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Melt Rheology of Binary Blends of Metallocene Polyethylene with Conventional Polyolefins
Choe, Soon ja,Rana, Dipak,Kwak, Han Jin 한국공업화학회 2000 Journal of Industrial and Engineering Chemistry Vol.6 No.2
The melt rheology of the binary blends of metallocene polyethylene (MCPE) (polyethylene synthesized by metallocene catalyst) with conventional polyolefins prepared using the Ziegler-Natta catalyst was investigated. The blend pairs are MCPE with high density polyethylene (MCPE-HDPE), polypropylene (MOPE-PP), polypropylene-co-ethylene) (MCPE-CoPP), and poly(propylene-co-ethylene-co-l-butylene) (MOPE-TerPP). The analysis was based on three methods. The first analyzed the shape and diameter of the semi-circular curves in the plots of the storage melt viscosity (η') versus the loss melt viscosity (η "), representing the Cole-Cole plot. The second was based on the slopes in logarithmic plots of the dynamic storage modulus (G') versus the dynamic loss modulus (G") between the blend compositions and the pure components. The third analyzed the deviation of the plot of the log complex viscosity (log η ^*), log η ' and log η " versus the blend compositions from the linearity. As a consequence, the MCPEHDPE blend showed semi-circular curves with the same diameter in the Cole-Cole plot, linearity in the slope of the log G' versus log G" between the pure components and the blend compositions, and the rule of the mixtures between the melt viscosity and the blend compositions. In contrast, the other three blends showed a different manner. Accordingly, the MCPE-HDPE blend is miscible, however, the other blends are not, which may result from the similar chemical structure of the ethylene unit between the main and the side chain. This interpretation of the melt rheology agrees well with the morphology.
Choe, Soon ja,Rana, Dipak,Kwak, Han Jin,Kim, Hak Lim 한국공업화학회 2000 Journal of Industrial and Engineering Chemistry Vol.6 No.2
The effect of comonomer content and the distribution of side chain branching on thermal, viscoelastic, rheological, and mechanical properties was investigated using the ethylene 1-octene copolymer (EOC) blends, which consist of one component by the Ziegler-Natta and another by the metallocene catalysts. Two model blend systems were selected; one was composed of FA+FM, which were made using the Ziegler-Natta and metallocene catalysts, respectively, and which has a similar melt index (MI), density, and comonomer content. The other blend was composed of SF+FM, which were also made using the Ziegler-Natta and metallocene catalysts, respectively, however, despite similar MI and density they had different comonomer contents. The big difference between the Zieler-Natta and metallocene EOC's is the comonomer distribution and the length of the side chain branching. Regardless of the blending methods (solution and melt blending), the blends exhibited two distinct melting and crystallization peaks, implying that the constituents excluded one another during crystallization. A single γrelaxation shifted to a lower temperature relative to the content of metallocene EOC, thereby indicating miscibility in the amorphous region. In addition, the mechanical properties seemed to have no dependency on the comonomer content. Hence the properties of EOC blends consisting of components with a similar MI and density influenced by both the comonomer contents and the distribution of the side chain branching.
( Ja Kyung Koo ),( Jeong Han Kim ),( Yun Jung Choi ),( Cho I Lee ),( Jae Hoon Yang ),( Hyeon Young Yoon ),( Hye Jin Choi ),( Soon Young Ko ),( Won Hyeok Choe ),( So Young Kwon ),( Chang Hong Lee ) 대한간학회 2012 춘·추계 학술대회 (KASL) Vol.2012 No.1
Background: The Model for end-stage liver disease (MELD) has been widely used for predicting short term mortality in cirrhotic patients and employed for deceased donor liver allocation in the U.S. In year 2011, modification of MELD score was published (Gastroenterology 2011;140:1952-1960). We aimed to validate this for Korean cirrhotic patients. Methods: We retrospectively reviewed medical records of cirrhotic patients who admitted at konkuk university hospital from 2006 to 2010. Predictive value for 3 months mortality was compared between Refit MELD, Refit MELD-Na, current MELD, current MELD-Na, Child-Pugh score. Comparison was done by calculating area under receiver operating curve (AUROC). Results: Total 882 patients were enrolled and there were 77 deaths (8.7%) within 3 month. The most common etiology was alcohol (n=400, 45.4%) and the next was hepatitis B (n=302, 34.2%). 666 patients were male (75.5%), and Child-Pugh class A, B and C were 256 (29.0%), 379 (43.0%) and 247 (28.0%). AUROC of Refit MELD, Refit MELD-Na, MELD, MELD-Na and Child-Pugh score were 0.842, 0.817, 0.844, 0.848 and 0.831 respectively. There was no significant difference between scores except between Refit MELD-Na and MELD (p=0.0447), andu between Refit MELD-Na and MELD-Na (p=0.0008). After exclude Child-Pugh class A patients, AUROC of Refit MELD, Refit MELD-Na, MELD, MELD-Na and Child-Pugh score were 0.793, 0.751, 0.795, 0.798 and 0.765 respectively. The Refit MELD-Na showed lower value than MELD-Na (p=0.0005), MELD (p=0.0190) and Refit MELD (p=0.0174). Conclusions: Improvement of predictive value for 3 months mortality was not definite. Especially Refit MELD-Na showed the lowest value. This result may be due to difference of underlying etiology of cirrhosis between Korea and U.S. More large prospective study is warranted.
