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Polyethylene oxides

Analysis of tablet formation and properties of the resulting tablets

Journal of Thermal Analysis and Calorimetry
Author: Katharina Picker-Freyer

Abstract  

The aim of this study was to study tablet formation of polyethylene oxides (PEOs) with different molecular masses by means of 3D modeling and comparing the results to those of other more traditional techniques, such as Heckel analysis, analysis by the pressure- time function and energy analysis. The molecular masses ranged between 400,000 and 7,000,000 Da. Material properties, such as water content, particle size and morphology, and glass transition temperature were also studied. To complete this study, elastic recovery dependent on maximum relative density and time were determined. Furthermore, the crushing force of the tablets and their morphology were analyzed. The PEOs consist of smooth edged particles of irregular shape; the particle size is similar to one type of MCC, namely Avicel PH 200. The PEOs are much more ductile during compression than MCC. Elastic recovery after tableting is higher than that for tablets made from MCC and continues for some time after tableting. The crushing force of the resulting tablets is low. In conclusion, with regards to direct compression the PEOs do not appear to be useful as sole tableting excipients.

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Dual retention behavior is observed for triphenylmethane (TPM) derivatives in RPTLC on silica gel plates when the composition of acetone-water mobile phases is varied. The physicochemical and molecular properties of the TPM derivatives causing this unusual retention behavior have been investigated by traditional quantitative structure-retention relationship (QSRR) modeling and by 3D molecular modeling. The QSRR studies were performed by using PLS regression analysis based upon use of selected sets of Dragon molecular descriptors and pharmacokinetically relevant VolSurf descriptors to identify the physicochemical properties that govern chromatographic behavior. Comparative molecular similarity indices analysis (CoMSIA) was used to create the 3D isoenergy contours of favored and unfavored contributions of the molecular fields around the molecules in the RPTLC systems used. The dual retention behavior of the TPM derivatives can be attributed to the propensity of these molecules to become oriented with different parts of their surface toward the silica gel layer when mobile phases with high or low water content are used. This hypothesis was supported by the 3D modeling results, which revealed that the isoenergy contours of the electrostatic, hydrophobic, and hydrogen bond acceptor fields of CoMSIA around the molecules were very different in systems with high or low water content. Furthermore, the VolSurf descriptors, which represent pharmacokinetic properties, correlated better with R M values measured using mobile phases with high water content than with those measured using mobile phases with low water content, and thus may be related to chromatographic behavior. Statistically significant PLS models with high predictive power ( q 2 > 0.8) have been developed for prediction of R M values for the four mobile phases used. Lipophilicity was found to be the most important molecular property governing the retention of TPM derivatives.

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56 62 Zheng, J. Y. (1994) Acquiring 3-D models from sequences of contours. IEEE Transactions on Pattern Analysis and Machine , 16, 163

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. P OGGIO , L. & G IMONA , A. , 2014 . National scale 3D modelling of soil organic carbon stocks with uncertainty propagation –An example from Scotland . Geoderma . 232–234 . 284 – 299

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printed reactionware made by FDM type 3D printers. Adapted with permission from Ref. [ 35 ], Copyright 2012 The Royal Society of Chemistry. (b) Polypropylene microreactor and rendered 3D model of microreactor. 1 EUR coin is for size comparison. The

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the calculations are done using the software package ANSYS, establishing a 3-D model of SHU in Fig. 5 and choosing the Solid 90 as the space element. The properties of the sample and background material are listed in Table 1 , while the thermal

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simulated by a step-by-step incremental method which needs to store huge data of stress history in a large-scale 3D model. Zhu [ 38 , 39 ] proposed an implicit method for the creep stress analysis which avoids storing the entire stress history and makes the

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