By using measurements of the intensity of light scattered from intact calf lenses, we have determined a number of reagents that induce nuclear and cortical opacification at body temperature. Diffusion of buffered saline solutions of glycerol, other glycols, urea, guanidine hydrochloride or glycine into the lens reverses the opacity of all the reagent-induced cataracts. Similar findings are obtained with lens homogenates, which have gel-like properties as determined from viscosity measurements. A 50 % (by volume) glycerol or 5 M urea solution clarifies human pathologic cataractous lenses by reducing the opacification due to light scattering. These findings suggest that it may be possible, in principle, to reverse human lens cataracts chemically
in situ
. The scattering of laser light from quasi-periodic lattice of normal lens cells produces a regular diffraction pattern containing many Bragg spots whose positions are those predicted from the basis vectors of the cellular lattice. The intensity of the Bragg reflexions increases greatly when cataracts are formed in the calf and human lens, and falls greatly when the lenses are clarified. The spatial variation in the scattered light intensity of the Bragg spots and between these spots contains detailed information on the structure of the scattering elements associated with opacification.
Elemental sulfur recovery from SO2-containing gas streams is highly attractive as it produces a saleable product and no waste to dispose of. However, commercially available schemes are complex and involve multi-stage reactors, such as, most notably in the Resox(reduction of SO2 with coke) and Claus plants(reaction of SO2 with H2S over catalyst). This project will investigate a cerium oxide catalyst for the single-stage selective reduction of SO2 to elemental sulfur by a reductant, such as carbon monoxide. Cerium oxide has been identified in recent work at MIT as a superior catalyst for SO2 reduction by CO to elemental sulfur because of its high activi_ and high selectivity to sulfur over COS over a wide temperature range(40{3-650 "C). The detailed kinetic and parametric studies of SO2 reduction planned in this work over various CeO2-formulations will provide the necessary basis for development of a very simplified process, namely that of a single-stage elemental sulfur recovery scheme from variable concentration ,7,"as streams. The potential cost-and energy-efficiency benefits from this approach can not be overstated. A first apparent application is treatment of regenerator off-gases in power plants using regenerative flue gas desulfurization. Such a simple catalytic converter may offer the long-sought "Claus-alte:rnative" for coal-fired power plant applications.
Emissions of primary concern for coal-fueled diesel cogeneration and electric power plants are nitrogen oxides, sulfur dioxide, particulate matter, and aromatic hydrocarbons. In addition, the exhaust particulate size distribution and ash content are relevant to durability of the exhaust valves, turbocharger, and other engine components. This paper summarizes preliminary measurements of “uncontrolled” emissions in the exhaust of a Cooper-Bessemer 33-cm (13-in.) bore, 400 rpm, single-cylinder research engine, operated on “engine-grade” coal-water fuel (0.5 percent ash, 1 percent sulfur, 8 μm mean size coal). Based on these results, we present a preliminary evaluation of emission control options for satisfying hypothetical future emission standards for 2–50 MW power plants. The paper describes coal-diesel component subsystems such as (a) “reburning” for reducing NOx and hydrocarbon emissions, (b) high- and low-temperature injection of calcium sorbents for SO2 capture, and (c) high-temperature bag filters for control of fine particles. The expected performance of a conceptual, integrated control system is presented.
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