2018 - Repozytorium publikacji - Politechnika Gdańska

Pokaż publikacje z roku

Publikacje z roku 2018

Pokaż wszystkie

A New Approach to Chemical Recycling of Polyamide 6.6 and Synthesis of Polyurethanes with Recovered Intermediates
- Janusz Datta
- Kamila Błażek
- Marcin Włoch
- Radosław Bukowski
2018 Pełny tekst JOURNAL OF POLYMERS AND THE ENVIRONMENT
A new efficient method for the chemical decomposition of polyamide 6.6 by the glycolysis and amino-glycolysis processes was proposed. The glycolysis was conducted using the mass excess of ethylene glycol (EG) as a decomposing agent in the presence of a catalyst. Also, a mixture of EG and triethylenetetramine was used as another decomposing agent in the amino- glycolysis process. The described process of decomposition did not require the use of elevated pressure. The hydroxyl and amine numbers, rheology behavior and the presence of characteristic chemical groups in the obtained glycolysates and aminoglycolysates were determined in order to characterize the reaction products. The decomposition products were defined as non-Newtonian fluids that could be described by suitable mathematical models. The conducted studies showed that the properties of the obtained intermediates depend on the mass excess of the decomposing agent used. The resulting semi- products are suitable for reusing in the synthesis of polyurethanes, which has been confirmed by the exemplary synthesis. In the reaction, 10 and 15 wt% of commercial polyol were replaced with the recovered intermediates.
A New Approach to Stability Evaluation of Digital Filters
- Lukasz Grzymkowski
- Tomasz Stefański
2018 Pełny tekst
In this paper, a new numerical method of evaluating digital filter stability is presented. This approach is based on novel root-finding algorithms at the complex plane using the Delaunay triangulation and Cauchy's Argument Principle. The presented algorithm locates unstable zeros of the characteristic equation with their multiplicities. The proposed method is generic and can be applied to a vast range of systems. Verification of this method is presented with benchmarks that include integer-order and fractional-order digital filters.
A new method for real-time monitoring of volatiles in frying fumes using proton transfer reaction mass spectrometry with time-of-flight analyse
- Tomasz Majchrzak
- Wojciech Wojnowski
- Tomasz Dymerski
- Jacek Gębicki
- Jacek Namieśnik
2018 Pełny tekst MONATSHEFTE FUR CHEMIE
To safeguard the consumers’ well-being, it is necessary to develop novel methods for determination of carcinogens in food, including volatiles generated during frying. The currently used procedures for analysis of volatile fraction of vegetable oils are not based on real-time measurements and thus do not enable the determination of carcinogenic compounds in frying fumes; instead, only the headspace or liquid fraction is sampled. In this article, described is an approach in which proton transfer reaction mass spectrometry with time-of-flight analyser (PTR-TOFMS) was used for real-time monitoring of carcinogenic compounds generated during thermal degradation of rapeseed oil. Using PTR-MS, it was possible to monitor the concentration of known volatile carcinogens according to the International Agency for Research on Cancer (IARC), alongside BTEX compounds, acrolein, and selected aldehydes. Moreover, the applicability of several supervised data analysis methods for the classification of oil samples according to their degree of thermal degradation was presented, with best results obtained using the k-nearest neighbours algorithm. Proton transfer reaction mass spectrometry is a powerful technique for the determination of carcinogenic compounds generated during thermal degradation of edible oils. Further investigation of the chemical processes which occur during frying can lead to improvement of food safety.
A new tool for the evaluation of the analytical procedure: Green Analytical Procedure Index
- Justyna Płotka-Wasylka
2018 Pełny tekst TALANTA.The International Journal of Pure and Applied Analytical Chemistry
A new means for assessing analytical protocols relating to green analytical chemistry attributes has been developed. The new tool, called GAPI (Green Analytical Procedure Index), evaluates the green character of an entire analytical methodology, from sample collection to final determination, and was created using such tools as the National Environmental Methods Index (NEMI) or Analytical Eco-Scale to provide not only general but also qualitative information. In GAPI, a specific symbol with five pentagrams can be used to evaluate and quantify the environmental impact involved in each step of an analytical methodology, mainly from green through yellow to red depicting low, medium to high impact, respectively. The proposed tool was used to evaluate analytical procedures applied in the determination of biogenic amines in wine samples, and polycyclic aromatic hydrocarbon determination by EPA methods. GAPI tool not only provides an immediately perceptible perspective to the user/reader but also offers exhaustive information on evaluated procedures.
