External Stress Conditions Research Articles

STK33 as the functional substrate of miR-454-3p for suppression and apoptosis in neuroblastoma

miR-454-3p has been reported to be a tumor suppressive micro-RNA (miRNA) in multiple cancer types. We identified the kinase STK33 mRNA, which is a high-risk factor for survival in neuroblastoma (NB) patients, as being a substrate of miR-454-3p in NB. Even though STK33 is an attractive target for several cancers, development of inhibitors of STK33 has been challenging. For the various cell lines tested, we demonstrated reduced growth and viability with the miR-454-3p mimic. From among the candidate NB-associated miRNAs, miR-454-3p mimic and its antagonist had the most profound effect on STK33 mRNA and protein level changes. Under various conditions of growth and external stress for the cells, the RNA levels for miR-454-3p and STK33 also negatively correlated. Luciferase reporter assays demonstrated STK33 as a substrate for miR-454-3p, and recombinant versions of STK33 resistant to miR-454-3p significantly blunted the suppressive effect of the miR-454-3p and established STK33 as the major functional substrate of miR-454-3p. Overexpression of miR-454-3p or knockdown of STK33 mRNA promoted autophagy, and at the same time, increased the apoptotic markers in the tested NB cells, indicating a mechanism for the suppressive effect of the agents. Given the difficult-to-drug targets such as STK33 and the recent successes in RNA delivery methods for cancer treatment, it is thought that targeting cancer cells with a suppressive miRNA such as miR-454-3p for STK33-dependent cancer types may be an alternative means of NB therapy.

Dual-color Correlative Light and Electron Microscopy for the Visualization of Interactions between Mitochondria and Lysosomes.

Cellular organelles, such as mitochondria and lysosomes, display dynamic structures. Despite the higher resolution of transmission electron microscopy for structural analysis, light microscopy is essential for the visualization of dynamic organelles by target-specific labeling. The following protocol describes a method that combines dual-color correlative light and electron microscopy (CLEM) to observe the interactions between mitochondria and lysosomes. In this study, mitochondria were labeled with mEosEM (Mito-mEosEM) and lysosomes with TMEM192-V5-APEX2. The results obtained from CLEM images enable us to observe the changes in the interactions between mitochondria and lysosomes under external stress conditions. Treatment with bafilomycin (BFA), which inhibits lysosomal function, resulted in an increase in contact between mitochondria and lysosomes, leading to the formation of fragmented mitochondria trapped inside lysosomes. Conversely, treatment with U18666A, which inhibits cholesterol export from lysosomes, caused lysosomes to be surrounded by mitochondria, indicating a distinct form of interaction. This study presents an effective method for observing the interactions between mitochondria and lysosomes in fixed cells. Furthermore, CLEM imaging with dual-color probes offers a powerful tool for future investigations of organelle dynamics and their implications for cell function and pathology.

Tentative identification of phytochelatins, their derivatives, and Cd-phytochelatin complexes in Ocimum basilicum L. roots by Paper Spray Mass Spectrometry.

An unprecedented and direct PS-MS (paper spray ionization mass spectrometry) method was proposed for the detection of native peptides, that is, glutathiones (GSHs), homoglutathiones (hGSHs), and phytochelatins (PCs), in basil (Ocimum basilicum L.) roots before and after cadmium exposure. The roots were submitted to cold maceration followed by sonication with formic acid as the extractor solvent for sample preparation. PS-MS was used to analyze such extracts in the positive mode, and the results allowed for the detection of several GSHs, hGSHs, and PCs. Some of these PCs were not distinguished in the control samples, that is, basil roots not exposed to cadmium. Other PCs were noticed in both types of roots, uncontaminated and cadmium-contaminated, but the intensities were higher in the former samples. Moreover, long-time exposure to cadmium stimulated the formation of some of these PCs and their cadmium complexes. The results, therefore, provided some crucial insights into the defense mechanism of plants against an external stress condition due to exposure to a toxic heavy metal. The present study represents a promising alternative to investigate other crucial physiological processes in plants submitted to assorted stress conditions.

