Search results for: zero strength layer

Authors: Christina Peristeri, Tobias Berg, Domenico Caridi, Paul Hutcheson, Robert Winstanley

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In recent years the demand for rapid innovations in the automotive industry has led to the need for accelerated simulation procedures while retaining a detailed representation of the simulated phenomena. The project’s aim is to create a fast transient workflow for external aerodynamic CFD simulations of road vehicles. The geometry used was the SAE Notchback Closed Cooling DrivAer model, and the simulation results were compared with data from wind tunnel tests. The meshes generated for this study were of two types. One was a mix of polyhedral cells near the surface and hexahedral cells away from the surface. The other was an octree hex mesh with a rapid method of fitting to the surface. Three different grid refinement levels were used for each mesh type, with the biggest total cell count for the octree mesh being close to 1 billion. A series of steady-state solutions were obtained on three different grid levels using a pseudo-transient coupled solver and a k-omega-based RANS turbulence model. A mesh-independent solution was found in all cases with a medium level of refinement with 200 million cells. Stress-Blended Eddy Simulation (SBES) was chosen for the transient simulations, which uses a shielding function to explicitly switch between RANS and LES mode. A converged pseudo-transient steady-state solution was used to initialize the transient SBES run that was set up with the SIMPLEC pressure-velocity coupling scheme to reach the fastest solution (on both CPU & GPU solvers). An important part of this project was the use of FLUENT’s Multi-GPU solver. Tesla A100 GPU has been shown to be 8x faster than an Intel 48-core Sky Lake CPU system, leading to significant simulation speed-up compared to the traditional CPU solver. The current study used 4 Tesla A100 GPUs and 192 CPU cores. The combination of rapid octree meshing and GPU computing shows significant promise in reducing time and hardware costs for industrial strength aerodynamic simulations.

Keywords: CFD, DrivAer, LES, Multi-GPU solver, octree mesh, RANS

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Authors: Sevdenur Onger, Ali Asram Sagiroglu

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Hyperpigmentation is a cosmetically unappealing skin problem caused by an overabundance of melanin in the skin. Its pathophysiology is caused by melanocytes being exposed to paracrine melanogenic stimuli, which can upregulate melanogenesis-related enzymes (such as tyrosinase) and cause melanosome formation. Tyrosinase is linked to the development of melanosomes biochemically, and it is the main target of hyperpigmentation treatment. therefore, decreasing tyrosinase activity to reduce melanosomes has become the main target of hyperpigmentation treatment. Niacinamide (NA) is a natural chemical found in a variety of plants that is used as a skin-whitening ingredient in cosmetic formulations. NA decreases melanogenesis in the skin by inhibiting melanosome transfer from melanocytes to covering keratinocytes. Furthermore, NA protects the skin from reactive oxygen species and acts as a main barrier with the skin, reducing moisture loss by increasing ceramide and fatty acid synthesis. However, it is very difficult for hydrophilic compounds such as NA to penetrate deep into the skin. Furthermore, because of the nicotinic acid in NA, it is an irritant. As a result, we've concentrated on strategies to increase NA skin permeability while avoiding its irritating impacts. Since nanotechnology can affect drug penetration behavior by controlling the release and increasing the period of permanence on the skin, it can be a useful technique in the development of whitening formulations. Liposomes have become increasingly popular in the cosmetics industry in recent years due to benefits such as their lack of toxicity, high penetration ability in living skin layers, ability to increase skin moisture by forming a thin layer on the skin surface, and suitability for large-scale production. Therefore, liposomes containing NA were developed for this study. Different formulations were prepared by varying the amount of phospholipid and cholesterol and examined in terms of particle sizes, polydispersity index (PDI) and pH values. The pH values of the produced formulations were determined to be suitable with the pH value of the skin. Particle sizes were determined to be smaller than 250 nm and the particles were found to be of homogeneous size in the formulation (pdi<0.30). Despite the important advantages of liposomal systems, they have low viscosity and stability for topical use. For these reasons, in this study, liposomal cream formulations have been prepared for easy topical application of liposomal systems. As a result, liposomal cream formulations containing NA have been successfully prepared and characterized. Following the in-vitro release and ex-vivo diffusion studies to be conducted in the continuation of the study, it is planned to test the formulation that gives the most appropriate result on the volunteers after obtaining the approval of the ethics committee.

Keywords: delivery systems, hyperpigmentation, liposome, niacinamide

Procedia PDF Downloads 98

Authors: Elena B. Cherepetskaya, Alexander A. Karabutov, Natalia B. Podymova, Ivan Sas

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Nonlinear evolution of broadband ultrasonic pulses passed through the rock specimens is studied using the apparatus ‘GEOSCAN-02M’. Ultrasonic pulses are excited by the pulses of Q-switched Nd:YAG laser with the time duration of 10 ns and with the energy of 260 mJ. This energy can be reduced to 20 mJ by some light filters. The laser beam radius did not exceed 5 mm. As a result of the absorption of the laser pulse in the special material – the optoacoustic generator–the pulses of longitudinal ultrasonic waves are excited with the time duration of 100 ns and with the maximum pressure amplitude of 10 MPa. The immersion technique is used to measure the parameters of these ultrasonic pulses passed through a specimen, the immersion liquid is distilled water. The reference pulse passed through the cell with water has the compression and the rarefaction phases. The amplitude of the rarefaction phase is five times lower than that of the compression phase. The spectral range of the reference pulse reaches 10 MHz. The cubic-shaped specimens of the Karelian gabbro are studied with the rib length 3 cm. The ultimate strength of the specimens by the uniaxial compression is (300±10) MPa. As the reference pulse passes through the area of the specimen without cracks the compression phase decreases and the rarefaction one increases due to diffraction and scattering of ultrasound, so the ratio of these phases becomes 2.3:1. After preloading some horizontal cracks appear in the specimens. Their location is found by one-sided scanning of the specimen using the backward mode detection of the ultrasonic pulses reflected from the structure defects. Using the computer processing of these signals the images are obtained of the cross-sections of the specimens with cracks. By the increase of the reference pulse amplitude from 0.1 MPa to 5 MPa the nonlinear transformation of the ultrasonic pulse passed through the specimen with horizontal cracks results in the decrease by 2.5 times of the amplitude of the rarefaction phase and in the increase of its duration by 2.1 times. By the increase of the reference pulse amplitude from 5 MPa to 10 MPa the time splitting of the phases is observed for the bipolar pulse passed through the specimen. The compression and rarefaction phases propagate with different velocities. These features of the powerful broadband ultrasonic pulses passed through the rock specimens can be described by the hysteresis model of Preisach-Mayergoyz and can be used for the location of cracks in the optically opaque materials.

Keywords: cracks, geological materials, nonlinear evolution of ultrasonic pulses, rock

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Authors: Abhay Asthana, Shally Toshkhani, Gyati Shilakari

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The objective of the present research work is to develop a topical biodegradable dermal patch based formulation to aid accelerated wound healing. It is always better for patient compliance to be able to reduce the frequency of dressings with improved drug delivery and overall therapeutic efficacy. In present study optimized formulation using biodegradable components was obtained evaluating polymers and excipients (HPMC K4M, Ethylcellulose, Povidone, Polyethylene glycol and Gelatin) to impart significant folding endurance, elasticity, and strength. Molten gelatin was used to get a mixture using ethylene glycol. Chitosan dissolved in acidic medium was mixed with stirring to Gelatin mixture. With continued stirring to the mixture Curcumin was added with the aid of DCM and Methanol in an optimized ratio of 60:40 to get homogenous dispersion. Polymers were dispersed with stirring in the final formulation. The mixture was sonicated casted to get the film form. All steps were carried out under strict aseptic conditions. The final formulation was a thin uniformly smooth textured film with dark brown-yellow color. The film was found to have folding endurance was around 20 to 21 times without a crack in an optimized formulation at RT (23°C). The drug content was in range 96 to 102% and it passed the content uniform test. The final moisture content of the optimized formulation film was NMT 9.0%. The films passed stability study conducted at refrigerated conditions (4±0.2°C) and at room temperature (23 ± 2°C) for 30 days. Further, the drug content and texture remained undisturbed with stability study conducted at RT 23±2°C for 45 and 90 days. Percentage cumulative drug release was found to be 80% in 12h and matched the biodegradation rate as tested in vivo with correlation factor R2>0.9. In in vivo study administration of one dose in equivalent quantity per 2 days was applied topically. The data demonstrated a significant improvement with percentage wound contraction in contrast to control and plain drug respectively in given period. The film based formulation developed shows promising results in terms of stability and in vivo performance.

