摘要 :
A much studied oil-soluble surfactant, bis[2-ethylhexyljsulfosuccinate, sodium salt, was ion exchanged into the silver ion form and dissolved into microemulsionsof immiscible polyurethane step monomers. Coating andcuring of these ...
展开
A much studied oil-soluble surfactant, bis[2-ethylhexyljsulfosuccinate, sodium salt, was ion exchanged into the silver ion form and dissolved into microemulsionsof immiscible polyurethane step monomers. Coating andcuring of these microemulsions produced polyurethanecoatings that exhibit bactericidal activity against representative Gram negative bacteria. After 24 h exposure, 0.006-0.012% weight Ag relative to coating weight (0.0013-0.0025 mu mol Ag/cm~2) results in the three-log reduction in Escherichia coli. A slightly higher level of 0.031% weightAg relative to coating weight (0.006 mu mol Ag/cm~2) killedall of the E. coli after 12 h exposure. Similar results wereobtained for Pseudomonas aeruginosa. Since the doubletail surfactant anion promotes reverse micelle formation in many different kinds of oils and solvents, it appears anexcellent vector for incorporating low and effectiveamounts of silver ion into many industrial, hospital, andhousehold coating formulations.
收起
摘要 :
Accompanying increased commercial applications and production of silver nanomaterials is an increased probability of human exposure, with inhalation a key route. Nanomaterials that deposit in the pulmonary alveolar region followin...
展开
Accompanying increased commercial applications and production of silver nanomaterials is an increased probability of human exposure, with inhalation a key route. Nanomaterials that deposit in the pulmonary alveolar region following inhalation will interact firstly with pulmonary surfactant before they interact with the alveolar epithelium. It is therefore critical to understand the effects of human pulmonary surfactant when evaluating the inhalation toxicity of silver nanoparticles. In this study, we evaluated the toxicity of AgNPs on human alveolar type-I-like epithelial (TT1) cells in the absence and presence of Curosurf (a natural pulmonary surfactant substitute), hypothesising that the pulmonary surfactant would act to modify toxicity. We demonstrated that 20 nm citrate-capped AgNPs induce toxicity in human alveolar type I-like epithelial cells and, in agreement with our hypothesis, that pulmonary surfactant acts to mitigate this toxicity, possibly through reducing AgNP dissolution into cytotoxic Ag+ ions. For example, IL-6 and IL-8 release by TT1 cells significantly increased 10.7- and 35-fold, respectively (P < 0.01), 24h after treatment with 25 mu g/ml AgNPs. In contrast, following pre-incubation of AgNPs with Curosurf (R), this effect was almost completely abolished. We further determined that the mechanism of this toxicity is likely associated with Ag+ ion release and lysosomal disruption, but not with increased reactive oxygen species generation. This study provides a critical understanding of the toxicity of AgNPs in target human alveolar type-I-like epithelial cells and the role of pulmonary surfactant in mitigating this toxicity. The observations reported have important implications for the manufacture and application of AgNPs, in particular for applications involving use of aerosolised AgNPs. (C) 2016 Elsevier B.V. All rights reserved.
收起
摘要 :
Polymer electrolytes containing silver salts have gained great interest due to their effective performance in the separation of olefin/paraffin mixtures. However, they suffer from the poor long-term stability. The membrane perform...
展开
Polymer electrolytes containing silver salts have gained great interest due to their effective performance in the separation of olefin/paraffin mixtures. However, they suffer from the poor long-term stability. The membrane performance of polyvinylpyrrolidone (PVP)/AgBF_4 membranes was decreased with time primarily due to the reduction of silver ions to silver metal. In this study, non-ionic n-octyl β-D-glucopyranoside (8G1) surfactant has been employed to prolong the stability of the separation performance of PVP/AgBF_4 membranes. It was found that the growth rate of the silver particles became slower and the propylene permeability was maintained for much longer time when 8G1 was added into the membranes. The reduction behavior of silver ions to silver metal particles and their growth were investigated by Transmission electron microscopy (TEM), scanning electron microscope (SEM), and UV spectroscopy.
