Search results for: Nrf2 oxidative stress

Authors: Shilu Deepa Thomas, P. Jayaprakash, Dorota Łazewska, Katarzyna Kieć-Kononowicz, B. Sadek

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A large body of evidence suggests the involvement of cognitive impairment, increased levels of inflammation and oxidative stress in the pathogenesis of autism spectrum disorder (ASD). ASD commonly coexists with psychiatric conditions like anxiety and cognitive challenges, and individuals with ASD exhibit significant levels of inflammation and immune system dysregulation. Previous Studies have identified elevated levels of pro-inflammatory markers such as IL-1β, IL-6, IL-2 and TNF-α, particularly in young children with ASD. The current therapeutic options for ASD show limited effectiveness, signifying the importance of exploring an efficient drugs to address the core symptoms. The role of histamine H3 receptors (H3Rs) in memory and the prospective role of H3R antagonists in pharmacological control of neurodegenerative disorders, e.g., ASD, is well-accepted. Hence, the effects of chronic systemic administration of H3R antagonist E159 on autistic-like repetitive behaviors, social deficits, memory and anxiety parameters, as well as neuroinflammation in Black and Tan BRachyury (BTBR) mice, were evaluated using Y maze, Barnes maze, self-grooming, open field and three chamber social test. E159 (2.5, 5 and 10 mg/kg, i.p.) dose-dependently ameliorated repetitive and compulsive behaviors by reducing the increased time spent in self-grooming and improved reduced spontaneous alternation in BTBR mice. Moreover, treatment with E159 attenuated disturbed anxiety levels and social deficits in tested male BTBR mice. Furthermore, E159 attenuated oxidative stress by significantly increasing GSH, CAT, and SOD and decreasing the increased levels of MDA in the cerebellum as well as the hippocampus. In addition, E159 decreased the elevated levels of proinflammatory cytokines (tumor necrosis factor (TNF-α), interleukin-1β (IL-1β), and IL-6). The observed results show that H3R antagonists like E159 may represent a promising novel pharmacological strategy for the future treatment of ASD.

Keywords: histamine H3 receptors, antagonist E159, autism, behaviors, mice

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Authors: Nitin Joseph

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Objectives: This study was done to assess emotional intelligence levels and to find out its association with socio demographic variables and perceived stress among medical students. Material and Methods: This study was done among first and second year medical students. Data was collected using a self-administered questionnaire. Results: Emotional intelligence scores was found to significantly increase with age of the participants (F=2.377, P < 0.05). Perceived stress was found to be significantly more among first year (t=1.997, P=0.05). Perceived stress was found to significantly decrease with increasing emotional intelligence scores (r = – 0.226, P < 0.001). Conclusion: First year students were found to be more vulnerable to stress than their seniors probably due to lesser emotional intelligence. As both these parameters are related, ample measures to improve emotional intelligence needs to be supported in the training curriculum of beginners so as to make them more stress free during early student life.

Keywords: emotional intelligence, medical students, perceived stress, socio demographic variables

Procedia PDF Downloads 426

Authors: Amina Unis, Samah S. El Basateeny, Noha A. H. Nassef

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Introduction: Acute Renal Failure (ARF) is one of the most common problems encountered in hospitalized critically ill patients. In recent years great effort has been focused on the introduction of herbal medicine as a novel therapeutic agent for prevention of ARF. Hence, the current study was designed to investigate the effect of Green Coffee Bean Extract (GCBE) on gentamicin induced ARF in rats. Methods: The study was conducted on 60 male rats divided into six equal groups. Group 1 served as normal control group and GCBE was administered for 7 days at a dose of 20 mg/kg/day in group 2 and 40 mg/kg/day in group 3 to test the effect of GCBE on normal kidneys. ARF was induced by a daily intraperitoneal injection of gentamicin (80 mg/kg) for 7 days in group 4 (model group), group 5 (GCBE 20 mg/kg/day) and group 6 (GCBE 20 mg/kg/day). All rats were sacrificed after 7 days and blood was withdrawn for kidney function tests. Kidneys were removed for determination of renal oxidative stress markers and histopathological examination. Results: The present study showed that rats that received oral GCBE for 7 days without induction of ARF showed no significant change in all the assessed parameters in comparison to the normal control group, while rats in the groups that received oral GCBE for 7 days with induction of ARF showed a significant improvement in kidney functions tests (decrease in serum urea, serum creatinine, and blood urea nitrogen) when compared to the ARF model group. Moreover, there was significant amelioration in renal oxidative stress markers (renal malondialdehyde, renal superoxide dismutase) and renal histopathological changes in the GCBE treated groups along induction of ARF when compared to ARF model group. The most significant improvement was reported in the group where GCBE was administered for 7 days in a dose 40 mg/kg/day, along with induction of ARF. Conclusion: GCBE has a potential role in ameliorating renal damage involved in ARF mostly through its antioxidant effect.