Keywords: wound healing, biodegradable, polymers, patch

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Authors: Aiman Zehra, Sajad Mohd Wani

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Packaging has a vital role as it contains and protects the food that moves from the supply chain to the consumer. Chitosan (CH) has been extensively used in food packaging applications among the plentiful natural macromolecules, including all the polysaccharide class, owing to its easy film-forming capacity, biodegradability, better oxygen and water vapour barrier ability and good mechanical strength. Compared to synthetic films, the films produced from chitosan present poor barrier and mechanical properties. To overcome its deficient qualities, a number of modification procedures are required to enhance the mechanical and physical properties. Various additives such as plasticizers (e.g., glycerol and sorbitol), crosslinkers (e.g.,CaCl₂, ZnO), fillers (nanoclay), and antimicrobial agents (e.g. thyme essential oil) have been used to improve the mechanical, thermal, morphological, antimicrobial properties and emulsifying agents for the stability and elasticity of chitosan-based biodegradable films. Different novel biocomposite films based on chitosan incorporated with thyme essential oil and different additives (ZnO, CaCl₂, NC, and PEG) were successfully prepared and used as packaging material for carrot candy. The chitosan film incorporated with crosslinkers was capable of forming a protective barrier on the surface of the candy to maintain moisture content, water activity, TSS, total sugars, and titratable acidity. ZnO +PEG +NC +CaCl₂ remarkably promotes a synergistic effect on the barrier properties of the film. The combined use of ZnO +PEG +NC +CaCl₂ in CH-TO films was more effective in preventing the moisture gain in candies. The lowest a𝓌 (0.624) was also observed for the candies stored in treatment. The color values L*, a*, b* of the candies were also retained in the film containing all the additives during the 6th month of storage. The value for L*, a*, and b* observed for T was 42.72, 9.89, and 10.84, respectively. The candies packaged in film retained TSS and acidity. The packaging film significantly p≤0.05 conserved sensory qualities and inhibited microbial activity during storage. Carrot candy was found microbiologically safe for human consumption even after six months of storage in all the packaging materials.

Keywords: chitosan, biodegradable films, antimicrobial activity, thyme essential oil, crosslinkers

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Authors: B. Atli-Veltin, A. Vosteen, D. Megan, A. Jedynska, L. K. Cheng

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Composite materials combine the advantages of being lightweight and possessing high strength. This is in particular of interest for the development of large constructions, e.g., aircraft, space applications, wind turbines, etc. One of the shortcomings of using composite materials is the complex nature of the failure mechanisms which makes it difficult to predict the remaining lifetime. Therefore, condition and health monitoring are essential for using composite material for critical parts of a construction. Different types of sensors are used/developed to monitor composite structures. These include ultrasonic, thermography, shearography and fiber optic. The first 3 technologies are complex and mostly used for measurement in laboratory or during maintenance of the construction. Optical fiber sensor can be surface mounted or embedded in the composite construction to provide the unique advantage of in-operation measurement of mechanical strain and other parameters of interest. This is identified to be a promising technology for Structural Health Monitoring (SHM) or Prognostic Health Monitoring (PHM) of composite constructions. Among the different fiber optic sensing technologies, Fiber Bragg Grating (FBG) sensor is the most mature and widely used. FBG sensors can be realized in an array configuration with many FBGs in a single optical fiber. In the current project, different aspects of using embedded FBG for composite wind turbine monitoring are investigated. The activities are divided into two parts. Firstly, FBG embedded carbon composite laminate is subjected to tensile and bending loading to investigate the response of FBG which are placed in different orientations with respect to the fiber. Secondly, the demonstration of using FBG sensor array for temperature and strain sensing and monitoring of a 5 m long scale model of a glass fiber mono-pile is investigated. Two different FBG types are used; special in-house fibers and off-the-shelf ones. The results from the first part of the study are showing that the FBG sensors survive the conditions during the production of the laminate. The test results from the tensile and the bending experiments are indicating that the sensors successfully response to the change of strain. The measurements from the sensors will be correlated with the strain gauges that are placed on the surface of the laminates.

Keywords: Fiber Bragg Gratings, embedded sensors, health monitoring, wind turbine towers

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Authors: Yuen Man Yan

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Peer support has been a rising prevalent mental health service in the globe. The community-based mental health services employ persons with lived experience of mental illness to be peer support workers (PSWs) to provide peer support service to those who are in the progress of recovery (PIRs). It represents the transformation of mental health service system to a recovery-oriented and person-centered care. Literatures proved the feasibility and effectiveness of the peer support service. Researchers have attempted to explore the unique good qualities of peer support service that benefit the PIRs. Empirical researches found that the strength of the relationship between those who sought for change and the change agents positively related to the outcomes in one-to-one therapies across theoretical orientations. However, there is lack of literature on investigating the relationship building between the PSWs and PIRs in the one-to-one community-based peer support service. This study aims to identify and characterise the relationship in the community-based one-to-one peer support service from the perspectives of PSWs and PIRs; and to conceptualize the components of relationship building between PSWs and PIRs in the community-based one-to-one peer support service. The study adopted the constructivist grounded theory approach. 10 pairs of the PSWs and PIRs participated in the study. Data were collected through multiple qualitative methods, including observation of the interaction and exchange of the PSWs and PIRs in the 1ₛₜ, 3ᵣ𝒹 and 9th sessions of the community-based one-to-one peer support service; and semi-structural interview with the PSWs and PIRs separately after the 3ᵣ𝒹and 9ₜₕ session of the peer support service. This presentation is going to report the preliminary findings of the study. PSWs and PIRs identified their relationship as “life alliance”. Empathy was found to be one of key components of the relationship between the PSWs and the PIRs. Unlike the empathy, as explained by Carl Roger, in which the service provider was able to put themselves into the shoes of the service recipients as if he was the service recipients, the intensity of the empathy was much greater in the relationship between PSWs and PIRs because PSWs had the lived experience of mental illness and recovery. The dimensions of the empathy in the relationship between PSWs and PIRs was found to be multiple, not only related to the mental illness but also related to various aspects in life, like family relationship, employment, interest of life, self-esteem and etc.

Keywords: person with lived experience, peer support worker, peer support service, relationship building, therapeutic alliance, community-based mental health setting

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Authors: Qing Liu, Jean-fabien Capsal, Claude Richard

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In this current contribution, authors are dedicated to investigate influence of the crystal lamellae orientation on electromechanical behaviors of relaxor ferroelectric Poly (vinylidene fluoride –trifluoroethylene -chlorotrifluoroethylene) (P(VDF-TrFE-CTFE)) films by control of polymer microstructure, aiming to picture the full map of structure-property relationship. In order to define their crystal orientation films, terpolymer films were fabricated by solution-casting, stretching and hot-pressing process. Differential scanning calorimetry, impedance analyzer, and tensile strength techniques were employed to characterize crystallographic parameters, dielectric permittivity, and elastic Young’s modulus respectively. In addition, large electrical induced out-of-plane electrostrictive strain was obtained by cantilever beam mode. Consequently, as-casted pristine films exhibited surprisingly high electrostrictive strain 0.1774% due to considerably small value of elastic Young’s modulus although relatively low dielectric permittivity. Such reasons contributed to large mechanical elastic energy density. Instead, due to 2 folds increase of elastic Young’s modulus and less than 50% augmentation of dielectric constant, fully-crystallized film showed weak electrostrictive behavior and mechanical energy density as well. And subjected to mechanical stretching process, Film C exhibited stronger dielectric constant and out-performed electrostrictive strain over Film B because edge-on crystal lamellae orientation induced by uniaxially mechanical stretch. Hot-press films were compared in term of cooling rate. Rather large electrostrictive strain of 0.2788% for hot-pressed Film D in quenching process was observed although its dielectric permittivity equivalent to that of pristine as-casted Film A, showing highest mechanical elastic energy density value of 359.5 J/m^3. In hot-press cooling process, dielectric permittivity of Film E saw values at 48.8 concomitant with ca.100% increase of Young’s modulus. Films with intermediate mechanical energy density were obtained.

