Synthesis and physical property characterisation of phosphonium ionic liquids based on P(O)2(OR)2− and P(O)2(R)2− anions with potential application for corrosion mitigation of magnesium alloys

Phosphonium cation based ionic liquids (ILs) have become of interest due to their unique chemical and electrochemical stability as well as their promising tribological properties. At the same time, interest has also grown in the use of phosphate and phosphinate based ionic liquids for corrosion protection of reactive metals. In this work we describe the synthesis and characterization of six novel ionic liquids based on the tetraalkylphosponium cation coupled with organophosphate and organophosphinate anions and their sulfur analogues. The conductivity and viscosity of these ILs has been measured and discussed in terms of the nature of the interactions, effect of anion basicity and the extent of ionic character. The reaction of the IL with a ZE41 magnesium aerospace alloy surface is also demonstrated.

An unified framework based on p-norm for feature aggregation in content- based image retrieval

Feature aggregation is a critical technique in content- based image retrieval systems that employ multiple visual features to characterize image content. In this paper, the p-norm is introduced to feature aggregation that provides a framework to unify various previous feature aggregation schemes such as linear combination, Euclidean distance, Boolean logic and decision fusion schemes in which previous schemes are instances. Some insights of the mechanism of how various aggregation schemes work are discussed through the effects of model parameters in the unified framework. Experiments show that performances vary over feature aggregation schemes that necessitates an unified framework in order to optimize the retrieval performance according to individual queries and user query concept. Revealing experimental results conducted with IAPR TC-12 ImageCLEF2006 benchmark collection that contains over 20,000 photographic images are presented and discussed.

Improved hydrogen monitoring properties based on p-NiO/n-SnO2 heterojunction composite nanofibers

Here we demonstrate the preparation and improved hydrogen monitoring properties based on p-NiO/n-SnO2 heterojunction composite nanofibers via the electrospinning technique and calcination procedure. NiO/SnO2 heterojuction composite nanofibers were spin-coated on the ceramic tube with a pair of Au electrodes for the detection of hydrogen. Extremely fast response−recovery behavior (̰3s) has been obtained at the operable temperature of 320 °C, based on our gas sensor, with the detection limit of approximate 5 ppm H₂. The role of the addition of NiO into the SnO₂ nanofibers and the sensing mechanism has also been discussed in this work.

Use of in vitro critical inhibitory concentration, a novel approach to predict in vivo synergistic bactericidal effect of combined amikacin and piperacillin against pseudomonas aeruginosa in a systemic rat infection model

PURPOSE: This study was undertaken to explore the use of in vitro critical inhibitory concentration (CIC) as a surrogate marker relating the pharmacokinetic (PK) parameters to in vivo bactericidal synergistic effect [pharmacodynamic (PD)] of amikacin + piperacillin combination against Pseudomonas aeruginosa in a systemic rat infection model. METHODS: The in vitro antibacterial activities of amikacin and piperacillin, alone and in combinations at various ratios of the concentrations, were tested against a standard [5 x 10(5) colony-forming units (CFU)/ml] and a large (1.5 x 10(8) CFU/ml) inoculum of P. aeruginosa ATCC 9027 using a modified survival-time method. The CIC of each individual antibiotic for the different combinations was determined using a cup-plate method. In vivo studies were performed on Sprague-Dawley rats using a systemic model of infection with P. aeruginosa ATCC 9027. PK profiles and in vivo killing effects of the combination at different dosing ratios were studied. RESULTS: An inoculum effect was observed with the antibiotics studied. Synergy was seen against both the inocula at the following concentration ratios: 70% C(ami) + 30% C(pip) and 75% C(ami) + 25% C(pip), where C(ami) and C(pip) are the concentrations of amikacin and piperacillin to produce a 1000-fold decrease in bacterial population over 5 h, respectively. The CIC values determined corroborated with the order of in vitro bacterial killing observed for the antibiotic combinations. The dosing ratio of 12.6 mg/kg amikacin + 36 mg/kg piperacillin (a 70:30 ratio of the individual doses) exhibited the greatest killing in vivo when compared to the other ratios. The PK-PD relationships were described by simple, linear regression equations using the area under the in vivo killing curve as a PD marker and the AUCIC(ami)/CIC(ami) + AUCIC(pip)/CIC(pip), AUC(ami)/CIC(ami) + AUC(pip)/CIC(pip), C(max,ami)/CIC(ami) + C(max,pip)/CIC(pip), and AUCIC(ami)/MIC(ami) + AUCIC(pip)/MIC(pip) as PK markers for the amikacin + piperacillin combination. CONCLUSION: The combination of amikacin and piperacillin exhibited synergistic killing effect on P. aeruginosa that could be modeled using CIC as a surrogate marker relating the PK parameters to in vivo bactericidal effect.

