Search results for: thermal stress response

Authors: Milad Golshan, Wim Zeiler

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During the last decade research was done to clarify the importance of good Indoor Air Quality in schools. As a result, measurements were undertaken in different types of schools to see whether naturally ventilated schools could provide adequate indoor conditions. Also, a comparison was made between schools with hybrid ventilation and those with complete mechanical ventilation systems. Recently a large survey was undertaken at 60 schools to establish the average current situation of schools in the Netherlands. The results of the questionnaires were compared with those of earlier measured schools. This allowed us to compare different types of schools as well as schools of different periods. Overall it leads to insights about the actual current perceived quality by the teachers as well as the pupils and enables to draw some conclusions about the typical performances of specific types of school ventilation systems. Also, the perceived thermal comfort and controllability were researched. It proved that in around 50% of the schools there were major complains about the indoor air quality causing concentration problems and headaches by the pupils at the end of class. Although the main focus of the latest research was focused more on the quality of recently finished nearly Zero Energy schools, this research showed that especially the main focus school be on the renovation and upgrading of the existing 10.000 schools in the Netherlands.

Keywords: school ventilation, indoor air quality, perceiver thermal comfort, comparison different types

Procedia PDF Downloads 221

Authors: Ahmed Elkholy

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Most power transmission cases use gearing in general, and worm gearing, in particular for energy utilization. Therefore, designing gears for minimum weight and maximum power transmission is the main target of this study. In this regard, a new approach has been developed to estimate the load share and stress distribution of worm gear sets. The approach is based upon considering the instantaneous tooth meshing stiffness where the worm gear drive was modelled as a series of spur gear slices, and each slice was analyzed separately using a well-established criteria. By combining the results obtained for all slices, the entire worm gear set loading and stressing was determined. The geometric modelling method presented, allows tooth elastic deformation and tooth root stresses of worm gear drives under different load conditions to be investigated. On the basis of the method introduced in this study, the instantaneous meshing stiffness and load share were obtained. In comparison with existing methods, this approach has both good analytical accuracy and less computing time.

Keywords: gear, load/stress distribution, worm, wheel, tooth stiffness, contact line

Procedia PDF Downloads 422

Authors: Pisut Boonkaew, Jatuporn Thongsri

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In hard disk drive manufacturing industry, the process of reducing an unnecessary part and qualifying the quality of part before assembling is important. Thus, clamp was designed and fabricated as a fixture for holding in testing process. Basically, testing by trial and error consumes a long time to improve. Consequently, the simulation was brought to improve the part and reduce the time taken. The problem is the present clamp has a low life expectancy because of the critical stress that occurred. Hence, the simulation was brought to study the behavior of stress and compressive force to improve the clamp expectancy with all probability of designs which are present up to 27 designs, which excluding the repeated designs. The probability was calculated followed by the full fractional rules of six sigma methodology which was provided correctly. The six sigma methodology is a well-structured method for improving quality level by detecting and reducing the variability of the process. Therefore, the defective will be decreased while the process capability increasing. This research focuses on the methodology of stress and fatigue reduction while compressive force still remains in the acceptable range that has been set by the company. In the simulation, ANSYS simulates the 3D CAD with the same condition during the experiment. Then the force at each distance started from 0.01 to 0.1 mm will be recorded. The setting in ANSYS was verified by mesh convergence methodology and compared the percentage error with the experimental result; the error must not exceed the acceptable range. Therefore, the improved process focuses on degree, radius, and length that will reduce stress and still remain in the acceptable force number. Therefore, the fatigue analysis will be brought as the next process in order to guarantee that the lifetime will be extended by simulating through ANSYS simulation program. Not only to simulate it, but also to confirm the setting by comparing with the actual clamp in order to observe the different of fatigue between both designs. This brings the life time improvement up to 57% compared with the actual clamp in the manufacturing. This study provides a precise and trustable setting enough to be set as a reference methodology for the future design. Because of the combination and adaptation from the six sigma method, finite element, fatigue and linear regressive analysis that lead to accurate calculation, this project will able to save up to 60 million dollars annually.

Keywords: clamp, finite element analysis, structural, six sigma, linear regressive analysis, fatigue analysis, probability

Procedia PDF Downloads 235

Authors: Mina Ganji Morad, Maziar Azadisoleimanieh, Sina Ganji Morad

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A green roof is formed by green plants alive and has many positive impacts in the regional climatic, as well as indoor. Green roof system to prevent solar radiation plays a role in the cooling space. The cooling is done by reducing thermal fluctuations on the exterior of the roof and by increasing the roof heat capacity which cause to keep the space under the roof cool in the summer and heating rate increases during the winter. A roof garden is one of the recommended ways to reduce energy consumption in large cities. Despite the scale of the city green roofs have effective functions, such as beautiful view of city and decontaminating the urban landscape and reduce mental stress, and in an exchange of energy and heat from outside to inside spaces. This article is based on a review of 20 articles and 10 books and valid survey results on the positive effects of green roofs to prevent energy waste in the building. According to these publications, three of the conventional roof, green roof typical and green roof with certain administrative details (layers of glass) and the use of resistant plants and shrubs have been analyzed and compared their heat transfer. The results of these studies showed that one of the best green roof systems for mountainous climate is tree and shrub system that in addition to being resistant to climate change in mountainous regions, will benefit from the other advantages of green roof. Due to the severity of climate change in mountainous areas it is essential to prevent the waste of buildings heating and cooling energy. Proper climate design can greatly help to reduce energy.

