Search results for: environmental stress cracking

Authors: Xiao-Jing Zhu, Liang Zhou, Shi-Zhong Zheng

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Various studies have shown that diallyl trisulfide (DATS) can protect the liver injury, and DATS has a strong antioxidant property. The aim of this study is to evaluate the in vivo role of DATS in protecting the liver against injury and fibrogenesis and further explores the underlying mechanisms. Our results demonstrated that DATS protected the liver from CCl4-caused injury by suppressing the elevation of ALT and AST activities, and by improving the histological architecture of the liver. Treatment with DATS or colchicine improved the liver fibrosis by sirius red staining and immunofluorescence. In addition, immunohistochemistry, western blot, and RT-PCR analyses indicated that DATS inhibited HSC activation. Furthermore, DATS attenuated oxidative stress by increasing glutathione and reducing lipid peroxides and malondialdehyde. These findings suggest that the protective effect of DATS on CCl4-caused liver injury and liver fibrogenesis was, at least partially, attributed to its antioxidant activity.

Keywords: liver fibrogenesis, liver injury, oxidative stress, DATS

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Authors: Vandana T. Gawande, Kailash G. Bothara, Chandani O. Satija

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The present research work was aimed to determine stability of cefprozil monohydrate (CEFZ) as per various stress degradation conditions recommended by International Conference on Harmonization (ICH) guideline Q1A (R2). Forced degradation studies were carried out for hydrolytic, oxidative, photolytic and thermal stress conditions. The drug was found susceptible for degradation under all stress conditions. Separation was carried out by using High Performance Thin Layer Chromatographic System (HPTLC). Aluminum plates pre-coated with silica gel 60F254 were used as the stationary phase. The mobile phase consisted of ethyl acetate: acetone: methanol: water: glacial acetic acid (7.5:2.5:2.5:1.5:0.5v/v). Densitometric analysis was carried out at 280 nm. The system was found to give compact spot for cefprozil monohydrate (0.45 Rf). The linear regression analysis data showed good linear relationship in the concentration range 200-5.000 ng/band for cefprozil monohydrate. Percent recovery for the drug was found to be in the range of 98.78-101.24. Method was found to be reproducible with % relative standard deviation (%RSD) for intra- and inter-day precision to be < 1.5% over the said concentration range. The method was validated for precision, accuracy, specificity and robustness. The method has been successfully applied in the analysis of drug in tablet dosage form. Three unknown degradation products formed under various stress conditions were isolated by preparative HPTLC and characterized by mass spectroscopic studies.

Keywords: cefprozil monohydrate, degradation products, HPTLC, stress study, stability indicating method

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Authors: Draoui Belkacem, Rahmani Lakhdar, Benachour Elhadj, Seghier Oussama

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Rheology is known to have a strong impact on the flow behavior and the power consumption of mechanically agitated vessels. The laminar 2D agitation flow and power consumption of viscoplastic fluids with an anchor impeller in a stirring tank is studied by using computational fluid dynamics (CFD). In this work the objective of this paper is: to evaluate the power consumption for yield stress fluids in standard mixing system. The power consumption is calculated for the different types of anchor impeller configurations and an optimum configuration is proposed.The hydrodynamic fields of incompressible yield stress fluid with model of Bingham in a cylindrical vessel not chicaned equipped with anchor stirrer was undertaken by means of numerical simulation. The flow structures, and especially the effect of inertia, the plasticity and the yield stress, are discussed.

Keywords: rheology, 2D, numerical, anchor, rotating vissel, non-Newtonien fluid

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Authors: Muhammed Kök & Adem Kantar

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Learning a foreign language can be affected by various factors such as age, aptitude, motivation, L2 disposition, etc. Among these factors, masculine gender roles stress (MGRS) that male learners possess is the least touched area that has been examined so far.MGRS can be defined as the traditional male role stress when the male learners feel the masculinity threat against their traditionally adopted masculinity norms. Traditional masculine norms include toughness, accuracy, completeness, and faultlessness. From this perspective, these norms are diametrically opposed to the language learning process since learning a language, by its nature, involves stages such as making mistakes and errors, not recalling words, pronouncing sounds incorrectly, creating wrong sentences, etc. Considering the potential impact of MGRS on the language learning process, the main purpose of this study is to investigate the mediating role of MGRS on the relationship between the EFL learners’ self-disclosure and English class anxiety. Data were collected from Turkish EFL learners (N=282) who study different majors in various state universities across Turkey. Data were analyzed by means of the Bootstraping method using the SPSS Process Macro plugin. The findings show that the indirect effect of self-disclosure level on the English Class Anxiety via MGRS was significant. We conclude that one of the reasons why Turkish EFL learners have English class anxiety might be the pressure that they feel because of their traditional gender role stress.

Keywords: masculine, gender role stress, english class anxiety, self-disclosure, masculinity norms

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Authors: Harun Rashid, Keerthi S. S. Atapaththu, Takashi Asaeda

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Cesium (Cs) induced growth and stress response of Nitella were studied after exposure to four concentration of the metal; i.e. 0 (control), 0.001, 0.01, and 0.1 ppm Cs in growth media. Each treatment with three replicates were randomly allocated to 12 glass beakers in a complete randomize design and the experiment was continued for 30 days. At the end of the experiment, shoot length, cesium content, total chlorophyll, and plant stress response were compared. Anti-oxidant enzyme activities (peroxidase, catalase, and ascorbic peroxidase) and the concentration of H2O2 were measured to check plant stress. The longest shoot was found in control treatment (0 ppm Cs) and the shoot length of plants exposed to 0.001 ppm was statistically similar to that of control. Concentration of cesium in plants grown at 0.001, 0.01, and 0.1 ppm were significantly higher than those in control treatments. The antioxidant enzymes activities of plants exposed to cesium were significantly higher than those grown without any Cs (control). An elevated level of H2O2 concentration was also observed in former groups of plants. Further, the reduction in chlorophyll concentration and chlorophyll fluorescence in response to cesium exposure indicated the chronically damaged photosynthetic efficiency in cesium stressed Nitella.

