Search results for: adhesion strength

Authors: Eman Helal, Ahmed M. Esmat

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Statement of problem: The development of computer-aided design/computer-aided manufacturing (CAD/CAM) resin dentures has simplified complete denture production. Most of the studies evaluated the mechanical properties of the material, but the hygienic performance of the CAD /CAM denture and their ability to maintain clean surfaces and minimize bacterial accumulation is still lacking. Purpose evaluation of the antibacterial characteristics of the 3D printed CAD/CAM denture and to compare it with the conventional heat polymerized acrylic denture base material. Methodology a total of thirty completely edentulous patients grouped randomly into two groups (Group I: Control group) received conventional heat polymerized acrylic resin complete dentures, (Group II: Test group) received 3D printed (CAD/CAM) dentures (stereolithographic PMMA), Samples of Candida albicans culture swabs were taken after 1 month and 3 months of dentures` insertion. A culture swab was obtained by scrubbing the fitting surface of the upper denture. At each time interval, three swab samples were collected from each patient and were inoculated in three individual culture media. Results: there was a significant difference in the colonization of Candida albicans to the fitting surface of the dentures between both groups (Group I: Conventional denture cases) exhibited more adhesion of Candida Albicans to the fitting surface than did (Group II: CAD/CAM cases) (P<0.05). Conclusion: 3D printed CAD/CAM complete denture showed minimal Candida adherence upon upper denture fitting compared to conventional heat-polymerized acrylic resin, which contributes to decreasing the incidence of denture stomatitis which is considered one of the most common problems among complete denture wearers.

Keywords: CAD/CAM denture, completely edentulous, elderly patients, 3D printing, antimicrobial efficiency, conventional denture, PMMA, Candida Albicans, denture stomatitis

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Authors: Tasnuba Binte Jamal, Khan Mahmud Amanat

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Carbon Fiber-Reinforced Polymer (CFRP) composite materials have proven to have valuable properties and suitability to be used in the construction of new buildings and in upgrading the existing ones due to its effectiveness, ease of implementation and many more. In the present study, a numerical finite element investigation has been conducted using ANSYS 18.1 to study the behavior of square HSS AISC sections under eccentric compressive loading strengthened with CFRP materials. A three-dimensional finite element model for square HSS section using shell element was developed. Application of CFRP strengthening was incorporated in the finite element model by adding an additional layer of shell elements. Both material and geometric nonlinearities were incorporated in the model. The developed finite element model was applied to simulate experimental studies done by past researchers and it was found that good agreement exists between the current analysis and past experimental results, which established the acceptability and validity of the developed finite element model to carry out further investigation. Study was then focused on some selected non-compact AISC square HSS columns and the effects of number of CFRP layers, amount of eccentricities and cross-sectional geometry on the strength gain of those columns were observed. Load was applied at a distance equal to the column dimension and twice that of column dimension. It was observed that CFRP strengthening is comparatively effective for smaller eccentricities. For medium sized sections, strengthening tends to be effective at smaller eccentricities as well. For relatively large AISC square HSS columns, with increasing number of CFRP layers (from 1 to 3 layers) the gain in strength is approximately 1 to 38% to that of unstrengthened section for smaller eccentricities and slenderness ratio ranging from 27 to 54. For medium sized square HSS sections, effectiveness of CFRP strengthening increases approximately by about 12 to 162%. The findings of the present study provide a better understanding of the behavior of HSS sections strengthened with CFRP subjected to eccentric compressive load.

Keywords: CFRP strengthening, eccentricity, finite element model, square hollow section

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Authors: Jae-Il Jeong, Hoon-Jae Park, Jung-Woo Cho, Yang-Gon Kim, Jin-Young Park, Joo-Young Oh, Si-Geun Choi, Seock-Sam Kim, Young Tae Cho, Chan Gyu Kim, Jong-Hyoung Kim

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Bearing component has strongly required to decrease vibration and wear to achieve high durability and life time. In the industry field, bearing durability is improved by surface treatment on the bearing surface by centrifugal casting or gravity casting production method. However, this manufacturing method has caused problems such as long processing time, defect rate, and health harmful effect. To solve this problem, there is a laser cladding deposition treatment, which provides fast processing and food adhesion. Therefore, optimum conditions of white metal laser deposition should be studied to minimize bearing contact axis wear using laser cladding techniques. In this study, we deposit a soft white metal layer on SCM440, which is mainly used for shaft and bolt. On laser deposition process, the laser power and powder feed rate and laser head speed factors are controlled to find out the optimal conditions. We also measure hardness using micro Vickers, analyze FE-SEM (Field Emission Scanning Electron Microscope) and EDS (Energy Dispersive Spectroscopy) to study the mechanical properties and surface characteristics with various parameters change. Furthermore, this paper suggests the optimum condition of laser cladding deposition to apply in industrial fields. This work was supported by the Industrial Innovation Project of the Korea Evaluation Institute of Industrial Technology (KEIT) granted financial resource from the Ministry of Trade, Industry & Energy, Republic of Korea (Research no. 10051653).

Keywords: laser deposition, bearing, white metal, mechanical properties

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Authors: Corey F. Fitzgerald

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This study provides a comprehensive examination of the biomechanical sequencing inherent in pitching motions, coupled with an advanced methodology for interpreting gathered data to inform programming strategies. The analysis is conducted utilizing state-of-the-art biomechanical laboratory equipment capable of detecting subtle changes and deviations, facilitating highly informed decision-making processes. Through this presentation, the intricate dynamics of pitching sequences are meticulously discussed to highlight the complex movement patterns accessible and actionable for performance enhancement purposes in the weight room.

Keywords: sport science, applied biomechanics, strength and conditioning, applied research

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Authors: Amirhosein Rostampour, Mehdi Sharif

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In this article, a series of high impact polystyrene/graphene (HIPS/Gr) nanocomposites were prepared by solution mixing method and their morphology and dynamic mechanical properties were investigated as a function of graphene content. SEM images and X-Ray diffraction data confirm that the graphene platelets are well dispersed in HIPS matrix for the nanocomposites with Gr contents up to 5.0 wt%. Mechanical properties analysis demonstrates that yielding strength and initial modulus of HIPS/Gr nanocomposites are highly improved with the increment of Gr content compared to pure HIPS.

