Papers by Keyword: Y-Shaped

Abstract: In this article, a new structure of dual band pass FSS is simulated and analyzed. The improved FSS structure, which satisfies the requirement of miniature, is much simpler than traditional one and has lower working frequency band, and it provides a new way to solving the problem of the coupling effect of dual bands. Besides, its response towards electric field is invariant. The response has no obvious change when the incident angles change a lot.

Abstract: A series of techniques, including field emission scanning electron microscopy, transmission electron microscopy, X-ray powder diffraction, and energy dispersive X-ray spectroscopy were employed to investigate three types of Y-shaped carbon fibers that were synthesized by the thermal decomposition of acetylene using an atmospheric pressure catalytic chemical vapor deposition process and copper tartrate as a catalyst precursor. On the basis of electron microscopy analysis, we propose that the simultaneous growth of three pieces of carbon fibers on the same copper catalyst particle results in the formation of Y-shaped carbon fibers. When several copper catalyst particles became positioned in a stratified arrangement, other types of Y-shaped carbon fibers were obtained. Our study indicates that the morphology of various Y-shaped carbon fibers can be controlled by tailoring the configuration of the copper catalyst particles used to generate them.

Abstract: Novel Y-shaped amphiphilic block copolymers of poly(ethylene glycol) and poly(N-isopropylacrylamide), PEG-b-(PNIPAM)2, were successfully synthesized through atom transfer radical polymerization (ATRP). A difunctional macroinitiator was prepared by esterification of 2,2-dichloroacetyl chloride with poly(ethylene glycol) monomethyl ether (PEG). The copolymers were obtained via the ATRP of N-isopropylacrylamide (NIPAM) with CuCl/Me6TREN as catalyst and DMF/H2O (v/v = 3:1) mixture as solvent. The resulting polymers were characterized by gel permeation chromatography (GPC) and 1H NMR. These block copolymers show controllable molecular weights and narrow molecular weight distributions (PDI <1.15). Their phase transition temperatures and enthalpy changes in aqueous solution were measured by differential scanning calorimetry (DSC). The results indicate a significant influence of the macromolecular architecture on the phase transition. This is the first study into the effect of molecular architecture on the phase transition using Y-shaped amphiphilic block copolymer composed of PEG and PNIPAM.