Liquid carbon, carbon-glass beads, and the crystallization of carbon nanotubes

The formation of carbon nanotubes in a pure carbon arc in a helium atmosphere is found to involve liquid carbon. Electron microscopy shows a viscous liquid-like amorphous carbon layer covering the surfaces of nanotube-containing millimeter-sized columnar structures from which the cathode deposit is composed. Regularly spaced, submicrometer-sized spherical beads of amorphous carbon are often found on the nanotubes at the surfaces of these columns. Apparently, at the anode, liquid-carbon drops form, which acquire a carbon-glass surface due to rapid evaporative cooling. Nanotubes crystallize inside the supercooled, glass-coated liquid-carbon drops. The carbon-glass layer ultimately coats and beads on the nanotubes near the surface.     

Environmental and Varietal Influences on the Fatty Acid Composition of Rapeseed, Soybeans and Sunflowers

The fatty acid (FA) composition of oil crops is of some importance under technological as well as under nutritional aspects. The influence of temperature on this parameter in rapeseed, soybeans and sunflowers was investigated under practical agricultural conditions, whereby varietal variations were taken into account. The analysed plant material originated from variety testing trials located in different climatic zones of Austria. As a measure of the climatic conditions of a location, the mean temperature of the last 30 days before harvest was calculated. Despite the low temperature differences between the various locations, moderate but significant negative correlations between temperature and the share of linolenic (18 : 3), respectively, linoleic (18 : 2) acid on the whole quantity of FAs in rapeseed (R² = 0.18–0.42), soybeans (R² = 0.11–0.13) and sunflowers (R² = 0.15) were found. Furthermore, there was a good negative correlation in the case of sunflower seeds between temperature and oil level (R² = 0.45). The environmental influence on the share of polyunsaturated FAs differed between the different species. The results show that quality of vegetable oils is as well a question of environment as of variety.     

Phosphinate inhibition studies of cholinesterases

The kinetic constants, K_d, k₂, and k_i, were determined for the inhibition by 4-nitro-phenyl methyl(phenyl)phosphinate of three cholinesterases: butyrylcholinesterase, bovine erythrocyte acetylcholinesterase and eel acetylcholinesterase. Stopped-flow kinetic evaluations and automated data acquisition and processing were employed. A broad range in affinity for the phosphinate inhibitor was observed as reflected by the binding constants, K_d. A similar wide range in the k₂ values for the unimolecular inhibition step was obtained. The net bimolecular rate constants, ki, indicate equal overall reactivity for butyrylcholinesterase and eel acetylcholinesterase with a smaller inhibition rate constant for bovine erythrocyte acetylcholinesterase.     

Maasai perception of the impact and incidence of malignant catarrhal fever (MCF) in southern Kenya

We investigated the perceived impact of malignant catarrhal fever (MCF) to pastoralists in Isinya Division, a wildlife dispersal area of Nairobi National Park, and used a range of participatory epidemiology methodologies. We compared the relative importance, incidence and impact of MCF compared to other locally defined important diseases with a total of 158 respondents in 11 group meetings and 21 household meetings in July 2004. Direct losses due to disease were investigated through lowered prices as a result of the emergency sale of disease-infected animals.

Overall, Maasai in Isinya Division perceived east coast fever (ECF) to be the most important cattle disease and to have the highest incidence. Anthrax was considered to have the largest impact. In areas within or adjacent to the wildebeest calving zone, MCF was perceived to be the most important cattle disease and also to have the largest impact. Outside the calving zone, MCF was considered the fourth-most important disease with the fourth largest impact, and these were areas where wildebeest were less common. MCF was also the fourth-most common disease, and across the Division incidence was estimated at 5% in calves and 10% in adults. However, MCF incidence varied greatly throughout the study area, from 3% to 12%, and the highest incidence risks were found in areas where wildebeest came to calve. The percent drop in sale price per animal infected with MCF was estimated at 50% for MCF for the year 2003–2004.

Forced avoidance movements away from wildebeest calves were reported to decrease livestock production due to loss of access to prime grazing sites. As suggested by pastoralists in this study, the development of compensation schemes or incentives from wildlife would reduce the conflict between livestock keeping and wildlife conservation.     

Characterisation of Non-Autoinducing Tropodithietic Acid (TDA) Production from Marine Sponge Pseudovibrio Species

The search for new antimicrobial compounds has gained added momentum in recent years, paralleled by the exponential rise in resistance to most known classes of current antibiotics. While modifications of existing drugs have brought some limited clinical success, there remains a critical need for new classes of antimicrobial compound to which key clinical pathogens will be naive. This has provided the context and impetus to marine biodiscovery programmes that seek to isolate and characterize new activities from the aquatic ecosystem. One new antibiotic to emerge from these initiatives is the antibacterial compound tropodithietic acid (TDA). The aim of this study was to provide insight into the bioactivity of and the factors governing the production of TDA in marine Pseudovibrio isolates from a collection of marine sponges. The TDA produced by these Pseudovibrio isolates exhibited potent antimicrobial activity against a broad spectrum of clinical pathogens, while TDA tolerance was frequent in non-TDA producing marine isolates. Comparative genomics analysis suggested a high degree of conservation among the tda biosynthetic clusters while expression studies revealed coordinated regulation of TDA synthesis upon transition from log to stationary phase growth, which was not induced by TDA itself or by the presence of the C10-acyl homoserine lactone quorum sensing signal molecule.