Keywords: crystal orientation, electrostroctive strain, mechanical energy density, permittivity, relaxor ferroelectric

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Authors: Anuruddha Jayasuriya, Thanakorn Pheeraphan

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In this paper, a review of different mathematical models which can be used as prediction tools to assess the time to crack reinforced concrete (RC) due to corrosion is investigated. This investigation leads to an experimental study to validate a selected prediction model. Most of these mathematical models depend upon the mechanical behaviors, chemical behaviors, electrochemical behaviors or geometric aspects of the RC members during a corrosion process. The experimental program is designed to verify the accuracy of a well-selected mathematical model from a rigorous literature study. Fundamentally, the experimental program exemplifies both one-dimensional chloride diffusion using RC squared slab elements of 500 mm by 500 mm and two-dimensional chloride diffusion using RC squared column elements of 225 mm by 225 mm by 500 mm. Each set consists of three water-to-cement ratios (w/c); 0.4, 0.5, 0.6 and two cover depths; 25 mm and 50 mm. 12 mm bars are used for column elements and 16 mm bars are used for slab elements. All the samples are subjected to accelerated chloride corrosion in a chloride bath of 5% (w/w) sodium chloride (NaCl) solution. Based on a pre-screening of different models, it is clear that the well-selected mathematical model had included mechanical properties, chemical and electrochemical properties, nature of corrosion whether it is accelerated or natural, and the amount of porous area that rust products can accommodate before exerting expansive pressure on the surrounding concrete. The experimental results have shown that the selected model for both one-dimensional and two-dimensional chloride diffusion had ±20% and ±10% respective accuracies compared to the experimental output. The half-cell potential readings are also used to see the corrosion probability, and experimental results have shown that the mass loss is proportional to the negative half-cell potential readings that are obtained. Additionally, a statistical analysis is carried out in order to determine the most influential factor that affects the time to corrode the reinforcement in the concrete due to chloride diffusion. The factors considered for this analysis are w/c, bar diameter, and cover depth. The analysis is accomplished by using Minitab statistical software, and it showed that cover depth is the significant effect on the time to crack the concrete from chloride induced corrosion than other factors considered. Thus, the time predictions can be illustrated through the selected mathematical model as it covers a wide range of factors affecting the corrosion process, and it can be used to predetermine the durability concern of RC structures that are vulnerable to chloride exposure. And eventually, it is further concluded that cover thickness plays a vital role in durability in terms of chloride diffusion.

Keywords: accelerated corrosion, chloride diffusion, corrosion cracks, passivation layer, reinforcement corrosion

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Authors: Christoph Opperer

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Space syntax is a theory and method for analyzing the spatial layout of buildings and urban environments to understand how they can influence patterns of human movement, social interaction, and behavior. While direct visibility is a key factor in space syntax research, important visual information such as light, color, texture, etc., are typically not considered, even though psychological studies have shown a strong correlation to the human perceptual experience within physical space – with light and color, for example, playing a crucial role in shaping the perception of spaciousness. Furthermore, these surface properties are often the visual features that are most salient and responsible for drawing attention to certain elements within the environment. This paper explores the potential of integrating these factors into general space syntax methods and visibility-based analysis of space, particularly for architectural spatial layouts. To this end, we use a combination of geometric (isovist) and topological (visibility graph) approaches together with image-based methods, allowing a comprehensive exploration of the relationship between spatial geometry, visual aesthetics, and human experience. Custom-coded ray-tracing techniques are employed to generate spherical panorama images, encoding three-dimensional spatial data in the form of two-dimensional images. These images are then processed through computer vision algorithms to generate saliency-maps, which serve as a visual representation of areas most likely to attract human attention based on their visual properties. The maps are subsequently used to weight the vertices of isovists and the visibility graph, placing greater emphasis on areas with high saliency. Compared to traditional methods, our weighted visibility analysis introduces an additional layer of information density by assigning different weights or importance levels to various aspects within the field of view. This extends general space syntax measures to provide a more nuanced understanding of visibility patterns that better reflect the dynamics of human attention and perception. Furthermore, by drawing parallels to traditional isovist and VGA analysis, our weighted approach emphasizes a crucial distinction, which has been pointed out by Ervin and Steinitz: the difference between what is possible to see and what is likely to be seen. Therefore, this paper emphasizes the importance of including surface properties in visibility-based analysis to gain deeper insights into how people interact with their surroundings and to establish a stronger connection with human attention and perception.

Keywords: space syntax, visibility analysis, isovist, visibility graph, visual features, human perception, saliency detection, raytracing, spherical images

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Authors: Rossella Marzullo

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Family plays a central role in the Calabrian criminal organization, which draws its strength from blood ties and gender stereotypes that still impose a strong verticalization of intra-family relationships for the benefit of men. However, female figures are of great importance in the organizational structure of the 'Ndrangheta families, despite the fact that they appear to be formally suffocated by the culture of gender subordination still strongly present in the archaic world of criminal organizations. And this is so much true that over time, the women of the 'Ndrangheta have added to the function of ‘internal containment’, the increasingly explicit function of intermediaries in the ‘external’ activities of the clan. But what happens in the 'Ndrangheta if women break the bond and decide to speak? The results are shocking. When a woman starts talking to ask the institutions for help, the system ‘goes crazy’, because the woman is considered the means of consolidating and transmitting family codes: she educates, forges, holds the structure together. If a woman from the 'Ndrangheta decides to speak out and get out of the family bottlenecks of the clan, she does not exclusively destroy the family; she destroys the system. This happens because, while not playing the same roles as men within organizations, women carry out support activities as intermediaries for the circulation of communications, thus ensuring the operability of the gang in practice and on a daily basis. Crossing the border means breaking the bonds of belonging, thus questioning one's own identity and reconstructing it according to other points of reference. How much these disruptive choices are feared by the men of the 'Ndrangheta has been seen in the dramatic stories of Lea Garofalo and Maria Concetta Cacciola: the fear of the breaking of the family pact, of the earthquake that arises from within, has marked their fate of death, useful both to stop the judicial action and to recompose the organization's estate under the aegis of terror. With physical, psychological violence, underhanded torture, and moral blackmail, the men of the mafia family tried to heal the shock caused by the voices of women, relying on violence and yet another attempt to subordinate them. This proves that the 'Ndrangheta is really afraid of them. The female voices of the 'Ndrangheta, who have shaken a consolidated and considered intangible system, represent the anti-'ndrangheta par excellence; in their choices, there is an even stronger desire to break with the mafia world.

Keywords: families, gender, ‘Ndrangheta, stereotypes

Procedia PDF Downloads 102

Authors: Himanshu Kushwah, Nidhi Sandal, Meenakshi K. Chauhan, Gaurav Mittal

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Excessive bleeding is the primary factor of avoidable death in both civilian trauma centers as well as the military battlefield. Hundreds of Indian troops die every year due to blood loss caused by combat-related injuries. These deaths are avoidable and can be prevented to a large extent by making available a suitable hemostatic dressing in an emergency medical kit. In this study, natural gums were evaluated as potential hemostatic agents in combination with calcium gluconate. The study compares the hemostatic activity of Gum Tragacanth (GT), Guar Gum (GG), Xanthan Gum (XG) and Gum Acacia (GA) by carrying out different in-vitro and in-vivo studies. In-vitro studies were performed using the Lee-White method and Eustrek method, which includes the visual and microscopic analysis of blood clotting. MTT assay was also performed using human lymphocytes to check the cytotoxicity of the gums. The in-vivo studies were performed in Sprague Dawley rats using tail bleeding assay to evaluate the hemostatic efficacy of the gums and compared with a commercially available hemostatic sponge, Surgispon. Erythrocyte agglutination test was also performed to check the interaction between blood cells and the natural gums. Other parameters like blood loss, adherence strength of the developed hemostatic dressing material incorporating these gums, re-bleeding, and survival of the animals were also studied. The data obtained from the MTT assay showed that Guar gum, Gum Tragacanth, and Gum Acacia were not significantly cytotoxic, but substantial cytotoxicity was observed in Xanthan gum samples at high concentrations. Also, Xanthan gum took the least time with its minimum concentration to achieve hemostasis, (approximately 50 seconds at 3mg concentration). Gum Tragacanth also showed efficient hemostasis at a concentration of 35mg at the same time, but the other two gums tested were not able to clot the blood in significantly less time. A sponge dressing made of Tragacanth gum was found to be more efficient in achieving hemostasis and showed better practical applicability among all the gums studied and also when compared to the commercially available product, Surgispon, thus making it a potentially better alternative.

