Origin of constant loss in ionic conductors

We have analyzed the constant loss contribution to the ac conductivity in the frequency range 10 Hz-1 MHz and temperatures down to 8 K, for two Li ionic conductors, one crystalline (Li(0.18)La(0.61)TiO(3)) and the other glassy (61SiO(2);35Li(2)O.3Al(2)O3.P(2)O(5)). As temperature is increased a crossover is observed from a nearly constant loss to a fractional power law frequency dependence of the ac conductivity. At any fixed frequency omega, this crossover occurs at a temperature T such that omega approximately nu(0)exp(-E(m)/k(B)T), where nu(0) is the attempt frequency and E(m) is identified with the barrier for Li+ ions to leave their wells.     

非水溶液滴定法测定普卢利沙星的含量

以0.1mol.L-1高氯酸为滴定液,结晶紫为指示剂,用非水滴定法测定普卢利沙星。重复测定普卢利沙星含量平均值为99.4%(n=6),相对标准偏差为0.1%。该方法准确简便、重复性好,可作为普卢利沙星含量测定的有效方法。     

模具钢表面激光毛化工艺的试验研究

以模具工业45^#钢摩擦学设计及性能要求为基础,分析了激光毛化模具钢表面形貌的形成机理及其关键的影响因素。采用灯泵浦Nd：YAG脉冲激光器在试样表面进行激光毛化工艺试验,获得了合理的激光毛化参数范围：激光峰值功率0．8～1．6kW,离焦量-1．4～-0．4mm、＋0．4～4-1．4mm,辅助气体压力〉0．2MPa,脉宽1．8ms。采用功率增益和氧气保护,可加工出预先设定的微火山口状毛化形貌。微凹坑形貌的成功获得对于提高拉伸模具的摩擦磨损性能,进一步掌握激光毛化参数与材料的作用规律,提供了有效的数据参考。     

局域共振型声学超材料薄板带隙特性的能量解法

研究局域共振型声学超材料的带隙特性时,面临的首要问题是寻求一种带隙特性的高效解法。为此,本文以局域共振型声学超材料薄板为研究对象,提出了一种基于能量泛函变分原理及正交多项式级数展开的带隙计算方法。该方法通过合并基体板及共振子的动、势能及外力功建立元胞的能量泛函,经过变分运算得到元胞的振动控制方程,进而引入第一类Chebyshev正交多项式作为基函数将控制方程进行离散。为克服无法直接对离散控制方程中的广义坐标施加周期边界条件的困难,该方法将连续边界条件弱化到若干选定的配点上以离散方式实现,并将对应的一组线性约束条件通过拉格朗日乘子法施加到系统中。仿真结果表明,该方法具有较高的计算精度和效率,并可应用于\     

二极管阵列检测-流动注射分光光度法同时测定食品中铁铜钴

目的在于建立同时测定食品中铁、铜、钴三种微量元素的新方法。以2-(5-溴-2-吡啶偶氮)-5-二乙氨基酚(5-Br-PADAP)为显色剂,Triton X-100为增敏剂,采用流动注射-CCD二极管阵列检测-分光光度分析法同时对其进行测定。优化了实验参数,并用偏最小二乘法计算程序解析重叠光谱。结果显示,铁、铜和钴的线性范围分别为0.2～10 μg·mL-1,0.1～5.0 μg·mL-1,0.01～1.0 μg·mL-1,检出限分别为：0.2,0.1,0.01 μg·mL-1,进样频率为45样·h-1。所建方法用于茶叶、芝麻、小米等食品测定时,样品加标回收率分别为铁89.4%～102.3%、铜92.2%～108.0%、钴93.2%～110.8%,相对标准偏差为1.1%～12.1%。对国家一级标准参考物质茶叶和桃叶进行测定(ｎ＝8),结果在其给出的保证值范围之内。     

Magnetic properties and morphology of Ni nanoparticles synthesized in gas phase

We report on the size, structure and magnetic properties of Ni nanoparticles fabricated with a free-jet sputtering nanoparticle source. It is found how the pressure of the inert gas and the diameter of the source nozzle can control the particle size and coercivity in a wide range. Measurements of the specific magnetic moment of Ni nanoparticles are reported. A particular growing regime is found at high pressures over 1.8 mbar observing a further aggregation process that leads to nanoparticle agglomerates with diameters larger than 100 nm with a low dispersion in size.     

All-optical generation of states for "Encoding a qubit in an oscillator"

Most quantum computation schemes propose encoding qubits in two-level systems. Others exploit the use of an infinite-dimensional system. In "Encoding a qubit in an oscillator" [Phys. Rev. A 64, 012310 (2001)], Gottesman, Kitaev, and Preskill (GKP) combined these approaches when they proposed a fault-tolerant quantum computation scheme in which a qubit is encoded in the continuous position and momentum degrees of freedom of an oscillator. One advantage of this scheme is that it can be performed by use of relatively simple linear optical devices, squeezing, and homodyne detection. However, we lack a practical method to prepare the initial GKP states. Here we propose the generation of an approximate GKP state by using superpositions of optical coherent states (sometimes called "Schr?dinger cat states"), squeezing, linear optical devices, and homodyne detection.     

不协调目标信息系统知识约简的比较研究

研究不协调目标信息系统的各种知识约简之间的关系。证明分布约简既是β上分布约简，也是β下分布约简，并且在一定条件下,β上、下分布约简与不协调目标信息系统的分配约简和最大分布约简等价。     

简并四波混频中的能级交叉效应

我们用微扰方法计算了近简并准二能级系统的三阶非线性极化率x⁽³⁾(-ω;ω,ω,-ω)。研究了简并四波混频的能级交叉效应,并与共振荧光的能级交叉效应比较。指出简并四波混频的能级交叉效应可用来测量上能级及下能级的弛豫速率。 关键词：     

Phase diagram of trivalent and pentavalent patchy particles

We compute the equilibrium phase diagram of two simple models for patchy particles with three and five patches in a very broad range of pressure and temperature. The phase diagram presents low-density crystal structures which compete with the fluid phase. The phase diagram of the five-patch model shows re-entrant melting, in analogy with the previously studied four-patch case, a metastable gas-liquid critical point and a stable, high-density liquid. The three-patch model shows a stable gas-liquid critical point and, in the region of temperatures where equilibration is numerically feasible, a stable liquid phase, suggesting the possibility that in this small valence model the liquid retains its thermodynamic stability down to the vanishing range limit.