Search results for: mechanical responses
Commenced in January 2007
Frequency: Monthly
Edition: International
Paper Count: 5811

Search results for: mechanical responses

4701 The Retinoprotective Effects and Mechanisms of Fungal Ingredient 3,4-Dihydroxybenzalacetone through Inhibition of Retinal Müller and Microglial Activation

Authors: Yu-Wen Cheng, Jau-Der Ho, Liang-Huan Wu, Fan-Li Lin, Li-Huei Chen, Hung-Ming Chang, Yueh-Hsiung Kuo, George Hsiao

Abstract:

Retina glial activation and neuroinflammation have been confirmed to cause devastating responses in retinodegenerative diseases. The expression and activation of matrix metalloproteinase (MMP)-9 and inducible nitric oxide synthase (iNOS) could be exerted as the crucial pathological factors in glaucoma- and blue light-induced retinal injuries. The present study aimed to investigate the retinoprotective effects and mechanisms of fungal ingredient 3,4-dihydroxybenzalacetone (DBL) isolated from Phellinus linteus in the retinal glial activation and retinodegenerative animal models. According to the cellular studies, DBL significantly and concentration-dependently abrogated MMP-9 activation and expression in TNFα-stimulated retinal Müller (rMC-1) cells. We found the inhibitory activities of DBL were strongly through the STAT- and ERK-dependent pathways. Furthermore, DBL dramatically attenuated MMP-9 activation in the stimulated Müller cells exposed to conditioned media from LPS-stimulated microglia BV-2 cells. On the other hand, DBL strongly suppressed LPS-induced production of NO and ROS and expression of iNOS in microglia BV-2 cells. Consistently, the phosphorylation of STAT was substantially blocked by DBL in LPS-stimulated microglia BV-2 cells. In the evaluation of retinoprotective functions, the high IOP-induced scotopic electroretinographic (ERG) deficit and blue light-induced abnormal pupillary light response (PLR) were assessed. The deficit scotopic ERG responses markedly recovered by DBL in a rat model of glaucoma-like ischemia/reperfusion (I/R)-injury. DBL also reduced the aqueous gelatinolytic activity and retinal MMP-9 expression in high IOP-injured conditions. Additionally, DBL could restore the abnormal PLR and reduce retinal MMP-9 activation. In summary, DBL could ameliorate retinal neuroinflammation and MMP-9 activation by predominantly inhibiting STAT3 activation in the retinal Müller cells and microglia, which exhibits therapeutic potential for glaucoma and other retinal degenerative diseases.

Keywords: glaucoma, blue light, DBL, retinal Müller cell, MMP-9, STAT, Microglia, iNOS, ERG, PLR

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4700 Changing Colours and Odours: Exploring Cues Used by Insect Pollinators in Two Brassicaceous Plants

Authors: Katherine Y. Barragan-Fonseca, Joop J. A. Van Loon, Marcel Dicke, Dani Lucas-Barbosa

Abstract:

Flowering plants use different traits to attract pollinators, which indicate flower location and reward quality. Visual and olfactory cues are among the most important floral traits exploited by pollinating insects. Pollination can alter physical and chemical cues of flowers, which can subsequently influence the behaviour of flower visitors. We investigated the main cues exploited by the syrphid fly Episyrphus balteatus and the butterfly Pieris brassicae when visiting flowers of Brassica nigra and Raphanus sativus plants. We studied post-pollination changes and their effects on the behaviour of flower visitors and flower volatile emission. Preference of pollinators was investigated by offering visual and olfactory cues simultaneously as well as separately in two-choice bioassays. We also assessed whether pollen is used as a cue by pollinating insects. In addition, we studied whether behavioural responses could be correlated with changes in plant volatile emission, by collecting volatiles from flower headspace. P. brassicae and E. balteatus did not use pollen as a cue in either of the two plant species studied. Interestingly, pollinators showed a strong bias for visual cues over olfactory cues when exposed to B. nigra plants. Flower visits by pollinators were influenced by post-pollination changes in B. nigra. In contrast, plant responses to pollination did not influence pollinator preference for R. sativus flowers. These results correlate well with floral volatile emission of B. nigra and R. sativus; pollination influenced the volatile profile of B. nigra flowers but not that of R. sativus. Collectively, our data show that different pollinators exploit different visual and olfactory traits when searching for nectar or pollen of flowers of two close related plant species. Although the syrphid fly consumes mostly pollen from brassicaceous flowers, it cannot detect pollen from a distance and likely associates other flower traits with quantity and quality of pollen.

Keywords: plant volatiles, pollinators, post-pollination changes, visual and odour cues

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4699 Elaboration and Characterization of PP/TiO2 Composites

Authors: F. Z. Benabid, S. Kridi, F. Zouai, D. Benachour

Abstract:

The aim of present work is to characterize the PP/TiO2 blends as composites, and study the effect of TiO2 on properties of different compositions and the evaluation of the effectiveness of the method used for filler treatment. Nanocomposite samples were synthesized by molten route in an internal mixer. The TiO2 nanoparticles were treated with stearic acid in order to obtain a good dispersion, and the demonstration of the effectiveness of the treatment on the morphology and roughness of the nanofiller was established by microstructural analysis by FTIR and AFM. The various developed nanocomposite compositions were characterized by different methods; i.e. FTIR, XRD, SEM and optical microscopy. Rheological, dielectric and mechanical studies were also performed. The results showed a remarkable increase in the impact strength results which increased about 39% compared to neat PP. The rheological study showed an increase in the fluidity in all developed composite compositions, involved by the good dispersion of TiO2 particles.

Keywords: composites, PP, TiO2, comixing, mechanical treatment

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4698 Mechanical and Biodegradability of Porous Poly-ε-Caprolactone/Polyethylene Glycol Copolymer-Reinforced Cellulose Nanofibers for Soft Tissue Engineering Applications

Authors: Mustafa Abu Ghalia, Mohammed Seddik

Abstract:

The design and development of a new class of biomaterial has gained particular interest in producing polymer scaffold for biomedical applications. Improving mechanical properties, biological and controlling pores scaffold are important factors to provide appropriate biomaterial for implement in soft tissue repair and regeneration. In this study, poly-ε-caprolactone (PCL) /polyethylene glycol (PEG) copolymer (80/20) incorporated with CNF scaffolds were made employing solvent casting and particulate leaching methods. Four mass percentages of CNF (1, 2.5, 5, and 10 wt.%) were integrated into the copolymer through a silane coupling agent. Mechanical properties were determined using Tensile Tester data acquisition to investigate the effect of porosity, pore size, and CNF contents. Tensile strength obtained for PCL/PEG- 5 wt.% CNF was 16 MPa, which drastically decreased after creating a porous structure to 7.1 MPa. The optimum parameters of the results were found to be 5 wt.% for CNF, 240 μm for pore size, and 83% for porosity. Scanning electron microscopy (SEM) micrograph reveals that consistent pore size and regular pore shape were accomplished after the addition of CNF-5 wt. % into PCL/PEG. The results of mass loss of PCL/PEG reinforced-CNF 1% have clearly enhanced to double values compared with PCL/PEG copolymer and three times with PCL/PEG scaffold-CNF 1%. In addition, all PCL/PEG reinforced and scaffold- CNF were partially disintegrated under composting conditions confirming their biodegradable behavior. This also provides a possible solution for the end life of these biomaterials.

