Telomeres maintain chromosome stability and cell replicative capacity. Telomere shortening occurs concomitant with aging. Short telomeres are associated with some diseases, such as dyskeratosis congenita, idiopathic pulmonary fibrosis, and aplastic anemia. Telomeres are longer in pluripotent stem cells than in somatic cells and lengthen significantly during preimplantation development. Furthermore, telomere elongation during somatic cell reprogramming is of great importance in the acquisition of authentic pluripotency. This review focuses primarily on regulatory mechanisms of telomere length maintenance in pluripotent cells, telomere length extension in early embryo development, and also telomere rejuvenation in somatic cell reprogramming. Telomere related diseases are also discussed in this review.
Urban infrastructure has been substantially upgraded in reform-era China. This paper explains, contextually and empirically, how Chinese cities finance their infrastructure. It demonstrates that China has succeeded in addressing urban infrastructure backlogs by opening up new venues for financing, but simultaneously, heavily relying on unconventional sources. The paper also argues that urban infrastructure financing has much to do with the country’s transition to a market-oriented economy that fosters the pro-growth role of city governments as well as the redistribution of fiscal power between the levels of the urban hierarchy that produces significant variation of financial capacities among the different administrative ranks of cities.
A series of novel triblock copolymers of poly(stearyl methacrylate)-b-poly(N-isopropylacrylamide)-b-poly(stearyl methacrylate) (PSMA-b-PNIPAAm-b-PSMA) with different molecular weights was synthesized through carboxyl-terminated trithiocarbonates as a highly efficient RAFT agent via reversible addition-fragmentation chain transfer (RAFT) polymerization. The resultant polymers were characterized by 1H NMR, FT-IR spectroscopy, and GPC. By varying the organic solvent used in the self-assembly procedure and adjusting the copolymer composition, multiple morphologies ranging from vesicles and core-shell spherical aggregates with different dimensions to pearl-necklace-like aggregates were obtained. The aggregates showed thermoresponsive and pH-responsive properties through the lower critical solution temperature (LCST) of PNIPAAm and the two carboxyl end groups of the copolymer.
Summary: In this work, epoxy resin/CaCO3 nanocomposites were prepared by in situ and inclusion polymerization. Nanoparticles with a size of 30–40 nm were dispersed efficiently in bisphenol‐A alkaline solution before polymerization and the dispersion could be kept in the resultant composite by a reaction that took place at the nanoparticle surface and among the nanoparticles when epichlorohydrin was added. Furthermore, the slightly conglomerated nanoparticles could even be separated by epoxy resin growing among them. This method showed a better dispersion of nanoparticles compared with solution‐blending as observed with TEM. Owing to better combination of epoxy resin and nanoparticles, the resultant nanocomposite showed a 12 °C increase in Tg compared to the nanocomposite prepared by solution‐blending. Tensile test revealed that the tensile strain of nanocomposites rises as the nano‐CaCO3 content increases.The dispersion mechanism of nanoparticles through in situ and inclusion polymerization.magnified imageThe dispersion mechanism of nanoparticles through in situ and inclusion polymerization.
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