pt nanoelectrode. We investigated the effects of the low molecular weight antioxidant N-acetylcysteine (NAC) and the antioxidant enzyme superoxide dismutase 1 (SOD1) on the physiological and mechanical properties of neuronal cells using SICM. Using electrochemical method and SICM, NAC effectively reduces oxidative stress and restores Young's Modulus in SH-SY5Y cells exposed to hydrogen peroxide and Aβ42 oligomers. Our study first examined the influence of SOD1 on intracellular ROS levels in the presence of Aβ oligomers. The investigation into the effects of SOD1 and its nanoparticle form SOD1 on SH-SY5Y cells reveals impacts on mechanical properties and oxidative stress. The combined use of SICM and electrochemical measurements provided a comprehensive understanding of how oxidative stress, including that triggered by the Aβ oligomers affects the mechanical properties of cells.

In‐Situ Self‐Respiratory Solid‐to‐Hydrogel Electrolyte Interface Evoked Well‐Distributed Deposition on Zinc Anode for Highly Reversible Zinc‐Ion Batteries

AbstractThe aqueous zinc‐ion batteries (AZIB) have emerged as a promising technology in the realm of electrochemical energy storage. Despite its potential advantages in terms of safety, cost‐effectiveness, and inherent safety, AZIB faces significant challenges. Issues attributed to unsupported thermodynamics and non‐uniform potential distribution and deposition, present formidable obstacles that necessitate resolution. To tackle these challenges, a novel strategy adapting hybrid organic–inorganic in situ derived solid‐to‐hydrogel electrolyte interface (StHEI) has been developed from coordination reactions and self‐respiratory process, establishing uniform diffusion channels by ion bridges and accelerating ion transport. Self‐respiratory pattern of StHEI realized through in situ inorganic component conversion further prolongs the protecting duration, which effectively mitigates corrosion and passivation but enhance the mechanical properties of the StHEI measured through Young's modulus. This novel StHEI promotes well‐distributed potential lines within the Helmholtz regions. Zn2+ are finally induced to deposit and nucleate in a compact, fine, and uniform manner. Asymmetrical batteries assembled with the modified Zn electrode and bare Zn exhibit exceptional stability over 3000 h (1 mA cm−2–0.5 mAh cm−2). The asymmetrical Cu//Zn cell achieved an outstanding average Coulombic efficiency (CE) of 99.6 % over 1200 cycles.

Superior Conductive, Large Diameter CNT Composite Yarn of Insulative Polymer: Inferences of a Unidirectional Compression‐Stretching Technique

ABSTRACTLarge diameter yet highly conductive Carbon Nanotube (CNT) yarn could have prospective control on high‐tech application field spanning from electronic devices to wearable textiles; although the development of such macroscopic CNTs is extremely challenging. Especially, while fabricating CNT composite yarn with polymer, insulative nature of polymeric materials inherently propagates poor electrical conductivity to CNT yarn. To address this, we have proposed an exciting approach to fabricate large dimension, highly conductive yet flexible CNT‐Thermoplastic Polyurethane (TPU) composite yarn through unidirectional compression‐stretching process. Our technique allowed TPU molecules to be well dispersed into inner and inter‐CNT bundles facilitating well flexibility while the simultaneous functions of pressure and tension allowed more closely packed CNTs network within densified CNT yarn reducing the inherent voids and contact resistance. The consequent yarn possessed high conductivity of 1613 S/cm, attractive mechanical performance (tensile strength 1.3 GPa, Young's modulus 12 GPa, toughness 100.75 MJ/m3), exceptional anti‐abrasive ability (up to 46,350 cycles) endowing its multidirectional adaptability for smart textiles. Moreover, the desirable E‐heating performance together with excellent electrical stability allows successful exploitation of the prepared CNT yarn as stretchable heater. Such amazing integrated characteristics may allow the resultant yarn to replace traditional carbon fiber in various high‐tech arena as well.

In-Situ Self-Respiratory Solid-to-Hydrogel Electrolyte Interface Evoked Well-Distributed Deposition on Zinc Anode for Highly Reversible Zinc-Ion Batteries.

