Publications Repository - Gdańsk University of Technology

Page settings

polski
Publications Repository
Gdańsk University of Technology

Show publications from the year

Recent items

  • EFEKTYWNOŚĆ EKONOMICZNA HYBRYDOWEJ MIKROINSTALACJI OZE
    • Elżbieta Bogalecka
    • Zbigniew Krzemiński
    2019 Full text Zeszyty Naukowe Wydziału Elektrotechniki i Automatyki Politechniki Gdańskiej

    W artykule przedstawiono warunki pracy mikroelektrowni hybrydowej zainstalowanej w małej firmie mieszczącej się na terenie przemysłowym. Pokazano strukturę i parametry elektrowni składającej się z paneli fotowoltaicznych i elektrowni wiatrowej. Przeanalizowano odbiorniki energii oraz warunki pobierania mocy biernej. Dla wybranego okresu czasu pokazano zużycie oraz produkcję energii elektrycznej i energię zużytą na potrzeby firmy oraz oddaną do sieci. Na podstawie cen energii określono czas zwrotu nakładów inwestycyjnych już poniesionych. Zbadano celowość modernizacji przekształtników w elektrowni polegającej na wymianie tranzystorów IGBT na tranzystory SiC i celowość zakupu magazynu energii. Wykazano, że poniesione nakłady zwrócą się po ponad 10 latach. Nieuchronny wzrost cen energii spowoduje skrócenie czasu zwrotu nakładów inwestycyjnych do mniej niż 10 lat.

  • Efektywność przewodowego transportu paliw gazowych. Część 1
    • Waldemar Kamrat
    • Adam Kielak
    2019 Full text Ciepłownictwo, Ogrzewnictwo, Wentylacja

    W pracy przeprowadzono badanie możliwości podwyższenia efektywności transportu rurociągowego gazu ziemnego. Przeanalizowano różnorodne aspekty z zakresu procedur projektowania. Zaproponowano modele określania kosztów kapitałowych (inwestycyjnych) i kosztów zmiennych. Określono równania jednostkowych kosztów całkowitych (rocznych), które poddano „quasi-optymalizacji”, w celu wyznaczenia średnic racjonalnych dla gazociągów.

  • Efektywność przewodowego transportu paliw gazowych. Część 2
    • Waldemar Kamrat
    • Adam Kielak
    2019 Full text Ciepłownictwo, Ogrzewnictwo, Wentylacja

    W pracy przeprowadzono badanie możliwości podwyższenia efektywności transportu rurociągowego gazu ziemnego. Przeanalizowano różnorodne aspekty z zakresu procedur projektowania. Zaproponowano modele określania kosztów kapitałowych (inwestycyjnych) i kosztów zmiennych. Określono równania jednostkowych kosztów całkowitych (rocznych), które poddano „quasi-optymalizacji”, w celu wyznaczenia średnic racjonalnych dla gazociągów.

  • Effect of aeration of antibiotic-loaded bone cement on its properties and bactericidal effectiveness
    • Anna Pałubicka
    • Jakub Czubek
    • Marcin Wekwejt
    2019 Full text Minerva Ortopedica E Traumatologica

    BACKGROUND: Antibiotic-loaded bone cements are now widely used in medicine. They are able to locally deliver antibiotic particles and they allow treat or protect against infection. It is assumed that the bactericidal effectiveness of bioactive bone cements depend on the parameters of its production. Hence, the aim of this study was to check the effect of aeration of bone cement before mixing the components on its properties as well as its effectiveness in combating infections. METHODS: The following research was carried out: preparation of specimens of commercially available bone cement with different aeration time, assessment of the obtained structure, porosity analysis, measurement of wettability, as well as, bactericidal tests (zone of bacterial growth inhibition and optical density of the bacterial solution). RESULTS: The results show that the process of aeration of bone cement improve the open-pore structure of bone cement, its porosity and in effect enables better inhibition of bacterial growth. However, longer aeration time resulted in defects in the structure that may contribute to fatigue breaks. Future research should undertake a broader investigation of mechanical properties, determination of the released dose of antibiotic and potential optimization of the aeration process of bone cement. CONCLUSIONS: The additional step in the form of aeration during the production of bone cement enables to modify its structure and improvement of bactericidal properties, which will result in better infection treatment (in the so-called shock dose).

  • Effect of coarse grain aggregate on strength parameters of two-stage concrete
    • Farzam Omidimoaf
    • Ali M. Rajabi
    • Hakim S. Abdelgader
    • Marzena Kurpińska
    • Krzysztof Wilde
    2019 Full text Materiały Budowlane

    . Two-stage concrete (TSC) is a special type of concrete that the method of its construction and implementation is different from conventional one. In TSC, coarse aggregate particles are first placed in the formwork and voids between them are subsequently injected with a special cementations mixture. TSC has been successfully used in many applications, such as underwater construction, casting concrete sections congested with reinforcement and concrete repair. Coarse aggregate forms about 60% of the total volume of TSC, while coarse aggregate forms about 40% of the total volume of conventional concrete. In TSC stresses are transferred through contact areas between coarse aggregate particles. In this paper coarse aggregate size influence on strength parameters of TSC and comparing it with conventional concrete is done (by uniaxial compressive strength test and Brazilian tensile strength test). According to results of tests in this paper, the TSC with finest grain of coarse aggregate has higher compressive and tensile strength, higher modulus of elasticity and less Poisson’s ratio from conventional concrete.

  • Effect of manufacturing errors of the pad sliding surface on the performance of the hydrodynamic thrust bearing
    • Loukas Zoupas
    • Michał Wodtke
    • Christos Papadopoulos
    • Michał Wasilczuk
    2019 Full text TRIBOLOGY INTERNATIONAL

    In the present study, investigation of the effect of manufacturing errors on the performance of large tilting pad thrust bearings has been performed, following a CFD-based Thermohydrodynamic analysis of a single pad. A 3D model has been generated, including the pad, the lubricant film and the corresponding part of the collar. The pad has been assumed to be deformed about the pivot point, due to thrust loading. Manufacturing errors of different type and amplitude have been superimposed. The equilibrium position of the pad has been calculated by a Newton-Raphson iterative procedure. The principal performance parameters of the bearing (minimum film thickness, friction torque, maximum pressure and temperature) have been calculated. The results demonstrate that manufacturing errors may affect substantially bearing performance, and should be taken into consideration in the design of large tilting pad thrust bearings.

  • Effect of operating conditions on N 2 O production in an anammox sequencing batch reactor containing granular sludge
    • Tiago D. S. Pereira
    • Carla E. D Santos
    • Lu Xi
    • Hussein Al-Hazmi
    • Joanna Majtacz
    • Eduardo C. Pires
    • Márcia H. R.Z. Damianovic
    • Jacek Mąkinia
    2019 WATER SCIENCE AND TECHNOLOGY

    Nitrous oxide (N2O) is one of the gases with the greatest impact in the atmosphere due to its persistence and significant contribution to the greenhouse effect. This study provides an insight into the dynamics of N2O production in wastewater nitrogen removal systems. A 10 L sequencing batch reactor containing enriched anammox biomass was subjected to different operational conditions, i.e., temperature, feed time, NO2 /NH4 þ ratio and the initial concentrations of NH4 þ and NO2 . Tests showed no significant differences in maximum N2O production when the system was operated with a shorter feed time and no increase in the operating temperature. A higher N2O production was observed when the initial NO2 /NH4 þ ratio increased from 1.3 to 1.7 and 1.9. The highest initial concentration of NO2 was linked to an increase in residual N2O at the end of the batch cycle, probably due to heterotrophic denitrifying metabolism

  • Effect Of Resveratrol And Quercetin On Telomerase Regulation In Cancer Cells And Their Anti-Cancer Potential
    • Wioletta Brankiewicz
    2019

    Telomeres and telomerase are nowadays one on targets for anticancer therapy. Telomerase is expressed in ~90% of human cancer cell lines and tumor specimens, whereas its enzymatic activity is not detectable in most human somatic cells. Was found that some dietary compounds can modulate telomerase activity in cancer cells. This review summarizes the current knowledge about the effects of resveratrol and quercetin on telomerase regulation in cancer cells.