Keywords: green roof, heat transfer, reducing energy consumption, mountainous areas, sustainable architecture

Procedia PDF Downloads 397

Authors: M. Sneha Reddy, M. Arun Kumar, V. Kameswara Rao

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Chromites are binary transition metal oxides with a general formula of ACr₂O₄, where A = Mn²⁺, Fe²⁺, Co²⁺, Ni²⁺, and Cu²⁺. Chromites have a normal-type spinel structure with interesting applications in the areas of applied physics, material sciences, and geophysics. They have attracted great consideration because of their unique physicochemical properties and tremendous technological applications in nanodevices, sensor elements, and high-temperature ceramics with useful optical properties. Copper chromite is one of the most efficient spinel oxides, having pronounced commercial application as a catalyst in various chemical reactions like oxidation, hydrogenation, alkylation, dehydrogenation, decomposition of organic compounds, and hydrogen production. Apart from its usage in chemical industries, CuCr₂O₄ finds its major application as a burn rate modifier in solid propellant processing for space launch vehicles globally. Herein we synthesized the nanoparticles of copper chromite using the co-precipitation method. The synthesized nanoparticles were characterized by XRD, TEM, SEM, BET, and TG-DTA. The synthesized nanoparticles of copper chromites were used as a catalyst for the thermal decomposition of various high-energy materials.

Keywords: copper chromite, coprecipitation method, high energy materials, catalytic thermal decomposition

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Authors: Reza Hadjiaghaie Vafaie, Sevda Givtaj

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Automation and control of biological samples and solutions at the microscale is a major advantage for biochemistry analysis and biological diagnostics. Despite the known potential of miniaturization in biochemistry and biomedical applications, comparatively little is known about fluid automation and control at the microscale. Here, we study the electric field effect inside a fluidic channel and proper electrode structures with different patterns proposed to form forward, reversal, and rotational flows inside the channel. The simulation results confirmed that the ac electro-thermal flow is efficient for the control and automation of high-conductive solutions. In this research, the fluid pumping and mixing effects were numerically studied by solving physic-coupled electric, temperature, hydrodynamic, and concentration fields inside a microchannel. From an experimental point of view, the electrode structures are deposited on a silicon substrate and bonded to a PDMS microchannel to form a microfluidic chip. The motions of fluorescent particles in pumping and mixing modes were captured by using a CCD camera. By measuring the frequency response of the fluid and exciting the electrodes with the proper voltage, the fluid motions (including pumping and mixing effects) are observed inside the channel through the CCD camera. Based on the results, there is good agreement between the experimental and simulation studies.

Keywords: microfluidic, nano/micro actuator, AC electrothermal, Reynolds number, micropump, micromixer, microfabrication, mass transfer, biomedical applications

Procedia PDF Downloads 59

Authors: W. Badla

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A significant portion of the buildings constructed in Algeria is structural frames with infill panels which are usually considered as non structural components and are neglected in the analysis. However, these masonry panels tend to influence the structural response. Thus, these structures can be regarded as seismic risk buildings, although in the Algerian seismic code there is little guidance on the seismic evaluation of infilled frame buildings. In this study, three RC frames with 2, 4, and 8 story and subjected to three recorded Algerian accelerograms are studied. The diagonal strut approach is adopted for modeling the infill panels and a fiber model is used to model RC members. This paper reports on the seismic evaluation of RC frames with brick infill panels. The results obtained show that the masonry panels enhance the load lateral capacity of the buildings and the infill panel configuration influences the response of the structures.

Keywords: seismic design, RC frames, infill panels, non linear dynamic analysis

Procedia PDF Downloads 546

Authors: Daniel Martin Fellows, Sean P. Walton, Jennifer Thompson, Oubay Hassan, Ella Quigley, Kevin Tinkham

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Fire performance is a crucial aspect to consider when designing cladding products, and testing this performance is extremely expensive. Appropriate use of numerical simulation of fire performance has the potential to reduce the total number of fire tests required when designing a product by eliminating poor-performing design ideas early in the design phase. Due to the complexity of fire and the large spectrum of failures it can cause, multi-disciplinary models are needed to capture the complex fire behavior and its structural effects on its surroundings. Working alongside Tata Steel U.K., the authors have focused on completing a coupled CFD-FEA simulation model suited to test Polyisocyanurate (PIR) based sandwich panel products to gain confidence before costly experimental standards testing. The sandwich panels are part of a thermally insulating façade system primarily for large non-domestic buildings. The work presented in this paper compares two coupling methodologies of a replicated physical experimental standards test LPS 1181-1, carried out by Tata Steel U.K. The two coupling methodologies that are considered within this research are; one-way and two-way. A one-way coupled analysis consists of importing thermal data from the CFD solver into the FEA solver. A two-way coupling analysis consists of continuously importing the updated changes in thermal data, due to the fire's behavior, to the FEA solver throughout the simulation. Likewise, the mechanical changes will also be updated back to the CFD solver to include geometric changes within the solution. For CFD calculations, a solver called Fire Dynamic Simulator (FDS) has been chosen due to its adapted numerical scheme to focus solely on fire problems. Validation of FDS applicability has been achieved in past benchmark cases. In addition, an FEA solver called ABAQUS has been chosen to model the structural response to the fire due to its crushable foam plasticity model, which can accurately model the compressibility of PIR foam. An open-source code called FDS-2-ABAQUS is used to couple the two solvers together, using several python modules to complete the process, including failure checks. The coupling methodologies and experimental data acquired from Tata Steel U.K are compared using several variables. The comparison data includes; gas temperatures, surface temperatures, and mechanical deformation of the panels. Conclusions are drawn, noting improvements to be made on the current coupling open-source code FDS-2-ABAQUS to make it more applicable to Tata Steel U.K sandwich panel products. Future directions for reducing the computational cost of the simulation are also considered.

