Synergistic Effects Of Stress Research Articles

Impact of multi-factor coupling on the corrosion behavior of 254SMo stainless steel in an aggressive oilfield environment containing CO2 and H2S

The passivity and corrosion behavior of 254SMo stainless steel in aggressive oilfield environments containing both carbon dioxide (CO2) and hydrogen sulfide (H2S) were investigated using weight-loss and surface analyses. The results indicated that the corrosion rate increased with the increase in temperature, CO2/H2S partial pressures, tensile stress and flow rate. Compressive stress led to a reduction in sulfide compound contents and promoted the formation of protective oxide films, while tensile stress had an opposite effect. Furthermore, a synergistic effect of stress and flow was observed.

Relationships between psychosocial stress, cerebrospinal fluid markers of Alzheimer’s disease, and cognitive function in middle‐aged and older adults

AbstractBackgroundExposure to psychosocial stress empirically associates with risk of cognitive impairment and dementia. Plausible mechanisms include (I) direct influence on AD pathology, and (II) indirect influence through cognitive reserve processes. Current evidence for modifiable determinants of amyloid and tau deposition is mixed, and stress has rarely been studied in this context. In richly characterized cognitive aging samples, we explored preliminary associations between (i) stress measures and amyloid (A), tau (T) and neurodegeneration (N) biomarkers in cerebrospinal fluid (CSF), and (ii) synergistic effects of stress and ATN in cognition.MethodParticipants were enrolled in the Wisconsin Registry for Alzheimer’s Prevention (WRAP) or Wisconsin Alzheimer’s Disease Research Center (ADRC), were cognitively intact, had stress and cognition data from at least one timepoint, and had available CSF data assayed using the NeuroToolKit panel of robust prototype assays (Roche Diagnostics International Ltd). Predictors included Perceived Stress T‐scores from the NIH Toolbox Emotion Battery, and self‐reported recent (past‐year) stressors. ATN outcomes included CSF measures of amyloid positivity, tau positivity, and neurofilament light protein (NfL). Cognitive outcomes included performance in domains of (a) processing speed and mental flexibility and (b) episodic memory. Multivariable regression models assessed cross‐sectional predictor‐outcome relationships.ResultCharacteristics of the predominantly white, middle‐aged and older samples are in Table 1. Stress scores associated with poorer performance on tests of speed and mental flexibility but not memory. There were no significant associations between measures of stress and any AD biomarker (Table 2). Estimate precision was limited by sample sizes, but there were observable interactions between stress measures and tau positivity and NfL, specifically in domains of speed and flexibility (Table 3; eg Figure 1); higher stress predicted poorer performance in the presence of accumulated pathology.ConclusionThere was no evidence for direct relationships between stress exposure and ATN pathology. However, the presence of elevated AD biomarkers exacerbated cognitive detriment associated with psychosocial stress, particularly in a key domain of executive function. Our findings must be replicated in a larger and more diverse sample. However, this study provides preliminary evidence suggesting high stress may act on dementia risk indirectly, through reduced resilience to pathological changes in the brain.

Quantitative study of the corrosion evolution and stress corrosion cracking of high strength aluminum alloys in solution and thin electrolyte layer containing Cl-

Stress corrosion cracking (SCC) behavior of 2024-T351 and 7075-T651 in solution and thin electrolyte layer (TEL) are investigated by electrochemical and mechanical testing, surface observation, and hydrogen detection. Corrosion in TEL is more severe than that in solution as indicated by the higher corrosion coverage fraction, deeper corrosion attacks, serious local exfoliation, and higher hydrogen uptake content. SCC susceptibility of 2024-T351 in TEL is higher than that in solution, while the 7075-T651 is the opposite. Corrosion-induced hydrogen dominates the degradation in TEL environment, while the synergistic effect of stress, corrosion, and hydrogen controls the elongation loss in solution.

Effect of residual and external stress on corrosion behaviour of X80 pipeline steel in sulphate-reducing bacteria environment

Abstract X80 pipeline steel has a wide application prospect. This steel is easily affected by sulphate-reducing bacteria (SRB) in neutral soil and causes stress-corrosion cracking. Based on the results of static and dynamic electrochemical tests, the corrosion behaviour and mechanism of X80 pipeline steel under the synergistic effect of stress and SRB in Shenyang soil environment were investigated through slow strain rate testing, electrochemical impedance spectroscopy, potentiodynamic polarisation technique and surface analysis techniques. Results showed that internal residual and external tensile stress accelerate the corrosion of X80 steel, and the effect of SRB is influenced by the stress type. When only residual stress is applied, the SRB adsorption film plays a certain protective role, which reduces the corrosion sensitivity of X80 steel, and its corrosion mechanism is the anode dissolution of the film rupture. When tensile stress is applied, stress and SRB play a role in the stress concentration at the crack tip, thereby increasing the corrosion sensitivity of X80 steel. The corrosion mechanism is then the activated anode dissolution.

