Donald K. Law

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Our knowledge of circular replication-associated protein encoding single-stranded (CRESS) DNA virus diversity has increased dramatically in recent years, largely due to advances in high-throughput sequencing technologies. These viruses are apparently major virome components in most terrestrial and aquatic environments and it is therefore of interest to(More)
Although several typing methods have been described for Shiga-like toxin-producingEscherichia coli O157, the methods are somewhat cumbersome. Using 22 isolates ofEscherichia coli O157 and five otherEscherichia coli isolates, two primers (M13 core sequence and 970-11) were found to give excellent differentiation between isolates using random amplified(More)
Various facets of thermal testing of space vehicles in cold vacuum chambers, with and without solar simulation, are discussed. Emphasis is on thermal modeling of spacecraft. Thermal modeling is discussed for the case of simultaneous preservation of temperature, material and surface properties. The following specific items are treated; (1) a criterion for(More)
The design and operational characteristics of an in-house-built 5-cm-diam Kaufman-type ion engine that was used to evaluate diagnostic methods is presented. The discharge of the ion engine was investigated and analyzed by employing various types of material probes. The emissive probe was used to determine the beam potential. In addition, the same probe was(More)
i Corrosion of cryopanel metals in space simulation chambers caused by contamination by fuels, oxidizers, or exhaust gases arising from propulsion systems testing may be a serious problem. Since data taken under operational conditions is needed, a preliminary study using nitrogen tetroxide and 300-series stainless steel was initiated. The temperature was(More)
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