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Effects of Thermal Conditioning at High Temperatures on the Response of Concrete Elements Confined with a PBO-FRCM Composite System
No full textFiber-reinforced cementitious matrix (FRCM) materials are well-recognized as suitable for the strengthening of reinforced concrete (RC) and masonry existing structures. However, one of the main issues regarding these materials is the lack of knowledge about their behavior when subjected to elevated temperatures or fires. In this study, the effects of thermal actions on both the mechanical properties of the PBO (short of polypara-phenylene-benzo-bisthiazole)-FRCM materials (textile, mortar, and FRCM) and the structural response of unconfined and PBO-FRCM-confined concrete cylinders were analyzed. An experimental investigation was conducted on PBO fabrics, PBO-FRCM coupons, and unconfined and PBO-FRCM confined concrete cylinders. All specimens were thermally conditioned at temperatures ranging from 20°C to 200°C and then tested at room temperature (20°C). The thermal treatment consisted of five heating/cooling down cycles (one per day); in each cycle, the specimens were kept in an electric oven, heated at a predefined temperature over a period of 6 h, and then left to cool down at ambient temperature before the beginning of the next cycle. The test results evidenced that the thermal conditioning affected both the mechanical properties of the FRCM materials and the effectiveness of the concrete confinement. To predict the strength of the PBO-FRCM confined concrete cylinders after thermal conditioning, a semiempirical model defined through the analysis of a database of experimental results (those described in this paper and others available in the literature) was also proposed
Ethnic differences in body composition, sociodemographic characteristics and lifestyle in people with type 2 diabetes mellitus living in Italy
No full textThis study aimed to compare immigrants and Italian natives with type 2 diabetes mellitus (DM2) in terms of anthropometric parameters and lifestyle-related characteristics and to investigate the relationship between ethnicity and glycemic control in men and women with DM2 living in Italy. The sample included 100 immigrants (55 Albanians and 45 Africans) and 100 Italians, followed by the Public Health Clinics of Rimini. The association of ethnicity with sex, socioeconomic status, anthropometric and hematological characteristics, and lifestyle were examined. In addition, differences among groups in glycemic control were evaluated. Among males, African participants presented significantly lower values than other groups in adiposity parameters and triglycerides. The highest percentage of obesity and of normal weight was found in Italians and in Africans, respectively. Among females, there were scanty differences, but Italians presented higher WHR values than the other groups. No statistical differences appeared in hematological parameters among groups. There were no significant differences in glycemic control among groups and sexes. Also considering the differences between subjects with optimal (L) or nonoptimal (H) glycemic control, the differences in lifestyle, anthropometric, and hematological variables remained scarce. Among all groups, significantly higher values of glucose were detected in H than in L. A similar condition appeared for triglycerides in males. Immigrant and native Italian diabetics did not present any difference in their clinical characteristics, but Italians generally presented worst lifestyle habits. The percentage of subjects with poor metabolic control of diabetes was not low, but similar in immigrants and natives
Residual Mechanical Properties of PBO FRCM Composites after Elevated Temperature Exposure: Experimental and Comparative Analysis
No full textThe effects of the exposure to elevated temperatures on the mechanical performances of a PBO FRCM (fabric reinforced cementitious matrix) composite system, consisting of polypara-phenylene-benzo-bisthiazole (PBO) fiber meshes embedded into an inorganic mortar, widely used in the strengthening of existing degraded reinforced concrete structures, are analyzed and discussed in the paper. The residual tensile properties of PBO FRCM composites and the residual bond properties of PBO FRCM-to-concrete are analyzed through the results of an experimental investigation conducted on specimens subjected to heating-cooling regimes at temperatures ranging from 20°C to 300°C, and then tested at ambient temperature (20°C). Direct tensile (DT) tests on PBO FRCM coupons and direct single lap shear (DS) tests on PBO FRCM-concrete elements were performed. The parameter varied was the target temperature value, namely 20°C, 100°C, 200°C, and 300°C. Test results are reported in terms of cracking stress, tensile strength, ultimate tensile strain, uncracked and cracked elasticity moduli, failure mode, bond strength, and corresponding slip values. The obtained results are evidence that the effects of exposure at the target temperatures were different for each mechanical parameter. Significant reductions of the values measured at ambient temperature were observed only at 300°C. Temperature-dependent relationships for both tensile and bond mechanical parameters, useful for thermo-mechanical simulations and fire design of reinforced concrete structures strengthened with PBO FRCM composites, are also defined. Finally, the results of a comparative analysis between the experimental results described in the present paper and those available in the literature are reported and discussed
Mass spectrometry in the study of anthocyanins and their derivatives: differentiation of Vitis vinifera and hybrid grapes by liquid chromatography/electrospray ionization mass spectrometry and tandem mass spectrometry.
