Aqueous photolysis of niclosamide

The photodegradation of [(14)C]niclosamide was studied in sterile, pH 5, 7, and 9 buffered aqueous solutions under artificial sunlight at 25.0 +/- 1.0 degrees C. Photolysis in pH 5 buffer is 4.3 times faster than in pH 9 buffer and 1.5 times faster than in pH 7 buffer. In the dark controls, niclosamide degraded only in the pH 5 buffer. After 360 h of continuous irradiation in pH 9 buffer, the chromatographic pattern of the degradates was the same regardless of which ring contained the radiolabel. An HPLC method was developed that confirmed these degradates to be carbon dioxide and two- and four-carbon aliphatic acids formed by cleavage of both aromatic rings. Carbon dioxide was the major degradate, comprising approximately 40% of the initial radioactivity in the 360 h samples from both labels. The other degradates formed were oxalic acid, maleic acid, glyoxylic acid, and glyoxal. In addition, in the chloronitroaniline-labeled irradiated test solution, 2-chloro-4-nitroaniline was observed and identified after 48 h of irradiation but was not detected thereafter. No other aromatic compounds were isolated or observed in either labeled test system.     

Neutron imaging of laser fusion targets

Along-term goal of inertial-confinement fusion research is the generation of energy by imploding capsules containing deuterium-tritium fuel. Progress in designing the capsules is aided by accurate imaging of the fusion burn. Penumbral coded-aperture techniques have been used to obtain neutron images that are a direct measurement of the fusion burn region in the capsules.     

Growth and digestibility by three sizes of Penaeus vannamei Boone: Effects of dietary protein level and protein source

Growth, survival and digestibility of Penaeus vannamei were studied in three experiments. P. vannamei averaging 4.0, 9.8 and 20.8 g were monocultured in circular fiberglass tanks (2650 l) for 30 days. Six diets having protein contents of 22, 29 and 36% and an animal: plant protein source ratio of 2:1 or 1:1 were fed ad libitum. Survival ranges for small, medium and large shrimp were 81.7–93.3, 65.6–90.0 and 65.0–80.0%, respectively, and were unrelated to diet.Growth (g/day) decreased significantly with increased size of shrimp, whereas digestibility varied independently of size. Growth by all three sizes of shrimp fed the 2:1 diet series was not significantly (α = 0.05) higher than that of the 1:1 diet series.Digestibility ranges for protein, lipid and total diet were 78.6–85.8, 45.1–64.8 and 43.9–53.8%, respectively, for small shrimp; 80.7–84.5, 52.8–63.8 and 46.9–53.0%, respectively, for medium shrimp; and 78.7–85.4, 49.2–63.2 and 41.8–58.4%, respectively, for large shrimp. Protein digestibility by small shrimp was strongly correlated with dietary protein level. Only small shrimp showed a strong correlation between protein digestibility and growth. No size exhibited a relationship between growth and either lipid or total diet digestibility.Growth of small P. vannamei appeared to be more influenced by protein level where-as growth of medium and large P. vannamei appeared to be more influenced by protein source.     

Landscape structure influences avian malaria ecology in the Western Cape, South Africa

A central theme in landscape ecology is that of understanding the consequences of landscape heterogeneity for ecological processes. The effects of landscape heterogeneity on parasite communities are poorly understood, although it has been shown that anthropogenic impacts may contribute to outbreaks of both parasites and pathogens. We tested for effects of landcover type, composition, configuration, and urbanisation on avian diversity and avian malaria prevalence in 26 communities of wetland-associated passerines in the Western Cape of South Africa. We predicted that avian malaria prevalence would be influenced by the pattern of farmland and urban areas in the surrounding landscapes and the sizes of the wetlands in which birds were sampled. We quantified landscape pattern using a six-class simplification of the National Landcover data set at 35 × 35 m resolution and five extents of between 1 and 20 km from each wetland. The bird community was sampled using point counts and we collected blood samples from birds at each site. We screened these for malaria using PCR and molecular techniques. Passerine species richness and infection prevalence varied significantly between different landcover types. Host richness and parasite prevalence were highest in viticultural and cropping sites respectively and lowest in urban sites. Wetlands located in indigenous vegetation had intermediate numbers of bird species and intermediate parasite prevalence. Landscape composition and habitat type surrounding wetlands emerged as useful correlates of infection prevalence. Anthropogenic landscape modification appears to have both direct and indirect effects on avian communities and their associated parasite assemblages, with attendant consequences for avian health.