Keywords: green coffee bean extract, gentamicin, acute renal failure, pharmacology

Procedia PDF Downloads 268

Authors: Amina Aloui, Jalila Ben Salah-Abbès, Abdellah Zinedine, Amar Riba, Noel Durand, Catherine Brabet, Didier Montet, Samir Abbès

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Mycotoxin contamination of food and feed-isa globaconcern, both economically and for public health. Aflatoxin M1 (AFM1) is the principal hydroxylated metabolite of aflatoxin B1. It is frequently found in milk and other dairy products. It is responsible for the development of hepatocellular carcinoma and immunotoxic in humans and animals. The reduction of its bioavailabilitybecomesa great demand in order to protect human and animal health. The use of probiotic bacteria and clay are demonstrated to be able to bind AFM1 in vitro. This study aimed to investigate, in vivo, the activity of two-component mixture: L. rhamnosusGAF06 (LR) and bentonite for reducing the oxidative stress and the histological alterationsinduced by AFM1 in the liver andkidneys. For the experiment, male mice were divided into 7 groups (6 mice/group) and treated, orally, by AFM1, alone or in combination with LR and/or bentonite, for 10 days as follows: group 1 control, group 2 treated with LR alone (2.108 CFU/ml), group 3 treated with bentonite alone (1g/kg), group 4 treated with AFM1 alone (100μg/kg), group 5 co-treated with LR+AFM1, group 6 co-treated with bentonite+AFM1, group 7 co-treated with bentonite+LR+AFM1. At the end of the treatment, the mice were sacrificed, and the livers and kidneys were collected for histological assays. Intracellular antioxidant activities and lipid peroxidation were also studied. The results showed that AFM1causeddamage in liver and kidney tissues, being evidence of hepatotoxicity and nephrotoxicity marked by necrotic cells. It increased the MDA level and decreased the antioxidant enzyme activities (SOD) in both organs. In contrast, the co-treatment with AFM1 plus LR and/or bentonitesignificantly improved the hepatic and renal tissues, regulated kidney, and liver antioxidant enzyme activities. This improvement was more remarkable with the administration of LR-bentonite mixture with AFM1.LR and bentonite alone showed to be safe during the treatment. This mixture can be a promising candidate for future applications in biotechnological processes that aimed to detoxify AFM1in food and feed.

Keywords: aflatoxin M1, bentonite, L. rhamnosus GAF06, oxidative stress, prevention

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Authors: Lídia Chienda, Tchilissila A. Simoes

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Angola is known for the low quality of maternal health services, registering one of the highest maternal and child mortality of Africa. Working in these health facilities may be of great challenge for health professionals. In this study, we aimed to identify the presence of occupational stress in 76 nurses working in a maternity ward in Lubango, Southern Angola. The participants completed the Health Professional Stress Questionnaire and reported a moderate and high level of stress. To these individuals, 'receiving a low salary,' 'inadequate/insufficient salary,' 'overwork or very demanding work' and 'working long hours in a row' seemed to be the main indicators of occupational stress. Moreover, there was an influence of the work overload, the remuneration earned, the career, and family conflicts in the occupational stress index. These results contributed to a better understanding of the difficulties Angolan nurses are facing and the need to implement policies that envisage the wellbeing of this population.

Keywords: Africa, maternity wards, nursing, occupational stress

Procedia PDF Downloads 158

Authors: Rami Al-Sadi

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The assignment of lexical stress in English to its correct syllable is an enormous challenge to EFL learners, especially if their first language (L1) phonology is very different from English phonology. Arabic-speaking EFL learners not only stumble very frequently when it comes to placing the lexical stress in a given word, but they also seem to relegate the role of lexical stress as unimportant, mainly because in Arabic, unlike in English, lexical stress is not phonemic. This study aims at exploring the possible benefits of utilizing spectrographic representations of English words correctly pronounced, for the purpose of finding out how these spectrograms can provide a visual aid to the learners and help them rectify their stress placement errors as they see in real time spectrograms of the correct pronunciations juxtaposed on a computer screen with spectrograms of their own pronunciations for easy comparison. The study involved 120 students from the English Department at Prince Sattam bin Abdulaziz University in Saudi Arabia. 60 participants were taught the English lexical stress rules and also received spectrographic guidance on pronunciation; the other 60 received only verbal instruction on the stress rules and verbal feedback on their pronunciations. Statistical results showed that when the learners had the opportunity to ‘see’ their pronunciation mistakes, they were three times more likely to rectify their placement of lexical stress.

