1,721,031 research outputs found
Analysis of the bond between fabric reinforced cementitious mortar (FRCM) strengthening systems and masonry
No full textThe structural performances of masonry elements strengthened with externally bonded composites, is strongly governed by the bond between the strengthening system and the masonry substrate; the failure of strengthened masonry usually takes place with loss of bonding at the interface strengthening system /masonry substrate. Debonding has been widely studied in Fiber Reinforced Polymers (FRP) applied to concrete substrates but less in the case of masonry; very limited studies have been conducted to analyze the bond between Fiber Reinforced Cementitious Matrix (FRCM) strengthening systems and masonry. Due to the growing use of FRCM as strengthening systems of masonry structures, mainly historical and monumental masonry buildings, the analysis of the FRCM/masonry bond is essential for a reliable design of strengthening systems. In the present paper, results of an investigation, both experimental and theoretical, on bond between FRCM materials, made by Carbon fabric meshes embedded in a cement based matrix, and the masonry are presented and discussed. A total of eighteen clay brick specimens strengthened with a single layer of Carbon FRCM, were tested under single face shear tests under the ambient temperature of 20°C. In order to evaluate the influence of the bond length and to identify an effective anchorage length, different bond lengths (Lb=150, 200, 250 and 300 mm) of the C-FRCM reinforcement were considered. The width of reinforcement, bf, was equal to 50 mm for all tested specimens. Results of the analysis, presented and discussed in the paper, make possible: i) to determine the bond strength and the failure modes of the masonry strengthened by the FRCM system, ii) to evaluate the influence of mechanical and geometrical parameters involved in the masonry/reinforcing system transfer mechanism on the local bond-slip law
Bond analysis of thermally conditioned FRCM-masonry joints
No full textResults of an experimental investigation on bond between thermally conditioned FRCM-masonry joints is presented and discussed in the paper. Single lap shear tests were conducted on clay brick specimens strengthened with different FRCM systems (basalt, steel and PBO-FRCM systems). Before testing, specimens were exposed at different temperature values: 20 °C (ambient temperature), 100 °C, 150 °C and 200 °C. The heat-treating was developed based on the following proceeding: strengthened specimens were kept in oven and exposed to constant temperature over a period of three hours, then, they were removed and cooled down freely to ambient temperature. After that, specimens were tested at ambient temperature. Experimental results allow evaluating the influence of the thermal conditioning on the local bond-slip response of strengthened specimens
OXIDATION OF DESFERRIOXAMINE TO NITROXIDE FREE-RADICAL BY ACTIVATED HUMAN NEUTROPHILS
No full textHuman neutrophils activated by PMA were found to induce the formation of a nitroxide radical from DFO. The presence of SOD was necessary to per-mit the formation of the DFO radical. The inactive phorbol ester did not induce DFO radical, and DL-sphinganine suppressed the radical produced by the active phorbol ester. Other cell stimuli (Zymocel and the chemotactic peptide) also induced the formation of the DFO radical, although radical concentration was very much lower than with PMA. Participation of .NO, .OH or O-1(2) was ruled out by the inability of N(G)-methyl-L-arginine, N(G)-nitro-L-arginine, DMSO, mannitol, histidine, and methionine to inhibit the formation of DFO radical produced by PMA-activated cells. Furthermore, PMA-activated cells did not produce detectable levels of NO2-, a stable oxidation product of .NO, and D2O, which enhances the lifetime of singlet oxygen, did not modify the intensity or the lifetime of DFO radical. The involvement of cell MPO was suggested by the inhibition of the DFO radical observed after treatment with catalase or with antihuman MPO antibodies. Also, HOCl was found to induce the DFO radical in cell-free reactions, but our data indicate that the reaction leading to DFO radical formation by neutrophils involves the reduction of MPO compound II back to the active enzyme (ferric-MPO). Anti-inflammatory drugs strongly increased the DFO radical produced by activated neutrophils. On the contrary, none of these drugs was able to increase the DFO radical produced by HOCl. Histidine and methionine that inhibited the DFO radical intensity in cell-free reactions, were shown to act directly on HOCl. Experiments with MPO-H2O2 in SOD- and Cl--free conditions showed the formation of DFO radical and confirmed the hypothesis of the involvement of compound II. The conversion of compound II to ferric MPO by DFO optimized the enzymatic activity of neutrophils, and in the presence of monochlorodimedon (compound II promoting agent) we measured an increased HOCl production. When DFO was modified by conjugation with hydroxyethyl starch, it lost the ability to produce the radical either by neutrophils or by MPO-H2O2 and did not increase HOCl production. The inability of these DFO derivatives to produce potentially toxic species might explain their reported lower toxicity in vivo
Time heals all (shallow)wounds: A lesson on forgiveness of ingroup transgressors learned by the feyenoord vandal fans
No full textThis paper examines how a social threat posed by a deviant behavior affects second-hand forgiveness over time toward ingroup and outgroup transgressors. In Study 1, using real news reports, we investigated intergroup rivalries between soccer fans in order to understand the role of group membership in predicting the intention to forgive transgressors. Results suggested that transgressors were less likely to be forgiven by ingroup members rather than outgroup members, thus showing evidence of the black sheep effect. In Study 2 (using a different sample), we analyzed the same intergroup rivalries one year after the transgression in order to explore changes in intention to forgive over time. Results showed that, after one year, ingroup members were more likely to forgive ingroup than outgroup transgressors, but only when the threat to the group stereotype was not salient. The implications of the results for the subjective group dynamics theory and for the black sheep effect are discussed
Bond between carbon fabric-reinforced cementitious matrix and masonry substrate
No full textThe bond between fabric reinforced cementitious matrix (FRCM) and masonry substrates is investigated in this paper. An experimental investigation was performed on eighteen clay brick specimens strengthened with a single layer of carbon FRCM (CFRCM). Direct shear tests (single lap) were conducted at an ambient temperature of 20°C varying the bond length of the CFRCM reinforcement [Lb = 150 (6), 200 (8), 250 (10), and 300 (12) mm (in.)]. Experimental bond strength values, bond-slip law, and failure modes described and analyzed in this paper allow for evidencing of the bond performances of the CFRCM-masonry substrates. Finally, an analytical local bondslip law was defined and used to compare theoretical predictions and experimental results
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
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