145 research outputs found

    Influence of Ultraviolet Radiation Exposure Time on Styrene-Ethylene-Butadiene-Styrene (SEBS) Copolymer

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    [EN] The effect of ultraviolet radiation on styrene-ethylene-butadiene-styrene (SEBS) has been studied at different exposures times in order to obtain a better understanding of the mechanism of ageing. The polymer materials were mechanically tested and then their surfaces were analyzed using a scanning electron microscope (SEM) and atomic force microscopy (AFM). Moreover, the optical analysis of contact angle (OCA) was used to evaluate the surface energy (gamma(s)) and the yellowing index (YI) and attenuated total reflectance infrared spectroscopy (ATR-FTIR) were used to observe structural and physical changes in aging SEBS. The results obtained for the SEBS, in relation to the duration of exposure, showed superficial changes that cause a decrease in the surface energy (gamma(s)) and, therefore, a decrease in surface roughness. This led to a reduction in mechanical performance, decreasing the tensile strength by about 50% for exposure times of around 200 hours.This work was supported by the Ministry of Economy and Competitiveness (MINECO) grant number MAT2017-84909-C2-2-R). Daniel Garcia-Garcia acknowledges Generalitat Valenciana (GVA) for financial support through a postdoctoral contract (APOSTD/2019/201).Garcia-Garcia, D.; Crespo, J.; Parres, F.; Samper, M. (2020). Influence of Ultraviolet Radiation Exposure Time on Styrene-Ethylene-Butadiene-Styrene (SEBS) Copolymer. Polymers. 12(4):1-14. https://doi.org/10.3390/polym12040862S114124Picchioni, F., Giorgi, I., Passaglia, E., Ruggeri, G., & Aglietto, M. (2001). Blending of styrene-block-butadiene-block-styrene copolymer with sulfonated vinyl aromatic polymers. Polymer International, 50(6), 714-721. doi:10.1002/pi.692Zhu, J., Birgisson, B., & Kringos, N. (2014). Polymer modification of bitumen: Advances and challenges. European Polymer Journal, 54, 18-38. doi:10.1016/j.eurpolymj.2014.02.005Gupta, S., Chandra, T., Sikder, A., Menon, A., & Bhowmick, A. K. (2008). Accelerated weathering behavior of poly(phenylene ether)-based TPE. Journal of Materials Science, 43(9), 3338-3350. doi:10.1007/s10853-008-2484-6Mamodia, M., Indukuri, K., Atkins, E. T., De Jeu, W. H., & Lesser, A. J. (2008). Hierarchical description of deformation in block copolymer TPEs. Journal of Materials Science, 43(22), 7035-7046. doi:10.1007/s10853-008-3030-2Allen, N. S., Edge, M., Wilkinson, A., Liauw, C. M., Mourelatou, D., Barrio, J., & Martı́nez-Zaporta, M. A. (2000). Degradation and stabilisation of styrene–ethylene–butadiene–styrene (SEBS) block copolymer. Polymer Degradation and Stability, 71(1), 113-122. doi:10.1016/s0141-3910(00)00162-2Costa, P., Ribeiro, S., Botelho, G., Machado, A. V., & Lanceros Mendez, S. (2015). Effect of butadiene/styrene ratio, block structure and carbon nanotube content on the mechanical and electrical properties of thermoplastic elastomers after UV ageing. Polymer Testing, 42, 225-233. doi:10.1016/j.polymertesting.2015.02.002Tomacheski, D., Pittol, M., Lopes, A. P. M., Simões, D. N., Ribeiro, V. F., & Santana, R. M. C. (2017). Effects of Weathering on Mechanical, Antimicrobial Properties and Biodegradation Process of Silver Loaded TPE Compounds. Journal of Polymers and the Environment, 26(1), 73-82. doi:10.1007/s10924-016-0927-8Singh, B., & Sharma, N. (2008). Mechanistic implications of plastic degradation. Polymer Degradation and Stability, 93(3), 561-584. doi:10.1016/j.polymdegradstab.2007.11.008White, C. C., Tan, K. T., Hunston, D. L., Nguyen, T., Benatti, D. J., Stanley, D., & Chin, J. W. (2011). Laboratory accelerated and natural weathering of styrene–ethylene–butylene–styrene (SEBS) block copolymer. Polymer Degradation and Stability, 96(6), 