Keywords: cytotoxicity, hemostasis, natural gums, sponge

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Authors: Sara A. Pakvis, Giulia Scalet, Stefania Marconi, Ferdinando Auricchio, Matthijs Langelaar

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In recent developments in the field of multi-material additive manufacturing, differences in material properties are exploited to create printed shape-memory structures, which are referred to as 4D-printed structures. New printing techniques allow for the deliberate introduction of prestresses in the specimen during manufacturing, and, in combination with the right design, this enables new functionalities. This research focuses on bi-polymer 4D-printed structures, where the transformation process is based on a heat-induced glass transition in one material lowering its Young’s modulus, combined with an initial prestress in the other material. Upon the decrease in stiffness, the prestress is released, which results in the realization of an essentially pre-programmed deformation. As the design of such functional multi-material structures is crucial but far from trivial, a systematic methodology to find the design of 4D-printed structures is developed, where a finite element model is combined with a density-based topology optimization method to describe the material layout. This modeling approach is verified by a convergence analysis and validated by comparing its numerical results to analytical and published data. Specific aspects that are addressed include the interplay between the definition of the prestress and the material interpolation function used in the density-based topology description, the inclusion of a temperature-dependent stiffness relationship to simulate the glass transition effect, and the importance of the consideration of geometric nonlinearity in the finite element modeling. The efficacy of topology optimization to design 4D-printed structures is explored by applying the methodology to a variety of design problems, both in 2D and 3D settings. Bi-layer designs composed of thermoplastic polymers are printed by means of the fused deposition modeling (FDM) technology. Acrylonitrile butadiene styrene (ABS) polymer undergoes the glass transition transformation, while polyurethane (TPU) polymer is prestressed by means of the 3D-printing process itself. Tests inducing shape transformation in the printed samples through heating are performed to calibrate the prestress and validate the modeling approach by comparing the numerical results to the experimental findings. Using the experimentally obtained prestress values, more complex designs have been generated through topology optimization, and samples have been printed and tested to evaluate their performance. This study demonstrates that by combining topology optimization and 4D-printing concepts, stimuli-responsive structures with specific properties can be designed and realized.

Keywords: 4D-printing, glass transition, shape memory polymer, topology optimization

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Authors: Jennifer Cuellar, Angie L. Parada, Kevin N. S. Chacon, Sol M. Mejia

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The purification of bio-ethanol through distillation methods is an unresolved issue at the biofuel industry because of the ethanol-water azeotrope formation, which increases the steps of the purification process and subsequently increases the production costs. Therefore, understanding the mixture nature at the molecular level could provide new insights for improving the current methods and/or designing new and more efficient purification methods. For that reason, the present study focuses on the evaluation and analysis of (ethanol)₉-water heterodecamers, as the systems with the minimum molecular proportion that represents the azeotropic concentration (96 %m/m in ethanol). The computational modelling was carried out with B3LYP-D3/6-311++G(d,p) in Gaussian 09. Initial explorations of the potential energy surface were done through two methods: annealing simulated runs and molecular dynamics trajectories besides intuitive structures obtained from smaller (ethanol)n-water heteroclusters, n = 7, 8 and 9. The energetic order of the seven stable heterodecamers determines the most stable heterodecamer (Hdec-1) as a structure forming a bicyclic geometry with the O-H---O hydrogen bonds (HBs) where the water is a double proton donor molecule. Hdec-1 combines 1 water molecule and the same quantity of every ethanol conformer; this is, 3 trans, 3 gauche 1 and 3 gauche 2; its abundance is 89%, its decamerization energy is -80.4 kcal/mol, i.e. 13 kcal/mol most stable than the less stable heterodecamer. Besides, a way to understand why methanol does not form an azeotropic mixture with water, analogous systems ((ethanol)10, (methanol)10, and (methanol)9-water)) were optimized. Topologic analysis of the electron density reveals that Hec-1 forms 33 weak interactions in total: 11 O-H---O, 8 C-H---O, 2 C-H---C hydrogen bonds and 12 H---H interactions. The strength and abundance of the most unconventional interactions (H---H, C-H---O and C-H---O) seem to explain the preference of the ethanol for forming heteroclusters instead of clusters. Besides, O-H---O HBs present a significant covalent character according to topologic parameters as the Laplacian of electron density and the relationship between potential and kinetic energy densities evaluated at the bond critical points; obtaining negatives values and values between 1 and 2, for those two topological parameters, respectively.

Keywords: ADMP, DFT, ethanol-water azeotrope, Grimme dispersion correction, simulated annealing, weak interactions

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Authors: G. Krishnamoorthy, S. Anandhakumar

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The effect of D-Lysine (D-Lys) on collagen with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide(EDC)/N-hydroxysuccinimide(NHS) initiated cross linking using experimental and modelling tools are evaluated. The results of the Coll-D-Lys-EDC/NHS scaffold also indicate an increase in the tensile strength (TS), percentage of elongation (% E), denaturation temperature (Td), and decrease the decomposition rate compared to L-Lys-EDC/NHS. Scanning electron microscopic (SEM) and atomic force microscopic (AFM) analyses revealed a well ordered with properly oriented and well-aligned structure of scaffold. The D-Lys stabilizes the scaffold against degradation by collagenase than L-Lys. The cell assay showed more than 98% fibroblast viability (NIH3T3) and improved cell adhesions, protein adsorption after 72h of culture when compared with native scaffold. Cell attachment after 74h was robust, with cytoskeletal analysis showing that the attached cells were aligned along the fibers assuming a spindle-shape appearance, despite, gene expression analyses revealed no apparent alterations in mRNA levels, although cell proliferation was not adversely affected. D-Lysine (D-Lys) plays a pivotal role in the self-assembly and conformation of collagen fibrils. The D-Lys assisted EDC/NHS initiated cross-linking induces the formation of an carboxamide by the activation of the side chain -COOH group, followed by aminolysis of the O-iso acylurea intermediates by the -NH2 groups are directly joined via an isopeptides bond. This leads to the formation of intra- and inter-helical cross links. Modeling studies indicated that D-Lys bind with collagen-like peptide (CLP) through multiple H-bonding and hydrophobic interactions. Orientational changes in collagenase on CLP-D-Lys are observed which may decrease its accessibility to degradation and stabilize CLP against the action of the former. D-Lys has lowest binding energy and improved fibrillar-assembly and staggered alignment without the undesired structural stiffness and aggregations. The proteolytic machinery is not well equipped to deal with Coll-D-Lys than Coll-L-Lys scaffold. The information derived from the present study could help in designing collagenolytically stable heterochiral collagen based scaffold for biomedical applications.

