Stress Fluctuations Research Articles

Turbulent blood flow in a cerebral artery with an aneurysm

Unruptured intracranial aneurysms are common in the general population, and many uncertainties remain when predicting rupture risks and treatment outcomes. One of the cutting-edge tools used to investigate this condition is computational fluid dynamics (CFD). However, CFD is not yet mature enough to guide the clinical management of this disease. In addition, recent studies have reported significant flow instabilities when refined numerical methods are used. Questions remain as to how to properly simulate and evaluate this flow, and whether these instabilities are really turbulence. The purpose of the present study is to evaluate the impact of the simulation setup on the results and investigate the occurrence of turbulence in a cerebral artery with an aneurysm. For this purpose, direct numerical simulations were performed with up to 200 cardiac cycles and with data sampling rates of up to 100,000 times per cardiac cycle. Through phase-averaging or triple decomposition, the contributions of turbulence and of laminar pulsatile waves to the velocity, pressure and wall shear stress fluctuations were distinguished. For example, the commonly used oscillatory shear index was found to be closely related to the laminar waves introduced at the inlet, rather than turbulence. The turbulence energy cascade was evaluated through energy spectrum estimates, revealing that, despite the low flow rates and Reynolds number, the flow is turbulent near the aneurysm. Phase-averaging was shown to be an approach that can help researchers better understand this flow, although the results are highly dependent on simulation setup and post-processing choices.

Shape sensing with iFEM on a type IV pressure vessel based on experimental measurements

The service life of a ship depends on its structural integrity, which can be undermined through time via different loading conditions. The incorporation of a Structural Health Monitoring (SHM) system could enhance the safety of the vessel because information about its health condition could potentially lead to the avoidance of catastrophic scenarios by the detection of structural damages and their progression, especially when they may be unobservable via physical inspection. Within this context, a model-based SHM method called inverse Finite Element Method (iFEM) has been recently developed to assess the displacement and stress profile of vessels. iFEM offers several advantages, including the independence from material properties and loading conditions, the lack of training procedures, and the limited computational demand, which makes it suitable for real-time applications, enabling to reconstruct the complete displacement, and thus, the strain field starting from discrete strain measures. In this work, we explore the application of the iFEM in challenging scenarios, regarding repeated stress fluctuations (e.g. fatigue) or other type of mechanisms like corrosion, buckling or even externally imposed damages from collision impacts or combat type damages (explosions, ballistic, etc.), depending on the specific case of naval vessels. An anomaly index is used to highlight the health state of the structure by comparing the strain predicted by the iFEM at some test locations with the strain measured by a test sensor in the same position. The two values will match only for the healthy structure, while their departure from each other will indicate anomalous conditions. Though the formulation of the diagnostic problem is general for an arbitrary component geometry and damage type, the proposed study is accompanied by some numerical examples applied to a realistic ship case.

Study on fault-slip process and seismic mechanism under dynamic loading of hard roof fracture disturbance

The dynamic stress disturbance induced by mining is a significant factor triggering fault-slip. To better understand the impact of mining-induced hard roof fracture on fault-slip, combined with the geological conditions of a longwall face in contact with the fault, a dynamic and static numerical model was established using FLAC3D. The influence of dynamic loading from hard roof fracture on fault stability was investigated. The characteristics of changes in fault shear stress, shear displacement, slip area, and seismic moment under dynamic loading were analyzed. Simultaneously, numerical results were compared and analyzed against microseismic (MS) monitoring records in the mining, validating the accuracy of the numerical results. The results indicate that dynamic loading is a critical factor in inducing fault-slip. As a geological weak surface, the fault impedes the transmission of shock waves and causes their attenuation. Under dynamic loading, when the fluctuation of fault shear stress and friction coefficient exceeds the threshold, the fault-slip. During the fault-slip process, accompanied by a sharp increase in shear displacement, the seismic moment increases. Finally, the influence of changes in seismic parameters (e.g. longwall–fault distance, seismic energy, and seismic location) on the fault-slip mechanism was analyzed. This study contributes to a better understanding of the disturbance mechanism of mining-induced dynamic loading on fault-slip and provides a theoretical basis for fault-slip rock bursts.

Bidirectional associations between prolonged grief symptoms and depressive, anxiety, and posttraumatic stress symptoms: A systematic review.

