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51.
Molecularly imprinted polymers hold great promise for the separation of chiral compounds. A non-covalent approach to the synthesis of MIPs relies on the presence of specific and non-specific interactions, which lead to the formation of a molecular imprint. The structural differences between 17-alpha-estradiol and 17-beta-estradiol are too small to permit their efficient separation on a MIP prepared with beta-estradiol as a template. Molecular modeling revealed the presence of only one hydrogen bond that differentiates the two isomers. 相似文献
52.
Jerzy Baranowski Tadeusz Cukiepda Bogusława Jeżowska-Trzebiatowska Henryk Kozłowski 《Chemical physics letters》1976,39(3):606-608
A simple method for the calculation of the resonance fields of the triplet EPR transitions is given, which are the solutions of a cubic equation with coefficients depending on the parameters g, D, and E. This method is very useful for the simulation of EPR powder spectra. 相似文献
53.
Kinetic parameters of thermal decomposition of compounds of general formulaM
2
I
M
II[Ni(NO2)6], whereM
I= K+, Rb+ or Cs+ andM
II= Ca2+, Sr2+ or Ba2+, were investigated on the basis of the respective thermal curves. Calculations of the reaction order and activation energy carried out by the Coats-Redfern method and by Doyle's method (modified by Zsakó) gave similar results, The reaction order is 2 for all the compounds investigated. In the group of potassium salts the activation energy increases fromM
II=Ca2+ toM
II=Ba2+. In the groups of rubidium and caesium salts, the lowest activation energy is observed whenM
II=Sr2+. Such behaviour of the nitritonickelates is explained in terms of structures and the principle of maximum density.
Zusammenfassung Die kinetischen Parameter der thermischen Zersetzung von Verbindungen der allgemeinen FormelM 2 I M II [Ni(NO2)6] (M I= K+, Rb+ oder Cs+ und MII = =Ca2+, Sr2+ oder Ba2+) wurden auf Grund der entsprechenden thermischen Kurven untersucht. Die an Hand der Coats-Redfern Methode und der durch Zsakó modifizierten Doyleschen Methode durchgeführten Berechnungen der Reaktionsordnung und der Aktivierungsenergie ergaben ähnliche Resultate. Die Reaktionsordnung ist 2 für sämtliche untersuchten Verbindungen. In der Gruppe der Kaliumsalze steigt die Aktivierungsenergie vonM II=Ca2+ in RichtungM II=Ba2+ an. In der Gruppe der Rubidium- und Caesiumsalze wird die niedrigste Aktivierungsenergie beiM II=Sr2+ beobachtet. Dieses Verhalten der Nitritonickelate wird durch die Strukturen und das Prinzip der maximalen Dichte erklärt.
1 2 II[Ni(NO2)6], I= +, Rb+Cs+,a II= 2+,8r2+2+. , - ( ), . 2. + 2+. II=S2+. .相似文献
54.
A commercial Chromolith C18 column and two new stationary phases with mixed ligands bonded on the Kromasil silica gel support, SG-MIX and SG-Chol, were characterized using simple tests based on the retention of non-polar, basic and acidic compounds. Polar and methylene selectivity tests in acetonitrile-water and methanol-water mobile phases revealed lower hydrophobicities of the SG-MIX and SG-Chol columns in comparison to the Chromolith column. The columns were further characterized using new test criteria - gradient oligomer capacity and isomeric selectivity and peak symmetry of naphthalene di-sulphonic acids in aqueous mobile phases. The cholesterolic column shows greater gradient oligomer selectivity for the separation of oligoethylene glycol samples than the SG-MIX and the Chromolith columns. Increased retention and peak tailing, but decreased isomeric selectivity for naphthalene-di-sulphonic acids was observed with the SG-MIX column, because of interactions with various polar bonded groups. 相似文献
55.
In this paper we discuss relations between symplectic forms and smooth structures on closed manifolds. Our main motivation is the problem if there exist symplectic structures on exotic tori. This is a symplectic generalization of a problem posed by Benson and Gordon. We give a short proof of the (known) positive answer to the original question of Benson and Gordon that there are no Kähler structures on exotic tori. We survey also other related results which give an evidence for the conjecture that there are no symplectic structures on exotic tori. 相似文献
56.
Edmonds KW Bogusławski P Wang KY Campion RP Novikov SN Farley NR Gallagher BL Foxon CT Sawicki M Dietl T Buongiorno Nardelli M Bernholc J 《Physical review letters》2004,92(3):037201
We present a combined theoretical and experimental study of the ferromagnetic semiconductor (Ga,Mn)As which explains the remarkably large changes observed on low-temperature annealing. Careful control of the annealing conditions allows us to obtain samples with ferromagnetic transition temperatures up to 159 K. Ab initio calculations, in situ Auger spectroscopy, and resistivity measurements during annealing show that the observed changes are due to out diffusion of Mn interstitials towards the surface, governed by an energy barrier of 0.7-0.8 eV. Electric fields induced by Mn acceptors have a significant effect on the diffusion. 相似文献
57.
We examine the Navier–Stokes equations in a two space dimensional time dependent domain. The system is considered with nonhomogeneous slip boundary conditions. The main result shows that under a certain geometrical constraint on deformations of the domain, it is possible to prove existence of solutions globally in time for arbitrary flows across the boundary with a new time independent bound on the vorticity. The geometrical restriction does not imply simply connectedness of the domain. Our model may be treated as a simple model of a pump.Mathematics Subject Classifications (2000) 35Q30, 75D03, 76D05. 相似文献
58.
Bogusлaw Misterkiewicz 《Journal of organometallic chemistry》1982,224(1):43-47
An alternative method for the preparation of 1-ferrocenylalkyl alcohols has been developed. This involves condensation of ferrocene with carbonyl compounds in concentrated sulfuric acid and addition of the resulting solutions of 1-ferrocenylalkylium ions into aqueous sodium bicarbonate. The mixtures are then treated with thioglycolic acid and the S-(1-ferrocenylalkyl)thioglycolic acids purified via sodium salts and hydrolysed in the presence of copper powder to give 1-ferrocenylalkyl alcohols in good yields. 相似文献
59.
The angular overlap model has been applied for the first time in a conformational study of ground state properties of coordination compounds. The existence of several triplet ground states resulting from continuous rotations about the MoOMo axis has been demonstrated for oxygen-bridged oxomolybdenum(V) dimers. 相似文献
60.
Sylwia Studzińska Rafał Rola Bogusław Buszewski 《Analytical and bioanalytical chemistry》2016,408(6):1585-1595