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Robust and biocompatible hydrogels are recognized as promising biomimetic soft materials to improve human life quality. To ensure their stable, reliable, and safe service, the hydrogels are further required to have non‐contact and wireless stress sensing ability. Herein, a mechanoluminescence (ML) based micellar hydrogel is developed, in which the surface‐modified BaSi2O2N2: Eu2+ (M‐BSON) particles are chemically incorporated into the cross‐linked polyacrylamide/polymethyl acrylate (PAM/PMA) network structure. Because of the interactions between the M‐BSON particles and the PMA micelles, the as‐fabricated composite hydrogel exhibits enhanced mechanical properties with a mechanical strength of 2.73 MPa and a toughness of 3.40 MJ m−3, respectively. The chemical wrapping of the M‐BSON particles by the hydrophobic PMA micelles further protects the ML properties from water quenching, leading to remarkable stress‐induced luminescence under the water environment of hydrogel. Because of its desirable mechanical performance, attractive stress‐light responsiveness, and good biocompatibility, the M‐BSON incorporated hydrogel has the potential to be applied as an intelligent artificial ligament for stress self‐monitoring and failure warning. This work addresses the inhomogeneous dispersion and water quenching issues of the ML particles in hydrogel structure, which significantly promote ML applications in bionic engineering. [ABSTRACT FROM AUTHOR]

Nighttime driving safety is a key focus in transportation research due to accidents caused by drivers' inability to clearly see road obstacles, leading to delayed or incorrect decisions. To address this, the use of mechanoluminescent materials on surfaces like roads and buildings offers a potential solution for better object contour detection in poor visibility. This study investigates the use of SrAl 2 O 4 as a phosphor matrix, exploring its luminescence characteristics and the effects of doping with Eu2+ and Dy3+. The optimal doping ratios were determined to be 2 % Eu and 1 % Dy by trap modulation, producing phosphors with significant mechanical luminescence and a prolonged afterglow. Spectroscopic analysis and image assessment demonstrated a visible afterglow lasting up to 60 min, along with impressive mechanical luminescence performance. By combining the developed SrAl 2 O 4 :Eu2+, Dy3+ phosphor-based coating with polydimethylsiloxane, a real-time surface stress sensing system was devised utilizing digital camera and other optical sensors. This advancement facilitates the visualization of stresses in complex or confined environments, potentially improving nighttime driving safety through enhanced object contour detection. [ABSTRACT FROM AUTHOR]

The phenomenon of flexoelectricity, wherein mechanical deformation induces alterations in the electron configuration of metal oxides, has emerged as a promising avenue for regulating electron transport. Leveraging this mechanism, stress sensing can be optimized through precise modulation of electron transport. In this study, the electron transport in 2D ultra‐smooth In2O3 crystals is modulated via flexoelectricity. By subjecting cubic In2O3 (c‐In2O3) crystals to significant strain gradients using an atomic force microscope (AFM) tip, the crystal symmetry is broken, resulting in the separation of positive and negative charge centers. Upon applying nano‐scale stress up to 100 nN, the output voltage and power values reach their maximum, e.g. 2.2 mV and 0.2 pW, respectively. The flexoelectric coefficient and flexocoupling coefficient of c‐In2O3 are determined as ≈0.49 nC m−1 and 0.4 V, respectively. More importantly, the sensitivity of the nano‐stress sensor upon c‐In2O3 flexoelectric effect reaches 20 nN, which is four to six orders smaller than that fabricated with other low dimensional materials based on the piezoresistive, capacitive, and piezoelectric effect. Such a deformation‐induced polarization modulates the band structure of c‐In2O3, significantly reducing the Schottky barrier height (SBH), thereby regulating its electron transport. This finding highlights the potential of flexoelectricity in enabling high‐performance nano‐stress sensing through precise control of electron transport. [ABSTRACT FROM AUTHOR]

Multimode luminescence is usually stimulated by various external stimuli in response to photon emission and is applied in various anti‐counterfeiting and encryption fields. However, integrating multimode luminescence into a single stable material, and how to quantitatively evaluate the relationship between temperature light and force light remains a challenge. In this work, LiNbO3:Er3+/Pr3+ microcrystals that can respond to X‐ray, UV light, temperature, and stress stimuli are developed. The temperature‐dependent upconversion emission spectra show a maximum relative sensitivity of 0.889% K−1 based on the intensity ratio. Meanwhile, the mechanoluminescence around 618 nm with a linear relationship is observed with the increase of force. These materials illustrate strong static and dynamic luminescence that can be manipulated in space and time dimensions, which provides new ideas in the field of anti‐counterfeiting and information encryption. [ABSTRACT FROM AUTHOR]

