A non local density functional calculation of the diamagnetic susceptibilities and other electronic properties of noble gases and closed-shell ions

The non local weighted-density approximation (WDA) to the exchange-correlation potentialV _xc (r) is used to compute electron densities, ionization potentials and electron affinities of several atoms and ions. Especial care is taken in calculating and discussing 〈r ²〉 in noble gas atoms. Good results are obtained for all those quantities, but it is critical that the WDA is applied in such a way that it preserves the correct larger behaviour ofV _xc (r). A comparison of the calculated electron density with that of the Hartree-Fock method shows the effects of coulomb correlation. The density rearrangements upon the introduction of correlation agree qualitatively with the results of Configuration-Interaction calculations     

Study of the 1,4-dihydroxyanthraquinone-yttrium(III) complex in solution and in the solid state

The photometric and fluorometric characteristics of the complex formed by 1,4-dihydroxyanthraquinone with Y(III) in 20–80% water-ethanol solution are described by the study of several variables. The stoichiometry and stability constant of the complex in the solution are 1:1 and log K = 4.57, respectively. The 1,4-dihydroxyanthraquinone-Y(III) solid complex has been prepared and studied by infrared spectroscopy and thermal analysis. The thermal behavior of this compound has been studied using thermogravimetry and differential scanning calorimetry techniques and the residue verified by X-ray diffraction.     

Spontaneous ring transformation of a 5-azido-1,2,3-thiadiazole

The reaction of 4-carbethoxy-5-chloro-1,2,3-thiadiazole ($\text{1}$) with sodium azide results in the formation of ethyl α-thiatriazolyldiazoacetate ($\text{3}$) instead of the corresponding azide ($\text{2}$). Two plausible mechanisms for this new rearrangement are formulated.     

Thermal properties of tetrahydroperparine derivatives

The thermal behaviour of tetrahydroperparine (THP) and its derivatives with various acids has been investigated. The acid is liberated from the formate derivative basically in two steps, while the other aliphatic acids are released quantitatively before the thermal decomposition of the THP molecule. The thermoanalytical curves, electrical conductivity data measured in the molten phase, and infrared spectra prove that while part of the formic acid is hydrogen-bonded the other part is bound ionically in the molecule. It may be assumed that the marked biological activity of the compound can be explained by this difference in the nature of the bonds.     

Electrospun cellulose acetate fibers: effect of solvent system on morphology and fiber diameter

This paper reports an investigation of the effects of solvent system, solution concentration, and applied electrostatic field strength (EFS) on the morphological appearance and/or size of as-spun cellulose acetate (CA) products. The single-solvent systems were acetone, chloroform, N,N -dimethylformamide (DMF), dichloromethane (DCM), methanol (MeOH), formic acid, and pyridine. The mixed-solvent systems were acetone–DMAc, chloroform–MeOH, and DCM–MeOH. Chloroform, DMF, DCM, MeOH, formic acid, and pyridine were able to dissolve CA, forming clear solutions (at 5% w/v), but electrospinning of these solutions produced mainly discrete beads. In contrast, electrospinning of the solution of CA in acetone produced short and beaded fibers. At the same solution concentration of 5% (w/v) electrospinning of the CA solutions was improved by addition of MeOH to either chloroform or DCM. For all the solvent systems investigated smooth fibers were obtained from 16% (w/v) CA solutions in 1:1, 2:1, and 3:1 (v/v) acetone–DMAc, 14–20% (w/v) CA solutions in 2:1 (v/v) acetone–DMAc, and 8–12% (w/v) CA solutions in 4:1 (v/v) DCM–MeOH. For the as-spun fibers from CA solutions in acetone–DMAc the average diameter ranged between 0.14 and 0.37 μm whereas for the fibers from solutions in DCM–MeOH it ranged between 0.48 and 1.58 μm. After submersion in distilled water for 24 h the as-spun CA fibers swelled appreciably (i.e. from 620 to 1110%) but the physical integrity of the fibrous structure remained intact.     

Studies on metal — protein interactions: Inter-comparison among various approaches

Binding ability of mercury, thallium, lead and bismuth with Erythrina variegata seed protein have been investigated using tracer packet technique. Due to the lack of standard methods, inter-comparisons have been made among three different approaches, like trichloroacetic acid (TCA) precipitation, isoelectric precipitation and dialysis of protein after incubation with the metals. Good agreement was observed for all the cases except that of lead.     

Infrared laser ablation study of pressed soil pellets with inductively coupled plasma atomic emission spectrometry

Potential of infrared laser ablation (LA) coupled with ICP-AES as a technique suitable for the determination of trace elements (Zn, Cu, Ni, Cr, and V) in agricultural soils was studied. Operating parameters such as laser beam energy, laser beam focusing with respect to the sample surface, and velocity of the sample translation in the plane perpendicular to the laser beam were optimized. Soil samples were mixed with powdered Ag as a binder, and an internal standard (GeO(2)), and pressed into pellets. Calibration samples were prepared by adding known amounts of oxides of elements of interest into soils of known elemental composition and then processed in the same way as the analyzed samples. Calibration curves were found to be linear at least up to several hundreds of mg kg(-1) for the elements of interest. The elemental contents obtained by using LA-ICP-AES were compared with those obtained by analysis using wet chemistry followed by ICP-AES with pneumatic nebulization (PN). The results were in good agreement. Accuracy was also tested using certified reference soils with a bias not exceeding 10% relative.     

Identification of the main by-products of the developing agent N-hydroxyethyl-N-ethyl-3-methyl-p-phenylenediamine in photographic effluents by liquid chromatography/mass spectrometry

N-Hydroxyethyl-N-ethyl-3-methyl-p-phenylenediamine (CD(4)) is commonly used as a developing agent in color photographic processes. The main by-products formed in developer baths used in the process were separated and identified by liquid chromatography/electron ionization mass spectrometry (LC/EI-MS) and liquid chromatography/atmospheric pressure ionization mass spectrometry (LC/API-MS). A number of side reactions, in addition to the main reactions involved in the developing process, were found to occur. Such side reactions involved in the formation of CD(4) by-products included oxidation, hydroxylation, sulfonation and the formation of coupling products. A reaction pathway for the degradation of CD(4) based on the nature of the by-products identified is proposed and discussed.     

Primary Transformation Rate Measurements Through Differential Scanning Calorimetry

The primary crystallization of molten alloy systems at high undercooling is studied by a precise quantitative analysis of the calorimetric signal obtained during the transformation in terms of the reaction rate under isothermal and continuous heating regimes. It is shown that, under specific conditions, namely, stoechiometric primary precipitates, generalized relationships for the crystallization enthalpy and the reaction rate may be obtained.     

Diagramme de phases du systeme binaire LiNO3-NaNO3

Phase diagram of the binary system LiNO₃-NaNO₃ has been obtained by using direct and differential thermal analysis between 323 and 623 K. This system is characterized by an eutectic plateau at 467 K. The eutectic point is at 0.465 mole NaNO₃. A peritectic appears at 550 K. There is no miscibility in the solid state. These findings associated with some other thermodynamic results have been used to calculate the activities of the constituents along the liquids curve and the excess thermodynamic functions at 618 K. The constituents seem not to have a symmetrical influence on the thermodynamic quantities.