Keywords: Arabic-speaking EFL learners, lexical stress, pronunciation, spectrographic representation, stress placement

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Authors: Ibrahim Ajani Tijani, C. W. Lim

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Limited studies have examined the effect of size on the mechanical behavior of confined concrete subjected to 3-dimensional (3D) test. With the novel 3D testing system to produce passive confinement, concrete cubes were tested to examine the effect of size on stress-strain behavior of the specimens. The effect of size on 3D stress-strain relationship was scrutinized and compared to the stress-strain relationship available in the literature. It was observed that the ultimate stress and the corresponding strain was related to the confining rigidity and size. The size shows a significant effect on the intersection stress and a new model was proposed for the intersection stress based on the conceptual design of the confining plates.

Keywords: concrete, aggregate size, size effect, 3D compression, passive confinement

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Authors: Parveen K. Saini, Tarun Agarwal

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An investigation into the effect of countersunk depth, plate thickness, countersunk angle and plate width on the stress concentration around countersunk hole is carried out with the help of finite element analysis. The variation of stress concentration with respect to these parameters is studied for three types of loading viz. uniformly distributed load, uniformly varying load and functionally distributed load. The results of the finite element analysis are interpreted and some conclusions are drawn. The distribution of stress concentration around countersunk hole in isotropic plates simply supported at all the edges is found similar and is independent of loading. The maximum stress concentration also occurs at a particular point irrespective of the loading conditions.

Keywords: stress concentration factor, countersunk hole, finite element, ANSYS

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Authors: Yasmina Bendaali, Cristian Vaquero, Carlos Escott, Carmen González, Antonio Morata

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Consumer tendencies to healthy eating habits and request for organic beverages led to the production of new drinks from fruit juices as a source of nutrients and bioactive compounds. Grape juice is a rich source of sugars, organic acids, and phenolic compounds, which define its beneficial effect on health and the attractive sensory profile for consumers' choices (color, taste, flavor). Thus, grape juice was used as a source of sugars, avoiding the addition of sweeteners by diluting it with mineral water to obtain the sugar concentration recommended for isotonic drinks (6% to 8%) to provide energy during physical activities. In addition, phenolic compounds of grape juice are associated with many human health benefits, mainly antioxidant activity, which helps to prevent different diseases associated with oxidative stress, including cancers and cardiovascular and neurodegenerative diseases. Furthermore, physical exercise has been shown to increase the production of free radicals and other reactive oxygen species. Thus, athletes need to improve their antioxidant defense systems to prevent oxidative damage. Different studies have demonstrated the positive effect of grape juice consumption during physical activities, which improves antioxidant activity and performance, protects against oxidative damage, and reduces inflammation. Thus, the use of grape juice to develop isotonic drinks can provide isotonic drinks with antioxidant and biological activities in addition to their principal role of rehydration and replacement of minerals and carbohydrates during physical exercises. Moreover, attractive sensory characteristics, mainly color, which is provided by anthocyanin content, have a great contribution to making the drinks more natural and help to dispense the use of synthetic dyes in addition to the health benefits which will be a novel product in the field of healthy beverages responding on the demand of consumers for new, innovative, and healthy products.

Keywords: grape juice, isotonic, antioxidants, anthocyanins, natural, sport

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Authors: Mohammad Vahedi Torshizi

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In this investigation, at first, bending stress, contact stress, Safety factor of bending and Safety factor of contact between sun gear and planet gear tooth was determined using mathematical equations. Also, The amount of Sun Revolution in, Speed carrier, power Transmitted of the sun, sun torque, sun peripheral speed, Enter the tangential force gears, was calculated using mathematical equations. According to the obtained results, maximum of bending stress and contact stress occurred in three plantary and low status of four plantary. Also, maximum of Speed carrier, sun peripheral speed, Safety factor of bending and Safety factor of contact obtained in four plantary and maximum of power Transmitted of the sun, Enter the tangential force gears, bending stress and contact stress was in three pantry and factors And other factors were equal in the two planets.

Keywords: bending stress, contact stress, plantary, mathematical equations

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Authors: Onwumere O. J.

