NdFeO3纳米晶的合成及气敏性能

以Nd2O3,Fe(NO3)3·9H2O,硝酸(1∶1)为原料,在柠檬酸体系中用溶胶凝胶法合成了具有钙钛矿结构的稀土复合氧化物NdFeO3;用XRD和TEM对产物的组成、颗粒大小、形貌进行了表征;结果表明:产物为纳米颗粒,平均粒径为28nm左右,且颗粒均匀。还采用静态配气法测试了材料的气敏性能,发现NdFeO3对H2S有很高的灵敏度,且抗干扰能力强,有较好的工业应用前景。     

NMR study on solubility of benzyl alcohol and its transfer free energy from D_2O to cationic micelle

A new kind of surfactant, [CnH_(2n+1)OCH2CH(OH)CH2N(CH3)3]Cl (n=12, 14, 16) was synthesized. The solubility of benzyl alcohol in micellar solutions was determined by 1H NMR method. The results indicate that the length of alkyl chains of surfactant affects the solubility of ben-zyl alcohol in 2.5 × l0~(-2) mol/L micellar solutions. The solubility of benzyl alcohol per liter of micellar solution is 0.095 mole for n=12, 0.115 mole for n=14, 0.165 mole for n=16. The transfer free energy of benzyl alcohol from aqueous phase to micellar phase is -24.29 kJ/mol for n=12, -24.37 kJ/mol for n=14, -24.49 kJ/mol for n=16.     

中国寻呼业发展抉择

为了避免中国寻呼业重蹈某些国家或地区在其他业务冲击下逐渐没落的覆辙,从近期看,首先应该加强行业管理,制备有利于整体发展的行业法规;建立健全全国性的行业协会,进行行业自律。其次,应通过兼并重组,优胜劣汰,进行市场调整,走规模 化经营之路。另外,还应针对不同用户,细分市场,增加服务层次,吸引更多的用户,而从长远看,实行单向收费,推行双向寻呼,才是促进寻呼业健康发展的根本措施。