分类： 核科学技术 >> 辐射物理与技术 提交时间： 2024-05-11
摘要： Carbon-based nanomaterials have important research significance in various disciplines, such as compositematerials, nanoelectronic devices, biosensors, biological imaging, and drug delivery. Recently, the human andecological risks associated with carbon-based nanomaterials have received increasing attention. However, thebiosafety of carbon-based nanomaterials has not been investigated extensively. In this study, we used differenttypes of carbon materials, namely, graphene oxide (GO), single-walled carbon nanotubes (SWCNTs), and multiwalledcarbon nanotubes (MWCNTs), as models to observe their distribution and oxidative damage in vivo.The results of Histopathological and ultrastructural examinations indicated that the liver and lungs were the mainaccumulation targets of these nanomaterials. SR-μ-XRF analysis revealed that SWCNTs and MWCNTs mightbe present in the brain. This shows that the three types of carbon-based nanomaterials could cross the gas–bloodbarrier and eventually reach the liver tissue. In addition, SWCNTs and MWCNTs could cross the blood–brainbarrier and accumulate in the cerebral cortex. The increase in ROS and MDA levels and the decrease in GSH,SOD, and CAT levels indicated that the three types of nanomaterials might cause oxidative stress in the liver.This suggests that direct instillation of these carbon-based nanomaterials into rats could induce ROS generation.In addition, iron (Fe) contaminants in these nanomaterials were a definite source of free radicals. However,these nanomaterials did not cause obvious damage to the rat brain tissue. The deposition of selenoprotein inthe rat brain was found to be related to oxidative stress and Fe deficiency. This information may support thedevelopment of secure and reasonable applications of the studied carbon-based nanomaterials.
分类： 材料科学 >> 材料科学（综合） 提交时间： 2016-11-04 合作期刊: 《金属学报》
摘要： 利用透射电子显微镜研究了一种低合金钢中马氏体的微结构. 研究发现, 淬火态的马氏体由铁素体基体和弥散于基体中的高密度纳米小颗粒组成, 这种小颗粒的晶体结构可标定为六角结构的?相. ?相与铁素体基体(α-Fe)的取向关系为:[113]α//[2113]ω，(110)α//(1101)ω 和(211)α//(0110)ω, 点阵常数aω =1.414aα, cω =0.866aα. 马氏体中的碳原子呈非均匀分布, 铁素体基体具有很低的碳含量, 合金中的碳原子主要富集在ω相中.
分类： 材料科学 >> 材料科学（综合） 提交时间： 2023-03-31 合作期刊: 《材料研究学报》
摘要： 设计并制备含有长周期堆垛有序结构(LPSO)的Mg94Cu4Y2储氢合金,研究了合金在吸放氢过程中组织的转变机制以及吸放氢动力学性能。结果表明,Mg94Cu4Y2合金主要由Mg、Mg2Cu和高度固溶Cu、Y元素的含18R及14H型的LPSO组成。LPSO在首次吸氢过程中分解,并原位生成均匀的(MgH2+MgCu2+YH3)纳米复合组织。在随后的脱氢和吸放氢循环中,合金主要通过Mg/MgH2反应实现吸放氢。细小均匀分布的Mg2Cu和YH2对Mg/MgH2的催化作用,使该合金表现出较优良的吸放氢动力学特性。
分类： 核科学技术 >> 核材料与工艺技术 提交时间： 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
LAN Tu
DING Cong-Cong
LIAO Jia-Li
LI Xiao-Long
LI Xing-Liang
ZHANG Jie
ZHANG Dong
YANG Ji-Jun
LUO Shun-Zhong
AN Zhu
WU Qi-Qi
YANG Yuan-You
FENG Su
TANG Jun
LIU Ning
摘要： To develop a microbe-based bioremediation strategy for cleaning up thorium-contaminated sites, we have investigated the biosorption behavior and mechanism of thorium on Bacillus sp. dwc-2, one of the dominant species of bacterial groups isolated from soils in Southwest China. Thorium biosorption depended on the pH of environment, and its rapid biosorption reached a maximum of up to 10.75 mg Th per gram of the bacteria (wet wt.) at pH 3.0. The biosorption agreed bettter with Langmuir isotherm model than Freundlich model, indicating that thorium biosorption was a monolayer adsorption. The thermodynamic parameters, negative change in Gibbs free energy and positive value in enthalpy and entropy, suggested that the biosorption was spontaneous, more favorable at higher temperature and endothermic process with an increase of entropy. Scanning electron microscopy (SEM) indicated that thorium initially binded with the cell surface, while transmission electron microscopy (TEM) revealed that Th deposited in the cytoplasm and served as cores for growth of element precipitation (e.g., phosphate minerals) or by self-precipitation of hydroxides, which is probably controlled by ion-exchange, as evidenced by particle induced X-ray emission (PIXE) and enhanced proton backscattering spectrometry (EPBS). Fourier Transform Infrared (FTIR) further indicated that thorium biosorption involved carboxyl and phosphate groups and protein in complexation or electrostatic interaction. Overall results indicated that a combined electrostatic interaction-complexation-ion exchange mechanism could be involved in thorium biosorption by Bacillus sp. dwc-2.
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