Isolation and Characterisation of Bacterial Metabolites as Potential Wood Preservatives

The durability of wood has traditionally relied on the use of heavy metals and toxic compounds to deter wood degrading fungi. Conventional wood preservatives such as Chromated Copper Arsenate (CCA) have been widely used to control wood degrade for many decades, however public pressure over perceived environmental and health risks have led to recent restrictions for use in some countries. This issue has focused the need for research towards environmentally friendly (benign) wood preservatives including compounds such as plant extractives and microbial metabolites. Previously chilli waste has been shown to have moderate antifungal activity against common wood sapstain fungi. Furthermore, Lactobacillus sp. isolated from chilli showed synergistic activity with chilli against these fungi. The intention of this study was to further develop this work, by isolating and identifying the range of bacteria from chilli waste, screening for antifungal activity against wood decay fungi then investigating any possible synergy between the isolates and chilli waste. Initially a quick screening 96-well optical density assay was optimised which allowed the screening of lactic acid bacterial metabolites against wood decay fungi. This technique proved to be comparable to a commonly used growth rate method and has potential as a standard initial screening method in the laboratory. Seven isolates from chilli juice had an antifungal effect on the wood decay fungus Oligoporus placenta and were identified using 16S rRNA phylogenetic techniques as Lactobacillus brevis, Leuconostoc mesenteroides subsp. mesenteroides (three isolates), L. mesenteroides subsp. cremoris, L. pseudomesenteroides and Gluconobacter oxydans. Cell-free supernatants of these isolates were used to treat wood blocks which were then exposed to wood decay fungi. L. brevis metabolites showed the greatest inhibition of wood decay and were identified as lactic and acetic acids by high performance liquid chromatography (HPLC) amongst other techniques. The media in which the bacteria were grown also had an antifungal effect on wood decay fungi most likely due to its hygroscopicity increasing wood moisture content to a point inhibitory to decay fungi. Synergy between the bacterial metabolites and chilli juice was examined using the optical density assay and it was discovered that two bacteria showed complete inhibition of decay fungi when grown in chilli juice. However, when subjected to a wood assay, both L. brevis and L. mesenteroides subsp. cremoris did not give satisfactory control of decay fungi suggesting the main mechanism of fungal inhibition was due to increased moisture content of wood induced by the specific media initially used in this study. Further research should determine whether the isolated bacteria can be induced to increase metabolite production and if this would improve antifungal activity. Ultimately these bacterial metabolites and chilli combined or alone, may not be suitable for long term protection against wood decay, but may provide a solution to other fungal degradation issues

Global health education in U.S. medical schools.

Interest in global health (GH) among medical students worldwide is measurably increasing. There is a concomitant emphasis on emphasizing globally-relevant health professions education. Through a structured literature review, expert consensus recommendations, and contact with relevant professional organizations, we review the existing state of GH education in US medical schools for which data were available. Several recommendations from professional societies have been developed, along with a renewed emphasis on competencies in global health. The implementation of these recommendations was not observed as being uniform across medical schools, with variation noted in the presence of global health curricula. Recommendations for including GH in medical education are suggested, as well as ways to formalize GH curricula, while providing flexibility for innovation and adaptation.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are

Updating the Finite Element Model of the Aerostructures Test Wing Using Ground Vibration Test Data

Improved and/or accelerated decision making is a crucial step during flutter certification processes. Unfortunately, most finite element structural dynamics models have uncertainties associated with model validity. Tuning the finite element model using measured data to minimize the model uncertainties is a challenging task in the area of structural dynamics. The model tuning process requires not only satisfactory correlations between analytical and experimental results, but also the retention of the mass and stiffness properties of the structures. Minimizing the difference between analytical and experimental results is a type of optimization problem. By utilizing the multidisciplinary design, analysis, and optimization (MDAO) tool in order to optimize the objective function and constraints; the mass properties, the natural frequencies, and the mode shapes can be matched to the target data to retain the mass matrix orthogonality. This approach has been applied to minimize the model uncertainties for the structural dynamics model of the aerostructures test wing (ATW), which was designed and tested at the National Aeronautics and Space Administration Dryden Flight Research Center (Edwards, California). This study has shown that natural frequencies and corresponding mode shapes from the updated finite element model have excellent agreement with corresponding measured data

Inhomogeneity of the ultrafast insulator-to-metal transition dynamics of VO2

The insulator-metal transition (IMT) of vanadium dioxide (VO2) has remained a long-standing challenge in correlated electron physics since its discovery five decades ago. Most interpretations of experimental observations have implicitly assumed a homogeneous material response. Here we reveal inhomogeneous behaviour of even individual VO2 microcrystals using pump-probe microscopy and nanoimaging. The timescales of the ultrafast IMT vary from 40±8 fs, that is, shorter than a suggested phonon bottleneck, to 200±20 fs, uncorrelated with crystal size, transition temperature and initial insulating structural phase, with average value similar to results from polycrystalline thin-film studies. In combination with the observed sensitive variations in the thermal nanodomain IMT behaviour, this suggests that the IMT is highly susceptible to local changes in, for example, doping, defects and strain. Our results suggest an electronic mechanism dominating the photoinduced IMT, but also highlight the difficulty to deduce microscopic mechanisms when the true intrinsic material response is yet unclear