Keywords: collagen, collagenase, collagen like peptide, D-lysine, heterochiral collagen scaffold

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Authors: Sanjay Shukla, A. Nayak, R. K. Sharma, A. P. Singh, S. P. Tiwari

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Excessive use of antibiotics is a major problem in the treatment of wounds and other chronic infections, and antibiotic treatment is frequently non-curative, thus alternative treatment is necessary. Phage therapy is considered one of the most promising approaches to treat multi-drug resistant bacterial pathogens. Infections caused by Staphylococcus aureus are very efficiently controlled with phage cocktails, containing a different individual phages lysate infecting a majority of known pathogenic S. aureus strains. The aim of the present study was to evaluate the efficacy of a purified phage cocktail for prophylactic as well as therapeutic application in mouse model and in large animals with chronic septic infection of wounds. A total of 150 sewage samples were collected from various livestock farms. These samples were subjected for the isolation of bacteriophage by the double agar layer method. A total of 27 sewage samples showed plaque formation by producing lytic activity against S. aureus in the double agar overlay method out of 150 sewage samples. In TEM, recovered isolates of bacteriophages showed hexagonal structure with tail fiber. In the bacteriophage (ØVS) had an icosahedral symmetry with the head size 52.20 nm in diameter and long tail of 109 nm. Head and tail were held together by connector and can be classified as a member of the Myoviridae family under the order of Caudovirale. Recovered bacteriophage had shown the antibacterial activity against the S. aureus in vitro. Cocktail (ØVS1, ØVS5, ØVS9, and ØVS 27) of phage lysate were tested to know in vivo antibacterial activity as well as the safety profile. Result of mice experiment indicated that the bacteriophage lysate were very safe, did not show any appearance of abscess formation, which indicates its safety in living system. The mice were also prophylactically protected against S. aureus when administered with cocktail of bacteriophage lysate just before the administration of S. aureuswhich indicates that they are good prophylactic agent. The S. aureusinoculated mice were completely recovered by bacteriophage administration with 100% recovery, which was very good as compere to conventional therapy. In the present study, ten chronic cases of the wound were treated with phage lysate, and follow up of these cases was done regularly up to ten days (at 0, 5, and 10 d). The result indicated that the six cases out of ten showed complete recovery of wounds within 10 d. The efficacy of bacteriophage therapy was found to be 60% which was very good as compared to the conventional antibiotic therapy in chronic septic wounds infections. Thus, the application of lytic phage in single dose proved to be innovative and effective therapy for the treatment of septic chronic wounds.

Keywords: phage therapy, S aureus, antimicrobial resistance, lytic phage, and bacteriophage

Procedia PDF Downloads 101

Authors: Sana Iqbal

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The female voice in Sufi poetry has been studied as a symbol of humility and devotion. Throughout the centuries, the Sufi shrines have also sheltered women and have served as a source of emotional strength in times of difficulty. Although women have been central to Sufi Islam, female-led rituals and performances (of veneration) are rarely studied as acts of empowerment and symbols of healing. This is especially true for rituals performed in informal spaces, which require going beyond the shrine practices. The rituals and meanings associated with Khizr Khwaja (or Sindhi Hindu god Jhelelal) among women in Punjab can serve as a useful case study to unpack some of these meanings. The paper aims to shed light on female-led rituals among women from Punjab associated with the folkloric traditions associated with Khizar Khwaja, Zinda Pir, Jhulelal or river god in the South Asian region to protect mariners from possible risks (since trade was primarily dependent on water channels) or for inducing timely rain date back to the 10th century in Sindh. However, these meanings and associations have evolved and the paper thus aims to establish a relationship between this figure and the women in Punjab by analysing the findings from an ethnographic study. It traces the historical meanings and significance attached to the divine figure and the wells (informal spaces) associated with him since the rituals performed by women is now infused solely with seeking fertility or to be blessed with a successful pregnancy, as opposed to him being celebrated for other reasons in older times. These associations beg the question of what women gain out of these rituals and making offerings to the mysterious figure of Khizr. Anecdotal evidence in the form of interviews conducted in Bhakar and Talwandi (Punjab) during the summer of 2015 helped to explore the stories related to this legend while also allowing us to witness some of the female-led ritual practices. It can be said that the symbols adopted in the ritual practices invoke liminality for women, which is a blend of opposites. The paper argues that this liminality/journey has been used as a vehicle to transcend all worldly structures of power and it symbolically emphasises the richness of feminine love/devotion and grants healing to female devotees.

Keywords: transgression, gender, liminality, ritual

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Authors: Edgar Santoyo, Daniel Perez-Zarate, Agustin Acevedo, Lorena Diaz-Gonzalez, Mirna Guevara

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Four new gas geothermometers have been derived from a multivariate geo chemometric analysis of a geothermal fluid chemistry database, two of which use the natural logarithm of CO₂ and H2S concentrations (mmol/mol), respectively, and the other two use the natural logarithm of the H₂S/H₂ and CO₂/H₂ ratios. As a strict compilation criterion, the database was created with gas-phase composition of fluids and bottomhole temperatures (BHTM) measured in producing wells. The calibration of the geothermometers was based on the geochemical relationship existing between the gas-phase composition of well discharges and the equilibrium temperatures measured at bottomhole conditions. Multivariate statistical analysis together with the use of artificial neural networks (ANN) was successfully applied for correlating the gas-phase compositions and the BHTM. The predicted or simulated bottomhole temperatures (BHTANN), defined as output neurons or simulation targets, were statistically compared with measured temperatures (BHTM). The coefficients of the new geothermometers were obtained from an optimized self-adjusting training algorithm applied to approximately 2,080 ANN architectures with 15,000 simulation iterations each one. The self-adjusting training algorithm used the well-known Levenberg-Marquardt model, which was used to calculate: (i) the number of neurons of the hidden layer; (ii) the training factor and the training patterns of the ANN; (iii) the linear correlation coefficient, R; (iv) the synaptic weighting coefficients; and (v) the statistical parameter, Root Mean Squared Error (RMSE) to evaluate the prediction performance between the BHTM and the simulated BHTANN. The prediction performance of the new gas geothermometers together with those predictions inferred from sixteen well-known gas geothermometers (previously developed) was statistically evaluated by using an external database for avoiding a bias problem. Statistical evaluation was performed through the analysis of the lowest RMSE values computed among the predictions of all the gas geothermometers. The new gas geothermometers developed in this work have been successfully used for predicting subsurface temperatures in high-temperature geothermal systems of Mexico (e.g., Los Azufres, Mich., Los Humeros, Pue., and Cerro Prieto, B.C.) as well as in a blind geothermal system (known as Acoculco, Puebla). The last results of the gas geothermometers (inferred from gas-phase compositions of soil-gas bubble emissions) compare well with the temperature measured in two wells of the blind geothermal system of Acoculco, Puebla (México). Details of this new development are outlined in the present research work. Acknowledgements: The authors acknowledge the funding received from CeMIE-Geo P09 project (SENER-CONACyT).

Keywords: artificial intelligence, gas geochemistry, geochemometrics, geothermal energy

Procedia PDF Downloads 328

Authors: Sharmistha Chanda, Anindita Choudhuri

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This exploratory study highlights the psychological aspects of women's empowerment to find the importance of the psychological dimension of empowerment, such as; meaning, competence, self-determination, impact, and assumption, especially in the weaker marginalized section of women. A large proportion of rural, suburban, and urban poor survive by working in unorganized sectors of metropolitan cities. Relative Poverty and lack of employment in rural areas and small towns drive many people to the metropolitan city for work and livelihood. Women working in that field remain unrecognized as people of low socio-economic status. They are usually willing to do domestic work as daily wage workers, single wage earners, street vendors, family businesses like agricultural activities, domestic workers, and self-employed. Usually, these women accept such jobs because they do not have such an opportunity as they lack the basic level of education that is required for better-paid jobs. The unorganized sector, on the other hand, has no such clear-cut employer-employee relationships and lacks most forms of social protection. Having no fixed employer, these workers are casual, contractual, migrant, home-based, own-account workers who attempt to earn a living from whatever meager assets and skills they possess. Women have become more empowered both financially and individually through small-scale business ownership or entrepreneurship development and in household-based work. In-depth interviews have been done with 10 participants in order to understand their living styles, habits, self-identity, and empowerment in their society in order to evaluate the key challenges that they may face following by qualitative research approach. Transcription has been done from the collected data. The three-layer coding technique guides the data analysis process, encompassing – open coding, axial coding, and selective coding. Women’s Entrepreneurship is one of the foremost concerns as the Government, and non-government institutions are readily serving this domain with the primary objectives of promoting self-employment opportunities in general and empowering women in specific. Thus, despite hardship and unrecognition unorganized sector provides a huge array of opportunities for rural and sub-urban poor to earn. Also, the upper section of society tends to depend on this working force. This study gave an idea about the well-being, and meaning in life, life satisfaction on the basis of their lived experience.