A new type of (TiZrNbTaHf)N/MoN nanocomposite coating: Microstructure and properties depending on energy of incident ions
- A.a. Bagdasaryan
- A. V. Pshyk
- L. E. Coy
- P. Konarski
- Maciej Miśnik
- V. I. Ivashchenko
- M. Kempiński
- N. R. Mediukh
- A. D. Pogrebnjak
- V. M. Beresnev
- S. Jurga
2018 COMPOSITES PART B-ENGINEERING
A novel (TiZrNbTaHf)N/MoN nanocomposite coatings, which consist of the nitride of the high-entropy alloy and the binary nitride, were synthesized by vacuum-arc deposition at various substrate biases. The elemental composition, chemical bonding state, phase structure, microstructure and mechanical properties of the coatings were studied by high-resolution experimental methods: SIMS, GDMS, XPS, XRD, HR-TEM and nano-indentation. It was found that the chemical state of the (TiZrNbTaHf)N/MoN coatings has a complex nature, which consist of a mixture of nitrides of constituting elements. It was also shown that the coatings are based on B1 NaCl-structured γ-Mo2N-phase with a mixture of crystallographic orientations (111), (200), (220) and (311) together with the B1 NaCl-structured (TiZrNbTaHf)N solid-solution phase. First-principles calculations demonstrated that the metal sub-lattice of the (TiZrNbTaHf)N solid solution can be based on Ti1-xHfyTa1-x-y, Zr1-xHfyTa1-x-y, Zr0.25Ti0.25Ta0.5 ternary alloys, which have the lowest mixing energy. The HR-TEM results showed that the nanocomposite nitride coatings have nano-scale multilayer structure with modulation periods ranged from 20 nm to 25 nm. The maximum hardness of approximately 29 GPa demonstrated the coating deposited at a higher energy condition (−200 V) with the thinnest modulation period of bilayer of 20 nm (15 nm of (TiZrNbTaHf)N and 5 nm of Mo2N).
A new viscoelastic method of calculation of low-temperature thermal stresses in asphalt layers of pavements
- Józef Judycki
2018 International Journal of Pavement Engineering
The paper presents a new method of calculation of thermal stresses in asphalt layers of pavements induced by cooling or heating. The method, developed by the author, is based on the analytical solution for the linear viscoelastic Burgers model extended numerically for the case of asphalt layers whose rheological parameters are strongly dependent on temperature. The coefficient of thermal expansion and Poisson’s ratio may optionally be taken either as constant or varying with temperature. Two equivalent numerical methods have been developed, named as ‘the incremental method’ and ‘the stress increase and relaxation method’. The computer program was developed for calculation of thermal stresses in several different cases of temperature impact, included constant rate cooling and heating, change of temperature and relaxation and a cycle of first cooling, relaxation and second cooling. What the most important practically, the solution for any change of temperature, modelling real winter changes in long period of time, was also developed. Several examples of calculations are presented. The results obtained with use of this method are promising and appear to be acceptable. The advantages of the new method in comparison with existing methods are that it takes fully into account the viscoelastic properties of a layer and the method is correct if the material does not meet the time–temperature superposition principle.
A Nonlinear Model of a Mesh Shell
- Victor Eremeev
2018 Pełny tekst Mechanics of Solids
For a certain class of elastic lattice shells experiencing finite deformations, a continual model using the equations of the so-called six-parameter shell theory has been proposed. Within this model, the kinematics of the shell is described using six kinematically independent scalar degrees of freedom — the field of displacements and turns, as in the case of the Cosserat continuum, which gives reason to call the model under consideration as the theory of micropolar shells. Nonlinear equations of state for the surface energy density of the shell deformation are derived. The obtained relations of the continuum model are a special case of the general defining relations of elastic micropolar shells for finite deformations.
A Note on Knowledge Management Education: Towards Implementing Active Learning Methods
- Mieczysław Owoc
- Paweł Weichbroth
2018 Pełny tekst
Knowledge Management as an area of education is still a big challenge for teachers and practitioners. Nevertheless, there are several useful teaching methods in active education, especially oriented towards courses where innovation and delivering dynamic knowledge are critical. The goal of the paper is to present and discuss criteria relevant in the selection of active educational methods supporting knowledge management courses. Examples of real cases from business schools seem to confirm the usefulness of a learner-centered approach.
A Note on Reduced Strain Gradient Elasticity
- Victor Eremeev
- Francesco dell'Isola
2018
We discuss the particular class of strain-gradient elastic material models which we called the reduced or degenerated strain-gradient elasticity. For this class the strain energy density depends on functions which have different differential properties in different spatial directions. As an example of such media we consider the continual models of pantographic beam lattices and smectic and columnar liquid crystals.
