Stress Model Research Articles

Metabolic responses of sea anemone and jellyfish to temperature and UV bleaching: Insights into stress adaptation using LCMS-based metabolomics, molecular networking and chemometrics

IntroductionClimate change poses various threats to marine life, particularly in shallow tropical waters. Objective: The impact of increased temperature and ultraviolet (UV) exposure on two photosymbiotic Cnidarians, a common bubble-tip anemone and an upside-down jellyfish, was investigated. MethodsTo illustrate the response of aquatic organisms, the metabolomes of unstressed Entacmaea quadricolor and Cassiopea andromeda were compared for detailed metabolite profiling. UHPLC-MS coupled with chemometrics and GNPS molecular networking was employed for sample classification and identification of markers unique to stress responses in each organism. ResultsSeveral compounds with bioactive functions, including peptides and terpenoids, were reported for the first time in both organisms, viz. cyclic tetraglutamate, campestriene, and ceramide aminoethyl phosphonate (CEAP d18:2/16:0). Both anemone and jellyfish were subjected to either elevated UV-B light intensity up to 6.6 KJ m−2 or increased temperatures (28 °C, 30 °C, 32 °C, and 34 °C) over 4 days. Phospholipids, steroids, and ceramides emerged as chief markers of both types of stress, as revealed by the multivariate data analysis. Lysophosphatidylcholine (LPC 16:0), LPC (18:0/0:0), and echinoclasterol sulfate appeared as markers in both UV and thermal stress models of the anemone, whereas methyl/propyl cholestane-hexa-ol were discriminatory in the UV stress model only. In the case of jellyfish, nonpolar glycosyl ceramide GlcCer (d14:1/28:6) served as a marker for UV stress, whereas polar peptides were elevated in the thermal stress model. Interestingly, both models of jellyfish share a phospholipid, lysophosphatidylethanolamine (LPE 20:4), as a distinctive marker for stress, reported to be associated indirectly with the activity of innate immune response within other photosymbiotic Cnidaria such as corals and appears to be a fundamental stress response in marine organisms. ConclusionThis study presents several bioinformatic tools for the first time in two cnidarian organisms to provide not only a broader coverage of their metabolome but also broader insights into cnidarian bleaching in response to different stressors, i.e., heat and UV light, by comparing their effects in anemone versus jellyfish.

Melatonin Protects Against Mitochondrial Dyshomeostasis and Ovarian Damage Caused by Chronic Unpredictable Mild Stress Through the eIF2α-AFT4 Signaling Pathway in Mice.

Stress is an emotional state caused by an unexpected external environmental change or stimulus, and several experiments have demonstrated its negative impact on ovarian function, ultimately affecting reproductive ability. Melatonin (MT) has been shown to facilitate oocyte maturation and enhance ovarian function by regulating mitochondrial function. However, the specific effect and underlying molecular mechanisms of MT on stress-induced ovarian dysfunction remain largely unknown. In this study, we established a mouse model of chronic unpredictable mild stress (CUMS) to investigate its impact on ovarian function. Our findings revealed that CUMS led to premature ovarian insufficiency (POI) in mice, characterized by a reduction in follicle numbers and decreased levels of anti-Müllerian hormone (AMH) and bone morphogenetic protein 15 (BMP15). Furthermore, CUMS caused decreased expression of mitochondrial fission protein 1 (FIS1) and enhanced level of mitochondrial fusion protein optic atrophy 1(OPA1), mitofusin1(MFN1), as well as nucleus-encoded protein succinate dehydrogenase complex A (SDHA), reflecting mitochondrial dyshomeostasis. Additionally, CUMS resulted in excessive autophagy and apoptosis. However, MT reversed these effects and improved ovarian damage. Importantly, the protective effects of MT were mediated through the inhibition of the eIF2α-AFT4 pathway. Overall, this study provides valuable insights into the treatment of POI caused by CUMS.

