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排序方式: 共有659条查询结果,搜索用时 31 毫秒
281.
The studies on the human toxicity of nanoparticles (NPs) are far behind the rapid development of engineered functionalized NPs. Fullerene has been widely used as drug carrier skeleton due to its reported low risk. However, different from other kinds of NPs, fullerene-based NPs (C60 NPs) have been found to have an anticoagulation effect, although the potential target is still unknown. In the study, both experimental and computational methods were adopted to gain mechanistic insight into the modulation of thrombin activity by nine kinds of C60 NPs with diverse surface chemistry properties. In vitro enzyme activity assays showed that all tested surface-modified C60 NPs exhibited thrombin inhibition ability. Kinetic studies coupled with competitive testing using 3 known inhibitors indicated that six of the C60 NPs, of greater hydrophobicity and hydrogen bond (HB) donor acidity or acceptor basicity, acted as competitive inhibitors of thrombin by directly interacting with the active site of thrombin. A simple quantitative nanostructure-activity relationship model relating the surface substituent properties to the inhibition potential was then established for the six competitive inhibitors. Molecular docking analysis revealed that the intermolecular HB interactions were important for the specific binding of C60 NPs to the active site canyon, while the additional stability provided by the surface groups through van der Waals interaction also play a key role in the thrombin binding affinity of the NPs. Our results suggest that thrombin is a possible target of the surface-functionalized C60 NPs relevant to their anticoagulation effect. 相似文献
282.
Fei Wang Jiangtao He Baonan He Xiaojing Zhu Xiaocui Qiao Liuyue Peng 《环境科学学报(英文版)》2018,30(7):251-260
To explore the formation process and mechanism of organic matter and organic-mineral complex under humification and mineralization conditions, a series of samples including humic acid, kaolin, and humic acid-kaolin complex were prepared using a subcritical water treatment method(SWT) under specific temperature, pressure and reaction time conditions. HA was used as a surrogate for natural organic matter because it has a similar abundant pore structure,variety of carbon types, and chemical components. These samples were used in carbamazepine(CBZ) sorption experiments and characterized by a variety of techniques. The polymerization of humic acid under the conditions of increased temperature and pressure resulted in an increase in specific surface area and molecular quantity. In addition, the degree of aromaticity rose from59.52% to 70.90%. These changes were consistent with the transformation from ‘soft carbon' to‘hard carbon' that occurs in nature. The results of sorption experiments confirmed the interaction between humic acid and kaolin from the difference between the predicted and actual Qevalues. The conceptual model of humic acid-kaolin complex could be deduced and described as follows. Firstly, the aromatic components of humic acid preferentially combine with kaolin through the intercalation effect, which protects them from the treatment effects.Next, the free carboxyl groups and small aliphatic components of humic acid interact on the surface of kaolin, and these soft species transform into dense carbon through cyclization and polymerization. As a result, humic acid-kaolin complex with a mineral core and dense outer carbonaceous patches were formed. 相似文献
283.
Use of a multi-layer column device for study on leachability of nitrate in sludge-amended soils 总被引:5,自引:0,他引:5
This paper described a multi-layer column device constructed with six cylindrical polythene tubes with installation of Rhizon soil moisture samplers (Rhizon SMS). The feasibility of using the column device to collect soil solution and percolate and to monitor leachability of nitrate in two sludge-amended soils was evaluated under glasshouse conditions. The soil moisture sampler in the device was demonstrated to be a non-destructive, simultaneous, sequential, convenient and rapid sampling tool for multiple-site porewater extraction. The device provided an in situ monitoring technique for leachability of nitrate in a soil profile following application of the anaerobically digested sewage sludge. The monitored results showed that surface soil amendment of the sewage sludge increased markedly the concentration of nitrate in the soil solutions at depths of 10-30 cm in a neutral paddy soil and at 30-50 cm in an acid red paddy soil. This amendment also largely increased nitrate in the percolates of the acid red soil. The movement and distribution patterns of nitrate in the profile were related to soil types, profile depths and experimental periods. Land application of sewage sludge may pose a risk in groundwater contamination of nitrate. 相似文献
284.
