Fabrication of porous calcium phosphate cements using gelatin as porogen

Abstract

Porous calcium phosphate cements (CPCs) were fabricated using gelatin granules as the porogen. As the amount of gelatin was increased from 0 to 43 vol%, the porosity notably increased from 3 to 47 vol%, while the compressive strength decreased from 23 to 14 MPa; however, these values are still expected to be reasonably high for applications in bone tissue engineering. In addition, osteoblastic cells grew favorably on the surfaces of the CPCs prepared using gelatin of 11 and 43 vol%, which contained well interconnected pores with a size of several hundreds of microns, indicating excellent biocompatibility of the porous CPC samples produced in this study.

An Oosterhoff Analysis of the Galactic Bulge Field Rr Lyrae Stars: Implications on Their Absolute Magnitudes

“…The reddening-free apparent magnitude differences between the OoI and OoII-type bulge field RR Lyrae stars are discussed. As was found in RR0 Lyrae stars in GCs (Lee & Carney 1999), RR0 Lyrae variables with OoII-type properties are about 0.2 mag brighter than those with OoItype properties. The differences in the evolutionary stages of the OoI and OoII-type variables are probably the cause for this luminosity difference.…”

“…The van Albada & Baker (1971) explanation thus suggests (1) OoI clusters are evolving red to blue and OoII clusters the other way, (2) that OoI clusters have a smaller fraction of RR1 variables than OoII clusters, and (3) that metallicity is the dominant characteristic that determines where on the horizontal-branch core helium burning begins. However, this explanation does not explain the absence of a dichotomy in other galaxies unless the range in metallicity in each galaxy is very small (Lee & Carney 1999).…”

“…THE QUEST RR Lyrae catalog, which did not find a Oosterhoff dichotomy in their sample, probes deeper than the LONEOS survey (by ∼25 kpc), and hence would give a more complete picture of the Galactic halo. However, OoII RR Lyrae stars in general are located closer to the Galactic Plane (Lee & Carney 1999;de Lee 2008), and hence the depth of the QUEST survey may have the effect of limiting the number of OoII RR Lyrae with respect to OoI RR Lyrae. None of these samples probe the Galactic bulge, and are located at quite different locations on the sky as the MACHO bulge RR0 Lyrae sample.…”

“…A similar analysis cannot be carried out with the OoII-like RR0 Lyrae stars, because they exhibit a wide range of metallicities with no clear function on V -amplitude for a given period. Lee & Carney (1999) performed an investigation on the luminosities of RR Lyrae variables with similar metallicities but different Oosterhoff classes. They found that RR Lyrae variables in the Oosterhoff II cluster M2 are intrinsically brighter than those in Oosterhoff group I cluster M3, although these clusters have similar [Fe/H].…”

Brushite cement containing gelatin: evaluation of mechanical strength and in vitro degradation

“…The polymers can provide better mechanical performance and also better properties, such as injectability, setting time, cohesion, degradation rate and biological response [18]. Chitosan [21], alginate [22], silk fibroin [23], collagen [24] and gelatin [25,26] are some examples. The formation of CPC/polymer composite follows the natural bone, that consists of apatite and fibrous collagen [7,27,28].…”