Small-scale (< 100 W), low-pressure (4 MPa), low-cost hydraulic components, such as pumps and cylinders, have recently become more available. These components have potential uses in demanding applications such as in a pump-controlled electrohydrostatic actuators (EHA)s. This is limited by the fact that the unbalanced flows of a single-rod cylinder require a valve to reconcile the imbalance, which is commercially unavailable in this size and price range. We have hypothesized that it would be feasible to produce this component using additive manufactured (3D printed) plastic. Such a system would be relatively low cost with a high specific power, and could have applications in hand tools, prosthetics, robotics, and more. This paper focuses on some of the challenges in the use of 3D printed plastic for small-scale poppet valves and pressure vessels. The objectives of this research include the investigations of the sealing performance of 3D printed plastic poppet valves and the mechanical strength of 3D printed plastic pressure vessels. Experimental results included in this paper reveal the effects of surface finish and poppet and seat geometry on sealing performance. The influences of print process, material, and orientation on the strength of a 3D printed pressure vessel are examined and the results can inform valve casing design considerations. Mechanical tensile testing of fused deposition modelling (FDM) printed polyethylene terephthalate glycol (PETG) and stereolithography (SLA) printed acrylonitrile butadiene styrene (ABS)-like test specimens provided insight to the corresponding burst strength of that material and print process. The work presented in this paper advances the state-of-the-art of using 3D printed plastic for the construction of small-scale hydraulic components.
Although bacterial culture is considered to provide the most definitive diagnosis of gonorrhea, it has limitations when specimens must be transported long distances. A study was carried out to evaluate the validity and cost-effectiveness of an alternative method of diagnosing gonorrhea, the Gonozyme test, a commercially available enzyme immunoassay. Urogenital specimens from 100 men and 100 women with symptoms suggestive of or a history of exposure to gonorrhea were tested for the presence of Neisseria gonorrhoeae by means of bacterial culture and for gonococcal antigen with the Gonozyme test. The specimens from the men were also examined by means of microscopy of Gram-stained smears. The sensitivity and specificity of the Gonozyme test with reference to culture results were 95.6% and 97.4% respectively in the men and 84.2% and 98.7% in the women. The predictive value of a positive result was 91.6% in the men and 94.1% in the women, and the predictive value of a negative result 98.6% in the men and 96.3% in the women. The cost-effectiveness of the Gonozyme test was higher than that of bacterial culture in this population, which had a high prevalence rate of gonorrhea (23% in the men and 19% in the women). The Gonozyme test would be an adequate alternative to culture for the diagnosis of gonorrhea and contact tracing in areas far from diagnostic laboratories.Le diagnostic ferme de blennorragie se fait par la culture. Mais celle-ci est problematique lorsque les echantillons doivent etre expedies loin. On etudie
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