The photocatalytic degradation of gaseous trichloroethylene (TCE) without water has been studied. The degradation products were determined to be CO2, HCl and Cl2, and the reaction stoichiometry, was described as . The degradation rate was found to be linear with 0.16 power of the illumination intensity. When the TCE concentration was low (1014 mol L−1 or a little more), its degradation rate model could be considered as first order kinetics. A mechanism of valence band hole oxidation was proposed. 相似文献
285.
286.
287.
Qiao Bing 《环境科学学报(英文版)》2001,13(2):252-256
The paper introduces systematically the developing principle of CWCM 1.0 oil spill model based on Lagrange system and oil spill fate processes in environment, reviews two oil spill incidents of "East Ambassador" in Jiaozhou Bay and "Min Fuel 2" in the mouth of Pearl River, and designs the predictable system simulating oil spill applied in contingency plans. It is indicated that CWCM 1.0 has met preliminarily the demands for functions of precision simulating and predicting oil spill, and can plan an important role to support oil spill response. 相似文献
288.
在当前水资源浪费、用水效率较低的背景下,仍然有许多地区继续实行低水价政策,本文认为这是供水企业与用水企业以及政府水务部门相互博弈的结果。通过构建一个供水企业与用水企业的博弈模型,并采用演化博弈分析方法分析动态演化的结果,本文发现当前采用低水价的主要原因在于:供水企业制定水价时要同时考虑私人收益与公共节水收益,而高水价对经济产生的冲击成本不足以弥补高水价产生的公共节水收益与私人收益,从而导致有些地区供水企业不敢提高水价,一直采用低水价策略。进一步地,本文采用不完全信息动态博弈方法分析供水企业与政府关于水价的议定过程,发现提高水价对经济的冲击越大,且节水技术投入成本越大而节水的公共收益越小时,政府水务部门同意低水价的概率越大;反之,则同意高水价的概率越大。从博弈论的角度系统地分析了低水价产生的决策过程,可对提高水价、促进节约用水具有一定的指导意义。 相似文献
289.
从银铅锌废渣中回收硝酸银的研究 总被引:1,自引:0,他引:1
介绍了用灼烧、浸取、沉淀、溶转和离子交换等方法,从银铅锌废渣中直接回收硝酸银,收率可达80.12%,AgNO3纯度为99.9%。考察了试料粒度、FeCl3质量浓度、溶液酸度、固液比,反应温度及浸取时间对银浸出率的影响。 相似文献
290.
This article reports a novel way to synthesize carbon nanotubes and Cu/ZnO nanoparticles using metal hyperaccumulator plants.
Metal hyperaccumulator plants are traditionally used for phytoremediation to clean soil polluted by toxic metals. However,
the transfer of toxic metals in plant shoots and leaves is an environmental issue because animals and other living organisms
feeding on plants will transfer the metals to the ecosystem. Therefore, we suggest that hyperaccumulator plants could be used
to synthesize nanoparticles. Here, Brassica juncea L., a Cu-hyperaccumulator plant, was collected around a copper mine and used as a raw chemical to produce carbon nanotubes
and Cu/ZnO nanoparticles. The chlorophyll in shoots of B. juncea plants was ethanol extracted to yield chlorophyllin. Cu and Zn were extracted by HNO3 to form Cu/Zn(NO3)2. The chlorophyllin reacted with Cu/Zn(NO3)2 to form Cu/Zn chlorophyllin. Cu/ZnO nanoparticles were synthesized by direct precipitation of Cu/Zn chlorophyllin with NaOH
and ethanol. The vascular bundles in B. juncea plants, which have been purified and carbonized by HNO3, were rapidly heated to about 400°C and then they were cooled to room temperature to obtain carbon nanotubes. Results indicate
that the outer diameter of carbon nanotubes was around 80 nm. Cu/ZnO nanoparticles have a Cu0.05Zn0.95O composition, and had a diameter of about 97 nm. Our study not only inspires the search for a new strategy on the synthesis
of nanostructure from renewable natural products, but also breaks through the traditional and limited ideas about the reuse
of metals by hyperaccumulator plants. 相似文献