1104-1110. doi:10.1016/j.polymdegradstab.2011.03.003Allen, N. (2004). Photooxidation of styrene–ethylene–butadiene–styrene (SEBS) block copolymer. Journal of Photochemistry and Photobiology A: Chemistry, 162(1), 41-51. doi:10.1016/s1010-6030(03)00311-3Flaris, V., & Stachurski, Z. H. (1992). The effects of processing on the mechanical properties of a polyolefin blend. Polymer International, 27(3), 267-273. doi:10.1002/pi.4990270312Li, Y., Li, L., Zhang, Y., Zhao, S., Xie, L., & Yao, S. (2009). Improving the aging resistance of styrene-butadiene-styrene tri-block copolymer and application in polymer-modified asphalt. Journal of Applied Polymer Science, n/a-n/a. doi:10.1002/app.31458Xu, X., Yu, J., Xue, L., Zhang, C., He, B., & Wu, M. (2017). Structure and performance evaluation on aged SBS modified bitumen with bi- or tri-epoxy reactive rejuvenating system. 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S., Sutcliffe, M. P. F., & Tavakoli, S. M. (2001). Ageing of adhesively bonded joints—fracture and failure analysis using video imaging techniques. International Journal of Adhesion and Adhesives, 21(6), 455-463. doi:10.1016/s0143-7496(01)00022-7Komvopoulos, K. (2003). Adhesion and friction forces in microelectromechanical systems: mechanisms, measurement, surface modification techniques, and adhesion theory. Journal of Adhesion Science and Technology, 17(4), 477-517. doi:10.1163/15685610360554384Pijpers, A. ., & Meier, R. J. (2001). Adhesion behaviour of polypropylenes after flame treatment determined by XPS(ESCA) spectral analysis. Journal of Electron Spectroscopy and Related Phenomena, 121(1-3), 299-313. doi:10.1016/s0368-2048(01)00341-3Yu, S., Hu, H., Zhang, Y., & Liu, Y. (2008). Effect of transfer film on tribological behavior of polyamide 66-based binary and ternary nanocomposites. Polymer International, 57(3), 454-462. doi:10.1002/pi.2337Żenkiewicz, M. (2007). Comparative study on the surface free energy of a solid calculated by different methods. Polymer Testing, 26(1), 14-19. doi:10.1016/j.polymertesting.2006.08.005Kumar, S., & Misra, R. K. (2007). Analysis of Banana Fibers Reinforced Low‐density Polyethylene/Poly(Є‐caprolactone) Composites. Soft Materials, 4(1), 1-13. doi:10.1080/15394450600823040Fowkes, F. ., McCarthy, D. ., & Mostafa, M. . (1980). Contact angles and the equilibrium spreading pressures of liquids on hydrophobic solids. Journal of Colloid and Interface Science, 78(1), 200-206. doi:10.1016/0021-9797(80)90508-1Owens, D. K., & Wendt, R. C. (1969). Estimation of the surface free energy of polymers. Journal of Applied Polymer Science, 13(8), 1741-1747. doi:10.1002/app.1969.070130815Zhao, Y., Tang, S., Myung, S.-W., Lu, N., & Choi, H.-S. (2006). Effect of washing on surface free energy of polystyrene plate treated by RF atmospheric pressure plasma. Polymer Testing, 25(3), 327-332. doi:10.1016/j.polymertesting.2005.12.007Hänni‐Ciunel, K., Findenegg, G. H., & von Klitzing, R. (2007). Water Contact Angle On Polyelectrolyte‐Coated Surfaces: Effects of Film Swelling and Droplet Evaporation. Soft Materials, 5(2-3), 61-73. doi:10.1080/15394450701554452Radovanovic, E., Carone, E., & Gonçalves, M. . (2004). Comparative AFM and TEM investigation of the morphology of nylon6-rubber blends. Polymer Testing, 23(2), 231-237. doi:10.1016/s0142-9418(03)00099-0Drnovská, H., Lapčík, L., Buršíková, V., Zemek, J., & Barros-Timmons, A. M. (2003). Surface properties of polyethylene after low-temperature plasma treatment. Colloid and Polymer Science, 281(11), 1025-1033. doi:10.1007/s00396-003-0871-8Lehocký, M., Drnovská, H., Lapčı́ková, B., Barros-Timmons, A. ., Trindade, T., Zembala, M., & Lapčı́k, L. (2003). Plasma surface modification of polyethylene. 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    Comparison of Mechanical Properties of Hemp-Fibre Biocomposites Fabricated with Biobased and Regular Epoxy Resins