  • Effect of selective laser treatment on initiation of fatigue crack in the main part of an undercarriage drag strut
    • Anna Bień
    • Marek Szkodo
    • Jerzy Doberski
    • Bartłomiej Karpiński
    2019 Full text Chinese Journal of Aeronautics

    This paper presents the results of material characterization and a fatigue test conducted for a laser-re-melted drag strut used in an aircraft landing gear. The drag strut was re-melted with a CO2 laser beam. Eight re-melted paths were made in the form of spiral lines along the axis of the drag strut. Next, the drag strut was subjected to variable loads on a testing machine simulating loads occurring when an aircraft lands. The fatigue test showed that the laser-treated drag strut was able to withstand 1700 simulated cycles of landing. This result was 70% better than that obtained for a drag strut with no laser treatment. In order to find the reason for the increase in the number of cycles of simulated landings, tests were carried out using transmission and scanning electron microscopes, a computer microtomograph, an X-ray diffractometer, and a nanoindenter, respectively. Results of the conducted research indicated that the reasons for the increased fatigue life of the laser-treated undercarriage drag strut were both an ultra-fine cellular martensitic microstructure and compressing residual stresses generated during the laser re-melting of the surface layer of the material.

  • Effect of soil moisture on current-carrying capacity of low-voltage power cables
    • Stanisław Czapp
    • Filip Ratkowski
    2019 Full text Przegląd Elektrotechniczny

    One of the factors affecting current-carrying capacity of underground power cables is the thermal resistivity of soil. Its value in the close proximity of the cable is the most important, and for this reason, in some cases, the local soil is replaced with an another soil type or with a cement-sand mixture. The thermal resistivity of the soil is strongly affected by moisture, and in the case of a cement-sand mixture – as tested by the authors – also by this mixture initial water content. The paper presents results of investigation of soil moisture influence on the soil thermal resistivity, and an analysis of the current-carrying capacity of a low-voltage power cable for various soil parameters, in particular its part directly surrounding the cable.

  • Effect of solar radiation on current-carrying capacity of PVC-insulated power cables – the numerical point of view
    • Stanisław Czapp
    • Seweryn Szultka
    • Adam Tomaszewski
    • Agata Szultka
    2019 Full text Tehnicki Vjesnik-Technical Gazette

    Power cables are usually buried in the soil, which results in their relatively high current-carrying capacity. However, there are cases in which the starting/final section of a cable line runs along a pole of an overhead power line. Power cables can be directly exposed to solar radiation then, and this negatively influences their current-carrying capacity as well as estimated life of the cables’ insulation. An analysis of thermal phenomena in PVC-insulated low-voltage power cables, exposed to solar radiation, is conducted in the paper. Current-carrying capacity of an example cable system, for various placements of the cables, is evaluated. The analysis has shown that solar radiation may significantly reduce current-carrying capacity of PVC-insulated cables. A possible method of protection of cables against solar radiation, and its effectiveness, is presented. To investigate the mentioned thermal phenomena, a Computational Fluid Dynamics (CFD) has been used.

  • Effect of Storage Conditions of Rutile Flux Cored Welding Wires on Properties of Welds
    • Aleksandra Świerczyńska
    2019 Full text Advances in Materials Science

    The influence of storage locations of two grades of rutile flux cored welding wires on their surface condition and the strength of the welds made with them were studied. Wires were stored in real urban conditions (Gdańsk and Katowice) for 1 month, simultaneously recording changes in conditions: temperature and relative humidity of the environment. Visual tests of wires in the delivered and stored condition as well as visual and tensile strength tests of welds made with them were carried out. It was found that the surface of the wires underwent more intense degradation (atmospheric corrosion) during storage in Katowice than in Gdańsk. Significant difference in tensile strength was observed only for padding welds made using Gdańsk stored wires. The lowest recorded tensile strength value was not lower than the standard requirements for the wires.

  • Effect of the Catalytic Center on the Electron Transfer Dynamics in Hydrogen-Evolving Ruthenium-Based Photocatalysts Investigated by Theoretical Calculations
    • Magdalena Staniszewska
    • Stephan Kupfer
    • Julien Guthmuller
    2019 Full text Journal of Physical Chemistry C

    The light-induced relaxation pathways in the molecular photocatalyst [(tbbpy)2Ru(tpphz)PtCl2]2+ are investigated with time-dependent density functional theory calculations together with the Marcus theory of electron transfer (ET). The calculations show that metal (Ru) to ligand (tpphz) charge transfer (MLCT) triplet states are populated following an excitation in the longer wavelength range of the absorption spectrum, but that an ET toward the catalytic center (PtCl2) from these states is thermodynamically unfavorable, implying that charge separation can only occur via higher energy states in this system. Moreover, low-lying Pt-centered states can be populated and the calculations predict that they can form an excited state equilibrium with MLCT states localized on the tpphz ligand. A comparison with previously reported results for the photocatalyst [(tbbpy)2Ru- (tpphz)PdCl2]2+, based on a PdCl2 catalytic center, is provided in order to decipher the effect of the catalytic center on their respective photochemistry (Staniszewska, M.; Kupfer, S.; Guthmuller, J. Chem.Eur. J. 2018, 24, 11166−11176).

  • Effect of the North Atlantic Thermohaline Circulation on changes in climatic conditions and river flow in Poland
    • Wrzesiński Dariusz
    • Marsz Andrzej
    • Anna Styszyńska
    • Leszek Sobkowiak
    2019 Full text Water

    : The purpose of this study is to find connections between the North Atlantic Thermohaline Circulation (NA THC), climate elements, such as cloud cover, precipitation, air temperature, sunshine duration, and relative humidity, and flow of rivers in Poland. The intensity of NA THC was characterized by the DG3L index, which was established to assess changes in the amount of heat transported by NA THC along with the transport of water to the Arctic. The paper explains and discusses the mechanism of impact of the NA THC changeability on the elements of the catchment water balance variability. The positive and negative phases of the DG3L index are strongly correlated with the heat anomalies in the upper layer of the North Atlantic waters. The obtained results show that changes of NA THC have significant impact on weather conditions and selected climate elements in Poland. Statistically significant positive correlations were found between the DG3L index and average annual air temperatures, particularly in April, July, and August, while negative between the DG3L index and the total cloud cover. Consequently, in the years with the positive values of the DG3L index, there are favorable conditions for the strong increase in evaporation and evapotranspiration from the ground surface. This has impact on flow of rivers in Poland, which shows considerable regional differences.