Abstract The phenomenon of flexoelectricity, wherein mechanical deformation induces alterations in the electron configuration of metal oxides, has emerged as a promising avenue for regulating electron transport. Leveraging this mechanism, stress sensing can be optimized through precise modulation of electron transport. In this study, the electron transport in 2D ultra‐smooth In2O3 crystals is modulated via flexoelectricity. By subjecting cubic In2O3 (c‐In2O3) crystals to significant strain gradients using an atomic force microscope (AFM) tip, the crystal symmetry is broken, resulting in the separation of positive and negative charge centers. Upon applying nano‐scale stress up to 100 nN, the output voltage and power values reach their maximum, e.g. 2.2 mV and 0.2 pW, respectively. The flexoelectric coefficient and flexocoupling coefficient of c‐In2O3 are determined as ≈0.49 nC m−1 and 0.4 V, respectively. More importantly, the sensitivity of the nano‐stress sensor upon c‐In2O3 flexoelectric effect reaches 20 nN, which is four to six orders smaller than that fabricated with other low dimensional materials based on the piezoresistive, capacitive, and piezoelectric effect. Such a deformation‐induced polarization modulates the band structure of c‐In2O3, significantly reducing the Schottky barrier height (SBH), thereby regulating its electron transport. This finding highlights the potential of flexoelectricity in enabling high‐performance nano‐stress sensing through precise control of electron transport.

Abstract The quest for mechanoluminescence (ML) in zinc sulfide (ZnS) spans more than a century, initially sparked by observations of natural minerals. There has been a resurgence in research into ML materials in recent decades, driven by advances in optoelectronic technologies and a deeper understanding of their luminescent properties under mechanical stress. ZnS, in particular, has garnered attention owing to its remarkable ability to sustain luminescence after more than 100,000 mechanical stimulations, positioning it as a standout candidate for optoelectronic applications. In contrast to conventional photoluminescent and electroluminescent light sources, ZnS composite elastomers have emerged as flexible, stretchable self‐powered light sources with considerable practical implications. This review introduces the development history, ML mechanisms, prototype ML devices, ZnS‐based ML material preparation methods, and their diverse applications spanning environmental mechanical‐to‐optical energy conversion, E‐signatures, anti‐counterfeiting, wearable information sensing devices, advanced battery‐free displays, biomedical imaging, and optical fiber sensors for human–computer interactions, among others. By integrating insights from ML‐optics, mechanics, and flexible optoelectronics, and by summarizing pertinent perspectives on current scientific challenges, application technology hurdles, and potential solutions for emerging scientific frontiers, this review aims to furnish fundamental guidance and conceptual frameworks for the design, advancement, and cutting‐edge application of novel mechanoluminescent materials.

Plants evolve stress‐specific responses that sense changes in their external environmental conditions and develop various mechanisms for acclimatization and survival. Calcium (Ca2+) is an essential stress‐sensing secondary messenger in plants. Ca2+ sensors, including calcium‐dependent protein kinases (CDPKs), calmodulins (CaMs), CaM‐like proteins (CMLs), and calcineurin B‐like proteins (CBLs), are involved in jasmonates (JAs) signalling and biosynthesis. Moreover, JAs are phospholipid‐derived phytohormones that control plant response to abiotic stresses. The JAs signalling pathway affects hormone–receptor gene transcription by binding to the basic helix–loop–helix (bHLH) transcription factor. MYC2 acts as a master regulator of JAs signalling module assimilated through various genes. The Ca2+ sensor CML regulates MYC2 and is involved in a distinct mechanism mediating JAs signalling during abiotic stresses. This review highlights the pivotal role of the Ca2+ sensors in JAs biosynthesis and MYC2‐mediated JAs signalling during abiotic stresses in plants. [ABSTRACT FROM AUTHOR]

Mechanical luminescence (ML) is the conversion of mechanical energy into light energy when a material is subjected to a force. It is challenging to develop ML materials with tunable luminescent properties by single ion doping, which have broad application prospects in the fields of stress sensing and dynamic signature anticounterfeiting. In this study, a Pr3+ doped Sr2Ga2GeO7 tunable ML material is reported. Due to the traps resulting from unequal substitution of Pr3+–Sr2+ in [SrO6] heptahedra, the deep/shallow traps redistribution occurs towards a multicolor ML from red to green. In addition, even after continuous friction sliding force (15 N), the ML intensities can be recovered after ultraviolet pre‐irradiation, indicating that Sr2Ga2GeO7: Pr3+ has excellent ML emission stability. Based on thermoluminescence analysis, potential PersL and ML mechanisms are further elaborated by a lattice engineering (trap regulation) strategy. In all, the development of single‐ion doped multicolor ML materials may have crucial research value and show a variety of potential applications in the fields of anticounterfeiting and information encryption. [ABSTRACT FROM AUTHOR]

Spiropyran (SP) based mechanochromic systems are intensively interesting in the research area of mechanochromic materials. Herein, an SP mechanophore is chemically incorporated into a liquid crystalline elastomer (LCE) network through Michael addition. The rigidity of mesogens and the orientation of polymer main chains, in which the aligned mesogens and SP moieties are covalently attached, facilitate the transduction of applied force to SP mechanophore to trigger mechanochromic reaction. The LCE network provides enough elasticity for mechanochromic activation. The obtained SP‐LCEs demonstrate strong and reversible mechanochromic response upon mechanical compression. The mechanochromic efficiency and sensitivity are substantially enhanced by doping the SP‐LCE matrix with nano zinc oxide such that it is easy to write on the material surface by using a thin iron wire. The authors hope such SP‐LCE materials will be further developed for real‐time stress detection applications. [ABSTRACT FROM AUTHOR]