Prolonged grief symptoms frequently co-occur with symptoms of depression, posttraumatic stress, and anxiety; however, little is known about how prolonged grief symptoms temporally relate to symptoms of neighboring stress-related and affective disorders. Clarifying such associations can help elucidate which symptoms to prioritize during treatment for distressed bereaved adults. We conducted a systematic review to provide a comprehensive overview of the empirical research on the bidirectional temporal associations between prolonged grief symptoms and symptoms of depression, posttraumatic stress, and anxiety. A search of the PsycInfo, Web of Science, and Scopus databases (final search: December 2023) identified eight relevant empirical longitudinal studies utilizing lower-level mediation (two studies), cross-lagged panel modeling (CLPM; four studies), or random-intercept CLPM (RI-CLPM; two studies). The studies included a total of 2,914 bereaved adult participants. Studies showed considerable methodological heterogeneity, including different sample characteristics, study designs (e.g., measurement moments, time frames), statistical analyses, and measures. Temporal associations between prolonged grief symptoms and different types of symptoms appeared intertwined. Prolonged grief symptoms more consistently predicted symptoms of depression and posttraumatic stress across measurement waves than vice versa, tentatively suggesting that prolonged grief may be a transdiagnostic risk factor for depressive and PTS symptoms. However, this pattern was not observed in the two studies utilizing RI-CLPM. Future research should aim to decrease methodological heterogeneity by using validated measures to capture prolonged grief symptoms, appropriate timeframes, and RI-CLPM to clarify associations between temporal within-person fluctuations of prolonged grief, depressive, posttraumatic stress, and anxiety symptoms.

Reassessing type 2 diabetes in adolescents and its management strategies based on insulin resistance.

With changes in lifestyle behaviors, including dietary structure and habits, the prevalence of Youth-onset Type 2 Diabetes Mellitus (YODM) has increased 2 to 3 times compared to 30 years ago. YODM patients experience complications earlier, progress faster, and exhibit more severe symptoms. However, limited and inconclusive direct evidence, coupled with poor patient compliance, poses challenges in the clinical management of YODM. Apart from the continuous decline in pancreatic β-cell function and quantity, tissue-specific insulin resistance (IR) is also a typical characteristic of YODM. The main mechanisms of IR in YODM involve different aspects such as obesity, dietary imbalance, abnormal substance metabolism, chronic inflammation, oxidative stress, and hormonal fluctuations during adolescence. For the comprehensive management of YODM, besides achieving good control of blood glucose levels, it may be necessary to apply the most appropriate methods considering the uniqueness of the patient population and the specifics of the disease. Early identification and detection of the disease are crucial. Precise screening of patients with well-functioning pancreatic insulin β-cells, primarily characterized by IR and obesity, represents the population most likely to achieve diabetes remission or reversal through lifestyle modifications, medications, or even surgical interventions. Additionally, considering potential emotional disorders or the impact of adolescent hormones in these patients, health education for patients and caregivers is essential to make them aware of the long-term benefits of well-controlled blood glucose. In conclusion, adopting comprehensive management measures to achieve diabetes remission or reversal is the ideal goal. Controlling high blood glucose, obesity, and other risk factors related to diabetes complications is the next priority to delay the occurrence and progression of complications. A comprehensive perspective on IR provides insights and references for identifying YODM and its management strategies.

Local characteristics of bubbly flow in rods assembly 3 × 3

This study focuses on the experimental investigation of local characteristics of upward bubble flow in a 3 × 3 square rod bundle assembly. The experiments were conducted at Reynolds numbers ranging from 4000 to 11000 and gas void fractions up to 10%. The distribution of the gas phase around the central rod of the assembly was measured using a frontal conductivity probe, while the wall shear stress on the central rod was obtained through the electrodiffusion method. It is shown that the gas phase distribution does not exhibit the symmetry characteristic of the assembly cross-section. Furthermore, as the distance from the spacer grid increases, a reconfiguration of void fraction profiles is observed. This explains the non-monotonic dependence of wall shear stress and wall shear stress fluctuations on the distance to the spacer grid.

