Search results for: free surface sloshing

Authors: Shuang Chen, Zongqian Shi, Jiajia Sun, Mingjia Li

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Microfluidics is a technology that small amounts of fluids are manipulated using channels with dimensions of tens to hundreds of micrometers. At present, this significant technology is required for several applications in some fields, including disease diagnostics, genetic engineering, and environmental monitoring, etc. Among these fields, manipulation of microparticles and cells in microfluidic device, especially separation, have aroused general concern. In magnetic field, the separation methods include positive and negative magnetophoresis. By comparison, negative magnetophoresis is a label-free technology. It has many advantages, e.g., easy operation, low cost, and simple design. Before the separation of particles or cells, focusing them into a single tight stream is usually a necessary upstream operation. In this work, the focusing of diamagnetic particles in ferrofluid microflows with a single set of overhead permanent magnets is investigated numerically. The geometric model of the simulation is based on the configuration of previous experiments. The straight microchannel is 24mm long and has a rectangular cross-section of 100μm in width and 50μm in depth. The spherical diamagnetic particles of 10μm in diameter are suspended into ferrofluid. The initial concentration of the ferrofluid c₀ is 0.096%, and the flow rate of the ferrofluid is 1.8mL/h. The magnetic field is induced by five identical rectangular neodymium−iron− boron permanent magnets (1/8 × 1/8 × 1/8 in.), and it is calculated by equivalent charge source (ECS) method. The flow of the ferrofluid is governed by the Navier–Stokes equations. The trajectories of particles are solved by the discrete phase model (DPM) in the ANSYS FLUENT program. The positions of diamagnetic particles are recorded by transient simulation. Compared with the results of the mentioned experiments, our simulation shows consistent results that diamagnetic particles are gradually focused in ferrofluid under magnetic field. Besides, the diamagnetic particle focusing is studied by varying the flow rate of the ferrofluid. It is in agreement with the experiment that the diamagnetic particle focusing is better with the increase of the flow rate. Furthermore, it is investigated that the diamagnetic particle focusing is affected by other factors, e.g., the width and depth of the microchannel, the concentration of the ferrofluid and the diameter of diamagnetic particles.

Keywords: diamagnetic particle, focusing, microfluidics, permanent magnet

Procedia PDF Downloads 124

Authors: Qianli Ma, Xuemin Zhao, Lingai Yao, Zhencheng Xu, Li Wang

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Heavy metal pollution accidents, frequently happened in this decade in China, severely threaten aquatic ecosystem and economy. In January 2012, a basin-scale accidental Cd pollution happened in Longjiang River in southwest China. Although water quality was recovered in short period by emergency treatment with flocculants, a large amount of contaminated cage-cultivated fish were left with the task of preventing or mitigating Cd contamination of fish. In this study, unpolluted Ctenopharyngodon idellus were fed by Cd-contaminated macrophytes for assessing the effect of Cd accumulation through food exposure, and the contaminated C. idellus were fed with Cd-free macrophytes for assessing the ability of Cd depuration. The on-site cultivation experiments were done in two sites of Lalang (S1, accidental Cd pollution originated) and Sancha (S2, a large amount of flocculants were added to accelerate Cd precipitation) in Longjiang river. Results showed that Cd content in fish muscle presented an increasing trend in the accumulation experiment. In S1, Cd content of fish muscle rose sharply from day 8 to day 18 with higher average Cd content in macrophytes and sediment, and kept in the range of 0.208-0.308 mg/kg afterward. In S2, Cd content of fish muscle rose gradually throughout the experiment and reached the maximum level of 0.285 mg/kg on day 76. The results of the depuration experiment showed that Cd content in fish muscle decreased and significant changes were observed in the first half time of the experiment. Meanwhile, fish with lower initial Cd content presented higher elimination constant. In S1, Cd content of fish significantly decreased from 0.713 to 0.304 mg/kg in 18 days and kept decreasing to 0.110 mg/kg in the end, and 84.6% of Cd content was eliminated. While in S2, there was a sharp decrease of Cd content of fish in 0-8 days from 0.355 mg/kg to 0.069 mg/kg. The total elimination percentage was 93.8% and 80.6% of which appeared in day 0-8. The elimination constant of fish in S2 was 0.03 which was higher than 0.02 in S1. Collectively, our results showed Cd could be absorbed through food exposure and accumulate in fish muscle, and the accumulated Cd in fish muscle can be excreted after isolated from the polluted food sources. This knowledge allows managers to assess health risk of Cd contaminated fish and minimize aquaculture loss when considering fish cultivation after accidental pollution.

Keywords: accidental pollution, cadmium accumulation and depuration, cage-cultivated fish, environmental management, river

Procedia PDF Downloads 247

Authors: Hamil Uribe, Cristian Arancibia

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In Chile, the water for irrigation and hydropower generation is delivery essentially through unlined channels on earth, which have high seepage losses. Traditional seepage-abatement technologies are very expensive. The goals of this work were to quantify water loss in unlined channels and select reaches to evaluate the use of linear anionic polyacrylamide (LA-PAM) to reduce seepage losses. The study was carried out in Maule Region, central area of Chile. Water users indicated reaches with potential seepage losses, 45 km of channels in total, whose flow varied between 1.07 and 23.6 m³ s⁻¹. According to seepage measurements, 4 reaches of channels, 4.5 km in total, were selected for LA-PAM application. One to 4 LA-PAM applications were performed at rates of 11 kg ha⁻¹, considering wet perimeter area as basis of calculation. Large channels were used to allow motorboat moving against the current to carry-out LA-PAM application. For applications, a seeder machine was used to evenly distribute granulated polymer on water surface. Water flow was measured (StreamPro ADCP) upstream and downstream in selected reaches, to estimate seepage losses before and after LA-PAM application. Weekly measurements were made to quantify treatment effect and duration. In each case, water turbidity and temperature were measured. Channels showed variable losses up to 13.5%. Channels showing water gains were not treated with PAM. In all cases, LA-PAM effect was positive, achieving average loss reductions of 8% to 3.1%. Water loss was confirmed and it was possible to reduce seepage through LA-PAM applications provided that losses were known and correctly determined when applying the polymer. This could allow increasing irrigation security in critical periods, especially under drought conditions.

