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31.
Mohammad Mazloum Ardakani Ali Asghar Ensafi Mohammad Salavati Niasari Hossain Mirhoseini 《Analytical sciences》2003,19(8):1187-1190
The performance of octahydroxycalix[4]arene derivative used as a neutral carrier for silver polymeric membrane electrode was studied. The sensor gave a good Nernstian response of 58 +/- 1 mV per decade for silver ion in the activity range 3.3 x 10(-6) to 3.3 x 10(-2) M Ag+. The limit of detection reached 2.1 x 10(-6) M Ag+ and exhibited high selectivity for silver ion against the alkali, alkaline earth and transition metal ions. The sensor can be used in wide pH range from 1.5 to 6.5. The response time of the sensor is less than 20 s. The potentiometric sensor was used as the indicator electrode in the titration of Ag+ ions by sodium chloride solution. 相似文献
32.
Ghodratollah Absalan Mohammad Soleimani Mozaffar Asadi Mohammad Bagher Ahmadi 《Analytical sciences》2004,20(10):1433-1436
A new ammonia optical sensor was designed using bis(acetylacetoneethylendiamine)tributylphosphin cobalt(III) tetraphenylborate complex, coated on transparent triacetylcellulose film as membrane. The change in the absorbance of the optode at the maximum wavelength of 408 nm was related to ammonia concentration in aqueous samples. A buffer solution with a pH of 9 (sodium borate-HCl) was used. The optode was fully regenerated in pH 2. The linear dynamic range for determination of ammonia was 3.3 x 10(-4) to 6.9 x 10(-3) mol l(-1) with a detection limit of 5.0 x 10(-5) mol l(-1) and a response time range of 4 - 6 min. This membrane was successfully applied for determination of ammonia in drinking water. 相似文献
33.
Hamid R Zare Masoud Salavati-Niassary Farkhondeh Memarzadeh Mohammad Mazloum Navid Nasirizadeh 《Analytical sciences》2004,20(5):815-819
A novel membrane coated platinum-wire electrode (MCPWE) based on N,N'-bis(2-thienylmethylene)-1,2-diaminobenzene (BTMD) for highly selective determination of Ag+ ion has been developed. The influences of membrane composition and pH on the potentiometric responses of electrode were investigated. The potentiometric responses are independent of the pH of the test solution in the range of 5.0 - 9.0. The electrode shows a linear response for Ag+ ion over the concentration range of 1.0 x 10(-60 to 1.0 x 10(-1) M with a lower detection limit of 6.0 x 10(-7) M. The electrode possesses a Nernstian slope of 59.7 mV decade(-1) and a fast response time of < or = 17 s and can be used for at least 2 months without any observable deviation. The proposed electrode displayed very good selectivity for Ag+ ion with respect to NH4+ and alkali, alkaline earth and some common transition metal ions. The practical utility of the electrode has been demonstrated by its use as the indicator electrode in the potentiometric titration of an AgNO3 solution with a NaI solution and in determination of the silver content of a developed radiological film. 相似文献
34.
LetP(z) be a polynomial of degreen which does not vanish in |z|<1. In this paper, we estimate the maximum and minimum moduli of thekth polar derivative ofP(z) on |z|=1 and thereby obtain compact generalizations of some known results, which among other results, yields interesting refinements of Erdos-Lax theorem and a theorem of Ankeny and Rivlin. 相似文献
35.
The triple differential cross-section for K-shell ionization of silver and copper atoms by relativistic electrons have been
computed in the coplanar symmetric geometry with the inclusion of exchange effects following the multiple scattering theory
of Das and Seal [1] multiplied by suitable spinors. Present computed results are marginally improved in some cases from the
previous computed results [2]. Present results are compared with measured values [3] and with previous computation results
[2]. Some other theoretical computational results are also presented here for comparison.
相似文献
36.
We prove that, in Euclidean space, any nonnegatively curved, compact, smoothly immersed hypersurface lies outside the convex hull of its boundary, provided the boundary satisfies certain required conditions. This gives a convex hull property, dual to the classical one for surfaces with nonpositive curvature. A version of this result in the nonsmooth category is obtained as well. We show that our boundary conditions determine the topology of the surface up to at most two choices. The proof is based on uniform estimates for radii of convexity of these surfaces under a clipping procedure, a noncollapsing convergence theorem, and a gluing procedure. 相似文献
37.
Hamid R. Memarian Mohammad Bagheri Dietrich D?pp 《Monatshefte für Chemie / Chemical Monthly》2004,42(3):833-838
In continuation of previous work some novel 3,5-diacetyl-1,4-dihydropyridine derivatives were synthesized and their photochemical behavior was studied under oxygen and argon atmosphere. Oxidation of the dihydropyridine ring and formation of pyridine derivatives was the result of the reaction. The presence of oxygen affects not only on the rate of oxidation, but also the formation of some unidentified by-products was observed on irradiation under this atmosphere. 相似文献
38.
Md. Nur Alam Per B. Zetterlund Masayoshi Okubo 《Journal of polymer science. Part A, Polymer chemistry》2007,45(21):4995-5004
Bimolecular termination in nitroxide‐mediated radical polymerization in miniemulsion has been investigated through the heating of a polystyrene–2,2,6,6‐tetramethylpiperidinyl‐1‐oxy macroinitiator and its 4‐hydroxy‐2,2,6,6‐tetramethylpiperidinyl‐1‐oxy analogue in an aqueous toluene dispersion with sodium dodecyl benzenesulfonate as a surfactant at 125 °C. The level of bimolecular termination by combination, evaluated from the high‐molecular‐weight shoulder, was higher in miniemulsion than in solution and increased with decreasing particle size. Quantitative analysis revealed that these results cannot be rationalized solely by nitroxide partitioning to the aqueous phase. The results are explained by an interface effect, by which nitroxide is adsorbed or located at the aqueous–organic interface. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4995–5004, 2007 相似文献
39.
Mohammad Reza Ganjali Morteza Rezapour Mohammad Reza Pourjavid Masoud Salavati-Niasari 《Analytical sciences》2003,19(8):1127-1131
A cobalt(II) derivative was used as a suitable ionophore for the preparation of a polymeric membrane nitrite-selective electrode. The electrode reveals a Nemstian behavior over a very wide NO2- ion concentration range (1.0 x 10(-6)-1.0 x 10(-1) M) and a very low detection limit (5.0 x 10(-7) M). The potentiometric response is independent of the pH of solution in the pH range 4.0-9.5. The electrode shows advantages such as low resistance, fast response and, most importantly, good selectivity relative to a wide variety of inorganic and organic anions. In fact, the selectivity behavior of the proposed NO2- ion-selective electrode shows great improvements compared to the previously reported electrodes for nitrite ion. The proposed electrodes could be used for at least 2 months without any significant changes in potentials. The electrode was successfully applied to the determination of nitrate ion concentrations in sausage and milk samples. 相似文献
40.