  • Effect of the welding environment and storage time of electrodes on the diffusible hydrogen content in deposited metal
    • Jacek Tomków
    • Dariusz Fydrych
    • Grzegorz Rogalski
    • Jerzy Łabanowski
    2019 Full text REVISTA DE METALURGIA

    In the study the glycerin displacement method was used for determination of diffusible hydrogen content in deposited metal. Specimens were welded in the air and in the water with covered rutile electrodes. The first part of the specimens was made immediately after opening the package of the electrodes. The electrodes were then stored in opened packages in laboratory conditions that allowed for contact with the air for three years. After that time, the second part of the samples was made. The results of the measurements of the diffusible hydrogen amount in deposited metal ranged from 32.61 to 39.95 ml/100 g for specimens welded in the air and from 51.50 to 61.34 ml/100 g for specimens made in the water. The statistical analyses were performed in a Statistical software package using the ANOVA module (one-way analysis of variance) with an assumed significance level α = 0.05. The assumption of normality was verified by the Shapiro-Wilk test. The homogeneity of variance was verified by the Levene test. In the next step, post-hoc analyzes were made. The aim was to determine which averages are significantly different. Scheffe, Tukey, NIR Fisher, Newman-Keuls and Duncan tests were used. Possible changes in the diffusible hydrogen content in deposited metal resulting from storage time of electrodes (3 years) were verified by Student’s t-test. All of the statistical analysis shows that the storage time of the electrodes has no significant influence on the diffusible hydrogen content in deposited metal regardless of the welding environment.

  • Effective configuration of a double triad planar parallel manipulator for precise positioning of heavy details during their assembling process
    • Krzysztof Lipiński
    2019 Full text

    In the paper, dynamics analysis of a parallel manipulator is presented. It is an atypical manipulator, devoted to help in assembling of heavy industrial constructions. Few atypical properties are required: small workspace; slow velocities; high loads. Initially, a short discussion about definition of the parallel manipulators is presented, as well as the sketch of the proposed structure. In parallel, some definitions, assumptions and equations are presented for the used multibody methodology. The main part of the paper presents results of the numerical tests performed in order to determinate the best work configuration of the proposed structure. It is verified, that with the initially proposed one, not all of the work requirements are satisfied, mainly about the load distribution. Obtained numerical results are confirmed by some diagrammatic simplified analysis of the load distribution. With the same diagrammatic method, alternative configurations are proposed and verified numerically, next. At the end, final configuration is presented as the one satisfying the requirements.

  • Effective degradation of sulfide ions and organic sulfides in cavitation-based Advanced Oxidation Processes (AOPs)
    • Michał Gągol
    • Reza Soltani
    • Andrzej Przyjazny
    • Grzegorz Boczkaj
    2019 Full text ULTRASONICS SONOCHEMISTRY

    The paper presents the results of investigations on the effectiveness and reaction rate constants of the oxidation of sulfide ions and organic sulfides in real industrial effluents from the production of bitumens (2000 mg S2- L-1) using hydrodynamic and acoustic cavitation. The content of the effluents was analysed in terms carbon disulfide, dimethyl sulfide, and di-tert-butyl disulfide concentration. A possibility of complete oxidation of sulfides by cavitation alone as well as by its combination with external oxidants such as hydrogen peroxide, ozone or peroxone was demonstrated. The oxidation time for the most effective processes is as little as 15 min. Due to the presence of sulfide ions, the effluents from the production of bitumens were oxidized at a strongly alkaline pH. The results of this study reveal the advantage of performing advanced oxidation processes (AOPs) at a basic pH. The effective degradation of sulfide ions enables performance of further degradation of organic contaminants at an acidic pH, ensuring high efficiency of treatment based, for example, on the Fenton reaction without the risk of release of hydrogen sulfide to the atmosphere. The results of this research are applicable to all kinds of caustic effluents for which the lack of possibility of pH adjustment limits their efficient treatment.

  • Effective Formula for Impact Damping Ratio for Simulation of Earthquake-induced Structural Pounding
    • Seyed Khatami
    • Hosein Naderpour
    • Rui Barros
    • Anna Jakubczyk-Gałczyńska
    • Robert Jankowski
    2019 Full text Geosciences

    Structural pounding during earthquakes may cause substantial damage to colliding structures. The phenomenon is numerically studied using different models of collisions. The aim of the present paper is to propose an effective formula for the impact damping ratio, as a parameter of the impact force model used to study different problems of structural pounding under seismic excitations. Its accuracy has been verified by four various approaches. Firstly, for the case of collisions between two structural elements, the dissipated energy during impact has been compared to the loss of kinetic energy. In the second stage of verifications, the peak impact forces during single collision have been analyzed. Then, the accuracy of different equations have been verified by comparing the impact force time histories for the situation when a concrete ball is dropped on a rigid concrete surface. Finally, pounding between two structures during earthquakes has been studied. The results of the analysis focused on comparison between dissipated and kinetic energy show relatively low errors between calculated and assumed values of the coefficient of restitution when the proposed equation is used. In addition, the results of the comparison between experimentally and numerically determined peak impact forces during single collision confirm the effectiveness of the approach. The same conclusion has been obtained for the whole impact time history for collision between a ball and a rigid surface. Finally, the results of the comparative analysis, conducted for pounding between two structures during an earthquake, confirm the simulation accuracy when the proposed approach is used. The above conclusions indicate that the proposed formula for impact damping ratio, as a parameter of impact force model for simulation of earthquake-induced structural pounding, is very effective and accurate in numerical simulations in the case of different scenarios.

  • Effective Friction Angle Of Deltaic Soils In The Vistula Marshlands
    • Kamila Międlarz
    • Jakub Konkol
    • Lech Bałachowski
    2019 Full text Studia Geotechnica et Mechanica

    This article presents the results of laboratory tests on soft, normally consolidated soils from the Vistula Marshlands. Samples of high-plasticity organic soils (muds) taken from 3.2–4.0 m and 9.5–10.0 m depth, as well as peat deposit at 14.0 m, are analysed. Presented case study confirms the applicability of the Norwegian Institute of Technology (NTH) method based on Cone Penetration Tests (CPTU) and allows for a conservative estimation of effective friction angle for muds. The plastification angle equal to 14.5° for organic silt, applied in the modified NTH method, fits well the triaxial test (TX) results. Moreover, the dilative-contractive behaviour according to the CPTU soil classification based on the Robertson’s proposal from 2016 corresponds well with volumetric changes observed in the consolidated drained triaxial compression tests. The internal friction angles of the Vistula Marshlands’ muds and peats are lower in comparison with the database of similar soft soils.

  • Effective yttrium based coating for steel interconnects of solid oxide cells: Corrosion evaluation in steam-hydrogen atmosphere
    • Sebastian Molin
    • Å.h. Persson
    • T.l. Skafte
    • A.l. Smitshuysen
    • S.h. Jensen
    • K. H. Andersen
    • H. Xu
    • Ming Chen
    • Peter Vang Hendriksen
    2019 JOURNAL OF POWER SOURCES

    This work describes manufacture, analysis and test of a new well conducting corrosion-protection coating that can be applied on steel types with high chromium content. Electrolytic deposition of yttrium salts is used to form thin (<100 nm) coatings on both flat steel sheets (material: Crofer 22 APU) and its properties are proven on woven wire-meshes (materials from two different sources: SUS316 and SUS316L). The oxide scale on the coated Crofer 22 APU sheet remains intact after 2000 h operation at 750 °C in H2 with 90% H2O. The corrosion rate at 750 °C of the coated Crofer 22 APU sheets is compared with that of uncoated samples and of samples with a commercial magneton sputtered CGO coating revealing that the coatings reduce the parabolic rate constant characteristic of the corrosion by a factor of 10 and 20 for the CGO and the Y, respectively.

