Towards a general framework for including noise impacts in LCA

Industrial Ecolog

The Psychometric Properties of a Self-Administered, Open-Source Module for Valuing Metastatic Epidural Spinal Cord Compression Utilities.

Introduction Web surveys are often used for utility valuation. Typically, custom utility valuation tools that have not undergone psychometric evaluation are used. Objectives This study aimed to determine the psychometric properties of a metastatic epidural spinal cord compression (MESCC) module run on a customizable open-source, internet-based, self-directed utility valuation platform (Self-directed Online Assessment of Preferences [SOAP]). Methods Individuals accompanying patients to the emergency department waiting room in Ottawa, Canada, were recruited. Participants made SOAP MESCC health state valuations in the waiting room and 48 h later at home. Validity, agreement reliability, and responsiveness were measured by logical consistency of responses, smallest detectable change, the interclass correlation coefficient, and Guyatt’s responsiveness index, respectively. Results Of 285 participants who completed utility valuations, only 113 (39.6%) completed the re-test. Of these 113 participants, 92 (81.4%) provided valid responses on the first test and 75 (66.4%) provided valid responses on the test and re-test. Agreement for all groups of health states was adequate, since their smallest detectable change was less than the minimal clinically important difference. The mean interclass correlation coefficients for all health states were > 0.8, indicating at least substantial reliability. Guyatt’s responsiveness indices all exceeded 0.80, indicating a high level of responsiveness. Conclusions To our knowledge, this is the first validated open-source, web-based, self-directed utility valuation module. We have demonstrated the SOAP MESCC module is valid, reproducible, and responsive for obtaining ex ante utilities. Considering the successful psychometric validation of the SOAP MESCC module, other investigators can consider developing modules for other diseases where direct utility valuation is needed.Hans K. Uthoff Fun

THE INFRARED SPECTRUM OF ACETYLENE CHEMISORBED ON NICKEL

Author Institution: Beacon Laboratories, The Texas CompanyThe infrared spectrum of acetylene chemisorbed on silica-supported nickel (9.2 wt. %) has been obtained. As in chemisorbed ethylene the absorption due to C-H stretching was essentially in the region characteristic of saturated hydrocarbons. But unlike chemisorbed ethylene, the chemisorbed acetylene spectrum shows evidence of the existence of $-CH_{3}$ groups by a sharp absorption band at 7.25 microns. Attempts were made to rule out effects due to residual surface hydrogen by chemisorbing acetylene on a de-hydrogenated surface and also on a deuterated surface. However in both cases the presence of $CH_{2}$ and $CH_{3}$ groups was indicated in the spectra of the chemisorbed acetylene. It was therefore concluded that self-hydrogenation takes place with some acetylene molecules giving up hydrogen atoms to others to form chemisorbed ethyl groups, $C^{*}H_{2}CH_{3}$, and a surface carbide

THE INFRARED SPECTRA OF OLEFINS CHEMISORBED ON NICKEL

Author Institution: Beacon Laboratories, The Texas CompanyThe infrared spectra of ethylene and propylene chemisorbed on silica-supported nickel (9.2 wt. %) have been obtained. Interpretation of the spectra is based on analogy with the spectra of hydrocarbons of known structure neglecting any possible effects of strain on the spectra of of the adsorbed hydrocarbons. In the case of chemisorbed ethylene the position of the absorption due to C-H stretching was essentially in the region characteristic of saturated hydrocarbons. In addition a band attributed to $CH_{2}$ deformation was observed at 6.91 microns. On the basis of these data it was concluded that the chemisorbed species consists mainly of $H_{2}C^{*}-C^{*}H_{2}$ (asterisk indicates bonding to the nickel surface). Evidence was obtained for the existence of a half-hydrogenated state, $C^{*}H_{2}CH_{3}$, by exposing the chemisorbed ethylene to hydrogen. Infrared spectra of chemisorbed propylene and hydrogen exposed chemisorbed propylene were also obtained

INFRARED STUDY OF THE HYDROGENATION AND DEHYDROGENATION OF CHEMISORBED OLEFINS AND ACETYLENE

Author Institution: Texaco Research Center, Beacon“Various unsaturated hydrocarbons were chemisorbed on Cabosil-supported nickel and then exposed to hydrogen to form adsorbed alkyl groups. Infrared spectra show that these chemisorbed alkyl groups can be dehydrogenated by evacuation to form a surface carbide type chemisorbed species. By reexposure to hydrogen at room temperature, the surface carbide is easily rehydrogenated to form adsorbed alkyl groups. The spectra show that some polymerization can occur during this procedure. This is especially interesting in the case of acetylene which on chemisorption forms both adsorbed ethyl groups and an appreciable quantity of surface carbide. Subsequent hydrogen exposure results in an infrared spectrum indicating mainly adsorbed butyl groups, consistent with the fact that hydrogenation of acetylene produces a product containing a high percentage of butane.