Preparation and characterization of high molecular weight poly(hydroxy ethers) with unusually high glass transition temperatures

A series of novel poly(hydroxy ethers) have been prepared via polymerization of the diglycidyl ethers of bisphenol-A ( 4 ), 4,4 ′-tribromotetramethylbiphenol ( 6a ), and 4,4 ′-tetrabromotetramethylbiphenol ( 6b ) with a variety of rigid diols in an effort to systematically modify structural features of the phenoxy repeat unit in order to control the torsional mobility of polymer backbones and produce materials with softening temperatures higher than are typical for the class. The resulting poly(hydroxy ethers) displyed glass transition temperatures ranging from 109 to 242°C. There of the polymers were characterized with respect to tensile and impact properties and were compared to the polymer sythesized from bisphenol-A ( 1 ) and bisphenol-A diglycidyl ether ( 4 ).     

伊莫·麦凯伯

<正>Sylyester Mittee"我使用一支180mm镜头将画面聚焦在紧紧缠绕的绷带上。我看到过有些广告画面明显在模仿这幅作品,但他们永远无法捕捉这样一幅完美作品的精髓。轻微晃动给画面带来了独特的氛围。"     

如何让你的照片充满活力

<正>本期重点:1使用仿制图章工具2转换黑白影调和调整反差3调整画面影调与色彩4调整高光与增加细节5使用蒙版工具强化色彩和反差6调整构图与使用可选颜色7使用自由变换与调节曲线一张优秀的照片如何脱颖而出?是什么让它显得与众不同?如果你需要建议让自己的照片变得出色,我们的专家很乐意在此提供     

拉直倾斜的建筑

<正>George Cairns告诉我们如何使用镜头校正命令完善建筑摄影作品我们敢打赌大部分建筑都有拔地而起的90度垂直外墙。但是在拍摄建筑物照片的时候,由于透视畸变,所有垂直线条向一点汇聚,外墙的下半部分往往要比上半部分看上去宽很多。     

A new case of the unstable haemoglobin Genova (alpha 2 beta 2 28 (beta 10) leu leads to pro) in Canada: as a result of sporadic mutation and causing Heinz body haemolytic anaemia

The first case of the unstable Hb Genova as a result of sporadic mutation is described. It is found in a 3-year-old Canadian boy of East Indian extraction with chronic Heinz body haemolytic anaemia.