A novel analytical approach in the assessment of unprocessed Kaffir lime peel and pulp as potential raw materials for cosmetic applications
- Martyna Lubinska-Szczygeł
- Anna Różańska
- Tomasz Dymerski
- Jacek Namieśnik
- Elena Katrich
- Shela Gorinstein
2018 INDUSTRIAL CROPS AND PRODUCTS
Volatile fraction of fruits is a rich source of bioactive and aroma compounds, which can be used in the cosmetics industry after meeting relevant criteria. This is particularly evident in citrus fruits, especially in Citrus hystrix, in which the headspace consists mainly of terpenes. Due to the insufficient sensitivity of analytical methods, essential oils are used in investigations in contrast to fresh fruits. Therefore, a novel approach in the assessment of unprocessed Citrus hystrix was proposed for the first time. It was proven that the application of two-dimensional gas chromatography coupled with time-of-flight mass spectrometry combined with solid phase microextraction gives reliable results in this context. Quantitation of key aroma compounds (α-pinene, limonene, citronellal, linalool, terpinen-4-ol, myrcene, α-terpineol, and citral), in the peel and pulp of fruit after prior assessment of bioactive properties measured as total phenolic content, ferric-reducing/antioxidant power and binding to human serum albumin, gives opportunity to use Citrus hystrix as a raw material in the cosmetic industry. Terpinen-4-ol and citronellal appeared to be the most important constituents of Citrus hystrix with the highest concentrations in the peel (34.58 ± 0.75 μg/g) and pulp (66.02 ± 0.85 μg/g), respectively. Polyphenols and antioxidant activities and binding properties revealed approximately twice higher bioactivity of Kaffir lime peel than pulp. Fluorescence studies of interaction of polyphenol extracts and some volatile standards with human serum albumin (HSA) showed relatively high binding properties and the correlation between biological activity and the volatile composition. Terpenes are primarily used as components of the fragrances of new perfumes and also as additives to creams, lotions or shampoos. The natural origin of terpenes is recommended in cosmetics industry.
A Novel Bitrate Adaptation Method for Heterogeneous Wireless Body Area Networks
- Krzysztof Cwalina
- Sławomir Ambroziak
- Piotr Rajchowski
- Jarosław Sadowski
- Jacek Stefański
2018 Pełny tekst Applied Sciences-Basel
In the article, a novel bitrate adaptation method for data streams allocation in heterogeneous Wireless Body Area Networks (WBANs) is presented. The efficiency of the proposed algorithm was compared with other known algorithms of data stream allocation using computer simulation. A dedicated simulator has been developed using results of measurements in the real environment. The usage of the proposed adaptive data streams allocation method by transmission rate adaptation based on radio channel parameters can increase the efficiency of resources’ usage in a heterogeneous WBANs, in relation to fixed bitrates transmissions and the use of well-known algorithms. This increase of efficiency has been shown regardless of the mobile node placement on the human body.
A novel calibration method for RSS-based DoA estimation using ESPAR antennas
- Marek Płotka
- Michał Tarkowski
- Krzysztof Nyka
- Łukasz Kulas
2018
In this paper, we introduce a new calibration method that can successfully be used in direction of arrival (DoA) estimation using electronically steerable parasitic array radiator (ESPAR) antennas and employing power-pattern cross-correlation (PPCC) algorithm, which relies on received signal strength (RSS) values recorded at the antenna output port. Instead of the commonly used two-step approach, during which ESPAR antenna calibration is performed and then the overall DoA estimation accuracy is measured, a single setup, which allows simultaneous calibration and verification, has been proposed. Measurement results indicate that the new calibration method reduces the total time required for calibration and verification in RSS-based DoA estimation using ESPAR antennas, which makes this approach easily applicable in practical wireless sensor network (WSN) deployments saving the time and associated costs required for system implementations, where the number of WSN nodes can easily reach hundreds.
A novel chemiluminescent immunoassay based on original acridinium ester labels as better solution for diagnosis of human toxoplasmosis than conventional ELISA test
- Lucyna Holec-Gąsior
- Bartłomiej Ferra
- Justyna Czechowska
- Illia E. Serdiuk
- Karol Krzymiński
2018 DIAGNOSTIC MICROBIOLOGY AND INFECTIOUS DISEASE
Toxoplasma gondii infection is one of the most common human zoonosis. Laboratory diagnosis of this disease is mainly based on the results of serological methods detecting speciﬁc antibodies in the patient’s sera. In this study we aimed to evaluate the performance of a chemiluminescence immunoassay (CLIA) based on the use of a novel immunochemical reagent in the form of the conjugate of original acridinium label (AL) attached to secondary antibody (IgG-AL) and SAG2-GRA1-ROP1L chimeric antigen for T. gondii speciﬁc antibodies detection. The CLIA test was compared with conventional ELISA, which was based on the same recombinant antigen and differed only in terms of the detection methodology of immune complexes. The new CLIA assay proved to be more sensitive and better differentiated sera of patients with T. gondii infection from sera of healthy individuals, being a promising alternative to more labor, cost-demanding and less versatile ELISA as screening test in toxoplasmosis diagnostics.