Mechanoluminescence (ML) materials have found potential applications in information storage, anti‐counterfeiting, and stress sensing. Conventional stress sensing based on absolute ML intensity is prone to significant mistakes owing to the unpredictability of measurement surroundings. However, implementing a ratiometric ML sensing technique may considerably ameliorate this issue. In this study, a single activator‐doped gallate material (LiGa5O8:Pr3+) is proposed to determine the relationship between the ML intensity and the change in local positional symmetry that occurs when the material is subjected to stress. The sensing reliability of the ML intensity ratio under different factors (Force; Content; Thickness and Materials) is systematically analyzed, where the factor that has the greatest effect on the proportional ML is the concentration, with the ML intensity asymmetry ratio decreasing from 1.868 to 1.300 varying concentration at constant stress. The colour‐resolved visualization of stress sensing is further realized, which opens a new path for a ratiometric ML‐based strategy to improve the reliability of stress sensing. [ABSTRACT FROM AUTHOR]

The use of microalgal resources as a potential biomaterial for bioenergy production has captured significant attention but requires process optimization to improve efficiency and enhance economic viability. The integral part of microalgae process optimization is to understand how they undergo epigenetic changes as a means of sensing environmental stresses, especially through oxidative phosphorylation. The ability of microalgae to respond to different stress conditions tends to cause epigenetic changes that influence the bioenergy potential of microalgae. This comprehensive review delves into the importance of understanding these epigenetic changes in microalgae and how they can be manipulated to enhance bioenergy potential. The review shows how epigenetic changes in oxidative phosphorylation cause a change that affects cellular energy homeostasis and signal transduction pathways, leading to altered metabolic profiles and stress adaptation strategies. This metabolic change was linked to the change in the gene expression level of different proteins, including Nicotinamide adenine dinucleotide (NADH) dehydrogenase, cytochrome, and ATPase synthase. The epigenetic change in this protein trigger a change in energy production and photosynthesis efficiency in microalgae, which are vital for the biosynthesis and accumulation of important metabolites useful for biofuel production. The manipulation of these proteins will facilitate the redirection of metabolic flux towards increasing lipid accumulation in microalgae, leading to increased biofuel potential. [Display omitted] • Epigenetic changes in oxidative phosphorylation trigger stress sensing. • Stress sensing enhances microalgal metabolic efficiency and resilience. • Promoting the balance between microalgal biomass and lipid yield. • Upscaling microalgal resource sustainability for bioenergy production [ABSTRACT FROM AUTHOR]

Featured with specific relationship between luminescence intensity and stress, mechanoluminescence (ML) has shown great application potential in stress sensing. However, the uncertainty in acquisition of absolute ML intensity may cause significant error in ML‐intensity‐based stress sensing. A ratiometric ML scheme has been recently proposed as an alternative solution to circumvent such problem. In this paper, a novel strategy based on a lanthanide structural probe is demonstrated to realize the ratiometric ML for stress sensing, where the stress‐induced change in local site symmetry leads to the establishment of the relationship between the ML asymmetry ratio of the structural probe and the applied stress. This strategy offers a brand‐new design solution toward ratiometric ML aiming at improving the reliability of stress sensing. [ABSTRACT FROM AUTHOR]

In the course of their life, plants continuously experience a wide range of unfavourable environmental conditions in the form of biotic and abiotic stress factors. The perception of stress via various organelles and rapid, tailored cellular responses are essential for the establishment of plant stress resilience. Mitochondria as the biosynthetic sites of energy equivalents in the form of ATP-provided in order to enable a multitude of biological processes in the cell-are often directly impacted by external stress factors. At the same time, mitochondrial function may fluctuate to a tolerable extent without the need to activate downstream retrograde signalling cascades for stress adaptation. In this Focus Review, we summarise the current state of knowledge on the perception and processing of stress signals by mitochondria and show which layers of retrograde signalling, that is, those involving transcription factors, metabolites, but also enzymes with moonlighting functions, enable communication with the nucleus. Also, light is shed on signal integration between mitochondria and chloroplasts as part of retrograde signalling. With this Focus Review, we aim to show ways in which organelle-specific communication can be further researched and the collected data used in the long-term to strengthen plant resilience in the context of climate change., (© 2024 The Author(s). The Plant Journal published by Society for Experimental Biology and John Wiley & Sons Ltd.)

Delivery of proteins in plant cells can facilitate the design of desired functions by modulation of biological processes and plant traits but is currently limited by narrow host range, tissue damage, and poor scalability. Physical barriers in plants, including cell walls and membranes, limit protein delivery to desired plant tissues. Herein, a cationic high aspect ratio polymeric nanocarriers (PNCs) platform is developed to enable efficient protein delivery to plants. The cationic nature of PNCs binds proteins through electrostatic. The ability to precisely design PNCs' size and aspect ratio allowed us to find a cutoff of ≈14 nm in the cell wall, below which cationic PNCs can autonomously overcome the barrier and carry their cargo into plant cells. To exploit these findings, a reduction-oxidation sensitive green fluorescent protein (roGFP) is deployed as a stress sensor protein cargo in a model plant Nicotiana benthamiana and common crop plants, including tomato and maize. In vivo imaging of PNC-roGFP enabled optical monitoring of plant response to wounding, biotic, and heat stressors. These results show that PNCs can be precisely designed below the size exclusion limit of cell walls to overcome current limitations in protein delivery to plants and facilitate species-independent plant engineering., (© 2024 The Author(s). Advanced Materials published by Wiley‐VCH GmbH.)

