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131.
Effects of shear deformation on vibration of doublewalled carbon nanotubes embedded in an elastic medium 总被引:1,自引:0,他引:1
Metin Aydogdu 《Archive of Applied Mechanics (Ingenieur Archiv)》2008,78(9):711-723
In this study, free vibration of simply supported multi-walled carbon nanotubes (CNTs) embedded in an elastic medium was investigated
by using the generalized shear deformation-beam theory (GSDBT). The effects of surrounding elastic medium, which is considered
as a spring, defined by the Winkler model, and van der Waals forces from adjacent nanotubes are taken into account. Third-order
shear deformation (TOSD) theory is used to study free vibration of a multi-walled carbon nanotube embedded in an elastic medium.
Unlike Timoshenko beam theory, TOSD theory satisfies zero traction boundary conditions on the upper and lower surface of the
structures, so there is no need to use a shear correction factor. Free vibration frequencies and amplitude ratios were obtained
for various sides to thickness ratios and elastic medium effects and results are compared with previous studies. The results
showed that significant difference exist between TOSD and Euler beam theory. It is also interesting to note that, although
frequency parameter is increasing by increasing stiffness of embedded medium, amplitude ratios are insensitive to stiffness
of embedded elastic medium.
Dedicated to the honorable memory of my beloved mother Fatma Aydogdu (Romania,1933-Tekirdag, August 7, 2007) 相似文献
132.
133.
Attempts to induce the catalytic dehydrocoupling of the phosphine-gallane adduct Cy2PH.GaH3 (Cy=cyclohexyl) (1) by treatment with ca. 5 mol% of either the Rh(I) complex [{Rh(mu-Cl)(1,5-cod)}2] (cod=cyclooctadiene) or the Rh(0) species Rh/Al2O3 and [Oct4N]Cl-stabilized colloidal Rh led to catalytic P-Ga bond cleavage to generate the phosphine, H2, and Ga metal. Interestingly, subsequent treatment of the reaction mixtures with Me2NH.BH3 failed to lead to the formation of [Me2N-BH2]2 via Rh-catalyzed dehydrocoupling, which suggested that catalyst deactivation was taking place. Poisoning studies involving the treatment of the active Rh(0) catalyst with Cy2PH, PMe3, or GaH3.OEt2 showed that deactivation indeed occurred as the dehydrocoupling of Me2NH.BH3 either dramatically decreased in rate or did not take place at all. The X-ray photoelectron spectroscopy analysis of colloidal Rh(0) that had been treated with Cy2PH and PMe3 confirmed the presence of phosphorus on the catalyst surface in each case, consistent with catalyst poisoning via phosphine ligation. A mechanism for the Rh-catalyzed P-Ga bond cleavage reaction of 1 and Me3P.GaH3 (2) is proposed and involves the initial reaction of Ga-H bonds with the Rh colloid surface, which weakens and ultimately breaks the P-Ga bond. The reasonable nature of this mechanism is supported by a model reaction between the zerovalent group 9 complex Co2(CO)8 and 2 which afforded Me3P.Ga[Co(CO)4]3 (3). Consistent with the elongated and thus weakened P-Ga bond in 3, solutions of this species in Et2O subsequently form the known complex [(Me3P)Co(CO)3]2 (4) and Ga metal after 4 h at 25 degrees C. 相似文献
134.
Mehmet Karakus Dr. Yıldırım Aydogdu Omer Celik Veysel Kuzucu Semra Ide Evamarie Hey‐Hawkins Prof. Dr. 《无机化学与普通化学杂志》2007,633(3):405-410
Ferrocenyldithiodiphosphetane [FcPS(μ‐S)]2 [Fc = Fe(η5‐C5H4)(η5‐C5H5)] reacts with the aminoethanol derivatives 1‐ethyl‐3‐pyrrolidinol and 2‐(piperazin‐1‐yl)ethanol to give the zwitterionic (O‐ethylammonium)ferrocenyldithiophosphonates ( 2 ) and ( 3 ), which were fully characterized by elemental analysis, IR and NMR spectroscopy and mass spectrometry. The optical and electrical properties of 2 and 3 as well as those of the previously reported [FcP(S)S(OC2H4NHEt2)] ( 1 ) were studied. A molecular structure determination of 1 is also reported. 相似文献
135.
Particle deposition in turbulent flow depends on diffusional migrations and gravitational forces. However, the rate of this process occurs differently in vertical and horizontal flows. Therefore, some new expressions were suggested for these two types of flow in this article. Moreover, impact of the coalescence and break‐up phenomena on deposition was investigated. Suggested equations were compared with the experimental data taken from the literature and a good agreement was recorded. 相似文献