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The teaching of stress at any level of education could be a daunting task for the second language teacher because most times, they are bereft of the right approach to use in teaching it even at the fact is that, teaching it. But the fact is that teaching stress even at the middle basic could be interesting if the right approach is employed. To this end, the researcher was of the view that grouping could be a very good strategy to employ in order to sustain the interest of the learner and that the use at drums would be a good way to concretise the teaching of stress at this level. He was able to do this by discussing stress, grouping as a good technique, and the use of drums in teaching stress. To establish the fact that the use of drums would be very effective, four research questions contained in a questionnaire were structured. Three hundred (300) teachers of English in four tertiary institutions, three secondary schools and three primary schools in Nigeria were used. Based on the data analysis and findings, suggestions were given on how teachers and learners could use drums to make the teaching and learning of stress enjoyable for both teachers and learners at the middle basic of education.

Keywords: concretise, grouping, right approach, second language

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Authors: Lintle Mohase, Ninikoe Lebusa, Mpho Stephen Mafa

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Wheat is an economically important cereal crop. However, the changing climatic conditions that intensify drought in production areas, and additional pest infestation, such as the Russian wheat aphid (RWA, Diuraphis noxia), severely hamper its production. Drought and pest management require an additional water supply through irrigation and applying inorganic nutrients (including silicon) as alternative strategies to mitigate the stress effects. Therefore, other approaches are needed to enhance wheat productivity during drought stress and aphid abundance. Two wheat cultivars were raised under greenhouse conditions, exposed to drought stress, and treated with silicon before infestation with the South African RWA biotype 2 (RWASA2). The morphological evaluations showed that severe drought or a combination of drought and infestation significantly reduced the plant height of wheat cultivars. Silicon treatment did not alleviate the growth reduction. The biochemical responses were measured using spectrophotometric assays with specific substrates. An evaluation of the enzyme activities associated with oxidative stress and defence responses indicated that drought stress increased NADPH oxidase activity, while silicon treatment significantly reduced it in drought-stressed and infested plants. At 48 and 72 hours sampling periods, a combination of silicon, drought and infestation treatment significantly increased peroxidase activity compared to drought and infestation treatment. The treatment also increased β-1,3-glucanase activity 72 hours after infestation. In addition, silicon and drought treatment increased glucose but reduced sucrose accumulation. Furthermore, silicon, drought, and infestation treatment combinations reduced the sucrose content. Finally, silicon significantly increased the trehalose content under severe drought and infestation, evident at 48 and 72-hour sampling periods. Our findings shed light on silicon’s ability to induce protective biochemical responses during drought and aphid infestation.

Keywords: drought, enzyme activity, silicon, soluble sugars, Russian wheat aphid, wheat

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Authors: Rini Rahul, Manoj Kumar

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Cadmium (Cd) is a poisonous trace metal, which is responsible for excess reactive oxygen species generation (ROS) in plants, thereby adversely affecting their productivity and commercial potential. Ricinus communis (castor) is an industry-efficient non-edible bioenergy crop used for phytoremediation and re-vegetation. We have determined the total Cd content in castor genotypes and established a relationship between the Cd tolerance mechanism and physiological parameters like chlorophyll fluorescence, the total photosynthetic activity, chlorophyll and carotenoid content as well as ROS generation and malondialdehyde content. This study is an effort to comprehend the interrelation between Cd toxicity (control, 250 µM and 500 µM), proline, various ROS scavenging enzymes (anti-oxidative in nature), nicotianamine synthase (NAS) and Natural resistance-associated macrophage protein (NRAMP) gene. The antioxidant enzyme activity increased for WM hence conferring Cd toxicity in this genotype. RcNRAMP genes showed differential expression in GCH2 and WM genotypes; this can also be one of the reasons for Cd toxicity and sensitivity in WM and GCH2, respectively. The cause of pronounced Cd tolerance in WM leaves can be because of enhanced expression of RcNAS1, RcNAS2 and RcNAS3 genes. Our results demonstrate that there is an interrelation between Cd toxicity (control, 250 µM and 500 µM), proline, various ROS scavenging enzymes (anti-oxidative in nature), NAS and NRAMP gene.

