Introduction.Electrical resistivity is an important material characteristic in the field of electrical engineering and material science. There are several methods that can be used to measure ...resistance, like the 4-wire method which relates the resistance to a voltage drop at a given current flow, but to define the resistivity from the resistance value requires an analytical expression for the given system which requires a sufficient mathematical apparatus for describing complicated shapes. Therefore we use finite element method computations to compute the resistivity of a metal material. This approach has been already used for different materials like concrete and aluminum in the past. We then compare this method with an analytical expression that due to intuition could approximate the solution sufficiently. After that, the same material is used again to test the electrical isotropy of the sample. Novelty.A method is developed by combining the results of experimental studies and the results of mathematical modelling of the process of determining the electrical conductivity of metals. The goal is to describe and employ a method of measuring the electrical resistivity of metal objects of random shapes. Using this method, it is possible to measure the resistivity of materials without the need to manufacture them into wires or ribbons.Methods.The solution to the problem was carried out by the finite element method via the COMSOL Multiphysics 5.6 simulation program in a cartesian coordinate system and the resistance between two points of the metal sample was measured by the 4-wire method.Results.A similar resistance value was obtained when the measuring terminals were placed in different places. The difference between them was within 1,5 % and the obtained values were close to the values given by the literature for the electrical resistivity of electrical steels. Terminal size influences the measured conductivity and a max error of 5,2 % was estimated. Practical value. A method of estimating the resistivity of materials without the need to manufacture them into specific shapes, like wires or ribbons, for which analytical expressions between resistivity and resistance are easily derived.
The modulus of semicrystalline polymers mainly depends on two parameters of the crystalline structure, the crystallinity and the lamellae thickness. These parameters can be obtained from a single ...calorimetric melting curve, which makes it possible to predict the modulus from a calorimetric measurement. Our equation gives the relation between these two parameters and the elastic modulus. However, in polymers like polylactic acid (PLA), the cold crystallization influences the melting curve and hiders the simple evaluation. This work presents a novel method to eliminate the cold crystallization during the calorimetric measurements and determine the iterative constants needed for the modulus prediction. The crystalline structure of PLA was characterized by differential scanning calorimeter (DSC) and wide-angle X-ray scattering (WAXS) measurements. Tensile properties were determined by standardized tensile tests on injection molded specimens, which were annealed at different temperatures and times to achieve significantly different crystalline structures for the model's development.
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•Novel methods presented for the theoretical treatment of calorimetric data.•Modulus can be predicted from calorimetric melting curves for polymers with pronounced cold crystallization ability.•With a heating rate above 100 °C min−1, cold crystallization of PLA can be eliminated.•Extrapolating the average melting temperature to the heating rate of a standard DSC measurement is possible.
Synergistic extension of long-distance and local trails is a great opportunity to form unified networks with increased potential and attractiveness. This paper presents and analyses two recent hiking ...trail network extension projects in Northern Transdanubia, Hungary, as they relate to network structure and the variety of possible hiking tours. One features new local trail connections added to existing long-distance trails, resulting in a local network with various trip options. Another is an example of a new regional multi-day route created by extensions and connections to existing local trails. We present the motivations behind these extensions, the opportunities opened up by them, including their potential on conservation and development, by observing the layout of the resulting trail network and its connections to natural and man-made attractions and facilities. These typical synergistic trail developments reveal a set of good practices in network design which can be generalised and adapted to other regions and contexts.
The solvolysis of poly(ethylene-terephthalate) (PET) is one of the most researched areas in chemical recycling. In this study PET aminolysis with isophorondiamine has been done - in opposition to ...recent trends - without excess reagent and the raw reaction product was further used without purification. The aminolysis product was thoroughly characterized with nuclear magnetic resonance (NMR) spectroscopy. Isophoronediamine was used as a solvent to prepare amine crosslinker solutions for epoxy resins. The effect of the concentration on the cross-linking reaction and thermomechanical properties were investigated. The curing reaction was found to be significantly accelerated by the presence of the aminolysis product. Both the ethylene-glycol and the terephthal-amide-diamines have a catalytic effect on the reaction. The glass transition temperature decreased with increasing concentrations of the cross-linker solutions due to the decreasing cross-link density. Thus, raw aminolysis products can be utilized for epoxy curing and are advantageous in modifying slower curing cycloaliphatic cross linker systems.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, ODKLJ, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
This work demonstrates the most widely used characterization methods and techniques of the supermolecular and lamellar structure of semicrystalline polymers. Polarized optical microscopy (POM) ...equipped with a hot-stage (thermo-optical microscopy, TOM), brightfield microscopy (BF), darkfield microscopy (DF), digital image processing techniques, optical profilometry (OP), scanning electron microscopy (SEM), and atomic force microscopy (AFM) were used as investigation techniques. The same iPP grade was used with different sample preparation techniques to compare these methods. The advantages and drawbacks of the sample preparation and investigation methods were discussed. The results show how the introduced techniques could reveal different kinds of information, and it is also shown how the experimental techniques should be matched to the goals of a structural study.
