A-deficit LSCF for intermediate temperature solid oxide fuel cells

A-deficit La_0.54Sr_0.44Co_0.2Fe_0.8O_3 ? δ cathode material for intermediate temperature solid oxide fuel cells (IT-SOFCs) was synthesized by a citrate complexation (Pechini) route. Using La_0.54Sr_0.44Co_0.2Fe_0.8O_3 ? δ as cathode material, a superior cell performance with the maximum power density of 309, 470 and 855 mW cm^? 2 at 600, 650 and 700 °C was achieved, in contrast with the maximum power density of 266, 354 and 589 mW cm^? 2 using conventional La_0.6Sr_0.4Co_0.2Fe_0.8O_3 ? δ as cathode material at the same temperatures. The reason of this improvement was analyzed on the basis of defect chemistry. Thermal shrinkage experiment testified that the oxygen vacancies in La_0.54Sr_0.44Co_0.2Fe_0.8O_3 ? δ are more mobile than in La_0.6Sr_0.4Co_0.2Fe_0.8O_3 ? δ. Furthermore, theoretical calculation in terms of their composition and the shift of peak position in XRD pattern showed that the concentration of oxygen vacancies of La_0.54Sr_0.44Co_0.2Fe_0.8O_3 ? δ is higher than that of La_0.6Sr_0.4Co_0.2Fe_0.8O_3 ? δ. Therefore, the oxygen ion conductivity via vacancies transfer mechanism is enhanced, which induces the polarization resistance of La_0.54Sr_0.44Co_0.2Fe_0.8O_3 ? δ being decreased with a result of cell performance improved.     

Room temperature growth and properties of ZnO films by pulsed laser deposition

ZnO thin films were prepared by pulsed laser deposition at room temperature on glass substrates with oxygen pressures of 10-30 Pa. The structural, electrical, and optical properties of ZnO films were studied in detail. ZnO films had an acceptable crystal quality with high c-axis orientation and smooth surface. The resistivity was in the 10² Ω cm order for ZnO films, with the electron concentration of 10¹⁶-10¹⁷ cm⁻³. All the films showed a high visible transmittance ∼90% and a high UV absorption about 90-100%. The UV emission ∼390 nm was observed in the photoluminescence spectra. The oxygen pressures in the 10-30 Pa range were suitable for room temperature growth of high-quality ZnO films.     

一个自适应Dai-Liao共轭梯度法

共轭梯度法是求解大规模无约束优化问题的经典方法之一.基于搜索方向矩阵的谱条件数,给出了一个Dai-Liao(DL)共轭梯度法中参数的自适应形式,提出一种自适应DL共轭梯度算法.在适当的条件下,对于一致凸的目标函数证明了该方法具有全局收敛性.数值结果表明,提出的方法是可行的.     

Role of oxygen vacancies in the origin of ferromagnetism in Mn‐doped ZnO

The relationship between the oxygen vacancy and ferromagnetism in Mn‐doped ZnO has been studied based on the first‐principles calculations. Three possible charge states of oxygen vacancies, i.e., neutral (V_O⁰), 1+ (V_O¹⁺) and 2+ (V_O²⁺) are considered. Results show that the lattice relaxations around oxygen vacancies are large difference under different charge states. It is found that V_O¹⁺ and V_O²⁺ oxygen vacancies induce ferromagnetism. However, Mn‐doped ZnO system shows ferromagnetism with V_O⁰ oxygen vacancies in hydrogenated environment, the ferromagnetism is attributed to the interstitial H, which forms a bridge bond and mediates d ‐d coupling and stabilizes the ferromagnetic state. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

细胞组织对称结构点温度漂移值诊断技术研究

体内细胞组织的缺陷能以皮肤表面所发射红外线的热效应,即细胞组织对称结构点温度漂移值诊断出来,分析缺陷温值的对称性并对其温度值的漂移量进行计算处理,可以临床确诊病变的准确部位。本文即介绍这一诊断系统。     

