Thermoanalytical, magnetic and structural study of Co(II) complexes with substituted salicylaldehydes and neocuproine

In this study, simultaneous TG/DTG-DTA technique was used for two cobalt(II) complexes with neocuproine(neoc) and the anion of a substituted salicylaldehyde ligand (X-salo) (X?=?3-OCH₃, or 5-CH₃) with the general formula [Co(X-salo)₂(neoc)], to determine their thermal degradation in inert atmosphere, which was found to be a multi-step decomposition related to the release of the ligand molecules. The solid material at 1300?°C (verified with PXRD) was a mixture of carbonaceous metal cobalt. Evolved gas analysis by coupled TG-MS verified the elimination of a formaldehyde molecule in the first decomposition stage, initially proposed by the percentage mass loss data. By single-crystal X-ray diffraction analysis an octahedral geometry of the complex [Co(3-OCH₃-salo)₂(neoc)] was found. The variable temperature magnetic susceptibility measurements showed a paramagnetic nature of the complexes, in accordance with their molecular structure. Finally, for the determination of the activation energy (E) two different methods (the isoconversional methods of Ozawa, Flynn and Wall (OFW) and Friedman) were used comparatively.     

Photoelastic determination of stresses in multiple-pin connectors

The design, fabrication, and testing of photoelastic models of double-lap, multiple-pin connectors are discussed. Interest is in the stresses in the inner laps. These stresses are determined by constructing models with photoelastic inner laps and transparent-acrylic outer laps. The connectors have two pins, in tandem, parallel to the load direction. A photoelastic-isotropic point is shown to permit the evaluation of load sharing between the two pins. A numerical scheme, utilizing the isochromatic- and isoclinic-photoelastic data and a finite-difference representation of the planestress equilibrium equations, is used to compute the stresses around the two pins. Representative stress distributions and stress-concentration factors are shown.     

Strings in Kerr–Newman Black Holes

We study the evolution of strings in the equatorial plane of a Kerr–Newman black hole. Writing the equations of motion and the constraints resulting from Hamilton's principle, three classes of exact solutions are presented, for a closed string, encircling the black hole. They all depend on two arbitrary integration functions and two constants. A process for extracting energy is examined for the case of one of the three families of solutions. This is the analogue of the Penrose process for the case of a particle.     

Synthesis and characterization of novel "3 + 2" oxorhenium complexes, ReO[SNO][NN

The present paper deals with the synthesis and structural characterization of novel neutral oxorhenium(V) complexes of the general formula ReO[SNO][NN]. The simultaneous action of the tridentate SNO ligand, N-(2-mercaptoacetyl)glycine (1), and the bidentate NN ligand, N-phenylpyridine-2-aldimine (2), on ReOCl3(PPh3)2 leads to the formation of two isomers 4a and 4b of the general formula ReO[SNO][NN], as a result of the different orientations of the NN ligand. In both cases, the SNO donor atoms of the tridentate ligand occupy the three positions in the equatorial plane of the distorted octahedron, whereas the oxo group is always directed toward one of the apical positions. In the first isomer, 4a, the imino nitrogen of the NN ligand occupies the fourth equatorial position and the pyridine type nitrogen is directed trans to the oxo group, while in the second isomer, 4b, the imino nitrogen of the NN ligand occupies the apical position trans to the oxo group and the pyridine type nitrogen completes the equatorial plane of the distorted octahedron. The [SNO][NN] mixed-ligand system was applied in the synthesis of the oxorhenium complex 5 in which the 1-(2-methoxyphenyl)piperazine moiety, a fragment of the true 5-HT1A antagonist WAY 100635, has been incorporated in the NN bidentate ligand (NN is N-{3-[4-(2-methoxyphenyl)piperazin-1-yl]propyl}pyridine-2-aldimine). In this case, high-performance liquid chromatography and NMR showed the existence of one isomer, 5, in which the pyridine nitrogen is trans to the oxo core, as demonstrated by crystal structure analysis.     

Synthesis of 4(3H)-quinazolinones from derivatives of methyl 2-isothiocyanatobenzoate

Ethyl N-(2-methoxycarbonylphenyl)thiocarbamate ( 2), N -(2-ethoxycarbonylphenyl)-4-methoxythiobenz-amide ( 3b ), and 2-(4-methoxyphenyl)-4H-3,1-benzothiazin-4-one ( 4a ), react with nucleophilic reagents containing at least one primary amino group to yield a variety of 2-substituted and 2,4-disubstituted 4(3H)quinazolinones, as well as some tricyclic and tetracyclic products.     

van der Waals interaction between internal aqueous droplets and the external aqueous phase in double emulsions

A mathematical model for analyzing the van der Waals interaction between the internal aqueous droplets (W(1)) and the external aqueous phase (W(2)) of double emulsions has been established. The effects of Hamaker constants of the materials forming the system, especially those of the two different adsorbed surfactant layers with uniform density (A(1) and A(2)), on the van der Waals interaction were investigated. The overall van der Waals interaction across the oil film is a combined result of four individual parts, that is, W(1)-W(2), A(1)-A(2), W(1)-A(1), and A(2)-W(2) van der Waals interaction, and it may be either attractive or repulsive depending on many factors. It was found that the overall van der Waals interaction is dominated by the W(1)-W(2) interaction at large separation distances between the W(1)/O and O/W(2) interfaces, while it is mostly determined by the A(1)-A(2) interaction when the two interfaces are extremely close. Specifically, in the cases when the value of the Hamaker constant of the oil phase is intermediate between those of W(1) and W(2) and there is a thick oil film separating the two interfaces, a weak repulsive overall van der Waals interaction will prevail. If the Hamaker constant of the oil phase is intermediate between those of A(1) and A(2) and the two interfaces are very close, the overall van der Waals interaction will be dominated by the strong repulsive A(1)-A(2) interaction. The repulsive van der Waals interaction at such cases helps stabilize the double emulsions.     

On the Geometry of the Berry-Robbins Approach to Spin-Statistics

Within a geometric and algebraic framework, the structures which are related to the spin-statistics connection are discussed. A comparison with the Berry-Robbins approach is made. The underlying geometric structure constitutes an additional support for this approach. In our work, a geometric approach to quantum indistinguishability is introduced which allows the treatment of singlevaluedness of wave functions in a global, model independent way.     

Investigations of the adulteration of extra virgin olive oils with seed oils using their weak chemiluminescence

A weak chemiluminescence (CL) emission was observed in commercial Greek extra virgin olive oils (Knossos, Spitiko, Ananias, Altis, Minerva, Xenia) and in refined seed oils such as sunflower oils (Marata, Sanola, Sun, Mana, Sol, Minerva) as well as in corn oils (Flora, Minerva, Marata Sun and Sol) with potassium superoxide in the aprotic solvent dimethoxyethylene.On measuring the CL of mixtures of extra virgin olive oils with the cheaper refined seed oils, calibrations were produced which can be used for the determination of the adulteration of olive oils with seed oils down to 3%. Furthermore, depending on the kind of oils, “low” authenticity-CL-factors for olive oils (0.8-2.15 μmol l⁻¹ gallic acid) and “high” for seed oils (4.5-11.2 μmol l⁻¹ gallic acid) were calculated.