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11.
Résumé Soit (V
)0 une résolvante définie sur un espace mesurable telle que le noyau initial est borné; on trouve une condition nécéssaire et suffisante pour qu'un noyau borné U possède une résolvante (U
)0 telle que U
V
pour tout 0. On donne plusieurs applications de ce résultat. 相似文献
12.
Ahmed A. El-Asmy Yehia M. Shaibi Abdallah S. Babaqi Mohamed Mounir Salah A. Ashour 《Transition Metal Chemistry》1988,13(5):332-335
Summary The interaction of 1-benzoin-4-phenylthiosemicarbazone (H2 BPS) with some transition metal ions has been investigated. The ligand can function as a tridentate chelating agent, giving M(HBPS)2 and M(BPS). Potentiometric studies proved that the mechanism of chelation is based on hydrogen ion liberation. Spectral studies in solution show that the ligand could be used for the microdetermination of CuIIions. On the basis of magnetic and spectral data, an octahedral structure is proposed for the CoII and NiII complexes and a square-planar structure for the CuII complex. The corrosion inhibition of aluminium in Cl3CCO2H using H2BPS is studied. The electrical conductivity of H2BPS and of its complexes have been measured. The ligand shows an activation energy in the range of semiconducting materials. The antimicrobial activity of all compounds has also been demonstrated. 相似文献
13.
Fatehy M. Abdel‐Haleem Azza Salah Mahmoud S. Rizk Hussein Moustafa Mikhael Bechelany Ahmed Barhoum 《Electroanalysis》2019,31(4):778-789
Thiourea derivative‐based carbon paste electrode (TUD1‐CPE) was constructed as a potentiometric sensor for the determination of salicylate anion in pharmaceutical formulations, Aspocid® and Aspirin®. The optimized CPE contained 45.5 % graphite, 0.5 % reduced graphene oxide (rGO), 46.0 % nitrophenyl octyl ether (NPOE) plasticizer, 5.0 % TUD1 ionophore, and 3.0 % tridodecylmethyl ammonium chloride as additive. The incorporation of NPOE of high dielectric constant, and rGO in electrode caused better performance of the sensor; Nernstian response of 59.0 mV decade?1 in the concentration range of 10?1–10?5 mole L?1, a detection limit of 1×10?5 mole L?1 in a very short response time of 6 seconds. The prepared sensor showed high selectivity against similar anions (i. e. , benzoate, I?, SCN?). Selectivity was confirmed by calculating the formation constant (Kβ) using sandwich membrane method, where Kβ for TUD1‐salicylate is 100.43. Theoretical calculations at DFT‐B3LY/6‐31G** level of theory were performed to find interaction mechanism, Energies of HOMO and LUMO orbitals, non‐linear optical (NLO) properties (the electronic dipole moment (μ), first‐order hyperpolarizability (β), the hyper‐Rayleigh scattering (βHRS) and the depolarization ratio (DR)), and other global properties; these calculations showed lower values of β and DR, higher value of βHRS, and the shortest lengths of the four N?H bonds between TUD1 and salicylate which confirm their strong complexation and salicylate‐selectivity. Also, all the studied anion‐TUD1 exhibited relatively high NLO properties, and these results were considered as a preliminary study for investigating new types of NLO bearing materials. The sensors were applied successfully for the determination of salicylate anion in Aspocid® and Aspirin®. 相似文献
14.
Salah Hassoon 《Analytica chimica acta》2004,512(1):125-132
Ultrasound-based water treatment is often applied for degradation of stable organic pollutants, such as polycyclic aromatic hydrocarbons and halogenated compounds. Monitoring the degradation process, during the application of ultrasound radiation, is of considerable economical interest. In this work, the possibility of performing on-line spectral analysis during sonication was examined and it was found that direct absorption or fluorescence readings are misleading. Optical monitoring is strongly affected by the absorption and scattering of light by cavitation micro-bubbles and ultrasound induced particulates. A model was developed to account for these effects and to allow for on-line fluorescence analysis. The model takes into account the absorption and scattering coefficients of the micro-bubbles and particulates, as well as their time dependent concentration. The model parameters are found from independent measurements where the pollutants are added to already sonicated pure water. Then, the model is tested for predicting the actual fluorescence behavior during the sonication process. It has been shown that the model allows for recovery of the true degradation data, as obtained by off-line HPLC measurements. 相似文献
15.
Small amounts of papaverine (about 3 mg in 15 ml solution) can be determined heterometrically in the presence of thiocyanate by titration with cobaltous solution. A strong electrolyte (Na2SO4) must be added to obtain a clear endpoint. The titration can be carried out in the presence of large amounts (97%) of quinine and ephedrine. The titration takes 2–3 min and the error rarely exceeds 1%.Papaverine, quinine, and ephedrine can be determined individually by spectrophotometry as their cobaltothiocyanates, which are extracted in 30% cyclohexanone in carbon tetrachloride, and the optical density measured at 625 nm. The method is reproducible at milligram levels with a standard deviation of ±0.3% for papaverine and quinine and = 0.5% for ephedrine. 相似文献
16.
Nitron and tetraphenylarsonium chloride react with a cobaltous salt in the presence of thiocyanate to form blue ion-association complexes, which can be extracted with organic solvents. This fact has been made the basis for the analysis of mixtures of nitrate and perchlorate by difference spectrophotometry. An aliquot of the sample solution is treated with a known excess of tetraphenylarsonium chloride to precipitate perchlorate only. After separating off the precipitate, the excess of reagent is determined in the supernatant liquid as tetraphenylarsonium cobaltothiocyanate and the perchlorate content can be found from a calibration curve. Another aliquot is treated with an excess of nitron to precipitate both anions; the excess of nitron is then determined as nitron
Perchlorate | Nitrate | ||||||
Taken (μg) | Found (μg) | Error (%) | Taken (μg) | Found (μg) | Error (%) | ||
400 | 404 | + 1.00 | 248 | 250 | +0.81 | ||
400 | 400 | 0.00 | 496 | 492 | ?0.81 | ||
400 | 400 | 0.00 | 992 | 992 | 0.00 | ||
800 | 796 | ?0.50 | 248 | 248 | 0.00 | ||
600 | 602 | +0.33 | 248 | 245 | ?1.21 | ||
800 | 792 | ?1.25 | 496 | 498 | +0.40 |