Shaking table testing of an existing masonry building: assessment and improvement of the seismic performance

This paper aims to assess and improve the seismic performance of an existing masonry building with flexible floors, representative of a Portuguese building typology—‘gaioleiro’ buildings. The study involved seismic tests and dynamic identification tests of two models (nonstrengthened and strengthened) in the shaking table. Each model was subjected to several seismic tests with increasing amplitude. . Before the first test and after each seismic test, the dynamic identification of the model was carried out, aiming at obtaining their seismic vulnerability curves based on a damage indicator obtained from the decrease of the frequencies of the modes. In the strengthened model, steel elements were used to improve the connection between walls and floors, together with ties in the upper stories. The results show that adopted strengthening technique is effective for reducing the seismic vulnerability of ‘gaioleiro’ buildings, namely for improving the out-of-plane behavior of the facades.The first author acknowledges the financial support from the Portuguese Foundation for Science and Technology (FCT) through grant SFRH/BD/32190/2006. The work was also supported by the project 'New Integrated Knowledge based approaches to the protection of cultural heritage form Earthquake-induced Risk' (NIKER FP7-ENV-2009-1-224123) from the European Commission

Effect of some biotic factors on microbially-induced calcite precipitation in cement mortar

Sporosarcina pasteurii, a common soil bacterium has been tested for microbial treatment of cement mortar. The present study also seeks to investigate the effects of growth medium, bacterial concentration and different buffers concerning the preparation of bacterial suspensions on the compressive strength of cement mortar. Two growth media, six different suspensions and two bacterial concentrations were used in the study. The influence of growth medium on calcification efficiency of S. pasteurii was insignificant. Significant improvement in the compressive as well as the tensile strength of cement mortar was observed. Microbial mineral precipitation visualized by Scanning Electron Microscopy (SEM) shows fibrous material that increased the strength of cement mortar. Formation of thin strands of fillers observed through SEM micrographs improves the pore structure, impermeability and thus the compressive as well as the tensile strengths of the cement mortar. The type of substrate and its molarity have a significant influence on the strength of cement mortar

A new method to predict optimum cure time of rubber compound using dynamic mechanical analysis

The degree of vulcanization of a rubber compound has a big influence on the properties of the final product. Therefore, precisely defining the curing process including optimum cure time is important to ensure the production of final products having high performance. Typically, vulcanization is represented using vulcanization curves. The main types of equipment used for producing vulcanization curves are the oscillating disc rheometer (ODR) and the moving die rheometer (MDR). These can be used to plot graphs of torque versus time at a constant temperature to show how cure is proceeding. Based on the results obtained, optimum cure time (t₉₀) is calculated as the time required for the torque to reach 90% of the maximum achievable torque. In this study, the use of Dynamic Mechanical Analysis (DMA) for assessment of t₉₀ was assessed. DMA was carried out using shear mode isothermal tests to measure the changes in material properties caused by vulcanization. The results revealed that the shear storage modulus (G′), shear loss modulus (G′′), and tan δ all reflect the vulcanization process, however, tan δ gave the best representation of level of vulcanization. Indeed, the curve of tan δ was able to be used to derive the t₉₀ for rubber compounds and showed good agreement with the results from an MDR

A comparison of flexural strengths of polymer (SBR and PVA) modified, roller compacted concrete

This brief article aims to reveal the flexural performance, including the equivalent flexural strength of PVA (Polyvinyl Alcohol) modified concrete by comparing it primarily with that of SBR (Styrene Butadiene Rubber) concrete. This data article is directly related to Karadelis and Lin [6]

UV Degradation of the Optical Properties of Acrylic for Neutrino and Dark Matter Experiments