Opposition flow control for reducing skin-friction drag of a turbulent boundary layer

This work explores the dynamic response of a turbulent boundary layer to large-scale reactive opposition control, at a friction Reynolds number of Reτ≈2240. A surface-mounted hot-film is employed as the input sensor, capturing large-scale fluctuations in the wall-shear stress, and actuation is performed with a single on/off wall-normal blowing jet positioned 2.4δ downstream of the input sensor, operating with an exit velocity of vj=0.4U∞. Our study builds upon the work of Abbassi [] and includes a control-calibration experiment and a performance assessment using PIV- and PTV-based flow field analyses. With the control-off calibration-experiment conducted , a transfer kernel is identified so that the velocity fluctuations that are to-be-controlled can be estimated. The controller targets large-scale high-speed zones in an “opposing” mode and low-speed zones in a “reinforcing” mode. A desynchronized mode was tested for reference and consisted of a statistically similar control mode, but without synchronization to the incoming velocity fluctuations. An energy-attenuation of about 40 % is observed for the opposing control mode in the frequency band corresponding to the passage of large-scale motions. This proves the effectiveness of the control in targeting large-scale motions: an energy-intensification of roughly 45% occurs for the reinforcing control mode instead, while no change in energy, within the wall-normal range targeted, appears with the desynchronized control mode. Moreover, direct measures of the skin-friction drag are inferred from PTV data. Results indicate that the opposing control logic yields the lowest wall-shear stress (3% lower than the desynchronized control, and 10% lower than the uncontrolled flow). Finally, a FIK-decomposition of the skin-friction coefficient revealed that the off-the-wall turbulence follows a consistent trend with the PTV-based wall-shear stress measurements, although biased by an increased shear in the wake of the boundary layer given the formation of a plume due to the jet-in-crossflow actuation. Published by the American Physical Society 2024

Numerical Analysis of Temperature and Stress Field of Side Dam on the Twin‐Roll Strip Casting

Side sealing technology is crucial in the twin‐roll casting process. The performance of side dam materials directly determines twin‐roll casting (TRC) process stability and safety. An orthogonal test is conducted to study the effects of thermal conductivity, linear expansion coefficient, and elastic modulus on the maximum thermal stress of side dams. The elastic modulus and linear expansion coefficient are identified as key factors affecting the maximum thermal stress of the side dam. The fluctuation of maximum thermal stress under different elastic modulus and linear expansion coefficients is 79.7 and 75.8 MPa, respectively, whereas it is only 11.2 MPa under different thermal conductivity. A side dam with heterogeneous material along height and thickness gradient is designed. The results indicate that the maximum thermal stress in the contact area between the side dam and the molten metal decreases to 31.2 MPa, representing a reduction of more than 30 MPa compared to the homogeneous side dam with optimal performance. The results provide important guidance in improving the stability of the TRC process.

Study on dynamic stress variation of head cover bolt during transient operation of pump turbine

Abstract The head cover bolt is an important connecting part of pump turbine, if it is damaged, it will affect the operation safety of the unit and the power station. During the transient process, such as start-up and load rejection in extreme case, the head cover bolt is subjected to complex load action, and its stress also changes, and extreme cases may occur. The dynamic stress level of the bolt will have a certain influence on its fatigue life, therefore, in order to further study the dynamic stress level and variation law of the bolt, this paper relies on a pumped-storage station, the dynamic stress of the head cover bolt during the start-up and load rejection is measured, and the pressure pulsation between the head cover and the runner and the bladeless zone are collected synchronously. Through the data analysis, the bolt dynamic stress level and variation law and the correlation between stress and pressure fluctuation under the power generation and pumping conditions are summarized.

FSI simulation of a high-head pump-turbine during load rejection process

Abstract High-head pump-turbine suffers large centrifugal and hydraulic forces due to large rotational speed and severe pressure pulsations during transient processes, and the strong vibration may increase the risk of runner failure. Load rejection transient process is crucial for pumped-storage hydropower stations, and the evolution laws of the runner dynamic stress during this process need profound research. In this study, the evolution of the runner dynamic stress of a prototype pump-turbine during a load rejection transient process was simulated using the one-dimensional and three-dimensional coupling (1D-3D) method and the fluid-structure interaction (FSI) method. The results of this dynamic transient process were compared to the results of the static working points. It is shown that the rotational speed dominates the mean value of stress while the fluctuating amplitude of stress is dominated by pressure fluctuations, which are larger in the S-shaped region of characteristics. Compared with the static working point solutions, the transient process solutions can better reflect the stress fluctuations and should be used for safety assessment.

