Synthesis and characterization of well-defined comb-like branched polymers

Well-defined comb-like branched polymers having one branch in each repeating unit have been suc-cessfully synthesized by the coupling reaction of living polystyrene(PS)and polyisoprene(PI)anions with 1,1-diphenylethenyl(DPE)groups along PS backbone pre-pared via atom transfer radical polymerization(ATRP)of 4-vinylbenzyloxy benzophenone(Sc)followed by Wittig reaction.The resulting comb-like branched poly-mers were characterized by IR,1H-NMR,gel permeation chromatography(GPC)and static light scattering(SLS)in detail.The effect of living chains and DPE group molar ratio on grafting efficiency was discussed.The results show the coupling reaction of living chains and DPE groups was highly effective,and the coupling efficiency can be controlled via the feed molar ratios of living chains and DPE groups.Moreover,the effect of molecular weights of backbone(PSe)and PSLi or PILi on grafting efficiency was also discussed.The results show that when excess living polymers were used,the almost quantitative grafting efficiency could be achieved.

Consideration of climate change impacts will improve the efficiency of protected areas on the Qinghai-Tibet Plateau

The protection of migratory birds and their habitats is important to the ecological stability of the Qinghai-Tibet Plateau(QTP).Currently protected areas(PAs)were designed in accordance with species distribution patterns under current climatic conditions,thus ignoring climate change will lead to a decrease in the protection efficiency of PAs.In this study,using the flagship species Grus nigricollis,as an example,we used the maximum entropy(MaxEnt)model to simulate the distributions and conservation status of G.nigricollis and optimized the existing PA boundaries.The results showed that(1)suitable habitat-for G.nigricollis accounts for 12.48%of the QTP area,and the PAs established under current climatic conditions cover 17.84%of this suitable habitat area;(2)future climate changes will influence the distribution and quality of G.nigricollis habitats,and the average protection efficiency of the current PAs in four climatic scenarios will decrease from 17.84%to 15.31%;and(3)through optimization,the efficiency of existing PAs can be increased by 0.75 times and reach 28.37%,indicating PA planning must consider not only current climate conditions but also the effects of climate changes.Our results aim to address shortcomings in the conservation efficiency of PAs and provide an example for resolving mismatched PA boundaries and habitat changes for species.

Planar Magnetic Integrated Harmonic Filter with Reduced EMI Noise

Through the analysis of the circuit structure and electromagnetic interference(EMI)conduction path,the structure of the traditional harmonic filter is optimized so that it has the ability to suppress EMI.Using the structure of planar magnetic integration not only ensures the basic harmonic suppression ability of the harmonic filter,but also improves the EMI suppression effect.With a single-phase voltage source 500-W SiC inverter as the platform,the feasibility and effectiveness of the design scheme are experimentally verified.The results indicated that the planar magnetic integrated harmonic EMI filter satisfies the design requirements.Additionally,the proposed planar magnetic integration scheme can significantly reduce the volume and weight of the filter and increase the power density of the entire system.