The experimental and numerical study of the behaviour of polymers in concentrated solutions is a line of research that is still highly active. In the past, it enabled us to understand why materials like rubber have certain elastic1（弹性的） properties. A distinctive2 feature of these systems is that the long chained molecules3 composing them tend to penetrate4 each other and interweave at their ends forming very durable5 bonds that make them always return to their initial conformation whenever they are stretched. The behaviour of dense6 solutions of ring polymers, i.e., polymers that form closed loops like rings and have no free ends, is very different. Angelo Rosa, a theoretical physicist7 from the International School for Advanced Studies in Trieste, and Ralf Everaers from the cole Normale Suprieure de Lyon devised a highly efficient numerical method to study these materials, a method which they intend to apply to biology in the future.Ring polymers - by construction - dont have free ends and so when in a solution they cannot interweave with each other and form bonds as the more common linear polymers do, explains Rosa. This causes them to behave very differently from linear polymers. So we wanted to understand the physics of these peculiar8 solutions and we constructed some models of ring polymers that allowed us to predict their behaviour. We then compared the models we created with other earlier simulations conducted with different methods, and found that they confirmed our findings.The really interesting thing about our study is that it considerably9 reduces analysis time, which means the method is highly efficient, the researcher adds. We found that compared to dense solutions of linear polymers, which form the base of the more common visco-elastic materials such as rubber, these materials are much more fragile because a ring polymer interweaves very little with the others and remains10 TOPologically always confined within a restricted region.Rosa and Everaers point out that they will now continue to develop their research in the field of biology. We think that our models of ring polymers are useful to understand chromosomes12 dissolved in the cell nucleus13, says Rosa. Even though it isnt a circular polymer, a chromosome11 behaves in a very similar manner, in that it remains TOPologically isolated14 from the other chromosomes dissolved in the cyTOPlasm（细胞质） for a long time.
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1 elastic n.橡皮圈，松紧带；adj.有弹性的；灵活的 参考例句： Rubber is an elastic material.橡胶是一种弹性材料。 These regulations are elastic.这类规定是有弹性的。
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