UV-transmitting (UVT) acrylic is a commonly used light-propagating material in neutrino and dark matter detectors as it has low intrinsic radioactivity and exhibits low absorption in the detectors' light producing regions, from 350 nm to 500 nm. Degradation of optical transmittance in this region lowers light yields in the detector, which can affect energy reconstruction, resolution, and experimental sensitivities. We examine transmittance loss as a result of short- and long-term UV exposure for a variety of UVT acrylic samples from a number of acrylic manufacturers. Significant degradation peaking at 343 nm was observed in some UVT acrylics with as little as three hours of direct sunlight, while others exhibited softer degradation peaking at 310 nm over many days of exposure to sunlight. Based on their measured degradation results, safe time limits for indoor and outdoor UV exposure of UVT acrylic are formulated.Comment: 13 pages, 6 figures, 3 tables; To be submitted to Journal of Instrumentatio

Influence of liposome encapsulated essential oils on properties of chitosan films

[EN] The effect of the encapsulation of eugenol and cinnamon leaf essential oil (CLEO) in lecithin liposomes on the losses of these compounds during the chitosan film formation process by casting was evaluated. Film-forming dispersions and films with eugenol or CLEO (either free or encapsulated) were obtained and characterized. The content of eugenol in active films was quantified by means of solvent extraction and gas chromatograph analysis. The encapsulation of eugenol or CLEO in lecithin liposomes led to the films retaining 40% −50% of the incorporated eugenol, whereas only 1%−2% was retained when eugenol was incorporated by direct emulsification. Films with liposomes exhibited a lamellar microstructure which improved film extensibility and increased water vapour barrier capacity with respect to those with free emulsified compounds. Liposomes also modified the optical properties of the films, reducing their gloss, increasing colour saturation and making them redder in colour. The encapsulation of volatile active compounds in liposomes appears to be a good strategy for obtaining antimicrobial films with essential oils.The authors acknowledge the financial support provided by the Ministerio de Economía y Competitividad (Project AGL2013-42989-R). Cristina Valencia Sullca thanks the Programa Nacional de Becas del Perú (Pronabec) for the completion of her doctoral thesis.Valencia-Sullca, CE.; Jiménez Serrallé, M.; Jiménez Marco, A.; Atarés Huerta, LM.; Vargas, M.; Chiralt, A. (2016). Influence of liposome encapsulated essential oils on properties of chitosan films. Polymer International (Online). 65(8):979-987. https://doi.org/10.1002/pi.5143S979987658Jiménez, A., Fabra, M. J., Talens, P., & Chiralt, A. (2013). Physical properties and antioxidant capacity of starch–sodium caseinate films containing lipids. Journal of Food Engineering, 116(3), 695-702. doi:10.1016/j.jfoodeng.2013.01.010Zhai, M., Zhao, L., Yoshii, F., & Kume, T. (2004). Study on antibacterial starch/chitosan blend film formed under the action of irradiation. Carbohydrate Polymers, 57(1), 83-88. doi:10.1016/j.carbpol.2004.04.003Perdones, Á., Vargas, M., Atarés, L., & Chiralt, A. (2014). Physical, antioxidant and antimicrobial properties of chitosan–cinnamon leaf oil films as affected by oleic acid. Food Hydrocolloids, 36, 256-264. doi:10.1016/j.foodhyd.2013.10.003Singh, G., Maurya, S., deLampasona, M. P., & Catalan, C. A. N. (2007). A comparison of chemical, antioxidant and antimicrobial studies of cinnamon leaf and bark volatile oils, oleoresins and their constituents. Food and Chemical Toxicology, 45(9), 1650-1661. doi:10.1016/j.fct.2007.02.031Bajpai, V. K., Baek, K.-H., & Kang, S. C. (2012). Control of Salmonella in foods by using essential oils: A review. Food Research International, 45(2), 722-734. doi:10.1016/j.foodres.2011.04.052Shah, B., Davidson, P. M., & Zhong, Q. (2013). Nanodispersed eugenol has improved antimicrobial activity against Escherichia coli O157:H7 and Listeria monocytogenes in bovine milk. International Journal of Food Microbiology, 161(1), 53-59. doi:10.1016/j.ijfoodmicro.2012.11.020Sebaaly, C., Jraij, A., Fessi, H., Charcosset, C., & Greige-Gerges, H. (2015). Preparation and characterization of clove essential oil-loaded liposomes. Food Chemistry, 178, 52-62. doi:10.1016/j.foodchem.2015.01.067Atarés, L., & Chiralt, A. (2016). Essential oils as additives in biodegradable films and coatings