Long-distance super-exchange and quantum magnetic relaxation in a hybrid metal–organic framework

The hybrid metal–organic framework [(CH3)2NH2]Fe(HCOO)3with a perovskite-like structure exhibits a variety of unusual magnetic behaviors at low temperatures. While the long-distance super-exchange through the Fe-O–CH-O–Fe exchange path leads to a canted antiferromagnetic ordering at TN～ 19 K, a second transition of magnetic blocking develops at TB～ 9 K. The stair-shaped magnetization hysteresis loops below TBresemble the behaviors of resonant quantum tunneling of magnetization in single-molecular quantum magnets. Moreover, the magnetic relaxation also exhibits several features of resonant quantum relaxation, such as the exponential law with a single characteristic relaxation time, and the nonmonotonic dependence of relaxation rate on the applied magnetic field with a much faster relaxation around the resonant fields. The origin of quantum tunneling behaviors in the [(CH3)2NH2]Fe(HCOO)3metal–organic framework is discussed in terms of magnetic phase separation due to the modification of hydrogen bonding on the long-distance super-exchange interaction.     

石墨炉原子吸收光谱法测定人血清中微量锰

采用石墨炉原子吸收光谱法测定人血清中微量锰 ,回收率为 10 5 .0 % ,检出限为 7.7× 10 -10 g/ m L,相对标准偏差为 6 .5 16 %。本方法简单、快速和准确 ,已用于血中微量锰的测定 ,结果令人满意。     

基于聚类和双向门控循环单元 条件随机场的多类型流式文档结构识别

流式文档结构识别对于文档自动排版和优化、信息检索等领域有着重要作用.以往针对流式文档结构识别主要集中于学术论文领域,对于其他诸如公文、报告等多类型的文档结构识别研究较少.针对此现状,使用聚类的方法对文档进行分类,在此基础上提出了针对不同文档分类的、基于双向门控循环单元-条件随机场(bidirectional gated recurrent unit-conditional random field,BIGRU-CRF)的文档结构识别方法,以此来解决多类型文档结构识别的问题.实验结果表明,该方法不仅能够提高学术论文结构识别的效果,对其他类型的文档结构也能够进行较好地识别.     

金融危机中企业IT架构变革与能源成本管理

本论述讲述了在当前金融危机中,企业怎样进行IT架构的变革,为什么要对现有的服务、物理服务器进行整合,怎样利用服务器虚拟化技术提高服务器利用率减少成本开销,以及怎样对存储进行集中管理;并讲述了怎样对数据中心的能源成本进行控制和优化,介绍了一些切实可行的措施和方法,以期降低企业的IT运维成本。