Relationship of the meniscofemoral ligaments of the knee to lateral meniscus tears: magnetic resonance imaging evaluation

This study sought to determine if the presence or absence of meniscofemoral ligaments exerts an influence on the prevalence of tears of the lateral meniscus. We reviewed the sagittal and coronal magnetic resonance images of 173 knees for lateral meniscus tears and the presence of the meniscofemoral ligaments. One or both meniscofemoral ligaments were present in 142 of 173 knees (82%). Fifty-four knees had lateral meniscus tears, 27 of which involved the posterior horn. Thirty-three percent of knees with meniscofemoral ligaments had a lateral meniscus tear, and 23% of knees without meniscofemoral ligaments had a lateral meniscus tear (no significant difference). We found no association between the presence of the meniscofemoral ligaments and tears of the lateral meniscus. Our study questions the importance of preserving or reconstructing these ligaments in instances of meniscal transplantation.     

Postpartum hemorrhage of the uterine artery rupture

Fatty masses, especially solid lipomas, in the paediatric abdomen are very rare. We present such a case, that of an 11-year-old boy who was admitted with abdominal pain and distension. The pre-operative diagnosis of lipoma was suggested by US and CT. The diagnosis of simple lipoma arising in the leaves of the small bowel mesentery, without immature cells, was verified microscopically after the operation. The tumour was enucleated from the mesenterium leaving the intestine intact. We underline the importance of US and CT as pre-operative diagnostic tools.     

Low-cycle fatigue and cyclic stress-strain behavior of incoloy 800

Strain-controlled low-cycle fatigue tests of solution-annealed Incoloy 800 were performed at temperatures of 538°, 649°, 704°, and 760°C using axial strain rates of 4 × 10^-3 and 4 × 10^-4 sec^-1. A few hold-time tests were also performed to indicate a noticeable reduction in fatigue life at hold times of 10 and 60 min. A comparison of these fatigue data with similar results for AISI 304 stainless steel indicates essentially identical behavior. An extensive study is made of the cyclic stress-strain behavior of Incoloy 800 and the relationship between the cyclic strain-hardening exponent and fatigue behavior is confirmed. Exponents onN _f in the elastic and plastic strain range terms of the total strain range equation are identified and compared with those used in the Universal Slopes equation.     

Analysis of a short, porous, flexible journal bearing

This article generalizes the very well-known Michell-Ocvirk short-bearing theory to take into account both porosity and flexibility of the bearing. The oil is assumed to be isoviscous, and pressure distributions are obtained for several eccentricity ratios and values of parameters involving porosity, bearing dimensions and speed.     

Electrocatalytic activation of ruthenium electrodes for the Cl2 and O2 evolution reactions by anodic/cathodic cycling

Ruthenium electrodes subjected to an anodic/cathodic potential cycling regime from 0.06 to 1.4E _H develop a changed state of surface oxidation in comparison with that observed in the initial sequence of potentiodynamic sweeps. The cycling effect is analogous to that known at iridium electrodes but here refers to monolayers. The kinetics of Cl₂ and O₂ evolution of these two types of oxidized surfaces were studied by steady-state polarization experiments. Current densities for Cl₂ evolution at the cycled Ru surface oxide areca 30 times greater than those at the original oxidized Ru surface. Oxygen evolution current densities are increased byca 8 times. The effect is a true electrocatalytic one since the real area of the Ru surfaces remains constant withinca 5%. The mechanisms of Cl₂ or O₂ evolution appear to remain unchanged, so the electrocatalytic effects observed are tentatively attributed to a change of potential range over which Ru(III) and Ru(IV) oxidation states arise in the oxide film causing modification of electron transfer rates or adsorption of ions and intermediates.Based on a report to Hooker Chemicals and Plastics Corp., Research Centre, Niagara Falls, NY, July 1976, on a research project supported by Hooker Research Center at the University of Ottawa, 1974–76.Where part of this work (on O₂ evolution electrocatalysis) was carried out by MV.     

Uranium spectrum between 1.8 and 5.5 microns emitted from a hollow cathode

The emission spectrum of uranium has been observed in the infrared from 1.8 to 5.5 μm using the McMath Fourier transform spectrometer at the Kitt Peak National Observatory, and a water-cooled hollow cathode lamp. The wavenumber, wavelength, and relative intensity of 4418 lines between 1817 and 5598 cm^?1 that can be classified as transitions between known levels of the first and second spectra of uranium have been tabulated. In addition, wavenumbers and intensities of 4744 lines that cannot be classified in this manner are listed. Most of these are believed to be uranium emission lines. Isotope shifts are reported for 196 lines.     

A method for shape optimization of a hip prosthesis to maximize the fatigue life of the cement

The long term success of total joint replacement can be limited by fatigue failure of the acrylic cement and the resulting disruption of the bone-cement interface. The incidence of such problems may be diminished by reduction of the fatigue notch factor in the cement, so that stress concentrations are avoided and the fatigue crack initiation time maximized. This study describes a method for numerical shape optimization whereby the finite element method is used to determine an optimal shape for the femoral stem of a hip prosthesis in order to minimize the fatigue notch factor in the cement layer and at interfaces with the bone and stem. A two-dimensional model of the proximal end of a femur fitted with a total hip prosthesis was used which was equivalent to a simplified three-dimensional axisymmetric model. Software was developed to calculate the fatigue notch factor in the cement along the cement/stem and cement/bone interfaces and in the proximal bone. The fatigue notch factor in the cement at the cement/stem interface was then minimized using the ANSYS finite element program while constraining the fatigue notch factor at the cement/bone interface at or below its initial level and maintaining levels of stress in the proximal bone to prevent stress shielding. The results were compared with those from other optimization studies.