Keywords: nanocomposite, graphene, dynamic mechanical properties, morphology

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Authors: Hanna Faron, Wojciech Marcinkowski, Daniel Prusak, Władysław Hamiga

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Interest in composite materials comes out of two basic premises: their supreme mechanical and strength properties,combined with a small specific weight. Origin and evolution of modern composite materials bonds with development of manufacturing of synthetic fibers, which have begun during Second World War. Main condition to achieve intended properties of composite materials is proper bonding of reinforcing layer with appropriate adhesive in manufacturing process. It is one of the fundamental quality evaluation criterion of fabrication processes.

Keywords: SAE, formula student, composite materials, carbon fiber, Aramid fiber, hot wire cutter

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Authors: Hany M. Fayed, Rehab F. Abdel-Rahman, Alyaa F. Hessin, Hanan A. Ogaly, Gihan F. Asaad, Abeer A. A. Salama, Sahar Abdelrahman, Mahmoud S. Arbid, Marwan Abd Elbaset Mohamed

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Liver fibrosis is a serious global health problem that occurs as a result of a variety of chronic liver disorders. Apigenin, a flavonoid found in many plants, has several pharmacological properties. The aim of this study was to evaluate the antifibrotic efficacy of apigenin (APG) against experimentally induced hepatic fibrosis in rats via using thioacetamide (TAA) and to explore the possible underlying mechanisms. TAA (100 mg/kg, i.p.) was given three times each week for two weeks to induce liver fibrosis. After TAA injections, APG was given orally (5 and 10 mg/kg) daily for two weeks. Biochemical, molecular, histological and immunohistochemical analyses were performed on blood and liver tissue samples. The functioning of the liver, oxidative stress, inflammation, and liver fibrosis indicators were all evaluated. The findings showed that TAA markedly increased the activities of aspartate aminotransferase (AST) and alanine aminotransferase (ALT), as well as the levels of malondialdehyde (MDA), focal adhesion kinase (FAK), hypoxia-inducible factor-1 (HIF-1), nuclear factor-κB (NF-κB), transforming growth factor-beta (TGF-β), tumor necrosis factor-alpha (TNF-α) and interleukin-1β (IL-1β) with a reduction in albumin, total protein, A/G ratio, GSH content and interleukin-10 (IL-10). Moreover, TAA elevated the content of collagen I, α -smooth muscle actin (α-SMA), and hydroxyproline in the liver. The treatment with APG in a dose-dependent manner has obviously prevented these alterations and amended the harmful effects induced by TAA. The histopathological and immunohistochemical observations supported this biochemical evidence. The higher dose of APG produced the most significant antifibrotic effect. As a result of these data, APG appears to be a promising antifibrotic drug and could be used as a new herbal medication or dietary supplement in the future for the treatment of liver fibrosis. This effect might be related to the inhibition of the HIF-1/FAK signaling pathway.

Keywords: apigenin, FAK, HIF-1, liver fibrosis, rat, thioacetamide

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Authors: Mariya Dayana, Budhmal Jain

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Kannur International Airport Ltd. (KIAL) is a new Greenfield airport project with airside development on an undulating terrain with an average height of 90m above Mean Sea Level (MSL) and a maximum height of 142m. To accommodate the desired Runway length and Runway End Safety Area (RESA) at both the ends along the proposed alignment, it resulted in 45.5 million cubic meters in cutting and filling. The insufficient availability of land for the construction of free slope embankment at RESA 07 end resulted in the design and construction of Reinforced Soil Slope (RSS) with a maximum slope of 65 degrees. An embankment fill of average 70m height with steep slopes located in high rainfall area is a unique feature of this project. The design and construction was challenging being asymmetrical with curves and bends. The fill was reinforced with high strength Uniaxial geogrids laid perpendicular to the slope. Weld mesh wrapped with coir mat acted as the facia units to protect it against surface failure. Face anchorage were also provided by wrapping the geogrids along the facia units where the slope angle was steeper than 45 degrees. Considering high rainfall received on this table top airport site, extensive drainage system was designed for the high embankment fill. Gabion wall up to 10m height were also designed and constructed along the boundary to accommodate the toe of the RSS fill beside the jeepable track at the base level. The design of RSS fill was done using ReSSA software and verified in PLAXIS 2D modeling. Both slip surface failure and wedge failure cases were considered in static and seismic analysis for local and global failure cases. The site won excavated laterite soil was used as the fill material for the construction. Extensive field and laboratory tests were conducted during the construction of RSS system for quality assurance. This paper represents a case study detailing the design and construction of a very high embankment using geosynthetics for the provision of Runway length and RESA area.

Keywords: airport, embankment, gabion, high strength uniaxial geogrid, kial, laterite soil, plaxis 2d

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Authors: Mohit Chauhan, Atul Narayan

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Moisture damage is the continuous deterioration of asphalt concrete mixtures by the loss of adhesive bond between the asphalt binder and aggregates, or loss of cohesive bonds within the asphalt binder in the presence of moisture. Moisture has been known to either cause or exacerbates distresses in asphalt concrete pavements. Since moisture would often retain for a relatively long duration at the bottom of asphalt concrete layer, the movement of traffic loading in this saturated condition would cause excess stresses or strains within the mixture. This would accelerate the degradation of the adhesion and cohesion within the mixture and likely to contribute the development of fatigue cracking in asphalt concrete pavements. In view of this, it is important to investigate the effect of moisture on the fatigue behavior of asphalt concrete mixtures. In this study, changes in fatigue characteristics after moisture conditioning were evaluated by conducting four-point beam fatigue tests on dry and moisture conditioned specimens. For this purpose, mixtures with two different types of binders were prepared and saturated with moisture using 700 mm Hg vacuum. Beam specimens, in this way, were taken to a saturation level of 65-75 percent. After preconditioning specimens in this degree of saturation and 60°C for a period of 24 hours, they were subjected to four point beam fatigue tests in strain-controlled mode with a strain amplitude of 400 microstrain. The results were then compared with the fatigue test results obtained with beam specimens that were not subjected to moisture conditioning. Test results show that the conditioning reduces both fatigue life and initial flexural stiffness of specimen significantly. The moisture conditioning was also found to increase the rate of reduction of flexural stiffness. Moreover, it was observed that the fatigue life ratio (FLR), the ratio of the fatigue life of the moisture conditioned sample to that of the dry sample, is significantly lower than the flexural stiffness ratio (FSR). The study indicates that four-point bending test is an appropriate tool with FLR and FSR as the potential parameters for moisture-sensitivity evaluation.

