Artificial Stress Research Articles

Numerical simulation on multi-well fracturing considering multiple thin layers in vertical direction

Multiwell fracturing is a key technology for developing shale gas and shale oil reservoirs. In this study, a multiple planar 3D (PL3D) fracture simulator that can capture multiple thin layers was developed to examine the propagation of multiple fractures during multicluster fracturing in multiple horizontal wells. The simulator considers multiple thin layers in the vertical direction. The results of the model are validated against the analytical solution of a single radial fracture and the implicit level set algorithm (ILSA). Using the simulator, a series of numerical simulations based on the field case are performed to investigate the fracture propagation mechanism of multiwell fracturing. The completion sequence, well placement pattern, well spacing, and cluster spacing are investigated to optimize the treatment parameters. The effective fracture area is used to quantitatively describe the stimulation effect. The adaptability of the completion sequence and well placement pattern is also analysed from the perspective of “frac hits”. The results show that the completion sequence has a critical influence on the stimulation effect and fracture geometry. From the perspective of avoiding “frac-hit” fractures, fracturing the low-stress layer can form an “artificial stress barrier”, which slightly protects the well from interference from other fractures. The staggered well pattern is better than the stacked well pattern. Compared with the stacked pattern, the staggered pattern can reduce the overlap area of fractures by 80 %, which greatly reduces the probability of “frac-hits”. With increasing well spacing from 200 m to 500 m, the fracture area increases by 25 %, and the degree of uneven stimulation between the two pay zones also increases by 6 %. Considering that a small well spacing is prone to “frac hits”, a large well spacing leads to an unstimulated area between two wells, and a 350 m well spacing is optimal. The effective fracture area decreases slightly with increasing perforation cluster spacing, but the fracture geometry becomes much more regular. The results can be helpful for the field design of multiwell fracturing.

Exposure assessment and risks associated with wearing silver nanoparticle-coated textiles

Background Silver (Ag) nanoparticles (NPs) are used increasingly in consumer and healthcare fabrics due to their antimicrobial properties. Abrasive leaching experiments have shown that AgNPs can be released during textile wear and cause a dermal exposure. Derived-no-effect-limit value for AgNPs ranges from 0.01 to 0.0375 mg/kg-body-weight, and thus, low exposures levels can cause relevant risk. Methods In this study AgNP release from textiles by artificial sweat immersion and mechanical stress was investigated. A mass balance model was used to calculate dermal Ag exposure and potential intake via percutaneous absorption and inadvertent (peri-)oral intake during wear of face mask, suit with a full body exposure and gloves. Mass flow analysis was performed for up to 8-h wear time and by using Ag penetration rate constants reported for fresh-, cryopreserved- and glycerolized skin grafts. Results Dermal intake risk characterization ratio (RCR) during 8-h wear time for glycerolized skin was up to 0.02 for face mask and 0.9 for full body wear in a worst-case condition. Wearing gloves for 1-h followed by single unintentional fingertip mouthing (contact area 11.5 cm2) resulted in an RCR of 0.0002. RCR varied depending on the type of textile-product, exposure wear duration and skin type. Conclusions This study provides a comprehensive assessment of AgNPs release from textiles and their potential impact on human dermal exposure and was essential for understanding the safety implications for different exposure scenarios and mitigating potential risks.

Evaluating artificial intelligence-driven stress echocardiography analysis system (EASE study): A mixed method study

IntroductionThe use and value of artificial intelligence (AI)-driven tools and techniques are under investigation in detecting coronary artery disease (CAD). EchoGo Pro is a patented AI-driven stress echocardiography analysis system...

Transcriptome analysis of the common moss Bryum pseudotriquetrum grown under Antarctic field condition.

