Effect of High Resistance Phases on Metal—Insulator Transition of La0.67Ca0.33MnO3

The temperature dependence of resistivity ρ of YSZ doping composite of (1-x) La0.67Ca0.33MnO3 xYSZ and Y2O3 doping composite of (1-y) La0.67MnO3 yY2O3 is investigated,respectively,in a temperature range 77-300K,where the YSZ represents yttria-stabilized zirconia(8mol%Y2O3 92mol% ZrO2).Experimental results show that the YSZ doping level has important effects on both the metal-insulator(M-I) transition temperatures and zero field resistivity of the composites of (1-x) La0.67Ca0.33MnO3 xYSZ.However,the Y2O3 doping level has little effect on the M-I transition temperatures and the zero field resistivity of (1-y)La0.67Ca0.33MnO3 yY2O3 only increases slightly.The difference between the two types of composites may mainly results from the different distribution of high resistance phases at the grain boundaries and /or surfaces of La0.67Ca0.33MnO3 grains rather than the substitution of La^3 ions with Y^3 ions.     

Efficient Quantum Cryptography Network without Entanglement and Quantum Memory

An efficient quantum cryptography network protocol is proposed with d-dimensional polarized photons, without resorting to entanglement and quantum memory. A server on the network, say Alice, provides the service for preparing and measuring single photons whose initial state are ｜0〉. The users code the information on the single photons with some unitary operations. To prevent the untrustworthy server Alice from eavesdropping the quantum lines, a nonorthogonal-coding technique is used in the process that the quantum signal is transmitted between the users. This protocol does not require the servers and the users to store the quantum states and almost all of the single photons can be used for carrying the information, which makes it more convenient for application than others with present technology. We also discuss the case with a faint laser pulse.     

Multiparty Quantum Secret Report

A multiparty quantum secret report scheme is proposed with quantum encryption. The boss Alice and her M agents first share a sequence of （M ＋ 1）-particle Greenberger-Horne-Zeilinger （GHZ） states that only Alice knows which state each （M ＋ 1）-particle quantum system is in. Each agent exploits a controlled-not （CNot） gate to encrypt the travelling particle by using the particle in the GHZ state as the control qubit. The boss Alice decrypts the travelling particle with a CNot gate after performing a aσ∞ operation on her particle in the GHZ state or not. After the GHZ states （the quantum key） are used up, the parties check whether there is a vicious eavesdropper, say Eve, monitoring the quantum line, by picking out some samples from the GHZ states shared and measuring them with two measuring bases. After confirming the security of the quantum key, they use the remaining GHZ states repeatedly for the next round of quantum communication. This scheme has the advantage of high intrinsic efficiency for the qubits and total efficiency.     

Sr_2Ru_(1-x)Mn_xO_4电阻率随掺杂量x变化规律的研究

采用传统固相烧结法合成了单相Sr2Ru1-xMnxO4多晶样品.同步辐射X射线衍射结果表明,随着Mn的逐渐掺入,晶胞中ab面内Ru-Ru距离逐渐增大.电阻率的测量结果表明,随着Mn的逐渐掺入体系的电阻率逐渐增大.一方面,Ru 3d的X射线光电子能谱(XPS)峰逐渐向高能方向移动,表明由于Ru-Ru距离的增大,Ru周围的电荷密度逐渐降低,贡献于电阻率的增大.另一方面,随着Mn的逐渐掺入体系室温磁化强度逐渐增强,表明Mn的掺入逐渐增大了体系的有效磁矩,同时体系在低温下出现负磁电阻效应,表明磁散射同样对电阻率的增大有一定的贡献.     