Keywords: canal seepage, irrigation, polyacrylamide, water management

Procedia PDF Downloads 167

Authors: M. O. Adeniyi, R. T. Akinnubi

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The parameterization of turbulent heat fluxes is needed for modeling land-atmosphere interactions in Global Climate Models (GCMs). However, current GCMs still have difficulties with producing reliable turbulent heat fluxes for humid tropical regions, which may be due to inadequate parameterization of the roughness lengths for momentum (z0m) and heat (z0h) transfer. These roughness lengths are usually expressed in term of excess resistance factor (κB^(-1)), and this factor is used to account for different resistances for momentum and heat transfers. In this paper, a more appropriate excess resistance factor (〖 κB〗^(-1)) suitable for low wind speed condition was developed and incorporated into the aerodynamic resistance approach (ARA) in the GCMs. Also, the performance of various standard GCMs κB^(-1) schemes developed for high wind speed conditions were assessed. Based on the in-situ surface heat fluxes and profile measurements of wind speed and temperature from Nigeria Micrometeorological Experimental site (NIMEX), new κB^(-1) was derived through application of the Monin–Obukhov similarity theory and Brutsaert theoretical model for heat transfer. Turbulent flux parameterizations with this new formula provides better estimates of heat fluxes when compared with others estimated using existing GCMs κB^(-1) schemes. The derived κB^(-1) MBE and RMSE in the parameterized QH ranged from -1.15 to – 5.10 Wm-2 and 10.01 to 23.47 Wm-2, while that of QE ranged from - 8.02 to 6.11 Wm-2 and 14.01 to 18.11 Wm-2 respectively. The derived 〖 κB〗^(-1) gave better estimates of QH than QE during daytime. The derived 〖 κB〗^(-1)=6.66〖 Re〗_*^0.02-5.47, where Re_* is the Reynolds number. The derived κB^(-1) scheme which corrects a well documented large overestimation of turbulent heat fluxes is therefore, recommended for most regional models within the tropic where low wind speed is prevalent.

Keywords: humid, tropic, excess resistance factor, overestimation, turbulent heat fluxes

Procedia PDF Downloads 186

Authors: Issam Lakdhar, Akram Alhussein, Juan Creus

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With the huge increase in world energy consumption, researchers are working to find other alternative sources of energy instead of fossil fuel one causing many environmental problems as the production of greenhouse effect gases. Hydrogen is considered a green energy source, which its combustion does not cause environmental pollution. The transport and the storage of the gas molecules or the other products containing this smallest chemical element in metallic structures (pipelines, tanks) are crucial issues. The dissolve and the permeation of hydrogen into the metal lattice lead to the formation of hydride phases and the embrittlement of structures. To protect the metallic structures, a surface treatment could be a good solution. Among the different techniques, magnetron sputtering is used to elaborate micrometric coatings capable of slowing down or stop hydrogen permeation. In the plasma environment, the deposition parameters of new thin-film metallic glasses Al-Ti-W were optimized and controlled in order to obtain, hydrogen barrier. Many characterizations were carried out (SEM, XRD and Nano-indentation…) to control the composition and understand the influence of film microstructure and chemical composition on the hydrogen permeation through the coatings. The coating performance was evaluated under two hydrogen production methods: chemical and electrochemical (cathodic protection) techniques. The hydrogen quantity absorbed was experimentally determined using the Thermal-Desorption Spectroscopy method (TDS)). An ideal ATW thin film was developed and showed excellent behavior against the diffusion of hydrogen.

Keywords: thin films, hydrogen, PVD, plasma technology, electrochemical properties

Procedia PDF Downloads 178

Authors: Veronika Solopova, Oana-Iuliana Popescu, Tim Landgraf, Christoph Benzmüller

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Beginning in 2014, slowly building geopolitical tensions in Eastern Europe led to a full-blown conflict between the Russian Federation and Ukraine that generated an unprecedented amount of news articles and data from social media data, reflecting the opposing ideologies and narratives as a background and the essence of the ongoing war. These polarized informational campaigns have led to countless mutual accusations of misinformation and fake news, shaping an atmosphere of confusion and mistrust for many readers all over the world. In this study, we analyzed scraped news articles from Ukrainian, Russian, Romanian and English-speaking news outlets, on the eve of 24th of February 2022, compared to day five of the conflict (28th of February), to see how the media influenced and mirrored the changes in public opinion. We also contrast the sources opposing and supporting the stands of the Russian government in Ukrainian, Russian and Romanian media spaces. In a data-driven way, we describe how the narratives are spread throughout Eastern and Central Europe. We present predictive linguistic features surrounding war propaganda. Our results indicate that there are strong similarities in terms of rhetoric strategies in the pro-Kremlin media in both Ukraine and Russia, which, while being relatively neutral according to surface structure, use aggressive vocabulary. This suggests that automatic propaganda identification systems have to be tailored for each new case, as they have to rely on situationally specific words. Both Ukrainian and Russian outlets lean towards strongly opinionated news, pointing towards the use of war propaganda in order to achieve strategic goals.

Keywords: linguistic, news, propaganda, Russia, ukraine

Procedia PDF Downloads 111

Authors: Eko Adhi Setiawan, Duli Asih Siregar, Aiman Setiawan

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Solar energy is abundant in nature, particularly in the tropics which have peak sun hour that can reach 8 hours per day. In the fabrication process, Photovoltaic’s (PV) performance are tested in standard test conditions (STC). It specifies a module temperature of 25°C, an irradiance of 1000 W/ m² with an air mass 1.5 (AM1.5) spectrum and zero wind speed. Thus, the results of the performance testing of PV at STC conditions cannot fully represent the performance of PV in the tropics. For example Indonesia, which has a temperature of 20-40°C. In this paper, the effect of temperature on the choice of the 5 kW AC inverter topology on the PV system such as the Central Inverter, String Inverter and AC-Module specifically for the tropics will be discussed. The proper inverter topology can be determined by analysis of the effect of temperature and irradiation on the PV panel. The effect of temperature and irradiation will be represented in the characteristics of I-V and P-V curves. PV’s characteristics on high temperature would be analyzed using Solar panel modeling through MATLAB Simulink based on mathematical equations that form Solar panel’s characteristic curve. Based on PV simulation, it is known then that temperature coefficients of short circuit current (ISC), open circuit voltage (VOC), and maximum output power (PMAX) consecutively as high as 0.56%/oC, -0.31%/oC and -0.4%/oC. Those coefficients can be used to calculate PV’s electrical parameters such as ISC, VOC, and PMAX in certain earth’s surface’s certain point. Then, from the parameters, the utility of the 5 kW AC inverter system can be determined. As the result, for tropical area, string inverter topology has the highest utility rates with 98, 80 %. On the other hand, central inverter and AC-Module Topology has utility rates of 92.69 % and 87.7 % eventually.

