氨基乙酸在预腐蚀A3钢表面的吸附行为研究

利用极化曲线法及交流阻抗技术研究了NaHCO3溶液中氨基乙酸（GLY）在FeCO3膜表面的吸附行为及其对A3钢腐蚀行为的影响。结果表明：GLY在腐蚀产物膜上形成了多层吸附,且存在脱附过程,其缓蚀机理为“几何覆盖效应”,浓度为100mg/L时具有最好的缓蚀效果;吸附过程为自发过程,GLY在低浓度时,△G= –27.364kJ/mol,在高浓度时,△G= –13.152kJ/mol。     

Similarity principle of microwave argon plasma at low pressure

In order to validate the similarity principle of microwave breakdown, a two-dimensional(2 D) fluid model of lowpressure microwave argon plasma is established and solved by the finite-element method. Proportional conditions are used in this model to build three different breakdown processes that meet the premise of a similarity principle, and these breakdown processes are called "similar cases" in this paper. Similar cases have proportionately sized breakdown regions,where the ratio of frequency of incident microwave f to gas pressure p( f/p), and the reduced field E/p in them are kept the same. All the important physical parameters such as electron density, electron temperature, and reduced electric field can be obtained from the simulation of this model. The results show that the parameters between similar cases are in constant ratio without changing with time, which means that the similarity principle is also valid in microwave breakdown.     

聚(N,N-二乙基丙烯酰胺)的合成及盐对其水溶液温敏性的影响

采用CuBr/2,2'-联二吡啶催化体系, α-溴代丙酸乙酯为引发剂, 甲醇为溶剂, 通过原子转移自由基聚合(ATRP)合成了分子量分布窄的聚(N,N-二乙基丙烯酰胺)(PDEAM). 用FT-IR、1H-NMR和凝胶渗透色谱(GPC)对其结构进行了表征; 利用透光率的测定研究了PDEAM水溶液浓度、盐以及表面活性剂对PDEAM水溶液低临界溶解温度(LCST)的影响. 结果表明: 随着PDEAM水溶液浓度的增大, LCST逐渐降低; NaCl、CH3COONa、KCl、Na2SO4及MgSO4使PDEAM水溶液的LCST降低, 降低程度与盐的种类和阴离子价数有关; 十二烷基磺酸钠(SDS)则使PDEAM水溶液的LCST升高.     

P(DEAM-co-NAS)的合成及其温敏性的环境效应

采用自由基溶液聚合法合成聚(N,N-二乙基丙烯酰胺-co-N-丙烯酸琥珀酰亚胺)(P(DEAM-co-NAS))共聚比为7.9∶1、3.5∶1、2.5∶1、2∶1、1.5∶1的五组共聚物.利用傅里叶变换红外(FTIR)光谱和核磁共振(1HNMR)谱对P(DEAM-co-NAS)结构进行表征.共聚物组成和介质性质对P(DEAM-co-NAS)水溶液温敏性有显著影响.结果表明:随着NAS含量增加,共聚物水溶液的低临界溶解温度(LCST)逐渐升高,温敏性降低;盐的引入使P(DEAM-co-NAS)水溶液的LCST降低,所引入盐的阴离子价数越高,影响程度越大;有机酸的引入使P(DEAM-co-NAS)水溶液的LCST降低;NaOH、乙二胺、丁二胺的引入使P(DEAM-co-NAS)水溶液的LCST升高,二胺对P(DEAM-co-NAS)水溶液温敏性影响程度要大于NaOH.     

用分级教学方法来提升学生科学探究素养——以“万有引力定律”教学为例

科学探究在科学课中有着重要的角色和地位，课程标准指出科学探究要渗透在课程内容之中，两者不能割裂.科学探究素养的培养不仅仅是以学生实验课程为载体的，在很多概念、规律推理的内容中也都体现了科学探究要素.课程标准同时也具体地描述了学业质量水平的5个等级，就科学探究素养来说，5个等级如何实现是一线教师需要思考的.以“万有引力定律”的教学为例，阐述在规律课中，如何通过分级的教学方法，培养学生的科学探究素养，教学设计中又是如何体现科学探究要素的培养策略.