The chemistry andphysics involved at the metal/atmosphereinterface is interesting both from a fundamental and an appliedperspective. Since iron is the most important of all metalsthis interface is of particular interest. The objective withthis thesis is to obtain new information on a molecular levelof the iron/atmosphere interface with a special emphasis on theinitial atmospheric corrosion. The work presented herein combines a large variety ofdifferent analytical surface science techniques. Both ultrahigh vacuum and ambient pressure investigations were conductedwith single crystals as well as polycrystalline samples. The interaction of segregated sulfur with a Fe(110) surfacewas investigated by means of atomically resolved scanningtunneling microscopy (STM). A large variety of high and lowcoverage reconstructions were reported. Comparable studies ofoxygen adsorption on the same surface were also completed.Similar to the sulfur experiments, oxygen induced a number oflow coverage reconstructions. At higher coverage, oxideformation was observed and ordered oxides could be fabricatedat elevated temperatures. The oxygen interaction with Fe(110) and Fe(100) surfaces wasalso investigated with synchrotron radiation basedphotoelectron spectroscopy. Detailed information of the initialadsorption and subsequent oxidation was obtained. The Fe 2pcore level of the clean Fe(110) surface was subject to furtherinvestigations because of its complicated line profile that wasinterpreted as an exchange split of the final state. Iron exposed to humidified air with low concentrations ofsulfur dioxide (SO2) shows a surprisingly passive behavior. Themeasured mass gain was significantly lower than that of acopper sample exposed in the same environment. In-situtechniques such as atomic force microscopy (AFM), quartzcrystal microbalance (QCM) and infrared reflection absorptionspectroscopy (IRAS) showed little or no corrosion. Initiationof corrosion was observed upon introduction of additionaloxidants. The conclusion drawn challenge the established modelfor formation and growth of sulfate nests. The condition andformation of sulfate nests are discussed in view of thegenerated in-situ observations. During further experiments, iron was exposed to humid airand sodium chloride aerosols. The surface was investigated within-situ techniques, which provided new useful information. Ahigh corrosion rate was observed and the corrosion attacks formfilaments characteristic of filiform corrosion. A schematicmodel for propagation of the corrosion filaments wasproposed. Filiform corrosion was observed on aluminum surfaces aswell. The corroded surfaces were investigated with synchrotronradiation based photoelectron microscopy and scanning over afiliform head revealed different oxidation states within the Al2p spectrum. The microscopy data was interpreted as anenrichment of aluminum chloride containing compounds within thefiliform corrosion head.

<p>The chemistry andphysics involved at the metal/atmosphereinterface is interesting both from a fundamental and an appliedperspective. Since iron is the most important of all metalsthis interface is of particular interest. The objective withthis thesis is to obtain new information on a molecular levelof the iron/atmosphere interface with a special emphasis on theinitial atmospheric corrosion.</p><p>The work presented herein combines a large variety ofdifferent analytical surface science techniques. Both ultrahigh vacuum and ambient pressure investigations were conductedwith single crystals as well as polycrystalline samples.</p><p>The interaction of segregated sulfur with a Fe(110) surfacewas investigated by means of atomically resolved scanningtunneling microscopy (STM). A large variety of high and lowcoverage reconstructions were reported. Comparable studies ofoxygen adsorption on the same surface were also completed.Similar to the sulfur experiments, oxygen induced a number oflow coverage reconstructions. At higher coverage, oxideformation was observed and ordered oxides could be fabricatedat elevated temperatures.</p><p>The oxygen interaction with Fe(110) and Fe(100) surfaces wasalso investigated with synchrotron radiation basedphotoelectron spectroscopy. Detailed information of the initialadsorption and subsequent oxidation was obtained. The Fe 2pcore level of the clean Fe(110) surface was subject to furtherinvestigations because of its complicated line profile that wasinterpreted as an exchange split of the final state.</p><p>Iron exposed to humidified air with low concentrations ofsulfur dioxide (SO2) shows a surprisingly passive behavior. Themeasured mass gain was significantly lower than that of acopper sample exposed in the same environment. In-situtechniques such as atomic force microscopy (AFM), quartzcrystal microbalance (QCM) and infrared reflection absorptionspectroscopy (IRAS) showed little or no corrosion. Initiationof corrosion was observed upon introduction of additionaloxidants. The conclusion drawn challenge the established modelfor formation and growth of sulfate nests. The condition andformation of sulfate nests are discussed in view of thegenerated in-situ observations.</p><p>During further experiments, iron was exposed to humid airand sodium chloride aerosols. The surface was investigated within-situ techniques, which provided new useful information. Ahigh corrosion rate was observed and the corrosion attacks formfilaments characteristic of filiform corrosion. A schematicmodel for propagation of the corrosion filaments wasproposed.</p><p>Filiform corrosion was observed on aluminum surfaces aswell. The corroded surfaces were investigated with synchrotronradiation based photoelectron microscopy and scanning over afiliform head revealed different oxidation states within the Al2p spectrum. The microscopy data was interpreted as anenrichment of aluminum chloride containing compounds within thefiliform corrosion head.</p>

