1,643 research outputs found

    Large-scale molecular dynamics simulation of magnetic properties of amorphous iron under pressure

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    Author name used in this publication: C. H. Woo2006-2007 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

    Dynamic Failure Properties of the Porcine Medial Collateral Ligament-Bone Complex for Predicting Injury in Automotive Collisions

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    The goal of this study was to model the dynamic failure properties of ligaments and their attachment sites to facilitate the development of more realistic dynamic finite element models of the human lower extremities for use in automotive collision simulations. Porcine medial collateral ligaments were chosen as a test model due to their similarities in size and geometry with human ligaments. Each porcine medial collateral ligament-bone complex (n = 12) was held in a custom test fixture placed in a drop tower to apply an axial impulsive impact load, applying strain rates ranging from 0.005 s-1 to 145 s-1. The data from the impact tests were analyzed using nonlinear regression to construct model equations for predicting the failure load of ligament-bone complexes subjected to specific strain rates as calculated from finite element knee, thigh, and hip impact simulations. The majority of the ligaments tested failed by tibial avulsion (75%) while the remaining ligaments failed via mid-substance tearing. The failure load ranged from 384 N to 1184 N and was found to increase with the applied strain rate and the product of ligament length and cross-sectional area. The findings of this study indicate the force required to rupture the porcine MCL increases with the applied bone-to-bone strain rate in the range expected from high speed frontal automotive collisions

    Production and optimization of alkalostable lipase by alkalophilic Burkholderia cenocepacia ST8

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    A superior lipase-producing bacterium was isolated from forest soil samples in Setapak, Malaysia and it was identified as Burkholderia cenocepacia with 16S rRNA sequencing technique. Multifactor experimental design based on ‘change-one-factor-at-a-time’ approach was employed to optimize the production of Bukholderia lipase with submerged fermentation technique. Effects of carbon and nitrogen sources, metal ions as well as initial pH of medium on lipase production were extensively investigated. Optimal lipase activity was achieved in medium using combination of sunflower oil and Tween 80 (1% v/v each) as carbon sources. Simple sugars such as glucose and fructose, however, did not promote the production of lipase. Peptone (from meat) at 0.33% (w/v) was the most suitable nitrogen source for lipase production by this Gram-negative bacterium. The presence of Ca2+ in the cultivation medium possessed significant effect on lipase production while Mg2+, Mn2+, Na+, Fe2+, Cu2+ and Co2+ exhibited inhibitory effect towards the enzyme production. Initial culture pH in the range of 5 to 11 were found suitable for lipase production, with the maximum level of lipase activity recorded in the medium with initial culture pH of 9.0.Key words: Alkalostable lipase, alkalophilic Burkholderia cenocepacia, optimization, multifactor experimental design

    PTA and stenting in supra-aortic arch arteries

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    Spin-lattice-electron dynamics simulations of magnetic materials

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    Author name used in this publication: C.H. Woo2011-2012 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

    Segregation of voids in a spatially heterogeneous dislocation microstructure

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    Author name used in this publication: C. H. Woo2004-2005 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

    Large-scale simulation of the spin-lattice dynamics in ferromagnetic iron

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    Author name used in this publication: C. H. Woo2008-2009 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

    Heterogeneous void swelling near grain boundaries in irradiated materials

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    Author name used in this publication: C. H. Woo2002-2003 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

    Temperature for a dynamic spin ensemble

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    Author name used in this publication: C. H. Woo2010-2011 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

    Trichoderma atroviride P1 Colonization of Tomato Plants Enhances Both Direct and Indirect Defense Barriers Against Insects

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    Numerous microbial root symbionts are known to induce different levels of enhanced plant protection against a variety of pathogens. However, more recent studies have demonstrated that beneficial microbes are able to induce plant systemic resistance that confers some degree of protection against insects. Here, we report how treatments with the fungal biocontrol agent Trichoderma atroviride strain P1 in tomato plants induce responses that affect pest insects with different feeding habits: the noctuid moth Spodoptera littoralis (Boisduval) and the aphid Macrosiphum euphorbiae (Thomas). We observed that the tomato plant–Trichoderma P1 interaction had a negative impact on the development of moth larvae and on aphid longevity. These effects were attributed to a plant response induced by Trichoderma that was associated with transcriptional changes of a wide array of defense-related genes. While the impact on aphids could be related to the up-regulation of genes involved in the oxidative burst reaction, which occur early in the defense reaction, the negative performance of moth larvae was associated with the enhanced expression of genes encoding for protective enzymes (i.e., Proteinase inhibitor I (PI), Threonine deaminase, Leucine aminopeptidase A1, Arginase 2, and Polyphenol oxidase) that are activated downstream in the defense cascade. In addition, Trichoderma P1 produced alterations in plant metabolic pathways leading to the production and release of volatile organic compounds (VOCs) that are involved in the attraction of the aphid parasitoid Aphidius ervi, thus reinforcing the indirect plant defense barriers. Our findings, along with the evidence available in the literature, indicate that the outcome of the tripartite interaction among plant, Trichoderma, and pests is highly specific and only a comprehensive approach, integrating both insect phenotypic changes and plant transcriptomic alterations, can allow a reliable prediction of its potential for plant protectio
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