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1.
Pure metallic Cu nanoparticles at a high concentration (up to 0.2 M) have been synthesized by the reduction of cupric chloride with hydrazine in the aqueous CTAB solution. The input of extra inert gases was not necessary. The use of ammonia solution for the adjustment of solution pH up to 10 and the use of hydrazine as a reducing agent in a capped reaction bottle are crucial for the synthesis of pure Cu nanoparticles. The reaction solution finally became wine-reddish and its UV/vis absorption spectrum exhibited an absorption band at 574 nm, revealing the formation of metallic Cu nanoparticles. By the analysis of electron diffraction pattern, EDS, XRD, and XPS, the resultant particles were confirmed to be pure Cu with a face-centered cubic (fcc) structure. From the TEM analysis, it was found that the mean diameter of Cu nanoparticles first decreased and then approached a constant with the increase of hydrazine concentration. In addition, the CTAB concentration had not significant influence on the size of Cu nanoparticles. Also, TG analysis indicated that there were two weight-loss steps for the CTAB-capped Cu nanoparticles. It was suggested that a bilayer structure of CTAB was formed on the surface of Cu nanoparticles to prevent from the particle agglomeration. The synthesis method reported in this work might be helpful for the large-scale production of Cu nanoparticles. 相似文献
2.
Adsorption of CTAB onto perlite samples from aqueous solutions 总被引:2,自引:0,他引:2
In this study, the adsorption properties of unexpanded and expanded perlite samples in aqueous cetyltrimethylammonium bromide (CTAB) solutions were investigated as a function of ionic strength, pH, and temperature. It was found that the amount of cetyltrimethylammonium bromide adsorbed onto unexpanded perlite was greater than that onto expanded perlite. For both perlite samples, the sorption capacity increased with increasing ionic strength and pH and decreasing temperature. Experimental data were analyzed by Langmuir and Freundlich isotherms and it was found that the experimental data were correlated reasonably well by the Freundlich adsorption isotherm. Furthermore, the isotherm parameters (KF and n) were also calculated. The adsorption enthalpy was determined from experimental data at different temperatures. Results have shown that the interaction between the perlite surface and CTAB is a physical interaction, and the adsorption process is an exothermic one. 相似文献
3.
In this experimental work we carefully investigate the influence of some organic counterions (having similarities): sodium
salicylate (NaSal), sodium tosylate (NaTos) and sodium benzoate (NaBz) on the rheological properties of two aqueous solutions
(0.1 and 0.05 M) of cetyltrimethylammonium bromide (CTAB). Here we are particularly interested in the occurrence of the shear
thickening effect corresponding to shear induced structures (SIS). All the rheological measurements presented in this work
are realized with the same geometrical device (plan-cone) with controlled imposed shear stress. Conditions of occurrence and
evolutions of the characteristics of the obtained shear thickening are given.
Received: 30 June 1997 Accepted: 20 October 1997 相似文献
4.
Low-temperature electron microscopy was used to image fracture faces of shock-frozen aqueous solutions containing the very large micelles of CTAB existing in the presence of N-methyl-N,N-diphenylamine (MDPA) and 9-anthracene carboxylic acid (9-AC) as solubilizates. When MDPA is present, large globular micelles are formed which have total aggregation numbers of the order of 105 and are seen to be clusters of smaller disc-like structures containing some thousand CTAB-units. Thread-like features are visualized in solutions containing 9-AC which is known to induce the formation of micellar rods. 相似文献
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A strategy to obtain photochromism from the network of chemical reactions originated by flavylium compounds in solution is described. This strategy is particularly useful for flavylium salts bearing amino groups which give rise to a variety of beautiful colors but lack photochemistry in water. The trans-chalcone of 7-(N,N-diethylamino)-4'-hydroxyflavylium interacts strongly with CTAB micelles defining a yellow dark state. Upon irradiation, the system switches to a pink-red state emerging from the flavylium cation that is formed inside the micelle and ejected to the bulk aqueous phase. The photochemical product reverts back to the trans-chalcone adduct with the micelle in the dark. The thermodynamics as well as the kinetics of the photochromic system were studied in detail. The best color contrast is obtained at pH = 4.25 with Phi = 0.001 and a recovery lifetime of approximately 3 h. This photochromic system works with no need of changing the pH, which constitutes an important improvement over previously described systems dependent on pH jumps. 相似文献
8.
