Synthesis of 3-acetonyl- and 3-(2-oxoethyl)glutarates

Several synthetic routes to 3-acetonyl- and 3-(2-oxoethyl)glutarates 1-5 have been explored. The most advantageous involves, as the key steps, the conjugate addition of an appropriately substituted vinylmagnesium bromide to an alkylidenemalonic ester, a bis-homologation of the resulting diester and, finally, the reductive ozonolysis of the carbon-carbon double bond. The synthesis can be satisfactorily conducted in good overall yield on a multigram scale.     

基于量子限制的受主带间跃迁太赫兹探测器的制备与测量

使用分子束外延生长设备,在GaAs（100）衬底上生长了量子阱宽度为3 nm的GaAs/AlAs多量子阱样品,并在量子阱层中央进行了Be受主的δ-掺杂。根据量子限制受主从束缚态到非束缚态之间的跃迁,设计并制备了δ-掺杂Be受主GaAs/AlAs多量子阱太赫兹光探测器原型器件。在4.2 K温度下,分别对器件进行了太赫兹光电流谱和暗电流-电压曲线的测量。在6 V直流偏压下,空穴载流子沿量子阱层方向输运。当正入射激光频率为6.8 THz时,器件响应率为2×10^-4 V/W（2 μA/W）。通过器件的暗电流-电压曲线计算了器件全散粒噪声电流,在4.2 K、6 V直流偏压下,全散粒噪声电流为5.03 fA·Hz^-1/2。     

Spaces of holomorphic functions on non-balanced domains

This paper studies the coincidence of the _τω${\tau }_{\omega }$ and _τδ${\tau }_{\mathrm{<font\; color="red">\delta </font>}}$ topologies on the space of holomorphic functions defined on an open subset U   of a Banach space. Dineen and Mujica proved that _τω=_τδ${\tau }_{\omega }={\tau }_{\mathrm{<font\; color="red">\delta </font>}}$ when U   is a balanced open subset of a separable Banach space with the bounded approximation property. Here, we study the _τω=_τδ${\tau }_{\omega }={\tau }_{\mathrm{<font\; color="red">\delta </font>}}$ problem for several types of non-balanced domains U.     

凝胶注模工艺制备Ce0.9Gd0.1O2-δ粉体及性能研究

采用凝胶注模工艺制备了Ce0.9Gd0.1O2-δ（GDC）粉体,对其性能进行了TG-DSC、XRD、TEM和粒度等表征,分别与同等原料采用传统固相合成工艺制备的粉体,与不同原料同种凝胶注模工艺制备的粉体进行了性能比较。采用不同压力成型了坯体,在1350℃烧结得到瓷体,对粉体的烧结性能和瓷体的电导性能进行了表征。结果表明：采用凝胶注模工艺在600℃就能获得纯相GDC粉体,比固相反应合成GDC粉体温度降低400℃;相比以氧化物为原料合成的粉体,以硝酸盐为原料采用凝胶注模工艺合成的粉体有助于氧化钆在氧化铈晶格中的固溶;在1350℃烧结获得相对密度为96.5%瓷体,600℃电导率为0.0258S/cm,满足中温电解质材料对电导率的要求。     

ACTION DES CYANOARYLIDENES ACTIVES SUR LES β -CETO- δ -CARBETHOXYPHOSPHONATES ET PHOSPHINEOXYDES: SYNTHESE DE 2-AMINO-6-(PHOSPHONOMETHYL)-4H-PYRANES

The reaction of β-keto-δ-carbethoxyphosphonates and phosphineoxides 1 with active cyanoarylidenes 2 in basic conditions provides a convenient access to the new 2-amino-6-(phosphonomethyl)-4H-pyranes 3. The reaction is found to be highly regioselective. The structure of all obtained products is confirmed by NMR ( ¹ H, ³¹ P, ¹³ C), IR spectroscopy, and in some cases by mass spectrometry.     

Ce1-xErxO2-δ的溶胶-凝胶法合成及其性质

采用溶胶-凝胶法合成Ce1-xExO2-δ(x=0.00～0.30)系列固体电解质,系统地研究了其晶体结构和导电性.X-射线衍射(XRD)结果表明:所有Ce1-xErxO2-δ粉体经800℃焙烧2 h后,均结晶为立方萤石结构,其平均晶粒尺寸为32～43nm,晶胞参数与掺杂量的非线性关系与掺杂离子半径、氧空位及缺位缔合有...     

Influence of lattice oxygen stoichiometry on the mechanism of methane oxidation in SOFC anodes

There is growing interest in developing oxide materials for direct hydrocarbon solid oxide fuel cell anodes. In addition to electronic and ionic conductivities, the electrocatalytic activity of these materials is a critical requirement for a high performance anode. In this paper, we present evidence for the important role of variable lattice oxygen stoichiometry and anode geometry in dictating the activity and reaction mechanism of La_0.75Sr_0.25Cr_1 − xMn_xO_3 − δ-based anodes for CH₄ oxidation. Total oxidation of CH₄ is favored by low oxygen vacancy concentration and availability of reducible B-site cations. The non-linear dependence of electrode polarization resistance with current density is attributed to dynamic changes in lattice oxygen vacancy concentration. The relatively high open circuit potential of porous anodes compared with thin films is attributed to an increase in secondary reactions of the fuel within the porous anode.     

Fast epitaxial growth of a-axis- and c-axis-oriented YBa2Cu3O7−δ films on (1 0 0) LaAlO3 substrate by laser chemical vapor deposition

a-axis- and c-axis-oriented YBa₂Cu₃O_7−δ (YBCO) films were epitaxially grown on (1 0 0) LaAlO₃ substrates by laser chemical vapor deposition. The preferred orientation in the YBCO film changed from the a-axis to the c-axis with increasing laser powers from 77 to 158 W (the deposition temperatures from 951 to 1087 K). The a-axis-oriented YBCO film showed in-plane epitaxial growth of YBCO [0 0 1]//LAO [0 0 1], and the c-axis-oriented YBCO film showed that of YBCO [0 1 0]//LAO [0 0 1]. A c-axis-oriented YBCO film with a high critical temperature of 90 K was prepared at a deposition rate of 90 μm h⁻¹, about 2-1000 times higher than that of metalorganic chemical vapor deposition.     

罗尔中值定理的一些新证法

给出了罗尔微分中值定理的三种新的证明方法,其中第二种很简便的方法仅依赖于大家熟知的Heine-Borel有限覆盖定理.由此可见罗尔微分中值定理可以是实数的完备性的直接推论.