Caregiving, caring intensity, and allostatic load: A comparison of caring to others inside and outside the home

ObjectiveCaregiving to a sick or disabled relative is a key chronic stress model in health psychology. However, caregiving is not uniformly stressful, and this study tested whether caregiving effects on life satisfaction and allostatic load varies by caring intensity, i.e., caring within the home, outside the own home, or both (e.g. Dual caring). MethodUsing data from the UK Understanding Society Wave 2, a sample of non-caregivers (N = 3149) and caregivers (N = 562) met inclusion criteria and completed measures of life satisfaction and provided blood samples for capturing endocrine, cardiovascular and immune parameters for assessment of allostatic load. ResultsDual caregivers had lower life satisfaction compared to non-carers, and other caregiver groups. Further, dual caregivers had higher levels of allostatic load compared to non-carers and those caring within the home and those caring outside the home. These group differences withstood adjustment for several co-variates including gender, education, income and lifestyle factors. ConclusionsThese results confirm that caregiving is not uniformly stressful with dual caring, an index of caring intensity being more damaging for health. The findings are also discussed in relation to the caregiver-control model of chronic stress.

Moringa oleifera Lam. seed lectin (WSMoL) reduces chronic stress-induced anxiety and depression in mice by lessening inflammation and balancing brain chemicals.

Phyto-based treatments for anxiety and depression are gaining attention. The efficacy of the water-soluble Moringa oleifera seed lectin (WSMoL) in reducing acute anxiolytic and depressive-like behaviors in mice has been previously demonstrated. In the present study, it was evaluated the effects of WSMoL on reducing anxiety and depressive-like symptoms in a mouse model of unpredictable chronic mild stress (UCMS). The animals were divided into groups and exposed to a four-week UCMS regimen. Following this, the mice received daily intraperitoneal injections of vehicle (non-stressed and UCMS control groups), WSMoL (2 or 4mg/kg), or fluoxetine (10mg/kg) for 21 days. Neurobehavioral tests included the open field test and elevated plus maze test to assess anxiety-like behavior, and the tail suspension test and sucrose preference test to evaluate depression-like behavior. Biochemical analyses measured serum corticosterone and cytokines as well brain levels of cytokines and monoamines. All tests indicated that WSMoL significantly (p < 0.05) reversed the anxiety and depression-like behaviors induced by UCMS. The stress protocol increased serum corticosterone levels and WSMoL treatment was not able to normalize corticosterone secretion. WSMoL treatment reduced serum and brain levels of IL-2, IL-6, and TNF-α, indicating reduced neuroinflammation, and increased brain levels of dopamine, serotonin, and noradrenaline, respectively. In summary, WSMoL mitigated UCMS-induced anxiety and depression-like behaviors by reducing neuroinflammation and modulating brain monoamine levels.

Omeprazole affects the expression of serotonin-1A in the brain regions and alleviates anxiety in rat model of immobilization-induced stress.

Omeprazole, a drug of choice for the management of gastric hyperacidity, influences serotonergic neurotransmission in brain regions and its long-term use is known to cause stress-related behavioral deficits including anxiety. Aim of the current study was to explore the effects of omeprazole treatment on immobilization-induced anxiety in rats, specifically on the role of serotonin (5-HT). In view of the role of serotonin-1A (5-HT1A) autoreceptor in the availability of 5-HT in brain regions, mRNA expression of this autoreceptor was performed in raphe nuclei. Similarly, because of the role of hippocampal 5-HT neurotransmission in anxiety-like disorders, expression of the 5-HT1A heteroreceptors was determined in this region. We found that the treatment with omeprazole reduces anxiety-like behavior in rats, increases the expression of 5-HT1A autoreceptor in the raphe and decreases the hippocampal expression of 5-HT1A heteroreceptor. This suggests a role of 5-HT1A receptor types in omeprazole-induced behavioral changes. It also indicates a potential role of omeprazole in the management of serotonergic disorders.