Keywords: Photovoltaic, PV-Inverter Configuration, PV Modeling, Solar Panel Characteristics.

Procedia PDF Downloads 373

Authors: Cita Ayeni

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Amidst numerous arguments on reasons for low Human Development (low HDI) in Nigeria ranging from corruption, incompetence of the government and its agencies, mismanagement of funds, terrorism, violence, and crime in the country, just to mention a few. There have been several actions by agencies of the government that for years has threatened the security and development of the citizens, and the country in a broader sense. This paper analyses the activities of SARS (Special Anti-Robbery Squad) as a government agency with a mandate to tackling the high rate of crime in the country but instead have been marred with allegations of violence, killings, extortion, harsh treatment, and terror of the Nigerian citizenry, predominantly the youths. This paper establishes the effect of these actions of the agency on human development in Nigeria, hindering the capacity of the Nigerian youths to earn a decent living due to constant terrorism, extortion, and extrajudicial activities, which in numerous cases resulted in maiming and death, thus instigating fear in the vast majority. This research further analyses the executive order by the then Acting President of Nigeria (Vice-President) that overhauled the agency following many years of continuous public outcry, complaint, grievance, and protest. This work establishes that this order carried out in the absence of the President was to a large extent enough to stop these violations, thereby resulting in little or no recorded complaint or grievance by the public, as many of the officials involved in the gruesome activities were said to have been put away. This would pave way and give freedom to the youths to realize their potentials free from intimidation, violence, and fear from the agencies created to protect them, and on the other hand refocus the new agency FSARS (Federal Special Anti-Robbery Squad) on its real mandate in collaboration with independent organizations acting as a check to its actions. This work thus depicts how direct executive orders on policies pertaining to individual insecurities, on youths in this case, in a country can be a potential drive to increased human development.

Keywords: special anti-robbery squad, Nigerian youths, overhaul, insecurities, human development

Procedia PDF Downloads 163

Authors: Emmanuel Kamal Aziz Saba

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Aim of the work: This study proposed to assess the role of the median versus ulnar medial thenar motor (MTM) recording in supporting the diagnosis of carpal tunnel syndrome (CTS). Patients and methods: The present study included 130 hands (70 CTS and 60 controls). Clinical examination was done for all patients. The following tests were done (using surface electrodes recording) for patients and control: (1) sensory nerve conduction studies: median nerve, ulnar nerve and median versus ulnar digit four sensory study; (2) motor nerve conduction studies: median nerve, ulnar nerve, median (second lumbrical) versus ulnar (interosseous) (2-LINT) motor study and median versus ulnar (MTM) study. Results: The tests with higher sensitivity in diagnosing CTS were median versus ulnar (2-LINT) motor latency difference (87.1%), median versus ulnar (MTM) motor latency difference (80%) and median versus ulnar digit four sensory latency differences (91.4%). There was no statistically significant difference between median versus ulnar (MTM) motor latency difference with both median versus ulnar (2-LINT) motor latency difference and median versus ulnar digit four sensory latency difference (P > 0.05) as regards the confirmation of CTS. Conclusions: Median versus ulnar (MTM) motor latency difference has high sensitivity and specificity for the diagnosis of CTS as for both median versus ulnar (2-LINT) motor latency difference and median versus ulnar digit four sensory latency differences. It can be considered a useful neurophysiological test to be used in combination with another median versus ulnar comparative tests for confirming the diagnosis of CTS beside other well-known electrophysiological tests.

Keywords: carpal tunnel syndrome, medial thenar motor, median nerve, ulnar nerve

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Authors: Simone Balin, Cecilia M. Bolognesi, Paolo Borin

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In the construction industry, there is a large amount of data and interconnected information. To manage this information effectively, a transition to the immersive digitization of information processes is required. This transition is important to improve knowledge circulation, product quality, production sustainability and user satisfaction. However, there is currently a lack of a common definition of immersion in the construction industry, leading to misunderstandings and limiting the use of advanced immersive technologies. Furthermore, the lack of guidelines and a common vocabulary causes interested actors to abandon the virtual world after the first collaborative steps. This research aims to define the optimal use of immersive technologies in the AEC sector, particularly for collaborative processes based on the BIM methodology. Additionally, the research focuses on creating classes and levels to structure and define guidelines and a vocabulary for the use of the " Immersive Need Level." This concept, matured by recent technological advancements, aims to enable a broader application of state-of-the-art immersive technologies, avoiding misunderstandings, redundancies, or paradoxes. While the concept of "Informational Need Level" has been well clarified with the recent UNI EN 17412-1:2021 standard, when it comes to immersion, current regulations and literature only provide some hints about the technology and related equipment, leaving the procedural approach and the user's free interpretation completely unexplored. Therefore, once the necessary knowledge and information are acquired (Informational Need Level), it is possible to transition to an Immersive Need Level that involves the practical application of the acquired knowledge, exploring scenarios and solutions in a more thorough and detailed manner, with user involvement, via different immersion scales, in the design, construction or management process of a building or infrastructure. The need for information constitutes the basis for acquiring relevant knowledge and information, while the immersive need can manifest itself later, once a solid information base has been solidified, using the senses and developing immersive awareness. This new approach could solve the problem of inertia among AEC industry players in adopting and experimenting with new immersive technologies, expanding collaborative iterations and the range of available options.

Keywords: AECindustry, immersive technology (IMT), virtual reality, augmented reality, building information modeling (BIM), decision making, collaborative process, information need level, immersive level of need

Procedia PDF Downloads 84

Authors: Vabya Kumar Pandit, Mudit Mittal, N. Prahlad Rao, Ramnath Babu

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TeamIndus is the only Indian team competing for the Google Lunar XPRIZE(GLXP). The GLXP is a global competition to challenge the private entities to soft land a rover on the moon, travel minimum 500 meters and transmit high definition images and videos to Earth. Towards this goal, the TeamIndus strategy is to design and developed lunar lander that will deliver a rover onto the surface of the moon which will accomplish GLXP mission objectives. This paper showcases the various system level noise control techniques adopted by Electrical Distribution System (EDS), to achieve the required Electromagnetic Compatibility (EMC) of the spacecraft. The design guidelines followed to control Electromagnetic Interference by proper electronic package design, grounding, shielding, filtering, and cable routing within the stipulated mass budget, are explained. The paper also deals with the challenges of achieving Electromagnetic Cleanliness in presence of various Commercial Off-The-Shelf (COTS) and In-House developed components. The methods of minimizing Electrostatic Discharge (ESD) by identifying the potential noise sources, susceptible areas for charge accumulation and the methodology to prevent arcing inside spacecraft are explained. The paper then provides the EMC requirements matrix derived from the mission requirements to meet the overall Electromagnetic compatibility of the Spacecraft.