Keywords: asphalt concrete, fatigue cracking, moisture damage, preconditioning

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Authors: Anca Maria Cimpean, Serban Comsa

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Chick embryo chorioallantoic membrane (CAM) is a well vascularised in vivo experimental model used as a platform for testing the behavior of different implants inserted on it from tumor fragments to therapeutic agents or various biomaterials. Five types of collagen-based biomaterials with 2D and 3D structure (MotifMesh, Optimaix2D, Optimaix3D, Dual Layer Collagen and Xenoderm) were implanted on CAM and continuously evaluated by stereomicroscope for up to 5 days post-implant with an emphasis of their ability to requisite and develop new blood vessels (BVs) followed by microscopic analysis. MotifMEsh did not induce any angiogenic response lacking to be invaded by BVs from the CAM, but it induced intense inflammatory response necrosis and fibroblastic reaction around the implant. Optimaix2D has good adherence. CAM with minimal or no inflammatory reaction, a good integration of the CAM between the collagen mesh’s fibers, consistent adhesion of the cells to the collagen fibers,and a good ability to form pseudo-vascular channels filled with cells. Optimaix3D induced the highest angiogenic effects on CAM. The material shows good integration on CAM. The collagen fibers of the material show the ability to organize themselves into linear and tubular structures. It is possible to see blood elements, especially at the periphery of the implant. Dual-layer collagen behaves similar to Optimaix 3D, while Xenoderm induced a moderate angiogenic effect on CAM. Based on these data, we may conclude that collagen-based materials have variable ability to requisite and develop new blood vessels. A proper selection of collagen-based biomaterial scaffolds may crucially influence the acquisition and development of blood vessels during angiogenesis assays.

Keywords: chick embryo chorioallantoic membrane, collagen scaffolds, blood vessels, vascular microenvironment

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Authors: Mohamed M. Ragab, Neveen A. Abdel Raoof, Reham H. Diab

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Background: Delayed onset muscle soreness (DOMS) is the most common symptom when ordinary individuals and athletes are exposed to unaccustomed physical activity, especially eccentric contraction which impairs athletic performance, ordinary people work ability and physical functioning. A multitude of methods have been investigated to reduce DOMS. One of the valuable method to control DOMS is repeated bout effect (RBE) as a prophylactic method. Purpose: To compare the repeated bout effect of submaximal eccentric contraction versus maximal isometric contraction on induced DOMS. Methods: Sixty normal male volunteers were assigned randomly into three groups of equal number: Group (A) “first study group”: 20 subjects received submaximal eccentric contraction on non-dominant elbow flexors as prophylactic exercise. Group (B) “second study group”: 20 subjects received maximal isometric contraction on non-dominant elbow flexors as prophylactic exercise. Group (C) “control group”: 20 subjects did not receive any prophylactic exercise. Maximal isometric contraction peak torque of elbow flexors and patient related elbow evaluation (PREE) scale were measured for each subject 3 times before, immediately after and 48 hours after induction of DOMS. Results: Post-hoc test for maximal isometric peak torque and PREE scale immediately and 48 hours after induction of DOMS revealed that group (A) and group (B) resulted in significant decrease in maximal isometric strength loss and elbow pain and disability rather than control group (C), but submaximal eccentric group (A) was more effective than maximal isometric group (B) as it showed more rapid recovery of functional strength and less degrees of elbow pain and disability. Conclusion: Both submaximal eccentric contraction and maximal isometric contraction were effective in prevention of DOMS but submaximal eccentric contraction had the greatest protective effect.

Keywords: delayed onset muscle soreness, maximal isometric peak torque, patient related elbow evaluation scale, repeated bout effect

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Authors: Mohd Javaid, Shahbaz Khan, Abid Haleem

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Purpose: Large numbers of 3D printing technologies are now available for sophisticated applications in different fields. Additive manufacturing has established its dominance in design, development, and customisation of the product. In the era of developing technologies, there is a need to identify the appropriate technology for different application. In order to fulfil this need, two widely used printing technologies such as Fused Deposition Modeling (FDM), and Binding-Jet 3D Printing are compared for effective utilisation in the current scenario for different applications. Methodology: Systematic literature review conducted for both technologies with applications and associated factors enabling for the same. Appropriate MCDM tool is used to compare critical factors for both the technologies. Findings: Both technologies have their potential and capabilities to provide better direction to the industry. Additionally, this paper is helpful to develop a decision support system for the proper selection of technologies according to their continuum of applications and associated research and development capability. The vital issue is raw materials, and research-based material development is key to the sustainability of the developed technologies. FDM is a low-cost technology which provides high strength product as compared to binding jet technology. Researcher and companies can take benefits of this study to achieve the required applications in lesser resources. Limitations: Study has undertaken the comparison with the opinion of experts, which may not always be free from bias, and some own limitations of each technology. Originality: Comparison between these technologies will help to identify best-suited technology as per the customer requirements. It also provides development in this different field as per their extensive capability where these technologies can be successfully adopted. Conclusion: FDM and binding jet technology play an active role in industrial development. These help to assist the customisation and production of personalised parts cost-effectively. So, there is a need to understand how these technologies can provide these developments rapidly. These technologies help in easy changes or in making revised versions of the product, which is not easily possible in the conventional manufacturing system. High machine cost, the requirement of skilled human resources, low surface finish, and mechanical strength of product and material changing option is the main limitation of this technology. However, these limitations vary from technology to technology. In the future, these technologies are to be commercially viable for efficient usage in direct manufacturing of varied parts.

