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Journal of Thermal Analysis and Calorimetry
Authors: F. Mallet, S. Petit, S. Lafont, P. Billot, D. Lemarchand, and G. Coquerel

Abstract  

Solid-solid transformations between solvates of pharmaceutical compounds are investigated under various conditions. In the case of Roxithromycin, it is shown that starting from single crystals of the acetonitrile solvate, a transformation towards the monohydrate occurs according to a cooperative mechanism. This smooth exchange of solvent probably involves a transport of matter within channels, and the comparison of crystal structures is consistent with the persistence of the main features of the 3D lattice. By contrast, starting from the DMSO solvate of Dexamethasone acetate, the transformation towards the sesquihydrated form, induced by the immersion of the DMSO solvate in water, is fully destructive and reconstructive. This occurs far-from-equilibrium and is therefore controlled by kinetic factors. The existence of an intermediate liquid phase within the particle is postulated to account for the appearance of whisker-like crystals growing first on high-energy sites of the former particle. An extended analysis of these transformations between solvates shows that they could be classified according to rules previously proposed in the case of desolvation mechanisms.

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Journal of Thermal Analysis and Calorimetry
Authors: V. Balek, V. Zeleňák, T. Mitsuhashi, S. Bakardjieva, J. Šubrt, and H. Haneda

Abstract  

Results of emanation thermal analysis (ETA) characterizing microstructure changes of SiC based materials during heat treatment in argon are demonstrated. This method made it possible to reveal fine changes of the texture of SiC nano-sized powders, SiC micro-sized powders and SiC whiskers under in situconditions of the heating. ETA curves can serve as fingerprints of the respective samples.

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Young adult male Wistar rats were treated, by gavage, with 80 or 320 mg/kg Pb 2+ (lead acetate), 0.4 or 1.6 mg/kg Hg 2+ (mercuric chloride) or both by combining the lower doses. For combination with alcohol, ethanol was added to the rats’ drinking water in 5 v/v %. After 12 weeks of treatment, electrophysiological recording was made from the somatosensory cortex in urethane anaesthesia. Evoked potentials obtained by stimulation of the whiskers were recorded. Both metals, and alcohol alone, increased significantly the latency of the evoked response. Alcohol seemed to abolish the effect of Pb, but not of Hg. Fatigue, calculated form the response amplitude, was increased by Pb and Hg treatment and this effect of Hg was reduced by ethanol. Evoked activity and its dynamic characteristics were sensitive to the complex neurotoxic effect induced in the rats and can provide a basis for developing functional markers.

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Abstract  

Solid dispersions of the antidiabetic drug glibenclamide and polyethylene glycol 4000 (macrogol 4000) were prepared by the melting method in order to increase the solubility of this poorly water-soluble compound. The temperature/composition phase diagram of the components was analyzed by hot-stage microscopy and differential scanning calorimetry, showing a monotectic. Polarized light hot stage microscopy and X-ray-powder diffraction confirmed, that glibenclamide is mainly present in a non-crystalline state after melting and solidifying of a 10% (w/w) mixture, which results in an enhanced solubility compared to physical mixtures. The solubility and dissolution rate of the drug increases clearly with decreasing drug/polymer ratio. Moreover, it was observed for the first time that a drug could crystallize as whiskers at the surface of aged solid dispersion particles. Besides relaxation phenomena, this crystallization mechanism may be responsible for a deterioration of liberation properties and bioavailability of solid dispersion based drug products with increasing storage time.

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Graphs , Arch. Math. , 68 ( 1997 ), 124 – 128 . [4] F rancisco , C. A. and H à , H. T. , Whiskers and Sequentially Cohen–Macaulay Graphs , J. Combin. Theory Ser. A

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with unique properties compared to inorganic materials. The main advantages of cellulose is its renewable nature, high-specific strength and modulus (the elastic modulus for cellulose whiskers is about 145 GPa, while that of glass fibers averages about

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elevated temperatures. As one-dimensional functional materials, whiskers have attracted great attention because they exhibit unique structure and various excellent physical, chemical, and mechanical properties, which are distinctive from those of

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Raj, S. K., Snehi, S. K., Khan, M. S., Tiwari, A. K. and Rao, G. P. (2010b): Detection of Ageratum enation virus from cat’s whiskers ( Cleome gynandra L.) with leaf curl symptoms in India. J. General Plant Pathology 76, 292

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Journal of Thermal Analysis and Calorimetry
Authors: Lingli Peng, Xiangyu Xu, Zhi Lv, Jiaqing Song, Mingyuan He, Qian Wang, Lijun Yan, Yang Li, and Zhaofei Li

], nanosheets [ 16 ], nanobelts [ 15 ], nanofibers [ 17 , 18 ], and whiskers [ 19 ] had been obtained by a variety of methods in the past a few years. The concept of surfactant templating has been introduced into the synthesis of most nanostructured Al 2 O 3

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