Mosses are distributed all over the world including Antarctica. Although Antarctic mosses show active growth in a short summer season under harsh environments such as low temperature, drought and high levels of UV radiation, survival mechanisms for such multiple environmental stresses of Antarctic mosses have not yet been clarified. In the present study, transcriptome analyses were performed using one of the common mosses Bryum pseudotriquetrum grown under an Antarctic field and artificial cultivation conditions. Totally 88205 contigs were generated by de novo assembly, among which 1377 and 435 genes were significantly up and downregulated, respectively, under Antarctic field conditions compared with artificial cultivation conditions at 15°C. Among the upregulated genes, a number of lipid metabolism-related and oil body formation-related genes were identified. Expression levels of these genes were increased by artificial environmental stress treatments such as low temperature, salt and osmic stress treatments. Consistent with these results, B. pseudotriquetrum grown under Antarctic field conditions contained large amounts of fatty acids, especially α-linolenic acid, linolenic acid and arachidonic acid. In addition, proportion of unsaturated fatty acids, which enhance membrane fluidity, to the total fatty acids was also higher in B. pseudotriquetrum grown under Antarctic field conditions. Since lipid accumulation and unsaturation of fatty acids are generally important factors for the acquisition of various environmental stress tolerance in plants, these intracellular physiological and metabolic changes may be responsible for the survival of B. pseudotriquetrum under Antarctic harsh environments.

Artificial intelligence-derived stress ejection fraction in stress cardiac magnetic resonance with dipyridamole: bridging past insights with future innovations.

Artificial intelligence-derived stress ejection fraction in stress cardiac magnetic resonance with dipyridamole: bridging past insights with future innovations.

Stability assessment of surrounding rock in downward mining route supported by slab-wall backfill structure

Characteristic of ground pressure in surrounding rock is generally considered as the theoretical basis of parameter optimization for stope structure and technology. To explore the feasibility of efficient method for the second-step downward route backfill stopes in Shanjin gold mine, various numerical simulation methods were used to investigate the effect of slab-wall backfill structure on stability of surrounding rock in downward route mining system. The maximum principal stress, artificial false roof stress, and displacement were analyzed to evaluate the level of ground pressure in different mining areas. These results indicate the optimized structural parameters for backfill stopes, which may also provide a low-cost way to achieve a high safety for downward route mining system.

Exposure assessment and risks associated with wearing silver nanoparticle-coated textiles

Background Silver (Ag) nanoparticles (NPs) are used increasingly in consumer and healthcare fabrics due to their antimicrobial properties. Abrasive leaching experiments have shown that AgNPs can be released during textile wear and cause a dermal exposure. Derived-no-effect-limit value for AgNPs ranges from 0.01 to 0.0375 mg/kg-body-weight, and thus, low exposures levels can cause relevant risk. Methods In this study AgNP release from textiles by artificial sweat immersion and mechanical stress was investigated. A mass balance model was used to calculate dermal Ag exposure and potential intake via percutaneous absorption and inadvertent (peri-)oral intake during wear of face mask, suit with a full body exposure and gloves. Mass flow analysis was performed for up to 8-h wear time and by using Ag penetration rate constants reported for fresh-, cryopreserved- and glycerolized skin grafts. Results Dermal intake risk characterization ratio (RCR) during 8-h wear time for glycerolized skin was up to 0.02 for face mask and 0.9 for full body wear in a worst-case condition. Wearing gloves for 1-h followed by single unintentional fingertip mouthing (contact area 11.5 cm2) resulted in an RCR of 0.0002. RCR varied depending on the type of textile-product, exposure wear duration and skin type. Conclusions This study provides a comprehensive assessment of AgNPs release from textiles and their potential impact on human dermal exposure and was essential for understanding the safety implications for different exposure scenarios and mitigating potential risks.