Keywords: 3D printing, comparison, fused deposition modeling, FDM, binding jet technology

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Authors: Mahmood Niroobakhsh

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This article deals with special structuralism approaches to explain a certain kind of social problem. Widespread presence of poverty is a reminder of deep-rooted unresolved problems of social relations. The expected role from an individual for the social system recognizes poverty derived from an interrelated social structure. By the time, enabled to act on his role in the course of social interaction, reintegration of the poor in society may take place. Poverty and housing type are reflections of the underlying social structure, primarily structure’s elements, systemic interrelations, and the overall strength or weakness of that structure. Poverty varies based on social structure in that the stronger structures are less likely to produce poverty.

Keywords: absolute poverty, relative poverty, social structure, urban poverty

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Authors: Elham Azimzadeh, Saeedeh Sepehri, Hamidollah Hassanlouei

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Obesity is associated with postural instability, might influence the quality of daily life, and could be considered a potential factor for falling in obese people. The fat body mass especially in the abdominal area may increase body sway. Furthermore, loss of visual feedback may induce a larger postural sway in obese people. Moreover, Muscle fatigue may impair the work capacity of the skeletal muscle and may alter joint proprioception. So, the purpose of this study was to investigate the effect of physical fatigue and visual feedback on body sway and strength of lower extremities in obese people. 12 obese (4 female, 8 male; BMI >30 kg/m2), and 12 normal weight (4 female, 8 male; BMI: 20-25 kg/m2) subjects aged 37- 47 years participated in this study. The postural stability test on the Biodex balance system was used to characterize postural control along the anterior-posterior (AP) and mediolateral (ML) directions in eyes open and eyes closed conditions and maximal voluntary contraction (MVC) of knee extensors and flexors were measured before and after the high-intensity exhausting exercise protocol on the ergometer bike to confirm the presence of fatigue. Results indicated that the obese group demonstrated significantly greater body sway, in all indices (ML, AP, overall) compared with the normal weight group (eyes open). However, when visual feedback was eliminated, fatigue impaired the balance in the overall and AP indicators in both groups; ML sway was higher only in the obese group after exerting the fatigue in the eyes closed condition. Also, maximal voluntary contraction of knee extensors was impaired in the fatigued normal group but, there was no significant impairment in knee flexors MVC in both group. According to the findings, peripheral fatigue was associated with altered postural control in upright standing when eyes were closed, and that mechanoreceptors of the feet may be less able to estimate the position of the body COM over the base of support in the loss of visual feedback. This suggests that the overall capability of the postural control system during upright standing especially in the ML direction could be lower due to fatigue in obese individuals and could be a predictor of future falls.

Keywords: maximal voluntary contraction, obesity, peripheral fatigue, postural control, visual feedback

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Authors: Mehrzad Mohabbi Yadollahi, Pouneh Abdollahifard, Behzad Mokhtare, Majid Atashafrazeh

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Geopolymers are believed to provide good fire resistance. The effects of elevated temperatures on mechanical and microstructural properties of pumice-based geopolymer were investigated in this study. Pumice based geopolymer was exposed to elevated temperatures of 200, 400, 600, and 800 ºC for 3 hours. The residual strength of these specimens was determined after cooling at room temperature and microstructures of these samples were investigated by FTIR and SEM analyses. Specimens which were initially grey turned reddish accompanied by the appearance of cracks as temperatures increased to 600 and 800 ºC.

Keywords: geopolymer, pumice, elevated temperature, SEM, FTIR

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Authors: Sharmistha Chowdhury, Shuva Chowdhury

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Buying-selling new as well as second-hand goods like tools, furniture, household, electronics, clothing, baby stuff, vehicles, and hobbies through the Facebook marketplace has become a new paradigm for c2c sellers. This phenomenon encourages and empowers decentralised home-oriented sellers. This study adopts Elaboration Likelihood Model (ELM) to explain consumer behaviour on Facebook Marketplace (FM). ELM suggests that consumers process information through the central and peripheral routes, which eventually shape their attitudes towards posts. The central route focuses on information quality, and the peripheral route focuses on cues. Sellers’ FM posts usually include product features, prices, conditions, pictures, and pick-up location. This study uses information relevance and accuracy as central route factors. The post’s attractiveness represents cues and creates positive or negative associations with the product. A post with remarkable pictures increases the attractiveness of the post. So, post aesthetics is used as a peripheral route factor. People influenced via the central or peripheral route forms an attitude that includes multiple processes – response and purchase intention. People respond to FM posts through save, share and chat. Purchase intention reflects a positive image of the product and higher purchase intention. This study proposes trust on sellers as a moderator to test the strength of its influence on consumer attitudes and behaviour. Trust on sellers is assessed whether sellers have badges or not. A sample questionnaire will be developed and distributed among a group of random FM sellers who are selling vehicles on this platform to conduct the study. The chosen product of this study is the vehicle, a high-value purchase item. High-value purchase requires consumers to consider forming their attitude without any sign of impulsiveness seriously. Hence, vehicles are the perfect choice to test the strength of consumers attitudes and behaviour. The findings of the study add to the elaboration likelihood model and online second-hand marketplace literature.

Keywords: consumer behaviour, elaboration likelihood model, facebook marketplace, c2c marketing

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Authors: Shigeyuki Haruyama, Oke Oktavianty, Zefry Darmawan, Tadayuki Kyoutani, Ken Kaminishi

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Cab’s frame strength is considered as an important factor in excavator’s operator safety, especially during roll-over. In this study, we use a model of cab frame with different thicknesses and perform elastoplastic numerical analysis by using Finite Element Method (FEM). Deformation mode and energy absorption's of cab’s frame part are investigated on two conditions, with wrinkle and without wrinkle. The occurrence of wrinkle when deforming cab frame can reduce energy absorption, and among 4 parts with wrinkle, the energy absorption significantly decreases in part C. Residual stress that generated upon the bending process of part C is analyzed to confirm it possibility in increasing the energy absorption.