Keywords: antioxidant enzymes, cesium, growth, Nitella, oxidative stress

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Authors: Ngozi N. Sydney-Agbor, Chioma N. Ihegboro

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Stress and personality as factors influencing nurses’ aggressive behaviour were investigated. The participants comprised of one hundred and fifty nurses selected through convenience sampling technique from four (4) private hospitals in Imo State, Nigeria; namely: Eastern Summit Specialist Clinics and Maternity, St. David Hospital, New Cross Hospital, and Christian Teaching Hospital. The nurses were all females with ages between 20–35 and a mean age of 25.10 years and a standard deviation of 4.15. The participants were administered with Job Related Tension Scale, Type A Behaviour Scale and Buss- Perry Aggressive Behaviour Scale. Two hypotheses were postulated and tested. Cross- sectional survey and Regression Analysis were adopted as design and statistics respectively. Results showed that as stress increased, nurses aggression also increased. Personality also predicted nurses aggressive behaviour with Type As’ exhibiting higher aggression than Type Bs’.The study recommended that hospital management board should improve the welfare of the nurses and their morale should be boosted by involving them in policy-making concerning their welfare and care of their patients, this will help minimise situations capable of increasing aggressive behaviour. There should also be sensitization on the negative impact of aggressive behaviour to patients especially amongst the personality Type A’s who are more susceptible to aggression.

Keywords: aggressive behaviour, nurses, personality, stress

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Authors: Chao-xun Liu, Shi-hong Lu

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In spite of its importance to the aerospace and automobile industries, little or no attention has been devoted to the accurate modeling of the ultrasonic shot peening (USP) process. It is therefore the purpose of this study to conduct finite element analysis of the process using a realistic multiple pin impacts model with the explicit solver of ABAQUS. In this paper, we research the effect of several key parameters on the residual stress distribution within the target, including impact velocity, incident angle, friction coefficient between pins and target and impact number of times were investigated. The results reveal that the impact velocity and impact number of times have obvious effect and impacting vertically could produce the most perfect residual stress distribution. Then we compare the results with the date in USP experiment and verify the exactness of the model. The analysis of the multiple pin impacts date reveal the relationships between peening process parameters and peening quality, which are useful for identifying the parameters which need to be controlled and regulated in order to produce a more beneficial compressive residual stress distribution within the target.

Keywords: ultrasonic shot peening, finite element, multiple pins, residual stress, numerical simulation

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Authors: Aneeq Sarwar

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This study assesses the interaction between environmental and intellectual property policy on the rate of invention of environmental inventions and specifically tests for whether there is a synergy between stricter IP regimes and stronger environmental policies. The empirical analysis uses firm and industry-level data from seven OECD countries from 2009 to 2015. We also introduce a new measure of environmental inventions using a Natural Language Processing Topic Modelling technique. We find that intellectual property policy strictness demonstrates greater effectiveness in encouraging inventiveness in environmental inventions when used in combination with stronger environmental policies. This study contributes to existing literature in two ways. First, it devises a method for better identification of environmental technologies, we demonstrate how our method is more comprehensive than existing methods as we are better able to identify not only environmental inventions, but also major components of said inventions. Second, we test how various policy regimes affect the development of environmental technologies, we are the first study to examine the interaction of the environmental and intellectual property policy on firm level innovation.

Keywords: environmental economics, economics of innovation, environmental policy, firm level

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Authors: Seul Ki Min, Gwang Heum Yoon, Jung Hyun Joo, Hwa Sung Shin

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Cellular membrane distortion is known as a factor to change intracellular signaling. However, progress of relevant studies is difficult because there are no facilities that can control membrane distortion finely. In this study, we developed microfluidic device which can inflict mechanical stress on cell membrane of Chlamydomonas reinhardtii using regular height of the channels. And cellular physiological changes were analyzed from cells cultured in the device. Excessive calcium ion influx through into cytoplasm was induced from mechanical stress. The results revealed that compressed cells had up-regulated Mat3 mRNA which regulates cell size and cell cycle from a prolonged G1 phase. Additionally, TAG used for the production of biodiesel was raised rapidly from 4 h after compression. Taken together, membrane distortion can be considered as an attractive inducer for biofuel production.