Exploitation of Grafting for Abiotic and Biotic Stress Management in Vegetable Crops: A Review

Growing vegetables is often impacted by various abiotic and biotic stresses that can hinder growth and yield. Abiotic stresses, such as salinity, water stress, and temperature fluctuations, and biotic stresses, including diseases, pests, and nematodes, pose significant threats to agriculture. Grafting, a horticultural technique, offers a promising solution to overcome these challenges. In cases of salinity stress, grafting with salt-tolerant rootstocks can limit the transport of harmful ions to the shoot and help store them in the roots, mitigating ion toxicity. Water stress, including drought and water logging, can be addressed by grafting with drought-tolerant rootstocks, which can reduce yield losses and enhance photosynthesis under adverse water conditions. Grafting can also improve nutrient uptake, translocation of water, and osmoregulation, thereby assisting plants in surviving under water stress. High and low-temperature stresses, which can disrupt plant metabolism, membrane stability, and growth, can also be addressed through grafting. Grafted plants with temperature-tolerant rootstocks may indirectly enhance tolerance to extreme temperatures. Additionally, grafted plants can adapt to varying temperature conditions by promoting root growth, nutrient absorption, and the production of specific compounds that protect against temperature-related damage. Heavy metal stress, which can contaminate crops and impact human health, can be alleviated by using rootstocks that control the uptake and transport of heavy metals, reducing their toxicity to plants. Furthermore, grafting can effectively combat biotic stresses. By selecting disease-resistant rootstocks, plants can be protected against soil-borne diseases, pests, and nematodes, thereby increasing yields and sustainability in agriculture.

Coupling structural, chemical composition and stress fluctuations with relaxation dynamics in metallic glasses

Understanding the atomistic mechanisms of relaxation dynamics in metallic glasses remains a longstanding challenge. Here, using microsecond time scale molecular dynamics simulations, three main relaxation stages in metallic glasses are identified. At about 0.6Tg, chemical composition plays a dominant role in the relaxation, manifested by stress accumulation and only minimal variations in structure. As Tg approaches, the confluence of structural heterogeneity and chemical composition leads to the decoupling of relaxation mechanisms. At this temperature, the relaxation results in a structure with a lower energy state and a lower level of stress. In the supercooled liquid regime, an extensive increase in the number of closed-packed icosahedral clusters is responsible for accelerated structural relaxation while their packing frustration leads to the accumulation of intrinsic residual stresses in the glass. The atomistic origin of these dynamic relaxation modes is discussed in terms of structural, chemical composition and stress variations.

Multi-factor corrosion model of TP110TS steel in H2S/CO2 coexistence and life prediction of petroleum casings

The failure of petroleum casings due to the combined effects of CO2/H2S corrosion and internal pressure has become a main concern during the exploitation of high-temperature, high-pressure, and high-corrosion gas fields. Therefore, establishing a corrosion evolution model is crucial for accurately predicting the service life of casings. In this study, an analytical model describing the corrosion rate of casing steel TP110TS under different CO2/H2S partial pressures and applied stresses was established, combined with the mechanical-chemical effect. The weightlessness method was used to determine the model parameters from the experimental results using a multiple regression. Based on the elasticity, a service life prediction model considering mechanical property attenuation and casing stress fluctuation was established from the assumption of uniform thickness thinning. The effects of internal pressure and CO2/H2S partial pressures on the service life were analyzed. The corrosion rate initially decreased with time. However, the stress increased as the wall thickness decreases from corrosion. The stress-promoting corrosion effect gradually manifested, and the corrosion rate rapidly increased. The higher the internal pressure and H2S/CO2 partial pressure, the shorter was the service life of the casing. In the H2S/CO2 coexistence environment, the influence of H2S partial pressure was more significant than that of CO2.

