题干

生物电池可以利用蜗牛体内葡萄糖发电。我们在蜗牛壳上钻孔,把覆盖着酶的电极植入聚集在蜗牛身体和壳之间的血淋巴,也就是蜗牛的血液中。与其他类型的电池类似,我们的电池也是基于化学反应来让电子流动的;一个电极捕获血淋巴中葡萄糖的电子,之后这些电子会通过外部回路——包括我们想要供电的任何设备——抵达相对的电极。在那里,电子与血淋巴中的氧反应形成水,输出的电力很微弱,在微瓦的量级上,而且在数分钟后会因葡萄糖耗尽而断电。收获能量之后,蜗牛通过吃喝会恢复体内的葡萄糖水平,就可以再次发电了。而蜗牛看来并没有受到生物电池的伤害。

电池的输出功率受两个因素的限制:蜗牛微小身体内的葡萄糖含量,以及葡萄糖向电极扩散所用的时间。如果医生把类似的某种装置植入人体而不是蜗牛体内,我们就能获得更强更持久的电流,因为人类血液中的葡萄糖含量要比蜗牛的高,而且人类的循环系统会持续把新的葡萄糖补充给电极(蜗牛没有闭合的循环系统)。一个想法是用我们的生物电池基于人体内烦人的修改版来为植入医疗设备供电,例如起搏器,蜗牛不能为手机充电,但它能为微型传感器供电,这促成另一个想法——让蜗牛、蠕虫和昆虫为环境鉴别和国土安全服务。

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    There are two basic ways to see growth:one as a product,the other as a process.People have generally viewed personal growth as an external(外在的)result or a product that can easily be identified and measured.The worker who gets a rise,the student whose grades improve,the foreigner who learns a new language—all these examples of people who have measurable results to show for their efforts.

    By contrast(对照),the process of personal growth is much more difficult to determine,since it is a journey and not the specific signposts or landmarks along the way.The process is not the road itself,but the attitudes,feelings people have,and their caution or courage,as they meet with new experiences and unexpected difficulties.In this process,the journey never really ends;there are always new ways to experience the world,new ideas to try,new challenges to accept.

    In order to grow,to travel new roads,people need to have a willingness to take risks,to face the unknown,and to accept the possibility that they may“fail”at first.How we see ourselves as we try a new way of being is necessary for our ability to grow.Do we see ourselves as quick and curious?If so,we tend to take more chances and be more open to unfamiliar experiences.Do we think we're shy and indecisive?Then our sense of fear can cause us to hesitate,to move slowly,and we think we are slow to adapt(适应)change or that we're not smart enough to deal with a new challenge.Then we are likely to take a more passive role or not try at all.

    These feelings of insecurity(不安全)and self­doubt are both unavoidable and necessary if we are to change and grow.If we protect ourselves too much,then we stop growing.We become trapped inside a shell of our own making.

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