Search results for: Residual stress and distortions

Authors: Luc Conti, Dimitry Dumont-Fillon, Harald van Lintel, Eric Chappel

Abstract:

Flow control valves comprise a silicon flexible membrane that deflects against a substrate, usually made of glass, containing pillars, an outlet hole, and anti-stiction features. However, there is a strong interest in using silicon instead of glass as substrate material, as it would simplify the process flow by allowing the use of well controlled anisotropic etching. Moreover, specific devices demanding a bending of the substrate would also benefit from the inherent outstanding mechanical strength of monocrystalline silicon. Unfortunately, direct Si-Si bonding is not easily achieved with highly structured wafers since residual stress may prevent the good adhesion between wafers. Using a thermoplastic polymer, such as parylene, as intermediate layer is not well adapted to this design as the wafer-to-wafer alignment is critical. An alternative anodic bonding method using an intermediate borosilicate layer has been successfully tested. This layer has been deposited onto the silicon substrate. The bonding recipe has been adapted to account for the presence of the SOI buried oxide and intermediate glass layer in order not to exceed the breakdown voltage. Flow control valves dedicated to infusion of viscous fluids at very high pressure have been made and characterized. The results are compared to previous data obtained using the standard anodic bonding method.

Keywords: anodic bonding, evaporated glass, flow control valve, drug delivery

Procedia PDF Downloads 184

Authors: Showkat Ahmad Lone, Ahmadur Rahman, Ariful Islam

Abstract:

The major assumption in accelerated life tests (ALT) is that the mathematical model relating the lifetime of a test unit and the stress are known or can be assumed. In some cases, such life–stress relationships are not known and cannot be assumed, i.e. ALT data cannot be extrapolated to use condition. So, in such cases, partially accelerated life test (PALT) is a more suitable test to be performed for which tested units are subjected to both normal and accelerated conditions. This study deals with estimating information about failure times of items under step-stress partially accelerated life tests using progressive failure-censored hybrid data with random removals. The life data of the units under test is considered to follow exponential life distribution. The removals from the test are assumed to have binomial distributions. The point and interval maximum likelihood estimations are obtained for unknown distribution parameters and tampering coefficient. An optimum test plan is developed using the D-optimality criterion. The performances of the resulting estimators of the developed model parameters are evaluated and investigated by using a simulation algorithm.

Keywords: binomial distribution, d-optimality, multiple censoring, optimal design, partially accelerated life testing, simulation study

Procedia PDF Downloads 302

Authors: Muchiri Josephine, Qdero Agnes

Abstract:

The current study was conducted during the coronavirus pandemic (COVID-19) period, soon after the lifting of the lockdown measures and schools had just re-opened. It investigated the sociodemographic correlates of Post-Traumatic Stress Disorder (PTSD) among adolescents (13-18 years) who had undergone domestic violence (DV) in Kajiado County, Kenya. The adolescents were administered a sociodemographic questionnaire to ascertain the forms of domestic violence experienced, and those who met the criteria were assessed for the presence of PTSD using the Harvard Trauma Questionnaire (HTQ). Overall, 93(90.3%) had experienced domestic violence, and 57(61.3%) had PTSD; where the severity and prevalence of PTSD increased with increased age, and it also increased significantly among those in higher academic levels, indicating that PTSD prevalence was chronic and additionally influenced by increased academic pressure. Social connections seemed to mitigate PTSD prevalence, whereas, regarding the family background, those living with guardians seemed to have more severe PTSD.

Keywords: age, education level, gender, post-traumatic stress disorder

Procedia PDF Downloads 58

Authors: Farhad Fakoursevom

Abstract:

Heart disease is one of the diseases which is found in abundance today. Various types of surgeries, such as bypasses, angiography, angioplasty, etc., are used to treat patients. People may receive such surgeries, some of which are invasive and some non-invasive, throughout their lives. People might cope with pre-surgery anxiety and stress, which can disrupt their normal life and even reduce the effects of the surgery, so the desired result can not be achieved in surgery. Considering this issue, the present study aimed to do a comparative assessment of people who received sedatives before surgery and people who did not receive sedatives. In terms of the purpose, this is an applied research and descriptive survey in terms of method. The statistical population included patients who underwent surgeries in the specialist heart hospitals of Mashhad, Iran; 60 people were considered as a statistical population, 30 of them received sedatives before surgery, and 30 others had not received sedatives before surgery. Valid and up-to-date articles were systematically used to collect theoretical bases, and a researcher-made questionnaire was used to examine the level of stress and anxiety of people. The questionnaire content validity was assessed by a panel of experts in psychology and medicine. The construct validity was tested using the software. Cronbach's alpha and composite reliability were used for reliability, which shows the appropriate reliability of the questionnaire. SPSS software was used to compare the research results between two groups, and the research findings showed that there is no significant association between the people who received sedatives and those who did not receive sedatives in terms of the amount of stress and anxiety. The longer the time of taking the drugs before the surgery, the more the mental peace of the patients will be. According to the results, it can be said that if we don't need to have an emergency operation and need more time, we have to use sedative drugs with different doses compared to the severity of the surgery, and also in case of a medical emergency such as heart surgery due to a stroke, we have to take advantage of psychological services during and before the operation and sedative drugs so that the patients can control their stress and anxiety and achieve better outcomes.