In-Situ Electrochemical Corrosion Behavior of Nickel-Base 718 Alloy Under Various CO2 Partial Pressures at 150 and 205 °C in NaCl Solution

The electrochemical corrosion behavior of nickel-base alloy 718 was investigated using electrochemical impedance spectroscopy and potentiodynamic polarization techniques at various partial pressures of CO2 ( $$P_{{{\text{CO}}_{2} }}$$ s) in a 25 wt% NaCl solution at 150 and 205 °C. The passive films composed of FeCO3 exhibit good corrosion resistance with a feature of Warburg impedance, Tafel plots show a complete passivation and the anodic reactions was dominated by a diffusion process at low $$P_{{{\text{CO}}_{2} }}$$ s (1.8–9.8 MPa) at 150 °C. While numerous dented corrosion areas appeared on the sample surface for the $$P_{{{\text{CO}}_{2} }}$$ of 11.6 MPa at 205 °C, the Tafel plot with three anodic peaks and the Nyquist diagram with an atrophied impedance arc were present. This dented corrosion attribute to the synergistic effects of stress, temperature, $$P_{{{\text{CO}}_{2} }}$$ and Cl−, the temperature and stress could play crucial roles on the corrosion of the alloy 718.

Synergistic effect of stress and crevice on the corrosion of N80 carbon steel in the CO2-saturated NaCl solution containing acetic acid

The corrosion behaviour of N80 carbon steel under the coexistence of stress and crevice in the CO2-saturated NaCl solution containing acetic acid (HAc) was studied by electrochemical measurements, surface analysis, and stress analysis. It is demonstrated that the corrosion potential of steel shifts negatively and corrosion activity is enhanced with increasing stress. A deep corrosion groove is formed at crevice mouth, which causes stress concentration, increasing the susceptibility to stress corrosion cracking (SCC). The stress concentration also results in larger driving force for crevice corrosion. Therefore, there is a synergistic effect of stress and crevice on the corrosion of steel.

Effects of H2S/HS− on Stress Corrosion Cracking Behavior of X100 Pipeline Steel Under Simulated Sulfate-Reducing Bacteria Metabolite Conditions

The effect of H2S/HS−, which simulates the main metabolites of sulfate-reducing bacteria (SRB), on the electrochemical and stress corrosion cracking (SCC) behaviors of X100 steel was investigated in a near-neutral solution. The results showed that different H2S/HS− contents mainly affected the cathodic process of X100 electrochemical corrosion. As the concentration of H2S/HS− increased, the corrosion potential was shifted negatively, the corrosion current density was considerably increased, and the corrosion rate was linearly increased. Different rust layers with shifting structures were formed under different conditions and had different effects on electrochemical behaviors. However, sulfide mainly promoted local corrosion processes. With the synergistic effects of stress and H2S/HS−, SCC susceptibility was considerably enhanced. The accelerated process of hydrogen evolution by sulfide was crucial in enhancing SCC processes. In brief, the trace H2S/HS− generated by SRB metabolites played a positive role in promoting SCC.

Hypothermia and renal tubular vacuolisation revisited

Aim To use a rodent model to evaluate the association between basal vacuolisation and hypothermia. Methods An established model with anaesthetised, minimally-stressed Sprague-Dawley rats was used. Twenty-eight rats were given free access to food, water, and social interaction to reduce psychological and physiological stress. They were then sequentially anaesthetised and placed into a cooling chamber with continuous monitoring of core body temperature. This study was fully approved by the Animal Ethics Committee at The University of Adelaide. Results Core temperatures decreased to a minimum of 7–10 °C which resulted in death of the animals under anaesthesia at times ranging from 120–240 mins. There was no evidence of basal vacuolisation in any of the renal tubular epithelial cells. Discussion The diagnosis of hypothermia at autopsy is often difficult as it relies on a series of variable features such as skin discolouration and gastric erosions. Basal lipid vacuolisation in renal epithelial cells has recently been proposed as another diagnostic marker. This study suggests that basal renal tubular cell vacuolisation may not be solely caused by lethal hypothermia but may be a manifestation of a more complex pathophysiological pathway involving the synergistic effects of stress.

Synergistic effect of stray current and stress on corrosion of API X65 steel

The effect of stray current and stress on corrosion of API X65 steel in simulated solution of the alkaline soil in Daqing in China was investigated using corrosion potential test, potentiodynamic polarization measurement, as well as surface analysis techniques. A mathematical relationship between corrosion rate and yield strength, direct current (DC) stray current density was obtained by multiple linear regression. The results demonstrate that, the corrosion potential of API X65 steel with and without superimposed DC stray current all shifted negatively, and the corrosion current density increases with the enhancement of tensile stress in solution. The corrosion current density under the synergistic effect of stress and stray current is much higher than corrosion current density that single factor (stress or stray current) induced. Comparing with the stress, the effect of stray current on corrosion rate of API X65 steel is more significant in elastic deformation. Mutation in corrosion potential and corrosion rate appeared when the strain reaches plastic deformation. This work provides reference suggestion for pipeline safety design and operation, where the corrosion enhancement due to the synergistic effect of stray current and stress should be considered.