A. B. Darintseva I. B. Murashova N. V. Matrenina 《Russian Journal of Electrochemistry》2008,44(6):755-760
Experimental data on the contact displacement of metals from aqueous solutions are shown. Experimental chronopotentiograms are compared with those calculated based on an earlier proposed model. 相似文献
9.
H. Bubert P. Burba R. Klockenkämper A. Schönborn M. Wielunski 《Fresenius' Journal of Analytical Chemistry》1991,341(3-4):245-247
Summary The dose of nickel ions implanted with an energy of 300 keV or 6 MeV, respectively, into silicon wafers was measured by X-ray fluorescence analysis (XRFA) after the implantation process. Dose values for Ni were determined within the range from 5×1015 to 1×1018 ions/cm2. The detection limit of this simple and non-destructive procedure amounts to about 1014 atoms/cm2. The accuracy was confirmed by flame atomic absorption spectrometry (FAAS), total-reflection X-ray fluorescence analysis (TXRFA), and by Rutherford-backscattering spectroscopy (RBS). The study confirms XRFA to be a suitable method for dose determinations after the implantation process. 相似文献
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I. L. Baranov L. B. Tabulina L. V. Stanovaya T. G. Rusal’skaya 《Russian Journal of Applied Chemistry》2010,83(6):978-983
Bulk chemical etching of single-crystal semiconducting silicon in aqueous alkaline solutions of KOH was studied at various
solution temperatures, alkaline component concentrations, and microscopic amounts of a potassium ferricyanide additive. Specific
effects of these factors on the process of silicon etching are explained by comparing the corresponding activation energies.
The possibility of using alkaline aqueous solutions of KOH with a potassium ferricyanide additive for fabrication of elements
in microsystem technology devices is assessed. 相似文献
13.
Kunieda H Rodriguez C Tanaka Y Kabir MH Ishitobi M 《Colloids and surfaces. B, Biointerfaces》2004,38(3-4):127-130
The effect of adding tri(oxyethylene) dodecyl ether (C12EO3) on the phase and rheological behavior of sucrose hexadecanoate and CTAB aqueous solutions in the presence of added salt (NaBr) was investigated. Viscoelastic solutions are formed in CTAB and C16SE systems upon addition of lipophilic nonionic surfactant C12EO3. The zero-shear viscosity shows a maximum at a certain mixing fraction of C12EO3, except in the case of the aqueous CTAB/C12EO3 system in the absence of salt. The rheological properties are strongly affected by the addition of salt to the CTAB systems but they remain unaltered in the case of C16SE systems. In ionic systems, the mixing fraction of C12EO3 for the maximum viscosity depends on salt concentration. 相似文献
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N. B. Kim H. W. Choi S. K. Chun S. Y. Cho H. J. Woo K. S. Park 《Journal of Radioanalytical and Nuclear Chemistry》2001,248(1):125-128
For the instrumental neutron activation analysis of trace impurities in high purity silicon wafer, a modified single comparator method has been applied. The energy distribution of the neutrons at the irradiation position was measured using the two flux monitors, Au and Co, and elemental contents were calculated using the silicon matrix in the wafer as a comparator. This has advantage of reducing the cross contamination from an external monitor during sample preparation and irradiation, the uncertainties from the non-homogeneity of the neutron flux and the error on the weight of comparators. Determination limits for 49 elements were presented under the condition of 72 hours irradiation at a neutron flux of 3.7·1013 n·cm-2·s-1 and 4000 s measurement. The analytical results obtained by this method and the conventional single comparator method were compared and were found to agree well within 5%. 相似文献
16.
