Fundamental solutions of cavitation in porous solids: a comparative study

The expansion of internally pressurized cavities, embedded in infinite bodies, in spherical and cylindrical (plane strain and plane stress) configurations, is investigated within the framework of finite plasticity. Material response is modeled by the Gurson theory for porous solids and includes strain hardening. Numerical results, obtained under the assumption of nearly universal loading histories, reveal limit cavitation states for all three deformation patterns. Cavitation is identified with asymptotic levels of the specific cavitation energy, which is highest for the spherical cavity and smallest for plane stress (plate) holes. The influence of material porosity is assessed in context of weight optimization of protective plates. A limited comparison with experimental data for porous titanium plate perforation reveals close prediction of ballistic limit velocity.     

Inorganic Photochromism

This is a review of the photochromism of inorgonic ond co-ordinotion compounds. Reoction mechanisms are discussed and methods of investigating the phenomenon are indicated.     

Sustained release of IL-1Ra from biodegradable microspheres prolongs its IL-1-neutralizing effects

A sustained delivery system for interleukin-1 receptor antagonist (IL-1Ra) may have great therapeutic and industrial potential due to the cytokine activity as an IL-1 inhibitor. Here, we investigated the capability of biodegradable polymeric microspheres to sustain the release and prolong the therapeutic efficacy of IL-1Ra. IL-1Ra was encapsulated within rapidly degrading poly(lactic/glycolic acid) PLGA RG502H microspheres, which showed a desirable release profile of IL-1Ra in vitro. Pharmacokinetic study in mice revealed elevated serum levels of the recombinant IL-1Ra (rIL-1Ra) for up to 8 days following subcutaneous injection of IL-1Ra microspheres. In comparison, the serum levels of rIL-1Ra following subcutaneous or intravenous bolus injection of the soluble cytokine decreased very rapidly; within 48 h no recombinant cytokine was detected in mice sera. The sustained delivery of rIL-1Ra for over two weeks was efficient in inhibiting IL-1ß-stimulated induction of serum IL-6. These results suggest that the present therapeutic protocol of daily bolus injections of the IL-1Ra may be replaced by a weekly injection of IL-1Ra within PLGA RG502H microspheres.     

Real time discrete shading

A shading technique for voxel-based images, termedcongradient shading, is presented. As the surface information is not available in voxel representation, the surface normal must be recovered from the 3D discrete voxel map itself. The technique defines the normal as one of a finite set of neighborhood-estimated gradients and can thus employ precalculated look-up tables. Furthermore, a table-driven mechanism permits changing the light source parameters by merely redefining the look-up table. The technique uses only simple arithmetic operations and is thus suitable for hardware implementation. Since it has been implemented not as a post-processor, but as part of the projection pipeline of the cube architecture, congradient shading can be executed in real time. Two versions of the technique in real time. Two versions of the technique have been conceived and implemented:unidirectional shading, in which the gradient is estimated only from neighborhoods along the scan-lines;bidirectional shading, in which both horizontal and vertical components of the gradient are considered. In spite of the simplicity of the technique, the results are practically indistinguishable from images generated by conventional techniques.This work was supported by the National Science Foundation under grants DCR 8603603, CCR 8743478, CCR 8717016, and MIP 8805130