| 项目编号: | 1549519
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| 项目名称: | EAGER: External Injection of Electrons and Holes in As- Manufactured Nanomaterials to Understand Environmental Hazards |
| 作者: | Amar Nath
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| 承担单位: | University of North Carolina at Asheville
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| 批准年: | 2014
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| 开始日期: | 2015-08-15
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| 结束日期: | 2018-05-31
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| 资助金额: | USD149942
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| 资助来源: | US-NSF
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| 项目类别: | Standard Grant
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| 国家: | US
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| 语种: | 英语
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| 特色学科分类: | Engineering - Chemical, Bioengineering, Environmental, and Transport Systems
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| 英文关键词: | nanomaterial
; electron
; carbon nanotube
; environmental hazard
; health hazard
; model
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| 英文摘要: | 1549519(Nath)
It is well known that ultrafine particles regardless of their origin or chemical nature are an environmental hazard. The question arises as to why any material when subdivided to a very fine powder (nanomaterial) becomes hazardous. Part of it has to do with the aerodynamics of the lungs. More importantly, in very small particles where the surface is large, some of the atoms or molecules on the surface are displaced from their regular sites forming what is known as "defects". These intrinsic defects often trap stray electrons, which are loosely bound according to our proposed model. The nature and concentration of the defects varies from material to material. No systematic study has been made about these defects. We believe that once these ultrafine particles are inhaled, the loosely bound electrons are released on interaction with the lung tissue and trigger a chain of biological events resulting in damage, which is not well understood at present. Nanomaterials like carbon nanotubes and titanium dioxide are playing ever increasing role in modern technology. They find application in electronics, drug delivery, cosmetics, sunscreens, catalysts, solar cells, energy storage devices and as composites (e.g. carbon nanotubes in Boeing 787 jet). The problem of health hazard posed by respiration of nanomaterials by mild thermal treatment in ambient of electron accepting (oxidizing) or electron donating (reducing) vapors is addressed to find out which of the treatments is likely to pacify (deactivate) the defect centers.
Why are nano- and meso-sized particulates of different origin including auto- and industrial emissions and of the widely used materials in nanotechnology like Carbon Nanotubes, TiO2, ZnO, MgO, and SiO2 toxic to inhalation? Proposed Model: Electronically active surface defects release shallow trapped electrons or holes on interaction with biomolecules in the lung tissues which are primarily responsible for toxicity. Once the model is put on a firm footing by experimentation several technologies of great societal benefit follow logically. We propose to conduct the following experiments with a couple of systems to check the veracity of the proposed model. For example, ultrafine powder of âlpha phthalocyanine would be divided in three portions. One portion will serve as reference. One of the other would be thermally treated in an ambient of ethanol vapors, which is known from our previous work to be an electron donor (A. Nath, "Studies of Isotopic Exchange in Solid State Healing of Damaged Molecules" Accounts of Chemical Research 17, 90, 1984). The third specimen would be subjected to mild thermal treatment in oxygen ambient. The chemisorbed O2 would grab electrons and make the material hole conducting. The three samples of phthalocyanine would be checked for toxicity by our toxicologist collaborator. Whether the toxicity is enhanced or reduced by the treatments would shed light on the electronic nature of defect centers. Similar experiments with TiO2 and carbon nanotubes would be in order. |
| 资源类型: | 项目
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| 标识符: | http://119.78.100.158/handle/2HF3EXSE/93681
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| Appears in Collections: | 影响、适应和脆弱性
气候减缓与适应
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| Recommended Citation: | |
Amar Nath. EAGER: External Injection of Electrons and Holes in As- Manufactured Nanomaterials to Understand Environmental Hazards. 2014-01-01.
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