Keywords: mechanical stress, membrane distortion, Chlamydomonas reinhardtii, deflagellation, cell cycle, lipid metabolism

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Authors: Shau-Ping Shiu, Shu-Ling Lin

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Pregnancy lead a process of changing in the endocrine system. Either pregnancy itself or the surrounding affect such as the attitude of family to the pregnant lady can bring lots of stress. Sever stress may lead pregnant women display serious mental problem such as mood swings, impulsivity, and abnormal behavior. A method of self management of stress(SMS) has been proved that help patient of cancer in release their stress. This study were going to use SMS to help pregnant women. Methods: In this study, 42 ladies in the first to third months of pregnancy process applied to join SMS of program have divided into 21 participants in both control and experimental group by draw. 24 sessions of Yoga program were conducted once a week for 6 months for experimental group. Verbatim used to gather more feedbacks from the interview followed by each Yoga sessions. Brief symptom Rating scale also conducted pre and post experiment for 42 participations. Results: Overall score of Brief Symptom Rating Scale reduced 17.82 points and suicide drop 9 points in experimental group, compared to the control group increasing 10.24 point of overall score and suicide add 7 points. Feedback from interviews showed participations improved in emotion, physical health and stress management. They indicated having more positive emotion daily, having better gastrointestinal peristalsis movement, releasing back tention, well weight control, reducing stress and changing the quality of interpersonal relationships. Conclusion: SMS of Yoga program in this study included four key training directions which were stimulation, relaxation, awareness and pranayama lead a great improvment of stress management for pregnant lady. Throughout this Yoga program, women learned to ignite eustress, remove distress, create calmness and breath slows down. As the result, Yoga program has helped women in experiment group lower their tension, and bring the extra benifits in emotion and relationships. It support women to overcome their pregnancy. Suggestion: An unexpected result of this study showed all participants had no morning sickness since they engaged in SMS program, and no one absent from course due to the benefits of it. We strongly suggest that SMS of Yoga program can be a add of medication for women in pregnancy, however, the position of Forward in the SMS sequence has been point out pressing participant’s stomach, which can be replace to Bridge position to comfort participants.

Keywords: self-management of stress(SMS), yoga program, pregnant women, early pregnancy

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Authors: Júlia Cristina Bonaldo, Christophe L. Martin, Martiniano Piccico, Keith Beale, Roop Kishore, Severine Romero-Baivier

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Refractory composite materials employed in steel casting applications are prone to cracking and material damage because of the very high operating temperature (thermal shock) and mismatched properties of the constituent phases. The fracture behavior of a model MgO-C composite refractory is investigated to quantify and characterize its thermal shock resistance, employing a cold crushing test and Brazilian test with fractographic analysis. The discrete element method (DEM) is used to generate numerical refractory composites. The composite in DEM is represented by an assembly of bonded particle clusters forming perfectly spherical aggregates and single spherical particles. For the stresses to converge with a low standard deviation and a minimum number of particles to allow reasonable CPU calculation time, representative volume element (RVE) numerical packings are created with various numbers of particles. Key microscopic properties are calibrated sequentially by comparing stress-strain curves from crushing experimental data. Comparing simulations with experiments also allows for the evaluation of crack propagation, fracture energy, and strength. The crack propagation during Brazilian experimental tests is monitored with digital image correlation (DIC). Simulations and experiments reveal three distinct types of fracture. The crack may spread throughout the aggregate, at the aggregate-matrix interface, or throughout the matrix.

Keywords: refractory composite, fracture mechanics, crack propagation, DEM

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Authors: Silindile Gumede, Amir Hossein Mohammadi, Mbuyu Germain Ntunka

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Goal 12 of the 17 Sustainable Development Goals (SDGs) encourages sustainable consumption and production patterns. This necessitates achieving the environmentally safe management of chemicals and all wastes throughout their life cycle and the proper disposal of pollutants and toxic waste. Fluid catalytic cracking (FCC) catalysts are widely used in the refinery to convert heavy feedstocks to lighter ones. During the refining processes, the catalysts are deactivated and discarded as hazardous toxic solid waste. Spent catalysts (SC) contain high-cost metal, and the recovery of metals from SCs is a tactical plan for supplying part of the demand for these substances and minimizing the environmental impacts. Leaching followed by solvent extraction, has been found to be the most efficient method to recover valuable metals with high purity from spent catalysts. However, the use of inorganic acids during the leaching process causes a secondary environmental issue. Therefore, it is necessary to explore other alternative efficient leaching agents that are economical and environmentally friendly. In this study, the waste catalyst was collected from a domestic refinery and was characterised using XRD, ICP, XRF, and SEM. Response surface methodology (RSM) and Box Behnken design were used to model and optimize the influence of some parameters affecting the acidic leaching process. The parameters selected in this investigation were the acid concentration, temperature, and leaching time. From the characterisation results, it was found that the spent catalyst consists of high concentrations of Vanadium (V) and Nickel (Ni); hence this study focuses on the leaching of Ni and V using a biodegradable acid to eliminate the formation of the secondary pollution.

Keywords: eco-friendly leaching, optimization, metal recovery, leaching

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Authors: Sanat K. Dash, Rama S. Verma, Sarit K. Das

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A logarithmic microfluidic shear device was designed and fabricated for cellular mechanotransduction studies. The device contains four cell culture chambers in which flow was modulated to achieve a logarithmic increment. Resistance values were optimized to make the device compact. The network of resistances was developed according to a unique combination of series and parallel resistances as found via optimization. Simulation results done in Ansys 16.1 matched the analytical calculations and showed the shear stress distribution at different inlet flow rates. Fabrication of the device was carried out using conventional photolithography and PDMS soft lithography. Flow profile was validated taking DI water as working fluid and measuring the volume collected at all four outlets. Volumes collected at the outlets were in accordance with the simulation results at inlet flow rates ranging from 1 ml/min to 0.1 ml/min. The device can exert fluid shear stresses ranging four orders of magnitude on the culture chamber walls which will cover shear stress values from interstitial flow to blood flow. This will allow studying cell behavior in the long physiological range of shear stress in a single run reducing number of experiments.