•Comparison of experimental techniques and sample preparation used for the study of crystalline morphology in polymers.•It is shown how the experimental techniques should be matched to the goals of a structural study.•The importance and ways of etching and also the precautions to be taken during sample preparation are discussed.
Abstract Several compounds isolated from the plant Carpobrotus edulis were evaluated for their activity against multidrug-resistant (MDR) bacteria and their efflux pump systems. Amongst the compounds ...isolated, six compounds were tested, namely uvaol, β-amyrin, oleanolic acid, catechin, epicatechin and monogalactosyldiacylglycerol. Oleanolic acid presented high antibacterial activity against a large number of bacterial strains. The triterpene uvaol was the most active compound for modulation of efflux activity by MDR Gram-positive strains.
Shell structure and magic numbers in atomic nuclei were generally explained by pioneering work that introduced a strong spin-orbit interaction to the nuclear shell model potential. However, knowledge ...of nuclear forces and the mechanisms governing the structure of nuclei, in particular far from stability, is still incomplete. In nuclei with equal neutron and proton numbers (N = Z), enhanced correlations arise between neutrons and protons (two distinct types of fermions) that occupy orbitals with the same quantum numbers. Such correlations have been predicted to favour an unusual type of nuclear superfluidity, termed isoscalar neutron-proton pairing, in addition to normal isovector pairing. Despite many experimental efforts, these predictions have not been confirmed. Here we report the experimental observation of excited states in the N = Z = 46 nucleus (92)Pd. Gamma rays emitted following the (58)Ni((36)Ar,2n)(92)Pd fusion-evaporation reaction were identified using a combination of state-of-the-art high-resolution γ-ray, charged-particle and neutron detector systems. Our results reveal evidence for a spin-aligned, isoscalar neutron-proton coupling scheme, different from the previous prediction. We suggest that this coupling scheme replaces normal superfluidity (characterized by seniority coupling) in the ground and low-lying excited states of the heaviest N = Z nuclei. Such strong, isoscalar neutron-proton correlations would have a considerable impact on the nuclear level structure and possibly influence the dynamics of rapid proton capture in stellar nucleosynthesis.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Introduction
Parkinson’s disease (PD) has a complex genetic background involving both rare and common genetic variants. Although a small percentage of cases show a clear Mendelian inheritance ...pattern, it is much more relevant to identify patients who present with a complex genetic profile of risk variants with different severity. The ß-glucocerebrosidase coding gene (
GBA1
) is recognized as the most frequent genetic risk factor for PD and Lewy body dementia, irrespective of reduction of the enzyme activity due to genetic variants.
Methods
In a selected cohort of 190 Hungarian patients with clinical signs of PD and suspected genetic risk, we performed the genetic testing of the
GBA1
gene. As other genetic hits can modify clinical features, we also screened for additional rare variants in other neurodegenerative genes and assessed the APOE-ε genotype of the patients.
Results
In our cohort, we identified 29
GBA1
rare variant (RV) carriers. Out of the six different detected RVs, the highly debated E365K and T408M variants are composed of the majority of them (22 out of 32). Three patients carried two
GBA1
variants, and an additional three patients carried rare variants in other neurodegenerative genes (
SMPD1
,
SPG11
, and
SNCA
). We did not observe differences in age at onset or other clinical features of the patients carrying two
GBA1
variants or patients carrying heterozygous APOE-ε4 allele.
Conclusion
We need further studies to better understand the drivers of clinical differences in these patients, as this could have important therapeutic implications.
The objective of the paper is to shed light on the importance of the digital presentation of religious heritage and present the multimedia documentation of a chapel developed within the “Oltári Múlt” ...(“Sacred Past”, in Hungarian) project. It aims to preserve the values of medieval churches through video documentation. Walls and stones come alive for contemporary visitors, connecting the present with the past. The paper showcases an example of a chapel and how video documentation, virtual tours, and other ICT tools are applied in the project to create a digital narrative with a creative vision and mastermind approach.
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