RESUMO
BACKGROUND: This study is aimed to investigate the types of knot failure (untying or breaking) and the tension required to break different sutures diameters. METHODS: One hundred and fifty knots were fabricated using polyamide sutures diameters of 6/0, 7/0, and 8/0. The studied knots were either squared or slipped with different numbers of throws (2, 3, 4, 5 and 6), and the following data were recorded: type of failure (untied or broken), number of throws, the tension required to untie or break each knot, slippage, and elongation of the knot. The knots were created in a standardized way. with a device and weights and then subjected to a controlled tension. RESULTS: The knots that got untied were: 1=1, 1x1, 2=1, and 2x1, whereas the remaining knots got broken. Notably, at least three throws were required to prevent untying, but separately, as in 1=1=1 or 1x1x1. The mean tension to break the knots of 6/0, 7/0, and 8/0 sutures were 3.1, 1.3, and 0.6 N, respectively (P < 0.05), and they were independent of the knot type. CONCLUSION: Results from this study demonstrated that the knots with geometries of 2=2/2x2 and 1=1=1/1x1x1 were secure, and additional throws does not increase their security. Furthermore, tensile strength reduces with decreased suture size.
RESUMO
We report the one-pot mechanochemical synthesis of N-doped porous carbons at room temperature using a planetary ball mill. The fast reaction (5 minutes) between calcium carbide and cyanuric chloride proceeds in absence of any solvent and displays a facile bottom-up strategy that completely avoids typical thermal carbonization steps and directly yields a N-doped porous carbon containing 16 wt% of nitrogen and exhibiting a surface area of 1080 m2 g-1.
RESUMO
Methane hydrate inheres the great potential to be a nature-inspired alternative for chemical energy storage, as it allows to store large amounts of methane in a dense solid phase. The embedment of methane hydrate in the confined environment of porous materials can be capitalized for potential applications as its physicochemical properties, such as the formation kinetics or pressure and temperature stability, are significantly changed compared to the bulk system. We review this topic from a materials scientific perspective by considering porous carbons, silica, clays, zeolites, and polymers as host structures for methane hydrate formation. We discuss the contribution of advanced characterization techniques and theoretical simulations towards the elucidation of the methane hydrate formation and dissociation process within the confined space. We outline the scientific challenges this system is currently facing and look on possible future applications for this technology.
