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  • Author: Ildiko Peter x
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Abstract

High-strength EN AW 7075 Al-based alloy (Al-Zn-Mg-Cu) is currently employed in many industrial fields where excellent mechanical performances of structural components are required. In contrast to the many positive features this alloy presents, it is not fusion weldable, because it is subjected to solidification and liquation cracking. In this paper, the possibility to weld low thickness plates, made of 7075 aluminum alloy, by the tungsten inert gas welding technique will be presented. Two types of welding have been performed: for the former one, welding involves only one surface, while for the second one, welding has been carried out on both faces of the plates. After welding, microstructural analysis and mechanical properties investigations have been carried out. The present research highlights that the mechanical properties evolution is affected by the welding procedure. In particular, the mechanical strength reached for the samples welded on both faces, in the proposed setting, is comparable to that of the un-welded alloys.

Abstract

This paper deals with the design of metamaterial (MTM) substrates to be used in electromagnetic devices. In particular, the approach has been considered for different investigations having the scope the realization of antennas on flexible substrates. The importance of the topic resides in the potential of conforming the antenna to/on desirable shapes. Flexibility is well exploitable either in advanced communication systems or in biomedical applications, just to mention some. The proposed MTM is made of metallic spherical inclusions of AISI52100, which are embedded in a polymer host. The paper aims to assess the feasibility of increasing the performance of a microstrip patch antenna, and to decrease its size by using the MTM substrate, which is able to locally control the permittivity of the substrate and to create electromagnetic band-gap regions outside of the patch.

Abstract

0.88Pb(Zr0.52Ti0.48)O3 – 0.12Pb(Mn1/3Sb2/3)O3 – 0,02 at%E piezoelectric ceramics, with E = Pr3+ were synthesized by using a conventional method, namely a solid state reaction technique. X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) were employed for the structural and microstructural investigations. Piezoelectric methods were used for the dielectric and piezoelectric properties determination. The results of XRD show a perovskite structure and XRD patterns, indexing on a tetragonal cell structure, was carried out for the most common phases. The SEM micrographs of the sintered compositions reveal a homogenous structure with a sharp or rounded grain boundary. The modified PZT ceramic presents still superior piezoelectric properties. Based on the results obtained, one can conclude that the analysed piezoelectric ceramics are useful for device applications.

Abstract

Mucosal capnometry involves the monitoring of partial pressure of carbon dioxide (PCO2) in mucous membranes. Different techniques have been developed and applied for this purpose, including sublingual or buccal sensors, or special gastrointestinal tonometric devices. The primary use of these procedures is to detect compensated shock in critically ill patients or patients undergoing major surgery. Compensatory mechanisms, in the early phases of shock, lead to the redistribution of blood flow towards the vital organs, within ostensibly typical macro-haemodynamic parameters. Unfortunately, this may result in microcirculatory disturbances, which can play a pivotal role in the development of organ failure. In such circumstances mucosal capnometry monitoring, at different gastrointestinal sites, can provide a sensitive method for the early diagnosis of shock. The special PCO2 monitoring methods assess the severity of ischaemia and help to define the necessary therapeutic interventions and testing of these monitors have justified their prognostic value. Gastrointestinal mucosal capnometry monitoring also helps in determining the severity of ischaemia and is a useful adjunctive in the diagnosis of occlusive splanchnic arterial diseases. The supplementary functional information increases the diagnostic accuracy of radiological techniques, assists in creating individualized treatment plans, and helps in follow-up the results of interventions. The results of a pilot study focusing on the interrelation of splanchnic perfusion and gastrointestinal function are given and discussed concerning recent advances in mucosal capnometry.

Abstract

Drought is one of the major abiotic stresses that frequently causes severe loss in crop yield worldwide. Laboratory predictors of field drought tolerance could significantly increase the effectiveness of existing plant breeding programs. In earlier field experiments, drought tolerance of 22 cultivated barley varieties has already been quantified. In order to develop laboratory markers of drought sensitivity, field drought tolerance data were correlated with parameters obtained in laboratory tests. Root and shoot length and weight were measured on control and PEG-treated (a simple laboratory drought model) seedlings. Significant correlations were found among root growth, shoot weight in laboratory stress conditions and field drought tolerance. Interestingly, a negative correlation was found between root length of the untreated seedlings and drought tolerance. Laboratory Drought Tolerance Index (DTI) was introduced as the linear combination of those laboratory parameters which were correlated with field drought tolerance. DTI showed good predictive value (r = 0.57, p < 0.05) for drought tolerance in field experiments and we suggest it for preselection of drought tolerant barley breeding lines and for the characterization of drought tolerance in general.

Abstract

Acceptance of genetically modified plants is restricted in EU by legislation, while the attitude of public is not favourable as well. Surveys show that knowledge about GM plants is getting increased. Newly developed strategies on GM safety for environment can be a crucial aspect for the (partial) acceptance in future. GM trees as non-edible plants might appear as more admissible, however, are relatively rarely discussed. We performed a comparative survey on knowledge and perception of GM forest trees among students at four Slovak universities. We also compared their responses between as well as with the outcome of similar cross-country survey in frames of the COST Action FP0905. The results point to very similar attitude of Slovak students when compared with students from other countries, no significant difference between responses of males and females, but also influence of age as well as orientation of their study (natural sciences vs. economy) on view of GM tree safety and placing on the market.

Abstract

The current findings show that positron emission tomography (PET), primarily developed for medical diagnostic imaging, can be applied in plant studies to analyze the transport and allocation of wide range of compounds labelled with positronemitting radioisotopes. This work is focused on PET analysis of the uptake and transport of 2-deoxy-2-fluoro[18F]-D-glucose (2-[18F]FDG), as a model of photoassimilates, in tissues of giant reed (Arundo donax L. var. versicolor) as a potential energy crop. The absorption of 2-[18F]FDG and its subsequent transport in plant tissues were evaluated in both acropetal and basipetal direction as well. Visualization and quantification of the uptake and transport of 2-[18F]FDG in plants immersed with the root system into a 2-[18F]FDG solution revealed a significant accumulation of 18F radioactivity in the roots. The transport rate in plants was increased in the order of plant exposure through: stem > mechanically damaged root system > intact root system. PET analysis in basipetal direction, when the plant was immersed into the 2-[18F]FDG solution with the cut area of the leaf of whole plant, showed minimal translocation of 2-[18F]FDG into the other plant parts. The PET results were verified by measuring the accumulated radioactivity of 18F by direct gamma-spectrometry.