硒化镉量子点在土壤中分解产生有毒物质-凯发k8官网

硒化镉量子点在土壤中分解产生有毒物质
文章来源:未知 文章作者:enread 发布时间:2011-07-19 02:31 字体: [ ] 
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quantum dots made from cadmium(镉) and selenium(硒) degrade in soil, 1 2 cadmium and selenium ions into their surroundings, a university at 3 study has found. the research, accepted for publication in the journal environmental science and technology, demonstrates the importance of learning more about how quantum dots -- and other nanomaterials -- interact with the environment after disposal, said diana aga, the chemistry professor who led the study.

quantum dots are 4 nanocrystals with diameters of about 2 to 100 nanometers. though quantum dots are not yet commonly used in consumer products, scientists are exploring the particles' applications in technologies ranging from solar panels to biomedical imaging.

"quantum dots are not yet used widely, but they have a lot of potential and we can anticipate that the use of this nanomaterial will increase," said aga, who presented the findings in late june at a national science foundation-funded workshop on nanomaterials in the environment. "we can also anticipate that their occurrence in the environment will also increase, and we need to be proactive(有前瞻性的) and learn more about whether these materials will be a problem when they enter the environment."

"we can conclude from our research that there is potential for some negative impacts, since the quantum dots biodegrade. but there is also a possibility to modify the chemistry, the surface of the nanomaterials, to prevent 5 in the future," she said.

aga's research into the afterlife of quantum dots is funded by a $400,000 environmental protection agency grant to investigate the environmental transport, biodegradation and bioaccumulation of quantum dots and 6 nanoparticles.

her collaborators on the new study in environmental science and technology include phd student divina navarro, assistant professor sarbajit banerjee and associate professor david watson, all of the ub department of chemistry.

working in the laboratory, the team tested two kinds of quantum dots: cadmium selenide quantum dots, and cadmium-selenide quantum dots with a protective, 7-sulfide shell. though the shelled quantum dots are known in scientific literature to be more stable, aga's team found that both varieties of quantum dot leaked toxic elements within 15 days of entering soil.

in a related experiment designed to predict the likelihood that discarded quantum dots would 8 into groundwater, the scientists placed a sample of each type of quantum dot at the top of a narrow soil column. the researchers then added 9 chloride(氯化钙) solution to 10 rain.

what they observed: almost all the cadmium and selenium detected in each of the two columns -- more than 90 percent of that in the column holding unshelled quantum dots, and more than 70 percent of that in the column holding shelled quantum dots - -remained in the top 1.5 centimeters of the soil.

but how the nanomaterials moved depended on what else was in the soil. when the team added ethylenediaminetetraacetic acid (edta) to test columns instead of calcium chloride, the quantum dots traveled through the soil more quickly. edta is a chelating agent, similar to the citric acid(柠檬酸) often found in soaps and laundry 11(洗衣粉) .

the data suggest that under normal circumstances, quantum dots resting in top soil are unlikely to 12(探索,寻找) their way down into underground water tables, unless chelating agents such as edta are introduced on purpose, or naturally-occurring organic acids (such as plant exudates) are present.

aga said that even if the quantum dots remain in top soil, without contaminating underground 13, the particles' degradation still poses a risk to the environment.

in a separate study submitted for publication in a different journal, she and her colleagues tested the reaction of arabidopsis plants to quantum dots with zinc sulfide shells. the team found that while the plants did not absorb the nanocrystals into their root systems, the plants still displayed a typical phytotoxic reaction upon coming into contact with the foreign matter; in other words, the plants treated the quantum dots as a poison.



点击收听单词发音收听单词发音  

1 8742c1b567c83ec8d9e14c8aeacbc729     
v.把(感情、力量等)释放出来,发泄( unleash的现在分词 )
参考例句:
  • company logos: making people's life better by unleashing cummins power. 公司理念:以康明斯动力建设更美好的生活! 来自互联网
  • sooner or later the dam will burst, unleashing catastrophic destruction. 否则堤坝将崩溃,酿成灾难。 来自互联网
2 inswc     
adj.有毒的,因中毒引起的
参考例句:
  • the factory had accidentally released a quantity of toxic waste into the sea.这家工厂意外泄漏大量有毒废物到海中。
  • there is a risk that toxic chemicals might be blasted into the atmosphere.爆炸后有毒化学物质可能会进入大气层。
3 1sby4     
n.(北美)野牛;(亚洲)水牛
参考例句:
  • asian buffalo isn't as wild as that of america's. 亚洲水牛比美洲水牛温顺些。
  • the boots are made of buffalo hide. 这双靴子是由水牛皮制成的。
4 uzuwq     
n.半导体
参考例句:
  • in the beginning,engineers hoped to use semiconductor lasers.在开始时,工程师们希望能够利用半导体激光器。
  • the main agent of the company brand semiconductor sales.本公司主要代理各品牌半导体销售。
5 qxkxl     
n.降级;低落;退化;陵削;降解;衰变
参考例句:
  • there are serious problems of land degradation in some arid zones.在一些干旱地带存在严重的土地退化问题。
  • gambling is always coupled with degradation.赌博总是与堕落相联系。
6 k4dz8     
n.氧化物
参考例句:
  • oxide is usually seen in our daily life.在我们的日常生活中氧化物很常见。
  • how can you get rid of this oxide coating?你们该怎样除去这些氧化皮?
7 dfxwx     
n.锌;vt.在...上镀锌
参考例句:
  • brass is formed by the fusion of copper and zinc.黄铜是通过铜和锌的熔合而成的。
  • zinc is used to protect other metals from corrosion.锌被用来保护其他金属不受腐蚀。
8 uxcyn     
v.分离,过滤掉;n.过滤;过滤器
参考例句:
  • liquid water can leach soluble materials from the interface.液态水能够从界面溶解出可溶性物质。
  • they believe that the humic materials are leached from decaying plant materials.他们认为腐植物料是从腐烂的植物体浸沥而来。
9 sndzy     
n.钙(化学符号ca)
参考例句:
  • we need calcium to make bones.我们需要钙来壮骨。
  • calcium is found most abundantly in milk.奶含钙最丰富。
10 pd2xc     
v.模仿,戏弄;n.模仿他人言行的人
参考例句:
  • a parrot can mimic a person's voice.鹦鹉能学人的声音。
  • he used to mimic speech peculiarities of another.他过去总是模仿别人讲话的特点。
11 2f4a6c42e9c2663b781bda4f769407b9     
n.洗涤剂( detergent的名词复数 )
参考例句:
  • such detergents do not yellow the wool as alkali tends to do. 这种洗涤剂不会象碱那样使羊毛发黄。 来自辞典例句
  • development of detergents has required optimization of the surfactants structure. 发展洗涤剂时,要求使用最恰当的表面活性剂结构。 来自辞典例句
12 esaza     
vt.挖掘(洞穴);钻进;vi.挖洞;翻寻;n.地洞
参考例句:
  • earthworms burrow deep into the subsoil.蚯蚓深深地钻进底土。
  • the dog had chased a rabbit into its burrow.狗把兔子追进了洞穴。
13 25c4600513b703affac796567751e105     
n.地下蓄水层,砂石含水层( aquifer的名词复数 )
参考例句:
  • and in africa, the aquifers barely recharge at all. 非洲的地下水开采以后几乎得不到补充。 来自时文部分
  • aquifers have water contents over 30%. 含水层的水含过30%。 来自辞典例句
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