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    [EN] Bio- and green composites are mainly used in non-structural automotive elements like interior panels and vehicle underpanels. Currently, the use of biocomposites as a worthy alternative to glass fibre-reinforced plastics (GFRPs) in structural applications still needs to be fully evaluated. In the current study, the development of a suited biocomposites started with a thorough review of the available raw materials, including both reinforcement fibres and matrix materials. Based on its specific properties, hemp appeared to be a very suitable fibre. A similar analysis was conducted for the commercially available biobased matrix materials. Greenpoxy 55 (with a biocontent of 55%) and Super Sap 100 (with a biocontent of 37%) were selected and compared with a standard epoxy resin. Tensile and three-point bending tests were conducted to characterise the hemp-based biocomposite.The authors acknowledge financial support from the Spanish Government, Project PID2019-108807RB-I00.Colomer Romero, V.; Rogiest, D.; García Manrique, JA.; Crespo, J. (2020). Comparison of Mechanical Properties of Hemp-Fibre Biocomposites Fabricated with Biobased and Regular Epoxy Resins. Materials. 13(24):1-8. https://doi.org/10.3390/ma13245720181324Mohanty, A. K., Misra, M., & Hinrichsen, G. (2000). Biofibres, biodegradable polymers and biocomposites: An overview. Macromolecular Materials and Engineering, 276-277(1), 1-24. doi:10.1002/(sici)1439-2054(20000301)276:13.0.co;2-wLa Mantia, F. P., & Morreale, M. (2011). Green composites: A brief review. Composites Part A: Applied Science and Manufacturing, 42(6), 579-588. doi:10.1016/j.compositesa.2011.01.017Hansen, O., Habermann, C., & Endres, H.-J. (2019). BIO-BASED MATERIALS FOR EXTERIOR APPLICATIONS – PROJECT BIOHYBRIDCAR. Zukunftstechnologien für den multifunktionalen Leichtbau, 189-200. doi:10.1007/978-3-662-58206-0_18Gholampour, A., & Ozbakkaloglu, T. (2019). A review of natural fiber composites: properties, modification and processing techniques, characterization, applications. Journal of Materials Science, 55(3), 829-892. doi:10.1007/s10853-019-03990-yPatil, N. V., Rahman, M. M., & Netravali, A. N. (2017). «Green» composites using bioresins from agro‐wastes and modified sisal fibers. Polymer Composites, 40(1), 99-108. doi:10.1002/pc.24607Verma, D., & Senal, I. (2019). Natural fiber-reinforced polymer composites. Biomass, Biopolymer-Based Materials, and Bioenergy, 103-122. doi:10.1016/b978-0-08-102426-3.00006-0Adekomaya, O. (2020). Adaption of green composite in automotive part replacements: discussions on material modification and future patronage. Environmental Science and Pollution Research, 27(8), 8807-8813. doi:10.1007/s11356-019-07557-xKim, Y. K., & Chalivendra, V. (2020). Natural fibre composites (NFCs) for construction and automotive industries. Handbook of Natural Fibres, 469-498. doi:10.1016/b978-0-12-818782-1.00014-6Potluri, R., & Chaitanya Krishna, N. (2020). Potential and Applications of Green Composites in Industrial Space. Materials Today: Proceedings, 22, 2041-2048. doi:10.1016/j.matpr.2020.03.218Mann, G. S., Singh, L. P., Kumar, P., & Singh, S. (2018). Green composites: A review of processing technologies and recent applications. Journal of Thermoplastic Composite Materials, 33(8), 1145-1171. doi:10.1177/0892705718816354Standard Test Method for Tensile Properties of Polymer Matrix Composite Materials https://www.astm.org/Standards/D3039https://www.pecepoxy.co.uk/data-sheets/TDS_100_1000_v4.pdfhttp://www.matrix-composites.co.uk/prod-data-sheet/old/greenpoxy-55-ft-uk.pdfCzłonka, S., Strąkowska, A., & Kairytė, A. (2020). The Impact of Hemp Shives Impregnated with Selected Plant Oils on Mechanical, Thermal, and Insulating Properties of Polyurethane Composite Foams. Materials, 13(21), 4709. doi:10.3390/ma13214709Madhu, P., Mavinkere Rangappa, S., Khan, A., Al Otaibi, A., Al‐Zahrani, S. A., Pradeep, S., … Siengchin, S. (2020). Experimental investigation on the mechanical and morphological behavior of Prosopis juliflora bark fibers/E‐glass/carbon fabrics reinforced hybrid polymeric composites for structural applications. Polymer Composites, 41(12), 4983-4993. doi:10.1002/pc.2576