Keywords: PCL/PEG, cellulose nanofibers, tissue engineering, biodegradation, compost polymers

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4697 Jute Based Biocomposites: The Future of Automobiles

Authors: D. P. Ray, L. Ammayappan, S. Debnath, R. K. Ghosh, D. Mondal, S. Dasgupta, S. Islam, S. Chakroborty, P. K. Ganguly, D. Nag

Abstract:

Nature being bountiful is generous enough to provide rich resources to mankind. These resources can be used as an alternative to synthetics, thereby reducing the chances of environmental pollution. Natural fibre based composites have emerged as a successful trend in recent automobile industry. Natural fibre based composites used in automobile industries not only reduces their fuel consumption but also do not pose any health hazards. In spite of the use of natural fibre based bio composite in automobile industries, its use is only being limited to interior products. However, its major drawbacks which contributed to limited scope in the field of industry are reduced durability and mechanical strength. Thereby, the use of natural fibre based bio composites as headliner in case of automobile industries is also not successfully deployed. Out of all the natural fibres available, jute can widely be used as automobile parts because of its easy availability, comparatively higher specific strength, lower density, low thermal conductivity and most importantly its non polluting and non abrasive nature. Various research outcomes in the field of jute based biocomposites for the use of automobile industries has not successfully being deployed due to certain inherent problem of the fibre. Jute being hydrophilic in nature is not readily adhered to the hydrophobic polyester resin. Therefore introduction of a chemical compatibilizer, in the preparation of jute based composites have been tested to enhance the mechanical and durable properties of the material to a greater extent. This present work therefore focuses on the synthesis of a suitable compatibilizer, acting as a chemical bridge between the polar jute fabric and the non polar resin matrix. This in turn results in imparting better interfacial bonding between the two, thereby inducing higher mechanical strength. These coupling treated fabrics are casted into composites and tested for their mechanical properties. The test reports show a remarkable change in all of its properties. The durability test was performed by soil burial test method.

Keywords: jute, automobile industry, biodegradability, chemical compatibilizer

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4696 Development of a Paediatric Head Model for the Computational Analysis of Head Impact Interactions

Authors: G. A. Khalid, M. D. Jones, R. Prabhu, A. Mason-Jones, W. Whittington, H. Bakhtiarydavijani, P. S. Theobald

Abstract:

Head injury in childhood is a common cause of death or permanent disability from injury. However, despite its frequency and significance, there is little understanding of how a child’s head responds during injurious loading. Whilst Infant Post Mortem Human Subject (PMHS) experimentation is a logical approach to understand injury biomechanics, it is the authors’ opinion that a lack of subject availability is hindering potential progress. Computer modelling adds great value when considering adult populations; however, its potential remains largely untapped for infant surrogates. The complexities of child growth and development, which result in age dependent changes in anatomy, geometry and physical response characteristics, present new challenges for computational simulation. Further geometric challenges are presented by the intricate infant cranial bones, which are separated by sutures and fontanelles and demonstrate a visible fibre orientation. This study presents an FE model of a newborn infant’s head, developed from high-resolution computer tomography scans, informed by published tissue material properties. To mimic the fibre orientation of immature cranial bone, anisotropic properties were applied to the FE cranial bone model, with elastic moduli representing the bone response both parallel and perpendicular to the fibre orientation. Biofiedility of the computational model was confirmed by global validation against published PMHS data, by replicating experimental impact tests with a series of computational simulations, in terms of head kinematic responses. Numerical results confirm that the FE head model’s mechanical response is in favourable agreement with the PMHS drop test results.

Keywords: finite element analysis, impact simulation, infant head trauma, material properties, post mortem human subjects

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4695 Increased Seedling Vigor Through Phytohomeopathy

Authors: Jasper Jose Zanco

Abstract:

Plants are affected by substances diluted below certain limits. In seeds subjected to ultra-high dilutions (UHD), according to phytohomeopathic methods, it is possible to reduce the concentrations to infinitesimal levels and the effects persist. This research aimed to test different potencies of UHD to modify the vigor of Eruca versicaria (L) Cav. seedlings. The research was carried out at the Plant Production Laboratory of UNISUL University in Santa Catarina, Brazil. Eight UHD treatments were tested, four drops for every 30 mL of distilled water: Control (70% alcohol - A70); Sulphur (S9), Acidum fluoridricum (A30), Calcarea carbonica (C200), Graphies naturalis (G200), Kali carbonicum (K100) Belladonna (B12), diluted and succussed in Hahnemannian centesimal standards. Succussion is a standard pharmaceutical method found in worldwide pharmaceuticals. The statistical design consisted of 50 seeds every 4 replicates per treatment, completely randomized, followed by ANOVA and Tukey's test. Succussion may integrate the high dilution of water treatments, even after successive dilutions, and the product of this process acts through physical-chemical and bioelectric stimuli, causing physiological responses at the cellular level, such as the activation of antioxidant systems, increased resistance to environmental stress or growth modulation. According to some researchers, these responses could be mediated by genetic expression changes or the plants' cellular signaling systems. The results showed significant differences between the control (A70) and the other treatments. Conductivity measurements were made in the seed germination water and impedance; the seedlings were measured for dry weight and total area. The highest conductivity occurred in the control treatment (27.8 μS/cm) and the lowest in K100 (21.3 μS/cm). After germination, on germitest paper, A70 was significantly different from G200 (<1%) and S9 (5%). Both homeopathies differed from the other treatments, with S9 obtaining the best germination (87.1%) and vigor index (IV=7.98) in relation to the other treatments. The control, A70, presented the lowest germination (63.9%) and vigor (IV=4.93).

Keywords: ultra high dilution, impedance, condutivity, eruca versicaria

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4694 An Electromechanical Device to Use in Road Pavements to Convert Vehicles Mechanical Energy into Electrical Energy

Authors: Francisco Duarte, Adelino Ferreira, Paulo Fael

Abstract:

With the growing need for alternative energy sources, research into energy harvesting technologies has increased considerably in recent years. The particular case of energy harvesting on road pavements is a very recent area of research, with different technologies having been developed in recent years. However, none of them have presented high conversion efficiencies nor technical or economic viability. This paper deals with the development of a mechanical system to implement on a road pavement energy harvesting electromechanical device, to transmit energy from the device surface to an electrical generator. The main goal is to quantify the energy harvesting, transmission and conversion efficiency of the proposed system and compare it with existing systems. Conclusions about the system’s efficiency are presented.

