For the first time, PM2.5 source apportionment methods and techniques previously and currently applied in China are summarized, including sampling preparation, sampler selection, chemical speciation analysis, and source apportionment tools. The research direction for PM2.5 source apportionment work in China is also suggested. This review is expected to provide a fundamental understanding of PM2.5 source apportionment methods and to serve as an important reference for future source apportionment studies to be widely conducted in China and regulations or law for PM2.5 abatement in China.
This article reviews the current research on stroke order of hanzi (as used to write the Chinese, Japanese and Korean languages) in teaching Chinese as a second language (CSL). Based on an extensive review of current research on stroke order, it first discusses the importance and difficulty of stroke order in hanzi learning. It goes on to present the mixed attitudes held by CSL learners and teachers towards learning stroke order, followed by a synthesis of the literature on stroke order errors and current methods of displaying and practising stroke order. Finally, some key implications for teaching and learning stroke order are suggested, and future research directions are proposed for the Chinese language classroom.
Durinf April, July, October 2009 and January 2010, daily (24-h average) PM2.5 sample were collected at urban sites in Beijing and 29 metal elements were analized by the ICP-MS.
Enhanced triplet-triplet annihilation upconversion efficiency is achieved with two tris-cyclometalated iridium sensitizers covalently tethered with a pyrene annihilator. The improved sensitizing ability and very long phosphorescence lifetimes (1-2 ms) of these bichromophore molecules are both attributed to the intramolecular energy transfer between the iridium complex and appended pyrene group.