Keywords: electromagnetic compatibility, electrostatic discharge, electrical distribution systems, grounding schemes, light weight harnessing

Procedia PDF Downloads 287

Authors: Xiaojie Cheng, Ulrike Frank, Feng Zhao, Karin Pritsch

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Ragweed (Ambrosia artemisiifolia) is an invasive weed that has become an increasing global problem. In addition to affecting land use and crop yields, ragweed has a strong impact on human health as it produces highly allergenic pollen. Global warming will result in an earlier and longer pollen season enhanced pollen production and an increase in pollen allergenicity with a negative effect on atopic patients. The aims of this study were to investigate the effects of increasing temperature, the future climate scenario in the Munich area, southern Germany, predicted on the basis of RCP8.5 until the end of 2050s, or/and NO₂, a major air pollutant, 1) on the vegetative and reproductive characteristics of ragweed plants, 2) on the total allergenicity of ragweed pollen, 3) on the total pollen proteomic patterns. Ragweed plants were cultivated for the whole plant vegetation period under controlled conditions either under ambient climate conditions or 4°C higher temperatures with or without additional NO₂. Higher temperature resulted in bigger plant sizes, longer male inflorescences, and longer pollen seasons. The total allergenic potential of the pollen was accessed by dot blot using serum from ragweed pollen sensitized patients. The comparative immunoblot analysis revealed that the in vivo fumigation of ragweed plants with elevated NO₂-concentrations significantly increased the allergenic potential of the pollen, and in combination with increased temperature, the allergenic potential was even higher. On the other hand, label-free protein quantification by liquid chromatography-tandem mass spectrometry (LC-MS/MS) was performed. The results showed that more proteins were significantly up- and down-regulated under higher temperatures with/without elevated NO₂ conditions. Most of the highly expressed proteins were participating intensively in the metabolic process, the cellular process, and the stress defense process. These findings suggest that rising temperature and elevated NO₂ are important environmental factors for higher abiotic stress activities, catalytic activities, and thus higher allergenic potential observed in pollen proteins.

Keywords: climate change, NO₂, pollen proteome, ragweed, temperature

Procedia PDF Downloads 174

Authors: Altab Hossain, Shakerul Islam, Golamur R. Khan, Abu Zafar M. Salahuddin

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An effective identification of breakdowns is of premier importance for the safe and reliable operation of Nuclear Power Plants (NPP) and its associated facilities. A great number of monitoring and diagnosis methodologies are applied and used worldwide in areas such as industry, automobiles, hospitals, and power plant to detect and reduce human disasters. The potential consequences of several hazardous activities may harm the society using nuclear and its associated facilities. Hence, one of the most popular and effective methods to ensure safety and monitor the entire nuclear facility and imply risk-free operation without human interference during the hazardous situation is using a robot. Therefore, in this study, an advanced autonomous robot has been designed and developed that can monitor several parameters in the NPP to ensure the safety and do some risky job in case of nuclear disaster. The robot consisted of autonomous track following unit, data processing and transmitting unit can follow a straight line and take turn as the bank greater than 90 degrees. The developed robot can analyze various parameters such as temperature, altitude, radiation, obstacle, humidity, detecting fire, measuring distance, ultrasonic scan and taking the heat of any particular object. It has an ability to broadcast live stream and can record the document to its own server memory. There is a separate control unit constructed with a baseboard which processes the recorded data and a transmitter which transmits the processed data. To make the robot user-friendly, the code is developed such a way that a user can control any of robotic arm as per types of work. To control at any place and without the track, there is an advanced code has been developed to take manual overwrite. Through this process, administrator who has logged in permission to Dynamic Host Client Protocol (DHCP) can make the handover of the control of the robot. In this process, this robot is provided maximum nuclear security from being hacked. Not only NPP, this robot can be used to maximize the real-time monitoring system of any nuclear facility as well as nuclear material transportation and decomposition system.

Keywords: nuclear power plant, radiation, dynamic host client protocol, nuclear security

Procedia PDF Downloads 199

Authors: Hong Yu, Ion Matei

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Carbon fiber reinforced composites (CFRP) used as aircraft structure are subject to lightning strike, putting structural integrity under risk. Indirect damage may occur after a lightning strike where the internal structure can be damaged due to excessive heat induced by lightning current, while the surface of the structures remains intact. Three damage modes may be observed after a lightning strike: fiber breakage, inter-ply delamination and intra-ply cracks. The assessment of internal damage states in composite is challenging due to complicated microstructure, inherent uncertainties, and existence of multiple damage modes. In this work, a model based approach is adopted to diagnose faults in carbon composites after lighting strikes. A resistor network model is implemented to relate the overall electrical and thermal conduction behavior under simulated lightning current waveform to the intrinsic temperature dependent material properties, microstructure and degradation of materials. A fault detection and identification (FDI) module utilizes the physics based model and a particle filtering algorithm to identify damage mode as well as calculate the probability of structural failure. Extensive simulation results are provided to substantiate the proposed fault diagnosis methodology with both single fault and multiple faults cases. The approach is also demonstrated on transient resistance data collected from a IM7/Epoxy laminate under simulated lightning strike.

Keywords: carbon composite, fault detection, fault identification, particle filter

Procedia PDF Downloads 186

Authors: Barenten Suciu

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In this work, effects of the friction and truncation on the dynamics of a double-cone gravitational motor, self-propelled on a straight V-shaped horizontal rail, are evaluated. Such mechanism has a variable radius of contact, and, on one hand, it is similar to a pulley mechanism that changes the potential energy into the kinetic energy of rotation, but on the other hand, it is similar to a pendulum mechanism that converts the potential energy of the suspended body into the kinetic energy of translation along a circular path. Movies of the self- propelled double-cones, made of S45C carbon steel and wood, along rails made of aluminum alloy, were shot for various opening angles of the rails. Kinematical features of the double-cones were estimated through the slow-motion processing of the recorded movies. Then, a kinematical model is derived under assumption that the distance traveled by the contact points on the rectilinear rails is identical with the distance traveled by the contact points on the truncated conical surface. Additionally, a dynamic model, for this particular contact problem, was proposed and validated against the experimental results. Based on such model, the traction force and the traction torque acting on the double-cone are identified. One proved that the rolling traction force is always smaller than the sliding friction force; i.e., the double-cone is rolling without slipping. Results obtained in this work can be used to achieve the proper design of such gravitational motor.

