940 resultados para Initial stages
Resumo:
NMR studies were conducted with the aim of determining the diastereoisomeric ratio of a commercially supplied sample of mesoridazine (MES) and to compare the results with a freshly synthesised sample of MES. The results indicated that the commercially supplied MES consisted almost entirely of one diastereoisomeric pair, which was in agreement with previous findings reported by Eap et al. (J Chromatogr 669:271-279, 1995). The synthesised sample of MES was analysed by NMR in two stages: 1) as the initial product isolated as the free base from the direct synthesis, and 2) as the free base isolated from the crystallised besylate salt of the synthetic product. The NMR results show that the initial synthetic product consisted of two equal pairs of diastereoisomers. The diastereoisomeric pairs were further separated by the addition of the chiral shift reagent (R)-(-)-N-(3,5 dinitrobenzoyl)-alpha-benzylamine to reveal equal quantities of all four enantiomers, clearly observed at the methyl sulfoxide proton peak of the NMR scan. The sample obtained from the crystallisation of MES besylate, however, indicated a significant difference, with a diastereoisomeric ratio of 75:25. The results suggest that MES besylate undergoes preferential crystallisation of one pair of diastereoisomers, with the other pair remaining in solution. (C) 2004 Wiley-Liss, Inc.
Resumo:
The origins of Sephardic press date back to the mid-20th century, when the influence of the Western world spread across the Sephardim communities of the East. The content of these newspapers was diverse: pieces of general interest, but also scientific, literary and humorous works, with various political orientations. These papers were published in different languages, writing styles and alphabets. Those to be analysed here, however, were published in aljamiado Judeo-Spanish: three papers from Smyrna and one from Salonica. Throughout this work we will focus on the different obstacles and difficulties the editors and publishers of this Ottoman Sephardic press had to face to bring their publications to light.
Resumo:
This study investigates the use of co-melt fluidised bed granulation for the agglomeration of model pharmaceutical powders, namely, lactose mono-hydrate, PEG 10000, poly-vinyl pyrolidone and ibuprofen as a model drug. Granulation within the co-melt system was found to follow a nucleationâ??steady growthâ??coating regime profile. Using high molecular weight PEG binder, the granulation mechanism and thus the extent of granulation was found to be significantly influenced by binder viscosity. The compression properties of the granulate within the hot fluidised bed were correlated using a novel high temperature experimental procedure. It was found that the fracture stress and fractural modulus of the materials under hot processing conditions were orders of magnitude lower than those measured under ambient conditions. A range of particle velocities within the granulator were considered based on theoretical models. After an initial period of nucleation, the Stokes deformation number analysis indicated that only velocities within the high shear region of the fluidised bed were sufficient to promote significant granule deformation and therefore, coalescence. The data also indicated that larger granules de-fluidised preventing agglomeration by coalescence. Furthermore, experimental data indicated that dissipation of the viscous molten binder to the surface was the most important factor in the latter stages of the granulation process. From a pharmaceutical perspective the inclusion of the model drug, ibuprofen, combined with PVP in the co-melt process proved to be highly significant. It was found that using DSC analysis on the formulations that the decrease in the heat of fusion associated with the melting of ibuprofen within the FHMG systems may be attributed to interaction between PVP and ibuprofen through inter-molecular hydrogen bonding. This interaction decreases the crystallinity of ibuprofen and facilitates solubilisation and bioavailability within the solid matrix.
Resumo:
Credit unions are member-owned, voluntary, self-help, democratic, not-for-profit institutions that provide financial services to their members. They have both economic and social goals. Over this last decade they have achieved remarkable growth levels and currently there are 600 such organisations in Ireland, with approximately 50 per cent of the adult population of Ireland belonging to a credit union. Accounting for credit unions is a much-neglected area and relatively little is known about the sector's accountability. This paper presents the results of an initial empirical study of the financial accountability of Irish credit unions. A series of interviews and a basic content analysis of 178 recent financial statements were used to identify the views of key stakeholders with respect to the discharge of financial accountability by credit unions and the current quality of financial reporting. Overall, the research points to a sector where financial accountability through the medium of the annual report is weak and possible adverse consequences of this are explored. On the basis of the interviews it is suggested that if changes in financial accountability are to be achieved then some more proactive engagement of parties external to the management of individual credit unions is needed.
Resumo:
This paper investigates the two-stage stepwise identification for a class of nonlinear dynamic systems that can be described by linear-in-the-parameters models, and the model has to be built from a very large pool of basis functions or model terms. The main objective is to improve the compactness of the model that is obtained by the forward stepwise methods, while retaining the computational efficiency. The proposed algorithm first generates an initial model using a forward stepwise procedure. The significance of each selected term is then reviewed at the second stage and all insignificant ones are replaced, resulting in an optimised compact model with significantly improved performance. The main contribution of this paper is that these two stages are performed within a well-defined regression context, leading to significantly reduced computational complexity. The efficiency of the algorithm is confirmed by the computational complexity analysis, and its effectiveness is demonstrated by the simulation results.