Nanocrystalline Cubic Phase Scandium-Stabilized Zirconia Thin Films.

The cubic zirconia (ZrO2) is attractive for a broad range of applications. However, at room temperature, the cubic phase needs to be stabilized. The most studied stabilization method is the addition of the oxides of trivalent metals, such as Sc2O3. Another method is the stabilization of the cubic phase in nanostructures-nanopowders or nanocrystallites of pure zirconia. We studied the relationship between the size factor and the dopant concentration range for the formation and stabilization of the cubic phase in scandium-stabilized zirconia (ScSZ) films. The thin films of (ZrO2)1-x(Sc2O3)x, with x from 0 to 0.2, were deposited on room-temperature substrates by reactive direct current magnetron co-sputtering. The crystal structure of films with an average crystallite size of 85 Å was cubic at Sc2O3 content from 6.5 to 17.5 mol%, which is much broader than the range of 8-12 mol.% of the conventional deposition methods. The sputtering of ScSZ films on hot substrates resulted in a doubling of crystallite size and a decrease in the cubic phase range to 7.4-11 mol% of Sc2O3 content. This confirmed that the size of crystallites is one of the determining factors for expanding the concentration range for forming and stabilizing the cubic phase of ScSZ films.

Platinum-Enhanced Electron Transfer and Surface Passivation through Ultrathin Film Aluminum Oxide (Al2O3) on Si(111)-CH3 Photoelectrodes.

We report the preparation, stability, and utility of Si(111)-CH3 photoelectrodes protected with thin films of aluminum oxide (Al2O3) prepared by atomic layer deposition (ALD). The photoelectrodes have been characterized by X-ray photoelectron spectroscopy (XPS), photoelectrochemistry (Fc in MeCN, Fc-OH in H2O), electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV) simulation. XPS analysis of the growing Al2O3 layer affords both the thickness, and information regarding two-dimensional versus three-dimensional mode of growth. Impedance measurements on Si(111)|CH3|Al2O3 devices reveal that the nascent films (5-30 Å) exhibit significant capacitance, which is attenuated upon surpassing the bulk threshold (∼30 Å). The Al2O3 layer provides enhanced photoelectrochemical (PEC) stability evidenced by an increase in the anodic window of operation in MeCN (up to +0.5 V vs Ag) and enhanced stability in aqueous electrolyte (up to +0.2 V vs Ag). XPS analysis before and after PEC confirms the Al2O3 layer is persistent and prevents surface corrosion (SiOx). Sweep-rate dependent CVs in MeCN at varying thicknesses exhibit a trend of increasingly broad features, characteristic of slow electron transport kinetics. Simulations were modeled as slow electron transfer through a partially resistive and electroactive Al2O3 layer. Lastly, we find that the Al2O3 ultrathin film serves as a support for the ALD deposition of Pt nanoparticles (d ≈ 8 nm) that enhance electron transfer through the Al2O3 layer. Surface recombination velocity (SRV) measurements on the assembled Si(111)|CH3|Al2O3-15 device affords an S value of 4170 cm s(-1) (τ = 4.2 µs) comparable to the bare Si(111)-CH3 surface (3950 cm s(-1); τ = 4.4 µs). Overall, the results indicate that high electronic quality and low surface defect densities can be retained throughout a multistep assembly of an integrated and passivated semiconductor|thin-film|metal device.

GAMSAT: A 10-year retrospective overview, with detailed analysis of candidates' performance in 2014.

BACKGROUND: The Graduate Australian Medical Schools Admission Test (GAMSAT) is undertaken annually in centres around Australia and a small number of overseas locations. Most Australian graduate entry medical schools also use Grade Point Average and interview score for selection. The aim of this study was to review the performance of the GAMSAT over the last 10 years; the study provides an analysis of the impact of candidates' gender, age, language background, level of academic qualification and background discipline on performance; and details on the performance of higher-scoring candidates. These analyses were undertaken on the 2014 data; and trends in the data over the 10-year period are noted. METHODS: In reviewing performance, the main variables considered were: - Overall GAMSAT score and scores for Section 1, Reasoning in Humanities and Social Sciences, Section 2, Written Communication, and Section 3, Reasoning in Biological and Physical Sciences. - Proportions of candidates achieving a Typical Entry Score. - Impact of gender, age, language background, level of academic qualification and undergraduate course (i.e. subject discipline) on test scores. Descriptive statistics and tests of significance were applied to determine the impact of demographic variables on performance. RESULTS: The number of candidates is increasing. Test reliability is consistently high. Higher scores overall are more likely for candidates who are male; are less than 24 years old; have an English-speaking background; have an Honours degree or a doctorate; and have completed a degree which is not health-related. CONCLUSIONS: Performance of the GAMSAT exam over the last 10 years has been stable with high reliability. There are significant variations in candidate performance related to age, gender, level and discipline of previous academic study and language background.

Cell-type-specific circuit connectivity of hippocampal CA1 revealed through Cre-dependent rabies tracing.

We developed and applied a Cre-dependent, genetically modified rabies-based tracing system to map direct synaptic connections to specific CA1 neuron types in the mouse hippocampus. We found common inputs to excitatory and inhibitory CA1 neurons from CA3, CA2, the entorhinal cortex (EC), the medial septum (MS), and, unexpectedly, the subiculum. Excitatory CA1 neurons receive inputs from both cholinergic and GABAergic MS neurons, whereas inhibitory neurons receive a great majority of inputs from GABAergic MS neurons. Both cell types also receive weaker input from glutamatergic MS neurons. Comparisons of inputs to CA1 PV+ interneurons versus SOM+ interneurons showed similar strengths of input from the subiculum, but PV+ interneurons received much stronger input than SOM+ neurons from CA3, the EC, and the MS. Thus, rabies tracing identifies hippocampal circuit connections and maps how the different input sources to CA1 are distributed with different strengths on each of its constituent cell types.