Biomaterials are widely used in medical devices with good success. However, the surface chemistries of our present generation of biomaterials are not specifically recognized by living organisms. Thus, biological reactions to biomaterials in use today are primarily influenced by non-specific interactions occurring at their surfaces. This paper develops a hypothesis for the development of a future generation of biomaterials. A discussion of the meaning of biocompatibility is followed by a strategy for developing biomaterials that actively induce healing and reconstruction by turning on specific biologic pathways. Materials strategies for encouraging specific reactions and inhibiting non-specific bioreaction are presented. 相似文献
Several decades after the groundbreaking discovery of X-rays in 1895 by Wilhelm Conrad Roentgen, it became quite evident that the possibility of building X-ray sources with controlled photon beam parameters was a revolutionary step to address some of the important challenges facing humanity. The awareness that these sources could dramatically improve mankind's scientific knowledge and technological ability was at the base of significant investments and scientific programs worldwide that brought X-ray sources into the present “golden age.” 相似文献
The zero-field mobilities of many atomic ions in rare gases are calculated from highly accurate, ab initio potential energy curves. They are expected to be accurate to at least 0.05%, thus allowing them to be used to calibrate mobility measurements in different drift-tube and ion mobility mass spectrometers. 相似文献
We present experimental data on water repetitively brought in contact with cellophane. Although this hydrophilic polymer is insoluble in water, repetitively immersing it in water changes the liquid’s properties. We compare the physicochemical properties of the water left over after removing the cellophane to those of previously published data on water repetitively brought in contact with other in water insoluble polymers (cotton wool or Nafion). Some of the properties are similar. All the properties considerably differ from those of the Milli-Q® water used. On lyophilizing these waters, solid residues remain. The residues are soluble in water. The chemical nature of the residues differs from that of the perturbing polymers.
The tensile stability of rotationally symmetric thin membranes composed of isotropic, incompressible and elastic materials is considered by investigating under what conditions the initial equilibrium configuration can bifurcate to another rotationally symmetric equilibrium mode.The general equilibrium equations of a rotationally symmetric membrane are first derived in cylindrical coordinates. The initially cylindrical membrane is studied. The classic solution, which assumes homogeneous deformations, is shown to be a special case of the general equations. Perturbation theory is employed to find the bifurcation points from the homogeneous mode.This study shows that, for the chosen boundary conditions, no rotationally symmetric equilibrium mode exists near the cylindrical mode except the cylindrical mode itself. This corresponds to all experimental data that the author is aware of. The initially cylindrical membrane either remains cylindrical or goes into a non-rotationally symmetric mode. 相似文献
Organic photovoltaics (OPVs) offer the opportunity for cheap, lightweight and mass‐producible devices. However, an incomplete understanding of the charge generation process, in particular the timescale of dynamics and role of exciton diffusion, has slowed further progress in the field. We report a new Kinetic Monte Carlo model for the exciton dissociation mechanism in OPVs that addresses the origin of ultra‐fast (<1 ps) dissociation by incorporating exciton delocalization. The model reproduces experimental results, such as the diminished rapid dissociation with increasing domain size, and also lends insight into the interplay between mixed domains, domain geometry, and exciton delocalization. Additionally, the model addresses the recent dispute on the origin of ultra‐fast exciton dissociation by comparing the effects of exciton delocalization and impure domains on the photo‐dynamics.This model provides insight into exciton dynamics that can advance our understanding of OPV structure–function relationships. 相似文献
We analyse the phase diagram of a lattice gas model with both condenseation and order-disorder phase transitions, when the system is confined between two walls. The gas-liquid transition is shifted into the, so called, capillary condensation. The crystallization, both from the gas and from the liquid, is also shifted from the bulk values, but the ordered structure is frustrated or enhanced depending on its commensuration with the walls separation, H. This produces a strong oscillatory dependence of the phase diagram with H. 相似文献