Keywords: marginalized women, psychological empowerment, relative poverty, unorganized sector

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Authors: Ehsan Alishahi, Chuang Deng

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Materials with microstructural heterogeneity have recently attracted dramatic attention in the materials science community. Although most of the metals are identified as crystalline, the new class of amorphous alloys, sometimes are known as metallic glasses (MGs), exhibited remarkable properties, particularly high mechanical strength and elastic limit. The unique properties of MGs led to the wide range of studies in developing and characterizing of new alloys or composites which met the commercial desires. In spite of applicable properties of MGs, commercializing of metallic glasses was limited due to a major drawback, the lack of ductility and sudden brittle failure mode. Hence, crystalline-amorphous (C-A) composites were introduced almost in 2000s as a toughening strategy to improve the ductility of MGs. Despite the considerable progress reported in previous studies, there are still challenges in both synthesis and characterization of metallic C-A composites. In this study, accumulative roll bonding (ARB) was used to synthesize bulk crystalline-amorphous composites starting from crystalline Cu-Zr multilayers. Due to the severe plastic deformation state, new CuZr phases were formed during the rolling process which was reflected in SEM-EDS analysis. EDS elemental analysis showed the variation in the composition of CuZr phases such as 38-62, 50-50 to 68-32 at Cu-Zr % respectively. Moreover, TEM with electron diffraction analysis indicated the presence of both crystalline and amorphous structures for the new formed CuZr phases. In addition to the microstructural analysis, the mechanical properties of the synthesized composites were studied using the nanoindentation technique. Hysitron Nanoindentation instrument was used to conduct nanoindentation tests with cube corner tip. The maximum load of 5000 µN was applied in load control mode to measure the elastic modulus and hardness of different phases. The trend of results indicated three distinct regimes of hardness and elastic modulus including pure Cu, pure Zr, and new formed CuZr phases. More specifically, pure Cu regions showed the lowest values for both nanoindentation hardness and elastic modulus while the CuZr phases take the highest values. Consequently, pure Zr was placed in the intermediate range which is harder than pure Cu but softer than CuZr phases. In overall, it was found that CuZr phases with higher hardness were nucleated during ARB process as a result of mechanical alloying phenomenon.

Keywords: ARB, crystalline-amorphous composites, mechanical alloying, nanoindentation hardness

Procedia PDF Downloads 534

Authors: Izuddin Fahmy Abu, Mohamad Haiqal Nizar Mohamad, Muhammad Fattah Fazel, Renu Agarwal, Igor Iezhitsa, Nor Salmah Bakar, Henrik Franzyk, Ian Mellor

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Glaucoma is the global leading cause of irreversible blindness. Currently, the available treatment strategy only involves lowering intraocular pressure (IOP); however, the condition often progresses despite lowered or normal IOP in some patients. N-methyl-D-aspartate receptor (NMDAR) excitotoxicity often occurs in neurodegeneration-related glaucoma; thus it is a relevant target to develop a therapy based on neuroprotection approach. This study investigated the effects of Philanthotoxin-343 (PhTX-343), an NMDAR antagonist, on the neuroprotection of NMDA-induced glaucoma to alleviate visual impairments. Male Sprague-Dawley rats were equally divided: Groups 1 (control) and 2 (glaucoma) were intravitreally injected with phosphate buffer saline (PBS) and NMDA (160nM), respectively, while group 3 was pre-treated with PhTX-343 (160nM) 24 hours prior to NMDA injection. Seven days post-treatments, rats were subjected to visual behavior assessments and subsequently euthanized to harvest their retina and optic nerve tissues for histological analysis and determination of nitrosative stress level using 3-nitrotyrosine ELISA. Visual behavior assessments via open field, object, and color recognition tests demonstrated poor visual performance in glaucoma rats indicated by high exploratory behavior. PhTX-343 pre-treatment appeared to preserve visual abilities as all test results were significantly improved (p < 0.05). H&E staining of the retina showed a marked reduction of ganglion cell layer thickness in the glaucoma group; in contrast, PhTX-343 significantly increased the number by 1.28-folds (p < 0.05). PhTX-343 also increased the number of cell nuclei/100μm2 within inner retina by 1.82-folds compared to the glaucoma group (p < 0.05). Toluidine blue staining of optic nerve tissues showed that PhTX-343 reduced the degeneration changes compared to the glaucoma group which exhibited vacuolation overall sections. PhTX-343 also decreased retinal 3- nitrotyrosine concentration by 1.74-folds compared to the glaucoma group (p < 0.05). All results in PhTX-343 group were comparable to control (p > 0.05). We conclude that PhTX-343 protects against NMDA-induced changes and visual impairments in the rat model by reducing nitrosative stress levels.

Keywords: excitotoxicity, glaucoma, nitrosative stress , NMDA receptor , N-methyl-D-aspartate , philanthotoxin, visual behaviour

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Authors: Vaibhav Rathi, Soumen Maity, Achu R. Sekhar, Abhijit Banerjee

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Construction sector in India is extremely resource and carbon intensive. It contributes to significantly to national greenhouse emissions. At the resource end the industry consumes significant portions of the output from mining. Resources such as sand and soil are most exploited and their rampant extraction is becoming constant source of impact on environment and society. Cement is another resource that is used in abundance in building and construction and has a direct impact on limestone resources. Though India is rich in cement grade limestone resource, efforts have to be made for sustainable consumption of this resource to ensure future availability. Use of these resources in high volumes in India is a result of rapid urbanization. More cities have grown to a population of million plus in the last decade and million plus cities are growing further. To cater to needs of growing urban population of construction activities are inevitable in the coming future thereby increasing material consumption. Increased construction will also lead to substantial increase in end of life waste generation from Construction and Demolition (C&D). Therefore proper management of C&D waste has the potential to reduce environmental pollution as well as contribute to the resource efficiency in the construction sector. The present study deals with estimation, characterisation and documenting current management practices of C&D waste in 10 Indian cities of different geographies and classes. Based on primary data the study draws conclusions on the potential of C&D waste to be used as an alternative to primary raw materials. The estimation results show that India generates 716 million tons of C&D waste annually, placing the country as second largest C&D waste generator in the world after China. The study also aimed at utilization of C&D waste in to building materials. The waste samples collected from various cities have been used to replace 100% stone aggregates in paver blocks without any decrease in strength. However, management practices of C&D waste in cities still remains poor instead of notification of rules and regulations notified for C&D waste management. Only a few cities have managed to install processing plant and set up management systems for C&D waste. Therefore there is immense opportunity for management and reuse of C&D waste in Indian cities.

Keywords: building materials, construction and demolition waste, cities, environmental pollution, resource efficiency

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Authors: Jaroslaw Gawryluk, Andrzej Teter

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Simply supported angle columns subjected to uniform shortening are tested. The experimental studies are conducted on a testing machine using additional Aramis and the acoustic emission system. The laminate samples are subjected to axial uniform shortening. The tested columns are loaded with the force values from zero to the maximal load destroying the L-shaped column, which allowed one to observe the column post-buckling behavior until its collapse. Laboratory tests are performed at a constant velocity of the cross-bar equal to 1 mm/min. In order to eliminate stress concentrations between sample and support, flexible pads are used. Analyzed samples are made with carbon-epoxy laminate using the autoclave method. The configurations of laminate layers are: [60,0₂,-60₂,60₃,-60₂,0₃,-60₂,0,60₂]T, where direction 0 is along the length of the profile. Material parameters of laminate are: Young’s modulus along the fiber direction - 170GPa, Young’s modulus along the fiber transverse direction - 7.6GPa, shear modulus in-plane - 3.52GPa, Poisson’s ratio in-plane - 0.36. The dimensions of all columns are: length-300 mm, thickness-0.81mm, width of the flanges-40mm. Next, two numerical models of the column with and without flexible pads are developed using the finite element method in Abaqus software. The L-profile laminate column is modeled using the S8R shell elements. The layup-ply technique is used to define the sequence of the laminate layers. However, the model of grips is made of the R3D4 discrete rigid elements. The flexible pad is consists of the C3D20R type solid elements. In order to estimate the moment of the first laminate layer damage, the following initiation criteria were applied: maximum stress criterion, Tsai-Hill, Tsai-Wu, Azzi-Tsai-Hill, and Hashin criteria. The best compliance of results was observed for the Hashin criterion. It was found that the use of the pad in the numerical model significantly influences the damage mechanism. The model without pads characterized a much more stiffness, as evidenced by a greater bifurcation load and damage initiation load in all analyzed criteria, lower shortening, and less deflection of the column in its center than the model with flexible pads. Acknowledgment: The project/research was financed in the framework of the project Lublin University of Technology-Regional Excellence Initiative, funded by the Polish Ministry of Science and Higher Education (contract no. 030/RID/2018/19).