    Academic competence, teacher–student relationship, and violence and victimisation in adolescents: The classroom climate as a mediator

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    School violence is a serious social and public health problem prevalent worldwide. Alt-hough the relevance of teacher and classroom factors is well established in the literature, few studies have focused on the role of teacher perceptions in school violence and victimisation and the poten-tial mediational role of classroom climate in this relationship. A total of 2399 adolescents (50% girls), aged between 11 and 18 years (M = 14.65, SD = 1.78) and enrolled in five Spanish Secondary Com-pulsory Education schools completed measures of classroom climate, school violence towards peers and perception of peer victimisation, and their teachers informed about their academic competence and the teacher–student relationship. Correlational analyses revealed that whereas academic competence perceived by the teacher was negatively related to overt violence and victimisation, its relationship with pure relational violence was positive. Structural equation modelling analyses showed that variables of classroom climate (involvement, affiliation, and teacher support) perceived by the students functioned as partial mediators between teacher perceptions of academic competence and of teacher–student relationship and violence and victimisation. In the mediational model, teacher perception of academic competence acted as a direct protective factor against violence and victimisation, and teacher perception of teacher–student relationship acted as a direct risk for violence, as well as an indirect protective factor through classroom climate for victimisation. The interpretation of these results points to the importance of the teacher’s subjective perceptions in the prevention of violence and victimisation problems and their practical implications for the classroom climate perceived by students

    Applying an experimental design to improve the manufacturing process and properties of a novel sound absorber with recycled fibres from End-of-Life-Tyres

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    [EN] The present work analyses the acoustic properties of acoustic absorbent textile products obtained from the thermo-compression of recycled End-of-Life Tyres. The objective is to obtain products of greater added value from the waste of End-of-Life Tyres, which can become a substitute for the fibrous materials currently used as acoustic absorbents. Experimental design was used to determine the number of samples to be prepared and the manufacturing conditions to maximise acoustic absorption. Five factors were taken into account: material type, temperature, time, weight and compaction factor. The obtained results demonstrate the validity of the experimental design to select the manufacturing factors in order to improve the sound absorption of these textile waste products.Segura Alcaraz, JG.; Zamorano Cantó, M.; Miró Martínez, P.; Nadal Gisbert, AV.; Crespo, J. (2020). Applying an experimental design to improve the manufacturing process and properties of a novel sound absorber with recycled fibres from End-of-Life-Tyres. Journal of Industrial Textiles (Online). 50(1):13-22. https://doi.org/10.1177/1528083718819876S1322501Santini, A., Morselli, L., Passarini, F., Vassura, I., Di Carlo, S., & Bonino, F. (2011). End-of-Life Vehicles management: Italian material and energy recovery efficiency. Waste Management, 31(3), 489-494. doi:10.1016/j.wasman.2010.09.015Sienkiewicz, M., Kucinska-Lipka, J., Janik, H., & Balas, A. (2012). Progress in used tyres management in the European Union: A review. Waste Management, 32(10), 1742-1751. doi:10.1016/j.wasman.2012.05.010Bartl, A., Hackl, A., Mihalyi, B., Wistuba, M., & Marini, I. (2005). Recycling of Fibre Materials. Process Safety and Environmental Protection, 83(4), 351-358. doi:10.1205/psep.04392Maderuelo-Sanz, R., Nadal-Gisbert, A. V., Crespo-Amorós, J. E., & Parres-García, F. (2012). A novel sound absorber with recycled fibers coming from end of life tires (ELTs). Applied Acoustics, 73(4), 402-408. doi:10.1016/j.apacoust.2011.12.001Jimenez-Espadafor, F. J., Becerra Villanueva, J. A., García, M. T., Trujillo, E. C., & Blanco, A. M. (2011). Optimal design of acoustic material from tire fluff. Materials & Design, 32(6), 3608-3616. doi:10.1016/j.matdes.2011.02.024Parres, F., Crespo-Amorós, J. E., Nadal-Gisbert, A., & Navarro, R. (2012). Mechanical and Thermal Properties Analysis of Polypropylene Reinforced with Polyamide Microfibre Obtained from Shredded Tyres. Polymers and Polymer Composites, 20(9), 817-822. doi:10.1177/096739111202000907Maderuelo-Sanz, R., Martín-Castizo, M., & Vílchez-Gómez, R. (2011). The performance of resilient layers made from recycled rubber fluff for impact noise reduction. Applied Acoustics, 72(11), 823-828. doi:10.1016/j.apacoust.2011.05.004Castagnède, B., Aknine, A., Brouard, B., & Tarnow, V. (2000). Effects of compression on the sound absorption of fibrous materials. Applied Acoustics, 61(2), 173-182. doi:10.1016/s0003-682x(00)00003-7Lou, C.-W., Lin, J.-H., & Su, K.-H. (2005). Recycling Polyester and Polypropylene Nonwoven Selvages to Produce Functional Sound Absorption Composites. Textile Research Journal, 75(5), 390-394. doi:10.1177/0040517505054178Seddeq, H. S., Aly, N. M., Marwa A, A., & Elshakankery, M. (2012). Investigation on sound absorption properties for recycled fibrous materials. Journal of Industrial Textiles, 43(1), 56-73. doi:10.1177/1528083712446956Sun, Z., Shen, Z., Ma, S., & Zhang, X. (2013). Novel Application of Glass Fibers Recovered From Waste Printed Circuit Boards as Sound and Thermal Insulation Material. Journal of Materials Engineering and Performance, 22(10), 3140-3146. doi:10.1007/s11665-013-0587-yRushforth, I. M., Horoshenkov, K. V., Miraftab, M., & Swift, M. J. (2005). Impact sound insulation and viscoelastic properties of underlay manufactured from recycled carpet waste. Applied Acoustics, 66(6), 731-749. doi:10.1016/j.apacoust.2004.10.00

