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  • Author: Ján Novák x
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Abstract

This paper contains the results of the electric properties measurement of lentil set. Electric measurements with use of these materials are of fundamental importance in relation to the analysis of quantity of absorbed water and dielectric heating characteristics. The aim of this paper was to perform the measurements of conductivity, dielectric constant and loss tangent on samples of lentil, the electrical properties of which had not been sufficiently measured. Measurements were performed under various moisture contents, and the frequency of electric field ranged from 1 MHz to 16 MHz, using a Q meter with coaxial probe. It was concluded that conductivity, relative permittivity and loss tangent increased with an increase in moisture content, and dielectric constant and loss tangent decreased as the frequency of electric field increased.

Abstract

This work contains the results of measuring the electrical properties of popcorn grains. Interest in electrical properties of biological materials resulted in engineering research in this field. The results of measurements are used for determining the moisture content, the surface level of liquid and grainy materials, for controlling the presence of pests in grain storage, for a quantitative determination of mechanical damage, in applications of dielectric heating, and in many other cases. Electrical measurements on these materials are of fundamental importance in relation to the analysis of quantity of absorbed water and dielectric heating characteristics. It is a well-known fact that electrical properties of materials, namely dielectric constant and conductivity, are affected by the moisture content of material. This fact is important for the design of many commercial moisture-testing instruments for agricultural products. The knowledge of dielectric properties of materials is necessary for the application of dielectric heating. The aim of this work was to perform the measurements of conductivity, dielectric constant and loss tangent on samples of popcorn grains, the electrical properties of which had not been sufficiently measured. Measurements were performed under variable moisture content and the frequency of electric field in the range from 1 MHz to 16 MHz, using a Q meter with a coaxial probe. It was concluded that conductivity, dielectric constant and loss tangent increased with increase of moisture content, and dielectric constant and loss factor decreased as the frequency of electric field increased.

Abstract

This work contains the results of measuring the electrical properties of sunflower achenes. The interest in electrical properties of biological materials resulted in engineering research in this field. The results of measurements are used for determining the moisture content, the surface level of liquid and grainy materials, for controlling the presence of pests in grain storage, for the quantitative determination of mechanical damage, in the application of dielectric heating, and in many other areas. Electrical measurements of these materials are of fundamental importance in relation to the analysis of quantity of absorbed water and dielectric heating characteristics. It is a well-known fact that electrical properties of materials, namely dielectric constant and conductivity, are affected by the moisture content of material. This fact is important for the design of many commercial moisturetesting instruments for agricultural products. The knowledge of dielectric properties of materials is necessary for the application of dielectric heating. The aim of this work was to measure conductivity, dielectric constant and loss tangent on samples of sunflower achenes, the electrical properties of which had not been sufficiently measured. Measurements were performed under variable moisture content and the frequency of electric field ranging from 1 MHz to 16 MHz, using a Q meter with coaxial probe. It was concluded that conductivity, dielectric constant and loss tangent increased with increasing moisture content, and dielectric constant and loss tangent decreased as the frequency of electric field increased.

Abstract

Many induction heating processes must be controlled in accordance with the prescribed time evolution of temperature of the heated body (bodies). This requires a correct setting of field currents (amplitudes and frequencies) in the heating inductors that can vary either continuously or by steps. The paper presents a novel model of induction annealing of cylindrical aluminum billets based on solution of nonstationary forward and inverse tasks. The methodology is described in detail and illustrated with a typical example. Some of the results were verified experimentally.

Abstract

Ventricular septal rupture is a potentially fatal complication of acute myocardial infarction. The key to management of this critical condition is an aggressive approach to haemodynamic stabilization and surgical closure of the rupture. Where there is a small rupture and the patient is in a haemodynamically stable condition, surgery can be delayed with the prospect of achieving better perioperative results. However, in unstable critically ill patients either immediate surgery or extracorporeal membranous oxygenation support and delayed surgery is indicated. In some patients, trans-catheter closure may be considered as an alternative to surgery.

Abstract

Vegetation of the ski slopes in the Low Tatras National Park in Slovakia was evaluated through the environmental variables and species composition caused by human impact assessment. We compared the grasslands located on pistes, off pistes and on the edge of pistes, and within these we also recorded the grassland management. The results show that the majority of study areas managed by transport of sod clippings has reached the lowest number of species; contrariwise, the grasslands with no management are characterized by the highest number of species. Areas on pistes managed by cutting correlates positively with the bare ground. Cover of mosses positively correlates with the total cover and areas with no management. Total of 17 synanthropic plant species and 2 nonnative species as the indicator of human interventions were noticed. They occurred particularly on the edge areas but also in the surroundings of the off piste areas.

