1,720,959 research outputs found
Microbiological characteristics of fresh tofu produced in small industrial scale and identification of specific spoiling microorganisms (SSO)
No full textFresh tofu is a traditional Asian soybean-derived food product which has become increasingly popular worldwide, however, little is known on its microbial ecology and the microbial groups that can cause its deterioration. In this study, the microbiological characteristics of ready-to-eat fresh tofu produced by a small company in Northern Italy were investigated to unveil the abundance and composition of the microbiota and the identity and provenance of the specific spoiling microorganisms (SSO). Culture-dependent (RAPD-PCR and 16S rRNA gene sequencing) and culture-independent (PCR-DGGE) analyses were carried out on soybean lots and derived fresh tofu samples collected in different months and on two samples subjected to thermal abuse to simulate the interruption of the cold chain. Lactic acid bacteria species predominated in correctly preserved fresh tofu and bacterial species able to grow after thermal abuse mostly derived from the raw materials and belonged to heat labile species, thus suggesting that a more efficient heat treatment can increase the shelf-life of the product. Possible safety concerns could come from Streptococcus lutetientis, isolated from the artificially altered tofu, Clostridium spp. highlighted by culture-independent approach, and from Weissella confusa, but the majority of dominant bacteria identified belonged to non-pathogenic specie
Capacity assessment of uncorroded and corroded dapped‐end beams by NLFE and strut‐and‐tie based methods
Get PDFThe verification of dapped-end beams degraded by corrosion is a problem, especially for existing bridges in service. This paper proposes a nonlinear finite element (NLFE) modeling procedure and a simple strut-and-tie based procedure for predicting the response of dapped-end beams subjected to chloride corrosion. Firstly, the finite element modeling strategy, based on the adoption of multilayer shell elements and the PARC_CL 2.1 crack model is described. Then, the degradation effects on concrete, rebars, and steel-to-concrete interaction are defined as a function of the propagation period of corrosion. In particular, the effects of corrosion on the reinforcement are modeled by applying a reduction of tensile strength that considers for both the reduction of cross-section and the ultimate strain caused by pitting. Concrete splitting cracking due to volume expansion during rust formation is modeled by reducing the mechanical properties of concrete. Corrosion effects in steel-to-concrete interaction are modeled by applying a bond strength decay to the spring elements connecting corroded rebars-modeled with truss elements-and concrete multilayer shell elements. The proposed finite element procedure is used to study two scenarios based on different spatial distributions of corrosion-prone areas. Subsequently, a simplified analytical approach based on the strut-and-corroded tie method-called S&CT method-is proposed and compared with the finite element outcomes. Finally, the validations of the two proposed methods are presented with respect to a corroded dapped-end beam, showing that corrosion of rebars affects the resistance mechanisms of the dapped-end beam, by reducing both resistance and ductility. The proposed simplified analytical S&CT method provides conservative and safe results compared to the numerical NLFE model and to experimental data
SEISMIC ASSESSMENT OF EXISTING CIRCULAR HOLLOW RC PIERS SUBJECTED TO CORROSION THROUGH NLFEA
No full textThe capacity assessment of existing Reinforced Concrete (RC) bridges is a fundamental step to define rational intervention and retrofit strategies. Most of the Italian RC bridges date back to the second half of the last century and were therefore designed for gravity loads only or according to obsolete seismic codes, with inadequate structural detailing and poor-quality construction materials. The situation is further aggravated by aging and degradation over time, together with the limited maintenance level, which can lead to an increase in the seismic vulnerability of the infrastructure. Reinforcement corrosion is a major factor in the reduction of the seismic performance of RC bridges over time and can modify the expected failure mode of primary bridge components, such as piers. To investigate the effect of corrosion on RC piers, a non-linear finite element (NLFE) approach is presented in this work, based on the adoption of the PARC_CL 2.1 crack model, developed at the University of Parma, Italy, for RC elements subjected to cyclic loads and implemented as a user subroutine within the Abaqus FE package. Among the most remarkable features of the model stands out its capability to accurate simulate rheological phenomena, shear failures, reinforcement buckling, as well as the effects of corrosion on the structural response over time. The effectiveness of the proposed approach in the case of bridges is first proved through comparison with experimental data available in the literature on circular hollow RC piers. Finally, the model is applied to evaluate the time-varying capacity reduction of RC piers under aggressive environmental conditions, by considering the decay of the mechanical features and the role of rebars’ buckling
Structural Assessment of Corroded Dapped-end Beams
No full textMany existing concrete bridges with typical cantilever static schemes and with dapped-end suffer deterioration problems due to reinforcement corrosion and concrete degradation. Indeed, such infrastructures have usually reached or are going to reach the end of their service lives, and have been designed with outdated standards, where the durability problems were not considered. Moreover, the design loads used in the past are obsolete, not merely related to the design procedures, but also for increasing magnitudes of traffic and truck weights. In this context, the evolution of degradation of the reinforcement and concrete due to corrosion is particularly relevant, especially concerning the failure modes of the dapped-end beam. In recent decades, some catastrophic events related to the collapse of bridges with dapped-end beams highlighted how these elements are a critical part of such infrastructures. For this reason, their state of conservation must be analysed and evaluated carefully, especially in cases where reinforcement corrosion is present.
