Determination and Evaluation of Alternate Methods for Managing and Controlling Highway-Related Dust, TR-449, 2002

Road dust is caused by wind entraining fine material from the roadway surface and the main source of Iowa road dust is attrition of carbonate rock used as aggregate. The mechanisms of dust suppression can be considered as two processes: increasing particle size of the surface fines by agglomeration and inhibiting degradation of the coarse material. Agglomeration may occur by capillary tension in the pore water, surfactants that increase bonding between clay particles, and cements that bind the mineral matter together. Hygroscopic dust suppressants such as calcium chloride have short durations of effectiveness because capillary tension is the primary agglomeration mechanism. Somewhat more permanent methods of agglomeration result from chemicals that cement smaller particles into a mat or larger particles. The cements include lignosulfonates, resins, and asphalt products. The duration of the cements depend on their solubility and the climate. The only dust palliative that decreases aggregate degradation is shredded shingles that act as cushions between aggregate particles. It is likely that synthetic polymers also provide some protection against coarse aggregate attrition. Calcium chloride and lignosulfonates are widely used in Iowa. Both palliatives have a useful duration of about 6 months. Calcium chloride is effective with surface soils of moderate fine content and plasticity whereas lignin works best with materials that have high fine content and high plasticity indices. Bentonite appears to be effective for up to two years and works well with surface materials having low fines and plasticity and works well with limestone aggregate. Selection of appropriate dust suppressants should be based on characterization of the road surface material. Estimation of dosage rates for potential palliatives can be based on data from this report, from technical reports, information from reliable vendors, or laboratory screening tests. The selection should include economic analysis of construction and maintenance costs. The effectiveness of the treatment should be evaluated by any of the field performance measuring techniques discussed in this report. Novel dust control agents that need research for potential application in Iowa include; acidulated soybean oil (soapstock), soybean oil, ground up asphalt shingles, and foamed asphalt. New laboratory evaluation protocols to screen additives for potential effectiveness and determine dosage are needed. A modification of ASTM D 560 to estimate the freeze-thaw and wet-dry durability of Portland cement stabilized soils would be a starting point for improved laboratory testing of dust palliatives.

Comparison of three separate antiadhesive barriers for intraperitoneal onlay mesh hernia repair in an experimental model (Br J Surg 2011; 98: 442-449).

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Análise comparativa dos genomas de Salmonella enterica subsp. enterica sorovar Gallinarum biovares Gallinarum 287/91 e Pullorum 449/87 para identificação de regiões de diferenças (RODs)

Pós-graduação em Microbiologia Agropecuária - FCAV

Ms.Ff.F.Stoltze 3. 449 - Brief von Friedrich Stoltze an Laura Stoltze

Frankfurter Latern, Schmuckfarbe, Justinus Kerner

Na 1 Nachlass Max Horkheimer, 558 - Korrespondenzen mit Leo Löwenthal (p. VI 24, 231-449)

139 Briefe zwischen Max Horkheimer und Leo Löwenthal; 5 Briefe zwischen Charles Y. Glock und Max Horkheimer; 2 Briefe von Leo Löwenthal an Frederick Pollock, 1951/1952; 1 Brief von Leo Löwenthal an Theodor W. Adorno, 10.06.1952; 2 Briefe zwischen Max Horkheimer und Max Rheinstein, 1953; 2 Briefe von Max Horkheimer an Herbert W. Schneider, 16.07.1953;

Levine Suzanne Jill. Manuel Puig and the Spider Woman. His Life and Fictions. New York, Farrar, Straus and Giroux, 449 págs

Fil: Amícola, José. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.

Levine Suzanne Jill. Manuel Puig and the Spider Woman. His Life and Fictions. New York, Farrar, Straus and Giroux, 449 págs

Fil: Amícola, José. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.