269 research outputs found

    Improving the Torsional Strength of Reinforced Concrete Hollow Beams Strengthened with Externally Bonded Reinforcement CFRP Stripe Subjected to Monotonic and Repeated Loads

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    The loading on bridges, ports, multi-story parking garages, airport facilities, and many other structures is often repeated and usually built with reinforced concrete beams. The behavior of concrete under repeated loads differs from that of static loads. Due to the loading and unloading process, repeated loads cause crushing in some concrete sections. The war and other events damaged numerous concrete structures and bridges in Iraq. Therefore, maintenance and rehabilitation of these structural parts are already required. This study aims to illustrate the behaviour of reinforced concrete hollow beams strengthened with a strip of carbon fiber reinforced polymer (CFRP) in various configurations using the externally bonded reinforcement (EBR) method when exposed to monotonic and repeated torsion. Eight beams of 250 x 350 x 3000 mm were cast and tested up to failure under pure torsion. Two of these beams were unreinforced. Other beams were strengthened with varied configurations of CFRP strips. The tested specimens were divided into two groups. For each investigation condition, the beam was examined under monotonic torsion and utilized as a control for those examined under repeated torsion after seven cycles of 60% of the control samples ultimate loads. Using the CFRP stripe, the torsional performance of the reinforced concrete beams was greatly enhanced. Test beams reinforced with two continuous CFRP stripes demonstrated a more significant increase in the ultimate torsional moment than beams strengthened with other CFRP stripe configurations. Beams tested under repeated torsion show less degradation in torsional strength than beams tested under monotonic torsion moment

    Proizvodnja amorfnih traka gotovo stalnog stupnja amorfnosti

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    This paper describes a modified melt spinning method that provides for production of amorphous ribbons with a nearly constant short-range order. The ribbon structure can be controlled by relevant parameters, and if these parameters are constant, the ribbons produced have approximately the same degree of amorphousness. A detailed investigation proved that it was necessary to control accurately the melting temperature and the surface velocity of the drum on which the quenching is made. The system is computer controlled using specially adapted software. The particular phases during the process of amorphous ribbon production are turned on in accordance with the temperature of the melt. We made a comparative measurement of produced ribbons proving that ribbons produced with the same parameters have approximately the same degree of amorphousness.Opisujemo usavršenu metodu taljevine na rotirajućem valjku kojom se proizvode amorfne trake gotovo stalnog kratko-dosežnog uređenja. Struktura traka može se upravljati putem parametara, a ako su ti parametri stalni, proizvedene trake imaju jednake stupnjeve amorfnosti. Pažljiva ispitivanja su pokazala da je potrebno točno podesiti temperaturu taljevine i obodnu brzinu hlađenog valjka kojim se postiže brzo hlađenje. Uređajem upravlja računalo koje rabi posebno preuređen program. Pojedine faze proizvodnje se uključuju ovisno o temperaturi taljevine. Načinili smo usporedbena mjerenja s proizvedenim trakama uz jednake parametre koja pokazuju da postižemo stalne stupnjeve amorfnosti

    Pubertal timing in girls and depression: A systematic review

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    Background: Because the incidence of depression increases after puberty, it is possible that pubertal timing in girls influences the onset of depression. Our objective was to assess the effect of early and late puberty in girls on the incidence of depression. Methods: We systematically searched relevant databases for controlled studies that assessed the impact of pubertal timing in girls on the incidence of depression or depressive symptoms. The last search was completed in August 2013. Two authors selected the studies, extracted the data, and assessed the quality of the evidence. Meta-analyses of the adjusted and unadjusted results were calculated using random effects. Results: Four cohort studies were included (n=8055 participants). Early puberty significantly increased the risk of new cases of depression in the unadjusted meta-analysis (RR=1.33; CI 95%: 1.02, 1.73) but not in the adjusted estimate of two of the included studies (RR=1.48; CI 95%: 0.69, 2.28). For late puberty, no significant associations were found (unadjusted RR=1.28; CI 95%: 0.87, 1.88). Two studies assessed the effect of early puberty on depressive symptoms and found positive associations. The quality of the available evidence was rated as very low. Limitations: The polled results had wide confidence intervals, and the available evidence was of very low quality. Conclusions: The available evidence supports little confidence regarding the impact of pubertal timing on the onset of depression in girls but suggests that early puberty in girls may increase the risk of depression. Further higher quality studies are needed to clarify the association between pubertal timing and the incidence of depression in girls and women

    Profile of Trypanosoma cruzi Infection in a Tropical Medicine Reference Center, Northern Italy

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    Chagas disease (CD) is endemic in Central and South America, Mexico and even in some areas of the United States. However, cases have been increasingly recorded also in non-endemic countries. The estimated number of infected people in Europe is in a wide range of 14000 to 181000 subjects, mostly resident in Spain, Italy and the United Kingdom

