[Oxidative Capacity of the PM10 and PM2.5 in Beijing During 2014 APEC].

In order to evaluate the effect of the joint air pollution prevention and control program on the toxicity of the airborne particles in Beijing during the APEC conference, we collected the PM10 and PM2.5 (particulate matter with aerodynamic diameters of less than 10 µm and 2.5 µm respectively) from October to December in the urban district of Beijing, and analyzed the oxidative capacity of the particles by plasmid scission assay. The results indicated that the oxidative capacity of PM10 was higher than that of PM2.5 during the APEC conference, and that the damage rate of supercoiled DNA by the samples increased with their experimental dose levels. The TD30 (toxic dose of PM causing 30% of plasmid DNA damage, unit: µg·mL-1) was used to indicate the oxidative capacity and the lower TD30 values indicated higher oxidative capacity. The TD30 values of the PM samples before, during, and after APEC conference displayed a descending order of during APEC (November) >before APEC (October) >after APEC (December), which indicated a decreasing order of the PM oxidative capacity of after APEC (November) >before APEC (October) >during APEC. The TI (toxic index) was further introduced to represent the human exposure risk of particles, which was represented by the product of the mass concentration of PM (µg·m-3) and the DNA damage percentages under the PM dose of 250 µg·mL-1 (%). Compared with the TI values of previous years, the TI value of the 2014 APEC PM was lower than that of 2004, but higher than that of the 2008 Olypic Games, suggesting that the exposure risk of airborne particles decreased obviously with the increase of policy control strength.

New species of the isolated Psaroniaceous rachis from the Early Permian in China.

A new kind of marattialean raches are reported from the coal balls in Coal Seam No.7 in the upper part of the Taiyuan Formation (early Early Permian) from Taiyuan, Shanxi, China and are assigned to the genus Stipitopteris Grand'Eury (Psaroniaceae). The present specimens are different from all six reported species of the genus, and are therefore proposed as a new species: Stipitopteris shanxiensis. The raches of the new species are generally dorsi-ventrally flattened. The main raches usually exhibit scales of different forms on their surface. Beneath the epidermis is a zone of parenchymatous cells, some of which contain tannin-like contents. Inside this is a zone of small sclerenchymatous cells. Inward are the ground tissue and vascular bundles. The vascular bundles are continuous and are in two circles: the outer circle assumes a transversely elliptical shape with the gap and pinna trace, and the inner circle assumes a shallow C-shape with inrolled ends. The ground tissue located at the inner side of the vascular bundle is composed of thicker-walled parenchymatous cells. The cells of the ground tissue are vertically elongated in longitudinal sections. Subordered raches are smaller and have simpler structures than the main raches. The parenchyma zone beneath the epidermis is thinner, usually one to two cells wide and the sclerenchyma zone is usually absent. The scales are poorly developed and there is only one C-shaped vascular bundle. The new species is comparable to the crosiers of Psaroniaceae of the Euramerican Flora in some aspects, for example, it has a dorsi-ventrally flattened rachis and scales on the surface of the rachis. However, the other features and the preservative conditions of the present specimens indicate that they are not crosiers, but fully developed or mature raches. The new species is the first well-studied anatomically-preserved rachis of Psaroniaceae from the Cathaysian Flora and bears significance not only in understanding the anatomy and taxonomy of Psaroniaceae in the Cathaysian Flora, but also in the relationship between the Euramerican Flora and the Cathaysian Flora.