Keywords: fire engineering, numerical coupling, sandwich panels, thermo fluids

Procedia PDF Downloads 89

Authors: Shobha U. Jadhav, R. S. Saler

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Onion is most Important Vegetable crop grown throughout the world. Onion suffers from pest and fungal diseases but the fungicides cause pollution and disturb microbial balance of soil. Under integrated fungal disease management programme cost effective and eco- friendly component like plant extract are used to control plant pathogens. Alternaria porri, Fusarium oxysporium, Stemphylium vesicarium are soil borne pathogens of onion. Effect of three different plant extract (Datura metel, Pongamia pinnata, Ipomoea palmata) at five different concentration Viz, 10,25,50,75 and 100 percentage on these pathogens was studied by food poisoning techniquie. Detura metal gave 94.73% growth of Alternaria porri at 10% extract concentraton and 26.31% growth in 100% extract concentration. As compared to Fusarium oxysporium, and Stemphylium vesicarium, Alternaria porri give good inhibitory response. In Pongamia pinnata L. at 10% extract concentration 84.21% growth and at 100% extract concentration 36.84% growth of Stemphylium vesicarium was observed. Stemphylium vesicarium give good in inhibitory response as compared to Alternaria porri and Fusarium oxysporium. Ipomoea palmata in 10% extract concentration 92% growth and in 100% extract concentration 40% growth of Fusarium oxysporium was recorded. Fusarium oxysporium give good inhibitory response as compared to Alternaria porri and, Stemphylium vesicarium.

Keywords: pathogen, onion, plant extract, Allium cepa L.

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Authors: N. K. Thakur

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A major proportion of the formations drilled for the production of hydrocarbons consists of clay containing shales. The petroleum industry has hugely investigated the role of clay minerals and their subsequent effect on wellbore stability during the drilling and production of hydrocarbons. It has been found that when the shale formation comes in contact with water-based drilling fluid, the interaction of clay minerals like montmorillonite with infiltrated water leads to hydration of the clay minerals, which causes shale swelling. When shale swelling proceeds further, it may lead to major drilling complications like caving, pipe sticking, which invariably influences wellbore stability, wellbore diameter, the mechanical strength of shale, stress distribution in the wellbore, etc. These problems ultimately lead to an increase in nonproductive time and additional costs during drilling. Several additives are used to prevent shale instability. Among the popular additives used for shale inhibition in drilling muds, ionic liquids and nanoparticles are emerging to be the best additives. The efficiency of the proposed additives will be studied and compared with conventional clay inhibitors like KCl. The main objective is to develop a highly efficient water-based mud for mitigating shale instability and reducing fluid loss which is environmentally friendly and does not alter the formation permeability. The use of nanoparticles has been exploited to enhance the rheological and fluid loss properties in water-based drilling fluid ionic liquid have attracted significant research interest due to its unique thermal stability. It is referred to as ‘green chemical’. The preliminary experimental studies performed are promising. The application of more effective mud additives is always desirable to make the drilling process techno-economically proficient.

Keywords: ionic liquid, shale inhibitor, wellbore stability, unconventional

Procedia PDF Downloads 194

Authors: M. Zaïgouche, A. Kouvahe, F. Stefanelli

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IMPERTIO is a high technology based project aiming at offering efficient assistance help in communication for persons affected by Cerebral Palsy. The systems currently available are hardly used by these patients who are not satisfied by ergonomics and response time. The project rests upon the concept that, opposite to usual master-slave communication giving power to the entity with larger range of possibilities, providing conversely the mastery to the entity with smaller range of possibilities will allow a better understanding ground for both parties. Entirely customizable, the application developed from this idea gives full freedom to the user. Through pictograms (one button linked to a word or a sentence) and adapted keyboard, noticeable improvements are brought to the response time and ease to use ergonomics.

Keywords: cerebral palsy, master-slave relation, communication interface, virtual keyboard, word construction algorithm

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Authors: Bokku Kang, Changsoo Chon, Han Sung Kim

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We developed new design of rod of pedicle screw system that is beneficial in maintaining the spacing between the vertebrae and assessed the performance of the posterior fixation screw systems by numerical analysis according to the range of motion (flexion, extension, lateral bending, and axial rotation) of the vertebral column after inserting the pedicle screws. The simulation results showed that the conventional rod was the most low equivalent stress value among implant units in the case of flexion, extension and lateral bending of the vertebrae. In all cases except the torsional rotation, the results showed that the stress level of the single and double rounded rod exceeded about 30% to 70% compare to the conventional rod. Therefore, this product is not suitable for actual application in the field yet and it seems that product design optimization is necessary. Acknowledgement: This research was supported by the Ministry of Trade, Industry & Energy (MOTIE), Korea Institute for Advancement of Technology (KIAT) through the Encouragement Program for The Industries of Economic Cooperation Region.