for active food packaging. Trends in Food Science & Technology, 48, 51-62. doi:10.1016/j.tifs.2015.12.001Sánchez-González, L., Chiralt, A., González-Martínez, C., & Cháfer, M. (2011). Effect of essential oils on properties of film forming emulsions and films based on hydroxypropylmethylcellulose and chitosan. Journal of Food Engineering, 105(2), 246-253. doi:10.1016/j.jfoodeng.2011.02.028Bakkali, F., Averbeck, S., Averbeck, D., & Idaomar, M. (2008). Biological effects of essential oils – A review. Food and Chemical Toxicology, 46(2), 446-475. doi:10.1016/j.fct.2007.09.106Wu, J., Liu, H., Ge, S., Wang, S., Qin, Z., Chen, L., … Zhang, Q. (2015). The preparation, characterization, antimicrobial stability and in vitro release evaluation of fish gelatin films incorporated with cinnamon essential oil nanoliposomes. Food Hydrocolloids, 43, 427-435. doi:10.1016/j.foodhyd.2014.06.017Imran, M., Revol-Junelles, A.-M., René, N., Jamshidian, M., Akhtar, M. J., Arab-Tehrany, E., … Desobry, S. (2012). Microstructure and physico-chemical evaluation of nano-emulsion-based antimicrobial peptides embedded in bioactive packaging films. Food Hydrocolloids, 29(2), 407-419. doi:10.1016/j.foodhyd.2012.04.010Zhang, H. Y., Arab Tehrany, E., Kahn, C. J. F., Ponçot, M., Linder, M., & Cleymand, F. (2012). Effects of nanoliposomes based on soya, rapeseed and fish lecithins on chitosan thin films designed for tissue engineering. Carbohydrate Polymers, 88(2), 618-627. doi:10.1016/j.carbpol.2012.01.007Jiménez, A., Sánchez-González, L., Desobry, S., Chiralt, A., & Tehrany, E. A. (2014). Influence of nanoliposomes incorporation on properties of film forming dispersions and films based on corn starch and sodium caseinate. Food Hydrocolloids, 35, 159-169. doi:10.1016/j.foodhyd.2013.05.006Olasupo, N. A., Fitzgerald, D. J., Gasson, M. J., & Narbad, A. (2003). Activity of natural antimicrobial compounds against Escherichia coli and Salmonella enterica serovar Typhimurium. Letters in Applied Microbiology, 37(6), 448-451. doi:10.1046/j.1472-765x.2003.01427.xMcHUGH, T. H., AVENA-BUSTILLOS, R., & KROCHTA, J. M. (1993). Hydrophilic Edible Films: Modified Procedure for Water Vapor Permeability and Explanation of Thickness Effects. Journal of Food Science, 58(4), 899-903. doi:10.1111/j.1365-2621.1993.tb09387.xHutchings, J. B. (1999). Food Colour and Appearance. doi:10.1007/978-1-4615-2373-4Falguera, V., Quintero, J. P., Jiménez, A., Muñoz, J. A., & Ibarz, A. (2011). Edible films and coatings: Structures, active functions and trends in their use. Trends in Food Science & Technology, 22(6), 292-303. doi:10.1016/j.tifs.2011.02.004Leceta, I., Guerrero, P., & de la Caba, K. (2013). Functional properties of chitosan-based films. Carbohydrate Polymers, 93(1), 339-346. doi:10.1016/j.carbpol.2012.04.031Pérez-Gago, M. B., & Krochta, J. M. (2001). Lipid Particle Size Effect on Water Vapor Permeability and Mechanical Properties of Whey Protein/Beeswax Emulsion Films. Journal of Agricultural and Food Chemistry, 49(2), 996-1002. doi:10.1021/jf000615fFabra, M. J., Talens, P., & Chiralt, A. (2008). Tensile properties and water vapor permeability of sodium caseinate films containing oleic acid–beeswax mixtures. Journal of Food Engineering, 85(3), 393-400. doi:10.1016/j.jfoodeng.2007.07.022Sánchez-González, L., Vargas, M., González-Martínez, C., Chiralt, A., & Cháfer, M. (2009). Characterization of edible films based on hydroxypropylmethylcellulose and tea tree essential oil. Food Hydrocolloids, 23(8), 2102-2109. doi:10.1016/j.foodhyd.2009.05.006McHugh, T. H., & Krochta, J. M. (1994). Water vapor permeability properties of edible whey protein-lipid emulsion films. Journal of the American Oil Chemists’ Society, 71(3), 307-312. doi:10.1007/bf02638058Ma, X., Chang, P. R., & Yu, J. (2008). Properties of biodegradable thermoplastic pea starch/carboxymethyl cellulose and pea starch/microcrystalline cellulose composites. Carbohydrate Polymers, 72(3), 369-375. doi:10.1016/j.carbpol.2007.09.002Fabra, M. J., Talens, P., & Chiralt, A. (2010). Water sorption isotherms and phase transitions of sodium caseinate–lipid films as affected by lipid interactions. Food Hydrocolloids, 24(4), 384-391. doi:10.1016/j.foodhyd.2009.11.004Shen, Z., & Kamdem, D. P. (2015). Development and characterization of biodegradable chitosan films containing two essential oils. 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Thermal conditions affecting heat transfer in FDM/FFE: a contribution towards the numerical modelling of the process