Impact of climatic anomalies and reservoir induced seismicity on earthquake generation using Federated Learning

In this article, impact of climatic anomalies and artificial hydraulic loading on earthquake generation has been studied using federated learning (FL) technique and a model for the prediction of earthquake has been proposed. Federated Learning being one of the most recent techniques of machine learning (ML) guarantees that the proposed model possesses the intrinsic ability to handle all concerns related to data involving data privacy, data availability, data security, and network latency glitches involved in earthquake prediction by restricting data transmission to the network during different stages of model training. The main objective of this study is to determine the impact of artificial stresses and climatic anomalies on increase and decrease in regional seismicity. Experimental verification of proposed model has been carried out within 100 km radial area from 34.708o N, 72.5478o E in Western Himalayan region. Regional data of atmospheric temperature, air pressure, rainfall, water level of reservoir and seismicity has been collected on hourly bases from 1985 till 2022. In this research, four client stations at different points within the selected area have been established to train local models by calculating time lag correlation between multiple data parameters. These local models are transmitted to central server where global model is trained for generating earthquake alert with ten days lead time alarming a specific client that reported high correlation among all selected parameters about expected earthquake.

품질이 관리된 스트레스 측정용 데이터셋 구축을 위한 제언

The construction of a stress measurement dataset plays a crucial role in various modern applications. In particular, for the efficient training of artificial intelligence models for stress measurement, it is essential to compare various biases and construct a quality-controlled dataset. In this paper, we propose the construction of a stress measurement dataset with quality management through the comparison of various biases. To achieve this, we introduce stress definitions and measurement tools, the process of building an artificial intelligence stress dataset, strategies to overcome biases for quality improvement, and considerations for stress data collection. Specifically, to manage dataset quality, we discuss various biases such as selection bias, measurement bias, causal bias, confirmation bias, and artificial intelligence bias that may arise during stress data collection. Through this paper, we aim to systematically understand considerations for stress data collection and various biases that may occur during the construction of a stress dataset, contributing to the construction of a dataset with guaranteed quality by overcoming these biases.

Mitigation of Cutting-Induced Artificial Stresses in Contour Method Analysis of Irregular Components

Mitigation of Cutting-Induced Artificial Stresses in Contour Method Analysis of Irregular Components

Generation of Mature Toxoplasma gondii Bradyzoites in Human Immortalized Myogenic KD3 Cells.

Toxoplasma gondii is a zoonotic protozoan parasite and one of the most successful foodborne pathogens. Upon infection and dissemination, the parasites convert into the persisting, chronic form called bradyzoites, which reside within cysts in muscle and brain tissue. Despite their importance, bradyzoites remain difficult to investigate directly, owing to limited in vitro models. In addition, the need for new drugs targeting the chronic stage, which is underlined by the lack of eradicating treatment options, remains difficult to address since in vitro access to drug-tolerant bradyzoites remains limited. We recently published the use of a human myotube-based bradyzoite cell culture system and demonstrated its applicability to investigate the biology of T. gondii bradyzoites. Encysted parasites can be functionally matured during long-term cultivation in these immortalized cells and possess many in vivo-like features, including pepsin resistance, oral infectivity, and antifolate resistance. In addition, the system is scalable, enabling experimental approaches that rely on large numbers, such as metabolomics. In short, we detail the cultivation of terminally differentiated human myotubes and their subsequent infection with tachyzoites, which then mature to encysted bradyzoites within four weeks at ambient CO2 levels. We also discuss critical aspects of the procedure and suggest improvements. Key features • This protocol describes a scalable human myotube-based in vitro system capable of generating encysted bradyzoites featuring in vivo hallmarks. • Bradyzoite differentiation is facilitated through CO2 depletion but without additional artificial stress factors like alkaline pH. • Functional maturation occurs over four weeks.

İki Amerikan Asma Anacının Kuraklık Stresine Toleransının PEG Uygulaması ile Belirlenmesi

