Interaction between poly(vinyl pyridine) and poly(2,6-dimethyl-1,4-phenylene oxide): A copolymer blend miscibility study

The phase behavior of blends of poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) with random copolymers of styrene and 2-vinyl pyridine, Poly(S-co-2VP), as well as with random copolymers of styrene and 4-vinyl pyridine, Poly(S-co-4VP), has been investigated in order to estimate the values of the Flory-Huggins parameters χPPO,2VP and χPPO,4VP between PPO and 2-vinyl pyridine, resp. 4-vinyl pyridine. Using previously estimated values for the Flory-Huggins parameters 0.09<χS,2VP<0.11 and 0.30<χS,4VP<0.35, together with the literature value of χS,PPO=−0.043, the phase behavior observed as a function of the copolymer composition results in 0.11≤χPPO,2VP≤0.12 and 0.46≤χPPO,4VP≤0.48. Insight in the interaction between PPO and poly(vinyl pyridine) is of considerable interest for several nanotechnology developments, since PPO is used to improve the mechanical properties of e.g. PS-block-P4VP nanorods.     

Influence of different dispersants on the quality and stability of aqueous quinacridone magenta pigment dispersion for ink-jet applications

The stability of water-based pigment dispersions is a key factor in determining their utility in ink-jet applications, and the appropriate choice of dispersant plays a special role. Among the pigment formulations tested to date, literature data on magenta pigments are very limited. Thus, the goal of this work was to study the influence of the type and loading of dispersants on the quality and stability of quinacridone magenta pigment dispersions. Three different commercially available dispersants were tested: (1) a cationic styrene-maleic anhydride copolymer, (2) an anionic polyacrylate, and (3) a nonionic alkyl ethoxylate. Pigment and dispersing agents were analysed using the Fourier Transform–infrared method. The stability of pigment dispersions was determined by comparative studies of changes in the pigment particle size, viscosity, pH, filtration time, optical density and gloss during the accelerated ageing test. Moreover, Turbiscan AGS and LUMiFuge analysers were used for evaluations of the instability of the dispersions. The properties of each dispersing agent affected the performances of the different dispersants. The highest stability for the pigment formulations was provided using the nonionic dispersant (small particle size, < 60 nm; the lowest viscosity < 60 mPa·s at the optimal dispersant content; favourable results of the filtration test; the highest pigment dispersability, proven by optical density and gloss). The Turbiscan AGS and LUMiFuge results indicated that the stability of all tested quinacridone magenta pigment dispersions was excellent (Turbiscan Stability Index values below three, and no significant differences in transmission profiles, respectively). However, it was found that the measurement results were influenced by the viscosity of the formulations.     

A 160-MHz analog equalizer for magnetic disk read channels

This paper presents a 160-MHz five-tap adaptive analog equalizer for magnetic recording disk drive read channels. The design is based on a direct form finite impulse response (FIR) architecture which includes four key features: signal shuffling in the analog domain to improve noise performance, use of a master sample-and-hold stage to improve the dynamic performance and clock jitter of the clock recovery loop, use of an additional sample-and-hold stage to accommodate settling time requirements and reduce power, and use of a time interleaved sign-sign LMS algorithm which permits coefficient adaptation at low power and area. This equalizer occupies 1.36 mm² and consumes only 240 mW with 5-V supply voltage. It is fabricated in BiCMOS technology with 0.8-μm CMOS and 0.72-μm² NPN, 3LM, and DP capacitor     

紫外可调谐激光晶体Ce^3＋：LiSrAlF6生长及其光谱特性

在国内首次用提拉法生长出Ｃｅ＾３＋：ＬｉＳｒＡｌＦ６晶体,晶体尺寸达φ２０ｍｍ×８０ｍｍ,测定了其在室温下的吸收及发射光谱,并计算了晶体的主吸收系数及残余吸收系数。