Topology optimization of AISI 4140 steel with surface texture filled by multi-solid lubricants for enhancing tribological properties

Wind power gears will be excessively worn due to lubrication failure during operation. Herein, the tribological properties of rubbing pairs are improved by filling solid lubricants into surface texture. In texture design, three types of topological textures (Circle (C), Hexagon (H) and Circle/Hexagon (CH)) were obtained by cell topology optimization, and then three cases with 20%, 30%, and 40% density were designed for each texture. Next, SnAgCu and TiC were deposited in texture of AISI 4140 steel (AS) to obtain 9 kinds of self-lubricating surfaces. Among them, AS with 30% CH density (AS-CH30) exhibits excellent mechanical and tribological properties. Compared with AS-C and AS-H, the maximum equivalent stress of AS-CH was decreased by 10.86% and 5.37%, respectively. Friction coefficient and wear rate of AS-CH30 were 79.68% and 78% lower than those of AS. The excellent tribological performances of AS-CH30 can be attributed to the synergistic effect of topological surface and solid lubricants. Topological surface can not only reduce fluctuation of equivalent stress, but also promote the stored lubricants to be easily transferred at the contact interface to form a 200 nm lubricating film containing solid lubricants (mainly), oxides and wear debris.

Dynamic response of ultra-high performance engineered cementitious composites (UHP-ECC) under low-velocity impact: Effect of waste rubber incorporation and low temperatures

This study aims to explore the dynamic response of ultra-high performance engineered cementitious composites (UHP-ECC) incorporating waste crumb rubber (CR) at various temperatures, focusing on its potential to enhance the resilience and sustainability of civil infrastructures against low-velocity impacts. To date, the impact behaviour of UHP-ECC under low temperatures has rarely been explored. Firstly, natural river sand and waste tyre CR was utilized to prepare the UHP-ECC. Then, a series of mechanical tests, including compression test, flexural test and uniaxial tensile test were carried out to investigate the static mechanical properties of rubberised UHP-ECCs. In addition, the effects of different waste CR incorporations (0%, 5%, 10%, and 15%) and various temperatures (25 °C, −5 °C, −30 °C, −50 °C, −100 °C and −196 °C) were comprehensively investigated by low-velocity impact tests with constant impact energy. Lastly, the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) model was introduced to evaluate the overall performance of UHP-ECC. It was found that the use of river sand and CR significantly enhanced the tensile ductility and impact toughness of UHP-ECC. Impact energy primarily dissipates through damage such as matrix crack initiation, propagation, and fibre pull-out/rupture within the specimen. Adding CR notably decreased stress fluctuations during impact at room temperature, facilitating steady state energy absorption. Moreover, the time to reach peak impact force decreased with decreasing temperature across all UHP-ECC groups. At room temperature during impact process, fibre failure mode is dominated by pull-out failure, while lower temperatures lead to increased fibre rupture at the cracking surface. In low-temperature conditions, the impact response of rubberised UHP-ECC necessitates a comprehensive consideration of the synergistic effects, including material contraction, fibre bridging capacity, rubber phase transition, and water freezing.

Tensile strength of particle reinforced composite with interfacial debonding

Strength prediction of a particle reinforced polymer composite (PRPC) is still challenging. Although a PRPC is overall isotropic, it is more difficult to predict its tensile strength accurately than a continuous fiber reinforced composite (CFRC). One reason for this difficulty is that the calculation of stress fields of the constituents in a PRPC are complicated. The other reason is that the strength of a PRPC is significantly affected by interfacial strength, which is hard to be measured directly. In our research, the discount of the composite strength after debonding is attributed to the intensifying stress concentration. Two stress concentration factors (SCFs) are derived respectively to characterize the stress fluctuations in the matrix caused by the embedded particle before and after debonding. Based on the micromechanics Bridging Model and the matrix true stress theory, these two SCFs can be applied to evaluate the interface strength and the ultimate tensile strength of the composite from the properties of its component materials. Illustrations are presented to verify the efficiency of our theory and analyze the main influencing factors on the strength of the PRPC, including mechanical properties of component materials, particle size and volume fraction.

Direct numerical simulation of compressible turbulent channel flows over porous boundaries

The impact of porous boundaries on skin friction and heat transfer in compressible turbulent channel flows is explored through direct numerical simulations. Utilizing the volume-averaged Navier–Stokes equations for the porous media, we examine flows at Mach numbers Mb=0.3 and Mb=1.5, with friction Reynolds numbers ranging from 176 to 220, across three permeability levels: 0 (impermeable), 1.6×10−5, and 1.0×10−4. Our findings reveal a dual impact of porous boundaries on skin friction: a direct reduction due to averaged slip velocity at the interface and an indirect increase from amplified Reynolds shear stress due to enhanced wall-normal permeability. This permeability weakens the wall-blocking effect, leading to intensified wall-normal velocity fluctuations and consequently higher Reynolds stress. Additionally, the Mach number significantly influences flow structures, particularly at higher permeabilities, where it disrupts near-wall streaks at Mb=0.3 but has a diminished effect at Mb=1.5. Thermal analysis confirms the validity of the generalized Reynolds analogy for the mean temperature in these flows, with the turbulent Prandtl number approximating 1, in line with the strong Reynolds analogy. Moreover, a strong spatial correlation between heat flux and wall shear stress fluctuations underscores the intertwined dynamics of momentum and thermal transport at the porous–fluid interface.