Keywords: road pavement, energy harvesting, energy conversion, system modelling

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4693 Effect of Social Stress on Behavioural and Physiological Responses and its Assessment by non-Invasive Method in Zebu Cattle

Authors: Baishali Deb, Hari Om Pandey, Shrilla Elangbam, Mukesh Singh, Ayon Tarafdar, A. K. S. Tomar, A. K. Pandey, Triveni Dutt

Abstract:

The goal of the present investigation was to determine the impact of social stress on behavioural characteristics, physiological responses, and haemato-biochemical indicators under various social environments in Tharparkar cattle. Serum cortisol and faecal cortisol metabolites analysis were used to determine the stress level of Tharparkar cattle. Social isolation and social mixing were the two different social circumstances used to evaluate the animals. In both the experiments i.e., social isolation and social mixing, the lying period of animals decreased significantly (p<0.05) while standing period significantly (p<0.05) increased. Frequency and duration of activities like idling, walking, exploration, oral manipulation, and elimination increased significantly (p<0.05) in Tharparkar cattle after being subjected to social isolation and social mixing. Time spent in grooming (self-grooming and allo-grooming) in respect to social isolation significantly increased during isolation and post-reunion, whereas there was a significant (p<0.05) decline in the grooming behaviour especially allo-grooming during mixing of the animals. Feeding and rumination time also decreased significantly (p<0.05) in animals during both the experiments. Physiological parameters such as respiration rate, heart rate and pulse rate increased during the treatment periods. There was no significant difference in the haematological parameters for both the experiments. There was significant (p<0.05) increase in serum cortisol and faecal cortisol metabolites (FCM) concentration in animals subjected to social stress. Therefore, it can be concluded that social stress strongly impacts the behaviour and physiological parameters of the animals, causing stress and nervousness, proving that social stress is a valid psychological stress in animals. The higher concentration of FCM in Tharparkar cattle subjected to social stress, further supported by higher serum cortisol and behaviour manifestations, suggest that FCM could be used to assess stress response as a non-invasive method.

Keywords: social stress, fecal cortisol metabolites, non-invasive, animal welfare, behaviour

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4692 Spectral Responses of the Laser Generated Coal Aerosol

Authors: Tibor Ajtai, Noémi Utry, Máté Pintér, Tomi Smausz, Zoltán Kónya, Béla Hopp, Gábor Szabó, Zoltán Bozóki

Abstract:

Characterization of spectral responses of light absorbing carbonaceous particulate matter (LAC) is of great importance in both modelling its climate effect and interpreting remote sensing measurement data. The residential or domestic combustion of coal is one of the dominant LAC constituent. According to some related assessments the residential coal burning account for roughly half of anthropogenic BC emitted from fossil fuel burning. Despite of its significance in climate the comprehensive investigation of optical properties of residential coal aerosol is really limited in the literature. There are many reason of that starting from the difficulties associated with the controlled burning conditions of the fuel, through the lack of detailed supplementary proximate and ultimate chemical analysis enforced, the interpretation of the measured optical data, ending with many analytical and methodological difficulties regarding the in-situ measurement of coal aerosol spectral responses. Since the gas matrix of ambient can significantly mask the physicochemical characteristics of the generated coal aerosol the accurate and controlled generation of residential coal particulates is one of the most actual issues in this research area. Most of the laboratory imitation of residential coal combustion is simply based on coal burning in stove with ambient air support allowing one to measure only the apparent spectral feature of the particulates. However, the recently introduced methodology based on a laser ablation of solid coal target opens up novel possibilities to model the real combustion procedure under well controlled laboratory conditions and makes the investigation of the inherent optical properties also possible. Most of the methodology for spectral characterization of LAC is based on transmission measurement made of filter accumulated aerosol or deduced indirectly from parallel measurements of scattering and extinction coefficient using free floating sampling. In the former one the accuracy while in the latter one the sensitivity are liming the applicability of this approaches. Although the scientific community are at the common platform that aerosol-phase PhotoAcoustic Spectroscopy (PAS) is the only method for precise and accurate determination of light absorption by LAC, the PAS based instrumentation for spectral characterization of absorption has only been recently introduced. In this study, the investigation of the inherent, spectral features of laser generated and chemically characterized residential coal aerosols are demonstrated. The experimental set-up and its characteristic for residential coal aerosol generation are introduced here. The optical absorption and the scattering coefficients as well as their wavelength dependency are determined by our state-of-the-art multi wavelength PAS instrument (4λ-PAS) and multi wavelength cosinus sensor (Aurora 3000). The quantified wavelength dependency (AAE and SAE) are deduced from the measured data. Finally, some correlation between the proximate and ultimate chemical as well as the measured or deduced optical parameters are also revealed.

Keywords: absorption, scattering, residential coal, aerosol generation by laser ablation

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4691 Phi Thickening Induction as a Response to Abiotic Stress in the Orchid Miltoniopsis

Authors: Nurul Aliaa Idris, David A. Collings

Abstract:

Phi thickenings are specialized secondary cell wall thickenings that are found in the cortex of the roots in a wide range of plant species, including orchids. The role of phi thickenings in the root is still under debate through research have linked environmental conditions, particularly abiotic stresses such as water stress, heavy metal stress and salinity to their induction in the roots. It has also been suggested that phi thickenings may act as a barrier to regulate solute uptake, act as a physical barrier against fungal hyphal penetration due to its resemblance to the Casparian strip and play a mechanical role to support cortical cells. We have investigated phi thickening function in epiphytic orchids of the genus Miltoniopsis through induction experiment against factors such as soil compaction and water stress. The permeability of the phi thickenings in Miltoniopsis was tested through uptake experiments using the fluorescent tracer dyes Calcofluor white, Lucifer yellow and Propidium iodide then viewed with wide-field or confocal microscopy. To test whether phi thickening may prevent fungal colonization in the root cell, fungal re-infection experiment was conducted by inoculating isolated symbiotic fungus to sterile in vitro Miltoniopsis explants. As the movement of fluorescent tracers through the apoplast was not blocked by phi thickenings, and as phi thickenings developed in the roots of sterile cultures in the absence of fungus and did not prevent fungal colonization of cortical cells, the phi thickenings in Miltoniopsis do not function as a barrier. Phi thickenings were found to be absent in roots grown on agar and remained absent when plants were transplanted to moist soil. However, phi thickenings were induced when plants were transplanted to well-drained media, and by the application of water stress in all soils tested. It is likely that phi thickenings stabilize the root cortex during dehydration. Nevertheless, the varied induction responses present in different plant species suggest that the phi thickenings may play several adaptive roles, instead of just one, depending on species.

