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The Reasons for Some Legal Fictions

In this age of fact, fancy is at a discount. Consequently legal fictions, which required the play of some fancy in their beginning, have fallen not only into disuse but also into disfavor. Many of them, however, have done good work in the past, and some are doing it now. Therefore it may not prove uninstructive to consider some in a discursive way. A legal fiction is probably best defined as a legal assumption that something is true which is, or may be, false-being an assumption of an innocent and beneficial character, made to advance the interests of justice. 1 From the definition it would seem that such fictions would always merit praise, never blame; but while their past use is now commended by most, no development of Law has had more condemnation from others. Sir Henry MAINE2 calls attention to the fact tha

Ireland Dear Ireland

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Community education and the older adult

The purpose of this article is twofold: a) to acquaint the reader with some factual information relating to the older American; b) to familiarize the reader with the community education philosophy and based on this philosophy how local communities can plan and implement programs and services for and with older adults

Investigation of Fluid Flow Through a Control Valve Opening

Mechanical Engineerin

Come To Baby, Do!\u27

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Reactivation of a Tin-Oxide-Containing Catalyst

The electrons in electric-discharge CO2 lasers cause dissociation of some CO2 into O2 and CO, and attach themselves to electronegative molecules such as O2, forming negative O2 ions, as well as larger negative ion clusters by collisions with CO or other molecules. The decrease in CO2 concentration due to dissociation into CO and O2 will reduce the average repetitively pulsed or continuous wave laser power, even if no disruptive negative ion instabilities occur. Accordingly, it is the primary object of this invention to extend the lifetime of a catalyst used to combine the CO and O2 products formed in a laser discharge. A promising low-temperature catalyst for combining CO and O2 is platinum on tin oxide (Pt/SnO2). First, the catalyst is pretreated by a standard procedure. The pretreatment is considered complete when no measurable quantity of CO2 is given off by the catalyst. After this standard pretreatment, the catalyst is ready for its low-temperature use in the sealed, high-energy, pulsed CO2 laser. However, after about 3,000 minutes of operation, the activity of the catalyst begins to slowly diminish. When the catalyst experiences diminished activity during exposure to the circulating gas stream inside or external to the laser, the heated zone surrounding the catalyst is raised to a temperature between 100 and 400 C. A temperature of 225 C was experimentally found to provide an adequate temperature for reactivation. During this period, the catalyst is still exposed to the circulating gas inside or external to the laser. This constant heating and exposing the catalyst to the laser gas mixture is maintained for an hour. After heating and exposing for an appropriate amount of time, the heated zone around the catalyst is allowed to return to the nominal operating temperature of the CO2 laser. This temperature normally resides in the range of 23 to 100 C. Catalyst activity can be measured as the percentage conversion of CO to CO2. In the specific embodiment described above, the initial steady-state conversion percentage was 70 percent. After four days, this conversion percentage decreased to 67 percent. No decrease in activity is acceptable because the catalyst must maintain its activity for long periods of time. After being subjected to the reactivation process of the present invention, the conversion percentage rose to 77 percent. Such a reactivation not only returned the catalyst to its initial steady state but resulted in a 10-percent improvement over the initial steady state value

Pt/SnO2-based CO-oxidation catalysts for long-life closed-cycle CO2 lasers

Noble-metal/tin-oxide based catalysts such as Pt/SnO2 have been shown to be good catalysts for the efficient oxidation of CO at or near room temperature. These catalysts require a reductive pretreatment and traces of hydrogen or water to exhibit their full activity. Addition of Palladium enhances the activity of these catalysts with about 15 to 20 percent Pt, 4 percent Pd, and the balance SnO2 being an optimum composition. Unfortunately, these catalysts presently exhibit significant decay due in part to CO2 retention, probably as a bicarbonate. Research on minimizing the decay in activity of these catalysts is currently in progress. A proposed mechanism of CO oxidation on Pt/SnO2-based catalysts has been developed and is discussed