首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
考研
Nano-sized toothbrushes that can clean very small surfaces have been developed by researchers. Fabricated out of millions of car
Nano-sized toothbrushes that can clean very small surfaces have been developed by researchers. Fabricated out of millions of car
admin
2020-03-31
35
问题
Nano-sized toothbrushes that can clean very small surfaces have been developed by researchers. Fabricated out of millions of carbon nanotubes, the minuscule brushes could even paint the inside of capillaries thinner than a human hair.
But besides being small, the nanotubes have other advantages over traditional bristles, says one of their creators Pulickel Ajayan at Rensselaer Polytechnic Institute in Troy, New York. The materials typically used for making brush bristles include animal hairs, synthetic polymer fibres and metal wires. But each has its limitations. Metals corrode and weaken, hair is not very strong and synthetic fibres melt.
Carbon nanotubes, on the other hand, are 30 times stronger than steel, yet five times less dense. They are highly elastic, resistant to heat, have large surface areas and even conduct electricity. The latter property makes them highly suitable for the contact brushes used in electric motors, says Ajayan.
He and Anyuan Cao at Rensselaer, in collaboration with colleagues at the University of Hawaii in Honolulu, U.S., have designed brushes consisting of a silicon carbide fibre base on which the carbon nanotubes are grown in a single row of bristles like a toothbrush, or in groups of bristles more like a toilet brush. One end of the base is coated with gold, which acts like a "handle" and also inhibits nanotube growth at that end. The dimensions can be varied dramatically, says Ajayan, but typically the bundle of nanotubes is no smaller than a few micrometres in diameter.
The brushes could have a variety of applications. They have already been used to sweep particles measuring just 50 nanometres in diameter off a plain surface, and off another surface pitted with microscopic grooves. The researchers have also attached the gold handle of a three-pronged brush to the shaft of a small electric motor. This allowed them to rotate the bristles inside a 300-micrometre-wide capillary tube, cleaning contamination off its walls. Then, by coating the brush with a red dye, they were able to paint the inside of the cavity using the same approach.
The brushes’ ability to clean small particles appears to be extremely good, says Ajayan, although he is still not sure why. "Perhaps the cleaning occurs by electrostatic interactions, and since the surface area of the nanostructures is large, the cleaning is possibly more effective." The aim now is to apply the brushes to more specific microelectronic and biomedical applications.
Gold is used in making the brushes because______.
选项
A、it is an excellent glue
B、it forces the nanotubes to grow in a given direction
C、it forms a particularly strong handle, or base, for the nanotubes
D、it can be moulded into different shapes
答案
B
解析
属细节题。A、D在文章中没有提到。原文第四段第四行指出,基底的一端要镀金,其作用就像一个把手(并不是形成一个特别有力的把手,所以排除C),同时也控制那一端纳米管的增长。故而选B。
转载请注明原文地址:https://kaotiyun.com/show/DE1Z777K
0
考研英语一
相关试题推荐
HenryKissingerpublishedanarticleintheJune2018AtlanticMonthlydetailinghisbeliefartificialintelligence(AI)threate
Whenyougotobed,isitbecauseyou’retiredorbecauseyouneedtogetupatacertaintimeandwanttomakesureyougeteno
"Googleisnotaconventionalcompany.Wedonot【C1】______tobecomeone,"wroteLarryPageandSergeyBrin,thesearchfirm’sfo
Drones,originallydevelopedformilitarypurposes,weren’tapprovedforcommercialuseintheUnitedStatesuntil2013.Whenth
Childrenmodelthemselveslargelyontheirparents.Theydosomainlythroughidentification.Childrenidentify【C1】______aparen
Childrenmodelthemselveslargelyontheirparents.Theydosomainlythroughidentification.Childrenidentify【C1】______aparen
Childrenmodelthemselveslargelyontheirparents.Theydosomainlythroughidentification.Childrenidentify【C1】______aparen
LucyhasjustwonthescholarshipinPekingUniversity.Asherfriend,pleasewritealettertoherto1)extendyoursincer
Despitethescandalsoverleakede-mails,thescientificevidenceforglobalwarmingremainsstrong.Thequestion,then,istow
"Beforetheoperation,IwouldlookatsomeoneandallIcouldseefortheirfacewasjelly,"saysJonathanWyatt"Now,Icanse
随机试题
男,58岁,因上腹部饱胀,隐痛5年,在门诊做肝造影和腹部B超均未见异常,胃镜检查诊断浅表性胃炎,此病人的治疗方案应该是
两艘同属巴拿马国籍的船舶在韩国海域发生碰撞,后均首先到达我国的大连港。其中一艘“玛丽号”向我国大连中级人民法院提起诉讼,并申请对另一艘碰撞船舶“哥白号”进行扣押。我国法院在审理此案时应适用的法律是:()。
背景某公司总承包航管楼,将劳务清包给一家劳务公司,合同签订时,按设计图和投标清单报价计算,以单价245元/m2(不含水电、门窗、楼梯扶手)签订了劳务承包协议。劳务公司进场后,迅速展开施工,由于原材料供应不及时、天气影响及垂直运输跟不上,共造成窝工5200
甲、乙签订的买卖合同约定了定金和违约金条款。甲违约,造成乙经济损失。下列选项中,乙可选择追究甲违约责任的方式有()。
会计是以货币为唯一的度量单位,反映和监督一个单位经济活动的一种经济管理工作。()
第二次技术革命的标志是()
2个优先级相同的并发进程P1和P2,它们的执行过程如下所示,假设当前信号量s1=0,s2=0,当前的z=2,进程运行结束后,x、y和z的值分别为()。进程P1进程P2y:=1;x:=1;y:=y+2;
Lookatthenotesonhowtosucceedinajobinterview.Someinformationismissing.Youwillhearpartofapresentationbythe
【B1】【B20】
Earthquakesoftenhappennearvolcanoes,butthisisnotalwaystrue.Thecentersofsomeare【L1】______.Thebottomoftheseas
最新回复
(
0
)