Exploring Effect of Concentration on Quantitative Accuracy of QAMS by Taking Ginsenosides as an Example / 中国实验方剂学杂志

ObjectiveTo investigate the influence of concentration ratio（CR） between the internal reference and target components on the quantitative accuracy of quantitative analysis of multi-components by single marker（QAMS） by taking ginsenosides as an example. MethodUltra performance liquid chromatography（UPLC） was employed， the contents of nine components in Ginseng Radix et Rhizoma（ginsenosides Rg1， Re， Rf， Rh1， Rb1， Rc， Rb2， Rb3， Rd） were determined by external standard method（ES）. Using ginsenoside Rg1 as the internal reference， the contents of the remaining 8 ginsenosides were determined by QAMS， and the quantitative results were compared with those of ES to evaluate the quantitative accuracy of the established QAMS. According to the contents of these 9 ginsenosides， the simulated sample solutions with different CRs of ginsenoside Rg1 to ginsenosides Rf， Rb2， Rd were prepared with the reference substance（CR=100∶1， 10∶1， 5∶1， 2∶1， 1∶1， 0.5∶1， 0.25∶1）， in order to validate the effect of the CRs between the internal reference and other components on the quantitative accuracy of the QAMS. ResultThe results of ginsenosides Re， Rf， Rb1， Rc， Rb2 calculated by the two methods were the same with the relative standard deviation（RSD）<3%， however， the results of ginsenosides Rh1， Rb3 and Rd calculated by the two methods were different with RSDs of 7.06%-9.61%. According to the result of the simulated sample solution， the difference between the calculated results of ES and QAMS was large when the CR between the internal reference（ginsenoside Rg1） and other components was 5 or 10 or even higher. ConclusionThe quantitative error of QAMS will increase when the CR between the quantitative component and the internal reference is too large， so it is suggested that when establishing the QAMS， the components with close concentration to the internal reference should be selected for quantification.

Assessment of contribution of BCRP to intestinal absorption of various drugs using portal-systemic blood concentration difference model in mice.

Prediction of the intestinal absorption of new chemical entities (NCEs) is still difficult, in part because drug efflux transporters, including breast cancer resistance protein (BCRP) and P-glycoprotein (P-gp), restrict their intestinal permeability. We have demonstrated that the absorptive quotient (AQ) obtained from the in vitro Caco-2 permeability study would be a valuable parameter for estimating the impact of BCRP on the intestinal absorption of drugs. In this study, in order to assess the correlation between the in vitro AQ for BCRP and in vivo contribution of BCRP on drug absorption, we evaluated the oral absorption of various compounds by portal-systemic blood concentration (P-S) difference method in wild-type (WT), Bcrp(-/-), and Mdr1a/1b(-/-) mice. In addition, we also calculated a rate of BCRP contribution (Rbcrp ). Ciprofloxacin and nitrofurantoin showed the low Rbcrp value (0.05 and 0.15), and their apparent fractions of intestinal absorption in WT mice were 46.5% and 63.7%, respectively. These results suggest that BCRP hardly affects their intestinal absorption in mice. On the other hand, the apparent fraction of intestinal absorption of topotecan and sulfasalazine was significantly lower in WT mice than in Bcrp(-/-) mice. Moreover, their Rbcrp values were 0.42 and 0.79, respectively, indicating the high contribution of BCRP to their oral absorption. Furthermore, in vivo Rbcrp calculated in this study was almost comparable to in vitro AQ obtained from Caco-2 permeability study. This study provides useful concepts in assessing the contribution of BCRP on intestinal absorption in drug discovery and development process.

Correlations of Ion Composition and Power Efficiency in a Reverse Electrodialysis Heat Engine.

The main objective of this study is to explore the influence of ion composition on the trans-membrane potential across the ion exchange membrane (IEM), and thus offers a reference for the deep insight of "reverse electrodialysis heat engine" running in the composite systems. In comparison to the natural system (river water | seawater), the performance of the reverse electrodialysis (RED) stack was examined using NaHCO3, Na2CO3, and NH4Cl as the supporting electrolyte in the corresponding compartment. The effect of flow rates and the concentration ratio in the high salt concentration compartment (HCC)/low salt concentration compartment (LCC) on energy generation was investigated in terms of the open-circuit voltage (OCV) and power density per membrane area. It was found that the new system (0.49 M NaCl + 0.01 M NaHCO3|0.01 M NaHCO3) output a relatively stable power density (0.174 W·m-2), with the open-circuit voltage 2.95 V under the low flow rate of 0.22 cm/s. Meanwhile, the simulated natural system (0.5 M NaCl|0.01 M NaCl) output the power density 0.168 W·m-2, with the open-circuit voltage 2.86 V under the low flow rate of 0.22 cm/s. The findings in this work further confirm the excellent potential of RED for the recovery of salinity gradient energy (SGP) that is reserved in artificially-induced systems (wastewaters).

Spatial distribution differences in PM2.5 concentration between heating and non-heating seasons in Beijing, China.

Suffered from serious air pollution, Beijing, the capital of China, has implemented multiple measures to reduce the discharge of PM2.5 (particulate matter with aerodynamic diameters of less than 2.5 µm). The average annual PM2.5 concentration of Beijing has shown a continued decline in recent years. However, the improvement was not obvious during the heating season, which had heavier pollution than the non-heating season. Analyzing the spatial distribution of PM2.5 concentrations during heating and non-heating seasons, as well as their spatial differences, is believed to benefit the study of spatial-temporal variation of air pollution and provide scientific reference for the control of air pollution in Beijing. In this study, land use regression (LUR) model was employed to simulate the spatial distribution of PM2.5 concentrations in Beijing during heating and non-heating seasons in 2015. The spatial distribution of the concentration difference between heating and non-heating seasons was analyzed, and the influencing factors were also examined. The results showed that: (1) PM2.5 concentrations during heating and non-heating seasons, as well as their differences, were clearly at a maximum in the south and east of Beijing and at a minimum in the north and west; (2) the area with the biggest concentration difference was situated in a suburban area to the south and east, as well as in outer suburbs to the southeast and northwest; and (3) wind speed, area of transport land and industrial-mining-warehouse land were the main influence factors for the PM2.5 concentration difference in the central, eastern and southern area. Heating activity was not the only cause for the increased PM2.5 concentration during the heating season, vehicle emission, industrial discharge and regional transport of pollutants also played varied roles in PM2.5 pollution in different area.

Effect of heat wave at the initial stage in spark plasma sintering.

Thermal effects are important considerations at the initial stage in spark plasma sintering of non-conductive Al2O3 powders. The generalized thermo-elastic theory is introduced to describe the influence of the heat transport and thermal focusing caused by thermal wave propagation within a constrained space and transient time. Simulations show that low sintering temperature can realize high local temperature because of the superposition effect of heat waves. Thus, vacancy concentration differences between the sink and the cross section of the particles increase relative to that observed during pressure-less and hot-pressure sintering. Results show that vacancy concentration differences are significantly improved during spark plasma sintering, thereby decreasing the time required for sintering.