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41.
Static dipole and quadrupole polarizability (αd and αq, respectively) values of coupled Hartree–Fock quality have been calculated for the alkaline earth atoms Be(2s), Mg(3s), Ca(4s), and Sr(5s) using a method based on the many-body perturbation theory. The present values of αd and αq for Be and αd for Mg are in excellent agreement with the other available results of similar accuracy. The CHF calculations of αd for Sr and αq for Mg, Ca, and Sr are being reported for the first time. 相似文献
42.
A. J. V. Ferrer-Correia K. R. Jennings D. K. Sen Sharma 《Journal of mass spectrometry : JMS》1976,11(8):867-872
A method for the location of the positions of carbon-carbon double bonds using high pressure mass spectrometry is proposed. A known olefinic molecular ion reacts with a second, unknown olefin to form a four-centre complex, which fragments with retention of the structural identity of methylene and substituted methylene groups to eliminate a new olefin molecule and to form an unsaturated ion from which the position of the double bond in the unknown olefin can be inferred. Vinyl methyl ether proved to be a convenient reagent gas and its molecular ion undergoes the required reaction with several classes of olefinic compound. Conjugated dienes and unsaturated compounds containing electronegative groups do not undergo this reaction. 相似文献
43.
Surface composition and property of film prepared with aqueous dispersion of polyurethaneurea-acrylate including fluorinated block copolymer 总被引:1,自引:0,他引:1
The aqueous dispersion of polyurethaneurea-acrylate (PUA) including small amount of fluorinated block copolymers containing carboxyl groups (PATF), which can be dissolved in water, was used to make films and the surface properties of these films were examined. The experimental data show that the modified PUA film exhibits a hydrophobic surface property, although the original surface of PUA film is hydrophilic. The surface composition of the modified PUA film was measured by ATR and XPS. The results indicate that there is a concentration gradient of the fluorine groups along the lines of thickness of the modified film and towards the outmost surface layer, resulting from the migration of fluorinated blocks to the air side surface of the modified PUA film during the film formation process. However, the PUA film can not be modified effectively by adding the sodium salt of PATF, since the urethane groups in the system are easy to occupy on the surface of the film. 相似文献
44.
Density functional theory (DFT) and Monte Carlo (MC) simulation with free energy perturbation (FEP) techniques have been used to study the tautomeric proton transfer reaction of 2-amino-2-oxazoline, 2-amino-2-thiazoline, and 2-amino-2-imidazoline in the gas phase and in water. Two reaction pathways were considered: the direct and water-assisted transfers. The optimized structures and thermodynamic properties of stationary points for the title reaction system in the gas phase were calculated at the B3LYP/6-311+G(d, p) level of theory. The potential energy profiles along the minimum energy path in the gas phase and in water were obtained. The study of the solvent effect of water on the proton transfer of 2-amino-2-oxozoline, 2-amino-2-thiazoline, and 2-amino-2-imidazoline indicates that water as a solvent is favorable for the water-assisted process and slows down the rate of the direct transfer pathway. 相似文献
45.
46.
Sajal Sen Mark W. Perrin Adam C. Sedgwick Vincent M. Lynch Jonathan L. Sessler Jonathan F. Arambula 《Chemical science》2021,12(21):7547
Recent decades have witnessed the emergence of Au(i) bis-N-heterocyclic carbenes (NHCs) as potential anticancer agents. However, these systems exhibit little interaction with serum proteins (e.g., human serum albumin), which presumably impacts their pharmacokinetic profile and tumor exposure. Anticancer drugs bound to human serum albumin (HSA) often benefit from significant advantages, including longer circulatory half-lives, tumor targeted delivery, and easier administration relative to the drug alone. In this work, we present Au(i) bis-NHCs complexes, 7 and 9, capable of binding to HSA. Complex 7 contains a reactive maleimide moiety for covalent protein conjugation, whereas its congener 9 contains a naphthalimide fluorophore for non-covalent binding. A similar drug motif was used in both cases. Complexes 7 and 9 were prepared from a carboxylic acid functionalized Au(i) bis-NHC (complex 2) using a newly developed post-synthetic amide functionalization protocol that allows coupling to both aliphatic and aromatic amines. Analytical, and in vitro techniques were used to confirm protein binding, as well as cellular uptake and antiproliferative activity in A549 human lung cancer cells. The present findings highlight a hitherto unexplored approach to modifying Au(i) bis-NHC drug candidates for protein ligation and serve to showcase the relative benefits of covalent and non-covalent HSA binding.Au(i) bis-N-heterocyclic carbenes (NHCs) functionalized using an amide linker were found to bind to human serum albumin (HSA) in covalent and non-covalent fashion. The solubility and in vitro anti-cancer activity of these new conjugates were studied. 相似文献
47.
Sen Gupta JG 《Talanta》1985,32(1):1-6
An improved graphite furnace atomic-absorption method has been developed for the determination of Sc, Y and the rare-earth elements in silicate rocks and related materials. The method, which involves the separation of the lanthanides by ion-exchange followed by their determination by electrothermal atomization, with use of an automatic sampling device, is more rapid than a previous method based on separation by co-precipitation with calcium oxalate and hydrous ferric oxide followed by normal injection of the solution into the furnace. Greater sensitivity (~ 10-40-fold) for La, Ce, Pr, Gd, Tb and Lu is also achieved by using a tantalum foil-lined graphite furnace instead of a pyrolytically-coated furnace. Results obtained for five international reference rock samples, NIM-G, SCo-1, MAG-1, SDC-1 and BHVO-1, are compared with those obtained previously by the oxalate-hydrous oxide co-precipitation method and with other published values. Results are given for four new Canadian iron-formation reference materials, FeR-1 to FeR-4. 相似文献
48.
The distribution of a solute in a gas-liquid Chromatographic column has been discussed from the probability view point and its analogy to the Bernoulli trial system has been shown. It has been shown that the reproduction of column behavior is possible by reproducing the probability. The criterion for the optimum column temperature has also been discussed. Recommendations have been made for determining the optimum column conditions and its reproduction. 相似文献
49.
Summary The main theorem establishes the existence of a positive decaying solution u D
0
1,p
(Rn) of a quasilinear elliptic problem involving the p-Laplacian operator and the critical Sobolev exponent pN/(N - p), 1
相似文献
50.
Chaotic dynamics of charged particles in the field of two monochromatic waves in a magnetized plasma
We study the dynamics of charged particles in the presence of two electrostatic waves propagating obliquely to an ambient magnetic field. The presence of a second wave makes the problem a two-dimensional and time-dependent one with a complicated phase space behavior. We derive a set of difference equations (maps) for the nonrelativistic particle motion limit and numerically study them to elucidate the various aspects of the phase space dynamics. For the general case of oblique propagation, we observe synergistic effects leading to the lowering of the stochasticity threshold and the concomitant reduction in electric field amplitudes for particle heating applications. These results can be understood in terms of the resonance structures associated with the two waves and we obtain approximate analytic expressions for the thresholds. For the degenerate case of omega(1)=nOmega,omega(2)=mOmega (where omega(1),omega(2) are the frequencies of the two waves, Omega is the cyclotron frequency and n,m are integers) and strictly perpendicular propagation, the problem simplifies to a one-and-one-half-dimensional one. We observe the presence of stochastic webs in this situation. (c) 1996 American Institute of Physics. 相似文献