Keywords: abiotic stress, Miltoniopsis, orchid, phi thickening

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4690 Effect of Hot Extrusion on the Mechanical and Corrosion Properties of Mg-Zn-Ca and Mg-Zn-Ca-Mn Alloys for Medical Application

Authors: V. E. Bazhenov, A. V. Li, A. A. Komissarov, A. V. Koltygin, S. A. Tavolzhanskii, O. O. Voropaeva, A. M. Mukhametshina, A. A. Tokar, V. A. Bautin

Abstract:

Magnesium-based alloys are considered as effective materials in the development of biodegradable implants. The magnesium alloys containing Mg, Zn, Ca as an alloying element are the subject of the particular interest. These elements are the nutrients for the human body, which provide their high biocompatibility. In this work, we investigated the effect of severe plastic deformation (SPD) on the mechanical and corrosion properties of Mg-Zn-Ca and Mg-Zn-Ca-Mn alloys containing from 2 to 4 wt.% Zn; 0.7 wt.% Ca and up to 1 wt.% Mn. Hot extrusion was used as a method of intensive plastic deformation. The temperature of hot extrusion was set to 220 °C and 300 °C. Metallographic analysis after hot extrusion shows that the grain size in the studied alloys depends on the deformation temperature. The grain size for all of investigated alloys is in the range from 3 to 7 microns, and 3 μm corresponds to the extrusion temperature of 220 °C. Analysis of mechanical properties after extrusion shows that extrusion at a temperature of 220 °C and alloying with Mn increase the strength characteristics and decrease the ductility of studied alloys. A slight anisotropy of properties in the longitudinal and transverse directions was also observed. Measurements of corrosion properties revealed that the addition of Mn to Mg-Zn-Ca alloys reduces the corrosion rate. On the other hand, increasing the Zn content in alloys increases the corrosion rate. The extrusion temperature practically does not affect the corrosion rate. Acknowledgement: The authors gratefully acknowledge the financial support of the Ministry of Science and Higher Education of the Russian Federation in the framework of Increase Competitiveness Program of NUST «MISiS» (No K2-2019-008), implemented by a governmental decree dated 16th of March 2013, N 211.

Keywords: biocompatibility, hot extrusion, magnesium alloys, severe plastic deformation, properties

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4689 The Mechanical Properties of a Small-Size Seismic Isolation Rubber Bearing for Bridges

Authors: Yi F. Wu, Ai Q. Li, Hao Wang

Abstract:

Taking a novel type of bridge bearings with the diameter being 100mm as an example, the theoretical analysis, the experimental research as well as the numerical simulation of the bearing were conducted. Since the normal compression-shear machines cannot be applied to the small-size bearing, an improved device to test the properties of the bearing was proposed and fabricated. Besides, the simulation of the bearing was conducted on the basis of the explicit finite element software ANSYS/LS-DYNA, and some parameters of the bearing are modified in the finite element model to effectively reduce the computation cost. Results show that all the research methods are capable of revealing the fundamental properties of the small-size bearings, and a combined use of these methods can better catch both the integral properties and the inner detailed mechanical behaviors of the bearing.

Keywords: ANSYS/LS-DYNA, compression shear, contact analysis, explicit algorithm, small-size

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4688 A Fabrication Method for PEDOT: PSS Based Humidity Sensor

Authors: Nazia Tarannum, M. Ayaz Ahmad

Abstract:

The main goal of this article is to report some interesting features for the fabrication/design of PEDOT:PSS based humidity sensor. Here first we fabricated humidity sensor and then studied its electro-mechanical characteristics. In general the humidity plays an important role in various private and government sectors all over the world. Monitoring and controlling the humidity is a great task for the reliable operation of various systems. The PEDOT:PSS is very much promising humidity sensor and also is fabricated by performing various analyses. The interdigited electrode (IDE) has channel length 200 microns prepared by lithography. Lithography of IDE was done on PPR coated glass substrate using negative mask and exposing it with UV light for 10 secs via DSA. During the above said fabrication, we have taken account for the following steps: •Plasma ashing of IDE •Spincoating of PEDOT:PSS was done @3000 rpm on IDE substrace •Baked the substrace at 130 °C up to time limit 15 mins. •Resistance measurement using Labtracer 2.9 software via Keithley 2400source meter.

Keywords: fabrication method, PEDOT:PSS material, humidity sensor, electro-mechanical

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4687 Hydration Matters: Impact on 3 km Running Performance in Trained Male Athletes Under Heat Conditions

Authors: Zhaoqi He

Abstract:

Research Context: Endurance performance in hot environments is influenced by the interplay of hydration status and physiological responses. This study aims to investigate how dehydration, up to 2.11% body weight loss, affects the 3 km running performance of trained male athletes under conditions mimicking high temperatures. Methodology: In a randomized crossover design, five male athletes participated in two trials – euhydrated (EU) and dehydrated (HYPO). Both trials included a 70-minute preload run at 55-60% VO2max in 32°C and 50% humidity, followed by a 3-kilometer time trial. Fluid intake was restricted in HYPO to induce a 2.11% body weight loss. Physiological metrics, including heart rate, core temperature, and oxygen uptake, were measured, along with perceptual metrics like perceived exertion and thirst sensation. Findings: The 3-kilometer run completion times showed no significant differences between EU and HYPO trials (p=0.944). Physiological indicators, including heart rate, core temperature, and oxygen uptake, did not significantly vary (p>0.05). Thirst sensation was markedly higher in HYPO (p=0.013), confirming successful induction of dehydration. Other perceptual metrics and gastrointestinal comfort remained consistent. Conclusion: Contrary to the hypothesis, the study reveals that dehydration, inducing up to 2.11% body weight loss, does not significantly impair 3 km running performance in trained male athletes under hot conditions. Thirst sensation was notably higher in the dehydrated state, emphasizing the importance of considering perceptual factors in hydration strategies. The findings suggest that trained runners can maintain performance despite moderate dehydration, highlighting the need for nuanced hydration guidelines in hot-weather running.

