Production of vertical nanowire resonators by cryogenic-ICP–DRIE

Silicon resonant sensors with large surface area-to-volume ratios provide high weighing sensitivity. This fact implies the possibility for detection of slight mass changes [i.e. by attached nanoparticles (NPs)]. Vertical silicon nanowire (SiNW) resonators are therefore suitable for exposure assessment or airborne NPs. SiNW arrays are top-down fabricated by nanolithography and subsequent inductively coupled plasma reactive ion etching at cryogenic temperature. Nanolithography is performed by conventional UV-lithography and nanoimprint for even smaller structures. Wire diameters are further reduced by multiple thermal oxidations and oxide stripping at times. Parameter effects of cryogenic dry etching are studied for SiNW arrays.     

Corrosion of high purity Mg, Mg2Zn0.2Mn, ZE41 and AZ91 in Hank’s solution at 37 °C

The CO₂ partial pressure required to maintain a synthetic body fluid (SBF) at a constant pH, based on the initial bicarbonate concentration, was evaluated to be 0.013 atm for Hank’s solution and 0.083 atm for SBF27. Corrosion of high purity Mg and three Mg alloys in Hank’s solution was studied using hydrogen evolution, weight loss and Tafel extrapolation. The solution pH was maintained constant by CO₂. There was initially an incubation period with a low corrosion rate, a period of increasing corrosion rate, and subsequently steady state corrosion. Some hydrogen dissolved in the Mg metal.     

Structural,mechanical and electrical-contact properties of nanocrystalline-NbC/amorphous-C coatings deposited by magnetron sputtering

Niobium-carbide nanocomposite coatings with a carbon content varying from 43 to 64 at.% were deposited by dual DC magnetron sputtering. X-ray diffraction, x-ray photoelectron spectroscopy and electron microscopy showed that all coatings consisted of nanometer sized NbC grains embedded in a matrix of amorphous carbon. Mechanical properties and electrical resistivity showed a strong dependency on the amount of amorphous carbon (a-C) and NbC grain size in the coating. The highest hardness (23 GPa), elastic modulus (295 GPa) and the lowest resistivity (260 μΩ cm) were measured for the coating with about 15% of a-C phase. Contact resistance measurements using a crossed cylinder set-up showed lowest contact resistance for the coating containing 33% a-C (140 μΩ at a contact force of 100 N), which is comparable to a Ag reference (45 μΩ at a contact force of 100 N). Comparison with TiC-based nanocomposites studied under similar conditions showed that the NbC system has less tendency to form a-C and that lowest contact resistance is obtained at comparable amounts of a-C phase in both material systems (33% for NbC compared to 35% for TiC). With these good electrical contact properties, the NbC nanocomposites can be considered as a potential material for electrical contact applications.     

A simple algorithm for the calculation of multiple site titration curves

A simple algorithm for the calculation of multiple site titrationcurves is proposed. It is based on a hybridization of two computationaltechniques: (i) a modified Tanford-Roxby iterative procedure[Tanford and Roxby (1972) Biochemistry, 11, 2193–2198]and (ii) the Boltzmann statistics. The sites characterized bystrong electrostatic coupling were selected for statisticalmechanical treatment, whereas all other sites were treated bymeans of the modified Tanford-Roxby procedure. The selectionof the two sets was made on the basis of a criterion relatedto the interaction energy between the titratable sites in theprotein molecule. The algorithm was tested for bovine pancreatictrypsin inhibitor and the pK values calculated were discussedin the light of experimental data and theoretical results obtainedby other authors. The algorithm can easily be coded and incorporatedinto any program package for the calculation of electrostaticinteractions in proteins.     

Numerical simulation of backdraft phenomena

This paper reports preliminary computational fluid dynamics (CFD) simulations of backdraft observed in an experimental rig at Lund University. The analysis was performed with the CFX software using the Detached Eddy Simulation (DES) turbulence model, a hybrid of Large Eddy Simulation (LES) and RANS, in combination with the EDM combustion model. The DES model uses a RANS formulation in wall proximity to avoid computationally expensive grid resolution that is necessary for realistic LES predictions in wall layers.     

Metall-Matrix-Verbundwerkstoffe auf Eisenbasis

Metal-Matrix-Composites use a reinforcing phase to improve the mechanical properties of the matrix material or achieve a weight reduction. For example in iron and steel industrial applications typically carbides and borides are used to improve wear resistance. The intention of current investigations at the Chair of Metallurgy at the Montanuniversitaet Leoben is to produce a composite with reduced density and consistent or increased stiffness as steel. This paper reviews possible processing routes on steel composites with ceramic reinforcing phases based on a literature survey. A classification of the processing steps based on the origin of the ceramic phase is made and the advantages and disadvantages of these steps are summarized. Two tables are given to present the high amount of possible producing steps and the used investigation techniques for steel-based metal matrix composites.     

Production of High Purity Magnesium Alloys by Melt Purification with Zr

The efficacy of Zr in removing Fe from molten Mg‐X binary alloys was studied experimentally and using calculated phase diagrams. Zr is effective in reducing the Fe content from the Mg melt for Mg‐X binary alloys, X = Y, Si, Sn, Ca, Sr, Ce, Gd, Nd, Li, La, Mn, and Zn. Purification occurs by the precipitation from the melt of Fe rich precipitates, and the settling of the precipitates to the bottom of the melt. Any desired Fe content down to 1 ppm can be achieved by appropriate melt treatment.     

Animation model of Krško nuclear power plant for RELAP5 calculations

Today most software applications, also in the nuclear field, come with a graphical user interface. The first graphical user interface for the RELAP5 thermal-hydraulic computer code was called the Nuclear Plant Analyzer (NPA). Later, Symbolic Nuclear Analysis Package (SNAP) was developed. The purpose of the present study was to develop SNAP animation model of Krško nuclear power plant (NPP) for RELAP5 calculations with the aim to help analyze the results. In addition, the reference calculations for Krško full scope simulator validation were performed with the latest RELAP5/MOD3.3 Patch 03 code and compared to previous RELAP5 versions to provide verified source data, needed to demonstrate animation model. In total six scenarios were analyzed: two scenarios of the small-break loss-of-coolant accident, two scenarios of the loss of main feedwater, a scenario of the anticipated transient without scram, and a scenario of the steam generator tube rupture. The use of SNAP for animation of Krško nuclear power plant analyses showed several benefits, especially better understanding of the calculated physical phenomena and processes. It can be concluded that an animation tool was created, which enables to analyze very complex accident scenarios. The graphical surface helps keeping the overview and focusing on the main influences. Also, the use of such support tools to system codes may significantly contribute to better quality of safety analysis.     

pH-based one pot synthesis of biocompatible olive shaped inorganic particles

A novel, single-step, one-pot method for preparation of inorganic hollow particles is introduced. The concept is grounded on the classical theory of nucleation of growth and can be carried out entirely at room temperature. Starting from an appropriate solution, precipitation and selective dissolution of inorganic nanoparticles are triggered by continuous addition of a salt while carefully controlling the pH. The approach is demonstrated on the example of hollow calcium phosphate particles using calcium carbonate solid nanoparticles as a template. The proposed synthesis procedure is simple and cheap and can be extended to other biocompatible compounds. It also can be upgraded with an additional in situ step.