Antidepressant-like and antistress effects of the ACTH(4–10) synthetic analogs Semax and Melanotan II on male rats in a model of chronic unpredictable stress

Current antidepressant therapy shows substantial limitations, and there is an urgent need for the development of new treatment strategies for depression. Stressful events and hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis play an important role in the pathogenesis of depression. HPA axis activity is self-regulated by negative feedback at several levels including adrenocorticotropic hormone (ACTH)-mediated feedback. Here, we investigated whether noncorticotropic synthetic analogs of the ACTH(4–10) fragment, ACTH(4–7)-Pro-Gly-Pro (Semax) and Ac-Nle4-cyclo[Asp5-His6-D-Phe7-Arg8-Trp9-Lys10]ACTH(4–10)-NH2 (Melanotan II (MTII), a potent agonist of melanocortin receptors), have potential antidepressant activity in a chronic unpredictable stress (CUS) rat model of depression. Stressed and control male adult Sprague-Dawley rats received daily intraperitoneal injections of saline or a low dose (60 nmol/kg of body weight (BW)) of Semax or MTII. Rats were monitored for BW and hedonic status, as measured in the sucrose preference test. We found that chronic treatment with Semax and MTII reversed or substantially attenuated CUS-induced anhedonia, BW gain suppression, adrenal hypertrophy and a decrease in the hippocampal levels of BDNF. In the forced swim test, no effects of the CUS procedure or peptides on the duration of rat immobility were detected. Our findings show that in the CUS paradigm, systemically administered ACTH(4–10) analogs Semax and MTII exert antidepressant-like effects on anhedonia and hippocampal BDNF levels, and attenuate markers of chronic stress load, at least in male rats. The results support the argument that ACTH(4–10) analogs and other noncorticotropic melanocortins may have promising therapeutic potential for the treatment and prevention of depression and other stress-related pathologies.

Enhancing uterine receptivity for embryo implantation through controlled collagenase intervention.

Ineffective endometrial matrix remodeling, a key factor in infertility, impedes embryo implantation in the uterine wall. Our study reveals the cellular and molecular impact of human collagenase-1 administration in mouse uteri, demonstrating enhanced embryo implantation rates. Collagenase-1 promotes remodeling of the endometrial ECM, degrading collagen fibers and proteoglycans. This process releases matrix-bound bioactive factors (e.g., VEGF, decorin), facilitating vascular permeability and angiogenesis. Collagenase-1 elevates embryo implantation regulators, including NK cell infiltration and the key cytokine LIF. Remarkably, uterine tissue maintains structural integrity despite reduced endometrial collagen fiber tension. In-utero collagenase-1 application rescues implantation in heat stress and embryo transfer models, known for low implantation rates. Importantly, ex vivo exposure of human uterine tissue to collagenase-1 induces collagen de-tensioning and VEGF release, mirroring remodeling observed in mice. Our research highlights the potential of collagenases to induce and orchestrate cellular and molecular processes enhancing uterine receptivity for effective embryo implantation. This innovative approach underscores ECM remodeling mechanisms critical for embryo implantation.

Hypocretin-1/Hypocretin Receptor 1 Regulates Neuroplasticity and Cognitive Function through Hippocampal Lactate Homeostasis in Depressed Model.

Cognitive dysfunction is not only a common symptom of major depressive disorder, but also a more common residual symptom after antidepressant treatment and a risk factor for chronic and recurrent disease. The disruption of hypocretin regulation is known to be associated with depression, however, their exact correlation is remains to be elucidated. Hypocretin-1 levels are increased in the plasma and hypothalamus from chronic unpredictable mild stress (CUMS) model mice. Excessive hypocretin-1 conducted with hypocretin receptor 1 (HCRTR1) reduced lactate production and brain-derived neurotrophic factor (BDNF) expression by hypoxia-inducible factor-1α (HIF-1α), thus impairing adult hippocampal neuroplasticity, and cognitive impairment in CUMS model. Subsequently, it is found that HCRTR1 antagonists can reverse these changes. The direct effect of hypocretin-1 on hippocampal lactate production and cognitive behavior is further confirmed by intraventricular injection of hypocretin-1 and microPET-CT in rats. In addition, these mechanisms are further validated in astrocytes and neurons in vitro. Moreover, these phenotypes and changes in molecules of lactate transport pathway can be duplicated by specifically knockdown of HCRTR1 in hippocampal astrocytes. In summary, the results provide molecular and functional insights for involvement of hypocretin-1-HCRTR1 in altered cognitive function in depression.

