Thermochemical approach to solid-state decomposition reactions against the background of traditional theories

The novel thermochemical and traditional Arrhenius approaches to solid-state decomposition reactions have been evaluated from the standpoints of the number and the validity of the assumptions introduced in the theories, and achievements obtained over the last decade in the frameworks of both approaches. As it follows from the analysis, in both respects, the thermochemical approach is preferable. The so-called ‘controversial’ problem of the use of thermodynamic concepts and thermochemical data for the quantitative evaluation of decomposition kinetics in the thermochemical approach has also been discussed.     

The image adaptive method for solder paste 3D measurement system

The extensive application of Surface Mount Technology (SMT) requires various measurement methods to evaluate the circuit board. The solder paste 3D measurement system utilizing laser light projecting on the printed circuit board (PCB) surface is one of the critical methods. The local oversaturation, arising from the non-consistent reflectivity of the PCB surface, will lead to inaccurate measurement. The paper reports a novel optical image adaptive method of remedying the local oversaturation for solder paste measurement. The liquid crystal on silicon (LCoS) and image sensor (CCD or CMOS) are combined as the high dynamic range image (HDRI) acquisition system. The significant characteristic of the new method is that the image after adjustment is captured by specially designed HDRI acquisition system programmed by the LCoS mask. The formation of the LCoS mask, depending on a HDRI combined with the image fusion algorithm, is based on separating the laser light from the local oversaturated region. Experimental results demonstrate that the method can significantly improve the accuracy for the solder paste 3D measurement system with local oversaturation.     

Critical Reappraisal of Methods for Measuring Urine Saturation with Calcium Salts

Background: Metabolic and physicochemical evaluation is recommended to manage the condition of patients with nephrolithiasis. The estimation of the saturation state (β values) is often included in the diagnostic work-up, and it is preferably performed through calculations. The free concentrations of constituent ions are estimated by considering the main ionic soluble complexes. It is contended that this approach is liable to an overestimation of β values because some complexes may be overlooked. A recent report found that β values could be significantly lowered upon the addition of new and so far neglected complexes, [Ca(PO₄)Cit]⁴⁻ and [Ca₂H₂(PO₄)₂]. The aim of this work was to assess whether these complexes can be relevant to explaining the chemistry of urine. Methods: The Ca–phosphate–citrate aqueous system was investigated by potentiometric titrations. The stability constants of the parent binary complexes [Cacit]⁻ and [CaPO₄]⁻, and the coordination tendency of PO₄³⁻ toward [Ca(cit)]⁻ to form the ternary complex, were estimated. β_CaOx and β_CaHPO4 were then calculated on 5 natural urines by chemical models, including or not including the [CaPO₄]⁻ and [Ca(PO₄)cit]⁴⁻ species. Results: Species distribution diagrams show that the [Ca(PO₄)cit]⁴⁻ species was only noticeable at pH > 8.5 and below 10% of the total calcium. β values estimated on natural urine were slightly lowered by the formation of [CaPO₄]⁻ species, whereas [Ca(PO₄)cit]⁴⁻ results were irrelevant. Conclusions: While [CaPO₄]⁻ species have an impact on saturation levels at higher pHs, the existence of ternary complex and of the dimer is rejected.