    Panels of eco-friendly materials for architectural acoustics

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    [EN] The objective of this work is to study the acoustic and mechanical properties of environmentally friendly materials manufactured through the process of resin infusion made from different types of fibres: some are biodegradable obtained from renewable resources and others from recycled textile waste. The materials studied are composed of fibres of jute, hemp, coconut, biaxial linen and textile waste. The modulus of elasticity and the airborne sound insulation are determined through dynamic and acoustic tests, respectively. The behaviour of these innovative materials is compared to some traditional materials commonly used in architectural acoustics. The acoustic study of these environmentally friendly materials is carried out considering them as light elements of a single layer for their application to insulation of walls. The results are compared to plasterboards, considered as the most commonly used light material in buildings for airborne sound insulation. In conclusion, these materials are a real and effective alternative to the traditional composites of synthetic matrices and reinforcements of glass fibres and there is a reduction in the production cost compared to the usual porous synthetic media that have expensive production processes.Fontoba-Ferrándiz, J.; Juliá Sanchis, E.; Crespo, J.; Segura Alcaraz, JG.; Gadea Borrell, JM.; Parres, F. (2020). Panels of eco-friendly materials for architectural acoustics. Journal of Composite Materials. 54(25):3743-3753. https://doi.org/10.1177/0021998320918914S374337535425Yahya, M. N., Sambu, M., Latif, H. A., & Junaid, T. M. (2017). A study of Acoustics Performance on Natural Fibre Composite. IOP Conference Series: Materials Science and Engineering, 226, 012013. doi:10.1088/1757-899x/226/1/012013Putra, A., Or, K. H., Selamat, M. Z., Nor, M. J. M., Hassan, M. H., & Prasetiyo, I. (2018). Sound absorption of extracted pineapple-leaf fibres. Applied Acoustics, 136, 9-15. doi:10.1016/j.apacoust.2018.01.029Dunne, R., Desai, D., & Sadiku, R. (2017). Material characterization of blended sisal-kenaf composites with an ABS matrix. Applied Acoustics, 125, 184-193. doi:10.1016/j.apacoust.2017.03.022Mohanty, A. K., Misra, M., & Hinrichsen, G. (2000). Biofibres, biodegradable polymers and biocomposites: An overview. Macromolecular Materials and Engineering, 276-277(1), 1-24. doi:10.1002/(sici)1439-2054(20000301)276:13.0.co;2-wLuckachan, G. E., & Pillai, C. K. S. (2011). Biodegradable Polymers- A Review on Recent Trends and Emerging Perspectives. Journal of Polymers and the Environment, 19(3), 637-676. doi:10.1007/s10924-011-0317-1Belakroum, R., Gherfi, A., Kadja, M., Maalouf, C., Lachi, M., El Wakil, N., & Mai, T. H. (2018). Design and properties of a new sustainable construction material based on date palm fibers and lime. Construction and Building Materials, 184, 330-343. doi:10.1016/j.conbuildmat.2018.06.196Sèbe, G. (2000). Applied Composite Materials, 7(5/6), 341-349. doi:10.1023/a:1026538107200Yates, M. R., & Barlow, C. Y. (2013). Life cycle assessments of biodegradable, commercial biopolymers—A critical review. Resources, Conservation and Recycling, 78, 54-66. doi:10.1016/j.resconrec.2013.06.010Rouison, D., Sain, M., & Couturier, M. (2006). Resin transfer molding of hemp fiber composites: optimization of the process and mechanical properties of the materials. Composites Science and Technology, 66(7-8), 895-906. doi:10.1016/j.compscitech.2005.07.040Sreekumar, P. A., Joseph, K., Unnikrishnan, G., & Thomas, S. (2007). A comparative study on mechanical properties of sisal-leaf fibre-reinforced polyester composites prepared by resin transfer and compression moulding techniques. Composites Science and Technology, 67(3-4), 453-461. doi:10.1016/j.compscitech.2006.08.025Rassmann, S., Reid, R. G., & Paskaramoorthy, R. (2010). Effects of processing conditions on the mechanical and water absorption properties of resin transfer moulded kenaf fibre reinforced polyester composite laminates. Composites Part A: Applied Science and Manufacturing, 41(11), 1612-1619. doi:10.1016/j.compositesa.2010.07.009Vijay, R., & Singaravelu, D. L. (2016). Experimental investigation on the mechanical properties ofCyperus pangoreifibers