Advances in Understanding the Evolution Mechanism of Micropore Defects in Metal Materials under External Loads

Micropores are one of the critical factors affecting materials’ performance and service life. As the need for a deeper understanding of micropore evolution and damage mechanisms grows, assessing the mechanical properties of materials containing micropores and predicting the lifespan of related metal structural components becomes increasingly complex. This paper focuses on the evolution process, regularities, and research methods of micropores in metal materials. Based on recent research and practical applications, the key stages of micropore evolution are discussed, encompassing nucleation, growth, coalescence, collapse, interaction, and the influence of other microstructures. Firstly, the advantages and limitations of commonly used characterization methods such as scanning electron microscopy, transmission electron microscopy, and X-ray computed tomography are introduced in the study of micropore evolution. Subsequently, critical theoretical models for micropore evolution, such as the Gurson model and its extensions, are summarized. By using a multiscale approach combining the crystal plasticity finite element method, dislocation dynamics, and molecular dynamics, the factors influencing the micropore evolution, such as external stress conditions, internal microstructures, and micropore characteristics, are specifically elaborated, and the basic physical mechanisms of micropore evolution are analyzed. Finally, a comprehensive review and summary of current research trends and key findings are provided, and a forward-looking perspective on future research directions is presented.

Maternal nitric oxide homeostasis impacts female gametophyte development under optimal and stress conditions.

In adverse environments, the number of fertilizable female gametophytes (FGs) in plants is reduced, leading to increased survival of the remaining offspring. How the maternal plant perceives internal growth cues and external stress conditions to alter FG development remains largely unknown. We report that homeostasis of the stress signaling molecule nitric oxide (NO) plays a key role in controlling FG development under both optimal and stress conditions. NO homeostasis is precisely regulated by S-nitrosoglutathione reductase (GSNOR). Prior to fertilization, GSNOR protein is exclusively accumulated in sporophytic tissues and indirectly controls FG development in Arabidopsis (Arabidopsis thaliana). In GSNOR null mutants, NO species accumulated in the degenerating sporophytic nucellus, and auxin efflux into the developing FG was restricted, which inhibited FG development, resulting in reduced fertility. Importantly, restoring GSNOR expression in maternal, but not gametophytic tissues, or increasing auxin efflux substrate significantly increased the proportion of normal FGs and fertility. Furthermore, GSNOR overexpression or added auxin efflux substrate increased fertility under drought and salt stress. These data indicate that NO homeostasis is critical to normal auxin transport and maternal control of FG development, which in turn determine seed yield. Understanding this aspect of fertility control could contribute to mediating yield loss under adverse conditions.

Irradiation-induced hardening of Zircaloy-2 at room temperature under external stress conditions

Irradiation-induced hardening of Zircaloy-2 at room temperature under external stress conditions

An emerging role of heterotrimeric G-proteins in nodulation and nitrogen sensing.

A comprehensive understanding of nitrogen signaling cascades involving heterotrimeric G-proteins and their putative receptors can assist in the production of nitrogen-efficient plants. Plants are immobile in nature, so they must endure abiotic stresses including nutrient stress. Plant development and agricultural productivity are frequently constrained by the restricted availability of nitrogen in the soil. Non-legume plants acquire nitrogen from the soil through root membrane-bound transporters. In depleted soil nitrogen conditions, legumes are naturally conditioned to fix atmospheric nitrogen with the aid of nodulation elicited by nitrogen-fixing bacteria. Moreover, apart from the symbiotic nitrogen fixation process, nitrogen uptake from the soil can also be a significant secondary source to satisfy the nitrogen requirements of legumes. Heterotrimeric G-proteins function as molecular switches to help plant cells relay diverse stimuli emanating from external stress conditions. They are comprised of Gα, Gβ and Gγ subunits, which cooperate with several downstream effectors to regulate multiple plant signaling events. In the present review, we concentrate on signaling mechanisms that regulate plant nitrogen nutrition. Our review highlights the potential of heterotrimeric G-proteins, together with their putative receptors, to assist the legume root nodule symbiosis (RNS) cascade, particularly during calcium spiking and nodulation. Additionally, the functions of heterotrimeric G-proteins in nitrogen acquisition by plant roots as well as in improving nitrogen use efficiency (NUE) have also been discussed. Future research oriented towards heterotrimeric G-proteins through genome editing tools can be a game changer in the enhancement of the nitrogen fixation process. This will foster the precise manipulation and production of plants to ensure global food security in an era of climate change by enhancing crop productivity and minimizing reliance on external inputs.

