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1.
Sanchez-sanz M; Blyth MG 《The Quarterly Journal of Mechanics and Applied Mathematics》2007,60(2):125-138
Unsteady, axisymmetric stagnation flow about a circular cylinderis examined when the far-field flow is a periodic function oftime with a fixed time average and an oscillatory part of prescribedamplitude and frequency. Solutions are computed for arbitraryvalues of the Reynolds number, quantifying the effects of surfacecurvature, and a frequency parameter based on the period ofthe far-field flow. It is found that solutions remain regularand periodic provided that the far-field amplitude lies belowa critical value. Above this value, solutions terminate in afinite-time singularity. The blow-up time is delayed by increasingthe curvature of the surface. These results are corroboratedby asymptotic predictions valid in the limits of small and largeamplitude and frequency. For large Reynolds number, the problemreduces to the two-dimensional stagnation-point flow againsta plane wall studied by previous authors. 相似文献
2.
Koridze A. A. Kuklin S. A. Sheloumov A. M. Kondrashov M. V. Dolgushin F. M. Ezernitskaya M. G. Petrovskii P. V. Vorontsov E. V. 《Russian Chemical Bulletin》2003,52(12):2757-2759
Russian Chemical Bulletin - 相似文献
3.
M. G. Ezernitskaya B. V. Lokshin T. Yu. Orlova V. N. Setkina V. I. Shilnikov S. Nunziante Cesaro 《Russian Chemical Bulletin》1994,43(11):1841-1845
FTIR spectra have been studied for staircase cyclopentadienyl complexes containing two or three metal carbonyl fragments bound by the metal-carbon bond Cp(CO)2Fe-CpmMn(CO)3 (1), Cp(CO)2Fe-CpmFe(CO)2CH2Ph (2), Cp(CO)2Fe-Cpm(CO)2Fe-CpmMn(CO)3 (3), Cp(CO)2Mo-Cpm(CO)2Fe-CpmMn(CO)3 (4), Cp(CO)3W-Cpm(CO)2Fe-CpmMn(CO)3 (5), Cp(CO)2Fe-Cpm(CO)2Fe-BmCr(CO)3 (6), Cr(CO)3Bm-CpmFe(CO)2CH2Ph (7), where Cp = 5-C5H5, Cpm = 15-C5H4, Bm = 16-C6H5. Temperature-dependent FTIR spectra were measured inn-pentane solutions over a wide temperature range and in the low-temperature solid matrices of argon and nitrogen. Rotamers, formed due to rotation about the metal-carbon -bond, were found in solutions and matrices. A molecular mechanics calculation of1 proved the possibility of such rotation.Translated fromIzyestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1952–1956, November, 1994.The authors are grateful to the Russian Foundation for Basic Research (project code No 93-03-18592) and to the International Science Foundation (project code No MEQ000). 相似文献
4.
T. Yu. Orlova Yu. S. Nekrasov P. V. Petrovskii M. G. Ezernitskaya T. V. Magdesieva S. V. Milovanov K. P. Butin 《Russian Chemical Bulletin》1998,47(9):1785-1788
The behavior of binuclear “ladder” type complexes FpL, where Fp=Cp(CO)2Fe, L=p-MeC6H4Cr(CO)3 (4), CH2C6H5Cr(CO)3 (5), andp-FpC6H4Cr(CO)3 (6), under conditions of metallation was studied. Unlike compounds5 and6, the σ-bound ligand L in compound4 migrates from the iron atom to the cyclopentadienyl ring to give complexes Me(CO)2FeC5H4−C6H4(p-Me)Cr(CO)3. The electrochemical reduction potentials of the complexes4–6 and the rearrangement products were measured. The migration activity of L is determined by the ease of reductive cleavage
of the Fe−L bond and the susceptibility of the system to undergo intramolecular electron transfer from the Cp ligand to the
aromatic ring.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1832–1835, September, 1998. 相似文献
5.
Koridze A. A. Kuklin S. A. Petrovskii P. V. Dolgushin F. M. Ezernitskaya M. G. 《Russian Chemical Bulletin》2002,51(2):350-353
The Os3(-H)2(CO)7(-C6H4){3-Ph2PCH2P(C6H4)Ph} complex, which was isolated from the products of thermolysis of Os3(CO)10(-dppm) (dppm is Ph2PCH2PPh2) in toluene, was characterized by X-ray diffraction analysis. Protonation of the resulting complex with trifluoroacetic acid afforded the cationic complex [Os3(-H)3(CO)7(-C6H4){3-Ph2PCH2P(C6H4)Ph}]+. 相似文献
6.
