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41.
We propose an all-electrical nanostructure where pure spin current is induced in the transverse voltage probes attached to a quantum-coherent ballistic one-dimensional ring when unpolarized charge current is injected through its longitudinal leads. Tuning of the Rashba spin-orbit coupling in a semiconductor heterostructure hosting the ring generates quasiperiodic oscillations of the predicted spin-Hall current due to spin-sensitive quantum-interference effects caused by the difference in the Aharonov-Casher phase accumulated by opposite spin states. Its amplitude is comparable to that of the spin-Hall current predicted for finite-size (simply connected) two-dimensional electron gases, while it gets reduced gradually in wide two-dimensional rings or due to spin-independent disorder. 相似文献
42.
The hydrozirconation of alkynes with zirconocene hydrochloride and the dimethylzinc-mediated addition of alkenylzirconocenes to diphenylphosphinoyl imines can be greatly accelerated with microwave irradiation, resulting in a convenient and rapid one-pot process for the preparation of synthetically useful allylic amines. 相似文献
43.
Vujasinović I Veljković J Mlinarić-Majerski K 《The Journal of organic chemistry》2004,69(24):8550-8553
The preparation of new tin templates, stannathianes 1-3 is described. New templates have been successfully applied to the synthesis of macrocyclic polythialactones 4-9 by cyclization of corresponding stannathianes 1-3 with pimeloyl dichloride. 相似文献
44.
Optical sectioning in wide-field microscopy is achieved by illumination of the object with a continuously moving single-spatial-frequency pattern and detecting the image with a smart pixel detector array. This detector performs an on-chip electronic signal processing that extracts the optically sectioned image. The optically sectioned image is directly observed in real time without any additional postprocessing. 相似文献
45.
D. Nikolić S. Djurović Z. Mijatović R. Kobilarov N. Konjević 《Journal of Applied Spectroscopy》2001,68(6):902-910
A method of simulating the contour of the asymmetric spectral lines of neutral nonhydrogen-like atoms in a plasma is suggested. The methods of nonlinear regression are used to approximate the experimental data by a model function. The method has been checked on the spectral lines emitted by the electric arc stabilized by the walls. The method makes it possible to evaluate the Stark parameters directly from the experimentally obtained shapes of isolated or overlapping spectral lines. 相似文献
46.
I. S. Ristić L. Nikolić V. Nikolić D. Ilić J. Budinski-Simendić 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2011,85(13):2264-2269
Polyrotaxanes are intermediary products in the synthesis of topological gels. They are created by inclusion complex formation
of hydrophobic linear macromolecules with cyclodextrins or their derivatives. Then, pairs of cyclodextrin molecules with covalently
linkage were practically forming the nodes of the semi-flexible polymer network. Such gels are called topological gels and
they can absorb huge quantities of water due to the net flexibility allowing the poly(ethylene oxide) chains to slide through
the cyclodextrin cavities, without being pulled out altogether. For polyrotaxane formation poly(ethylene oxide) was used like
linear macromolecules. There are hydroxyl groups at poly(ethylene oxide) chains, whereby the linking of the voluminous molecules
should be made. To avoid the reaction of cyclodextrin OH groups with stoppers, they should be protected by, e.g., acetylation.
In this work, the acetylation of the OH groups of β-cyclodextrin was performed by acetic acid anhydride with iodine as the
catalyst. The acetylation reaction was assessed by the FTIR and HPLC method. By the HPLC analysis was found that the acetylation
was completed in 20 minutes. Inserting of poly(ethylene oxide) with 4000 g/mol molecule mass into acetyl-β-cyclodextrin with
2:1 poly(ethylene oxide) monomer unit to acetyl-β-cyclodextrin ratio was also monitored by FTIR, and it was found that the
process was completed in 12 h at the temperature of 10°C. If the process is performed at temperatures above 10°C, or for periods
longer than 12 hours, the process of uncontrolled hydrolysis of acetate groups was initiated. 相似文献
47.
