Výsledky vyhledávání - "James M. Gallas"

Structural Studies of Bleached Melanin by Synchrotron Small-angle X-ray Scattering¶

Autor: Kenneth C. Littrell, Pappannan Thiyagarajan, James M. Gallas, Gerry W. Zajac

Publikováno v: Photochemistry and Photobiology. 77:115-120

Small-angle X-ray scattering was used to measure the effects of chemical bleaching on the size and morphology of tyrosine-derived synthetic melanin dispersed in aqueous media. The average size as measured by the radius of gyration of the melanin part

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::c7a26db8adf7ce7c0048c6874f55c479
https://doi.org/10.1562/0031-8655(2003)0770115ssobmb2.0.co2

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Effect of Stacking and Redox State on Optical Absorption Spectra of Melanins−Comparison of Theoretical and Experimental Results

Autor: Shirley Gidanian, Joseph T. Golab, Patrick J. Farmer, Gerry W. Zajac, James M. Gallas, Theresa M. McIntire, Klaus B. Stark

Publikováno v: The Journal of Physical Chemistry B. 109:1970-1977

In this work the effect of aggregation and oxidation on the optical absorption of eumelanin oligomeric sheets is investigated by applying quantum mechanics and atomistic simulation studies to a simplified eumelanin structural model that includes 1-3

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::416fd62036012658bebc997c3884fbbb
https://doi.org/10.1021/jp046710z

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Spectroscopic Study and Simulation from Recent Structural Models for Eumelanin: II. Oligomers

Autor: James M. Gallas, Klaus B. Stark, Gerry W. Zajac, Joseph T. Golab, Melvin Eisner

Publikováno v: The Journal of Physical Chemistry B. 107:11558-11562

Spectroscopic simulations of a leading structural model for melanin, which is the pigment responsible for coloration and photo protection in humans and animals, were conducted. In direct continuation of an earlier study on possible monomer and dimer

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_________::18841ffe64ebfa2a2e2e50b29723c787
https://doi.org/10.1021/jp034965r

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Spectroscopic Study and Simulation from Recent Structural Models for Eumelanin: I. Monomer, Dimers

Autor: James M. Gallas, Gerry W. Zajac, Klaus B. Stark, Melvin Eisner, Joseph T. Golab

Publikováno v: The Journal of Physical Chemistry B. 107:3061-3067

Spectroscopic simulations of a leading structural model for melanin, the pigment responsible for coloration and photoprotection in humans and animals, were done. We performed density functional theory (DFT) calculations using both the local density a

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_________::0ed7d77fb1e3d47ff922d862a7ad571c
https://doi.org/10.1021/jp0266594

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Structural Differences in Unbleached and Mildly-Bleached Synthetic Tyrosine-Derived Melanins Identified by Scanning Probe Microscopies

Autor: Philip L. Stotter, Gerry W. Zajac, Tadeusz Sarna, James M. Gallas

Publikováno v: Pigment Cell Research. 13:99-108

Using scanning tunneling microscopy (STM), we have imaged two types of mildly-bleached, synthetic tyrosine-derived melanins for comparison with the unbleached melanin from which they were prepared. These mildly-bleached melanins were generated by mil

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_________::5a43f7b602777959eea8c114f7dca458
https://doi.org/10.1034/j.1600-0749.2000.130208.x

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Solution Structure of Copper Ion-Induced Molecular Aggregates of Tyrosine Melanin

Autor: James M. Gallas, Kenneth C. Littrell, Pappannan Thiyagarajan, Gerry W. Zajac, Soenke Seifert

Publikováno v: ResearcherID
Scopus-Elsevier

Melanin, the ubiquitous biological pigment, provides photoprotection by efficient filtration of light and also by its antioxidant behavior. In solutions of synthetic melanin, both optical and antioxidant behavior are affected by the aggregation state

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::6eef6197ec057f818a76e349e96d27a7
https://doi.org/10.1016/s0006-3495(99)76964-x

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The fundamental unit of synthetic melanin: a verification by tunneling microscopy of X-ray scattering results

Autor: Gerry W. Zajac, Melvin Eisner, S.C. Moss, A. E. Alvarado‐Swaisgood, J. Cheng, James M. Gallas

Publikováno v: Biochimica et Biophysica Acta (BBA) - General Subjects. 1199:271-278

A characteristic dimension of a melanin protomolecule synthesized from tyrosine has been investigated by scanning tunneling microscopy (STM). Identification of a melanin protomolecule of approximately approximately 20 A lateral extent and approximate

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::750288999ce0ad8943022168cb045dbf
https://doi.org/10.1016/0304-4165(94)90006-x

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Structural studies of bleached melanin by synchrotron small-angle X-ray scattering

Autor: Kenneth C, Littrell, James M, Gallas, Gerry W, Zajac, Pappannan, Thiyagarajan

Publikováno v: Photochemistry and photobiology. 77(2)

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=pmid________::9ff7dba02557c22020ab5e535d5ae3a3
https://pubmed.ncbi.nlm.nih.gov/12785048

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Physical and photochemical properties of ocular melanin

Autor: Dhiraj K. Sardar, Randolph D. Glickman, Steven L. Jacques, Benjamin A. Rockwell, James M. Gallas

Publikováno v: SPIE Proceedings.

Recent advances in the current state of knowledge about the properties of physiological and synthetic melanin are reviewed in the context of that pigment's optical properties, the physical structure that confers some of its unusual properties, its su

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_________::49548a44162999aa2168c84dced03866
https://doi.org/10.1117/12.431511

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