1,201 research outputs found

    Unusual presentation of synovial sarcoma as meniscal cyst: A Case Report

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    Periarticular cyst and cystic soft tissue lesion around the knee are common. Synovial sarcoma is a rare and malignant soft tissue tumor accounting for approximately 5 of soft tissue sarcoma. A case is presented where a lesion adjacent to the joint line of the knee was diagnosed clinically and on imaging as a meniscal cyst. MRI signal was homogenous and no concomitant meniscal tears were seen. The tissue diagnosis was monophasic synovial sarcoma. © 2015 BY THE ARCHIVES OF BONE AND JOINT SURGERY

    Assessment of the durability performance of fiber-cement sheets

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    According to standards, the durability performance of fiber-cement sheets must be evaluated by comparing the modulus of rupture (MOR) before and after durability tests (freeze-thaw, soak-dry, and warm water) are completed. This paper investigated the MOR of two different fiber-cement sheets samples before and after durability tests as well as its ductility and toughness. Results showed no significant difference between the MOR of control specimens and that of the specimens submitted to durability tests except in the case of the freezing and thawing test where after 100 cycles, a 7–9% decrease was observed. The differences between the MOR of the control specimens and that of the specimens submitted to durability tests were negligible and acceptable in accordance to the requirements of the standard. However, toughness and ductility decreased considerably in specimens of sample 1 by 25, 35, and 15%, respectively, when exposed to soak-dry (25 and 50 cycles) and warm water conditions. In turn, the reduction in toughness and ductility for specimens of sample 2 exposed to soak-dry (50 cycles) and warm water conditions were of 40 and 7%, respectively. The results of this investigation suggest that ductility and toughness should also be considered to assess the durability performance of fiber-cement sheets

    Concomitant Ulecranon Fracture, Ipsilateral Segmental Humerus Fracture and Intercondylar Humerus Fracture in a 4-Year-Old Girl: an Extremely Rare Case Report and Literature Review

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    T-condylar fracture of distal humerus in young children is very rare. Pure physeal fractures of the olecranon are also rare. We report on an extremely rare case of concomitant ulecranon fracture, ipsilateral segmental humerus and intercondylar humerus fracture (type III) in a skeletally immature patient

    Cementitious composites reinforced with polypropylene, nylon and polyacrylonitile fibres

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    This paper compares the adhesion strength between three polymeric fibres (polypropylene (PP), nylon66 (N66) and polyacrylonitrile (PAN)) embedded in a cement paste. The specimens were prepared at a water to cement ratio (w/c) of 0.5, and tested after 7, 14 and 28 curing days. It was found that although the adhesion between the polymeric fibres to the cement matrix is an important factor, the energy absorption capacity or energy dissipation ability of the fibres plays a more important role in the improvement of the cementitious composites fracture toughness. Scanning electron micrographs was used to characterize the fibres surface before and after the Pullout tests

    Evaluation of adhesion in polymeric fibre reinforced cementitious composites

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    In this study adhesion of some polymeric fibres to a cement matrix was evaluated both by a theoretical and by an experimental approach. In common methods adhesion of the fibres to the cementitious materials is determined by pull-out test. This test evaluates the energy failure during the fibre drawing out. This paper analyzes the adhesion theory for fibre reinforced cementitious composites to separate the share of the chemical and mechanical adhesion expressing new parameters, which are effective in the adhesion behaviour. Explanations about how the different fibres, matrix properties, test factors and environmental conditions can affect the adhesion results are given. It was found that for fibre/cement composites the fracture energy due to the interfacial interactions is for several orders of magnitude smaller that the polymeric fibre losses function. By employing adhesion theory, fibre/cement interac- tions are better described by a simple relationship of their surface free energy. Determination of the loss function (energy dissipation) leads us to predict the fibre behaviour in the cement matrix and the selection of the appropriate reinforcement

    Spatial Factors Affecting the Frequency of Pedestrian Traffic Crashes: A Systematic Review

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    Context: Considering the importance of pedestrian traffic crashes and the role of environmental factors in the frequency of crashes, this paper aimed to review the published evidence and synthesize the results of related studies for the associations between environmental factors and distribution of pedestrian-vehicular traffic crashes. Evidence Acquisition: We searched all epidemiological studies from 1966 to 2015 in electronic databases. We found 2,828 studies. Only 15 observational studies out of these studies met the inclusion criteria of the study. The quality of the included studies was assessed using the strengthening the reporting of observational studies in epidemiology (STROBE) checklist. Results: A review of the studies showed significant correlations between a large number of spatial variables including student population and the number of schools, population density, traffic volume, roadway density, socio-economic status, number of intersections, and the pedestrian volume and the dependent variable of the frequency of pedestrian traffic crashes. In the studies, some spatial factors that play an important role in determining the frequency of pedestrian traffic crashes, such as facilities for increasing the pedestrians’ safety were ignored. Conclusions: It is proposed that the needed research be conducted at national and regional levels in coordination and cooperation with international organizations active in the field of traffic crashes in various parts of the world, especially in Asian, African and Latin American developing countries, where a greater proportion of pedestrian traffic crashes occur

    Influence of acrylic fibers geometry on the mechanical performance of fiber-cement composites

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    This article analyses the influence of acrylic fibers shape on the flexural behavior of cement composite. The fibers differ in their cross-sectional shapes due to the spinning process (wet-spun and dry-spun). The fibers were characterized by optical microscopy, and the shape factors were calculated on the basis of their geometric characteristics. Results showed that both types of acrylic fiber remarkably improved the flexural performance of the composites. Wet-spun acrylic fibers lead to high flexural strength and toughness. It was found that by increasing the fibers’ shape factor by a factor of 10%, flexural strength and toughness increase to 26% and 23%, respectively

    Synthesis and Characterization of Acrylamide-Based Anionic Copolymer and Investigation of Solution Properties

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    The copolymer of acrylamide (AM) and 2-acrylamido-2-methyl-1-propane sulfonic acid (AMPS) was synthesized through radical solution polymerization by potassium persulfate as initiator. By changing the AMPS feed ratio from 10 to 70%, and keeping other reaction conditions constant, different copolymers were synthesized. The techniques of Fourier transform infrared (FTIR) and nuclear magnetic resonance (1H- 13C-NMR) spectroscopy were used for identification of functional groups and confirmation of copolymers’ structure. Intrinsic and apparent viscosity of samples were measured in aqueous sodium chloride solution under standard conditions. The anionic degree of copolymers was determined by back titration method and by 13C-NMR spectroscopy. Molecular weight of copolymers was determined by the Mark-Houwink relationship. The measured molecular weight of samples showed that we have acquired a high molecular weight product. The effect of different range of shear rates on solution viscosity was evaluated. The copolymer solutions showed non-Newtonian shear thinning behavior. The performance of copolymers with respect to shear resistance and molecular weight was evaluated from industry application standpoint

    A finite element assessment of the workpiece plastic deformation in machining of Ti-6Al-4V

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    Severe plastic deformation is not desired in machining as it adversely affects surface integrity. In this study, the performance of finite element formulations on subsurface plastic deformation is studied. Finite element models of orthogonal milling of Ti6Al4V have been developed using Update Lagrangian with element deletion as well as continuous remeshing algorithms. The models are validated not only by the measured cutting forces, but quantitative measurements of the subsurface plastic deformation. The results showed that continuous remeshing strategy generate smooth milling forces and predicted the plastic deformation of the machined subsurface with higher accuracy compared to the element deletion method
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