Keywords: Truncated double-cone, friction, rolling and sliding, dynamic model, gravitational motor

Procedia PDF Downloads 265

Authors: Sujay Bisht

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The purpose of the study was to assess and examines the pattern of injury among the field hockey players at different field position during practice & game. It was hypothesized that the backfield might have the height rate of injury, followed by midfield. Methods: university level and national level male field hockey (N=60) are selected as a subject and requested to respond an anon questionnaire. Personal characteristics of each and individual players were also collected like (age, height, weight); field hockey professional information (level of play, year of experience, playing surface); players injury history (site, types, cause etc). The rates of injury per athlete per year were also calculated. Result: Around half of the injury occurred were to the lower limbs (49%) followed by head and face (30%), upper limbs (19%) and torso region (2%). Injuries included concussion, wounds, broken nose, ligament sprain, dislocation, fracture, and muscles strain and knee injury. The ligament sprain is the highest rate (40%) among the other types of injuries. After investigation and evaluation backfield players had the highest rate of risk of injury (1.10 injury/athletes-year) followed by midfield players (0.70 injury/athlete-year), forward players (0.45 injury/athlete-year) & goalkeeper was (0.37 injury/athlete-year). Conclusion: Due to the different field position the pattern & rate of injury were different. After evaluation, lower limbs had the highest rate of injury followed by head and face, upper limbs and torso respectively. It also revealed that not only there is a difference in the rate of injury between playing the position, but also in the types of injury sustain at a different position.

Keywords: trauma, sprain, strain, astroturf, acute injury

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Authors: N. Hedayat, E. Karamifar

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Sustainable food and fiber production is emerging as an irresistible option in agrarian planning. Although one should not underestimate the successes of the Green Revolution in enhancing crop production, its adverse environmental and ecosystem consequences have also been remarkable. The aim of this paper is to identify ways of improving crop production to ensure agricultural sustainability and environmental integrity. Systematic observations are used for data collection on intensive farming, deforestation and the environmental implications of industrial pollutants on agricultural sustainability at national and international levels. These were achieved within a comparative analytical model of data interpretation. Results show that while multiple factors enhance yield, they have a simultaneous effect in undermining the ecosystem and environmental integrity. Results show that application of excessive agrichemical have been one of the major cause of polluting the surface and underground water bodies as well as soil layers in affected croplands. Results consider rapid deforestation in the tropical regions has been the underlying cause of impairing the integrity of biodiversity and oxygen-generation regime. These, coupled with production of greenhouse gasses, have contributed to global warming and hydrological irregularities. Continuous production of pollutants and effluents has affected marine and land biodiversity arising from acid rains generated by modern farming and deforestation. Continuous production of greenhouse gases has also been instrumental in affecting climatic behavior manifested in recurring draughts and contraction of lakes and ponds as well as emergence of potential flooding of waterways and floodplains in the future.

Keywords: agricultural sustainability, environmental integrity, pollution, eco-system

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Authors: Kamrun N. Keya, Nasrin A. Kona, Ruhul A. Khan

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Sugarcane bagasse (SCB)-reinforced Polypropylene (PP) Based matrix composites (25-45 wt% fiber) were fabricated by a compression molding technique. The SCB surface was chemically modified using 5%-10% sodium hydroxide (NaOH), and after that, mechanical properties, water uptake, and soil degradation of the composites were investigated. Tensile strength (TS), tensile modulus (TM), bending strength (BS), bending modulus (BM) and elongation at break (Eb%) of the 30wt% composites were found to be 35.6 MPa, 10.2 GPa, 56 MPa, 5.6 GPa, and 11%, respectively. The SCB/PP based composites were treated with irradiated under gamma radiation (the source strength 50 kCi Cobalt-60) of various doses (2.5 kGy to 10 kGy). The effect of gamma radiation on the composites was also investigated, and it found that the effect of 5.0 kGy (i.e. units for radiation measurement is 'gray', kGy=kilogray ) gamma dose showed better mechanical properties than other doses. The results revealed that the combination of the chemical modification of the SCB fibers and irradiation of the composites were more effective in compatibility improvement than chemical modification alone. After flexural testing, fracture sides of the untreated and treated both composites were studied by scanning electron microscope (SEM). SEM results of the treated SCB/PP based composites showed better fiber-matrix adhesion than untreated SCB/PP based composites. However, it was found that the treated SCB/PP composite has better mechanical strength, durability, and more receptivity than untreated SCB/PP based composite.

Keywords: sugarcane bagasse (SCB), polypropylene (PP), mechanical properties, scanning electron microscope (SEM), gamma radiation, water uptake tests and soil degradation

Procedia PDF Downloads 128

Authors: Saja M. Nabat Al-Ajrash, Charles Browning, Rose Eckerle, Li Cao

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Three preceramic polymer formulations for potential use in 3D printing technologies were investigated. The polymeric precursors include an allyl hydrido polycarbosilane (SMP-10), SMP-10/1,6-dexanediol diacrylate (HDDA) mixture, and polydimethylsiloxane (PDMS). The rheological property of the polymeric precursors, including the viscosity within a wide shear rate range was compared to determine the applicability in additive manufacturing technology. The structural properties of the polymeric solutions and their photocureability were investigated using Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). Moreover, thermogravimetric analysis (TGA) and X-ray diffraction (XRD) were utilized to study polymeric to ceramic conversion for versatile precursors. The prepared precursor resin proved to have outstanding photo-curing properties and the ability to transform to the silicon carbide phase at temperatures as low as 850 °C. The obtained ceramic was fully dense with nearly linear shrinkage and a shiny, smooth surface after pyrolysis. Furthermore, after pyrolysis to 1350 °C and TGA analysis, PDMS polymer showed the highest onset decomposition temperature and the lowest retained weight (52 wt%), while SMP.10/HDDA showed the lowest onset temperature and ceramic yield (71.7 wt%). In terms of crystallography, the ceramic matrix composite appeared to have three coexisting phases, including silicon carbide, and silicon oxycarbide. The results are very promising to fabricate ceramic materials working at high temperatures with complex geometries.

