Influence of starting material particle size on pellet surface roughness

10.1208/s12249-013-0031-5AAPS PharmSciTech151131-13

Influence of degree of polymerization on behavior of cellulose during homogenization and extrusion/spheronization

The study objective was to investigate the influence of the degree of polymerization (DP) of cellulose materials (microcrystalline cellulose [MCC] and powder cellulose [PC]) on the behavior of these materials during homogenization and extrusion/spheronization processes. Suspensions of the cellulose types with different DP values were homogenized using a high-pressure homogenizer. The particle size, agglomeration index, and apparent viscosity of these suspensions was determined at different times after pouring. Additionally, these different cellulose types were processed into pellets using the extrusion/spheronization, method, and the water content and power consumption as a function of the DP were determined. Cellulose types with a high DP value showed greater particle size after homogenization, than the types with a low DP value. In contrast, no relevant relationship between the apparent viscosity and DP could be observed. During the extrusion process, water content in the extrudate and pellet porosity were increased as the DP was increased for the extrudates produced at the same level of power consumption. MCC types with various DPs compared with PC provided a novel way of understanding the role of cellulose in the extrusion process. The DP showed a remarkable influence on the physicochemical properties of the cellulose materials and, consequently, on the behavior of these materials during the extrusion/spheronization process. It is postulated that the sponge model is more appropriate for the cellulose type with high DP (PC), whereas the gel model is more applicable to cellulose types with lower DP (MCC)

Direct pelletization in a rotary processor controlled by torque measurements. II: Effects of changes in the content of microcrystalline cellulose

In the present study we investigated the effect of changes in the content of microcrystalline cellulose (MCC) on a direct pelletization process in a rotary processor in which the liquid addition was terminated once a certain increase in torque was produced. Nine different mixtures of MCC and lactose with MCC contents varying from 10% to 100% (w/w) were pelletized using 6 different torque increase levels, and the changes in pellet characteristics were investigated. The pellet characteristics investigated were pellet shape, size, and size distribution as well as the water content of the pellets at the end of liquid addition. To produce spherical agglomerates with suitable characteristics in a reproducible way, a content of a least 20% (w/w) MCC was found necessary. Linear correlations were found between the MCC content and the water content and between the torque incraase and the water content, showing that the torque increase is suitable to control the process. A higher torque increase or a higher MCC content was found to increase the water content independently of each other

Effects of reminiscence interventions on psychosocial outcomes: A meta-analysis

Objectives: This study integrated results from controlled trials of reminiscence interventions. Methods: Meta-analysis was used to aggregate results from 128 studies on nine outcome variables. Results: Compared to non-specific changes in control-group members, moderate improvements were observed at posttest with regard to ego-integrity (g = 0.64) and depression (g = 0.57 standard deviation units). Small effects were found on purpose in life (g = 0.48), death preparation (g = 0.40), mastery (g = 0.40), mental health symptoms (g = 0.33), positive well-being (g = 0.33), social integration (g = 0.31), and cognitive performance (g = 0.24). Most effects were maintained at follow-up. We observed larger improvements of depressive symptoms in depressed individuals (g = 1.09) and persons with chronic physical disease (g = 0.94) than in other individuals, and in those receiving life-review therapy (g = 1.28) rather than life-review or simple reminiscence. Moderating effects of the control condition were also detected. Conclusions: Reminiscence interventions affect a broad range of outcomes, and therapeutic as well as preventive effects are similar to those observed in other frequently used interventions