Abstract

The paper is focused on analyses of dark copper patina defects that were formed on one sheet under the same conditions. Roofs of ten historical buildings were studied by image analysis and samples of two roofs were subjected to more detailed destructive analysis. These samples were studied by means of scanning electron microscopy with energy dispersive X-ray spectroscopy, X-ray diffraction and infrared spectroscopy. Both types of patina are composed of brochantite. Green patinas consisted of a pure brochantite and they had a fl at and compact surface. Conversely, black patina contained a high degree of impurities (ammonia cations, nitrates, silicates) and the surface was rough. The proportion of dark patina was higher in south and east facing surfaces, where washing by rainfall is more difficult.

Epitaxial Growth of GaP/InxGa1-xP (x In ≥ 0.27) Virtual Substrate for Optoelectronic Applications

Compositionally graded epitaxial semiconductor buffer layers are prepared with the aim of using them as a virtual substrate for following growth of heterostructures with the lattice parameter different from that of the substrates available on market (GaAs, GaP, InP or InAs). In this paper we report on the preparation of the step graded InxGa1-xP buffer layers on the GaP substrate. The final InxGa1-xP composition x In was chosen to be at least 0.27. At this composition the InxGa1-xP band-gap structure converts from the indirect to the direct one and the material of such composition is suitable for application in light emitting diode structures. Our task was to design a set of layers with graded composition (graded buffer layer) and to optimize growth parameters with the aim to prepare strain relaxed template of quality suitable for the subsequent epitaxial growth.

Abstract

Purpose

The purpose of this study was to translate the low anterior resection syndrome (LARS) score into Slovenian and to test its validity on Slovenian patients who underwent low anterior rectal resection.

Methods

The LARS score was translated from English into Slovenian and then back-translated following international recommendations. The Slovenian version of the LARS questionnaire was completed by patients who underwent low anterior rectal resection between 1 January 2006 and 31 December 2010 at the University Medical Centre Ljubljana. An anchor question assessing the impact of bowel function on lifestyle was included. To assess test-retest reliability, some of the patients answered the LARS score questionnaire twice.

Results

A total of 100 patients (66.7%) of the 150 patients who were contacted for participation, were included in the final analysis. A total of 58 patients reported major LARS score. The LARS score was able to discriminate between patients who received radiotherapy and those who did not (p<0.001), and between total and partial mesorectal excision (p<0.001). Age was not associated with a greater LARS score (p=0.975). There was a perfect fit between the QoL category question and the LARS score in 66.0% of cases and a moderate fit was found in 24.0% of the cases, showing good convergent validity. Test-retest reliability of 51 patients showed a high intraclass correlation coefficient of 0.86.

Conclusions

The Slovenian translation of the LARS score is a valid tool for measuring LARS.

Abstract

Coronary angiography is still the most widely used method for the assessment of lumen of coronary arteries and for diagnosis and treatment of coronary artery disease. New imaging modalities of coronary arteries play an increasing role in interventional cardiology. Intravascular ultrasound (IVUS) is the oldest technology, however due to its high tissue penetration remains very important for imaging of left main coronary artery and saphenous vein grafts. IVUS was used in many clinical trials and clinical experience with it is huge. Optical coherence tomography (OCT) is a new, very fast developing method. It has ten times higher axial resolution than IVUS. It gives us the opportunity to assess the inner structures of coronary artery wall, to evaluate the characteristics of atherosclerotic plaques, quality of stent implantation and its healing. It helps us to find the culprit lesion of acute coronary syndrome in some cases, to diagnose the cause of stent thrombosis, and to evaluate stent apposition which has a direct relation to prognosis. We use it to perform complex percutaneous coronary interventions and after heart transplantation to diagnose the vascular graft disease. We strongly believe that OCT is important for the assessment of plaque instability and patient´s prognosis. Near infrared spectroscopy combined with IVUS can distinguish fibrous from lipid core plaques. Lipid core burden index is in relation to a risk of periprocedural myocardial infarction and to prognosis. It is the only method which can sufficiently detect the amount of lipids in coronary wall.