Effects of hydrogen and surface dislocation on active dissolution of deformed 304 austenitic stainless steel in acid chloride solution

The mechanochemical effects between dissolved hydrogen and deformation on active dissolution of 304 stainless steel in acid chloride solution were investigated by use of constant loading test method. A theoretical model was proposed in terms of the stored strain energy and electron work function. Results indicated that active dissolution was affected mainly by Gibbs free energy produced by the part of plastic deformation and surface dislocation structure. A good agreement between the prediction and test results revealed that the synergistic effect of stress and dissolved hydrogen only promoted the process of active dissolution.

A framework for examining social stress and susceptibility to air pollution in respiratory health

There is growing interest in disentangling the health effects of spatially clustered social and physical environmental exposures and in exploring potential synergies among them, with particular attention directed to the combined effects of psychosocial stress and air pollution. Both exposures may be elevated in lower-income urban communities, and it has been hypothesized that stress, which can influence immune function and susceptibility, may potentiate the effects of air pollution in respiratory disease onset and exacerbation. In this paper, we review the existing epidemiologic and toxicologic evidence on synergistic effects of stress and pollution, and describe the physiologic effects of stress and key issues related to measuring and evaluating stress as it relates to physical environmental exposures and susceptibility. Finally, we identify some of the major methodologic challenges ahead as we work toward disentangling the health effects of clustered social and physical exposures and accurately describing the interplay among these exposures. As this research proceeds, we recommend careful attention to the relative temporalities of stress and pollution exposures, to nonlinearities in their independent and combined effects, to physiologic pathways not elucidated by epidemiologic methods, and to the relative spatial distributions of social and physical exposures at multiple geographic scales.

Stress Corrosion Cracking of High Strength Steel Fasteners for Space Applications

Cadmium electrodeposited Afnor 35NCD16 steel fasteners in hardened and tempered condition are used in the Indian space program. Failures were observed in size M6X17L fasteners that were under assembly load for a period of four months in an integrated test set up which involved exposure to severe humid environments. During disassembly, few of the fasteners were found to be broken at head–shank junction. Detailed metallurgical investigations carried out on failed fasteners and those, which were in assembly but did not fail, revealed their failure was caused by the synergistic effects of stress and corrosion. An attempt is made in this case history to correlate the metallurgical features collected with the failure mode of the fasteners.

A framework for examining social stress and susceptibility to air pollution in respiratory health.

ObjectiveThere is growing interest in disentangling the health effects of spatially clustered social and physical environmental exposures and in exploring potential synergies among them, with particular attention directed to the combined effects of psychosocial stress and air pollution. Both exposures may be elevated in lower-income urban communities, and it has been hypothesized that stress, which can influence immune function and susceptibility, may potentiate the effects of air pollution in respiratory disease onset and exacerbation. In this paper, we attempt to synthesize the relevant research from social and environmental epidemiology, toxicology, immunology, and exposure assessment to provide a useful framework for environmental health researchers aiming to investigate the health effects of environmental pollution in combination with social or psychological factors.Data synthesisWe review the existing epidemiologic and toxicologic evidence on synergistic effects of stress and pollution, and then describe the physiologic effects of stress and key issues related to measuring and evaluating stress as it relates to physical environmental exposures and susceptibility. Finally, we identify some of the major methodologic challenges ahead as we work toward disentangling the health effects of clustered social and physical exposures and accurately describing the interplay among these exposures.ConclusionsThere is still tremendous work to be done toward understanding the combined and potentially synergistic health effects of stress and pollution. As this research proceeds, we recommend careful attention to the relative temporalities of stress and pollution exposures, to nonlinearities in their independent and combined effects, to physiologic pathways not elucidated by epidemiologic methods, and to the relative spatial distributions of social and physical exposures at multiple geographic scales.

Mental Depression and Cardiovascular Disease: A Multifaceted, Bidirectional Association

The association between cardiovascular disease and mental depression is multifaceted and likely bidirectional. Depressed patients are at significantly higher risk for cardiac morbidity and mortality even in the absence of a diagnosis of major depression, whereas mental depression is nearly 3 times more frequent in patients after an acute myocardial infarction and contributes to a worse prognosis. Therefore, depressed patients might become trapped in a harmful loop, where mental symptoms might be worsened by the synergistic effects of stress and cardiovascular risk factors, and where they are otherwise vulnerable to acute cardiovascular events due to the synergistic effects of mental stress and an underlying atherothrombotic disorder. Although the exact pathway(s) underlying the interplay between depression and cardiovascular disease remains to be elucidated, the mechanisms most often implicated include hormonal variations, metabolic abnormalities, hypercoagulability, increased platelet aggregation, inflammation, and endothelial dysfunction. This article aims to review the biological and clinical links between depression and cardiovascular disease.