Keywords: microfluidics, mechanotransduction, fluid shear stress, physiological shear

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Authors: Stephen Adeniyi Adefegha, Vitor Mostardeiro, Vera Maria Morsch, Ademir F. Morel, Ivana Beatrice Manica Da Cruz, Sabrina Somacal Maria Rosa Chitolina Schetinger

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Moringa stenopetala is often consumed as food and used in folkloric medicine for the management of several diseases. Purpose: This study was set up in order to assess the effect of aqueous extract of Moringa stenopetala on cell viability and oxidative stress biomarkers in BV-2 microglial cells. Aqueous extracts of M. stenopetala were prepared, lyophilized and reconstituted in 0.5% dimethylsulphoxide (DMSO). Cells were treated with M. stenopetala extracts (0.1 - 100 µg/ml) for cell viability and nitric oxide (NO) production tests. However, M. stenopetala extract (50 µg/ml) was used in the treatment of cells for the determination of protein carbonyl content and reactive oxygen species (ROS) level. Incubation of BV-2 microglia cell with M. stenopetala extract maintained cell viability, diminished NO and ROS levels, and reduced protein carbonyl contents Chlorogenic acid, rutin, kaempferol and quercetin derivatives were the main phenolic compounds identified in M. stenopetala leaf extract. These phenolic compounds present in M. stenopetala may be responsible for the mitigation of oxidative stress in BV-2 microglial cells.

Keywords: oxidative stress, BV-2 microglial cell, Moringa stenopetala, cell viability, antioxidant

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Authors: Usha Barahmand, Ruhollah Heydari Sheikh Ahmad, Sara Alaie Khoraem

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Introduction: The association of epilepsy with several psychological disorders and reduced quality of life has long been recognized. The present study aimed at comparing the personality profiles, quality of life and symptomatology of anxiety and depression in patients with epilepsy and healthy controls. Materials and Methods: Forty seven patients (29 men and 18 women) with diagnosed epilepsy participated in this study. Forty seven healthy controls who matched the patients in age and gender were also recruited. The participants’ personality and psychological profiles were assessed using the Depression, Anxiety, and Stress Scale (DASS-21), the Short-Form Health Survey (SF-36) and the HEXACO Personality Inventory (HEXACO-PI). Scoring algorithms were applied to the SF-36 produce the physical and mental component scores (PCS and MCS). Results: There were statistically significant differences in the total SF-36 score, anxiety, depression and stress scores of the DASS-21 between patients and controls. Anxiety, stress and depression scores significantly correlated inversely with the PCS and MCS. Data analysis showed that females had higher depression scores than males in both patients and controls, while males in both groups scored higher on stress. Patients’ personality scores were also different from those reported by controls on emotional, agreeableness and extroversion. Patients scored higher on emotionality, and lower on agreeableness and extraversion. Patients also scored lower on indices of quality of life. Regression analysis revealed that emotionality, anxiety, stress and MCS accounted for a significant proportion of the variance in severity of epileptic seizures. Conclusion: Stressful situations and psychological conditions as well as the personality trait of neuroticism were related to the occurrence of recurrent epileptic seizures.

Keywords: anxiety, depression, epilepsy, neuroticism, personality, quality of life, stress

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Authors: Duane Booysen, Ashraf Kagee

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There is a high prevalence of violent crime and trauma exposure in South African society. Considering the prevalence of continuous violent crimes and traumatization in South Africa, the public mental health sector is required to combat the burgeoning effect of traumatic stress in South Africa. Trauma counselors, especially, provide important mental health services at primary health care to persons affected by traumatic events. Therefore, the evaluation and implementation of evidence-based trauma therapies is essential at a primary health care level in treating traumatic stress. A single-case design was used to evaluate the treatment effect of a Brief Trauma Treatment Programme treating persons who present with symptoms of posttraumatic stress disorder at a primary care trauma centre in Cape Town, South Africa. The sample consisted of six adult participants who presented with symptoms of posttraumatic stress and were assessed at baseline, during treatment, post-intervention and at 3-month follow. All participants received six sessions of trauma therapy. Assessment measures included the posttraumatic stress disorder symptom scale interviews for Diagnostic and Statistical Manual fifth edition (DSM5), the posttraumatic disorder checklist for DSM5, Beck Depression Inventory and Beck Anxiety Inventory. Results demonstrate that participants had noticeable reduced symptoms for traumatic stress, anxiety and depression despite living in contexts of violent crime and trauma. In conclusion, the article critically reflects on the need to evaluate and implement evidence-based treatments for the South African context, and how evidence-based treatments are used in developing socio-economic and cultural diverse contexts with continuous levels of violence and traumatization.

Keywords: psychological interventions, public mental health, traumatic stress, single-case design

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Authors: Ayman El Sabagh, Celaleddin Barutçular, Hirofumi Saneoka

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Drought is one of the most serious problems posing a grave threat to cereals production including maize. Maize improvement in drought-stress tolerance poses a great challenge as the global need for food and bio-enegry increases. Thus, the current study was planned to explore the variations and determine the performance of target traits of maize hybrids at grain growth stage under drought conditions during 2014 under Adana, Mediterranean climate conditions, Turkey. Maize hybrids (Sancia, Indaco, 71May69, Aaccel, Calgary, 70May82, 72May80) were evaluated under (irrigated and water stress). Results revealed that, grain yield and yield traits had a negative effects because of water stress conditions compared with the normal irrigation. As well as, based on the result under normal irrigation, the maximum biological yield and harvest index were recorded. According to the differences among hybrids were found that, significant differences were observed among hybrids with respect to yield and yield traits under current research. Based on the results, grain weight had more effect on grain yield than grain number during grain filling growth stage under water stress conditions. In this concern, according to low drought susceptibility index (less grain yield losses), the hybrid (Indaco) was more stable in grain number and grain weight. Consequently, it may be concluded that this hybrid would be recommended for use in the future breeding programs for production of drought tolerant hybrids.

