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A UPLC method has been developed for simultaneous determination of nine furanocoumarins of Angelica dahurics,and was used for quality evaluation of A. dahurica from different habitats. ACQUITY UPLC BEH C18 chromatographic column was employed,the separation was performed with the mobile phase consisting of acetonitrile and water,and the detection wavelength was set at254 nm. This method was used to simultaneously determine the content of xanthotoxol,oxypeucedaninhydrate,byak-angelicin,psoralen,xanthotoxin,bergapten,oxypeucedanin,imperatorin and isoimperatorin in A. dahurica from different habitats. Then,the further quality assessment of the drug was carried out by similarity evaluation,cluster analysis( CA),principal component analysis( PCA),and orthogonal partial least squares discriminant analysis( OPLS-DA). The content order of measured furanocoumarins from high to low was: oxypeucedanin>imperatorin>isoimperatorin>oxypeucedaninhydrate>bergapten>byak-angelicin>xanthotoxin>xanthotoxol>psoralen,with the mean content 2. 844,1. 277,0. 649 2,0. 216 2,0. 129 8,0. 062 68,0. 052 68,0. 019 30,0. 018 19 mg·g-1,respectively. There were difference between the batches of the drug,and the quality was influenced by smouldering sulphur based on the results of chemical pattern recognition and content determination. Finally,six active ingredients were recognized as the quality makers using OPLS-DA method. The validated UPLC fingerprint combined with chemical pattern recognition method can be used in the quality control and evaluation of A. dahurica.

Experimental research on the evolution characteristics of diesel particles under the cooling conditions has been carried out. The results showed that the cooling of the exhaust had important effect on the mass concentration of the diesel particles in the exhaust. The main cause that resulted in the change of the particle mass concentration was the condensation of gaseous hydrocarbon on the particle surface or existing in the form of liquid drop. The cooling of the exhaust promoted the increasing of the particle dimension and the decreasing of the particle numbers, especially for the smaller particles below 0.1 microm. The cooling temperature of the exhaust had important effect on the evolution of diesel particles. After exhaust cooling, the volume concentration of diesel particles between 0.1 microm and 1.0 microm exhibited a tendency of decreasing. Moreover, exhaust velocity also had effect on the evolution of the diesel particles. The number concentration and volume concentration of the diesel particles between 0.01 microm and 1.0 microm decreased along with the decreasing of the exhaust velocity.

The evolution characteristics of particle distribution in the vehicle exhaust plume have been investigated based on the models of nucleation, coagulation and condensation of particles. The simulated results showed that nucleation created a large number of new nanoparticles, and coagulation and condensation changed the distribution of particles in the vehicle exhaust plume. The effect of nucleation on the distribution of exhaust particles was weaker, and the distribution of exhaust particles was affected mainly by the effect of coagulation and condensation. The process of nucleation, coagulation and condensation was intense near the exit of the tailpipe and the variation of the particle distribution with time was strong. With the increase of the distance from the exit of the tailpipe, the evolution of exhaust particles got weaker. This work can provide much more information necessary for the establishment of vehicle emission control strategies and the study of the effect of vehicle particles on the human health.