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Open access

Kamil Janeczek, Małgorzata Jakubowska, Grażyna Kozioł and Piotr Jankowski-Mihułowicz

Abstract

Temperature change is one of key factors which should be taken into account in logistics during transportation or storage of many types of goods. In this study, a passive UHF RFID-enabled sensor system for elevated temperature (above 58°C) detection has been demonstrated. This system consists of an RFID reader and disposable temperature sensor comprising an UHF antenna, chip and temperature sensitive unit. The UHF antenna was designed and simulated in an IE3D software. The properties of the system were examined depending on the temperature level, type of package which contains the studied objects and the type of antenna substrate.

Open access

Tadeusz Karamucki, Józefa Gardzielewska, Małgorzata Jakubowska, Kinga Rybak and Justyna Garczewska

Abstract

The purpose of this study was to analyse the colour of the breast muscles of Japanese Pharaoh quail on the first day after slaughter and again after further six days of cold storage, in relation to their muscle pH. The material for the study consisted of 40 breast muscles taken from the carcasses of six-week-old Japanese Pharaoh quail. Based on pH results, the muscles were divided into three groups: I (pH = 5.51-5.70), II (pH = 5.71-5.90) and III (pH = 5.91-6.10). After this the muscles were stored for a further 6 days at 4°C. It was found that the pH of freshly dissected quail breast muscle is a good indicator of the colour stability of muscles cold-stored at 4°C for six days. The lowest degree of colour stability was observed in the pH range 5.51-5.70. In the sensory evaluation muscles displaying this degree of colour instability were considered unacceptable or barely acceptable. In contrast, muscles in the pH ranges 5.71-5.90 and 5.91-6.10 displayed a high degree of colour stability and were considered acceptable in the sensory evaluation. The colour changes that occurred during storage of the muscles were due to changes in the values of all of the colour parameters (L*, a*, b*, C* and hº); however, the greatest changes were found in the case of redness (a*) and the hue angle (hº). The changes were caused both by alterations in the amount of pigment reached by light, and by changes in the relative amounts of the chemical forms of myoglobin.

Open access

Marcin Słoma, Małgorzata Jakubowska and Jakub Szałatkiewicz

Abstract

Superior electrical properties of carbon nanotubes were utilized by the authors in the fabrication of printed resistors. In common applications such as electrodes or sensors, only basic electrical and mechanical properties are investigated, leaving aside other key parameters related to the stability and reliability of particular elements. In this paper we present experimental results on the properties of printed resistive layers. One of the most important issues is their stability under high currents creating excessive thermal stresses. In order to investigate such behavior, a high direct current stress test was performed along with the observation of temperature distribution that allowed us to gain a fundamental insight into the electrical behavior at such operating conditions. These experiments allowed us to observe parametric failure or catastrophic damage that occurred under excessive supply parameters. Electrical parameters of all investigated samples remained stable after applying currents inducing an increase in temperature up to 130 °C and 200 °C. For selected samples, catastrophic failure was observed at the current values inducing temperature above 220 °C and 300 °C but in all cases the failure was related to the damage of PET or alumina substrate. Additional experiments were carried out with short high voltage pulse stresses. Printed resistors filled with nanomaterials sustained similar voltage levels (up to 750 V) without changing their parameters, while commonly used graphite filled polymer resistors changed their resistance value.

Open access

Łucja Dybowska-Sarapuk, Sławomir Rumiński, Grzegorz Wróblewski, Marcin Słoma, Anna Młożniak, Ilona Kalaszczyńska, Małgorzata Lewandowska-Szumieł and Małgorzata Jakubowska

Abstract

The aim of the study was to produce heterophasic graphene nanoplatelets based formulation designed for ink-jet printing and biomedical applications. The compositions should meet two conditions: should be cytocompatible and have the rheological properties that allow to apply it with ink-jet printing technique. In view of the above conditions, the selection of suspensions components, such as binder, solvent and surfactants was performed. In the first stage of the research the homogeneity of the dispersion of nanoplatelets and their sedimentation behaviour in diverse solutions were tested. Subsequently, the cytotoxicity of each ink on human mesenchymal stem cells was examined using the Alamar Blue Test. At the same time the rheology of the resulting suspensions was tested. As a result of these tests the best ink composition was elaborated: water, polyethylene glycol, graphene nanoplatelets and the surfactant from DuPont company.

Open access

Krzysztof Mleczko, Piotr Ptak, Zbigniew Zawiślak, Marcin Słoma, Małgorzata Jakubowska and Andrzej Kolek

Abstract

Graphene is a very promising material for potential applications in many fields. Since manufacturing technologies of graphene are still at the developing stage, low-frequency noise measurements as a tool for evaluating their quality is proposed. In this work, noise properties of polymer thick-film resistors with graphene nano-platelets as a functional phase are reported. The measurements were carried out in room temperature. 1/f noise caused by resistance fluctuations has been found to be the main component in the specimens. The parameter values describing noise intensity of the polymer thick-film specimens have been calculated and compared with the values obtained for other thick-film resistors and layers used in microelectronics. The studied polymer thick-film specimens exhibit rather poor noise properties, especially for the layers with a low content of the functional phase.

Open access

Jerzy Szałapak, Konrad Kiełbasiński, Jakub Krzemiński, Anna Młożniak, Elżbieta Zwierkowska, Małgorzata Jakubowska and Radosław Pawłowski

Abstract

The Low Temperature Joining Technique (LTJT) using silver compounds enables to significantly increase the thermal conductivity between joined elements, which is much higher than for soldered joints. However, it also makes difficult to measure the thermal conductivity of the joint. The Laser Flash Analysis (LFA) is a non-intrusive method of measuring the temperature rise of one surface of a specimen after excitation with a laser pulse of its other surface. The main limitation of the LFA method is its standard computer software, which assumes the dimensions of a bonded component to be similar to those of the substrate, because it uses the standard Parker’s formula dedicated for one-dimensional heat flow. In the paper a special design of measured specimen was proposed, consisting of two copper plates of different size joined with the sintered silver layer. It was shown that heat properties of these specimens can also be measured after modifying the LFA method. The authors adapted these specimens by masking the false heat signal sourced from the uncovered plate area. Another adaptation was introducing a correcting factor of the heat travel distance, which was calculated with heat-flow simulations and placed into the Parker’s formula. The heat-flow simulated data were compared with the real LFA measurement results, which enabled estimation of the joint properties, e.g. its porosity.