Keywords: hypohydration, euhydration, hot environment, 3km running time trial, endurance performance, trained athletes, perceptual metrics, dehydration impact, physiological responses, hydration strategies

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4686 Clinicians’ Experiences with IT Systems in a UK District General Hospital: A Qualitative Analysis

Authors: Sunny Deo, Eve Barnes, Peter Arnold-Smith

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Introduction: Healthcare technology is a rapidly expanding field in healthcare, with enthusiasts suggesting a revolution in the quality and efficiency of healthcare delivery based on the utilisation of better e-healthcare, including the move to paperless healthcare. The role and use of computers and programmes for healthcare have been increasing over the past 50 years. Despite this, there is no standardised method of assessing the quality of hardware and software utilised by frontline healthcare workers. Methods and subjects: Based on standard Patient Related Outcome Measures, a questionnaire was devised with the aim of providing quantitative and qualitative data on clinicians’ perspectives of their hospital’s Information Technology (IT). The survey was distributed via the Institution’s Intranet to all contracted doctors, and the survey's qualitative results were analysed. Qualitative opinions were grouped as positive, neutral, or negative and further sub-grouped into speed/usability, software/hardware, integration, IT staffing, clinical risk, and wellbeing. Analysis was undertaken on the basis of doctor seniority and by specialty. Results: There were 196 responses, with 51% from senior doctors (consultant grades) and the rest from junior grades, with the largest group of respondents 52% coming from medicine specialties. Differences in the proportion of principle and sub-groups were noted by seniority and specialty. Negative themes were by far the commonest stated opinion type, occurring in almost 2/3’s of responses (63%), while positive comments occurred less than 1 in 10 (8%). Conclusions: This survey confirms strongly negative attitudes to the current state of electronic documentation and IT in a large single-centre cohort of hospital-based frontline physicians after two decades of so-called progress to a paperless healthcare system. Greater use would provide further insights and potentially optimise the focus of development and delivery to improve the quality and effectiveness of IT for clinicians and their patients.

Keywords: information technology, electronic patient records, digitisation, paperless healthcare

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4685 Investigation of Interlayer Shear Effects in Asphalt Overlay on Existing Rigid Airfield Pavement Using Digital Image Correlation

Authors: Yuechao Lei, Lei Zhang

Abstract:

The interface shear between asphalt overlay and existing rigid airport pavements occurs due to differences in the mechanical properties of materials subjected to aircraft loading. Interlayer contact influences the mechanical characteristics of the asphalt overlay directly. However, the effective interlayer relative displacement obtained accurately using existing displacement sensors of the loading apparatus remains challenging. This study aims to utilize digital image correlation technology to enhance the accuracy of interfacial contact parameters by obtaining effective interlayer relative displacements. Composite structure specimens were prepared, and fixtures for interlayer shear tests were designed and fabricated. Subsequently, a digital image recognition scheme for required markers was designed and optimized. Effective interlayer relative displacement values were obtained through image recognition and calculation of surface markers on specimens. Finite element simulations validated the mechanical response of composite specimens with interlayer shearing. Results indicated that an optimized marking approach using the wall mending agent for surface application and color coding enhanced the image recognition quality of marking points on the specimen surface. Further image extraction provided effective interlayer relative displacement values during interlayer shear, thereby improving the accuracy of interface contact parameters. For composite structure specimens utilizing Styrene-Butadiene-Styrene (SBS) modified asphalt as the tack coat, the corresponding maximum interlayer shear stress strength was 0.6 MPa, and fracture energy was 2917 J/m2. This research provides valuable insights for investigating the impact of interlayer contact in composite pavement structures on the mechanical characteristics of asphalt overlay.

Keywords: interlayer contact, effective relative displacement, digital image correlation technology, composite pavement structure, asphalt overlay

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4684 Tobacco Taxation and the Heterogeneity of Smokers' Responses to Price Increases

Authors: Simone Tedeschi, Francesco Crespi, Paolo Liberati, Massimo Paradiso, Antonio Sciala

Abstract:

This paper aims at contributing to the understanding of smokers’ responses to cigarette prices increases with a focus on heterogeneity, both across individuals and price levels. To do this, a stated preference quasi-experimental design grounded in a random utility framework is proposed to evaluate the effect on smokers’ utility of the price level and variation, along with social conditioning and health impact perception. The analysis is based on individual-level data drawn from a unique survey gathering very detailed information on Italian smokers’ habits. In particular, qualitative information on the individual reactions triggered by changes in prices of different magnitude and composition are exploited. The main findings stemming from the analysis are the following; the average price elasticity of cigarette consumption is comparable with previous estimates for advanced economies (-.32). However, the decomposition of this result across five latent-classes of smokers, reveals extreme heterogeneity in terms of price responsiveness, implying a potential price elasticity that ranges between 0.05 to almost 1. Such heterogeneity is in part explained by observable characteristics such as age, income, gender, education as well as (current and lagged) smoking intensity. Moreover, price responsiveness is far from being independent from the size of the prospected price increase. Finally, by comparing even and uneven price variations, it is shown that uniform across-brand price increases are able to limit the scope of product substitutions and downgrade. Estimated price-response heterogeneity has significant implications for tax policy. Among them, first, it provides evidence and a rationale for why the aggregate price elasticity is likely to follow a strictly increasing pattern as a function of the experienced price variation. This information is crucial for forecasting the effect of a given tax-driven price change on tax revenue. Second, it provides some guidance on how to design excise tax reforms to balance public health and revenue goals.

Keywords: smoking behaviour, preference heterogeneity, price responsiveness, cigarette taxation, random utility models

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4683 Calculation of Stress Intensity Factors in Rotating Disks Containing 3D Semi-Elliptical Cracks

Authors: Mahdi Fakoor, Seyed Mohammad Navid Ghoreishi

Abstract:

Initiation and propagation of cracks may cause catastrophic failures in rotating disks, and hence determination of fracture parameter in rotating disks under the different working condition is very important issue. In this paper, a comprehensive study of stress intensity factors in rotating disks containing 3D semi-elliptical cracks under the different working condition is investigated. In this regard, after verification of modeling and analytical procedure, the effects of mechanical properties, rotational velocity, and orientation of cracks on Stress Intensity Factors (SIF) in rotating disks under centrifugal loading are investigated. Also, the effects of using composite patch in reduction of SIF in rotating disks are studied. By that way, the effects of patching design variables like mechanical properties, thickness, and ply angle are investigated individually.

Keywords: stress intensity factor, semi-elliptical crack, rotating disk, finite element analysis (FEA)

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4682 Fatigue Behavior of Dissimilar Welded Monel400 and SS316 by Frictions Stir Welding

Authors: Aboozar Aghaei

Abstract:

In the present work, the dissimilar Monel400 and SS316 were joined by friction stir welding (FSW). The applied rotating speed was 400 rpm, whereas the traverse speed varied between 50 and 150 mm/min. At a constant rotating speed, the sound welds were obtained at the welding speeds of 50 and 100 mm/min. However, a groove-like defect was formed when the welding speed exceeded 100 mm/min. The mechanical properties of the joints were evaluated using tensile and fatigue tests. The fatigue strength of dissimilar FSWed specimens was higher than that of both Monel400 and SS316. To study the failure behavior of FSWed specimens, the fracture surfaces were analyzed using a scanning electron microscope (SEM). The failure analysis indicates that different mechanisms may contribute to the fracture of welds. This was attributed to the dissimilar characteristics of dissimilar materials exhibiting different failure behaviors.