Keywords: ricinus communis, cadmium, reactive oxygen species, nicotianamine synthase, NRAMP, malondialdehyde

Procedia PDF Downloads 43

Authors: Rafik Baouche, Rabah Chaouchi

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This work reports the first comprehensive stress field interpretation from the eleven recently drilled wells in the Berkaoui Basin, Algerian Sahara. A cumulative length of 7000+m acoustic image logs from 06 vertical wells were investigated, and a mean NW-SE (128°-145° N) maximum horizontal stress (SHMax) orientation is inferred from the B-D quality wellbore breakouts. The study integrates log-based approach with the downhole measurements to infer pore pressure, in-situ stress magnitudes. Vertical stress (Sv), interpreted from the bulk-density profiles, has an average gradient of 22.36 MPa/km. The Ordovician and Cambrian reservoirs have a pore pressure gradient of 13.47-13.77 MPa/km, which is more than the hydrostatic pressure regime. A 17.2-18.3 MPa/km gradient of minimum horizontal stress (Shmin) is inferred from the fracture closure pressure in the reservoirs. Breakout widths constrained the SHMax magnitude in the 23.8-26.5 MPa/km range. Subsurface stress distribution in the central Saharan Algeria indicates that the present-day stress field in the Berkaoui Basin is principally strike-slip faulting (SHMax > Sv > Shmin). Inferences are drawn on the regional stress pattern and drilling and reservoir development.

Keywords: stress, imagery, breakouts, sahara

Procedia PDF Downloads 46

Authors: Tejeet Singh, Ishavneet Singh

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The present study focused on carrying out the creep analysis in an isotropic thick-walled composite cylindrical pressure vessel composed of aluminum matrix reinforced with silicon-carbide in particulate form. The creep behavior of the composite material has been described by the threshold stress based creep law. The values of stress exponent appearing in the creep law were selected as 3, 5 and 8. The constitutive equations were developed using well known von-Mises yield criteria. Models were developed to find out the distributions of creep stress and strain rate in thick-walled composite cylindrical pressure vessels under internal pressure. In order to obtain the stress distributions in the cylinder, the equilibrium equation of the continuum mechanics and the constitutive equations are solved together. It was observed that the radial stress, tangential stress and axial stress increases along with the radial distance. The cross-over was also obtained almost at the middle region of cylindrical vessel for tangential and axial stress for different values of stress exponent. The strain rates were also decreasing in nature along the entire radius.

Keywords: steady state creep, composite, cylinder, pressure

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Authors: Priyakant Vaghela, Jagdish Prajapati

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Bending stress at the root of the gear tooth is the very important criteria in gear design and it should be kept the minimum. Minimization of bending stress at the root of the gear tooth is a recent demand from industry. This paper presents an innovative approach to obtain minimum bending stress at the root of a tooth by optimizing tooth root profile and drive side pressure angle. Circular-filleted at the root of the tooth is widely used in the design. Circular fillet creates discontinuity at the root of the tooth. So, at root stress concentration occurs. In order to minimize stress concentration, an important criterion is a G2 continuity at the blending of the gear tooth. A Bezier curve is used with G2 continuity at the root of asymmetric spur gear tooth. The comparison has been done between normal and modified tooth using ANSYS simulation. Tooth root profile and drive side pressure angle are optimized to minimize bending stress at the root of the tooth of the asymmetric involute spur gear. Von Mises stress of optimized profile is analyzed and compared with normal profile symmetric gear. Von Mises stress is reducing by 31.27% by optimization of drive side pressure angle and root profile. Stress concentration of modified gear was significantly reduced.

Keywords: asymmetric spur gear tooth, G2 continuity, pressure angle, stress concentration at the root of tooth, tooth root stress

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Authors: F. Husem, M. E. Turan, Y. Sun, H. Ahlatci, I. Tozlu

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Residual stress and fatigue crack growth rates are important to determine mechanical behavior of rails. This study aims to make relationship between residual stress and fatigue crack growth values in rails. For this purpose, three R260 quality rails (0.6-0.8% C, 0.6-1.25 Mn) were chosen. Residual stress of samples was measured by cutting method that is related in railway standard. Then samples were machined for fatigue crack growth test and analyze was completed according to the ASTM E647 standard which gives information about parameters of rails for this test. Microstructure characterizations were examined by Light Optic Microscope (LOM). The results showed that residual stress change with fatigue crack growth rate. The sample has highest residual stress exhibits highest crack growth rate and pearlitic structure can be seen clearly for all samples by microstructure analyze.

