A位取代对ZnO-0.5SiO_2陶瓷烧结特性和介电性能的影响

采用常规固相反应法,以ZnO-0.5Si O2体系为基体成分,研究了A位取代ZnO-0.5Si O2陶瓷的烧结特性和介电性能的影响规律.结果表明:Mg在一定范围内A位取代ZnO-0.5Si O2中的Zn可形成(Zn1-x,Mgx)2Si O4固溶体,x(Mg)最大固溶度不超过0.5.当取代量超过固溶度后,出现Mg2Si O4和Mg2Si O3相.x(Mg)≤0.5,陶瓷介电常数变化不大,品质因子较高;x(Mg)>0.5时,陶瓷介电常数增大,品质因子急剧下降.研究还揭示了(Zn1-x,Mgx)2Si O4(x=0.1~0.3)陶瓷在1 275℃烧结具有良好的介电性能,其介电常数为6.19~6.23,品质因子为48 000~53 000 GHz,频率温度系数为-50×10-6~-60×10-6/℃

Effects of cold hardening on membrane lipid peroxidation and activities of cell defense enzymes in leaves of Pritchardia gaudichaudii seedling under low temperature stress

在 - 5℃低温胁迫下 ,夏威夷椰子 (PritchardiagaudichaudiiH .Wendl.)幼苗叶片的丙二醛 (MDA)含量逐渐增加 ,表明膜脂过氧化作用逐渐增强 ;含水量不断下降 ;细胞保护酶中的超氧化物歧化酶 (SOD)、过氧化物酶 (POD)和过氧化氢酶 (CAT)酶活性均先升高 ,然后下降。冷锻炼处理可以减缓夏威夷椰子膜脂过氧化作用的增强 ,促进SOD酶活性的提高 ,同时抑制POD和CAT酶活性的变化 ,因而使夏威夷椰子幼苗的抗寒性得以提高 ,在 - 5℃低温胁迫下的半致死时间从 1.6d延长到 2 .2d。Under -5℃ low temperature stress, malondialdehyde (MDA) content in leaves of \%Pritchardia gaudichaudii \%H. Wendl. seedling gradually increased, reflecting that membrane lipid peroxidation aggravated. Water content lowered. Cell defense enzymes SOD (superoxide dimutase), POD (peroxidase) and CAT (catalase) activity raised at early stage, and then lowered. Cold hardening treatment could lessen the increase of membrane lipid peroxidation, promote SOD activity, and inhibite the change of POD and CAT activity under low temperature stress, so the resistance to chilling stress had been enhanced for \%P. gaudichaudii \%seedling. By cold hardening, the half lethal time had been extended to 2.2 d from 1.6 d under -5℃ low temperature stress.国家建设部和厦门市建设委员会资助项

溶菌酶1在小鼠超数排卵前后孵化及休眠囊胚中差异表达的研究

目的研究溶菌酶1(lysozyme 1,LYZ1)基因在超数排卵前后小鼠孵化囊胚和休眠胚胎中的分布以及表达,探究动物胚胎着床过程中新的调节机制。方法从妊娠5 d ICR小鼠体内获取的正常孵化囊胚和超排囊胚,利用小鼠延迟着床模型于妊娠第8天获取休眠胚胎和超排休眠胚胎。利用免疫荧光和Western Blot方法检测LYZ1蛋白在四组胚胎中的分布和差异表达变化。结果 LYZ1在超数排卵前、后小鼠孵化囊胚和休眠胚胎中均有表达,且主要集中在内细胞团中,滋养层细胞和胞质中少见分布;与未进行超排的小鼠相比,LYZ1蛋白在超排后小鼠胚胎中表达量显著上调,与未营造休眠模型的小鼠相比,LYZ1蛋白在休眠模型小鼠胚胎中的表达量显著上调。结论 LYZ1蛋白在囊胚内细胞团中表达,可能参与调节胚胎内细胞团的发育;LYZ1蛋白在超排-休眠胚胎中的高表达,说明LYZ1蛋白在休眠和超数排卵的双重影响下,会因为抵御不利环境而上调。2016年度科技创新服务能力建设-科技计划重点项目(KZ201610020018);;2018科技创新服务能力建设(KZ201610020018)~

PHOTOELECTRON SPECTROSCOPIC STUDIES OF CH_4-O_2 INTERACTION ON IRON AND MANGANESE SURFACES

[中文摘要]利用ESCA研究比较了CH_4—O_2在过渡金属铁和锰表面上的化学行为,结果表明:(1)在室温和高真空(P=10~(-5)Pa)下,甲烷与金属(铁和锰)表面和预先氧化的金属(Fe_2O3和MnO)表面作用,均未观察到有任何化学反应。但当甲烷与氧共吸附时,金属表面上就可检测到碳物种生成(CH_x,CH_xO,Carbide等),说明过渡金属铁和锰表面上的过渡态氧能够使甲烷脱氢活化;(2)合理地选择反应气CH_4/O_2比值。对有效且有选择地进行甲烷转化十分重要。CH_4/O_2比值太低,易使在表面生成的碳物种深度氧化;CH_4/O_2比值太高,表面生成碳物种的速率(甲烷转化率)大为减小;(3)在设计和选择甲烷氧化偶联反应催化剂时,应考虑催化剂表面上金属离子对氧和碳的键合强度因素。[英文摘要]The development of a better control over the selective oxidation of methane requires an understanding of some mechanistic questions, such as how is the C-H bond of methane activated, what are the surface intermediates and what is the active oxygen species for methane activation? The answers to the above questions will help the development of processes for selective oxidation of methane. In this paper, the chemical interactions of CH4 -O2 on iron and manganese surfaces have been studied by Photoelectron Spectroscopy.The chemisorption of methane was not observed at low pressure (10-5Pa)and room temperature on Fe and Mn surfaces and on their preoxidised surfaces (Fe2O3 and MnO).However,when the atomically clean iron and manganese surfaces were exposed to the mixed-gas of methane and dioxygen,the chemical dissociative adsorption of methane was observed on the exposed-surfaces,indicating that the surface transient oxygen,most probably O-(s),produced on the metallic surfaces of Fe and Mn is responsible for the cleavage of C-H bond in methane molecule:CH4(g)+O-(s)→CHx(a)+OH(a) (1)Increasing the sample temperature would result in partial oxidation and even total oxidation of CHx species by labile lattice oxygen O2- on the surface:CH4(

浅析核电施工现场动火作业中监火机器人的设计与应用

针对核电施工现场动火作业等重大安全问题，本文对智能监火的设计方法展开了设想、分析、应用和展望，提出了智能监火设计方案，并对机器人各项功能进行了设计，确保机器人能够做到监火和发出火灾警报。从监火机器人的应用情况来看，能够及时发现和预警，辅助人员加强对动火作业监管，因此能够保证现场施工安全，增加防火预警屏障。</jats:p