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F Salama

Publications and source records attributed to F Salama.

10 recordsLinked to original sources
PubMed1998

Carbon in the universe.

Carbon is a major player in the evolutionary scheme of the universe because of its abundance and its ability to form complex species. It is also a key element in the evolution of prebiotic molecules. The different forms of cosmic carbon are reviewed ranging from carbon atoms and carbon-bearing molecules to complex, solid-state, carbonaceous structures. The current state of knowledge is assessed on the observational and laboratory fronts. Fundamental astrophysical implications are examined as well as the impact of these studies on the hitherto poorly understood physical and chemical properties of carbon materials in space.

Astronomical Phenomena↗
PubMed1998

The diffuse interstellar bands: a tracer for organics in the diffuse interstellar medium?

The diffuse interstellar bands (DIBs) are absorption bands seen in the spectra of stars obscured by interstellar dust. DIBs are recognized as a tracer for free, organic molecules in the diffuse interstellar medium (ISM). The potential molecular carriers for the DIBs are discussed with an emphasis on neutral and ionized polycyclic aromatic hydrocarbons (PAHs) for which the most focused effort has been made to date. From the combined astronomical, laboratory and theoretical study, it is concluded that a distribution of free neutral and ionized complex organics (PAHs, fullerenes, unsaturated hydrocarbons) represents the most promising class of candidates to account for the DIBs. The case for aromatic hydrocarbons appears particularly strong. The implied widespread distribution of complex organics in the diffuse ISM bears profound implications for our understanding of the chemical complexity of the ISM, the evolution of prebiotic molecules and its impact on the origin and the evolution of life on early Earth through the exogenous delivery (cometary encounters and metoritic bombardments) of prebiotic organics.

Astronomical Phenomena↗
PubMed1989

Alveolar ridge augmentation in Macaca fascicularis using polysulfone with and without demineralized bone powder.

The purpose of this study was to test the soft tissue and bone response to the implantation of porous polysulfone (PPSF) with and without demineralized bone powder (DBP) for ridge augmentation in Macaca fascicularis. The mandibular molar teeth were extracted in five adult female monkeys, followed by massive alveolectomy. Five to eight months later, PPSF + DBP was inserted subperiosteally on the left side, while PPSF alone was inserted on the right side. The animals were killed 42, 60, and 90 days following implantation. Specimens were processed for light microscopy, scanning electron microscopy, tetracycline labeling, and histomorphometric measurement of new bone. The 42-day specimens of the PPSF + DBP and PPSF revealed penetration of fibrous tissue rich in fibroblasts and blood vessels into the pores of the PPSF. At 60 and 90 days, the PPSF side showed organized fibrous tissue, but bone grew only for a short distance into the implant. In contrast, the PPSF + DBP side showed large amounts of bone formation, and bone almost covered the implant. The qualitative results were confirmed by histomorphometric examination.

Alveolar Process↗