Study of hydrogen peroxide,potato enzymes and blackspot

The rate of oxidation of tyrosine, p-cresol and catechol by potato enzyme diminished as H₂O₂ concentration increased. By contrast, the rate of oxidation of chlorogenic acid in the presence of H₂O₂ increased. Bovine catalase destroyed H₂O₂ and thus effectively prevented either H₂O₂-induced inhibition or acceleration of oxidation of the four substrates by potato enzyme. Horseradish peroxidase in the presence of H₂O₂ did not oxidize either monophenol, but oxidized both polyphenols. Possible association of H₂O₂, peroxidase and catalase with blackspot susceptibility is discussed.     

A simple device for respiratory resuscitation of newborn calves and lambs

The neonatal death of calves and lambs is responsible for a heavy financial loss to the farming industry; respiratory failure accounts for 6 per cent of the post parturient deaths in lambs. A simple method of pulmonary resuscitation with expired air is described employing a device portable and simple enough for emergency use by herdsmen and shepherds. The rationale of the use of the equipment is explained.     

Comparing deep drainage estimated with transient and steady state assumptions in irrigated vertisols

Chloride mass balance (steady state or transient state) models are used extensively in Vertisols of Queensland and New South Wales (NSW) in Australia to estimate deep drainage. The aim of this study was to compare deep drainage estimated assuming steady state and transient state conditions with chloride mass balance models in irrigated cotton (Gossypium hirsutum L.)-based farming systems in the lower Namoi Valley of North Western NSW. Drainage was estimated at seven sites, and treatments included rotation crops such as wheat (21–62 mm/year) (Triticum aestivum), sorghum (12–47 mm/year) (Sorghum bicolor) and dolichos (12–21 mm/year) (Lablab purpureus), minimum tillage (62–83 mm/year), where cotton was sown into standing wheat stubble, and conventional tillage where stubble was incorporated (35–78 mm/year). Soil water content was measured with a neutron moisture meter in the 0.2–1.2 m depth. Soil was sampled before sowing and after harvest to a depth of 1.2 m along diagonal transects. The soil chloride concentration was determined by titration with AgNO₃. Irrigation water was also analysed for chloride. The deep drainage estimates were compared using regression analysis and students paired t-test. In addition, a paired t-test of the soil chloride concentration before sowing and after harvest was used to determine if the soil chloride flux was either in a steady state or transient state. In 9 out of the 13 data sets (69%), drainage estimated with the models agreed with changes between pre- and post-season soil chloride concentrations. Under frequently irrigated summer crops such as cotton and sorghum and in better structured soils chloride flux reached steady state conditions whereas under partially-irrigated crops or where soil structure was poorer, the chloride flux deviated markedly from steady-state conditions. The latter observation may be due to preferential flow via deep cracks in infrequently irrigated soil. Deep cracking would be due to the more intense shrinking and swelling in partially irrigated soil in comparison with frequently-irrigated crops. Comparison of estimated deep drainage with pre- and post-season soil chloride concentrations showed that the steady state mass balance model best estimated deep drainage under cotton crops which were irrigated more frequently or wheat crops which had better soil structure.

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Skeleton of Euplectella sp.: structural hierarchy from the nanoscale to the macroscale

Structural materials in nature exhibit remarkable designs with building blocks, often hierarchically arranged from the nanometer to the macroscopic length scales. We report on the structural properties of biosilica observed in the hexactinellid sponge Euplectella sp. Consolidated, nanometer-scaled silica spheres are arranged in well-defined microscopic concentric rings glued together by organic matrix to form laminated spicules. The assembly of these spicules into bundles, effected by the laminated silica-based cement, results in the formation of a macroscopic cylindrical square-lattice cagelike structure reinforced by diagonal ridges. The ensuing design overcomes the brittleness of its constituent material, glass, and shows outstanding mechanical rigidity and stability. The mechanical benefits of each of seven identified hierarchical levels and their comparison with common mechanical engineering strategies are discussed.     

Mineralization of carbon and nitrogen from cowpea leaves decomposing in soils with different levels of microbial biomass

Soils with greater levels of microbial biomass may be able to release nutrients more rapidly from applied plant material. We tested the hypothesis that the indigenous soil microbial biomass affects the rate of decomposition of added green manure. Cowpea (Vigna unguiculata L.) Walp.] leaves were added to four soils with widely differing microbial biomass C levels. C and N mineralization of the added plant material was followed during incubation at 30°C for 60 days. Low levels of soil microbial biomass resulted in an initially slower rate of decomposition of soil-incorporated green manure. The microbial biomass appeared to adjust rapidly to the new substrate, so that at 60 days of incubation the cumulative C loss and net N mineralization from decomposing cowpea leaves were not significantly affected by the level of the indigenous soil microbial biomass.     

Uranium stabilization of c28: a tetravalent fullerene

Laser vaporization experiments with graphite in a supersonic cluster beam apparatus indicate that the smallest fullerene to form in substantial abundance is C(28). Although ab initio quantum chemical calculations predict that this cluster will favor a tetrahedral cage structure, it is electronically open shell. Further calculations reveal that C(28) in this structure should behave as a sort of hollow superatom with an effective valence of 4. This tetravalence should be exhibited toward chemical bonding both on the outside and on the inside of the cage. Thus, stable closed-shell derivatives of C(28) with large highest occupied molecular orbital-lowest unoccupied molecular orbital gaps should be attainable either by reacting at the four tetrahedral vertices on the outside of the C(28) cage to make, for example, C(28)H(4), or by trapping a tetravalent atom inside the cage to make endothedral fullerenes such as Ti@C(28). An example of this second, inside route to C(28) stabilization is reported here: the laser and carbon-arc production of U@C(28).     

Jupiter's nightside airglow and aurora

Observations of Jupiter's nightside airglow (nightglow) and aurora obtained during the flyby of the New Horizons spacecraft show an unexpected lack of ultraviolet nightglow emissions, in contrast to the case during the Voyager flybys in 1979. The flux and average energy of precipitating electrons generally decrease with increasing local time across the nightside, consistent with a possible source region along the dusk flank of Jupiter's magnetosphere. Visible emissions associated with the interaction of Jupiter and its satellite Io extend to a surprisingly high altitude, indicating localized low-energy electron precipitation. These results indicate that the interaction between Jupiter's upper atmosphere and near-space environment is variable and poorly understood; extensive observations of the day side are no guide to what goes on at night.