Sound-Absorption Properties of Materials Made of Esparto Grass Fibers

[EN] Research on sound-absorbing materials made of natural fibers is an emerging area in sustainable materials. In this communication, the use of raw esparto grass as an environmentally friendly sound-absorbing material is explored. Measurements of the normal-incidence sound-absorption coefficient and airflow resistivity of three different types of esparto from different countries are presented. In addition, the best-fit coefficients for reasonable prediction of the sound-absorption performance by means of simple empirical formulae are reported. These formulae require only knowledge of the airflow resistivity of the fibrous material. The results presented in this paper are an addition to the characterization of available natural fibers to be used as alternatives to synthetic ones in the manufacturing of sound-absorbing materials.This research was funded by CONICYT-FONDECYT, grant number 1171110.Arenas, JP.; Rey Tormos, RMD.; Alba, J.; Oltra, R. (2020). 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Evaluation of two alternative procedures for measuring airflow resistance of sound absorbing materials

[EN] It is well known that sound absorption and sound transmission properties of open porous materials are highly dependent on their airflow resistance values. Low values of airflow resistance indicate little resistance for air streaming through the porous material and high values are a sign that most of the pores inside the material are closed. The laboratory procedures for measuring airflow resistance have been stan- dardized by several organizations, including ISO and ASTM for both alternate flow and continuous flow. However, practical implementation of these standardized methods could be both complex and expensive. In this work, two indirect alternative measurement procedures were compared against the alternate flow standardized technique. The techniques were tested using three families of eco-friendly sound absorbent materials: recycled polyurethane foams, coconut natural fibres, and recycled polyester fibres. It is found that the values of airflow resistance measured using both alternative methods are very similar. There is also a good correlation between the values obtained through alternative and standardized methods.This project has been made possible thanks to the FONDECYT Project 1110605 and the grant GV/2012/066 Projects I+D for emerging research groups. The authors would like to thank Dr. Luis Godinho from the Department of Civil Engineering of University of Coimbra (Portugal) for his help with the experimental work and the ISO data reported in Table 1 of this paper.Rey Tormos, RMD.; Alba Fernández, J.; Arenas, JP.; Ramis Soriano, J. (2013). Evaluation of two alternative procedures for measuring airflow resistance of sound absorbing materials. Archives of Acoustics. 38(4):547-554. https://doi.org/10.2478/aoa:2013-0064S54755438

An electroacoustic method for measuring airflow resistivity of porous sound-absorbing materials

[EN] In this paper, a method for measuring the airflow resistivity of air-saturated porous sound-absorbing materials is presented. The method is based on a modification of the previous device developed by Dragonetti et al. The approach used in the present work involves a cavity and a Helmholtz resonator that are coupled through a loudspeaker so that the complete system behaves as a fourth-order symmetrical band-pass loudspeaker system. After a straightforward calibration, the airflow resistivity of a material sample is indirectly estimated from the direct measurement of the total electric impedance at the loudspeaker connection terminals. In this way, the use of microphones is not necessary, which makes its implementation very simple and inexpensive. Experimental results obtained with the present method agree well with those obtained through a standardized method as long as the values of the material's airflow resistance are not too high. (C) 2019 Elsevier Ltd. All rights reserved.The authors would like to gratefully acknowledge the support of CONICYT-FONDECYT under Grant 1171110 and to the Vicerectorate of R+i+t at Univ. Politecnica of Valencia, Grant PAID0017.Alba, J.; Arenas, JP.; Rey Tormos, RMD.; Rodríguez-Vercher, J. (2019). An electroacoustic method for measuring airflow resistivity of porous sound-absorbing materials. Applied Acoustics. 150:132-137. https://doi.org/10.1016/j.apacoust.2019.02.009S13213715

Determination of the elastic parameters of a material from a standardized dynamic stiffness testing