Keywords: sedative drugs, stress, anxiety, surgery

Procedia PDF Downloads 81

Authors: Shengwei Zhu, Alireza Afshani, Hirokazu Akagi

Abstract:

Ground surface settlement induced by shield tunneling is addressing increasing attention as shield tunneling becomes a popular construction technique for tunnels in urban areas. This paper discusses a 2D longitudinal FEM simulation of a tunneling case study in Japan (Tokyo Metro Yurakucho Line). Tunneling-induced field data was already collected and is used here for comparison and evaluating purposes. In this model, earth pressure, face pressure, backfilling grouting, elastic tunnel lining, and Mohr-Coulomb failure criterion for soil elements are considered. A method called ‘stress relaxation’ is also exploited to simulate the gradual tunneling excavation. Ground surface settlements obtained from numerical results using the introduced method are then compared with the measurement data.

Keywords: 2D longitudinal FEM model, tunneling case study, stress relaxation, shield tunneling excavation

Procedia PDF Downloads 312

Authors: Priyanka Kalra

Abstract:

Background: Complementary and alternative medicine (CAM) includes various practices like Ayurveda, Yoga & Meditation Acupressure Acupuncture and Reiki. These practices are frequently used by patients with spinal cord injury (SCI). They have shown effectiveness in the management of pain and stress consequently improving overall quality of life post injury. Objective: The goals of the present case series were to evaluate the feasibility of 1) Using of Ayurvedic herbal oil massages in shoulder pain management, 2) Using yoga & meditation on managing the stress in spinal cord injury. Methodology: 15 SCI cases with muscular pain around shoulder were treated with Ayurvedic herbal oil massage for 10 days in CAM Department. Each session consisted of 30 min oil massage followed by 10 min hot towel fomentation. The patients continued regular therapy medications along with CAM. Another 15 SCI cases were treated with yoga and meditation for 15 days 30 min yoga (20 min Asana+ 10 min Pranayam + 15 min Meditation) in isolated yoga room of CAM department. Results: On the VAS scale the patients reported a reduction in their pain score by 70 %. On the PSS scale, the patients reported a reduction in their stress score by 80 %. Conclusion: These case series may encourage more people to explore CAM therapies.

Keywords: spinal cord injury, Ayurveda, complementary and alternative medicine, yoga, meditation

Procedia PDF Downloads 284

Authors: Daniel Motlhanka, Neo Kerebotswe

Abstract:

The strong and long history of use of medicinal plants in Botswana to address existing and emerging health threats provides undebatable evidence for their potential as innovative therapeutic tools. The prevalence of emerging health threats, such as COVID-19 and hard-to-treat non-communicable diseases, warrants the scientific community to revisit and exploit ethnopharmacology for its potential as a source of therapeutic tools. Many studies conducted on bioactivity-guided bioassays of ethnobotanical resources have proved a number of health beneficial properties of these plants, such as free radical scavenging, anti-inflammatory, antimicrobial and, most importantly, the capability of medicinal plants to alleviate oxidative stress. In this work, a number of medicinal plants used in Botswana traditional medicine were investigated for both their free radical scavenging capability and total phenolic contents using the Free Radical Scavenging Power (FRSP) and Folin Ciocalteau (FC) method. At 100 micrograms/ml all the studied plants expressed above 90% Scavenging power and expressed total phenolic contents between 5000- 8890 mg/L.GAE. These plants are promising tools for engineering active therapeutic tools against life-threatening diseases of oxidative stress origin.

Keywords: oxidative stress, non-communicable diseases, total phenolics, ethnobotanicals

Procedia PDF Downloads 20

Authors: Susan Evans, Janna Gordon-Elliott, Katarzyna Wyka, Virginia Mutch

Abstract:

During the rise of the COVID-19 pandemic, healthcare workers needed an intervention that could address their profound acute stress. Mindfulness-based stress reduction (MBSR) is a program that has long established effectiveness for mental and physical health outcomes. In recent years, MBSR has been modified such that the duration of both class time and number of sessions has been abbreviated, and its delivery has been adapted for online dissemination, thus increasing the likelihood that individuals who could most benefit from the program would do so. We sought to investigate whether a brief, online version of MBSR could be feasible and acceptable for health care workers (HCW) in acute stress in response to the COVID-19 pandemic. Participants were recruited via an email sent to all hospital employees, which spans residents, physicians, nurses, housekeeping, lab technicians, administrators, and others. Participating HCW were asked about their previous experience with mindfulness and asked to commit to a minimum of 3 sessions. They were then provided with four weekly 1-hour sessions online that included the major mindfulness exercises taught during traditional MBSR programs (i.e., body scan, sitting meditation, mindful eating, and yoga). Participants were provided with supporting slides, videos, demonstrations and asked to track their practice. Hospital staff enrolled in the program; by the end of the first day of recruitment, 40 had applied; by the start date, about 100 were enrolled, and n attended a minimum of 3 sessions, supporting feasibility. Hospital staff also participated and practiced the mindfulness exercises (n=42), thus supporting acceptability. Participants reported that the program was logical, successful, and worth recommending both before starting the program and after completing it (M= 22.02 and M=21.76, respectively, possible range 0-27). There was a slight decline in the belief in improvement in health and well-being due to the program (ES=.37, p=.021). Secondary hypotheses regarding participants’ self-reported stress and levels of mindfulness were also supported, such that participants reported improvements in perceived stress (ES=.45, p=.006), compassion satisfaction, burnout, and secondary traumatic stress (ES=.41, ES=.31, ES=.35, respectively, p<.05). Participants reported significant improvements in the describing facet of mindfulness (ES=.49, p=.004), while all other facets (observing, acting with awareness, nonjudging of inner experience, nonreactivity to inner experience) remained unchanged pre- to post-program. Results from this study suggest that an abridged, online version of MBSR is feasible and accessible to health care workers in acute stress and provides benefits expected from traditional MBSR programs. The lack of a randomized control group limits generalizability. We intend to provide a structure, framework, and lessons learned to hospital administrators and clinical staff seeking to support their employees in acute stress.

