[[alternative]]Application of Ase and Isotope Dilution GC-MS for the Determination of 35 PAHs in Soil Samples

[[abstract]]A new technique for sample preparation, accelerated solvent extraction (ASE), that combines elevated temperature and pressure with liquid solvent is utilized in this study to pretreat soil samples for PAH analysis, The effects of various operational parameters (i.e. temperature, pressure, solvent type, extraction time) on the performance of ASE were investigated.The research aims at the development of a new sample pretreatment .technique for 35 polynuclear aromatic hydrocarbons (PAHs) in soil samples with GC-FID and isotope dilution GC-MS. The analytes are extracted by acetonitrile at 130℃ and 1500 psi within 5 minutes of static extraction.The time for the entire extraction process is 20 minutes.Results demonstrated that the ASE extraction is selective for PAHs.Thus, a further clean-up procedure after ASE is not necessary.The procedure of the extraction is simple and fast.ASE in recovery compared with Soxhlet extraction is higher.The results from CRM 103-100 and QCS345 analyses further vrified the high precision and accuracy of the developed analytical scheme.The result from real samples demonstrated that the concentration of PAHs in soil is low.

[[alternative]]Applying Science Writing in Science Teaching and Assessing -- An Example of Describing and Explaining of the Acid-Base Phenomenon in the Movie

[[abstract]]Applying Science Writing in Science Teaching and Assessing -- An Example of Describing and Explaining of the Acid-Base Phenomenon in the Movie Abstract Drawn on the Systemic Functional Linguistics (SFL), the present study aims to explore the effects of applying science writing in science teaching and assessing. A Quasi-experiment was designed. After reading a text extracted from the science textbook, the experimental group was asked to accomplish science writing task as watching movie film, while the control group just watched movie film only. These students’ performance of acid-base tests and academic achievement including Chinese and Science were collected. Students’ science writing texts were analyzed by the grammatical system of transitivity in SFL and the relations between science writing and learning achievement were analyzed. The major findings were as follows: 1. In the text of students’ science writing, observational clauses were more than explanatory ones, the average lexical density was 3.14, where 29% was science content words. 2. Students’ science writing text was significant correlated with their academic achievement in Chinese and Science. However the coefficient of the later was higher than the former. 3. The experimental group performed better than the control group in the achievement test. Reading the science text promoted high-grade students’ learning achievement, while reading the science text accompanied with science writing promoted both high- and low-grade students’ achievements. 4. The combinations of the amount of content words, clauses and rank-shift, observational and explanatory clauses could be serve as possible rubrics for assessing the quality of students’ science writing. Issues and implications in science teaching of the above findings were discussed, and suggestions were proposed for further study.