Polycyclic aromatic hydrocarbons (PAH),t also known as polynuclear aromatic hydrocarbons or polyarenes, constitute a large class of organic compounds. They are formed and released into the environment through natural and man-made sources. Natural sources include volcanoes and forest fire, while the man-made sources come from wood burning, automobile exhaust, industrial power generators, incinerators, production of coal tar, coke, asphalt and petroleum, incomplete combustion of coal, oil, gas, garbage, tobacco and charbroiled meat. Polycyclic aromatic heterocyclic analogs containing one or more nitrogen, oxygen or sulfur atoms are also present in substantial quantities in coal tar and petroleum residues produced during the refining process. In the atmosphere, they are principally generated from the combustion of fossil fuels, wood or forest burning, refuse burning and coal tar. Although anthropogenic sources account for the major portion of atmospheric PAH pollution (l), vehicle emissions are believed to be responsible for 35% of the total PAH emission in highly populated and industrialized urban areas of the United States (2). Deposition of PAH in surface and ground waters can take place from a variety of sources such as airborne PAH, municipal wastewater discharge, effluents from wood treatment plants and other industries, oil spills and petroleum pressing. Accumulation of PAH in soils is believed to result from atmospheric deposition after long-range transport. The concentration of PAH found in soil around urban and industrialized areas are sometimes up to two orders of magnitude higher than those in less-developed areas (derived from forest fires and airborne pollution). Once released into the environment, PAH can partition between air, water, soil or sediments. An extensive body of work on this subject has appeared in the literature in recent years. Representative examples include partitioning of PAH between the gas and suspended particle phase (3,4), aidwater

A Compilation of Physical, Spectroscopic and Photophysical Properties of Polycyclic Aromatic Hydrocarbons

Garlic and garlic extracts, through their antioxidant activities, have been reported to provide protection against free radical damage in the body. This study investigated antioxidant properties of garlic compounds representing the four main chemical classes, alliin, allyl cysteine, allyl disulfide, and allicin, prepared by chemical synthesis or purification. Alliin scavenged superoxide, while allyl cysteine and allyl disulfide did not react with superoxide. Allicin suppressed the formation of superoxide by the xanthine/xanthine oxidase system, probably via a thiol exchange mechanism. Alliin, allyl cysteine, and allyl disulfide all scavenged hydroxyl radicals; the rate constants calculated based on deoxyribose competitive assay were 1.4-1.7 x 10(10), 2.1-2.2 x 10(9), and 0.7-1.5 x 10(10) M (1) second(1), respectively. Contrary to previous reports, allicin did not exhibit hydroxyl radical scavenging activity in this study. Alliin, allicin, and allyl cysteine did not prevent induced microsomal lipid peroxidation, but both alliin and allyl cysteine were hydroxyl scavengers, and allyl disulfide was a lipid peroxidation terminator. In summary, our findings indicated that allyl disulfide, alliin, allicin, and allyl cysteine exhibit different patterns of antioxidant activities as protective compounds against free radical damage.

The Antioxidant Properties of Garlic Compounds: Allyl Cysteine, Alliin, Allicin, and Allyl Disulfide

The molecular level details of the displacement of surface adsorbed fibrinogen from silica substrates were studied by atomic force microscopy, immunochemical assays, fluorescence microscopy, and vibrational sum frequency spectroscopy. The results showed that human plasma fibrinogen (HPF) can be readily displaced from the interface by other plasma proteins near neutral pH because the positively charged αC domains on HPF sit between the rest of the macromolecule and the underlying surface. The αC domains make weak electrostatic contact with the substrate, which is manifest by a high degree of alignment of Lys and Arg residues. Upon cycling through acidic pH, however, the αC domains are irreversibly removed from this position and the rest of the macromolecule is free to engage in stronger hydrogen bonding, van der Waals, and hydrophobic interactions with the surface. This results in a 170-fold decrease in the rate at which HPF can be displaced from the interface by other proteins in human plasma.

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The Vroman effect: a molecular level description of fibrinogen displacement.

....................................................................^ 2 Introduction.....................................................^ 2 Physical and Chemical Characteristics of the Okefenokee Swamp...................................................................................... 3 Geology...................................................................................................................................................................... 3 Peat Deposits.................................................................^ 4 Hydrology............................................................................................................................................................^ 5 Water Chemistry........................................................................................................................................................ 6 Major Habitats in the Okefenokee Swamp............................................................................................................................ 7 Forested Upland................................................................................................................................................^ 7 Forested Wetland................................................._ 7 Scrab-Shrub Wetland................................................................^ 8 Prairie......................................................................................................................................................................... 8 Successional Processes and Disturbances in the Okefenokee Swamp.................................................................................. 8 Formation of Tree Islands.......................................................................................................................................... 8 Episodic Fires............................................................................................................................................................. 9 Logging...................................................................................................................................................................... 9 Animal Life in the Okefenokee Swamp................................................................................................................................ 9 Sunimary...........................................................»^ 11 References Cited.................................................................................................................................................................... 11

/pdf/humic-substances-in-the-suwannee-river-georgia-interactions-iwlwa80y3p.pdf

Humic substances in the Suwannee River, Georgia; interactions, properties, and proposed structures

Metal based biologically active compounds: design, synthesis, and antibacterial/antifungal/cytotoxic properties of triazole-derived Schiff bases and their oxovanadium(IV) complexes

William Walter Simons

Papers

The Sadtler Handbook Of Infrared Spectra

The Sadtler handbook of proton NMR spectra

The Sadtler handbook of ultraviolet spectra

The Sadtler guide to carbon-13 NMR spectra

Nuclear magnetic resonance spectra of N-acylanilines. Effect of substituents on the chemical shift of the ortho proton