Dataset acquisition, accessibility, annotation, e-research technologies (DART) project

The DART project undertook a coordinated program of e-Research requirements analysis, software development, policy and guideline creation and prototyping to investigate how best to: (1) collect, capture and retain large data sets and streams from a range of different sources; (2) deal with the infrastructure issues of scale, sustainability and interoperability between repositories; (3) support deposit into, access to, and annotation by a range of actors, to a set of digital libraries which include publications, datasets, simulations, software and dynamic knowledge representations; (4) assist researchers in dealing with intellectual property issues during the research process; and (5) adopt next-generation methods for research publication, dissemination and access. In this short paper we will describe a case study using an X-ray diffractometer. We report on the implementation and some of the issues encountered during the implementation.     

Heat Transfer in Straight Channels with Two‐Dimensional Cross‐Sectional Profiles under Conditions of Nonisothermal Stabilized Flow of a Fluid

Heat transfer in stabilized regimes of nonisothermal flows in a round tube and in channels with twodimensional convex cross sections is investigated with allowance for the velocity profile of a heating or cooling flow of a fluid. Mathematical models of unsteady processes of cooling by convection and radiation in pulling of rods and plane sheets at a constant velocity and of heat transfer (mass transfer) in a thin runningdown layer of a medium (fluid) are solved.     

Ge quantum dot memory structure with laterally ordered highly dense arrays of Ge dots

This work was devoted to the development of a Ge quantum dot memory structure of a MOSFET type with laterally ordered Ge quantum dots within the gate dielectric stack. Lateral ordering of the Ge dots was achieved by the combination of the following technological steps: (a) use of a focused ion beam (FIB) to create ordered two-dimensional arrays of regular holes on a field oxide on the silicon substrate, (b) chemical cleaning and restoring of the Si surface in the holes, (c) further oxidation to transfer the pattern from the field oxide to the silicon substrate, (d) removal of the field oxide and thermal re-oxidation of the sample in order to create a tunneling oxide of homogeneous thickness on the patterned silicon surface, and (e) self-assembly of the two-dimensional arrays of Ge dots on the patterned tunneling oxide. The charging properties of the obtained memory structure were characterized by electrical measurements. Charging of the Ge quantum dot layer by electrons injected from the substrate resulted in a large shift in the capacitance-voltage curves of the MOS structure. Charges were stored in deep traps in the charging layer, and consequently the erasing process was difficult, resulting in a limited memory window. The advantages of controlled positioning of the quantum dots in the charging layer will be discussed.     

A Thioether‐Stabilized d‐Proline–l‐Proline‐Induced β‐Hairpin Peptide of Defensin Segment Increases Its Anti‐Candida albicans Ability

We report a β‐hairpin dual stabilizing strategy: a d ‐proline‐l ‐proline (d ‐Pro‐l ‐Pro) dipeptide as the nucleating turn, and a thioether tether as a side‐chain linkage at a precisely designed position to stabilize the β‐hairpin. This method was used to modify the C‐terminal β‐hairpin moiety of the plant defensin, pv‐defensin, in order to obtain a stabilized peptide with enhanced anti‐Candida albicans activity (MIC 84–3.0 μm ), high serum stability (50 % remaining after 48 h) and low hemolysis (<10 % at 152 μm ). This modified peptide penetrated the C. albicans cell membrane within 5 min and showed high activity against clinically isolated antibiotic‐resistant C. albicans and Candida glabrata strains.     

Diffusion Characteristics of Zr4+ in LiNbO3 Single‐Crystal

Diffusion characteristics of Zr⁴⁺ in LiNbO₃ single‐crystal were studied. Zr⁴⁺‐doped LiNbO₃ crystal plates were prepared by in‐diffusion of 100 nm thick ZrO₂ film coated onto Z‐cut congruent substrates in wet O₂ at different temperatures. Zr⁴⁺‐diffused profile was analyzed by secondary ion mass spectrometry. The results show that the Zr⁴⁺ diffusion follows the traditional diffusion theory. From the measured profiles, important diffusion parameters are obtained, such as diffusivity and its temperature dependence, diffusion constant, activation energy, surface concentration, and solubility. The Zr⁴⁺ has a diffusivity similar to that of Ti⁴⁺, implying that the Zr⁴⁺ doping and the Ti⁴⁺ diffusion can be performed simultaneously to simplify the fabrication process of a photorefractive‐damage‐resistant Zr⁴⁺‐doped Ti‐diffused LiNbO₃ waveguide.     

Vibrationally Assisted Polariton‐Relaxation Processes in Strongly Coupled Organic‐Semiconductor Microcavities

If a semiconductor with an electronic transition that approximates a two‐level system is placed within an optical cavity, strong coupling can occur between the confined photons and the semiconductor excitons. This coupling can result in the formation of cavity polariton states that are a coherent superposition of light and matter. If the material in the cavity is an organic semiconductor, it has been predicted that interactions between Frenkel excitons, polaritons, and molecular vibrational modes will have a profound role in defining the overall relaxation dynamics of the system. Here, using temperature‐dependent spectroscopy on a microcavity containing a J‐ aggregated cyanine dye, it is shown that a spectrum of localized vibrational modes (identified by Raman scattering) enhances the population of certain polaritonic modes by acting as an energy‐loss channel to the excitons as they undergo scattering. Our work demonstrates that simultaneous control of the optical properties of a cavity and the vibrational structure of a molecular dye could promote the efficient population of k = 0 polariton states, from which lasing and other cooperative phenomena may occur.     

Comparison of various buffer schemes to grow GaN on large-area Si(111) substrates using metal-organic chemical-vapor deposition

A comparison of gallium-nitride (GaN) films grown on large-area Si(111) using a single aluminum-nitride (AlN) buffer, an AlN/graded-Al_xGa_1−xN buffer, and the introduction of additional low-temperature (LT)-grown AlN interlayers is reported. A graded-AlGaN buffer followed by additional LT-AlN interlayers is shown to completely eliminate cracking in nitride films of thickness >2 μm and also reduce the threading-dislocation density significantly. A partial compensation of GaN-tensile strain by the compressive-lattice strain induced by the AlGaN and AlN layers is responsible for this effect. The surface roughness is increased by the introduction of the LT-AlN buffers.     

Oscillation detection technique by using Vector Network Analyzer

A Vector Network Analyzer(VNA) can be used to identify oscillation frequency of a signal source with moderate or low Radio Frequency(RF) power if certain care is taken according to experimental results. Unlike reported in the literature that a resonant peak of measured absolute value of reflection coefficient greater than 1 that corresponds to an oscillation frequency, we report that by observing the magnitude change of one-port reflection coefficient across the entire swept frequency range, a sudden peak or a dip corresponds to an oscillation frequency, this is more accurate than other reports. In addition, using modern VNA as a signal detection method can significantly reduce measurement time and increase measurement accuracy to VNA capability for developing emerging signal generating devices at early stage, especially for planar, large quantity and operating in a wide frequency range.