Keywords: frictions stir welding (FSW), stainless steel, mechanical properties, Monel400

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4681 The Efficacy of Government Strategies to Control COVID 19: Evidence from 22 High Covid Fatality Rated Countries

Authors: Imalka Wasana Rathnayaka, Rasheda Khanam, Mohammad Mafizur Rahman

Abstract:

TheCOVID-19 pandemic has created unprecedented challenges to both the health and economic states in countries around the world. This study aims to evaluate the effectiveness of governments' decisions to mitigate the risks of COVID-19 through proposing policy directions to reduce its magnitude. The study is motivated by the ongoing coronavirus outbreaks and comprehensive policy responses taken by countries to mitigate the spread of COVID-19 and reduce death rates. This study contributes to filling the knowledge by exploiting the long-term efficacy of extensive plans of governments. This study employs a Panel autoregressive distributed lag (ARDL) framework. The panels incorporate both a significant number of variables and fortnightly observations from22 countries. The dependent variables adopted in this study are the fortnightly death rates and the rates of the spread of COVID-19. Mortality rate and the rate of infection data were computed based on the number of deaths and the number of new cases per 10000 people.The explanatory variables are fortnightly values of indexes taken to investigate the efficacy of government interventions to control COVID-19. Overall government response index, Stringency index, Containment and health index, and Economic support index were selected as explanatory variables. The study relies on the Oxford COVID-19 Government Measure Tracker (OxCGRT). According to the procedures of ARDL, the study employs (i) the unit root test to check stationarity, (ii) panel cointegration, and (iii) PMG and ARDL estimation techniques. The study shows that the COVID-19 pandemic forced immediate responses from policymakers across the world to mitigate the risks of COVID-19. Of the four types of government policy interventions: (i) Stringency and (ii) Economic Support have been most effective and reveal that facilitating Stringency and financial measures has resulted in a reduction in infection and fatality rates, while (iii) Government responses are positively associated with deaths but negatively with infected cases. Even though this positive relationship is unexpected to some extent in the long run, social distancing norms of the governments have been broken by the public in some countries, and population age demographics would be a possible reason for that result. (iv) Containment and healthcare improvements reduce death rates but increase the infection rates, although the effect has been lower (in absolute value). The model implies that implementation of containment health practices without association with tracing and individual-level quarantine does not work well. The policy implication based on containment health measures must be applied together with targeted, aggressive, and rapid containment to extensively reduce the number of people infected with COVID 19. Furthermore, the results demonstrate that economic support for income and debt relief has been the key to suppressing the rate of COVID-19 infections and fatality rates.

Keywords: COVID-19, infection rate, deaths rate, government response, panel data

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4680 Finite Element Modeling of Global Ti-6Al-4V Mechanical Behavior in Relationship with Microstructural Parameters

Authors: Fatna Benmessaoud, Mohammed Cheikh, Vencent Velay, Vanessa Vedal, Farhad Rezai-Aria, Christine Boher

Abstract:

The global mechanical behavior of materials is strongly linked to their microstructure, especially their crystallographic texture and their grains morphology. These material aspects determine the mechanical fields character (heterogeneous or homogeneous), thus, they give to the global behavior a degree of anisotropy according the initial microstructure. For these reasons, the prediction of global behavior of materials in relationship with the microstructure must be performed with a multi-scale approach. Therefore, multi-scale modeling in the context of crystal plasticity is widely used. In this present contribution, a phenomenological elasto-viscoplastic model developed in the crystal plasticity context and finite element method are used to investigate the effects of crystallographic texture and grains sizes on global behavior of a polycrystalline equiaxed Ti-6Al-4V alloy. The constitutive equations of this model are written on local scale for each slip system within each grain while the strain and stress mechanical fields are investigated at the global scale via finite element scale transition. The beta phase of Ti-6Al-4V alloy modeled is negligible; its percent is less than 10%. Three families of slip systems of alpha phase are considered: basal and prismatic families with a burgers vector and pyramidal family with a burgers vector. The twinning mechanism of plastic strain is not observed in Ti-6Al-4V, therefore, it is not considered in the present modeling. Nine representative elementary volumes (REV) are generated with Voronoi tessellations. For each individual equiaxed grain, the own crystallographic orientation vis-à-vis the loading is taken into account. The meshing strategy is optimized in a way to eliminate the meshing effects and at the same time to allow calculating the individual grain size. The stress and strain fields are determined in each Gauss point of the mesh element. A post-treatment is used to calculate the local behavior (in each grain) and then by appropriate homogenization, the macroscopic behavior is calculated. The developed model is validated by comparing the numerical simulation results with an experimental data reported in the literature. It is observed that the present model is able to predict the global mechanical behavior of Ti-6Al-4V alloy and investigate the microstructural parameters' effects. According to the simulations performed on the generated volumes (REV), the macroscopic mechanical behavior of Ti-6Al-4V is strongly linked to the active slip systems family (prismatic, basal or pyramidal). The crystallographic texture determines which family of slip systems can be activated; therefore it gives to the plastic strain a heterogeneous character thus an anisotropic macroscopic mechanical behavior. The average grains size influences also the Ti-6Al-4V mechanical proprieties, especially the yield stress; by decreasing of the average grains size, the yield strength increases according to Hall-Petch relationship. The grains sizes' distribution gives to the strain fields considerable heterogeneity. By increasing grain sizes, the scattering in the localization of plastic strain is observed, thus, in certain areas the stress concentrations are stronger than other regions.

Keywords: microstructural parameters, multi-scale modeling, crystal plasticity, Ti-6Al-4V alloy

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4679 A Robust Theoretical Elastoplastic Continuum Damage T-H-M Model for Rock Surrounding a Wellbore

Authors: Nikolaos Reppas, Yilin Gui, Ben Wetenhall, Colin Davie

Abstract:

Injection of CO2 inside wellbore can induce different kind of loadings that can lead to thermal, hydraulic, and mechanical changes on the surrounding rock. A dual-porosity theoretical constitutive model will be presented for the stability analysis of the wellbore during CO2 injection. An elastoplastic damage response will be considered. A bounding yield surface will be presented considering damage effects on sandstone. The main target of the research paper is to present a theoretical constitutive model that can help industries to safely store CO2 in geological rock formations and forecast any changes on the surrounding rock of the wellbore. The fully coupled elasto-plastic damage Thermo-Hydraulic-Mechanical theoretical model will be validated from existing experimental data for sandstone after simulating some scenarios by using FEM on MATLAB software.

