精密控制纳米微粒的大小、形状和成分-凯发k8官网

精密控制纳米微粒的大小、形状和成分
文章来源:未知 文章作者:meng 发布时间:2010-09-02 03:01 字体: [ ] 
(单词翻译:双击或拖选)

with growing interest in using nanoparticles for everything from antibacterial(抗菌的) socks to medical imaging to electronic devices, the need to understand the environmental, health and safety risks of these particles also grows. researchers at the national institute of standards and technology (nist) have developed a simple process for producing nanocrystals that will enable studies of certain physical and chemical properties that affect how nanoparticles interact with the world around them. because nanoparticles behave differently from bulk(体积,容量) samples of the same material, new tests to understand how they affect biological systems must be developed. toxicologists(毒理学家) determine the hazards(危害,危险) posed by nanoparticles by introducing them to a biological system and monitoring the effects, but they currently lack a set of control particles whose size, shape and composition have been carefully produced and characterized.

in a recent paper published in angewandte chemie, nist scientists describe a one-step process that allows them to control the size, shape and composition of gold-1 2 nanocrystals to create perfect-edged nanocubes as small as 3.4 nanometers—just half the thickness of a cell wall and on the same size range as 3.

the researchers combined and heated gold and copper 4 with other chemicals to produce highly crystalline(透明的,水晶般的) , homogeneous(均匀的) , perfect nanocubes with abundant yield. to study the formation process, they removed samples at 1 hour, 1.5 hours, 5 hours, and 24 hours and found that just five hours were needed to produce 5 cubic nanoparticles of uniform size. by adjusting the ratios of the chemicals in the original solution and the reaction time, they were able to 6 control the size, shape and composition of the nanocubes. this process is unique in allowing control of the ratio of copper to gold atoms within the nanocube to either 3:1 or 1:3.

"it's a simple process, and to the best of our knowledge is the first to use 7 chemistry, or 'bottom up' technology, to produce gold-containing nanocubes below 5 nanometers. anything less than 10 nanometers has been extremely challenging due to the mobile behavior of the gold atoms," says nist 8 angela r. hight walker, who wrote the paper with yonglin liu, a guest researcher at nist.

the nist-developed process for creating such nanocubes will allow toxicologists to 9 alter one of the nanocubes' characteristics and observe how the change affects the biological response, if at all.

this synthesis(综合,合成) and the resulting high-quality nanocubes may have other applications in areas such as solar energy, says liu. "typically, we cannot make big 10(批次) of high-quality samples for testing; now we can."

the perfect-edged nanocubes are unique from other nanocubes in the literature, says hight walker. the sharp edges, as opposed to 11(缩短了的) or rounded edges, will enable different, more reactive chemistry that could be beneficial in applications such as catalysis(催化作用,刺激作用) —in which the nanocubes would be used to 12 or enhance a chemical reaction.



点击收听单词发音收听单词发音  

1 hzxyu     
n.铜;铜币;铜器;adj.铜(制)的;(紫)铜色的
参考例句:
  • the students are asked to prove the purity of copper.要求学生们检验铜的纯度。
  • copper is a good medium for the conduction of heat and electricity.铜是热和电的良导体。
2 flryq     
n.合金,(金属的)成色
参考例句:
  • the company produces titanium alloy.该公司生产钛合金。
  • bronze is an alloy of copper and tin.青铜是铜和锡的合金。
3 4u3z1l     
(缩)deoxyribonucleic acid 脱氧核糖核酸
参考例句:
  • dna is stored in the nucleus of a cell.脱氧核糖核酸储存于细胞的细胞核里。
  • gene mutations are alterations in the dna code.基因突变是指dna密码的改变。
4 5e19fce64ab14f5a4b5c8687640c2593     
n.先驱( precursor的名词复数 );先行者;先兆;初期形式
参考例句:
  • phenyl (or polyphenyl) substituted epoxides serve as excellent precursors to phenyl (or diphenyl) carbenes. 某些苯代(或多苯)环氧乙烷是制取带苯环(或二苯)碳烯的极好原料。 来自辞典例句
  • note the presence of megakaryocytes, erythroid islands, and granulocytic precursors. 可见巨核细胞,红细胞岛和粒细胞前体细胞。 来自互联网
5 8mzxb     
adv.完美地,无可非议地,彻底地
参考例句:
  • the witnesses were each perfectly certain of what they said.证人们个个对自己所说的话十分肯定。
  • everything that we're doing is all perfectly above board.我们做的每件事情都是光明正大的。
6 zlwzub     
adv.恰好,正好,精确地,细致地
参考例句:
  • it's precisely that sort of slick sales-talk that i mistrust.我不相信的正是那种油腔滑调的推销宣传。
  • the man adjusted very precisely.那个人调得很准。
7 zhtzy     
adj.合成的,人工的;综合的;n.人工制品
参考例句:
  • we felt the salesman's synthetic friendliness.我们感觉到那位销售员的虚情假意。
  • it's a synthetic diamond.这是人造钻石。
8 onqx4     
n.物理学家,研究物理学的人
参考例句:
  • he is a physicist of the first rank.他是一流的物理学家。
  • the successful physicist never puts on airs.这位卓有成就的物理学家从不摆架子。
9 7qhwn     
adv.有系统地
参考例句:
  • this government has systematically run down public services since it took office.这一屆政府自上台以来系统地削减了公共服务。
  • the rainforest is being systematically destroyed.雨林正被系统地毀灭。
10 f8c77c3bee0bd5d27b9ca0e20c216d1a     
一批( batch的名词复数 ); 一炉; (食物、药物等的)一批生产的量; 成批作业
参考例句:
  • the prisoners were led out in batches and shot. 这些囚犯被分批带出去枪毙了。
  • the stainless drum may be used to make larger batches. 不锈钢转数设备可用来加工批量大的料。
11 ac273a9aa2a7a6e63ef477fa7f6d1980     
adj.切去顶端的,缩短了的,被删节的v.截面的( truncate的过去式和过去分词 );截头的;缩短了的;截去顶端或末端
参考例句:
  • my article was published in truncated form. 我的文章以节录的形式发表了。
  • oligocene erosion had truncated the sediments draped over the dome. 覆盖于穹丘上的沉积岩为渐新世侵蚀所截削。 来自辞典例句
12 z6hxz     
vt.开始,创始,发动;启蒙,使入门;引入
参考例句:
  • a language teacher should initiate pupils into the elements of grammar.语言老师应该把基本语法教给学生。
  • they wanted to initiate a discussion on economics.他们想启动一次经济学讨论。
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