On the stress dependency of sand production coefficient in hydro-dynamical sanding criteria

Solids production is a complex physical process which is controlled by several factors including mechanical failure from in-situ stresses and hydrodynamic erosion from fluid flow. Hydrodynamic models for the prediction of sand production involve sanding criteria based on filtration theories. Such models contain a constitutive model parameter, the coefficient λ, with dimensions of inverse length which is calibrated by sand erosion tests, but its nature and its dependencies have not been clarified to date. The aim of this work is an attempt to refine the hydrodynamic models by investigating the dependence of the sand production coefficient λ on the external stress conditions and on the plastic zone Λ that is developed on hollow cylinders tests and propose an expression describing its importance in the sand production prediction modelling. The aim of the work is obtained through simulations with finite elements by utilizing the well-established Arbitrary Lagrangian-Eulerian (ALE) analysis considering the poro-mechanical coupling of the fluid-solid system for simulating hollow cylinder tests. Best fitting experimental data estimated values for the sand production coefficient for various values of external stress are obtained through back analysis. The dependence of λ on the external stress turns out to be fairly smooth and a three-parameter model is proposed to describe that dependence: a scale parameter, an exponent, and a stress parameter defining the magnitude of stress at which erosion onset is predicted. It turns out that the stress parameter is associated with the minimum stress required for plastic yielding to occur, which was also estimated theoretically. This finding is in agreement with the physical assumption underlying the simulations that erosion onsets and progresses after the material reaches a critical plastic strain as a consequence of material plastic yielding. A power law model describing the dependence of λ on the plastic zone depth is also proposed and discussed.

Accelerated Stress Testing of Perovskite Photovoltaic Modules: Differentiating Degradation Modes with Electroluminescence Imaging

Herein, electroluminescence (EL) and thermal imaging are used to examine p–i–n metal halide perovskite (MHP) photovoltaic (PV) mini‐modules (MA0.6FA0.4PbI3, 20 cells, 78 cm2) before and after indoor‐accelerated stress testing or outdoor deployment. Distinct spatial patterns in the EL images emerge, which depend on the external stress conditions experienced by the mini‐module. Imaging results highlight a distribution of dark speckle features that dominate after UV stress, attributed to widespread interfacial contact degradation. Lateral intensity gradients across cells dominate after thermal cycling (TC) stress, attributed to current crowding near scribe defects. While current–voltage analysis alone does not give full insight on the degradation process, this study shows that distinct degradation modes can be further defined by multimodal electro‐optical imaging (i.e., EL combined with photoluminescence and dark lock‐in thermography). Neither UV exposure nor TC‐accelerated stress testing alone replicates the same degradation signatures observed after outdoor deployment, suggesting that multiple degradation modes occur under concurrent stressors outdoors. Spatial characterization of degradation modes in MHP PV mini‐modules before and after accelerated stress testing lays the groundwork for developing targeted accelerated stress testing procedures through comparison with outdoor aging.

Effect of stress loading on hot salt corrosion behavior of TiAlTaN/CrAlN multilayer coatings

The hot salt corrosion behavior of TiAlTaN coating and TiAlTaN/CrAlN multilayer coatings with different modulation periods under external stress condition were studied. The complex stress distribution on the specimen surface was obtained by designing a double-sided notched tensile specimen, and then the hot salt stress corrosion test was carried out at 500 °C for 120 h. The TiAlTaN monolayer coating had obvious stress cracking under stress loading, while the TiAlTaN/CrAlN multilayer coatings showed good resistance to hot salt stress corrosion crack even under high stress. The performance improvement was attributed to the role of multilayer interfaces in inhibiting microcrack growth and diffusion of the corrosion medium into the coating. In particular, the TiAlTaN/CrAlN-10 multilayer coating with smaller modulation period not only had better hot salt corrosion resistance, but also showed excellent resistance to crack propagation under stress loading, forming effective protection for the titanium alloy substrate.