Ecology of Pittosporum undulatum Vent. (Pittosporaceae) an environmental weed in south east Australia

Pittosporum undulatum Vent. (Sweet Pittosporum) is a densely foliaged tall shrub or small tree, native to the wet forests of south east Australia, This species now functions as a serious environmental weed in a range of habitats in Australia and on other continents and islands throughout the temperate, sub-tropical and tropical zones. This study investigated some of the ecological causes and consequences of P. undulatum invasion across a range of habitat types in south east Australia. Key aspects of P. undulatum biology and ecology investigated in the current study include; patterns of morphological variation across the range of habitats occupied (as a measure of the species’ plasticity), dispersal ecology and seed germinability, population structure and spatial pattern, community relationships and the ecological impacts of invasion. Phenotypic plasticity is considerable in P. undulatum. No clear patterns of geographic variation emerged from a study of leaf morphological attributes across the current range of this species on mainland south east Australia. The pattern of morphological variation is particularly complex in Victoria, where the invasion of this species is most advanced. The species’ adaptability to a range of environments and environmental conditions will likely promote further range expansion. The abundant winter fruit crop produced by functionally female P. undulatum plants attracts a suite of generalist opportunistic frugivores, which feed on P. undulatum fruits and seeds at various stages of fruit dehiscence, thereby enhancing dispersal opportunities for this species. P. undulatum seed collected from natural and invasive populations, at two stages of fruit maturity and from the scats and pellets of dispersal agents, displayed high germinability. European Blackbirds and Pied Currawongs are implicated as the main avian dispersal agents of P undulatum in south east Australia. The broader ecological implications of developing relationships between invasive fleshy-fruited bird-dispersed plant species and adaptive frugivores are likely to be considerable. The distribution of P. undulatutn seedlings was significantly negatively correlated with adult conspecifics and significantly positively correlated with trees and shrubs of other genera. This pattern reflects the importance of both firugivorous dispersal agents and the species’ germination and establishment requirements, in shaping the contagious distribution pattern typical of this species. These analyses suggest that recruitment opportunities for conspecific seedlings are limited beneath the canopy of adult conspecifics. Densities of P. undulatum were on average, 2.7 times higher in invaded populations, compared to the natural populations sampled. A male-bias was evident in all populations and no relationships between reproductive activity and the density of seedlings and juveniles were evident. Invading populations of P. undulatum impose substantial changes on ecosystem-level properties and functions. Mean species richness and cover-abundance declined notably once P. undulatum cover-abundance exceeded 20% at the invaded sites and 60% at the natural sites sampled. The natural communities sampled displayed comparatively greater resilience to the competitive effects of P. undulatum, but community attributes were affected at high densities and cover-abundance of this species. The cover-abundance of herbs and grasses declined most substantially with increasing P. undulatum at invaded sites, whereas, at the natural sites sampled, the species’ structural analogues appeared to be most affected by increasing P. undulatum cover-abundance. This study has demonstrated that the ecological consequences of P. undulatum population expansion are substantial and contribute to changes in the composition and successional trajectory of affected communities. These processes ultimately lead to the loss and simplification of biodiversity values and the homogenisation of affected habitats. P. undulatum has the potential to emerge as one of south east Australia's most serious environmental weed species.