Keywords: drought susceptibility index, grain growth, grain yield, maize, water stress

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Authors: M. Szechynska-Hebda, M. Sobczak, E. Rozanska, J. Troczynska, Z. Banaszak, N. Hordyńska, M. Dyda, M. Wedzony

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Chloroplasts, as essential organelles for photosynthesis, play a critical role in plant development. However, disturbances in the proper functioning of chloroplasts, in the extreme case manifesting as albinism of tissues and whole plants, are a phenomenon often occurring in conditions deviating from natural (e.g., in vitro cultures applied in breeding programs). Using whole-transcriptome analysis (RNA-Seq) together with light, fluorescent and electron microscopy, it was shown, that development of chloroplasts and formation of green or albino plants in the androgenesis process are genotype-dependent; however, they could be modulated by sub-optimal temperature treatment. The reprogramming of the microspore development from gametophytic to sporophytic, and then regeneration of green plant can be positively regulated by cold stress (4 ⁰C). A high temperature stress (32 ⁰C) can induce androgenesis, but it is a factor negatively influencing green plant regeneration (promoting albinism). A similar effect on microspores, androgenesis, and subsequent chloroplast formation, is elicited as a result of postponing the date of spike collection from spring to summer in field conditions (natural temperature rise). It is determined in both environmental or genotypic manner. The delay of the sowing date (environmental effect) or growing of late genotypes (genotypic effect) result in spike maturation at higher temperatures and significantly enhance albino plant formation in androgenesis process. Such a temperature system (4 ⁰C vs. 32 ⁰C) was used to study the chloroplast biogenesis process in wheat and triticale. It was shown, that efficiency of physiological processes differentiates microspore development during cold reprograming in genotypes susceptible and resistant to androgenesis. Moreover, a great variation in developmental stages of the microspores in one anther is observed for susceptible genotypes. Microspores that are more physiologically active under cold conditions can activate signaling pathways and processes, which provide an appropriate supply of metabolites to cell compartments. This, in turn, fully correlates with the genotype-dependent efficiency of chloroplast formation (or different types of plastid) at particular steps of androgenesis. The effect obtained after applying a high temperature stress is different. High temperature causes a significant acceleration of microspore development and less variation in developmental stages at the end of the treatment. Therefore, the developmental diversity of the microspores in one anther seems to be a critical factor for subsequent cell and chloroplast differentiation. The work was financed by Ministry of Agriculture and Rural Development within Program: 'Biological Progress in Plant Production', project no HOR.hn.802.15.2018

Keywords: androgenesis, chloroplast biogenesis, temperature stress, wheat

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Authors: Lee Jin-Eui, Kim Jin-OK, Han Seung-Hoon, Kim Nam-Jo

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Recently, there has been a growing interest in wellbeing where individuals pursue a healthy life. About the half of world population is living in cities, and the urban environment is negatively affecting the mental health of modern people. The stress level of urban dwellers continues to increase, and they pursue nature-based recreation activities to relieve their stresses. It was found that activities in green spaces are improving concentration, relieving mental stress, and positively affecting physical activities and social relationship, thus enhancing the quality of life. For that reason, studies have been continuously conducted on the role of nature, which is a green space for pursuing health and relieving the stress of urban dwellers. Therefore, this study investigated the effect of experiencing a restoration from nature-based outdoor recreation activities of urban dwellers on their quality of life for the groups with high and low-stress levels. The results of the analysis against visitors who trekked and climbed Mt. Bukhan National Park in Seoul, South Korea showed that the effect of perceiving restorative environment on relaxation, calmness and subjective vitality, and the effect of relaxation and calmness on the quality of life were similar in both groups. However, it was found that subjective vitality affected the quality of life in the group with the high-stress group, while it did not show a significant result in the low-stress group. This is because the high-stress group increased their belief in the future and themselves and vitality through nature-based outdoor activities, which in turn affected their quality of life, while people in the low-stress group normally have subjective vitality in their daily lives, not affected by nature-based outdoor recreation. This result suggests that urban dwellers feel relaxed and calm through nature-based outdoor recreation activities with perceived restorative environment, and such activities enhance their quality of life. Therefore, a wellbeing policy is needed to enhance the quality of life of citizens by creating green spaces in city centers for the promotion of public health.

Keywords: healing tourism, nature-based outdoor recreation, perceived restorative environment, quality of life

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Authors: Abdoulnabi Tavangari, Nasim Salehzadeh

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We presume a cylindrical medium that is under a uniform loading and there is a penny shaped crack located in the center of cylinder. In the crack growth analysis, the Stress Intensity Factor (SIF) is a fundamental prerequisite. In the present study, according to the RITZ method and by considering a cylindrical coordinate system as the main coordinate and a local polar coordinate, the mode-I SIF of threedimensional penny-shaped crack is obtained. In this method the unknown coefficients will be obtained with minimizing the potential energy that is including the strain energy and the external force work. By using the hook's law, stress fields will be obtained and then by using the Irvine equations, the amount of SIF will be obtained near the edge of the crack. This question has been solved for extreme medium in the Tada handbook and the result of the present research has been compared with that.