Study of Potential‐Induced Degradation in Glass‐Encapsulated Perovskite Solar Cells under Different Stress Conditions

Potential‐induced degradation (PID) is an important reliability issue of photovoltaic modules. For future field applications of perovskite photovoltaic modules, it is important to study the PID behavior under real‐world operating conditions, which has not yet been thoroughly researched. This work presents PID investigation of glass‐encapsulated perovskite solar cells (PSCs) at different stress conditions for an extended duration of 55 h. At room condition (25 °C, 20% relative humidity [RH]) the efficiency is reduced by 59% when −1000 V is applied to the short‐circuited PSCs, whereas under elevated stress condition (60 °C, 60% RH) the device efficiency suffers severe degradation of >90%. The PID effects are analyzed with several characterization methods, revealing that Na+ion migration from the front glass pane toward the perovskite layer causes the degradation. Application of a reverse voltage bias right after PID results in very poor recovery under elevated condition compared to the recovery of devices under room condition. It is proposed that PID and its recovery rate depend on the external stress conditions and the reverse bias strategy is not sufficient for the recovery. Possible mitigation strategies which can open a new avenue for further research on PID in PSCs are also presented.

The Role of MEF2 Transcription Factor Family in Neuronal Survival and Degeneration.

The family of myocyte enhancer factor 2 (MEF2) transcription factors comprises four highly conserved members that play an important role in the nervous system. They appear in precisely defined time frames in the developing brain to turn on and turn off genes affecting growth, pruning and survival of neurons. MEF2s are known to dictate neuronal development, synaptic plasticity and restrict the number of synapses in the hippocampus, thus affecting learning and memory formation. In primary neurons, negative regulation of MEF2 activity by external stimuli or stress conditions is known to induce apoptosis, albeit the pro or antiapoptotic action of MEF2 depends on the neuronal maturation stage. By contrast, enhancement of MEF2 transcriptional activity protects neurons from apoptotic death both in vitro and in preclinical models of neurodegenerative diseases. A growing body of evidence places this transcription factor in the center of many neuropathologies associated with age-dependent neuronal dysfunctions or gradual but irreversible neuron loss. In this work, we discuss how the altered function of MEF2s during development and in adulthood affecting neuronal survival may be linked to neuropsychiatric disorders.

The influence mechanism of effective stress, adsorption effect and Klinkenberg effect on coal seam permeability

Permeability is an important parameter in the process of coalbed methane exploitation. To improve the production efficiency of coalbed methane and explore the control mechanism of the gas flow law in coal, the permeability of helium and nitrogen in the same coal sample was tested under different effective stress (the difference between external stress and pore pressure of coal mass) and pressure by using the seepage device. Based on the gas flow theory, the interaction mechanism of effective stress, adsorption effect and Klinkenberg effect in controlling the permeability has been analyzed. Increasing the gas pressure will enhance the adsorption and deformation ability of coal, causing the reduction of pore size, while it will also cause the reduction of effective stress and stress deformation. There is a certain competition between them under the same external stress condition, which will lead to the change of pore and then affect the permeability of coal seam. The Klinkenberg effect will lead to more complex change factors of permeability, especially in laboratory experiments. Both adsorption deformation and stress deformation will affect the pore structure of coal body, which will also lead to changes in the influence degree of Klinkenberg effect on apparent permeability. Under the influence of adsorption effect, the Klinkenberg effect may be a variable. The experimental results in this work elaborate the microscopic control mechanism of gas permeability change in coal. It can not only provide important guidance for gas injection technology, but also enrich the theory of coal seam gas flow.

Nanovesicle and extracellular polymeric substance synthesis from the remediation of heavy metal ions from soil

