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
外语
If you are a fan of science fiction, you’ve no doubt encountered the term nanotechnol-ogy. Yet over the past year also, a series
If you are a fan of science fiction, you’ve no doubt encountered the term nanotechnol-ogy. Yet over the past year also, a series
admin
2017-03-25
40
问题
If you are a fan of science fiction, you’ve no doubt encountered the term nanotechnol-ogy. Yet over the past year also, a series of breakthroughs have transformed nanotech from sci-fi fantasy into a real world. Applied science, in the process, inspired huge investments by business, academia, and government. In industries as diverse as health care, computers, chemicals, and aerospace, nanotech is overhauling production techniques, resulting in new and improved products, some of which may already be in your home or workplace.
The inspiration for nanotech goes back to a 1959 speech by the late physicist Richard Feynman, then a professor at the California Institute of Technology, titled "There’s Plenty of Room at the Bottom. " Four decades later, Chad Mirkin, a Chemistry professor at Northwestern University’s $34 million nanotech center, used a nanoscale device to etch most of Feynman’s speech onto a surface the size of about 10 tobacco smoke particles.
What accounts for the sudden acceleration of nanotechnology? A key breakthrough came in 1990, when researchers at IBM’s Almaden Research Center succeeded in rearranging individual atoms at will. Using a device known as a scanning probe microscope, the team slowly moved 35 atoms to spell the three-letter IBM logo, thus proving Feynman right. The entire Logo was less than three nanometers.
Soon, scientists were not only manipulating individual atoms but "spray painting" with them as well. Using a tool known as a molecular beam epitaxy, scientists have learned to create ultra fine films of specialized crystals, built up one molecular layer at a time. This is the technology used today to build read-head components for computer hard drives.
The next stage in the development of nanotechnology borrows a page from nature. Building a supercomputer no bigger than a speck of dust might seem an impossible task, until one realizes that evolution solved such problems more than a billion years ago. Living cells contain all sorts of nanoscale motors made of proteins that perform myriad mechanical and chemical functions, from muscle contraction to photosynthesis. In some instances, such motors may be re-engineered, or imitated, to produce products and processes useful to humans.
How are these biologically inspired machines constructed? Often, they construct themselves, manifesting a phenomenon of nature known as self assembly. The macromole-cules of such biological machines have exactly the right shape and chemical binding preferences to ensure that when they combine they will snap together in predesigned ways. For example, the two strands that make up DNA’s double helix match each other exactly, which means that if they are separated in a complex chemical mixture, they are still able to find each other easily.
Scientists created ultra fine films of specialized crystals by means of______.
选项
A、a scanning probe microscope
B、a nanoscale device
C、a molecular beam epitaxy
D、a super computer
答案
C
解析
本题的四个选项中,只有C项为正确答案。这可从文中第四段的第二句话“Using a tool known as a molecular beam epitaxy…of specialized crystals…”推知,即科学家使用的是a molecular beam epitaxy来制造ultra fine films of specialized crystals。
转载请注明原文地址:https://kaotiyun.com/show/aZGO777K
0
考博英语
相关试题推荐
Sincetheenergycrisis,thesebigcarshavebecomearealliability.Theycosttoomuchtorun.
Iwasmostfavorablystruckbytheassurancewithwhichtheboyansweredallmyquestions.
Theschoolauthority______againststudents’smokingbothintheclassroomsandathome.
Womenhavesignificantadvantagesovermeninspacebecausetheyneedlessfoodandlessoxygenandthey______radiationbetter
Woodyarrivedatamost______moment;Iwasjustgettingintothebath.
It’sallannualback-to-schoolroutine.Onemorningyouwavegoodbye,andthat【C1】______eveningyou’reburningthelate-night
Thesearchforthelostshipmustbe______becauseofpoorweather.
Duringaninternationalcrisis,many____messageswillgenerallyemanatefromthepresident’soffice.
Youaretowriteacompositionofnolessthan250wordsanddoyourcompositionneatlyontheAnswerSheet.Ypurcompositionsh
Whatdoconsumersreallywant?That’saquestionmarketresearcherswouldlovetoanswer.Butsincepeopledon’talwayssaywhat
随机试题
在测定含悬浮物的饮料样品中的可溶性固形物含量时,样液制备的方法是()。
下肢静脉血栓形成,溶栓疗法的首选药物是
下列哪项眼征不是由交感神经兴奋性增高引起的
在逆行性尿路造影检查中,可能出现下列哪种正常生理性改变
男性,22岁。发烧2天。同时伴有乏力、腹痛、出现无痛性肉眼血尿。查体:体温38℃。脊肋角及输尿管压痛阳性,尿白细胞10~15/高倍镜。其原因是
A.粘连性肠梗阻B.肠扭转C.肠套叠D.蛔虫性肠梗阻E.麻痹性肠梗阻驱虫不当易引起
企业处置一项以公允价值模式计量的投资性房地产,实际收到的金额为100万元,投资性房地产的账面余额为80万元。其中成本为70万元,公允价值变动为10万元。该项投资性房地产是由自用房地产转换的,转换日公允价值大于账面价值的差额为12万元。假设不考虑相关税费,处
企业因员工工资的集中发放而进行筹资的动机属于()。
中古调式:
根据以下资料,回答问题。到2010年末,股民资金开户数比2005年末增长了大约()。
最新回复
(
0
)