A compendium of phase change enthalpies published in 2010 is updated to include the period 1880–2015. Phase change enthalpies including fusion, vaporization, and sublimation enthalpies are included for organic, organometallic, and a few inorganic compounds. Part 1 of this compendium includes organic compounds from C1 to C10. Part 2 of this compendium, to be published separately, will include organic and organometallic compounds from C11 to C192. Sufficient data are presently available to permit thermodynamic cycles to be constructed as an independent means of evaluating the reliability of the data. Temperature adjustments of phase change enthalpies from the temperature of measurement to the standard reference temperature, T = 298.15 K, and a protocol for doing so are briefly discussed.

Phase Transition Enthalpy Measurements of Organic and Organometallic Compounds. Sublimation, Vaporization and Fusion Enthalpies From 1880 to 2015. Part 1. C1-C10

Commercial antioxidants and thermal stability evaluations

Synthesis of Fe/Fe3C nanoparticles encapsulated in nitrogen-doped carbon with single-source molecular precursor for the oxygen reduction reaction

Thermal decomposition of citric acid is one of the most common synthesis methods for fluorescent carbon dots; the reaction pathway is, however, quite complex and the details are still far from being understood. For instance, several intermediates form during the process and they also give rise to fluorescent species. In the present work, the formation of fluorescent C-dots from citric acid has been studied as a function of reaction time by coupling infrared analysis, X-ray photoelectron spectroscopy, liquid chromatography/mass spectroscopy (LC/MS) with the change of the optical properties, absorption and emission. The reaction intermediates, which have been identified at different stages, produce two main emissive species, in the green and blue, as also indicated by the decay time analysis. C-dots formed from the intermediates have also been synthesised by thermal decomposition, which gave an emission maximum around 450 nm. The citric acid C-dots in water show short temporal stability, but their functionalisation with 3-aminopropyltriethoxysilane reduces the quenching. The understanding of the citric acid thermal decomposition reaction is expected to improve the control and reproducibility of C-dots synthesis.

Carbon Dots from Citric Acid and its Intermediates Formed by Thermal Decomposition

The aim of this study was to produce a powdered probiotic passion fruit juice, in order to develop a new non-dairy probiotic beverage. For this purpose, passion fruit juice added with Bifidobacterium animalis ssp. lactis BB-12 was microencapsulated by spray drying using maltodextrin and/or inulin as encapsulating agents. The microcapsules obtained were characterized in relation to their morphological, physical and thermogravimetric properties after spray drying. The viability of probiotic microorganism, as well as the powders’ moisture content, water activity, solubility and color were evaluated throughout 30 days of storage at 25 °C and 4 °C. The storage at 4 °C resulted in a better maintenance of probiotic viability throughout the storage period. During storage at 25 °C, the sample made only with maltodextrin showed loss of viability of the bifidobacteria while the sample made with inulin offered better protection to the encapsulated bacteria. The different carrier agents affected the morphology and the particle size of the microcapsules. All the probiotic juice powders had similar flow characteristics. The use of maltodextrin resulted in higher values for moisture content and water activity. Throughout storage, an increase in moisture content and water activity was noted for all the samples. All the powders showed high solubility indexes. An increase in luminosity and a concurrent reduction in b* values throughout storage was noted for all the juice powder formulations at both temperatures, but more markedly at 25 °C. The results of the thermal analysis showed that both encapsulating agents improved the stability of the passion fruit juice.

Development and physico-chemical characterization of microencapsulated bifidobacteria in passion fruit juice: A functional non-dairy product for probiotic delivery

Thermal decomposition of citric acid, trans- and cis-aconitic acid has been studied using the TG-MS, TG-FTIR and DSC techniques. The measurements were carried out in an argon atmosphere over a temperature range of 293–673 K. The influence of the acid structures and configurational geometry on stability of the transition products and pathways of thermal transformations of the studied compounds studied is discussed.

https://link.springer.com/content/pdf/10.1007%2Fs10973-010-1015-2.pdf

G. Nowak-Wiczk

Papers

Thermal behaviour of citric acid and isomeric aconitic acids