A high-sodium lignite from the Freedom mine in North Dakota was tested in the transport gasifier at the Power Systems Development Facility (PSDF). During the first use of the high-sodium lignite in October 2003, agglomerated deposits formed at various locations in the transport gasifier system. An extensive laboratory testing program was carried out to characterize the deposits, understand the mechanism of the deposit formation, and test various methods of preventing or minimizing the agglomeration. The results of the deposit analysis and initial lab studies suggested that sodium released from the lignite was deposited on the surface of the sand bed material, resulting in the formation of sticky sodium silicates. Additional laboratory tests indicated that the agglomeration could be avoided or minimized by replacing the sand with a nonreactive bed material (e.g., coarse coal ash), operating at slightly reduced temperatures and using certain types of additives. By using these procedures, we completely eliminated the deposition problems in a subsequent gasification run in August 2004.

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Children require a large amount of time, effort, and resources to raise. Physical help, financial contributions, medical care, and other types of assistance from kin and social network members allow couples to space births closer together while maintaining or increasing child survival. We examine the impact of kin availability on couples' reproductive success in the early twentieth-century United States with a panel data set of over 3.1 million couples linked between the 1900 and 1910 U.S. censuses. Our results indicate that kin proximity outside the household was positively associated with fertility, child survival, and net reproduction, and suggest that declining kin availability was an important contributing factor to the fertility transition in the United States. We also find important differences between maternal and paternal kin inside the household—including higher fertility among women residing with their mother-in-law than among those residing with their mother—that support hypotheses related to the contrasting motivations and concerns of parents and parents-in-law.

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