G. M. Nikolić A. M. Veselinović R. S. Nikolić S. S. Mitić 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2011,85(13):2270-2273
Gallic acid autoxidation in weakly alkaline aqueous solutions was studied by UV-Vis spectrophotometry and ESR spectroscopy
under various conditions. Lowering the pH value from 10 to 8.5 probably changes the mechanism of the autoxidation reaction
as evidenced by the different time variations of UV-Vis spectra of solutions. The presence of Mg(II) ions greatly influences
the autoxidation reaction at pH 8.5. Although the UV-Vis spectral changes with time follow the similar pattern during the
gallic acid autoxidation at pH 10 and at pH 8.5 in the presence of Mg(II) ions, some small differences indicate that Mg(II)
ions not only affect the electron density of absorbing species but also influence the overall mechanism of the autoxidation
reaction. ESR spectra of free radials formed during the initial stage of gallic acid autoxidation at pH 8.5 in the presence
of Mg(II) ions were recorded. Computer simulation of ESR spectra allows partial characterization of these free radicals. 相似文献
48.
Copper electrodeposition processes in the hydrogen co-deposition range by the pulsating current (PC) regime were examined by the determination of the average current efficiency of hydrogen evolution and by the scanning electron microscopic (SEM) analysis of the morphology of the formed deposits. The two sets of the square-wave PC of the same pause to pulse ratios, but with different duration of deposition pulses and pauses were analyzed. The one set of square-wave PC was with the constant pause duration and different deposition pulses. In the other set, the deposition pulse was constant while the pause duration was varied. The obtained results were compared with those obtained by electrodeposition at the constant overpotential from solutions of different CuSO4 and H2SO4 concentrations. It was found that the effect of the increasing deposition pulse was equivalent to the decreasing CuSO4 concentration, while the effect of the decreasing pause duration was equivalent to the increasing H2SO4 concentration. It is shown that it is possible to achieve a substitution of more solutions of different CuSO4 and H2SO4 concentartions by the use of the only one solution if the appropriate PC parameters were applied, what can be of high technological significance. 相似文献
49.
Lina Skardžiūtė Karolis Kazlauskas Jelena Dodonova Jonas Bucevičius Sigitas Tumkevičius Saulius Juršėnas 《Tetrahedron》2013
Pyrrolo[2,3-d]pyrimidine derivatives possessing different sterically-hindered end-groups at position 7 of the heterocycle were studied and compared with respect to nanoaggregate formation ability by the reprecipitation method in aqueous solutions. The emergence of nanoaggregates with an increasing water fraction in THF/water mixture was traced by observing sudden changes in spectral and transient fluorescence dynamics accompanied by fluorescence efficiency turn-on. The aggregation induced emission with a maximal 20-fold emission efficiency enhancement was obtained. Tuning of the nanoaggregates sizes from about 50 nm to 600 nm by increasing the THF/water ratio was revealed by electron microscopy. Almost perfect spherical shapes of the nanoaggregates and their structureless fluorescence bands similar to those of their neat amorphous films suggested an amorphous-like nature of the pyrrolo[2,3-d]pyrimidine-based nanoparticles. 相似文献
50.
Aanski Marijana M. Dobrijevi Jelena P. Redepovi Azra S. Vuji ura N. Jovanovi-anta Suzana S. 《Chromatographia》2009,70(11):1679-1683
The retention behaviour of a number of 16,17-secoestrone derivatives has been studied by LC and HPTLC on a polar cyanopropyl-bonded stationary phase using non-aqueous and aqueous-organic mobile phases. The retention behaviour has been discussed in terms of nature of the solute, eluent and stationary phase. The correlation between retention constants of 16,17-secoestrone derivatives obtained from reversed-phases and commercially available ACD log P software (Advanced Chemistry, Toronto, Canada) has also been examined.
相似文献