Objective: This study was conducted to establish the in vivo protocol for the use of polyethylene glycol (PEG-6000) in 5BB (V. berlandieri x V. riparia) and 1103P (V. berlandieri x V. rupestris) American grapevine rootstocks, as well as to determine the plants' resilience to artificially induced drought stress.
 Materials and Methods: The experimental design of this study was planned as a randomized complete plot design with 3 replications, each consisting of 10 plants. Polyethylene glycol (PEG-6000) was administered to the plants in each irrigation at doses of 0%, 2%, 4%, 8%, and 16%, based on the percentage of irrigation water. The application lasted for a total of 3 weeks. The study investigated the responses of plants to drought in terms of shoot development parameters (shoot fresh weight, shoot dry weight, shoot length, node and leaf number, leaf area, shoot tolerance ratio), root development parameters (root fresh weight, root number, rooting rate, root tolerance ratio, root length), and physiological development parameters (plant vitality, damage degree, leaf turgor weight, chlorophyll content, ion flux, and cell membrane damage rate).
 Results: When examining the findings of the study, it was observed that polyethylene glycol material retained water, reducing the plant's water uptake and consequently creating artificial drought stress. The impact of drought induced by polyethylene glycol revealed that the 1103P rootstock exhibited higher resilience in shoot development parameters compared to the 5BB rootstock. On the contrary, the 5BB rootstock outperformed the 1103P rootstock in root development parameters. Concerning physiological development parameters, the severity of drought led to a significant decrease in plant vitality, chlorophyll content, and leaf turgor weight, while ion flux, cell membrane damage rate, and damage degree increased significantly to critical levels.
 Conclusion: As a result of the research, the 1103P rootstock was found to be more successful in terms of shoot and physiological development under drought conditions, while the 5BB rootstock was found to be more successful in terms of root development parameters. Compared to other cultivation environments (in vitro, hydroponics), it was determined that polyethylene glycol (PEG) had a less pronounced effect at lower doses due to the difficulty of binding PEG in the soil. However, when compared to control plants, statistically significant differences were observed in the examined traits. Regarding the parameters investigated in this study, the 16% PEG concentration used was identified as the most effective dose in triggering drought stress.

Understanding the Impact of Artificial Stress on the Morphological Characteristics of cv. ‘Merlot’ Berry and Cluster

Understanding the Impact of Artificial Stress on the Morphological Characteristics of cv. ‘Merlot’ Berry and Cluster

Numerical simulations of Phan-Thien-Tanner viscoelastic fluid flows based on the SPH method

Numerical simulations of viscoelastic fluid flows are always a hot issue in the field of computational fluid dynamics and the study of their complex rheological properties has important academic and engineering application value. In the present work, we develop a smoothed particle hydrodynamics (SPH) method for simulating transient viscoelastic fluid flows governed by the Phan-Thien-Tanner (PTT) constitutive equation. To improve the computational accuracy of the SPH method, the mixed symmetric correction algorithm of kernel gradient is implemented. To remove the particle clustering and unphysical fracture in fluid stretching which is named as the tensile instability, the artificial stress model is added into the momentum equation. We firstly apply the proposed SPH method to solve the plane Poiseuille flow of a PTT viscoelastic fluid, in which the effectiveness and advantage of the method are verified by comparing the SPH solution with those obtained by the finite volume method (FVM) and analyzing the l2 norm error of different SPH solutions to the FVM solution. Then, the method is employed to simulate the impact behavior of a PTT viscoelastic droplet with a rigid plate. In particular, we not only investigate the spreading behavior of PTT viscoelastic droplet after impacting the rigid plate, but also for the first time capture and analyze the bouncing behavior of droplet by decreasing the Reynolds number. The influences of the Reynolds number, the Weissenberg number, the solvent viscosity ratio, and the PTT elongational parameter on the droplet dynamics behavior are further deeply studied. Numerical results demonstrate that the SPH method proposed in this paper is a powerful computation tool for simulating PTT viscoelastic fluid flows and is capable of effectively describing their complex rheological properties and free surface variation characteristics.

A detailed study on genetic diversity, antioxidant machinery, and expression profile of drought-responsive genes in rice genotypes exposed to artificial osmotic stress