and jute fiber-based natural fiber composites. International Journal of Polymer Analysis and Characterization, 21(7), 617-627. doi:10.1080/1023666x.2016.1192354Williams, G. I. (2000). Applied Composite Materials, 7(5/6), 421-432. doi:10.1023/a:1026583404899O’Donnell, A., Dweib, M. ., & Wool, R. . (2004). Natural fiber composites with plant oil-based resin. Composites Science and Technology, 64(9), 1135-1145. doi:10.1016/j.compscitech.2003.09.024Tran, P., Graiver, D., & Narayan, R. (2006). Biocomposites synthesized from chemically modified soy oil and biofibers. Journal of Applied Polymer Science, 102(1), 69-75. doi:10.1002/app.22265Liu, Q., & Hughes, M. (2008). The fracture behaviour and toughness of woven flax fibre reinforced epoxy composites. Composites Part A: Applied Science and Manufacturing, 39(10), 1644-1652. doi:10.1016/j.compositesa.2008.07.008Scarponi, C., Pizzinelli, C. S., Sánchez-Sáez, S., & Barbero, E. (2009). Impact Load Behaviour of Resin Transfer Moulding (RTM) Hemp Fibre Composite Laminates. Journal of Biobased Materials and Bioenergy, 3(3), 298-310. doi:10.1166/jbmb.2009.1040Dahy, H. (2017). Biocomposite materials based on annual natural fibres and biopolymers – Design, fabrication and customized applications in architecture. Construction and Building Materials, 147, 212-220. doi:10.1016/j.conbuildmat.2017.04.079Saba, N., Paridah, M. T., & Jawaid, M. (2015). Mechanical properties of kenaf fibre reinforced polymer composite: A review. Construction and Building Materials, 76, 87-96. doi:10.1016/j.conbuildmat.2014.11.043Senthilkumar, K., Saba, N., Rajini, N., Chandrasekar, M., Jawaid, M., Siengchin, S., & Alotman, O. Y. (2018). Mechanical properties evaluation of sisal fibre reinforced polymer composites: A review. Construction and Building Materials, 174, 713-729. doi:10.1016/j.conbuildmat.2018.04.143Alves, C., Ferrão, P. M. C., Silva, A. J., Reis, L. G., Freitas, M., Rodrigues, L. B., & Alves, D. E. (2010). Ecodesign of automotive components making use of natural jute fiber composites. Journal of Cleaner Production, 18(4), 313-327. doi:10.1016/j.jclepro.2009.10.022Van Vuure, A. W., Baets, J., Wouters, K., & Hendrickx, K. (2015). Compressive properties of natural fibre composites. Materials Letters, 149, 138-140. doi:10.1016/j.matlet.2015.01.158Galan-Marin, C., Rivera-Gomez, C., & Garcia-Martinez, A. (2016). Use of Natural-Fiber Bio-Composites in Construction versus Traditional Solutions: Operational and Embodied Energy Assessment. Materials, 9(6), 465. doi:10.3390/ma9060465Bogoeva-Gaceva, G., Avella, M., Malinconico, M., Buzarovska, A., Grozdanov, A., Gentile, G., & Errico, M. E. (2007). Natural fiber eco-composites. Polymer Composites, 28(1), 98-107. doi:10.1002/pc.20270Peng, L., Song, B., Wang, J., & Wang, D. (2015). Mechanic and Acoustic Properties of the Sound-Absorbing Material Made from Natural Fiber and Polyester. Advances in Materials Science and Engineering, 2015, 1-5. doi:10.1155/2015/274913Benfratello, S., Capitano, C., Peri, G., Rizzo, G., Scaccianoce, G., & Sorrentino, G. (2013). Thermal and structural properties of a hemp–lime biocomposite. Construction and Building Materials, 48, 745-754. doi:10.1016/j.conbuildmat.2013.07.096Adekomaya, O., Jamiru, T., Sadiku, R., & Huan, Z. (2015). A review on the sustainability of natural fiber in matrix reinforcement – A practical perspective. Journal of Reinforced Plastics and Composites, 35(1), 3-7. doi:10.1177/0731684415611974Kadam, A., Pawar, M., Yemul, O., Thamke, V., & Kodam, K. (2015). Biodegradable biobased epoxy resin from karanja oil. Polymer, 72, 82-92. doi:10.1016/j.polymer.2015.07.002Yan, L., Chouw, N., & Jayaraman, K. (2014). Flax fibre and its composites – A review. Composites Part B: Engineering, 56, 296-317. doi:10.1016/j.compositesb.2013.08.014Wambua, P., Ivens, J., & Verpoest, I. (2003). Natural fibres: can they replace glass in fibre reinforced plastics? Composites Science and Technology, 63(9), 1259-1264. doi:10.1016/s0266-3538(03)00096-4Williams, C., Summerscales, J., & Grove, S. (1996). Resin Infusion under Flexible Tooling (RIFT): a review. 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    Personality traits, theory of mind and their relationship with multiple suicide attempts in a sample of first episode psychosis patients: One-year follow-up study