  • Effects of electrophoretic deposition times and nanotubular oxide surfaces on properties of the nanohydroxyapatite/nanocopper coating on the Ti13Zr13Nb alloy
    • Michał Bartmański
    • Andrzej Zieliński
    • Magdalena Jażdżewska
    • Joanna Głodowska
    • Pamela Kalka
    2019 CERAMICS INTERNATIONAL

    Load-bearing implants are developed with a particular emphasis placed on an application of ceramic hydroxyapatite coatings in order, to enhance the bioactivity of titanium implants and to shorten the healing time. Therefore, thin, fully crystalline coatings that are, highly adhesive, hydrophilic and demonstrating antibacterial properties are ly looked for. The aim of this research was to develop and characterize the properties of (nano)hydroxyapatite coatings implemented with nanocopper particles and obtained by the electrophoretic method. The deposition was carried out on the Ti13Zr13Nb alloy, either on a bare surface or a nanotubular oxide layer. The deposition was made for 1 or 2 min. The chemical composition, phase composition, coating structure, homogeneity, thickness, nanoindentation and nanomechanical properties, adhesion determined by a nanoscratch test, and wettability measured by a contact angle were investigated. The presence of nanotubular oxide layers caused no significant change in nanoindentation and nanomechanical propertie and an increase in adhesion strength and a decrease in the contact angle. The increase in deposition time resulted in an increased thickness, a decreased hardness, an increased adhesion strength and wettabilty. The observed effects in the composite (nano)HAp/Cu – (nano)TiO2 coatings are attributed to the change in the structure of coatings following the increasing deposition time and coating thickness.

  • Effects of mechanical stress on electrical arameters and noise of supercapacitors
    • Arkadiusz Szewczyk
    • Łukasz Lentka
    • Janusz Smulko
    2019 Full text

    Results of noise and electrical parameters measurements of prototype electrochemical double layer capacitors (EDLC) are reported at the presence of selected mechanical stress. This issue is of great importance due to future applications in wearable technology. The measurement results are compared, and we may conclude than flicker noise is more sensitive to any stress than other considered electrical parameters.

  • Effects of Na+, K+ and B3+ Substitutions on the Electrical Properties of La10Si6O27 Ceramics
    • Sea-Fue Wang
    • Yung-Fu Hsu
    • Yi-Le Liao
    • Ting-Ting Yang
    • Piotr Jasiński
    2019 JOURNAL OF ELECTRONIC MATERIALS

    Doping of Na and K at La sites and of B at Si site in La10Si6O27 with oxyapatite structure and fabrication of their ceramics were made by the solid-state reaction method. It was found that partial substitution of Na+ and K+ on La sites decreased the sinterability of the La10Si6O27 based ceramics, whereas partial substitution of B3+ on the Si site improved the sinterability. Na+ and K+ substitutions in La10−xNaxSi6O27−x and La10−xKxSi6O27−x can suppress second-phase La2SiO5 formation, and, in this study, as the x value of the two substitutions reached 0.7 and 0.5, respectively, the La2SiO5 phase disappeared. Doping of Na+, K+, and B3+ all displayed the hindering effect of grain growth during sintering. Compositions of La9.3Na0.7Si6O26.3, La9.5K0.5Si6O26.5, and La10Si5.5B0.5O26.75 revealed the highest electrical conductivity in each system. La10Si5.5B0.5O26.75 ceramic sintered at 1575°C showed the highest electrical conductivity at temperatures above 600°C among all the apatite ceramics evaluated. The electrical conductivities of La10Si5.5B0.5O26.75 at 700°C and 800°C reported 0.011 S cm−1 and 0.024 S cm−1, respectively, which are superior or comparable to previous studies, and their activation energies for conduction were calculated to be 0.80 eV.

  • Effects of Na+, K+ and B3+ Substitutions on the Electrical Properties of La10Si6O27 Ceramics
    • Sea-Fue Wang
    • Yung-Fu Hsu
    • Yi-Le Liao
    • Ting-Ting Yang
    • Piotr Jasiński
    2019 ECS Transactions

    Doping of Na and K at La sites and of B at Si site in La10Si6O27 with oxyapatite structure and fabrication of their ceramics were made by solid-state reaction method. It was found that partial substitution of Na+ and K+ on La sites decreased the sinterability of the La10Si6O27 based ceramics, whereas partial substitution of B3+ on Si site imporved the sinterability. Na+ and K+ substitutions in La10-xNaxSi6O27-x and La10-xKxSi6O27-x were found to suppress second-phase La2SiO5 formation. La10Si5.5B0.5O26.75 ceramic sintered at 1575ºC showed the highest electrical conductivity at temperatures above 600ºC among all the apatite ceramics evaluated. The electrical conductivities of La10Si5.5B0.5O26.75 at 700ºC and 800ºC reported 0.011 and 0.024 S cm-1, respectively, which are superior or comparable to previous studies, and their activation energies for conduction were calculated to be 0.80 eV.

  • Effects of n-butanol presence, inlet loading, empty bed residence time and starvation periods on the performance of a biotrickling filter removing cyclohexane vapors from air
    • Piotr Rybarczyk
    • Bartosz Szulczyński
    • Milena Gospodarek
    • Jacek Gębicki
    2019 Full text CHEMICAL PAPERS

    This paper presents the results of investigations on the removal of cyclohexane vapors from air using a peat-perlite packed biotrickling filter. Effects of basic process parameters i.e. IL (inlet loading) and EBRT (empty bed residence time) as well as introduction of n-butanol to the treated air stream and starvation periods on the process performance were evaluated. The results show that the introduction of hydrophilic n-butanol results in an enhanced removal of hydrophobic cyclohexane comparing to the experiments where only cyclohexane was treated. Additionally, the biotrickling filter performance after the starvation events is regained to more extent for mixed system than for the single cyclohexane. A novel and interesting element of the paper is the application of an electronic nose for the process monitoring. Obtained results are discussed in the perspective of an influence of the presence of a compound with different affinity to aqueous phase on the removal efficiency of the compound with opposite chemical properties.

  • Effects of Road Infrastructure on Pedestrian Safety
    • Marcin Budzyński
    • Lucyna Gumińska
    • Kazimierz Jamroz
    • Tomasz Mackun
    • Piotr Tomczuk
    2019 Full text IOP Conference Series: Materials Science and Engineering

    The objective of the work was to identify risks for pedestrians that involve road infrastructure and roadside and to define how selected elements of geometry and traffic layout affect driver behaviour (speed on approaching pedestrian crossings). The results have helped to formulate recommendations on pedestrian crossing design. The research included an analysis of 2013-2017 statistics to identify the circumstances and causes of pedestrian accidents. Field work at about 2,000 unsignalized pedestrian crossings was the basis for assessing the safety of these crossings. Assessment criteria were selected and a safety classification was made with specific recommendations made for possible treatments. More field work was designed to measure speeds near pedestrian crossings in three cases: no pedestrians in the crossing area, a pedestrian is approaching a crossing, a pedestrian is waiting to cross the road. The study was conducted in different areas (city, transit roads passing through small towns, non-built-up areas) for different cross-sections (one carriageway and two lanes –1x2, two carriageways with two or three lanes each –2x2, 2x3, one carriageway and four lanes –1x4). The study also looked at speed limits –50 and 70 km/h. The share of drivers giving way to pedestrians waiting to cross was also assessed. Pedestrians were surveyed and asked about how safe they feel crossing the road. The survey also asked drivers about driver behaviour and use of speed management measures.Statistical analyses show the circumstances and causes of pedestrian accidents

