Browsing by Author "Lu, M. -C."

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Correlation between Klebsiella pneumoniae carrying pLVPK-derived loci and abscess formation
(2010-06-01)
Tang, H. -L.
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Chiang, M. -K.
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Liou, W. -J.
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Chen, Y. -T.
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Peng, H. -L.
Klebsiella pneumoniae-caused liver abscess (KLA) is an emerging infectious disease. However, factors other than K1-specific loci that contribute to the pathogenesis of this disease have not been identified. pLVPK is a 219,385-bp plasmid of K. pneumoniae CG43, an invasive K2 strain associated with KLA. We aimed in this study to evaluate the involvement of pLVPK in K. pneumoniae virulence and its clinical significance in abscess formation. A pLVPK-cured CG43 was isolated and its virulence was examined in a mouse model. The prevalence of pLVPK-derived loci terW, iutA, rmpA, silS, and repA was investigated in 207 clinical isolates by screening with specific primers. Loss of pLVPK abolished the ability of K. pneumoniae to disseminate into extraintestinal sites and, consequently, attenuated abscess formation in mice. Primary K. pneumoniae abscess isolates (n = 94) were more likely to be terW (+)-iutA (+)-rmpA (+)-silS (+) than those related to non-abscess infections (n = 113) (62% vs. 27%; p < 0.0001). Logistic regression analysis indicated that the presence of the terW-rmpA-iutA-silS loci was a significant risk factor (odds ratio, 4.12; 95% confidence interval, 2.02-8.4; p < 0.0001) for abscess formation. pLVPK is a determinant for K. pneumoniae virulence and infection with strains carrying the pLVPK-derived terW-rmpA-iutA-silS loci may predispose patients to abscess formation.
Effects of high shear rate shearing on material structure and mechanical property of iPP/PC blends
(2008-02-01)
Lu, M. -C.
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Chen, R. -H.
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Chi, K. -H.
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機械工程學系
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Department of Mechanical Engineering
Polycarbonate (PC) and crystalline polymer, isotatic polypropylene (iPP), are extruded using a mechanical blending extruder and a reciprocated mechanism for shearing is designed to perform long term shearing at a high shear rate in the packing stage. The present work investigates the effects of high shear rate shearing on the orientation of the phase morphologies and mechanical properties. The experiment utilises the technologies of specimen preparation and observation to examine the change in phase morphology. Additionally, the mechanical properties of injection moulded specimens under different processing conditions are measured. Experimental results show that adding a little PC into the iPP matrix, less than around 20%, increases the tensile strength of specimens. The orientation of the phase is improved and most of the tensile strength of the blends is increased after shearing. The tensile strength of the shearing specimens with a PC content of,25% exceeds that of the normal specimens of pure iPP. A higher iPP content corresponds to a higher tensile strength after shearing. This investigation also considers the possibility of using iPP/PC blends in industrial applications, indicating that shearing is valuable in industrial applications when the PC content in iPP/PC blends is 25%.