Quorum sensing is the chemical language that enables bacteria to collaborate, share resources, and perform tasks, that individual bacteria cannot accomplish alone. Similarly, we can achieve greater things when we work as a group. Bonnie L. Bassler, recipient of this year's Wolf prize, ends her talks acknowledging her team, stating, "the group accomplishes more than the individual". Inspired by her research subjects, she orchestrates her research via communication and exchange of ideas, often over shared public goods in the form of caffeine and sugary nutrients. Here, I highlight select insights into how vital collaborations between microbes may serve to enlighten and inspire us to work better together. [ABSTRACT FROM AUTHOR]

The optical multifunctional applications based on mechanoluminescence and colour-changing properties. The green part indicates the remote reading of pressure information and thus vehicle damage detection. The blue part indicates the dynamic analysis of signature track and footprint pressure information. The yellow part indicates the use of pressure sensing to transfer information. The red part indicates the use of material optical properties to achieve anti-counterfeiting. [Display omitted] • Heterojunction material has higher sensitivity than pure sulphur oxides when stimulated by same stress. • Heterojunction materials have faster response than pure sulphur oxides. • Heterojunction materials have promising applications in high distance stress sensor and anti-counterfeiting. Mechanoluminescent (ML) materials offer significant potential for remote stress sensing and distribution. However, creating highly sensitive and responsive ML materials remains a challenge. In this study, mechanoluminescent semiconductor materials have been successfully prepared as Mn2+ doped ZnS-SrZnOS heterojunction composites. These materials exhibit high-resolution stress distribution visualization and rapid response, captured via camera recording. Notably, they possess a low stress triggering threshold, reaching the KPa level, and respond within milliseconds. Furthermore, it was found that by adjusting the doping concentration of Mn2+ within the heterojunction, the material utilizes its bimodal emission capability to manipulate the fluorescence shift and achieve optical anti-counterfeiting. The synthesis of smart films by combining the material with polydimethylsiloxane matrix had enabled the achievement of collision detection, information hiding and optical anti-counterfeiting. These results suggest that the prepared smart films have wide range of optical sensing applications. [ABSTRACT FROM AUTHOR]

Quantitative and real-time characterization of mechanically induced bond-scission events taken place in polymeric hydrogels is essential to uncover their fracture mechanics. Herein, a class of mechanochemiluminescent swelling hydrogels have been synthesized through a facile micellar copolymerization method using chemiluminescent bisacrylate-modified bis(adamantyl)-1,2-dioxetane (Ad) as a crosslinker. This design and synthetic strategy ensure intense mechanochemiluminescence from Ad located in a hydrophobic network inside micelles. Moreover, the mechanochemiluminescent colors can be tailored from blue to red by mixing variant acceptors. Taking advantages of the transient nature of dioxetane chemiluminescence, the damage distribution and crack evolution of the hydrogels can be visualized and analyzed with high spatial and temporal resolution. The results demonstrate the strengths of the Ad mechanophore and micellar copolymerization method in the study of damage evolution and fracture mechanism of swelling hydrogels. [ABSTRACT FROM AUTHOR]

Mechanoluminescence (ML) materials with the ability to convert mechanical stimulate into visible light signals have enabled visualized mechanics sensing. To this point, stress sensing based on ML color is preferred over that based on ML intensity in terms of both sensing reliability and visual sensitivity. In this work, a ratiometric dual‐emitting ML strategy to realize the stress‐sensitive ML color variation, where the Lanthanide/transition‐metal combination is adopted to build the dual‐activator ML system is proposed. The difference in electronic configuration between Lanthanide and transition‐metal ions leads to the significant discrepancy in the response of corresponding luminescence kinetics to the instantaneous change of local crystal field environment induced by stress, which plays a key role in the strategy. This strategy establishes a new general path for the design of novel ratiometric ML materials. [ABSTRACT FROM AUTHOR]

The recovery and maintenance of plant homeostasis under stressful environments are complex processes involving organelle crosstalk for a coordinated cellular response. Here, we revealed through nuclear and chloroplast subcellular proteomics, biochemical cell profiles and targeted transcriptomics how chloroplasts and nuclei developed their responses under increased temperatures in a long‐lived species (Pinus radiata). Parallel to photosynthetic impairment and reactive oxygen species production in the chloroplast, a DNA damage response was triggered in the nucleus followed by an altered chromatin conformation. In addition, in the nuclei, we found several proteins, such as HEMERA or WHIRLY, which change their locations from the chloroplasts to the nuclei carrying the stress message. Additionally, our data showed a deep rearrangement of RNA metabolism in both organelles, revealing microRNAs and AGO1 as potential regulators of the acclimation mechanisms. Altogether, our study highlights the synchronisation among the different stages required for thermotolerance acquisition in P. radiata, pointing out the role of chromatin conformation and posttranscriptional gene regulation in overcoming heat stress and assuring plant survival for the following years. Summary Statement: Here, we show how nuclei and chloroplasts exchange signals and coordinate their proteomes to overcome heat stress in Pinus radiata. The acclimation process is reflected in a profound physiological rearrangement and a reprogramming of RNA metabolism including an increase in microRNA contents. [ABSTRACT FROM AUTHOR]