There are puzzle pieces to the cure for Alzheimer’s Disease (AD), and such can emerge by inspecting the biomolecular interactions and their effects on neuronal cells. The upcoming presented literature review will cover the molecular changes caused by AD pathological progression, explore the relationship between non-AD molecules and AD molecules in the body, and analyze potential contributing factors in AD. In addition, the information to be provided will highlight medicinal alternatives respective to a particular stage in AD.

Radionuclides, 129I and 239,240Pu, are major products or by-products of nuclear fission and among the top risk drivers for waste disposal at the Savannah River Sites (SRS) and Rocky Flats Environmental Technology Sites (RFETS), respectively, due to their perceived mobility in the environment, excessive inventory, toxicity, and long half-life. The objective of this study is to investigate the role of natural organic matter in retarding or facilitating the migration of 129I and 239,240Pu in the Department of Energy (DOE) sites. Measurements of 127I and 129I in humic acids (HAs) and fulvic acids (FAs) obtained by five successive alkaline, two glycerol and one citric acid-alkaline extractions, demonstrated that these extractable humic substances (HS) together account for 54-56 percent and 46 percent of the total 127I and 129I in the soil, respectively. The variations among 127I and 129I concentrations, isotopic ratios (129I/127I), chemical properties of all these humic substances indicated iodine was bound to a small-size aromatic subunit (~10 kDa), while the large-size subunit (~90 kDa), which likely linked the small-size unit through some weak chemical forces, determined the relative mobility of iodine bound to organic matter. Soil resuspension experiments simulating surface runoff or stormflow and erosion events were conducted with soils collected from SRS. Results showed that 72-77 percent of the newly-introduced I- or IO3- were irreversibly sequestered into the organic-rich soil, while the rest was transformed into colloidal and dissolved organo-iodine by the soil. The resulting iodine remobilization contradicts the conventional view that considers only I- or IO3- as the mobile forms. Quantitative structure analysis by 13C DPMAS NMR and solution state 1H NMR on these humic substances indicate that iodine is closely related to the aromatic regions containing esterified products of phenolic and fomic acid or other aliphatic carboxylic acids, amide functionalities, quinone-like structure activated by electron-donating groups (e.g., NH2) or hemicelluloses-lignin-like complex with phenyl-glycosidic linkage. The micro-molecular environment, such as the hydrophobic aliphatic periphery hindering the active aromatic cores and the hydrophilic polysaccharides favoring its accessibility towards hydrophilic iodine species, play another key role in the interactions between iodine and SOM. NMR spectra of the colloidal organic Pu carrier which can potentially be released from the soil during the surface runoff or stormflow showed Pu was transported, at sub-pM concentrations, by a cutin-derived soil degradation products containing siderophore-like moieties and virtually all mobile Pu.