    A Simple Double-Spin Closed Method for Preparing Platelet-Rich Plasma

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    Objective: To describe and analyze a new protocol for the extraction of platelet-rich plasma (PRP) for use in clinical practice and compare this technique with methods that have been previously described in the medical literature. Methods: Sixteen blood samples from healthy volunteers were collected. PRP was prepared using our new double-spin technique, consisting of successive centrifugation of blood samples with two different spins, without opening the container. Descriptive analysis of cell counts in baseline and PRP samples was undertaken. Comparison between cell and platelet count in baseline and PRP samples, as well as the statistical analysis, were done. Results: The mean platelet concentration ratio was 3.47 (SD: 0.85; 95% CI: 3.01-3.92; range: 2.48-5.71). The baseline whole blood platelet count correlated positively to the PRP platelet count (rP = 0.56; 95% CI: 0.09- 0.88; P = 0.023). The PRP was enriched for lymphocytes and monocytes but presented significantly lower counts of neutrophils and eosinophils in comparison to baseline. Conclusion: Results show a safe and easily reproducible method to obtain PRP for use in clinical daily practice.info:eu-repo/semantics/publishedVersio

    (R)-(-)-carvone and (1R, 4R)-trans-(+)-dihydrocarvone from poiretia latifolia vogel

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    The essential oils of Poiretia latifolia Vogel, native and cultivated leaves (Samples A and B, respectively) and native flowers (sample C), were obtained by hydrodistillation and analyzed by GC, GC/MS and chiral phase gas chromatography (CPGC). Twenty-four compounds were identified, representing 99.25, 99.26 and 99.23% of the oils, respectively. The major constituents of the oils were the monoterpenes (S)-(-)-limonene (16.05, 27.60, 15.60%, respectively), (1R, 4R)-trans-(+)-dihydrocarvone (18.05, 0.66 and 77.80%, respectively) and (R)-(-)-carvone (61.05, 64.20 and 4.50%, respectively). The essential oils were evaluated against some strains of Gram (+) and Gram (-) bacteria, and yeast, but displayed only modest antimicrobial activity

    A comparison of two distinct murine macrophage gene expression profiles in response to Leishmania amazonensis infection

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    <p>Abstract</p> <p>Background</p> <p>The experimental murine model of leishmaniasis has been widely used to characterize the immune response against <it>Leishmania</it>. CBA mice develop severe lesions, while C57BL/6 present small chronic lesions under <it>L. amazonensis </it>infection. Employing a transcriptomic approach combined with biological network analysis, the gene expression profiles of C57BL/6 and CBA macrophages, before and after <it>L. amazonensis </it>infection in vitro, were compared. These strains were selected due to their different degrees of susceptibility to this parasite.</p> <p>Results</p> <p>The genes expressed by C57BL/6 and CBA macrophages, before and after infection, differ greatly, both with respect to absolute number as well as cell function. Uninfected C57BL/6 macrophages express genes involved in the deactivation pathway of macrophages at lower levels, while genes related to the activation of the host immune inflammatory response, including apoptosis and phagocytosis, have elevated expression levels. Several genes that participate in the apoptosis process were also observed to be up-regulated in C57BL/6 macrophages infected with <it>L. amazonensis</it>, which is very likely related to the capacity of these cells to control parasite infection. By contrast, genes involved in lipid metabolism were found to be up-regulated in CBA macrophages in response to infection, which supports the notion that <it>L. amazonensis </it>probably modulates parasitophorous vacuoles in order to survive and multiply in host cells.</p> <p>Conclusion</p> <p>The transcriptomic profiles of C57BL/6 macrophages, before and after infection, were shown to be involved in the macrophage pathway of activation, which may aid in the control of <it>L. amazonensis </it>infection, in contrast to the profiles of CBA cells.</p

    Study on antibacterial activity of silver nanoparticles synthesized by gamma irradiation method using different stabilizers

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    In order to observe the microbiological status of CMT positive samples, 734 apparently health mammary quarters from buffalo cows were submitted to physical evaluation, strip cup test and CMT. After milk samples inoculation in 10% ovine blood agar base media and in MacConkey agar and incubation under aerobic condition for 72 hours at 37 degrees C, identification was proceeded. According to CMT, 227 quarters (30,93%) were positive, among them 73 (32,16%) presented 1+ reaction, 53 (23,35%) were 2+ and 101 (44,49%) were 3+. Microbiological exams of such samples were positive in 147 (64,76%) out of 227 CMT positive samples and among the remaining 72 (31,72%) were negative and 8 (3,52) were contaminated. In the 147 microbiological positive samples 204 bacteria were found in pure or associated growth and the most frequent agents were: Corynebacterium sp (59,25%); Staphylococcus sp (17,65%) among which 86,11% were coagulase negative and 13,89% were coagulase positive; and Micrococcus sp (6,37%). The results revealed that, excluding the eight contaminated samples, 147 (67,12%) quarters out of 219 CMT positive could be considered as bacteria-carrier and that even in a smaller percentage false-positive results can cause problems in a sanitary program for mastitis control in dairy buffalo cows
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