Live fish waterless transport strategy for the purpose of consumption or ornament is a novel technology, which can implement the larger volume transportation with high survival results as well as less wastewater pollution. The aim of this study was to establish an accurate survival prediction system based on the least physiological stress variations in different temperature ranges, which statistically analyzes the trend of key stress factors under the well life-supported temperatures to improve the final survival result. Furthermore, the accuracy of survival prediction can be adaptively and dynamically improved in consideration of the historical survival series in different seasons. In order to verify the practicability and performance of the system, Paralichthys olivaceus was selected as experimental subjects to carry out dynamic survival prediction experiments for over 30 hours waterless transportation, and the accuracy of the survival prediction system has verified over 97.2% in 0.5-2.5C°, which show that mean absolute error (MAE) and mean squared error (MSE) by less than 0.2 and 0.07 to produce the most accurate estimation in the comparison. The development of this survival prediction system can significantly optimize the current waterless delivery management by reducing the potential mortality and providing the managerial references for industrialization of the live fish waterless logistics.

Mechanoluminescence (ML) is one of the most important routes to realize remote sensing of stress distribution, but has never been used in temperature sensing. Traditionally, stress sensing and temperature sensing are separately realized through different methods in multifunctional sensors, which definitely makes the structure more complicated. In this work, the remote stress–temperature dual‐modal sensing is proposed by using the double‐lanthanide‐activated ML material SrZnSO:Tb,Eu, where the stress is read by the integral intensity of ML and the temperature is displayed by the green to red emission ratio (ITb/IEu) of ML in one material. The dual sensing mode in SrZnSO:Tb,Eu enables building of a new imaging system, providing a facile, reliable, and more sensitive way to remotely visualize the distribution of stress and temperature. It opens up a novel approach to develop advanced artificial skins with simplified structures in human–machine interfaces, structural health monitoring, and biomedical engineering applications. [ABSTRACT FROM AUTHOR]

In this letter, magnetic and magnetostriction studies were performed on spinel ferrite Co1–xNixFe2O4 (CNF series) with $0.0 < x < 0.5$. All the samples were synthesized by the conventional ceramic method and confirmed to be forming pure spinel phase. The unit cell parameter showed gradual decrease with increasing Ni content. A linear decrease in saturation magnetization $(M_s)$ and coercivity $(H_c)$ was observed with increasing Ni substitution, which could be attributed to reduced magneto-crystalline anisotropy. The room temperature magnetostriction studies revealed a slow decrease in maximum magnetostriction, and interestingly, for 20% reduction of cobalt concentration, i.e., for $x$ = 0.2, a magnetostrictive strain of −164 ppm and substantially high stress sensitivity of −56 × 10−6 A−1 m were observed, making Co0.8Ni0.2Fe2O4 suitable for application as a magnetostrictive stress-sensing material. [ABSTRACT FROM AUTHOR]

The article focuses on Optical fiber sensor based on Sagnac interferomter. Topics include that the sensor is designed by combination of photonic crystal fiber (PCF) and fiber Bragg grating (FBG) and the device is used for measuring various physical parameters including temperature and stress by the changes of physical characteristics such as interference, diffraction, and polarization caused by light propagation in the optical fiber.

In this work, multi-scale cementitious composites containing short carbon fibers (CFs) and carbon nanofibers (CNFs)/multi-walled carbon nanotubes (MWCNTs) were studied for their tensile stress sensing properties. CF-based composites were prepared by mixing 0.25, 0.5 and 0.75 wt.% CFs (of cement) with water using magnetic stirring and Pluronic F-127 surfactant and adding the mixture to the cement paste. In multi-scale composites, CNFs/MWCNTs (0.1 and 0.15 wt.% of cement) were dispersed in water using Pluronic F-127 and ultrasonication and CFs were then added before mixing with the cement paste. All composites showed a reversible change in the electrical resistivity with tensile loading; the electrical resistivity increased and decreased with the increase and decrease in the tensile load/stress, respectively. Although CF-based composites showed the highest stress sensitivity among all specimens at 0.25% CF content, the fractional change in resistivity (FCR) did not show a linear correlation with the tensile load/stress. On the contrary, multi-scale composites containing CNFs (0.15% CNFs with 0.75% CFs) and MWCNTs (0.1% MWCNTs with 0.5% CFs) showed good stress sensitivity, along with a linear correlation between FCR and tensile load/stress. Stress sensitivities of 6.36 and 11.82%/MPa were obtained for the best CNF and MWCNT-based multi-scale composite sensors, respectively.

