An efficient technique for the multilayered microwave and millimeter planar waveguides

The method of lines is extended to the multilayered inhomogenous dielectric layers by means of the additional transformation and the recurrence matrix. The computed dispersion diagrams for the multilayered planar waveguides agree very well with the results from other authors. New results for a six layer structure are given.     

Long-wavelength 640×486 GaAs-AlGaAs quantum well infraredphotodetector snap-shot camera

A 9-μm cutoff 640×486 snap-shot quantum well infrared photodetector (QWIP) camera has been demonstrated. The performance of this QWIP camera is reported including indoor and outdoor imaging. The noise equivalent differential temperature (NEΔT) of 36 mK has been achieved at 300 K background with f/2 optics. This is in good agreement with expected focal plane array sensitivity due to the practical limitations on charge handling capacity of the multiplexer, read noise, bias voltage, and operating temperature     

关中窄院民居

对陕西省关中地区传统窄院民居的形成,平面与空间的构成特点,外观形态以及地方材料的合理运用等进行了归纳,分析和研究。     

LaCrMnNiO系热敏陶瓷的微观结构控制

通过对不同配方、工艺下的ＬａＣｒＭｎＮｉＯ系热敏陶瓷的微观结构研究，指出材料的相组成对其宏观电性能的影响，并提出了通过复合工艺利用“过渡相”的形成，对材料的“最终相”加以控制的方法。文中列出了使用ＸＲＤ及ＸＰＳ手段对材料微观结构的分析结果及有关电性能的测试数据。     

面向对象系统中的特性表机制与复合对象

本文主要讨论特性表机制与复合对象的概念、功能及实现．在基于知识的面向对象系统中引入特性表机制与复合对象概念的目的在于增强系统的知识表达能力．文中提出的特性表机制包括了三种类型的特性说明表：类说明特性表、继承关系特性表和变量特性说明表．复合对象在系统中是通过引入一个称为“影子类”的新概念来构造和实现的．     

泥浆制备中工艺改造的研究

根据室条件下粉磨试验结果，发现球磨过程中筛上料变化存在的突变范围，提出两次加料一次加水可改变泥浆颗粒分布，并找出适宜的加料种类与时间。另外给予测粒度分布提供了宝贵的试验基础数据。     

Inhibition of G1 cyclin-dependent kinase activity during growth arrest of human breast carcinoma cells by prostaglandin A2

Prostaglandin A2 (PGA2) potently inhibits cell proliferation and suppresses tumor growth in vivo, but little is known regarding the molecular mechanisms mediating these effects. Here we demonstrate that treatment of breast carcinoma MCF-7 cells with PGA2 leads to G1 arrest associated with a dramatic decrease in the levels of cyclin D1 and cyclin-dependent kinase 4 (cdk4) and accompanied by an increase in the expression of p21. We further show that these effects occur independent of cellular p53 status. The decline in cyclin D and cdk4 protein levels is correlated with loss in cdk4 kinase activity, cdk2 activity is also significantly inhibited in PGA2-treated cells, an effect closely associated with the upregulation of p21. Immunoprecipitation experiments verified that p21 was indeed complexed with cdk2 in PGA2-treated cells. Additional experiments with synchronized MCF-7 cultures stimulated with serum revealed that treatment with PGA2 prevents the progression of cells from G1 to S. Accordingly, the kinase activity associated with cdk4, cyclin E, and cdk2 immunocomplexes, which normally increases following serum addition, was unchanged in PGA2-treated cells. Furthermore, the retinoblastoma protein (Rb), a substrate of cdk4 and cdk2 whose phosphorylation is necessary for cell cycle progression, remains underphosphorylated in PGA2-treated serum-stimulated cells. These findings indicate that PGA2 exerts its growth-inhibitory effects through modulation of the expression and/or activity of several key G1 regulatory proteins. Our results highlight the chemotherapeutic potential of PGA2, particularly for suppressing growth of tumors lacking p53 function.     

Investigation of optical losses in photoelastic and ridge waveguides in GaAs-AlGaAs heterostructures

Two approaches have been used to fabricate stable photoelastic waveguides with planarized surfaces on GaAs-AlGaAs heterostructures. The first approach uses tensile Ni/sub 3/GaAs stressors formed by metal-semiconductor reactions. The second approach uses inert, refractory and compressive stressors, such as RF sputtered W and RF co-sputtered WNi films. For comparison purposes, ridge waveguides have also been fabricated using the same heterostructure by a dry etching technique. Optical losses of photoelastic waveguides, measured by Fabry-Perot (FP) method at a wavelength of 1.53 /spl mu/m, are comparable to or better than those of the ridge waveguides. Material loss appears to be the primary loss mechanism in both photoelastic and ridge waveguides. These results indicate that the photoelastic waveguide processing technique reported in this study is a promising alternative to commonly used dry etching techniques for planarization.     

EFFECT OF STREAMLINE CURVATURE AND SOME OTHER CONDITIONS ON THE TURBULENT STRUCTURES IN THE OTHER REGION OF AN OBSTACLE

ＥＦＦＥＣＴＯＦＳＴＲＥＡＭＬＩＮＥＣＵＲＶＡＴＵＲＥＡＮＤＳＯＭＥＯＴＨＥＲＣＯＮＤＩＴＩＯＮＳＯＮＴＨＥＴＵＲＢＵＬＥＮＴＳＴＲＵＣＴＵＲＥＳＩＮＴＨＥＯＴＨＥＲＲＥＧＩＯＮＯＦＡＮＯＢＳＴＡＣＬＥＬｉｕＳｈｉ－ｈｅ（ＷｕｈａｎＵｎｉｖｅｒｓｉｔ...     

β—BBO晶体的电光性能

用干涉法测量了β－ＢＢＯ晶体的电光系数：γ２２＝２．６，γ３３＝０．２３，γ３１＝０．２５，γ５１＝－３．５×１０－１２ｍ／Ｖ。结果表明如果在Ｙ方向加电场，Ｚ方向通光，β—ＢＢＯ晶体可能制作成有应用价值的光开关。