Keywords: ROPS, FEM, hydraulic excavator, cab frame

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Authors: Angel Pérez Sánchez

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Magnet attraction or repulsion is not a product of a strange force from afar but comes from anchored lines of force inside the magnet as if it were reinforced concrete since you can move a small block by taking the steel rods that protrude from its interior. This approach serves as a basis for studying the behavior of diamagnetic materials. The significance of this study is to unify all diamagnetic phenomena: Movement of grapes, cooper approaching a magnet, Magnet levitation, etc., with a single explanation for all these phenomena. The method followed has consisted of observation of hundreds of diamagnetism experiments (in copper, aluminum, grapes, tomatoes, and bismuth), including the creation of own and new experiments and application of logical deduction product of these observations. Approaching a magnet to a hanging grape, Diamagnetism seems to consist not only of a slight repulsion but also of a slight attraction at a small distance. Replacing the grapes with a copper sphere, it behaves like the grape, pushing and pulling a nearby magnet. Diamagnetism could be redefined in the following way: There are materials that don't magnetize their internal structure when approaching a magnet, as ferromagnetic materials do. But they do allow magnetic lines of force to run through its interior, enhancing them without creating their own lines of force. Magnet levitates on superconducting ceramics because magnet gives lines near poles a force superior to what a superconductor can enhance these lines. Little further from the magnet, enhancing of lines by the superconductor is greater than the strength provided by the magnet due to the distance from the magnet's pole. It is this point that defines the magnet's levitation band. The anchoring effect of lines is what ultimately keeps the magnet and superconductor at a certain distance. The magnet seeks to levitate the area in which magnetic lines are stronger near de magnet's poles. Pouring ferrofluid into a magnet, lines of force are observed coming out of the poles. On other occasions, diamagnetic materials simply enhance the lines they receive without moving their position since their own weight is greater than the strength of the enhanced lines. (This is the case with grapes and copper). Magnet and diamagnetic materials look for a place where the lines of force are most enhanced, and this is at a small distance. Once the ideal distance is established, they tend to keep it by pushing or pulling on each other. At a certain distance from the magnet: the power exerted by diamagnetic materials is greater than the force of lines in the vicinity of the magnet's poles. All Diamagnetism phenomena: copper, aluminum, grapes, tomatoes, bismuth levitation, and magnet levitation on superconducting ceramics can now be explained with the support of magnetic lines of force.

Keywords: diamagnetism, magnetic levitation, magnetic lines of force, enhancing magnetic lines

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Authors: C. Catalina Zapata, Z. Claudia Montoya

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Transplant from hematopoietic parents (THP) or medulla (MT) is a procedure used to replace the medulla that does not work as part of a disease or when it is destroyed either by a treatment of high medication doses against cancer or by radiation. The transplant process has three stages, a stage prior to transplant, during and after the transplant. It is held with the help of an interdisciplinary team, including nursing, carrying out mainly educative procedures to warrant the adhesion and the changes in lifestyles needed to whom will undergo this procedure. The aim of the study was to assess the results of an educative procedure by nursing, on adult patients subjected to a transplant from hematopoietic parents at a high complexity institution of Medellin city, Colombia. This study had an observational longitudinal design. According to the rules of protocol, the educative activity must be held on all patients joining the procedure. Four instruments were designed in order to collect all the information. One of them to measure the sociodemographic variables, another one to measure self-care practices, another one to measure transplant knowledge and its cares and the other one to measure the 30-day post-transplant complications. The last three instruments were applied before and after the educative procedure. A univaried analysis was carried out but the bivaried analysis was not carried out since there were not statistically meaningful differences before and after. Within the results, ten patients were evaluated. The average age was 38.2 (13.38 SD – standard deviation), 8/10 were men. Some self-care practices such us having pets and plants and consuming some specific food as well as little use of UV protection are all present in this type of patients and are not modified after the procedure. In measuring the knowledge, something stands out among the answers. It is the fact that some patients do not know what the medulla is, the nature of separating wastes at home and the need to consult about vomit and nausea. The most frequent complications during the first thirty days were: nausea, vomit, fever, and rash. They are considered to be expected within this period. Patients do not exhibit differences in their level of knowledge before and after the educative procedure by nursing. The patients’ self-care practices do not involve all the necessary ones to avoid complications. During the first 30 days, most of the complications are typical of the transplant process from hematopoietic parents.

Keywords: bone marrow transplant, education, family, nursing, patients, Transplantation of hematopoietic progenitors

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Authors: A. Hakem, Y. Bouafia

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Characterization of materials used for various mechanical components is of great importance in their design. Several studies were conducted by various authors in order to improve their physical and/or chemical properties in general and mechanical or metallurgical properties in particular. The foundry alloy AlSi7Zn3Cu2Mg is one of the main components constituting the various mechanisms for the implementation of applications and various industrial projects. Obtaining a reliable product is not an easy task; several results proposed by different authors show sometimes results that can contradictory. Due to their high mechanical characteristics, these alloys are widely used in engineering. Silicon improves casting properties and magnesium allows heat treatment. It is thus possible to obtain various degrees of hardening and therefore interesting compromise between tensile strength and yield strength, on one hand, and elongation, on the other hand. These mechanical characteristics can be further enhanced by a series of mechanical treatments or heat treatments. Their light weight coupled with high mechanical characteristics, aluminum alloys are very much used in cars and aircraft industry. The present study is focused on the influence of heat treatments which cause significant micro structural changes, usually hardening by variation of annealing temperatures by increments of 10°C and 20°C on the evolution of the main elastic characteristics, the resistance, the ductility and the structural characteristics of AlSi7Zn3Cu2Mg foundry alloy cast in sand by gravity. These elastic properties are determined in three directions for each specimen of dimensions 200x150x20 mm³ by the ultrasonic method based on acoustic or elastic waves. The hardness, the micro hardness and the structural characteristics are evaluated by a non-destructive method. The aim of this work is to study the hardening ability of AlSi7Zn3Cu2Mg alloy by considering ten states. To improve the mechanical properties obtained with the raw casting, one should use heat treatment for structural hardening; the addition of magnesium is necessary to increase the sensitivity to this specific heat treatment: Treatment followed by homogenization which generates a diffusion of atoms in a substitution solid solution inside a hardening furnace at 500°C during 8h, followed immediately by quenching in water at room temperature 20 to 25°C, then an ageing process for 17h at room temperature and at different annealing temperature (150, 160, 170, 180, 190, 240, 200, 220 and 240°C) for 20h in an annealing oven. The specimens were allowed to cool inside the oven.