  • Efficiency and proportions of waste tyre pyrolysis products depending on the reactor type—A review
    • Witold Lewandowski
    • Katarzyna Januszewicz
    • Wojciech Kosakowski
    2019 Full text JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS

    This article discusses the current use of different pyrolytic reactors, their constructions and operating principles regarding the yields of main products of waste tyre pyrolytic recycling. Whether one makes a larger or smaller profit, or even a loss due to a surcharge being levied on waste tyre recycling, depends on the sale of the pyrolysis products (gas, char, oil), the proportions and market prices of which differ. The cheapest is gas, which can be used as a source of technological heat of energetically self-sufficient pyrolysis or after purification, can be burned in a boiler and converted into heat or electricity. Raw char is not expensive either. It requires upgrading and then, as carbon black, can be re-used for the production of tyres or in the form of improved carbon can be used as an absorber or catalyst. The most expensive is oil, containing mainly aromatic compounds, on the condition that it will not be burned as diesel or liquid fuel. Hence, the oil yields obtained in various types of pyrolysers are given. This review of pyrolysis reactors is organised according to the criterion of charge movement in the reactor and the means of bringing this about. Depending on the method and speed of movement of the load in reactors, they are classified as fixed-bed and movable-bed reactors. The latter group is subdivided, depending on the method of inducing this movement, into pneumatic (bubbling, spouted, circulating or transport fluidised beds), mechanical (rotary kiln, rake, auger, ablative, stirred) reactors and reactors in which the charge moves under gravity. This review focuses on the construction and operating principles of the reactors and the yields of the products of pyrolytic thermal decomposition of scrap tyres. The summary and comparison of main product yields (oil/ gas/coal) obtained in different reactors and by different authors, presented in graphical and tabular form, constitute a summary and supplement to this work.

  • Efficient Finite Element Analysis of Axially Symmetrical Waveguides and Waveguide Discontinuities
    • Małgorzata Warecka
    • Rafał Lech
    • Piotr Kowalczyk
    2019 Full text IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES

    A combination of the body-of-revolution and finite element methods is adopted for full-wave analysis of waveguides and waveguide discontinuities involving angular field variation. Such an approach is highly efficient and much more flexible than analytical techniques. The method is performed in two different cases: utilizing a generalized impedance matrix to determine the scattering parameters of a single waveguide section and utilizing periodic boundary conditions without sources. In order to confirm the validity and efficiency of both approaches, a few examples of axially symmetrical structures have been analyzed. The obtained results are compared to those obtained from commercial software and available in the literature.

  • Efficient Gradient-Based Algorithm with Numerical Derivatives for Expedited Optimization of Multi-Parameter Miniaturized Impedance Matching Transformers
    • Sławomir Kozieł
    • Anna Pietrenko-Dąbrowska
    2019 Full text RADIOENGINEERING

    Full-wave electromagnetic (EM) simulation tools have become ubiquitous in the design of microwave components. In some cases, e.g., miniaturized microstrip components, EM analysis is mandatory due to considera¬ble cross-coupling effects that cannot be accounted for otherwise (e.g., by means of equivalent circuits). These effects are particularly pronounced in the structures in¬volving slow-wave compact cells and their numerical opti¬mization is challenging due to expensive simulations and large number of parameters. In this paper, a novel gradi¬ent-based procedure with numerical derivatives is pro¬posed for expedited optimization of compact microstrip impedance matching transformers. The method restricts the use of finite differentiation which is replaced for se¬lected parameters by a rank-one Broyden updating for¬mula. The usage of the formula is governed by an ac¬ceptance parameter which is made dependent on the pa¬rameter space dimensionality. This facilitates handling circuits of various complexities. The proposed approach is validated using three impedance matching transformer circuits with the number of parameters varying from ten to twenty. A significant speedup of up to 50 percent is demon¬strated with respect to the reference algorithm.

  • Efficient synthesis and antifungal investigation of nucleosides’ quaternary ammonium salt derivatives
    • Barbara Dmochowska
    • Lucyna Pellowska-Januszek
    • Justyna Samaszko
    • Rafał Ślusarz
    • Roland Wakieć
    • Janusz Madaj
    2019 Full text TURKISH JOURNAL OF CHEMISTRY

    Quaternary ammonium salts are a group of compounds with diverse biological properties, the most important of which are their antiviral, antibacterial, and antifungal activities. The quaternization reactions of 5'-O-tosyl derivatives of uridine and thymidine with triethylamine, trimethylamine, 4-(N ,N -dimethylamino)pyridine, 2-methylpyridine, and pyridine are described in this article. Two of the synthesized compounds are exceptional because they are first of this type that demonstrate concentration-dependent antifungal in vitro activity against two species of the genus Candida in minimal YNB-SG medium. The experimental results have been extended by adding full atom molecular dynamics simulations and substrates and products energies evaluation.

  • Ekonometryczna analiza konsumpcji w Polsce w latach 1995-2018- statyczne modele wydatków konsumpcyjnych w wartościach nominalnych
    • Jerzy Ossowski
    2019 Full text Przestrzeń Ekonomia Społeczeństwo

    W artykule przeprowadzono badania makroekonomicznych związków pomiędzy konsumpcją globalną (C) a produktem krajowym brutto (PKB). W części teoretycznej artykułu: • zdefiniowano postacie analityczne przyczynowo-skutkowych makromodeli konsumpcji, • sformułowano interpretację mierników opisujących badane zależności, • sformułowano założenia stochastyczne dla rozważanych makromodeli konsumpcji, W części empirycznej artykułu: • przeprowadzono analizę i interpretację danych statystycznych oraz podstawowych mierników charakteryzujących makroekonomiczne procesy konsumpcji w Polsce w latach 1995-2018, • oszacowano parametry strukturalne proponowanych wersji modeli, • przeprowadzono weryfikację oszacowanych wersji modeli, • zinterpretowano oszacowane i zweryfikowane mierniki. Ostatecznie w stosunku do konsumpcji ogółem (CON) oraz konsumpcji gospodarstw domowych (CN) wykazano, że w gospodarce polskiej w latach 1995-2018: • z każdego dodatkowego miliarda nominalnego produktu krajowego brutto (PKBN) społeczeństwo przeznaczało na konsumpcję ogółem (CON) około 0,744 miliarda złotych z przeciętnym błędem wynoszącym 0,034 miliarda złotych. • z każdego dodatkowego miliarda nominalnego produktu krajowego brutto (PKBN) gospodarstwa domowe przeznaczały na swoją indywidualną konsumpcję (CN) około 0,574 miliarda złotych z przeciętnym błędem wynoszącym 0,029 miliarda złotych.

  • Ekspertyza dotycząca wpływu tlenków żelaza na nowy rurociąg ze stali nierdzewnej gat. 1.4307 podwieszany pod mostem stalowym nad rzeką Wisłą, który jest połączony z dwóch stron z magistralą wodociągową wykonaną z rur z żeliwa szarego.
    • Łukasz Gaweł
    2019

    Przedmiotem niniejszej umowy jest dokonanie oceny wpływu na nowy rurociąg ze stali nierdzewnej (1.4307), związków żelaza rozpuszczonych w wodzie oraz związków żelaza odłożonych w starych przewodach z żeliwa szarego, a które to związki przemieszczają się pod wpływem zmian kierunku przepływu wody oraz uderzeń hydraulicznych. Ponadto przedmiot stanowi ocena wpływu produktów korozji na stan stali nierdzewnej i układu żeliwo/stal nierdzewna.

