Clustering gully profiles for investigating the spatial variation in landform formation on the Chinese Loess Plateau

The gully is the most dynamic and changeable landform unit on the Loess Plateau,and the characteristics of gully landforms are key indicators of gully evolution.Different gully profiles are connected and combined through runoff nodes.Thus,it is necessary to cluster gully profiles into a gully profile combination(GPC)to reveal the spatial variation in gully landforms throughout the Loess Plateau.First,the gradient and gully evolution index(GEI)of two sample areas in Changwu and Suide in Shaanxi Province,China are calculated and analysed based on GPC.Then,the gradient and GEI are calculated by using 90-m-resolution digital elevation model(DEM)data for the severe soil erosion area with the basin as the research unit.On this basis,the spatial variation in the development degree is analysed with Getis-Ord Gi*.The results show that the degree of gully undercutting decreases from southeast to northwest under the influence of rainfall.Due to the soil properties,the loess in the northwest is more prone to collapse,resulting in the decrease of GEI from northwest to southeast.The development degree of gullies is closely related to rivers.The strong erosive capacity of rivers leads to greater differences in gullies within the basin.At the same time,the skewness and kurtosis of the gully index in the basin are correlated;when the distribution of the gully index in the basin is less normal,the distribution of the gully index is more concentrated.These results reveal the spatial variation characteristics of the Loess Plateau based on GPC.

A newfangled study using risk silhouette and uncertainty approximation for quantification of acyclovir in diverse formulation

Risk assessment and uncertainty approximation are two major and important parameters that need to be adopted for the development of pharmaceutical process to ensure reliable results.Additionally,there is a need to switch from the traditional method validation checklist to provide a high level of assurance of method reliability to measure quality attribute of a drug product.In the present work,evaluation of risk profile,combined standard uncertainty and expanded uncertainty in the analysis of acyclovir were studied.Uncertainty was calculated using cause-effect approach,and to make it more accurately applicable a method was validated in our laboratory as per the ICH guidelines.While assessing the results of validation,the calibration model was justified by the lack of fit and Levene＇s test.Risk profile represents the future applications of this method.In uncertainty the major contribution is due to sample concentration and mass.This work demonstrates the application of theoretical concepts of calibration model tests,relative bias,risk profile and uncertainty in routine methods used for analysis in pharmaceutical field.