Soil texture affects the conversion factor of electrical conductivity from 1:5 soil-water to saturated paste extracts

Electrical conductivity(EC)of soil-water extracts is commonly used to assess soil salinity.However,its conversion to the EC of saturated soil paste extracts(ECe),the standard measure of soil salinity,is currently required for practical applications.Although many regression models can be used to obtain ECe from the EC of soil-water extracts,the application of a site-specific model to different sites is not straightforward due to confounding soil factors such as soil texture.This study was conducted to develop a universal regression model to estimate a conversion factor(CF)for predicting EC_(e) from EC of soil-water extracts at a 1:5 ratio(EC_(1:5)),by employing a site-specific soil texture(i.e.,sand content).A regression model,CF=8.9105e^(0.0106sand)/1.2984(r^(2)=0.97,P<0.001),was developed based on the results of coastal saline soil surveys(n=173)and laboratory experiments using artificial saline soils with different textures(n=6,sand content=10%-65%)and salinity levels(n=7,salinity=1-24 dS m^(-1)).Model performance was validated using an independent dataset and demonstrated that EC_(e) prediction using the developed model is more suitable for highly saline soils than for low saline soils.The feasibility of the regression model should be tested at other sites.Other soil factors affecting EC conversion factor also need to be explored to revise and improve the model through further studies.

The effect of carboxymethylchitosan nanoparticles on proliferation of keloid fibroblast

In this study,different molecular weight(MW)carboxymethyl chitosans(CM-chitosan)nanoparticles were prepared by ionic gelification.The particle size of nanoparticles was around 180–250 nm by dynamic light scattering(DLS)and transmission electron microscope(TEM).With the increase of CM-chitosan nanoparticles concentration from 2 to 200μg/mL,the growth inhibition effects on the keloid fibroblast increased.At the concentration of 100μg/mL,CM-chitosan nanoparticles withMW6.3 kDa had a significant inhibitory effect(inhibition ratio 48.79%)of the proliferation of keloid fibroblast.Compared with CM-chitosan solution,the inhibition of CM-chitosan nanoparticles were lower in prior period and similar in later period.By analyzing the different effects of chitosan,CM-chitosan solution and CM-chitosan nanoparticles on proliferation of keloid fibroblast,we have found that the carboxylmethyl groups of CM-chitosan play an important role in inhibition of proliferation of keloid fibroblast.