  • Elastic Fender-Dolphin Interaction for Economic Design of Berthing Dolphins
    • Waldemar Magda
    2019 JOURNAL OF WATERWAY PORT COASTAL AND OCEAN ENGINEERING-ASCE

    The study addresses the question of the possible design benefits when considering the interaction between a modern marine modular rubber fender and a steel tubular pile substructure of a berthing dolphin. Absorption of the berthing kinetic energy of the vessel by a dualelasticity pile-fender berthing system is described in detail using the interactive treatment method (ITM). Application of the ITM is illustrated by a calculative example, assuming a 37,700 deadweight ton (DWT) tanker as a berthing ship, realistic geometries of large-diameter steel piles of the berthing dolphin substructure, and a family of Sumitomo Pi-type modular rubber fender units. By splitting the berthing kinetic energy into two parts absorbed by two elastic component elements of the dual-elasticity system of the berthing dolphin, the ITM is an effective tool for proper selection of the minimum required size (i.e., outside diameter and wall thickness) of steel piles of the berthing dolphin substructure in relation to the size of fender unit assumed. Finally, using ITM, an example analysis is performed to illustrate the influence of fender size selection on the berthing force, and the mass and stiffness of the steel-pile substructure of the berthing dolphin, as meaningful parameters influencing the most economical solution in the berthing dolphin design.

  • Elastic scattering of electrons from chloroform
    • Borna Hlousek
    • M. F. Martin
    • Murtadha Khakoo
    • Mateusz Zawadzki
    • G. M. Moreira
    • L. S. Maioli
    • Marcio Bettega
    • L Machado
    • V. A. S. da Mata
    • A. J. da Silva
    • I Iga
    • M-T Lee
    • M Homem
    2019 Full text PHYSICAL REVIEW A

    We present experimental and theoretical cross sections for elastic electron scattering from CHCl3. This is an important target because of its relevance to environmental chemistry and the plasma etching industry as a source of chlorine radicals. The experimental results were obtained at incident electron energies ranging from 0.5 to 800 eV in the 10deg-130deg scattering angle range. Theoretically, the scattering cross sections in the low-energy region were obtained by using the Schwinger multichannel method with pseudopotentials in the static-exchange plus polarization approximation. Additionally, in the low- and intermediate-energy ranges, theoretical calculations were also performed using a molecular complex optical potential and a single-center expansion method combined with Padé approximation. Further calculations using the independent atom model were also made at intermediate energies. Momentum-transfer cross sections were derived by integrating the differential cross sections. In general, there is a good agreement between the experimental data and the theoretical results. Moreover, the calculations reveal the presence of three shape resonances in the elastic channel, located at 0.5, 2, and 8 eV. The two higher-lying resonances were confirmed by the present experiments, whereas the positions of the two lower-lying resonances agree well with previous results of electron attachment experiments.

  • Electrical properties of organic and perovskite systems used in solar cells
    • Damian Głowienka
    2019 Full text

    Nowadays, a great progress in the areas of molecular and hybrid photovoltaics is observed. The devices based on organic and perovskite materials are getting attention mostly due to their low cost production process. However, their efficiency and stability are still lower than for inorganic materials which make them less popular. Therefore, a detailed understanding of the device physics is fundamental for organic and perovskite solar cells. The goal of this thesis is to understand which processes influence the electrical properties of both types of solar cells. Here, numerical and experimental techniques are used to accurately determine and understand electrical phenomena taking place in both photovoltaic cells. The special attention is paid to different effects, including excitonic processes, interface phenomena or recombination mechanisms which affect the photovoltaic parameters. The results of the thesis should help in further development of aforementioned solar cells.

  • Electrochemical behavior of a composite material containing 3D-structured diatom biosilica
    • Andrzej Nowak
    • Myroslav Sprynskyy
    • Weronika Brzozowska
    • Anna Lisowska-Oleksiak
    2019 Full text Algal Research-Biomass Biofuels and Bioproducts

    3D-structured diatom biosilica mixed with conducting carbon black was investigated as an active electrode material for lithium-ion batteries. Diatom biosilica was obtained by cultivation of the selected diatom species under laboratory conditions. Several instrumental techniques (XRD, FTIR, Raman, SEM-EDX, TGA) were used to characterize the physicochemical properties of applied biosilica. It was evidenced that the prepared new composite material has a significant impact on the electrochemical properties of the electrode. The ratio 1:1 of biosilica and carbon black exhibited a specific capacity of 400 ± 9 mAh/g over 90 cycles. Such a ratio ensured proper electric contact between biosilica particles. The specificity of the faradaic process suggests that biosilica-based electrodes might be suitable in large-scale energy storage applications.

  • Electrochemical capacitor temperature fluctuations during charging/discharging processes
    • Stanisław Galla
    • Arkadiusz Szewczyk
    • Łukasz Lentka
    2019 Full text Metrology and Measurement Systems

    Thepaperpresentsaproposalofusingadditionalstatisticalparameterssuchas:standarddeviation,variance, maximum and minimum increases of the observed value that were determined during measurements of temperature fields created on the surface of the tested electrochemical capacitor. The measurements were carriedoutusingthermographicmethodsinordertosupportassessmentoftheconditionofelectrochemical capacitorunderclassicdurabilitytestsbasedonmethodsofdeterminationofcapacityandequivalentseries resistance.Thepossibilityofusingsomestatisticalparametersinassessmentoftheelectrochemicalcapacitor quality was illustrated. The applied measurement methodology and the results of research associated with the classic methods of supercapacitors’ assessment are presented. The obtained results indicate that the variabilityofsomestatisticalparametersoftemperaturefieldscanbedirectlyrelatedtochangingthevalues of standard parameters describing electrochemical capacitor, which are capacitance and equivalent series resistance.

  • Electrochemical degradation of textile dyes in a flow reactor: effect of operating conditions and dyes chemical structure
    • A Pieczyńska
    • Tadeusz Ossowski
    • Robert Bogdanowicz
    • E.m. Siedlecka
    2019 Full text International Journal of Environmental Science and Technology

    In this study, electrochemical oxidation of five azo dyestuffs (Yellow D-5GN, Red D-B8, Ruby F-2B, Blue D-5RN, Black DN), that are widely used in the textile industry, was investigated in a flow reactor. BDD electrode with a high boron doping level (C/B = 10 000) was prepared and used. Two configurations of reactor were considered, i.e., one with the undivided cell, and the other with the cell divided by anodic and cathodic compartments. The effect of current density and the initial pH of the solution on the dyestuff degradation process was investigated. As expected, higher degradation rate was found for higher current density, while the effect of pH was marginal. Next, electrochemical oxidation of azo dyestuffs with different chemical structures was investigated. Based on the cyclic voltammetry measurements, the correlation between the dyestuff removal rate and the oxidation potential value of dyestuff was found. These results suggest that the direct oxidation of dyestuffs at the highly doped BDD anode plays a significant role in the electrochemical oxidation. Finally, the electrochemical removal of dyestuffs was carried out in two types of dyeing baths. The dyeing bath composition has a significant effect on the degradation efficiency. Chlorides in F-type dyeing bath accelerated electrochemical removal due to effective generation of Cl2/HOCl at the highly B-doped BDD anode. In contrast, OH− inhibited the D-type dyestuff removal from dyeing bath, because they acted as scavengers of ·OH radicals. Highly B-doped BDD anode is promising material to F-type dyestuff treatment in industrial wastewater.