Keywords: preceramic polymer, silicon carbide, photocuring, allyl hydrido polycarbosilane, SMP-10

Procedia PDF Downloads 116

Authors: Daniel Canales, Fabián Alvarez, Pablo Varela, Marcela Saavedra, Claudio García, Paula Zapata

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Calcium oxide nanoparticles (n-CaO) ca. 8 nm were obtained from eggshell waste. The n-CaO was incorporated into Poly(lactic acid) PLA matrix in 10 and 20 wt.% of filler content by electrospinning process to obtain PLA/n-CaO nanocomposite fibers as a potential use in scaffold for bone tissue regeneration. The fibers morphology and diameter were homogeneity, the PLA had a diameter of 2.2 ± 0.8 µm and, with the nanoparticles incorporation (20wt.%), reached ca. 2.9 ± 0.9 µm. The PLA/n-CaO nanocomposites fibers showed in vitro bioactivity, capable of inducing the precipitation of hydroxyapatite (HA) layer in the fiber surface after 7 days in Simulated Body Solution (SBF). The biocidal and biological properties of PLA/n-Cao with 20 wt.% were evaluated, showing a 30% reduction in bacterial viability against S. aureus and 11% for E. coli after 6 hours of bacterial suspensions exposure. Furthermore, the fibers did not show a cytotoxic effect on the bone marrow ST-2 cell line, permitting the cell adhesion and proliferation in Roswell Park Memorial Institute medium (RPMI). The PLA/n-CaO with 20 wt.% of nanoparticles showed a higher capacity to promote the osteogenic differentiation, significantly increasing the alkaline phosphatase (ALP) expression after 7 days compared to PLA and cell control. The in vivo analysis corroborated the biocompatibility of scaffolds prepared, the presence of n-CaO in PLA reduced the formation of fibrous encapsulation of the material improve the healing process.

Keywords: electrospun scaffolds, PLA based nanocomposites, calcium oxide nanoparticles, bioactive materials, tissue engineering

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Authors: Thomas Chinedu Aniokete, Gordian Onyebuchukwu Mbah, Michael Daramola

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A sustainable NaOH integrated hydrothermal protocol was developed for the synthesis of waste-derived hydroxy sodalite catalysts for transesterification of waste animal fat (WAF) with a high per cent free fatty acid (FFA) to biodiesel. In this work, hydroxy sodalite catalyst was synthesized from two complex waste materials namely coal fly ash (CFA) and waste industrial brine (WIB). Measured amounts of South African CFA and WIB obtained from a coal mine field were mixed with NaOH solution at different concentrations contained in secured glass vessels equipped with magnetic stirrers and formed consistent slurries after aging condition at 47 oC for 48 h. The slurries were then subjected to hydrothermal treatments at 140 oC for 48 h, washed thoroughly and separated by the action of a centrifuge on the mixture. The resulting catalysts were calcined in a muffle furnace for 2 h at 200 oC and subsequently characterized for different effects using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR), and Bennett Emmet Teller (BET) adsorption-desorption techniques. The produced animal fat methyl ester (AFME) was analyzed using the gas chromatography-mass spectrometry (GC-MS) method. Results of the investigation indicate profoundly an enhanced catalyst purity, textural property and desired morphology due to the action of NaOH. Similarly, the performance evaluation with respect to catalyst activity reveals a high catalytic conversion efficiency of 98 % of the high FFA WAF to biodiesel under the following reaction conditions; a methanol-to-WAF ratio of 15:1, amount of SOD catalyst of 3 wt % with a stirring speed of 300-500 rpm, a reaction temperature of 60 oC and a reaction time of 8 h. There was a recovered 96 % stable catalyst after reactions and potentially recyclable, thus contributing to the economic savings to the process that had been a major bottleneck to the production of biodiesel. This NaOH route for synthesizing waste-derived hydroxy sodalite (SOD) catalyst is a sustainable and eco-friendly technology that speaks directly to the global quest for renewable-fossil fuel controversy enforcing sustainable development goal 7.

Keywords: coal fly ash, waste industrial brine, waste-derived hydroxy sodalite catalyst, sodium hydroxide, biodiesel, transesterification, biomass conversion

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Authors: Shrutika Lakshmi

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Gender inequality has been quite evident particularly in the third world economies in different domains like health, education, marriages and personal freedom. Women’s exercise to personal freedom is driven by their financial standing in third world social milieu. However, even after decades of attempt to achieve a socio-economic standing equal to men, their attempts have failed in registering success.This research has been conducted in the national capital of India New Delhi aiming to reflect upon the gendered relations in society on the category of employed women. This particular category of women have been chosen for the study in order to study the gender relations, subordination of such women in household despite having an economic standing of their own, etc. The methodology used for this study is semi-structured interview along with qualitative analysis. Moreover, with the help of direct interaction with these women, we get insight into the kind of gendered relations prevailing inside the household structure which have their roots in age old customs and stereotype of the social milieu. Most importantly, the highlight of the study remains on the point where the hierarchy remains in the subconscious of these women and they never forget their social standing. It has been interesting to note that how even after contributing to the family income successively, their position remains subjugated in front of their male counterparts and thus, they are not ‘free’ in the real sense of the term. Even after attaining an economically stable position, these women did not enjoy the same comfort and freedom of choice as their male counterparts do, this could be gauged from the fact that when asked about ‘time for one’s own self’ they had no sense of it. This is astonishing in today’s world where every individual works and strives for a better livelihood and quality existence. Such findings reflect upon the reality of our society where women are still subjugated and duty bound towards the household even after having the same economic stand as their male counterparts. The burden of household chores and responsibilities fall solely on the shoulders of a women despite being an employed women even in the present times. Cooperation comes primarily from female members of the household and not from males. And thus, we as a society are far away from gender equity. We still suffer from prejudices and stereotypes which prevent us from giving same respect to women which we keep reserved for the man. Given this scenario, it seems, gender equity is a distant goal which we will have to keep striving for even harder even after decades of feminist struggles all over the world.

Keywords: employed women, subjugation in household, gender hierarchy, financial independence,

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Authors: Baljinder Singh, Navneet Sharma

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The skin can be used as the site for drug administration for continuous transdermal drug infusion into the systemic circulation. For the continuous diffusion/penetration of the drugs through the intact skin surface membrane-moderated systems, matrix dispersion type systems, adhesive diffusion controlled systems and micro reservoir systems have been developed. Various penetration enhancers are used for the drug diffusion through skin. In matrix dispersion type systems, the drug is dispersed in the solvent along with the polymers and solvent allowed to evaporate forming a homogeneous drug-polymer matrix. Matrix type systems were developed in the present study. In the present work, an attempt has been made to develop a matrix-type transdermal therapeutic system comprising of ondansetron-HCl with different ratios of hydrophilic and hydrophobic polymeric combinations using solvent evaporation technique. The physicochemical compatibility of the drug and the polymers was studied by infrared spectroscopy. The results obtained showed no physical-chemical incompatibility between the drug and the polymers. The patches were further subjected to various physical evaluations along with the in-vitro permeation studies using rat skin. On the basis of results obtained form the in vitro study and physical evaluation, the patches containing hydrophilic polymers i.e. polyvinyl alcohol and poly vinyl pyrrolidone with oleic acid as the penetration enhancer(5%) were considered as suitable for large scale manufacturing with a backing layer and a suitable adhesive membrane.