Keywords: acute stress, health care workers, mindfulness, online interventions

Procedia PDF Downloads 96

Authors: Negar Ganjouhaghighi, Amirali Dolatshahi

Abstract:

The origin of most risks of a mega project usually takes place in the phases before closing the contract. As a practical point of view, using project risk management techniques for preparing a proposal is not a total solution for managing the risks of a contract. The objective of this paper is to cover all those activities associated with risk management of a mega project sale’s processes; from entrance to a new market to awarding activities and the review of contract performance. In this study, the risk management happens in six consecutive steps that are divided into three distinct but interdependent phases upstream of the award of the contract: pre-tendering, tendering and closing. In the first step, by preparing standard market risk report, risks of the new market are identified. The next step is the bid or no bid decision making based on the previous gathered data. During the next three steps in tendering phase, project risk management techniques are applied for determining how much contingency reserve must be added or reduced to the estimated cost in order to put the residual risk to an acceptable level. Finally, the last step which happens in closing phase would be an overview of the project risks and final clarification of residual risks. The sales experience of more than 20,000 MW turn-key power plant projects alongside this framework, are used to develop a software that assists the sales team to have a better project risk management.

Keywords: project marketing, risk management, tendering, project management, turn-key projects

Procedia PDF Downloads 310

Authors: Asmaa M. El-Bandrawy, Afaf M. Botla, Ghada E. El-Refaye, Hassan O. Ghareeb

Abstract:

Background: Urinary incontinence is a common problem among adults. Its incidence increases with age and it is more frequent in women. Pelvic floor muscle training (PFMT) is the first-line therapy in the treatment of pelvic floor dysfunction (PFD) either alone or combined with biofeedback-assisted PFMT. The aim of the work: The purpose of this study is to evaluate the efficacy of biofeedback-assisted PFMT in postoperative stress urinary incontinence. Settings and Design: A single blind controlled trial design was. Methods and Material: This study was carried out in 30 volunteer patients diagnosed as severe degree of stress urinary incontinence and they were admitted to surgical treatment. They were divided randomly into two equal groups: (Group A) consisted of 15 patients who had been treated with post-operative biofeedback-assisted PFMT and home exercise program (Group B) consisted of 15 patients who had been treated with home exercise program only. Assessment of all patients in both groups (A) and (B) was carried out before and after the treatment program by measuring intra-vaginal pressure in addition to the visual analog scale. Results: At the end of the treatment program, there was a highly statistically significant difference between group (A) and group (B) in the intra-vaginal pressure and the visual analog scale favoring the group (A). Conclusion: biofeedback-assisted PFMT is an effective method for the symptomatic relief of post-operative female stress urinary incontinence.

Keywords: stress urinary incontinence, pelvic floor muscles, pelvic floor exercises, biofeedback

Procedia PDF Downloads 287

Authors: Hakim S. Sultan Aljibori

Abstract:

An experimental procedure is developed to study the performance of composite thin wall cylinders subjected to internal pressure loading for investigations of stress distribution through the composite cylinders wall. Three types of fibers were used in this study are; woven roving glass fiber/epoxy, hybrid fiber/epoxy, and Kevlar fiber/epoxy composite specimens were fabricated and tested. All of these specimens subjected to uniformed pressure load using the hydraulic pump. Axial stress is identified, and values were found after collecting all the results. Comparison between the deferent types of specimens was done. Thus, the present investigation concludes the efficient and effective composite cylinder experimentally and provides a considerable advantage for using woven roving fibers in pressure vessels applications.

Keywords: stress distribution, composite material, internal pressure, glass fiber, hybrid fiber

Procedia PDF Downloads 139

Authors: Ebissa Gadissa Kedir, C. S. P. Ojha, K. S. Hari Prasad

Abstract:

In the present study, the depth-averaged velocity and boundary shear stress in non-prismatic compound channels with three different converging floodplain angles ranging from 1.43ᶱ to 7.59ᶱ have been studied. The analytical solutions were derived by considering acting forces on the channel beds and walls. In the present study, five key parameters, i.e., non-dimensional coefficient, secondary flow term, secondary flow coefficient, friction factor, and dimensionless eddy viscosity, were considered and discussed. An expression for non-dimensional coefficient and integration constants was derived based on the boundary conditions. The model was applied to different data sets of the present experiments and experiments from other sources, respectively, to examine and analyse the influence of floodplain converging angles on depth-averaged velocity and boundary shear stress distributions. The results show that the non-dimensional parameter plays important in portraying the variation of depth-averaged velocity and boundary shear stress distributions with different floodplain converging angles. Thus, the variation of the non-dimensional coefficient needs attention since it affects the secondary flow term and secondary flow coefficient in both the main channel and floodplains. The analysis shows that the depth-averaged velocities are sensitive to a shear stress-dependent model parameter non-dimensional coefficient, and the analytical solutions are well agreed with experimental data when five parameters are included. It is inferred that the developed model may facilitate the interest of others in complex flow modeling.

