Results 181 to 190 of about 5,617 (213)
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The Journal of Physical Chemistry A, 2016
The supramolecular structure of melanin pigments is characterized by a high concentration of radical species. Therefore, the energetics of the radical formation in melanin building blocks is key for understanding the structure and the electronic properties of the pigments at the molecular level. Nevertheless, the radical energetics of even the simplest
Filipe Agapito, Benedito J. Costa Cabral
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The supramolecular structure of melanin pigments is characterized by a high concentration of radical species. Therefore, the energetics of the radical formation in melanin building blocks is key for understanding the structure and the electronic properties of the pigments at the molecular level. Nevertheless, the radical energetics of even the simplest
Filipe Agapito, Benedito J. Costa Cabral
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Elucidating the Photoprotection Mechanism of Eumelanin Monomers
The Journal of Physical Chemistry B, 2017Eumelanin, the functional polymer in human skin, forms a heterogeneous layered structure intrinsic to its broadband monotonic spectra. The inherent structural heterogeneity of eumelanin makes the photoprocesses very complex and diverse in nature. Due to this diversity, a complete mechanistic picture of these photoprocesses, essential to understanding ...
Paulami Ghosh, Debashree Ghosh
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Solvochromic Effects in Model Eumelanin Compounds†
Photochemistry and Photobiology, 2008ABSTRACTWe have created an indolic compound which is ideally suited to the study of the relationship between structure and function in eumelanin formation. N‐methyl‐5‐hydroxy‐6‐methoxyindole (MHMI) is stable in solid and liquid states, highly soluble in a variety of solvents and forms a dimer only through the 4‐4′ positions.
Nighswander-Rempel, Stephen P. +4 more
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Establishing structure–function relationships for eumelanin
Biopolymers, 2002AbstractThe aggregation‐dependent optical properties of eumelanin from human hair are examined. When aggregation is increased, the absorption spectrum extends to lower energy. The absorption spectra of oligomers isolated from black human hair and Sepia officinalis are comparable and are in quantitative agreement with the reported action spectra for ...
J Brian, Nofsinger +2 more
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Speculations on the molecular structure of eumelanin
International Journal of Cosmetic Science, 2009SynopsisEumelanin is the polymeric black pigment commonly found in hair and skin. Its chemical intractability, to all but vigorous oxidizing agents, has hindered satisfactory understanding of its molecular structure. It is well‐established that the immediate precursor to polymerization, indole‐5,6‐quinone (IQ), is biosynthesized from the amino acid ...
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Charge Transport in Eumelanin [PDF]
Melanins are a class of bio-macromolecules that are found throughout the biosphere. They fulfill various functions in human beings, which makes them a long studied substance in medicine and biology. Furthermore they possess a set of rare and special physico-chemical properties which include featureless broad band absorption in the UV-Vis spectrum and ...
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Spectrophotometric Characterization of Eumelanin and Pheomelanin in Hair
Pigment Cell Research, 1996Mammalian melanins exist in two chemically distinct forms: the brown to black eumelanins and the yellow to reddish‐brown pheomelanins. They can be quantified by HPLC analysis of pyrrole‐2,3,5‐tricarboxylic acid (PTCA) and aminohydroxyphenylalanine (AHP).
H, Ozeki +3 more
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Spectrophotometric Assay of Eumelanin in Tissue Samples
Analytical Biochemistry, 1993Most of the natural melanin pigments consist of not only indolic eumelanin but also sulfur-containing pheomelanin. Previous methods for spectrophotometric assay of melanins use solubilization in alkaline media; a major disadvantage of these procedures is that they do not distinguish between eumelanin and pheomelanin.
S, Ito, K, Wakamatsu, H, Ozeki
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A Hierarchical Self-Assembly of Eumelanin
The Journal of Physical Chemistry B, 2000Atomic force microscopy is used to examine the structure of a natural eumelanin isolated from the ink sacs of cuttlefish (Sepia officinalis). The experimental data presented clearly show that the 100−200 nm spherical eumelanin particles imaged previously by SEM are not a fundamental structural unit. While these spherical particles are stable structures,
Christine M. R. Clancy +3 more
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1988
It is generally accepted that black and brown skin is well-protected against sunlight-induced inflammation and degeneration. In contrast the fair skin of certain Caucasian subjects and especially the skin of red-haired people is highly sensitive to the damaging effects of sunlight.
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It is generally accepted that black and brown skin is well-protected against sunlight-induced inflammation and degeneration. In contrast the fair skin of certain Caucasian subjects and especially the skin of red-haired people is highly sensitive to the damaging effects of sunlight.
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