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1.
The feasibility of using bis(delta2-2-imidazolinyl)-5,5'-dioxime (H2L) for the selective extraction of iron(III) from aqueous solutions was investigated by employing an solvent-extraction technique. The extraction of iron(III) from an aqueous nitrate solution in the presence of metal ions, such as cobalt(II), copper(II) and nickel(II), was carried out using H2L in binary and multicomponent mixtures. Iron(III) extraction has been studied as a function of the pH, equilibrium time and extractant concentration. From the extracted complex species in the organic phase, iron(III) was stripped with 2 M HNO3, and later determined using atomic-absorption spectrometry. The extraction was found to significantly depend on the aqueous solution pH. The extraction of iron(III) with H2L increases with the pH value, reaching a maximum in the zone of pH 2.0, remaining constant between 2 and 3.5 and subsequently decreasing. The quantitative extraction of iron(III) with 5 x 10(-30 M H2L in toluene is observed at pH 2.0. H2L was found to react with iron(III) to form ligand complex having a composition of 1:2 (Fe:H2L).  相似文献   
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It has long been known that thiol-terminated molecules self-assemble as commensurate monolayers on Au(111) surfaces. By spreading floating octadecanethiol monolayers on aqueous solutions of chloroauric acid (HAuCl4) and using x rays to reduce the gold ions as well as to probe the structure, we have observed the nucleation of (111)-oriented Au nanoparticles at thiol surfaces. This process may be similar to the formation of biogenic gold by bacteria. The thiol monolayer acts as a "soft template," changing its structure as Au crystals form so that there is a sqrt[3]×sqrt[3] commensurate relationship.  相似文献   
4.
The waiting time distribution between successive events and the unified scaling law is studied using the coherent noise model. It is shown that, although this model generates uncorrelated event sizes and does not exhibit criticality, it still provides the unified scaling law. We argue the role of characteristic kink observed in the unified scaling law and the meaning of the parameter CC used to fix the peak of the kink to unity. Our results indicate that the parameter CC is indeed a physical quantity localizing the end of the linear tendency in the scaling law, which corresponds to the completion of the dominance of correlated events in time.  相似文献   
5.
We have presented non-linear analytical formula for fusion–fission cross-sections. This is achieved by analysing many fusion–fission experiments of the compound nuclei of atomic number range \(23 \le Z \le 146\) available in literature. Our parametrised formula can reproduce the fusion–fission cross-sections which agree well with the experiments. Our parametrisations depend on the charges and masses of the compound nuclei and fission fragments only. These results can be used as a guideline for estimating the fusion–fission cross-sections in those cases where measurements do not exist and also for studying new nuclei which are not yet explored.  相似文献   
6.
We report on ZF and TF‐studies of PrCu2 above the induced Jahn–Teller transition at 7.3 K. Generally a two‐component signal is found, one showing inhomogeneous the other one homogeneous, temperature dependent line broadening. In ZF the former component is well represented by a Gaussian Kubo–Toyabe function with \varDelta \simeq 6.5\,μs-1 at 7.5 K, corresponding to a field width of 76 G. This is about 30 times larger than what is calculated to arise from the 141Pr‐nuclear dipole moments alone, pointing to strong hyperfine enhanced features. TF‐field scans at 12 K revealed that the enhancement is suppressed in external fields exceeding 1 kG. In parallel the Knight shift drops from very large values well above 10% at 100 G to shifts of the order of 1% above 1 kG. A scaling of the Knight shifts with the corresponding relaxation rates seems to imply that the strange field dependence below 1 kG is associated with the magnetic susceptibility of the muons’s nearest neighbour Pr3+‐ions, a result for which we have no explanation yet to offer. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   
7.
The antiferromagnetic Blume–Emery–Griffiths model in an external magnetic field is studied by using the exact recursion relations on the Bethe lattice for arbitrary values of biquadratic and for negative values of bilinear interactions. We have studied the thermal variations of two-sublattice magnetizations belonging to spin-1 BEG model to obtain the phase diagrams on the (H/|J|,kT/|J|)(H/|J|,kT/|J|) plane. As a result, we have found that the system presents second- and first-order phase transitions, therefore, tricritical points for appropriate values of K/|J|K/|J|, D/|J|D/|J| and q  . We have also found that the second-order phase transition lines exhibit reentrant phenomena in temperature, besides it also shows reentrant phenomena for the first-order phase lines in external magnetic field for q=4q=4 and 6.  相似文献   
8.
The aim of this paper is to obtain the approximate analytical solution of a fractional Zakharov-Kuznetsov equation by using homotopy perturbation method (HPM). The fractional derivatives are described in the Caputo sense. Several examples are given and the results are compared to exact solutions. The results reveal that the method is very effective and simple.  相似文献   
9.
    
Phenoxy- and naphthoxy-substituted bisphenol-bridged cyclic phosphazenes were synthesized in 2 steps and their thermal, photophysical, and electrochemical properties were investigated. The structures of the cyclic phosphazene compounds were determined by ESI-MS mass spectrometry and 1 H, 13 C, and 31 P NMR spectroscopies. The photophysical studies of phenoxy- and naphthoxy-substituted bridged cyclophosphazenes were investigated by means of absorption and fluorescence spectroscopies in different solvents. Thermal and electrochemical properties of the target compounds were also studied. Furthermore, the excimer emissions through intramolecular interactions in solution and in solid state were investigated by fluorescence spectroscopy and the theoretical calculations were performed in detail using DFT.  相似文献   
10.
    
This work reports on dyeing of nylon/elastane fabric with water-soluble phthalocyanines ( 1-4 ) bearing quinoline 5-sulfonic acid substituents on the peripheral or nonperipheral positions and determining the antibacterial efficiency of the phthalocyanine compounds and the dyed nylon/elastane fabrics. The light, washing, water, perspiration, and rubbing fastness properties of nylon/elastane fabrics dyed with phthalocyanines were also determined. The results showed that all dyed fabrics showed very good wet fastness values. The lightfastness value of the nylon/elastane fabric dyed with phthalocyanine dye ( 1 ) showed a much better value than the others. Also, the antibacterial efficiencies of the dyed nylon fabrics and the dye compounds were investigated against a gram-negative ( Escherichia coli ) and a grampositive ( Staphylococcus aureus ) bacteria by using disc diffusion method. The results showed that the dyed nylon/elastane fabrics and the compounds exhibited antibacterial activities against both bacteria.  相似文献   
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