Keywords: depth-average velocity, converging floodplain angles, non-dimensional coefficient, non-prismatic compound channels

Procedia PDF Downloads 61

Authors: Pudji Astuti, C. P. C. Putro, C. M. Airin, L. Sjahfirdi, S. Widiyanto, H. Maheshwari

Abstract:

Stress of slaughter animals starting long before until at the time of process of slaughtering which cause misery and decrease of meat quality. Meanwhile, determination of animal stress using hormonal such as cortisol is expensive and less practical so that portable stress indicator for cows based on Fourier Transform Infrared Spectroscopy (FTIR) must be provided. The aims of this research are to find out the comparison process of slaughter between Rope Casting Local (RCL) and Restraining Box Method (RBM) by measuring of cortisol and wavelength in FTIR methods. Thirty two of male Ongole crossbred cattle were used in this experiment. Blood sampling was taken from jugular vein when they were rested and repeated when slaughtered. All of blood samples were centrifuged at 3000 rpm for 20 minutes to get serum, and then divided into two parts for cortisol assayed using ELISA and for measuring the wavelength using FTIR. The serum then measured at the wavelength between 4000-400 cm-1 using MB3000 FTIR. Band data absorption in wavelength of FTIR is analyzed descriptively by using FTIR Horizon MBTM. For RCL, average of serum cortisol when the animals rested were 11.47 ± 4.88 ng/mL, when the time of slaughter were 23.27 ± 7.84 ng/mL. For RBM, level of cortisol when rested animals were 13.67 ± 3.41 ng/mL and 53.47 ± 20.25 ng/mL during the slaughter. Based on student t-Test, there were significantly different between RBM and RCL methods when beef cattle were slaughtered (P < 0.05), but no significantly different when animals were rested (P > 0.05). Result of FTIR with the various of wavelength such as methyl group (=CH3) 2986cm-1, methylene (=CH2) 2827 cm-1, hydroxyl (-OH) 3371 cm-1, carbonyl (ketones) (C=O) 1636 cm-1, carboxyl (COO-1) 1408 cm-1, glucosa 1057 cm-1, urea 1011 cm-1have been obtained. It can be concluded that the RCL slaughtered method is better than the RBM method based on the increase of cortisol as an indicator of stress in beef cattle (P<0.05). FTIR is really possible to be used as stub of stress tool due to differentiate of resting and slaughter condition by recognizing the increase of absorption and the separation of component group at the wavelength.

Keywords: cows, cortisol, FTIR, RBM, RCL, stress indicator

Procedia PDF Downloads 621

Authors: Jing Li, Li Jin, Fulin Wang, Jie Dong, Wenjiang Ding

Abstract:

Mg-Li dual-phase alloy exhibits better combination of yield strength and elongation than the Mg single-phase alloy. To exploit its deformation behavior, the deformation mechanisms of Mg-2Gd alloy with or without Li addition, i.e., Mg-6Li-2Gd and Mg-2Gd alloy, have been studied at both microscale and mesoscale. EBSD-assisted slip trace, twin trace, and texture evolution analysis show that the α-Mg phase of Mg-6Li-2Gd alloy exhibits different microscopic deformation mechanisms with the Mg-2Gd alloy, i.e., mainly prismatic slip in the former one, while basal slip, prismatic slip and extension twin in the latter one. Further Schmid factor analysis results attribute this different intra-phase deformation mechanisms to the higher critical resolved shear stress (CRSS) value of extension twin and lower ratio of CRSSprismatic /CRSSbasal in the α-Mg phase of Mg-6Li-2Gd alloy. Additionally, Li addition can induce dual-phase microstructure in the Mg-6Li-2Gd alloy, leading to the formation of hetero-deformation induced (HDI) stress at the mesoscale. This can be evidenced by the hysteresis loops appearing during the loading-unloading-reloading (LUR) tensile tests and the activation of multiple slip activity in the α-Mg phase neighboring β-Li phase. The Mg-6Li-2Gd alloy shows higher yield strength is due to the harder α-Mg phase arising from solid solution hardening of Li addition, as well asthe strengthening of soft β-Li phase by the HDI stress during yield stage. Since the strain hardening rate of Mg-6Li-2Gd alloy is lower than that of Mg-2Gd alloy after ~2% strain, which is partly due to the weak contribution of HDI stress, Mg-6Li-2Gd alloy shows no obvious increase of uniform elongation than the Mg-2Gd alloy.But since the β-Li phase is effective in blunting the crack tips, the Mg-6Li-2Gd alloy shows ununiform elongation, which, thus, leads to the higher total elongation than the Mg-2Gd alloy.

Keywords: Mg-Li-Gd dual-phase alloy, phase boundary, HDI stress, dislocation slip activity, mechanical properties

Procedia PDF Downloads 184

Authors: Samih Ahmed, Guayente Minchot, Fritz King, Mikael Hallgren

Abstract:

The stress ribbon system has numerous advantages that include but are not limited to increasing overall stiffness, control deflections, and reduction of materials consumption, which in turn, reduces the load and the cost. Nevertheless, its use is usually limited to bridges, in particular, pedestrian bridges; this can be attributed to the insufficient space that buildings' usually have for end supports, and/or back- stayed cables, that can accommodate the expected high pull-out forces occurring at the cables' ends. In this work, the roof of Västerås Travel Center, which will become one of the longest cable suspended roofs in the world, was chosen as a case study. The aim was to investigate the optimal technique to model the post-tensioned stress ribbon system for the roof structure using the FEM software SAP2000 and to assess any possible reduction in the pull-out forces, deflections, and concrete stresses. Subsequently, a conventional cable suspended roof was simulated using SAP2000, and compared to the post-tension stress ribbon system in order to examine the potential of the latter. Moreover, the effects of temperature loads and support movements on the final design loads were examined. Based on the study, a few practical recommendations concerning the construction method and the iterative design process, required to meet the architectural geometrical demands, are stated by the authors. The results showed that the post-tensioned stress ribbon system reduces the concrete stresses, overall deflections, and more importantly, reduces the pull-out forces and the vertical reactions at both ends by up to 16% and 11%, respectively, which substantially reduces the design forces for the support structures. The magnitude of these reductions was found to be highly correlated to the applied prestressing force, making the size of the prestressing force a key factor in the design.

Keywords: cable suspended, post-tension, roof structure, SAP2000, stress ribbon

Procedia PDF Downloads 145

Authors: Huey-Fang Sun, Wei-Kai Weng, Mei-Kuang Chao, Hui-Shan Hsu, Tsai-Yin Shih

Abstract:

Psycho-social stress is important for mental illness and the presence of emotional and behavioral symptoms to an identifiable event is the central feature of adjustment disorders. However, whether patients with adjustment disorders have been raised in family with poor family functions and social supports and have higher stress perception than their peer group when they both experienced a similar stressful environment remains unknown. The specific aims of the study are to investigate the correlation among the family function, social supports and the level of stress perception and to test the hypothesis that military patients with adjustment disorders would have lower family function, lower social supports and higher stress perception than their healthy colleagues recruited in the same cohort for military services given their common exposure to similar stressful environments. Methods: The study was conducted in four hospitals of northern part of Taiwan from July 1, 2015 to June 30, 2017 and a matched case-control study design was used. The inclusion criteria for potential patient participants were psychiatric inpatients that serviced in military during the study period and met the diagnosis of adjustment disorders. Patients who had been admitted to psychiatric ward before or had illiteracy problem were excluded. A healthy military control sample matched by the same military service unit, gender, and recruited cohort was invited to participate the study as well. Totally 74 participants (37 patients and 37 controls) completed the consent forms and filled out the research questionnaires. Questionnaires used in the study included Perceived Stress Scale (PSS) as a measure of stress perception; Family APGAR as a measure of family function, and Multidimensional Scale of Perceived Social Support (MSPSS) as a measure of social supports. Pearson correlation analysis and t-test were applied for statistical analysis. Results: The analysis results showed that PSS level significantly negatively correlated with three social support subscales (family subscale, r= -.37, P < .05; friend subscale, r= -.38, P < .05; significant other subscale, r= -.39, P < .05). A negative correlation between PSS level and Family APGAR only reached a borderline significant level (P= .06). The t-test results for PSS scores, Family APGAR levels, and three subscale scores of MSPSS between patient and control participants were all significantly different (P < .001, P < .05, P < .05, P < .05, P < .05, respectively) and the patient participants had higher stress perception scores, lower social supports and lower family function scores than the healthy control participants. Conclusions: Our study suggested that family function and social supports were negatively correlated with patients’ subjective stress perception. Military patients with adjustment disorders tended to have higher stress perception and lower family function and social supports than those military peers who remained healthy and still provided services in their military units.

Keywords: adjustment disorders, family function, social support, stress perception

Procedia PDF Downloads 176

Authors: Serge Mudinga Lemika, Samuel Olukayode Akinwamide, Aribo Sunday, Babatunde Abiodun Obadele, Peter Apata Olubambi

Abstract:

Use of Duplex stainless steel has become predominant in applications where excellent corrosion resistance is of utmost importance. Corrosion behavior of duplex stainless steel induced with varying stress in a chloride media were studied. Characterization of as received 2205 duplex stainless steels were carried out to reveal its structure and properties tensile sample produced from duplex stainless steel was initially subjected to tensile test to obtain the yield strength. Stresses obtained by various percentages (20, 40, 60 and 80%) of the yield strength was induced in DSS samples. Corrosion tests were carried out in magnesium chloride solution at room temperature. Morphologies of cracks observed with optical and scanning electron microscope showed that samples induced with higher stress had its austenite and ferrite grains affected by pitting.

Keywords: duplex stainless steel, hardness, nanoceramics, spark plasma sintering

Procedia PDF Downloads 280

Authors: T. Bettaieb, S. Soufi, S. Arbaoui

Abstract:

Stevia rebaudiana Bert. is a natural sweet plant. The leaves contain diterpene glycosides stevioside, rebaudiosides A-F, steviolbioside and dulcoside, which are responsible for its sweet taste and have commercial value all over the world as sugar substitute in foods and medicines. Stevia rebaudiana Bert. is sensitive temperature lower than 9°C. The possibility of its outdoor culture in Tunisian conditions demand genotypes tolerant to low temperatures. In order to evaluate the low temperature tolerance of eight genotypes of Stevia rebaudiana, the activities of superoxide dismutase (SOD), ascorbate peroxidase (APX) and catalases (CAT) were measured. Before carrying out the analyses, three genotypes of Stevia were exposed for 1 month at a temperature regime of 18°C during the day and 7°C at night similar to winter conditions in Tunisia. In response to the stress generated by low temperature, antioxidant enzymes activity revealed on native gel and quantified by spectrophotometry showed variable levels according to their degree of tolerance to low temperatures.