Over the years, various experimental techniques and analytical methods have been developed for studying dapped-end beams, and current standards provide well-tested tools for the design of these elements, such as the strut-and-tie method. However, the evaluation of existing dapped-end beams presents a separate issue. Due to both their shape and their location in areas that are difficult to access for regular and special inspections, these elements are highly susceptible to significant degradation and corrosion. Assessing the load-bearing capacity of dapped-end beams affected by corrosion is a current and relevant topic. The uncertainties related to reinforcement corrosion and the difficulty of accurately determining the structural degradation make this assessment extremely challenging. Current standards have only recently begun focusing on the development of reliable tools for evaluating existing structures, with limited progress specifically regarding dapped-end beams. In the literature, there are still relatively few studies addressing the issue of residual life assessment for dapped-end beams, particularly concerning corrosion-related aspects, highlighting the lack of a unified or standardized procedure for this type of analysis.
In this context, the present study aims to contribute to a correct methodological and engineering approach for evaluating the resistance of existing corroded dapped-end beams. Specifically, the problem of chloride-induced corrosion in dapped-end beams is analysed. The research aims to propose both numerical and analytical methods for assessing the residual structural capacity of corroded and non-corroded dapped-end beams, by adopting nonlinear finite element techniques and a simplified strut-and-tie model for corroded elements. The capacity of corroded dapped-ends is evaluated by considering several corrosion effects, such as mechanical properties decay of steel rebars and concrete as well as deterioration of bond-slip behaviour between steel and concrete. The proposed models have been validated both with and without corrosion using the latest experimental tests. Both the numerical modelling techniques and the analytical method have proven to be adequate and reasonably accurate for assessing the residual capacity of corroded dapped-end beams
L’insospettabile e straordinaria ricchezza alimentare generata dall’incontro tra le civiltà europea e latinoamericana
No full textDalla scienza del fare – tecnologia – che studia l’aspetto materialistico della preparazione del cibo, si attraversano campi come l’antropologia e la nutrizione, per arrivare all’analisi sensoriale che si interessa di un aspetto fisiologico-psicologico-culturale più intellettuale, intriso di valori estetici legati al consumo, un equilibrio tra necessità e piacere. Il cibo, con la preparazione, il consumo, la conservazione, diventa per l’emigrante un ‘bagaglio’ rifugio, un insostituibile compagno e strumento di consolazione e aggregazione.The Unexpected Influence of the European-Latin American Encounter on Food Cultivation, Preservation and PreparationThis essay combines the science of technology, which studies the material aspects of food preparation, with anthropology, nutrition and sensory analysis, which focuses on the physiological-psychological-cultural aspect – a more intellectual aspect linked with the aesthetic values of consumption that ensures a balance between necessity and pleasure. For migrants, the preparation, consumption and preservation of food becomes a shelter, an irreplaceable travel-mate and a tool for aggregation and consolation
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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