Microstructure and dielectric function modelling by spectroscopic ellipsometry and energy electron loss spectroscopy of In₂O₃:Sn thin films

Indium tin oxide (ITO) is a semiconducting material combining high conductivity and high transparency in the visible range. It is the most widely used transparent conducting oxide in applications such as flat panel displays. In this work, ITO thin films were deposited by pulsed laser deposition (PLD) onto transparent glass substrates. The substrate temperature and oxygen pressure during deposition were controlled to generate a variety of microstructures and electro-optical properties. Similar film thicknesses were used to avoid any change of carrier concentration. The dielectric function and complex refractive index were derived using spectroscopic ellipsometry and electron energy loss spectroscopy

Incorporating Nutrition Education Classes into Food Pantry Settings: Lessons Learned in Design and Implementation

The project reported here evaluated the effectiveness of nutrition education at food pantries. We offer best practices for future Extension-based nutrition programming with this clientele. Three classes were offered at food pantries through the Expanded Food and Nutrition Education Program (EFNEP). Entry and exit surveys were collected for each series, including 24-hour food recalls. Seventy-three percent of participants reported an increase in vegetable consumption, and 82% reported positive changes in consumption of at least one food group. Nutrition education in food pantries is promising, particularly for Extension-led programs like SNAP-Ed and EFNEP, to address nutrition behaviors among food insecure populations

Vertical effective stress as a control on quartz cementation in sandstones

Temperature-controlled precipitation kinetics has become the overwhelmingly dominant hypothesis for the control of quartz cementation in sandstones. Here, we integrate quantitative petrographic data, high spatial resolution oxygen isotope analyses of quartz cement, basin modelling and a kinetic model for quartz precipitation to suggest that the supply of silica from stress-sensitive intergranular pressure dissolution at grain contacts is in fact a key control on quartz cementation in sandstones. We present data from highly overpressured sandstones in which, despite the current burial temperature of 190 °C, quartz cement occurs in low amounts (4.6 ± 1.2% of bulk volume). In situ oxygen isotope data across quartz overgrowths suggest that cementation occurred over 100 Ma and a temperature range of 80–150 °C, during which time high fluid overpressures resulted in consistently low vertical effective stress. We argue that the very low amounts of quartz cement can only be explained by the low vertical effective stress which occurred throughout the burial history and which restricted silica supply as a result of a low rate of intergranular pressure dissolution at grain contacts

Magnetic isomers and local moment distribution in Mn5O and Mn6O clusters

A synergistic approach combining the experimental photoelectron spectroscopy and theoretical electronic structure studies is used to demonstrate the existence of magnetic isomers as well as configurations having comparable binding energies, identical spins, and yet differing in the distribution of local moments (called isomags). Our studies carried out on Mn5O and Mn6O clusters show that while the O atom occupies either bridge or hollow site with a binding energy of 6.88eV in Mn5, it prefers a hollow site with a binding energy of 7.18eV in Mn6 clusters. Mn5O is shown to possess two magnetic isomers with total spins of 13 and 5μB that contain three and five isomags, respectively. Mn6O possesses three isomers, two with moments of 8 and 2μBand a nonmagnetic. It is shown that the isomags, although undetected in magnetic experiments, can be identified via their electronic structure in experimental photoelectron spectra

Inelastic interaction mean free path of negative pions in tungsten

The inelastic interaction mean free paths lambda of 5, 10, and 15 GeV/c pions were measured by determining the distribution of first interaction locations in a modular tungsten-scintillator ionization spectrometer. In addition to commonly used interaction signatures of a few (2-5) particles in two or three consecutive modules, a chi2 distribution is used to calculate the probability that the first interaction occurred at a specific depth in the spectrometer. This latter technique seems to be more reliable than use of the simpler criteria. No significant dependence of lambda on energy was observed. In tungsten, lambda for pions is 206 plus or minus 6 g/sq cm

Numerical simulations of stellar SiO maser variability. Investigation of the effect of shocks

A stellar hydrodynamic pulsation model has been combined with a SiO maser model in an attempt to calculate the temporal variability of SiO maser emission in the circumstellar envelope (CE) of a model AGB star. This study investigates whether the variations in local physical conditions brought about by shocks are the predominant contributing factor to SiO maser variability because, in this work, the radiative part of the pump is constant. We find that some aspects of the variability are not consistent with a pump provided by shock-enhanced collisions alone. In these simulations, gas parcels of relatively enhanced SiO abundance are distributed in a model CE by a Monte Carlo method, at a single epoch of the stellar cycle. From this epoch on, Lagrangian motions of individual parcels are calculated according to the velocity fields encountered in the model CE during the stellar pulsation cycle. The potentially masing gas parcels therefore experience different densities and temperatures, and have varying line-of-sight velocity gradients throughout the stellar cycle, which may or may not be suitable to produce maser emission. At each epoch (separated by 16.6 days), emission lines from the parcels are combined to produce synthetic spectra and VLBI-type images. We report here the results for v=1, J=1-0 (43-GHz) and J=2-1 (86-GHz) masers.Comment: 16 pages, 8 figures, accepted by A&

The role of growth directors in controlling the morphology of hematite nanorods

The control of the growth of hematite nanoparticles from iron chloride solutions under hydrothermal conditions in the presence of two different structure promoters has been studied using a range of both structural and spectroscopic techniques including the first report of photo induced force microscopy (PiFM) to map the topographic distribution of the structure-directing agents on the developing nanoparticles. We show that the shape of the nanoparticles can be controlled using the concentration of phosphate ions up to a limit determined to be ~6 × 10−3 mol. Akaganéite (β-FeOOH) is a major component of the nanoparticles formed in the absence of structure directors but only present in the very early stages (< 8 h) of particle growth when phosphate is present. The PiFM data suggest a correlation between the areas in which phosphate ions are adsorbed and areas where akaganéite persists on the surface. In contrast, goethite (α-FeOOH) is a directly observed precursor of the hematite nanorods when 1,2-diamino propane is present. The PiFM data shows goethite in the center of the developing particles consistent with a mechanism in which the iron hydroxide re-dissolves and precipitates at the nanorod ends as hematite