Unpredictable chronic mild stress induced anxio-depressive disorders and enterobacteria dysbiosis: Potential protective effects of Detariummicrocarpum

Ethnopharmacological relevanceDetarium microcarpum Guill. & Perr. is used traditionally in Far North Cameroun to treat stomach aches, anxiety, epilepsy, and other mental disorders. Aim of the studyEvaluate the anxiolytic and antidepressant-like effects of D. microcarpum (DM) in unpredictable chronic mild stress (UCMS) model of depression in male rats and its impact on fecal enterobacteria of stressed rats. Materials and methodsRats were handled daily (control) or subjected to the UCMS procedure for 42 days. Anxiety-like behaviors were assessed using the light and dark box test (LBD) and the open field test (OFT). Depressive-like behaviors were assessed using the forced swimming test (FST), the sucrose preference test (SPT), and the novelty suppressed feeding test (NSFT). Feces were then collected, followed by blood, brain, and duodenum sections after sacrifice. Monoamine levels, pro-inflammatory cytokines, oxidative stress factors, and nitrosative stress were assessed. Feces were introduced into Hectoen enteric agar for the identification of enterobacteria. An in vitro growth test was performed. ResultsThe DM ethanolic extract has significantly increased the time spent in the light box, in the LBD, and in the center area of the OFT. Moreover, the extract has significantly reduced the preference for sucrose in the SPT, the time of immobility in the FST, and the latency period to consume the pet in the NSFT. DM extract has significantly reduced serum cortisol levels. It also significantly decreased the pro-inflammatory cytokines TNF-α and Il-1β in both brain and duodenum homogenate. DM has increased the brain's serotonin, GABA, and dopamine levels. The DM extract also decreased the MDA and nitrite levels. It also increased the SOD and CAT activities in both brain and duodenal homogenate. Histologically, the DM extract restored the cell's density in hippocampi sections and prevented gut inflammation and peroxidation characterizing leaky gut syndrome. DM extract has no effect on the growth of enterobacteria species isolated in vitro. ConclusionThe ethanolic extract of DM would have anxiolytic and antidepressant effects via the modulation of the HPA axis, brain antioxidant enzyme activities, inflammation, and nitrosative stress. Moreover, it could act by preventing leaky gut syndrome.

How Creativity Influenced by the Network Efficiency of a Student’s Ego Network Affect Academic Performance Through Academic Coping Strategies?

The purpose of this study is to investigate the dual mediation role of creativity and academic coping in network efficiency and academic performance, using Folkman and Lazarus’s transactional model of stress. Data were obtained from 39 students taking business administration at a Korean university. Social network analysis was performed to check the ego network of students. The double mediation model was applied to analyze the path from network efficiency to academic performance. The results showed that network efficiency, in relation to the structural hole in social network parameters, was double mediated by creativity and academic coping, which had a positive effect on academic performance. However, the effect of double mediation through avoidance was insignificant. Based on the research results, the theoretical and practical implications for the dual mediation effect of creativity and academic coping were presented.

S-(+)-mecamylamine increases the firing rate of serotonin neurons and diminishes depressive-like behaviors in an animal model of stress

Mecamylamine, a noncompetitive blocker of nicotinic acetylcholine receptors (nAChRs), is the racemic mixture of two stereoisomers: S-(+)-mecamylamine (S-mec) and R-(−)-mecamylamine (R-mec), with distinct interactions with α4β2 nAChRs. It has been shown that mecamylamine increases glutamate release and excites serotonergic (5-HT) neurons in the dorsal raphe nucleus (DRN). In this study, we separately evaluated the effects of S-mec and R-mec on 5-HT neuron excitability. S-mec (3 μM) increased firing frequency by 40 %, while R-mec (3 μM) raised it by only 22 %. S-mec acts as a positive allosteric modulator on high-sensitivity (HS) α4β2 nAChRs at glutamate terminals, enhancing spontaneous excitatory postsynaptic currents (sEPSCs) in 5-HT neurons. Conversely, R-mec decreased sEPSCs by blocking HS α4β2 nAChRs and reduced GABA-mediated inhibitory currents (sIPSCs) by blocking α7 nAChRs at GABAergic terminals. These mechanisms make S-mec more effective than R-mec in enhancing 5-HT neuron firing. Moreover, combining S-mec with TC-2559, a selective agonist of HS α4β2 nAChRs, increased firing frequency by 65 %, exceeding the effect of S-mec alone. To validate these findings, we evaluated the antidepressant effects of S-mec (1 mg/kg) combined with TC-2559 or RJR-2403, another α4β2 nAChR agonist. This combination successfully reduced depression-like behaviors, suggesting a potential treatment strategy for patients resistant to conventional antidepressants.

