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Petroporphyrins contribute to many of the challenges encountered when producing, transporting, and refining heavy crude oil and bitumen. They are the source of heavy metals that poison catalysts and may facilitate the aggregation, deposition, and emulsion formation exhibited by asphaltenes. Here, they are extracted and enriched to ultrahigh purities from several sources: an Athabasca bitumen, a Canadian northern tier crude oil, and a North American heavy crude oil. Our motivation is to produce usable quantities that can be characterized and used in model studies to understand the molecular structure of asphaltenes and to probe asphaltene−petroporphyrin intermolecular interactions, in the bulk and at interfaces. Extraction is performed in a Soxhlet apparatus. The porphyrin-rich extract is then further purified using extrography (on silicapacked columns) and chromatography (on alumina-packed columns). The process yields purified petroporphyrins in unprecedented quantities (>100 mg). These purified petroporphyrins can be further refined to ultrahigh purities (>85% petroporphyrin by weight) using temperature and centrifugation to fractionate them into more and less soluble fractions. Petroporphyrins are characterized by ultraviolet−visible spectroscopy, X-ray fluorescence spectroscopy, and mass spectrometry (time of flight and Fourier transform ion cyclotron resonance). The majority of the petroporphyrins are simple etioporphyrin (407 nm Soret band) or deoxophylloerythroetioporphyrin (410 nm Soret band) types, but some are more functionalized compounds with highly broadened and shifted Soret bands.

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Probiotics or health-beneficial bacteria have only recently been introduced in dentistry after years of successful use in mainly gastrointestinal disorders. The concept of bacteriotherapy was first introduced in the beginning of 20th century. They are administered in different quantities that allow for colon colonization. These products help in stimulating health promoting flora and also suppressing the pathologic colonization and disease spread. The use of probiotic plays an important aspect in dentistry too, ever since the oral infections occupied the prime spot among the other infections affecting the humans. Probiotics strengthen the immune system to combat allergies, stress, exposure to toxic substances, and other diseases. This review is an attempt to discuss briefly the role of probiotics in oral health.

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