Keywords: chilling tolerance, enzymatic activity, stevia rebaudiana bert, low thermal stress

Procedia PDF Downloads 420

Authors: Kobid Panthi, Suttisak Soralump, Suriyon Prempramote

Abstract:

In June 27, 2014 slope movement was observed in upstream side of Khlong Pa Bon Dam, Thailand. The slide did not have any major catastrophic impact on the dam structure but raised a very important question; why did the slide occur after 10 years of operation? Various site investigations (Bore Hole Test, SASW, Echo Sounding, and Geophysical Survey), laboratory analysis and numerical modelling using SIGMA/W and SLOPE/W were conducted to determine the cause of slope movement. It was observed that the dam had undergone the greatest differential drawdown in its operational history in the year 2014 and was termed as the major cause of movement. From the laboratory tests, it was found that the shear strength of clay had decreased with a period of time and was near its residual value. The cyclic movement of water, i.e., reservoir filling and emptying was coined out to be the major cause for the reduction of shear strength. The numerical analysis was carried out using a modified cam clay (MCC) model to determine the strain softening behavior of the clay. The strain accumulation was observed in the slope with each reservoir cycle triggering the slope failure in 2014. It can be inferred that if there was no major drawdown in 2014, the slope would not have failed but eventually would have failed after a long period of time. If there was no major drawdown in 2014, the slope would not have failed. However, even if there hadn’t been a drawdown, it would have failed eventually in the long run.

Keywords: slope movement, strain softening, residual strength, modified cam clay

Procedia PDF Downloads 114

Authors: D. S. Mohale, A.V. Chandewar

Abstract:

Study was undertaken to investigate the effect of imipramine on various biochemical parameters and oxidative stress markers in short and long term depression on rats. Rats were subjected for short (21 days) and long term (84 days) social isolation for and checked for depression on force swim test and tail suspension method. Various markers of oxidative stress like lipid peroxidation (LPO), reduced glutathione (GSH), Supersoxide dismutase (SOD), catalase (CAT) and biochemical parameters like Serum glutamate oxaloacetate transaminase (SGOT), Serum glutamate pyruate transaminase (SGPT), and blood glucose were determined in depressed, control, imipramine and Vitamin E treated group. The rats displayed an increase in depression on force swim test and tail suspension method relative to control. There was significant increase in the level of LPO and decrease in the levels of GSH, SOD and CAT after short and long term depression. Increased oxidative stress in depression which may leads to alteration of biochemical parameters. Treatment with imipramine an tricyclic antidepressant significantly decreases in level of LPO, SGOT, SGPT and increase in the levels of GSH, SOD and CAT in long term depression.

Keywords: depression, oxidative stress, lipid peroxidation, reduced glutathione

Procedia PDF Downloads 486

Authors: Wojciech Gilewski, Anna Al Sabouni-Zawadzka, Jan Pelczynski

Abstract:

This paper focuses on the analysis of tensile stresses perpendicular to the grain in simply supported beams with different geometry made of glued laminated timber. Two types of beams are considered: standard double-tapered beams described in Eurocode 5 and non-standard glulam beams with a flattened apex. The beams are analyzed using two methodology approaches: a code design verification method and a finite element method (FEM) in terms of the linear theory of elasticity with plane stress assumption. The performed analyses proved that both methodologies lead to consistent results in case of standard glulam beams and therefore, the FEM can be used in case of non-standard structures, which are not included in Eurocode 5. Moreover, the FE analysis of the glulam beam with a flattened apex showed that it can be treated as a structure with two apex zones.

Keywords: double-tapered beams, finite element analysis, glued laminated timber, perpendicular to grain stress

Procedia PDF Downloads 216

Authors: S. Noreen, S. Ahmad

Abstract:

Salinity is one of the most important environmental factors that limit the production of crop plants to the greatest proportion than any other ones. Salt-induced changes in growth, pigment concentration, water status, malondialdehydes (MDA) and H₂O₂ content, enzymatic and non-enzymatic antioxidants, Na⁺, K⁺ content and yield attributes were examined in the glasshouse on ten pea (Pisum Sativum L.) accessions, namely ‘13240’, ‘18302’, ‘19666’, ‘19700’, ‘19776’, ‘19785’, ‘19788’, ‘20153’, ‘20155’, ‘26719’ were subjected to non-stress (0 mM NaCl) and salt stress (100 mM and150 mM NaCl) in pots containing sand medium. The results showed that salt stress at level150 mM substantially reduced biomass production, leaf water status, pigment concentration (chlorophyll ‘a’, ‘b’, ‘carotenoid content’ total chlorophyll), K⁺ content, quantum yield and yield attributes as compared to plants treated with 100 mM NaCl. Antioxidant enzymes, Catalase (CAT), Peroxidase (POD), Superoxide dismutase (SOD) and Ascorbate peroxidase (APX), proline content, total soluble protein, total amino acids, Malondialdehyde content (MDA), Hydrogen peroxide (H₂O₂) content and Na⁺ uptake markedly enhanced due to the influence of salt stress. On the basis of analyses (expressed as percent of control), of 10 accessions of pea plant, two were ranked as salt tolerant namely (‘19666’, ‘20153’), four were moderately tolerant namely (‘19700’, ‘19776’, ‘19785’, ‘20155’), and three were salt sensitive namely (‘13240’, ‘18302’, ‘26719’) at 150 mM NaCl level.