Quinic acid contributes to neurogenesis: Targeting Notch pathway a key player in hippocampus

Coordinated proliferation and differentiation of neural stem cells (NSCs) results in continuous neurogenesis. The present study provides novel insights into the Notch intracellular signaling in neuronal cell proliferation, maintenance, migration, and differentiation regulated by naturally based Quinic acid (QA) in primary hippocampal cell culture. Further, this study might help in the discovery and development of lead molecules that can overcome the challenges in the treatment of neurodegenerative diseases. The growth supporting effect of QA was studied using Alamar Blue assay. The migratory potential of QA was evaluated using scratch assay. The in vitro H2O2-induced oxidative stress model was used to upregulate neuronal survival after QA treatment. The RT-qPCR and immunocytochemical analysis were performed for selected markers of Notch signaling to determine the proliferation, differentiation, and maintenance of NSCs at gene and molecular levels. The Mash1 and Ngn2 are the upstream proneural genes of the Notch pathway which were included to evaluate the differentiation of NSCs into mature neurons after treatment with QA.Furthermore, regarding the role of QA in maintaining the pool of NPCs, we used Notch1 and Hes1 markers for proliferation analysis. Also, secondary neuronal markers i.e. Pax6, PCNA, and Mcm2 were included in this study and their gene expression analysis was analyzed following treatment with QA. Based on the study’s results, we suggest that naturally based QA can promote the growth and differentiation of neonatal NSCs residing in hippocampal regions into neuronal lineage. Therefore, we propose that the neurogenic potential of QA can be employed to prevent and treat neurodegenerative diseases.

Managing Stress From a Systemic Perspective: Occupational Stress Models

The World Health Organization (WHO) defines stress as a “state of worry or mental tension caused by a difficult situation.” Burnout results from chronic occupational stress that has not been well managed, and is the result of both systemic and personal factors. Systemic structures and planning to optimize work environments are the focus of occupational stress models. To effectively manage stress and avoid the detrimental effects of neglecting both its acute and chronic consequences (such as decreased productivity, low morale, interpersonal conflicts, absenteeism, and other negative outcomes), it is essential to examine various occupational stress models to determine root causes and identify issues at the work unit level. [ Psychiatr Ann . 2024;54(10):e287–e291.]

Sensitized Reynolds stress modeling of a bubbly jet emerging into a water cross-flow

The present work is concerned with the computational study of an air–water mixture stream emanating from a nozzle submerged in a water cross-flow inside a rectangular open channel to form a curved, intensively dispersed, bubbly jet. The work focuses on evaluating the predictive performance of an eddy-resolving turbulence model applied to the described case of a multiphase gas-liquid flow system characterized by a variety of closely coupled phenomena, including: turbulence anisotropy-induced secondary motion, free surface flow, bubbly jet propagation, and the varying interaction dynamics of the carrier water flow with the air bubble dispersion. Correspondingly, an appropriately extended differential near-wall Reynolds stress model, which describes the dynamics of unresolved subscale structures within the Sensitized Reynolds-Averaged Navier–Stokes (RANS) computational framework, is currently used in conjunction with a two-way coupled Euler–Lagrange approach to simulate this gas-water bubbly flow, with the operating and boundary conditions following the experimental reference of Zhang and Zhu (2013). Accordingly, the conditions at the free surface are adequately derived for all components of the residual turbulence stress tensor and the corresponding length scale determining variable. It is shown that the statistics of the bubble phase can be accurately captured, and the proper-orthogonal-decomposition analysis of the dynamic properties of the flow reveals at least two large-scale transient effects associated with the bubbly jet. Furthermore, in the preliminary part of this work it is shown that the currently applied turbulence model can be successfully used to correctly capture the effects of Reynolds stress anisotropy in the single-phase open-channel configuration, representing the incoming flow field of the main two-phase flow configuration.

