Thermal behaviour of CuS (covellite) obtained from copper–thiosulfate system

Thermal behaviour of CuS (covellite) obtained from the Cu(CH₃COO)₂·H₂O and Na₂S₂O₃·5H₂O system, working at different molar ratio (1:6 and 1:4) in presence/absence of NH₄VO₃, was studied. It was established that the presence of vanadium in the system induces a densification of CuS nodules, but do not change the hexagonal CuS structure. It has an important influence in thermal behaviour of copper sulfide CuS obtained also. The morphological characteristics of CuS play an important role in the thermal stability and the stoichiometry of the thermal decompositions. Also, the possibility to obtain copper sulfides with greater cooper content was investigated.     

Influence of the synthesis parameters on the thermal behavior of some ZnO–starch composites

Ten ZnO–starch composites were synthesized using a simple precipitation methodology. The IR spectroscopy and XRD investigations reveal the presence of amorphous starch and crystalline ZnO. The obtained composites present a spherical morphology, 5–8 spheres being interconnected into aggregates. The thermal analysis demonstrates that starch decomposition and ZnO thermally induced nucleation and crystal growth depending on the synthesis parameters such as starch processing (dissolution or gelatinization), reaction temperature (80, 90, and 100 °C), reaction time (15 min or 6 h), and applied treatments (heating or ultrasound irradiation).     

Fructose-derived hydrochar: combustion thermochemistry and kinetics assessments

Journal of Thermal Analysis and Calorimetry - The combustion behavior of fructose-derived hydrochar was investigated using a kinetic evaluation protocol that brings about novel elements related to...     

Steric blocking as a tool to control molecular film geometry at a metal surface

The application of steric blocking in surface science is exemplified by the control of surface patterns through the selective methylation of pentacenetetrone. Pentacenetetrones interact (with one another) on Cu(111) via intermolecular hydrogen bonding involving the carbonyl oxygen and the adjacent hydrogen atoms. Steric blocking of the intermolecular interaction by the successive insertion of inert methyl groups at terminal locations transforms a dense molecular pattern first into isolated double rows and eventually into single rows in a highly predictable fashion. Density functional theory modeling reveals the underlying energetics.     

Iterative solution of inconsistent systems of linear inequalities

In 1980 S.P. Han proposed a finitely terminating (in exact arithmetic) algorithm for solving an inconsistent system of linear inequalities in a least squares sense. This algorithm uses a singular value decomposition of a submatrix of the problem matrix on each iteration, making it impractical for all but only smaller problems. In this paper we show that a modification of Han's algorithm allows us to introduce an iterative approximation to the singular value decomposition solution. (© 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Thermal behavior of the coordination compound [Co(urea)6](NO3)2

The coordination compound [Co(urea)₆](NO₃)₂ was synthesized and physico-chemically characterized. The thermal decomposition carried out in dynamic air and inert atmosphere under non-isothermal conditions has been investigated by means of combined thermogravimetry/mass spectrometry, X-ray diffraction, IR and UV-VIS spectroscopy as well as magnetic measurements. The course of the thermal decomposition starts with two-phase transitions (melting and a O_h→T_dconfiguration change of the Co²⁺ ion) and continues with seven mass loss steps. According to the thermogravimetric and magnetic investigations a dimeric compound, [Co(biuret)(NCO)]₂(NO₃)₂, is assumed to arise. Up ~250°C, an oxohydroxide nitrate intermediate is formed and a gradual oxidation of the Co²⁺ ions is observed. At 550°C, Co₃O₄ with mean crystallite sizes of ~150 Ĺ is identified. This revised version was published online in August 2006 with corrections to the Cover Date.     

Thermal behaviour of some Al(III)-Mg(II) polynuclear coordination compounds with polycarboxylic acid anions as ligands,precursors of aluminates

A TG, DTG and DTA study of three polynuclear coordination compounds,containing Al(III)-Mg(II), namely (NH₄)₄[Al₂Mg(C₄O₅H₄)₄(OH)₄]?2H₂O,(NH₄)₄[MgAl₂(C₄H₄O₆)₄(OH)₄]?3H₂Oand (NH₄)₂[Al₂Mg(C₆O₇H₁₁)₅(OH)₅]?3H₂O,has been reported together with the associated thermal decomposition mechanismrationalized in terms of intermediate products. As decomposition end-product,magnesium-aluminum spinel is obtained. The values of MgAl₂O₄mean crystallite size depend on the anionic ligand contained by the precursorcompound, varying in the order: malate (143 Å) ligand contained by theprecursor compound, varying in the order: malate (143 Å)