Keywords: angle column, compression, experiment, FEM

Procedia PDF Downloads 191

Authors: F. Elhaouzi, H. Lahlali, M. Zaghrioui, I. El Aboudi A. BelfKira, A. Mdarhri

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The effect of physico chemical properties of solvents on the transport process and mechanical properties in elastomeric nano composite materials is reported. The investigated samples are formed by a semi-crystalline ethylene-co-butyl acrylate polymer filled with hard spherical carbon black (CB) nano particles. The swelling behavior was studied by immersion the dried samples in selected solvents at room temperature during 2 days. For this purpose, two chemical compounds methyl derivatives of aromatic hydrocarbons of benzene, i.e. toluene and xylene, are used to search for the mass and molar volume dependence on the absorption kinetics. Mass gain relative to the mass of dry material at specific times was recorded to probe the absorption kinetics. The transport of solvent molecules in these filled elastomeric composites is following a Fickian diffusion mechanism. Additionally, the swelling ratio and diffusivity coefficient deduced from the Fickian law are found to decrease with the CB concentration. These results indicate that the CB nano particles increase the effective path length for diffusion and consequently limit the absorption of the solvent by occupation free volumes in the material. According to physico chemical properties of the two used solvents, it is found that the diffusion is more important for the toluene molecules solvent due to their low values of the molecular weight and volume molar compared to those for the xylene. Differential Scanning Calorimetry (DSC) and X-ray photo electron (XPS) were also used to probe the eventual change in the chemical composition for the swollen samples. Mechanically speaking, the stress-strain curves of uniaxial tensile tests pre- and post- swelling highlight a remarkably decrease of the strength and elongation at break of the swollen samples. This behavior can be attributed to the decrease of the load transfer density between the matrix and the CB in the presence of the solvent. We believe that the results reported in this experimental investigation can be useful for some demanding applications e.g. tires, sealing rubber.

Keywords: nanocomposite, absorption kinetics, mechanical behavior, diffusion, modelling, XPS, DSC

Procedia PDF Downloads 337

Authors: S. Trafela, X. Xua, K. Zuzek Rozmana

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In this study, we used an accurate and precise method to measure the electrochemically active surface areas (Aecsa) of nickel electrodes. Calculated Aecsa is really important for the evaluation of an electro-catalyst’s activity in electrochemical reaction of different organic compounds. The method involves the electrochemical formation of Ni(OH)₂ and NiOOH in the presence of adsorbed oxalate in alkaline media. The studies were carried out using cyclic voltammetry with polycrystalline nickel as a reference material and electrodeposited nickel nanowires, homogeneous and heterogeneous nickel films. From cyclic voltammograms, the charge (Q) values for the formation of Ni(OH)₂ and NiOOH surface oxides were calculated under various conditions. At sufficiently fast potential scan rates (200 mV s⁻¹), the adsorbed oxalate limits the growth of the surface hydroxides to a monolayer. Although the Ni(OH)₂/NiOOH oxidation peak overlaps with the oxygen evolution reaction, in the reverse scan, the NiOOH/ Ni(OH)₂ reduction peak is well-separated from other electrochemical processes and can be easily integrated. The values of these integrals were used to correlate experimentally measured charge density with an electrochemically active surface layer. The Aecsa of the nickel nanowires, homogeneous and heterogeneous nickel films were calculated to be Aecsa-NiNWs = 4.2066 ± 0.0472 cm², Aecsa-homNi = 1.7175 ± 0.0503 cm² and Aecsa-hetNi = 2.1862 ± 0.0154 cm². These valuable results were expanded and used in electrochemical studies of formaldehyde oxidation. As mentioned nickel nanowires, heterogeneous and homogeneous nickel films were used as simple and efficient sensor for formaldehyde detection. For this purpose, electrodeposited nickel electrodes were modified in 0.1 mol L⁻¹ solution of KOH in order to expect electrochemical activity towards formaldehyde. The investigation of the electrochemical behavior of formaldehyde oxidation in 0.1 mol L⁻¹ NaOH solution at the surface of modified nickel nanowires, homogeneous and heterogeneous nickel films were carried out by means of electrochemical techniques such as cyclic voltammetric and chronoamperometric methods. From investigations of effect of different formaldehyde concentrations (from 0.001 to 0.1 mol L⁻¹) on electrochemical signal - current we provided catalysis mechanism of formaldehyde oxidation, detection limit and sensitivity of nickel electrodes. The results indicated that nickel electrodes participate directly in the electrocatalytic oxidation of formaldehyde. In the overall reaction, formaldehyde in alkaline aqueous solution exists predominantly in form of CH₂(OH)O⁻, which is oxidized to CH₂(O)O⁻. Taking into account the determined (Aecsa) values we have been able to calculate the sensitivities: 7 mA mol L⁻¹ cm⁻² for nickel nanowires, 3.5 mA mol L⁻¹ cm⁻² for heterogeneous nickel film and 2 mA mol L⁻¹ cm⁻² for heterogeneous nickel film. The detection limit was 0.2 mM for nickel nanowires, 0.5 mM for porous Ni film and 0.8 mM for homogeneous Ni film. All of these results make nickel electrodes capable for further applications.

Keywords: electrochemically active surface areas, nickel electrodes, formaldehyde, electrocatalytic oxidation

Procedia PDF Downloads 143

Authors: Mariam A. Abu-Alim

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The purpose of this study was to validate muscle activation amplitudes of two field base dynamic balance tests that are used as strengthen and motor control exercises too in the activation of selected hip and knee stabilizer muscles. Methods: Eighteen college-age females students (21±2 years; 65.6± 8.7 kg; 169.7±8.1 cm) who participated at least for 30 minutes in physical activity most days of the week volunteered. The wireless BIOPAC (MP150, BIOPAC System. Inc, California, USA) surface electromyography system was used to validate the activation of the Gluteus Medius and the Adductor Magnus of hip stabilizer muscles; and the Hamstrings, Quadriceps, and the Gastrocnemius of the knee stabilizer muscles. Surface electrodes (EL 503, BIOPAC, System. Inc) connected to dual wireless EMG BioNormadix Transmitters were place on selected muscles of participants dominate side. Manual muscle testing was performed to obtain the maximal voluntary isometric contraction (MVIC) in which all collected muscle activity data during the three reaching direction: anterior, posteromedial, posterolateral of the Star Excursion Balance Test (SEBT) and the Y-balance Test (YBT) data could be normalized. All participants performed three trials for each reaching direction of the SEBT and the YBT. The domanial leg trial for each participant was selected for analysis which was also the standing leg. Results: the selected hip stabilizer muscles (Gluteus Medius, Adductor Magnus) were both greater than 100%MVIC during the performance of the SEBT and in all three directions. Whereas, selected knee stabilizer muscles had greater activation 0f 100% MVIC and were significantly more activated during the performance of the YBT test in all three reaching directions. The results showed that the posterolateral and the postmedial reaching directions for both dynamic balance tests had greater activation levels and greater than 200%MVIC for all tested muscles expect of the hamstrings. Conclusion: the results of this study showed that the SEBT and the YBT had validated high levels of muscular activity for the hip and the knee stabilizer muscles; which can be used to represent the improvement, strength, control and the decreasing in the injury levels. Since these selected hip and knee stabilizer muscles, represent 35% of all athletic injuries depending on the type of sport.