Keywords: antioxidant enzymes, ion uptake, pigment concentration, salt stress, yield attributes

Procedia PDF Downloads 87

Authors: Nosheen Zareen Khan, Abdul Majeed Siddiqui, Muhammad Afzal Rana

Abstract:

The steady flow of a second order fluid through constricted tube with slip velocity at wall is modeled and analyzed theoretically. The governing equations are simplified by implying no slip in radial direction. Based on Karman Pohlhausen procedure polynomial solution for axial velocity profile is presented. An expressions for pressure gradient, shear stress, separation and reattachment points and radial velocity are also calculated. The effect of slip and no slip velocity on velocity, shear stress, pressure gradient are discussed and depicted graphically. It is noted that when Reynolds number increases velocity of the fluid decreases in both slip and no slip conditions. It is also found that the wall shear stress, separation and reattachment points are strongly effected by Reynolds number.

Keywords: approximate solution, constricted tube, non-Newtonian fluids, Reynolds number

Procedia PDF Downloads 377

Authors: Omnia Y. Shawky, Asmaa M. Megahed, Alaa E. ElKomy, A. E. Abd-El-Hamid, Y. A. Attia

Abstract:

This study was carried out to elevate the broilers physiological response against heat stress and reduce this impact by adding vitamin C (VC), vitamin E (VE) alone/or with organic zinc (Zn) to chicks’ rations. A total of 192, 26-day-old Arbor Acers male chicks were randomly divided into equal 8 groups (4 replicates for each). All experimental groups were treated as follow: Group 2 was served as a heat stress control that reared at 37ºC with relative humidity 53 ± 8% for 6 hours/day for three successive days/week and fed the basal diet only. Groups 3-8 were heat stressed in a like manner to group 2 and fed basal diet inclusion 200mg VC (group 3), 200mg VE (group 4), 200mg VC+200mg VE (group 5), 200mg VC+30mg Zn (group 6), 200mg VE+30mg Zn (group 7) and 200mg VC+200mg VE+30mg Zn (group 8) /kg feed, while Group 1 was served as a positive control that reared on a neutral temperature (NT) (approximately 21ºC) and fed the basal diet only. Respiration rate and rectal temperature were boosted of HS chicks (80.8 breath/min and 41.97ºC) compared to NT group (60.12 breath/min and 40.9ºC), while, adding VC alone and with VE or Zn resulted in decrease these measurements. Heat stress had a significantly negative effect on chicks body weight gain, feed consumption and feed conversion ratio compared to the NT group, this harmful effect could be overcome by adding VC and VE individually or with Zn. Chicks exposed to heat stress showed slightly increase hemoglobin concentration compared to NT group, while, adding VC, VE individually or with Zn alleviated this effect. Plasma glucose concentration was significantly increased in HS group than the NT group, but adding VC, VE individually or with Zn resulted in a reduction plasma glucose level, which it was still higher than the NT group. Heat stress caused an increase in plasma total lipids and cholesterol concentration compared to the NT group and inclusion VC or VE alone or with Zn was not able to reduce this effect. The increased liver enzymes activities (AST and ALT) that observed in HS group compared to NT group were removed by adding VC and VE individually or with Zn. As well, exposure of broiler chicks to heat stress resulted in a slightly decrease in plasma total antioxidant capacity level (TAC) superoxide dismutase and catalase enzymes activities, while inclusion VC and VE individually or with Zn in chicks rations caused an increased in these measurements. Broiler chicks that exposed to HS revealed a significant increase in heat shock protein (Hsp 70) compared to the NT group, while, adding VC or VE individually or with Zn resulted in a significant decrease in Hsp70 than the HS group and VE alone or with VC had the greatest effect. In conclusion, it could be overcome the harmful and the negative effect of heat stress on broiler chicks’ productive performance and physiological status by inclusion VC (200mg) or VE (200mg) individual or in a combination with organic zinc (30 mg) in chicks’ rations.

Keywords: heat stress, broiler, vitamin C, vitamin E, organic zinc

Procedia PDF Downloads 184

Authors: Rodrigo D. S. Oliveira, Sarah David-Muzel, Maristela Gava, Victor A. De Araujo, Glaucia A. Prates, Juliana Cortez-Barbosa

Abstract:

Improper disposal of treated wood waste is a problem of the timber sector, since this residue is toxic, due to the harmful characteristics of the preservative substances. An environmentally friendly alternative is the use of this waste for the production of cement-wood composites. The aim of this work was to study the possibility of using wood treated with CCA (Chromated Cooper Arsenate) in cement-wood. Specimens of Pinus sp. and Eucalyptus sp. were produced with wood raw in natura and treated with CCA. A test was performed to determine the parallel shear stress of samples after 14 days of drying, according to the Brazilian Standard NBR-7215/97. Based on the analyzed results it is concluded that the use of wood treated with CCA is not feasible in cement-wood production, because the composite samples of treated wood showed lower mechanical strength in shear stress than those with wood in natura.