Keywords: residual stress, fatigue crack growth, R260, SEM, ASTM E647

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Authors: Amin Derakhshan, Mohammad Mikaili, Mohammad Ali Khalilzadeh, Amin Mohammadian

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This paper proposes a stress recognition system from multi-modal bio-potential signals. For stress recognition, Support Vector Machines (SVM) and LDA are applied to design the stress classifiers and its characteristics are investigated. Using gathered data under psychological polygraph experiments, the classifiers are trained and tested. The pattern recognition method classifies stressful from non-stressful subjects based on labels which come from polygraph data. The successful classification rate is 96% for 12 subjects. It means that facial thermal imaging due to its non-contact advantage could be a remarkable alternative for psycho-physiological methods.

Keywords: stress, thermal imaging, face, SVM, polygraph

Procedia PDF Downloads 455

Authors: Jeonghun Lee

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Thyroid-stimulating hormone (TSH) is regulated by the negative feedback of T3 and T4 but is affected by cortisol and cytokines during allostasis. Hence, TSH levels can be influenced by stress through cortisol. In the present study, changes in TSH levels under stress and the potential of TSH as a stress marker were examined in patients lacking T3 or T4 feedback after thyroid surgery. The three stress questionnaires (Korean version of the Daily Stress Inventory, Social Readjustment Rating Scale, and Stress Overload Scale-Short [SOSS]), open-ended question (OQ), and thyroid function tests were performed twice in 106 patients enrolled from January 2019 to October 2020. Statistical analysis was performed using the generalized linear mixed effect model (GLMM) in R software version 4.1.0. In a multiple LMM involving 106 patients, T3, T4, SOSS (category), open-ended questions, the extent of thyroidectomy, and preoperative TSH were significantly correlated with lnTSH. T3 and T4 increased by 1 and lnTSH decreased by 0.03, 3.52, respectively. In case of a stressful event on OQ, lnTSH increased by 1.55. In the high-risk group, lnTSH increased by 0.79, compared with the low group (p<0.05). TSH had a significant relationship with stress, together with T3, T4, and the extent of thyroidectomy. As such, it has the potential to be used as a stress marker, though it showed a low correlation with other stress questionnaires. To address this limitation, questionnaires on various social environments and research on copy strategies are necessary for future studies.

Keywords: stress, surgery, thyroid stimulating hormone, thyroidectomy

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Authors: Anurag Niranjan, Michael Fitzpatrick, Yin Jin Janin, Jazeel Chukkan, Niall Smyth

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Fillet welds are used in joining longitudinal stiffeners in ship structures. Welding residual stresses in fillet welds are generally distributed in a non-uniform manner, as shown in previous research the residual stress redistribution occurs under the cyclic loading that is experienced by such joints during service, and the combination of the initial residual stress, local constraints, and loading can alter the stress field in ways that are extremely difficult to predict. As the residual stress influences the crack propagation originating from the toe of the fillet welds, full understanding of the residual stress field and how it evolves is very important for structural integrity calculations. Knowledge of the residual stress redistribution in the presence of a flaw is therefore required for better fatigue life prediction. Moreover, defect assessment procedures such as BS7910 offer very limited guidance for flaw acceptance and the associated residual stress redistribution in the assessment of fillet welds. Therefore the objective of this work is to study a surface-breaking flaw at the weld toe region in a fillet weld under cyclic load, in conjunction with residual stress measurement at pre-defined crack depths. This work will provide details of residual stress redistribution under cyclic load in the presence of a crack. The outcome of this project will inform integrity assessment with respect to the treatment of residual stress in fillet welds. Knowledge of the residual stress evolution for this weld geometry will be greatly beneficial for flaw tolerance assessments (BS 7910, API 591).

Keywords: fillet weld, fatigue, residual stress, structure integrity

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Authors: Terri A. Croteau, Todd G. Morrison

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Despite increased scholarly attention paid to minority stress and sexual satisfaction among sexual minorities, to the authors’ knowledge, no researchers, to date, have attempted to synthesize this literature. To address this omission, the authors conducted a meta-analytic review of the association between sexual minority stress (i.e., sexual identity stigma, internalized sexual identity stigma, and sexual identity concealment) and sexual satisfaction. Twenty-seven articles containing 58 effect sizes were analyzed (N = 183,582). Findings indicated a small, inverse relationship between these constructs, indicating that minority stress may lead to diminished sexual satisfaction among gay/lesbian and bisexual individuals. Further, the overall effect size varied as a function of minority stress type, such that the effect for internalized stigma was significantly larger than the effects for stigma or concealment. Age also moderated the relationship between minority stress and sexual satisfaction; specifically, older age was associated with a smaller effect, suggesting that older adults may be better at coping with minority stress than younger adults. Limitations, implications, and directions for future research are discussed.