Development of simple, readily-applicable sensors for mechanical deformation of polymers is highly sought albeit a formidable task. Here we demonstrate that composite films comprising carbon dots (C-dots) embedded in an elastic polymer host allow fluorescence-based quantitative determination of tensile modulation. Film stretching induced both blue shift in the C-dots' fluorescence peak positions and dramatic increase in fluorescence intensities. The phenomenon was demonstrated for different C-dots exhibiting distinct fluorescence emissions (e.g. colors). Importantly, the C-dot/polymer fluorescence intensity could be quantitatively correlated to tensile parameters, specifically film stress and strain. The direct correlation is ascribed to stretch-induced modulation of the average distances among the polymer-embedded C-dots and concomitant modification of aggregation-induced self-quenching. We further exploited the tensile-dependent fluorescence modulation of the C-dot/polymer system to construct a tunable-intensity white light emitter, opening the way to innovative mechanically-tuned optical device. Image 1 [ABSTRACT FROM AUTHOR]

External stress affects the stiffness distribution of a MEMS gyroscope and, along with temperature, is affiliated with long-term drift. Although the detrimental effects of stress on MEMS gyroscopes are well-documented, modeling of such effects is still lacking in the literature. For the first time, we present an analytical model that mathematically describes the stress effects in a ring gyroscope. Our model revolves around the key observation that stress-induced anchor displacements result in variations of electrostatic gaps and nonhomogeneous boundary conditions at the interface between the gyroscope's suspension system and the anchored internal structure. Our gyroscope is equipped with 16 capacitive stress sensors distributed with 45° symmetry on the inside and outside of the main ring. We use these stress sensors' measurements to interpolate the strain field across the substrate and deduce the anchor displacements. To capture the stress effects, we show that two fundamental assumptions in the existing literature should be amended: (1) Linearity: the linear engineering strain should be upgraded to the nonlinear Green–Lagrange strain to reveal the stress-induced stiffness through geometric nonlinearity; (2) Inextensibility: for a ring, this stress stiffness is determined by the extensional stress arising from centerline extensibility. We analyze variations of frequencies and mode shapes' orientation along with the resultant quadrature and in-phase errors. Moreover, we present a fairly general formulation incorporating fabrication-induced imperfections and elastic anisotropy. We validate our model experimentally using extensive bending tests performed on our 59 kHz, 3.2 mm diameter gyroscope. [Display omitted] • For the first time, we present a model for stress effects in a ring gyroscope. • Ring extensibility and geometric nonlinearity are the key aspects of our modeling. • We performed tests on a 59 kHz, 3.2 mm diameter gyro with 16 on-chip stress sensors. • Predicted frequencies and quadrature/in-phase errors match the experimental results. [ABSTRACT FROM AUTHOR]

In this study, we methodologically compare and review the accuracy and performance of C0-continuous flat and curved inverse-shell elements (i.e., iMIN3, iQS4, and iCS8) for inverse finite element method (iFEM) in terms of shape, strain, and stress monitoring, and damage detection on various plane and curved geometries subjected to different loading and constraint conditions. For this purpose, four different benchmark problems are proposed, namely, a tapered plate, a quarter of a cylindrical shell, a stiffened curved plate, and a curved plate with a degraded material region in stiffness, representing a damage. The complexity of these test cases is increased systematically to reveal the advantages and shortcomings of the elements under different sensor density deployments. The reference displacement solutions and strain-sensor data used in the benchmark problems are established numerically, utilizing direct finite element analysis. After performing shape-, strain-, and stress-sensing analyses, the reference solutions are compared to the reconstructed solutions of iMIN3, iQS4, and iCS8 models. For plane geometries with sparse sensor configurations, these three elements provide rather close reconstructed-displacement fields with slightly more accurate stress sensing using iCS8 than when using iMIN3/iQS4. It is demonstrated on the curved geometry that the cross-diagonal meshing of a quadrilateral element pattern (e.g., leading to four iMIN3 elements) improves the accuracy of the displacement reconstruction as compared to a single-diagonal meshing strategy (e.g., two iMIN3 elements in a quad-shape element) utilizing iMIN3 element. Nevertheless, regardless of any geometry, sensor density, and meshing strategy, iQS4 has better shape and stress-sensing than iMIN3. As the complexity of the problem is elevated, the predictive capabilities of iCS8 element become obviously superior to that of flat inverse-shell elements (e.g., iMIN3 and iQS4) in terms of both shape sensing and damage detection. Comprehensively speaking, we envisage that the set of scrupulously selected test cases proposed herein can be reliable benchmarks for testing/validating/comparing for the features of newly developed inverse elements.

Stress is a naturally occurring psychological response and identifiable by several body signs. We propose a novel way to discriminate acute stress and relaxation, using movement and posture characteristics of the foot. Based on data collected from 23 participants performing tasks that induced stress and relaxation, we developed several machine learning models to construct the validity of our method. We tested our models in another study with 11 additional participants. The results demonstrated replicability with an overall accuracy of 87%. To also demonstrate external validity, we conducted a field study with 10 participants, performing their usual everyday office tasks over a working day. The results showed substantial robustness. We describe ten significant features in detail to enable an easy replication of our models.

Plants evolve stress-specific responses that sense changes in their external environmental conditions and develop various mechanisms for acclimatization and survival. Calcium (Ca 2+ ) is an essential stress-sensing secondary messenger in plants. Ca 2+ sensors, including calcium-dependent protein kinases (CDPKs), calmodulins (CaMs), CaM-like proteins (CMLs), and calcineurin B-like proteins (CBLs), are involved in jasmonates (JAs) signalling and biosynthesis. Moreover, JAs are phospholipid-derived phytohormones that control plant response to abiotic stresses. The JAs signalling pathway affects hormone-receptor gene transcription by binding to the basic helix-loop-helix (bHLH) transcription factor. MYC2 acts as a master regulator of JAs signalling module assimilated through various genes. The Ca 2+ sensor CML regulates MYC2 and is involved in a distinct mechanism mediating JAs signalling during abiotic stresses. This review highlights the pivotal role of the Ca 2+ sensors in JAs biosynthesis and MYC2-mediated JAs signalling during abiotic stresses in plants., (© 2023 John Wiley & Sons Ltd. Published by John Wiley & Sons Ltd.)

