Engineering the activity and lifetime of heterogeneous catalysts for carbon nanotube growth via substrate ion beam bombardment.

We demonstrate that argon ion bombardment of single crystal sapphire leads to the creation of substrates that support the growth of vertically aligned carbon nanotubes from iron catalysts with a density, height, and quality equivalent to those grown on conventional, disordered alumina supports. We quantify the evolution of the catalyst using a range of surface characterization techniques and demonstrate the ability to engineer and pattern the catalyst support through control of ion beam bombardment parameters.

Acquired immunodeficiency syndrome and human immunodeficiency virus infection in Nevada.

We summarize information from three sets of epidemiologic data: the Nevada AIDS [acquired immunodeficiency syndrome] Surveillance System, which contains information about every case identified within the state boundaries through September 1989; the human immunodeficiency virus (HIV) seroprevalence reporting systems, which currently include data on all HIV-positive reports submitted statewide to public health authorities; and surveys on the knowledge, attitudes, and behaviors of Nevadans concerning HIV-related disease. The Nevada State AIDS Task Force outlined major policy recommendations, nearly half of which concerned testing; only 2 dealt with preventing HIV transmission. Greater efforts should go into education, particularly directed toward groups at greatest risk of exposure to HIV, and to improve community-based care of infected persons.