Keywords: minority stress, stigma, sexual satisfaction, sexual minorities

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Authors: Vaishali Patil, Neeraj Masand

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In older people, Alzheimer’s disease (AD) is turning out to be a lethal disease. According to the amyloid hypothesis, aggregation of the amyloid β–protein (Aβ), particularly its 42-residue variant (Aβ42), plays direct role in the pathogenesis of AD. Aβ is generated through sequential cleavage of amyloid precursor protein (APP) by β–secretase (BACE) and γ–secretase (GS). Thus in the treatment of AD, γ-secretase modulators (GSMs) are potential disease-modifying as they selectively lower pathogenic Aβ42 levels by shifting the enzyme cleavage sites without inhibiting γ–secretase activity. This possibly avoids known adverse effects observed with complete inhibition of the enzyme complex. Virtual screening, via drug-like ADMET filter, QSAR and molecular docking analyses, has been utilized to identify novel γ–secretase modulators with sulphonamide nucleus. Based on QSAR analyses and docking score, some novel analogs have been synthesized. The results obtained by in silico studies have been validated by performing in vivo analysis. In the first step, behavioral assessment has been carried out using Scopolamine induced amnesia methodology. Later the same series has been evaluated for neuroprotective potential against the oxidative stress induced by Scopolamine. Biochemical estimation was performed to evaluate the changes in biochemical markers of Alzheimer’s disease such as lipid peroxidation (LPO), Glutathione reductase (GSH), and Catalase. The Scopolamine induced amnesia model has shown increased Acetylcholinesterase (AChE) levels and the inhibitory effect of test compounds in the brain AChE levels have been evaluated. In all the studies Donapezil (Dose: 50µg/kg) has been used as reference drug. The reduced AChE activity is shown by compounds 3f, 3c, and 3e. In the later stage, the most potent compounds have been evaluated for Aβ42 inhibitory profile. It can be hypothesized that this series of alkyl-aryl sulphonamides exhibit anti-AD activity by inhibition of Acetylcholinesterase (AChE) enzyme as well as inhibition of plaque formation on prolong dosage along with neuroprotection from oxidative stress.

Keywords: gamma-secretase inhibitors, Alzzheimer's disease, sulphonamides, QSAR

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Authors: Ellie Fini, Mahour Parast, Daniel Oldham, Shahrzad Hosseinnezhad

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This paper investigates the relationship between molecular species of four different bio-based adhesives (made from Swine Manure, Miscanthus Pellet, Corn Stover, and Wood Pellet) and their rheological behavior before and after they undergo extensive oxidative aging. To study the effect of oxidative aging on the chemical structure of bio-adhesives, Infrared Attenuated Total Reflectance Spectroscopy (Fourier transform infrared) was utilised. In addition, a Drop Shape Analyser, Rotational Viscometer, and Dynamic Shear Rheometer were used to evaluate the surface properties and rheological behaviour of each bio-adhesive. Overall, bio-adhesives were found to be significantly different in terms of their ageing characteristics. Accordingly, their surface and rheological properties were found to be ranked differently before and after ageing. The results showed that the bio-adhesive from swine manure is less susceptible to aging compared to plant-based bio-oils. This can be further attributed to the chemical structure and the high lipid contents of the bio-adhesive from swine manure, making it less affected by oxidative ageing.

Keywords: bio-adhesive, rheology, bio-mass, material genome

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Authors: Khodamorad Nabaki, Jianhu Shen, Xiaodong Huang

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This paper develops a method for considering the critical fatigue stress as a constraint in the Bi-directional Evolutionary Structural Optimization (BESO) method. Our aim is to reach an optimal design in which high cycle fatigue failure does not occur for a specific life time. The critical fatigue stress is calculated based on modified Goodman criteria and used as a stress constraint in our topology optimization problem. Since fatigue generally does not occur for compressive stresses, we use the p-norm approach of the stress measurement that considers the highest tensile principal stress in each point as stress measure to calculate the sensitivity numbers. The BESO method has been extended to minimize volume an object subjected to the critical fatigue stress constraint. The optimization results are compared with the results from the compliance minimization problem which shows clearly the merits of our newly developed approach.

