Probing amorphous and crystalline pharmaceuticals systems using NMR

The Ή and '3C solution-state NMR spectra of the three studied drug molecules (indomethacin, nifedipine and carbamazepine) were fully assigned. This led to the characterisation and assignment of the '3C CPMAS SSNMR spectra of the stable polymorphic forms of these molecules. The signal for the с-СІ carbon of indomethacin has been studied as a function of applied magnetic field, and the observed bandshapes have been simulated. A T(_1)(^H)and T(_1p)(^H) study was undertaken on the crystalline materials, as well as on the quench-cooled amorphous and PVP/drug co-melts. This was done in order to fulfill the aim of this research, i.e. to understand the difference in stability of the amorphous compounds and also to investigate the effect of the presence of PVP on the stability and mobility of the drug. It was shown that, under the conditions of the experiments, amorphous indomethacin did not recrystallise until 110 c, whilst in the case of nifedipine and carbamazepine the recrystallisation occurred at 70 c and 75 c respectively. It was also shown that in the case of the co-melts a transition occurs consistently between 65 c and 85 c for the three materials and this seems to be due to the Tg of the co-melts. The comparison of the T(_1)(^H)and T(_1p)(^H) data for the different states showed that amorphisation increased the mobility of the sample, this being more pronounced for carbamazepine and nifedipine than for indomethacin, and also that the co-melts were more stable and slightly more mobile than the amorphous compounds. The comparison of the relaxation data between the pure compounds showed that amorphous indomethacin was more stable than the other two amorphous drugs as slope changes occurred for the latter at a temperature below Tg, whilst this happens at or around Tg for amorphous indomethacin

The transition from hydrostatic to greater than hydrostatic fluid pressure in presently active continental hydrothermal systems in crystalline rock

Fluid flow at hydrostatic pressure (Ph) is relatively common through fractures in silicic and in mafic crystalline rocks where temperatures are less than about 350–370°C. In contrast, pore‐fluid pressure (Pf) > Ph has been encountered at the bottom of 3 geothermal exploration wells that attained temperatures >370°C (at Larderello, Italy, at Nesjavellir, Iceland, and at The Geysers, California). Chemical sealing by deposition of minerals in veins appears to have allowed the development of the high Pf encountered in the above wells. The upper limit for the magnitude of Pf that can be attained is controlled by either the onset of shear fracturing (where differential stress is relatively high) that reopens clogged veins, or the hydraulic opening of new or old fractures (at relatively low values of differential stress). The brittle‐plastic transition for silicic rocks can occur at temperatures as high as 370–400°C in tectonically active regions. In regions where high‐temperature geothermal systems develop and persist, it appears that either strain rates commonly are in the range 10−12 to 10−13, or that silicic rocks in the shallow crust generally behave rheologically more like wet quartz diorite than wet Westerly granite

regeneration

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Boris Arvatov, théoricien du productivisme

Maria Zalambani. Boris Arvatov, theoretician of productivism. Boris Arvatov is the most significant theorist of productivist art. The present article goes through the main stages of the evolution of his thought. Starting from his first theoretical formulations of a proletarian art (which resounds with echoes of Bogdanov's theory about Proletkurt), through his numerous contributions to the journals of the 1920s until the publication of his most significant works of 1926 and 1930, the author has taken into consideration the whole arvatovian corpus. She has studied its inner evolution in order to place it within the political and cultural debate of the period, concerning the genesis (and the necessity) of a productivist art. Arvatov's thought focuses on three main points: 1. work as a free and creative process; 2. identification of work, art and life; 3. the development of an art which is work and invades all human life, starting from time spent working, overflowing into free time and finally pervading private life. To carry out his plan, Arvatov puts his trusts in the rules of the scientific organization of work ( NOT) and creates the figure of the artist-engineer, supreme fusion of art and technique. Productivist art thus arises as an image and likeness of the working process in factories, perpetuates its norms and rules: vanguard art changes into a kind of perpetual working process.Maria Zalambani. Boris Arvatov, théoricien du productivisme. Boris Arvatov est le plus important théoricien de l'art productiviste. Cet article suit les étapes de l'évolution de sa pensée. L'auteur considère toute la production ď Arvatov, depuis ses premières formulations théoriques sur un art prolétaire (qui font écho à la théorie du Proletkul't de Bogdanov) jusqu'à la publication de ses œuvres les plus importantes de la période 1926- 1930, en passant par ses nombreuses contributions aux revues des années 1920. On étudie l'évolution interne de cette production afin de la situer dans le débat politique et culturel de l'époque sur la genèse et la nécessité d'un art productiviste. La pensée d'Arvatov est centrée sur trois points principaux : 1 ) le travail en tant que processus libre de création ; 2) l'identification entre le travail, l'art et la vie ; 3) le développement d'un art qui est travail et qui envahit entièrement la vie humaine, par le temps passé à travailler, l'empiétement sur le temps libre, et enfin, par l'extension dans la vie privée. Pour mener à bien son projet, Arvatov se fie aux règles de l'organisation scientifique du travail (NOT) et crée un personnage fusionnant l'art et la technique, l'artiste-ingénieur. Ainsi, l'art productiviste apparaît comme l'image fidèle du travail en usine dont il perpétue les normes et les valeurs : l'art d'avant-garde se mue en une sorte de travail perpétuel.Zalambani Maria, Foumier Jeannine. Boris Arvatov, théoricien du productivisme. In: Cahiers du monde russe : Russie, Empire russe, Union soviétique, États indépendants, vol. 40, n°3, Juillet-septembre 1999. pp. 415-446