Keywords: aluminum, foundry alloy, magnesium, mechanical characteristics, silicon

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Authors: Vera Sovkova, Andrea Mickova, Matej Buzgo, Karolina Vocetkova, Eva Filova, Evzen Amler

Abstract:

PCL (poly-ε-caprolactone) nanofibrous scaffolds with adhered liposomes were prepared and tested as a possible drug delivery system for various synthetic growth factors. TGFβ, bFGF, and IGF-I have been shown to increase hMSC (human mesenchymal stem cells) proliferation and to induce hMSC differentiation. Functionalized PCL nanofibers were prepared with synthetic growth factors encapsulated in liposomes adhered to them in three different concentrations. Other samples contained PCL nanofibers with adhered, free synthetic growth factors. The synthetic growth factors free medium served as a control. The interaction of liposomes with the PCL nanofibers was visualized by SEM, and the release kinetics were determined by ELISA testing. The potential of liposomes, immobilized on the biodegradable scaffolds, as a delivery system for synthetic growth factors, and as a suitable system for MSCs adhesion, proliferation and differentiation in vitro was evaluated by MTS assay, dsDNA amount determination, confocal microscopy, flow cytometry and real-time PCR. The results showed that the growth factors adhered to the PCL nanofibers stimulated cell proliferation mainly up to day 11 and that subsequently their effect was lower. By contrast, the release of the lowest concentration of growth factors from liposomes resulted in gradual proliferation of MSCs throughout the experiment. Moreover, liposomes, as well as free growth factors, stimulated type II collagen production, which was confirmed by immunohistochemical staining using monoclonal antibody against type II collagen. The results of this study indicate that growth factors enriched liposomes adhered to surface of PCL nanofibers could be useful as a drug delivery instrument for application in short timescales, be combined with nanofiber scaffolds to promote local and persistent delivery while mimicking the local microenvironment. This work was supported by project LO1508 from the Ministry of Education, Youth and Sports of the Czech Republic

Keywords: drug delivery, growth factors, hMSC, liposomes, nanofibres

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Authors: Irfan Turetgen

Abstract:

Closed-circuit cooling towers are cooling units that operate according to the indirect cooling principle. Unlike the open-loop cooling tower, the filler material includes a closed-loop water-operated heat exchanger. The main purpose of this heat exchanger is to prevent the cooled process water from contacting with the external environment. In order to ensure that the hot water is cooled, the water is cooled by the air flow and the circulation water of the tower as it passes through the pipe. They are now more commonly used than open loop cooling towers that provide cooling with plastic filling material. As with all surfaces in contact with water, there is a biofilm formation on the outer surface of the pipe. Although biofilm has been studied very well on plastic surfaces in open loop cooling towers, studies on biofilm layer formed on the heat exchangers of the closed circuit tower have not been found. In the recent study, natural biofilm formation was observed on the heat exchangers of the closed loop tower for 6 months. At the same time, nano-silica coating, which is known to reduce the formation of the biofilm layer, a comparison was made between the two different surfaces in terms of biofilm formation potential. Test surfaces were placed into biofilm reactor along with the untreated control coupons up to 6-months period for biofilm maturation. Natural bacterial communities were monitored to analyze the impact to mimic the real-life conditions. Surfaces were monthly analyzed in situ for their microbial load using epifluorescence microscopy. Wettability is known to play a key role in biofilm formation on surfaces, because characteristics of surface properties affect the bacterial adhesion. Results showed that surface-conditioning with nano-silica significantly reduce (up to 90%) biofilm formation. Easy coating process is a facile and low-cost method to prepare hydrophobic surface without any kinds of expensive compounds or methods.

Keywords: biofilms, cooling towers, fill material, nano silica

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Authors: Florian Keipert, Hagen Schmitd

Abstract:

The size selective separation of different species in a microfluidic system is an actual task in biological or medical research. Former works dealt with the utilisation of the acoustic radiation force (ARF) caused by a plane travelling Surface Acoustic Wave (tSAW). In literature the ARF is described by a dimensionless parameter κ, depending on the wavelength and the particle diameter. To our knowledge research was done for values 0.2 < κ < 5.8 showing that the ARF is dominating the acoustic streaming force (ASF) for κ > 1.2. As a consequence the particle separation is limited by κ. In addition the dependence on the electrical power level was examined but only for κ > 1 pointing out an increased particle deflection for higher electrical power levels. Nevertheless a detailed study on the ASF and ARF especially for κ < 1 is still missing. In our setup we used a tSAW with a wavelength λ = 90 µm and 3 µm PS particles corresponding to κ = 0.3. Herewith the influence of the applied electrical power level on the particle deflection in a polydimethylsiloxan micro channel was investigated. Our results show an increased particle deflection for an increased electrical power level, which coincides with the reported results for κ > 1. Therefore particle separation is in contrast to literature also possible for lower κ values. Thereby the experimental setup can be generally simplified by a coordinated electrical power level for the specific particle size. Furthermore this raises the question of whether this particle deflection is caused only by the ARF as adopted so far or by the ASF or the sum of both forces. To investigate this fact a 0% - 24% saline solution was used and thus the mismatch between the compressibility of the PS particle and the working fluid could be changed. Therefore it is possible to change the relative strength between ARF and ASF and consequently the particle deflection. We observed a decreasing in the particle deflection for an increased NaCl content up to a 12% saline solution and subsequently an increasing of the particle deflection. Our observation could be explained by the acoustic contrast factor Φ, which depends on the compressibility mismatch. The compressibility of water is increased by the NaCl and the range of a 0% - 24% saline solution covers the PS particle compressibility. Hence the particle deflection reaches a minimum value for the accordance between compressibility of PS particle and saline solution. This minimum value can be estimated as the particle deflection only caused by the ASF. Knowing the particle deflection due to the ASF the particle deflection caused by the ARF can be calculated and thus finally the relation between both forces. Concluding, the particle deflection and therefore the size selective particle separation generated by a tSAW can be achieved for values κ < 1, simplifying actual setups by adjusting the electrical power level. Beyond we studied for the first time the relative strength between ARF and ASF to characterise the particle deflection in a microchannel.