Keywords: three-dimensional cracks, penny-shaped crack, stress intensity factor, fracture mechanics, Ritz method

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Authors: Aymen Arfaoui, Abdelkader Soumaya

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The Messalla-Ressas-Bou Kornine (MRB) and Hammamet Korbous (HK) major trending North-South fault zones provide a good opportunity to show the effects of the Eocene compressive phase in northern Tunisia. They acted as paleogeographical boundaries during the Mesozoic and belonged to a significant strike-slip corridor called the «North-South Axis,» extending from the Saharan platform at the South to the Gulf of Tunis at the North. Our study area is situated in a relay zone between two significant strike-slip faults (HK and MRB), separating the Atlas domain from the Pelagian Block. We used a multidisciplinary approach, including fieldwork, stress inversion, and geophysical profiles, to argue the shortening event that affected the study region. The MRB and HK contractional duplex is a privileged area for a local stress field and stress nucleation. The stress inversion of fault slip data reveals an Eocene compression with NW-SE trending SHmax, reactivating most of the ancient Mesozoic normal faults in the region. This shortening phase is represented in the MRB belt by an angular unconformity between the Upper Eocene over various Cretaceous strata. The stress inversion data reveal a compressive tectonic with an average NW-SE trending Shmax. The major N-S faults are reactivated under this shortening as sinistral oblique faults. The orientation of SHmax deviates from NW-SE to E-W near the preexisting deep faults of MRB and HK. This E-W stress direction generated the emerging overlap of Ressas-Messella and blind thrust faults in the Cretaceous deposits. The connection of the sub-meridian reverse faults in depth creates "flower structures" under an E-W local compressive stress. In addition, we detected a reorientation of the SHmax into an N-S direction in the central part of the MRB - HK contractional duplex, creating E-W reverse faults and overlapping zones. Finally, the Eocene compression constituted the first major tectonic phase which inverted the Mesozoic preexisting extensive fault system in Northern Tunisia.

Keywords: Tunisia, eocene compression, tectonic stress field, Bou Kornine-Ressas-Messella

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Authors: Anton G. Kalmykov, Andrew Yu. Bychkov, Georgy A. Kalmykov

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Nowadays, most oil reserves in Russia and all over the world are hard to recover. That is the reason oil companies are searching for new sources for hydrocarbon production. One of the sources might be high-carbon formations with unconventional reservoirs. Bazhenov formation is a huge source rock formation located in West Siberia, which contains unconventional reservoirs on some of the areas. These reservoirs are formed by secondary processes with low predicting ratio. Only one of five wells is drilled through unconventional reservoirs, in others kerogen has low thermal maturity, and they are of low petroliferous. Therefore, there was a request for tertiary methods for in-situ cracking of kerogen and production of oil. Laboratory experiments of Bazhenov formation rock hydrous pyrolysis were used to investigate features of the oil generation process. Experiments on Bazhenov rocks with a different mineral composition (silica concentration from 15 to 90 wt.%, clays – 5-50 wt.%, carbonates – 0-30 wt.%, kerogen – 1-25 wt.%) and thermal maturity (from immature to late oil window kerogen) were performed in a retort under reservoir conditions. Rock samples of 50 g weight were placed in retort, covered with water and heated to the different temperature varied from 250 to 400°C with the durability of the experiments from several hours to one week. After the experiments, the retort was cooled to room temperature; generated hydrocarbons were extracted with hexane, then separated from the solvent and weighted. The molecular composition of this synthesized oil was then investigated via GC-MS chromatography Characteristics of rock samples after the heating was measured via the Rock-Eval method. It was found, that the amount of synthesized oil and its composition depending on the experimental conditions and composition of rocks. The highest amount of oil was produced at a temperature of 350°C after 12 hours of heating and was up to 12 wt.% of initial organic matter content in the rocks. At the higher temperatures and within longer heating time secondary cracking of generated hydrocarbons occurs, the mass of produced oil is lowering, and the composition contains more hydrocarbons that need to be recovered by catalytical processes. If the temperature is lower than 300°C, the amount of produced oil is too low for the process to be economically effective. It was also found that silica and clay minerals work as catalysts. Selection of heating conditions allows producing synthesized oil with specified composition. Kerogen investigations after heating have shown that thermal maturity increases, but the yield is only up to 35% of the maximum amount of synthetic oil. This yield is the result of gaseous hydrocarbons formation due to secondary cracking and aromatization and coaling of kerogen. Future investigations will allow the increase in the yield of synthetic oil. The results are in a good agreement with theoretical data on kerogen maturation during oil production. Evaluated trends could be tooled up for in-situ oil generation by shale rocks thermal action.

Keywords: Bazhenov formation, fossil fuels, hydropyrolysis, synthetic oil

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Authors: Lele Dominic Dummene

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Economic development and environmental development have been a long-lasting debate between capitalist and environmentalist. It is also seen as a debate between modernisation, globalisation at one end, and environmental justice at the other end. Our society today is moving rapidly towards development and increased industrial revolutions, and globalisation. Indigenous communities in Ogoniland are also experiencing such development due to multinationals’ exploration of crude oil in the communities. The oil exploration activities have caused environmental, socio-economic, health, and political problems in indigenous communities in Ogoniland. These issues require depth understanding from all sectors (public, government, and corporate sectors) to address them. Hence, this paper presents the types of environmental education programs used in indigenous communities in Ogoniland to address environmental issues and other problems caused by oil exploration in Ogoniland, Nigeria. These environmental education programs contributes to environmental policy creation, development of environmental curriculum, and pragmatic actions towards mitigating environmental degradation and related environmental socio-economic and political issues in indigenous communities.