Keywords: lumber spine, internal fixation device, finite element method, biomechanics

Procedia PDF Downloads 378

Authors: Peter G. Hollis, Kim G. Clarke

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Accurate quantification of the overall volumetric oxygen transfer coefficient (KLa) is ubiquitously measured in bioprocesses by analysing the response of dissolved oxygen (DO) to a step change in the oxygen partial pressure in the sparge gas using a DO probe. Typically, the response lag (τ) of the probe has been ignored in the calculation of KLa when τ is less than the reciprocal KLa, failing which a constant τ has invariably been assumed. These conventions have now been reassessed in the context of multiphase bioprocesses, such as a hydrocarbon-based system. Here, significant variation of τ in response to changes in process conditions has been documented. Experiments were conducted in a 5 L baffled stirred tank bioreactor (New Brunswick) in a simulated hydrocarbon-based bioprocess comprising a C14-20 alkane-aqueous dispersion with suspended non-viable Saccharomyces cerevisiae solids. DO was measured with a polarographic DO probe fitted with a Teflon membrane (Mettler Toledo). The DO concentration response to a step change in the sparge gas oxygen partial pressure was recorded, from which KLa was calculated using a first order model (without incorporation of τ) and a second order model (incorporating τ). τ was determined as the time taken to reach 63.2% of the saturation DO after the probe was transferred from a nitrogen saturated vessel to an oxygen saturated bioreactor and is represented as the inverse of the probe constant (KP). The relative effects of the process parameters on KP were quantified using a central composite design with factor levels typical of hydrocarbon bioprocesses, namely 1-10 g/L yeast, 2-20 vol% alkane and 450-1000 rpm. A response surface was fitted to the empirical data, while ANOVA was used to determine the significance of the effects with a 95% confidence interval. KP varied with changes in the system parameters with the impact of solid loading statistically significant at the 95% confidence level. Increased solid loading reduced KP consistently, an effect which was magnified at high alkane concentrations, with a minimum KP of 0.024 s-1 observed at the highest solids loading of 10 g/L. This KP was 2.8 fold lower that the maximum of 0.0661 s-1 recorded at 1 g/L solids, demonstrating a substantial increase in τ from 15.1 s to 41.6 s as a result of differing process conditions. Importantly, exclusion of KP in the calculation of KLa was shown to under-predict KLa for all process conditions, with an error up to 50% at the highest KLa values. Accurate quantification of KLa, and therefore KP, has far-reaching impact on industrial bioprocesses to ensure these systems are not transport limited during scale-up and operation. This study has shown the incorporation of τ to be essential to ensure KLa measurement accuracy in multiphase bioprocesses. Moreover, since τ has been conclusively shown to vary significantly with process conditions, it has also been shown that it is essential for τ to be determined individually for each set of process conditions.

Keywords: effect of process conditions, measuring oxygen transfer coefficients, multiphase bioprocesses, oxygen probe response lag

Procedia PDF Downloads 266

Authors: Raj Banerjee, Y. M. Parulekar, Aniruddha Sengupta, J. Chattopadhyay

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This study proposes a Discrete Element Method (DEM) simulation using a commercial software PFC 2D (2019) for quantitatively simulating the monotonic and cyclic behaviour of sand using irregular shapes of sand grains. A preliminary analysis of the number of particles for optimal Representative Element Volume (REV) simulation of dimension 35mm x 35mm x 70mm using the scaled Grain Size Distribution (GSD) of sand is carried out. Subsequently, the effect of particle shape on the performance of sand during monotonic and cyclic bi-axial tests is assessed using numerical simulation. The validation of the numerical simulation for one case is carried out using the test results from the literature. Further numerical studies are performed in which the particles in REV are simulated by mixing round discs with irregular clumps (100% round disc, 75% round disc 25% irregular clump, 50% round disc 50% irregular clump, 25% round disc 75% irregular clump, 100% irregular clump) in different proportions using Dry Deposition (DD) method. The macro response for monotonic loading shows that irregular sand has a higher strength than round particles and that the Mohr-Coulomb failure envelope depends on the shape of the grains. During cyclic loading, it is observed that the liquefaction resistance curve (Cyclic Stress Ratio (CSR)-Number of cycles (N)) of sand is dependent on the combination of particle shapes with different proportions.

Keywords: biaxial test, particle shape, monotonic, cyclic

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Authors: Gianna Zou

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Propensity score matching (PSM), introduced by Paul R. Rosenbaum and Donald Rubin in 1983, is a popular statistical matching technique which tries to estimate the treatment effects by taking into account covariates that could impact the efficacy of study medication in clinical trials. PSM can be used to reduce the bias due to confounding variables. However, PSM assumes that the response values are normally distributed. In some cases, this assumption may not be held. In this paper, a machine learning method - Bayesian Additive Regression Tree (BART), is used as a more robust method of matching. BART can work well when models are misspecified since it can be used to model heterogeneous treatment effects. Moreover, it has the capability to handle non-linear main effects and multiway interactions. In this research, a BART Matching Method (BMM) is proposed to provide a more reliable matching method over PSM. By comparing the analysis results from PSM and BMM, BMM can perform well and has better prediction capability when the response values are not normally distributed.

