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81.
Clair S Variola F Kondratenko M Jedrzejowski P Nanci A Rosei F Perepichka DF 《The Journal of chemical physics》2008,128(14):144705
Surface modification of titanium and its alloys is of great importance for their practical application as biomedical implants. We have studied and compared assembly of dodecylphosphoric acid on commercial polished and on nanostructured titanium disks. The latter were produced by chemical etching that created nanoscale pits of typical size of about 20 nm. Enhanced hydrophobicity and high molecular density were obtained after functionalization of the nanotextured substrate. Aging tests showed a lifetime of the organic films of about one month in phosphate buffer. The samples were characterized by means of infrared spectroscopy, contact angle measurements, ellipsometry, and atomic force and scanning tunneling microscopies. 相似文献
82.
83.
Mikhail E. Minyaev Alexandr A. Vinogradov Dmitrii M. Roitershtein Konstantin A. Lyssenko Ivan V. Ananyev Ilya E. Nifant'ev 《Acta Crystallographica. Section C, Structural Chemistry》2016,72(7):578-584
The significant variety in the crystal structures of rare‐earth carboxylate complexes is due to both the large coordination numbers of the rare‐earth cations and the ability of the carboxylate anions to form several types of bridges between rare‐earth metal atoms. Therefore, these complexes are represented by mono‐, di‐ and polynuclear complexes, and by coordination polymers. The interaction of LnCl3(thf)x (Ln = Eu or Y; thf is tetrahydrofuran) with sodium or diethylammonium diphenylacetate in methanol followed by recrystallization from a DME/THF/hexane solvent mixture (DME is 1,2‐dimethoxyethane) leads to crystals of the non‐isomorphic dinuclear complexes tetrakis(μ‐2,2‐diphenylacetato)‐κ4O:O′;κ3O,O′:O′;κ3O:O,O′‐bis[(1,2‐dimethoxyethane‐κ2O,O′)(2,2‐diphenylacetato‐κ2O,O′)europium(III)], [Eu(C14H11O2)6(C4H10O2)2], (I), and tetrakis(μ‐2,2‐diphenylacetato)‐κ4O:O′;κ3O,O′:O′;κ3O:O,O′‐bis[(1,2‐dimethoxyethane‐κ2O,O′)(2,2‐diphenylacetato‐κ2O,O′)yttrium(III)], [Y(C14H11O2)6(C4H10O2)2], (II), possessing monoclinic (P21/c) symmetry. The [Ln(Ph2CHCOO)3(dme)]2 molecule (Ln = Eu or Y) lies on an inversion centre and exhibits three different coordination modes of the diphenylacetate ligands, namely bidentate κ2O,O′‐terminal, bidentate μ2‐κ1O:κ1O′‐bridging and tridentate μ2‐κ1O:κ2O,O′‐semibridging. The terminal and bridging ligands in (I) are disordered over two positions, with an occupancy ratio of 0.806 (2):0.194 (2). The interaction of EuCl3(thf)2 with Na[Ph3CCOO] in methanol followed by crystallization from hot methanol produces crystals of tetrakis(methanol‐κO)tris(2,2,2‐triphenylacetato)‐κ4O:O′;κO‐europium(III) methanol disolvate, [Eu(C19H15O2)3(CH3OH)4]·2CH3OH, (III)·2MeOH, with triclinic (P) symmetry. The molecule of (III) contains two O,O′‐bidentate and one O‐monodentate terminal triphenylacetate ligand. (III)·2MeOH possesses one intramolecular and four intermolecular hydrogen bonds, forming a [(III)·2MeOH]2 dimer with two bridging methanol molecules. 相似文献
84.
Dmitrii O. Kharchenko Vasyl O. Kharchenko Anna I. Bashtova 《The European Physical Journal B - Condensed Matter and Complex Systems》2016,89(5):123
We study properties of voids growth dynamics in a stochastic system of point defects insolids under nonequilibrium conditions (sustained irradiation). It is shown thatfluctuations of defect production rate (external noise) increase the critical void radiuscomparing to a deterministic system. An automodel regime of void size growth in astochastic system is studied in detail. Considering a homogeneous system, it is found thatexternal noise does not change the universality of the void size distribution function;the mean void size evolves according to classical nucleation theory. The noise increasesthe mean void size and spreads the void size distribution. Studying dynamics of spatiallyextended systems it was shown that vacancies remaining in a matrix phase are able toorganize into vacancy enriched domains due to an instability caused by an elastic latticedeformation. It is shown that dynamics of voids growth is defined by void sinks strengthwith void size growth exponent varying from 1/3 up to 1/2. 相似文献
85.
