The effects of temperature on nitrous oxide and oxygen mixture homogeneity and stability

<p>Abstract</p> <p>Background</p> <p>For many long standing practices, the rationale for them is often lost as time passes. This is the situation with respect to the storage and handling of equimolar 50% nitrous oxide and 50% oxygen volume/volume (v/v) mixtures.</p> <p>Methods</p> <p>A review was undertaken of existing literature to examine the developmental history of nitrous oxide and oxygen mixtures for anesthesia and analgesia and to ascertain if sufficient bibliographic data was available to support the position that the contents of a cylinder of a 50%/50% volume/volume (v/v) mixture of nitrous oxide and oxygen is in a homogenous single gas phase in a filled cylinder under normal conditions of handling and storage and if justification could be found for the standard instructions given for handling before use.</p> <p>Results</p> <p>After ranking and removing duplicates, a total of fifteen articles were identified by the various search strategies and formed the basis of this literature review. Several studies were identified that confirmed that 50%/50% v/v mixture of nitrous oxide and oxygen is in a homogenous single gas phase in a filled cylinder under normal conditions of handling and storage. The effect of temperature on the change of phase of the nitrous oxide in this mixture was further examined by several authors. These studies demonstrated that although it is possible to cause condensation and phase separation by cooling the cylinder, by allowing the cylinder to rewarm to room temperature for at least 48 hours, preferably in a horizontal orientation, and inverting it three times before use, the cylinder consistently delivered the proper proportions of the component gases as a homogenous mixture.</p> <p>Conclusions</p> <p>The contents of a cylinder of a 50%/50% volume/volume (v/v) mixture of nitrous oxide and oxygen is in a homogenous single gas phase in a filled cylinder under normal conditions of handling and storage. The standard instructions given for handling before are justified based on previously conducted studies.</p

Some fundamental aspects of self-levitating sliding contact bearings and their practical implementations

In this study, fundamental aspects and mechanisms of acoustic levitation together with governing equations are presented first. Then, the acoustic levitation phenomenon is considered as a new way to design air suspension systems capable of self-levitation. A particular emphasis is laid on journal bearings and their specific geometrical configuration. A practical feasibility of using acoustic levitation to separate contacting surfaces is supported and illustrated by results of experimental testing of a number of prototype devices

Nonlinear Acoustic Properties of Structural Materials — A Review

One of the most obvious manifestations of the nonlinear stress-strain relation in elastic solids is the existence of thermal expansion due to a non-parabolic atomic potential. From the acoustic point of view, this nonlinearity immediately explains a variety of observations such as stress effects on the sound propagation velocities and acoustic harmonic generation, which is basically a distortion of the wave. Additional nonlinearities come about due to dislocation motion, or the initiation of plastic flow, and the nucleation of a new phase, such as in the case of a martensitic transformation, e.g. Other examples are nonlinear acoustic effects that are induced at free and internal surfaces caused for a variety of reasons. Detailed acoustic experiments on these phenomena have been made over the past forty years but the ideas have not been applied seriously in NDE. The present paper is a short review of work, some of which this author has been involved in. The objective is to show the utility of nonlinear acoustics for NDE of structural materials