Koridze A. A. Zdanovich V. I. Lagunova V. Yu. Petukhova I. I. Dolgushin F. M. Starikova Z. A. Ezernitskaya M. G. Petrovskii P. V. 《Russian Chemical Bulletin》2002,51(5):876-886
The thermal reaction of Ru3(CO)10(-Ph2PCH2PPh2) (1) with enyne PhCH=CHCCPh afforded the trinuclear ruthenium clusters Ru3(CO)6{3-P(Ph)CH2PPh2}{3-C(Ph)=CHCC(Ph)(1,2-C6H4)C(=0)} (2), Ru3(-H)(CO)5{3-P(Ph)CH2PPh2}{3-C(Ph)=CHCC(Ph)(1,2-C6H4)C(—0)} (3), and Ru3(CO)6(-CO){3-P(Ph)CH2PPh2}{3-C(C=CPh2)CH=C(H)Ph} (4) and also two isomers of Ru3(CO)5(-CO)(-Ph2PCH2PPh2){3-C4Ph2(CH=CHPh)2} (5a and 5b). Clusters 2, 3, and 4 were characterized by IR spectroscopy, 1H and 31P NMR spectroscopy, and X-ray diffraction analysis. The reaction of complex 1 with enyne FcCH=CHCCFc gave rise to the Ru3(CO)6{3-P(Ph)CH2PPh2}{3-C(Fc)=CHCC(Fc)(1,2-C6H4)C(=0)} (6) and Ru3(-H)(CO)5{3-P(Ph)CH2PPh2}{3-C(Fc)=CHCC(Fc)(1,2-C6H4)C(—0)} (7) clusters. According to the spectral data, the latter compounds are isostructural to complexes 2 and 3, respectively. 相似文献
7.
S -nitrosothiols have many biological activities and may act as nitric oxide (NO) carriers and donors, prolonging NO half-life in vivo. In spite of their great potential as therapeutic agents, most S -nitrosothiols are too unstable to isolate. We have shown that the S -nitroso adduct of N -acetylcysteine (SNAC) can be synthesized directly in aqueous and polyethylene glycol (PEG) 400 matrix by using a reactive gaseous (NO/O2 ) mixture. Spectral monitoring of the S–N bond cleavage showed that SNAC, synthesized by this method, is relatively stable in nonbuf-fered aqueous solution at 25°C in the dark and that its stability is greatly increased in PEG matrix, resulting in a 28-fold decrease in its initial rate of thermal decomposition. Irradiation with UV light (λ= 333 nm) accelerated the rate of decomposition of SNAC to NO in both matrices, indicating that SNAC may find use for the photogeneration of NO. The quantum yield for SNAC decomposition decreased from 0.65 ± 0.15 in aqueous solution to 0.047 ± 0.005 in PEG 400 matrix. This increased stability in PEG matrix was assigned to a cage effect promoted by the PEG microenvironment that increases the rate of geminated radical pair recombination in the homolytic S–N bond cleavage process. This effect allowed for the storage of SNAC in PEG at −20°C in the dark for more than 10 weeks with negligible decomposition. Such stabilization may represent a viable option for the synthesis, storage and handling of S -nitrosothiol solutions for biomedical applications. 相似文献
8.
A. V. Polukeev S. A. Kuklin P. V. Petrovskii A. S. Peregudov F. M. Dolgushin M. G. Ezernitskaya A. A. Koridze 《Russian Chemical Bulletin》2010,59(4):745-749
Iridium pincer complexes [C6H3-2,6-(OPBut
2)2]Ir(H)Cl (10) and [4-EtOOCC6H2-2,6-(OPBut
2)2]Ir(H)Cl (11) react with protic acids undergoing metallation of one of the tert-butyl groups to form double cyclometallated products [4-R-C6H2-2-(OPBut
2)-6-(OP(But)CMe2CH2)]IrCl (12, R = H; 13, R = COOEt), which are stable in air. Complex 12 reacts with CO and ButNC giving the corresponding 18-electron complexes [C6H3-2-(OP-But
2)-6-(OP(But)CMe2CH2)]Ir(L)Cl (14, L = CO; 15, L = CNBut). The structure of compound 14 was established by X-ray diffraction analysis. 相似文献
9.
10.
T. Yu. Orlova Yu. S. Nekrasov P. V. Petrovskii M. G. Ezernitskaya Z. A. Starikova O. L. Lependina 《Russian Chemical Bulletin》2008,57(1):63-67
The metallation of the η5-C5H5(CO)2Fe-η1,η5-C5H4Mn(CO)3 complex with BunLi (THF, ?78 °C) followed by the treatment of the lithium derivative with Ph2PCl afforded the η5-Ph2PC5H4(CO)2Fe-η1,η5-C5H4Mn(CO)3 complex. The reaction of the latter with η5-C5H5(CO)3WCl in the presence of Me3NO produced the trinuclear complex η5-C5H5Cl(CO)2W-η1,η5-(Ph2P)C5H4(CO)2Fe-η1,η5-C5H4Mn(CO)3. The structure of the latter complex was established by IR, UV, and 1H and 31P NMR spectroscopy and X-ray diffraction. The reaction of MeSiCl3 with three equivalents of LiC5H4(CO)2Fe-η1,η5-C5H4Mn(CO)2PPh3 gave the hexanuclear complex MeSi[C5H4(CO)2Fe-η1,η5-C5H4Mn(CO)2PPh3]3. 相似文献