Keywords: environmental education, indigenous communities, environmental problems, ogoniland

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Authors: Tetsya Sok, Seong Jae Hong, Young Kyu Kim, Seung Woo Lee

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The temperature distribution for asphalt concrete (AC)-Concrete composite pavement is one of main influencing factor that affects to performance life of pavement. The temperature gradient in concrete slab underneath the AC layer results the critical curling stress and lead to causes de-bonding of AC-Concrete interface. These stresses, when enhanced by repetitive axial loadings, also contribute to the fatigue damage and eventual crack development within the slab. Moreover, the temperature change within concrete slab extremely causes the slab contracts and expands that significantly induces reflective cracking in AC layer. In this paper, the numerical prediction of pavement temperature was investigated using one-dimensional finite different method (FDM) in fully explicit scheme. The numerical predicted model provides a fundamental and clear understanding of heat energy balance including incoming and outgoing thermal energies in addition to dissipated heat in the system. By using the reliable meteorological data for daily air temperature, solar radiation, wind speech and variable pavement surface properties, the predicted pavement temperature profile was validated with the field measured data. Additionally, the effects of AC thickness and daily air temperature on the temperature profile in underlying concrete were also investigated. Based on obtained results, the numerical predicted temperature of AC-Concrete composite pavement using FDM provided a good accuracy compared to field measured data and thicker AC layer significantly insulates the temperature distribution in underlying concrete slab.

Keywords: asphalt concrete, finite different method (FDM), curling effect, heat transfer, solar radiation

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Authors: Jana Hodna, Bozena Vacenovska, Vit Petranek

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The paper is focused on the identification of limiting environmental factors of individual industrial floors on which newly developed polymer protection and repair systems with the use of secondary raw materials will be used. These mainly include floors with extreme stresses and special requirements for materials used. In relation to the environment of a particular industrial floor, it is necessary to ensure, for example, chemical stability, resistance to higher temperatures, resistance to higher mechanical stress, etc. for developed materials, which is reflected in the demands for the developed material systems. The paper describes individual environments and, in relation to them, also requirements for individual components of the developed materials and for the developed materials as a whole.

Keywords: limits, environment, polymer, industrial floors, recycling, secondary raw material, protective system

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Authors: Ligia Nascimento, Manuela Faia Correia

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Nowadays, Information and Communication Technologies (ICT) are embedded in most professions. Technostress - or stress induced by the use of ICTs, has been studied in various sectors of activity and in different geographical areas, mainly from the perspective of its harmful impacts. In the context of work, the technological contexts capable of causing stress have been examined in-depth, as well as the type of individuals most likely to experience its negative effects. However, new lines of the research argue that the stress generated by the use of ICTs may not necessarily be detrimental (technodistress), admitting that, in contrast, and in addition, it may actually be beneficial to organizations and their employees (technoeustress). Any measures that succeed in reducing technodistress do not necessarily lead to the creation of technoeustress, justifying the study of this phenomenon in a focused and independent manner. Adopting the transactional model of stress as the basic theoretical framework, an ongoing research project aims to study technoeustress independently. Given the role played in the qualification and progress of society and the economy, it becomes particularly critical to care for the well-being of the higher education teacher. Particularly in recent times, when teleworking is prevalent, these professionals have made a huge, compulsive effort to adapt to a new teaching reality. Rather than limiting itself to mitigating adverse effects of ICT use, which featured earlier approaches, the present study seeks to understand how to activate the positive side of technostress in higher education teachers in order to obtain favorable personal and organizational outcomes from ICT use at work. The research model seeks to understand, upstream, the ICT characteristics that increase the perception of technoeustress among higher education teachers, studying the direct and moderating effects of individual and organizational variables and, downstream, the impacts that technoeustress has on job satisfaction and performance. This research contributes both to expanding the knowledge of the technostress phenomenon and to identify possible recommendations for management.

Keywords: higher education teachers, ICT, stress, technoeustress

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Authors: Nishant Shrivastava, D. K. Sehgal

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In Finite Element Technique nodal stresses are calculated through displacement as nodes. In this process, the displacement calculated at nodes is sufficiently good enough but stresses calculated at nodes are not sufficiently accurate. Therefore, the accuracy in the stress computation in FEM models based on the displacement technique is obviously matter of concern for computational time in shape optimization of engineering problems. In the present work same is focused to find out unique points within the element as well as the boundary of the element so, that good accuracy in stress computation can be achieved. Generally, major optimal stress points are located in domain of the element some points have been also located at boundary of the element where stresses are fairly accurate as compared to nodal values. Then, it is subsequently concluded that there is an existence of unique points within the element, where stresses have higher accuracy than other points in the elements. Therefore, it is main aim is to evolve a generalized procedure for the determination of the optimal stress location inside the element as well as at the boundaries of the element and verify the same with results from numerical experimentation. The results of quadratic 9 noded serendipity elements are presented and the location of distinct optimal stress points is determined inside the element, as well as at the boundaries. The theoretical results indicate various optimal stress locations are in local coordinates at origin and at a distance of 0.577 in both directions from origin. Also, at the boundaries optimal stress locations are at the midpoints of the element boundary and the locations are at a distance of 0.577 from the origin in both directions. The above findings were verified through experimentation and findings were authenticated. For numerical experimentation five engineering problems were identified and the numerical results of 9-noded element were compared to those obtained by using the same order of 25-noded quadratic Lagrangian elements, which are considered as standard. Then root mean square errors are plotted with respect to various locations within the elements as well as the boundaries and conclusions were drawn. After numerical verification it is noted that in a 9-noded element, origin and locations at a distance of 0.577 from origin in both directions are the best sampling points for the stresses. It was also noted that stresses calculated within line at boundary enclosed by 0.577 midpoints are also very good and the error found is very less. When sampling points move away from these points, then it causes line zone error to increase rapidly. Thus, it is established that there are unique points at boundary of element where stresses are accurate, which can be utilized in solving various engineering problems and are also useful in shape optimizations.