The aqueous zinc-ion batteries (AZIB) have emerged as a promising technology in the realm of electrochemical energy storage. Despite its potential advantages in terms of safety, cost-effectiveness, and inherent safety, AZIB faces significant challenges. Issues attributed to unsupported thermodynamics and non-uniform potential distribution and deposition, present formidable obstacles that necessitate resolution. To tackle these challenges, a novel strategy adapting hybrid organic-inorganic in situ derived solid-to-hydrogel electrolyte interface (StHEI) has been developed from coordination reactions and self-respiratory process, establishing uniform diffusion channels by ion bridges and accelerating ion transport. Self-respiratory pattern of StHEI realized through in situ inorganic component conversion further prolongs the protecting duration, which effectively mitigates corrosion and passivation but enhance the mechanical properties of the StHEI measured through Young's modulus. This novel StHEI promotes well-distributed potential lines within the Helmholtz regions. Zn2+ are finally induced to deposit and nucleate in a compact, fine, and uniform manner. Asymmetrical batteries assembled with the modified Zn electrode and bare Zn exhibit exceptional stability over 3000 h (1 mA cm-2-0.5 mAh cm-2). The asymmetrical Cu//Zn cell achieved an outstanding average Coulombic efficiency (CE) of 99.6 % over 1200 cycles.

Modeling Acoustic Attenuation, Sound Velocity and Wave Propagation in Lithium‐Ion Batteries via a Transfer Matrix

AbstractA simple 1D transfer matrix model of a battery is introduced and parametrized using harvested individual cell components at 0 % and 100 % SoC. This model allows for the calculation of group velocity and attenuation. The results of the model show good agreement with measured values, highlighting increased attenuation and group velocity at the resonances. This emphasizes the importance of selecting a suitable interrogation frequency for ultrasound investigations in lithium‐ion batteries. The model accurately replicates the observed weakening of resonances with increasing SoC. Additionally, it provides the basis to fit US spectroscopy data in the future, enabling immediate determination of component thickness and the Young's modulus of individual components, along with aiding in the identification aging effects of the anode and cathode materials. The model can visualize wave propagation within the battery. At certain frequencies, standing waves form which could be used in high‐intensity ultrasound applications targeted at individual cell components.

Effect of carbon nanotubes and zinc oxide on electrical and mechanical properties of polyvinyl alcohol matrix composite by electrospinning method.

In this study, polymer composite nanofibers and thin membranes were synthesized using Carbon Nanotubes (CNTs) and Zinc Oxide (ZnO) as fillers in a Polyvinyl Alcohol (PVA) matrix, aiming to evaluate their electrical and mechanical properties. The composite nanofibers and thin membranes were prepared by incorporating different weight ratios of CNTs and ZnO into the PVA matrix using electrospinning and solution casting techniques, respectively. Solutions were prepared by mixing specific weight ratios of PVA, ZnO, and CNTs, followed by magnetic stirring and ultrasonication for homogenization. Electrospinning was performed at 20kV with a syringe-to-collector distance of 14.5cm at flow rate of 2.4ml/hr. The composites were characterized using FTIR spectroscopy and Scanning Electron Microscopy (SEM). The PVA/5%ZnO/0.5%CNT composite exhibited the highest dielectric constant of 10.3 at high frequencies, while PVA/5%CNT showed the highest capacitance of 31.1 pF at 2MHz. The maximum AC conductivity of 2.72 × 10- 7S/m was also observed for the PVA/5%ZnO/0.5%CNT composite. Mechanical testing revealed significant improvements in Young's modulus, stress yield, and load yield, with PVA/5%CNT achieving a Young's modulus of 387.12 MPa and a stress yield of 6.92 MPa. The addition of ZnO and CNT fillers resulted in enhanced electrical and mechanical properties, making these composites suitable for applications in microelectronic devices and packaging materials.

Robust liquid crystal semi-interpenetrating polymer network with superior energy-dissipation performance.

Liquid crystal networks (LCN) have attracted surging interest as extraordinary energy-dissipation materials owning to their unique dissipation mechanism based on the re-orientation of mesogens. However, how to integrate high Young's modulus, good dissipation efficiency and wide effective damping temperature range in energy-dissipation LCN remains a challenge. Here, we report a strategy to resolve this challenge by fabricating robust energy-dissipation liquid crystal semi-interpenetrating polymer network (LC-semi-IPN) consisting crystalline LC polymers (c-LCP). LC-semi-IPN demonstrates a superior synergistic performance in both mechanical and energy-dissipation properties, surpassing all currently reported LCNs. The crystallinity of c-LCP endows LC-semi-IPN with a substantial leap in Young's modulus (1800% higher than single network). The chain reptation of c-LCP also promotes an enhanced dissipation efficiency of LC-semi-IPN by 200%. Moreover, its effective damping temperature reaches up to 130 °C, which is the widest reported for LCNs. By leveraging its exceptional synergistic performance, LC-semi-IPN can be further utilized as a functional architected structure with exceptional energy-dissipation density and deformation-resistance.

