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italic>K-values of 56 batches of 7 types of povidone were measured by microfluidic rheometry and with a Ubbelohde capillary viscometer. The K-values of the two methods were tested by SPSS software and the results showed that there was no significant difference between the two methods (P > 0.05). Taking K-values measured with the Ubbelohde capillary viscometer (Ku) as the abscissa and K-values measured by microfluidic rheometry (Km) as the ordinate a linear equation was calculated: Km = 0.893 9Ku + 4.617 6, R2 = 0.986 2, with good linearity, indicating that the microfluidic rheometer method can replace the Ubbelohde capillary viscometer in determining K-values of povidone. The microfluidic rheometer method has the benefits of less sample consumption, faster determination, and is more accurate, and it can be used with high-throughput automatic acquisition, which provides a more convenient method for the determination of K-values of different types of povidone. The weight-average molecular weights (Mw) of each type of povidone were measured by gel permeation chromatography-multi angle laser light scattering (GPC-MALLS), and the relationship between Mw and Km was lgMw = -0.000 4 Km2 + 0.072 7 Km + 2.791, R2 = 0.990 1. The fitting relationship was good, and Mw could be calculated by Km by the equation.
RESUMO
To determine relative molecular weight of astragalus polysaccharides (APs), we used Shodex GS620 gel permeation chromatographic column and differential refraction detector (GPC-RI) with dextran as a reference. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and GPC combined with multi-angle laser light scattering detection (GPC-MALLS) were also used．GPC-RI measure showed four peaks of APs, with the Mw of 1 380 000, 231 000, 18 000, and 480, respectively. Three main peaks were found by GPC-RI-MALLS with the Mw as 1 148 000, 180 000, and 43 000, respectively. Strong signals in 155 000 and 18 000 were detected by MALDI-TOF-MS, which also indicated the sugar moieties of the APs as hexoses. From our study, we found that the GPC-RI method with universal correction is most suitable for Mw determination of the APs. Nevertheless, the three methods should be combined and contrasted with each other to obtain accurate information in research of polysaccharides from Chinese medicine.
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This paper explored the multi-angle, comprehensive and systematic clinical prac-tice teaching system for international students. Six teaching methods were integrated: bedside teach-ing, standardized patients teaching, electronic patients clinic teaching, Chinese students one-to-one help foreign students, a variety of English clinic small presentation and many after-school social activi-ties. The multi-angle, comprehensive and systematic clinical practice teaching system was evidently a better choice than traditional teaching system for international students.