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[en] The design and metrological characteristics of a photometric gas analyzer for atmospheric sulfur dioxide that is equipped with adsorbing polymer films are considered. It is shown that the device can solve ecological and health safety issues and has small overall dimensions and power consumption.
[en] This fact sheet explains how Anon, Inc., has developed a novel method of removing photoresist--a light-sensitive material used to produce semiconductor wafers for computers--from the computer manufacturing process at reduced cost and greater efficiency. The new technology is technically superior to existing semiconductor cleaning methods and results in reduced use of hazardous chemicals
[en] We present molecular line and 1.4 mm continuum observations toward five massive star-forming regions at arcsecond resolution using the Submillimeter Array. We find that the warm molecular gas surrounding each H II region (as traced by SO2 and OCS) appears to be undergoing bulk rotation. From the molecular line emission and thermal component of the continuum emission, we independently derived gas masses for each region which are consistent with each other. From the free-free component of the continuum emission, we estimate the minimum stellar mass required to power the H II region and find that this mass, when added to the derived gas mass, is a significant fraction of the dynamical mass for that region.
[en] The SO2 tradable allowance program has been introduced into an electric industry undergoing dramatic changes. Entry of nonutilities into the industry and the emergence of stranded costs are two major changes that are shown to have an impact on the market for allowances and the industry's incentives to switch to cleaner fuels. The degree of impact depends on the extent to which consumers bypass traditional utilities and buy from entrants, and on public utility commission policies regarding the recovery of stranded costs. In turn, the amount of stranded costs depends on fuel switching. The results follow from simulations of a two-utility model that illustrate the qualitative effects of changing policies
[en] To the exclusion of other major atmospheric pollutants, sulfur dioxide is mainly responsible for attack upon dolomite. This article characterizes Laurel Dolomite on the basis of composition, texture, and porosity; describes the mechanism of the SO2 reaction with dolomite; and develops two equations for the prediction of the rate of decay of dolomite. Over a period of 120 yr nearly 3.57 mm surface reduction at protected areas and 0.915 mm surface reduction at unprotected surfaces of a building in Louisville was calculated. However, these values could not be verified because measurement of these quantities in the field cannot be made
[en] The ground and next excited 1A1 potential energy surfaces of the valence-isoelectronic molecules O3, S3, SO2, and S2O have been studied using full-valence-space-multiconfiguration self-consistent-field calculations. An open and a ring minimum were found for all species. In each case, interconversion between the C2v open and closed isomers proceeds via a C2v transition state which lies on a very sharp ridge separating the basins surrounding the minima. In the immediate vicinity of these transition states, the upper state for each species is found to have a minimum, also in C2v. Furthermore, not far away on the C2v ridges, the 11A1 and 21A1 surfaces intersect conically for all molecules. copyright 1997 American Institute of Physics
[en] We theoretically analyze the effectiveness of multiple-pulse laser alignment methods for asymmetric-top molecules. As an example, we choose SO2 and investigate the alignment dynamics induced by two different sequences, each consisting of four identical laser pulses. Each sequence differs only in the time delay between the pulses. Equally spaced pulses matching the alignment revival of the symmetrized SO2 rotor model are exploited in the first sequence. The pulse separations in the second sequence are short compared to the rotation dynamics of the molecule and monotonically increase the degree of alignment until the maximum alignment is reached. We point out the significant differences between the alignment dynamics of SO2 treated as an asymmetric-top and a symmetric-top rotor, respectively. We also explain why the fast sequence of laser pulses creates considerably stronger one-dimensional molecular alignment for asymmetric-top molecules. In addition, we show that multiple-pulse trains with elliptically polarized pulses do not enhance one-dimensional alignment or create three-dimensional alignment.
[en] The sulfur content of fossil fuels has been an environmental concern for many years. When burned, the sulfur forms harmful atmospheric contaminants such as SO2, a precursor to acid rain. To evaluate potential environmental hazards, it has become important to analyze the sulfur content of fossil fuels. This analysis is complicated due to the complex hydrocarbon matrix of the fossil fuels. Identification and quantification of the sulfur is possible only through the use of a sulfur-selective detector. This paper involves the application of high resolution gas chromatography for the analysis of various fuel mixtures and the detection of sulfur contaminants with an electrolytic conductivity detector operated in the sulfur mode (ELCD-S). This detector has a linear response to sulfur concentration for four orders of magnitude. Selectivity of sulfur to carbon is 105
[en] Although Thobacillus ferrooxidans and Leptospirillum ferrooxidans are widely considered to be the microorganisms that control the rate of generation of acid mine drainage, little is known about their natural distribution and abundance. Fluorescence in situ hybridization studies showed that at Iron Mountain, California, T. ferrooxidans occurs in peripheral slime-based communities (at pH over 1.3 and temperature under 30 degree C) but not in important subsurface acid-forming environments (pH 0.3 to 0.7, temperature 30 degree to 50 degree C). Leptospirillum ferrooxidans in abundant in slimes and as a planktonic organism in environments with lower pH. Thiobacillus ferrooxidans affects the precipitation of ferric iron solids but plays a limited role in acid generation, and neither species controls direct catalysis at low pH at this site. 24 refs., 3 figs
[en] This work investigates the predissociative C(11B2) state of SO2 by cooling the SO2 in a pulsed molecular beam and dispersing the emission upon resonant excitation into several different vibronic absorption features in the C state between 197 and 212 nm. Unlike at the lower excitation energies, the dispersed emission spectra at the higher excitation energies are dominated by progressions with odd quanta in the antisymmetric stretch mode ν3 and combination bands with up to six quanta in the bending mode ν2. The formidable intensity for emission into vibrational states with odd quanta in the antisymmetric stretch of the jet-cooled molecule suggests that the intermediate state at high energies in the excited state is of mixed electronic character at nonsymmetric geometries, so the operative components of the transition moment for excitation and emission may be different. We discuss our results by considering the avoided crossing seam and coupling between the C(11B2) state and two dissociative states potentially involved in the electronic predissociation, the 31A1 and the 13A1 states. copyright 1998 American Institute of Physics