Keywords: waste recovery, wood composites, cement-wood, wood preservation, chromated copper arsenate

Procedia PDF Downloads 590

Authors: Solehuddin Shuib, Koay Boon Aik, Zainul Ahmad Rajion

Abstract:

There are many types of mechanical failure on the dental implant. In this project, the failure that needs to take into consideration is the bone resorption on the dental implant. Human bone has its ability to remodel after the implantation. As the dental implant is installed into the bone, the bone will detect and change the bone structure to achieve new biomechanical environment. This phenomenon is known as bone remodeling. The objective of the project is to improve the performance of dental implant by using different types of design. These designs are used to analyze and predict the failure of the dental implant by using finite element analysis (FEA) namely ANSYS. The bone is assumed to be fully attached to the implant or cement. Hence, results are then compared with other researchers. The results were presented in the form of Von Mises stress, normal stress, shear stress analysis, and displacement. The selected design will be analyzed further based on a theoretical calculation of bone remodeling on the dental implant. The results have shown that the design constructed passed the failure analysis. Therefore, the selected design is proven to have a stable performance at the recovery stage.

Keywords: dental implant, FEA, bone remodeling, design

Procedia PDF Downloads 485

Authors: N. Guo, C. Xu, Z. C. Yang

Abstract:

In order to ensure the high reliability of an aircraft, the accurate structural dynamics analysis has become an indispensable part in the design of an aircraft structure. Therefore, the structural finite element model which can be used to accurately calculate the structural dynamics and their transfer relations is the prerequisite in structural dynamic design. A dynamic finite element model updating method is presented to correct the uncertain parameters of the finite element model of a structure using measured modal parameters. The coordinate modal assurance criterion is used to evaluate the correlation level at each coordinate over the experimental and the analytical mode shapes. Then, the weighted summation of the natural frequency residual and the coordinate modal assurance criterion residual is used as the objective function. Moreover, the hybrid pattern search (HPS) optimization technique, which synthesizes the advantages of pattern search (PS) optimization technique and genetic algorithm (GA), is introduced to solve the dynamic FE model updating problem. A numerical simulation and a model updating experiment for GARTEUR aircraft model are performed to validate the feasibility and effectiveness of the present dynamic model updating method, respectively. The updated results show that the proposed method can be successfully used to modify the incorrect parameters with good robustness.

Keywords: model updating, modal parameter, coordinate modal assurance criterion, hybrid genetic/pattern search

Procedia PDF Downloads 138

Authors: Emrah Caylak

Abstract:

The aim of this study is to investigate the effect of iron therapy on oxidative stress, ghrelin, and nesfatin-1 levels in patients with iron deficiency anemia (IDA). Thirty patients who applied to Internal Medicine Clinic and were diagnosed with IDA and also 30 healthy individuals as a control were included in the study. The samples were collected from IDA patients before and after treatment. Differences in serum MDA, TAC, and plasma ghrelin, nesfatin-1 were analyzed among the three groups. Serum MDA and TAC levels were found higher and lower in IDA patients before the treatment group compared to the controls (p < 0.05). After the iron therapy, plasma acylated ghrelin and nesfatin-1 levels in IDA patients were found higher in IDA patients before the treatment group and controls (p < 0.05). Plasma ghrelin and nesfatin-1 levels increase with iron treatment in IDA patients. The iron therapy induces the synthesis of ghrelin and nesfatin-1 in human body, thus causes increased appetite and food intake.

Keywords: anemia, oxidative stress, ghrelin, nesfatin-1

Procedia PDF Downloads 130

Authors: Kanlaya Kong-Ngern, Chutima Homwonk, Sittiruk Roytrakul

Abstract:

In this research, we compared the proteomic profile of two rice leaf sheaths under salt stress, Thai moderately salt tolerant rice (Leaung Anan), and high salt tolerant rice (Pokkali). Seeds were grown in hydroponic culture for 21 days before NaCl was introduced initially at the level of 12 dS m⁻¹ for 10 days. Then the leaf sheath proteomes were analyzed by 1D-SDS-PAGE and NanoLC-MS/MS. In this study, 873 proteins were detected. Among these proteins, 219 proteins were known proteins and the other proteins were unnamed and unknown proteins. By using Mev software, we found that only 31 proteins in treated plants of both rice cultivars significantly expressed, 21 proteins were up-regulated and 10 proteins were down-regulated. Interestingly, the intensity of the 3 proteins in the Leaung Anan more expressed than in the Pokkali. The results indicate that the up-regulated proteins were more expressed in less tolerant rice may play an important role in helping rice to survive under salt stress.

Keywords: mass spectrometry, proteomics, rice leaf sheaths, salt stress

Procedia PDF Downloads 111

Authors: Ahmed Hammad, Yehia Abdel-Nasser, Mohamed Shamma

Abstract:

The main configuration of ship construction consists of standard and fabricated stiffening members which are commonly used in shipbuilding such as fabricated T-sections. During the welding process, the non-uniform heating and rapid cooling lead to the inevitable presence of out-of-plane distortion and welding induced residual stresses. Because of these imperfections, the fabricated structural members may not attain their design load to be carried. The removal of these imperfections will require extra man-hours. In the present work, controlling these imperfections has been investigated at both design and fabrication stages. A typical fabricated T-girder is selected to investigate the problem of these imperfections using double-side welding. A numerical simulation based on finite element (FE) modeling has been used to investigate the effect of different parameters of the selected fabricated T-girder such as geometrical properties and welding sequences on the magnitude of welding imperfections. FE results were compared with the results of experimental model of a double-side fillet weld. The present work concludes that: Firstly, in the design stage, the optimum geometry of the fabricated T- girder is determined based on minimum steel weight and out- of- plane distortion. Secondly, in the fabrication stage, the best welding sequence is determined on the basis of minimum welding out- of- plane distortion.

Keywords: fabricated T-girder, FEM, out-of-plane distortion, section modulus, welding residual stresses

Procedia PDF Downloads 105