七元瓜环与芦竹碱的主客体相互作用

利用紫外可见吸收光谱法和荧光光谱法分别考察了七元瓜环(Q[7])与芦竹碱(Gramine)在溶液中的主客体相互作用;考察了p H值对主客体相互作用的影响,并利用摩尔比法和Job法计算了主客体相互作用的作用比以及稳定常数;利用等温量热滴定法进一步考察了Q[7]与Gramine主客体相互作用的热力学参数。实验结果表明Gramine与Q[7]在很宽的p H介质条件下(2p H10)都能发生主客体相互作用,在酸性、中性水溶液中形成2∶1的主客体配合物,而在碱性溶液中则形成1∶1的主客体配合物。Gramine与Q[7]的主客体相互作用过程主要是以焓驱动为主的过程。相溶解度实验的结果表明当Q[7]的浓度为1.0×10~(-3)mol·L~(-1)时,可使Gramine的溶解度增大82倍。     

嗜酸性氧化亚铁硫杆菌代谢产物的常压化学电离质谱分析

本研究以721矿和745矿嗜酸性氧化亚铁硫杆菌为研究对象,采用常压化学电离质谱直接分析其代谢产物,分别考察了顶空采样( Headspace sampling)、界面采样( Interface sampling)和中性解吸采样( Neutral desorption sampling)3种进样方式对电离效果的影响。在优化条件下,常压化学电离质谱对微生物纯菌种和混合菌种的代谢产物均具有良好的分析能力,可根据获得的代谢产物指纹谱图结合主成分分析( PCA)方法和聚类分析( CA)方法区分2个放射性强弱不同区域共4类嗜酸性微生物样品,并对主要胺类、酯类等代谢成分进行串联质谱鉴定,为耐辐射微生物的相关研究提供了一种可借鉴的分析方法。     

中空结构聚苯胺/Fe_3O_4/炭黑复合材料的制备及吸波性能

采用界面聚合和Pickering乳液聚合相结合的方法制备了具有微米尺寸的中空聚苯胺/Fe_3O_4/炭黑微球复合材料,研究了其形貌、电磁性能和吸波性能.结果表明,中空聚苯胺/Fe_3O_4/炭黑微球的平均粒径约为2.0μm;在2~4 GHz范围内的磁损耗主要是自然共振和交换共振,而在4~18 GHz范围内的磁损耗主要是涡流损耗;在2~18 GHz范围内,随着涂层厚度增加,反射损耗峰向低频方向移动,当涂层厚度增大到5.0mm时,反射损耗曲线出现2个反射损耗峰,分别位于C波段(4~8 GHz)和Ku波段(12~18 GHz),说明中空聚苯胺/Fe_3O_4/炭黑微球复合材料可作为特定频段的吸波材料.     

海底大地秩亏基准网快速标校方法

基于信标互测距信息与绝对坐标信息的融合,提出一种海洋大地控制网快速标校方法。相较于现有方法,快速标校方法降低了自由网平差对起算条件的需求,减少了50%以上的绝对标定点数目,标校效率与绝对坐标精度显著提升。在大范围布设时,优势明显。此外,通过对阵型与绝对校准点数目的分析,提出了几种典型阵型在理想条件下的布设方案。浅水试验结果表明,在保证基准网标校精度高于0.2 m的条件下,标校效率提升了50%。     

基于光纤色散相位补偿的高分辨率激光频率扫描干涉测量研究

为了实现更高分辨率的激光频率扫描干涉测量, 增大光源的扫频范围以及减小扫描频率的非线性成为关键. 采用外腔式大带宽扫频光源结合光纤辅助干涉仪构建的外部时钟频率采样非线性校正是目前较为常用的方法. 本研究发现随着扫频带宽和测量范围的增加, 光纤辅助干涉仪与测量光路中存在的色散失配导致频谱出现严重展宽, 极大的降低了测量的分辨率. 本文建立了辅助干涉仪和测量干涉仪色散失配影响的理论模型, 利用该模型分析了扫频带宽和测量范围与测量分辨率的变化关系, 与实验结果相一致, 并进而提出了基于峰值演化消畸变的色散相位补偿方法, 有效地提高了测量的分辨率, 在2.53 m 处实现了接近理论值的64.5 μm的测量分辨率. 该色散失配模型及补偿方法为提高大尺寸激光频率扫描干涉仪的测量分辨率及测距范围提供了参考.     

具有内部构造安全保障体系的冗余机器系统的最优控制

把系统方程的解转化为Volterra积分方程的形式,用范数指标函数作为衡量控制变量的标准,研究具有内部构造安全保障体系的冗余机器系统的最优控制问题.