Differential Scanning Calorimetry combined with Fourier transform infrared spectroscopy, was applied to the study of a number of fulvic and humic acids extracted from soils, peat, river and seawater. The thermal patterns obtained were related to the nature and origin of samples. The low-temperature endotherms were attributed to dehydration and loss of peripheral polysaccharide chains. The endotherm at 250°C observed for soil FA was ascribed to partial decarboxylation of more labile surface COOH groups, whereas the high-temperature exotherms at about 500°C were related to the degree of polycondensation of the aromatic network of the humic molecules.
A critical thermodynamic analysis of differential thermal calorimetry is reported herein to gain further insight into the
phenomena leading to the reported differences between kinetic parameters extracted from isothermal DSC methods and those from
dynamic DSC methods. The sources have been identified for the variations observed in the total heat of reaction as a function
of the heating rate in dynamic DSC experiments. The analysis clearly indicates that these variations are, in fact, to be anticipated.
The relationships necessary for extracting kinetic data from both isothermal and dynamic experiments are derived rigorously
by resorting to classical thermodynamics.
Authors:K. Cieśla, E. Svensson, and A.-C. Eliasson
Differential scanning calorimetry was applied in studies of the effect of gamma irradiation on the potato starch and wheat
flour. Essential differences were noticed between endothermal effects observed in concentrated suspensions of the initial
and irradiated potato starch and wheat flour heated at a rate of 2.5C min-1, while only small differences were noticed between gelatinization thermal effects recorded for ca. 20% suspensions of the
initial and irradiated potato starch samples heated at a rate 10C min-1. Moreover, in the case of wheat flour, a decrease of decomposition temperature of the amylose-lipid complex was concluded.
Authors:K. Ngai, S. Capaccioli, M. Shahin Thayyil, and N. Shinyashiki
In several current important problems in different areas of soft matter physics, controversy persists in interpreting the
molecular dynamics observed by various spectroscopies including dielectric relaxation, light scattering, nuclear magnetic
resonance, and neutron scattering. Outstanding examples include: (1) relaxation of water in aqueous mixtures, in molecular
sieves and silica-gel nanopores, and in hydration shell of proteins; and (2) dynamics of each component in binary miscible
polymer blends, in mixtures of an amorphous polymer with a small molecular glassformer, and in binary mixtures of two small
molecular glassformers. We show the applications of calorimetry to these problems have enhanced our understanding of the dynamics
and eliminated the controversies.
Authors:L. Mécs, Z. Aigner, G. Sohár, Piroska Szabó-Révész, and K. Tóth
The purpose of this study was to further characterize the altered metabolism spondylolisthesis that promotes disease progression.
Degenerative human cartilage (intervertebral disc, facet joint and vertebral end-plate) was obtained during 15 posterior lumbar
spine interbody fusion procedures performed at the University of Szeged. The thermal properties of samples were determined
by differential scanning calorimetry (Mettler-Toledo DSC 821e). Greatest change in the enthalpy was observed in the intervertebral disc samples: −1600.78 J g−1. Denaturation caused by heating in the normal human hyaline cartilage needed −1493.31 J g−1 energy. Characterization of the altered metabolism that promotes disease progression should lead to future treatment options.
Authors:Vikram Kestens, Guy Auclair, Katarzyna Drozdzewska, Andrea Held, Gert Roebben, and Thomas Linsinger
In this study, the use of differential scanning calorimetry (DSC) is demonstrated as a powerful technique that can provide
accurate thermodynamic property values of environmental contaminants such as polycyclic aromatic hydrocarbons (PAHs). In total,
47 high purity PAH certified reference materials were selected and analysed by DSC. Their onset melting temperature, enthalpy
of fusion and eutectic purity were calculated from the obtained melting endotherms. In addition, the entropy of fusion, which
was calculated from the onset melting temperature and enthalpy of fusion, is presented. All measurements were evaluated in
a metrologically rigorous manner, including measurement uncertainties.
An isothermal titration calorimetry (ITC) method
to measure the heat effects evolving from the binding between cation exchanger
Amberlite IRP 69 and the cationic drug substances propranolol hydrochloride
(PROP), metoprolol tartarate (METO), acebutolol hydrochloride (ACEB) and chlorpheniramine
maleate (CPR) has been developed. The method gives repeatable results with
an error about 5% for the beta-blockers PROP, METO and ACEB, and about 10%
for the antihistamine CPR.
The calculation of the thermodynamic parameters enthalpy
and Gibbs free energy change (ΔGbind)
show significant differences between the different drug substances.
Authors:G. Baert, S. Hoste, G. De Schutter, and N. De Belie
Four paste mixtures with varying replacement level of the cement content by fly ash have been studied. Due to fly ash, the
acceleration period decreased and a third hydration peak was noticed with isothermal calorimetry. The total heat after 7 days
increased with increasing fly ash content. From 1 to 7 days, thermogravimetry showed a higher chemically bound water and Ca(OH)2-content for the pastes with fly ash. Between 7 and 14 days the calcium hydroxide started to be depleted due to the pozzolanic
reaction. A unique relation was found between calcium hydroxide and total heat development.
Authors:J. Zhu, H. Jin, D. Dong, D. Qiang, and F. Ma
The glass formation and devitrification of GaF3-based glasses were studied by differential scanning calorimetry. A comparison of various simple quantitative methods to assess
the level of stability of multicomponent fluoride glass systems is presented. Most of these methods are based on critical
temperatures. In this paper a new parameter kb(T) is added to the stability criteria. The stability of several GaF3-based glasses were experimentally evaluated and correlated with the activation energies of crystallization via this new kinetic
criterion and compared with those evaluated by other criteria.
Authors:Chung-Hwei Su, Sheng-Hung Wu, Sun-Ju Shen, Gong-Yih Shiue, Yih-Weng Wang, and Chi-Min Shu
Volatile organic compounds (VOCs) are the main factors involved in pollution control and global warming in industrialized
nations. Various treatment methods involving incineration, adsorption, etc., were employed to reduce VOCs concentration. Various
absorbents, such as activated carbon, zeolite, silica gel or alumina, and so on were broadly used to adsorb VOCs in various
industrial applications. Differential scanning calorimetry (DSC) was handled to analyze the thermal characteristics of absorbents.
Typically, a scanning electron microscope (SEM) has been used to evaluate the structure variation of absorbents under high
temperature situations. In view of pollution control and loss prevention, versatility and analysis of recycled adsorbents
are necessary and useful for various industrial applications.