A K-band bi-phase modulator MMIC for UWB application

A 24-GHz-band, three-dimensional microwave monolithic integrated circuit (MMIC) bi-phase modulator, that is a combination of an active 0//spl pi/ splitter and a SPDT switch, is proposed and demonstrated. Comparing conventional K-band bi-phase modulators, this modulator is broadband, significantly MMIC compatible, and shrinks its chip area. A fabricated bi-phase modulator exhibits an area of 1.0/spl times/0.7mm/sup 2/ and a 1-dB bandwidth of nearly 10GHz. The SPDT switch is optimized in control-gate's time constant so that a very clear bi-phase modulated waveform can be generated from 1Gbps PN code. The insertion loss and the phase imbalance are 6.4 dB+/-0.6 dB and within 10/spl deg/, respectively, between 22GHz and 32GHz.     

Thermal Degradation Behavior of WOP2O7/Phenanthroline Complex

An intercalation compound of WOP₂O₇/phenanthroline and a mixture of WOP₂O₇/carbon black were prepared to have equal carbon contents. Both samples were heated below 1400°C under a nitrogen atmosphere and their thermal degradation behaviors compared, with the following results: (1) CO gas evolved through carbothermal reduction at a temperature 150°C lower in the intercalation compound than in the WOP₂O₇/carbon black mixture. (2) Both WP and W formed at temperatures approximately 100°C lower in the intercalation compound than in the mixture. (3) Thermal degradation occurred homogeneously throughout the intercalation compound particles, and the particle morphology remained favorable after thermal degradation.     

自适应巡航系统对高速公路交通安全及流量的影响

在建立了基于固定车头时距策略（constant time-gap,CTG）的自适应巡航系统模型的基础上,着重研究了不同车头时距下的自适应巡航系统对高速公路交通安全及流量的影响。模拟了一个八车队列在不同特殊行车工况下的响应,体现了自适应巡航系统的安全特性。在高速公路管道模型的基础上,讨论了不同车头时距下的自适应巡航系统对交通流量的影响,并对自适应巡航系统的适用条件提出了相应的建议。     

A thermally-stable self-mending polymer networked by Diels-Alder cycloaddition

A novel self-mending polymer with high thermal stability is developed based on the DA reaction between anthracene and maleimide. A network polymer, PEAA₂M₃ is prepared by the DA reaction of anthryl-telechelic poly(ethylene adipate) and a tris-maleimide. While the forward DA (addition) reaction is favored at room temperature, the reverse DA (dissociation) reaction is induced by mechanical stress. This mechanochemical reversibility allows the autonomous mending of cracks in PEAA₂M₃ at room temperature. It is well known that the thermal dissociation of the DA reaction occurs only at very high temperatures at which organic polymers degrades significantly. Therefore, thermal stability is successfully combined with self-mending ability in PEAA₂M₃.     

Quantitative determination of colored oily soil adhering to metal surface using digital image data

A method for calculating the amount of colored soil on a flat metal surface from digital image data was examined. Round samples cut out of SUS tape were soiled with oily soil mixed with sudan III, placed in sample bottles, and washed using a tube rotator. Images of the samples before and after the washing process were captured using a CCD camera and the image data were processed by a computer. The shine from the metallic surface was controlled by using indirect lighting. It was necessary to diminish the effect of the substrate's color, and to this end, we attempted to apply linear and non-linear color correction procedures. We found that the use of gamma correction after linear correction to remove the effect of the metal surface color was the most accurate quantitative method. Additionally, we conducted a washing test with commercial detergents using this quantitative method for image data and found that the removal process for the greasy soil from the metal surface could be expressed as a first-order reaction.     

In vitro release study of diltiazem hydrochloride from poly(vinyl pyrrolidone)/sodium alginate blend microspheres

Polymeric blend microspheres of poly(vinyl pyrrolidone) (PVP) with sodium alginate (NaAlg) were prepared by cross‐linking with calcium ions and used to deliver a calcium channel blocker drug, diltiazem hydrochloride (DT). The prepared microspheres were characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. Scanning electron microscopy confirmed the spherical nature of the particles. Preparation conditions for the microspheres were optimized by considering the percentage entrapment efficiency, particle size, and swelling capacity. Effects of variables such as PVP/NaAlg ratio, molecular weight of PVP, cross‐linker concentration, and drug/polymer ratio on the release of DT were discussed at two different pH values (1.2, 6.8) at 37°C. It was observed that DT release from the microspheres decreased with increasing molecular weight of PVP and extent of cross‐linking. However, DT release increased with increasing PVP content and drug/polymer ratio (d/p) of the blend microspheres. The highest DT release percentage was obtained as 99% for PVP/NaAlg ratio of 1/2 with d/p ratio of 1/2 at the end of 4 h. It was also observed from release results that DT delivery from the microspheres through the external medium are much higher at low pH (1.2) value than that of high pH (6.8) value. The drug release from the microspheres mostly followed Fickian transport. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008