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121.
122.
Konidaris KF Polyzou CD Kostakis GE Tasiopoulos AJ Roubeau O Teat SJ Manessi-Zoupa E Powell AK Perlepes SP 《Dalton transactions (Cambridge, England : 2003)》2012,41(10):2862-2865
Metal-ion mediated reactions of 2-pyridinealdoxime and hexafluorophosphate lead to Zn(II) complexes containing picolinic acid, picolinamide and monofluorophosphate (-2) as ligands. 相似文献
123.
124.
Spyros S. Magliveras 《Mathematica Slovaca》2009,59(1):19-38
This paper addresses questions related to the existence and construction of large sets of t-(v, k, λ) designs. It contains material from my talk in the Combinatorial Designs Conference in honor of Alex Rosa’s 70th birthday,
which took place in beautiful Bratislava, in July, 2007. Naturally, only a small number of “highlight” topics could be included,
and for the most part these involve the use of symmetry, that is, it is assumed that the particular designs or large sets of designs, are invariant under a prescribed group of automorphisms.
I present almost no proofs, but give references so that the reader can find a much wider repertory of theorems and constructions
in the literature. For completeness, I include the statement of a few recursive constructions. The latter are extremely important
on their own right, and deserve extensive attention elsewhere. I hope the reader becomes interested in the intriguing open
problems posed at the end of the paper and succeeds in solving some of them.
(Communicated by Peter Horák) 相似文献
125.
Daniel Vasilikis Spyros A. Karamanos 《International Journal of Solids and Structures》2012,49(23-24):3432-3446
The paper focuses on wrinkling of lined pipes (sometimes referred to as clad pipes) under bending loading, where a corrosion-resistant thin-walled liner is fitted inside a carbon–steel outer pipe. The problem is solved numerically, using nonlinear finite elements to simulate liner pipe deformation and its interaction with the outer pipe. Stresses and strains are monitored throughout the deformation stage, detecting possible detachment of the liner from the outer pipe and the formation of wrinkles. The wrinkling behavior of elastic and elastic–plastic (steel) lined pipes under bending is examined. The results indicate that the lateral confinement of the liner pipe due to the deformable outer pipe and its interaction with the outer pipe has a decisive influence on the wrinkling behavior of the lined pipe. It is also shown that the behavior is characterized by a first bifurcation in a uniform wrinkling pattern, followed by a secondary bifurcation. The values of corresponding buckling curvature are determined and comparison with available experimental results is conducted in terms of wrinkle height development and the corresponding buckling wavelength. The results of the present research can be used for safer design of lined pipes in pipeline applications. 相似文献
126.
We introduce certain spherically symmetric singular Ricci solitons and study their stability under the Ricci flow from a dynamical PDE point of view. The solitons in question exist for all dimensions n + 1 ≥ 3, and all have a point singularity where the curvature blows up; their evolution under the Ricci flow is in sharp contrast to the evolution of their smooth counterparts. In particular, the family of diffeomorphisms associated with the Ricci flow “pushes away” from the singularity causing the evolving soliton to open up immediately becoming an incomplete (but non-singular) metric. The main objective of this paper is to study the local-in time stability of this dynamical evolution, under spherically symmetric perturbations of the singular initial metric. We prove a local well-posedness result for the Ricci flow in suitably weighted Sobolev spaces, which in particular implies that the “opening up” of the singularity persists for the perturbations as well. 相似文献
127.
Boudalis AK Sanakis Y Clemente-Juan JM Donnadieu B Nastopoulos V Mari A Coppel Y Tuchagues JP Perlepes SP 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(8):2514-2526
Complexes [Fe9(X)2(O2CMe)8{(2‐py)2CO2}4] (X?=OH? ( 1 ), N3? ( 2 ), and NCO? ( 3 )) have been prepared by a route previously employed for the synthesis of analogous Co9 and Ni9 complexes, involving hydroxide substitution by pseudohalides (N3?, NCO?). As indicated by DC magnetic susceptibility measurements, this substitution induced higher ferromagnetic couplings in complexes 2 and 3 , leading to higher ground spin states compared to that of 1 . Variable‐field experiments have shown that the ground state is not well isolated from excited states, as a result of which it cannot be unambiguously determined. AC susceptometry has revealed out‐of‐phase signals, which suggests that these complexes exhibit a slow relaxation of magnetization that follows Arrhenius behavior, as observed in single‐molecule magnets, with energy barriers of 41 K for 2 (τ0=3.4×10?12 s) and 44 K for 3 (τ0=2.0×10?11 s). Slow magnetic relaxation has also been observed by zero‐field 57Fe Mössbauer spectroscopy. Characteristic integer‐spin electron paramagnetic resonance (EPR) signals have been observed at X‐band for 1 , whereas 2 and 3 were found to be EPR‐silent at this frequency. 1H NMR spectrometry in CD3CN has shown that complexes 1 – 3 are stable in solution. 相似文献
128.
Patrina Paraskevopoulou Nikos Psaroudakis Spyros Koinis Pericles Stavropoulos Konstantinos Mertis 《Journal of molecular catalysis. A, Chemical》2005,240(1-2):27-32
The system (nBu4N)ReO4 5/PhIO/CH2Cl2, T = 298 K catalyses effectively and with total selectivity the anaerobic oxidation of a range of primary substituted benzyl alcohols (o-, m-, p-X-C6H4-CH2OH, X = H, Me, MeO, Cl, NO2, CF3) to the corresponding aldehydes; in contrast, it is unreactive towards secondary benzyl and aliphatic (primary and secondary) alcohols. This may prove of interest in synthetic organic transformations, when several alcoholic functionalities are present in the same molecule. 相似文献
129.
Georgios A. Heropoulos Spyros Georgakopoulos Barry R. Steele 《Tetrahedron letters》2005,46(14):2469-2473
Sterically demanding nitroaromatic compounds have been prepared and reduced to their corresponding amines with high intensity ultrasound using hydrazine in the presence of a Raney nickel catalyst. These reactions were dependent on catalyst quality, solvent and ultrasonic amplitude and, in comparison to their silent reactions, proceeded much faster and afforded higher yields. 相似文献
130.
A. Spyros Photis Dais R. H. Marchessault 《Journal of Polymer Science.Polymer Physics》1995,33(3):367-378
Variable-temperature 13C NMR spin-lattice relaxation times (T1) and Nuclear Overhauser Enhancements (NOE) at two magnetic fields have been used to study the dynamics of the amorphous part of a semicrystalline sample (33% of crystallinity) of poly(β-hydroxyoctanoate) (PHO). The interpretation of the relaxation data of the backbone carbons was made by employing a number of motional models. Among these, the DLM model offered the best interpretation of the relaxation data in terms of conformational transitions and librational motions of the backbone C? H vectors, and proved to be superior to unimodal distribution functions. The interpretation of temperature- and frequency-dependent T1 and NOE data of the carbon nuclei in the n-pentyl side chain was made by employing a newly developed composite spectral density function for multiple internal C? C bond rotations of restricted amplitude and chain segmental motion. The temperature dependence of the linewidths of the various protonated carbon resonances of PHO has been discussed in terms of the semicrystalline character of this polymer. © 1995 John Wiley & Sons, Inc. 相似文献