Steps on Fe3O4(100): STM measurements and theoretical calculations

Scanning tunneling microscopy (STM) measurements of the step structure on natural single-crystal samples of Fe3O4(100) have been performed. Step edges are found to occur along both [110] and [1 (1) over bar0] directions. For step heights of 4.2 +/- 0.3 angstrom, the step edges are found to be straight, whereas for step heights of 2.1 +/- 0.2 angstrom, alternate step edges are straight and jagged. The straight (jagged) step edges are parallel (perpendicular) to the octahedral iron rows on the upper terrace. The concepts of coordinative unsaturation and excess surface charge are used to predict which atomic geometries are likely to be most stable along step edges. Our calculations show that steps parallel to the octahedral iron rows on the upper terrace are expected to be more stable than those perpendicular to them, in agreement with our STM observations. This step stability is found to be independent of both terrace structure and step height

Protocol for implementation of family health history collection and decision support into primary care using a computerized family health history system

<p>Abstract</p> <p>Background</p> <p>The CDC's Family History Public Health Initiative encourages adoption and increase awareness of family health history. To meet these goals and develop a personalized medicine implementation science research agenda, the Genomedical Connection is using an implementation research (T3 research) framework to develop and integrate a self-administered computerized family history system with built-in decision support into 2 primary care clinics in North Carolina.</p> <p>Methods/Design</p> <p>The family health history system collects a three generation family history on 48 conditions and provides decision support (pedigree and tabular family history, provider recommendation report and patient summary report) for 4 pilot conditions: breast cancer, ovarian cancer, colon cancer, and thrombosis. All adult English-speaking, non-adopted, patients scheduled for well-visits are invited to complete the family health system prior to their appointment. Decision support documents are entered into the medical record and available to provider's prior to the appointment. In order to optimize integration, components were piloted by stakeholders prior to and during implementation. Primary outcomes are change in appropriate testing for hereditary thrombophilia and screening for breast cancer, colon cancer, and ovarian cancer one year after study enrollment. Secondary outcomes include implementation measures related to the benefits and burdens of the family health system and its impact on clinic workflow, patients' risk perception, and intention to change health related behaviors. Outcomes are assessed through chart review, patient surveys at baseline and follow-up, and provider surveys. Clinical validity of the decision support is calculated by comparing its recommendations to those made by a genetic counselor reviewing the same pedigree; and clinical utility is demonstrated through reclassification rates and changes in appropriate screening (the primary outcome).</p> <p>Discussion</p> <p>This study integrates a computerized family health history system within the context of a routine well-visit appointment to overcome many of the existing barriers to collection and use of family history information by primary care providers. Results of the implementation process, its acceptability to patients and providers, modifications necessary to optimize the system, and impact on clinical care can serve to guide future implementation projects for both family history and other tools of personalized medicine, such as health risk assessments.</p

On the difference in valence electron plasmon energy and density of states between beta- and cubic-Si3N4

Core and valence level photoemissionspectra of β- and cubic-Si3N4 have been measured under monochromatic AlKα excitation. Strong satellites to high binding energy of the core lines are shown to arise from excitation of valence electron plasmons during the photoemission process. An increase in the plasmonenergy from 23.45 eV for β-Si3N4 to 26.10 eV for cubic-Si3N4 is of the magnitude expected from the 26% increase in the valence electron density associated with the shock-induced β-to-cubic phase transition. The measuredvalence banddensity of states for cubic-Si3N4 is in agreement with theoretical calculations.</p

Studies of the electronic structure at the Fe3O4-NiO interface

The interfacial electronic structure between the metallic ferrimagnet Fe3O4 and the insulating antiferromagnet NiO is investigated in the lattice matched heteroepitaxial system Fe3O4 (100)-NiO (100) by growing ultrathin NiO films on single-crystal Fe3O4 (100) substrates. The Fe3O4 (root2 X root2)R45degrees surface is characterized prior to growth by low-energy electron diffraction, reflection high-energy diffraction, scanning tunneling microscopy, ultraviolet photoelectron spectroscopy (UPS), x-ray photoemission spectroscopy (XPS) and Auger electron spectroscopy. UPS and XPS, which sample several monolayers in the substrate-overlayer structure, are used to monitor near-surface electronic properties versus NiO overlayer thickness. Comparison of experimental He II UPS spectra of the valence band electronic structure with a simple model of substrate-overlayer emission indicates that the electronic transition from Fe3O4 to NiO is nearly atomically sharp. (C) 2004 American Vacuum Society

Growth and surface structure of vanadium oxide on anatase(001)

Oxygen plasma-assisted molecular beam epitaxy (OPA-MBE) of vanadium oxide on (1x4)-reconstructed anatase (001) thin films was studied using reflection high energy electron diffraction (RHEED), low energy electron diffraction (LEED), X-ray and ultraviolet photoelectron spectroscopy (XPS and UPS), X-ray diffraction (XRD), and transmission electron microscopy (TEM). XPS and UPS results showed that the vanadium was predominantly in the 5+ oxidation state after deposition of a monolayer at 525 K. After 1 ML of vanadia, was deposited, the anatase (1x4)/(4x1) LEED and RHEED patterns were replaced by (1x1) patterns indicating that the vanadia lifts the reconstruction and sugesting that the monolayer is pseudomorphic. At 525 K, the V5+ oxidation state predominated in thicker films, however. no discernible LEED or RHEED patterns were seen after a few monolayers were deposited indicating that V2O5 epitaxy cannot be continued beyond 1 ML. When the growth temperature was increased to 750 K, RHEED patterns indicated no change in the surface structure after more than 20 ML of vanadia, were deposited. Under these conditions. XPS peak positions were consistent with VO2. After growth at 775 K a c(2x2) LEED pattern attributed to half a monolayer of adsorbed oxygen on the VO2 surface was observed. The surface characterization data all pointed towards pseudomorphic growth of VO2 with a half monolayer of capping oxygen allowing the monolayer to achieve the V2O5 stoichiometry while maintaining the anatase structure. Bulk XRD data, however, were consistent with VO2(B), V6O13. and rutile VO2; none of which expose surfaces with the periodicity observed with RHEED and LEED. The reasons for the differences between the surface and bulk characterization are discussed. (C) 2004 Elsevier B.V. All rights reserved