Keywords: transdermal drug delivery, penetration enhancers, hydrophilic and hydrophobic polymers, ondansetron HCl

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Authors: Wayde Veldman, Ozlem T. Bishop, Igor Polikarpov

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In bacteria, mono and disaccharides are phosphorylated during uptake into the cell via the widely used phosphoenolpyruvate (PEP)-dependent phosphotransferase transport system. As an initial step in the phosphorylated disaccharide metabolism pathway, certain glycoside hydrolase family 1 (GH1) enzymes play a crucial role in releasing phosphorylated and non-phosphorylated monosaccharides. However, structural determinants for the specificity of these enzymes still need to be clarified. GH1 enzymes are known to have a wide array of functions. According to the CAZy database, there are twenty-one different enzymatic activities in the GH1 family. Here, the structure and substrate specificity of a GH1 enzyme from Bacillus licheniformis, hereafter known as BlBglH, was investigated. The sequence of the enzyme BlBglH was compared to the sequences of other characterized GH1 enzymes using sequence alignment, sequence identity calculations, phylogenetic analysis, and motif discovery. Through these various analyses, BlBglH was found to have sequence features characteristic of the 6-phospho-β-glucosidase activity enzymes. Additionally, motif and structure comparisons of the three most commonly studied GH1 enzyme-activities revealed a shared loop amongst the different structures that consist of different sequence motifs – this loop is thought to guide specific substrates (depending on activity) towards the active-site. To further affirm BlBglH enzyme activity, molecular docking and molecular dynamics simulations were performed. Docking was carried out using 6-phospho-β-glucosidase enzyme-activity positive (p-Nitrophenyl-beta-D-glucoside-6-phosphate) and negative (p-Nitrophenyl-beta-D-galactoside-6-phosphate) control ligands, followed by 400 ns molecular dynamics simulations. The positive-control ligand maintained favourable interactions within the active site until the end of the simulation. The negative-control ligand was observed exiting the enzyme at 287 ns. Binding free energy calculations showed that the positive-control complex had a substantially more favourable binding energy compared to the negative-control complex. Jointly, the findings of this study suggest that the BlBglH enzyme possesses 6-phospho-β-glucosidase enzymatic activity.

Keywords: 6-P-β-glucosidase, glycoside hydrolase 1, molecular dynamics, sequence analysis, substrate specificity

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Authors: Supriya Manikrao Ovhal

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In India, the summer monsoon rainfall occurs owing to large scale convection with reference to continental ITCZ. It was found that convection over tropical ocean increases with SST from 26 to 28 degree C, and when SST is above 29 degree C, it sharply decreases for warm pool areas of Indian and for monsoon areas of West Pacific Ocean. The reduction in convection can be influenced by large scale subsidence forced by nearby or remotely generated deep convection, thus it was observed that under the influence of strong large scale rising motion, convection does not decreases but increases monotonically with SST even if SST value is higher than 29.5 degree C. Since convection is related to SST gradient, that helps to generate low level moisture convergence and upward vertical motion in the atmosphere. Strong wind fields like cross equatorial low level jet stream on equator ward side of the warm pool are produced due to convection initiated by SST gradient. Areas having maximum SST have low SST gradient, and that result in feeble convection. Hence it is imperative to mention that the oceanic role (other than SST) could be prominent in influencing large Scale Atmospheric convection. Since warm oceanic surface somewhere or the other contributes to penetrate the heat radiation to the subsurface of the ocean, and as there is no studies seen related to oceanic subsurface role in large Scale Atmospheric convection, in the present study, we are concentrating on the oceanic subsurface contribution in large Scale Atmospheric convection by considering the SST gradient, mixed layer depth (MLD), thermocline, barrier layer. The present study examines the probable role of subsurface ocean parameters in influencing convection.

Keywords: sst, d20, olr, wind

Procedia PDF Downloads 86

Authors: Gregory Chown, Benjamin Infantolino, Christopher Wise, Rachel Holmes, Samantha O'Donnell, Katelyn Pfeiffer, Victoria Ward

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Background: There is a lack of understanding of how Kinesio Tape® physiologically works. Furthermore, few studies compare Kinesio Tape® to other forms of taping. The research question is: Does Kinesio Tape® cause a difference in muscle facilitation, inhibition, and pain, between Kinesio Tape® and no tape for collegiate athletes with self-reported shoulder pain? Method: This quantitative non-randomized design used a convenience sampling method. There were eleven participants with self-reported shoulder pain who were athletes on the men’s and women’s lacrosse and tennis teams. Participants attended one 30-45 minute session for data collection. Each participant received all three taping conditions and performed four repetitions of 120 degrees of active shoulder flexion for the three separate trials (no tape, Kinesio Tape® inhibition, and Kinesio Tape® facilitation). Surface electromyography (sEMG) electrodes were placed on the anterior deltoid, supraspinatus, and lower trapezius to measure muscle facilitation and inhibition. Each participant completed the visual analogue scale (VAS) before and after each trial to measure pain. Results: No statistical significance was found for pain scores on the VAS between the taping methods of facilitation, inhibition, and no tape (p = .118). No statistical significance was found for the percentage of change in muscle function for each taping method; Anterior deltoid (p = .993), supraspinatus (p = .997) and lower trapezius (p = .922). Conclusion: Based on the results, Kinesio Tape® appears to not have an effect on muscle function or pain when utilizing the facilitation or inhibition taping method when compared to no tape.

