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111.
On the supercyclicity and hypercyclicity of the operator algebra 总被引:1,自引:0,他引:1
Let B(X) be the operator algebra for a separable infinite dimensional Hilbert space H, endowed with the strong operator topology or *-strong topology. We give sufficient conditions for a continuous linear mapping L : B(X) →B(X) to be supercyclic or ,-supercyclic. In particular our condition implies the existence of an infinite dimensional subspace of supercyclic vectors for a mapping T on H. Hypercyclicity of the operator algebra with strong operator topology was studied' by Chan and here we obtain an analogous result in the case of *-strong operator topology. 相似文献
112.
A spectrophotometric flow injection system is described for the determination of hydrazine, involving oxidation of hydrazine by thallium(III) with concomitant formation of thallium(I). The optimum analytical conditions have been established. The linear range for hydrazine is 25-500 ng ml(-1) with a detection limit of 20 ng ml(-1). The sampling frequency is 40+/-5 samples h(-1). The relative standard deviation for 100, 250 and 500 ng ml(-1) is 3.5, 2.6 and 1.8%, respectively. The method has been applied to the determination of hydrazine in water. 相似文献
113.
Spino C Rezaei H Dupont-Gaudet K Bélanger F 《Journal of the American Chemical Society》2004,126(32):9926-9927
Inter- and intramolecular [4 + 1]-annulations between dialkoxy carbenes and electron-deficient dienes afford mono- or bicyclic products in moderate to good yield. 相似文献
114.
G. Rezaei Behbehani Marie Dillon Jennifer Smyth W. Earle Waghorne 《Journal of solution chemistry》2002,31(10):811-822
The infrared spectra of tetramethylurea have been measured in mixtures of dimethylsulfoxide or acetonitrile with D2O or deuterated methanol (CH3OD). Marked solvatochroism is observed for bands associated with the C=O and C–N stretches of tetramethylurea, with the former moving to lower wavenumber, and the latter to higher, as the concentration of the protic component is increased. The C=O band shows four distinct absorbances, which are attributed to non-, mono, di-, and trihydrogen bonded tetramethylurea. The relative populations of the different hydrogen bonded species were determined from analyses of the C=O band shapes. It is found that the variations in the populations of the different hydrogen bonded species can be accounted for by a simple mass action treatment. 相似文献
115.
Enthalpies of Transfer of Tetraalkylammonium Bromides and CsBr from water to Aqueous DMF at 298.15 K
G. Rezaei Behbehani 《Journal of solution chemistry》2007,36(8):939-945
Enthalpies of transfer of tetraalkylammonium bromides and CsBr from water to aqueous DMF mixtures are reported and analyzed
in terms of a new solvation theory. It was found that a previous equation could not reproduce these data over the whole range
of solvent compositions. Using a new solvation theory to model the enthalpies of transfer shows excellent agreement between
experimental and calculated values over the entire range of solvent compositions. The analyses show that tetrapropylammonium
bromide, Pr4NBr, and tetrapentylammonium bromide, Pen4NBr, are preferentially solvated by water; in contrast tetrabutylammonium bromide, Bu4NBr, is preferentially solvated by DMF. The solvation of tetramethylammonium bromide, Me4NBr, and cesium bromide, CsBr, is random. The extent to which the tetraalkylammonium bromides disrupt solvent–solvent bonds
increases systematically in going from Me4NBr to Pen4NBr. 相似文献
116.
Two electron-deficient dienes were reacted with a series of twelve electron-poor and electron-rich dienophiles to give, in some cases, the corresponding Diels-Alder adducts. Clear differences in the roles played by the two frontier orbital interactions emerged. It was demonstrated that in the case of normal Diels-Alder cycloadditions, the FMO theory could predict the relative reactivities between dienophiles, while in the case of inverse-electron demand Diels-Alder reactions, it could not. It was shown that the dissymmetry in electron-rich dienophiles increases their reactivities. 相似文献
117.
