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Model System Consisting (model + system_consisting)
Selected AbstractsCohesive-zone modelling of the deformation and fracture of spot-welded jointsFATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 10 2005M. N. CAVALLI ABSTRACT The deformation and failure of spot-welded joints have been successfully modelled using a cohesive-zone model for fracture. This has been accomplished by implementing a user-defined, three-dimensional, cohesive-zone element within a commercial finite-element package. The model requires two material parameters for each mode of deformation. Results show that the material parameters from this type of approach are transferable for identical spot welds in different geometries where a single parameter (such as maximum stress) is not. The approach has been demonstrated using a model system consisting of spot-welded joints made from 5754 aluminium sheets. The techniques for determining the cohesive fracture parameters for both nugget fracture and nugget pullout are described in this paper. It has been demonstrated that once the appropriate cohesive parameters for a weld are determined, quantitative predictions can be developed for the strengths, deformations and failure mechanisms of different geometries with nominally identical welds. [source] A numerical approach revealing the impact of rheological properties on mouthfeel caused by foodINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 6 2007Katrin Mathmann Summary In contrast to the static chemoreceptor-related flavour perception, texture of food capable of flow is detected dynamically with oral mechanoreceptors while the food is manipulated in the mouth. The resulting sensation called mouthfeel strongly depends on the different physical properties of food. Aim of the current study is to determine numerically the occurring fluid mechanical forces in food suspensions using a simplified tongue-palate model system consisting of two parallel plates. For this purpose, the equations of fluid and particle motion are numerically solved by using structured overlapping grids. In the computational experiment, a density neutral fluid system between the plates is compressed by moving the upper plate with constant velocity down to the other one. It has been found that suspended particles move with the fluid flow but have only minor effect on the global flow field in the applied concentration. [source] Effects of Phosphates and Salt in Ground Raw and Cooked Farmed Cod (Gadus morhua) Muscle Studied by the Water Holding Capacity (WHC), and Supported by 31P-NMR MeasurementsJOURNAL OF FOOD SCIENCE, Issue 3 2009S.O. Johnsen ABSTRACT:, A model system consisting of ground farmed cod muscle (80%, w/w) and added brine (20%, w/w) with different content and combinations of salt (0% and 3% in brine) and phosphorus compounds (mono-, di-, tri- and hexametaphosphates; 0% and 3% in brine) was used to simulate industrial brining of muscle foods. Individual phosphorus component concentrations and breakdown as function of time (0, 23 h) were analyzed using 31P-NMR spectroscopy. The effects of salt and phosphate on water holding capacity (WHC) were measured at similar sampling times, and interrelations between phosphorous components determined by NMR and WHC were established. Addition of salt led to a significant increase (+18%) in WHC, and the combined effect of salt and phosphates was even more pronounced (+29%). The positive effect of triphosphate and salt on WHC was also seen after cooking (+36% in raw and +41% in cooked cod muscle, relative to control), although NMR analysis showed a rapid breakdown of di- and triphosphates. [source] Molecular dynamics simulations of hydrotropic solubilization and self-aggregation of nicotinamideJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 7 2010Yong Cui Abstract Hydrotropy is a phenomenon where the presence of a large quantity of one solute enhances the solubility of another solute. The mechanism of this phenomenon remains elusive and a topic of debate. This study employed molecular dynamics simulation to investigate the hydrotropic mechanism of a model system consisting of a hydrotropic agent, nicotinamide (NA), a poorly water-soluble solute, PG-300995 (PG), and water. Our study demonstrates that NA and PG undergo significant aggregation in the aqueous solution, a result correlating closely to the self-aggregation of NA under the same conditions. The correlations are found both structurally and dynamically, suggesting that the self-aggregation of NA may be a prerequisite, or at least a major contributor, to its hydrotropic effects. The self-aggregation of NA allows the segregation of the hydrophobic solute from water, a key step to ease the energy increase to the system. Energetic evidences directly show that the hydrotropic solubilization is favored in the presence of NA aggregation. These results are in strong support of the molecular aggregation hypothesis for hydrotropic solubilization. Additionally, it is found that the restoration of water,water HBs from the interference of the NA and PG molecules plays an important role for the aggregation. The HBs between the solute and the hydrotrope may contribute, but is not vital, to the aggregation and hence the hydrotropic effects. The dynamic data confirm that the aggregates, while remain in liquid state, are much more active dynamically than a pure NA amorphous/liquid phase under the same temperature and pressure. By equilibrating an NA amorphous agglomerate with water, it is found that the aggregation state, rather than an NA,water two phase system, is the equilibrium state of the NA,+,water system. © 2010 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 99:3048,3059, 2010 [source] Toward Understanding the Mechanism of Chromophore-assisted Laser Inactivation,Evidence for the Primary Photochemical Steps,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 2 2005Elke Horstkotte ABSTRACT Chromophore-assisted laser inactivation (CALI) is a lightmediated technique used to selectively inactivate proteins of interest to elucidate their biological function. CALI has potential applications to a wide array of biological questions, and its efficiency allows for high-throughput application. A solid understanding of its underlying photochemical mechanism is still missing. In this study, we address the CALI mechanism using a simplified model system consisting of the enzyme ,-galactosidase as target protein and the common dye fluorescein. We demonstrate that protein photoinactivation is independent from dye photobleaching and provide evidence that the first singlet state of the chromophore is the relevant transient state for the initiation of CALI. Furthermore, the inactivation process was shown to be dependent on oxygen and likely to be based on photooxidation of the target protein via singlet oxygen. The simple model system used in this study may be further applied to identify and optimize other CALI chromophores. [source] | ||||||||||