Keywords: finite elements, Lagrangian, optimal stress location, serendipity

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Authors: Ali Ashtiani, Hamid Shirazi

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This paper reviews the status of existing practice and research related to measuring pavement cracking and using crack density as a pavement surface evaluation protocol. Crack density for pavement evaluation is currently not widely used within the airport community and its use by the highway community is limited. However, surface cracking is a distress that is closely monitored by airport staff and significantly influences the development of maintenance, rehabilitation and reconstruction plans for airport pavements. Therefore crack density has the potential to become an important indicator of pavement condition if the type, severity and extent of surface cracking can be accurately measured. A pavement distress survey is an essential component of any pavement assessment. Manual crack surveying has been widely used for decades to measure pavement performance. However, the accuracy and precision of manual surveys can vary depending upon the surveyor and performing surveys may disrupt normal operations. Given the variability of manual surveys, this method has shown inconsistencies in distress classification and measurement. This can potentially impact the planning for pavement maintenance, rehabilitation and reconstruction and the associated funding strategies. A substantial effort has been devoted for the past 20 years to reduce the human intervention and the error associated with it by moving toward automated distress collection methods. The automated methods refer to the systems that identify, classify and quantify pavement distresses through processes that require no or very minimal human intervention. This principally involves the use of a digital recognition software to analyze and characterize pavement distresses. The lack of established protocols for measurement and classification of pavement cracks captured using digital images is a challenge to developing a reliable automated system for distress assessment. Variations in types and severity of distresses, different pavement surface textures and colors and presence of pavement joints and edges all complicate automated image processing and crack measurement and classification. This paper summarizes the commercially available systems and technologies for automated pavement distress evaluation. A comprehensive automated pavement distress survey involves collection, interpretation, and processing of the surface images to identify the type, quantity and severity of the surface distresses. The outputs can be used to quantitatively calculate the crack density. The systems for automated distress survey using digital images reviewed in this paper can assist the airport industry in the development of a pavement evaluation protocol based on crack density. Analysis of automated distress survey data can lead to a crack density index. This index can be used as a means of assessing pavement condition and to predict pavement performance. This can be used by airport owners to determine the type of pavement maintenance and rehabilitation in a more consistent way.

Keywords: airport pavement management, crack density, pavement evaluation, pavement management

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Authors: Petra Hurbišová, Monika Davidová

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The article deals with the readiness of military professionals for challenging situations. It discusses higher requirements on the psychical endurance of military professionals arising from the specific nature of the military occupation, which is typical for being very difficult to maintain regularity, which is in accordance with the hygiene of work alternated by relaxation. The soldier must be able to serve in the long term and constantly intense performance that goes beyond human tolerance to stress situations. A challenging situation is always associated with overcoming difficulties, obstacles and complicated circumstances or using unusual methods, ways and means to achieve the desired (expected) objectives, performing a given task or satisfying an important need. This paper describes the categories of challenging situations, their classification and characteristics. Attention is also paid to the formation of personality in challenging situations, coping with stress in challenging situations, Phases of solutions of stressful situations, resistance to challenging life situations and its factors. Finally, the article is focused on increasing the readiness of military professionals for challenging situations.

Keywords: coping, challenging situations, stress, stressful situations, military professionals, resilience

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Authors: Vincent Iacobellis, Kamran Behdinan

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A finite element cohesive zone model is used to predict the temperature dependent material properties of a polyimide matrix composite with unidirectional carbon fiber arrangement. The cohesive zone parameters have been obtained from previous research involving an atomistic-to-continuum multiscale simulation of the fiber-matrix interface using the bridging cell multiscale method. The goal of the research was to both investigate the effect of temperature change on the composite behavior with respect to transverse loading as well as the validate the use of cohesive parameters obtained from atomistic-to-continuum multiscale modeling to predict fiber-matrix interfacial cracking. From the multiscale model cohesive zone parameters (i.e. maximum traction and energy of separation) were obtained by modeling the interface between the coarse-grained polyimide matrix and graphite based carbon fiber. The cohesive parameters from this simulation were used in a cohesive zone model of the composite microstructure in order to predict the properties of the macroscale composite with respect to changes in temperature ranging from 21 ˚C to 316 ˚C. Good agreement was found between the microscale RUC model and experimental results for stress-strain response, stiffness, and material strength at low and high temperatures. Examination of the deformation of the composite through localized crack initiation at the fiber-matrix interface also agreed with experimental observations of similar phenomena. Overall, the cohesive zone model was shown to be both effective at modeling the composite properties with respect to transverse loading as well as validated the use of cohesive zone parameters obtained from the multiscale simulation.

Keywords: cohesive zone model, fiber-matrix interface, microscale damage, multiscale modeling

Procedia PDF Downloads 467