Keywords: carbon capture and storage, rock mechanics, THM effects on rock, constitutive model

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4678 Voices from Inside and the Power of Art to Transform and Restore

Authors: Karen Miner-Romanoff

Abstract:

Few art programs for incarcerated juveniles exist; however, evaluation results indicate decreased recidivism and behavior problems. This paper reports on an on-going study of a promising art program for incarcerated adolescents with community exhibits and charitable sale of their work. Voices from Inside, a partnership between Franklin University and the Ohio Department of Youth Services, sponsored three exhibits in 2012, 2013, and 2014. In 2013, youth exhibitor survey results (response rate 47%, 16 of 34) showed that 81% cited as benefits cooperation with others, task completion, and increased self-esteem from public recognition and art sales. Community attendee survey results (response rate 29.5%, 59 of 200) showed positive attitude changes toward juvenile offenders, from 40% to 53%. Qualitative responses were similarly positive. The 2014 youth exhibitor sample was larger (response rate 58%, 29 of 50) and showed that 93% cited positive benefits including increase in self-esteem, decrease in stress, pride or recognition of the ability to reach a goal from completing, exhibiting and selling their art to benefit a charity for at-risk youth. This year, the research was able to conduct ten one-on-one interviews inside of the youth facilities, and qualitative responses were even more positive with one youth explaining, “This art represents my joy, my tears, my pain and my hope.” Community attendee survey results (response rate 50%, 86 of 170) were transformative in that that they indicated significant impression on attitudes toward juvenile offenders and their rehabilitative needs with one attendee stating that the event had an, “Immense impact for me bringing into focus the humanity and value these youth still have for us and society.” Future research indicates a need for a correlation study to determine the extent to which these art programs reduce behavioral incidents inside of the facility and long-term reduction in reoffending rates. Generally, further study of juvenile offenders’ art for rehabilitation and restorative justice, the power of art to transform, and university-community partnerships implementing art programs for juvenile offenders should continue.

Keywords: art, juvenile, incarcerated, restorative justice

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4677 Influence of Sodium Lauryl Ether Sulfate and Curing Temperature on Behaviors of Lightweight Kaolinite-Based Geopolymer

Authors: W. Sornlar, S. Supothina, A. Wannagon

Abstract:

Lightweight geopolymer can be prepared by using some foaming agents, such as metal powders or hydrogen peroxide; however, it is difficult to control the generated cell size due to the high reactivity of the system. This study aims to investigate the influence of Sodium Lauryl Ether Sulfate (SLES) foam addition and curing temperature on the physical, mechanical, thermal, and microstructure behaviors of the lightweight kaolinite-based geopolymer. To provide porous structure, the geopolymer paste was mixed with 0-15 wt% of SLES foam before casting into the mold. Testing and characterizations were carried out after 28 days. The results showed that SLES foam generated the regular and spherical macropores, which were well distributed in the geopolymer samples. The total porosity increased as SLES foam increased, similarly as the apparent porosity and water absorption. On the other hand, the bulk density and mechanical strength decreased as SLES foam increased. Curing temperature was studied simultaneously due to it strongly affects the mechanical strength of geopolymer. In this study, rising of curing temperature from 27 to 50°C (at 75% relative humidity) improved the compressive strength of samples but deteriorated after curing at 60°C. Among them, the composition of 15 wt% SLES foam (NF15) presented the highest porosity (70.51-72.89%), the lowest density (0.68-0.73 g/cm³), and very low thermal conductivity (0.172-0.197 W/mK). It had the proper compressive strength of 4.21-4.74 MPa that can be applied for the thermal insulation.

Keywords: lightweight, kaolinite-based geopolymer, curing temperature, foaming agent, thermal conductivity

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4676 Polydimethylsiloxane Applications in Interferometric Optical Fiber Sensors

Authors: Zeenat Parveen, Ashiq Hussain

Abstract:

This review paper consists of applications of PDMS (polydimethylsiloxane) materials for enhanced performance, optical fiber sensors in acousto-ultrasonic, mechanical measurements, current applications, sensing, measurements and interferometric optical fiber sensors. We will discuss the basic working principle of fiber optic sensing technology, various types of fiber optic and the PDMS as a coating material to increase the performance. Optical fiber sensing methods for detecting dynamic strain signals, including general sound and acoustic signals, high frequency signals i.e. ultrasonic/ultrasound, and other signals such as acoustic emission and impact induced dynamic strain. Optical fiber sensors have Industrial and civil engineering applications in mechanical measurements. Sometimes it requires different configurations and parameters of sensors. Optical fiber current sensors are based on Faraday Effect due to which we obtain better performance as compared to the conventional current transformer. Recent advancement and cost reduction has simulated interest in optical fiber sensing. Optical techniques are also implemented in material measurement. Fiber optic interferometers are used to sense various physical parameters including temperature, pressure and refractive index. There are four types of interferometers i.e. Fabry–perot, Mach-Zehnder, Michelson, and Sagnac. This paper also describes the future work of fiber optic sensors.

Keywords: fiber optic sensing, PDMS materials, acoustic, ultrasound, current sensor, mechanical measurements

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4675 Fabrication of All-Cellulose Composites from End-of-Life Textiles

Authors: Behnaz Baghaei, Mikael Skrifvars

Abstract:

Sustainability is today a trend that is seen everywhere, with no exception for the textiles 31 industry. However, there is a rather significant downside regarding how the textile industry currently operates, namely the huge amount of end-of-life textiles coming along with it. Approximately 73% of the 53 million tonnes of fibres used annually for textile production is landfilled or incinerated, while only 12% is recycled as secondary products. Mechanical recycling of end-of-life textile fabrics into yarns and fabrics was before very common, but due to the low costs for virgin man-made fibres, the current textile material composition diversity, the fibre material quality variations and the high recycling costs this route is not feasible. Another way to decrease the ever-growing pile of textile waste is to repurpose the textile. If a feasible methodology can be found to reuse end-of life textiles as secondary market products including a manufacturing process that requires rather low investment costs, then this can be highly beneficial to counteract the increasing textile waste volumes. In structural composites, glass fibre textiles are used as reinforcements, but today there is a growing interest in biocomposites where the reinforcement and/or the resin are from a biomass resource. All-cellulose composites (ACCs) are monocomponent or single polymer composites, and they are entirely made from cellulose, ideally leading to a homogeneous biocomposite. Since the matrix and the reinforcement are both made from cellulose, and therefore chemically identical, they are fully compatible with each other which allow efficient stress transfer and adhesion at their interface. Apart from improving the mechanical performance of the final products, the recycling of the composites will be facilitated. This paper reports the recycling of end-of-life cellulose containing textiles by fabrication of all-cellulose composites (ACCs). Composite laminates were prepared by using an ionic liquid (IL) in a hot process, involving a partial dissolving of the cellulose fibres. Discharged denim fabrics were used as the reinforcement while dissolved cellulose from two different cellulose resources was used as the matrix phase. Virgin cotton staple fibres and recovered cotton from polyester/cotton (polycotton) waste fabrics were used to form the matrix phase. The process comprises the dissolving 6 wt.% cellulose solution in the ionic liquid 1-butyl-3-methyl imidazolium acetate ([BMIM][Ac]), this solution acted as a precursor for the matrix component. The denim fabrics were embedded in the cellulose/IL solution after which laminates were formed, which also involved removal of the IL by washing. The effect of reuse of the recovered IL was also investigated. The mechanical properties of the obtained ACCs were determined regarding tensile, impact and flexural properties. Mechanical testing revealed that there are no clear differences between the values measured for mechanical strength and modulus of the manufactured ACCs from denim/cotton-fresh IL, denim/recovered cotton-fresh IL and denim/cotton-recycled IL. This could be due to the low weight fraction of the cellulose matrix in the final ACC laminates and presumably the denim as cellulose reinforcement strongly influences and dominates the mechanical properties. Fabricated ACC composite laminates were further characterized regarding scanning electron microscopy.