Keywords: dynamic balance tests, electromyography, hip stabilizer muscles, nee stabilizer muscles

Procedia PDF Downloads 133

Authors: Eliott Guérin, Remi Daudin, Georges Kalepsi, Alexis Lenain, Sebastien Gravier, Benoit Ter-Ovanessian, Damien Fabregue, Jean-Jacques Blandin

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Due to interesting compromise between mechanical and corrosion properties, Zr-based BMGs are attractive for biomedical applications. However, the enhancement of their glass forming ability (GFA) is often achieved by addition of toxic elements like Ni or Be, which is of course a problem for such applications. Consequently, the development of Ni-free Be-free Zr-based BMGs is of great interest. We have developed a Zr-based (Ni and Be-free) amorphous metallic alloy with an elastic limit twice the one of Ti-6Al-4V. The Zr56Co28Al16 composition exhibits a yield strength close to 2 GPa and low Young’s modulus (close to 90 GPa) [1-2]. In this work, we investigated Niobium (Nb) addition through substitution of Zr up to 8 at%. Cobalt substitution has already been reported [3], but we chose Zr substitution to preserve the glass forming ability. In this case, we show that the glass forming ability for 5 mm diameters rods is maintained up to 3 at% of Nb substitution using suction casting in cooper moulds. Concerning the thermal stability, we measure a strong compositional dependence on the glass transition (Tg). Using DSC analysis (heating rate 20 K/min), we show that the Tg rises from 752 K for 0 at% of Nb to 759 K for 3 at% of Nb. Yet, the thermal range between Tg and the crystallisation temperature (Tx) remains almost unchanged from 33 K to 35 K. Uniaxial compression tests on 2 mm diameter pillars and 3 points bending (3PB) tests on 1 mm thick plates are performed to study the Nb addition on the mechanical properties and the plastic behaviour. With these tests, an optimal Nb concentration is found, improving both plasticity and fatigue resistance. Through interpretations of DSC measurements, an attempt is made to correlate the modifications of the mechanical properties with the structural changes. The optimized chemical, structural and mechanical properties through Nb addition are encouraging to develop the potential of this BMG alloy for biomedical applications. For this purpose, we performed polarisation, immersion and cytotoxicity tests. The figure illustrates the polarisation response of Zr56Co28Al16, Zr54Co28Al16Nb2 and TA6V as a reference after 2h of open circuit potential. The results show that the substitution of Zr by a small amount of Nb significantly improves the corrosion resistance of the alloy.

Keywords: metallic glasses, amorphous metal, medical, mechanical resistance, biocompatibility

Procedia PDF Downloads 134

Authors: Susan Dodd

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This presentation details the methodology for teachers to identify and support a population of students who have historically been overlooked in regards to their educational needs. The twice exceptional (2e) student is a learner who is considered gifted and also has a learning disability, as defined by the Individuals with Disabilities Education Act (IDEA). Many of these students remain underserved throughout their educational careers because their exceptionalities may mask each other, resulting in a special population of students who are not achieving to their fullest potential. There are three common scenarios that may make the identification of a 2e student challenging. First, the student may have been identified as gifted, and her disability may go unnoticed. She could also be considered an under-achiever, or she may be able to compensate for her disability under the school works becomes more challenging. In the second scenario, the student may be identified as having a learning disability and is only receiving remedial services where his giftedness will not be highlighted. His overall IQ scores may be misleading because they were impacted by his learning disability. In the third scenario, the student is able to compensate for her ability well enough to maintain average scores, and she goes undetected as both gifted and learning disabled. Research in the area identifies the complexity involved in identifying 2e students, and how multiple forms of assessment are required. It is important for teachers to be aware of the common characteristics exhibited by many 2e students, so these learners can be identified and appropriately served. Once 2e students have been identified, teachers are then challenged to meet the varying needs of these exceptional learners. Strength-based teaching entails simultaneously providing gifted instruction as well as individualized accommodations for those students. Research in this field has yielded strategies that have proven helpful for teaching 2e students, as well as other students who may be struggling academically. Differentiated instruction, while necessary in all classrooms, is especially important for 2e students, as is encouragement for academic success. Teachers who take the time to really know their students will have a better understanding of each student’s strengths and areas for growth, and therefore tailor instruction to extend the intellectual capacities for optimal achievement. Teachers should also understand that some learning activities can prove very frustrating to students, and these activities can be modified based on individual student needs. Because 2e students can often become discouraged by their learning challenges, it is especially important for teachers to assist students in recognizing their own strengths and maintaining motivation for learning. Although research on the needs of 2e students has spanned across two decades, this population remains underserved in many educational institutions. Teacher awareness of the identification of and the support strategies for 2e students is critical for their success.

Keywords: gifted, learning disability, special needs, twice exceptional

Procedia PDF Downloads 164

Authors: Robert Jedrys, Zdzislaw Kobos, Justyna Skrzynska, Zbigniew Wochynski

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Professions connected to aviation require an assessment of the suitability of health, psychological and psychomotor skills and overall physical fitness of the organism, who applies. Assessment of the physical condition is conducted by the committees consisting of aero-medical specialists in clinical medicine and aviation. In addition, psychological predispositions should be evaluated by specialized psychologists familiar with the specifics of the tasks and requirements for the various positions in aviation. Both, physical abilities and general physical fitness of candidates for aviation shall be assessed during the selection exams, which also test the ability to deal with stress what is very important in aviation. Hence, the mentioned exams in physical education not only help to judge on the ranking in candidates in terms of their efficiency and performance, but also allows to evaluate the functioning under stress measured using psychological tests. Moreover, before-test stress is a predictors of successfulness in the next stages of education and practical training in the aviation. The aim of the study was to evaluate the influence of temperamental traits on strategies used for coping with stress during selection exams in physical education, deciding on admission to aviation school. The study involved 30 candidates for fighter pilot training in aviation school . To evaluate the temperament 'The Formal Characteristics of Behavior-Temperament Inventory' (FCB-TI) by B. Zawadzki and J.Strelau was used. To determine the pattern of coping with stress 'The Coping Inventory for Stressful Situations' (CISS) to N. S. Endler and J. D. A. Parker were engaged. Study of temperament and styles of coping with stress was conducted directly before the exam selection of physical education. The results were analyzed with 'Statistica 9' program. The studies showed that:-There is a negative correlation between such a temperament feature as 'perseverance' and preferred style of coping with stress concentrated on the task (r = -0.590; p < 0.004); -There is a positive correlation between such a feature of temperament as 'emotional reactivity,' and preference to deal with a stressful situation with ‘style centered on emotions’ (r = 0.520; p <0.011); -There is a negative correlation between such a feature of temperament as ‘strength’ and ‘style of coping with stress concentrated on emotions’ (r = -0.580; p < 0.004). Studies indicate that temperament traits determine the perception of stress and preferred coping styles used during the selection, as during the exams in physical education.

Keywords: aviation, physical education, stress, temperamental traits

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Authors: Peter Kutis, Vladimir Littva

Abstract:

Nowadays, it is necessary to ensure that this reduction in costs is not at the expense of the quality of health care and future medical success. In general, physiotherapy for total hip joint arthroplasty is considered to be a routine matter that deals mainly with mobility training, increased muscular strength, and basic day-to-day activities such as bed-to-chair transition, standing, and walking. Within the KEGA project no. 003KU-4-2021, we decided to investigate preoperative physiotherapy care in Slovakia and Austria in total hip arthroplasty patients to shortened overall recovery. Research Sample and Methods: The sample comprised 498 respondents –patients who were indicated to total hip arthroplasty on the territory of Slovakia and Austria. There were 130 women in Slovakia and 135 women in Austria. The numbers of men were 120 in Slovakia and 113 men in Austria. The age of respondents was between 40 and 85 years of age. As a method of our research, we chose a non-standardized questionnaire, which consisted of three parts. The first part for the initial examination of the patient contained the identification of the patient according to the assigned number and subsequently 19 questions conditioned by the physical examination and evaluation of the patients. The second part of our questionnaire was completed after the patient's hospitalization and contained 10 questions that were conditioned by the patient's examination. The last third part for the overall assessment of the patient's state of health consisted of 12 questions conditioned by the patient's examination. This part was performed at the last meeting with the patient at the end of the treatment. All data were statistically processed by SPSS 25. Results: All data were evaluated at a significance level of p = 0.05. From the comparison of patients who underwent preoperative preparation, we can clearly state that the total duration of treatment is significantly shorter. A t-test of two mean values with uneven variance was used to verify the validity of the assumption. The total duration of treatment in patients with preoperative preparation was on average 92,635 days and without preoperative preparation was on average 135,884 days (t-Stat = 44,52784, t Critical one-tail = 1,648187415, t Critical two-tail = 1,965157). Conclusion: The results obtained during the research show the importance of adequate preoperative physiotherapeutic preparation of the patient. The results of total hip joint arthroplasty studies showed a significant reduction in a hospital stay as well as shortened total treatment time.

Keywords: THA, physiotherapy, recovery, preoperative physiotherapy care

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