T. Nozaki M. Iwamoto K. Usami K. Mukai A. Hiraiwa 《Journal of Radioanalytical and Nuclear Chemistry》1979,52(2):449-459
Oxygen in silicon nitride films on silicon wafers was analyzed by activation with the16O(3He, p)18F reaction. By3He bombardment of samples propertly arranged under consideration of the18F recoil effect, total oxygen was reliably determined and its predominant part was estimated to be located whether on film
surface, in film interior, or on film-substrate interface. Sample films with 0.1 to 2 μm thicknesses were found to contain
0.2 to 2 μg/cm2 of oxygen in locations varying with preparation conditions. This method has been compared with ESCA and other methods for
surface analysis. 相似文献
17.
Inoue T Inoue Y Watanabe H 《Langmuir : the ACS journal of surfaces and colloids》2005,21(4):1201-1208
The nonlinear rheology of aqueous solutions of cetyltrimethylammonium bromide (CTAB) and sodium salicylate (NaSal) was investigated. The concentration of CTAB was fixed at 0.1 mol L(-1), and the concentration of NaSal was varied from 0.07 to 0.4 mol L(-1). For all test solutions, dynamic moduli were described with the Maxwell model having a single relaxation time, tau. Time evolutions of the shear stress, sigma, and the first normal stress difference, N(1), after inception of the steady shear flow were measured. For solutions having low NaSal concentrations, strain-hardening was observed and sigma and N(1) diverged at a certain strain when the shear rate, , exceeded tau(-1). For solutions with high NaSal concentrations, stress overshoot similar to that of ordinary entangled polymer solutions was observed at between tau(-1) and a certain critical rate, (C), while the strain-hardening was observed at > (C). A simple relationship for elastic solids, N(1)/sigma = gamma with gamma being the strain imposed by shear flow, held for all the solutions in the strain-hardening regime. The strain-hardening was attributable to the strain-dependent shear modulus and well described with the network theory considering the finite extensibility of network strands. The segment size of network strands was successfully determined. Thus, the stress-strain relationship obtained after the inception of fast flows is useful for characterizing the network properties. 相似文献
18.
M. L. Verheijke H. J. J. Jaspers J. M. G. Hanssen 《Journal of Radioanalytical and Nuclear Chemistry》1989,131(1):197-214
Procedure and results of instrumental neutron activation analysis of very pure silicon wafers of 12.5 and 15 cm diameter are described. It is shown that the determined contaminations are mainly present on the surface or in a surface layer of the wafers. With the method outlined here very low limits of detection for a large number of elements are obtained. The analyses also confirmed that two routine process cleaning procedures do not contaminate the surface of the waters. 相似文献
19.
N. V. Nikolenko A. A. Pivovarov R. I. Zakharov A. N. Kalashnikova 《High Energy Chemistry》2013,47(5):262-267
Changes in the composition of aqueous NaCl solutions during the course of their treatment with glow-discharge plasma in a gas-liquid plasma-chemical reactor have been studied. A mathematical model involving the steps of oxidation of water molecules and chloride ions and the steps of reduction of their chemical conversion products has been developed. For the first time, it has been found that the hydrogen peroxide content of the solution monotonically decreases with the concentration of NaCl and a change in chlorite, chlorate, and perchlorate concentrations has the appearance of an undulating curve with a maximum at c(NaCl) = 3 g/L. The predominant accumulation of hypochlorite ions in the solution has been detected only in the case of the plasma treatment of the NaCl solutions with concentrations higher than 5 g/L. 相似文献
20.
It was found that a commercial silicon photodiode modified only by removing its window can be used as a low-background detector of -rays from45Ca solutions. We built a test system which could count -rays from 0.21% hot CaCl2 solutions in the concentration range of 10–5–10–8M with linear sensitivity. Such a system using a small photodiode for real-time detection of -rays from small amounts of assay solutions could have many applications in the field of biophysics, biochemistry and physiology, e.g., in the study of Ca-binding proteins. This photodiode was also found to be suitable for measurement of low-energy -rays from14C. 相似文献