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961.
Novel type hydrogel‐clay nanocomposites based on the acrylamide (AAm)‐ 2‐acrylamido‐ 2‐methylpropane sulfonic acid (AMPS) sodium salt and clay were synthesized via in situ copolymerization in aqueous solution. Samples were characterized by determining total basic group (TGB) content and swelling degree, XRD analysis, and FTIR spectroscopy. Effects of monomer ratio and clay amount on the swelling properties of the samples were investigated. It was found that the hydrogel/clay nanocomposites exhibited improved swelling capacity compared with the hydrogels. Samples were used to remove heavy metal ions (Cu (II), Cd (II), and Pb (II)) from aqueous solution in competitive and non‐competitive conditions for the first time. The effects of time and pH of the initial metal ion solution on the adsorption capacity were investigated and selectivity properties of the samples were evaluated. It was found that incorporation of a low amount of clay (10% (wt)) into the polymer structure increased the heavy metal ion adsorption capacity of the sample. It was concluded that the AAm‐AMPS/clay nanocomposites could be used as novel type, fast‐responsive, and high capacity sorbent materials in heavy metal removing processes. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
962.
Cağirgan MI Ozbaş MO Heng LK Afza R 《Isotopes in environmental and health studies》2005,41(3):229-235
Drought tolerance is an important breeding objective in dry and semi-dry conditions. Carbon isotope discrimination (Delta) is a tool that may be used to improve water-use efficiency (WUE) as an indirect selection criterion. The study investigated the variability for Delta in improved F7 lines and their parents (three cultivars and two mutant lines), which were sampled randomly from an F6 nursery performing well under semi-dry conditions. In total, 40 entries were grown in sand culture, arranged in three-replicated randomized complete block designs in two sets of experiments in Antalya, Turkey. There were statistically significant differences (p<0.01) among genotypes in both sets of experiments for Delta, and Delta values range from 20.14 to 21.86. Low coefficient of variation (C.V.) values, i.e. 2 and 1.65 %, for both data sets revealed efficient control of experimental error for Delta and indicated little effect of environment. Consequently, broad-sense heritability estimates for Delta were 0.63 and 0.74. As Delta showed a considerably high heritability and consistency over the two sets of experiments and low C.V. values, it was concluded that this trait could be used in breeding programmes aimed at developing drought tolerance lines. The early heading mutant, M-K-88, and the cultivar selected from land race, Tokak 157-37, showed lowest Delta values, indicating that they had the best water-use efficiency. Low Delta values of these two genotypes were inheritable. 相似文献
963.
Some new (naphthalen-1-yl-selenyl)acetic acids derivatives 7a-d have been synthesized by two different methods, using naphthylselenols or naphthylselenocyanates. The structures of the products were investigated by spectroscopic methods. 相似文献
964.
Y. Yener M.N. Özişik C.E. Siewert 《Journal of Quantitative Spectroscopy & Radiative Transfer》1976,16(2):165-175
A generalized equation of radiative transfer in the two-group picket-fence model is analyzed for a plane parallel, emitting, absorbing and isotropically scattering medium containing uniform heat sources and having boundary surfaces which are diffuse emitters and diffuse reflectors and are maintained at uniform but arbitrary temperatures. The solution of the general problem is expressed by the superposition of simpler problems which are solved by the application of the normal-mode-expansion technique. Highly accurate numerical results are presented for the temperature distribution and the radiative heat flux in the medium. 相似文献
965.
It is shown that in an electron gas with coexisting charge density wave and spin density wave a spontaneous magnetization can occur. In the first paramagnetic region (T,Tt;Δs = Δt = 0) the spin susceptibility is independent of temperature (Pauli paramagnetism). In the second paramagnetic region (TK<T<Tt,Δt≠0;Δs=0) the total susceptibility of the spin density wave is enhanced by a temperature dependent paramagnetic susceptibility with a Curie type law. This reflects the instability of the system to the formation of a charge density wave or to ferromagnetism. At sufficiently low temperatures (T~TK) the spin susceptibility is anomalous great a fact which cannot be explained with the standard Fedders-Martin theory. Experimental results for pure chromium are in good agreement with our predictions. 相似文献
966.
Summary A gas chromatographic method is described for the analysis of methyldemeton present in the form of two isomers,O,O-dimethyl O-2-(ethylthio)ethylphosphorothioate andO,O-dimethyl S-2(ethylthio)ethylphosphorothioate in mixtures containg benzene, xylene, 3-thiapentanol-1, andO,O,O-trimethylthiophosphate. Such mixtures are obtained when methyldemeton is synthesized fromO,O-dimethylchlorothiophosphate and 3-thiapentanol-1 [1]. The best results are obtained using a short stainless steel column packed with 5% (w/w) OV-17 on Chromosorb G AW-DMCS 100–120 mesh. 相似文献
967.
Electron spin resonance spectra of Cu2+ doped in single crystals of strontium tartrate trihydrate grown by a diffusion technique have been investigated at 77K. Copper enters the lattice substitutionally and is trapped at two magnetically inequivalent sites. ESR measurements gave the following values for the spin-Hamiltonian parameters. Cu2+(I): ggg = 2.0380, gyy = 2.1317, gzz = 2.3918 and Axx = 26.3 G, Ayy = 56.3 G, Azz = 110.8 G. Cu2+(II): gxx = 2.0497, gyy = 2.1297, gzz = 2.3706 and Axx = 19.2 G, Ayy = 61.4 G, Azz = 107.2 G. 相似文献
968.
969.
The aim of this study is extraction, preconcentration and spectrophotometric determination of Rhodamine B (RB) in aqueous media by developing solid phase extraction (SPE) and cloud point extraction (CPE) methods. Amberlite XAD-1180 adsorbent and Tergitol NP-7 surfactant were used for SPE and CPE, respectively. Parameters of SPE and CPE which effected quantitative extractions were investigated and optimized. Matrix effects of some ions and dyes were analyzed at the optimum conditions. Developed methods were used to determine RB contents of anti-freeze, lipstick and water samples. The results of both methods demonstrated that the RB was quantitatively extracted and determined. RB contents of solid samples were found between 473 ± 15 and 317 ± 8 μg/g; 472 ± 11 and 312 ± 6 μg/L dye contents were determined for liquid samples. The methods were tested by analysis of spiked samples. Analytical characteristics of the methods were compared with each other and previously reported studies. 相似文献
970.
Özge Yetgin Çetin Hatice Karadeniz Alper Karakaş Serpil Yenisoy-Karakaş 《Journal of Analytical Chemistry》2018,73(6):613-625
The uncertainty of measurement for well-known neurotransmitters like serotonin, noradrenalin and gamma-aminobutyric acid (GABA), glutamate and melatonin hormone with high performance liquid chromatography?fluorescence detection was calculated after the method validation. Two methods were developed for the determination of the neurotransmitters. A derivatization step was performed for the determination of GABA and glutamate. Sensitivity, method detection limit, limit of quantification, linearity, recovery, interday and intraday precision values were calculated. Low detection limit values were obtained especially for the determination of GABA and glutamate. Then, bottom-up approach was used to calculate measurement uncertainty. The critical stages of the method were evaluated. The major sources of the uncertainty budget were calibration curves, stock solution and recovery. The calculated percentage relative uncertainty values for the compounds changed between 10.1 and 16.7. 相似文献