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
51
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
Whenpeopletalkabouta"north-southdivide"inBritaintheyareusuallyreferringtohouseprices,employmentandtheratioof
Whenyougotobed,isitbecauseyou’retiredorbecauseyouneedtogetupatacertaintimeandwanttomakesureyougeteno
"Googleisnotaconventionalcompany.Wedonot【C1】______tobecomeone,"wroteLarryPageandSergeyBrin,thesearchfirm’sfo
"Googleisnotaconventionalcompany.Wedonot【C1】______tobecomeone,"wroteLarryPageandSergeyBrin,thesearchfirm’sfo
Theterme-commercereferstoallcommercialtransactionsconductedovertheInternet,includingtransactionsbyconsumersandb
Healthimpliesmorethanphysicalfitness.Italsoimpliesmentalandemotionalwell-being.Anangry,frustrated,emotionally【C1
Childrenmodelthemselveslargelyontheirparents.Theydosomainlythroughidentification.Childrenidentify【C1】______aparen
Despitethescandalsoverleakede-mails,thescientificevidenceforglobalwarmingremainsstrong.Thequestion,then,istow
Americans’prideandfaithoftheireconomicsystem,【C1】______thatitprovidesopportunitiesforallcitizenstohavegoodliv
随机试题
下列哪项是临床确定患者存在急性心肌损害最有价值的指标
神经精神狼疮的临床表现有
A.二硫化二砷(As2S2)B.含水硅酸镁[Me3(Si4O10)(OH)2]C.三氧化二铁(Fe2O3)D.三氧化二砷(As2O3)E.硫化汞(HgS)
某机电安装施工单位通过招投标中标一地下动力中心安装工程,建筑物为现浇钢筋混凝土结构,并已施工完成。预埋的照明电线管和其他预埋工作经检查无遗漏。地下建筑物的平面及剖面简图如图2H320060—5所示。设备布置和设计要求是:一2.600层I区安装冷
自理报检单位的权利包括()。
甲公司为一生产钢材的企业,近年来由于钢材市场利润率下降,企业的收益大幅度降低。为了寻求进一步发展,甲公司于2012年至2014年实施了一系列并购和其他相关交易。资料一(1)2012年7月1日,甲公司与A公司的原股东远洋公司签订股权转让合
风险报酬率是指投资者因冒风险进行投资而要求的超过资金时间价值的那部分额外报酬率。()
在量表编制过程中,因素分析的主要目的是()。(2011年)
(1996年)设函数y=y(χ)由方程2y3-2y2+2χy-χ2=1所确定,试求y=y(χ)的驻点,并判别它是否为极值点.
Whilestillcatchinguptomeninsomespheresofmodernlife,womenappeartobewayaheadinatleastoneundesirablecategory
最新回复
(
0
)