Abstract This work reports capacitance-based stress self-sensing in cement paste without requiring any particular admixture (whatever type). The in-plane capacitance is measured between two coplanar electrodes (aluminum foil) adhered to the cement slab by double-sided adhesive tape. The capacitance decreases with increasing normal stress, whether the stress is purely compressive or flexural compressive, due to piezoelectricity. The capacitance decrease is completely reversible in the low-stress regime (normal stress up to 19 kPa), and partially reversible above this stress. The minimum normal stress change detected is 0.2 kPa, which, in case of flexure, corresponds to a flexural stress change of 8.5 kPa. The change in capacitance per unit normal stress change is up to 0.061 and 0.101 pF/kPa for purely compressive and flexural compressive loading, respectively; the value is higher in the low-stress regime, which gives superior linearity and reversibility. Low-stress sensing is relevant to pedestrian monitoring and room occupancy monitoring. [ABSTRACT FROM AUTHOR]

An experimental piezospectroscopic system was built to study the stress sensing properties of SrSiAlN3:Eu2+ phosphor-silicone composite. A novel technique named barycenter technique was used to analyze the stress-dependent spectra, and accordingly stress sensing functions were obtained. Shape and area of the sample surface on which compressive stress was applied didn't affect the sensitivity. Stress tests on the experimental setup showed good repeatability for sensing applications. The barycenter technique gave linear stress sensing functions in this research, and finally the determined sensitivity was 0.20 nm/MPa averagely. This sensitivity is one thousand times larger than the piezospectroscopic coefficient of ruby. [ABSTRACT FROM AUTHOR]

An endoplasmic reticulum (ER)-located transmembrane protein, Ire1, triggers cytoprotective events upon ER stress. Chimeric yeast Ire1 carrying the luminal domain of the mammalian major Ire1 paralogue IRE1α is upregulated in ER-stressed yeast cells, but is poorly associated with the ER-located chaperone BiP even under non-stressed conditions. This observation contradicts the theory that BiP is the master regulator of IRE1α. [ABSTRACT FROM AUTHOR]

The purpose of the study was to evaluate the antimycobacterial activity and the possible action mode of cinnamon bark essential oil and its main constituent--cinnamaldehyde--against the Mycobacterium tuberculosis ATCC 25177 strain. Cinnamaldehyde was proved to be the main bioactive compound responsible for mycobacterial growth inhibition and bactericidal effects. The antimycobacterial activity of cinnamaldehyde was found to be comparable with that of ethambutol, one of the first-line anti-TB antibiotics. The selectivity index determined using cell culture studies in vitro showed a high biological potential of cinnamaldehyde. In M. tuberculosis cells exposed to cinnamaldehyde the cell membrane stress sensing and envelope preserving system are activated. Overexpression of clgR gene indicates a threat to the stability of the cell membrane and suggests a possible mechanism of action. No synergism was detected with the basic set of antibiotics used in tuberculosis treatment: ethambutol, isoniazid, streptomycin, rifampicin, and ciprofloxacin. [ABSTRACT FROM AUTHOR]

Abstract: A mechanically robust, ultraelastic foam with controlled multiscale architectures and tunable mechanical/conductive performance is fabricated via 3D printing. Hierarchical porosity, including both macro‐ and microscaled pores, are produced by the combination of direct ink writing (DIW), acid etching, and phase inversion. The thixotropic inks in DIW are formulated by a simple one‐pot process to disperse duo nanoparticles (nanoclay and silica nanoparticles) in a polyurethane suspension. The resulting lightweight foam exhibits tailorable mechanical strength, unprecedented elasticity (standing over 1000 compression cycles), and remarkable robustness (rapidly and fully recover after a load more than 20 000 times of its own weight). Surface coating of carbon nanotubes yields a conductive elastic foam that can be used as piezoresistivity sensor with high sensitivity. For the first time, this strategy achieves 3D printing of elastic foam with controlled multilevel 3D structures and mechanical/conductive properties. Moreover, the facile ink preparation method can be utilized to fabricate foams of various materials with desirable performance via 3D printing. [ABSTRACT FROM AUTHOR]

This paper describes the development of an entirely remote, portable, and low-cost sensor system that includes a mechanoluminescence (ML) sample, optical sensor, and wireless data transmitter module. A composite consisting of SrAl 2 O 4 :Eu,Dy and epoxy resin was used as the ML test sample. The performance of the ML system, including the wireless function and accuracy, were tested under laboratory conditions. The wireless module was confirmed to provide reliable synchronous data transmission. The ML sensor system was then utilized to measure the stress of an object in a practical application. The ML data were easily acquired even with an applied load of 300 N and eventually stabilized with continuous load cycles. The ML system was able to detect a crack in a gas pipeline during operation with high sensitivity. The combined results indicate that the designed ML sensor system can potentially be applied as a smart and wireless structural health monitoring system. [ABSTRACT FROM AUTHOR]