Synergistic effects of stress and omega-3 fatty acid deprivation on emotional response and brain lipid composition in adult rats

The aim was to determine the consequences of multi-generational n-3 polyunsaturated fatty acids (PUFA) deficiency on emotional response in rats subjected to maternal separation (MS) as chronic early life stress. Pups fed a control or an n-3 PUFA deficient diet were daily separated for 2 weeks before weaning. In adult rats, reward response was assessed by sucrose consumption and reactivity to novelty using openfield test. Both n-3 PUFA deficiency and MS increased reward response and impulsivity. Moreover, nutritional deficiency and stress acted in synergy to elevate sucrose intake by 80%, compared to control conditions. n-3 PUFA deprivation induced a depletion of docosahexanoeic acid of brain membranes by 70% compensated by increase in 22:5 n-6 and arachidonic acid (AA) levels. The diet-induced AA increase was, however, significantly higher in MS rats. This suggests that n-3 PUFA deficit could be an environmental risk increasing vulnerability to depressive-like response induced by chronic stress.

Recipe for High Blood Pressure: Synergistic Effects of Stress and Lead

Human research has shown associations between lead exposure and hypertension as well as between stress and hypertension. A new study now shows for the first time that stress amplifies the effects of lead exposure on blood pressure in humans [EHP 115:1154–1159; Peters et al.]. National Heart, Lung, and Blood Institute guidelines define high blood pressure as systolic pressure over 140 mmHg or diastolic pressure over 80 mmHg. Systolic pressure tends to rise with age whereas diastolic pressure tends to decline. High readings of either type significantly raise the risk of stroke and coronary disease. A multi-institutional team examined data from 513 participants in the Normative Aging Study, a longitudinal study of men in the greater Boston area begun in 1963. Using data from the period 1987–1996, the researchers compared blood pressure status with self-reported stress levels (determined by questionnaires) and body burden of lead (determined by bone lead tests). About half the participants did not have hypertension; for this group the researchers analyzed follow-up data until 2004 or the participants developed hypertension, whichever came first. In the latter group, 97 new cases of hypertension were observed. The study participants averaged 66.9 years of age. This put them in the age group most likely to have high systolic pressure, and meant they were old enough to have been exposed to significant amounts of lead before public policy changes in the 1970s reduced environmental lead from gasoline, paint, and other sources. After accounting for other known hypertension risk factors, including age, body mass index, family history, and alcohol consumption, the researchers found that the effect of lead was “most pronounced among highly stressed individuals, independent of demographic and behavioral risk factors.” Among those reporting high stress, the risk of developing hypertension was more than 2.5 times that of participants reporting low stress for each standard deviation increase in bone lead. The current study was consistent with previous research suggesting that lead and stress affect only systolic pressure. The authors note that their study does not address lead’s potential effects at various life stages. For example, early exposure leading to neurological damage might make people more likely to experience events as stressful. In addition, the study was limited in that participants were all male, were 97% white, and had higher than median incomes. Given that both lead exposure and stress tend to be elevated in lower socioeconomic strata, their effects on blood pressure may be more serious in those populations.

Durability of Composite Reinforcement for Timber Bridges

Fiber-reinforced polymeric (FRP) composites are materials that are increasing in use in civil engineering applications. Despite the excellent mechanical properties and corrosion resistance offered by these organic matrix materials, their susceptibility to the synergistic effects of stress and environmental weathering hinders their widespread acceptance in civil engineering. The durability of a specific formulation of wood-compatible, pultruded, E-glass–phenolic composite is characterized. This composite is unique because its layered structure and void content make it compatible with standard structural wood adhesives. The durability of this wood-compatible FRP reinforcement cannot be directly determined from published work on the durability of E-glass composites because of its unique design. A durability test matrix was generated according to specifications and test standards from the International Conference of Building Officials Evaluation Service, Inc., and from the California Department of Transportation. Physical and mechanical properties that were used as indicators of degradation mechanisms and that applied to the bridge environment included tensile behavior, interlaminar shear strength, void content, and glass-transition temperature. Environmental testing involved exposure to various storage media, such as moisture, saline solutions, and calcium carbonate, followed by mechanical testing. Other exposure treatments included dry heat, cyclic freeze-thaw, accelerated weathering, and natural weathering. In addition to the strength-retention determination after environmental conditioning, control and exposed specimens were examined visually with optical and scanning electron microscopy to determine surface changes and their effect on failure and fracture modes.