The performance of parts produced by Free Form Extrusion (FFE), an increasingly popular additive manufacturing technique, depends mainly on their dimensional accuracy, surface quality and mechanical performance. These attributes are strongly influenced by the evolution of the filament temperature and deformation during deposition and solidification. Consequently, the availability of adequate process modelling software would offer a powerful tool to support efficient process set-up and optimisation. This work examines the contribution to the overall heat transfer of various thermal phenomena developing during the manufacturing sequence, including convection and radiation with the environment, conduction with support and between adjacent filaments, radiation between adjacent filaments and convection with entrapped air. The magnitude of the mechanical deformation is also studied. Once this exercise is completed, it is possible to select the material properties, process variables and thermal phenomena that should be taken in for effective numerical modelling of FFE.This work was supported by Strategic Project - LA 25 - 2013–2014 [PEst-C/CTM/LA0025/2013]

Green concrete production incorporating waste carpet fiber and palm oil fuel ash

With the increasing amount of waste generation from various processes, there has been a growing interest in the utilization of waste in producing building materials to achieve potential benefits. This paper highlights the results of an experimental investigation on the performance of concrete incorporating waste carpet fiber (WCF) and palm oil fuel ash (POFA) as partial replacements of ordinary Portland cement (OPC). Six volume fractions varying from 0 to 1.25% of 20-mm-long carpet fiber were used with OPC concrete mixes. Another six mixes were made that replaced OPC with 20% POFA. The specimens were cured in water and tested for fresh and hardened state properties. The combination of WCF and POFA decreased the slump values and increased the VeBe time of fresh concrete. The addition of WCF to either OPC or POFA concrete mixes did not improve the compressive strength or modulus of elasticity. At 91 days, the compressive strength was in the range of 38.1e49.1 MPa. The positive interaction between WCF and POFA, however, leads to high tensile and flexural strengths, thereby increasing the concrete ductility with higher energy absorption and improved crack distribution. The maximum increases in tensile and flexural strengths compared to those of plain concrete were achieved by the addition of 0.5% carpet fiber at the age of 91 days. The ultrasonic pulse velocity (UPV) was examined and was classified as good quality concrete. The study showed that the use of waste carpet fiber and palm oil fuel ash in the production of sustainable green concrete is feasible both technically and environmentally