Rheology of flexible fiber-reinforced cement pastes: Maximum packing fraction determination and structural build-up analysis

The maximum packing fraction (φfm) of flexible fibers is an essential parameter for understanding the rheological behavior of flexible fiber-reinforced cement paste (FFRCP). However, direct measurement of φfm of flexible fibers is still lacking. In this study, a shear rheology-based method for direct measurement of φfm was proposed and the assumption of fiber conformation under shear was verified by micro-CT. Based on this, a yield stress model for FFRCP was constructed to explain the entanglement and friction effects in the fiber network. Finally, static yield stress tests and small amplitude oscillatory shear (SAOS) tests were carried out to explore the structural build-up of FFRCP. It was found that the proposed method enables direct determination of φfm through only a few viscosity-fiber content data for a given FFRCP. Furthermore, the proposed model can describe the static yield stress of FFRCP well. Finally, the relative structural build-up rate of FFRCP follows a similar trend as the relative yield stress, with a critical relative fiber volume fraction (0.299) as the boundary. Subsequently, the relative structural build-up gradually deviates from the relative yield stress due to the limiting effect of the fibers.

Interfacial characterization of spinning water film along a concave wall

Abstract Thin liquid film flowing down the inner concave surface of a vertical cylindrical vessel is examined. At the top of the vessel, the water is injected horizontally at high speed circumferentially along the vessel wall and flows downwards due to the action of gravity. This turbulent film flow is modeled using the large eddy simulation (LES) and Reynolds averaged Navier–Stokes (RANS) approaches combined with the volume-of-fluid method. The results of both methods are validated with direct numerical simulation. The Favre-filtered two-phase LES, which is implemented and studied in this paper, can reasonably predict the film thickness similarly to that of the RANS approach using the elliptic blending Reynolds stress model, although it requires fine resolution in the wall region. The effect of volume flow rate on the film structure and thickness is investigated. The film thickness is shown to be nearly constant when the wall is partially wetted and changes as the cubic root of the volume flow rate when the spinning film encloses the entire circumference of the vessel.

Poverty Reduction and Family Functioning: Results from an Experimental Study in Sub-Saharan Africa

The study tests the effect of poverty-reduction intervention on family functioning reported by AIDS-orphaned children in extended families in Southern Uganda by asking two questions: (1) based on children’s reports, how does poverty reduction intervention affect family functioning? and (2) to what extent do these effects vary by a child’s gender and orphanhood status? Informed by the social causation theory, family stress model, and asset theory, the study aims to address the existing knowledge gap on effects of poverty reduction interventions on family functioning in low-income families caring for AIDS orphaned children in Uganda. We ran multilevel regression models using longitudinal data collected in a cluster-randomized controlled trial from N = 1410 children (n = 621 boys and n = 789 girls) recruited from 48 rural primary schools in Uganda. Survey data was collected every 12 months over the course of 5 years. The average age of children at enrollment was 13 years. We found significant positive effects of the intervention on family cohesion, family communication, and child-caregiver relationship. Effects vary by child’s gender and orphanhood category. Intervention improves family communication for boys, while improving family cohesion and quality of child-caregiver relationship for girls. Single maternal orphans reported improved family communication, while single paternal orphans reported improved child-caregiver relationship. Poverty reduction interventions are important to improve family functioning for low-income families. Variations by child’s gender and orphanhood status have not been reported in previous studies, and our findings underscore the importance of continued research in this area.

