-
[show abstract]
[hide abstract]
ABSTRACT: During the past two decades, research on ceramic scaffolds for bone regeneration has progressed rapidly, however currently available porous scaffolds remain unsuitable for load bearing applications. The key to success is to apply microstructural design strategies to develop ceramic scaffolds with mechanical properties approaching those of bone. Here we report on the development of a unique microstructurally-designed ceramic scaffold, strontium-hardystonite-gahnite (Sr-HT-Gahnite) with 85% porosity, 500 μm pore size with a competitive compressive strength of 4.1±0.3MPa and compressive modulus of 170±20MPa. The in vitro biocompatibility of the scaffolds was studied using of primary human bone-derived cells.The ability of Sr-HT-Gahnite scaffolds to repair of critical-sized bone defects was also investigated in a rabbit radius under normal load with β-tricalcium phosphate/hydroxyapatite (TCP/HA) scaffolds used in the control group. Studies with primary human osteoblast cultures confirmed the bioactivity of these scaffolds, and regeneration of rabbit radial critical defects demonstrated this material induces new bone defect bridging with clear evidence of regeneration of original radial architecture and bone marrow environment.
Acta biomaterialia 03/2013; · 3.98 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: This is the first reported study to prepare highly porous baghdadite (Ca(3)ZrSi(2)O(9)) scaffolds with and without surface modification and investigate their ability to repair critical-sized bone defects in a rabbit radius under normal load. The modification was carried out to improve the mechanical properties of the baghdadite scaffolds (particularly to address their brittleness) by coating their surfaces with a thin layer (∼400nm) of polycaprolactone (PCL)/bioactive glass nanoparticles (nBGs). The β-tricalcium phosphate/hydroxyapatite (TCP/HA) scaffolds with and without modification were used as the control groups. All of the tested scaffolds had an open and interconnected porous structure with a porosity of ∼85% and average pore size of 500μm. The scaffolds (six per scaffold type and size of 4mm×4mm×15mm) were implanted (press-fit) into the rabbit radial segmental defects for 12weeks. Micro-computed tomography and histological evaluations were used to determine bone ingrowth, bone quality, and implant integration after 12weeks of healing. Extensive new bone formation with complete bridging of the radial defect was evident with the baghdadite scaffolds (modified/unmodified) at the periphery and in close proximity to the ceramics within the pores, in contrast to TCP/HA scaffolds (modified/unmodified), where bone tended to grow between the ulna adjacent to the implant edge. Although the modification of the baghdadite scaffolds significantly improved their mechanical properties, it did not show any significant effect on in vivo bone formation. Our findings suggest that baghdadite scaffolds with and without modification can serve as a potential material to repair critical sized bone defects.
Acta biomaterialia 07/2012; 8(11):4162-72. · 3.98 Impact Factor
-
Y Escabi,
L San Miguel,
T. Judd,
J Hertza,
J Nicholson,
W Schiff,
C Bell,
B Estes,
C Millikin,
P Shelton, [......],
D Wygant,
P Klonoff,
D Carone,
T O'Connor Pennuto,
A Kluck,
J Ball,
L Shahani,
J Thomspon,
A Bowles,
M Greiffenstein
[show abstract]
[hide abstract]
ABSTRACT: The evaluation of bilingual children is a complicated endeavor because there are various views of how bilingualism affects brain organization and functioning. Added to that is the challenge of determining language development of Hispanic children living in a monolingual Spanish-speaking home in a Spanish-speaking country, but mostly exposed to English language television programming and, in some cases, English language school curriculum. Our case will review the evaluation process of a 14-year-old Puerto Rican boy with previous diagnoses of expressive language disorder and Attention-deficit/Hyperactivity Disorder (ADHD). The neuropsychological evaluation revealed an IQ within the average range, with significant differences between the perceptual reasoning, verbal comprehension, and processing speed. The case will summarize performance in verbal, executive, and psycho-educational measures with a thorough review of his developmental history and the interpretation of these neuropsychological achievement and behavioral measures in light of other variables influencing his difficulties.
Archives of Clinical Neuropsychology 09/2010; 25(6):475-583. · 2.18 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We have obtained evidence that fluoride ions are mobile in SiO 2 at room temperature. The outer surface of a thin layer of the oxide is coated with a fluoride salt and charged by a negative corona discharge in air. From shifts in the C-V curve and changes in the properties of trapping states near the interface we infer that negative ions have moved through the oxide. This is confirmed by an analysis with a secondary-ion mass spectrometer.
Journal of Applied Physics 03/1975; · 2.17 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: M. Della Valle, Arcetri Astrophysical Observatory, Florence; I. Saviane, European Southern Observatory; and R. Williams, Space Telescope Science Institute, report that preliminary analysis of a spectrum (range 390-850 nm), obtained on Oct. 30.25 UT at La Silla with the 1.5-m telescope (+ Boller amp Chivens spectrograph), shows that the suspected nova reported on IAUC 7738 is indeed a nova caught during its early decline. The spectrum is dominated by emission lines of the Balmer series, flanked by P-Cyg profiles. Also prominent are emission lines due to Na I, Fe II, and O I. The FWZI measured for H-alpha yields about 5500 km/s.
iaucirc. 7743:2.
