Authors:H. Tanojo, J. Bouwstra, H. Junginger, and H. Boddé
The thermal behaviour of human stratum corneum (SC) with various hydration levels was studied using differential thermal analysis DSC within the temperature range of –130 to 120°C. SC containing 20% water, resembling the intact condition, shows thermal transitions at around –20°C (representing water in skin), –10, 40, 70°C (representing skin lipids), 85°C (representing protein-associated lipids) and 100°C (representing skin protein). Dehydration of SC causes the transitions at –20 and 100°C to be invisible. Lipid extraction followed by dehydration eliminates all transitions. Further hydration produces a transition of water at around 0°C with a huge change in enthalpy. The perturbation effects of penetration enhancers fatty acids (FA) and propylene glycol (PG) were studied using DTA on SC after pretreatment with PG alone and FA/PG. The application of PG alone shifted the transitions at 70 and 85°C to lower temperatures. Additionally, the application to dehydrated stratum corneum removes the transitions at –10°C. Saturated fatty acids, e.g. nonanoic and decanoic acids, exert barely noticeable effects on the thermal behaviour of SC suggesting that they easily mix with the skin lipids. Thermal analysis also revealed that the cis-9- and 13-isomers of octadecenoic acid (monounsaturated fatty acids) form a separate domain containing mostly the pure fatty acids within the SC lipids and suppress the lipid transitions at 70/80°C. Polyunsaturated fatty acids linoleic and -linolenic acids — form separate domains but do not completely suppress the SC lipid transitions at 70/80°C as monounsaturated acids do. This study suggests different ways of perturbation by various fatty acids.
simultaneous thermogravimetry and differentialthermalanalysis (TG–DTA) systems. The experiments were carried out with ~10 mg, crude oil-limestone sample (15 wt% crude oil in the mixture) at 10 °C/min heating rate. Air flow rate through the sample pan was kept
Authors:S. Wacharine, D. Hellali, H. Zamali, J. Rogez, and M. Jemal
and differentialthermalanalysis technique. The device was already described in details in previous works [ 38 , 39 , 53 ]. It consists of an Adamel-Lhomargyam furnace connected to a Setaram PRT 540 C regulator-programmer of temperature, that allows
Authors:Simone Pereira da Silva Ribeiro, Luciana Rocha de Moura Estevão, Csaba Novák, and Regina Sandra Veiga Nascimento
interplanar distance on the synergistic effect with an intumescent formulation is evaluated by thermogravimetric analysis (TG) and differentialthermalanalysis (DTA), in addition to heating microscopy. Although the aforementioned techniques are not designed
Authors:George G. G. de Oliveira, Humberto G. Ferraz, Patrícia Severino, and Eliana B. Souto
The aim of this article was to analyse the phase transition and dehydration processes of nevirapine using DSC and thermogravimetry differentialthermalanalysis (TG-DTA).
Materials and methods
Nevirapine was provided by the
Authors:Ronaldo S. Nunes, Gilbert Bannach, José M. Luiz, Flávio J. Caires, Claudio T. Carvalho, and Massao Ionashiro
Th(IV) and Al(III), with EDTA [ 2 , 3 ].
The works reported the synthesis and characterization of the compounds by means of thermogravimetry (TG), derivative thermogravimetry (DTG), differentialthermalanalysis (DTA), X-ray powder
reported to show that there is a reduction in Ca(OH) 2 content [ 14 ]. Little is known however, in terms of the effect thereafter and that no full investigation of the system have been found using both thermogravimetric and differentialthermalanalysis
The effect of vibration grinding on the DTA curves of montmorillonite isolated from the most important locality of bentonite
in the Slovak Republic (Jelšovy potok, Middle Slovakia) was studied in the temperature range 20–1500°C. Interpretation is
offered for 6 endothermic and 3 exothermic peaks. vibration grinding modified the course of dehydration of the mineral, suppresses
the “dehydroxylation’ peak at 700°C, enables the crystallization of high-temperature quartz, cristobalite and cordierite at
lower temperatures in comparison with unground natural montmorillonite. Vibration griding slows down the crystallization of
mullite which—unlike quartz, cristobalite and cordierite—does not belong to high-temperature phases of Cheto-montmorillonite.
The order in which these high-temperature phases occur is not influenced by vibration grinding.