Biocompatible nanocomposite hydroxyapatite-based granules with increased specific surface area and bioresorbability for bone regenerative medicine applications.

Hydroxyapatite (HA) granules are frequently used in orthopedics and maxillofacial surgeries to fill bone defects and stimulate the regeneration process. Optimal HA granules should have high biocompatibility, high microporosity and/or mesoporosity, and high specific surface area (SSA), which are essential for their bioabsorbability, high bioactivity (ability to form apatite layer on their surfaces) and good osseointegration with the host tissue. Commercially available HA granules that are sintered at high temperatures (≥ 900°C) are biocompatible but show low porosity and SSA (2-5 m2/g), reduced bioactivity, poor solubility and thereby, low bioabsorbability. HA granules of high microporosity and SSA can be produced by applying low sintering temperatures (below 900°C). Nevertheless, although HA sintered at low temperatures shows significantly higher SSA (10-60 m2/g) and improved bioabsorbability, it also exhibits high ion reactivity and cytotoxicity under in vitro conditions. The latter is due to the presence of reaction by-products. Thus, the aim of this study was to fabricate novel biomaterials in the form of granules, composed of hydroxyapatite nanopowder sintered at a high temperature (1100°C) and a biopolymer matrix: chitosan/agarose or chitosan/β-1,3-glucan (curdlan). It was hypothesized that appropriately selected ingredients would ensure high biocompatibility and microstructural properties comparable to HA sintered at low temperatures. Synthesized granules were subjected to the evaluation of their biological, microstructural, physicochemical, and mechanical properties. The obtained results showed that the developed nanocomposite granules were characterized by a lack of cytotoxicity towards both mouse preosteoblasts and normal human fetal osteoblasts, and supported cell adhesion to their surface. Moreover, produced biomaterials had the ability to induce precipitation of apatite crystals after immersion in simulated body fluid, which, combined with high biocompatibility, should ensure good osseointegration after implantation. Additionally, nanocomposite granules possessed microstructural parameters similar to HA sintered at a low temperature (porosity approx. 50%, SSA approx. 30m²/g), Young's modulus (5-8 GPa) comparable to cancellous bone, and high fluid absorption capacity. Moreover, the nanocomposites were prone to biodegradation under the influence of enzymatic solution and in an acidic environment. Additionally, it was noted that the hydroxyapatite nanoparticles remaining after the physicochemical dissolution of the biomaterial were easily phagocytosed by mouse macrophages, mouse preosteoblasts, and normal human fetal osteoblasts (in vitro studies). The obtained materials show great potential as bone tissue implantation biomaterials with improved bioresorbability. The obtained materials show great potential as bone tissue implantation biomaterials with improved bioresorbability.

Mechanically Reinforced Pseudosolid Polyelectrolyte Membranes via Layer‐by‐Layer Assembly for High‐Performing Lithium‐Metal Batteries

AbstractIonogels are emerging as high‐potential pseudosolid electrolytes for lithium‐metal batteries (LMBs), leveraging their intrinsic high ionic conductivity from entrapped ionic liquid (IL) electrolytes. However, their practical application is hindered by poor mechanical strength stemming from the confinement of ILs within a polymer matrix. To address this challenge, the formation of conformal polyion coatings with functional groups is reported to be relevant to LMBs’ application on ionogels, utilizing a layer‐by‐layer (LbL) assembly strategy. This approach significantly enhances the mechanical strength (Young's modulus and tensile strength) and electrochemical performance of ionogels, owing to the tailored interface modifications introduced by functional groups’ specific conformal polyion coatings. The core of this methodology leverages the inherent ionic structure of ionogels to enable facile interface modification through Coulombic interactions between polyanions and polycations. These conformally coated interface functionalized membranes show improved electrochemical performance when integrated with cathode materials such as LiFePO4 (LFP) and LiNi0.8Mn0.1Co0.1O2 (NMC811) in an LMB configuration, underscoring their potential for robust, high‐conductivity, pseudosolid membranes for LMB applications. These innovative pseudosolid membranes offer improved mechanical and electrochemical properties, leading to higher battery efficiency and safety, making them promising candidates for next‐generation LMB technology.

