DETECTION OF CLIMATE CHANGE IN THE SLOVAK MOUNTAINS

This paper is devoted to detection of some expected changes in the climatological regime (means, variability, frequency distribution) at selected elements due to climate change. Very reliable time series of daily data (air temperature and relative humidity since 1951) measured by the meteorological stations at Hurbanovo, 115 m a.s.l., SW Slovakia, Poprad, 695 m a.sl., at the foot of the High Tatras mountains and Lomnický štít, 2635 m a.s.l., the 3rd highest peak in Slovakia have been utilized. More over the daily aerological data measured at the Poprad-Gánovce Observatory since 1961 (850 hPa) were elaborated for comparisons with those obtained by ground measurements. Some results are compared also with those designed as climate change scenarios for Slovakia based on the modified CGCM2 GCM outputs. The results showed very significant increase in temperature and decrease in relative humidity in the April to August season after 1990. Only selected results are presented in this extended abstract

Coil combination of multichannel MRSI data at 7 T: MUSICAL

The goal of this study was to evaluate a new method of combining multi-channel 1H MRSI data by direct use of a matching imaging scan as a reference, rather than computing sensitivity maps. Seven healthy volunteers were measured on a 7-T MR scanner using a head coil with a 32-channel array coil for receive-only and a volume coil for receive/transmit. The accuracy of prediction of the phase of the 1H MRSI data with a fast imaging pre-scan was investigated with the volume coil. The array coil 1H MRSI data were combined using matching imaging data as coil combination weights. The signal-to-noise ratio (SNR), spectral quality, metabolic map quality and Cramér–Rao lower bounds were then compared with the data obtained by two standard methods, i.e. using sensitivity maps and the first free induction decay (FID) data point. Additional noise decorrelation was performed to further optimize the SNR gain. The new combination method improved significantly the SNR (+29%), overall spectral quality and visual appearance of metabolic maps, and lowered the Cramér–Rao lower bounds (−34%), compared with the combination method based on the first FID data point. The results were similar to those obtained by the combination method using sensitivity maps, but the new method increased the SNR slightly (+1.7%), decreased the algorithm complexity, required no reference coil and pre-phased all spectra correctly prior to spectral processing. Noise decorrelation further increased the SNR by 13%. The proposed method is a fast, robust and simple way to improve the coil combination in 1H MRSI of the human brain at 7 T, and could be extended to other 1H MRSI techniques. © 2013 The Authors. NMR in Biomedicine published by John Wiley & Sons, Ltd

Analysis of Thermal Effects in Infrared and Interference Microscopy: n-Butane-5A and Methanol-Ferrierite Systems

Recently, infrared and interference microscopy methods have been increasingly applied to measure internal concentration gradients and hence the uptake of different adsorbates in zeolite crystals. In contrast to conventional macroscopic batch uptake techniques, these microscopic/mesoscopic methods measure changes associated with single zeolite crystals. The analysis of data from these measurements to determine micropore diffusivities has been performed on the basis of the assumption that isothermal conditions prevail during both the adsorption and desorption experiments. This assumption is critically examined in this paper for the case of methanol diffusion in ferrierite crystals during adsorption and desorption to vacuum. It is shown by both detailed simulation as well as an order of magnitude analysis of time constants for heat transfer and diffusion that the temperature changes in the system are negligible during adsorption due to the high conductive heat transfer rate. However, during desorption to a vacuum, heat conduction is minimal so that heat transfer occurs only by radiation. Temperature changes as large as 5–7K are therefore to be expected at the beginning of the desorption process. However, since the time constant for the desorption process is of the order of hundreds of seconds, this temperature transient dissipates rapidly and has no significant impact on the overall desorption process. Even for the worst case scenario considered here, for both interference and infrared microscopy methods, the systems can be considered as essentially isothermal

Occurrence of the Portevin Le-Chatelier effect in open-cell microcellular Al-2 wt% Mg

Microcellular open-cell metal foams with pores of 75 or 400 pm in diameter and made of pure Al or Al-2 wt% Mg are tested in compression. The aluminum foam exhibits a typical smooth plastic flow and a positive strain rate sensitivity, whereas plastic instabilities and a negative strain rate sensitivity appear in the stress-strain curves of the Al-2 wt Mg foams, indicating the presence of the Portevin Le-Chatelier (PLC) effect. The effect is further confirmed by acoustic emission analysis.Taken together, the data indicate that the PLC effect is caused in this material by the sudden collective deformation of many struts across the material. (C) 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved

Anwendung von Interferenz- und IR-Mikroskopie zur Charakterisierung und Untersuchung des Stofftransportes in nanoporösen Materialien

Die Anwendung der Interferenz-Mikroskopie bedeutet einen entscheidenden Durchbruch in der Untersuchung des Stofftransports von Gastmolekülen in nanoporösen Wirtsmaterialien. Diese Technik ermöglicht die Beobachtung der zeitaufgelösten intrakristallinen Konzentrationsprofile, die durch eine Änderung des umgebenden Gasdruckes entstehen. Dieser Ansatz wurde zur Untersuchung von Adsorptions- und Desorptionsprozessen in verschiedenen Zeolithsystemen verwendet. Die Vorteile dieser Technik, vor allem wenn sie mit Infrarotabsorptionsmessungen kombiniert wird, werden an Hand der experimentellen Resultate des Methanol-in-Ferrierit-Systems illustriert