收起
摘要 :
Gold and silver nanoparticles anchored on surfactant intercalated montmorillonite were prepared by two methodologies. In the first case, gold and silver nanoparticles were synthesized by reduction of gold and silver salt in hexade...
展开
Gold and silver nanoparticles anchored on surfactant intercalated montmorillonite were prepared by two methodologies. In the first case, gold and silver nanoparticles were synthesized by reduction of gold and silver salt in hexadecyltrimethylammonium bromide (HDTA) and dioctadecyldimethylammonium chloride (DODA), followed by exchange of HDTA and DODA solution containing gold and silver nanoparticles into montmorillonite (MMT). In second case, HDTA and DODA with gold and silver salt was exchanged with MMT, and then reduced to obtain gold and silver nanoparticles. The particle size of gold and silver varies with the path of reduction as well as type of surfactant used for the modification of MMT. Gold and silver nanoparticles synthesized using quaternary ammonium salt with two long alkyl chain resulted into finer particles than a single long alkyl chain. The present study demonstrates the effect of reduction path, type of surfactants, and concentration of gold and silver on the particle size of gold and silver nanoparticles anchored on organoclay. Gold and silver nanoparticles supported organoclay were characterized by High resolution transmission electron microscopy (HRTEM), powdered X-ray diffraction (PXRD) and Inductive coupled plasma-atomic emission spectroscopy (ICP-AES).
收起
摘要 :
The loading of noble-metal nanoparticles (NMNPs) onto various carriers to obtain stable and highly efficient catalysts is currently an important strategy in the development of noble metal (NM)-based catalytic reactions and their a...
展开
The loading of noble-metal nanoparticles (NMNPs) onto various carriers to obtain stable and highly efficient catalysts is currently an important strategy in the development of noble metal (NM)-based catalytic reactions and their applications. We herein report a nanowire supramolecular assembly constructed from the surfactant-encapsulating polyoxometalates (SEPs) CTAB-PW12, which can act as new carriers for NMNPs. In this case, the Ag NPs are loaded onto the SEP nanowire assembly with a narrow size distribution from 5 to 20nm in diameter; the average size is approximately 10nm. The Ag NPs on the nanowire assemblies are well stabilized and the over agglomeration of Ag NPs is avoided owing to the existence of well-arranged polyoxometalate (POM) units in the SEP assembly and the hydrophobic surfactant on the surface of the nanowire assembly. Furthermore, the loading amount of the Ag NPs can be adjusted by controlling the concentration of the AgNO3 aqueous solution. The resultant Ag/CTAB-PW12 composite materials exhibit high activity and good stability for the catalytic reduction of 4-nitrophenol (4-NP) with NaBH4 in isopropanol/H2O solution. The NMNPs-loaded SEP nanoassembly may represent a new composite catalyst system for application in NM-based catalysis.
收起
摘要 :
A general and facile surfactant-assisted solvothermal route was developed for the synthesis of CoTe, Ag2Te/Ag, and CdTe nanostructures using the corresponding metal salt, Na2TeO3, ascorbic acid, and polyvinyl pyrrolidone (PVP) or ...
展开
A general and facile surfactant-assisted solvothermal route was developed for the synthesis of CoTe, Ag2Te/Ag, and CdTe nanostructures using the corresponding metal salt, Na2TeO3, ascorbic acid, and polyvinyl pyrrolidone (PVP) or cetyltrimethylammonium bromide (CTAB) in mixed solvents of ethanolamine and water. It was also found that the morphology of the product varied dramatically when using different surfactants such as PVP and CTAB. A formation mechanism of telluride nanostructures was proposed. The products were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), thermogravimetry (TG), and differential scanning calorimetric (DSC) analysis.
收起
摘要 :
Silver nanowires with a diameter of 30 nm and typical lengths of 5-10μm have been synthesized in an aqueous medium. To initiate the reaction, citrate ions were used, and during the reaction the aromatic organic molecules polymeri...