Keywords: topology optimization, BESO method, p-norm, fatigue constraint

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Authors: Jeries J. Abou-Hanna

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Several techniques exist for determining stress-intensity factors in linear elastic fracture mechanics analysis. These techniques are based on analytical, numerical, and empirical approaches that have been well documented in literature and engineering handbooks. However, not all techniques share the same merit. In addition to overly-conservative results, the numerical methods that require extensive computational effort, and those requiring copious user parameters hinder practicing engineers from efficiently evaluating stress-intensity factors. This paper investigates the prospects of reducing the complexity and required variables to determine stress-intensity factors through the utilization of the stress gradient and a weighting function. The heart of this work resides in the understanding that fracture emanating from stress concentration locations cannot be explained by a single maximum stress value approach, but requires use of a critical volume in which the crack exists. In order to understand the effectiveness of this technique, this study investigated components of different notch geometry and varying levels of stress gradients. Two forms of weighting functions were employed to determine stress-intensity factors and results were compared to analytical exact methods. The results indicated that the “exponential” weighting function was superior to the “absolute” weighting function. An error band +/- 10% was met for cases ranging from a steep stress gradient in a sharp v-notch to the less severe stress transitions of a large circular notch. The incorporation of the proposed method has shown to be a worthwhile consideration.

Keywords: fracture mechanics, finite element method, stress intensity factor, stress gradient

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Authors: Aisha Bano, Rizwan Nazir

Abstract:

The present study aimed at exploring the impact of meaning in life on psychological well-being and stress among university students. Victor Frankl's paradigm provided the theoretical foundation for this study. A sample of 560 university students was drawn from Quaid-i-Azam University Islamabad. The sample was drawn using stratified random sampling technique. Data were collected using Existence Scale, Warwick-Edinburg Mental Well-Being Scale, and Stress Scale. Results of linear regression analysis reveals that high perception of meaning in life will lead to high psychological well-being and low stress among university students. Non-significant differences are found on meaning in life variable with regard to gender in the sample using t-test. Together these results suggest that meaning in life independent of gender, is a significant predictor of the levels of stress and psychological well-being being directly related to psychological well-being and inversely related to stress levels.

Keywords: existential meaning in life, psychological well-being, stress, students

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Authors: A. Ritcey, J. R. Mcdermid, S. Ziada

Abstract:

Wall shear stress was experimentally measured under a planar impinging air jet as a function of jet Reynolds number (Rejet = 5000, 8000, 11000) and different normalized impingement distances (H/D = 4, 6, 8, 10, 12) using the razor blade technique to complete a parametric study. The wall pressure, wall pressure gradient, and wall shear stress information were obtained.

Keywords: experimental fluid mechanics, impinging planar jets, skin friction factor, wall shear stress

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Authors: H. Gholami, M. Jalali Azizpour

Abstract:

For materials such as hard coating whose stresses state are difficult to obtain by a widely used method called high-speed hole-drilling method (ASTM Standard E837). It is important to develop a non contact method. This process itself imposes an additional stresses. The through thickness residual stress of st37 steel using elector-discharge was investigated. The strain gage and dynamic strain indicator used in all cases was FRS-2-11 rosette type and TML 221, respectively. The average residual stress in depth of 320 µm was -6.47 MPa.

Keywords: HVOF, residual stress, thermal spray, WC-Co

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Authors: Kamel Hachour, Lydia Sadeg, Djamel Sersab, Tassadit Bellahcen

Abstract:

The hydrostatic stress is, for polymers, a significant parameter which affects the yield behavior of these materials. In this work, we investigate the influence of this parameter on yield behavior of the high density polyethylene (hdpe). Some tests on specimens with diverse geometries are described in this paper. Uniaxial tests: tensile on notched round bar specimens with different curvature radii, compression on cylindrical specimens and simple shear on parallelepiped specimens were performed. Biaxial tests with various combinations of tensile/compressive and shear loading on butterfly specimens were also realized in order to determine the hydrostatic stress for different states of solicitation. The experimental results show that the yield stress is very affected by the hydrostatic stress developed in the material during solicitations.

Keywords: biaxial tests, hdpe, Hydrostatic stress, yield behavior

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Authors: Masoud Rafiee

Abstract:

To study the quality response of forage to chickpea-barley mixed cropping under drought stress and vermicompost consumption, an experiment was carried out under well watered and %70 water requirement (stress condition) in RCBD as split plot with four replications in temperate condition of Khorramabad in 2013. Chickpea-barley mix cropping (%100 chickpea, %75:25 chickpea:barley, %50:50 chickpea:barley, %25:75 chickpea:barley, and %100 barley) was studied. Results showed that wet and dry forage yield were significantly affected by environment and decreased in stress condition. Also, crude protein content decreased from %26.2 in well watered to %17.3 in stress condition.

Keywords: crude protein, wet forage yield, dry forage yield, water stress condition, well watered

Procedia PDF Downloads 316