Keywords: BART, Bayesian, matching, regression

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Authors: Nadine Sammy, Mark Wilson, Samuel Vine

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The Theory of Challenge and Threat States in Athletes (TCTSA) states that self-efficacy is an antecedent of challenge and threat. These states result from conscious and unconscious evaluations of situational demands and personal resources and are represented by both cognitive and physiological markers. Challenge is considered a more adaptive stress response as it is associated with a more efficient cardiovascular profile, as well as better performance and attention effects compared with threat. Self-efficacy is proposed to influence challenge/threat because an individual’s belief that they have the skills necessary to execute the courses of action required to succeed contributes to a perception that they can cope with the demands of the situation. This study experimentally examined the effects of self-efficacy on cardiovascular responses (challenge and threat), demand and resource evaluations, performance and attention under pressurised conditions. Forty-five university students were randomly assigned to either a control (n=15), low self-efficacy (n=15) or high self-efficacy (n=15) group and completed baseline and pressurised golf putting tasks. Self-efficacy was manipulated using false feedback adapted from previous studies. Measures of self-efficacy, cardiovascular reactivity, demand and resource evaluations, task performance and attention were recorded. The high self-efficacy group displayed more favourable cardiovascular reactivity, indicative of a challenge state, compared with the low self-efficacy group. The former group also reported high resource evaluations, but no task performance or attention effects were detected. These findings demonstrate that levels of self-efficacy influence cardiovascular reactivity and perceptions of resources under pressurised conditions.

Keywords: cardiovascular, challenge, performance, threat

Procedia PDF Downloads 232

Authors: Saheed A. Adekola, Mabel A. Charles-Davies, Ridwan A. Adekola

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Background: Testosterone is a known androgenic and anabolic steroid, primarily secreted in the testes. It plays an important role in the development of testes and prostate and has a range of biological actions. There is evidence that exposure to mixed chemicals in the workplace leads to the generation of free radicals and inadequate antioxidants leading to oxidative stress, which may serve as an early indicator of a pathophysiologic state. Based on findings, testosterone shows direct antioxidant effects by increasing the activities of antioxidant enzymes like glutathione peroxidase, thus indirectly contributing to antioxidant capacity. Objective: To evaluate the antioxidant role of testosterone as well as the relationship between testosterone and oxidative stress biomarkers in males exposed to mixed chemicals in the automobile repair community. Methods: The study included 43 participants aged 22- 60years exposed to mixed chemicals (EMC) from the automobile repair community. Forty (40) apparently healthy, unexposed, age-matched controls were recruited after informed consent. Demographic, sexual and anthropometric characteristics were obtained from pre-test structured questionnaires using standard methods. Blood samples (10mls) were collected from each subject into plain bottles and sera obtained were used for biochemical analyses. Serum levels of testosterone and luteinizing hormone (LH) were determined by enzyme immunoassay method, EIA (Immunometrics UK.LTD). Levels of total antioxidant capacity (TAC), total plasma peroxide (TPP), Malondialdehyde (MDA), hydrogen peroxide (H2O2), glutathione peroxide (GPX), superoxide dismutase (SOD), glutathione-S-transferase (GST), and reduced glutathione (GSH) were determined using spectrophotometric methods respectively. Results obtained were analyzed using the Student’s t-test and Chi-square test for quantitative variables and qualitative variables respectively. Multiple regression was used to find associations and relationships between the variables. Results: Significant higher concentrations of TPP, MDA, OSI, H2O2 and GST were observed in EMC compared with controls (p < 0.001). Within EMC, significantly higher levels of testosterone, LH and TAC were observed in eugonadic when compared with hypogonadic participants (p < 0.001). Diastolic blood pressure, waist circumference, waist height ratio and waist hip ratio were significantly higher in participants EMC compared with the controls. Sexual history and dietary intake showed that the controls had normal erection during sex and took more vegetables in their diet which may therefore be beneficial. Conclusion: The significantly increased levels of total antioxidant capacity in males exposed to mixed chemicals despite their exposure may probably reflect the contributory antioxidant role testosterone that prevents oxidative stress.

Keywords: mixed chemicals, oxidative stress, antioxidant, hypogonadism testosterone

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Authors: Ilya B. Tsyrlov, Dmitry Y. Oshchepkov

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A computational search for dioxin response elements (DREs) in genes of proteins comprising the Ah receptor (AhR) cytosolic core complex was performed by highly efficient tool SITECON. Eventually, the following number of new DREs in 5’flanking region was detected by SITECON: one in AHR gene, five in XAP2, eight in HSP90AA1, and three in HSP90AB1 genes. Numerous DREs found in genes of AhR and AhR cytosolic complex members would shed a light on potential mechanisms of expression, the stoichiometry of unliganded AhR core complex, and its degradation vs biosynthesis dynamics resulted from treatment of target cells with the AhR most potent ligand, 2,3,7,8-TCDD. With human viruses, reduced susceptibility to TCDD of geneencoding HIV-1 P247 was justified by the only potential DRE determined in gag gene encoding HIV-1 P24 protein, whereas the regulatory region of CMV genes encoding IE gp/UL37 has five potent DRE, 1.65 kb/UL36 – six DRE, pp65 and pp71 – each has seven DRE, and pp150 – ten DRE. Also, from six to eight DRE were determined with SITECON in the regulatory region of HSV-1 IE genes encoding tegument proteins, UL36 and UL37, and of UL19 gene encoding bindingglycoprotein C (gC). So, TCDD in the low picomolar range may activate in human cells AhR: Arnt transcription pathway that triggers CMV and HSV-1 reactivation by binding to numerous promoter DRE within immediate-early (IE) genes UL37 and UL36, thus committing virus to the lytic cycle.