Goodrich CP Kirmizialtin S Huyghues-Despointes BM Zhu A Scholtz JM Makarov DE Movileanu L 《The journal of physical chemistry. B》2007,111(13):3332-3335
We used single-channel electrical recordings and Langevin molecular dynamics simulations to explore the electrophoretic translocation of various beta-hairpin peptides across the staphylococcal alpha-hemolysin (alphaHL) protein pore at single-molecule resolution. The beta-hairpin peptides, which varied in their folding properties, corresponded to the C terminal residues of the B1 domain of protein G. The translocation time was strongly dependent on the electric force and was correlated with the folding features of the beta-hairpin peptides. Highly unfolded peptides entered the pore in an extended conformation, resulting in fast single-file translocation events. In contrast, the translocation of the folded beta-hairpin peptides occurred more slowly. In this case, the beta-hairpin peptides traversed the alphaHL pore in a misfolded or fully folded conformation. This study demonstrates that the interaction between a polypeptide and a beta-barrel protein pore is dependent on the folding features of the polypeptide. 相似文献
86.
Motivated by recent experiments, in which knots have been tied in individual biopolymer molecules, we use Langevin dynamics simulations to study the diffusion of a knot along a tensioned polymer chain. We find that the dependence of the knot diffusion coefficient on the tension can be non-monotonic. This behavior can be explained by the model, in which the motion of the knot involves cooperative displacement of a local knot region. At low tension, the overall viscous drag force that acts on the knot region is proportional to the number N of monomers that participate in the knot, which decreases as the tension is increased, leading to faster diffusion. At high tension the knot becomes tight and its dynamics are dominated by the chain's internal friction, which increases with the increasing tension, thereby slowing down the knot diffusion. This model is further supported by the observation that the knot diffusion coefficient measured across a set of different knot types is inversely proportional to N. We propose that the lack of tension dependence of the knot diffusion coefficients measured in recent experiments is due to the fact that the experimental values of the tension are close to the turnover between the high- and low-force regimes. 相似文献
87.
When triisobutylaluminum (AliBu(3)) is added to solutions containing methylaluminoxane (MAO) and rac-[Me(2)Si(ind)(2)ZrCl(2)] (ind: indenyl) in C(6)D(6), NMR spectra show that methyl-bridged mixed-alkylaluminum dimers Al(mu-Me)(2)Me(4-x)iBu(x) predominate. These dimers react with MAO under partial transfer of isobutyl groups and induce a conversion of the initially prevailing cationic trimethylaluminum adduct rac-[Me(2)Si(ind)(2)Zr(mu-Me)(2)AlMe(2) (+)] to rac-[Me(2)Si(ind)(2)Zr(mu-Me)(2)AlMeiBu(+)] and rac-[Me(2)Si(ind)(2)Zr(mu-Me)(2)AliBu(2) (+)]. These species are unstable and release isobutene under formation of zirconocene hydrides. 相似文献
88.
Dmitrii P. Krut’ko Roman S. Kirsanov Maxim V. Borzov Andrei V. Churakov 《Journal of organometallic chemistry》2007,692(7):1465-1471
Half-sandwich [η5:η1-κN-C5Me4CH2-(2-C5H4N)]MCl3 (M = Ti (4), Zr (5)) and sandwich [η5-C5Me4CH2-(2-C5H4N)][η5-C5Me5]ZrCl2 (6) ring-peralkylated complexes have been prepared and characterized. Evidence of the intramolecular coordination of the side-chain pyridyl group both in 4 and 5 in solutions is provided by NMR spectroscopy data. Crystal structure of an adduct 5-py with one molecule of pyridine has been established by X-ray diffraction analysis. 相似文献
89.
Dmitrii S. Yufit Judith A. K. Howard 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(3):o141-o143
The crystal structures of (1R,1′S)‐2′,2′‐dichloro‐N‐(1‐phenylethyl)cyclopropane‐1′‐carboxamide, C12H13Cl2NO, (I), and (1R,1′R)‐2′,2′‐difluoro‐N‐(1‐phenylethyl)cyclopropane‐1′‐carboxamide, C12H13F2NO, (II), have been determined. Both crystals contain two independent molecules with different conformations of the phenylethyl groups. In the crystals of both compounds, the molecules are linked together by N—H⃛O hydrogen bonds, thus forming chains in the a direction. 相似文献
90.