Seasonal variations in rainfall patterns, particularly during sowing, early growing season, and flowering, drastically affect rice production in northeastern India. However, sensitivity to drought stress is genotype-specific. Since 80% of the land in this region is used for rice production, it is crucial to understand how they have adapted to water stress. This study evaluated 112 rice genotypes grown in NE India for seed germination percentage and seedling development under PEG-mediated drought stress. Among the rice genotype, Sahbhagi dhan, RCPL-1-82, Bhalum-3 and RCPL-1-128 showed drought-tolerant traits, while Ketaki Joha, Chakhao, Chandan, RCPL-1-185 and IR-64 were the most drought-sensitive rice genotypes. Drought-tolerant rice also showed significantly higher seed germination potential, proline content, antioxidant activity and expression of drought-responsive genes than drought-sensitive rice genotypes. A similar expression pattern of genes was also observed in the rice genotype treated with a 50% water deficit in pot culture. In addition, drought stress reduced the pollen fertility and yield per plant in sensitive rice genotypes. Molecular markers associated with drought stress were also used to characterize genetic diversity among the rice genotypes studied.

Physiological ER stress caused by amylase production induces regulated Ire1-dependent mRNA decay in Aspergillus oryzae

Regulated Ire1-dependent decay (RIDD) is a feedback mechanism in which the endoribonuclease Ire1 cleaves endoplasmic reticulum (ER)-localized mRNAs encoding secretory and membrane proteins in eukaryotic cells under ER stress. RIDD is artificially induced by chemicals that generate ER stress; however, its importance under physiological conditions remains unclear. Here, we demonstrate the occurrence of RIDD in filamentous fungus using Aspergillus oryzae as a model, which secretes copious amounts of amylases. α-Amylase mRNA was rapidly degraded by IreA, an Ire1 ortholog, depending on its ER-associated translation when mycelia were treated with dithiothreitol, an ER-stress inducer. The mRNA encoding maltose permease MalP, a prerequisite for the induction of amylolytic genes, was also identified as an RIDD target. Importantly, RIDD of malP mRNA is triggered by inducing amylase production without any artificial ER stress inducer. Our data provide the evidence that RIDD occurs in eukaryotic microorganisms under physiological ER stress.

The regulation of simulated artificial oro-gastrointestinal transit stress on the adhesion of Lactobacillus plantarum S7

BackgroundOro-gastrointestinal stress in the digestive tract is the main stress to which orally administered probiotics are exposed. The regulation of oro-gastrointestinal transit (OGT) stress on the adhesion and survival of probiotics under continuous exposure to simulated salivary-gastric juice-intestinal juice was researched in this study.ResultsLactobacillus plantarum S7 had a higher survival rate after exposure to simulated OGT1 (containing 0.15% bile salt) stress and OGT2 (containing 0.30% bile salt) stress. The adhesion ability of L. plantarum S7 was significantly increased by OGT1 stress (P < 0.05) but was not changed significantly by OGT2 stress (P > 0.05), and this trend was also observed in terms of the thickness of the surface material of L. plantarum S7 cells. The expression of surface proteins of L. plantarum S7, such as the 30 S ribosomal proteins, mucus-binding protein and S-layer protein, was significantly downregulated by OGT stress (P < 0.05); meanwhile, the expression of moonlight proteins, such as glyceraldehyde-3-phosphate dehydrogenase (GAPDH), phosphoglycorate kinase (PGK), beta-phosphoglucomutase (PGM1), GroEL and glucose-6-phosphate isomerase (PGI), was significantly upregulated (P < 0.05). However, the upregulation of GAPDH, PGK, PGM1 and PGI mediated by OGT1 stress was greater than those mediated by OGT2 stress. The quorum sensing pathway of L. plantarum S7 was changed significantly by OGT stress compared with no OGT stress cells (P < 0.05), and the expression of Luxs in the pathway was significantly upregulated by OGT1 stress (P < 0.05). The ABC transportation pathway was significantly altered by OGT1 stress (P < 0.05), of which the expression of the peptide ABC transporter substrate-binding protein and energy-coupling factor transporter ATP-binding protein EcfA was significantly upregulated by OGT stress (P < 0.05). The glycolide metabolism pathway was significantly altered by OGT1 stress compared with that in response to OGT2 stress (P < 0.05).ConclusionL. plantarum S7 had a strong ability to resist OGT stress, which was regulated by the proteins and pathways related to OGT stress. The adhesion ability of L. plantarum S7 was enhanced after continuous exposure to OGT1 stress, making it a potential probiotic with a promising future for application.

