First experiments to determine snow density from diffuse near-infrared transmittance

Snow density is one of the key properties to characterize a snow cover. We present diffuse near-infrared transmittance measurements with an integrating sphere setup in the laboratory. We analyze 8 snow samples taken from melt forms, decomposed, rounded, faceted and machine made snow. Reference measurements of specific surface area (optically equivalent grain size) and density are done by micro-computed tomography and used as input for transmittance calculations. A diffuse flux extinction model cannot be applied to simulate transmittance as our setup cannot be approximated by an infinite snow block thickness. Calculations with a more intricate radiative transfer model (DISORT) agree with our measurements within the estimated grain size and density variability for all probed natural snow types. Only our machine made snow shows a morphology which cannot be modeled by DISORT. Thus, our results show for the first time a direct experimental correlation between transmittance and snow specific surface area and density without the need for an empirical fitting parameter. We feel this to be an important step towards a possible high-resolution, quantitative optical measurement method to determine snow density in combination with an independent specific surface area measurement.     

Investigation of Phenolic Components of Hungarian Wines

Ninety-two wines from the southernmost wine-producing region in Hungary (Villány) were analyzed for their polyphenolic content by high performance liquid chromatography (HPLC). Our results show that wine variety or vintage year could not be distinguished based on polyphenol content, but winery origin could be. Resveratrol concentration is mainly dependent on variety and vintage year. The “human factor” (i.e., winemaking style and technology) seems to be more decisive for the polyphenolic composition of red wines than other factors, such as variety and vintage year.     

A polymer-based spiky microelectrode array for electrocorticography

The advanced technology of microelectromechanical systems (MEMS) makes possible precise and reproducible construction of various microelectrode arrays (MEAs) with patterns of high spatial density. Polymer-based MEMS devices are gaining increasing attention in the field of electrophysiology, since they can be used to form flexible, yet reliable electrical interfaces with the central and the peripheral nervous system. In this paper we present a novel MEA, designed for obtaining neural signals, with a polyimide (PI)—platinum (Pt)—SU-8 layer structure. Electrodes with special, arrow-like shapes were formed in a single row, enabling slight penetration into the tissue. The applied process flow allowed reproducible batch fabrication of the devices with high yield. In vitro characterization of the electrode arrays was performed with electrochemical impedance spectroscopy in lactated Ringer’s solution. Functional tests were carried out by performing acute recordings on rat neocortex. The devices have proven to be convenient tools for acute in vivo electrocorticography.     

The FOAMCARP process: foaming of aluminium MMCs by the chalk-aluminium reaction in precursors

A brief outline is presented of the factors involved in the search for gas-generating agents offering superior performance for foaming of liquid aluminium alloys. These include kinetic and thermodynamic characteristics of decomposition reactions, the ease of dispersion of the powdered foaming agent in the melt, the nature and likely effect of decomposition products on melt flow, potential reactions between the foaming gas and the melt and the availability, cost and ease of handling of the powder concerned. There is one very promising candidate material, calcium carbonate, which offers advantages compared to currently-employed hydride powders in virtually all aspects of their performance. It is shown that foams can be produced having appreciably finer cells (<1 mm diameter) and more uniform cell structures than currently-available melt route foams, a potentially lower ceramic content in the cell walls and dramatically reduced raw material costs. The presence of an oxidising foaming gas in the cells leads to reaction with the liquid cell surface, forming a continuous oxide film. The presence of this film has a significant effect on foam stabilisation, slowing down cell coalescence and melt drainage.