Analysis of trichome exudate from mite-resistant geraniums

Trichome exudate from mite-resistant geraniums (Pelargonium horlorum) was analyzed, principally by mass spectrometry and NMR spectroscopy. The exudate was found to consist of two anacardic acid derivatives,o-pentadecenylsalicylic acid ando-heptadecenylsalicylic acid. Bioassays established a moderate toxicity of these compounds to the two-spotted spider mite,Tetranychus urticae. The production of these compounds in geraniums was correlated with the two complementary dominant genes previously reported for host resistance to spider mites.     

An Agent-Based Model for Simulating Environmental Behavior in an Educational Organization

Neural Processing Letters - Agent-based modeling (ABM) is an increasingly popular technique for modeling organizations or societies. In this paper, an ABM of environmental decisions in an academic...     

Conservation of Riparian Forest Remnants, West Coast, New Zealand

Riparian forest is a priority for protection in New Zealand. Data are provided on the spatial extent and distribution of riparian forest and forest remnants within the West Coast region of New Zealand. Despite the West Coast having the bulk of New Zealand's riparian forest, such forests are under-represented in many of the region's Ecological Districts. Lack of other suitable soils meant that, where possible, floodplains were extensively developed for agriculture. Consequently riparian forest remnants within farmland are small and isolated. The implications of ecological processes and land-management practices for the conservation management of the riparian forest remnants are discussed, and three conservation priorities are identified.     

Effect of ethanol on BTEX biodegradation kinetics: aerobic continuous culture experiments

The use of ethanol as an automotive fuel oxygenate represents potential economic and air-quality benefits. However, little is known about how ethanol may affect the natural attenuation of petroleum product releases. Chemostat experiments were conducted with four pure cultures (representing archetypes of the known aerobic toluene degradation pathways) to determine how ethanol affects benzene, toluene, ethylbenzene, and xylene (BTEX) biodegradation kinetics. In all cases, the presence of ethanol decreased the metabolic flux of toluene (measured as the rate of toluene degradation per cell). This negative effect was counteracted by an ethanol-supported increase in biomass, which is conducive to faster degradation rates. When the influent total organic carbon (TOC) of the toluene-ethanol mixture was kept constant, the metabolic flux of toluene was proportional to its relative contribution to the influent TOC. This empirical relationship was used to derive a mathematical model that simulated effluent benzene concentrations as a function of the influent mixed-substrate composition, the dilution rate, and Monod kinetic coefficients. Under carbon-limiting conditions (1 mg/L influent benzene), the data and model simulations showed an increase in benzene removal efficiency when ethanol was fed at low concentrations (ca. 1 mg/L) because its positive effect on cell growth outweighed its negative effect on the metabolic flux of benzene. High ethanol concentrations, however, had a negative effect, causing oxygen limitation and increasing effluent benzene concentrations to higher levels than when benzene was fed alone. The slower BTEX degradation rates expected at sites with high ethanol concentrations (e.g., at gasohol-contaminated sites) could result in longer BTEX plumes and a greater risk of exposure.     

Integrating tools for longwall geomechanics assessment

Issues associated with longwall geomechanics are complex and any approach that attempts to characterise or design for it needs to account for this complexity. Operating mines have requirements for the safety of their workforce and for production continuity. Incorrect characterisation of longwall geomechanics is a significant risk to both of these core objectives. A multi-path approach in which there is corroboration and cross checking of outcomes during design and characterisation is required to reduce this risk. Single method approaches for issues, such as longwall geometry or face strata control management plans, have no place in this environment.Over the past 6 years, the CSIRO has conducted research into longwall geomechanics at 13 sites both for assessment of potential issues and to establish causal factors of site problems that have occurred. A variety of assessment tools have been used in these case studies including microseismic monitoring, numerical stress deformation modelling, various underground monitoring methods and 3D visualisation.Whilst the reporting of these studies has concentrated on geomechanics issues, both the development of the assessment tools and their use in combination are also important topics. Often the results of these studies have been unexpected and new insights have only been gained and validated with consideration of results from several independent assessment tools. This consideration is also worth discussion as it has its basis in formal problem analyses tools.Using the case studies as a background and canvas, this paper concentrates on the use and status of these assessment tools and their required future development.     

Interaction of Sprinklers with Smoke and Heat Vents

There has been an ongoing controversy about the use of sprinklers and smoke/heat vents together, and dozens of position papers have been published over the decades. This paper reviews 13 experimental studies that have some relevance to the claims posed for and against the combined use of sprinklers and smoke/heat vents. These studies are used to evaluate the positive and negative claims that have been made with regard to the combined use of sprinklers and smoke/heat vents. Three of the studies investigate the use of smoke/heat vents alone. Four investigations include sprinklers, but do not include roof vents. Three of these are test series in which perimeter vents were used in the test facility, and the fourth included sprinklers, a partial draft curtain, and no smoke/heat vents. Four test series included sprinklers, smoke/heat vents, and draft curtains, but utilized spray or pool fires which were not subject to extinguishment by the sprinklers. Four test series included sprinklers, smoke/heat vents, draft curtains, and used Class A fuels which were subject to extinguishment.The studies of smoke and heat venting used in conjunction with sprinklers show clearly that venting does not have a negative effect on sprinkler performance. Experimental studies have shown that venting does limit the spread of products of combustion by releasing them from the building within the curtained compartment of fire origin. This improves visibility for building occupants and firefighters who need to find the seat of the fire to complete fire extinguishment. Limiting the spread of smoke and heat also reduces smoke and heat damage to the building. In the event that sprinklers do not operate, venting remains a valuable aid to manual control of the fire.The experimental studies have shown that early vent activation has no detrimental effects on sprinkler performance and have also shown that current design practices are likely to limit the number of vents operated to one and vents may in fact not operate at all in very successful sprinkler operations. Design practices should move to methods that assure early operation of vents, and vent operation should be ganged so that the benefit of roof vents is fully realized. Sprinkler design with vents and draft curtains needs to take full account of draft curtains as obstructions. Curtains should be placed in aisles rather than over storage.     

Potentiometric determination of acid dissociation constants (pKa) for human and veterinary antibiotics

This work determined the acid dissociation constants (pKa) of 26 common human and veterinary antibiotics by potentiometric titration. Selected antibiotics consisted of sulfonamides, macrolides, tetracyclines, fluoroquinolones, and other miscellaneous antibiotics. After validation of analysis methods using phosphoric acid as a model compound, a second-derivative (delta2pH/deltaV2) method was primarily applied to determining pKa's from titration curves for most antibiotics due to its convenience and accuracy. For tetracyclines, however, a least-square non-linear regression method was developed to determine their pKa's because the second-derivative method cannot well distinguish the pKa,2 and pKa,3 of tetracyclines. Results indicate that the pKa values are approximately 2 and 5-7.5 for sulfonamides; 7.5-9 for macrolides; 3-4, 7-8 and 9-10 for tetracyclines; 3-4, 6, 7.5-9 and 10-11 for fluoroquinolones; while compound-specific for other miscellaneous antibiotics. The moieties corresponding to specific pKa's were identified based on chemical structures of antibiotics. In addition, the pKa's available in literature determined by various techniques are compiled in comparison with the values of this work. These results are expected to essentially facilitate the research on occurrence, fate and effects, analysis methods development, and control of antibiotics in various treatment operations.