MODAL ANALYSIS OF A SLOTTED WAVEGUIDE: COMPARISON BETWEEN ANALYTIC SOLUTION AND COMPUTER SIMULATIONS

Because of the complicated geometry of the slotted structure, analytical theories of such structures are inevitably developed on the basis of simplifying assumptions. On the other hand, the accuracy of the theory is of importance to the design of microwave interaction structures. In this study, modes of the slotted waveguide are investigated analytically and simulated with the HFSS code. It is shown that, in spite of the approximations made, the dispersion relation and field patterns of the standard analytical theory are in excellent agreement with the HFSS simulations over the complete range of the slot depth. Modes not built into the theory will also be noted.     

静高压下Al80Mn14Si6合金准晶相形成的研究

 本文首次研究了Al₈₀Mn₁₄Si₆合金在静高压下准晶相得形成。利用静高压熔态淬火方法，在压力2.8和3.1 GPa下得到淬火的Al-Mn-Si样品。电子和X射线衍射实验表明，高压淬火样品中含有准晶二十面体相和非晶相。X射线衍射实验还表明，高压淬火样品经350 ℃退火一小时基本上没有发生变化；而经过500 ℃退火一小时后，准晶相晶化为α-Al₇₃Si₁₀Mn₁₇相。另外，电子衍射实验表明，高压淬火后样品中还存在其它中间亚稳相。本文还讨论了静高压熔态淬火方法的适用性。     

On best restricted range approximation in continuous complex-valued function spaces

To provide a Kolmogorov-type condition for characterizing a best approximation in a continuous complex-valued function space, it is usually assumed that the family of closed convex sets in the complex plane used to restrict the range satisfies a strong interior-point condition, and this excludes the interesting case when some Ω_t is a line-segment or a singleton. The main aim of the present paper is to remove this restriction by virtue of a study of the notion of the strong CHIP for an infinite system of closed convex sets in a continuous complex-valued function space.     

l-Proline-catalyzed intramolecular cyclization of 5-hydroxypentene to β-halogenated tetrahydrofuran

A series of β-bromo- and β-iodotetrahydrofurans was synthesized from the reaction mixture of 5-hydroxypentene, l-proline, NBS (or I₂) in THF at 0 °C for 10 min. This l-proline-catalyzed intramolecular cyclization provides a simple and efficient method for the preparation of β-halogenated tetrahydrofuran.     

甲烷部分氧化制合成气Ⅱ．镍系催化剂的反应性能

主要用第四周期金属元素的氧化物与Ａｌ２Ｏ３的复合氧化物催化剂上甲烷氧化的结果证实了催化剂设计中的预测：（１）催化剂首先应能解离活化甲烷，（２）催化剂要能较快地活化Ｏ２分子．只有同时满足这两个条件，催化剂才可能有较好的甲烷部分氧化活性．第四周期元素中只有镍具有这样的性质．Ｃｕ，Ｍｎ，Ｃｒ，Ｌａ，Ｃａ，Ｚｎ等氧化物的添加可明显提高Ｎｉ－Ａｌ２Ｏ３催化剂的甲烷部分氧化性能，其中Ｃｕ的助催化性能最好．催化剂ＮｉＯ－ＣｕＯ－Ａｌ２Ｏ３，ＮｉＯ－ＭｎＯ－Ａｌ２Ｏ３，ＮｉＯ－Ｃｒ２Ｏ３－Ａｌ２Ｏ３的反应活性和选择性顺序，与金属Ｃｕ，Ｍｎ，Ｃｒ上ＣＯ和Ｈ２脱附的顺序是一致的     

Pb0.50Sr0.75Y0.70Ca0.25Cu1.70Oy单晶的磁阻研究

对低掺杂区非超导的Pb_(6.56)Sr_(?)Y_(?)Ca_(?)Cu_(?)O_y单晶样品进行了电阻和磁阻的测量,发现在低温下电阻温度关系遵从变程跳跃传导的R=R_(?)exp[(T_(?)/T)~(?)]的变化规律,这说明该样品处于强局域化区域.在低温下的磁阻为负并有明显的各向异性,这表明这类体系的磁阻主要来自于轨道效应的贡献,并且可能受到自旋-轨道散射的影响. 关键词：     

The effect of protecting groups on tin-lithium exchange in α-alkoxyalkyltrimethylstannanes

MOM-protected α-hydroxytrimethylstannanes do not undergo tin-lithium exchange cleanly as their tributyl-counterparts do. Other protecting groups (e.g. N,N-diethylcarbamate) allow for clean transmetalation to occur presumably due to the formation of a more stable α-alkoxyorganolithium species.     

Geometry of the quantum complex projective spaceCP q (N)

We study the constraints from theb→sγ decay in the parameter space of effective supergravities from orbifold string theory and with minimal supesymmetric particle content. Both the general dilaton-dominated universal scenario as well as a non-universal scenario for the soft terms are investigated. It is found that the recently reported CLEO upper and lower bounds constrain the parameter space of the models under scrutiny. In particular we find constraints on the values of the parameter tanβ and the gluino masses. In this class of string scenarios the negative sign of the Higgs mixing parameterμ, is phenomenologically preferred.     

White electroluminescence from a single polyfluorene containing bis‐DCM units

A series of fluorene‐based copolymers composed of blue‐ and orange‐light‐emitting comonomers were synthesized through palladium‐catalyzed Suzuki coupling reactions. 9,9‐Dihexylfluorene and 2‐(2,6‐bis‐{2‐[1‐(9,9‐dihexyl‐9H‐fluoren‐2‐yl)‐1,2,3,4‐tetrahydroquinolin‐6‐yl]‐vinyl}‐pyran‐4‐ylidene)‐malononitrile (DCMF) were used as the blue‐ and orange‐light‐emitting chromophores, respectively. The resulting single polymers exhibited simultaneous blue (423/450 nm) and orange (580–600 nm) emissions from these two chromophores. By adjusting the fluorene and DCMF contents, white light emission could be obtained from a single polymer; a device with an ITO/PEDOT:PSS/polymer/Ca/Al configuration was found to exhibit pure white electroluminescence with Commission Internationale de L'Eclairage (CIE) coordinates of (0.33, 0.31), a maximum brightness of 1180 cd/m², and a current efficiency of 0.60 cd/A. Furthermore, the white light emission of this device was found to be very stable with respect to variation of the driving voltage. The CIE coordinates of the device were (0.32, 0.29), (0.32, 0.29), and (0.33, 0.31) for driving voltages of 7, 8, and 10 V, respectively. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3380–3390, 2007