Keywords: dioxin response elements, Ah receptor, AhR: Arnt transcription pathway, human and viral genes

Procedia PDF Downloads 104

Authors: Sharmeelee Subramaniam, Muhd Harris Ramli, Fauziah Ahmad

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The application of vacuum pressure to accelerate ground consolidation has been growing significantly in recent years. This ground improvement technique has its advantages, especially in areas where suitable fill is scarce, as it minimizes the surcharge fill height required for the preloading. A study was carried out to examine the response of soft subsoil subjected to vacuum consolidation in combination with embankment loading, surcharge preloading and PVD with two-way drainage. This paper shall describe a procedure to determine the optimum surcharge height and penetration depth of prefabricated vertical drains (PVD) where vacuum consolidation is combined with the use of PVD in soft clay deposits with two-way drainage.

Keywords: prefabricated vertical drain, soft soil, surcharge preload, vacuum consolidation

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Authors: A. Iqbal Banauaji, Muchamad Sholikun

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Diabetes mellitus (DM) is a metabolism disorder that tends to increase its prevalence in the world, including in Indonesia. The development of DM type 2 can cause oxidative stress characterized by an imbalance between oxidants and antioxidants in the body Increased oxidative stress causes type 2 diabetes mellitus to require intake of exogenous antioxidants in large quantities to inhibit oxidative damage in the body. Bran can be defined as a functional food because it consists of 11.39% fiberand 28.7% antioxidants and the purple yam consists of anthocyanin which functions as an antioxidant. With abundant amount and low price, purple yam and bran can be used for analog rice as the effort to diversify functional food. The antioxidant’s activity of analog rice from purple yam and bran which is measured by using DPPH’s method is 12,963%. The rough fiber’s level on the analog rice from purple yam is 2.985%. The water amount of analog rice from purple yam and bran is 8.726%. Analog rice from purple yam and bran has the similar texture as the usual rice, tasted slightly sweet, light purple colored, and smelled like bran.

Keywords: antioxidant, analog rice, functional food, diabetes mellitus

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Authors: Maryam Kiani, Xiaoqin Tian, Yu Du, Abdul Basit Kiani

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Zn-doped MgFe₂O₄ nanoparticles (ZMFO) (Zn=0.0, 0.2, 0.35, 0.5,) were prepared by Co-precipitation synthesis route. Structural and morphological analysis confirmed the formation of spinel cubic nanostructure by X-Ray diffraction (XRD) data shows high reactive surface area owing to a small average particle size of about 14 nm, which greatly influences the gas sensing mechanism. The gas sensing property of ZMFO for several gases was obtained by measuring the resistance as a function of different factors, like composition and response time in air and in the presence of gas. The sensitivity of spinel ferrite to gases CO₂, O₂, and O₂ at room temperature has been compared. The nanostructured ZMFO exhibited high sensitivity in the order of CO₂>O₂ and showed a good response time of (~1min) to CO₂, demonstrating that this expanse of research can be used in the field of gas sensors devising high sensitivity and good selectivity at 25°C.

Keywords: MgFe₂O₄ nanoparticles, hydrothermal synthesis, gas sensing properties, XRD

Procedia PDF Downloads 118

Authors: B. Gechbaia, K. Goletiani, G. Gabedava, N. Mikeltadze

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At this stage, Georgia is a country which is actively involved in the European integration process, for which the primary priority is effective integration in the European education system. The modern Georgian higher education system is the process of establishing a new sociocultural reality, whose main priorities are determined by the Quality System as a continuous cycle of planning, implementation, checking and acting. Obviously, in this situation, the issue of management of education institutions comes out in the foreground, since the proper planning and implementation of personnel management processes is one of the main determinants of the company's performance. At the same time, one of the most important factors is the psychological comfort of the personnel, ensuring their protection and efficiency of stress management policy. The purpose of this research is to determine how intensely the relationship is between the psychological comfort of the personnel and the efficiency of the quality system in the institution as the quality assurance mechanisms of educational institutions affect the stability of personnel, prevention and management of the stressful situation. The research was carried out within the framework of the Internal Grant Project «The Role of Organizational Culture in the Process of Settlement of Management of Stress and Conflict, Georgian Reality and European Experience » of the Batumi Navigation Teaching University, based on the analysis of the survey results of target groups. The small-scale research conducted by us has revealed that the introduction of quality assurance system and its active implementation increased the quality of management of Georgian educational institutions, increased the level of universal engagement in internal and external processes and as a result, it has improved the quality of education as well as social and psychological comfort indicators of the society.