Engineering properties of microcapsules self-healing geopolymer cutoff wall backfill under dry-wet cycles

Vertical cutoff wall has been employed for decades to control groundwater flow and subsurface contaminant transport. Environmental stress fluctuations induced by alternating dry and wet conditions impair the permeability and durability of the cutoff wall, leading to the dispersion of contaminants. The objective of this study is to incorporate self-healing microcapsules into existing geopolymer cutoff wall backfill (GCWB) to form self-healing geopolymer cutoff wall backfill (SHGCWB) that hold promise for better durability and performance. The in-situ polymerization method was used to develop single-walled and double-walled microcapsules. The microcapsules use sodium silicate as the healing agent encapsulated in single-walled polyurethane (PU) and double-walled polyurethane/melamine-formaldehyde (PU/MF) microcapsules. The effect of microcapsules on the unconfined compressive strength (UCS) and hydraulic conductivity of SHGCWB were elaborated. The durability and hydraulic conductivity variation of SHGCWB in dry-wet cycle was thoroughly investigated by Scanning Electron Microscopy (SEM) test for understanding the self-healing mechanism. The overall performance demonstrated the significant potential of the use microcapsules as a self-healing approach for cutoff walls.

Atomic behavior of nickel-based single crystal superalloy during heat treatment process based on molecular dynamics

The heat treatment process plays a pivotal role in enhancing the characteristics of nickel-based single crystal (NBSC) superalloys. Nevertheless, there exists a paucity of comprehensive investigations concerning the microstructural evolution of NBSC superalloys during heat treatment. This study employs a molecular dynamics simulation method to control the temperature of the NBSC superalloy precisely, aiming to unveil intricate details regarding microstructural evolution, temperature distribution patterns, mechanical properties, and other pertinent aspects during the cooling phase. Additionally, a comparative analysis of internal defect evolution under varying cooling rates is undertaken. The findings highlight the consistently heightened activity of atoms in the γ phase compared to those in the γ′ phase. Notably, the stability disparity between these phases gradually diminishes as the temperature decreases during the cooling process. At elevated temperatures, the prevalence of amorphous phases and dislocations in the γ phase channel diminishes concomitantly with the temperature reduction. Strain distribution in the alloy primarily concentrates in the γ phase channel and the central cross position of the γ′ phase. The temperature reduction correlates with a decline in the alloy model’s strain. In the initial phase of strain reduction, stress fluctuation trends in the X, Y, and Z directions exhibit an initial increase followed by a gradual decrease. Furthermore, the atomic number of HCP defects and dislocation density exhibit distinct patterns of change contingent upon the cooling rates employed.

Screen Time and Psychosocial Health Conditions Amongst University Students

Abstract University students, predominantly young adults, spend vast periods of the day utilizing technology and looking at screens to complete assignments, study and relax. These students also commonly complain of several mental health disorders. The aim of this study is to determine how neurological stress, such as anxiety, depression and more, affects average screen time and to assess the weekly fluctuations in neurological stress and their influence on screen use. Additional factors (gender, quality of sleep, alcohol, etc.) were also considered with regards to their relation to screen time. The data collection was conducted in 2022, targeting university students of ages 18-24 in Ajman, UAE, via a self-administered questionnaire. 425 responses were collected and crosstabulation, using the Chi square test (p <0.05), was performed to assess statistical significance. Significant statistical association was found between depression and other psychological states (mood swings, insomnia, addictive tendencies) with screen time during the week and weekend. No other associations were identified. Overall, this study affirms the relation between negative mental health and its effects on the average user screen time amongst university students in Ajman. Additional studies are needed to clarify what specific contents and types of screens are more impactful on mental health. JEL classification numbers: I12, I19. Keywords: Screen time, Depression, Stress, University Students.