Heavy metal toxicity affects aquatic plants and animals, disturbing biodiversity and ecological balance causing bioaccumulation of heavy metals. Industrialization and urbanization are inevitable in modern-day life, and control and detoxification methods need to be accorded to meet the hazardous environment. Microorganisms and plants have been widely used in the bioremediation of heavy metals. Sporosarcina pasteurii, a gram-positive bacterium that is widely known for its calcite precipitation property in bio-cementing applications has been explored in the study for its metal tolerance ability for the first time. S. pasteurii SRMNP1 (KF214757) can tolerate silver stress to form nanoparticles and can remediate multiple heavy metals to promote the growth of various plants. This astounding property of the isolate warranted extensive examinations to comprehend the physiological changes during an external heavy metal stress condition. The present study aimed to understand various physiological responses occurring in S. pasteuriiSRMNP1 during the metal tolerance phenomenon using electron microscopy. The isolate was subjected to heavy metal stress, and a transmission electron microscope examination was used to analyze the physiological changes in bacteria to evade the metal stress. S. pasteurii SRMNP1 was tolerant against a wide range of heavy metal ions and can withstand a broad pH range (5–9). Transmission Electron Microscopy (TEM) examination of S. pasteurii SRMNP1 followed by 5 mM nickel sulfate treatment revealed the presence of nanovesicles encapsulating nanosized particles in intra and extracellular spaces. This suggests that the bacteria evade the metal stress by converting the metal ions into nanosized particles and encapsulating them within nanovesicles to efflux them through the vesicle budding mechanism. Moreover, the TEM images revealed an excessive secretion of extracellular polymeric substances by the strain to discharge the metal particles outside the bacterial system. S. pasteurii can be foreseen as an effective bioremediation agent with the potential to produce nanosized particles, nanovesicles, and extracellular polymeric substances. This study provides physiological evidence that, besides calcium precipitation applications, S. pasteurii can further be explored for its multidimensional roles in the fields of drug delivery and environmental engineering.

Gas permeability evolution of unsaturated GMZ bentonite under thermo-mechanical effects

The variation in the gas permeability of unsaturated GMZ bentonite caused by coupled thermo-mechanical effects is essential in evaluating the long-term safety of deep geologic repositories. Gas permeability tests were conducted on samples containing different water contents under different confining pressures and real-time heating processes to investigate their effects. Samples with different water contents were obtained by equilibrating the samples at different relative humidity (RH) conditions under unrestricted conditions. The results show that the gas permeability of the unsaturated GMZ bentonite varies from 10−15 to 10−20 m2 under coupled thermo-mechanical effects. It is significantly influenced by temperature and confining pressure, and the extent of change is related to the initial RH conditions. Gas permeability generally decreases with temperature. When the temperature reaches 80 °C, a sudden increase in gas permeability occurs in samples with high RHs (94.7% and 97.3%) as gas pressure pushes out moisture. The rapid increase in permeability remains dependent on the confining pressure, with it exceeding the value in the initial 20 °C under low confining pressures and falling below that under high confining pressures. The exploration of real-time water loss also reflects the phenomenon of the gas migration process carrying water vapor out as the temperature increases, which is responsible for the sudden change in gas permeability. The external stress condition is the key to ensuring its sound sealing performance. Microscopic pore structure observation results further reflect that pore closure due to thermal effects is the primary reason for the temperature-dependent decrease in gas permeability during the loading process. The cracking of samples with high RHs under thermal effects and the decrease in water-content capacity are potential endogenous causes of the sudden gas permeability increase. The study results provide reliable data to support the construction of the Beishan geologic repository in China.

Halide Remixing under Device Operation Imparts Stability on Mixed‐Cation Mixed‐Halide Perovskite Solar Cells

Mixed-halide mixed-cation hybrid perovskites are among the most promising perovskite compositions for application in a variety of optoelectronic devices due to their high performance, low cost, and bandgap-tuning capabilities. Instability pathways such as those driven by ionic migration, however, continue to hinder their further progress. Here, an operando variable-pitch synchrotron grazing-incidence wide-angle X-ray scattering technique is used to track the surface and bulk structural changes in mixed-halide mixed-cation perovskite solar cells under continuous load and illumination. By monitoring the evolution of the material structure, it is demonstrated that halide remixing along the electric field and illumination direction during operation hinders phase segregation and limits device instability. Correlating the evolution with directionality- and depth-dependent analyses, it is proposed that this halide remixing is induced by an electrostrictive effect acting along the substrate out-of-plane direction. However, this stabilizing effect is overwhelmed by competing halide demixing processes in devices exposed to humid air or with poorer starting performance. The findings shed new light on understanding halide de- and re-mixing competitions and their impact on device longevity. These operando techniques allow real-time tracking of the structural evolution in full optoelectronic devices and unveil otherwise inaccessible insights into rapid structural evolution under external stressconditions.