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    BACKGROUND: High rates of suicidal behaviour (SB) have been found in first episode psychosis (FEP) patients. It has been suggested that the presence of multiple suicide attempts (mSA) increases the risk of later SA and the risk of eventual death by suicide. OBJECTIVE: Our main objective was to study the baseline factors associated with the presence of mSA during the first year after FEP. In addition, a second aim was to find out whether there were any differences between single and multiple suicide attempters in the timing of the first SA after FEP. METHOD: A total of 65 FEP patients were evaluated. The presence of SAs were recorded at two different times after FEP. Bivariate and multivariate analyses were performed to explore the relationship between SA with sociodemographic and clinical variables. RESULTS: Multiple linear regression showed that mSA was associated with the presence of increased symptom severity (B?=?0.35; t?=?3.67; p < 0.01) and errors in first-order false-belief task (B?=?0.48; t?=?2.11; p?=?0.04). There were significant differences in the timing of first SA after FEP between multiple and single suicide attempters. CONCLUSIONS: Theory of mind impairments along with more severe symptoms during the first contact with mental health services for psychotic symptoms appeared to be important predictors of mSA. On the other hand, multiple suicide attempters tend to make a first SA after FEP earlier than single suicide attempters. These results could contribute to the implementation of preventive suicidal programs, however they must be confirmed by additional research.Funding: This study was funded by Ministry of Science and Innovation grant ISC PI11/0233