Keywords: quality assurance, effective management, stability of personnel, psychological comfort, stress management

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Authors: H. Hammoudi, S. Bendenia, I. Batonneau-Gener, J. Comparot, K. Marouf-Khelifa, A. Khelifa

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X zeolites were prepared by ion-exchange with Cu2+ and/or Zn2+ cations, at different concentrations of the exchange solution, and characterised by thermal analysis and nitrogen adsorption. The acidity of the samples was investigated by pyridine adsorption–desorption followed by in situ Fourier transform infrared (FTIR) spectroscopy. Desorption was carried out at 150, 250 and 350 °C. The objective is to estimate the nature and concentration of acid sites. A comparison between the binary (Cu(x)X, Zn(x)X) and ternary (CuZn(x)X) exchanges was also established (x = level of exchange) through the Cu(43)X, Zn(48)X and CuZn(50)X samples. Lewis acidity decreases overall with desorption temperature and the level of exchange. As the latter increases, there is a conversion of some Lewis sites into those of Brønsted during thermal treatment. In return, the concentration of Brønsted sites increases with the degree of exchange. The Brønsted acidity of CuZn(50)X at 350 °C is more important than the sum of those of Cu(43)X and Zn(48)X. The found values were 73, 32 and 15 μmol g-1, respectively. Besides, the concentration of Brønsted sites for CuZn(50)X increases with desorption temperature. These features indicate the presence of a synergistic effect amplifying the strength of these sites when Cu2+ and Zn2+ cations compete for the occupancy of sites distributed inside zeolitic cavities.

Keywords: acidity, adsorption, pyridine, zeolites

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Authors: S. Mahdi S. Kolbadi, Ramezan Ali Alvand, Afrasiab Mirzaei

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In this study, to investigate and analyze the seismic behavior of concrete in open rectangular water storage tanks in two-dimensional and three-dimensional spaces, the Finite Element Method has been used. Through this method, dynamic responses can be investigated together in fluid storages system. Soil behavior has been simulated using tanks boundary conditions in linear form. In this research, in addition to flexibility of wall, the effects of fluid-structure interaction on seismic response of tanks have been investigated to account for the effects of flexible foundation in linear boundary conditions form, and a dynamic response of rectangular tanks in two-dimensional and three-dimensional spaces using finite element method has been provided. The boundary conditions of both rigid and flexible walls in two-dimensional finite element method have been considered to investigate the effect of wall flexibility on seismic response of fluid and storage system. Furthermore, three-dimensional model of fluid-structure interaction issue together with wall flexibility has been analyzed under the three components of earthquake. The obtained results show that two-dimensional model is also accurately near to the results of three-dimension as well as flexibility of foundation leads to absorb received energy and relative reduction of responses.

Keywords: dynamic behavior, flexible wall, fluid-structure interaction, water storage tank

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Authors: Fatemeh Rezaei, Babak Shokri

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In this study, PMMA films are modified by oxygen plasma treatment for biomedical applications. The plasma generator is capacitively coupled radio frequency (13.56 MHz) power source. The oxygen pressure and gas flow rate are kept constant at 40 mTorr and 30 sccm, respectively and samples are treated for 2 minutes. Hydrophilicity and biocompatibility of PMMA films are studied before and after treatments in different applied powers (10-80 W). In order to monitor the plasma process, the optical emission spectroscopy is used. The wettability and cellular response of samples are investigated by water contact angle (WCA) analysis and MTT assay, respectively. Also, surface free energy (SFE) variations are studied based on the contact angle measurements of three liquids. It is found that RF oxygen plasma treatment enhances the biocompatibility and also hydrophilicity of PMMA films.

Keywords: cellular response, hydrophilicity, MTT assay, PMMA, RF plasma

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Authors: Tomas Makaras

Abstract:

Sticklebacks (Gasterosteiformes) are increasingly used in ecological and evolutionary research and become well-established role as model species for biologists. However, ecotoxicology studies concerning behavioural effects in sticklebacks regarding stress responses, mainly induced by chemical mixtures, have hardly been addressed. Moreover, although many authors in their studies emphasised the similarity between three-spined and nine-spined stickleback in morphological, neuroanatomical and behavioural adaptations to environmental changes, several comparative studies have revealed considerable differences between these species in and their susceptibility and resistance to variousstressors in laboratory experiments. The hypothesis of this study was that three-spined and nine-spined stickleback species will demonstrate apparent differences in response patterns and sensitivity to metal-based chemicals stimuli. For this purpose, we investigated the swimming behaviour (including mortality rate based on 96-h LC50 values) of two ecologically similar three-spined (Gasterosteusaculeatus) and nine-spined sticklebacks (Pungitiuspungitius) to short-term (up to 24 h) metal mixture (MIX) exposure. We evaluated the relevance and efficacy of behavioural responses of test species in the early toxicity assessment of chemical mixtures. Fish exposed to six (Zn, Pb, Cd, Cu, Ni and Cr) metals in the mixture were either singled out by the Water Framework Directive as priority or as relevant substances in surface water, which was prepared according to the environmental quality standards (EQSs) of these metals set for inland waters in the European Union (EU) (Directive 2013/39/EU). Based on acute toxicity results, G. aculeatus found to be slightly (1.4-fold) more tolerant of MIX impact than those of P. pungitius specimens. The performed behavioural analysis showed the main effect on the interaction between time, species and treatment variables. Although both species exposed to MIX revealed a decreasing tendency in swimming activity, these species’ responsiveness to MIX was somewhat different. Substantial changes in the activity of G. aculeatus were established after 3-h exposure to MIX solutions, which was 1.43-fold lower, while in the case of P. pungitius, 1.96-fold higher than established 96-h LC50 values for each species. This study demonstrated species-specific differences in response sensitivity to metal-based water pollution, indicating behavioural insensitivity of P. pungitiuscompared to G. aculeatus. While many studies highlight the usefulness and suitability of nine-spined sticklebacks for evolutionary and ecological research, attested by their increasing popularity in these fields, great caution must be exercised when using them as model species in ecotoxicological research to probe metal contamination. Meanwhile, G. aculeatus showed to be a promising bioindicator species in the environmental ecotoxicology field.