A novel mitochondrial pyruvate carrier inhibitor drives stem cell-like memory CAR T cell generation and enhances antitumor efficacy

Adoptive cell transfer with chimeric antigen receptor (CAR) expressing T cells can induce remarkable complete responses in cancer patients. Therapeutic success has been correlated with central and stem cell-like memory T cell subsets in the infusion product which are better able to drive efficient CAR T cell in vivo expansion and long-term persistence. We previously reported that inhibition of the mitochondrial pyruvate carrier (MPC) during mouse CAR T cell culture, induces a memory phenotype and enhances antitumor efficacy against melanoma. Here, we use a novel MPC inhibitor, MITO-66, which robustly induces a stem cell-like memory phenotype in CD19-CAR T cells generated from healthy donors and patients with relapsed/refractory B cell malignancies. MITO-66-conditioned CAR T cells were superior in controlling human pre-B cell acute lymphoblastic leukemia in mice. Following adoptive cell transfer, MITO-66-conditioned CAR T cells maintained a memory phenotype and protected cured mice against tumor rechallenge. Furthermore, in an in vivo B cell leukemia stress model, CD19-CAR T cells generated in the presence of MITO-66 largely outperformed clinical-stage AKT and PI-3Kδ inhibitors. Thus, we provide compelling preclinical evidence that MPC inhibition with MITO-66 during CAR T cell manufacturing dramatically enhances their antitumor efficacy, thereby paving the way to clinical translation.

Computational modeling of multi-track multi-layer laser directed energy deposition process

This study presents the development of a 3D fully coupled thermomechanical finite element model to evaluate the melt pool geometry, defects, and micro-hardness of multi-track multi-layer deposition in the powder feed laser-directed energy deposition (LDED) technique. Fabrication strategies can significantly affect the melt pool geometry and material behavior of the manufactured components. Understanding the effect of process parameters in a multi-track multi-layer LDED is important. Optimal process parameters are crucial for achieving high-quality deposition in terms of deposition geometry and integrity. The model can aid in mitigating issues such as inadequate inter-track or track-substrate fusion, porosity, cracks, and other defects. A multi-track multi-layer finite element model (FEM) can realistically predict melt pool evolution, mechanical properties, and defects in laser-LDED. This work focuses on the development of a fully coupled thermomechanical model for multi-track multi-layer deposition processes using ABAQUS®. The finite element framework employs Johnson-Cook’s flow stress model for constitutive behavior and the Koistein-Marburger equation for predicting hardness. Two tracks and two layers of SS316L powder are deposited on an SS304 substrate in finite element simulations and experiments. The model has been validated for the melt-pool depth in the substrate, deposition geometry, heat-affected zone, and hardness. It has been observed that there is a ∼10 % error in the prediction of melt pool geometry characterization and a ∼12 % error in hardness as compared to experimental results. The melt-pool width, depth, substrate dilution, and hardness have been characterized as a function of process parameters via simulations and experiments. The model is capable of predicting inter-track and interface defects. In addition, the effect of interlayer cooling on the melt-pool geometry and hardness has been studied.

Structural risks and family adjustment in midwestern Latine immigrant families: Extending the family stress model.

We tested an extended family stress model of economic hardship (FSM; Conger et al., 2010) incorporating structural risks (discrimination, immigration, and COVID-19 experiences) and qualitative data, to better understand the impact of culturally relevant experiences on family stress processes in rural, immigrant Latine families in the U.S. Midwest. Participants were Latine families (N = 307) with a child aged 10-15 (Mage = 12.21 years, 51.0% boys; 71.5% two parent; 93.1% of caregivers and 29% of youth born outside the United States) Mean household income was 25-30K and 65% of caregivers had less than a high school education. We tested a cross-sectional structural equation model in Mplus and analyzed qualitative interviews with a subsample of mother-youth dyads (n = 19). COVID-19 experiences predicted economic pressure, and both COVID-19 and discrimination experiences were linked to caregiver psychological distress. Consistent with the FSM, economic pressure predicted psychological distress, which was associated with interparental relationship problems and parenting. Parenting was associated with youth global health. Unexpectedly, interparental relationship problems to parenting were not significant. The indirect association linking COVID-19 experiences to youth global health via psychological distress and parenting was significant. Qualitative data revealed five themes demonstrating how structural and economic risks contributed to distress, conflict, and maladjustment within the family system. Culturally relevant structural risks exert a negative influence on family processes in rural Latine immigrant families through contributing to economic pressures and parental distress. The additional impact of these experiences should be considered when addressing the FSM in Latine populations. (PsycInfo Database Record (c) 2024 APA, all rights reserved).