    GD1a modulates GM-CSF-induced cell proliferation

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    AbstractGangliosides have been extensively described to be involved in the proliferation and differentiation of various cell types, such including hematopoietic cells. Our previous studies on murine models of stroma-mediated myelopoiesis have shown that gangliosides are required for optimal capacity of stromal cells to support proliferation of myeloid precursor cells, being shed to the supernatant and selectively incorporated into myeloid cell membranes. Here we describe the effect of gangliosides on the specific granulocyte–macrophage colony-stimulating factor (GM-CSF)-induced proliferation. For that, we used the monocytic FDC-P1 cell line, which is dependent upon GM-CSF for survival and proliferation. Cells were cultured in the presence of GM-CSF and exogenous gangliosides (GM3, GD1a or GM1) or in the absence of endogenous ganglioside synthesis by the use of a ceramide-synthase inhibitor, d-PDMP. We observed that exogenous addition of GD1a enhanced the GM-CSF-induced proliferation of the FDC-P1 cells. Also, we detected an increase in the expression of the α isoform of the GM-CSF receptor (GMRα) as well as of the transcription factor C/EBPα. On the contrary, inhibition of glucosylceramide synthesis was accompanied by a decrease in cell proliferation, which was restored upon the addition of exogenous GD1a. We also show a co-localization of GD1a and GMR by immunocytochemistry. Taken together, our results suggest for the first time that ganglioside GD1a play a role on the modulation of GM-CSF-mediated proliferative response, which might be of great interest not only in hematopoiesis, but also in other immunological processes, Alzheimer disease, alveolar proteinosis and wherever GM-CSF exerts its effects

    El proyecto y construcción de prototipos de laboratorio como medio para el desarrollo de competencias

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    Sanchez-Caballero, S.; Sellés, M.; Crespo, J.; Parres, F.; Pérez Bernabeu, E. (2011). El proyecto y construcción de prototipos de laboratorio como medio para el desarrollo de competencias. Instituto de Ciencias de la Educación de la Universidad de Alicante. 1-10. http://hdl.handle.net/10251/178200S11

    Los problemas en ingeniería

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    [ES] La resolución de problemas constituye una de las facetas educativas que cualquier alumno suele relacionar con las enseñanzas técnicas. Ese reconocimiento suele también identificarse con listas interminables de problemas suministradas por el profesor o incluidas en monografías, en las que el alumno es incapaz de hallar una mínima relación con los problemas que acontecen en su quehacer diario o en la Ciencia real. Las conductas que desencadena en el profesor y en el alumno la resolución de problemas vienen a estar impregnadas de una serie de rutinas descontextualizadas, inalteradas década tras década y que promueven el aprendizaje memorístico más que la oportunidad de indagar en la comprensión del contenido científico. En este trabajo se expone cómo mejorar el proceso de resolución de problemas, y también se exponen indicaciones de como evaluar el aprendizaje.Sellés, M.; Pérez Bernabeu, E.; Sanchez-Caballero, S.; Crespo, J.; Parres, F. (2011). Los problemas en ingeniería. Instituto de Ciencias de la Educación de la Universidad de Alicante. 2317-2325. http://hdl.handle.net/10251/178197S2317232

    Coordinacion entre diferentes areas de conocimiento para el desarrollo de productos de consumo

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    [ES] Las metodologías docentes están evolucionando en los últimos años. Si bien tradicionalmente se basaban en una mera transmisión de conocimientos por parte del profesor, con un alumno pasivo que básicamente se dedicaba a tomar apuntes, en la actualidad, esta situación está cambiando, ya que se están poniendo en marcha nuevas metodologías cuya finalidad es dar al alumno un papel activo, participando en el desarrollo de las clases, y de esta manera desarrollando nuevas aptitudes. En este nuevo panorama docente, donde cada vez hay mayor preocupación por alcanzar el éxito en el proceso de ENSEÑANZA-APRENDIZAJE, en la Escuela Politécnica Superior de Alcoy, se ha puesto en marcha una experiencia piloto en el Bloque de Intensificación de Ocio y Equipamiento de la especialidad Diseño industrial. Esta experiencia consiste en el desarrollo de PROYECTOS INTERDISCIPLINARES donde un grupo de alumnos debe desarrollar un proyecto creativoCrespo, J.; Parres, F.; Sanchez-Caballero, S.; Sellés, M.; Pérez Bernabeu, E. (2011). Coordinacion entre diferentes areas de conocimiento para el desarrollo de productos de consumo. Instituto de Ciencias de la Educación de la Universidad de Alicante. 1771-1781. http://hdl.handle.net/10251/178207S1771178
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