Biomedical subjects

Joachim Ulrich

Publications and source records attributed to Joachim Ulrich.

4 recordsLinked to original sources

PubMed2005

Microwave processing of natural biopolymers--studies on the properties of different starches.

In this study, the influence of microwave irradiation on some physico-chemical properties and several pharmaceutical technological parameters of potato and maize starches was investigated. Changes in their habits were observed and decrease in moisture contents caused by the electromagnetic irradiation was determined. The crystalline structures and the micromorphological parameters of the starches were affected by microwave irradiation in different ways depending on the botanical origin of the samples. The tensile strengths of the compacts containing starches were decreased, their wetting properties were enhanced by the thermal process applied. Furthermore, microwave irradiation reduced the surface free energy and the polarity of the compacts significantly. Samples treated by conventional heating were used to compare the effects of microwave irradiation on the examined properties and parameters of these starches.

Biopolymers↗

PubMed2004

Investigation of entrapped pore in the pastilles by a mercury porosimetery technique.

The pore in pastilles was investigated which are produced by a pastillation technology. Mercury intrusion porosimeter and scanning electron microscopy (SEM) techniques were used for the investigation. The formation of micro-pores and cracks were in dependence of the manufacturing conditions of the pastilles (final impacting velocity, degree of subcooling and surface roughness of cooled substrate). The total pore is decreased with decreasing degree of subcooling, final impacting velocity and surface roughness of the cooled substrate. In order to design a drug delivery system and to select an optimum manufacturing parameter the relationship between overall growth rate of the pastilles and total pore was experimentally investigated. The total pore increased with increasing the overall growth rate of pastilles.

Bisacodyl↗

PubMed2003

Prediction of degree of deformation and crystallization time of molten droplets in pastillation process.

The direct solidification process of a melt into a particulate solid is studied to achieve the desired size and shape of the product and to predict the required crystallization time. For an example, a Bisacodyl melt is chosen. The role of the contact angle of the droplet is investigated as a function of Reynolds number, degree of subcooling and characteristic of used cooled surface (substrate). The static contact angle increases with increasing degree of surface roughness of the substrate. The contact angle, however, decreases with increasing Reynolds number and degree of subcooling. The phenomena of spreading and rebouncing of droplets are used in the discussion of the deformation process. By the model of Madejski the degree of deformation is found to be proportional to the Reynolds number to the power of 0.2. On the basis of a simple droplet solidification model and experimental data, a numerical study is presented. The equations allow to estimate the normalized deformation and crystallization times, which are proportional to the Reynolds number to the power of 1.23 and help the design of solidification processes.

Chemistry, Pharmaceutical↗

PubMed2002

Impurity distribution in a solid-liquid interface during static layer crystallization.

The impurity distribution inside crystalline layers in static layer crystallizations was explored theoretically and experimentally for a binary eutectic mixture of caprolactam and water. The impurity distribution in the layer is modeled by a mass balance equation coupled with an energy balance equation. The mass balance equation is established with a combination of the growth of the layer and the diffusional movement of impurity. The mathematical model was solved by a numerical method. The predictions are discussed with respect to the interfacial distribution coefficient, concentration, and temperature at the solid-liquid interface, crystalline layer thickness, and concentration of the layer. The impurity distribution obtained by the model was appropriately verified with the results obtained by the experiments.

Journal Article↗