Mechanoresponsive polymers have garnered significant attention in recent years, due to their great potential application in stress/strain sensing and damage warning. Several reviews of mechanochemistry have been published recently. In this review, we mainly focus on the most established mechanophore, spiropyran (SP), from an engineering perspective. We present a workflow for SP mechanochemistry, applications in various polymeric systems and impacting factors, as well as characterization techniques. Current limitations and future research directions are briefly highlighted in the end. This review aims to offer deep insight into polymer mechanochemistry and provide approaches to study other mechanophores using the example of SP mechanochemistry in polymers. [ABSTRACT FROM AUTHOR]

A combined stress-vibration sensor was developed to measure stress and vibration simultaneously based on fiber Bragg grating (FBG) technology. The sensor is composed of two FBGs and a stainless steel plate with a special design. The two FBGs sense vibration and stress and the sensor can realize temperature compensation by itself. The stainless steel plate can significantly increase sensitivity of vibration measurement. Theoretical analysis and Finite Element Method (FEM) were used to analyze the sensor’s working mechanism. As demonstrated with analysis, the obtained sensor has working range of 0–6000 Hz for vibration sensing and 0–100 MPa for stress sensing, respectively. The corresponding sensitivity for vibration is 0.46 pm/g and the resulted stress sensitivity is 5.94 pm/MPa, while the nonlinearity error for vibration and stress measurement is 0.77% and 1.02%, respectively. Compared to general FBGs, the vibration sensitivity of this sensor is 26.2 times higher. Therefore, the developed sensor can be used to concurrently detect vibration and stress. As this sensor has height of 1 mm and weight of 1.15 g, it is beneficial for minimization and integration. [ABSTRACT FROM AUTHOR]

In the past few years, there has been a significant increase in detection of drug resistant strains of Mycobacterium tuberculosis. Search for new antimycobacterial drugs brought natural sources with their chemical diversity in focus. Especially essential oils, produced by plants also for toxic effect, are reservoir of potentially antitubercular compounds. In the present work, we exposed M. tuberculosis H37Ra ATCC 25177 strain to some terpenes commonly occurring in essential oils. Gene expression profiling was used to explore possible influence of these compounds on stress sensing and envelope preserving function. Expression of two genes dprE1 involved in cell wall synthesis and clgR responsible for regulation of cell membrane preservation was investigated. We report that two out of five tested compounds: β-elemene and R-limonene alter expression of dprE1 and clgR genes. These findings indicate various mechanisms of action of essential oils compounds on M. tuberculosis . Especially the clgR expression seemed to be the perfect marker of stress sensing and envelope preserving systems status. [ABSTRACT FROM AUTHOR]

• Tunable stress visualization is obtained by ratio mechanoluminescence of Tb3+. • Ratio mechanoluminescence of Tb3+ is concentration dependant. • Traps dominating mechanoluminescence in Lu 3 Al 2 Ga 3 O 12 :Tb3+ are confirmed. When a material is stimulated by external stress, the mechanical energy may be converted into light energy calling mechanoluminescent (ML). The unique excitation method makes it promising for a wide range of applications in the field of stress sensing. However, traditional stress sensing methods based on absolute ML intensity have limitations in unpredictable and complex measurement environment. To address this topic, a ratiometric ML intensity-based stress sensing method has been proposed, which significantly improves the reliability and stability of sensing results. In this paper, a single Tb3+ ion-doped garnet ML compound is designed. The variation of defect concentration in the material was induced by changing the dopant concentration and the local crystal field intensity. Ratiometric ML stress sensing was achieved through external mechanical stimuli, which causes a change in local positional symmetry. The linear relationship between the luminescence intensity asymmetry ratio and stress was investigated, and the excellent stability and reliability of the ML material were demonstrated under multiple stress cycles. The single-activator ratiometric ML intensity strategy presented in this study provides a new approach for improving stress sensing accuracy, which represents an essential step for the application of ML materials in stress sensing. [ABSTRACT FROM AUTHOR]

• LiSrPO 4 :Eu2+/Eu3+ phosphors have been explored to realize the ratiometric ML for stress sensing. • The sensitivity of the stress-dependent ratiometric ML is found to be influenced by Eu dopant concentration. • The dopant concentration dependent sensitivity is associated with the evolution of local structural rigidity of the host. Ratiometric mechanoluminescence (ML) has been recently proposed for stress-sensing, which is regarded to be superior to the traditional ML-intensity based sensing route in terms of accuracy and cycle stability. The dual-activator strategy to realize the ratiometric ML takes advantage of instantaneous change of local crystal field environment induced by stress, where the structural characteristics of host are supposed to play major role. Herein, LiSrPO 4 :Eu2+/Eu3+ phosphors have been explored to realize the ratiometric ML, with the focus on the influence of Eu dopant concentration on the sensitivity of the stress-dependent ratiometric ML. The dependence between the dopant concentration and sensitivity can be interpreted in terms of host phase structure evolution with dopant concentration. [Display omitted] [ABSTRACT FROM AUTHOR]