A novel dual-band rectifier circuit with enhanced bandwidth for RF energy harvesting applications
- Tologon Karataev
- Adrian Bekasiewicz
- Sławomir Kozieł
2018 Pełny tekst
In recent years, a rapid development of low-power sensor networks, enabling machine-to-machine communication in applications such as environmental monitoring, has been observed. Contemporary sensors are normally supplied by an external power source, typically in a form of a battery, which limits their lifespan and increases the maintenance costs. This problem can be addressed by harvesting and converting ambient RF energy into DC power. In the paper, a novel dual-band rectifier circuit with high efficiency and enhanced bandwidth for RF energy harvesting applications is proposed along with its design procedure. The rectifier consists of two branches fed through a junction and two voltage doublers with a common DC output. The proposed structure is designed to work in 0.6 GHz to 1 GHz and 1.75 GHz to 2.45 GHz ranges with an average RFto-DC conversion efficiency of at least 50 percent. Compact dimensions of 19 mm × 17 mm (a footprint of only 345 mm2) have been obtained through appropriate folding of the impedance transformers. As demonstrated, the proposed design outperforms state-of-the-art rectifiers in terms of the operational bandwidth, efficiency, and the range of acceptable load impedances.
A novel microstrip dual-layer rat-race coupler with compact size and enhanced bandwidth
- Adrian Bekasiewicz
- Sławomir Kozieł
2018 Pełny tekst
Microwave hybrid couplers are crucial components of mixers, phase shifters, amplifiers and other high-frequency systems. Conventional couplers are characterized by large size which limits their usefulness in modern applications. In this work, a novel compact rat-race coupler with enhanced bandwidth has been proposed. The structure consists of six compact microstrip resonant cells. It is implemented on two separate layers which permits further size reduction as compared to single-layer topologies. The size of the optimized structure is only 15.3 mm ×19.5 mm (footprint of 297 mm2). The coupler is characterized by 300 MHz bandwidth (symmetrical w.r.t. 1 GHz operating frequency) and nearly perfect power split at the center frequency. The coupler has been favorably compared to state-of-the-art compact structures reported in the literature.
A novel one-variable first-order shear deformation theory for biaxial buckling of a size-dependent plate based on Eringen’s nonlocal differential law
- Mohammad Malikan
- Van Bac Nguyen
2018 Pełny tekst World Journal of Engineering
Purpose – This paper aims to present a new one-variable first-order shear deformation theory (OVFSDT) using nonlocal elasticity concepts for buckling of graphene sheets. Design/methodology/approach – The FSDT had errors in its assumptions owing to the assumption of constant shear stress distribution along the thickness of the plate, even though by using the shear correction factor (SCF), it has been slightly corrected, the errors have been remained owing to the fact that the exact value of SCF has not already been accurately identified. By using two-variable first-order shear deformation theories, these errors decreased further by removing the SCF. To consider nanoscale effects on the plate, Eringen’s nonlocal elasticity theory was adopted. The critical buckling loads were computed by Navier’s approach. The obtained numerical results were then compared with previous studies’ results using molecular dynamics simulations and other plate theories for validation which also showed the accuracy and simplicity of the proposed theory. Findings – In comparing the biaxial buckling results of the proposed theory with the two-variable shear deformation theories and exact results, it revealed that the two-variable plate theories were not appropriate for the investigation of asymmetrical analyses. Originality/value – A formulation for FSDT was innovated by reconsidering its errors to improve the FSDT for investigation of mechanical behavior of nanoplates.