Neeraj Gandotra Bartomiej Kizielewicz Abhimanyu Anand Aleksandra Bczkiewicz Andrii Shekhovtsov Jarosaw Wtrbski Akbar Rezaei Wojciech Saabun 《Entropy (Basel, Switzerland)》2021,23(12)
The purpose of this paper is to propose a new Pythagorean fuzzy entropy for Pythagorean fuzzy sets, which is a continuation of the Pythagorean fuzzy entropy of intuitionistic sets. The Pythagorean fuzzy set continues the intuitionistic fuzzy set with the additional advantage that it is well equipped to overcome its imperfections. Its entropy determines the quantity of information in the Pythagorean fuzzy set. Thus, the proposed entropy provides a new flexible tool that is particularly useful in complex multi-criteria problems where uncertain data and inaccurate information are considered. The performance of the introduced method is illustrated in a real-life case study, including a multi-criteria company selection problem. In this example, we provide a numerical illustration to distinguish the entropy measure proposed from some existing entropies used for Pythagorean fuzzy sets and intuitionistic fuzzy sets. Statistical illustrations show that the proposed entropy measures are reliable for demonstrating the degree of fuzziness of both Pythagorean fuzzy set (PFS) and intuitionistic fuzzy sets (IFS). In addition, a multi-criteria decision-making method complex proportional assessment (COPRAS) was also proposed with weights calculated based on the proposed new entropy measure. Finally, to validate the reliability of the results obtained using the proposed entropy, a comparative analysis was performed with a set of carefully selected reference methods containing other generally used entropy measurement methods. The illustrated numerical example proves that the calculation results of the proposed new method are similar to those of several other up-to-date methods. 相似文献
118.
An optical sensor has been proposed for the determination of silver by spectrophotometry. The sensor was prepared by immobilizing
5(p-dimethylaminobenzylidene)rhodanine on a transparent triacetylcellulose membrane. The effect of different variables on
the response of the sensor was studied and the optimum conditions were established. The sensor responded linearly in the range
1.8–55.6 μM of silver with a limit of detection of 0.8 μM and a response time range of 8–10 min depending on the concentration
of the silver ions. The presented optode is reversible and stable if stored in water for more than one month without reagent
leaching. The relative standard deviation for seven replicated measurement of 4.6 and 37 μM silver was 3.15 and 2.76%, respectively.
The sensor was successfully applied to the determination of silver in a silver sulphadiazine cream, an ore sample, and a radiology
film.
The text was submitted by the authors in English. 相似文献
119.
A simple and sensitive spectrofluorometric method was developed for the simultaneous determination of ascorbic acid and cysteine by a flow-injection system. This method is based on the reduction of Tl(III) with ascorbic acid or cysteine in acidic media, producing fluorescence reagent, TlCl3(2-) (lambdaex = 227 nm, lambdaem = 419 nm). The injected sample solution was divided into two separate streams. The first stream was treated with Tl(III) at pH 3.0 and then passed through a 270 cm reaction coil to the flow cell of the spectrofluorometer, where the fluorescence intensity was measured. This signal is related to ascorbic acid and cysteine concentration. The second part of the injected sample solution was treated with Tl(III) in HCl solution and then passed through a 50 cm reaction coil to the flow cell and the fluorescence intensity was measured. This signal is related only to cysteine. Thus, the ascorbic acid content was determined directly by the difference according to the calibration curve. Ascorbic acid and cysteine can be determined in the range of 1 x 10(-6) to 5.0 x 10(-5) M, at a rate of 16 samples per hour. The limits of detection (S/N = 3) were 8 x 10(-7) M for ascorbic acid and 7 x 10(-7) M for cysteine. The influence of potential interfering substances was studied. The proposed method was successfully applied to the simultaneous determination of both analytes in real samples. 相似文献
120.
Ali Jebali Seyedhossein Hekmatimoghaddam Aliasghar Behzadi Iraj Rezapor Bahador Haji Mohammadi Tahereh Jasemizad Seyed Ali Yasini Morteza Javadzadeh Asiye Amiri Mansoure Soltani Zeynab Rezaei Najme Sedighi Mina Seyfi Mohammad Rezaei Mehran Sayadi 《Cellulose (London, England)》2013,20(6):2897-2907
In this study, cellulose nanoparticles were prepared by acid hydrolysis, separately conjugated with allicin and lysozyme by a carbodiimide cross-linker, and characterized by scanning electron microscopy, dynamic light scattering, and Fourier transform infrared spectroscopy. Then, their antimicrobial properties were evaluated by the microdilution method and compared with allicin, lysozyme, and nanocellulose alone. The results showed that nanocellulose had few antimicrobial activities, but allicin-conjugated nanocellulose (ACNC) and lysozyme-conjugated nanocellulose (LCNC) had good antifungal and antibacterial effects against standard strains of Candida albicans, Aspergillus niger, Staphylococcus aureus, and Escherichia coli. Noticeably, although allicin and lysozyme had different minimum inhibitory concentrations (MICs) against all strains, the same quantity of MIC50 and MIC90 was observed for both ACNC and LCNC. The authors suggest that both ACNC and LCNC can be used in industries as an antimicrobial agent in food packaging, inside foodstuffs, and in textile materials. 相似文献