Distribution of matter in the current-carrying plasma and dense core of the discharge channel formed upon electrical wire explosion

Distribution of matter in the discharge channel formed upon a nanosecond electrical explosion of a single wire in air and vacuum was studied experimentally. Simultaneous use of optical, UV, and X-ray diagnostics made it possible to distinguish qualitatively different regions of the discharge channel, such as the current-carrying layers and the region occupied by a weakly conducting cold plasma. Several series of experiments with 25-μm-diameter 12-mm-long wires made of different materials were performed. The charging voltage and the current amplitude were varied in the ranges of U ₀ = 10–20 kV and I _max ∼ 5–10 kA, respectively. Explosion regimes with a current pause and with and without current interruption, as well as with wire preheating in air and vacuum, were studied. Shadow and schlieren images of the discharge channel were obtained using optical probing at the second harmonic of a YAG: Nd⁺³ laser (λ = 0.532 μm, τ ∼ 10 ns). In the experiments carried out in vacuum, X-ray images of the discharge channel were also obtained using an X-pinch as a point source of probing radiation and UV images were recorded using a four-frame MCP camera.     

The first vitamin B6 zinc complex, pyridoxinato-zinc acetate: A 1D coordination polymer with polar packing through strong inter-chain hydrogen bonding

The biologically important pyridoxinato(1−) ligand (anionic vitamin B₆) shows the rare phenolate-hydroxymethyl chelation plus bridging mode through the pyridine-nitrogen atom towards zinc(II) to give the one-dimensional (1D) coordination polymer {(acetato-κO)-aqua-μ-[2-methyl-3-oxy-4,5-di(hydroxymethyl)pyridine-κN:O,O′]zinc(II)}·monohydrate with polar packing of adjacent chains along the polar c axis (in space group Pc) through strong inter-chain hydrogen bonding.     

Ca2+ channel antagonist actions in bladder smooth muscle: comparative pharmacologic and [3H]nitrendipine binding studies

The actions of a series of 15 Ca2+ channel antagonists including D-600, nifedipine, and diltiazem were examined against K+ depolarization and muscarinic receptor induced responses in guinea pig bladder smooth muscle. Responses of bladder are very dependent upon extracellular Ca2+ and sensitive to the Ca2+ channel antagonists, the tonic component more than the phasic component of response. Regardless of stimulant, K+ or methylfurmethide (MF), or component of response, the same rank order of antagonist activities is expressed, suggestive of a single structure-activity relationship and the existence of a single category of binding site which may, however, exist in several affinity states. High affinity binding of [3H]nitrendipine (KD = 1.1 X 10(-10) M) occurs in bladder membranes, and similar high affinity binding was found in microsomal preparations from other smooth muscles including guinea pig and rat lung, rat vas deferens, uterus, and stomach. [3H]nitrendipine binding in the bladder was sensitive to displacement by other 1,4-dihydropyridines, paralleling their pharmacologic activities and showing excellent agreement with binding data previously obtained for guinea pig ileal smooth muscle. Comparison of pharmacologic data for inhibition of K+- and MF-induced responses by a common series of Ca2+ channel antagonists in bladder and ileum revealed excellent correlations. Neither pharmacologic nor binding studies suggest significant differences in Ca2+ channel antagonist properties in smooth muscle from bladder and intestine.     

Preference and performance of Lepidoptera varies with tree age in juniper woodlands

1. As trees age, they undergo significant physiological and morphological changes. Nevertheless, tree ontogeny and its impacts on herbivores are often overlooked as determinants of plant–herbivore population dynamics and the strength of plant–herbivore interactions. 2. Juniperus (Cupressaceae) is a dominant, long‐lived conifer that serves as the sole host to a specialised assemblage of caterpillars. Over the past 150 years, several juniper species in western North America have expanded their geographic occupancy at local and regional scales, which has resulted in an increase in the number of immature trees on the landscape. Using assays in the laboratory, the effects of tree ontogeny on caterpillar performance and oviposition preference for two juniper specialist caterpillars, Callophrys gryneus (Lycaenidae) and Glena quinquelinearia (Geometridae), were examined. The study considered whether responses to tree ontogeny were consistent across caterpillar species and juniper host species. 3. Tree age was found to be a reliable predictor of caterpillar performance, with caterpillars developing more quickly and growing larger when fed foliage from young trees. Differences in the phytochemical diversity between foliage from trees of different ages might help to explain observed differences in caterpillar performance. Interestingly, the specialist butterfly, C. gryneus, displayed an oviposition preference for foliage from old‐growth Juniperus osteosperma trees, despite the fact that larvae of this species performed poorly on older trees. 4. It is concluded that young juniper trees are an important resource for the specialised Lepidopteran community and that tree ontogeny is an important component of intraspecific variation, which contributes to the structure of plant–herbivore communities.     

The detection of fish pathogenVibrio anguillarum in water and fish using a species-specific DNA probe combined with membrane filtration

The marine bacteriumVibrio anguillarum causes disease in fish worldwide and is particularly devastating in aquaculture. Little is known about the ecology ofV. anguillarum in the environment and how this may relate to the pathogenicity of this organism. Combining membrane filtration and a species-specific DNA probe, culturableV. anguillarum cells were detected in water from three habitats and in chinook salmon (Onchorynchus tshawytscha) tissue samples. Results show that different marine habitats have a marked effect on cell numbers and that water temperature may play a role in the culturability and distribution ofV. anguillarum. Vibrio anguillarum was detected from the gills of salmon within 24 h of transfer of fingerlings from freshwater to seawater, with cell numbers reaching a concentration of 1.9 × 10² cells g^–1 tissue 28 days post transfer.Vibrio anguillarum cell numbers were low in the colon throughout the study, andV. anguillarum was not detected in healthy kidney samples. The methodology reported in this paper allows the accurate quantification of culturableV. anguillarum cells and has allowed a preliminary study of the ecology of this species.     

Development of a DNA probe using differential hybridization to detect the fish pathogenVibrio anguillarum

The fish pathogenVibrio anguillarum causes significant economic losses in commercially cultured fish species worldwide. At present, identification ofV. anguillarum requires conventional isolation and culturing techniques. Using differential hybridization, a 310 base pairV. anguillarum-specific DNA fragment was isolated for use as a probe. In specificity studies against 19 different bacterial species, including twoVibrio sp. and fish pathogens, and 223 marine bacterial isolates, the probe hybridized exclusively toV. anguillarum strains. The probe also strongly hybridizes to 7 of 9 serotypes tested, with serotype 09 giving a weak probe reaction and serotype O7 negative. The probe allows rapid and accurate detection of both pathogenic and environmental strains ofV. anguillarum.