Physics of compression

In terms of the flow properties, the physics of compression, the variability of the dissolution and porosimetry parameters and the variability between trials, the wet granulated formula showed best results in almost all cases. This process is then proposed for the study of prolonged release formulations. 

Pharmaceutical products have been manufactured into compressed tablets for many years. During the 1950s, much research was devoted to the physics of compression.f Since that time, the pharmaceutical industry has attained a much greater understanding of the compression process, which resulted in the development of more robust pharmaceutical formula-tions. This has been achieved by the use of instrumented tablet presses and sophisticated data collection systems combined with the development of mathematical models. 

Let us consider one more physical phenomenon, which can influence upon PT sensitivity and efficiency. There is a process of liquid s penetration inside a capillary, physical nature of that is not obvious up to present time. Let us consider one-side-closed conical capillary immersed in a liquid. If a liquid wets capillary wall, it flows towards cannel s top due to capillary pressure pc. This process is very fast and capillary imbibition stage is going on until the liquid fills the channel up to the depth l , which corresponds the equality pcm = (Pc + Pa), where pa - atmospheric pressure and pcm - the pressure of compressed air blocked in the channel. 

Asay J R and Shahinpour M (eds) 1993 High-Pressure Shock Compression of Solids (New York Springer) Bridgman P W 1958 The Physics of High Pressure (London G Beii and Sons)... 

Density and polymer composition have a large effect on compressive strength and modulus (Fig. 3). The dependence of compressive properties on cell size has been discussed (22). The cell shape or geometry has also been shown important in determining the compressive properties (22,59,60,153,154). In fact, the foam cell stmcture is controlled in some cases to optimize certain physical properties of rigid cellular polymers. 

The success of compression agglomeration depends on the effective utilization and transmission ofthe applied external force and on the ability of the material to form and maintain interparticle bonds during pressure compaction (or consolidation) and decompression. Both these aspects are controlled in turn by the geometiy of the confined space, the nature of the apphed loads and the physical properties of the particulate material and of the confining walls. (See the section on Powder Mechanics and Powder Compaction.)... 

The flow of compressible and non-compressible liquids, gases, vapors, suspensions, slurries and many other fluid systems has received sufficient study to allow definite evaluation of conditions for a variety of process situations for Newtonian fluids. For the non-Newtonian fluids, considerable data is available. However, its correlation is not as broad in application, due to the significant influence of physical and rheological properties. This presentation is limited to Newtonian systems, except where noted. 

W. B. Holzapfel, Physics of solids under strong compression. Rep. Prog. Phys. 59 (1996) 29. 

Delarue, B. J. and S. B. Pope (1997). Application of PDF methods to compressible turbulent flows. Physics of Fluids 9, 2704-2715. 

Dansereau, R., Peck, G. The Effect of the variability in the physical and chemical properties of magnesium stearate on the properties of compressed tablets. Drug Dev. Ind. Pharm.,13(6), 1987, 975-999. 

Production of tablets at medium-to-large scale requires more stringent control of powder properties due to the high-speed compression step. Processing of tablets and the physics of tablet compaction have been the subject of extensive investigation and voluminous literature exists on the topic. 

The NIR spectrum depends not only on the chemical composition of the sample, but also on some physical properties such as the size, form, particle distribution and degree of compression of the sample. This is useful in some cases as it enables the spectroscopic determination of some physical parameters of the sample. However, physical differences can lead to multiplicative effects in the spectrum, which, together with other additive effects such as baseline shift or chemical absorption, can complicate calibration models and detract from the quality of the results of quantitative analyses if not properly understood and accounted for. 

The physics of the problem under study is assumed to be governed by the compressible form of the Favre-filtered Navier-Stokes energy and species equations for an ideal gas mixture with constant specific heats, temperature-dependent transport properties, and equal diffusion coefficients. The molecular Schmidt, Prandtl, and Lewis numbers are set equal to 1.0, 0.7, and 1.43, respectively [17]. 

Fureby, C. 1996. On subgrid scale modeling in large eddy simulations of compressible fluid flow. J. Physics Fluids 8 1301-11. 

PP bead foams were subjected to oblique impacts (167), in which the material was compressed and sheared. This strain combination could occur when a cycle helmet hit a road surface. The results were compared with simple shear tests at low strain rates and to uniaxial compressive tests at impact strain rates. The observed shear hardening was greatest when there was no imposed density increase and practically zero when the angle of impact was less than 15 degrees. The shear hardening appeared to be a unique function of the main tensile extension ratio and was a polymer contribution, whereas the volumetric hardening was due to the isothermal compression of the cell gas. Eoam material models for FEA needed to be reformulated to consider the physics of the hardening mechanisms, so their... 

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