展开
Silver nanowires with a diameter of 30 nm and typical lengths of 5-10μm have been synthesized in an aqueous medium. To initiate the reaction, citrate ions were used, and during the reaction the aromatic organic molecules polymerize forming "straight" chain surfactants which support the formation of nanowires. Characterization by TEM and HRETM revealed the nanowires to be highly crystalline with a growth along the [110] direction.
收起
摘要 :
Convection heat transfer and pressure drop characteristics of water based silver nanowire suspensions flowing through CMOS compatible monolithic microchannel heat sinks are investigated experimentally. Three different rectangular ...
展开
Convection heat transfer and pressure drop characteristics of water based silver nanowire suspensions flowing through CMOS compatible monolithic microchannel heat sinks are investigated experimentally. Three different rectangular channels of 200 mu m x 50 mu m, 100 mu m x 50 mu m and 70 mu m x 50 mu m cross sectional area are used during the experiments. The stability of the silver nanofluids is established by the added polyvinylpyrrolidone (PVP) as the surfactant. To investigate the potential heat transfer enhancement by the silver nanofluids, the experiments are performed with deionized (DI) water, PVP-DI water solution, and the silver nanofluid with added PVP. It is observed that the silver nanofluid had higher heat transfer coefficient than both the PVP-DI water solution, and DI water only. Moreover, all fluids have similar hydrodynamic performance. The prepared silver nanofluid sample is a successful example of a stable nanofluid that has very little surfactant such that the existence of the surfactant does not cause a decrease in the heat transfer coefficient, while maintaining the stability. Upto 56% enhancement in the heat transfer coefficient is reached with practically no increase in the pumping power. The study is the first in using silver nanowire suspensions for heat transfer enhancement. (C) 2017 Elsevier Masson SAS. All rights reserved.
收起
摘要 :
The present study is focused on the synthesis and investigation of the physicochemical and biological properties of silver nanoparticles stabilized with a series of cationic gemini surfactants having a polymethylene spacer of vari...
展开
The present study is focused on the synthesis and investigation of the physicochemical and biological properties of silver nanoparticles stabilized with a series of cationic gemini surfactants having a polymethylene spacer of variable length. UV-VIS spectroscopy, dynamic light scattering, scanning electron microscopy and zeta potential measurements were applied to provide physicochemical characterization of the silver nanoparticles. The mean size values of the nanoparticles were found to be in the 50 to 115 nm range. From the nanoparticle size distributions and scanning electron microscopy images it results that a population of small nanoparticles with the size of several nanometers was confirmed if the nanoparticles were stabilized with gemini molecules with either a short methylene spacer (two or four-CH2-groups) or a long spacer (12-CH2-groups). The average zeta potential value for silver nanoparticles stabilized with gemini molecules is roughly independent of gemini surfactant spacer length and is approx. +58 mV. An interaction model between silver nanoparticles and gemini molecules which reflects the gained experimental data, is suggested. Microbicidal activity determinations revealed that the silver nanoparticles stabilized with gemini surfactants are more efficient against Gram-negative bacteria and yeasts, which has a direct relation to the interaction mechanism of nanoparticles with the bacterial cell membrane and its structural composition.
收起
摘要 :
In this investigation, a facial sonochemical route has been developed for the preparation of AgSCN micro/ nanostructures by using AgNO3 and KSCN. Different morphologies of AgSCN were obtained in ethanol, dimethyl sulfoxide, cycloh...
展开
In this investigation, a facial sonochemical route has been developed for the preparation of AgSCN micro/ nanostructures by using AgNO3 and KSCN. Different morphologies of AgSCN were obtained in ethanol, dimethyl sulfoxide, cyclohexanol, N,N-dimethylformamide, ethylene glycol and polyethylene glycol as solvent after sonication for 30 min. Besides, the effect of sodium dodecyl sulfate, polyethylene oxide, and polyvinylpyrrolidone as surfactant on the morphology and particle size of the products was investigated. The AgSCN micro/nanostructures were characterized using SEM, TEM, XRD, FT-IR, and PL.
收起
原文获取