Optimal bounds from below of the critical load for elastic solids subject to uniaxial compression

In the recent papers [1,2] we studied a new procedure based on the Korn inequality for determining sufficient conditions for the Hadamard stability, aimed at determining optimal lower bound estimates for the critical load in bifurcation problems. Here, we discuss the effectiveness of our approach for the classical representative problem of uniaxial compression of a Mooney-Rivlin circular cylinder. We find that our lower bound estimate is effective and advantageous for applications, since it is easily implementable in numerical codes. (© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Study of new resonances at high excitation energy by the 120Sn(p,t)118Sn reaction at 35 MeV

The ¹²⁰Sn(p,t)¹¹⁸Sn reaction was investigated at 35 MeV incident energy. The ¹¹⁸Sn excitation energy spectrum was reconstructed up to about 16 MeV. Preliminary results show the presence of a broad resonance at high excitation energy, compatible with the predicted population of the Giant Pairing Vibration (GPV).     

Weak alkali and alkaline earth metal complexes of low molecular weight ligands in aqueous solution

This work is aimed at reviewing the chemical literature dealing with thermodynamic aspects of the weak complex formation (species with log K values less than about 3) between alkali and alkaline earth metal ions with low molecular weight inorganic and organic ligands in aqueous solution. The following ligands (up to hexavalent anions) were examined in detail: (i) hydroxide, chloride, sulfate, carbonate and phosphate as inorganic, and (ii) carboxylates, amines, amino acids, complexones and nucleotides as organic ligands. The paper also identifies the main reasons responsible for the dispersion of the stability data on ion pairs in the literature. When possible, the trend of stability for the different metal ions interacting with the same ligand will be considered to find predictive interaction relationships. Since the stability of weak alkali and alkaline earth metal complexes are mainly due to electrostatic interaction, simple empirical relationships were obtained between log K and the charge of the anionic ligand. The interest for alkali and alkaline earth cations rises since they are used in study of basic science as components of the supporting electrolyte and are widely diffused in natural fluids. Some examples of application of this science were presented too, to show the role of weak complex formation in the modelling process of natural systems.     

A meta effect in nonphotochemical processes: the homolytic chemistry of m-methoxyphenol

The m-methoxy group is normally electron-withdrawing (EW), sigma(m) = +0.12, sigma(m+) = +0.05. The strong EW activity of a phenoxyl radical's O* atom causes the m-methoxy group to become electron-donating (ED), sigma(m)(+) = -0.14. In valence bond terms, this can be ascribed to the nonclassical resonance structures 1c-e. Although it has long been known that m-methoxy is ED in photoexcited states, it has now been found to be ED for homolytic O-H bond breaking in ground-state 3-methoxyphenol.     

Sequestering ability of polycarboxylic ligands towards dioxouranium(VI)

In this paper we report a comparison on the sequestering ability of some polycarboxylic ligands towards dioxouranium(VI) (UO(2)(2+), uranyl). Ligands taken into account are mono- (acetate), di- (oxalate, malonate, succinate and azelate), tri- (1,2,3-propanetricarboxylate) and hexa-carboxylate (1,2,3,4,5,6-benzenehexacarboxylate). The sequestering ability of polycarboxylic ligands towards UO(2)(2+) was quantified by a new approach expressed by means of a sigmoid Boltzman type equation and of a empirical parameters (pL(50)) which defines the amount of ligand necessary to sequester 50% of the total UO(2)(2+) concentration. A fairly linear correlation was obtained between pL(50) or log K(110) (log K(110) refers to the equilibrium: UO(2)(2+)+L(z-)=UO(2)L((2-z)); L=generic ligand) and the polyanion charges. In order to complete the picture, a tetra-carboxylate ligand (1,2,3,4-butanetetracarboxylate) was studied in NaCl aqueous solutions at 0相似文献   

Kinetic and thermodynamic parameters for the equilibrium reactions of phenols with the dpph. radical

The kinetics and energetics of the reversible reaction of phenols with the dpph. radical have been studied; steric shielding of the divalent N by the o-NO2 in dpph. seems to be the main cause of the entropic barriers of this reaction.