No full textA mass spectrometric-based procedure for anthocyanin profiling was set up to distinguish authentic Vitis vinifera from hybrid red grapevine cultivars. 3-O-Monoglucoside and the related acetyl-, p-coumaryland caffeoyl-monoglucoside anthocyanins occurred only in Vitis vinifera, whereas 3,5-O-diglucoside and the substituted acetyl-, p-coumaryl-, feruloyl- and caffeoyl-diglucoside anthocyanins were the additional pigments in hybrid grapevines. The procedure was applied expressly to identify red grape cultivars based on the anthocyanin chemo-type determination. In particular, a red grape cultivar, having 3,5-O-diglucoside anthocyanins and a novel class of anthocyanin monoglucosides, such as cyanidin-3-O-, cyanidin-3-O-(6-O-acetyl)- and cyanidin-3-O-(6-O-p-coumaryl)pentoside, was classified as hybrid. A second vine cultivar, characterized exclusively by 3-O-monoglucoside anthocyanins, was included among the Vitis vinifera species. Anthocyanin profiling by mass spectrometry could represent the core of a chemotaxonomic procedure for distinguishing American and European grapevines based on the identification of postsynthetic anthocyanidin modification
Effects of the Thermal Conditioning on the Mechanical Properties of an FRCM (Fiber Reinforced Cementitious Matrix) Strengthening System
No full textFiber reinforced composite materials are starting to have very widespread use for rehabilitation and strengthening of existing concrete structures. As demonstrated by several experimental results, the use of composites made with fibers and inorganic matrix (such as cement based or lime based matrix) is very useful from a mechanical point of view. The performances of existing reinforced concrete structures strengthened in bending and shear with FRCM systems evidenced a significant improvement both in strength and ductility. The durability of FRCM strengthening systems are not adequately analysed; due to a limited number of experimental studies and research carried out. Moreover, the effects on the environmental conditions on the mechanical properties of strengthening systems are not well investigated. In this paper, the effects of the thermal conditioning on the mechanical properties of the FRCM system was experimentally investigated. The examined strengthening system consists of PBO (short of Polyparaphenylenebenzobisthiazole) fabric meshes embedded into a cement-based matrix. The system was exposed to thermal cycles at different temperature values (100 and 200 °C) and, then, tested to evaluate its mechanical properties (ultimate strength, ultimate strain and elastic modulus). Five thermal cycles were developed by daily exposure of PBO fabric mesh, matrix and PBO-FRCM specimens at constant temperature value, over six hours and subsequently cooling down freely to ambient temperature (20 °C). After the thermal treatment, specimens were tested until failure, at room temperature. Results of tests analysed in terms of stress–strain relationships allowed influence evaluation of the thermal treatment on the structural response of PBO fibers, matrix and PBO-FRCM specimens
Durability Under Thermal Actions of Concrete Elements Confined with an Inorganic Matrix Fiber-Reinforced Composites
No full textFiber reinforced composite materials are starting to have very widespread use for rehabilitation and strengthening of existing concrete structures. As demonstrated by several experimental results, the use of composites made with fibers and inorganic matrix (such as cement based or lime based matrix) is very effective from a mechanical point of view. Nevertheless, there are legitimate concerns with the durability aspects of strengthened elements, which have hindered the widespread use of these composite materials in structural applications. The exposure of confined concrete elements to environmental actions could reduce the beneficial effects of the strengthening. For a better understanding of this aspect, through an experimental campaign, the paper aims to investigate the effects of thermal actions on the structural response of concrete elements confined with an inorganic matrix fiber-reinforced composite system, consisting of high strength fibers in the form of fabric embedded into a cement-based matrix. Cylindrical concrete specimens confined with one-layer of PBO (Polyparaphenylenebenzobisthiazole)-FRCM (Fiber Reinforced Cementitious Matrix) system were exposed to several (five) thermal cycles at different temperatures (100 and 200 °C) and, then tested under compression loads at ambient temperature (20 °C). When the desired temperature was reached, it was kept constant for 6 h and subsequently, the concrete specimens were cooled down freely to ambient temperature. The obtained results in terms of failure modes, peak strength, axial and radial strains were analysed, in order to evidence the effects of the thermal actions on the mechanical properties of confined concrete elements
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Walking for subjects with type 2 diabetes: A systematic review and joint AMD/SID/SISMES evidence-based practical guideline
Full text linkAIMS: Regular exercise is considered a cornerstone in the management of type 2 diabetes mellitus (T2DM). It improves glucose control and cardiovascular risk factors, contributes to weight loss, and also improves general well-being, likely playing a role in the prevention of chronic complications of diabetes. However, compliance to exercise recommendations is generally inadequate in subjects with T2DM. Walking is the most ancestral form of physical activity in humans, easily applicable in daily life. It may represent, in many patients, a first simple step towards lifestyle changes. Nevertheless, while most diabetic patients do not engage in any weekly walking, exercise guidelines do not generally detail how to improve its use. The aims of this document are to conduct a systematic review of available literature on walking as a therapeutic tool for people with T2DM, and to provide practical, evidence-based clinical recommendations regarding its utilization in these subjects.DATA SYNTHESIS: Analysis of available RCTs proved that regular walking training, especially when supervised, improves glucose control in subjects with T2DM, with favorable effects also on cardiorespiratory fitness, body weight and blood pressure. Moreover, some recent studies have shown that even short bouts of walking, used for breaking prolonged sitting, can ameliorate glucose profiles in diabetic patients with sedentary behavior.CONCLUSIONS: There is sufficient evidence to recognize that walking is a useful therapeutic tool for people with T2DM. This document discusses theoretical and practical issues for improving its use. This article is co-published in the journals Sport Sciences for Health and Nutrition, Metabolism and Cardiovascular Diseases
Variations on the Author
Full text link“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
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