Variability of the traits of technological quality of fiber flax varieties flax straw

The results of the study of the adaptation potential of perennial fruit crops depending on climatic changes are presented. The physiological state of some pear varieties during summer periods in 2021, 2022 in the fruit plantations of the Krasnodar Territory were evaluated. Two Russian varieties (Flamenko, Luberskaya) and two European varieties (Conference, Williams) were studied. An experiment on artificially drying freshly harvested pear leaves at constant room temperature was conducted to amplify the negative effects of summer stressors. The relative water content of leaves and electrolyte leakage were determined before and after the stress according to generally accepted methods. It was found that relative humidity is an important factor for normal leaf development, and the change in its values in the summer months correlated with the variability of values of the stress parameter of pear leaves - electrolyte leakage. It was found that the widespread European variety Conference was the most susceptible to the effects of artificial stress. After a short drying period, this variety was characterized by a sharp increase in the electrolyte leakage to ~36 % on the background of a significant decrease in the relative water content in the leaves (71–73 %), due to the development of oxidative processes, leading to a violation of the integrity of cell membranes. Russian varieties Flamenko and Luberskaya, as well as the European variety Williams, on the contrary, by the studied physiological parameters had no strong differences (the change of physiological parameters was from 1.1 to 1.3 times), which allowed them to be identified as more resistant varieties to this type of stress exposure.

Influence of weather conditions on the variability of physiological leaf parameters in pear cultivars

The results of the study of the adaptation potential of perennial fruit crops depending on climatic changes are presented. The physiological state of some pear varieties during summer periods in 2021, 2022 in the fruit plantations of the Krasnodar Territory were evaluated. Two Russian varieties (Flamenko, Luberskaya) and two European varieties (Conference, Williams) were studied. An experiment on artificially drying freshly harvested pear leaves at constant room temperature was conducted to amplify the negative effects of summer stressors. The relative water content of leaves and electrolyte leakage were determined before and after the stress according to generally accepted methods. It was found that relative humidity is an important factor for normal leaf development, and the change in its values in the summer months correlated with the variability of values of the stress parameter of pear leaves - electrolyte leakage. It was found that the widespread European variety Conference was the most susceptible to the effects of artificial stress. After a short drying period, this variety was characterized by a sharp increase in the electrolyte leakage to ~36 % on the background of a significant decrease in the relative water content in the leaves (71–73 %), due to the development of oxidative processes, leading to a violation of the integrity of cell membranes. Russian varieties Flamenko and Luberskaya, as well as the European variety Williams, on the contrary, by the studied physiological parameters had no strong differences (the change of physiological parameters was from 1.1 to 1.3 times), which allowed them to be identified as more resistant varieties to this type of stress exposure.

Transcriptomic Analysis Reveals Novel Regulators ofthe Scots Pine Stilbene Pathway.

Stilbenes accumulate in Scots pine heartwood where they have important roles in protecting wood from decaying fungi. They are also part of active defense responses, and their production is induced by different (a)biotic stressors. The specific transcriptional regulators as well as the enzyme responsible for activating the stilbene precursor cinnamate in the pathway are still unknown. UV-C radiation was the first discovered artificial stress activator of the pathway. Here, we describe a large-scale transcriptomic analysis of pine needles in response to UV-C and treatment with translational inhibitors, both activating the transcription of stilbene pathway genes. We used the data to identify putative candidates for the missing CoA ligase and for pathway regulators. We further showed that the pathway is transcriptionally activated by phosphatase inhibitor, ethylene and jasmonate treatments, as in grapevine, and that the stilbene synthase promoter retains its inducibility in some of the tested conditions in Arabidopsis, a species that normally does not synthesize stilbenes. Shared features between gymnosperm and angiosperm regulation and partially retained inducibility in Arabidopsis suggest that pathway regulation occurs not only via ancient stress-response pathway(s) but also via species-specific regulators. Understanding which genes control the biosynthesis of stilbenes in Scots pine aids breeding of more resistant trees.