Exogenous seed treatment with proline and its consequences to Norway spruce (Picea abies (L.) H. Karst) seedling establishment

Accumulation of proline is a defense mechanism against external stress conditions, preventing damage to the structure and function of cells and improving plant development processes, such as germination. The purpose of this study was to investigate proline treatment as a means of improving the germination and development of Norway spruce seedlings. The effect of exogenous proline has been studied in three stages of initial plant development. The collected seeds were soaked in water or 8 mM proline solution and placed on the germinators. The germination capacity and the mean germination time were determined. Seedlings with radicles >10 mm were transferred to the sand-peat substrate at a constant temperature of 20 °C. Seedlings at 3 subsequent developmental stages (S1 – germinated seeds with radicles > 3 mm; S2 – seedlings with radicles >10 mm; S3 – established seedlings grown for 90 days) were examined for the oxygen consumption rate, total antioxidant capacity, hydrogen peroxide level, malondialdehyde level and intracellular proline content. Proline treatment was conducive to lowering the levels of hydrogen peroxide and malondialdehyde at stage S1. At the subsequent stages of development, the levels of hydrogen peroxide and malondialdehyde increased, and at the S3 stage, there was also a marked increase in total antioxidant capacity. At stage S3, the seedlings of the proline treatment were characterized by a lower total mass, and the response to exogenous proline was stronger in the root tissues than in the leaves. The oxygen consumption rate was higher for the proline treatment at all stages of development. Seedlings at the analyzed stages of establishment differed in response to proline treatment. Exogenous proline had some beneficial effects during the first phase of germination by reducing the level of hydrogen peroxide and improving the condition of lipid membranes. In the subsequent stages of seedling development, in response to the same concentration of proline solution, undesirable effects, such as an increase in hydrogen peroxide levels and damage to cytoplasmic membranes, were observed. Optimal concentrations of exogenous proline should be determined prior to commercial use of proline treatment to improve plant stress tolerance.

Formula omitted][formula omitted] morphology prediction of Zr hydride precipitates using atomistically informed Eshelby’s ellipsoidal inclusion

We energetically predicted the morphology of Zr hydride precipitates in a hexagonal close-packed (HCP) Zr matrix. Considering Zr hydride precipitates as ellipsoids, we used Eshelby’s ellipsoidal inclusions to calculate the elastic energy increment due to the presence of Zr hydride precipitates in the Zr matrix, in which the elastic anisotropy and inhomogeneity of the elastic constants between Zr and Zr hydride were considered. We compared the difference in the elastic energy increment between the ellipsoidal inclusions with different shapes: plates (mimicked by penny-shape ellipsoids), needles (mimicked by longitudinal ellipsoids) and sphere, and orientations to detect the stable structure with the minimum elastic energy increment. Eigenstrains of each Zr hydride and elastic constants of Zr hydrides and HCP Zr for Eshelby’s ellipsoidal inclusion analysis were determined using atomistic simulations based on a density functional theory calculation, achieving a parameter free abinitio morphology prediction. The morphology predictions were implemented for two cases: with and without shear components of eigenstrain (w/ and w/o shear). The 〈12̄10〉 longitudinal needle for the γ hydride (w/o shear) and plate (or disk) on the plane, which is 20° to 30° tilted about 〈12̄10〉-axis from basal plane (0001), for δ and ε hydrides (w/ shear) were successfully predicted as stable shapes and orientations of the precipitates under zero external stress conditions, qualitatively consistent with experimental observations. The external circumferential tensile stress on the basal plane reduces the elastic energy of [0001] parallel Zr hydride plates, which is also qualitatively consistent with the reoriented δ hydride precipitates observed in the experiment. On the other hand, predicted external stress for the reorientation of Zr hydride is quite high, around 10 GPa. This is inconsistent with experimental observation and further investigation is necessary. Generally, our predictions based on elasticity theory appear qualitatively consistent with experimental observations, suggesting an elastic origin of the morphology of Zr hydride precipitates in the HCP Zr matrix.

Optimisation of the load-bearing structure of the control surface frame. Additive technology

Optimisation of the load-bearing structure of the control surface frame for application of the additive technology is proposed, with unchanged performance and strength characteristics of the body section, the weight of which is reduced by 20 %. The problems related to modelling of external stress and kinematic boundary conditions are considered for a structural analysis of units included in composite bodies. Optimisation is based on a stepby-step approximation (iteration) method and a finite element analysis software package, including comparison with the experiment.

Beginners guide to ribosome profiling

Beginners guide to ribosome profiling