Activity of 2-(1-alkenyl)-3-hydroxy-1,4-naphthoquinones and related compounds against Musca domestica

A series of 2-(1-alkenyl)-3-hydroxy-1,4-naphthoquinones has been prepared and their toxicities assessed against Musca domestica. By comparison with analogous compounds having saturated 2-alkyl substituents, or unsaturated substituents with an unconjugated double bond (e.g. lapachol), it was demonstrated that the α-unsaturation of the substituent is responsible for a significant increase in the toxicity. The effect of the compounds against several other insect species and Tetranychus urticae follows completely different patterns.     

Fungicidal activity of 2-(1-alkenyl)-3-hydroxy-1,4-naphthoquinones and related compounds

The fungicidal activity of a series of 2-(1-alkenyl)-3-hydroxy-1,4-naphthoquinones and their acetates has been assessed against various fungi in vitro and against others, notably powdery mildews, in vivo, and the activity compared with that of analogous compounds bearing saturated side chains. Several of the compounds demonstrated a broad spectrum of activity in vitro. Whereas the presence of α-unsaturation in the side chain is essential for the in-vitro activity against the non-obligate fungi tested, it is of virtually no importance for the curative effect against Erysiphe graminis on barley. Only the corresponding acetates had activity against the latter pathogen.     

Airborne heavy metal pollution in the environment of a danish steel plant

A survey of heavy metal deposition was carried out in the vicinity of a Danish steel plant. Bulk precipitation and transplanted lichen (Hypogymnia physodes (L.) Nyl.) were sampled at 12 stations in the environment before and after the production had been converted from open-hearth furnaces to electric-arc furnaces. The samples were analyzed for Cd, Cr, Cu, Fe, Mn, Pb and Zn. The results show that heavy metal pollution from the steelworks still is severe and that it follows a decreasing power curve when the distance to the steelworks is increased. However, a reduction in the deposition of heavy metals close to the steelworks has been observed, pointing to the conclusion that the change from a situation of emission through a 46 m stack without any filter to emission from the electric arc furnaces equipped with bag-filters has lead to changes in the emission. At the sampling stations with the highest deposition levels measured in bulk precipitation the corresponding concentrations in the lichens were relatively lower indicating a change in particle size distribution. Within each station there was a direct proportionality of metal concentrations in lichens and atmospheric fallout measured in bulk precipitation.     

Influence of zinc bacitracin, light regimen and dustbathing on the health and welfare of broiler chickens.

1. The influence of zinc bacitracin, an antibiotic growth promoter, and the combined influence of two environmental factors (8 h of darkness and access to sand) on health and welfare variables were studied in 96 broiler chickens (kept as pairs). 2. Chickens fed with zinc bacitracin (ZB) had a higher frequency of tibial dyschondroplasia (TD) and a higher frequency of dustbathing than chickens fed without zinc bacitracin. 3. When 42 d old, chickens exposed to 8 h of darkness and access to sand were heavier than chickens reared under continuous light and with no access to sand. 4. Fluctuating asymmetry was higher in the 'light/no sand' groups than in the 'night/sand + ZB' group. 5. There was a negative correlation between tonic immobility and weight and a positive correlation between weight and TD.     

Infection dynamics of Lawsonia intracellularis in pig herds

Little information is known about the natural course and within-herd prevalence of porcine proliferative enteropathy caused by Lawsonia intracellularis. The objective of the study was to investigate the within-herd dynamics of naturally acquired L. intracellularis infection in pigs from weaning to slaughter. The study was designed as a longitudinal survey where 100 pigs from five herds were randomly selected at weaning (approximately 4 weeks of age). Every second week until slaughter (10-12 times, i.e. 20-24 weeks) the pigs were weighed and faecal as well as blood samples were collected. Faecal shedding of L. intracellularis was assessed by real time-PCR and sero-conversion by an indirect immunofluorescence antibody test (IFAT). Clinical disease was not reported but infection was present in all herds and the PCR assay indicated infection in 75% of pigs examined. Most L. intracellularis infected pigs were shedding at 10-12 weeks of age (22-29 kg) and shed for 2-6 successive weeks. After 18 weeks of age all shedding had ceased and re-infection at PCR detectable level was not seen. Variable L. intracellularis associated impact on growth rate was observed. Immediately before bacterial shedding and during early infection the average growth rate declined whereas a compensatory impact was observed during later infection and after bacterial shedding had ceased. The performance of the IFAT resembled the bacteriological test almost perfectly. Sero-conversion was first detected at 12-14 weeks of age. Relative to the bacterial shedding, the onset of sero-conversion was a little delayed, in general, most pigs had sero-converted 2 weeks after the first shedding. Once sero-converted, 92% of the pigs remained sero-positive over the entire survey period.     

Climate-driven bedrock incision in an active mountain belt

Measurements of fluvial bedrock incision were made with submillimeter precision in the East Central Range of Taiwan, where long-term exhumation rates and precipitation-driven river discharge are independently known. They indicate that valley lowering is driven by relatively frequent flows of moderate intensity, abrasion by suspended sediment is an important fluvial wear process, and channel bed geometry and the presence of widely spaced planes of weakness in the rock mass influence erosion rate and style.     

Mantophasmatodea: a new insect order with extant members in the Afrotropics

A new insect order, Mantophasmatodea, is described on the basis of museum specimens of a new genus with two species: Mantophasma zephyra gen. et sp. nov. (one female from Namibia) and M. subsolana sp. nov. (one male from Tanzania). This is the first time since 1914 that a newly described extant insect taxon has proved unplaceable within a recognized order. Mantophasmatodeans are apterous carnivores. Their closest phylogenetic relationships may be to Grylloblattodea (ice-crawlers) and/or Phasmatodea (stick insects), but the morphological evidence is ambiguous. Raptophasma Zompro from Baltic amber is assigned to the Mantophasmatodea, revealing a wider previous range for the lineage.     

A 10,000-year record of Arctic Ocean sea-ice variability--view from the beach

We present a sea-ice record from northern Greenland covering the past 10,000 years. Multiyear sea ice reached a minimum between ~8500 and 6000 years ago, when the limit of year-round sea ice at the coast of Greenland was located ~1000 kilometers to the north of its present position. The subsequent increase in multiyear sea ice culminated during the past 2500 years and is linked to an increase in ice export from the western Arctic and higher variability of ice-drift routes. When the ice was at its minimum in northern Greenland, it greatly increased at Ellesmere Island to the west. The lack of uniformity in past sea-ice changes, which is probably related to large-scale atmospheric anomalies such as the Arctic Oscillation, is not well reproduced in models. This needs to be further explored, as it is likely to have an impact on predictions of future sea-ice distribution.     

Electron transfer-induced dynamics of oxygen molecules on the TiO2(110) surface

Diffusion of oxygen molecules on transition metal oxide surfaces plays a vital role for the understanding of catalysis and photocatalysis on these materials. By means of time-resolved scanning tunneling microscopy, we provide evidence for a charge transfer-induced diffusion mechanism for O2 molecules adsorbed on a rutile TiO2(110) surface. The O2 hopping rate depended on the number of surface donors (oxygen vacancies), which determines the density of conduction band electrons. These results may have implications for the understanding of oxidation processes on metal oxides in general.