Keywords: all-cellulose composites, denim fabrics, ionic liquid, mechanical properties

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4674 Agarose Based Multifunctional Nanofibrous Bandages for Wound Healing Applications

Authors: Sachin Latiyan, T. S. Sampath Kumar, Mukesh Doble

Abstract:

Natural polymer based nanofibrous wound dressings have gained increased attention because of their high surface area, bioactivity, biodegradability and resemblance to extracellular matrix. Agarose (a natural polymer) have been used largely for angiogenesis, cartilage formation and wound healing applications. However, electrospinning of agarose is tedious thereby rendering limited studies on fabrication and evaluation of agarose based nanofibrous wound dressings. Thus, present study focuses on the fabrication of agarose (10% w/v)/ polyvinyl alcohol (12% w/v) based multifunctional nanofibrous scaffolds. Zinc citrate (1, 3 and 5% w/w of the polymer) was added as a potential antibacterial agent to combat wound infections. The fabricated scaffolds exhibit ~500% swelling (in phosphate buffer saline) with enhanced mechanical strength which is suitable for most of the wound healing applications. In vitro studies were found to reveal an increased migration and proliferation of L929 mouse fibroblasts with agarose blends w.r.t to the control. The fabricated dressings were found to be effective against both Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) bacterial strains. Hence, a multifunctional (as provides effective swelling and mechanical support along with antibacterial property), natural product based, eco-friendly scaffold was successfully fabricated to serve as a potential wound dressing material.

Keywords: antibacterial dressings, benign solvent, nanofibrous agarose, biocompatibility, enhanced swelling and mechanical strength, biopolymeric dressings

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4673 Graphic Procession Unit-Based Parallel Processing for Inverse Computation of Full-Field Material Properties Based on Quantitative Laser Ultrasound Visualization

Authors: Sheng-Po Tseng, Che-Hua Yang

Abstract:

Motivation and Objective: Ultrasonic guided waves become an important tool for nondestructive evaluation of structures and components. Guided waves are used for the purpose of identifying defects or evaluating material properties in a nondestructive way. While guided waves are applied for evaluating material properties, instead of knowing the properties directly, preliminary signals such as time domain signals or frequency domain spectra are first revealed. With the measured ultrasound data, inversion calculation can be further employed to obtain the desired mechanical properties. Methods: This research is development of high speed inversion calculation technique for obtaining full-field mechanical properties from the quantitative laser ultrasound visualization system (QLUVS). The quantitative laser ultrasound visualization system (QLUVS) employs a mirror-controlled scanning pulsed laser to generate guided acoustic waves traveling in a two-dimensional target. Guided waves are detected with a piezoelectric transducer located at a fixed location. With a gyro-scanning of the generation source, the QLUVS has the advantage of fast, full-field, and quantitative inspection. Results and Discussions: This research introduces two important tools to improve the computation efficiency. Firstly, graphic procession unit (GPU) with large amount of cores are introduced. Furthermore, combining the CPU and GPU cores, parallel procession scheme is developed for the inversion of full-field mechanical properties based on the QLUVS data. The newly developed inversion scheme is applied to investigate the computation efficiency for single-layered and double-layered plate-like samples. The computation efficiency is shown to be 80 times faster than unparalleled computation scheme. Conclusions: This research demonstrates a high-speed inversion technique for the characterization of full-field material properties based on quantitative laser ultrasound visualization system. Significant computation efficiency is shown, however not reaching the limit yet. Further improvement can be reached by improving the parallel computation. Utilizing the development of the full-field mechanical property inspection technology, full-field mechanical property measured by non-destructive, high-speed and high-precision measurements can be obtained in qualitative and quantitative results. The developed high speed computation scheme is ready for applications where full-field mechanical properties are needed in a nondestructive and nearly real-time way.

Keywords: guided waves, material characterization, nondestructive evaluation, parallel processing

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4672 Review of Comparison of Subgrade Soil Stabilised with Natural, Synthetic, and Waste Fibers

Authors: Jacqueline Michella Anak Nathen

Abstract:

Subgrade soil is an essential component in the design of road structures as it provides lateral support to the pavement. One of the main reasons for the failure of the pavement is the settlement of the subgrade and the high susceptibility to moisture, which leads to a loss of strength of the subgrade. Construction over weak or soft subgrade affects the performance of the pavement and causes instability of the pavement. If the mechanical properties of the subgrade soils are lower than those required, the soil stabilisation method can be an option to improve the soil properties of the weak subgrade. Soil stabilisation is one of the most popular techniques for improving poor subgrade soils, resulting in a significant improvement in the subgrade soil’s tensile strength, shear strength, and bearing capacity. Soil stabilisation encompasses the various methods used to alter the properties of soil to improve its engineering properties. Soil stabilisation can be broadly divided into four types: thermal, electrical, mechanical, and chemical. The most common method of improving the physical and mechanical properties of soils is stabilisation using binders such as cement and lime. However, soil stabilisation with conventional methods using cement and lime has become uneconomical in recent years, so there is a need to look for an alternative, such as fiber. Although not a new technique, adding fiber is a very practical alternative to soil stabilisation. Various types of fibers, such as natural, synthetic, and waste fibers, have been used as stabilising agents to improve the strength and durability of subgrade soils. This review provides a comprehensive comparison of the effectiveness of natural, synthetic, and waste fibers in stabilising subgrade soils.

Keywords: subgrade, soil stabilisation, pavement, fiber, stabiliser

Procedia PDF Downloads 96