  • Electrochemical performance of indium-tin-oxide-coated lossy-mode resonance optical fiber sensor
    • Paweł Niedziałkowski
    • Wioleta Białobrzeska
    • Dariusz Burnat
    • Petr Sezemsky
    • Vitezslav Stranak
    • Harm Wulff
    • Tadeusz Ossowski
    • Robert Bogdanowicz
    • Marcin Koba
    • Mateusz Śmietana
    2019 SENSORS AND ACTUATORS B-CHEMICAL

    Analysis of liquids performed in multiple domain, e.g., optical and electrochemical (EC), has recently focus significant attention. Our previous works have shown that a simple device based on indium-tin-oxide (ITO) coated optical fiber core may be used for optical monitoring of EC processes. At satisfying optical properties and thickness of ITO a lossy-mode resonance (LMR) effect can be obtained and used for monitoring of optical properties of an analyte in proximity of the ITO surface. However, EC response of the ITO-LMR device to a redox probe has not been achieved for ITO-LMR sensor whereas it is generally observed for commercially available ITO electrodes. The changes in the response to a redox probe are typically used as a sensing parameter when EC label-free sensing is considered, so it is crucial for further development of combined LMR-EC sensing concept. In this work, we focus on enhancing the EC activity of the device by tuning ITO magnetron sputtering deposition parameters. Influence of the deposition pressure on the ITO properties has been the main consideration. Both optical and EC readouts in 0.1 M KCl containing such redox probes as 1 mM of K3[Fe(CN)6] or 1 mM 1,1′-Ferrocenedimethanol were discussed at different scan rate. The performed studies confirm that for optimized ITO properties the ITO-LMR sensor used as the EC electrode may also show excellent EC performance. The observed EC processes are quasi-reversible and diffusion-controlled. Moreover, for the devices, which offer improved EC response, an optical monitoring of the EC process is also possible. According to our best knowledge, fully functional combined optical and EC sensor, where optical effect is resonance-based and other than well-known surface plasmon resonance, is presented for the first time.

  • Electrochemical properties of porous Sr0.86Ti0.65Fe0.35O3 oxygen electrodes in solid oxide cells: Impedance study of symmetrical electrodes
    • Aleksander Mroziński
    • Sebastian Molin
    • Jakub Karczewski
    • Tadeusz Miruszewski
    • Piotr Jasiński
    2019 Full text INTERNATIONAL JOURNAL OF HYDROGEN ENERGY

    This work evaluates porous Sr0.86Ti0.65Fe0.35O3 (STF35) as a possible oxygen electrode material for Solid Oxide Cells. The powder synthesis was performed by solid state method. Characterization included DC electrical conductivity study of sintered bulk samples and impedance spectroscopy study of symmetrical electrodes deposited on gadolinium doped ceria substrates. Measurements were carried out in atmospheres with different pO2 levels: 0.1%–20% O2. Detailed equivalent circuit analysis was carried out in order to clarify the reaction pathway on porous electrode, which extends knowledge available for dense model electrodes. At 800 °C in 21% O2, the DC electrical conductivity of STF35 pellet was 0.6 S cm−1 and the polarization resistance of the electrode in the symmetrical cell was ∼100 mΩ cm2. Detailed impedance spectroscopy studies revealed that the largest contribution (∼80%) towards the polarization resistance is due to oxygen adsorption, which is limiting the oxygen reduction performance of the porous STF35 electrode. These results show the applicability of advanced impedance analysis methods (e.g. Distribution of Relaxation Times - DRT) for description of complex impedance electrode phenomena of porous electrodes.

  • Electrochemical simulation of metabolism for antitumor-active imidazoacridinone C-1311 and in silico prediction of drug metabolic reactions
    • Agnieszka Potęga
    • Dorota Żelaszczyk
    • Zofia Mazerska
    2019 Full text JOURNAL OF PHARMACEUTICAL AND BIOMEDICAL ANALYSIS

    The metabolism of antitumor-active 5-diethylaminoethylamino-8-hydroxyimidazoacridinone (C-1311) has been investigated widely over the last decade but some aspects of molecular mechanisms of its metabolic transformation are still not explained. In the current work, we have reported a direct and rapid analytical tool for better prediction of C-1311 metabolism which is based on electrochemistry (EC) coupled on-line with electrospray ionization mass spectrometry (ESI-MS). Simulation of the oxidative phase I metabolism of the compound was achieved in a simple electrochemical thin-layer cell consisting of three electrodes (ROXYTM, Antec Leyden, the Netherlands). We demonstrated that the formation of the products of N-dealkylation reactions can be easily simulated using purely instrumental approach. Newly reported products of oxidative transformations like hydroxylated or oxygenated derivatives become accessible. Structures of the electrochemically generated metabolites were elucidated on the basis of accurate mass ion data and tandem mass spectrometry experiments. In silico prediction of main sites of C-1311 metabolism was performed using MetaSite software. The compound was evaluated for cytochrome P450 1A2-, 3A4-, and 2D6-mediated reactions. The results obtained by EC were also compared and correlated with those of reported earlier for conventional in vitro enzymatic studies in the presence of liver microsomes and in the model peroxidase system. The in vitro experimental approach and the in silico metabolism findings showed a quite good agreement with the data from EC/ESI-MS analysis. Thus, we conclude here that the electrochemical technique provides the promising platform for the simple evaluation of drug metabolism and the reaction mechanism studies, giving first clues to the metabolic transformation of pharmaceuticals in the human body.

  • Electrochemical Stability of Few-Layered Phosphorene Flakes on Boron-Doped Diamond: A Wide Potential Range of Studies in Aqueous Solutions
    • Anna Dettlaff
    • Grzegorz Skowierzak
    • Łukasz Macewicz
    • Michał Sobaszek
    • Jakub Karczewski
    • Mirosław Sawczak
    • Jacek Ryl
    • Tadeusz Ossowski
    • Robert Bogdanowicz
    2019 Full text Journal of Physical Chemistry C

    Two-dimensional phosphorene has attracted great interest since its discovery as a result of its extraordinary properties. Two-dimensional single crystals of phosphorene can be useful for electrochemical (EC) sensing applications due to their enhanced surface-to-volume ratio. We proposed to investigate the electrochemical performance of phosphorene deposited directly on boron-doped diamond (BDD) electrodes. Noncovalent interaction of phosphorene with BDD was achieved due to van der Waals interactions. This extends the potential range of EC studies in aqueous solutions due to the extraordinary wide range of the BDD potential window (−2 to 2.5 V vs Ag|AgCl|3M KCl). Cyclic voltammetry studies demonstrated irreversible electrochemical oxidation of the phosphorene, with peaks observed at different potentials depending on the sonication power during the liquid exfoliation of black phosphorus (BP). This indicated the formation of polyphosphoric quasi-oxide layers with undefined oxidation states of phosphorus. Electrochemical impedance spectroscopy showed the second time constant for high power sonicated BP, which was attributed to PxOy(OH)z formation. The subsequent film was responsible for limiting the charge transfer rate. The BDD enabled the EC behavior of phosphorene to be studied at high anodic potentials.