Viscoelastic layers under floating floors are often used to reduce impact sound. A standardized dynamic stiffness test is routinely used to estimate the performance of a layer as an impact sound isolator. During the test, a material sample is placed between a load plate and a motionless rigid foundation. In this work, equations that provide a useful analytical description of the standardized test are derived. The new analytical approach is linked with the analysis of multilayer elastomeric bearings. The new approach leads to simpler analytical solutions as compared with those of previous studies, which makes them easy to translate into computer codes. The obtained expressions are almost independent of the shape of the boundary and are only dependent on static values such as the area and moments of inertia of the contour. Taking advantage of the new closed-form solutions, it is shown that, under certain restrictions, the analytical approach may be used to experimentally estimate the elastic parameters of a flexible material using a harmonic (frequency-dependent) analysis. It is reported that results obtained using the proposed approach are in good agreement with those obtained using a commercial finite element software.This work was supported by CONICYT–FONDECYT [grant number 1171110]

Evaluation of bacterial adherence of clinical isolates of Staphylococcus sp. using a competitive model: An in vitro approach to the "race for the surface" theory

Objectives Implant-related infection is one of the most devastating complications in orthopaedic surgery. Many surface and/or material modifications have been developed in order to minimise this problem; however, most of the in vitro studies did not evaluate bacterial adhesion in the presence of eukaryotic cells, as stated by the 'race for the surface' theory. Moreover, the adherence of numerous clinical strains with different initial concentrations has not been studied. Methods We describe a method for the study of bacterial adherence in the presence of preosteoblastic cells. For this purpose we mixed different concentrations of bacterial cells from collection and clinical strains of staphylococci isolated from implant-related infections with preosteoblastic cells, and analysed the minimal concentration of bacteria able to colonise the surface of the material with image analysis. Results Our results show that clinical strains adhere to the material surface at lower concentrations than collection strains. A destructive effect of bacteria on preosteoblastic cells was also detected, especially with higher concentrations of bacteria. Conclusions The method described herein can be used to evaluate the effect of surface modifications on bacterial adherence more accurately than conventional monoculture studies. Clinical strains behave differently than collection strains with respect to bacterial adherence.This work was funded by the following grants from the Spanish MINECO (MAT2013- 48224-C2-2-R and MAT2013-48224-C2-1-R). M. Martínez-Pérez reports funding received from EFORT 2015 congress: travel supported by PFIZER, which is related to this article. J. Esteban and E. Gómez-Barrena report funding received from several companies for travel, expenses and grants, none of which is related to this articl

Curso modelado de nicho ecológico, version 1.0

The suite of ideas, protocols, and software tools that has come to be known as “Ecological Niche Modeling” (ENM) — as well as those for the related “Species Distribution Modeling” (SDM)—has seen intensive exploration and research attention in recent decades. In spite of at least four syntheses, the field has grown so much in complexity that it is rather difficult to access for newcomers. Until now, accessibility to this field was achieved by in-person courses organized by universities or research centers, in some of which we have participated as instructors. However, the access to these specialized courses is limited, on one hand because they are not offered in all universities, and on the other because normally they are taught in English. To expand the access to a wider community of Spanish-speaking researchers, here we offer an entirely digital and free-of-charge course in Spanish, which was presented over 23 weeks via Internet in 2018. Although intrinsic Internet-related barriers may limit access to course materials, we have made them available in diverse formats (video, audio, pdf) in order to eliminate most of these problems.El conjunto de ideas, métodos y programas informáticos que se conoce como “Modelado de Nicho Ecológico” (MNE)—y el relacionado “Modelado de Distribución de Especies” (MDS)—han sido objeto de intensa exploración e investigación en las últimas décadas. A pesar de existir al menos cuatro síntesis publicadas, este campo ha crecido tanto en complejidad, que la formación de nuevos investigadores es difícil. Hasta ahora, dicha formación se ha hecho de manera presencial en cursos organizados por universidades o centros de investigación, de los que hemos formado parte como instructores. Sin embargo, el acceso a este tipo de cursos especializados es restringido, por un lado, porque los cursos no se ofrecen en todas las universidades, y por otro, porque normalmente se imparten en inglés. Para facilitar el acceso a una mayor comunidad de científicos de habla hispana, presentamos un curso en español, completamente digital y de acceso gratuito, que se realizó vía Internet durante 23 semanas consecutivas en 2018. Aunque las barreras intrínsecas al uso de Internet pueden dificultar la accesibilidad a los materiales del curso, hemos usado diversos formatos para la divulgación de los contenidos académicos (video, audio, pdf) con el objetivo de eliminar la mayor parte de estos problemas