A pilot study with flow mediated skin fluorescence: A novel device to assess microvascular endothelial function in coronary artery disease
- Maria Tarnawska
- Karolina Dorniak
- Mariusz Franciszek Kaszubowski
- Marian Dudziak
- Marcin Hellmann
2018 Pełny tekst Cardiology Journal
Background: Endothelial dysfunction is one of the earliest vascular manifestations in the pathogenesis of cardiovascular disease. Noninvasive, simple and inexpensive methods of endothelial function assessment are therefore needed. Methods: Microvascular endothelial function was assessed in coronary artery disease (CAD) patients by flow mediated skin fluorescence (FMSF), based on measurements of NADH fluorescence intensity during brachial artery occlusion (ischemic response [IRmax]) and immediately after occlusion (hyperemic response [HRmax]). Additionally, plasma levels of asymmetric dimethylarginine (ADMA) and endothelin-1 (ET-1) were measured to assess the association between biochemical markers and microvascular function evaluated in vivo by FMSF. Results: A significant inverse correlation was found between ADMA levels and hyperemic response (r = –0.534, p = 0.003), while ET-1 levels were inversely related to the ischemic response (r= –0.575, p = 0.001). Both IR and HR were found lowest in patients with advanced CAD and diabetes. When the repeatability of the method was tested, the intraclass correlation coefficient for IRmax and HRmax were 0.985 (p < 0.001) and 0.914 (p < 0.001), respectively. Moreover, in Bland and Altman analysis, both variables IRmax and HRmax showed good agreement in repeated measurements. Conclusions: In this pilot study, it was demonstrated that NADH fluorescence measured by FMSF device in CAD patients was associated with established plasma endothelial markers, and that both ischemic and hyperemic response were blunted in patients with advanced disease and diabetes. Furthermore, FMSF device showed excellent repeatability and good agreement for repeated measurements. However, further study is warranted to confirm these results in a larger patient cohort.
A pin-on-disc study of airborne wear particle emissions from studded tyre on concrete road contacts
- Ulf Olofsson
- Minghui Tu
- Oleksii Nosko
- Yezhe Lyu
- Senad Dizdar
2018 WEAR
Studded tyres wear surfaces of winter roads, generating inhalable airborne particles. In this study, four concrete road materials and two stud geometries were investigated in terms of wear, road material hardness and airborne particle concentration. The sliding contact between studded tyres and road materials was studied using a pin-on-disc machine in a clean chamber. The results show that the normal load and the stud size have a large influence on the wear and particle emission. It was found that the wear and particle concentration are inversely proportional to the hardness of the aggregate in the road material and proportional to the sliding distance. The particle size distribution has peaks at 0.2 μm, 1 μm and 2 μm.
A random signal generation method for microcontrollers with DACs
- Zbigniew Czaja
- Michał Kowalewski
2018 Pełny tekst Metrology and Measurement Systems
A new method of noise generation based on software implementation of a 7-bit LFSR based on a common polynomial PRBS7 using microcontrollers equipped with internal ADCs and DACs and a microcontroller noise generator structure are proposed in the paper. Two software applications implementing the method: written in ANSI C and based on the LUT technique and written in AVR Assembler are also proposed. In the method the ADC results are used to reseed the LFSR after its each full work cycle, what improves randomness of generated data, which results in a greater similarity of the generated random signal to white noise, what was confirmed by the results of experimental research. The noise generator uses only the internal devices of the microcontroller, hence the proposed solution does not introduce hardware redundancy to the system.
A rapid and sensitive method for the quantitative analysis of ibuprofen and its metabolites in equine urine samples by gas chromatography-tandem mass spectrometry
- Emilia Waraksa
- Mateusz Kacper Woźniak
- Ewa Kłodzińska
- Robert Wrzesień
- Barbara Bobrowska-Korczak
- Jacek Namieśnik
2018 JOURNAL OF SEPARATION SCIENCE
Ibuprofen is widely used in human and veterinary medicine for the treatment of chronic pain as well as rheumatic and musculoskeletal disorders. However, t he anal- gesic and anti-inﬂammatory properties of Ibuprofen have contributed to frequent drug abuse in equestr ian s ports. A sensitive and rapid gas chromatography with tandem mass spectrometry based method with a simple liquid-liquid extraction and deriva- tization requiring 200 μL volume of sample and 2 mL of extraction solvent for the simultaneous determination of ibuprofen and its metabolites was developed. The pro- posed procedure was optimized and validated according to the principles for bioana- lytical methods. The assay achieved satisfactory validation parameters, namely, recov- ery (92.2–105%), interday accuracy (92.5–106%), and precision (0.3–4.4%) for all investigated compounds as well as limits of quantiﬁcation of 50 ng/mL for ibuprofen, 2-hydroxyibuprofen, and carboxyibuprofen, 25 ng/mL for 1-hydroxyibuprofen and 100 ng/mL for 3-hydroxyibuprofen. The applicability of the method was evaluated by the analysis of ﬁve real urine samples collected from diﬀerent horses after drug administration. In view of the low limits of quantiﬁcation, high selectivity, repeata- bility, and recovery, t he procedure can be utilized for laboratory applications, includ- ing the control of ibuprofen abuse in equestrian sports for anti-doping purposes and drug/pharmaceutical mentality investigations.