Critical factors influencing electron and phonon thermal conductivity in metallic materials using first-principles calculations

Understanding the thermal transport of various metals is crucial for many energy-transfer applications. However, due to the complex transport mechanisms varying among different metals, current research on metallic thermal transport has been focusing on case studies of specific types of metallic materials. A general understanding of the transport mechanisms across a broad spectrum of metallic materials is still lacking. In this work, we perform first-principles calculations to determine the thermal conductivity of 40 representative metallic materials, within a range of 8-456 W mK-1. Our predicted values of electrical and thermal conductivity are in good agreement with available experimental results. Based on the data of separated electron and phonon thermal conductivity, we employ a statistical approach to examine nine factors derived from previous understandings and identify the critical factors determining these properties. For electrons, although a high electron density of states around the Fermi level implies more conductive electrons, we find it counterintuitively correlates with low electron thermal conductivity. This is attributed to the enlarged electron-phonon scattering channels induced by substantial electrons around the Fermi level. Regarding phonons, we demonstrate that among all the studied factors, Debye temperature plays the most significant role in determining the phonon thermal conductivity, despite the phonon-electron scattering being non-negligible in some transition metals. Correlation analysis suggests that Debye temperature has the highest positive correlation coefficient with phonon thermal conductivity, as it corresponds to a large phonon group velocity. Additionally, Young's modulus is found to be closely correlated with high phonon thermal conductivity and contribution. Our findings of simple factors that closely correlate with the electron and phonon thermal conductivity provide a general understanding of various metallic materials. They may facilitate the discovery of novel materials with extremely high or low thermal conductivity, or be used as descriptors in machine learning to accurately predict the thermal conductivity of metals in the future.

Near-infrared spectroscopy-enabled electromechanical systems for fast mapping of biomechanics and subcutaneous diagnosis.

Fast and accurate assessment of skin mechanics holds great promise in diagnosing various epidermal diseases, yet substantial challenges remain in developing simple and wearable strategies for continuous monitoring. Here, we present a design concept, named active near-infrared spectroscopy patch (ANIRP) for continuously mapping skin mechanics. ANIRP addresses these challenges by integrating near-infrared (NIR) sensing with mechanical actuators, enabling rapid measurement (<1 s) of Young's modulus, high spatial sensing density (~1 cm2), and high spatial sensitivity (<1 mm). Unlike conventional electromechanical sensors, NIR sensors precisely capture vibrational frequencies propagated from the actuators without needing ultraclose contact, enhancing wearing comfort. Demonstrated examples include ANIRPs for comprehensively moduli mapping of artificial tissues with varied mechanical properties emulating tumorous fibrosis. On-body validation of the ANIRP across skin locations confirms its practical utility for clinical monitoring of epidermal mechanics, promising considerable advancements in real-time, noninvasive skin diagnostics and continuous health monitoring.

First-principles calculations of the effect of vacancy defects on the optoelectronic and mechanical properties of the double perovskite Cs2NaInCl6

Abstract Cs2NaInCl6 have become a hot research topic in perovskite optoelectronic materials. However, there is no research on the vacancy properties of Cs2NaInCl6 at present. Herein，using density functional theory-based first-principles calculations, the impact of Cs, Na, In, and Cl single vacancies on the microstructure, electronic, optical, and mechanical properties of the double perovskite Cs2NaInCl6 were investigated. The research shows that the presence of vacancy defects leads to distortion of the Cs2NaInCl6 double perovskite structure and an increase in the unit cell volume. Cs vacancy (VCs) and Na vacancy (VNa) cause an increased band gap for Cs2NaInCl6, by 2.92eV and 3.1eV respectively, without changing the characteristics of the initial direct band gap; VIn and VCl cause the intrinsic semiconductor Cs2NaInCl6 to transform into p-type and n-type semiconductors, respectively, altering the conductivity of Cs2NaInCl6. In terms of optical properties, different vacancy defect systems exhibit different absorption abilities in the visible and ultraviolet light ranges. The defect system overall improves light absorption in the low energy region, and as the incident photon energy increases, the material exhibits the best optical performance at around 15eV. In addition, it is found that VCs, VNa, and VIn caused blue shift in the absorption edge of Cs2NaInCl6, while VCl caused red shift in the absorption edge. In terms of mechanical properties, defects cause varying degrees of reduction in Young's modulus (E), shear modulus (G), and bulk modulus (B) of Cs2NaInCl6, which to some extent alters the mechanical properties of Cs2NaInCl6. These research results provide theoretical guidance for understanding the influence of vacancies on the properties of Cs2NaInCl6 double perovskite and optimizing the performance of perovskite optoelectronic devices, and they also enhance its applications in photovoltaic cells, optoelectronic sensors, and other optoelectronic coupling devices.&amp;#xD;