  • Electrodes array for contactless ECG measurement of a bathing person - a sensitivity analysis
    • Kamil Osiński
    • Adam Bujnowski
    • Piotr Przystup
    • Jerzy Wtorek
    2019 Full text

    An applicability of a remote (contactless) electrocardiogram (ECG) measurements in a bathtub is presented in the paper. Possibility of ECG measurements in shallowly filled tube with a water was examined. A bathing person was, both, sitting and lying during experiments performed. The problem became non-trivial when the bathing person was moving in reference to a fixed set of electrodes and located at the longer walls of the bathtub. However, the results obtained indicate that the sensitivity of a developed electrode array could enable such measurements. However, a spatial sensitivity distribution determines, both, the recorded ECG signal parameters and quality.

  • Electromagnetic plane wave scattering from a cylindrical object with an arbitrary cross section using a hybrid technique
    • Piotr Kowalczyk
    • Rafał Lech
    • Małgorzata Warecka
    • Adam Kusiek
    2019 Full text JOURNAL OF ELECTROMAGNETIC WAVES AND APPLICATIONS

    A hybrid technique combining finite-element and mode-matching methods for the analysis of scattering problems in open and closed areas is presented. The main idea of the analysis is based on the utilization of the finite-element method to calculate the post impedance matrix and combine it with external excitation. The discrete analysis, which is the most time- and memory-consuming, is limited here only to the close proximity of the scatterer. Moreover, once the impedance matrix is calculated, any rotation or shifting of the post can be performed without the need for structure recalculation. All the obtained results have been verified by comparison with simulations performed using the hybrid finite-difference-modematching method and commercial software.

  • Electromagnetic-based derivation of fractional-order circuit theory
    • Tomasz Stefański
    • Jacek Gulgowski
    2019 Full text Communications in Nonlinear Science and Numerical Simulation

    In this paper, foundations of the fractional-order circuit theory are revisited. Although many papers have been devoted to fractional-order modelling of electrical circuits, there are relatively few foundations for such an approach. Therefore, we derive fractional-order lumped-element equations for capacitors, inductors and resistors, as well as Kirchhoff’s voltage and current laws using quasi-static approximations of fractional-order Maxwell’s equations. The proposed approach is not limited by the geometry of the considered lumped elements and employs the concepts of voltage and current known from the circuit theory. Finally, the proposed theory of circuit elements is applied to interpretation of Poynting’s theorem in fractional-order electromagnetism.

  • Electron collisions with X(CH3)4 molecules (X = C, Si, Ge)
    • Sylwia Stefanowska-Tur
    • Paweł Możejko
    • Elżbieta Ptasińska-Denga
    • Czesław Szmytkowski
    2019 Full text JOURNAL OF CHEMICAL PHYSICS

    Absolute grand-total cross sections (TCSs) for electron scattering from tetramethylmethane [C(CH3)4], tetramethylsilane [Si(CH3)4], and tetramethylgermane [Ge(CH3)4] molecules have been measured at electron-impact energies extending from around 0.5 to 300 eV in the linear electron-transmission experiment. The measured TCS energy dependences show very pronounced broad enhancement, peaking near 5.5 eV for Si(CH3)4 and Ge(CH3)4 molecules and around 6.5 eV for C(CH3)4. Additional weak structures are also located at higher electron energies. We attributed the TCS features to the resonant processes involved in the electron–molecule scattering. To examine the role of permethylation in the scattering, the measured TCS energy functions for X(CH3)4 compounds (X = C, Si, Ge) have been compared to the TCS curves for XH4 molecules. Additionally, the integral elastic cross section (ECS) and ionization cross section (ICS) have been calculated from intermediate to high electron-impact energies using model methods. At energies above 50 eV, the sum of ECS and ICS for the investigated targets is in satisfactory agreement with the respective measured TCS. The computed ECS+ICS values can be used as rough estimation of TCS at energies above 300 eV.

  • Electron energy-loss spectroscopy of excited states of the diazine molecules: Pyridazine
    • Ireneusz Linert
    • Mariusz Zubek
    2019 JOURNAL OF ELECTRON SPECTROSCOPY AND RELATED PHENOMENA

    Excitation of the valence electronic states of the pyridazine molecules in the gas phase have been studied using the technique of electron energy-loss spectroscopy. Varying the electron scattering conditions, the residual electron energy and scattering angle, enabled the optically-allowed and -forbidden excitations to be differentiated. The measured energy-loss spectra enabled the vertical excitation energies of the observed states to be determined and tentative assignments for them to be obtained. Comparison of the available vertical excitation energies of the correlating triplet and singlet states of the diazine molecules, pyridazine, pyrimidine and pyrazine, allowed systematic trends in the energy shifts to be determined.

  • Electron scattering from tin tetrachloride (SnCl4) molecules
    • Paweł Możejko
    • Sylwia Stefanowska-Tur
    • Elżbieta Ptasińska-Denga
    • Czesław Szmytkowski
    2019 Full text JOURNAL OF CHEMICAL PHYSICS

    Absolute grand-total cross section (TCS) for electron scattering from a tin tetrachloride, SnCl4, molecule was measured at electron-impact energies ranging from 0.6 to 300 eV, in the linear electron-transmission experiment. The measured TCS energy dependence shows two very pronounced enhancements peaking near 1.2 eV and around 9.5 eV, separated with a deep minimum centered close to 3 eV. The low energy structure is attributed to the formation of two short-living negative ion states. Additional weak structures in the TCS curve are also perceptible. We also calculated the integral elastic and ionization cross sections for SnCl4 up to 4 keV within the additivity rule approximation and the binary-encounter-Bethe approach, respectively. To examine the role of the central atom of tetrachloride target molecules in collisions with electrons, we compared the experimental TCS energy functions for XCl4 molecules (X = C, Si, Ge, Sn).

  • Electronic Noses in Medical Diagnostics
    • Wojciech Wojnowski
    • Tomasz Dymerski
    • Jacek Gębicki
    • Jacek Namieśnik
    2019 CURRENT MEDICINAL CHEMISTRY

    Electronic nose technology is being developed in order to identify aromas in a way parallel to the biologic olfaction. When applied to the field of medicine, such device should be able to identify and discriminate between different diseases. In recent years this kind of approach finds application in medical diagnostics, and especially in disease screening. Despite the fact that devices utilizing chemical sensor arrays are not routinely used in everyday medical practice, their prospective use would solve some established issues in healthcare. It would also find application in prophylactics by facilitating a widespread deployment of screening tests. In this review the comprehensive summary of research in medical diagnostics using electronic noses is presented. A special attention has been paid to application of these devices and sensor technologies, in response to current trends in medicine.

  • Electrophoretic co-deposition of Fe2O3 and Mn1,5Co1,5O4: Processing and oxidation performance of Fe-doped Mn-Co coatings for solid oxide cell interconnects
    • E Zanchi
    • B Talic
    • A Sabato
    • Sebastian Molin
    • A Boccaccini
    • F Smeacetto
    2019 JOURNAL OF THE EUROPEAN CERAMIC SOCIETY

    The “in-situ” Fe-doping of the manganese cobalt spinel was achieved by electrophoretic co-deposition of Mn1,5Co1,5O4 and Fe2O3 powders followed by a two-step reactive sintering treatment. The effects on the coating properties of two different Fe-doping levels (5 and 10 wt.% respectively) and two different temperatures of the reducing treatment (900 and 1000 °C) are discussed. Samples with Fe-doped coatings demonstrated a lower parabolic oxidation rate and thinner oxide scale in comparison with both the undoped Mn1,5Co1,5O4 spinel coating and bare Crofer 22 APU. The best corrosion protection was achieved with the combined effect of Fe-doping and a higher temperature of the reducing step at 1000 °C.