Keywords: ARF, ASF, particle separation, saline solution, tSAW

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Authors: Lanlan Xiao, Yang Liu, Shuo Chen, Bingmei Fu

Abstract:

Most cancer-related deaths are due to metastasis. Metastasis is a complex, multistep processes including the detachment of cancer cells from the primary tumor and the migration to distant targeted organs through blood and/or lymphatic circulations. During hematogenous metastasis, the emigration of tumor cells from the blood stream through the vascular wall into the tissue involves arrest in the microvasculature, adhesion to the endothelial cells forming the microvessel wall and transmigration to the tissue through the endothelial barrier termed as extravasation. The narrow slit between endothelial cells that line the microvessel wall is the principal pathway for tumor cell extravasation to the surrounding tissue. To understand this crucial step for tumor hematogenous metastasis, we used Dissipative Particle Dynamics method to investigate an individual cell passing through a narrow slit numerically. The cell membrane was simulated by a spring-based network model which can separate the internal cytoplasm and surrounding fluid. The effects of the cell elasticity, cell shape and cell surface area increase, and slit size on the cell transmigration through the slit were investigated. Under a fixed driven force, the cell with higher elasticity can be elongated more and pass faster through the slit. When the slit width decreases to 2/3 of the cell diameter, the spherical cell becomes jammed despite reducing its elasticity modulus by 10 times. However, transforming the cell from a spherical to ellipsoidal shape and increasing the cell surface area only by 3% can enable the cell to pass the narrow slit. Therefore the cell shape and surface area increase play a more important role than the cell elasticity in cell passing through the narrow slit. In addition, the simulation results indicate that the cell migration velocity decreases during entry but increases during exit of the slit, which is qualitatively in agreement with the experimental observation.

Keywords: dissipative particle dynamics, deformability, surface area increase, cell migration

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Authors: J. Joel Bright, P. Peer Mohamed, M. Aswin SAangameshwaran

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The increasing usage of concrete produces 80% of carbon dioxide in the atmosphere. Hence, this results in various environmental effects like global warming. The amount of the carbon dioxide released during the manufacture of OPC due to the calcination of limestone and combustion of fossil fuel is in the order of one ton for every ton of OPC produced. Hence, to minimize this Geo Polymer Concrete was introduced. Geo polymer concrete is produced with 0% cement, and hence, it is eco-friendly and it also uses waste product from various industries like thermal power plant, steel manufacturing plant, and paper waste materials. This research is mainly about using Geo polymer concrete for pavement which gives very high strength than conventional concrete and at the same time gives way for sustainable development.

Keywords: activator solution, GGBS, fly ash, metakaolin

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Authors: Alejandra Letelier, Anja Heilmann, Richard G. Watt, Stephen Jivraj, Georgios Tsakos

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Background: Socioeconomic position (SEP) influences adult health. People who experienced material disadvantages in childhood or adulthood tend to have higher adult disease levels than their peers from more advantaged backgrounds. Even so, life is a dynamic process and contains a series of transitions that could lead people through different socioeconomic paths. Research on social mobility takes this into account by adopting a trajectory approach, thereby providing a long-term view of the effect of SEP on health. Aim: The aim of this research examines the effects of intergenerational social mobility on adult general health, oral health and functioning in a population aged 50 and over in England. Methods: This study is based on the secondary analysis of data from the English Longitudinal Study of Ageing (ELSA). Using cross-sectional data, nine social trajectories were created based on parental and adult occupational socio-economic position. Regression models were used to estimate the associations between social trajectories and the following outcomes: adult self-rated health, self-rated oral health, oral health related quality of life, total tooth loss and grip strength; while controlling for socio-economic background and health related behaviours. Results: Associations with adult SEP were generally stronger than with childhood SEP, suggesting a stronger influence of proximal rather than distal SEP on health and oral health. Compared to the stable high group, being in the low SEP groups in childhood and adulthood was associated with poorer health and oral health for all examined outcome measures. For adult self-rated health and edentulousness, graded associations with social mobility trajectories were observed. Conclusion: Intergenerational social mobility was associated with self-rated health and total tooth loss. Compared to only those who remained in a low SEP group over time reported worse self-rated oral health and oral health related quality of life, and had lower grip strength measurements. Potential limitations in relation to data quality will be discussed.

Keywords: social determinants of oral health, social mobility, socioeconomic position and oral health, older adults oral health

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Authors: Maryam Parsian, Pelin Mutlu, Ufuk Gunduz

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Two-dimensional cell culture affords simplicity and low cost, but it has serious limitations; lacking cell-cell and cell-matrix interactions that are present in tissues. Cancer cells grown in 3D culture systems have distinct phenotypes of adhesion, growth, migration, invasion as well as profiles of gene and protein expression. These interactions cause the 3D-cultured cells to acquire morphological and cellular characteristics relevant to in vivo tumors. Palbociclib is a chemotherapeutic agent for the treatment of ER-positive and HER-negative metastatic breast cancer. Poly-amidoamine (PAMAM) dendrimer is a well-defined, special three-dimensional structure and has a multivalent surface and internal cavities that can play an essential role in drug delivery systems. In this study, palbociclib is loaded onto the magnetic PAMAM dendrimer. Hanging droplet method was used in order to form 3D spheroids. The possible toxic effects of both free drug and drug loaded nanoparticles were evaluated in 2D and 3D MCF-7, MD-MB-231 and SKBR-3 breast cancer cell culture models by performing MTT cell viability and Alamar Blue assays. MTT analysis was performed with six different doses from 1000 µg/ml to 25 µg/ml. Drug unloaded PAMAM dendrimer did not demonstrate significant toxicity on all breast cancer cell lines. The results showed that 3D spheroids are clearly less sensitive than 2D cell cultures to free palbociclib. Also, palbociclib loaded PAMAM dendrimers showed more toxic effect than free palbociclib in all cell lines at 2D and 3D cultures. The results suggest that the traditional cell culture method (2D) is insufficient for mimicking the actual tumor tissue. The response of the cancer cells to anticancer drugs is different in the 2D and 3D culture conditions. This study showed that breast cancer cells are more resistant to free palbociclib in 3D cultures than in 2D cultures. However, nanoparticle loaded drugs can be more cytotoxic when compared to free drug.