( Ja Kyung Koo ),( Jeong Han Kim ),( Yun Jung Choi ),( Cho I Lee ),( Jae Hoon Yang ),( Hyeon Young Yoon ),( Hye Jin Choi ),( Soon Young Ko ),( Won Hyeok Choe ),( So Young Kwon ),( Chang Hong Lee ) 대한간학회 2012 춘·추계 학술대회 (KASL) Vol.2012 No.-
Background: The Model for end-stage liver disease (MELD) has been widely used for predicting short term mortality in cirrhotic patients and employed for deceased donor liver allocation in the U.S. In year 2011, modification of MELD score was published (Gastroenterology 2011;140:1952-1960). We aimed to validate this for Korean cirrhotic patients. Methods: We retrospectively reviewed medical records of cirrhotic patients who admitted at konkuk university hospital from 2006 to 2010. Predictive value for 3 months mortality was compared between Refit MELD, Refit MELD-Na, current MELD, current MELD-Na, Child-Pugh score. Comparison was done by calculating area under receiver operating curve (AUROC). Results: Total 882 patients were enrolled and there were 77 deaths (8.7%) within 3 month. The most common etiology was alcohol (n=400, 45.4%) and the next was hepatitis B (n=302, 34.2%). 666 patients were male (75.5%), and Child-Pugh class A, B and C were 256 (29.0%), 379 (43.0%) and 247 (28.0%). AUROC of Refit MELD, Refit MELD-Na, MELD, MELD-Na and Child-Pugh score were 0.842, 0.817, 0.844, 0.848 and 0.831 respectively. There was no significant difference between scores except between Refit MELD-Na and MELD (p=0.0447), andu between Refit MELD-Na and MELD-Na (p=0.0008). After exclude Child-Pugh class A patients, AUROC of Refit MELD, Refit MELD-Na, MELD, MELD-Na and Child-Pugh score were 0.793, 0.751, 0.795, 0.798 and 0.765 respectively. The Refit MELD-Na showed lower value than MELD-Na (p=0.0005), MELD (p=0.0190) and Refit MELD (p=0.0174). Conclusions: Improvement of predictive value for 3 months mortality was not definite. Especially Refit MELD-Na showed the lowest value. This result may be due to difference of underlying etiology of cirrhosis between Korea and U.S. More large prospective study is warranted.
Subjective and Objective Caregiver Burden in Parkinson's Disease
Kim, Keum-Soon,Kim, Bog-Ja,Kim, Kyung-Hee,Choe, Myoung-Ae,Yi, Myung-Sun,Hah, Yang-Sook,Chung, Sun-Ju,Kwon, So-Hi Korean Society of Nursing Science 2007 Journal of Korean Academy of Nursing Vol.37 No.2
Purpose. Parkinson's disease (PD) is a common neurodegenerative disorder characterized by motor disabilities and increasing dependence on others for daily life activities with consequent impact on patients' and caregivers' quality of life. The aim of this study was to elucidate the burden on primary caregivers of patients with PD, and identify related factors. Methods. A cross-sectional descriptive study. Seventy-six primary caregivers of PD patients in a neurology out-patient clinic, Seoul, Korea completed structured questionnaires, of which 68 were analyzed. The structured self-report questionnaire included (1) demographic information on the caregivers, (2) information regarding the disease characteristics of the patients, and (3) the subjective and objective caregiver burdens as assessed on Montgomery, Gonyea, & Hooyman's scale. Results. The mean age of the caregivers was 54.56 years, and spouses represented the largest proportion (47.0%). Caregivers of PD patients experienced high levels of burden (mean scores on the subjective and objective burdens were 45.22 and 34.90, respectively), which were comparable to the caregiver burdens in stroke, and higher than the caregiver burdens in general chronic disease. Older caregivers and spousal caregivers experienced significantly higher burdens (p=.004 and p=.019, respectively). A greater motor disability and higher modified Hoehn and Yahr grade were related to higher caregiver burden (p=.001 and p=.018, respectively). Conclusion. Caring for PD patients is associated with a high level of caregiver burden. Therefore, healthcare professionals should identify the burden of caregivers who look after PD patients and develop comprehensive management strategies both for patients and their caregivers.