Keywords: Kinesio tape, muscle facilitation, muscle inhibition, pain

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Authors: Thangavelu Muthukumar, Thotapalli Parvathaleswara Sastry

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Collagen is the most abundantly available connective tissue protein, which is being used as a biomaterial for various biomedical applications. Presently, fish wastes are disposed improperly which is causing serious environmental pollution resulting in offensive odour. Fish scales are promising source of Type I collagen. Medicinal plants have been used since time immemorial for treatment of various ailments of skin and dermatological disorders especially cuts, wounds, and burns. Developing biomaterials from the natural sources which are having wound healing properties within the search of a common man is the need of hour, particularly in developing and third world countries. With these objectives in view we have developed a wound dressing material containing fish scale collagen (FSC) incorporated with Macrotyloma uniflorum plant extract (PE). The wound dressing composite was characterized for its physiochemical properties using conventional methods. SEM image revealed that the composite has fibrous and porous surface which helps in transportation of oxygen as well as absorbing wound fluids. The biomaterial has shown 95% biocompatibility with required mechanical strength and has exhibited antimicrobial properties. This biomaterial has been used as a wound dressing material in experimental wounds of rats. The healing pattern was evaluated by macroscopic observations, panimetric studies, biochemical, histopathological observations. The results showed faster healing pattern in the wounds treated with CSPE compared to the other composites used in this study and untreated control. These experiments clearly suggest that CSPE can be used as wound/burn dressing materials.

Keywords: collagen, wound dressing, Macrotyloma uniflorum, burn dressing

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Authors: Caroline M. Spagnol, Vera L. B. Isaac, Marcos A. Corrêa, Hérida R. N. Salgado

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Phenolic compounds are abundant in the Brazilian plant kingdom and they are part of a large and complex group of organic substances. Cinnamic acids are part of this group of organic compounds, and caffeic acid (CA) is one of its representatives. Antioxidants are compounds which act as free radical scavengers and, in other cases, such as metal chelators, both in the initiation stage and the propagation of oxidative process. The tyrosinase, polyphenol oxidase, is an enzyme that acts at various stages of melanin biosynthesis within the melanocytes and is considered a key molecule in this process. Some phenolic compounds exhibit inhibitory effects on melanogenesis by inhibiting the tyrosinase enzymatic activity and therefore has been the subject of studies. However, few studies have reported the effectiveness of these products and their safety. Objectives: To assess the inhibitory activity of tyrosinase, the antioxidant activity of CA and its cytotoxic potential. The method to evaluate the inhibitory activity of tyrosinase aims to assess the reduction transformation of L-dopa into dopaquinone reactions catalyzed by the enzyme. For evaluating the antioxidant activity was used the analytical methodology of DPPH radical inhibition. The cytotoxicity evaluation was carried out using the MTT method (3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide), a colorimetric assay which determines the amount of insoluble violet crystals formed by the reduction of MTT in the mitochondria of living cells. Based on the results obtained during the study, CA has low activity as a depigmenting agent. However, it is a more potent antioxidant than ascorbic acid (AA), since a lower amount of CA is sufficient to inhibit 50% of DPPH radical. The results are promising since CA concentration that promoted 50% toxicity in HepG2 cells (IC50=781.8 μg/mL) is approximately 330 to 400 times greater than the concentration required to inhibit 50% of DPPH (IC50 DPPH= 2.39 μg/mL) and ABTS (IC50 ABTS= 1.96 μg/mL) radicals scavenging activity, respectively. The maximum concentration of caffeic acid tested (1140 mg /mL) did not reach 50% of cell death in HaCat cells. Thus, it was concluded that the caffeic acid does not cause toxicity in HepG2 and HaCat cells in the concentrations required to promote antioxidant activity in vitro, and it can be applied in topical products.

Keywords: caffeic acid, antioxidant, cytotoxicity, cosmetic

Procedia PDF Downloads 369

Authors: Syed Irfan Raza Naqvi, Zheng Jiangbin, Ahmad Moshin, Pervez Akhter

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Currently, the IoT system depends on a centralized client-servant architecture that causes various scalability and privacy vulnerabilities. Distributed ledger technology (DLT) introduces a set of opportunities for the IoT, which leads to practical ideas for existing components at all levels of existing architectures. Blockchain Technology (BCT) appears to be one approach to solving several IoT problems, like Bitcoin (BTC) and Ethereum, which offer multiple possibilities. Besides, IoTs are resource-constrained devices with insufficient capacity and computational overhead to process blockchain consensus mechanisms; the traditional BCT existing challenge for IoTs is poor scalability, energy efficiency, and transaction fees. IOTA is a distributed ledger based on Direct Acyclic Graph (DAG) that ensures M2M micro-transactions are free of charge. IOTA has the potential to address existing IoT-related difficulties such as infrastructure scalability, privacy and access control mechanisms. We proposed an architecture, SLDBI: A Scalable, lightweight DAG-based Blockchain Design for Intelligent IoT Systems, which adapts the DAG base Tangle and implements a lightweight message data model to address the IoT limitations. It enables the smooth integration of new IoT devices into a variety of apps. SLDBI enables comprehensive access control, energy efficiency, and scalability in IoT ecosystems by utilizing the Masked Authentication Message (MAM) protocol and the IOTA Smart Contract Protocol (ISCP). Furthermore, we suggest proof-of-work (PoW) computation on the full node in an energy-efficient way. Experiments have been carried out to show the capability of a tangle to achieve better scalability while maintaining energy efficiency. The findings show user access control management at granularity levels and ensure scale up to massive networks with thousands of IoT nodes, such as Smart Connected Buildings (SCBDs).

Keywords: blockchain, IOT, direct acyclic graphy, scalability, access control, architecture, smart contract, smart connected buildings

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Authors: Lucian Capitanu, Virgil Florescu

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Often for the laboratory studies, modeling of specific tribological processes raises special problems. One such problem is the modeling of some temperatures and extremely high contact pressures, allowing modeling of temperatures and pressures at which the injection or extrusion processing of thermoplastic materials takes place. Tribological problems occur mainly in thermoplastics materials reinforced with glass fibers. They produce an advanced wear to the barrels and screws of processing machines, in short time. Obtaining temperatures around 210 °C and higher, as well as pressures around 100 MPa is very difficult in the laboratory. This paper reports a simple and convenient solution to get these conditions, using friction sliding couples with linear contact, cylindrical liner plastic filled with glass fibers on plate steel samples, polished and super-finished. C120 steel, which is a steel for moulds and Rp3 steel, high speed steel for tools, were used. Obtaining the pressure was achieved by continuous request of the liner in rotational movement up to its elasticity limits, when the dry friction coefficient reaches or exceeds the hardness value of 0.5 HB. By dissipation of the power lost by friction on flat steel sample, are reached contact temperatures at the metal surface that reach and exceed 230 °C, being placed in the range temperature values of the injection. Contact pressures (in load and materials conditions used) ranging from 16.3-36.4 MPa were obtained depending on the plastic material used and the glass fibers content.

Keywords: plastics with glass fibers, dry friction, linear contact, contact temperature, contact pressure, experimental simulation

Procedia PDF Downloads 297