Keywords: 2D and 3D cell culture, breast cancer, palbociclibe, PAMAM magnetic nanoparticles

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Authors: Komal Vig

Abstract:

Cardiovascular disease (CVD)-related deaths occur in 17.3 million people globally each year, accounting for 30% of all deaths worldwide, with a predicted annual incidence of deaths to reach 23.3 million globally by 2030. Autologous bypass grafts remain an important therapeutic option for the treatment of CVD, but the poor quality of the donor patient’s blood vessels, the invasiveness of the resection surgery, and postoperative movement restrictions create issues. The present study is aimed to improve the endothelialization of intimal surface of graft by using low temperature plasma (LTP) to increase the cell attachment and proliferation. Polytetrafluoroethylene (PTFE) was treated with LTP. Air was used as the feed-gas, and the pressure in the plasma chamber was kept at 800 mTorr. Scaffolds were also modified with gelatin and collagen by dipping method. Human umbilical vein endothelial cells (HUVEC) were plated on the developed scaffolds, and cell proliferation was determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay and by microscopy. mRNA expressions levels of different cell markers were investigated using quantitative real-time PCR (qPCR). XPS confirmed the introduction of oxygenated functionalities from LTP. HUVEC cells showed 80% seeding efficiency on the scaffold. Microscopic and MTT assays indicated increase in cell viability in LTP treated scaffolds, especially when treated with gelatin or collagen, compared to untreated scaffolds. Gene expression studies shows enhanced expression of cell adhesion marker Integrin- α 5 gene after LTP treatment. LTP treated scaffolds exhibited better cell proliferation and viability compared to untreated scaffolds. Protein treatment of scaffold increased cell proliferation. Based on our initial results, more scaffolds alternatives will be developed and investigated for cell growth and vascularization studies. Acknowledgments: This work is supported by the NSF EPSCoR RII-Track-1 Cooperative Agreement OIA-2148653.

Keywords: LTP, HUVEC cells, vascular graft, endothelialization

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Authors: Mina Iskander, Mina Melad, Mourad Yasser, Waleed Abdel Rahim, Amr Mosa, Mohamed El Lahamy, Ezzeldin Sayed-Ahmed, Mohamed Abou-Zeid

Abstract:

Strengthening of reinforced concrete beams in flexure using externally bonded composite laminate of high tensile strength is easy and of the minimum cost compared to traditional methods such as increasing the concrete section depth or reinforcement that requires formwork and curing which affect the structure usability. One of the main limitations of this technique is debonding of the externally bonded laminate, either by end delamination or by mid-span flexural crack-induced debonding. ACI 440.2-08 suggests that using side-bonded FRP laminate in the flexural strengthening of RC beams may serve to limit the extent and width of flexural cracks. Consequently, this technique may decrease the effect of flexural cracks on initiating the mid-span debonding; i.e. delays the flexural crack-induced debonding. Furthermore, bonding the FRP strips to the side of the beam may offer an attractive, practical solution when the soffit of this beam is not accessible. This paper presents an experimental programme designed to investigate the effect of using externally bonded CFRP laminate on the sides of reinforced concrete beams and compares the results to those of bonding the CFRP laminate to the soffit of the beams. In addition, the paper discusses the effect of using end anchorage by U-wrapping the CFRP strips at their end zones with CFRP sheets for beams strengthened with soffit-bonded and side-bonded CFRP strips. Thus, ten rectangular reinforced concrete beams were tested to failure in order to study the effect of changing the location of the externally bonded laminate on the flexural capacity and ductility of the strengthened beams. Pultruded CFRP strips were bonded to the soffit of the beams or their sides to check the possibility of limiting the flexural cracking in mid-span region, which is the main reason for mid-span debonding. Pre-peg CFRP sheets were used near the support as U-wrap for the beam to act as an end-anchorage for the externally bonded strips in order to delay/prevent the end delamination. Strength gains of 38% and 43% were recorded for the soffit-bonded and the side-bonded composite strips with end U-wrapped sheets, respectively. Furthermore, beams with end sheets applied as an end anchorage showed higher ductility than those without these sheets.

Keywords: flexural strengthening, externally bonded CFRP, side-bonded CFRP, CFRP laminates

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Authors: Ahlam H. Mahmoud, Samir F. Zohny, Ibrahim H. Boraia, Faten S. Bayoumic, Eman Eissa

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Hepatocellular carcinoma is one of the most common cancers worldwide and is known to be resistant to conventional chemotherapy. Therefore, we aimed to assess the Salsola inermis extract as a novel chemopreventive and/or therapeutic agent against N-nitrosodiethylamine (DNE)/phenobarbital (PB)-induced hepatocarcinogenesis in rats. Adult male Wistar albino rats were divided into five groups: group1 rats were served as normal controls; group 2 rats were injected intraperitoneally with S. inermis extract (100 mg/kg body weight/day) for 20 weeks; group 3 rats were subjected to two-phase hepatocarcinogenic regimen (initiation of hepatocarcinogenesis was performed by a single intraperitoneal injection of DEN at a dose of 200 mg/kg body weight, 2 weeks later, the carcinogenic effect was promoted by supplementation of rats with 0.05% PB for 16 weeks); group 4 rats were injected intraperitoneally with S. inermis extract 2 weeks prior to the injection of DEN, the daily injection of S. inermis extract was then continued for 18 weeks along with two-phase hepatocarcinogenic regimen (chemoprevention group); and group 5 rats were subjected to the two-phase hepatocarcinogenic regimen, and then, the animals were injected intraperitoneally with S. inermis extract for 4 weeks (treatment group). The activities of serum liver enzymes and levels of total bilirubin, conjugated bilirubin, α-fetoprotein, vascular endothelial growth factor (VEGF) and soluble intercellular adhesion molecule-1 (sICAM-1) in serum were decreased in chemopreventive and treated rats compared with DEN/PB-administered rats. Interestingly, the serum levels of total protein and albumin were normalized in chemopreventive and treated rats. Moreover, the majority of chemopreventive and treated rats showed an almost normal histological pattern of liver. In conclusion, S. inermis extract possessed chemopreventive and therapeutic activities against hepatocarcinogenesis in rats partially through the inhibition of VEGF and sICAM-1.

Keywords: Salsola inermis extract, hepatocarcinogenesis, α–fetoprotein, VEGF, sICAM-1

Procedia PDF Downloads 357