Colombia's cyberinfrastructure for biodiversity: Building data infrastructure in emerging countries to foster socioeconomic growth

Science and innovation are not a luxury but a prerequisite for social and economic development (Annan, 2003)

Analysis of consumption preference of goat products in different regions of Mexico

Objective: Characterize and determine consumption preferences for goat products in the different regions of Mexico. Design/methodology/approach: An exploratory study was carried out through a survey addressed to 300 consumers. The sample was obtained through convenience sampling. The semi-structured questionnaire was divided into the following sections: sociodemographic information, willingness to consume, type of known derivative products and frequency of consumption. To determine significant variables, the Kruskal-Wallis test was applied. Results: It was found that milk, cheese, and meat are the most relevant foods for goat consumption. These products are ideal for expanding the diversification of consumption in the Mexican regions. Limitations on study/implications: To deepen the analysis of sociodemographic and consumption characteristics, it is necessary to consider a greater number of variables. Findings/conclusions: Knowing the products that are consumed most frequently allows more effective and efficient strategies to be generated and, in turn, opens the pattern for consumption diversification.Objective: To characterize and determine the consumption preferences for goat products in different regions of Mexico. Design/methodology/approach: An exploratory study was carried out through a survey addressed to 300 consumers. The sample was obtained through convenience sampling. The semi-structured questionnaire was divided into the following sections: sociodemographic information, willingness to consume, type of derivative products known, and frequency of consumption. The Kruskal-Wallis test was applied to determine significant variables. Results: It was found that milk, cheese, and meat are the most relevant foods for goat consumption. These products are ideal for expanding the diversification of consumption in Mexican regions. Limitations on study/implications: To deepen the analysis of the sociodemographic and consumption characteristics, it is necessary to consider a greater number of variables. Findings/conclusions: Knowing the products that are consumed most frequently allows more effective and efficient strategies to be generated and, in turn, opens the pattern for consumption diversification

Setting performance indicators for coastal marine protected areas: An expert-based methodology

Marine Protected Areas (MPAs) require effective indicators to assess their performance, in compliance with the goals of relevant national and international commitments. Achieving and prioritizing shortlists of multidisciplinary indicators demands a significant effort from specialists to depict the multiple conservation and socioeconomic interests, and the large complexity of natural systems. The present paper describes a structured expert-based methodology (process and outputs) to co-define a list of multidisciplinary MPA performance indicators. This work was promoted by the management authority of coastal MPAs in mainland Portugal to gather a consensual and feasible list of indicators that would guide the design of a future national monitoring program. Hence, Portuguese coastal MPAs served as a case study to develop such a process between 2019 and 2020. In the end, participants (1) agreed on a shortlist of prioritized indicators (i.e., environmental, governance, and socioeconomic indicators) and (2) defined minimum monitoring frequencies for the indicators in this list, compatible with the potential replicability of the associated survey methods. The present approach recommends that management plans incorporate monitoring procedures and survey methods, with a validated list of indicators and associated monitoring periodicity, agreed among researchers, MPA managers and governance experts. The proposed methodology, and the lessons learned from it, can support future processes aiming to define and prioritize MPA performance indicatorsFundação para a Ciência e Tecnologia - FCT, European Maritime and Fisheries Fund (EMFF)info:eu-repo/semantics/publishedVersio