Study on the interactions between anti-tumor metal complexes and mononucleotides using trans -[en2Os(η2-H2)(CF3SO3)](CF3SO3) as a 1H NMR probe in a competitive mode

The interaction of several anti-tumor metal complexes with dGMP have been investigated using trans-[en₂Os(η²-H₂)]²⁺ as a ¹H NMR probe in a competitive mode. Me₂SnCl₂, Bu₂SnCl₂, Et₂Sn(phen)Cl₂ and Et₂SnCl₂can bind to dGMP mainly via phosphate; Cp₂TiCl₂ binds to dGMP mainly via phosphate and N₇. The binding constant for (CH₃)₂SnCl₂ binding to phosphate of dGMP exceeds 2.71×10⁴. The binding constant for Cp₂TiCl₂ to phosphate is even greater than that of Sn(IV). Cis-platin has high affinity for both N₇ and phosphate, but mainly for N₇. Binding of the probe to N₇ of dGMP reduces the binding affinity for phosphate of the same dGMP molecule by a factor of 5 to 6. Much the same factor is expected to apply to other metals containing agents interacting with dGMP.     

Phase Instability in van der Waals In2Se3 Determined by Surface Coordination

van der Waals In₂Se₃ has attracted significant attention for its room-temperature 2D ferroelectricity/antiferroelectricity down to monolayer thickness. However, instability and potential degradation pathway in 2D In₂Se₃ have not yet been adequately addressed. Using a combination of experimental and theoretical approaches, we here unravel the phase instability in both α- and β′-In₂Se₃ originating from the relatively unstable octahedral coordination. Together with the broken bonds at the edge steps, it leads to moisture-facilitated oxidation of In₂Se₃ in air to form amorphous In₂Se_3−3xO_3x layers and Se hemisphere particles. Both O₂ and H₂O are required for such surface oxidation, which can be further promoted by light illumination. In addition, the self-passivation effect from the In₂Se_3−3xO_3x layer can effectively limit such oxidation to only a few nanometer thickness. The achieved insight paves way for better understanding and optimizing 2D In₂Se₃ performance for device applications.     

Application of a stepwise flow ratiometry without phase separation to the determination of the chloroform/water distribution coefficients of volatile diazines

The chloroform/water distribution coefficients (K(D)) of sixteen diazine compounds were determined by a stepwise flow ratiometry. An aqueous solution of analyte was delivered and merged with chloroform. The flow rate ratio of both the phases was varied stepwise under a constant total (chloroform+aqueous) flow rate. The analyte was extracted to chloroform while both the phases, which were segmented by each other, were passing through an extraction coil. The segmented stream was then led to a UV/Vis detector directly without phase-separation. The absorbance of the chloroform and aqueous phases (A(o) and A(a), respectively) was each measured at the maximum absorption wavelength of the analyte. The plots of A(-1) against R(f), (AR(f))(-1) against R(f)(-1), and AR(f) against A gave straight lines, where A was A(o), A(a) or the sum of them (A(S)). The K(D) of the analyte was calculated from the slopes and intercepts of the plots. The log K(D) values obtained for the analytes (-0.5-1.4) were agreed well with the values measured by a shake-flask method. The present method is simple, rapid (5 min/determination) and applicable to the volatile compounds with reasonable precision (standard deviation of log K(D)<0.07).     

一类非线性四阶特征值问题的正解

该文讨论了如下边值问题正解的存在性和多解性     

偏振干涉成像光谱仪通量的分析与计算

论述了自行研制的偏振干涉成像光谱仪的剪切分光机理和干涉成像原理。对偏振干涉成像光谱仪的通量进行了分析和计算,推导了偏振器偏振化方向偏离理想方向时通量随偏角的变化关系。给出了最大调制度情形下的通量数值。这种偏振干涉成像光谱仪结构简单,无运动部件,能量通过率高,充分显示了超小,稳态,、大视场高通量,高调制度的优点,更加适合于航空航天遥感,野外环境操作和微弱信号探测。