Keywords: acute toxicity, comparative behaviour, metal mixture, swimming activity

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Authors: Hamed Mohamed Haggag

Abstract:

Prior to 12 November 1955, no earthquakes have been reported from the Abu Dabbab area in the International Seismological Center catalogue (ISC). The largest earthquake in Abu Dabbab area occurred on November 12, 1955 with magnitude Mb 6.0. The closest station from the epicenter was at Helwan (about 700 km to the north), so the depth of this event is not constrained and no foreshocks or aftershocks were recorded. Two other earthquakes of magnitude Mb 4.5 and 5.2 took place in the same area on March 02, 1982 and July 02, 1984, respectively. Since the installation of Aswan Seismic Network stations in 1982, (250-300 km to the south-west of Abu Dabbab area) then the Egyptian Natoinal Seismic Network stations, it was possible to record some activity from Abu Dabbab area. The recorded earthquakes at Abu Dabbab area as recorded from 1982 to 2014 shows that the earthquake epicenters are distributed in the same direction of the main trends of the faults in the area, which is parallel to the Red Sea coast. The spectral analysis was made for some earthquakes. The source parameters, seismic moment (Mo), source dimension (r), stress drop (Δδ), and apparent stress (δ) are determined for these events. The spectral analysis technique was completed using MAG software program.

Keywords: Abu Dabbab, seismicity, seismic moment, source parameter

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Authors: Surbhi Rani, Sunita Gakkhar

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The four-dimensional food web system consisting of two prey species for a generalist middle predator and a top predator is proposed and investigated. The middle predator is predating both the prey species with a modified Holling type-II functional response. The food web model is found to be well-posed, bounded, and dissipative. The proposed model's essential dynamical features are studied in terms of local stability. The four species' survival is explored, and persistence conditions are established. The numerical simulations reveal the persistence in the form of a chaotic attractor or stable focus. The conclusion is that providing additional food to the middle predator may help to control the food chain's chaos.

Keywords: predator-prey model, existence of equilibrium points, local stability, chaos, numerical simulations

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Authors: Maruful H. Mazumder, Raymond I. Gilbert

Abstract:

The design specifications for calculating development and lapped splice lengths of reinforcement in concrete are derived from a conventional empirical modelling approach that correlates experimental test data using a single mathematical equation. This paper describes part of a recently completed experimental research program to assess the effects of different structural parameters on the development length requirements of modern high strength steel reinforcing bars, including the case of lapped splices in large-scale reinforced concrete members. The normalized average bond stresses for the different variations of anchorage lengths are assessed according to the general form of a typical empirical analytical model of bond and anchorage. Improved analytical modelling equations are developed in the paper that better correlate the normalized bond strength parameters with the structural parameters of an empirical model of bond and anchorage.

Keywords: bond stress, development length, lapped splice length, reinforced concrete

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Authors: Emmanuel Bernard, Rebecca L. Cordell, Akeem A. Abayomi, Rose Alani, Paul S. Monks

Abstract:

This study investigates the prevalence and extent of BTEX (Benzene, Toluene, Ethylbenzene, and Xylene) contamination in Leicester, United Kingdom, and Lagos, Nigeria, through field measurements at roadside (RS) and urban background (UB) sites. Using thermal desorption gas chromatography mass spectrometry (TD-GC-MS), BTEX concentrations were quantified. In Leicester, the average RS concentration was 24.9 ± 8.9 μg/m³, and the UB concentration was 12.7 ± 5.7 μg/m³. In Lagos, the RS concentration was significantly higher at 106 ± 39.3 μg/m³, and the UB concentration was 20.1 ± 8.9 μg/m³. The RS concentration in Lagos was approximately 4.3 times higher than in Leicester, while the UB concentration was about 1.6 times higher. These disparities are attributed to differences in road infrastructure, traffic regulation compliance, fuel and oil quality, and local activities. In Leicester, the highest UB concentration (20.5 ± 1.7 μg/m³) was at Knighton Village, near the heavily polluted RS Wigston roundabout. In Lagos, the highest concentration (172.1 ± 12.2 μg/m³) was at Ojuelegba, a major transportation hub. Correlation analysis revealed strong positive relationships between the concentrations of BTEX compounds in both cities, suggesting common sources such as vehicular emissions and industrial activities. The ratios of toluene to benzene (T:B) and m/p xylene to ethylbenzene (m/p X:E) were analysed to infer source contributions and the photochemical age of air masses. The T:B ratio in Leicester ranged from 0.44 to 0.71, while in Lagos, it ranged from 1.36 to 2.17. The m/p X:E ratio in Leicester ranged from 2.11 to 2.19, like other UK cities, while in Lagos, it ranged from 1.65 to 2.32, indicating relatively fresh emissions. This study highlights significant differences in BTEX concentrations between Leicester and Lagos, emphasizing the need for tailored pollution control strategies to address the specific sources and conditions in different urban environments.

Keywords: BTEX contamination, urban air quality, thermal desorption GC-MS, roadside emissions, urban background sites, vehicular emissions, pollution control strategies

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